Grading the pivot shift. Objective tests with implications for treatment

Compressive force and valgus torque are the predominant applied loads during the pivot shift exam: An in vitro study

PURPOSE

Despite the clinical utility of the pivot shift exam, the requisite applied forces and torques to elicit a pivot shift remain unclear. The purposes of this study are (1) to identify the greatest forces and torques applied to the knee during the pivot shift exam and (2) to evaluate if the applied loads differ among experienced surgeons.

METHODS

Three cadaveric hemipelvis-to-toe specimens (ages 53, 36 and 31 years; two males and one female) with no history of knee or hip injury were utilized. The experimental setup consisted of securing the hemipelvis to a mounting frame via an external fixator to simulate patient positioning during the clinical exam. The hemipelvis, femur, and tibia were spatially tracked by motion capture and the applied loads were measured using a 6-axis force-torque sensor. After sectioning the anterior cruciate ligament (ACL), three board-certified sports medicine surgeons then performed the pivot shift exam on each specimen utilizing their preferred technique. Forces (compression-distraction, anterior-posterior, and medial-lateral) and torques (varus-valgus, internal-external rotation, and flexion-extension) applied to the knee joint immediately preceding the reduction of the proximal lateral tibia during each pivot shift exam were calculated.

RESULTS

Compression was the largest applied force averaging 95 N ± 15 N for all surgeons and knees, which was at least 4.5 times greater, on average, than the applied anterior and applied medial tibial forces (p < 0.0001). Valgus was the largest of the three applied torques, averaging 8.5 ± 2.1 Nm. Internal rotation torque was 3.7 times less, on average, than the applied valgus torque (p < 0.0001). Each surgeon applied compressive force. However, anterior force was more variable among surgeons, with one of the three surgeons applying minimal anterior force (p ≤ 0.024). The magnitude of applied torques was similar among examiners (n.s.).

CONCLUSION

Compressive force and valgus torque were the predominant applied loads during the pivot shift exam. A lower magnitude of internal rotation torque was also applied. The anterior force was not consistently applied among examiners. These data can better inform clinical, cadaveric, and computational studies utilizing the pivot shift exam to assess knee biomechanics and can be used to educate trainees in conducting this complex manoeuvre.

LEVEL OF EVIDENCE

N/A.

No difference in clinical outcome between quadriceps tendon anterior cruciate ligament reconstruction with and without bone block: Results from the Danish Knee Ligament Registry

PURPOSE

The quadriceps tendon (QT) has recently gained increasing interest as an anterior cruciate ligament reconstruction (ACLR) graft due to minimally invasive harvesting techniques and low donor site morbidity. QT grafts can be used both with a patella bone block and as complete soft tissue grafts. However, it is unknown whether the QT graft type affects clinical outcomes. This study used data from the Danish Knee Ligament Reconstruction Registry (DKRR) to compare revision rates, knee stability and subjective clinical outcomes in patients who underwent ACLR with QT graft with bone block (QT-B) or soft tissue only (QT-S).

METHODS

Patients who underwent primary ACL reconstruction with QT autografts documented in the DKRR were included and divided into the QT-B (n = 925) and QT-S (n = 659) groups. The clinical outcome was evaluated using objective-instrumented knee stability, pivot shift test, knee injury osteoarthritis outcome score (KOOS) and Tegner activity scores for the two cohorts performed at the 1-year follow-up. The overall revision rates were determined as well.

RESULTS

Revision rates at 2 years were equally low in both graft groups at 2.8%. Similarly, post-operative knee laxity was equal at 1.5 (1.4) and 1.6 (1.4) mm side-to-side laxity, respectively. However, QT-B exhibited a reduced post-operative positive pivot shift of 22% compared with 31% for QT-S. Although the subjective outcomes were equal for the KOOS and Tegner activity scale scores at the 1-year follow-up, reduced improvements in KOOS were observed for QT-B compared to QT-S.

CONCLUSION

ACL with a QT autograft harvested either with a bone block or as a soft tissue graft exhibited comparable revision rates and sagittal knee stability. Furthermore, ACL reconstruction using a QT graft with a bone block achieved better rotational stability with less pivot shift than ACL reconstruction using complete soft tissue QT grafts.

LEVEL OF EVIDENCE

Level III.

Lateral extrarticular tenodesis enhances outcomes in primary anterior cruciate ligament repair with knotless anchor: 24-Month minimum follow up

BACKGROUND

Previous studies have shown that primary repair of proximal ligament avulsion from the femoral condyle may have reasonable recovery and stability rates after repair. As a result, selecting patients more narrowly and more specifically has been recognized to improve short- and medium-term outcomes.

PURPOSE

This study aimed to assess the potential benefits of primary repair for acute anterior cruciate ligament (ACL) tears with a proximal tear and to evaluate the effect of performing lateral extraarticular tenodesis (LET) in addition to primary repair on patient outcomes.

STUDY DESIGN

Retrospective cohort study.

METHODS

This study was a retrospective cohort study. Thirty-eight patients between the ages of 21 and 40 years who underwent ACL repair surgery within the first 3 weeks after injury due to Sherman type 1 proximal ACL tears were evaluated. Group 1 (n = 18) underwent only primary ACL repair with knotless anchor, while Group 2 (n = 20) had LET with iliotibial band autograft in addition to primary repair. Patients were evaluated using various tests and scoring systems at 6, 12, and 24 months postoperatively.

RESULTS

There was no statistically significant difference between the groups in preoperative and postoperative 6- and 12-month visual analog scale (VAS) scores (P >0.05). However, the 24-month VAS score of Group 1 was statistically significantly higher than that of Group 2 (P <0.05). The preoperative International Knee Documentation Committee (IKDC) score of Group 1 was statistically significantly higher than that of Group 2 (p: 0.004; P <0.05). Group 1 had statistically significantly lower IKDC scores at postoperative 6, 12, and 24 months than Group 2. Similarly, Group 1 had statistically significantly lower Single Assessment Numeric Evaluation (SANE) and Tegner-Lysholm scores at postoperative 6, 12, and 24 months than Group 2 (P <0.05). The occurrence rate of Lachman positivity in the preoperative period was 28.6% in Group 1 and 33.3% in Group 2.

CONCLUSION

Our study suggests that performing LET with iliotibial band autograft in addition to primary ACL repair may lead to better outcomes in terms of pain relief, knee function, and stability compared with primary ACL repair alone.

Posterior Cruciate Buckling Angle Variations Are Associated with Different Patterns of Medial Meniscus Tears in Anterior-Cruciate-Deficient Knees: Results of a Prospective Comparative Magnetic Imaging Resonance Study

BACKGROUND

The diagnosis of anterior cruciate ligament (ACL) tear relies on clinical evaluation and magnetic resonance imaging (MRI). Direct and indirect signs of ACL tear have been described with MRI evaluation. Posterior cruciate ligament (PCL) buckling has been described as an indirect radiographic sign of an ACL tear.

PURPOSE

The aim of the present study was to assess the variations in PCL buckling angles in patients with ACL tears and in patients with isolated lesions in the posterior horn of the medial meniscus. In addition, the influence of different patterns of medial meniscus tears in ACL-deficient knees was investigated. Finally, the influences of risk factors such as tibial slope, delay from injury to surgery, absence of medial meniscus tear, degree of Lachman and pivot shift testing were also assessed.

STUDY DESIGN

This was a cohort study.

METHODS

A total of 154 patients (78 in the group with ACL tear and 76 in the control group) were assessed with MRI and lateral weight-bearing X-ray to assess PCL buckling angle and tibial slope by two independent observers. The presence of a medial meniscus bucket handle or ramp lesion of the medial meniscus was assessed and recorded at the time of surgery.

RESULTS

PCL buckling angle measurement was highly reliable, with an ICC of 0.866 and 0.894, respectively, in the study group and the control group for interobserver reliability. The intrarater reliability was found to be high in PCL buckling angle for the study group [ICC = 0.955] and the control group [ICC = 0.943]. The mean angle in patients with ACL tear was 110.7 ± 15.2° and 115.3 ± 16.2° (for the two examiners) and 111.4 ± 12° and 114 ± 14.5° (for the two examiners) in patients with an intact, healthy ACL. An association emerged between bucket handle tears of the medial meniscus (p = 0.010) and a decreased PCL buckling angle and between ramp lesions of the medial meniscus and increased PCL buckling angle both (p = 0.024).

CONCLUSIONS

Good inter- and intraobserver reliability for the measurement of the PCL buckling angle was observed. Increased PCL buckling angle values were observed in patients with concomitant ACL and bucket handle tears of the medial meniscus, while decreased angle values were observed in those who had ACL tear and ramp lesion of the medial meniscus. No statistically significant difference in the PCL buckling angle emerged between patients with ACL tears and those who had a healthy, intact ACL.

Effect of anterior cruciate ligament injury on acceleration response of knee joint

This study investigated the effect of anterior cruciate ligament (ACL) injury on relative acceleration of the tibia and femur during a number of tests/activities, in order to assess the feasibility of acceleration-based diagnosis of ACL injury using inertial sensors. First, a detailed finite element model of the knee joint was developed to simulate the target tests/activities, and identify those in which a large difference between the maximum acceleration peaks (MAPs) of the healthy and ACL injured knees is likely to be observed. The promising tests/activities were entered in an experimental study, where the relative accelerations of the tibiae and femurs of 20 individuals with unilateral ACL injury, allocated randomly to two groups of conscious and unconscious test conditions, were recorded. Model predictions indicated MAP ratios>1.5 for the ACL-injured to healthy knees, during the anterior drawer, Lachman, and pivot-shift tests, as well as the lunge activity. The experimental MAP results indicated acceptable test-retest reliabilities for all tests (coefficient of variation<0.25), and significant MAP differences (p < 0.05) in the anterior drawer and pivot-shift tests, in both coconscious and unconscious conditions. The individualized MAP results indicated side-to-side differences>2 m/s2 for all subjects during unconscious pivot shift tests, and >0.5 m/s2 for eight cases out of ten during conscious anterior drawer tests. It was concluded that the pivot shift test had a great repeatability and discriminative ability for acceleration-based diagnosis of ACL injury in unconscious condition. For the conscious condition, however, the anterior drawer test was appeared to be most promising.

