Evaluation of the risk of patella fracture as the result of decreasing tibial plateau angle following tibial plateau leveling osteotomy.

OBJECTIVE

To evaluate the effect of postoperative tibial plateau angle (TPA) following tibial plateau leveling osteotomy (TPLO) on the risk of patella fracture during the convalescent period.

STUDY

DESIGN

Retrospective study.

SAMPLE POPULATION: Fracture group: 20 stifles; reference group: 65 stifles.

METHODS

Medical records were reviewed for stifles with patellar fractures after a TPLO procedure (fracture group) and stifles with >180 days radiographic examination with no complications following TPLO (reference group). Stifle radiographs were masked to group and final TPA (fTPA) was measured, at the time of fracture diagnosis (fracture group) and at last follow-up (reference group), using PACS software. TPAs in the fracture and reference groups were compared using the Wilcoxon rank-sum test. Statistical significance was set at .05.

RESULTS

Patellar fractures were diagnosed at a median of 69 days (range 31-189) after surgery. The median duration of follow-up time for the reference group was 471 days (range 180-1868). Median fTPA for the fracture group was 1.4° (range [-10.3]-7.1). Median fTPA for the reference group was 4.1° (range [-3.9]-14.1). The odds of patellar fractures increased by 21.7% (95% CI: 8.6%-35.6%) for every 1° decrease in fTPA.

CONCLUSION

The risk of patella fractures increased as TPAs after TPLOs decreased.

CLINICAL SIGNIFICANCE: Care should be taken to avoid excessive rotation during TPLO to decrease the likelihood of postoperative patellar fractures.