Risk Factors Associated With Grade 3 Pivot Shift After Acute Anterior Cruciate Ligament Injuries

Subjective grade of apprehension during the pivot-shift test reflects patient-reported outcomes more than conventional pivot-shift test grade after ACL reconstruction

PURPOSE

To investigate whether the pivot-shift test reflects patient-reported outcomes 1 year after anterior cruciate ligament (ACL) reconstruction based on a multicentre prospective cohort study.

METHODS

This study included patients who underwent primary ACL reconstruction using the hamstring tendons. The pivot-shift test grades were determined according to the International Knee Documentation Committee (IKDC) form as 0, 1+, 2+ or 3+. In addition, patients' subjective apprehension during the pivot-shift test were classified as 0 (no-apprehension), 1+ (mild-apprehension), 2+ (moderate-apprehension) or 3+ (severe-apprehension). In this study, a positive pivot-shift test was defined as grade 1+ or higher.

RESULTS

A total of 837 patients were enroled in this study. One year postoperatively, there was no significant difference in the Knee injury and Osteoarthritis Outcome Score (KOOS), IKDC score, Lysholm knee scale and Tegner activity scale between the positive (118 patients) and negative (719 patients) groups of the conventional IKDC grading of the pivot-shift test. However, when divided into two groups based on the apprehension grading of the pivot-shift test after surgery, the postoperative scores were significantly lower in the apprehension-positive group (114 patients) than those in the apprehension-negative group (723 patients) on the Tegner activity scale and KOOS Symptom, Sports/Rec and Quality of Life subscales.

CONCLUSIONS

Patients' subjective apprehension during the pivot-shift test after ACL reconstruction was significantly associated with the postoperative Tegner activity scale and three subscales of the KOOS. However, there was no association between the conventional IKDC grading of the pivot-shift test and any patient-reported outcomes postoperatively.

LEVEL OF EVIDENCE

Level II.

Steep medial posterior tibial slope angle and ramp lesion are independent risk factors for an increase in quantitatively measured pivot shift in patients with ACL-deficient knees

Background

Delayed anterior cruciate ligament (ACL) reconstruction often causes residual anterolateral rotatory instability (ALRI) and consequent knee osteoarthritis, warranting the recommendation of early ACL reconstruction within 6 months after injury. Nonetheless, some cases show notable instability, even shortly after injury. The purpose of this study was to identify risk factors for an increase in quantitatively measured pivot shift in patients with ACL-deficient knees within 6 months after injury.

Methods

Patients with primary ACL reconstruction within 6 months after injury and quantitative triaxial accelerometer measurements of preoperative pivot shift were included. Descriptive statistics were calculated for 11 independent variables (age, gender, time from injury to surgery, KT-1000, knee extension angle, lateral and medial posterior tibial slope angle, medial and lateral meniscus tears, ramp lesion and Tegner active scale). A single regression analysis was performed on the 11 items and acceleration during the pivot shift, and a multiple regression analysis was performed for items with p value less than 0.1.

Results

Overall, 111 patients met the inclusion criteria. Single regression analysis showed that medial posterior tibial slope angle, medial meniscus tear and ramp lesion were significantly correlated with acceleration during the pivot shift (p < 0.001, p = 0.04 and p = 0.001). Multiple regression analysis identified medial posterior tibial slope angles and ramp lesions as independent factors for increased preoperative pivot shift (p = 0.005 and 0.01).

Conclusion

A steep medial posterior tibial slope angle and ramp lesion were independent risk factors for increased quantitatively measured pivot shift in patients with ACL-deficient knees.

Level of Evidence

Level IV, case series study.

Lateral Extra-Articular Tenodesis and Anterolateral Procedures

The treatment of rotational instability has been an intriguing challenge since the era of modern anterior cruciate ligament (ACL) surgery. Lateral extra-articular procedures (LEAPs) have emerged as a solution to this problem, particularly in high-risk populations. Several studies have shown significant benefits of combining LEAPs with ACL reconstruction, including reduced graft failure rates, improved knee stability, improved rotational stability, and higher return-to-play rates. These findings have led to an in-depth evaluation of LEAPs as lateral extra-articular tenodesis and anterolateral ligament reconstruction and their potential role in improving outcomes after ACL reconstruction.

Factors Associated With Residual Pivot Shift After ACL Reconstruction: A Quantitative Evaluation of the Pivot-Shift Test Preoperatively and at Minimum 12-Month Follow-up

Background

Postoperative residual rotatory laxity remains despite improvement in surgical techniques for anterior cruciate ligament (ACL) reconstruction (ACLR).

Purpose

To evaluate factors associated with residual pivot shift after ACLR by quantitative measurement of the pivot shift before and after surgery.

Study Design

Case-control study; Level of evidence, 3.

Methods

A total of 97 patients who underwent primary double-bundle ACLR between June 2016 and March 2021 and underwent surgery to remove staples, with at least 12 months of follow-up evaluation, were enrolled. Quantitative measurements were performed under general anesthesia immediately before ACLR (preoperatively), after temporary fixation of the ACL graft (intraoperatively), and immediately before staple removal (postoperatively). The laxity of pivot shift was assessed using inertial sensors to measure acceleration and external rotational angular velocity (ERAV). Descriptive data were assessed for associations with postoperative acceleration and ERAV in a univariate analysis. A multiple linear regression analysis was performed to identify factors associated with postoperative acceleration and ERAV.

Results

Anterior tibial translation, acceleration, and ERAV increased from intra- to postoperatively (P < .05). Factors significantly associated with postoperative acceleration were age (β = -0.238; P = .021), lateral posterior tibial slope (PTS) (β = 0.194; P = .048), and preoperative acceleration (β = 0.261; P = .008). Factors significantly affecting postoperative ERAV were age (β = -0.222; P = .029), ramp lesions (β = 0.212; P = .027), and preoperative ERAV (β = 0.323; P = .001).

Conclusion

Greater preoperative laxity in the pivot shift was the factor having the most significant association with residual pivot shift after ACLR using quantitative measurements under general anesthesia. Younger age, higher lateral PTS, and concomitant ramp lesions were significant predictors of residual pivot shift. These findings can help pre- and intraoperative decision-making regarding whether an anterolateral structure augmentation should be added.

Combined Anterior Cruciate Ligament and Anterolateral Ligament Reconstruction Decreases Passive Anterior Tibial Subluxation Compared With Isolated Anterior Cruciate Ligament Reconstruction Despite Similar Rotational Stability and Clinical Outcomes

PURPOSE

To analyze the effect of augmenting a hamstring autograft anterior cruciate ligament reconstruction (ACLR) with an anterolateral ligament reconstruction (ALLR) on a primary outcome of passive anterior tibial subluxation (PATS) and a secondary outcome of the clinical outcomes.

METHODS

ACL-injured patients who underwent primary ACLR between March 2014 and February 2020 at our center were enrolled. Patients who underwent combined procedures (ACLR + ALLR) were matched in a 1:1 propensity ratio to patients who underwent ACLR only. We evaluated PATS, knee stability (side-to-side laxity difference, pivot-shift test), and patient-reported outcome measures (PROMs) after the procedure and documented complications.

RESULTS

From an initial cohort of 252 patients with a minimum follow-up period of 2 years (48.4 ± 16.6 months), 35 matched pairs were included, and 17 patients (48.6%) in each group underwent second-look arthroscopy. The combined ACLR + ALLR group showed significantly better improvement of PATS in the lateral compartments than the isolated ACLR group (P = .034). There were no significant differences between the groups regarding knee stability (side-to-side laxity difference, pivot-shift test), PROMs, complications, and second-look arthroscopic findings (all P > .05). Moreover, the proportions of patients who achieved the minimal clinically important difference in PROMs were not different between groups.

CONCLUSIONS

The combined ACLR + ALLR procedure was associated with a mean improvement in anterior tibial subluxation for the lateral compartment that was 1.2 mm better than an isolated ACLR procedure, despite its lack of clinical significance.

LEVEL OF EVIDENCE

Level III, cohort study.

Greater Knee Rotatory Instability After Posterior Meniscocapsular Injury Versus Anterolateral Ligament Injury: A Proposed Mechanism of High-Grade Pivot Shift

Background

For anterolateral rotatory instability as a result of secondary soft tissue injuries in anterior cruciate ligament (ACL)-deficient knees, there is increasing interest in secondary stabilizers to prevent internal rotation (IR) of the tibia.

Purpose

To determine which secondary stabilizer is more important in anterolateral rotatory instability in ACL-deficient knees.

Study Design

Controlled laboratory study.

Methods

The lower extremities of 10 fresh-frozen cadavers (20 extremities) without anterior-posterior or rotational instability were included. Matched-pair randomization was performed, with each side per specimen assigned to 1 of 2 groups. In group 1, the ACL was sectioned, followed by the anterolateral ligament (ALL); in group 2, the ACL was sectioned, followed by sequential sectioning of the posterolateral meniscocapsular complex (PLMCC) and posteromedial meniscocapsular complex (PMMCC). The primary outcome was the change in relative tibial IR during a simulated pivot-shift test with 5 N·m of IR torque and 8.9 N of valgus force. The secondary outcomes were the International Knee Documentation Committee grade in the pivot-shift test and the incidence of the grade 3 pivot shift.

Results

In group 1, compared with baseline, the change in relative tibial IR at 0° of knee flexion was 1.4° (95% CI, -0.1° to 2.9°; P = .052) after ALL release. In group 2, it was 2.5° (95% CI, 0.4° to 4.8°; P = .007) after PLMCC release and 4.1° (95% CI, 0.5° to 7.8°; P = .017) after combined PLMCC and PMMCC release. Combined PLMCC and PMMCC release resulted in greater change of tibial IR with statistical significance at 0°, 15°, and 30° of knee flexion (P = .008, .057, and .004, respectively) compared with ALL release. The incidence of grade 3 pivot shifts was 10% in group 1 and 90% in group 2.

Conclusion

Posterior meniscocapsular laxity caused an increase in relative tibial IR as much as ALL injury in ACL-deficient knees in our simulated laboratory test, and greater anterolateral rotatory instability occurred with posterior meniscocapsular injury compared with ALL injury.

Clinical Relevance

Repair of the injured posterior meniscocapsular complex may be an important treatment option for reducing anterolateral rotatory instability in the ACL-deficient knee.

Association Between Anterior Tibial Subluxation of Lateral Compartment and High-Grade Knee Laxity in Patients With Anterior Cruciate Ligament Deficiency

BACKGROUND

High-grade knee laxity and excessive anterior tibial subluxation (ATS) are correlated with poor clinical outcomes in patients with anterior cruciate ligament (ACL) deficiency and share similar risk factors; however, the association between excessive ATS and high-grade knee laxity remains unclear.

PURPOSE

To identify the association between excessive ATS and high-grade knee laxity in patients with ACL deficiency and determine the possibility that ATS can predict high-grade knee laxity.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A total of 226 patients who underwent ACL reconstruction between May 2018 and March 2022 were analyzed in the present study; the high-grade group consisted of 113 patients who had a grade 3 result on the preoperative anterior drawer test, Lachman test, or pivot-shift test while under anesthesia, and the low-grade group consisted of 113 matched patients. The ATS values for medial and lateral compartments (ATSMC and ATSLC) were measured on magnetic resonance imaging while patients relaxed the quadriceps in the supine position under no anesthesia. The optimal cutoff values of ATSMC and ATSLC for high-grade knee laxity were determined using receiver operating characteristic curves. Univariate and multivariate logistic regression analyses with stratification were performed to identify the association between excessive ATS and high-grade knee laxity.

