Outcomes And Reoperation Rates After Tibial Tubercle Transfer And Medial Patellofemoral Ligament Reconstruction

Abstract

Objectives: Patellofemoral instability (PFI) is a painful condition affecting approximately 7 patients per 100,000 in the US. Unfortunately, as many as 50% of young patients with patellar dislocations can go on to recurrent instability and have debilitating symptoms. With a wide range of operative techniques, and subsequent reoperation and complication rate cited in the literature, it becomes challenging to create an appropriate algorithm with which to treat patients. The goal of our study was to determine the reoperation rate, risk factors for reoperation, and patient reported outcomes after Tibial Tubercle Transfer (TTT), Medial Patellofemoral Ligament Reconstruction (MPFLR), or a combination of the two, for patellofemoral instability surgery. Methods: We retrospectively identified patients who underwent MPFLR and TTT by querying the surgical database at our single institution from 2002-2018 for CPT codes associated with the procedures (CPT-27418, CPT-27427). Patients were included if they had an MPFLR and/or TTT performed for PFI whether recurrent or single dislocation. Patients were excluded if either additional ligamentous reconstruction was performed simultaneously, indications for the procedure was for a condition other than PFI or if records were incomplete. 497 patients were eligible to be included. Radiographic measurements, demographic parameters, and subsequent revision procedures and their indications were identified. A modified anterior knee pain survey was conducted by mail and with follow-up phone survey. Chi-Square Tests or Fishers Exact Test were used to compare differences for categorical data and Wilcoxon rank sum tests were used to compare the non-parametric pain scores. A multivariable logistic regression was used to determine the association between patient demographics, radiographic parameters and procedure type. Results: The overall rate of reoperation amongst all patients was 25.6%. The rate of reoperation for MPFL alone (19.9%) was lower than that of TTT alone (34.8%) or both procedures simultaneously (26.4%) (P = .007). There was a trend towards increased major reoperation rates and revision stabilization procedures in patients with isolated TTT (P = .16). There was no association with tibial tubercle to trochlear groove (TTTG) distance and the rate of reoperation (P = .99). A preoperative Dejour classification D was associated with a higher reoperation rate (28%) than those with Dejour A-C (P=.43). A Caton-Deschamp ratio >1.3 increased the odds of having a revision stabilization surgery (odds ratio 2.303). Patients who had a revision surgery for any reason were more likely to report pain while walking compared to those who did not (P = <.0001). Conclusion: The overall reoperation after PFI surgery is higher than previously reported. Patients who underwent further procedures were more likely to report continued knee pain when walking. Our results would suggest that patients with trochlear dysplasia and patella alta are more likely to undergo future procedures for instability, and may benefit from more aggressive initial treatment, such as MPFLR and TTT in combination.