Osteosarcoma as a second malignant neoplasm in children.

Nine patients who had an osteosarcoma that had developed as a second malignant neoplasm in a previously irradiated site were managed at a major center for the treatment of tumors in children. The doses of radiation had averaged 4144 centigray (range, 2300 to 8000 centigray) and chemotherapy had been administered, when appropriate, for the primary malignant lesion (Ewing sarcoma, malignant fibrous histiocytoma, Hodgkin lymphoma, neuroblastoma, neurofibrosarcoma, rhabdomyosarcoma, and Wilms tumor). The interval between the initial treatment and the diagnosis of the secondary sarcoma averaged ten years and one month (range, five years and ten months to twenty-one years and nine months). Three patients were alive, two of them with active disease, at the time of writing. The other six had died within three years (average, fifteen months) after the second diagnosis. The prevalence of secondary osteosarcoma is increasing as the survival of children who have a malignant lesion increases. Plans for tumor therapy should take into account the risk of this complication, which is usually fatal.

Anterior cruciate ligament reconstruction using a composite collagenous prosthesis. A biomechanical and histologic study in rabbits.

We evaluated a prototype composite collagenous anterior cruciate ligament replacement device designed to possess the advantages of biological grafts and synthetic materials. Collagenous anterior cruciate ligament prostheses were made by embedding 225 reconstituted type I collagen fibers in a type I collagen matrix, and placing polymethylmethacrylate bone fixation plugs on the ends. The collagenous prosthesis was used to replace the anterior cruciate ligament of 31 mature rabbits. At 4 and 20 weeks postimplantation, histologic and mechanical studies were performed on the developing neoligament tissue, and compared to values for the contralateral sham-operated control. At 4 weeks, neoligament tissue infiltrated the collagen fibers of the prostheses. The tibial bone tunnel attachment site contained new bone approaching the fibrous neoligament. The glutaraldehyde-treated prosthetic fibers appeared intact, while the carbodiimide-treated prosthetic fibers began to resorb. The ultimate load and ultimate tensile strength of femur-neoligament-tibia complexes had decreased. At 20 weeks, glutaraldehyde-treated fibers appeared partially intact; in contrast, the carbodiimide-treated prostheses appeared to be completely degraded, and were replaced by organized, crimped neoligament tissue. The ultimate tensile strength and ultimate load increased substantially due to deposition and remodeling of neoligament tissue. The neoligament ultimate load was 2 to 4 times the initial load value of the prosthesis. Implantation of a resorbable, composite collagenous anterior cruciate ligament prosthesis encourages the development of functional neoligament tissue. Studies are underway to optimize the mechanical and biological properties of the prostheses.

Electromyographic analysis of the hip and knee during the golf swing.

As golf increases in popularity, more golfers seek the proper mechanics necessary for the perfect golf swing. Surprisingly little scientific work has been published on the contribution of the hip and knee muscles during the golf swing even though most professionals have recognized their vital contribution. Recent studies have described the electromyographic (EMG) muscle activity of the shoulder, back, and trunk during the golf swing. The purpose of this study was to describe the electrical muscle activity in seven hip and knee muscles of both the left (lead) and right (trail) leg in competitive golfers while performing the golf swing. Sixteen golfers were studied with indwelling electrodes and high-speed cinematography. The EMG was synchronized with the film to discern five phases of the golf swing. Means, SDs, and t-tests were done. The results revealed that the trail hip extensors and abductors in conjunction with the lead adductor magus initiated pelvic rotation during forward swing. The lead hamstrings maintained a flexed knee and provided a stable base on which pelvic rotation took place. The peak EMG muscle activity recorded in the hips and knees occurred in an earlier phase than that measured previously in the trunk and shoulder. This confirmed the sequential firing pattern of the hip and knee muscles that takes place during the competitive golf swing. Information gained from this study can be used by players and coaches to optimize performance and to minimize injury.