RESULTS

Compared with the low-grade group, the high-grade group had a longer time from injury to surgery; higher rates of medial meniscus posterior horn tear (MMPHT), lateral meniscus posterior horn tear (LMPHT), and anterolateral ligament (ALL) abnormality; and larger lateral tibial slope, ATSMC, and ATSLC. The optimal cutoff value was 2.6 mm (sensitivity, 52.2%; specificity, 76.1%) for ATSMC and 4.5 mm (sensitivity, 67.3%; specificity, 64.6%) for ATSLC in predicting high-grade knee laxity. After adjustment for covariates, ATSLC ≥4.5 mm (odds ratio [OR], 2.94; 95% CI, 1.56-5.55; P = .001), MMPHT (OR, 2.62; 95% CI, 1.35-5.08; P = .004), LMPHT (OR, 2.39; 95% CI, 1.20-4.78; P = .014), and ALL abnormality (OR, 2.09; 95% CI, 1.13-3.89; P = .019) were associated with high-grade knee laxity. The association between excessive ATSLC and high-grade knee laxity was validated in patients with acute ACL injury as well as those with chronic ACL injury.

CONCLUSION

Excessive ATSLC was associated with high-grade knee laxity in patients who had ACL deficiency, with a predictive cutoff value of 4.5 mm. This study may help surgeons estimate the degree of knee instability more accurately before anesthesia and may facilitate preliminary surgical decision-making, such as appropriate graft choices and consideration of extra-articular augmentation.

Low reoperation rate following lateral meniscus root repair: clinical outcomes at 2 years follow-up

PURPOSE

The aim of this study was to review the outcomes of lateral meniscus posterior root tears repair at the time of ACL reconstruction at a minimum 2-year follow-up.

METHODS

Between March 2015 and August 2018, 2017 patients underwent primary ACL reconstruction and were considered for study eligibility. Lateral meniscus posterior root tears were identified arthroscopically, and repair was performed with a transtibial pull-out suture technique or a side-to-side suture technique. Clinical outcomes were recorded at the time of physical examination. At the end of the study period, patients were contacted to determine whether they had required reoperation.

RESULTS

Lateral meniscus posterior root tears were identified in 153 out of the 2,017 primary ACL reconstructions (7.6%). Ninety-nine patients were included for analysis: 23 transtibial pull-out sutures and 76 side-to-side repairs. At a mean follow-up of 42 ± 10 months, one patient (1%) had undergone reoperation for failure of the side-to-side repair. There were 11 reoperations in 10 patients (10.1%), including 6 cyclops syndrome, 1 graft rupture, 1 tibial bone cyst, 1 medial and 1 lateral meniscus repair failure, and 1 arthrolysis. Postoperatively, ninety (90.9%) patients were graded A for the IKDC objective score and 9 (9.1%) patients were graded B, with an IKDC subjective score of 86.9 ± 7.6, a Lysholm score of 90.7 ± 6.7 and a median Tegner Activity Scale of 6 (3-9). All of their objective and subjective evaluations improved after surgery (p < 0.001) except for the Tegner Activity Scale. Ten patients underwent second look arthroscopy (10.1%), lateral meniscus healing was observed in 9 out of 10 patients (90%).

CONCLUSION

This study demonstrated that lateral meniscus posterior root tear repair is a safe procedure with a very low reoperation rate at a minimum follow-up of 2 years.

LEVEL OF EVIDENCE

IV.

Pivot shift intraoperative quantitative assessment using a smartphone accelerometer in ACL deficient knees

PURPOSE

The Pivot Shift (PS) test is a complex clinical sign that assesses the internal rotation and anterior tibial translation, which occurs abnormally in ACL deficient-knees. Because of the high inter-observer variability, different devices have been designed to characterize this complex movement in quantitative variables. The objective of this pilot study is to validate the reproducibility of intraoperative quantitative assessment of the PS with a smartphone accelerometer.

METHODS

Twelve ACL-injured knees were included and compared with the contralateral uninjured side. The PS was measured by two independent observers utilizing a smartphone accelerometer and graded according to the IKDC classification. Measurements were taken preoperatively, intraoperatively and postoperatively. Intraoperative readings were taken during each stage of reconstruction or repair of meniscoligamentous lesions including meniscal lesions, ramp lesions, ACL reconstruction and lateral tenodesis. Reproducibility of the measurements were evaluated according to an intraclass correlation coefficient (ICC).

RESULTS

The intra-observer reliability was good for the first examiner and excellent for the second examiner, with the ICC 0.89 [0.67, 0.98] p < 0,001 and ICC 0.97 [0.91, 1.0] p < 0,001 respectively. The inter-observer reliability was excellent between the two observers with the ICC 0.99 [0.97, 1.0] p < 0,001. The mean tibial acceleration measured 3.45 m.s² (SD = 1.71) preoperatively on the injured knees and 1.03 m.s² (SD = 0.36) on the healthy knees, demonstrating a significant difference following univariate analysis p < 0.001. Postoperatively, no significant difference was observed between healthy and reconstructed knees The magnitudes of tibial acceleration values were correlated with the PS IKDC grade.

CONCLUSION

The smartphone accelerometer is a reproducible device to quantitatively assess the internal rotation and anterior tibial translation during ACL reconstruction surgery. The measurements are influenced by the different surgical steps. Other larger cohort studies are needed to evaluate the specific impact of each step of the ACL reconstruction and meniscal repair on this measurement. An external validation using other technologies are needed to validate the reliability of this device to assess the PS test.

LEVEL OF EVIDENCE

Level IV, case series, pilot study.

The Association Between Bone Bruises and Concomitant Ligaments Injuries in Anterior Cruciate Ligament Injuries: A Systematic Review and Meta-analysis

Background

Bone bruises and concomitant ligament injuries after anterior cruciate ligament (ACL) injuries have attracted attention, but their correlation and potential clinical significance remain unclear.

Purpose

To assess the relationship between bone bruises and concomitant ligamentous injuries in ACL injuries.

Study design

Systematic review.

Methods

A comprehensive search of PubMed, Embase, Web of Science, and Cochrane Library was completed from inception to October 20, 2021. All articles that evaluated the relationship between bone bruises and related ligaments injuries were included. Methodological Index for Non-Randomized Studies (MINORS) was used for quality assessment as well as Review Manager 5.3 was used for data analysis.

Results

A total of 19 studies evaluating 3292 patients were included. After meta-analysis, anterolateral ligament (ALL) injuries were associated with bone bruising on the lateral tibial plateau (LTP) (RR = 2.33; 95% CI 1.44-3.77; p = 0.0006), lateral femoral condyle (LFC) (RR = 1.97; 95% CI 1.37-2.85; p = 0.0003) and medial tibial plateau (MTP) (RR = 1.62; 95% CI 1.24-2.11; p = 0.0004); Moreover, medial collateral ligament (MCL) injuries were associated with bone bruising on the femur (RR = 1.49; 95% CI 1.17-1.90; p = 0.001), and no statistical significance was found between bone bruising on the MTP and Kaplan fiber (KF) injuries (RR = 1.58; 95% CI 1.00-2.49; p = 0.05). Nonetheless, the current evidence did not conclude that bone bruises were associated with lateral collateral ligament (LCL) injuries.

Conclusion

For individuals with an ACL injury, bone bruises of the LTP, LFC, and MTP can assist in the diagnosis of ALL injuries. Furthermore, femoral bruising has potential diagnostic value for MCL injuries. Knowing these associations allows surgeons to be alert to ACL-related ligament injuries on MRI and during operations in future clinical practice.

Steeper lateral posterior tibial slope and greater lateral-medial slope asymmetry correlate with greater preoperative pivot-shift in anterior cruciate ligament injury

PURPOSE

To investigate the association between posterior tibial slope (PTS) and preoperative pivot-shift phenomenon in anterior cruciate ligament (ACL)-injured knees.

METHODS

Fifty unilateral ACL-injured patients (mean age: 28.0 ± 11.4 years, 29 males) who underwent ACL reconstruction were retrospectively included. Patients with a history of injury to the ipsilateral knee joint, concomitant ligament injuries with ACL injury, and/or more than one year from injury to surgery, were excluded. Pivot-shift tests were performed preoperatively under general anaesthesia using an electromagnetic measurement system, and tibial acceleration (m/s²) during the posterior reduction of the tibia was measured. Medial and lateral PTS (°) were measured respectively using high-resolution CT images taken two weeks after surgery. Lateral-medial slope asymmetry was calculated by subtracting medial PTS from lateral PTS (lateral-medial PTS) and we evaluated the correlation between each PTS parameter (medial PTS, lateral PTS, and lateral-medial slope asymmetry) and tibial acceleration during the pivot-shift test. The level of significance was set at p < 0.05.

RESULTS

Medial PTS was 4.9 ± 2.0°, and lateral PTS was 5.2 ± 1.9°. The lateral-medial slope asymmetry was 0.3 ± 1.6° (range: -2.9 to 3.8). Tibial acceleration during the pivot-shift test in the ACL-injured knee was 1.6 ± 0.1 m/s². Preoperative tibial acceleration was positively correlated with lateral PTS (r = 0.436, p < 0.01), and lateral-medial slope asymmetry (r = 0.443, p < 0.01), while no significant correlation was found between preoperative tibial acceleration and medial PTS (r = 0.06, p = 0.70).

CONCLUSION

Preoperative greater tibial acceleration during the pivot-shift test was associated with steeper lateral PTS and greater lateral-medial slope asymmetry in ACL-injured knees. These findings improve our understanding of anterolateral rotatory knee laxity by linking tibial bony morphology to quantitative measurement of pivot-shift phenomenon. Surgeons should be aware that not only lateral PTS but also lateral-medial slope asymmetry are the factors associated with preoperative pivot-shift.

LEVEL OF EVIDENCE

Level IV.

Lateral posterior tibial slope does not affect femoral but does affect tibial tunnel widening following anatomic anterior cruciate ligament reconstruction using a Bone-Patellar Tendon-Bone graft

Background

Tunnel widening (TW) after anterior cruciate ligament (ACL) reconstruction has been a research area of interest in ACL reconstruction. In recent years, it has been noted that posterior tibial slope (PTS) affects several types of outcomes after ACL reconstruction including TW. However, the relationships between femoral and tibial TW and between PTS and TW following anatomical ACL reconstruction using a bone–patellar tendon–bone (BTB) graft are often not understood. Therefore, the purpose of this study was to retrospectively clarify the magnitude of femoral and tibial TW and the effect of PTS on TW following anatomical ACL reconstruction using a BTB graft.

Methods

A total of 111 patients who underwent isolated ACL reconstructions using BTB grafts were included in this study. Femoral and tibial tunnel aperture areas were measured using three-dimensional computed tomography (3D CT) at 1 week and 1 year postoperatively, and femoral and tibial TW (%) was calculated. Lateral and medial PTS was also measured using 3D CT.

Results

As compared with 1 week postoperatively, the mean tibial tunnel aperture areas increased by 30.6% ± 28.5%, and the mean femoral tunnel aperture areas increased by 28.3% ± 27.9% when measured at 1 year postoperatively. Although no significant difference was observed between femoral and tibial TW, a significant positive correlation was noted between femoral and tibial TW (r = 0.240, p = 0.011). A significant correlation was observed only between lateral PTS and tibial TW (r = 0.354, p < 0.001). There was no significant correlation between medial PTS and tibial TW, lateral PTS and femoral TW, or medial PTS and femoral TW.