The Value of Ultrasound Diagnostic Imaging of Anterior Crucial Ligament Tears Verified Using Experimental and Arthroscopic Investigations

This study investigates the potential of the ultrasound imaging technique in the assessment of Anterior Cruciate Ligament (ACL) pathologies by standardizing the examination process. We focused on four key ultrasound parameters: the inclination of the ACL; swelling or scarring at the ACL's proximal attachment to the lateral femoral condyle; swelling or scarring of the ACL/posterior cruciate ligament (PCL) compartment complex with accompanying morphological changes in the posterior joint capsule; and dynamic instability, categorized into three ranges-0-2 mm, 3-4 mm, and ≥5 mm. The study group consisted of 25 patients with an ACL injury and 25 controls. All four tested parameters were found more frequently in the study group compared to the control (p < 0.0001). Our findings suggest that this standardized approach significantly augments the diagnostic capabilities of ultrasound, complementing clinical evaluation and magnetic resonance imaging (MRI) findings. The meticulous assessment of these parameters proved crucial in identifying subtle ACL pathologies, which might otherwise be missed in conventional imaging modalities. Notably, the quantification of dynamic instability and the evaluation of morphological changes were instrumental in early detection of ACL injuries, thereby facilitating more precise and effective treatment planning. This study underscores the importance of a standardized ultrasound protocol in the accurate diagnosis and management of ACL injuries, proposing a more comprehensive diagnostic tool for clinicians in the field of sports medicine and orthopedics.

Pivot Shift Syndrome of the Knee

The pivot shift test, in contrast to the Lachman or anterior drawer, is a manually subjective clinical test that simulates the injury mechanism. It is the most sensitive test to determine ACL insufficiency. This paper reviews the history, development, research, and treatment associated with the pivot shift phenomenon which is associated with tearing and loss of function of the knee anterior cruciate ligament. The pivot shift test most closely recapitulates what the symptomatic anterior cruciate ligament deficient patient feels is happening which is an abnormal translation and rotation of the injured joint during flexion or extension. The test is best conducted in the relaxed patient by applying knee flexion, tibial external rotation, and valgus stress. The pivot shift biomechanics and treatment measures are reviewed.

A comparison of the outcomes of anterior curciate ligament reconstruction with large-size graft versus reconstruction with average-size graft combined with extraarticular tenodesis

INTRODUCTION

Many patients who have had anterior cruciate ligament (ACL) reconstruction (R) complain of instability, inability to return to previous levels of sports activity, and possible ACL graft failure. Graft size was discovered to be an important factor in lowering ACL failure rates. Also, extraarticular tenodesis decreases recurrent instability, A comparative study was done to compare the effect of graft size and lateral external tenodesis on the recurrence of instability after ACL-R.

PATIENTS AND METHODS

A Prospective Blinded Randomized Controlled study included 100 consecutive patients who underwent ACL-R with hamstring tendon grafts in our Hospital. The patients were allocated into two groups (Group A and B) with randomization; group A received ACL-R with a large-size ACL-graft diameter of 6 strands, and group B received ACL-R of 4 strands combined with lateral extraarticular tenodesis (LET) (Modified Lemaire). Each group had fifty patients. The follow-up time was two years. They were examined for graft failure, anterolateral rotatory instability with the pivot shift test, and clinical outcomes, which were evaluated with the International Knee Documentation Committee score (IKDC) both subjective and objective.

RESULTS

In this study; group A, graft failure occurred in three (6.3%) patients, a positive pivot shift test grade I was detected in eight (17.8%) patients, grade II in three (6.7%) patients, and grade III in one (2.2%) patient. The subjective IKDC score was 87.9 (± 7.19) points. The objective IKDC score was normal or nearly normal in 43 (93.4%) patients. In group B, one (2.1%) patient had graft failure, five (10.9%) had a positive pivot shift test grade I, one (2.1%) had a grade II, and no patient had a grade III. The subjective IKDC score was 91.9 (± 8.9) points. The objective IKDC score was normal or nearly normal in 44 (95.6%) patients. As regard the subjective IKDC score, there was a non-significant difference between both groups (p value = 0.465).

CONCLUSION

Both groups showed a low ACL-graft failure rate, low anterolateral rotatory instability, and a good clinical outcome. Although there was no significant difference in subjective IKDC score between both groups, the failure rate and anterolateral rotatory instability were significantly lower in the ACL-R (4 strands) with LET combination group than in the group with the large-diameter (6 strands) graft.

LEVEL OF EVIDENCE

Level 1; Randomized Comparative Study.

Reliable ligamentous stability and high return-to-sport rates after arthroscopic reduction and internal fixation of tibial eminence fractures

PURPOSE

To investigate functional and clinical outcomes, and physical activity after arthroscopic suture fixation of tibial eminence fractures with regard to postoperative stability, range of motion (ROM), complications, and return to sports.

METHODS

Patients undergoing arthroscopic reduction and internal fixation (ARIF) of tibial eminence fractures using a suture fixation technique were included. Outcome was evaluated retrospectively after a minimum follow-up of 24 months using KT-1000 arthrometer measurements, clinical examination, outcome scores (Lysholm score, Tegner Activity Scale), and a questionnaire about sport activities.

RESULTS

A total of 23 patients (44% male, 57% female) with a mean age of 25 ± 15 years were included. Mean follow-up was 57 ± 25 months. KT-1000 arthrometer measurements of anterior tibial translation revealed a mean side-to-side difference of 0.9 ± 1.0 mm. Clinical examination showed 100% normal or nearly normal anterior translation of the tibia. Two patients (9%) received an ACL reconstruction due to traumatic ACL re-instability and were, therefore, considered as failures. An extension deficit concerning hyperextension occurred in 29% of patients postoperatively. Further postoperative complications occurred in 14% of patients and included postoperative stiffness with ROM limitations and secondary dislocation of a fragment. Mean postoperative Lysholm score was 89 ± 14. Comparing pre- and postoperative values, no significant change of the Tegner Activity Scale was observed. All patients (failures excluded) returned to high impact sports activities after ARIF.

CONCLUSION

Excellent reliable ligamentous stability and high rates of return to high impact sports can be expected after ARIF using a suture fixation technique for type II-IV tibial eminence fractures. Complications, such as limitations in ROM, commonly occur in up to 30% after ARIF. Therefore, regular follow-up examinations remain important in this usually young patient cohort.

LEVEL OF EVIDENCE

Level IV.

Anatomic Factors Associated With the Development of an Anterior Cruciate Ligament Rerupture in Men: A Case-Control Study

BACKGROUND

Although several factors are associated with anterior cruciate ligament (ACL) rerupture, the effect of anatomic factors associated with ACL rupture on ACL rerupture development has not been evaluated.

PURPOSE

To determine individual anatomic parameters independently associated with ACL rerupture and the diagnostic values of these parameters.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

A total of 91 male patients with ACL rerupture and 182 age-, sex-, body mass index-, and side dominance-matched patients without rerupture who underwent ACL reconstruction with a 5-year follow-up were included. In all, 35 parameters that were previously defined as risk factors for primary ACL rupture were compared between the 2 groups. Uni- and multivariate logistic regression models were created to evaluate independently associated factors. Receiver operating characteristic curve analysis was performed for independently associated parameters to predict sensitivity, specificity, and cutoff values.

RESULTS

The mean ± standard deviation age of patients at the time of index surgery was 26.5 ± 6.7 years. Notch shape index (P = .014), tibial proximal anteroposterior (AP) distance (TPAPD) (P < .001), lateral femoral condylar AP distance (LCAPD)/TPAPD ratio (P < .001), medial meniscal cartilage bone height (P < .001), and lateral meniscal bone angle (P = .004) were found to be significantly different between the 2 groups. Only the LCAPD/TPAPD ratio (odds ratio, 2.713; 95% CI, 1.998-5.480; P < .001) was found to be independently associated with ACL rerupture development. The LCAPD/TPAPD ratio revealed 78.9% sensitivity and 75.5% specificity (area under the curve, 0.815; 95% CI, 0.760-0.870) for values above 1.52.

CONCLUSION

The LCAPD/TPAPD ratio can be used to distinguish patients who are at risk of developing ACL rerupture from patients who are not. In the clinical practice, findings of this study may help to develop surgical and nonsurgical preventive strategies in ACL rerupture development.

Increased Rotatory Laxity after Anterolateral Ligament Lesion in Anterior Cruciate Ligament- (ACL-) Deficient Knees: A Cadaveric Study with Noninvasive Inertial Sensors

The anterolateral ligament (ALL) has been suggested as an important secondary knee restrain on the dynamic laxity in anterior cruciate ligament- (ACL-) deficient knees. Nevertheless, its kinematical contribution to the pivot-shift (PS) phenomenon has not been clearly and objectively defined, and noninvasive sensor technology could give a crucial contribution in this direction. The aim of the present study was to quantify in vitro the PS phenomenon in order to investigate the differences between an ACL-deficient knee and an ACL+ALL-deficient knee. Ten fresh-frozen paired human cadaveric knees (n = 20) were included in this controlled laboratory study. Intact, ACL-deficient, and ACL+ALL-deficient knees were subjected to a manual PS test quantified by a noninvasive triaxial accelerometer (KiRA, OrthoKey). Kinematic data (i.e., posterior acceleration of the tibial lateral compartment) were recorded and compared among the three statuses. Pairwise Student's t-test was used to compare the single groups (p < 0.05). Intact knees, ACL-deficient knees, and ACL+ALL-deficient knees showed an acceleration of 5.3 ± 2.1 m/s², 6.3 ± 2.3 m/s², and 7.8 ± 2.1 m/s², respectively. Combined sectioning of ACL and ALL resulted in a statistically significant acceleration increase compared to both the intact state (p < 0.01) and the ACL-deficient state (p < 0.01). The acceleration increase determined by isolated ACL resection compared to the intact state was not statistically significant (p > 0.05). The ALL sectioning increased the rotatory laxity during the PS after ACL sectioning as measured through a user-friendly, noninvasive triaxial accelerometer.

