Do Different Tibial Osteotomy Techniques Affect Sagittal Alignment in Children with Blount Disease?

Abstract

Objective: To determine the radiographic outcomes following dome or wedge-shaped proximal tibial osteotomy in the management of infantile Blount disease with a particular interest in sagittal alignment of the knee joint.

Method: Medical records of patients with Langenskiöld stage 2 Blount disease (aged ≤5 years) who underwent surgical correction between January 2005 and November 2019 were retrospectively identified. Patients with metabolic bone disease, bone tumors, prior traumatic fractures, congenital anomalies, inadequate plain films, and incomplete medical documents were excluded. Patient characteristics (e.g. age, gender, and body mass index [BMI]) and surgical characteristics (e.g. side, type of surgery, and follow-up times) were recorded. Antero-posterior (AP) and lateral knee radiographs were analyzed. Data were categorized by surgical technique as dome-shaped proximal tibial osteotomy or wedge-shaped proximal tibial osteotomy. The femorotibial angle (FTA) was used to evaluate the correction angle in varus deformities. Sagittal alignment of the lower limbs using the posterior tibial slope (PTS) angle was measured postoperatively at 3, 6, 12, and 24 months, and at the final follow-up visit.

Results: The present study included 72 surgeries of 46 patients who had undergone proximal tibial osteotomy. Twenty-nine (63%) were male. The mean age of patients at the time of surgery was 34.50 months (range, 26-47). The mean weight was 23.11 ± 4.98 kg (mean ± SD); the mean height was 95.33 ± 6.36 cm, and the mean BMI was 25.32 ± 4.36 kg/m² . The mean duration of follow up was 4.77 ± 2.78 years. Sixty-four patients (88.90%) received dome-shaped proximal osteotomy of the tibia, while 8 (11.10%) received wedge-shaped proximal osteotomy of the tibia. The average FTA of the total correction measured was 29.32° ± 7.98°. The demographic data of the two groups were not significantly different for gender, age, BMI, side follow-up times, and the total correction of varus deformities. In the dome-shaped osteotomy group, the mean correction of the FTA was 29.59° ± 7.45°. The mean degree of the PTS angle was 6.50° at 3 months, 6.38° at 6 months, 5.32° at 12 months, 5.17° at 24 months, and 5.53° at the final follow-up visit. In the wedge-shaped proximal tibial osteotomy group, the mean correction of the FTA was 27.25° ± 11.77°. The PTS was 6.00° at 3 months, 7.50° at 6 months, 7.00° at 12 months, 5.40° at 24 months, and 5.57° at the final follow-up visit. No significant difference was observed in the radiological outcome between surgical techniques.

Conclusion: Dome and wedge-shaped proximal tibial osteotomies did not demonstrate significant differences in the PTS angle in children with Blount disease.

Keywords: Blount disease; Dome-shaped proximal tibial osteotomy; Posterior tibial slope; Wedge-shaped proximal tibial osteotomy.