Conclusion

Significant positive correlation was observed between femoral and tibial TW. Steeper lateral PTS correlated with greater tibial TW; on the other hand, medial PTS did not correlate with tibial TW. Although lateral PTS affected tibial TW, it did not affect femoral TW.

Anterior Tibial Subluxation of Lateral Compartment Is Associated With High-Grade Rotatory Instability for Acute But Not Chronic Anterior Cruciate Ligament Injuries: An Magnetic Resonance Imaging Case-Control Study

PURPOSE

To investigate whether anterior tibial subluxation obtained from magnetic resonance imaging (MRI) could be a predictor of high-grade rotatory instability for anterior cruciate ligament (ACL) injuries, including acute and chronic cases.

METHODS

From September 2016 to August 2018, we retrospectively investigated 163 patients with ACL injuries who subsequently underwent primary ACL reconstruction. Among them, 30 patients with high-grade rotatory instability (grade II/III pivot shift) were included in the high-grade group, and their age and sex were matched 1:2 to low-grade cases (<grade II pivot shift). On preoperative MRI, we measured anterior tibial subluxation, posterior tibial slope, as well as the time from injury to surgery. Meniscal lesions were documented from arthroscopy. Multivariable logistic regression was used to determine predictors of high-grade rotatory instability. Furthermore, subgroup comparisons between 2 groups were divided into acute (≤3 months) and chronic (>3 months) phases.

RESULTS

The high-grade group had a larger anterior tibial subluxation of lateral compartment (8.1 mm vs 5.9 mm; P =.004) than the low-grade group, whereas no significant difference was found in anterior tibial subluxation of medial compartment (P > .05). Moreover, high-grade anterior tibial subluxation of lateral compartment (≥6 mm) was found to be an independent predictor (odds ratio, 12.992; P = .011) associated with concomitant meniscal tears after ACL injuries. Anterior tibial subluxation of lateral compartment demonstrated statistical significance between the two groups when comparing subgroups within 3 months but not beyond 3 months.

CONCLUSION

In ACL-injured patients, high-grade anterior tibial subluxation of lateral compartment (≥6 mm) could be a unique predictor of high-grade knee rotatory instability for acute but not chronic injuries. Prolonged time from injury to surgery and lateral meniscus tears were risk factors for high-grade rotatory laxity in chronic patients.

LEVEL OF EVIDENCE

Level III, retrospective prognostic trial.

No Difference in Knee Kinematics Between Anterior Cruciate Ligament-First and Posterior Cruciate Ligament-First Fixation During Single-Stage Multiligament Knee Reconstruction: A Biomechanical Study

Background:

For combined reconstruction of both the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL), there is no consensus regarding which graft should be tensioned and fixed first.

Purpose:

The purpose of this study was to determine which sequence of graft tensioning and fixation better restores normal knee kinematics. The hypothesis was that ACL-first fixation would more closely restore normal knee kinematics, graft force, and the tibiofemoral orientation in the neutral (resting) position compared with PCL-first fixation.

Study Design:

Controlled laboratory study.

Methods:

A total of 15 unpaired human cadaveric knees were examined using a robotic testing system under the following 4 conditions: (1) 89.0-N anterior tibial load at different knee angles; (2) 89.0-N posterior tibial load at different knee angles; (3) combined rotational 7.0-N·m valgus and 5.0-N·m internal rotation load (simulated pivot shift) at 0°, 15°, and 30° of flexion; and (4) 5.0-N·m external rotation load at 0°, 15°, and 30° of flexion. The 4 evaluated knee states were (1) intact ACL and PCL (intact), (2) ACL and PCL deficient (deficient), (3) combined anatomic ACL-PCL reconstruction fixing the ACL first (ACL-first), and (4) combined anatomic ACL-PCL reconstruction fixing the PCL first (PCL-first). A 9.0 mm–diameter quadriceps tendon autograft was used for the ACL graft, tensioned with 40.0 N at 30° of flexion. A 9.5 mm–diameter hamstring tendon autograft (gracilis and semitendinosus, quadrupled loop, and augmented with an additional allograft strand if needed), tensioned with 40.0 N at 90° of flexion, was used for the PCL graft.

Results:

There were no statistically significant differences between ACL-first and PCL-first fixation regarding knee kinematics. ACL-first fixation restored anterior tibial translation to the intact state at all tested knee angles, while PCL-first fixation showed higher anterior tibial translation than the intact state at 90° of flexion (9.05 ± 3.05 and 5.87 ± 2.40 mm, respectively; P = .018). Neither sequence restored posterior tibial translation to the intact state at 30°, 60°, and 90° of flexion. At 15° of flexion, PCL-first fixation restored posterior tibial translation to the intact state, whereas ACL-first fixation did not.

Conclusion:

There were no differences in knee laxity between ACL-first and PCL-first fixation with the ACL graft fixed at 30° and the PCL graft fixed at 90°.

Clinical Relevance:

This study showed that there was no evidence to support the use of one tensioning sequence over the other in single-stage multiligament knee reconstruction.

Grade III pivot shift as an early sign of knee decompensation in chronic ACL-injured knees with bimeniscal tears

PURPOSE

To analyse possible associations between the preoperative pivot shift (PS) test and both patient and injury characteristics in anterior cruciate ligament (ACL)-injured knees, considering previously neglected meniscal injuries such as ramp and root tears. The hypothesis was that a preoperative grade III PS was associated with the amount of intra-articular soft-tissue damage and chronicity of the injury.

METHODS

The cohort involved 376 patients who underwent primary ACL reconstruction (239 males/137 females; median age 26). Patients were examined under anesthesia before surgery, using the PS test. During arthroscopy, intra-articular soft-tissue damage of the injured knee was classified as: (1) partial ACL tear; (2) complete isolated ACL tear; (3) complete ACL tear with one meniscus tear; and (4) complete ACL and bimeniscal tears. Chi-square and Mann-Whitney U tests were used to evaluate whether sex, age, body mass index, sport at injury, mechanism of injury, time from injury and intra-articular damage (structural damage of ACL and menisci) were associated with a grade III PS. Intra-articular damage was further analyzed for two sub-cohorts: acute (time from injury ≤ 6 months) and chronic injuries (> 6 months).

RESULTS

A grade III PS test was observed in 26% of patients. A significant association with PS grading was shown for age, time from injury and intra-articular soft-tissue damage (p < 0.05). Further analyses showed that grade III PS was associated with intra-articular damage in chronic injuries only (p < 0.01). In complete ACL and bimeniscal tears, grade III PS was more frequent in chronic (53%) than in acute knee injuries (26%; p < 0.01). Patients with chronic complete ACL and bimeniscal tears had a grade III PS 3.3 [1.3-8.2] times more often than patients in the acute sub-cohort.

CONCLUSION

In ACL-injured patients, a preoperative grade III PS was mainly associated with a higher amount of intra-articular soft-tissue damage and chronicity of the injury. Patients with complete chronic ACL injuries and bimeniscal tears were more likely to have a preoperative grade III PS than their acute counterparts. This suggests that grade III PS may be an early sign of knee decompensation of dynamic rotational knee laxity in chronic ACL-injured knees with bimeniscal lesions.

LEVEL OF EVIDENCE

Level III.

Anterolateral complex injuries occur in the majority of 'isolated' anterior cruciate ligament ruptures

PURPOSE

The anterolateral soft tissue envelope of the knee is frequently injured at the time of ACL rupture. This study aims to investigate the MRI injury patterns to the Anterolateral complex and their associations in patients with acute 'isolated ligament' ACL ruptures.

METHODS

Professional athletes who underwent ACL reconstruction for complete ACL rupture between 2015 and 2019 were included in this study. Patients' characteristics and intraoperative findings were retrieved from clinical and surgical documentation. Preoperative MRIs were evaluated and the injuries to respective structures of the Anterolateral complex and their associations were recorded.

RESULTS

Anterolateral complex injuries were noted in 63% of cases. The majority of injuries were to Kaplan Fibre (39% isolated injury and 19% combined with Anterolateral ligament injury). There was a very low incidence of isolated Anterolateral ligament injuries (2%). Kaplan Fibre injuries are associated with the presence of lateral femoral condyle bone oedema, and injuries to the superficial MCL, deep MCL, and ramp lesions. High grade pivot shift test was not associated with the presence of Kaplan Fibre or Anterolateral ligament injuries. Patients with an intact Anterolateral complex sustained injury to other knee structures (13% to medial ligament complex, 14% to medial meniscus, and 16% to lateral meniscus).

CONCLUSION

There is a high incidence of concomitant Anterolateral complex injuries in combination with ACL ruptures, with Kaplan Fibre (and therefore the deep capsulo-osseous layer of the iliotibial band) being the most commonly injured structure. Anterolateral ligament injuries occur much less frequently. These findings reinforce the importance of considering the presence of, and if necessary, treating injuries to structures other than the ACL, as a truly isolated ACL injury is rare.

Anatomic characteristics of the knee influence the risk of suffering an isolated meniscal injury and the risk factors differ between women and men

PURPOSE

To analyse the relationship between multiple anatomic characteristics of the knee (tibia and femur) and isolated meniscal injury in women and men.

METHODS

Forty-seven patients with isolated medial meniscal injuries, 62 patients with isolated lateral meniscal injuries, and 70 control subjects were included. Medial posterior tibial slope (MTS), lateral posterior tibial slope (LTS), medial tibial plateau depth (MTD), coronal tibial slope (CTS), femoral notch width (NW), femoral condylar width (FCW), intercondylar notch depth (ND), femoral notch width index (NWI), intercondylar notch shape index (NSI), and cruciate ligaments tensity (CLT) were measured from magnetic resonance images. Anatomic characteristics differing between groups were compared, and risk factors for isolated meniscal injury were identified by multivariate forward stepwise logistic regression for men and women separately.

RESULTS

Risk factors for an isolated medial meniscal injury were a steeper MTS and a lowered MTD in men, and a steeper MTS and an increased NWI in women. Risk factors for isolated lateral meniscal injury were a steeper LTS and an increased NW in men, and a steeper LTS and a lowered ND in women. Risk factors for both medial and lateral meniscal injuries were a higher CTS, an increased NWI, and a looser CLT in men, and a higher CTS, an increased NSI, and a looser CLT in women.

CONCLUSION

The anatomic characteristics of the tibial plateau, femur, and cruciate ligaments influence the risk of suffering isolated meniscal injury, and the risk factors differ between men and women. This study provides a reference for developing identification criteria for those at risk of isolated meniscal injury.

LEVEL OF EVIDENCE

III.

Lateral posterior tibial slope and length of the tendon within the tibial tunnel are independent factors to predict tibial tunnel widening following anatomic anterior cruciate ligament reconstruction

PURPOSE

This study aimed to conduct a multivariate analysis to identify independent factors that predict tibial tunnel widening (TW) after anatomical anterior cruciate ligament (ACL) reconstruction using bone-patellar tendon-bone (BPTB) grafts.

METHODS

In total, 103 patients who underwent ACL reconstructions using BPTB grafts were included. Tunnel aperture area was measured using three-dimensional computed tomography 1 week and 1 year postoperatively, and the tibial TW was calculated. The patients were divided into group S comprising 58 patients who had tibial TW < 30% and group L comprising 45 patients who had tibial TW > 30%, retrospectively. Using univariate analyses, age, gender, body mass index, Tegner activity scale, the time between injury and surgery, tibial tunnel location, tibial tunnel angle, medial posterior tibial slope, lateral posterior tibial slope, and length of the tendon in the tibial tunnel were compared between two groups. Multivariate regression analysis was conducted to reveal the independent risk factors for the tibial TW among preoperative demographic factors and radiographic parameters that correlated with the tibial TW in the univariate analyses.

