The lateral patellar retinaculum is thicker in paediatric and adolescent patients with patellofemoral instability: An MRI analysis.

PURPOSE

The purpose of this study was to examine the thickness of the lateral patellar retinaculum (LPR) and patellar tilt in paediatric and adolescent patients who undergo a medial patellofemoral ligament (MPFL) reconstruction. The authors hypothesise that patients undergoing MPFL reconstruction will have a thicker LPR and increased patellar tilt when compared to a comparison cohort.

METHODS

Preoperative magnetic resonance imaging (MRI) of patients ≤ 18 years old who underwent an MPFL reconstruction was retrospectively reviewed. Patients were included if they had a proton density preoperative axial MRI performed internally at our institution. Included patients were matched to a comparison cohort. LPR thickness and patellar tilt were measured on MRI. LPR thickness and patellar tilt were compared between the MPFL cohort and the comparison cohort.

RESULTS

A total of 363 patients were identified. 145 participants were successfully matched to the comparison cohort. The mean age in the MPFL cohort was 14.4 ± 2.0 years and 68% were female. The LPR thickness in the MPFL cohort was significantly greater than the LPR thickness in the comparison cohort ( < 0.001). The patellar tilt was significantly greater in the MPFL cohort compared to the control cohort ( < 0.001). There was no statistical difference in patients undergoing MPFL reconstruction and the occurrence of a lateral release/lengthening procedure.

CONCLUSION

The LPR was significantly thicker on preoperative MRI in patients undergoing MPFL reconstruction compared to a comparison cohort, indicating that increased LPR thickness is a potential marker of patellofemoral instability on imaging.

LEVEL OF EVIDENCE

Level III.