Low surgical routine increases revision rates after quadriceps tendon autograft for anterior cruciate ligament reconstruction: results from the Danish Knee Ligament Reconstruction Registry

PURPOSE

Recent registry data have demonstrated a higher revision rate of quadriceps tendon (QT) graft compared with hamstring tendon (HT) and patellar tendon (PT) grafts. Clinic routines could be an important factor for revision outcomes. The purpose of this study is to use the Danish Knee Ligament Reconstruction Registry (DKRR) to compare revision rates in patients who have undergone ACLR with QT, HT and PT grafts related to individual clinic surgical routine.

METHODS

Data on primary ACLRs entered in the DKRR from 2012 through 2019 were analysed since QT graft usage started in 2012. Revision rates for QT, HT and PT grafts were compared according to clinic activity (0-100 and > 100 procedures). Revision rates for the three autograft cohorts are presented, as well as adjusted revision hazard rates. Instrumented knee stability and pivot-shift tests were performed at a one-year follow-up.

RESULT

QT revision rate (6.4%) for low-activity clinics was higher than for high-activity clinics (2.9%) (p = 0.003). The adjusted revision hazard ratio for low-activity clinics was 2.3 (p = 0.01). QT autograft was associated with statistically significant, increased side-to-side laxity at follow-up (1.4 mm) compared with HT and PT autografts (1.0 mm) (p < 0.01), as well as an increased positive pivot-shift rate.

CONCLUSION

QT autografts for ACLR were associated with higher revision rates in clinics with lower than 100 procedures performed from 2012 to 2019. QT graft usage is not associated with a high revision rate when routinely performed. Learning curve is an important factor when introducing QT ACLR.

LEVEL OF EVIDENCE

Level III.

Effect of Tibial Tunnel Placement Using the Lateral Meniscus as a Landmark on Clinical Outcomes of Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction

BACKGROUND

It remains unclear if use of the lateral meniscus anterior horn (LMAH) as a landmark will produce consistent tunnel positions in the anteroposterior (AP) distance across the tibial plateau.

PURPOSE

To evaluate the AP location of anterior cruciate ligament (ACL) reconstruction tibial tunnels utilizing the LMAH as an intra-articular landmark and to examine how tunnel placement affects knee stability and clinical outcomes.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A retrospective review was conducted of 98 patients who underwent primary ACL reconstruction with quadrupled hamstring tendon autografts between March 2013 and June 2017. Patients with unilateral ACL injuries and a minimum follow-up of 2 years were included in the study. All guide pins for the tibial tunnel were placed using the posterior border of the LMAH as an intra-articular landmark. Guide pins were evaluated with the Bernard-Hertel grid in the femur and the Stäubli-Rauschning method in the tibia. Patients were divided by the radiographic location of the articular entry point of the guide pin with relation to the anterior 40% of the tibial plateau. Outcomes were evaluated by the Marx Activity Scale and International Knee Documentation Committee (IKDC) form. Anterior knee laxity was evaluated using a KT-1000 arthrometer and graded with the objective portion of the IKDC form. Rotational stability was evaluated using the pivot-shift test.

RESULTS

A total of 60 patients were available for follow-up at a mean 28.6 months. The overall percentage of AP placement of the tibial tunnel was 39.3% ± 3.8% (mean ± SD; range, 31%-47%). Side-to-side difference of anterior knee laxity was significantly lower in the anterior group than the posterior group (1.2 ± 1.1 mm vs 2.5 ± 1.3 mm; P < .001; r = 0.51). The percentage of AP placement of the tibial tunnel demonstrated a positive medium correlation with side-to-side difference of anterior knee laxity as measured by a KT-1000 arthrometer (r = 0.430; P < .001). The anterior group reported significantly better distribution of IKDC grading as compared with the posterior group (26 grade A and 6 grade B vs 15 grade A and 13 grade B; P = .043; V = 0.297). The pivot-shift test results and outcome scores showed no significant differences between the groups.

CONCLUSION

Using the posterior border of the LMAH as an intraoperative landmark yields a wide range of tibial tunnel locations along the tibial plateau, with anterior placement of the tibial tunnel leading toward improved anterior knee stability.

Anterolateral ligament reconstruction improves the clinical and functional outcomes of anterior cruciate ligament reconstruction in athletes

PURPOSE

To compare the outcomes of anterior cruciate ligament (ACL) reconstruction with those of combined ACL and anterolateral ligament (ALL) reconstruction in ACL-deficient knees. The objective of this study was to improve knowledge regarding the treatment of ACL-deficient knees with combined ACL and ALL reconstruction. Combined ACL and ALL reconstruction has been hypothesized to result in better clinical and functional outcomes than isolated ACL reconstruction (ACLR).

METHODS

One-hundred and seven adult male athletes with ACL tears and high-grade pivot shifts were randomized into two groups. Those in group A (n = 54) underwent ACLR, while those in group B (n = 53) underwent combined ACL and ALL reconstruction. The median age was 26 (18-40) and 24 (18-33) years in groups A and B, respectively, and the median follow-up was 60 (55-65) months. Physical examination findings, instrumented knee laxity tested using a KT-1000 arthrometer, and International Knee Documentation Committee Scale (IKDC) scores were used to evaluate the outcomes.

RESULTS

One-hundred and two patients were available for follow-up: 52 in group A and 50 in group B. Postoperatively, the pivot shift was normal in 43 (82.7%) and 48 (96%) patients in groups A and B, respectively (p < 0.001). The median instrumented knee laxity was 2.5 ± 0.7 (1.2-6.1) mm in patients in group A and 1.2 ± 0.7 (1.2-3.2) mm in patients in group B (p < 0.001). Additionally, 44 (84.6%) patients in group A had normal IKDC scores and 3 (5.8%) had nearly normal scores, while 48 (96.0%) patients in group B had normal IKDC scores and 2 (4%) had nearly normal scores (p < 0.001).

CONCLUSION

Combined ACL and ALL reconstruction, compared with isolated ACLR resulted in favourable clinical and functional outcomes, as demonstrated by decreased rotational instability and instrumented knee laxity, a lower graft rupture rate and better postoperative IKDC scores.

LEVEL OF EVIDENCE

1.

Femoral and tibial bone bruise volume is not correlated with ALL injury or rotational instability in patients with ACL-deficient knee

PURPOSE

Some researchers have suggested that bone bruises are evidence of rotational instability. The hypothesis was that the extent of lateral bone edema is correlated with the presence of an anterolateral ligament (ALL) injury. The main objective was to determine whether there was a correlation between the presence of an ALL injury the extent of bone bruises.

METHODS

A prospective diagnostic study enrolled all the patients who suffered an acute anterior cruciate ligament (ACL) who were operated on within 8 weeks. The extent of bone bruising according to the ICRS classification was measured on preoperative MRIs by two independent blinded raters twice with an interval of 4 weeks. Dynamic ultrasonography (US) to look for ALL injury and the pivot shift test were performed before the ACL surgery. The correlation between ALL injury and bone bruises, and the correlation between an ALL injury and a high-grade pivot shift test were determined.

RESULTS

Sixty-one patients were included; 52% of patients had an ALL injury on US. The extent of lateral bone bruise was not related to the presence of an ALL injury, nor related to the presence of a high-grade pivot shift. A grade 2 or 3 pivot shift was significantly correlated with an ALL injury (p < 0.0001). Inter- and intra-rater reliability for the bone bruise rating was excellent.

CONCLUSION

The extent of lateral bone bruise is not correlated with ALL injury or a high-grade pivot shift; thus, it is not correlated with rotational instability of the knee.

LEVEL OF EVIDENCE

II.

The Lateral Femoral Notch Sign Is Correlated With Increased Rotatory Laxity After Anterior Cruciate Ligament Injury: Pivot Shift Quantification With A Surgical Navigation System

BACKGROUND

The lateral femoral notch sign (LNS) is a bony impression on the lateral femoral condyle correlated with anterior cruciate ligament (ACL) injury. Its presence is associated with lateral meniscal injury and higher cartilage degradation on the lateral femoral condyle.

PURPOSE/HYPOTHESIS

The purpose was to investigate the effect of the presence and magnitude of LNS on rotatory instability. The hypothesis was that a positive LNS is correlated with a high-grade pivot shift (PS).

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A total of 90 consecutive patients with complete ACL tears between 2013 and 2017 underwent intraoperative kinematic evaluation with the surgical navigation system and were included in the present study. The same surgeon performed a standardized PS under anesthesia. The PS was quantified through the acceleration of the lateral compartment during tibial reduction (PS ACC) and the internal-external rotation (PS IE). Presence and depth of LNS were evaluated on sagittal magnetic resonance images (1.5-T).

RESULTS

In 47 patients, the LNS was absent; in 33, the LNS depth was between 1 mm and 2 mm; and in 10 patients, it was deeper than 2 mm. Patients with a notch deeper than 2 mm showed increased PS ACC and PS IE compared with the group without the LNS. However, no significant differences were present between the group with a notch between 1 and 2 mm and the patients without LNS. Receiver operating characteristic curve analysis showed that 2 mm was the most predictive cutoff value to identify the "high-grade rotatory instability" group, with an accuracy of 77.8% and 74.4% and a specificity of 95.5% and 93.9% referred to the PS ACC and PS IE, respectively.

CONCLUSION

The presence of a lateral LNS deeper than 2 mm could be used for the preoperative identification of patients with a high risk of increased rotatory instability.

Is the KiRA Device Useful in Quantifying the Pivot Shift in Anterior Cruciate Ligament-Deficient Knees?

Background:

Various technologies have been developed to quantify the pivot shift, as it is regarded as a key indicator of anterolateral rotatory laxity of the knee.

Purpose:

To determine the usefulness of a commercially available triaxial accelerometer (Kinematic Rapid Assessment [KiRA]) in numerically quantifying the pivot shift in patients under anesthesia with an anterior cruciate ligament (ACL)–deficient knee.

Study Design:

Cohort study (diagnosis); Level of evidence, 3.

