Patellar instability MRI measurements are associated with knee joint degeneration after reconstruction of the medial patellofemoral ligament

Abstract

Objective To qualitatively and quantitatively evaluate the 2-year magnetic resonance imaging (MRI) outcome after MPFL reconstruction at the knee and to assess MRI-based risk factors that predispose for inferior clinical and imaging outcomes. Materials and methods A total of 31 patients with MPFL reconstruction were included (22 ± 6 years, 10 female). MRI was performed preoperatively in 21/31 patients. Two-year follow-up MRI included quantitative cartilage T2 and T1rho relaxation time measurements at the ipsilateral and contralateral knee. T2relative was calculated as T2patellofemoral/T2femorotibial. Morphological evaluation was conducted via WORMS scores. Patellar instability parameters and clinical scores were obtained. Statistical analyses included descriptive statistics, t-tests, multivariate regression models, and correlation analyses. Results Two years after MPFL reconstruction, all patellae were clinically stable. Mean total WORMS scores improved significantly from baseline to follow-up (mean difference ± SEM, − 4.0 ± 1.3; P = 0.005). As compared to patients with no worsening of WORMS subscores over time (n = 5), patients with worsening of any WORMS subscore (n = 16) had lower trochlear depth, lower facetal ratio, higher tibial-tuberosity to trochlear groove (TTTG) distance, and higher postoperative lateral patellar tilt (P < 0.05). T2relative was higher at the ipsilateral knee (P = 0.010). T2relative was associated with preoperatively higher patellar tilt (P = 0.021) and higher TTTG distance (P = 0.034). TTTG distance, global T2 values, and WORMS progression correlated with clinical outcomes (P < 0.05). Conclusion MPFL reconstruction is an optimal treatment strategy to restore patellar stability. Still, progressive knee joint degeneration and patellofemoral cartilage matrix degeneration may be observed, with patellar instability MRI parameters representing particular risk factors.

Elevated Patellofemoral and Tibiofemoral T1ρ Relaxation Times Following a First Time Patellar Dislocation

“…T1ρ relaxation times are more sensitive to concentration of proteoglycans, and T2 relaxation times are more sensitive to collagen structure. 15 Previous studies focused on general patellar instability, 8 multiple dislocations, 16,17 and surgical treatment for patellar dislocation 18 have shown elevated T2 relaxation times for cartilage on the patella. 18 A specific focus on the acute phase following a first-time patellar dislocation is lacking, but needed for longitudinal characterization of cartilage degradation.…”

“…15 Previous studies focused on general patellar instability, 8 multiple dislocations, 16,17 and surgical treatment for patellar dislocation 18 have shown elevated T2 relaxation times for cartilage on the patella. 18 A specific focus on the acute phase following a first-time patellar dislocation is lacking, but needed for longitudinal characterization of cartilage degradation. Quantitative MRI-based evaluation of cartilage within the trochlear groove and tibiofemoral joint is also lacking.…”

The remaining parameters of patellar instability could be affected for osteoarthritic change after medial patellofemoral ligament reconstruction with or without anteromedialization of the tibial tubercle osteotomy for patellar instability: a retrospective cohort study

“…In this study, the patellar position remained lateral, and a lateral patellar position may lead to increased contact pressure to the lateral facet of the trochlea as previously described [ 9 ]. Giesler et al [ 46 ] reported that trochlear dysplasia parameters, TT-TG distance, and postoperative persistent high lateral patellar tilt were risk factors for progressive knee joint degeneration after MPFLR. This suggests that the remaining parameters of patellar instability could be affected for the progression of PFOA after patellar stabilization surgery.…”

Are Patellofemoral Ligaments and Retinacula Distinct Structures of the Knee Joint? An Anatomic, Histological and Magnetic Resonance Imaging Study

“…Although multiple MPFL reconstruction techniques have been described, the ideal surgical procedure for MPFL on the patellar side remains controversial [41], and the ideal stiffness after MPFL reconstruction remains unclear [51,52]. Although several studies have indicated that combined MPFL reconstruction with trochleoplasty can result in good postoperative stability and patient satisfaction [53,54], many concerns have been raised about the complication rate and the risk to the cartilage and progression of arthritis in the patellofemoral joint after this procedure [55,56].…”