Aims: To evaluate the outcome of surgery in patients with lumbar spine degenerative disease or isthmic spon-dylolisthesis. Methods: Lumbar spine fusion with or without decompression was performed in 132 consecutive patients. Altogether 115 patients attended to follow-up an average 3.4 years after operation. The overall result was assessed by the patient and by an independent observer. Moreover, the disability was measured using Oswestry questionnaire and fusion rate was assessed from flexion and extension radiographs. Results: The complications of surgery were: misplacement of screws in 2 patients, paresis of peroneal nerve in 1 patient, superficial wound infection in 4 patients, breakage of fixation device in 1 patient and spinal fluid fistulas in 2 patients. According to patient’s own opinion the result of surgery was excellent, good or fair in 86 percent of the patients and even 89.6% of them benefited from the surgery. The average postoperative Oswestry score was 28. According to radiographs the fusion rate was 93 percent. At the time of operation 40 patients were retaired and 66 (93%) out of the 75 patients who were still at working age returned to work. Conclusion: Lumbar spine fusion is an effective and safe treatment of degenerative lumbar spine disease and isthmic spondylolisthesis. However, the careful selection of patients is an important factor for success.

Forty-four rabbits were operated on when five weeks old; in one group a 2 mm drill-hole was made in the intercondylar portion of the right femur across the central portion of the growth plate up to the diaphysis, while in the other group a similar drill-hole of 3.2 mm was made. At 3, 6, 12 and 24 weeks after operation, specimens from the growth plates of both femora were analysed using radiographic, microradiographic, histological and histomorphometric techniques. It was found that destruction of 7% of the cross-sectional area of the growth plate caused permanent growth disturbance and shortening of the femur.

Fifty-six patients with displaced malleolar fractures had open reduction and fixation of the fracture fragments using, by random selection, either biodegradable implants or metal AO plates and screws. The cylindrical biodegradable implants were made of polylactide-glycolide copolymer (polyglactin 910). The complications, radiographic results and functional recovery were studied prospectively. After follow-up of at least one year, no significant differences emerged in the complication rate or in the results of treatment between the two methods of fixation. Because of the advantage of avoiding the need to remove metal fixation after union, we now use biodegradable internal fixation routinely to treat displaced malleolar fractures.