Methods:

Both knees of 50 patients (26 male [mean age, 30.4 years], 24 female [mean age, 26.6 years]) under anesthesia were assessed immediately before unilateral ACL reconstruction by an orthopaedic fellow and 1 of 3 experienced knee surgeons. The pivot-shift grade and 2 KiRA outputs (range of acceleration and slope of acceleration change) were compared.

Results:

The surgeon and fellow recorded the same pivot-shift grade for 45 of 50 patients (90%). Data from the 5 patients with no agreement and 1 patient with extreme outlying data were excluded from subsequent analysis. Using the KiRA range and slope data, the surgeon identified the injured knee in 74% and 76% of patients, respectively, while the fellow’s rate of injured knee identification was 74% and 80%, respectively. A correlation could be found only between pivot-shift grade and surgeon-derived range data (ρ = 0.40; P < .01) but not slope data or any fellow-derived outputs. Using the surgeon-derived range data, there was a significant difference between a grade 3 pivot (>5 m/s²) and a grade 1 or 2 pivot (<5 m/s²) (P = .01).

Conclusion:

Although a correlation between KiRA output data and pivot-shift grade was found when the device was used by an experienced surgeon, there was no correlation when used by a well-trained but less experienced orthopaedic fellow. Furthermore, the KiRA output data identified the ACL-deficient knee correctly in only 74% of patients. Although a threshold acceleration range value could be identified, above which the value was associated with a grade 3 pivot shift, this was dependent on the examiner, and distinction between other grades could not be made.

Anterior tibial loading on the calf enhances anterior tibial translation in the anterior cruciate ligament deficient knee in the anterior gravity radiographic view

BACKGROUND

Lateral radiograph in the prone position with the knee flexed at 15° (anterior gravity view (AGV)) is useful as a screening for anterior cruciate ligament (ACL) injuries, while it is sometimes difficult to find the side-to-side difference (SSD) in anterior tibial translation. Thus, we applied a weight (three kilograms) around the lower leg to increase anterior tibial translation. We aimed to determine whether weight load confers an advantage in visualizing anterior knee laxity in ACL injuries.

METHODS

Fifty-eight patients with confirmed unilateral ACL tears from February 2012 to April 2014 had consented to participate in this study. Lateral radiographs for both knees were taken in AGV and in AGV with a three-kilogram weight load applied to the proximal lower leg. Then, the SSD of tibial position related to the femur was measured in these radiographs.

RESULTS

The SSD with the weight was significantly greater than that without the weight (5.9 ± 2.1 and 3.5 ± 1.6 mm, respectively, p < 0.01). The ratio of patients with SSD of three millimeters or more in AGV with the weight was also significantly larger than that without the weight (p < 0.01).

CONCLUSIONS

The anterior laxity in AGV with the three-kilogram weight is larger than that without the weight. Thus, the AGV with the weight could be one of the helpful radiographic technique for auxiliary diagnosis of ACL injury. Level of evidence Cohort study, Level IV.

Flexion deformity and laxity as a function of knee position at the time of tensioning of rigid anatomic hamstring ACL grafts

Background

Anatomic ACL grafts routinely display the anisometric length-tension behaviour seen in the native ligament with maximum length in full knee extension. Recent improvements in hamstring graft preparation and fixation have improved graft rigidity to the point where total graft lengthening after implantation may be less than 1 mm. Despite this it remains common practice to fix these grafts in a knee flexed position.

Methods

Nineteen participants underwent all-inside ACL reconstruction with optimally preconditioned 4 strand semitendinosus grafts using bi-cortical adjustable suspensory loop fixation. Using a computer navigation system, baseline measures of anisometricity, extension range, and tibial rotation were made. The graft was tensioned and provisionally fixed with the knee flexed 5° beyond its anisometric point and extension range recorded. The graft was then definitively fixed with the knee fully extended and extension range and tibial rotation recorded again. Anterior laxity measurements were made pre-operatively and postoperatively using a manual arthrometer and compared to those from the contralateral limb.

Results

Fixing the graft with the knee flexed produced a mean FD of 10.9° (p < 0.0001) and fixing in extension restored full extension (p = 0.661). Fixing in extension restored anterior laxity at 30° (p = 0.224) and at 90° (p = 0.668). There were very strong correlations between post-operative and control extension range (r = 0.931, p < 0.0001) and anterior laxity and 30° (r = 0.830, p < 0.0001) measures. Constraint of tibial internal rotation increased by 2.9° during the pivot-shift (p < 0.001) and increased with pivot shift grade (r = 0.474, p = 0.040).

Conclusion

Fixing rigid anatomic hamstring grafts in a knee flexed position routinely produces a flexion deformity. Tensioning and fixing grafts with the knee fully extended restores full extension and anterior laxity at 30° and 90°. Rotational constraint is significantly improved and correlates with the pivot-shift grade.

Clinical relevance

Rigid anatomic grafts should be tensioned and fixed with the knee fully extended.

Lateral Extra-articular Tenodesis Reduces Anterior Cruciate Ligament Graft Force and Anterior Tibial Translation in Response to Applied Pivoting and Anterior Drawer Loads

BACKGROUND

The biomechanical effect of lateral extra-articular tenodesis (LET) performed in conjunction with anterior cruciate ligament (ACL) reconstruction (ACLR) on load sharing between the ACL graft and the LET and on knee kinematics is not clear.

PURPOSE/HYPOTHESIS

The purpose was to quantify the effect of LET on (1) forces carried by both the ACL graft and the LET and (2) tibiofemoral kinematics in response to simulated pivot shift and anterior laxity tests. We hypothesized that LET would decrease forces carried by the ACL graft and anterior tibial translation (ATT) in response to simulated pivoting maneuvers and during simulated tests of anterior laxity.

STUDY DESIGN

Controlled laboratory study.

METHODS

Seven cadaveric knees (mean age, 39 ± 12 years [range, 28-54 years]; 4 male) were mounted to a robotic manipulator. The robot simulated clinical pivoting maneuvers and tests of anterior laxity: namely, the Lachman and anterior drawer tests. Each knee was assessed in the following states: ACL intact, ACL sectioned, ACL reconstructed (using a bone-patellar tendon-bone autograft), and after performing LET (the modified Lemaire technique after sectioning of the anterolateral ligament and Kaplan fibers). Resultant forces carried by the ACL graft and LET at the peak applied loads were determined via superposition. ATT was determined in response to the applied loads.

RESULTS

With the applied pivoting loads, performing LET decreased ACL graft force up to 80% (44 ± 12 N; P < .001) and decreased ATT of the lateral compartment compared with that of the intact knee up to 7.6 ± 2.9 mm (P < .001). The LET carried up to 91% of the force generated in the ACL graft during isolated ACLR (without LET). For simulated tests of anterior laxity, performing LET decreased ACL graft force by 70% (40 ± 20 N; P = .001) for the anterior drawer test with no significant difference detected for the Lachman test. No differences in ATT were deteced between ACLR with LET and the intact knee on both the Lachman and the anterior drawer tests (P = .409). LET reduced ATT compared with isolated ACLR on the simulated anterior drawer test by 2.4 ± 1.8 mm (P = .032) but not on the simulated Lachman test.

CONCLUSION

In a cadaveric model, LET in combination with ACLR transferred loads from the ACL graft to the LET and reduced ATT with applied pivoting loads and during the simulated anterior drawer test. The effect of LET on ACL graft force and ATT was less pronounced on the simulated Lachman test.

CLINICAL RELEVANCE

LET in addition to ACLR may be a suitable option to offload the ACL graft and to reduce ATT in the lateral compartment to magnitudes less than that of the intact knee with clinical pivoting maneuvers. In contrast, LET did not offload the ACL graft or add to the anterior restraint provided by the ACL graft during the Lachman test.

Objectifying the Pivot Shift Test

The pivot shift test is utilized for assessment of rotatory instability in the anterior cruciate ligament (ACL) deficient knee. There are multiple reports of the pivot shift maneuver, and there is a lack of consensus among clinicians as to a standardized maneuver. Measurement devices are a feasible option to evaluate rotatory knee instability, objectively or quantitatively. Traditionally, measurement systems have been invasive systems. More recently, electromagnetic system, inertial sensor, or imaging analysis systems, specifically with the utilization of a tablet computer, have emerged as noninvasive, and more importantly, validated options. It is important to recognize that anatomic structures other than the ACL contribute to rotatory knee stability. Addressing the tibial slope, anterolateral structures of the knee, specifically the iliotibial band, and menisci during ACL surgery may decrease residual pivot shift in an attempt to improve clinical outcomes and prevent reinjury. This review article describes the pivot shift maneuver, objective measurement tools, and clinical applications of the pivot shift test.

Quantitative assessment of the pivot shift test with smartphone accelerometer

PURPOSE

The pivot shift (PS) test is commonly used to diagnose and evaluate the dynamic instability of the knee joint in cases of anterior cruciate ligament (ACL) tear. There is a need of a reliable and inexpensive tool which is easily available to measure PS objectively in a clinical setting. The purpose of this study was to evaluate the use of a smartphone, which is readily available, to assess the PS phenomenon.

METHODS

Seventeen patients with unilateral ACL-injured knees, undergoing ACL reconstruction, were enrolled in the study. PS was initially graded according to the International Knee Documentation Committee classification by two observers. The PS test was then performed by them in normal and injured knees under anaesthesia using a smartphone attached to Gerdy's tubercle. Acceleration changes during the PS test were recorded using the smartphone accelerometer application. Intra-observer and inter-observer reliability of the test among the two observers were evaluated. Acceleration changes were compared between the injured and normal knees, and also between the clinical grades of PS. Diagnostic utility of the smartphone accelerometer was examined by a receiver operating characteristic curve analysis.

RESULTS

Intra-observer and inter-observer reliability were high for the smartphone accelerometer. The acceleration change was higher in the ACL-injured knees than in normal knees. The mean acceleration change was 2.54 m/s² (SD = 0.97) in ACL-injured knees and 0.73 m/s² (SD = 0.19) in normal knees (p < 0.001). The mean acceleration change of Grade 1 knees was 1.89 m/s² (SD = 0.57), and that of knees of Grade 2 and above were 2.99 m/s² (SD = 0.95) (p < 0.05). Sensitivity was 94% and specificity was 100% for the acceleration change required to detect ACL injury, i.e., 1.24 m/s².

