The Causes of Metallic Failure and Loosening of MOSS Transpedicular Spinal Instrumentation / 대한정형외과학회잡지

With the increasing use of pedicular system to fix the spine, many complications are being reported. Recently many systems are available to fix the spine. However, each system has own advantages and disadvantages. The causes of metallic failure of Modular Segmental Spinal (MOSS) instrumentation on 42 consecutive patients undergone in Kang-Nam St. Mary's hospital since 1989 were reviewed. The specific aim of this investigation was to assess causes of metallic failure and loosening of this system on various spinal disorders. Of these, 8 cases had metallic failure and loosening. Breakage of screw and rod developed in 6 cases and dislodgement of rod from screw in 2 cases. In case of degenerative spondylolisthesis (unstable phase) with stenosis, however, the complications were closely correlated to expansile decompressive laminectomy to widen the narrowed spinal canal and the instrumental distraction to gain normal intervertebral disc space at the operation. Bony union and back pain were not correlated to metallic failure and loosening. Therefore, the main causes of metallic failure and loosening were (1) preoperative instability undergone expansile decompressive laminectomy including total bilateral facetectomy that aggravated preoperative instability, and (2) forceful instrumental dis traction. In cases needed these requirements, combined anterior interbody fusion or posterior interbody fusion should be added, heavier rods and screws larger than 3.5mm, 4.0mm in diameter, respectively, should be used. In addition to postoperatively sufficient bed rest and immobilization using rigid braces should be recommended to reduce these complications.

Metallic Failures after Compression Plate Fixation Clinical Analysis of 12 Cases / 대한정형외과학회잡지

The twelve cases of metallic failure after compression plate fixation which were observed and treated at Department of Orthopedic Surgery, Busan National University Hospital were clinically analysed. The results were summerized as follows; 1. Age and sex of the patients was male in his active age in life. 2. The causes of fracture were traffic accidents and industrial accidents. The sites of fracture were femur in 11 cases and tibia 1 case. 3. The types of fracture were comminuted in 11 cases and short oblique in 1 case. 4. The 6 patients were not cooperative and began walking at their will after postoperative 4 weeks despite doctors order of nonweight bearing. Average duration of immobilization was 6 weeks. 5. Metallic failure occurred as screw failure in 1 case, plate failures through empty hole in 4 cases and plate failures through hole filled with screw nearest to the sites of fracture in 7 cases. 6. Interval between operation and metallic failure was 6.25 months average. The 75% of the metallic failure occurred between 4 to 7 months. 7. Treatments of metallic failures were cast immobilization with bone grafting in 1 case at tibia, intramedullary nailing with bone grafting in 1 case at femur and compression plate fixation with bone grafting in 10 cases at femur. 8. Causes of failure after internal fixation 1). Insufficient bone support Inadequate inter-fragmentary compression 9 cases Absence of cancellous bone graft 8 cases Empty plate hole 4 cases Remaining defects 3 cases 2). Inadequate postoperative treatment 6 cases.