Predictive Factors for Recurrence in Infantile Blount Disease Treated With Tibial Osteotomy.

BACKGROUND

This study aimed to determine the recurrence rate in infantile Blount disease (IBD) in a cohort of patients treated with a tibial osteotomy; and also to identify which factors were associated with recurrence.

METHODS

We reviewed the records of 20 patients, under the age of 7 years, with IBD (35 involved extremities) treated by proximal tibial realignment osteotomy to physiological valgus at a single institution over 4 years. We then analyzed the data to determine the rate of recurrence and identify the risk factors for recurrence.

RESULTS

The mean age of the included patients was 4.2 years (range, 2 to 6 y). We observed a recurrence rate of 40% (n=14) at a mean follow-up of 42 months (range, 21 to 72 mo). Knee instability [odds ratios OR, 6.6; 95% confidence interval (CI), 2.0-22.2], Langenskiöld stage (OR, 6.3; 95% CI, 2.0-19.4), and severity of the deformity, as measured by medial physeal slope (MPS) (OR, 1.2; 95% CI, 1.1-1.4), were associated with recurrence. On multiple logistic regression analysis, MPS remained the most relevant predictor of recurrence. Receiver operating curve analysis showed that an MPS ≥60 degrees predicted recurrence with a sensitivity of 79% and specificity of 95% (area under the curve=0.925). Postoperatively, increased varus alignment on weight-bearing as measured by the tibio-femoral angle was indicative of knee instability and associated with increased odds of recurrence (OR, 1.5; 95% CI, 1.1-1.9; P=0.004).

CONCLUSIONS

We observed a recurrence rate of 40% in children with IBD under 7 years treated with acute correction to a tibio-femoral angle of 5 to 10 degrees valgus through a dome proximal tibial osteotomy. Knee instability, Langenskiöld stage, and MPS were associated with recurrence. Cases with an MPS ≥60 degrees seem to be particularly at risk for recurrence. Further research is needed to validate these findings.

LEVEL OF EVIDENCE: Level IV.