The PCL index is correlated with the control of rotational kinematics that is achieved after anatomic anterior cruciate ligament reconstruction

Examining Postoperative Posterior Cruciate Ligament Index: A Structural Paradigm in Anterior Cruciate Ligament (ACL) Reconstructions With Hamstring Tendon Autograft

BACKGROUND

The current study aimed to compare the posterior cruciate ligament (PCL) index values of patients who underwent hamstring tendon (HT) autograft reconstruction due to an anterior cruciate ligament (ACL) tear. The comparison involved assessing these values in a similar cohort and evaluating the association between the alteration in the PCL index and functional results.

METHODS

Patients who were clinically diagnosed with a complete, unilateral ACL tear and underwent ACL reconstruction (ACLR) using HT autograft between January 2018 and January 2021 constituted the operated group (Group 1) of the study. The control group (Group 2) consisted of patients selected from a convenience sample without ACL rupture, meniscal lesion, or cartilage damage who underwent an MRI during an outpatient orthopaedic consultation for knee pain. The operated group was submitted for an MRI of the knee one year after the operation for any reason such as pain, graft healing, the presence of tunnel widening, or suspicion of re-rupture. The International Knee Documentation Committee (IKDC) Subjective Knee Evaluation Form and the Lysholm Scoring System were applied to the patients in the operated group in the preoperative and postoperative periods to evaluate their complaints, function, and participation in sports and to assess functional ability and functional capacity. A radiologist with five years of experience measured the PCL index in the sagittal section of an MRI. In the operated group, changes in PCL index, IKDC, and Lysholm values during the postoperative period were assessed, along with their correlation. Additionally, a comparison was made between the values of the operated group and the non-operated group.

RESULTS

No statistically significant correlation was found between the PCL index alteration and the functional score alteration (IKDC and Lysholm) in the operated group (p>0.05). In comparison to the non-operated group, the preoperative PCL index measures of the operated group were significantly lower (p: 0.000; p<0.05). The increase in the postoperative PCL index measurements of the operated group was similarly statistically significant (p: 0.000; p<0.05).

CONCLUSION

Although the PCL index appears to be a strong anatomical structural parameter in ACLR patients performing HT autograft in the postoperative period, its correlation with functional results is weak.

High anteromedial insertion reduced anteroposterior and rotational knee laxity on mid-term follow-up after anatomic anterior cruciate ligament reconstruction

Background

The position of the femoral insertion has a great influence on the laxity of the knee joint after ACLR, especially for rotational laxity.

Purpose

To compare the effects of different femoral tunnel positions on knee stability after arthroscopic anterior cruciate ligament reconstruction (ACLR).

Methods

The clinical outcomes of 165 patients after autograft ACLR were analyzed retrospectively. The patients were separated into three groups according to the position of the femoral tunnel, as follows: low center (LC) group, 53 patients; high center (HC) group, 45 patients; and high anteromedial (HAM) group, 67 patients. The side-to-side differences (SSDs) in anteroposterior knee laxity measured using a KT-2000 arthrometer and the pivot shift test (PST) pre- and postoperatively were compared among the three groups and analyzed.

Results

After 5 years postoperatively, the SSD in the anteroposterior knee laxity in the three groups was significantly decreased postoperatively compared with preoperatively in knees; meanwhile, the negative PST rate was significantly increased in the three groups. The postoperative SSD in anteroposterior knee laxity was significantly increased in the HC group compared with the LC and HAM groups (1.5 ± 1.3 VS 1.0 ± 1.1 VS 1.0 ± 1.0, P<0.05). The negative postoperative PST rate was higher in both the LC and HAM groups than in the HC group (84.9% VS 91.0% VS 71.1%, P<0.05), and there was no significant difference in the negative PST rate between the LC and HAM groups (84.9% VS 91.0%, P>0.05). The negative postoperative PST rate was significantly higher in the HAM group than in the LC and HC groups for patients with a high degree of laxity preoperatively (31.3% VS 3.3% VS 14.4%, P>0.05).

Conclusion

Patients in HAM group showed better control over anteroposterior laxity, rotational laxity, and subjective knee function compared to other groups post operation. Therefore, the HAM point is the closest to the I.D.E.A.L point concept, and is recommended as the preferred location for the femoral tunnel in ACLR.

Outpatient-based diagnostic criteria for partial ACL injury: clinical outcomes of non-operative treatment and radiographic predictor

INTRODUCTION

This study aimed to (1) evaluate the short-term clinical outcomes of patients who underwent non-operative treatment for partial anterior cruciate ligament (ACL) tears diagnosed using the outpatient-based diagnostic criteria and (2) investigate the radiographic predictors distinguishing patients at risk of non-operative treatment failure.