RESULTS

Compared with those at 1 week postoperatively, mean tibial tunnel aperture areas were increased by 30.3% ± 26.8% when measured at 1 year postoperatively. The lateral posterior tibial slope was significantly larger (p < 0.001), and the length of the tendon within the tibial tunnel was significantly longer in group L than that in group S (p = 0.03) in the univariate analyses. Multivariate regression analysis showed that the increase in lateral posterior tibial slope (p = 0.001) and the length of the tendon within the tibial tunnel (p = 0.03) were predictors of the tibial TW.

CONCLUSIONS

This study showed that increased lateral posterior tibial slope and a longer tendinous portion within the tibial tunnel were independent factors that predicted the tibial TW following anatomical ACL reconstruction with a BPTB graft.

LEVEL OF EVIDENCE

III.

Anterolateral Ligament Reconstruction Improves Anteroposterior Stability As Well As Rotational Stability in Revision Anterior Cruciate Ligament Reconstruction with High-Grade Pivot Shift

This study aimed to investigate the effect of anterolateral ligament reconstruction (ALLR) in revision anterior cruciate ligament reconstruction (ACLR) with high-grade pivot shift. The hypothesis was that revision ACLR combined with ALLR (RACLR with ALLR group) would show superior clinical outcomes to those of isolated revision ACLR. We retrospectively evaluated consecutive patients who underwent revision ACLR (RACLR) combined with ALLR between October 2015 and January 2017. The indication for combination of ALLR with revision ACLR was failed ACLR with ≥G2 pivot-shift instability. The control group included patients who underwent isolated revision ACLR (isolated RACLR group) for the same indication between July 2013 and September 2015. Exclusion criteria were ≤G1 pivot-shift instability, multiple ligament reconstruction, bilateral ligament injury, double-bundle reconstruction, insufficient medical records, postoperative infection, and follow-up loss at postoperative 2 years. Clinical scores, stability tests, and failure rates were compared between groups at the 2-year follow-up. The RACLR with ALLR group had 18 patients (mean age, 32.9 ± 10.8 years) and the RACLR group had 21 patients (mean age, 29.6 ± 10.2 years). Clinical scores at the 2-year follow-up showed no significant differences between groups. However, the RACLR with ALLR group showed better stability in the Lachman test (p = 0.005), pivot-shift test (p = 0.030), and side-to-side difference in stress radiographs (3.9 ± 3.0 mm vs. 5.9 ± 2.8 mm, p = 0.018) than the isolated RACLR group. The RACLR with ALLR group had two failures (11.1%), and the RACLR group had three failures (14.3%). In conclusion, ALLR in revision ACLR with high-grade pivot shift improves anteroposterior stability as well as rotational stability at 2-year follow-up. Therefore, ALLR is recommended with revision ACLR, especially in patients with high-grade pivot shift. This is a Level III, retrospective cohort review.

Reconstruction for Chronic ACL Tears with or without Anterolateral Structure Augmentation in Patients at High Risk for Clinical Failure: A Randomized Clinical Trial

BACKGROUND

The purpose of this trial was to determine whether anterior cruciate ligament reconstruction (ACLR) with anterolateral structure augmentation (ALSA) would result in better clinical outcomes in patients with a high risk of clinical failure.

METHODS

From February 2017 to June 2018, 120 young, active adults with chronic anterior cruciate ligament injury and high risk of clinical failure were randomized. The patients were followed for >2 years, with 5 being lost to follow-up and 1 being withdrawn from the study. Clinical characteristics, operative findings, and postoperative clinical outcomes were analyzed.

RESULTS

The analysis included data from 114 patients, including 95 men and 19 women with a mean age (and standard deviation) of 30.1 ± 6.7 years in the ACLR group and 30.1 ± 6.4 years in the ALSA group. The rate of clinical failure was 20.4% (11 of 54 patients) and 3.3% (2 of 60 patients) in the ACLR and ALSA groups, respectively (difference, 17.1%; 95% confidence interval [CI], 5.3% to 29.8%; p = 0.007). Significantly higher rates of return to the preinjury level of sports (48.3% versus 27.8%; difference, 20.5%; 95% CI, 2.7% to 36.6%; p = 0.024) and to a competitive level of play (63.3% versus 42.6%; difference, 22.3%; 95% CI, 4.1% to 38.8%; p = 0.027) was found in the ALSA group.

CONCLUSIONS

Compared with isolated ACLR, combined ACLR and ALSA resulted in a reduction in persistent rotatory laxity and higher rates of return to preinjury and competitive levels of play at 2 years of follow-up in the population studied. Our study suggests that patients with high risk of clinical failure appear to be candidates for the ALSA approach.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Sagittal Inclination Angle of Graft Is Associated With Knee Stability After Anatomic Anterior Cruciate Ligament Reconstruction

PURPOSE

To evaluate whether the sagittal inclination angle (SIA) of a graft is associated with postoperative knee stability after anatomic anterior cruciate ligament (ACL) reconstruction.

METHODS

All patients who had undergone anatomic ACL reconstruction between April 2014 and September 2015 in addition to volunteers with no history of knee injury were eligible for inclusion in this study. The patients were evaluated by magnetic resonance imaging of the knee in full extension at 1 year after surgery, as were volunteers. The posterior tibial slope (PTS) angle and the SIA of the intact ACL and reconstructed graft were measured relative to each medial and lateral tibial plateau. The patients were examined for knee stability by the side-to-side difference in the anterior tibial translation on stress radiographs at minimum 2-year follow-up.

RESULTS

We included 43 patients (26 male, 17 female, mean age 32.8 ± 14.8 years) and 12 volunteers (7 male, 5 female, mean age 28.7 ± 3.1 years) as normal controls. The mean follow-up duration was 29.8 ± 3.6 months. The mean PTS angle and mean SIA in the patients did not significantly differ from those of the intact ACL. The PTS angle in the patients was not significantly correlated with postoperative side-to-side difference in the anterior tibial translation. However, the graft SIA was significantly correlated with the postoperative anterior tibial translation (medial SIA; r = 0.42, P = .005, lateral SIA; r = 0.52, P < .001).

CONCLUSIONS

Even if anatomically reconstructed, the graft SIA in reference to the tibial plateau at full knee extension is variable and is associated with postoperative knee stability. The larger graft SIA was correlated with graft laxity after anatomic ACL reconstruction.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Double-Bundle Anterior Cruciate Ligament Reconstruction With Lateral Extra-Articular Tenodesis Is Effective in Restoring Knee Stability in a Chronic, Complex Anterior Cruciate Ligament-Injured Knee Model: A Cadaveric Biomechanical Study

PURPOSE

To compare knee stability after intra-articular isolated double-bundle (DB) anterior cruciate ligament reconstruction (ACLR) and single-bundle (SB) and DB ACLR combined with lateral extra-articular tenodesis (LET) in a chronic, complex anterior cruciate ligament (ACL)-injured knee model.

METHODS

In 10 fresh-frozen cadaveric knees, we measured knee laxity in the following order: (1) intact knee; (2) ACL-sectioned knee; (3) complex ACL-injured knee model with additional sectioning of the anterolateral complex and the posterior horns of the medial and lateral menisci; (4) SB ACLR plus LET; (5) DB ACLR; and (6) DB ACLR plus LET.

RESULTS

In comparison with the intact knee, significantly increased internal rotation (IR) laxity persisted at 60° and 90° after DB ACLR (P = .002 and P = .003, respectively). SB ACLR plus LET and DB ACLR plus LET resulted in significant reductions in IR laxity at 90° (P = .003 and P = .037, respectively), representing overconstraint in IR. SB ACLR plus LET resulted in persistently increased external rotation (ER) laxity at 30°, 60°, and 90° (P = .001, P < .001, and P < .001, respectively). The DB ACLR condition persistently showed significant increases in anterior tibial translation laxity at 60° and 90° (P = .037 and P = .024, respectively). A greater increase in ER laxity was seen after SB ACLR plus LET versus DB ACLR plus LET at 30°, 60°, and 90° (P < .001, P < .001, and P < .001, respectively).

CONCLUSIONS

DB ACLR plus LET restored intact knee stability in IR, ER, and anterior tibial translation laxity at 0°, 30°, 60°, and 90° of knee flexion except for overconstraint in IR at 90° in a chronic, complex ACL-injured knee model.

CLINICAL RELEVANCE

This cadaveric study provides some biomechanical evidence to support performing DB ACLR combined with LET to restore knee stability after a complex, chronic knee injury involving an ACL tear combined with anterolateral complex injury and irreparable tears of the posterior horns of the medial and lateral menisci.

Association of Ligamentous Laxity, Male Sex, Chronicity, Meniscal Injury, and Posterior Tibial Slope With a High-Grade Preoperative Pivot Shift: A Post Hoc Analysis of the STABILITY Study

Background:

A spectrum of anterolateral rotatory laxity exists in anterior cruciate ligament (ACL)–injured knees. Understanding of the factors contributing to a high-grade pivot shift continues to be refined.

Purpose:

To investigate factors associated with a high-grade preoperative pivot shift and to evaluate the relationship between this condition and baseline patient-reported outcome measures (PROMs).

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

A post hoc analysis was performed of 618 patients with ACL deficiency deemed high risk for reinjury. A binary logistic regression model was developed, with high-grade pivot shift as the dependent variable. Age, sex, Beighton score, chronicity of the ACL injury, posterior third medial or lateral meniscal injury, and tibial slope were selected as independent variables. The importance of knee hyperextension as a component of the Beighton score was assessed using receiver operator characteristic curves. Baseline PROMs were compared between patients with and without a high-grade pivot.

Results:

Six factors were associated with a high-grade pivot shift: Beighton score (each additional point; odds ratio [OR], 1.17; 95% CI, 1.06-1.30; P = .002), male sex (OR, 2.30; 95% CI, 1.28-4.13; P = .005), presence of a posterior third medial (OR, 2.55; 95% CI, 1.11-5.84; P = .03) or lateral (OR, 1.76; 95% CI, 1.01-3.08; P = .048) meniscal injury, tibial slope >9° (OR, 2.35; 95% CI, 1.09-5.07; P = .03), and chronicity >6 months (OR, 1.70; 95% CI, 1.00-2.88; P = .049). The presence of knee hyperextension improved the diagnostic utility of the Beighton score as a predictor of a high-grade pivot shift. Tibial slope <9° was associated with only a high-grade pivot in the presence of a posterior third medial meniscal injury. Patients with a high-grade pivot shift had higher baseline 4-Item Pain Intensity Measure scores than did those without a high-grade pivot shift (mean ± SD, 11 ± 13 vs 8 ± 14; P = .04); however, there was no difference between groups in baseline International Knee Documentation Committee, ACL Quality of Life, Knee injury and Osteoarthritis Outcome Score, or Knee injury and Osteoarthritis Outcome Score subscale scores.

Conclusion:

Ligamentous laxity, male sex, posterior third medial or lateral meniscal injury, increased posterior tibial slope, and chronicity were associated with a high-grade pivot shift in this population deemed high risk for repeat ACL injury. The effect of tibial slope may be accentuated by the presence of meniscal injury, supporting the need for meniscal preservation. Baseline PROMs were similar between patients with and without a high-grade pivot shift.

