Shital N. Parikh, MD

There are two distinct schools of thought when it comes to addressing patellar instability. The first approach to stabilization is the à la carte approach where each major anatomic abnormality (patellar height, trochlear dysplasia, tibial tubercle lateralization, lateral patellar tilt) is surgically corrected. The second school of thought emerged when MPFL reconstruction gained popularity as an effective method for patellar stabilization. The encouraging results of MPFL reconstruction have led to a decline in other proximal realignment procedures, like MPFL repair, medial imbrication and VMO advancement. Over a period, combined approach (MPFL reconstruction and correction of major underlying anatomic abnormality) has been advocated by many physicians. The rationale of such an approach is that correction of abnormal anatomy would allow for proper patellofemoral tracking and MPFL reconstruction would provide a checkrein to prevent patellar dislocation. However, it is not known if such a combined approach is necessary or if isolated MPFL reconstruction can compensate for underlying anatomic risk factors.

The authors of the current study report excellent results following 45 isolated MPFL reconstructions in skeletally immature patients at a mean of 4.3 years, irrespective of underlying anatomic risk factors. The safety of MPFL femoral attachment below the level of distal femoral physis using an interference screw was established as there were no clinically important growth disturbances. There were three (6.7%) redislocations, but there were no significant differences in redislocation rates or patient-reported outcome scores in patients with or without patella alta (CD ratio >1.2) or trochlear dysplasia. The findings of this study call into question the need to address anatomic risk factors during MPFL reconstruction. The study provides weak evidence that isolated MPFL reconstruction can yield satisfactory results in presence of patella alta or trochlear dysplasia but does not provide information on presence of other anatomic risk factors or combination of such risk factors.

A major drawback of the study is the lack of power analysis. It is important to note that both Lysholm and Kujala scores were lower in patients with high-grade patellar chondral lesions. This finding helps to justify authors’ aggressive approach to early patellar stabilization as 20 (44.4%) MPFL reconstructions in this study were performed after first patellar dislocation, even without an osteochondral fracture.

Overall, it seems that isolated MPFL reconstruction would provide satisfactory midterm clinical and radiographic outcomes in skeletally immature patients with patellar instability, irrespective of underlying anatomic abnormalities.