The Reduction of the Laminectomy Membrane in Dogs by the Synovial Fluid-Soaked Absorbable Gelatin Sponge

The reduction of the laminectomy membrane (LM) with synovial fluid soaked absorbable gelatin sponge (SSAGS) after laminectomy was investigated. Modified laminectomy of the first and second lumbar vertebra and concomitant full length durotomy were carried out in 16 mongrel dogs of different ages and sex. Two pieces of absorbable gelatin sponge (AGS-Gelfoam, Upjohn), soaked with 2 ml of synovial fluid taken from the shoulder joint, were implanted into the laminectomy defect in 8 dogs. Two pieces of AGS were implanted into the laminectomy defect in the control group of 8 dogs. Animals were allocated to 4 groups, each consisting of 4 dogs according to follow up examinations done in weeks 2, 5, 10 and 20. Myelography was performed at the end of the observation periods and the dogs were sacrificed. Gross and histologic evaluations of the operated region were done by an observer blinded to the groups. Modified laminectomy and full length duratomy were tolerated well by the dogs except for one dog, during both the early and the late postoperative observation periods. There was no noticeable difference between the two groups according to the clinical findings. Myelography indicated that the dural sac was reproduced in the SSAGS, but loss of the dorsal contrast column was noticeable in the control group at week 20. Gross and histological findings suggested that qualitative decreases in the inflammatory reaction at an early stage and LM in later periods were present in the SSAGS group. In conclusion SSAGS could be an alternative way of reducing the LM.