Correction of coronal plane deformities around the knee using a tension band plate in children younger than 10 years

Abstract

Background: Guided growth through temporary hemiepiphysiodesis has gained acceptance as the preferred primary treatment in treating pediatric lower limb deformities as it is minimally invasive with a lesser morbidity than the traditional osteotomy. The tension band plate is the most recent development in implants used for temporary hemiepiphysiodesis. Our aim was to determine its safety and efficacy in correcting coronal plane deformities around the knee in children younger than 10 years.

Materials and methods: A total of 24 children under the age of 10 were operated for coronal plane deformities around the knee with a single extra periosteal tension band plate and two nonlocking screws. All the children had a pathological deformity for which a detailed preoperative work-up was carried out to ascertain the cause of the deformity and rule out physiological ones. The average age at hemiepiphysiodesis was 5 years 3 months (range: 2 years to 9 years 1 month).

Results: The plates were inserted for an average of 15.625 months (range: 7 months to 29 months). All the patients showed improvement in the mechanical axis. Two patients showed partial correction. Two cases of screw loosening were observed. In the genu valgum group, the tibiofemoral angle improved from a preoperative mean of 19.89° valgus (range: 10° valgus to 40° valgus) to 5.72° valgus (range: 2° varus to 10° valgus). In patients with genu varum the tibiofemoral angle improved from a mean of 28.27° varus (range: 13° varus to 41° varus) to 1.59° valgus (range: 0-8° valgus).

Conclusion: Temporary hemiepiphysiodesis through the application of the tension band plate is an effective method to correct coronal plane deformities around the knee with minimal complications. Its ease and accuracy of insertion has extended the indication of temporary hemiepiphysiodesis to patients younger than 10 years and across a wide variety of diagnosis including pathological physis, which were traditionally out of the purview of guided growth.

Keywords: Angular deformity; Paediatrics; epiphysis; genu valgum; genu varum; hemiepiphysiodesis; knee; limb deformities.

Figure 1

Distribution of age at surgery

Figure 2

Duration of implantation of the plate to achieve a neutral mechanical axis, mean being 15.6 months

Figure 3

(a) Preoperative radiograph of a 4 year 3 months old case of nutritional rickets and bilateral genu valgum. (b) Postoperative radiograph with plates inserted in bilateral femur and tibia. (c) Neutral mechanical axis 7 months after insertion. (d) Clinical appearance before surgery. (e) Clinical appearance at 7 months after surgery

Figure 4

(a) A 4 year 10 months old boy with a posttraumatic tibia valga with mechanical axis in lateral zone 3. (b) Radiograph at 4 months after plate insertion shows the mechanical axis in lateral zone 2. (c) Radiograph at 12 months after plate insertion showing a neutral mechanical axis. (d) Clinical appearance before surgery. (e) Clinical appearance 12 months after surgery following which the plate was removed

Figure 5

Guide to guided growth - flow chart depicting the guidelines for temporary hemiepiphysiodesis