Summary
Excessive tibiofemoral rotation angle can predict primary MPFL-R failure with high reliability.
Abstract
Purpose
To determine whether an increased tibiofemoral rotation angle was associated with graft failure after primary medial patellofemoral ligament reconstruction (MPFL-R) and to investigate the role of the tibiofemoral rotation angle in predicting MPFL-R failure in patients with RPD.
Methods
A total of 632 consecutive patients with clinically diagnosed RPD from 2011 to 2018 were retrospectively analyzed. Postoperative stress radiography of patellofemoral joint was performed to identify whether the graft failed. Among them, 33 patients who showed failed MPFL-R were allocated into the failure group. They were matched 1:2 to 66 control participants who underwent successful MPFL-R (control group). The cutoff value and the area under the curve (AUC) of the tibiofemoral rotation angle for predicting graft failure after primary MPFL-R were determined by the receiver operating characteristic curve (ROC). Moreover, risk factors for primary MPFL-R failure were assessed by multivariate logistic regression analysis.
Results
The tibiofemoral rotation angle was significantly higher in the failure group than in the control group (16.4°±5.6° vs. 6.4°±4.5°; P<0.001). The cutoff value of the tibiofemoral rotation angle for predicting graft failure after MPFL-R failure was 12.3° (sensitivity, 81.8%; specificity, 89.4%; AUC, 0.920). Additionally, an excessive tibiofemoral rotation angle (>12.3°, odds ratio, 13.159 [95% CI, 2.469-70.139]; P=0.003) was determined to be the risk factor for primary MPFL-R failure.
Conclusion
Excessive tibiofemoral rotation angle can be regarded as a risk factor for graft failure after primary MPFL-R in patients with RPD. More importantly, an excessive tibiofemoral rotation angle (>12.3°) predicts primary MPFL-R failure with high reliability, which may help surgeons identify patients at high risk of graft failure before surgery.