Longitudinal Changes of Patellar Alignment Before and After Anterior Cruciate Ligament Reconstruction With Hamstring Autograft

Initial graft tension affects patellofemoral alignment during anatomical anterior cruciate ligament reconstruction

BACKGROUND

This study aimed to evaluate the effects of the differences in initial graft tension (IGT) on patellofemoral alignment in the axial plane after anatomical anterior cruciate ligament reconstruction (ACLR).

METHODS

A total of 102 patients who underwent primary anatomical ACLR using a bone-patellar-tendon-bone autograft were enrolled. The grafts were fixed with maximum manual force at full knee extension (higher graft tension; H group) and with 5-20 N at 20° knee flexion which corresponded to 80 N at full knee extension (lower graft tension; L group) pulls in 39 and 63 patients, respectively. All patients underwent computed tomography of the bilateral knee joints with knee extension 1 week postoperatively. The patellofemoral alignment (sulcus angle, lateral trochlear inclination angle, lateral patellofemoral angle (LPFA), condylar-patellar angle (CPA) (lateral facet, patellar tilt), congruence angle, and bisect offset index) on the axial computed tomography images were evaluated, and the side-to-side differences (SSDs) between the injured knee and the contralateral knee were calculated.

RESULTS

Congruence angle SSD was remarkably higher in the H group than in the L group (3.8 ± 4.7 vs. 0.4 ± 5.7, P < 0.01). Furthermore, the LPFA SSD and CPA (patellar tilt) SSD were significantly higher in the H group (-1.8 ± 3.1 vs. -0.4 ± 2.7, P = 0.04 and -1.6 ± 2.8 vs. -0.3 ± 2.7, P = 0.04, respectively).

CONCLUSIONS

A higher IGT during anatomical ACLR induces a lateral shift and tilt of the patella against the femur immediately after surgery compared with the lower IGT.

Clinical and Radiological Outcomes After Combined ACL and MPFL Reconstruction Versus Isolated ACL Reconstruction for ACL Injury With Patellar Instability

BACKGROUND

An anterior cruciate ligament (ACL) injury accompanied by patellar instability (PI) is a topic that has gained orthopaedic surgeons' attention recently. Untreated PI is reportedly associated with worse clinical outcomes after isolated ACL reconstruction (ACLR) in patients after an ACL injury with PI. Nevertheless, the appropriate surgical approach and its long-term therapeutic effects in these patients remain unclear.

PURPOSE

(1) To compare the clinical and radiological outcomes between isolated ACLR (iACLR) and combined ACLR and medial patellofemoral ligament reconstruction (cAMR) in patients after an ACL injury with PI and (2) to explore the correlations between these 2 procedures and clinical and radiological outcomes.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 106 patients diagnosed with an ACL injury accompanied by PI between January 2016 and April 2021 were analyzed in this study. There were 34 patients excluded because of missing postoperative radiological data. Among the remaining 72 patients, 34 patients underwent iACLR, while 38 patients underwent cAMR. Demographic characteristics, intraoperative findings, and patient-reported outcomes (Lysholm score, subjective International Knee Documentation Committee score, and Tegner activity score) were prospectively collected. Patellar alignment parameters and worsening patellofemoral osteoarthritis (PFOA) features (evaluated with the modified Whole-Organ Magnetic Resonance Imaging Score) were analyzed longitudinally on magnetic resonance imaging. The Kujala score was used to evaluate the functional recovery of the patellofemoral joint, and redislocations of the patella were prospectively recorded. Finally, multivariate logistic regression analysis was used to explore the correlations between these 2 procedures and clinical (not achieving the minimal detectable change [MDC] for the Lysholm score) and radiological (worsening PFOA features) outcomes.

RESULTS

The mean follow-up duration was 28.9 ± 6.2 and 27.1 ± 6.8 months for the iACLR and cAMR groups, respectively (P = .231). Significantly higher Lysholm scores (88.3 ± 9.9 vs 82.1 ± 11.1, respectively; P = .016) and subjective International Knee Documentation Committee scores (83.6 ± 11.9 vs 78.3 ± 10.2, respectively; P = .046) were detected in the cAMR group compared with the iACLR group postoperatively. The rates of return to preinjury sports were 20.6% and 44.7% in the iACLR and cAMR groups, respectively (difference, 24.1% [95% CI, 3.3%-45.0%]; P = .030). Moreover, the rates of worsening PFOA features were 44.1% and 18.4% in the iACLR and cAMR groups, respectively (difference, 25.7% [95% CI, 4.9%-46.4%]; P = .018). In addition, significantly higher Kujala scores (87.9 ± 11.3 vs 80.1 ± 12.0, respectively; P = .006), lower redislocation rates (0.0% vs 11.8%, respectively; difference, 11.8% [95% CI, 0.9%-22.6%]; P = .045), and significantly better patellar alignment were detected in the cAMR group compared with the iACLR group postoperatively. Furthermore, multivariate logistic regression analysis determined that iACLR and partial lateral meniscectomy were significantly correlated with not achieving the MDC for the Lysholm score and worsening PFOA features in our study population.

CONCLUSION

In patients after an ACL injury with PI, cAMR yielded better clinical and radiological outcomes compared with iACLR, with better patellar stability and a lower proportion of worsening PFOA features. Furthermore, not achieving the MDC for the Lysholm score and worsening PFOA features were significantly correlated with iACLR and partial lateral meniscectomy. Our study suggests that cAMR may be a more appropriate procedure for patients after an ACL injury with PI, which warrants further high-level clinical evidence.

