Experimental external fixation combined with percutaneous discectomy in the management of scoliosis

Study Design. An assessment of the value of external fixation with or without percutaneous discectomy for the management of scoliosis in young rabbits with induced progressive thoracic scoliosis. Objectives. To investigate in an experimental setting the effect of external fixation with or without percutaneous discectomy for the management of scoliosis, as a preliminary study to precede clinical consideration. Summary of Background Data. External fixation of the spine using percutaneous transpedicular screws has been used clinically for cases of traumatic spinal injury, infectious spine, or chronic low back pain caused by a disc lesion. Percutaneous discectomy for the management of scoliosis has been reported. Methods. Thirty-two young rabbits underwent partial resection of the right lower ribs. Nine rabbits were not treated after production of scoliosis and were followed as :controls. At 4-6 weeks after production of scoliosis, in 23 animals, Kirschner wires were inserted percutaneously into the T9-T10 and L1-L2 disc space, a nd both ends were attached to an external fixator after correction of the scoliosis. In 8 of those 23 animals, percutaneous discectomy was also performed at the apex of the caudal compensatory curvature. Results. In these 23 animals, the initial correction by fixation of the caudal vertebrae was accompanied by a derotation in the apex. Five animals treated with external fixation only and four treated with combined percutaneous discectomy survived with external fixation until the age of 17 weeks and were followed to the natural cessation of the curve progression, at which the fixation was removed and a final assessment was made. The mean progression of curvature was 15.8 degrees in the group of five animals with external fixation only, and 33.8 degrees in the controls. In the group of four animals treated with supplementary percutaneous discectomy, however, the treated disc space became rigid, and the mean progression of curvature after removal of the fixation was only 5.3 degrees. Conclusions. The results of the current study suggest the potential for external fixation to allow for derotation and, when combined with percutaneous discectomy, to offer a feasible method of managing scoliosis in the human adolescent, This study was a preliminary experimental study; further experimental studies are planned to develop this novel technique.