Rebound of Frontal Plane Malalignment After Tension Band Plating.

ABSTRACT

BACKGROUND: Despite the popularity of tension band plating (TBP) current literature lacks clinical data concerning recurrence ("rebound") of frontal plane malalignment. This study investigated the rebound phenomenon after TBP in idiopathic genu varum/valgum deformities. We analyzed factors that may contribute to the development of rebound after removal of TBP. METHODS: Patients who had correction of idiopathic valgus or varus deformities by TBP at the distal femoral and/or proximal tibial growth plate were selected from a prospective consecutive database. Only patients who had plates removed for at least 1 year and had a long standing radiograph of the lower limbs before plate removal were included. Patients who had presumably not yet reached skeletal maturity (age under 14 y for girls and under 16 y for boys) were excluded. The change of the mechanical axis from plate removal to follow-up after skeletal maturity was evaluated and a statistical analysis was performed. RESULTS: Twenty-nine patients (64 extremities) were eligible. The mean follow-up was 39.1 months (range, 12.3 to 67.3 mo). The mean mechanical axis deviation (MAD) was +0.8 mm (range, -26 to +22 mm) after plate removal and -2.4 mm (range, -29 to +27 mm) at follow-up, accounting for a significant change of MAD (P=0.046). We observed a mean, relative recurrence of frontal plate malalignment into valgus direction of -3.2 mm (range, -48 to +23 mm). Twenty extremities (31%) showed <3 mm of MAD change; 27 extremities (42%) showed >3 mm of MAD change into valgus, and 17 extremities (27%) >3 mm of MAD change into varus direction. Patients with <3 mm MAD change had only 0.8 years, and those >3 mm a mean of 2.0 years of remaining growth until skeletal maturity. Each additional m/kg of body mass index increased the risk of valgus recurrence by 12.1%. The 3 genua vara patients revealed to have an even higher rate of malalignment recurrence (4 of 6 limbs) at final follow-up. CONCLUSIONS: Given our strict criteria, there is a high rate of radiologic recurrence of frontal plane malalignment after TBP. Children who are more than 1 year before skeletal maturity at TBP removal, and those with increased body mass index are at higher risk for rebound growth. LEVEL OF EVIDENCE Level IV-consecutive therapeutic case series.