December 09, 2021
1 min read
MPFL reconstruction yields ‘excellent midterm results’ in skeletally immature patients
Regardless of patellar height and trochlear dysplasia, isolated medial patellofemoral ligament reconstruction yielded “excellent” midterm outcomes with low redislocation rates in skeletally immature patients, according to published results.
To determine whether bony abnormalities, such as patellar height and trochlear dysplasia, should be considered in skeletally immature patients undergoing isolated medial patellofemoral ligament (MPFL) reconstruction, Michael Schlumberger, MD, and colleagues analyzed outcomes of 45 MPFL reconstructions with gracilis tendon in 41 patients (mean age of 13.8 years). Outcome measures included the Tegner Activity Scale, IKDC subjective knee form, Lysholm scores, Kujala scores, as well as reoperations and redislocations, according to the study.
Among all procedures, 19 cases (42.2%) involved type A and B trochlear dysplasia, six cases (13.3%) involved type C trochlear dysplasia and one case (2.2%) involved type D trochlear dysplasia.
After a mean follow-up of 4.3 years, Schlumberger and colleagues determined patellar height and trochlear dysplasia had no influence on redislocation or clinical scores. Patellar redislocation occurred in three patients (6.7%). At final follow-up, mean Tegner score was 6.3; subjective IKDC score was 93.6; Lysholm score was 95.9 and Kujala score was 97.9.
“Isolated MPFL reconstruction as first-line surgical treatment in skeletally immature patients yields excellent midterm results, irrespective of patellar height and trochlear dysplasia,” the researchers concluded. “Redislocation still occurs in a certain number of patients, and a higher degree of retropatellar chondral lesion is a predictor for a worse clinical outcome,” they added.
Perspective
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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.
Shital N. Parikh, MD
Professor of orthopedic surgery
Cincinnati Children’s Hospital Medical Center
Cincinnati
Disclosures: Parikh reports no relevant financial disclosures.
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