Difference in Characteristics of Patients Undergoing Revision MPFL Reconstruction and Those Undergoing Primary MPFL Reconstruction.

Abstract

Background: In recurrent patellar instability, medial patellofemoral ligament reconstruction (MPFLR), with or without concomitant bony procedures, has become the treatment of choice to stabilize the patellofemoral joint. In the setting of recurrent patellar instability after primary MPFLR, revision MPFLR can be considered. Numerous potential risk factors for failure of isolated primary MPFLR have been evaluated with mixed findings.

Purpose/hypothesis: The purpose of this study was to compare anatomic and demographic patient characteristics between patients undergoing primary and revision MPFLR. It was hypothesized that patients undergoing revision MPFLR will demonstrate a higher prevalence of anatomic risk factors and J-tracking and will demonstrate more articular cartilage damage than patients undergoing primary MPFLR.

Study design: Cross-sectional study; Level of evidence, 3.

Methods: A retrospective chart review was performed to identify patients who underwent primary MPFLR between 2009 and 2021 and revision MPFLR between 2009 and 2023. Patients were categorized into 2 groups based on whether they underwent primary or revision MPFLR. Demographic (age, sex, and body mass index [BMI]), anatomic characteristics (patellar height, trochlear morphology, and tibial tubercle-trochlear groove distance), physical examination findings (presence or absence of a J-sign), and intraoperative findings (articular cartilage damage of the patellofemoral joint) were compared between these groups.

Results: A total of 164 patients who underwent MPFLR within this period, including 26 revision and 138 primary procedures, were evaluated. No difference in patient age, sex, or any measure of patellar height was noted between the 2 groups. The revision MPFLR group was noted to have a higher BMI (29.9 kg/m² vs 27.2 kg/m²; P = .036), a higher mean sulcus angle (145° vs 140°; P = .007), more frequent presence of a crossing sign (77% versus 18%; P < .001), and were more likely to have a J-sign (42% vs 22%; P = .048) than the primary MPFLR group. Intraoperatively, the revision MPFLR group had a higher prevalence of articular cartilage damage (81% versus 37%; P < .0001) than the primary MPFLR group.

Conclusion: Patients undergoing revision MPFLR had more prior patellar dislocations, higher BMI, and more trochlear dysplasia (increased sulcus angle and more frequent crossing sign) than those undergoing primary MPFLR. The revision group was also more likely to have a J-sign on clinical examination and patellar articular cartilage damage at the time of arthroscopy.