The Effect of Polylactide Resorbable Film on the Epidural Fibrosis After Lumbar Laminotomy / 대한정형외과연구학회지

PURPOSE: The purpose of this study is to evaluate the effect of polylactide resorbable film in preventing epidural fibrosis after lumbar laminotomy. MATERIALS AND METHODS: Thirty-six New Zealand male rabbits about fifteen month old, weighing 3.5 kg in average, were used. Uniform laminotomy windows measuring 7x7 mm were made on the left side of the spine at three lumber locations (L2, L3 and L4). The laminotomy window at second lumbar spine was left untreated and used as control group (Group 1). The lanimotomy window of 3rd lumbar spine was covered with free fat tissue (Group 2), and polylactide ( Surgi-Wrap(R)) resorbable film was inserted on the laminotomy window of 4th lumbar spine (Group 3). Twelve rabbits were euthanized at 4, 8 and 12 weeks each after operation for biochemical analysis of hydroxyproline content and histologic examination. RESULTS: 1. There was considerable reduction in the total collagen, ranging from 40~48% in the Group 2 or the Group 3 compared to the Group 1. There was no statistical difference between the Group 2 and the Group 3. 2. The extent of fibrosis and fibroblast density was significantly lower in the Group 2 or the Group 3 than in the Group 1. However, the extent of fibrosis and fibroblast density did not differ statistically between the Group 2 and the Group 3. 3. No significant statistical differences of the collagen content and the histologic findings in each group was demonstrated during experimental period. CONCLUSION: These results suggest that polylactide (Surgi-Wrap(R)) resorbable film may be a useful method for reduction of epidural fibrosis after lumbar laminotomy.

Experimental Study of Heterograft Method on the Healing Process of Long Bone Defect in Rabbits / 대한정형외과학회잡지

Bone grafts are used in the repair of segmental bone loss caused by severe trauma, bone tumors and infection, and to enhance bone healing in ununited fractures. Autograft is the most frequently used and the most effective method, but because of inadquate supply and additional operative morbidity, allograft or heterograft could be used. Heterograft has been shown to be poorly tolerated by the host and ineffective in providing an osteogenic system. The objective of this study is to observe healing process of a segmental defect of long bone following to heterograft, and to compare the difference of histologic process between autograft and hetero graft. Twenty-four white rabbits weighing 1,000 to 2,000 grams were used for the experiment. A segment measuring three times the diameter of the ulna shaft (1.5 to 2cm) of rabbit was resected with its periosteum. Twenty-four white rabbit were divided into three groups (control, autograft, heterograft group) according to graft methods, each group comprising of eight rabbits. The animals were sacrificed at 2, 4, 8 and 12 weeks after the experimental procedures and were periodically evaluated by radiographs and histology. The obtained results were as follows: 1. The results of the radiological evaluation showed that no ungrafted ulnar defects (control group) healed. In the heterograft group, partial union was observed from 8 weeks and complete union was obtained on 12 weeks. In the autograft group, partial union was observed on 2 weeks and complete union was obtained on 4 weeks. 2. The results from histological examination showed that the ungrafted ulnae did not heal across the defect but some immature trabeculae were founded on the edges of the defect. In the heterograft group, immature trabeculae were appeared from 4 weeks and defects were substituted with mature trabeculae on 12 weeks. In autograft group, defects were substituted with immature trabeculae on 2 weeks and with mature trabeculae on 4 weeks. As seen in the results of the experiment, union could be obtained with the heterograft, but needed more long time than autograft. Though the autograft is the most effective graft method in bone defect or non-union, above results suggest the heterograft as the alternative method in the treatment of large bone defect, in a multioperated patient, or in the children or the elderly, combined with autograft or alone.

Biomechanical Study about Difference between Stainless Steel and Titanium Dynamic Hip Screws in Peritrochanteric Fractures of the Femur / 대한정형외과학회잡지

Peritrochanteric fractures are common in the elderly, and the mortaliy and morbidity rates after conservative treatment of the fractures are usually high. In these fractures the internal fixation now allows the patient more rapid functional gain. It has been known that for stabilization of fracture the sliding hip screw is superior to other fixation devices. To investigate the biomechanical difference between two different materials of dynamic hip screw, eight intertrochateric and eight subtrochanteric femur fractures were artificially induced in human cadavers. Two femurs were used as the control. In eight cadaver intertrochanteric fractures (Group I), four of them were treated with stainless steel compression hip screw and four were treated with titanium compression hip screw. Eight cadaver subtrochanteric fractures (Group II) were divided by two groups as equal number. One group was treated with stainless steel compression hip screw and the other was treated with titanium compression hip screw with plate. Each femur was secured in a fixation device of the Instron and loaded in a vertical compression. Collapse or fixation failure during vertical compression were observed and recorded continuously in slow speed with deformation rate of 3mm/min. Biomechanical analysis of maximal loading force in the control and experimental two groups were performed. The results were as follows; 1. The mean maximal loading force was 625 kp in control group. 2. The mean maximal loading force in each 4 intertrochanteric fractures fixed with stainless steel DHS (dynamic hip screw) and plate was 92.59 kp, and with titanium DHS and plate was 71.57 kp. There was no statistical significance between stainless steel DHS and plate fixation and titanium DHS and plate fixation. (p>0.05) 3. The mean maximal loading force in each 4 subtrochanteric fractures fixed with stainless DHS and plate was 140.12 kp, and with titanium DHS with plate was 169.4 kp. There was no statistical significance between stainless steel DHS and plate fixation and titanium DHS and plate fixation. (p>0.05) 4. The breakage of metal implant was not occurred at the maximal loading force 600 kp in both group. There was no difference of fixability and stability according to the metal quality, as the results of the experiment of compression loading force to the stainless steel DHS and titanium DHS fixation on intertrochanteric and subtrochanteric fractures in cadaverous femurs.