METHODS

From 2010 to 2019, patients diagnosed with partial ACL tears and treated with non-operative treatment were reviewed retrospectively. Patients were then classified into two groups: those who successfully responded to non-operative treatment (group S) and those who failed to respond to non-operative treatment and required surgical reconstruction within 6 months after injury (group F). ACL laxity, patient-reported outcomes (PROs), and several radiographic parameters were analyzed. To identify radiographic predictors related to clinical outcomes, radiographic parameters were compared between the groups, which were statistically matched for potential confounders (age and activity level) using inverse probability of treatment weighting.

RESULTS

A total of 44 patients were analyzed (mean age, 28.7 ± 8.7 years; 31 men), and classified into two groups (group S, 23 patients; group F, 21 patients). There were no significant differences in ACL laxity and PROs between the groups at 1 year after either non-operative treatment or surgical reconstruction. A comparison of radiographic parameters between the groups revealed significant differences in several parameters related to secondary signs of ACL injury. Subsequent regression analyses revealed that anterior tibial translation and extent of bone bruises were radiographic predictors related to clinical outcomes.

CONCLUSION

Non-operative treatment for partial ACL tears diagnosed using the outpatient-based diagnostic criteria can provide successful short-term clinical outcomes in selective patients. Secondary signs of ACL injuries, particularly the amount of anterior tibial translation and the extent of bone bruises, are radiographic predictors that could differentiate patients at risk of non-operative treatment failure.

LEVEL OF EVIDENCE

Retrospective cohort study, III.

The posterior cruciate ligament index as a reliable indirect sign of anterior cruciate ligament rupture is associated with the course of knee joint injury

PURPOSE

The objective of this study was to clarify the clinical value of the posterior cruciate ligament index (PCLI) in anterior cruciate ligament (ACL) rupture, to explore the relationship between the PCLI and course of disease, and to identify the influencing factors of the PCLI.

METHODS

The PCLI was defined a quotient of the X (the tibial and femoral PCL attachments) and the Y (the maximum perpendicular distance from X to the PCL). A total of 858 patients were enrolled in this case-control study, including 433 patients with ACL ruptures who were assigned to the experimental group and 425 patients with meniscal tears (MTs) who were allocated to the control group. Some patients in the experimental group have collateral ligament rupture (CLR). Information, such as the patient's age, sex, and course of disease, was recorded. All patients underwent magnetic resonance imaging (MRI) preoperatively, and the diagnosis was confirmed with the aid of arthroscopy. The PCLI and the depth of the lateral femoral notch sign (LFNS) were calculated based on the MRI findings, and the characteristics of the PCLI were explored.

RESULTS

The PCLI in the experimental group (5.1 ± 1.6) was significantly smaller than that in the control group (5.8 ± 1.6) (P < 0.05). The PCLI gradually decreased with time and was only 4.8 ± 1.4 in patients in the chronic phase (P < 0.05). This change was not due to the decrease in X but rather the increase in Y. The results also showed that the PCLI was not related to the depth of the LFNS or injuries of other structures in the knee joint. Furthermore, when the optimal cut-off point of the PCLI was 5.2 (area under the curve = 71%), the specificity and the sensitivity were 84% and 67%, respectively, but the Youden index was just 0.3 (P < 0.05).

CONCLUSION

The PCLI decreases due to the increase in Y instead of the decrease in X with time, especially in the chronic phase. The change in X in this process may be offset during imaging. In addition, there are fewer influencing factors that lead to changes in the PCLI. Therefore, it can be used as a reliable indirect sign of ACL rupture. However, it is difficult to quantify the diagnostic criteria of the PCLI in clinical practice. Thus, the PCLI as a reliable indirect sign of ACL rupture is associated with the course of knee joint injury, and it can be used to describe the instability of the knee joint.

LEVELS OF EVIDENCE

III.

Development of new cartilage lesions after ACL reconstruction is associated with abnormal knee rotation

PURPOSE

The purpose of this study is to examine the association between the development of articular cartilage pathology and knee rotation after single-bundle anterior cruciate ligament (ACL) reconstruction.

