AUGMENTATION OF THE VDS WITH DOUBLEROD-IN STRUMENTATION - A CRITICAL ANALYSIS OF THE 2-4 YEAR RESULTS

Objectives: In order to evaluate the benefits of the doublerod-VDS in the operative treatment of scoliosis the midterm results were critical ly analysed with specific respect to primary stability. Methods: 24 pa tients with either idiopathic or neuromuscular curves were treated wit h the Doublerod-VDS. In some cases a singlerod instrumentation had to be carried out in the cranial fusion area due to too small vertebrae ( Hybrid-VDS). Patients with thoracic curves were ambulated without any external support, the thoracolumbar curves were ambulated in a light, semirigid vest for a few months. All data including early and late com plications were collected prospectively and a thorough radiometric ana lysis was carried out. Results: Fusion was mostly carried out from end -to end-vertebra. The correction of the idiopathic curves averaged 60, 2% (preoperative Cobb angle 67,3 degrees) with a loss of correction of 5,2 degrees. In the neuromuscular curves the average correction was 6 1,1% (preoperative Cobb angle 99,8 degrees) and the average loss of co rrection 4,2 degrees. There was no kyphogenic effect noted. In 6 cases a rod fracture was observed, in 4 cases the fracture occurred within the singlerod instrumentation in hybrid-VDS. Two of these patients dev eloped a pseudarthrosis with loss of correction but without any sympto ms. Conclusions: The hybrid-VDS does not offer any advantages compared to the Zielke-VDS. However, the doublerod-VDS in thoracic curves is p rimary stable and does not require any external support postoperativel y. In thoracolumbar curves a light vest is suggested for the first pos toperative months during day time.