Association Between Radiological Evidence of Kaplan Fiber Injury, Intraoperative Findings, and Pivot-Shift Grade in the Setting of Acute Anterior Cruciate Ligament Injury

BACKGROUND

Biomechanical studies have suggested that the Kaplan fibers (KFs) of the iliotibial band play a role in controlling anterolateral rotation of the knee. There is a paucity of clinical information on whether injury to the KF in the setting of anterior cruciate ligament (ACL) rupture contributes to increased rotatory laxity of the knee.

PURPOSE/HYPOTHESIS

The purpose was to evaluate the association among radiological evidence of KF injury, intraoperative arthroscopic findings, and grade of pivot shift at the time of ACL reconstruction (ACLR). It was hypothesized that KF injury would be associated with increased injury to the lateral compartment of the knee and a higher grade of pivot shift.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A retrospective magnetic resonance imaging (MRI) analysis was conducted on 267 patients with ACL-injured knees who underwent primary ACLR. Patients who had MRI and surgery within 60 days of injury were included (mean age, 23.6 years); there were 158 (59.2%) male patients. MRI was performed using standard knee protocols, and diagnostic criteria were applied to identify KF injury. Associations were made among MRI findings, intraoperative findings, and grade of pivot shift with the patient examined under anesthesia at the time of ACLR. A comparison was made between patients with and without radiological evidence of KF injury.

RESULTS

The prevalence of KF injury was 17.6% (47/267 patients). Arthroscopic evidence of lateral meniscal injury was associated with KF injury (KF intact, 31%; KF injured, 55%; P = .010). The majority of patients in the intact and injured KF groups had a grade 2 pivot shift (75% and 70%, respectively). A minority had grade 3 pivot shift: 5% in the intact group versus 6.4% in the injured group. There was no association between radiological evidence of KF injury and pivot-shift grade (P = .600).

CONCLUSION

In acute ACL injury, KF injuries were not very common (17.6%), and the rate of grade 3 pivot shift was low (5.2%). When present, KF injuries were not associated with a higher-grade pivot shift. However, there was an association between KF injury and lateral meniscal tears identified at the time of ACLR. The role of KFS in controlling anterolateral rotatory laxity in the acute ACL injury in the clinical setting may be less evident when compared with the biomechanical setting.

[Effectiveness of double-bundle anterior cruciate ligament reconstruction combined with anterolateral ligament reconstruction for revision]

Objective

To investigate the effectiveness of double-bundle anterior cruciate ligament (ACL) reconstruction combined with anterolateral ligament (ALL) reconstruction in the treatment of revision patients with ACL graft failure.

Methods

Between January 2018 and June 2019, 15 patients underwent ACL revision with double-bundle ACL reconstruction combined with ALL reconstruction. There were 12 males and 3 females with an average age of 30.1 years (range, 17-49 years). The technique of primary ACL reconstruction included single-bundle reconstruction in 13 cases and double-bundle reconstruction in 2 cases. These reconstructions applied autografts in 14 cases and allograft in 1 case. The causes of ACL reconstruction failure were identified as traumatic rupture in 9 cases and non-traumatic failure in 6 cases, including 2 cases of graft absorption and 3 cases of graft laxity. The average time from the primary ACL reconstruction to revision was 28.5 months (range, 8-60 months). The subjective and objective indicators of knee joint function were compared before operation and at last follow-up to evaluate the effectiveness. The subjective indicators included International Knee Documentation Committee (IKDC) score, Lysholm score, and Tegner score. The objective indicators included anterior tibial translation (dynamic and static) and side-to-side difference (SSD), pivot-shift test, Lachman test, the difference of single-legged hop test, and the loss ratio of extensor muscle strength on the affected side.

Results

All incisions healed by first intetion, and no complications such as infection, venous thrombosis of lower extremity, or neurovascular injury occurred. All patients were followed up for an average of 19.1 months (range, 12-30 months). At last follow-up, all patients had returned to pre-injury sports level. The IKDC score, Lysholm score, and Tegner score were significantly improved ( P<0.05); anterior tibial translations (dynamic and static) significantly decreased when compared with preoperative one ( P<0.05) and returned to the physiological range. The SSD, Lachman test, pivot-shift test, the difference of single-legged hop test, and the loss ratio of extensor muscle strength on the affected side were significantly better than those before operation ( P<0.05).During the follow-up, there was no re-rupture of the graft, no stiffness of the knee joint and limitation of mobility; 1 case had a protruding femoral end compression screw, which was removed through the original incision under local anesthesia.

Conclusion

Double-bundle ACL reconstruction combined with ALL reconstruction can significantly improve the knee function in revision patients with ACL graft failure. It can reduce the anterior translation of tibia, and effectively prevent postoperative rotational instability of the knee.

The role of MRI in evaluation of arthroscopic transtibial pullout repair for medial meniscus posterior root tears

Medial meniscus posterior root tears (MMPRT) can lead to meniscal extrusion, loss of hoop tension, loss of load-sharing ability and increased contact pressure. Currently, the most commonly used technique for root repair is arthroscopic transtibial pullout repair (ATPR). This article aims to illustrate both normal and abnormal postoperative imaging findings of the MMPRT repair performed with ATPR, with emphasis on MRI. The radiologist must highlight the tunnel position, the reduction of the medial meniscus posterior root to its anatomical attachment, the signs of root healing (continuity and lower signal intensity), and eventual meniscal extrusion or signs of osteoarthritis.

Preoperative Knee Instability Affects Residual Instability as Evaluated by Quantitative Pivot-Shift Measurements During Double-Bundle ACL Reconstruction

Background:

The pivot-shift test is an important indicator of functional outcomes after anterior cruciate ligament (ACL) reconstruction (ACLR). Preoperative instability as indicated by the pivot-shift test is associated with residual instability after ACLR. Few studies have used quantitative means to evaluate the pivot shift after ACLR.

Purpose:

To investigate the relationship between preoperative and residual instability and to identify the risk factors for residual instability by using quantitative measurements of the pivot shift.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

A total of 91 patients undergoing primary double-bundle ACLR were retrospectively enrolled. Quantitative measurements of instability for ACL-deficient knees (ACLD) and uninjured contralateral knees (intact) preoperatively, as well as ACLR knees intraoperatively, were performed under general anesthesia using the pivot-shift test, with inertial sensors to measure acceleration and external rotational (ER) angular velocity. The ratios of intact to ACLD (ACLD/I) and intact to ACLR (ACLR/I) were measured. Patients who showed an ACLR/I of >1 were classified into the residual instability group, and those with an ACLR/I of ≤1 were classified into the noninstability group. Regarding demographic, surgical, and quantitative measurement factors, between-group comparisons and multivariate logistic regression were conducted for predictors of residual instability. Receiver operating characteristic curves were used to evaluate the correlations between ACLD/I and ACLR/I and the cutoff value of ACLD/I in predicting residual instability.

Results:

The predictive factors for intraoperative residual instability included female sex (odds ratio [OR], 0.3 [95% CI, 0.1-0.9]; P = .034) and ACLD/I for acceleration (OR, 1.6 [95% CI, 1.2-2.1]; P < .001), and ACLD/I for ER angular velocity (OR, 1.9 [95% CI, 1.2-3.1]; P = .013). Correlations between ACLD/I and ACLR/I were moderate with respect to both acceleration (r = 0.435; P < .001) and ER angular velocity (r = 0.533; P < .001). The cutoff points for ACLD/I were 4.9 for acceleration (sensitivity, 65.1%; specificity, 85.7%; area under the curve [AUC], 0.76) and 2.4 for ER angular velocity (sensitivity, 80.0%; specificity, 50.0%; AUC, 0.74).

Conclusion:

Greater preoperative instability was a risk factor for residual instability as measured intraoperatively by a quantitatively evaluation in the pivot shift during ACL reconstruction. Quantitative measurements of instability during the pivot shift mechanism under general anesthesia may enable surgeons to predict postoperative residual instability.

Truly Existing or Hyped up? Unravelling the Current Knowledge Regarding the Anatomy, Radiology, Histology and Biomechanics of the Enigmatic Anterolateral Ligament of the Knee Joint

Ever since its description, anterolateral ligament (ALL) of the knee joint remains as the hotspot of controversies. Though it has been described under various descriptions, the structure gained its limelight when it was christened as anterolateral ligament by Claes in 2013. The main reason for the controversies around it is the lack of concrete evidences regarding its attachments, morphology, biomechanical aspects and radiological appearance. Similarly the role of ALL in pivot shift phenomenon also remains as a point of debate. The advocates of ALL suggest that because of its ability to modulate internal rotation and attachment to the lateral meniscus, ALL contributes to the pivot shift phenomenon. Similarly, the orientation of ALL stands as the reason for varied documentation with respect to imaging techniques. With the growing body of evidence, it is imperative to fix our stand regarding the structure because, if found to be morphologically persistent, it can be used for concomitant anterolateral stabilization along with anterior cruciate ligament reinforcement surgeries. The present review tries to systematically review the anatomy, variations in classifications, descriptions, histology, radiology and biomechanical features of ALL. At the end of the review, we would like to find the answer for the question: Is ALL a distinct ligamentous structure located at the anterolateral aspect of the knee? What is the contribution of it to the tibial internal rotation stability?

Risk Factors for Grade 3 Pivot Shift in Knees With Acute Anterior Cruciate Ligament Injuries: A Comprehensive Evaluation of the Importance of Osseous and Soft Tissue Parameters From the SANTI Study Group

BACKGROUND

Preoperative grade 3 pivot shift has been reported to be associated with higher rates of anterior cruciate ligament (ACL) failure, persistent instability, and inferior patient-reported outcomes. The etiology of a high-grade pivot shift is multifactorial, and numerous factors have been suggested to be responsible. More attention has recently been focused on injury to the anterolateral structures (ALS) as a risk factor for a grade 3 pivot shift.

PURPOSE

To determine risk factors for grade 3 pivot shift, including soft tissue and osseous parameters.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A prospective evaluation was undertaken of 200 consecutive patients undergoing acute ACL reconstruction (within 10 days of injury). An open exploration of the lateral side of the injured knee was performed at the time of the index procedure. Details regarding patient and injury characteristics were recorded, as were details of soft tissue injuries, including meniscal tears, ALS lesions, medial collateral ligament tears, and chondral injuries. Osseous parameters (tibial slope and condylar ratios) were determined per established magnetic resonance imaging protocols. A multivariate logistic regression with penalized maximum likelihood was used to identify risk factors associated with International Knee Documentation Committee (IKDC) grade 3 pivot shift.

RESULTS

The mean ± SD age of the population was 28.3 ± 9.8 years; 67.5% of patients were male. Among patients, 35 (17.5%) had a high-grade pivot shift (IKDC grade 3), and 165 (82.5%) had a low-grade pivot shift (IKDC grades 1 and 2). Univariate and multivariate logistic regression analysis demonstrated that injury to the ALS was the only significant risk factor for grade 3 pivot shift (odds ratio, 13.49; 95% CI, 1.80-1725.53).

CONCLUSION

This comprehensive evaluation of soft tissue and osseous factors has identified that injury to the ALS is the most important risk factor for grade 3 pivot shift in acute ACL-injured knees.

Painful Palpation of the Tibial Insertion of the Anterolateral Ligament Is Concordant With Acute Anterolateral Ligament Injury

Background

The anterolateral ligament (ALL) has been shown to contribute to the rotational stability of the knee. However, no clinical sign specific to ALL injury has been described.

Purpose/Hypothesis

The primary aim of this study was to determine the concordance between pain elicited upon ALL palpation and ALL injury diagnosed by ultrasonography (US). The secondary aim was to look for a relationship between ALL injury and high-grade pivot shift. We hypothesized that an ALL lesion can be diagnosed clinically in an acute knee injury by palpating its tibial insertion.