CONCLUSIONS

The results show that a smartphone can be used to evaluate the PS quantitatively and reliably, in the diagnosis of ACL injury.

LEVEL OF EVIDENCE

II.

Patient-Reported and Quantitative Outcomes of Anatomic Anterior Cruciate Ligament Reconstruction With Hamstring Tendon Autografts

Background:

The pivot-shift test has become more consistent and reliable and is a meaningful outcome measurement after anterior cruciate ligament reconstruction (ACLR).

Purpose/Hypothesis:

The purpose of this investigation was to assess patient-reported outcomes (PROs) and the quantitative pivot shift (QPS) preoperatively, at time zero immediately after anatomic ACLR, and after 24 months as well as the relationship between PROs and the QPS. It was hypothesized that anatomic ACLR would restore rotatory stability measured by the pivot-shift test and that QPS measurements would be positively correlated with PROs.

Study Design:

Cohort study; Level of evidence, 2.

Methods:

The ACL-injured and contralateral uninjured knees from 89 of 107 (83.2%) enrolled patients at 4 international centers were evaluated using a standardized pivot-shift test. Tibial acceleration was assessed with an inertial sensor, and lateral compartment translation was measured using an image analysis system preoperatively, at time zero immediately postoperatively, and at follow-up after 2 years. PROs were assessed at 12 and 24 months postoperatively with the International Knee Documentation Committee (IKDC) subjective knee form, Cincinnati Knee Rating System (CKRS), Marx activity rating scale, and activity of daily living score (ADLS).

Results:

The mean patient age at surgery was 27 years (range, 15-45 years). A positive pivot shift preoperatively (side-to-side difference in tibial acceleration, 2.6 ± 4.0 m/s²; side-to-side difference in anterior tibial translation, 2.0 ± 2.0 mm) was reduced at time zero postoperatively (side-to-side difference in tibial acceleration, –0.5 ± 1.3 m/s²; side-to-side difference in anterior tibial translation, –0.1 ± 1.0 mm). All PROs improved from preoperatively to final follow-up at 24 months: from 56.5 to 85.5 points for the IKDC (P = .0001), from 28.8 to 32.4 points for the CKRS (P = .04), from 11.2 to 7.9 points for the Marx (P < .0001), and from 75.7 to 91.6 points for the ADLS (P < .0001). Neither preoperative nor time zero postoperative rotatory laxity assessed by the pivot-shift test correlated with PROs at 24-month follow-up. A graft retear was observed in 4 patients (4.5%) within 2 years of follow-up.

Conclusion:

Anatomic ACLR resulted in significantly improved and acceptable PROs at 2-year follow-up and a low failure rate. Anatomic ACLR restored QPS measurements of anterior tibial translation and tibial acceleration to those of the contralateral knee immediately after surgery while still under anesthesia, but there was no correlation between the QPS preoperatively or at time zero after ACLR and PROs at 2-year follow-up.

Quadriceps tendon autograft for anterior cruciate ligament reconstruction is associated with high revision rates: results from the Danish Knee Ligament Registry

PURPOSE

The quadriceps tendon (QT) has recently gained interest as an anterior cruciate ligament reconstruction (ACLR) autograft. There is a paucity of data from large cohort studies on failures and revision rates after ACLR using the QT graft. The purpose of the present study is to use the Danish Knee Ligament Reconstruction Registry (DKRR) to compare revision rates, objective knee stability and subjective clinical outcomes in patients who have undergone ACLR with QT, hamstring tendon (HT), and patellar tendon (PT) as a graft for ACLR. It was hypothesized that QT autografts would result in similar objective knee stability and revision rates as HT and PT autografts.

METHODS

Data on primary ACLRs in the DKRR from 2005 through 2017 were analyzed. Knee injury and Osteoarthritis Outcome Scores (KOOS), Tegner activity scale scores, sagittal knee laxity, pivot-shift tests at 1-year follow-up and revision rates at 2-year follow-up were compared for the three autograft cohorts.

RESULTS

A total of 531 QT, 14,213 HT and 1835 PT ACLR were registered in the DKLR between 2005 and 2017. QT autograft was associated with statistically significant increased laxity (1.8 mm) compared to HT autograft (1.5 mm) (p < 0.001) and more positive pivot shift. There was a significant higher revision rate for QT (4.7%), compared to PT (1.5%) and HT (2.3%) autografts at 2-year follow-up (p < 0.002).

CONCLUSION

Quadriceps tendon autografts for ACLR was associated with higher revision rates than HT and PT grafts. QT graft was also associated with small increased objective knee laxity and more positive pivot shift than HT and PT grafts.

LEVEL OF EVIDENCE

III.

The Role of the Posterolateral Tibial Slope in the Rotational Instability of the Knee in Patients Affected by a Complete Isolated Anterior Cruciate Ligament Injury: Its Value in the Decision-Making Process during the Anterolateral Ligament Reconstruction

Purpose  The aim of this retrospective, multicenter study was to investigate the correlation between a high degree of rotatory instability, posterolateral tibial slope (PLTS), and anterolateral ligament (ALL) injury. Methods  The study population consisted of 76 adults with isolated, complete noncontact anterior cruciate ligament (ACL) tear. The sample was divided into two groups according to the preoperative degree of rotator instability (group A: pivot-shift test grades 2 and 3; group B: pivot-shift test grade 1). Preoperative magnetic resonance imaging (MRI) assessment included angle of PLTS, posterior shift of the lateral femoral condyle (16 mm) on the tibial plateau, and the presence/absence of ALL injury. The two groups were compared for differences. Results  There was a statistically significant association between pivot-shift test grades 2 and 3 (group A), PLTS slope angle > 9 degrees, and ALL injury ( p  < 0.05). Group A also demonstrated a greater posterior shift of lateral femoral condyle (>11 mm), which was, however, not statistically significant when evaluated as an isolated variable. Conclusion  Our study indicates that an increased PLTS is associated with an increased incidence of ALL injury and an increased grade of pivot shift in patients with ACL tear. Assessment of posterolateral tibial slope on MRI can therefore play a key adjunct role in the surgical planning of ALL reconstruction, especially in cases when ALL damage is radiologically difficult to detect or doubtful. Level of Evidence  This is a retrospective comparative level III study.

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.

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.

Education and repetition improve success rate and quantitative measures of the pivot shift test

PURPOSE

Clinicians have different techniques and varying levels of experience with the pivot shift test, introducing variability into its performance. The purpose of this study was to evaluate the influence of teaching and repetition on the success rate and anterior translation of the lateral knee compartment during the pivot shift test in a cadaveric ACL injury model.

METHODS

Twenty-five participants (five each of medical students, orthopaedic surgery residents, physical therapists, athletic trainers, sports medicine fellows) were recruited and a senior orthopaedic surgeon served as gold standard examiner. Each participant performed 20 pivot shift tests on lower extremity cadaveric specimens with ACL deficiency and lateral meniscectomy: 5 prior to education (baseline), 10 after watching an instructional video (passive teaching), and 5 after an interactive education session (active teaching). The anterior translation of the lateral knee compartment was recorded during each pivot shift test using electromagnetic tracking system.

RESULTS

For medical students and orthopaedic surgery residents, significant improvement in success rate was found when compared to baseline (12% and 24%, respectively) after both passive (36% and 60%, respectively) and active teaching (52% and 72%, respectively) (p < 0.5). Medical students and residents were the only participants that independently achieved significant increases in anterior translation of the lateral knee compartment, each tripling the respective baseline value (p < 0.5). In the entire study population, significant increases in anterior translation of the lateral knee compartment and success rate of the pivot shift test were seen with continuous repetition (p < 0.5). However, the standard deviation of anterior translation of the lateral knee compartment was more than twice the gold standard examiner's standard deviation, indicating a high degree of variability.

CONCLUSION

Teaching of the pivot shift test plays a major role in the development of a proper technique. However, variability persisted despite teaching and repetition. New methods may be needed to improve the teaching of the pivot shift test.

ACL reconstruction with lateral plasty reduces translational and rotatory laxity compared to anatomical single bundle and non-anatomical double bundle surgery: An in vivo kinematic evaluation with navigation system

BACKGROUND

Significantly better stability may be achieved with a Single Bundle Lateral Plasty (SBLP) reconstruction compared with the Single Bundle (SB) and Double Bundle (DB) procedures.

METHODS

The study included 42 patients who underwent ACL reconstruction. Patients were randomly selected for one of the following surgical procedure defining three study groups: Single-Bundle-Lateral-Plasty, Single-Bundle and Double-Bundle procedures. Laxity evaluation was performed with an intraoperative navigation system. Lachman test (AP30), Drawer test (AP90), Varus-Valgus stress test at 0° and 30° knee flexion (VV0, VV30), Internal-External rotation (IE30, IE90), and pivot shift (PS) test are the clinical test executed for the laxity evaluation. Laxity reduction was defined as the difference between laxity before the fixation of the graft used for the reconstruction and the laxity just after its fixation.

FINDINGS

For all the analyzed surgical techniques, the pre-reconstruction laxity values were statistically higher (P < 0.05) than the post-reconstruction values for all the analyzed tests. The analysis of the Drawer test and Internal-External rotation at 30° and 90° of knee flexion, highlighted a significant difference at time zero after surgery among the three study groups. The results showed that the SBLP technique had the highest reduction values compared to SB (P_IE90 = 0.001) and DB (P_AP90 = 0.012; P_IE30 = 0.021; P_IE90 = 0.003) techniques.

INTERPRETATION

SBLP technique showed significantly superior results in terms of antero-posterior and internal-external laxity reduction at time-zero after ACL reconstruction.

Effect of Femoral Tunnel Position on Stability and Clinical Outcomes After Single-Bundle Anterior Cruciate Ligament Reconstruction Using the Outside-In Technique

PURPOSE

To evaluate the effects of the femoral tunnel location in the femoral footprint of the anterior cruciate ligament (ACL) on postoperative knee stability and clinical outcomes after ACL reconstruction (ACLR) using the outside-in technique.

