Summary

The study is a retrospective MRI review of all patients undergoing MPFL reconstruction at a single institution to assess for its sensitivity in detecting acute and chronic MPFL injuries.

Abstract

Introduction

In patients with patellar instability due to one or more traumatic events, ligamentous laxity, or predisposing anatomic factors, magnetic resonance imaging (MRI) is the diagnostic imaging modality of choice to evaluate the integrity of the medial patellofemoral ligament (MPFL). For patients with recurrent instability who have failed conservative management and have an acute or chronic MPFL rupture, reconstruction with a variety of grafts can be offered in isolation or in combination with other open and arthroscopic procedures to treat instability. However, there are no studies known to the authors that evaluate the sensitivity and specificity of MRI for diagnosing MPFL injury. The purpose of this study is to evaluate the diagnostic utility of MRI in these injuries.

Methods

A retrospective review from January 2016 to September 2021 was completed within the Department of Orthopaedic Surgery at a single institution. All CPT codes related to MPFL reconstruction were searched within the hospital’s electronic medical record system. Inclusion criteria were all patients undergoing MPFL reconstruction either in isolation or with a combined procedure. Exclusion criteria included infection, fracture to proximal tibia or distal femur, open injuries, and patients without a pre-operative MRI. The primary outcomes measure was sensitivity of MRI in detecting MPFL rupture based on intra-operative findings.

Results

After exclusion, 113 patients were included in our analysis, including 52 males and 61 females. 110 underwent primary MPFL reconstruction with allograft, 1 revision MPFL reconstruction with allograft, and 1 ORIF of an osteochondral fragment. In these patients with confirmed intra-operative findings of MPFL injury, 27/113 (23.9%) were read as intact on the final dictated radiology reported. Interestingly, 43/113 (38.1%) of MRI reports did not make any specific mention of the MPFL. For MRI reports in which the MPFL was specifically analyzed, 27/70 (38.6%) of reports read the MPFL as intact.

Conclusion

In our study, the sensitivity of MRI for acute or chronic MPFL rupture was 61.4% high for patients with confirmed intra-operative findings of injury and MRI reports specifically evaluating the MPFL. In addition, there was a significant percentage of patients in which the integrity of the MPFL was not mentioned. This study highlights that MPFL may not be the most sensitive diagnostic modality for MPFL injury. In addition, it highlights the need for effective communication between orthopaedic surgeons and musculoskeletal radiologists to analyze the desired structure of interest in their dictated reports.