Complications After Tibial Tuberosity Osteotomy Association With Screw Size and Concomitant Distalization

Background: Tibial tuberosity osteotomy (TTO) is a versatile procedure commonly used to treat patellar instability as well as to unload cartilage lesions. TTO with concomitant distalization (TTO-d) may be performed in patients with patella alta to stabilize the patella by helping it to engage in the trochlea earlier during flexion. Purpose: To identify and compare perioperative complications in patients who underwent TTO and those who underwent TTO-d and to analyze risk factors associated with these complications. Study Design: Cohort study; Level of evidence, 3. Methods: We retrospectively identified perioperative complications and associated factors from medical records for 240 patients who underwent TTO with or without distalization performed by 2 surgeons at 2 institutions between 2009 and 2015. A musculoskeletal radiologist at each institution determined osteotomy union using a published grading system. Significance was set at P < .01. Results: Of the 240 patients, 153 (122 TTO, 31 TTO-d) had clinical and radiographic follow-up of at least 90 days or evidence of osseous union. Eighty-eight complications were identified in 71 of 153 (46%) patients: delayed union (n = 35); painful hardware (n = 32); deep vein thrombosis (n = 4); clinical nonunion, delayed range of motion, sensory deficit, and wound breakdown (n = 3 each); and broken screw, fascial hernia, hematoma, quadriceps dysfunction, and tibial fracture (n = 1 each). Thirteen of 35 delayed unions occurred in the TTO-d group (P = .005). Painful hardware was more frequent in patients who received 4.5-mm screws (31/115) than in those who received 3.5-mm screws (1/38) (P = .001). A reoperation was required in 38 of 153 patients (37 patients using 4.5-mm screws vs 1 patient using 3.5-mm screws; P < .001), primarily for screw removal (32/38). Conclusion: Minor complications, including delayed union and painful hardware, were common, but major complications such as tibial fracture, deep vein thrombosis, and clinical nonunion were rare. Delayed union was more frequent in the TTO-d group. The 3.5-mm screws were less painful and less likely to need removal than the 4.5-mm screws.