Study Design

Cohort study (diagnosis); Level of evidence, 2.

Methods

A total of 130 patients (89 men, 41 women; mean age, 27.2 ± 8.3 years) with an acute, isolated anterior cruciate ligament injury who were scheduled for ligament reconstruction were enrolled in this study. ALL palpation was carried out a mean 8.8 ± 3.2 days after injury. Preoperatively, ALL integrity was evaluated with US, and the pivot shift was determined under general anesthesia. The agreement between pain upon ALL palpation and ALL injury detected on US was determined by calculating the intraclass correlation coefficient (ICC), along with 95% CIs.

Results

Distal palpation of the ALL tibial insertion elicited pain in 67 (51.5%) patients, and upon US the ALL was found to be damaged in 64 (49.2%) patients. The agreement between pain over the ALL tibial insertion and the ALL being damaged on US was excellent (ICC, 0.801; 95% CI, 0.730-0.855). Moreover, the clinical test had excellent sensitivity (92%; 95% CI, 88%-97%) and specificity (88%; 95% CI, 82%-93%). The agreement between pain at the ALL distal insertion and the pivot shift was good (ICC, 0.654; 95% CI, 0.543-0.742), and ALL palpation had excellent diagnostic accuracy for identifying rotational instability (sensitivity, 88% [95% CI, 82%-93%]; specificity, 97% [95% CI, 94%-100%]).

Conclusion

Palpation of the ALL tibial insertion highly correlates with ultrasonographic evidence of an ALL injury in the context of an acute knee injury. This simple test should become part of our standard examination when evaluating patients with acute knee injuries.

Predictive Factors Associated with Anterolateral Ligament Injury in the Patients with Anterior Cruciate Ligament Tear

BACKGROUND

The earlier studies did not assess the associated factors of anterolateral ligament injury, comprehensively. We sought to evaluate the independent predictive factors of anterolateral ligament injury in the patients with anterior cruciate ligament tear. Ultrasound scan has an emerging role in the diagnosis of anterolateral ligament injury.

MATERIALS AND METHODS

We included 198 patients with anterior cruciate ligament tear in this study. All the patients underwent knee ultrasound scan to diagnose the anterolateral ligament injury. The potential predictive factors of anterolateral ligament injury were compared between the patients with anterolateral ligament injury and the patients with the intact anterolateral ligament.

RESULTS

In all the patients, the anterolateral ligament was seen in the tibial and femoral portions using the ultrasound scan. One hundred and ten patients (55.6%) had anterolateral ligament injury and the anterolateral ligament was intact in 88 patients (44.4%). The lateral collateral ligament injury was significantly associated with the anterolateral ligament injury (p < 0.001). In addition, the iliotibial band injury had a significant relationship with the anterolateral ligament injury (p = 0.001). An increased lateral tibial slope was significantly associated with the anterolateral ligament injury (p = 0.031). Furthermore, the bone contusion of the lateral femoral condyle had a significant relationship with the anterolateral ligament injury (p = 0.004).

CONCLUSION

The independent predictors of anterolateral ligament injury included the lateral collateral ligament injury, iliotibial band injury, bone contusion of the lateral femoral condyle, and an increased lateral tibial slope.

Increased lateral meniscal slope is associated with greater incidence of lateral bone contusions in noncontact ACL injury

PURPOSE

(1) To investigate whether an increased lateral meniscal slope measured on magnetic resonance image (MRI) would be associated with greater risk of bone contusions in noncontact anterior cruciate ligament injury, and (2) to measure the relationship between the occurrence of bone contusions and associated findings observed in ACL deficient knees such as cartilage damage, anterolateral complex injury and concomitant meniscal tears.

METHOD

Patients who underwent ACL reconstruction surgery between 2013 and 2018 were retrospectively reviewed. Sixty-three patients were included in the study group (ACL + bone contusions group), 56 participants were in the control group (isolated ACL group). The presence and severity of bone contusions were determined from preoperative MRIs. The lateral meniscal slope and lateral posterior tibial slope were measured on the MRIs in a blinded fashion. The predictors of lateral bone contusions including age, sex, body mass index, lateral meniscal slope and lateral posterior tibial slope were examined by multivariable logistic regression. Associated findings including concomitant meniscal lesions, intra-articular cartilage damage and anterolateral complex injury, which were also calculated by multivariable logistic regression.

RESULTS

The mean lateral meniscal slope in the study group was 6.5° ± 3.5°, which was significantly larger than that in the control group (3.8° ± 2.7°; P < 0.01). In addition, increased lateral meniscal slope was significantly associated with lateral bone contusions in noncontact ACL injury (Lateral femoral condyle (LFC): AOR 16.5; 95% CI 5.40-50.20; P < 0.01; Lateral tibial plateau (LTP): AOR 31.8; 95% CI 8.68-116.7; P < 0.01). However, lateral posterior tibial slope was not significantly associated with bone contusions. Moreover, the presence of lateral bone contusions was associated with concomitant lateral meniscal tears (OR 12.4; 95% CI 3.30-46.30) and cartilage damage (OR 2.9; 95% CI 1.04-8.18).

CONCLUSION

An increased lateral meniscal slope was associated with increased risk of lateral bone contusions in noncontact ACL injury. In addition, the presence of lateral bone contusions was associated with intra-articular cartilage damage, anterolateral complex injury and concomitant meniscal tears. Hence, additional information was provided for counseling patients who have increased LMS on the greater risk of knee rotational instability and identify patients undergoing ACL reconstruction who may benefit from extra-articular tenodesis.

LEVEL OF EVIDENCE

IV.

MRI appearance of the different meniscal ramp lesion types, with clinical and arthroscopic correlation

BACKGROUND

Meniscal ramp lesions have been defined as longitudinal vertical peripheral tears of the medial meniscus involving the posterior meniscocapsular ligament, meniscotibial ligament, and/or the red-red zone of the posterior horn. They are heavily associated with anterior cruciate ligament injuries, and because of their potentially important biomechanical role in knee stabilization, injuries to this region may require surgical repair. However, due to their location and lack of general knowledge regarding their different types and associated appearances on magnetic resonance imaging, ramp lesions are routinely underreported. This is compounded by the fact that ramp lesions are also often overlooked during conventional anterior portal arthroscopy when direct visualization is not achieved.

PURPOSE

To demonstrate MRI appearances and arthroscopic findings of the different types of meniscal ramp lesions, in the hopes of improving their detection on pre-operative imaging.

The Influences of Chronicity and Meniscal Injuries on Pivot Shift in Anterior Cruciate Ligament-Deficient Knees: Quantitative Evaluation Using an Electromagnetic Measurement System

PURPOSE

To investigate the influences of time from injury to surgery and meniscal injuries on knee rotational laxity in anterior cruciate ligament (ACL)-deficient knees using the electromagnetic system retrospectively.

METHODS

Ninety-four unilateral ACL-injured patients (44 male and 50 female, mean age: 27.3 ± 11.8 years) were included. The pivot-shift test was performed before ACL reconstruction, as was a quantitative evaluation using the electromagnetic system to determine tibial acceleration. Patients were divided into 4 groups according to the chronicity: group 1, within 3 months (22 patients); group 2, between 3 and 6 months (29 patients); group 3, between 6 and 12 months (23 patients); and group 4, more than 12 months (20 patients). The presence of meniscal injuries was examined arthroscopically.

RESULTS

The tibial acceleration was significantly greater in group 4. There was a positive correlation between tibial acceleration and the time from injury to surgery (r = 0.47, P = .02). In groups 1, 2 and 3, the tibial acceleration in patients with a lateral meniscal injury was significantly greater than in patients with a medial meniscal injury and without meniscal injury. When patients with lateral meniscal injury were excluded (leaving those with medial meniscus injury or without meniscal injury), group 4 had significantly greater accelerations than other groups.

CONCLUSIONS

In ACL-deficient knees, rotational laxity increased with time and the increased rotational laxity was evident more than 1 year after injury whereas it increased with concomitant lateral meniscal injuries within 1 year after injury.

LEVEL OF EVIDENCE

Ⅳ, diagnostic study of nonconsecutive patients.

Knee laxity in anterolateral complex injuries versus lateral meniscus posterior horn injuries in anterior cruciate ligament deficient knees: A cadaveric study

BACKGROUND

In the anterior cruciate ligament (ACL) injured knee, additional injury of the anterolateral ligament (ALL) and capsule may increase the pathologic laxity. The purpose of this study was to compare the effects of the anterolateral complex (ALC) injury in ACL injured knee with the effects of lateral meniscus posterior horn (LMPH) meniscectomy.

METHODS

Ten fresh-frozen cadaveric knees were used. After testing the (1) intact knees and (2) ACL sectioned knees (ACL-), two groups were established: an (3) ALC sectioning group (n = 5), which underwent additional ALC sectioning (ACL-/ALC-) after ACL sectioning, and a separate (3) LMPH meniscectomy group (n = 5) that underwent LMPH meniscectomy (ACL-/LMPH-) after ACL sectioning. Knee laxity was measured in terms of internal-external rotation, anterior-posterior translation, and varus-valgus angulation for each condition at knee flexion angles of 0°, 30°, 60° and 90°.

RESULTS

After additional sectioning of the ALC (ACL-/ALC-), the mean internal rotation at 0, 30, 60 and 90° of knee flexion was 11.9 ± 1.3°, 18.1 ± 1.6°, 18.3 ± 1.8°, and 17.8 ± 2.4°, respectively, showing significant internal rotation laxity when compared to the intact knee (P = .031, .020, .001 and .033). Anterior translation also significantly increased compared to the ACL- knee at 30° (12.7 ± 1.4 to 16.8 ± 1.7 mm: P = .039). In contrast, additional meniscectomy of the LMPH (ACL-/LMPH-) significantly increased valgus laxity compared to the intact knee at 30, 60 and 90° (P = .021, .018 and .024).

CONCLUSION

These findings suggest that the anterolateral complex, which include the ALL and anterolateral capsule, may play an important role in stabilizing the knee against internal rotation and anterior translation.

Excessive Preoperative Anterior Tibial Subluxation in Extension Is Associated With Inferior Knee Stability After Anatomic Anterior Cruciate Ligament Reconstruction

BACKGROUND

Anterior tibial subluxation (ATS) in extension after anterior cruciate ligament (ACL) injury highlights an increased anterior position of the tibia relative to the femur. Recent studies demonstrated that subluxation is sometimes irreducible and the normal tibiofemoral relationship is not restored by ACL reconstruction (ACLR), which raises concerns regarding clinical outcomes after ACLR.

HYPOTHESIS

Excessive preoperative ATS in extension is associated with inferior knee stability after anatomic ACLR.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

From March 2016 to January 2017, a total of 487 consecutive patients with clinically diagnosed noncontact ACL injuries who underwent primary anatomic ACLR were retrospectively analyzed. Of these patients, 430 met the criteria for inclusion in this study. Anterior subluxation of the lateral and medial compartments (ASLC and ASMC) in extension relative to the femoral condyles was measured on preoperative magnetic resonance imaging. Twenty patients (study group) who demonstrated excessive (>10 mm) ASLC and ASMC in extension were matched 1:2 to 40 participants (control group) who showed minimal or no (<3 mm) ASLC and ASMC in extension. The amount of ASLC and ASMC in extension relative to the femoral condyles at 2 years postoperatively was the primary outcome. Moreover, the Lysholm score, IKDC grade (International Knee Documentation Committee), and stability assessments (pivot-shift test and KT-1000 arthrometer side-to-side difference) were evaluated preoperatively and at the last follow-up visit.

