Pre-operative monitoring of halo-traction for Osteogenesis Imperfecta patients with scoliosis using radiation-free 3D ultrasound Scolioscan

Abstract

Patients with severe scoliosis are exposed to radiation during frequent radiographs taking especially during halo-traction. In order to minimize radiation, a method to visualize the spine without radiation is needed. We presented two cases of Osteogenesis Imperfecta (OI) patients who underwent halo-traction to reduce severe scoliosis as a pre-operative procedure. Radiation exposure was minimized using radiation-free Scolioscan to monitor the change in curvature regularly. The protocol and difficulties are discussed in this study. Methods Case report of two OI patients (one female and one male). Both patients received continuous traction for 12 hours a day. Radiographs and Scolioscans were performed (under traction) for comparison. Results The female patient (subject 1) received 8 weeks of traction. Scolioscans were done at no traction, 5kg and 7kg (24.1% body weight) traction. Cobb angle reduced from 97o to 88o with 5kg traction. At 7kg, thoracic curve Cobb angle measured 87o. Scolioscan angle of thoracic curve was 62.9o before traction and improved to 51.4o after 5kg traction. At 7kg, this angle further reduced to 48.9o. For the lumbar curve, Cobb angle measured 50o before traction. At 5kg and 7kg traction, Cobb angles were both 48o. Scolioscan angle remained unchanged with or without traction. The male patient (subject 2) received 12 weeks of traction. Scolioscan assessments were done at no traction, 8.5kg, 11kg, 13.5kg and 15kg. Maximum traction force reached 45.5% body weight. Primary curve (thoracic) Cobb angle measured before traction was 87o. At 8.5kg traction, Cobb angle reduced to 83o. However there was no change in the angle when traction increased to 11kg. At 13.5kg traction, Cobb angle reduced to 72o. It further decreased to 65o when traction increased to 15kg. Scolioscan angle of the thoracic curve measured 79.4o without traction. At 8.5kg, the angle reduced to 65.4o. When traction increased to 11kg, the angle was 66.3o. Further reduction of Scolioscan angle was noted with higher poundage of traction. The angle was 58.4o at 13.5kg traction and 51.3o at 15kg. Net reduction of Scolioscan angle was 28.1o. Conclusions Halo-traction reduces scoliosis in OI. The Scolioscan measurement is applicable to monitor Cobb angle changes. However, large sample size should be used to investigate the reliability and validity of Scolioscan for patients with large Cobb during halo traction.