The effect of intra-operative skeletal (skull femoral) traction on apical vertebral rotation

Abstract

The study design is a retrospective review of consecutive case series. Our goal was to identify and quantify the effect of skeletal traction on the apical vertebral rotation (AVR). Intra-operative skeletal traction has been used for the correction of large magnitude idiopathic and neuromuscular scoliosis. The ability of skeletal traction to correct the rotational deformity of the spine has not been characterized. Following REB approval, retrospective analysis of 22 (AIS = 14, neuromuscular = 8) consecutive pediatric patients having surgical posterior instrumented correction and fusion for their scoliosis was performed. Intra-operative skeletal traction with approximately 50% body weight was achieved with smooth distal femoral pins. Counter-traction up to 25% was used through Gardner-Wells tongs. The AVR of the major curve was assessed using the Nash-Moe grading system by a radiologist and a senior spine surgeon not involved in the treatment of these cases. Statistical analysis was performed to determine the significance. The overall mean AVR of the major structural curve was 3.1 +/- 0.8 and reduced to 2.4 +/- 0.6 (p = 0.0001) following traction. The AVR decreased by one or more Nash-Moe grades with traction in 14/22 (64%) patients. The Cobb angle corrected from a mean of 88.2 degrees to 49.1 degrees (44.3%, p = 0.00001) with traction. The decrease in AVR correlated with the higher magnitude Cobb angles (correlation 0.53, p = 0.014). Patients with pre-traction AVR > or = 3 showed the largest change with traction (3.4-2.5, p = 0.000004). There was very good association between the radiologist and the spine surgeon, 0.72(standing films) and 0.63(traction films). The minor structural curve corrected from a mean Cobb of 53.5 degrees to 33.8 degrees (37.8%) with AVR decreasing from a mean of 1.9 to 1.4 (p = 0.014). Significant apical derotation occurs with the use of intra-operative skull-skeletal traction in the correction of high magnitude scoliotic curves. This derotation can facilitate spinal exposure, placement of pedicles screws and final correction in these patients.