RESULTS

The preoperative mean ASLC and ASMC in extension of the study group were both significantly larger than those of the control group (study group vs control group: ASLC, 13.5 mm vs 1.2 mm; ASMC, 12.4 mm vs 1.0 mm; P < .05). Moreover, patients in the study group showed significantly larger posterior tibial slope than the patients in the control group (17.8°± 2.5° vs 9.5°± 1.5°; P < .05). At the final follow-up visit, the mean ASLC and ASMC of the study group were 8.1 mm and 7.3 mm, which were significantly larger than those of the control group (ASLC, 0.9 mm; ASMC, 0.7 mm; P < .05). In addition, the study group showed inferior knee stability when compared with the control group in terms of both the pivot-shift test (study group vs control group: 2 grade 2, 10 grade 1, and 8 grade 0 vs 1 grade 1 and 39 grade 0; P < .05) and the KT-1000 arthrometer side-to-side difference (study group vs control group: 4.4 ± 1.2 mm vs 1.5 ± 0.6 mm; P < .05). Furthermore, the study group showed significantly lower mean Lysholm score (study group vs control group: 80.3 ± 6.3 vs 93.3 ± 4.3, P < .05) and IKDC grading results (study group vs control group: 3 grade C, 16 grade B, and 1 grade A vs 3 grade B and 37 grade A; P < .05) as compared with the control group.

CONCLUSION

In this short-term study, the excessive (>10 mm) preoperative ATS in extension after ACL injury was associated with inferior knee stability after anatomic ACLR.

Triaxial accelerometer evaluation is correlated with IKDC grade of pivot shift

PURPOSE

The purpose of this study was to evaluate the correlation between tibial acceleration parameters measured by the KiRA device and the clinical grade of pivot shift. The secondary objective was to report the risk factors for pre-operative high-grade pivot shift.

METHODS

Two-hundred and ninety-five ACL deficient patients were examined under anesthesia. The pivot shift tests were performed twice by an expert surgeon. Clinical grading was performed using the International Knee Documentation Committee (IKDC) scale and tibial acceleration data was recorded using a triaxial accelerometer system (KiRA). The difference in the tibial acceleration range between injured and contralateral limbs was used in the analysis. Correlation coefficients were calculated using linear regression. Multivariate logistic regression was used to identify risk factors for high grade pivot shift.

RESULTS

The clinical grade of pivot shift and the side-to-side difference in delta tibial acceleration determined by KiRA were significantly correlated (r = 0.57; 95% CI 0.513-0.658, p < 0.0001). The only risk factor identified to have a significant association with high grade pivot shift was an antero-posterior side to side laxity difference > 6 mm (OR = 2.070; 95% CI (1.259-3.405), p = 0.0042).

CONCLUSION

Side-to-side difference in tibial acceleration range, as measured by KiRA, is correlated with the IKDC pivot shift grade in anaesthetized patients. Side-to-side A-P laxity difference greater than 6 mm is reported as a newly defined risk factor for high grade pivot shift in the ACL injured knee.

DIAGNOSTIC STUDY

Level II.

Risk factors for residual anterolateral rotational instability after double bundle anterior cruciate ligament reconstruction: Evaluation by quantitative assessment of the pivot shift phenomenon using triaxial accelerometer

BACKGROUND

Exact knowledge of risk factors for residual anterolateral rotatinoal instability (ALRI) after anterior cruciate ligament (ACL) reconstruction is limited. The purpose of this study was to analyse possible risk factors for ALRI after ACL reconstruction.

METHODS

Quantitative assessment of the pivot shift phenomenon by measuring tibial acceleration was performed in 46 patients during primary double-bundle ACL reconstructions. The absolute value of the acceleration of the injured knee after provisional fixation of the ACL grafts ('absolute residual acceleration') and the subtraction of the acceleration of the uninjured knee from absolute residual acceleration ('relative residual acceleration') were defined as indicators for residual ALRI. The associations between these indicators and nine candidate risk factors were analysed using univariate and multiple regression analyses.

RESULTS

Multiple regression analysis revealed that absolute residual acceleration was positively associated with both preoperative acceleration difference between injured and uninjured knees (β = 0.469, P < 0.001) and tibial acceleration of the uninjured knee (β = 0.597, P < 0.001). Relative residual acceleration was also positively associated with preoperative acceleration difference between injured and uninjured knees (β = 0.446, P< 0.001), but was negatively associated with tibial acceleration of the uninjured knee (β = -0.763, P < 0.001).

CONCLUSIONS

Patients with larger preoperative side-to-side difference of the pivot shift phenomenon have higher risk for both absolute and relative residual ALRIs after ACL reconstruction, whereas patients with larger pivot shift phenomenon in their uninjured knees are at higher risk for absolute residual ALRI but not for relative residual ALRI.

Diagnosis and treatment of rotatory knee instability

BACKGROUND

Rotatory knee instability is an abnormal, complex three-dimensional motion that can involve pathology of the anteromedial, anterolateral, posteromedial, and posterolateral ligaments, bony alignment, and menisci. To understand the abnormal joint kinematics in rotatory knee instability, a review of the anatomical structures and their graded role in maintaining rotational stability, the importance of concomitant pathologies, as well as the different components of the knee rotation motion will be presented.

MAIN BODY

The most common instability pattern, anterolateral rotatory knee instability in an anterior cruciate ligament (ACL)-deficient patient, will be discussed in detail. Although intra-articular ACL reconstruction is the gold standard treatment for ACL injury in physically active patients, in some cases current techniques may fail to restore native knee rotatory stability. The wide range of diagnostic options for rotatory knee instability including manual testing, different imaging modalities, static and dynamic measurement, and navigation is outlined. As numerous techniques of extra-articular tenodesis procedures have been described, performed in conjunction with ACL reconstruction, to restore anterolateral knee rotatory stability, a few of these techniques will be described in detail, and discuss the literature concerning their outcome.

CONCLUSION

In summary, the essence of reducing anterolateral rotatory knee instability begins and ends with a well-done, anatomic ACL reconstruction, which may be performed with consideration of extra-articular tenodesis in a select group of patients.

Anterior Cruciate Ligament Injury and the Anterolateral Complex of the Knee-Importance in Rotatory Knee Instability?

PURPOSE OF REVIEW

In the setting of rotatory knee instability following anterior cruciate ligament (ACL) reconstruction, there has been a resurgence of interest in knee's anterolateral complex (ALC). Reconstruction or augmentation of the ALC with procedures such as a lateral extra-articular tenodesis (LET) has been proposed to reduce rotatory knee instability in conjunction with ACL reconstruction. The current review investigates the recent literature surrounding the role of the ALC in preventing rotatory knee instability.

RECENT FINDINGS

The knee's anterolateral complex (ALC) is a complex structure composed of the superficial and deep portions of the iliotibial band, the capsulo-osseous layer, and the anterolateral capsule. Distally, these various layers merge to form a single functional unit which imparts stability to the lateral knee. While the iliotibial band and the capsule-osseous layer have been shown to be primary restraints to rotatory motion after ACL injury, the biomechanical role of the anterolateral capsule remains unclear. Biomechanical studies have shown that the anterolateral capsule and the anterolateral thickening of this capsule act as a sheet of fibrous tissue which does not resist motion around the knee as other longitudinally oriented ligaments do. Augmentation of the ALC, with LET, has been performed globally for over 30 years. This procedure can decrease rotatory knee instability, but long-term studies have found little difference in patient-reported outcomes, osteoarthritis, or ACL reconstruction failure with the addition of LET. Further research is needed to clarify indications for the clinical use of ALC-based procedures.

Steep lateral tibial slope and lateral-to-medial slope asymmetry are risk factors for concomitant posterolateral meniscus root tears in anterior cruciate ligament injuries

PURPOSE

To compare sagittal and coronal tibial slopes between anterior cruciate ligament (ACL) injured subjects with and without posterolateral meniscus root tear (PLRT).

METHODS

A chart review was conducted to identify patients with isolated ACL tears and patients with an associated PLRT. Patients with other concomitant injuries and patients who underwent surgery > 6 months after the injury were excluded. Magnetic resonance image data were used to compare the medial and lateral sagittal tibial slope (MTS and LTS), lateral-to-medial slope asymmetry (LTS-MTS), and coronal slope of the tibial plateau between both groups. Mean LTS and standard deviation (SD) of the control group were calculated, and a value of > mean + 1 SD was considered an abnormal LTS. Interobserver reproducibility was assessed by calculating interclass correlation coefficients (ICCs) of measurements independently obtained by two reviewers.

RESULTS

Fifty-nine patients met the in- and exclusion criteria. Thirty nine (66%) had an isolated ACL tear and 20 (34%) had an associated PLRT. Interrater ICCs for LTS, MTS, and coronal slope were 0.930, 0.884 and 0.825, respectively, representing good to excellent interobserver reproducibility. Patients with a PLRT had significantly steeper LTS (8.0 ± 3.2 vs. 4.0 ± 2.0; p < 0.001) and significantly greater difference of LTS-MTS (3.7 ± 2.9 vs. - 0.6 ± 2.0; p < 0.001). Furthermore, patients with abnormal LTS were significantly overrepresented among patients with PLRT (70% vs. 18%; p < 0.001). No significant difference between both groups was found for MTS and coronal slope.

CONCLUSION

A steep lateral tibial slope and lateral-to-medial slope asymmetry are risk factors for concomitant PLRT in ACL-injured subjects.

LEVEL OF EVIDENCE

IV, retrospective cohort study.

Magnetic Resonance Imaging Evaluation of the Anterolateral Ligament in Acute Anterior Cruciate Ligament Injuries in an Adolescent Population

PURPOSE

To evaluate the frequency of anterolateral ligament (ALL) injuries in acute anterior cruciate ligament (ACL) injuries in adolescent patients using magnetic resonance imaging (MRI) and characterize other potential intra- and extra-articular knee injuries that are associated with ALL injuries.

METHODS

Patients between 14 and 17 years of age with acute ACL injuries (trauma for <3 weeks before examination) were retrospectively evaluated with MRI over 24 months (January 2016-December 2017). Among this population, ALL was classified as not visible, normal, or injured. Injuries were separated into strains (partial injuries), complete injuries, or Segond fractures. Possible abnormalities of the menisci, collateral ligaments, popliteal tendon, posterior cruciate ligament (PCL), iliotibial tract (ITT), and bone injuries were evaluated. Associations were calculated between ALL injuries and injuries of these other knee structures, as well as age and gender.

RESULTS

ALL was visible in 171 of the 184 MRI-evaluated knees (92.9%). ALL was considered normal in 68 (39.8%) and damaged in 103 (60.2%) patients. ALL injuries were considered partial in 56 (54.4%) and total in 44 (42.7%) cases. Only 3 (2.9%) cases were Segond fractures. ALL injuries were associated with ITT (P < .0001), lateral meniscus (P = .04), lateral collateral ligament (P = .01), popliteal tendon (P = .001), and medial collateral ligament (P = .009) injuries, in addition to bone contusions in the lateral compartment of the knee (P < .0001). There was no correlation between ALL injuries and medial meniscus (P = .054) or PCL (P = .16) injuries.

CONCLUSIONS

MRI evaluation showed ALL injuries are present in 60.2% of acute ACL injuries in adolescent patients. These injuries are associated with the medial and lateral collateral ligaments, ITT, lateral meniscus injuries, and bone contusions, but they are not associated with medial meniscus or PCL injuries.

LEVEL OF EVIDENCE

Level IV, case series.

