Early experience with medial femoral tension band plating in idiopathic genu valgum

Abstract

Purpose: For correction of angular deformity, tension band plating has been proposed as a safe and minimally invasive technique. The purpose of this study was to assess the experiences and report the rate of correction obtained with this procedure in patients with idiopathic genu valgum.

Methods: This study was a retrospective review of 47 valgus deformities of the knee treated with medial hemiepiphysiodesis using a tension band plate. The tibiofemoral angle (TFA) and the anatomic lateral distal femoral angle (aLDFA) were assessed on anteroposterior (AP) radiographs of the lower extremity taken at multiple time intervals. The values were charted to determine the change in orientation of the joint surface over time. Pearson's correlation was used to analyze the correction over time. A subanalysis was performed evaluating the effect of age and the number of plates utilized.

Results: A total of 47 deformities in 25 patients were reviewed. The average time of follow-up from index surgery was 12.7 months, with an average correction of 0.96° every 3 months or 3.8° per year. The aLDFA corrected at a faster rate in knees with two plates per hemiepiphysiodesis than those with one plate, 4.2° and 3.3° per year, respectively (P = 0.035). Girls <11 years of age and boys <13 years of age corrected at a rate of 4.5°, while older children corrected at a rate of 3.4° per year (P = 0.39). There were no complications or instrumentation breakages.

Conclusion: Hemiepiphysiodesis with tension band plating provides an effective and predictable correction of idiopathic genu valgum. Two plates appear to provide a greater rate of correction. There is also a trend toward faster correction in younger patients as well.

Keywords: Genu valgum; Hemiepiphysiodesis; Tension band plate.

Figures

Fig. 1

Schematic representation of the measurement of the anatomic lateral distal femoral angle (aLDFA). The angle is formed by a line parallel to the distal femur articular surface and the anatomic axis of the femur (normal = 79°–83°)

Fig. 2

a An 11-year-old male with bilateral genu valgum (left aLDFA: 79°, right aLDFA: 75°). b The patient underwent bilateral hemiepiphysiodesis with a single tension band plate. He underwent removal at 11 months from the index procedure (left aLDFA: 88°, right aLDFA: 82°)

Fig. 3

a A 12-year-old female with bilateral genu valgum (left aLDFA: 80°, right aLDFA: 80°). b The patient underwent bilateral hemiepiphysiodesis with two tension band plates. She underwent removal at 18 months from the index procedure (left aLDFA: 84°, right aLDFA: 86°)

Fig. 4

Scatterplot of change in the aLDFA over time in all patients

Fig. 5

Scatterplot of change in the aLDFA for patients with one plate versus two plates in the distal femur

Fig. 6

Scatterplot of aLDFA change over time for the two age groups

Fig. 7

Poor visualization of the hip center in some X-rays caused inability to obtain mechanical axis data in these patients