METHODS

Seventeen patients that underwent single-bundle ACL reconstruction and did not have any cartilage lesions at the time of surgery based on the Outerbridge classification or meniscal injury that required meniscectomy > 20% were examined by MRI and in the biomechanics laboratory at a 6-year minimum follow-up. Cartilage lesions that occurred after reconstruction were graded on MRI according to a modified Noyes scale. For cartilage evaluation, the lateral and medial femoral condyles were divided into 9 segments each (lateral, central, and medial third and each third was divided into anterior, central, and posterior segment). Tibial rotation during a pivoting task was measured with optoelectronic motion analysis system and side-to-side differences of tibial rotation between the reconstructed and contralateral intact knees were calculated. The association between the total modified Noyes scale score (outcome variable) and side-to-side differences of tibial rotation after controlling for meniscectomy and meniscal repair was investigated with hierarchical regression models.

RESULTS

Side-to-side difference of tibial rotation was associated with total modified Noyes scale score (p = 0.015, β = 0.667, adjusted R² = 42.1%). All patients developed new cartilage lesions in MRI located mainly at the central region of the lateral femoral condyle and less frequently in the central and anterior regions of the medial femoral condyle.

CONCLUSION

Abnormally increased tibial rotation that persists after ACL-R is significantly associated with the development of new articular cartilage lesions at mean 8.4 years after reconstruction which were located mainly at the central region of the LFC and secondarily in the central and anterior regions of the MFC (more superficial lesions). These findings suggest that there is emerging evidence that abnormal rotational kinematics is a potential risk factor for the pathogenesis and onset of posttraumatic articular cartilage degeneration after ACLR.

LEVEL OF EVIDENCE

IV.

Coronal subluxation of the tibiofemoral joint before and after anterior cruciate ligament reconstruction

Background

Studies have shown that medial subluxation of the tibia occurs after anterior cruciate ligament (ACL) rupture. However, it is unclear whether anterior cruciate ligament reconstruction (ACLR) can correct tibial coronal subluxation.

Purpose

To determine whether the tibia is medially subluxated after ACL rupture, and whether ACLR can correct medial subluxation of the tibia.

Study design

Case series; Level of evidence, 4, Retrospective clinical study.

Methods

The distance of tibial coronal subluxation before and after ACLR surgery was measured in 48 patients with ACL rupture and meniscus injury. Tibiofemoral subluxation was defined as the perpendicular distance between the long axis of the tibia and a second parallel line originating at the most proximal aspect of the femoral intercondylar notch. To determine the long axis of the tibia, two circles separated by 5 cm were centered on the proximal tibia. The proximal circle is 5 cm from the tibial plateau, and the distal circle is 5 cm from the proximal circle. The line passing through the center of the two circles was considered the long axis of the proximal tibia. Care was taken to ensure that each patient lied on the back with their patellae facing upward, to minimize rotational variation among the radiographs. At the same time, 30 patients with simple meniscus injury who underwent arthroscopy during the same period were selected to determine the degree of tibiofemoral coronal subluxation as the baseline value. The changes before and after operation were compared, as well as the differences with the baseline data.

Result

The average follow-up period was 21.2 ± 5.8 months. The average distance of tibial coronal subluxation before ACLR was 5.5 ± 2.1 mm, which was significantly different from that of baseline group (7.3 ± 2.1 mm) (P < 0.001). The tibial subluxation after ACLR was 7.7 ± 2.6 mm, which was significantly different from that before operation (P < 0.001). There was no significant difference in the distance between postoperative tibial subluxation and baseline group (P = 0.472).

Conclusion

The tibia was coronally medially subluxated after ACL rupture. ACLR can correct the medial subluxation of tibia. This finding is helpful in the diagnosis of ACL rupture, and can be used to assess the imaging status of the tibiofemoral joint on the coronal plane during or after ACLR.

The clinical relevance of PCL index on the reconstruction of anterior cruciate ligament with hamstring tendon autograft

The posterior cruciate ligament index (PCL index) has been reported as a diagnostic and prognostic marker for anterior cruciate ligament (ACL) reconstruction. The clinical relevance of PCL index on the reconstruction of ACL with hamstring tendon autograft has not been described in the literature. The objective of this study is to evaluate the importance of the PCL index as a marker of anatomic reconstruction and of functional improvement of patients undergoing ACL reconstruction with HT autograft. Twenty-four patients were submitted to ACL reconstruction with HT autograft. The PCL index was assessed by magnetic resonance imaging before and after surgery. The functional evaluation was performed through the International Knee Documentation Committee (IKDC) Subjective Knee Evaluation Form© and Knee Society Knee Scoring System© (IKS). Patients presented a significant positive variation of the PCL index, IKDC and IKS scores. There is no significant correlation between PCL index variation and IKDC and IKS scores (p > 0.05). Unlike other studies reporting a relationship between the PCL index, control of rotational kinematics, and functional improvement in patients undergoing ACL reconstruction with bone-patellar tendon-bone autograft, this study does not demonstrate this association. There is evidence in this study to show that the PCL index may be used as an anatomic reconstructive marker of ACL but not to predict the clinical outcome in this type of reconstruction.

