Yujiro Mori

Efficacy of Lateral Retinacular Release for Painful Bipartite Patella

We treated painful bipartite patella with a modified lateral retinacular release technique in 15 patients (16 knees). Bony union of the separated fragment and the patella was obtained in 15 of 16 knees within 8 months of surgery. Sustained traction acting on the patella laterally and proximally is presumed to cause the pain. The surgical technique to reduce this force proved effective not only in relieving the pain but also in achieving bony union. Painful bipartite patella can lead to excessive lateral pressure syndrome or pa tellar compression syndrome, these complications can be effectively treated by this surgical technique. In contrast to conventional treatments, such as ex cision of smaller fragments or osteosynthesis to achieve bony union, the modified lateral retinacular release technique is easy to perform and provides an effective means for relieving patellofemoral pain and achieving bony union.

Osteochondritis dissecans of the patellofemoral groove in athletes: unusual cases of patellofemoral pain.

Five athletes who developed osteochondritis dissecans in the patellofemoral groove in the course of sports events at high school and college league level are described. They were male athletes complaining of anterior knee pain. When examining young people engaged in violent sports, it is well to remember that they might have osteochondritis dissecans in the patellofemoral groove. Clinically, four of the five patients under discussion were characterized by tight movements of the patella in a direction parallel to its transversal axis. X-ray studies in lateral projections and CT scans provided useful tools for definitive diagnosis, but AP radiography was no help in diagnosis. Release of a tight lateral retinaculum with or without drilling on the degenerated cartilage was effective in the treatment of osteochondritis dissecans of the patellofemoral groove in three of the four patients.

Clinical and histological study of patellar chondropathy in adolescents

An arthroscopic and histological investigation of patellar chondropathy in adolescents was performed in 98 knees of 83 patients who were classified into three clinical types of patellofemoral disorder. These were the anterior knee pain syndrome, idiopathic chondropathy, and unstable patella. Histological findings suggested little evidence of progression to high-grade chondropathy in the patients with anterior knee pain syndrome, and this may account for the resolution of clinical symptoms in this group. Even in patients with high-grade lesions in the idiopathic chondropathy and unstable patella groups, histological observations indicated that these lesions could heal either by intrinsic (fibrous metaplasia of chondrocytes and regeneration of matrix) or extrinsic repair. Chondropathy in adolescents may be similar to the early changes of osteoarthritis of the knee. However, chondropathy shows far more potential for repair by the synovium and/or the cartilage itself than does osteoarthritis.

A scanning electron microscopic study of the degenerative cartilage in patellar chondropathy.

Patellar chondropathy as cartilage degeneration localized in patellar cartilage in young persons is characterized by cartilaginous changes, such as softening, swelling, and fissuring. With a view to structural characterization of early cartilaginous degeneration before erosion, the morphology of affected cartilage was studied under a scanning electron microscope. The surface network of cartilage constituting fibrils had an edematous change, presenting with fibrillation on the medial facet, whereas many fibrils of the central ridge had a collagen bundle, and fissuring of varying size was observed. It appeared that a mechanical force (shearing) acting on the site of the central ridge was associated with the formation of a collagen bundle and its destruction. On the lateral facet, fibrils were arranged perpendicular to the joint surface; the superficial layer of fibrils was worn by hyper-pressure acting on the lateral facet. On the fractured surface, the coarseness of collagen fibrils showed changes that varied with the site and stage of cartilage degeneration. Frequent changes were signs of fibril loosening (coarsening), such as reduction in fibril density (i.e., edematous change), collagen fibril aggregation, and fissuring, and longitudinal restructuring of fibrils. The patellar cartilage in the patients of this series showed a structure adapted to the mechanical force. The initial structural changes of cartilage consisted of collagen fibril aggregation and reduction in fibril density. These changes give rise to matrix rarefaction, which in turn causes cartilage degeneration to progress. These changes were concurrent in both the superficial and middle layers and were not localized as basal degeneration.

