Abstract

OUTCOME OF GROWTH MODULATION USING THE TENSION BAND PRINCIPLE OF 8 PLATE FOR PAEDIATRIC GENU VALGUM DEFORMITY

Author(s): Ravi Teja Boddapalli, Mahendra Solanki, Anand Ajmera

BACKGROUND Osteotomies have traditionally been the mainstay of treating deformities not only in adults but also in children. Osteotomies involve extensive soft tissue dissection, complications of wound closure, infection, delayed union, malunion, and prolonged immobilization, which increase the morbidity of the patients. Depending upon the aetiology, recurrent deformity may lead to need for repeat osteotomy. While osteotomy is necessary for rotational correction and limb lengthening, angular correction may be achieved by other means. Several techniques of epiphyseal growth modulation have evolved, enabling gradual correction of angular deformities and/or length equalization through guided growth. Dallas Phemister introduced the concept of open epiphysiodesis which had the risk of permanent arrest of the physis. Walter Blount gave the idea of staples, but were susceptible to migration, bending and loosening. Permanent physeal closure might ensue with staples. Transphyseal screws by Metaizeau had a major risk of intra-articular perforation and also violated the physis. The 8-plate method of guided growth provides a tension band that expedites angular correction compared to stapling and transphyseal screws which rely upon the principle of compression. METHODS The study design was prospective and interventional. The parameters measured and documented were: 1. Tibio femoral angle 2. Lateral distal femoral angle 3. Medial proximal tibial angle 4. Mechanical axis zone These parameters were collected at each follow up until the deformity was corrected. Data was analysed statistically. A paired t-test was applied to compare the pre-operative tibio-femoral angles, and the tibio-femoral angles at various durations of follow-up. RESULTS Eighteen patients were included in the study. They were evaluated by the alignment of tibio-femoral axis at each post-operative visit. The mean pre-operative and the mean post-operative tibio-femoral axes alignment was subjected to a paired t-test. The final outcome was taken at an angle of zero degrees between both axes. We observed a t-value of 7.23, which corresponds to a p-value of 0.02 which is significant i.e., less than 0.05. CONCLUSION 8-plate hemi-epiphysiodesis is an effective means for correcting genu valgum deformities in skeletally immature patients. It is minimally invasive, and there is no permanent damage to the bone. It is a modular, diverse and a reversible procedure which accommodates the dynamic and ever-changing physis while promoting angular correction. The outlook for guided growth looks very promising, but as with all the new techniques, the results have to be evaluated carefully and the indications refined.