METHODS

From December 2012 to August 2014, ACLR was performed using the outside-in technique in 137 patients. Among these patients, those who had a follow-up period of over 2 years were retrospectively reviewed. A total of 102 patients met the inclusion criteria. The relative location of the femoral tunnel in the lateral condyle was evaluated as a percentage using the standardized grid system on a 3-dimensional computed tomography image. Each patient was then classified into the anterior group, center group (anteroposterior plane, 29.3% ± 3.5%), or posterior group depending on the location of the femoral tunnel. Knee laxity was evaluated using a GNRB knee arthrometer, stress radiography, and the pivot-shift test. From a clinical perspective, patient-reported outcomes (International Knee Documentation Committee subjective form and Lysholm knee score) were then evaluated.

RESULTS

Of 102 patients, 31 (30.4%) were assigned to the anterior group, 46 (45.1%) were assigned to the center group, and 25 (24.5%) were assigned to the posterior group. Postoperative side-to-side differences, which were measured using stress radiographs and the GNRB arthrometer, were significantly smaller in the posterior group (1.7 ± 0.6 mm and 1.5 ± 0.5 mm, respectively) than in the center group (2.3 ± 0.9 mm and 2.2 ± 2.8 mm, respectively) and anterior group (2.4 ± 0.7 mm and 2.4 ± 1.3 mm, respectively) (P = .002 for stress radiography and P = .002 for GNRB arthrometer). No significant between-group differences were observed in the pivot-shift test results and patient-reported outcomes among the 3 groups.

CONCLUSIONS

The location of the femoral tunnel in the anatomic ACL footprint did not affect postoperative stability and clinical outcomes in the case of ACLR using the outside-in technique.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Distal femur morphology affects rotatory knee instability in patients with anterior cruciate ligament ruptures

PURPOSE

Distal femur morphology has been shown to influence knee joint kinematics and may affect rotatory knee laxity. The purpose of this study was to determine the relationship between rotatory knee laxity and distal femoral morphology in patients with complete anterior cruciate ligament (ACL) rupture. It was hypothesized that increased posterior femoral condylar depth on standard lateral radiographs, quantified as the "lateral femoral condyle ratio" would correlate with increased rotatory knee laxity, measured by a quantitative pivot shift test.

METHODS

Consecutive patients who underwent ACL reconstruction from 2014 to 2016 were retrospectively reviewed. A standardized pivot shift test was performed preoperatively on both knees and quantified using tablet technology. Using standard lateral radiographs of the knee, the ratio of posterior condylar distance over total condylar distance was defined as the lateral femoral condyle ratio.

RESULTS

Data sets were obtained for 57 patients. The mean anterior translation of the lateral knee compartment during a quantitative pivot shift test was found to be 4.0 ± 2.4 mm and 1.3 ± 0.9 mm for the injured and uninjured knees, respectively. The mean lateral femoral condyle ratio on X-ray was 63.2 ± 4.5%. There were significant correlations between the lateral femoral condyle ratio and the absolute quantitative (ρ = 0.370, p < 0.05) and side-to-side differences in anterior translation of the lateral knee compartment (ρ = 0.419, p < 0.05).

CONCLUSION

The most important finding from this study is that increased posterior femoral condylar depth, quantified as a lateral femoral condyle ratio, is associated with increased rotatory knee laxity in ACL-deficient patients. This suggests that distal femur morphology may influence rotatory knee laxity. This study may assist clinicians in evaluating ACL injuries and identifying patients at greater risk for persistent increased rotatory knee laxity after ACL reconstruction.

LEVEL OF EVIDENCE

III.

Preoperative laxity in ACL-deficient knees increases with posterior tibial slope and medial meniscal tears

PURPOSE

The aim of this study was to determine patient and anatomic factors that influence anteroposterior and rotational laxity in knees with ACL tears. Based on the findings of biomechanical studies, we hypothesized that static and dynamic anterior tibial translation (ATT) as well as positive pivot shift would increase with female gender, tibial slope, and meniscal tears.

METHODS

The authors prospectively collected preoperative data and intraoperative findings of 417 patients that underwent ACL reconstruction. The exclusion criteria were: revision ACL procedures (n = 53), other surgical antecedents (n = 27), prior osteotomies (n = 7) or concomitant ligament tears on the ipsilateral knee (n = 34), and history of ACL tears in the contralateral knee (n = 45), leaving a study cohort of 251 patients. Their preoperative anteroposterior knee laxity was assessed objectively using 'static' monopodal weight-bearing radiographs and 'dynamic' instrumented differential measurements of ATT. Rotational laxity was assessed subjectively using the pivot shift test.

RESULTS

Multivariable regression showed that static ATT increases only with tibial slope (β = 0.30; p < 0.001), but dynamic ATT increases with tibial slope (β = 0.19; p = 0.041), medial meniscal tears (β = 1.27; p = 0.007), complete ACL tears (β = 2.06; p < 0.001), and to decrease with age (β = - 0.09; p < 0.001). Multivariable regression also indicated that high-grade pivot shift decreases with age (OR 0.94; p < 0.001) and for women (OR 0.25; p < 0.001), and to be higher for knees with complete ACL tears (OR 3.04; p = 0.002) or medial meniscal tears (OR 2.28; p = 0.010).

CONCLUSION

Contrary to expectations based on biomechanical studies, static ATT was only affected by high posterior tibial slope, while dynamic ATT was affected by both high posterior tibial slopes and medial meniscal tears, but not by gender or lateral meniscal tears. Likewise, pivot shift was affected by gender and medial meniscal tears, but not lateral meniscal tears or posterior tibial slope. These findings are relevant to guide surgeons in optimizing their surgical procedures, such as conserving the menisci when possible, and rehabilitation protocols, by delaying full weight-bearing and return to sports in patients with anatomic and lesional risk factors.

LEVEL OF EVIDENCE

Cohort study, Level IV.

Anatomic Anterior Cruciate Ligament Reconstruction Using Hamstring Tendons Restores Quantitative Pivot Shift

Background:

It is still uncertain how surgical reconstruction of the anterior cruciate ligament (ACL) is able to restore rotatory laxity of the involved joint. The desired amount of restraint applied by the ACL graft, as compared with the healthy knee, has not been fully clarified.

Purpose:

To quantify the ability of single-bundle anatomic ACL reconstruction using hamstring tendons in reducing the pivot-shift phenomenon immediately after surgery under anesthesia.

Study Design:

Case series; Level of evidence, 4.

Methods:

An inertial sensor and image analysis were used at 4 international centers to measure tibial acceleration and lateral compartment translation of the knee, respectively. The standardized pivot-shift test was quantified in terms of the side-to-side difference in laxity both preoperatively and postoperatively with the patient under anesthesia. The reduction in both tibial acceleration and lateral compartment translation after surgery and the side-to-side difference were evaluated using the Wilcoxon signed-rank test. Alpha was set at P < .05.

Results:

A total of 107 patients were recruited for the study, and data were available for 89 patients. There was a statistically significant reduction in quantitative rotatory knee laxity between preoperatively (inertial sensor, 2.55 ± 4.00 m/s²; image analysis, 2.04 ± 2.02 mm) and postoperatively (inertial sensor, –0.54 ± 1.25 m/s²; image analysis, –0.10 ± 1.04 mm) between the involved and healthy joints, as measured by the 2 devices (P < .001 for both). Postoperatively, both devices detected a lower rotatory laxity value in the involved joint compared with the healthy joint (inertial sensor, 2.45 ± 0.89 vs 2.99 ± 1.10 m/s², respectively [P < .001]; image analysis, 0.99 ± 0.83 vs 1.09 ± 0.92 mm, respectively [P = .38]).

Conclusion:

The data from this study indicated a significant reduction in the pivot shift when compared side to side. Both the inertial sensor and image analysis used for the quantitative assessment of the pivot-shift test could successfully detect restoration of the pivot shift after anatomic single-bundle ACL reconstruction. Future research will examine how pivot-shift control is maintained over time and correlation of the pivot shift with return to full activity in patients with an ACL injury.

Combined reconstruction of the anterolateral ligament in chronic ACL injuries leads to better clinical outcomes than isolated ACL reconstruction

PURPOSE

To evaluate the results of combined anterior cruciate ligament (ACL) and anterolateral ligament (ALL) reconstruction in patients with chronic ACL injury. It was hypothesized that patients who underwent combined ACL and ALL reconstruction would exhibit less residual laxity and better clinical outcomes.

METHODS

Two groups of patients were evaluated and compared retrospectively. Both groups consisted only of patients with chronic (more than 12 months) ACL injuries. Patients in group 1 underwent anatomical intra-articular reconstruction of the ACL and patients in group 2 underwent anatomic intra-articular ACL reconstruction combined with ALL reconstruction. The presence of associated meniscal injury, the subjective International Knee Documentation Committee (IKDC) and Lysholm functional outcome scores in the postoperative period, KT-1000 evaluation, the presence of residual pivot shift and graft rupture rate were evaluated.

RESULTS

One hundred and one patients who underwent reconstruction of chronic ACL injuries were evaluated. The median follow-up was 26 (24-29) months for group 1 and 25 (24-28) months for group 2. There were no significant differences between groups regarding gender, age, duration of injury until reconstruction, follow-up time or presence of associated meniscal injuries in the preoperative period. Regarding functional outcome scores, patients in group 2 presented better results on both the IKDC (p = 0.0013) and the Lysholm (p < 0.0001) evaluations. In addition, patients in group 2 had better KT-1000 evaluation (p = 0.048) and a lower pivot shift rate at physical examination, presenting only 9.1% positivity versus 35.3% in the isolated ACL reconstruction (p = 0.011). Regarding re-ruptures, group 1 presented 5 (7.3%) cases, and group 2 presented no cases.

CONCLUSION

The combined ACL and ALL reconstruction in patients with chronic ACL injury is an effective and safety solution and leads to good functional outcomes with no increase in complication rate. The clinical relevance of this finding is the possibility to indicate this type of procedure when patients present with more than 12 months after injury for surgery.

LEVEL OF EVIDENCE

Level III.