Restoring tibiofemoral alignment during ACL reconstruction results in better knee biomechanics

PURPOSE

Anterior cruciate ligament (ACL) reconstruction (ACLR) aims to restore normal knee joint function, stability and biomechanics and in the long term avoid joint degeneration. The purpose of this study is to present the anatomic single bundle (SB) ACLR that emphasizes intraoperative correction of tibiofemoral subluxation that occurs after ACL injury. It was hypothesized that this technique leads to optimal outcomes and better restoration of pathological tibiofemoral joint movement that results from ACL deficiency (ACLD).

METHODS

Thirteen men with unilateral ACLD were prospectively evaluated before and at a mean follow-up of 14.9 (SD = 1.8) months after anatomic SB ACLR with bone patellar tendon bone autograft. The anatomic ACLR replicated the native ACL attachment site anatomy and graft orientation. Emphasis was placed on intraoperative correction of tibiofemoral subluxation by reducing anterior tibial translation (ATT) and internal tibial rotation. Function was measured with IKDC, Lysholm and the Tegner activity scale, ATT was measured with the KT-1000 arthrometer and tibial rotation (TR) kinematics were measured with 3Dmotion analysis during a high-demand pivoting task.

RESULTS

The results showed significantly higher TR of the ACL-deficient knee when compared to the intact knee prior to surgery (12.2° ± 3.7° and 10.7° ± 2.6° respectively, P = 0.014). Postoperatively, the ACLR knee showed significantly lower TR as compared to the ACL-deficient knee (9.6°±3.1°, P = 0.001) but no difference as compared to the control knee (n.s.). All functional scores were significantly improved and ATT was restored within normal values (P < 0.001).

CONCLUSIONS

Intraoperative correction of tibiofemoral subluxation that results after ACL injury is an important step during anatomic SB ACLR. The intraoperative correction of tibiofemoral subluxation along with the replication of native ACL anatomy results in restoration of rotational kinematics of ACLD patients to normal levels that are comparable to the control knee. These results indicate that the reestablishment of tibiofemoral alignment during ACLR may be an important step that facilitates normal knee kinematics postoperatively.

LEVEL OF EVIDENCE

Level II, prospective cohort study.

Hip and Knee Kinematics and Kinetics During Landing Tasks After Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-Analysis

OBJECTIVE

  To evaluate the current evidence concerning kinematic and kinetic strategies adopted during dynamic landing tasks by patients with anterior cruciate ligament reconstruction (ACLR).

DATA SOURCES

  PubMed, Web of Science.

STUDY SELECTION

  Original research articles that evaluated kinematics or kinetics (or both) during a landing task in those with a history of ACLR were included.

DATA EXTRACTION

  Methodologic quality was assessed using the modified Downs and Black checklist. Means and standard deviations for knee or hip (or both) kinematics and kinetics were used to calculate Cohen d effect sizes and corresponding 95% confidence intervals between the injured limb of ACLR participants and contralateral or healthy matched limbs. Data were further stratified by landing tasks, either double- or single-limb landing. A random-effects-model meta-analysis was used to calculate pooled effect sizes and 95% confidence intervals.

DATA SYNTHESIS

  The involved limbs of ACLR patients demonstrated clinically and significantly lower knee-extension moments during double-legged landing compared with healthy contralateral limbs and healthy control limbs (Cohen d range = -0.81 to -1.23) and decreased vertical ground reaction forces when compared with healthy controls, regardless of task (Cohen d range = -0.39 to -1.75).

CONCLUSIONS

  During single- and double-legged landing tasks, individuals with ACLR demonstrated meaningful reductions in injured-limb knee-extension moments and vertical ground reaction forces. These findings indicate potential unloading of the injured limb after ACLR, which may have significant implications for secondary ACL injury and long-term joint health.

Anterolateral rotatory instability in vivo correlates tunnel position after anterior cruciate ligament reconstruction using bone-patellar tendon-bone graft

AIM

To quantitatively assess rotatory and anterior-posterior instability in vivo after anterior cruciate ligament (ACL) reconstruction using bone-patellar tendon-bone (BTB) autografts, and to clarify the influence of tunnel positions on the knee stability.