Pigmented villonodular synovitis of patellar plica

This article reports a rare case of pigmented villonodular synovitis (PVS) arising from the plica synovialis mediopatellaris that impeded the knee joint when it was extended. This lesion was diagnosed and treated by arthroscopy.

Histological comparison of patellar cartilage degeneration between chondromalacia in youth and osteoarthritis in aging.

The histological findings of the patellar cartilage were compared between cases of chondromalacia, which occurs predominantly in young persons (22 patients, average age 19.8 years) and cases of osteoarthritis, which is common among the elderly (21 patients, average age 65.4 years). The histological findings of cartilage in the chondromalacia were characterized by increased density and vigorous fibrous metaplasia of chondrocytes. These findings may be considered to represent a reactive change in the chondrocyte. Cartilage degeneration in osteoarthritis, by contrast, is regressive and presents a clearly different histological picture from that of chondromalacia patellae. We conclude that chondromalacia does not easily lead to osteoarthritis. On the other hand, the cartilage was characteristically softened, as observed by gross inspection, and showed rarefaction of the cartilage matrix. It should be noted that the change was not observed in aging, but showed a pattern of cartilage degeneration peculiar to young patients with chondromalacia patellae.

In vivo change of elastic property in polyethylene acetabular components

Polyethylene is an elastic material. It is known that oxidative degradation of polyethylene occurs after sterilization by means of gamma irradiation. However, there have been few detailed reports with regard to the effects of this degradation on the mechanical property, especially in total hip prostheses. The purpose of this study was to examine the change in mechanical property of irradiated and non-irradiated polyethylene cups after implantation. Fifty-six ultra-high molecular-weight polyethylene (UHMWPE) cups retrieved at revision surgery were evaluated. Thirty-two cups were sterilized by gamma irradiation in air and 24 by ethylene oxide gas (EtO). To evaluate the mechanical property of the cup and its regional distribution, Vickers hardness was measured at nine points at the cross-section of the cups. In the irradiated cups, the hardness increased in proportion to the time from sterilization. This phenomenon was not found in the cups sterilized by EtO. Less change of hardness was observed in the cups sterilized by EtO than in those sterilized by irradiation. The gamma-irradiation in air actually affected the elastic property of cup polyethylene in vivo, although any difference in the wear rate was not detected between two sterilization methods. In cases with accelerated wear of the acetabular cup, other factors affecting wear should also be considered.

The Natural History of Anterior Knee Pain in Japanese Adolescents

Many reports have described that chronic pain in the front of the knee among adolescents can be caused by cartilaginous changes of the patellofemoral joint, so-called chondromalacia of the patella. These cartilaginous changes are often present in patella alta, patellar malalignment syndrome, subluxation of the patella, unstable patella, dysplasia of the patella (such as Wiberg type III), dysplasia of the femoral condyle and others. We also found cartilaginous changes of the patellofemoral joint in these diseases using arthroscopic study or during operations. However, some patients with chronic pain in the front of the knee had no instability of the patella upon physical examination, no abnormalities of the patellofemoral joint (such as incongruity) on radiological study (including skyline view) and no morbid changes on arthroscopic study. Is it reasonable to regard such cases as having a prechondromalacia condition? How should they be categorised and treated? To attempt to answer these questions, we investigated the natural history of anterior knee pain in Japanese adolescents, using questionnaires.

Case report: rheumatoid arthritis occurring during observation after surgery for localized pigmented villonodular synovitis.

Abstract In the rare case presented here, arthroscopic resection was performed after a diagnosis of localized pigmented villonodular synovitis (LPVS) of the knee, but the disorder recurred after about 1 year as the diffuse form, and synovectomy was performed through a medial parapatella incision. Subsequently, rheumatoid arthritis (RA) occurred during the postoperative observation period. The course of this case is interesting because of the combination of the two diseases. In cases of PVS, the possibility of RA should always be considered.