Anatomical features of tibia and femur: Influence on laxity in the anterior cruciate ligament deficient knee

BACKGROUND

Until now, there has been a lack of in vivo analysis of the correlation between bony morphological features and laxity values after an anterior cruciate ligament (ACL) injury.

METHODS

Forty-two patients who underwent ACL-reconstruction were enrolled. Static laxity was evaluated as: antero-posterior displacement and internal-external rotation at 30° and 90° of flexion (AP30, AP90, IE30, IE90) and varus-valgus rotation at 0° and 30° of flexion (VV0, VV30). The pivot-shift (PS) test defined the dynamic laxity. Using magnetic resonance imaging, we evaluated the transepicondylar distance (TE), the width of the lateral and medial femoral condyles (LFCw and MFCw) and tibial plateau (LTPw and MTPw), the notch width index (NWI) and the ratio of width and height of the femoral notch (N-ratio), the ratio between the height and depth of the lateral and medial femoral condyle (LFC-ratio and MFC-ratio), the lateral and medial posterior tibial slopes (LTPs and MTPs) and the anterior subluxation of the lateral and medial tibial plateau with respect to the femoral condyle (LTPsublx and MTPsublx).

RESULTS

Concerning the AP30, LTPs (P=0.047) and MTPsublx (P=0.039) were shown to be independent predictors while for the AP90 only LTPs (P=0.049) was an independent predictor. The LTPs (P=0.039) was shown to be an independent predictor for IE90 laxity, while for the VV0 test it was identified as the LFCw (P=0.007).

CONCLUSIONS

A higher antero-posterior laxity at 30° and 90° of flexion was found in those with a lateral tibial slope <5.5°.

The Augmentation of Revision Anterior Cruciate Ligament Reconstruction With Modified Iliotibial Band Tenodesis to Correct the Pivot Shift: A Computer Navigation Study

BACKGROUND

Iliotibial band (ITB) tenodesis improves stability and functional outcomes when added to anterior cruciate ligament (ACL) reconstruction. Its precise indications are unknown. Persistence of the pivot shift after revision ACL reconstruction may be one indication.

HYPOTHESIS

The addition of ITB tenodesis for a persistent pivot shift after revision ACL reconstruction will improve stability and activity levels.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Adults with recurrent ACL ruptures underwent revision ACL reconstruction, followed by a pivot-shift test before the surgery ended. If the pivot shift was grade 0 or 1, no further surgery was performed (group 1). If it was grade 2 or 3, ITB tenodesis was performed (group 2). The pivot-shift test was performed, graded, and measured using computer navigation before revision ACL reconstruction and after revision ACL reconstruction with and without ITB tenodesis. Tegner activity scores were obtained 2 years after surgery. Groups were compared with regard to anterior translation and internal rotation during the pivot shift as well as Tegner activity scores ( P < .05).

RESULTS

There were 20 patients in group 1 and 18 in group 2. The mean anterior translation improved in group 1, from 17.7 ± 3.5 mm to 6.6 ± 1.9 mm, and group 2, from 18.5 ± 3.3 mm to 6.1 ± 1.2 mm, after revision ACL reconstruction ( P < .001), with no difference between the groups ( P = .15). After ITB tenodesis, the reduction in anterior translation in group 2 (5.3 ± 1.5 mm) became greater than that in group 1 (6.6 ± 1.9 mm) ( P = .03). In both groups after revision ACL reconstruction, there was a reduction in internal rotation (group 1: 24.2° ± 4.0° to 10.3° ± 1.1°; group 2: 25.4° ± 3.7° to 14.6° ± 2.8°; P < .001), but this change was less in group 2 ( P = .02). After ITB tenodesis, internal rotation in group 2 (8.3° ± 2.6°) became less than that in group 1 (10.3° ± 1.1°) ( P = .02). The mean Tegner activity scores in group 1 were 8.1 ± 1.1 before surgery and 7.4 ± 0.9 after surgery, while in group 2 they were 7.0 ± 1.3 and 7.2 ± 0.4, respectively, and not significantly different ( P = .29).

CONCLUSION

ITB tenodesis improved laxity, although it did not affect activity levels, when there was a persistent pivot shift after revision ACL reconstruction.

CLINICAL RELEVANCE

An indication to perform ITB tenodesis is the persistence of a grade ≥2 pivot shift after revision ACL reconstruction.

Prediction of progression of damage to articular cartilage 2 years after anterior cruciate ligament reconstruction: use of aggrecan and type II collagen biomarkers in a retrospective observational study

BACKGROUND

We aimed to determine whether synovial fluid (SF) biomarkers can predict the progression of articular cartilage damage as determined by arthroscopic evaluation during and after anterior cruciate ligament (ACL) reconstruction.

METHODS

Arthroscopic assessment of articular cartilage damage was performed twice in 62 patients, first during ACL reconstruction and then approximately 2 years later during implant removal for ligament fixation. SF levels of the collagenase-generated cleavage neoepitope of type II collagen (C2C) and proteoglycan glycosaminoglycans keratan sulfate (KS), chondroitin-4-sulfate (Δdi-C4S), and chondroitin-6-sulfate (Δdi-C6S) were measured at ACL reconstruction. Associations between baseline biomarker levels and subsequent progression of cartilage damage were determined using receiver operating characteristic analysis and multivariable logistic regression analysis.

RESULTS

No radiographic changes were observed in any of the patients. Progression of high-grade cartilage damage, observed arthroscopically, was negatively correlated with levels of Δdi-C6S and KS, as well as the ratio of Δdi-C6S to Δdi-C4S (C6S/C4S). Logistic regression analysis revealed significant associations of Δdi-C6S (cut-off: 55.7 nmol/ml, odds ratio (OR) 0.231, 95% confidence interval (CI) 0.061-0.879), KS (cut-off: 10.6 μg/ml, OR 0.114, 95% CI 0.024-0.529), and C6S/C4S ratio (cut-off: 4.6, OR 0.060, 95% CI 0.005-0.737) with the progression of high-grade cartilage damage after adjusting for age, the duration from injury to first surgery, sex, and the number of high-grade lesions (grades III and IV) at baseline.

CONCLUSIONS

The progression of high-grade cartilage damage was significantly associated with baseline levels of proteoglycan glycosaminoglycan biomarkers; namely, Δdi-C6S, KS, and C6S/C4S ratio.

Analysis of the influence of anaesthesia on the clinical and quantitative assessment of the pivot shift: a multicenter international study

PURPOSE

The main goal of this work was to evaluate the pivot shift test in awake and anesthetized patients by using two different quantitative methodologies and comparing the results with the standard clinical grading, taking advantage of a multicenter international study.

METHODS

Patients between 16 and 50 years of age undergoing primary unilateral single-bundle anterior cruciate ligament (ACL) reconstruction were considered eligible. The pivot shift test was performed pre-operatively, with the patient awake and again with the patient under general anaesthesia. The pivot shift test was clinically graded as defined by the International Knee Documentation Committee. The instrumented assessment was performed by using two non-invasive acquisition systems; specifically, a system exploiting an inertial sensor and a video-based application developed on a commercial tablet using skin markers. Lateral compartment translation and the tibial acceleration reached during joint reduction were used as quantitative parameters.

RESULTS

A total of 103 patients were enrolled in the study. Statistically significant difference was found between the distributions of clinical grade evaluated in awake patients and those under general anaesthesia (P < 0.01). Comparing awake patients to those under general anaesthesia, lower values were found both for tibial acceleration (3.7 ± 1.5 vs 6.0 ± 4.6 m/s², P < 0.01) and lateral compartment translation of the involved limb (2.2 ± 1.7 vs 3.0 ± 2.2 mm, P < 0.01).

CONCLUSIONS

This study indicated that significant differences in the grading of the pivot shift test exist between awake and anesthetized patients, regardless of the use of quantitative instruments during the evaluation. Actual clinical assessment reported indeed its weakness, presenting subjective variability and dependence on tester's experience. However, several factors might influence the validity of awake examination such as experience level of examiner and cultural factors, as seen in this international multicenter study.

LEVEL OF EVIDENCE

Prospective comparative study, Level II.

Evaluation of pivot shift phenomenon while awake and under anaesthesia by different manoeuvres using triaxial accelerometer

PURPOSE

Evaluating pivot shift phenomenon is difficult due to its subjectivity, wide variation of testing manoeuvres, and difficulty in evaluating patients while awake. The purpose of this study was to evaluate the pivot shift phenomenon using a triaxial accelerometer by two different manoeuvres, the pivot shift test as representative of flexion manoeuvre and N test as a representative of extension manoeuvre, and in two different conditions, awake and under anaesthesia.

METHODS

Twenty-nine patients with unilateral anterior cruciate ligament (ACL)-injured knee were included. Pivot shift test and N test were performed for both injured and uninjured legs while awake and under anaesthesia, with the acceleration measurements using a triaxial accelerometer (KiRA). The tests were also subjectively graded on a scale of 0-6 based on the modification of IKDC criteria.

RESULTS

Under anaesthesia, acceleration of ACL-injured knees was greater than that of uninjured knees in both pivot shift test (P < 0.001) and N test (P < 0.001) , whereas the acceleration value was greater in the N test. Furthermore, there were significant positive correlations between the acceleration and subjective grading in both tests, whereas the N test was more significant than the pivot shift test. On the other hand, there was no statistical significance in acceleration between ACL-injured and uninjured knees in either test while the patient was awake.

CONCLUSION

The triaxial accelerometer was useful to objectively detect and quantitatively evaluate the pivot shift phenomenon by both the pivot shift test and N test under anaesthesia. The acceleration of ACL-injured knees was greater than that of uninjured knees, and the acceleration was correlated with the subjective manual grading, especially in the N test. On the other hand, its use while the patient was awake was likely limited.

LEVELS OF EVIDENCE

Diagnostic study of non-consecutive patients without a universally applied gold standard, Level III.

