Distal Femoral Osteotomy Survivorship: A Population-based Study

OBJECTIVES: Malalignment of the lower extremity can lead to functional impairment and degenerative changes at an early age. Distal femoral osteotomies (DFO) are often performed concurrently with arthroscopic procedures to correct malalignment while addressing intra-articular pathology. The aim of this study was to examine survivorship following distal DFO and to identify risk factors for failure. METHODS: Data from the California Office of Statewide Health Planning and Development, a mandatory statewide discharge database, was utilized to identify all patients who underwent a DFO from 2000 to 2014. Patients with lower extremity trauma, infectious arthritis, rheumatologic disease, congenital deformities, malignancy, or concurrent arthroplasty were excluded. Patient demographic information was assessed for every patient. Failure was defined as conversion to total or unicompartmental knee arthroplasty. Statistically significant differences between patients who required arthroplasty and those who did not were identified on univariate analysis. A multivariate analysis was performed to account for identified differences and a survivorship curve was constructed to estimate 5 and 10-year survivorship. RESULTS: After exclusions were applied, 420 patients were identified and followed for an average of 5.0 years. Of those, 53 were converted to arthroplasty at an average of 5.9 years. 5-year survivorship was 98.3% and 10-year survivorship was 92.3%. Patients converted to arthroplasty tended to be older (43.6 years versus 36.9 years, p<0.001) and had a higher number of comorbidities (47.2% with at least one comorbidity versus 27.5%, p=0.021). A diagnosis of osteoarthritis at the time of surgery was more prevalent amongst patients who went on to arthroplasty (81.1% versus 53.7%, p<0.001). On multivariate analysis, patients were 4% more likely to undergo arthroplasty for each additional year of age (OR 1.04, p=0.013). Patients with osteoarthritis were also at increased risk of conversion to arthroplasty (OR 2.57, p=0.025). CONCLUSION: Older age and a diagnosis of osteoarthritis at the time of surgery were associated with conversion to arthroplasty. These factors should be taken into account when performing this procedure.