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

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.

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).

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 mid-term 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).

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.