Tibial fractures after tibial tubercle osteotomies for patellar instability: a comparison of three osteotomy configurations.

PURPOSE

Tibial tubercle osteotomies (TTOs) are a seemingly straightforward technique; however problems with bony union, implant failure, wound infections, and fractures have been reported in the literature.

METHODS

A database search identified all patients who had a TTO performed for patellofemoral instability between 1 March 2000 and 30 July 2008 by a single surgeon. The TTO technique was modified twice during the study period (December 2003 and June 2007, respectively), thereby creating three similar patient cohorts.

RESULTS

TTOs were performed in 101 knees (90 patients), in which 34 knees (29 patients) received the blunt technique (TTO-B), 32 knees (30 patients) the sloped technique (TTO-S), and 35 knees (31 patients) the greenstick technique (TTO-G). Mean age of the patients (75 females, 15 males) was 16.0 years (range 12.2-20.2 years). Overall, six patients had complications, namely, six tibia fractures and no nonunions, for an overall complication rate of 5.9%. In the TTO-B group, four patients had four tibia fractures for an overall bony complication rate of 11.8%. In the TTO-S group, two patients had two delayed unions which developed into tibia fractures for an overall bony complication rate of 6.2%. There were no complications (0%) in the TTO-G group. No correlation was identified between TTO screw size and complications. The caudal aspect of the osteotomy was the location of the tibia fracture in five knees and the caudal screw in 1 knee, at a mean of 11 weeks postoperatively. All fractures were treated only with splint or cast immobilization and protected weight-bearing.

CONCLUSION

The overall bony complication rate was 5.9% for the TTOs in this study. Utilizing the TTO-G technique with rigid two-screw, bicortical fixation the complication rate could be lowered to 0%. Avoidance of periosteal stripping, and secondary cortical devascularization at the caudal aspect of the TTO appears to optimize bony consolidation, thereby minimizing fractures.

CLINICAL RELEVANCE

Bony complications are an infrequent problem after TTO. Greensticking the distal end of the TTO can minimize postoperative tibia fractures. Running and sports should not be permitted until complete cortical healing is documented on the lateral radiograph.