Takashi Hashiguchi

Wear of Alumina Ceramics Prosthesis

Abstract To investigate the process of wear in the total knee prosthesis consisting of alumina ceramics (Al-ceramics) and ultra-high molecular weight polyethylene (UHMWP) in vivo, we observed the fine structures of the articular surface of the prostheses used for four patients with osteosarcoma of the distal femur. We also examined the wear debris in the surrounding soft tissues. The prostheses were extracted at autopsy between 13 and 48 months after surgery. An increase of pores, indicating where Al-ceramics grains fell off, and many streaks on the UHMWP running parallel to the gliding direction of the joint were observed on the articular surface. The streaks had similar widths to the Al-ceramics grains. Al-ceramics debris was detected in the soft tissues around the joint mixed with UHMWP debris. We concluded that the wear of UHMWP in Al-ceramics prosthesis was promoted by interposition of Al-ceramics debris.

Partial Laminectomy vs, Wide Laminectomy for Lumbar Canal Stenosis

24 patients operated by partial laminectomy and 22 patients operated by wide laminectomy, with out fusion, were compared. There were no difference between partial laminectomy and wide laminectomy about subjective symptom, ADL, return to the work and satisfaction. But in wide laminectomy, instability after operation increased as time goes on and as degrees of lumbago.

Long-Term Results of Operation for Lumbar Canal Stenosis

Forty-seven patients with lumbar canal stenosis operated were examined by questionaire. Their follow-up period ranged from 5 to 12 years with an average of 8.8 years. The excellent and good results were obtained in 77% of the cases. The results appeared to be correlated with their age, evaluation points, activities of daily living, sensory disturbance, muscle power loss, preoperative ambulatory distance and their follow-up period.