Hemiepiphyseodesis for late-onset tibia vara.

BACKGROUND: The amount of correction obtained with tibial and/or femoral hemiepiphyseodesis in late-onset tibia vara is quite variable. The purpose of this study is to identify preoperative factors which might help to predict the amount of correction that is obtainable.

METHODS: Fifty-three patients (67 knees) have been treated with hemiepiphyseodesis and followed until skeletal maturity or a secondary realignment procedure before maturity. The amount of correction obtained was correlated with multiple preoperative factors including age, body weight, and degree of deformity.

RESULTS: In 65 limbs treated with tibial hemiepiphyseodesis, the average correction in the tibia was 9 degrees, ranging widely from 33 degrees of correction to 6 degrees worsening of the deformity. In 22 limbs treated with femoral hemiepiphyseodesis, the average correction in the femur was 8 degrees (range, 0-19 degrees). Ultimately, 19 of the 67 limbs have been treated with an osteotomy and 10 more were left with greater than 10 degrees of varus deformity at maturity. In addition, 14 of the 67 limbs overcorrected into excessive valgus and/or required medial hemiepiphyseodesis procedures to prevent overcorrection. Using multiple regression analysis it was found that younger age and lesser deformity were weakly predictive of greater correction with tibial hemiepiphyseodesis. No factors were statistically significant predictors of femoral correction.

CONCLUSIONS: Variable amounts of correction are obtained with hemiepiphyseodesis in patients with late-onset tibia vara. Even very large amounts of correction may be obtainable in some cases, but unfortunately preoperative factors such as age, weight, and degree of deformity cannot be relied upon in clinical practice to predict outcome. Surgical decision making must weigh the safety and simplicity of this procedure against the much more extensive but much more predicable realignment obtained with osteotomy procedures.

LEVEL OF EVIDENCE: Level IV; retrospective and prospective longitudinal evaluation of a case series.