Qualitative and Quantitative 3-T MR Imaging Outcome after Reconstruction of the Medial Patellofemoral Ligament

Presentation Format: Oral presentation.

Purpose or Learning Objective: To evaluate quantitatively and semiquantitatively the 2-year magnetic resonance imaging (MRI) outcome after medial patellofemoral ligament (MPFL) reconstruction at the knee and to assess preoperative MRI risk factors.

Methods or Background: A total of 21 patients with MPFL reconstruction was included. MRI was performed preoperatively and 2 years after surgery. Clinical pulse sequences included two-dimensional (2D) intermediate-weighted turbo spin-echo (TSE) sequences in three planes and sagittal T1-weighted TSE sequences. At the postoperative time point, T2 and T1rho relaxation time measurements were additionally included for evaluation of quantitative cartilage matrix degeneration at the ipsilateral and at the contralateral knee. Morphological evaluation was conducted via the Whole-Organ Magnetic Resonance Imaging Score (WORMS) pre- and postoperatively. MRI-based patellar instability parameters were measured. Clinically, laxity of the patellofemoral joint, Kujala scores, and the Knee Injury and Osteoarthritis Outcome Score (KOOS) were assessed. Statistical analyses included descriptive statistics, t tests, multivariate regression models, and correlation analyses.

Results or Findings: The mean plus or minus standard deviation age of patients was 22 ± 6 years (10 female; 11 male). Two years after MPFL reconstruction, all patellae were clinically stable. WORMS scores improved significantly from baseline to follow-up (mean difference plus or minus standard error of the mean: − 4.0 ± 1.3; p = 0.005). As compared with patients with no increase in total WORMS scores over time (n = 16), patients with an increase in total WORMS scores (n = 5) had a lower trochlear depth (p = 0.016), an increased trochlear facet asymmetry (p = 0.023), and a higher sulcus angle (p = 0.001). Two years after MPFL surgery, mean cartilage T2 and T1rho values at the patella and at the global knee were similar at the ipsilateral and at the contralateral knee (global T2: 30.7 ± 3.3 ms versus 30.7 ± 3.5 ms; p = 0.911; global T1rho: 39.2 ± 2.8 ms versus 38.7 ± 2.6 ms; p = 0.209). Preoperatively, higher lateral patella tilt (R = 0.540; p = 0.011) and higher tibial tuberosity to trochlear groove (TTTG) distance (R = 0.508; p = 0.019) were associated with higher postoperative patellar T1rho values. Higher global cartilage T2 values at follow-up showed a significant correlation with a worse clinical score for sport and recreation function (R = − 0.524; p = 0.015).

Conclusion: At 2-year follow-up, MPFL reconstruction showed an overall favorable qualitative and quantitative MRI outcome with restored clinical patellofemoral stability. MRI-based patellar instability parameters may be predictive for progressive degenerative changes at the knee joint after MPFL reconstruction.

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Publikationsverlauf

Artikel online veröffentlicht:
03. Juni 2021