Does additional reconstruction of the anterolateral ligament during a primary anterior cruciate ligament reconstruction affect tibial rotational laxity - A case series

Background

The current evidence suggests that rotational stability in not restored in patients with anterior cruciate ligament (ACL) ruptures, despite reconstructive surgery. The graded pivot-shift is a useful clinical test to delineate extent of ligamentous laxity within the knee. Given its lateralised position, we hypothesized that reconstruction of the anterolateral ligament (ALL) would provide restraint to excessive internal rotation, restoring rotational stability.

Methods

10 patients with MRI confirmed diagnosis of an isolated ACL rupture were included. Patients assigned a grade-3 pivot-shift underwent dual-ligament reconstruction for the ACL and ALL (Group 2), whilst patients with an absent pivot-shift, grade-1 or grade-2 underwent single ligament reconstruction for just the ACL (Group 1). Total range of rotation (TRR) was measured using a 3D-kinematic system at 30°,60°and 90° of knee flexion. Data was collected on the pathology-free contralateral normal knee (CNK), ACL-deficient knee (ADK) and the ACL-reconstructed knee (ARK).

Results

A statistically significant pre-operative difference in TRR between the CNK and ADK was noted between Group 1 and 2 (4.04° vs. 1.53°; p < 0.05). Postoperatively, both groups achieved a TRR that was either equivalent, or surpassed values that were observed on the CNKs. The absolute and percentage reduction in TRR at 30° of knee flexion was significantly higher in Group-2 compared to Group-1 (−8.15° vs. −2.96°; p < 0.001) and (28.04% vs. 13.31%; p < 0.001) respectively.

Conclusion

Our findings are based primarily in anaesthetized patients, with kinematic values at time-zero postoperatively. Patients presenting with significant rotational instability following a primary ACL injury and assessed to have a grade-3 pivot-shift may benefit from dual-ligament reconstruction. Further research is required to assess long-term patient-centered clinical outcomes.

•

To prevent excessive rotation in the knee, a structure needs to be present away from the centre axis; at the edge of a plane, resisting rotational motion.

•

The graded pivot-shift is a useful clinical test to help delineate extent of ligamentous laxity within the knee.

•

The higher the grade of the pivot-shift in the ACL deficient knee, the greater the TRR present.

•

The ALL plays a significant role in ACL deficient knees with a grade-3 pivot shift, restoring TRR at time-zero.

•

Further research is required assessing long-term patient-centered clinical outcomes.

Kinematics of ACL and anterolateral ligament. Part I: Combined lesion

PURPOSE

To quantify the influence of ALL lesions on static and dynamic laxity in ACL-deficient knee.

METHODS

The study was performed in 10 fresh-frozen knees. The joints were analysed in the following conditions: intact, ACL resection and ACL + ALL resection. Testing parameters were defined as: anterior displacement at 30° and 90° of flexion (AP30, AP90) applying a manual-maximum load; internal rotation at 30° and 90° of flexion (INT30, INT90) applying a 5 N m torque and internal rotation and acceleration during manual pivot-shift (PS) test. Kinematics was acquired by a navigation system; a testing rig and a torquemeter were used to control the limb position and the applied torque. Paired Student's t test was conducted to assess statistical difference, and significance was set at P < 0.05.

RESULTS

The ALL resection determined a significant increase in terms of internal rotation (INT30 P = 0.02, INT90 P = 0.03), while AP30 (P n.s) and AP90 (P n.s) were not affected. ALL resection produced a significant increase in terms of acceleration during PS test (P < 0.01), but no significant change in PS internal rotation was observed.

CONCLUSION

The ALL plays a significant role in controlling static internal rotation and acceleration during PS test. On the other hand, ALL resection did not produce any significant change in terms of anterior displacement. A trend was seen for the internal rotation during the pivot-shift test to increase after ALL resection was higher when compared to the intact and isolated ACL lesion states; however, the differences were not significant. The results highlight the clinical relevance of this structure that should be assessed before an ACL reconstruction in order to avoid residual laxity.

The combination of tibial anterior translation and axial rotation into a single biomechanical factor improves the prediction of patient satisfaction over each factor alone in patients with ACL reconstructed knees

PURPOSE

The purpose of this study was to identify biomechanical factors, in both reconstructed and healthy knees, that correlate with patient satisfaction after ACL reconstruction.

METHODS

Seventeen patients who had undergone unilateral ACL reconstruction were reviewed 9 years post-op. Patients completed subjective questionnaires and underwent manual knee laxity testing (Lachman-Trillat, KT-1000, and pivot shift) and automated laxity testing. During automated testing, both legs were rotated into external rotation and then internal rotation until peak rotational torque reached 5.65 Nm. Load-deformation curves were generated from torque and rotation data. Features of the curves were extracted for analysis. Total leg rotation and anterior laxity during KT-1000 testing were combined into a single factor (Joint Play Envelope or JPE). Patients were divided into groups based on patient satisfaction scores (Group 1: Higher Satisfaction, Group 2: Lower Satisfaction, Group 3: Unsatisfied). Load-deformation curve features and manual laxity testing results were compared between groups 1 and 2 to determine which biomechanical factors could distinguish between the groups. Diagnostic screening values were calculated for KT-1000 testing, the pivot shift test, total leg rotation and JPE.

RESULTS

During manual testing, no significant differences in biomechanical factors were found when comparing reconstructed knees in group 1 and group 2. When comparing the reconstructed and healthy knees within group 2, the reconstructed knees had a significantly higher displacement during the KT-1000 manual maximum test (p < 0.002). When considering the reconstructed knees alone, neither the result of the pivot shift test nor KT-1000 testing could distinguish between group 1 and group 2. During automated testing, there were no significant differences between the groups when comparing the reconstructed lower limbs. The healthy lower limbs in group 2 had more maximum external rotation (p < 0.02) and decreased stiffness at maximum external rotation (p < 0.02) when compared to the healthy lower limbs in group 1. Total leg rotation was unable to distinguish between group 1 and group 2. JPE could distinguish between group 1 and group 2 when considering the reconstructed limb alone (p < 0.02). All four diagnostic screening values for JPE were equal or higher than in the other criteria. JPE also showed the most significant correlation with patient satisfaction.

CONCLUSIONS

Joint Play Envelope is an objective measure that demonstrated improved predictive value as compared to other tests when used as a measure of satisfaction in patients with ACL reconstructed knees.

The influence of applied internal and external rotation on the pivot shift phenomenon

PURPOSE

The pivot shift test is performed in different techniques and the rotation of the tibia seems to have a significant impact on the amount of the pivot shift phenomenon. It has been hypothesised that external rotation will increase the phenomenon due to less tension at the iliotibial band in knee extension.

METHODS

Twenty-four patients with unilateral anterior cruciate ligament insufficiency were included prospectively. The pivot shift test was performed bilaterally in internal and external tibial rotation under general anaesthesia. Knee motion was captured using a femoral and a tibial inertial sensor. The difference between positive and negative peak values in Euclidean norm of acceleration was calculated to evaluate the amount of the pivot shift phenomenon.

RESULTS

The pivot shift phenomenon was significantly increased in patients with ACL insufficiency when the test was performed in external [mean 5.2 ms^- 2 (95% CI 4.3-6.0)] compared to internal tibial rotation [mean 4.4 ms^- 2 (95% CI 3.5-5.4)] (p = 0.002). In healthy, contralateral knees did not show any difference between external [mean 4.0 ms^- 2 (95% CI 3.3-4.7)] and internal tibial rotation [mean 4.0 ms^- 2 (95% CI 3.4-4.6)] (ns).

CONCLUSIONS

The pivot shift phenomenon was increased with external rotation in ACL-insufficient knees, and therefore, one should perform the pivot shift test, rather, in external rotation to easily evoke the, sometimes difficult to detect, pivot shift phenomenon.

LEVEL OF EVIDENCE

I (diagnostic study).

Does meniscus removal affect ACL-deficient knee laxity? An in vivo study

PURPOSE

The purpose of the present study was to determine, in vivo, the effect of different types of meniscectomy on an ACL-deficient knee.

METHODS

Using a computer-assisted navigation system, 56 consecutive patients (45 men and 11 women) were subjected to a biomechanical testing with Lachman test (AP30), drawer test (AP90), internal/external rotation test, varus/valgus rotation test and pivot-shift test. The patients were divided into three groups according to the status of the medial meniscus. Group BH, 8 patients with bucket-handle tear of medial meniscus underwent a subtotal meniscectomy; Group PHB, 19 patients with posterior horn body of medial meniscus tear underwent a partial meniscectomy; and Group CG with isolated ACL rupture, as a control group, with 29 patients.

RESULTS

A significant difference in anterior tibial translation was seen at 30 grades and in 90 grades between BH and PHB groups compared to the CG. In response to pivot-shift test, no significant differences in terms of AREA and POSTERIOR ACC were found among the three groups (n.s). Concerning the anterior displacement of the pivot shift a statistically significant differences among the three tested groups was found.

CONCLUSION

The present study shows that meniscal defects significantly affect the kinematics of an ACL-deficient knee in terms of anterior tibial translation under static and dynamic testing.

Revision Anterior Cruciate Ligament Reconstruction: Results of a Single-stage Approach Using Allograft Dowel Bone Grafting for Femoral Defects

INTRODUCTION

The purpose of this study was to present results of single-stage revision anterior cruciate ligament (ACL) reconstruction using an allograft bone dowel for isolated femoral bony deficiency.

METHODS

Sixteen patients underwent single-stage revision ACL reconstruction using an allograft bone dowel for isolated femoral bony deficiency between 2007 and 2012. Twelve patients (75%) completed study visits, which included CT scans as well as completion of validated outcomes measures.

RESULTS

The average KT-1000 side-to-side difference was 1.0 mm ± 2.9 mm. The average International Knee Documentation Committee score was 70.2 ± 17.8, the Tegner score was 4.8 ± 2.8, and the visual analog scale pain score was 2.8 ± 2.4. An analysis of CT scans showed that all 12 dowels had excellent (>75%) incorporation.

CONCLUSIONS

A single-stage approach for revision ACL reconstruction using allograft dowels for isolated femoral bony deficiency yields objective and subjective outcomes comparable to those reported in the literature for two-stage and other single-stage techniques, with good incorporation of the dowels.

LEVEL OF EVIDENCE

Retrospective case series, level IV.