Characterization of the CT-based risk factors for concomitant patellofemoral instability in patients with anterior cruciate ligament injury

OBJECTIVES

Underestimation of concomitant patellofemoral instability in patients with anterior cruciate ligament (ACL) injury has aroused extensive attention. However, the characteristics of the combined injury is not well recognized. Hence, we aimed to characterize the features of the combined injury, and determine the radiographic risk factors.

METHODS

Fifteen radiological parameters were identified after discussion and pilot-tested. Radiographic measurements were compared using the analysis of variance model with Tukey post hoc analysis. A stepwise binomial logistic regression was performed and a nomogram model combining the significant risk factors was created. The model performance was validated by C-index, calibration plot, and decision curve.

RESULTS

A total of 204 patients (mean [SD] age, 25.1 [6.7] years; 108 [52.9%] male) were included. The final model was updated through regression analysis using 4 parameters as significant risk factors: lateral femoral condyle ratio (OR (95% CI), 1.194 (1.023 to 1.409)), medial anterior tibial subluxation (mATS) (OR (95% CI), 1.234 (1.065 to 1.446)), medial posterior plateau tibial angle (mPPTA) (OR (95% CI), 1.266 (1.088 to 1.500)), and trochlear depth (OR (95% CI), 0.569 (0.397 to 0.784)). C-index for the nomogram was 0.802 (95% CI, 0.731 to 0.873) and was confirmed to be 0.784 through bootstrapping validation. Calibration plot established a good agreement between prediction and observation. Decision curve analysis showed that if threshold probability was over 10%, using the nomogram adds more benefit than either all or none scheme.

CONCLUSIONS

Lateral femoral condyle ratio, mATS, mPPTA, and trochlear depth are strong adverse predictors of patellofemoral instability in patients with ACL injury.

CLINICAL RELEVANCE

This study characterizes the radiological features of the combined injury. Patellofemoral instability should be noted when treating ACL injuries.

KEY POINTS

• The radiological characteristics of the combined ACL injury and patellofemoral instability is not well recognized. • Lateral femoral condyle ratio, mATS, mPPTA, and trochlear depth are predominant risk factors for patellofemoral instability in patients with ACL injury. • Patellofemoral instability should be noted when treating ACL injuries.

Persistent underloading of patellofemoral joint following hamstring autograft ACL reconstruction is associated with cartilage health

OBJECTIVE

To determine the longitudinal changes of patellofemoral joint (PFJ) contact pressure following anterior cruciate ligament reconstruction (ACLR). To identify the associations between PFJ contact pressure and cartilage health.

DESIGN

Forty-nine subjects with hamstring autograft ACLR (27 males; age 28.8 [standard deviation, 8.3] years) and 19 controls (12 males; 30.7 [4.6] years) participated. A sagittal plane musculoskeletal model was used to estimate PFJ contact pressure. A combined T1ρ/T2 magnetic resonance sequence was obtained. Assessments were performed preoperatively, at 6 months, 1, 2, and 3 years postoperatively in ACLR subjects and once for controls. Repeated Analysis of Variance (ANOVA) was used to compare peak PFJ contact pressure between ACLR and contralateral knees, and t-tests to compare with control knees. Statistical parametric mapping was used to evaluate the associations between PFJ contact pressure and cartilage relaxation concurrently and longitudinally.

RESULTS

No changes in peak PFJ contact pressure were found within ACLR knees over 3 years (preoperative to 3 years, 0.36 [CI, -0.08, 0.81] MPa), but decreased over time in the contralateral knees (0.75 [0.32, 1.18] MPa). When compared to the controls, ACLR knees exhibited lower PFJ contact pressure at all time points (at baseline, -0.64 [-1.25, -0.03] MPa). Within ACLR knees, lower PFJ contact pressure at 6 months was associated with elevated T2 times (r = -0.47 to -0.49, p = 0.021-0.025).

CONCLUSIONS

Underloading of the PFJ following ACLR persists for up to 3 years and has concurrent and future consequences in cartilage health. The non-surgical knees exhibited normal contact pressure initially but decreased over time achieving limb symmetry.

Risk factors of cartilage lesion after anterior cruciate ligament reconstruction

Anterior cruciate ligament injury is the most common sports injury in orthopaedics, which can adversely affect knee joint function and exercise of patients. Using arthroscopy to reconstruct the anterior cruciate ligament has become the first choice for treating anterior cruciate ligament rupture. However, different degrees of articular cartilage injury of the knee can be observed in patients after anterior cruciate ligament reconstruction. More importantly, the articular cartilage injury after anterior cruciate ligament reconstruction indicates that it will develop into osteoarthritis in the long term. It is of great significance to fully understand the factors that lead to the occurrence and development of cartilage injury. This article reviews the effects of surgical methods, meniscus status, different grafts, time from injury to surgical intervention, postoperative knee joint stability, postoperative rehabilitation, knee joint anatomical factors, and demographic characteristics of patients on articular cartilage degeneration after anterior cruciate ligament reconstruction. The present review provides insights into the anterior cruciate ligament reconstruction, which can be used to investigate new treatment strategies to delay and prevent the progress of osteoarthritis. At the same time, it provides a holistic understanding of the influence of multiple factors on cartilage lesions after anterior cruciate ligament reconstruction.