The 8-plate versus physeal stapling for temporary hemiepiphyseodesis correcting genu valgum and genu varum: a retrospective analysis of thirty five patients

Abstract

Purpose: In skeletally immature patients, treatment of malalignment about the knee is possible by performing temporary hemi-epiphyseodesis. Following the well-established procedure of physeal stapling, the 8-plate was introduced as a new device. The purpose of this study was to compare physeal stapling with 8-plate hemi-epiphyseodesis. We focused on evaluating deformity correction, complication rate and duration of the procedures.

Methods: We retrospectively analysed 35 patients (61 extremities, age 2.9-16.0 years) who were treated by temporary hemi-epiphyseodesis about the knee for correction of genu varum or genu valgum by using Blount staples (32 extremities) or the 8-plate (29 extremities). Plain radiographs were analysed at the time of operation and at hardware removal that included measurement of mechanical axis deviation, mechanical lateral distal femoral angle and mechanical medial proximal tibial angle. Time until hardware removal, operation time and complications were recorded.

Results: A statistically significant improvement of all radiographic measurements could be achieved with comparable results in both groups. Complications were similar in both groups with no relevant differences in amount and severity. In the 8-plate group, however, the surgical time was significantly shorter by an average of ten minutes for implantation and 12 minutes for explantation.

Conclusions: Both Blount stapling and the 8-plate technique are methods for correction of genu varum and valgum deformity in skeletally immature patients; however, a shorter operating time for implantation and explantation was noted for the 8-plate technique.

Figures

Fig. 1

Radiographic illustration showing the measurements for (A) mechanical axis deviation (MAD) and (B) mechanical lateral distal femoral angle (mLDFA) and mechanical medial proximal tibial angle (mMPTA). MAD is defined as the distance from a line connecting the midpoints of the hip and ankle joint to the midpoint of the knee joint. The mLDFA is the lateral angle between the connection of the midpoints of the hip and knee with the joint line (normal value 88° (85–90°)). The mMPTA is the medial angle between a line connecting the midpoint of the knee and ankle and the knee joint line (normal value 87° (85–90°))

Fig. 2

Bilateral 8-plates implanted in a 13 years and 6 months old girl with idiopathic genua valga (A). After nine months on the left leg and 18 months on the right leg (B) full correction was achieved and the implants were removed at the time of adequate correction

Fig. 3

Physeal staples implanted in a 14 years and 4 months old boy with idiopathic genu valgum (A). Eighteen months later, extrusion of the femoral staples occurred (B). As the physes were closed and almost full correction achieved, the implants were removed without further treatment