Eight hips (6 patients) had revision total hip arthroplasty for failed uncemented bipolar prostheses using a hemispherical porous-coated socket, a biological ingrowth anatomic system (BIAS) stem, and bone grafting. The average age was 60 years (range, 54 to 67 years), and the average follow-up period was 4 years (range, 3 to 8 years) . Eighty-seven percent of the hips were rated excellent or good according to the hip score developed by the Japanese Orthopaedic Association. No proximal migrations of the uncemented acetabular socket were seen. However, subsidence of the femoral component was seen in 2 hips. One of the stems had radiolucent lines all around the stem, with the patient complaining of occasional thigh pain. One hip dislocation and one anterior cortical penetration of the tip of the stem occurred, but these patients were asymptomatic. The current results in our series are acceptable in comparison to those in the literature. We are currently performing revision surgery with the use of a revised long-stem hip system which has improved proximal geometry to achieve a better fit and fill of the proximal aspect of the femur, utilizing a separate porous-coated metaphyseal sleeve.

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Normal intervertebral disc contains high levels of group II phospholipase A₂ (PLA₂) . To examine its functional roles in disc, we studied the synthesis and secretion of phospholipase A₂ in cultured rabbit annulus fibrosus and articular chondrocytes. Basal PLA₂ activity of annulus fibrosus chondrocytes was very low (0.3 nmol/min/microplate well), whereas the cells spontaneously secreted significant amounts of prostaglandin E₂ (PGE₂) . Addition of interleukin-1β (IL-1β) (200 U/ml) to culture media caused a 10-fold increase in cell-associated PLA₂ activity within 5 h and further rapid increase to the maximal level with time (41 nmol/min/well at 40 h) . IL-1β also activated secretion of both PGE₂ and PLA₂ from the annulus fibrosus chondrocytes; the extracellular PLA₂ activity increased with a lag time of about 10 h and continued to increase linearly with further incubation (13 nmol/min/well at 40 h) . Cultured articular chondrocytes exhibited similar responses to the cytokine stimulation. Immunohistochemical analysis using a polyclonal anti-rat-group II PLA₂ showed that the IL-1β stimulated annulus fibrosus and articular chondrocytes contained immunoreactivity both in the cytoplasm and nucleus, whereas chondrocytes in normal disc and articular cartilage contained immunoreactivity only in the cytoplasm. These results suggest that group II PLA₂ plays a role in secretion and subcellular traffic of substances involved in the production and degradation of extracellular matrix in chondrocytes, and that the subcellular localization of PLA₂ is linked to the regulation of the enzyme function.

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From August 1990 to September 1992, the patellofemoral joints of 12 osteoarthritis knees were resurfaced using Medicarb mesh and rods, which are made of carbon fiber material. All patients were reviewed in 1997. The age of patients at surgery was 44 to 75 year old; mean follow-up time was 5.9 years. The mean hospitalization period was approximately 4 weeks. Pain and crepitus of the patellofemoral joint diminished or decreased in all patients soon after surgery, and desired effects of treatment continued at follow-up. The mean preoperative JOA score of 71.3±8.8 points improved to 86.7±3.9 at 5 years after surgery. X-ray examination revealed that 2 of 12 knees regained joint space on the skyline view. No major complications were found but moderate joint effusion of one knee was noted. The knee needed several aspirations and stabilized at one year after surgery. Our encouraging clinical results show that this procedure, patellofemoral resurfacing using Medicarb mesh and rods, is a good indication for treatment of elderly patients with patellofemoral osteoarthritis.

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We developed a small-diameter fiber arthroscope distinct in design from a conventional lens-system arthroscope. Initially, however, the image quality provided by the fiber arthroscope was inferior to that obtained with the lens-system arthroscope. In order to compensate for this shortcoming, we improved the image quality in real time using a personal computer. The diag-nostic rate was increased by the fiber arthroscope used with a PC, and we found that for such use the arthroscope was more practical. Because of such features as small diameter, flexibility, and visual inspection with minimum invasion, this fiber arthroscope can be applied for smaller joints and narrow spaces within the joint, which are difficult to observe with a conventional lens-system arthroscope. The small-diameter fiber arthroscope is also suitable for use in the office or clinic.

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The aim of this study was to estimate the function of the rotator cuff and scapulothoracic joint roentogenographically and electromyographically in patients with loose shoulder. Ten patients with inferior instability were examined in this study. Eight of 10 patients had symptoms. In these 8 patients, Scapula-45 radiographs with the arm at the side revealed inferior displacement of the humeral head and slightly upward migration of the humeral head at 45 degrees elevation. Although radiographs taken with the arm at the side also revealed inferior displacement of the humeral head in 2 patients without symptoms, radiographs at 45 degrees elevation revealed good adaptation of the humeral head to the glenoid fossa. Inferior inclination of the scapula was seen with the arm at the side in 10 patients. Although the scapula rotated upward at 45 degrees elevation in 2 patients, the scapula did not rotate upward in symptomatic patients. In IEMG study, the ratio of supraspinatus muscle activity to deltoid activity remained almost stationary irrespective of load in 2 patients without symptoms at 45 degrees elevation.

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Fixation of the tibia! component in 10 knees with uncemented unicompartmental knee arthroplasties (UKAs) for gonarthrosis was studied using roentgen stereophotogrammetric analysis (RSA) . All tibial components were fixed with 2 screws. The follow-up period was for over 2 years. Fixation of the prostheses remained clinically sound in all cases, however, signifi-cant migration was detected radiologically in all cases. The greater part of the migration occurred during the first 3-6 months post-surgery, after which all prostheses remained stable. The mean migration was 1.99 mm at 2 years (subsidence, 1.64 mm; lateral, 0.66 mm; anterior, 0.16 mm) . This was significantly greater than that of uncemented total knee arthroplasties (p<0.01) . Migration of UKAs affects the alignment of the lower limbs. This effect was particu-larly apparent in the case of subsidence. These results suggest that UKAs are better performed using cement.

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Thirteen elbows in 11 patients with rheumatoid arthritis were treated with Kudo type, uncemented total elbow arthroplasties. Prior to surgery, the elbows were grade 4 or 5 according to Larsen radiological criteria. The patients were followed for an average of 4.3 years (range, two to nine years) .
According to Kudo's category, there were 2 elbows with painful stiffness, 9 with painful instability, and 2 with ankylosis. The results, assessed according to the scoring system of the Japanese Orthopaedic Association, revealed remarkable improvement in pain, ROM in flexion and supination of the elbow, and function. Average rating of the elbows improved from 39 to 69 points. The mean flexion arc of the elbows improved from 101°to 130°, which is statistically significant. Although radiological findings revealed radiolucent lines around the ulnar component in 4 patients, total elbow arthroplasty is a valuable procedure to restore daily life activities of patients with rheumatoid arthritis.

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Two cases of bizarre parosteal Osteochondromatous proliferation (BPOP) were treated with EHDP (ethane-1, hydroxy-1, 1-diphosphonic acid), after local resection of the lesion based on the hypothesis that BPOP is a form of heterotopic ossification. In one case in which the lesion affected the humerus, the tumor recurred one month after the operation, possibly due to a delay of treatment and the short duration of drug administration. In the other case, which was a rerecurrent lesion affecting the middle phalanx, no evidence of recurrence was noted two years after the last surgery. This patient was treated with EHDP for three months. The difference in outcome between these two cases may have been due to the difference in the duration of EHDP treatment. However, the size of this small clinical trial precludes the formation of the firm conclusion that EHDP is effective in preventing local recurrence of BPOP.

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