METHODS

Single-bundle ACL reconstruction with BTB autograft was performed on 50 patients with a mean age of 28 years using the trans-tibial (TT) (n = 20) and trans-portal (TP) (n = 30) techniques. Femoral and tibial tunnel positions were identified from the high-resolution 3D-CT bone models two weeks after surgery. Anterolateral rotatory translation was examined using a Slocum anterolateral rotatory instability test in open magnetic resonance imaging (MRI) 1.0-1.5 years after surgery, by measuring anterior tibial translation at the medial and lateral compartments on its sagittal images. Anterior-posterior stability was evaluated with a Kneelax3 arthrometer.

RESULTS

A total of 40 patients (80%) were finally followed up. Femoral tunnel positions were shallower (P < 0.01) and higher (P < 0.001), and tibial tunnel positions were more posterior (P < 0.05) in the TT group compared with the TP group. Anterolateral rotatory translations in reconstructed knees were significantly correlated with the shallow femoral tunnel positions (R = 0.42, P < 0.01), and the rotatory translations were greater in the TT group (3.2 ± 1.6 mm) than in the TP group (2.0 ± 1.8 mm) (P < 0.05). Side-to-side differences of Kneelax3 arthrometer were 1.5 ± 1.3 mm in the TT, and 1.7 ± 1.6 mm in the TP group (N.S.). Lysholm scores, KOOS subscales and re-injury rate showed no difference between the two groups.

CONCLUSION

Anterolateral rotatory instability significantly correlated shallow femoral tunnel positions after ACL reconstruction using BTB autografts. Clinical outcomes, rotatory and anterior-posterior stability were overall satisfactory in both techniques, but the TT technique located femoral tunnels in shallower and higher positions, and tibial tunnels in more posterior positions than the TP technique, thus increased the anterolateral rotation. Anatomic ACL reconstruction with BTB autografts may restore knee function and stability.

Motion Task Selection for Kinematic Evaluation After Anterior Cruciate Ligament Reconstruction: A Systematic Review

PURPOSE

To examine the different motion tasks and the protocols used to objectively quantify dynamic stability in terms of knee kinematics at different stages of anterior cruciate ligament reconstruction (ACLR) recovery.

METHODS

A systematic search was done using OVID in Embase, Cochrane Central Register of Controlled Trials, Medline, PsychINFO, and AMED. A combination of the following keywords and their variations were used: anterior cruciate ligament, motion tasks (e.g., jump, hop, gait), and stability. The inclusion criteria were as follows: (1) ACLR subjects were recruited, (2) at least 1 motion task was performed and kinematics data were recorded, and (3) uninjured subjects or the contralateral uninjured limbs were included as a control group. Exclusion criteria were as follows: (1) non-English language publications, (2) retrospective studies and review articles, (3) animal studies, and (4) cadaveric studies.

RESULTS

The search returned 2,195 studies, and 56 were included in this review according to the criteria. A total of 1,086 ACLR subjects were included. Pivoting, landing, walking, running, stair negotiation, and squats were assessed using optoelectronic motion capture, electrogoniometry, or video-radiography.

CONCLUSIONS

The appropriate selection of motion tasks is an integral factor in dynamic stability testing as it evokes different kinematic outcomes in relation to the different stages of ACLR recovery. Stair negotiation and landing tasks are best performed during the early stages of recovery, and landing and pivoting are recommended 6 months after ACLR surgery.

LEVEL OF EVIDENCE

Level II, systematic review of Level I and II studies.

Spatial Change of Cruciate Ligaments in Rat Embryo Knee Joint by Three-Dimensional Reconstruction

This study aimed to analyze the spatial developmental changes of rat cruciate ligaments by three-dimensional (3D) reconstruction using episcopic fluorescence image capture (EFIC). Cruciate ligaments of Wister rat embryos between embryonic day (E) 16 and E20 were analyzed. Samples were sectioned and visualized using EFIC. 3D reconstructions were generated using Amira software. The length of the cruciate ligaments, distances between attachment points to femur and tibia, angles of the cruciate ligaments and the cross angle of the cruciate ligaments were measured. The shape of cruciate ligaments was clearly visible at E17. The lengths of the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) increased gradually from E17 to E19 and drastically at E20. Distances between attachment points to the femur and tibia gradually increased. The ACL angle and PCL angle gradually decreased. The cross angle of the cruciate ligaments changed in three planes. The primordium of the 3D structure of rat cruciate ligaments was constructed from the early stage, with the completion of the development of the structures occurring just before birth.