Can deformity of the knee and longitudinal growth of the leg be predicted in patients with hereditary multiple exostoses? A cross-sectional study

BackgroundThere is a high rate of knee deformity in patients with hereditary multiple exostoses (HME), and a quarter of patients have a limb length discrepancy.MethodsA prospective database of 172 patients with HME was compiled. Patient demographics, knee deformity and range of movement, leg length and height, and number of exostoses around the knee were recorded.ResultsNine out of 10 patients with HME were affected by exostoses around the knee, of which the distal femur was the most common site to be involved. Approximately 20% of patients had a valgus deformity and 16% had a fixed flexion deformity of the knee, with 25% having a diminished range of movement. Height was directly proportional to leg length and a quarter of patients were below the 10th centile for height. The presence of a distal femoral exostosis was an independent predictor of knee deformity (p = 0.002), diminished range of movement (ROM) (p < 0.001), and smaller stature (p < 0.001) on multivariate analysis. In addition increasing age, prior surgery, genotype, and gender were also intendant predictors of ROM and height.ConclusionFuture studies analysing if surgical excision improves knee function and limits deformity would need to assess whether this is dependent upon anatomical site, as our results suggest that distal femoral exostoses may have the greatest affect upon these outcomes.Level of EvidenceLevel II.