Imaging findings and clinical function after combined surgery for recurrent patella dislocation: a comparative study

Background: Limited research has evaluated imaging results following a combination of operations for recurrent patella dislocation (RPD) based on medial patellofemoral ligament (MPFL) reconstruction. Therefore, this study aimed to retrospectively compare the imaging and clinical results of RPD following 2 types of combined surgical techniques. Methods: Patients who underwent combined surgery for RPD from January 2008 to December 2019 were enrolled in the study and allocated into 2 groups. MPFL reconstruction combined with lateral retinacular release (LRR) was performed in groups A and B, and an additional tibial tuberosity transfer (TTT) was performed in group B only. Patients in group A with a tibial tuberosity trochlear groove (TT-TG) distance greater than 15 mm were included in subgroup A*. Congruence angle (CA), patellar tilt angle (PTA), lateral patellofemoral angle (LPA), lateral patellar displacement (LPD), TT-TG, Insall-Salvati Index (ISI), the Dejour type of trochlear dysplasia, and knee function were assessed. All groups were followed up in the short-term (1-2 years), and group B was also followed up in the mid-term (over 5 years). Results: A total of 40 knees (36 patients) were included in group A, 26 knees (24 patients) in subgroup A*, and 27 knees (26 patients) in group B. In group A, CA, PTA, and LPD had increased at the short-term follow-up, yet LPA had decreased compared to the results 3 days after surgery. In group B, at the midterm follow-up, PTA (12.54 +/- 6.88 vs. 15.23 +/- 6.10; P=0.002) increased while LPD (7.08 +/- 6.48 vs. 4.69 +/- 6.28; P=0.049) decreased compared with the short-term outcomes. The more severe the femoral trochlear dysplasia, the lower the mid-term Kujala scores in group B (P=0.007). The short-term TT-TG (17.32 +/- 4.288 vs. 12.84 +/- 3.758; P<0.001) and ISI [1.25 (1.1075, 1.300) vs. 1.06 (1.00, 1.16); P<0.001] in group B were lower than those in group A, who had a higher Kujala score (P<0.001). The CA, LPD, ISI, TT-TG, and Kujala score in subgroup A* were higher than those in group B at the short-term follow-up (P<0.05). Conclusions: Both types of combination treatments were successful in altering the patellofemoral joint in a satisfactory manner, and the knee function improved in both groups. A TTT might not be necessary for patients with a TT-TG distance greater than 15 mm.

Automated summary

This study retrospectively compared the imaging and clinical outcomes of two types of combination surgeries for recurrent patella dislocation (RPD). The results showed that both surgical techniques were effective in improving the patellofemoral joint and knee function. Tibial tuberosity transfer (TTT) may not be necessary for patients with a TT-TG distance greater than 15 mm.