Patients With Failed Anterior Cruciate Ligament Reconstruction Have an Increased Posterior Lateral Tibial Plateau Slope: A Case-Controlled Study

PURPOSE

To compare knee anatomical parameters of patients with failed anterior cruciate ligament reconstruction (ACL-R) with those of a control group of sex-matched patients with successful ACL-R.

METHODS

Forty-three patients (34 male, 9 female) who experienced graft failure after ACL-R were enrolled in the failed group. These patients were matched to a control group of 43 patients who underwent primary ACL-R with a minimum follow-up of 24 months. On magnetic resonance imaging, the following parameters were evaluated: transepicondylar distance, lateral and medial femoral condyle widths, tibial plateau width, notch width index, and the ratio of width and height of the femoral notch, ratio between the height and depth of the lateral and medial femoral condyle, lateral and medial posterior tibial slopes, and anterior subluxation of the lateral and medial tibial plateau. Multivariate regression with backward elimination, including only the previously identified significant variables, defined the independent predictors for revision surgery.

RESULTS

The anatomical variables that were significantly different between the 2 study groups were lateral and medial posterior tibial slopes, anterior subluxation of the lateral and medial tibial plateau, medial tibial plateau width, lateral tibial plateau width, medial femoral condyle width, and transepicondylar distance; however, the multivariate regression analysis identified the lateral posterior tibial slope (LTPs), the anterior subluxation of the medial tibial plateau, and the medial femoral condyle width as significant independent predictors (P < .05). The LPTs had the highest coefficient and the highest sensitivity (88%) and specificity (84%) to identify failures when considering the optimal cutoff value of 7.4°.

CONCLUSIONS

Several anatomical parameters have been identified that differ significantly between patients with failed ACL-R and those without a documented failure. The most accurate predictor of ACL failure was an LTPs >7.4°, with a sensitivity of 88% and specificity of 84%. Surgeons should consider measuring LTPs during preoperative assessment of ACL-injured patients, and patients with values >7.4° should be considered at high risk of ACL-R failure.

LEVEL OF EVIDENCE

Level III retrospective prognostic trial.

The Pivot Shift: Current Experimental Methodology and Clinical Utility for Anterior Cruciate Ligament Rupture and Associated Injury

PURPOSE OF REVIEW

The purpose of this manuscript is to (1) examine the history, techniques, and methodology behind quantitative pivot shift investigations to date and (2) review the current status of pivot shift research for its clinical utility for management of anterior cruciate ligament (ACL) rupture with associated injuries including the anterolateral complex (ALC).

RECENT FINDINGS

The pivot shift is a useful physical exam maneuver for diagnosis of rotatory instability related to ACL tear. Recent evidence suggests that the pivot shift is multifactorial and can be seen in the presence of ACL tear with concomitant injury to secondary stabilizers or with predisposing anatomical factors. The presence of a pivot shift post-operatively is associated with poorer outcomes after ACL reconstruction. Recent clinical and biomechanical investigations can help guide clinicians in utilizing pivot shift in diagnosis and surgical planning. Further research is needed to clarify optimal management of ALC in addition to ACL injury.

Clinical Outcomes of Isolated Revision Anterior Cruciate Ligament Reconstruction or in Combination With Anatomic Anterolateral Ligament Reconstruction

BACKGROUND

Although the cause of rotational instability after revision anterior cruciate ligament reconstruction (ACLR) is multifactorial, the rationale of adding an extra-articular procedure is based on its ability to restrict rotational instability.

PURPOSE

To assess the effect of anterolateral ligament (ALL) reconstruction on revision ACLR.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 87 patients who underwent revision ACLR between March 2011 and July 2014 with a follow-up of more than 3 years were included in this retrospective study. Patients were divided into the isolated revision ACLR group (group I, n = 45, from March 2011 to January 2013) or the revision ACLR in combination with ALL reconstruction group (group C, n = 42, from February 2013 to July 2014). Subjective knee assessments including the subjective International Knee Documentation Committee (IKDC) form, Lysholm score, Tegner activity scale, and Anterior Cruciate Ligament-Return to Sport after Injury (ACL-RSI) scale were used. Clinical and functional tests were performed before surgery and at ≥6 months after surgery. All tests were usually completed at 36 months of follow-up.

RESULTS

The mean follow-up duration for groups I and C were 41.5 ± 8.2 and 38.2 ± 6.9 months, respectively ( P = .451). The subjective IKDC score, Tegner score, and ACL-RSI score were significantly better in group C compared with those in group I at the last follow-up (84.3 ± 18.5 vs 75.9 ± 19.2, 7.0 ± 0.8 vs 6.3 ± 0.7, and 69.5 ± 25.4 vs 51.9 ± 23.1, respectively), although they were not significantly different between the 2 groups at 12 months after surgery (79.2 ± 18.8 vs 76.7 ± 17.2, 6.7 ± 0.7 vs 6.5 ± 0.9, and 50.2 ± 24.6 vs 49.9 ± 25.1, respectively). There were no significant differences in KT-2000 arthrometer, isokinetic extensor strength, single-legged hop for distance, co-contraction test, or carioca test results between the 2 groups at the last follow-up ( P = .304, .068, .125, .056, and .066, respectively). Preoperatively, 43 (95.6%) patients in group I and 40 (95.2%) patients in group C had a grade 2 or 3 pivot shift ( P = .387). Postoperatively, 23 (53.5%) patients in group I and 38 (90.5%) patients in group C had a negative pivot shift ( P < .001). Group C showed a higher rate of return to the same level of sports activity than group I (57.1% vs 25.6%, respectively; P = .008), although there was no significant difference in the rate of return to any sports activity at the last follow-up (88.4% in group I vs 88.1% in group C; P = .713).

CONCLUSION

Revision ACLR in combination with ALL reconstruction significantly reduced rotational laxity and showed a higher rate of return to the same level of sports activity than revision ACLR alone, although there were no significant differences in anterior laxity or functional test results between the 2 groups.

Effect of meniscus repair on pivot-shift during anterior cruciate ligament reconstruction: Objective evaluation using triaxial accelerometer

BACKGROUND

Some types of meniscus tear, especially lateral meniscus tear, have been reported to be associated with rotatory knee laxity. However, precise information regarding the effect of meniscus repair on rotatory laxity is limited. The purpose of this study was to investigate the effects of lateral and medial meniscus repair on rotatory laxity in anterior cruciate ligament (ACL) injured knees.

METHODS

Forty-one patients who underwent ACL reconstruction were included in the study. The tibial acceleration during the pivot shift test was measured using a triaxial accelerometer preoperatively under anesthesia and intraoperatively before and after medial and lateral meniscus repair and ACL reconstruction during surgery. Effects of meniscus tear and its repair on rotatory laxity were analyzed.

RESULTS

Preoperative measurements revealed that patients with lateral meniscus tear showed significantly higher tibial acceleration compared to the patients without meniscus tear (P = 0.006). Intraoperative measurements revealed that medial and lateral meniscus repair significantly reduced tibial acceleration by 1.46 m/s² (P = 0.002) and 1.91 m/s² (P < 0.001), respectively.

CONCLUSION

In ACL injured knees, knees with lateral meniscus tear showed greater rotatory laxity compared to the knees without meniscus tear. In addition, lateral meniscus repair, and to a lesser degree medial meniscus repair, reduced rotatory laxity during ACL reconstruction surgery. Therefore, the meniscus should be repaired as much as possible for its role as a secondary stabilizer of rotatory laxity. Besides, the effect of meniscus repair on rotatory laxity should be considered when the indication of anterolateral augmentation is determined.

Risk factors for residual pivot shift after anterior cruciate ligament reconstruction: data from the MAKS group

PURPOSE

To investigate the risk factors for residual pivot shift test after anterior cruciate ligament (ACL) reconstruction based on a multicenter prospective cohort study.

METHODS

This study included patients who were registered in the Multicenter Arthroscopic Knee Surgery Study, a prospective longitudinal multicenter cohort study, and who underwent primary ACL reconstruction using autologous hamstring tendon graft between 2013 and 2016. The exclusion criteria included prior injuries or surgeries in the contralateral knee, prior ligamentous injuries in the involved knee, grade 2 or 3 concomitant ligament injuries, and inflammatory or other forms of osteoarthritis. Data from the preoperative period and at 1-year follow-up were used for further analysis, and patients with incomplete data, re-injury and loss to follow-up were also excluded. Logistic regression analysis was conducted with age, gender, Lachman test, pivot shift test, KT measurement, hyperextension, single-bundle vs. double-bundle, meniscus injury sites, and meniscus treatments as the independent variables, and postoperative pivot shift test was used as the dependent variable.

RESULTS

Three hundred and sixty-eight patients were included in the study. Hyperextension knee (P = 0.025) and a preoperative pivot shift test under anesthesia (P = 0.040) were identified as risk factors for a postoperative pivot shift via logistic regression analysis. There were no statistically significant differences in the other variables.

CONCLUSIONS

The results from a multicenter cohort study indicated that knee hyperextension and greater preoperative pivot shift under anesthesia were risk factors for residual pivot shift at 1 year after ACL reconstruction. In cases with a preoperative high-grade pivot shift and knee hyperextension, additional anterolateral structure augmentation might be considered in order to eliminate pivot shift and eventually obtain better outcomes after ACL reconstruction.

LEVEL OF EVIDENCE

II.

Greater Laxity in the Anterior Cruciate Ligament-Injured Knee Carries a Higher Risk of Postreconstruction Pivot Shift: Intraoperative Measurements With a Navigation System

BACKGROUND

The presence of pivot shift after anterior cruciate ligament (ACL) reconstruction is correlated with worse clinical outcomes. An orthopaedic navigation system is a useful tool for quantifying laxity in the ACL-deficient knee.

PURPOSE

To investigate the relationship between preoperative knee laxity measured by a navigation system and postoperative pivot shift (PPS) after ACL reconstruction.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

One hundred patients who underwent primary ACL reconstruction (62 hamstring tendon grafts, 38 patellar tendon grafts) were grouped according to the presence or absence of pivot shift at the 2-year follow-up, and the groups were compared retrospectively. Before surgery, knee laxity was assessed with a navigation system to quantify posterior tibial reduction (PTR) during pivot-shift tests and anterior tibial translation (ATT) during Lachman tests. PTR and ATT cutoff values were determined by receiver operator characteristic (ROC) analysis.

RESULTS

Preoperative PTR and ATT were significantly larger for patients with PPS (PPS-positive group) than those without (PPS-negative group). In the ROC analysis, the PTR had an area under the curve of 0.871 (95% CI, 0.763-0.979; P < .0001) for predicting a PPS; this was larger than that obtained for the ATT, which had an area under the curve of 0.825 (95% CI, 0.705-0.946; P = .001). Because the ROC curve of the ATT had 2 peaks, the ATT alone was not a suitable predictor for PPS. Based on the ROC curve, the optimal PTR cutoff value was 7 mm, with 88.9% sensitivity and 71.4% specificity for PPS (adjusted odds ratio = 19.7; 95% CI, 2.1-187.9; P = .009). Setting the cutoff value as a combination of the PTR (≧7 mm) and ATT (≧12 mm) improved the specificity (88.9% sensitivity and 84.6% specificity; adjusted odds ratio = 149.8; 95% CI, 5.9-3822.7; P = .002) over that with the PTR alone.

CONCLUSION

ACL injuries in knees with a large PTR had a higher risk of PPS. When reconstructing the ACL in a knee with a high degree of laxity, surgeons may need to adopt strategies to prevent PPS.