Masahiro Ohnuma

Radial displacement of the medial meniscus in varus osteoarthritis of the knee.

The macroscopic and histologic findings for 31 medial menisci and medial tibial plateaus obtained during total knee arthroplasty were examined to clarify the etiology and progression of varus osteoarthritis. Medial menisci were preserved fairly well in cases of severe osteoarthritis in which the medial joint space had already disappeared. The anterior segment was preserved in 26 (84%) menisci and the posterior segment was preserved in 11 (35%). The medial meniscus may have been preserved because of its radial displacement. Exposure of subchondral bone of the medial tibial plateau occurred in all 31 knees. The exposure of subchondral bone was centered in the anterior, middle, and posterior in nine, 10, and 12 medial tibial plateaus, respectively. There was a mechanical inconsistency between the pattern of preservation of the medial menisci and the location of exposure of subchondral bone on the medial tibial plateaus. The inconsistency reflects that the segment of the medial meniscus on which the excessive load was considered to exist was preserved fairly well. The authors’ hypothesis for explaining this inconsistency is that radial displacement of the medial meniscus precedes narrowing of the medial joint space during progression of varus osteoarthritis, so that the displaced meniscus is saved from severe degeneration or attrition.

Histologic Findings and Possible Causes of Osteochondritis Dissecans of the Knee

Background The histologic findings of osteochondritis dissecans of the knee vary widely, leading to differences in the interpretation of its origins. Hypothesis The differences in the histologic findings of osteochondritis dissecans might represent a course of pathologic progression. Study Design Descriptive laboratory study. Methods Twelve knees in 11 patients (average age, 16 years) with osteochondritis dissecans of the medial femoral condyle were treated by biological internal fixation. During the surgery, cylinder osteochondral plugs were taken from the center of the osteochondritis dissecans lesion and examined with light microscopy. Results A complete or partial cleft separated the specimens into 2 parts: basal and fragment sides. The surface of the basal side was covered with dense fibrous or cartilaginous tissue and active bone remodeling was found beneath the surface. In the fragment side, the deep surface was also covered with dense fibrous or cartilaginous tissue and the articular surface consisted of normal articular cartilage. The area between these 2 surfaces could be classified into 3 types: (1) necrotic subchondral trabeculae, (2) viable subchondral trabeculae, and (3) cartilage without bone trabeculae. Conclusion Based on the histologic findings of this study, the following origins and the pathologic progression of osteochondritis dissecans might be assumed: the initial change in the subchondral area is bone necrosis or subchondral fracture; the necrotic bone is then absorbed and replaced either by viable subchondral trabeculae or cartilage without bone trabeculae. Clinical Relevance The results of this histologic study provide readers with several insights about the causes and treatment options of osteochondritis dissecans.

Cylindrical osteochondral graft for osteochondritis dissecans of the knee: A report of three cases

The treatment for osteochondral defects after separation of the fragments of osteochondritis dissecans of the knee has recently been greatly advanced using mosaicplasty or autologous chondrocyte transplantation. Ideally, the osteochondritis dissecans fragment should be fixed before the occurrence of separation or formation of loose bodies. The method of treating a patient with an osteochondritis dissecans lesion of the knee depends on whether the epiphyseal cartilage on the growth plate is open or closed. Although rest or drilling usually achieves union of the fragment in the presence of an open physis, secure internal fixation using screws, wires, or bone pegs is usually needed after growth plate closure. Unfortunately, damage to the articular cartilage can occur when using these fixation devices. In 1999, Berlet et al. reported on a patient treated with an autogenous osteochondral graft (mosaicplasty) for an unstable osteochondritis dissecans lesion of the knee. They used three 4.5-mm diameter osteochondral plugs and described their method as biologic internal fixation. Between 1995 and 1997, we treated three patients with osteochondritis dissecans using a 10-mm diameter cylindrical osteochondral graft to both internally fix and allow repair of the fragment. All three patients had closed growth plates. Our method is consistent with the concept of biologic internal fixation described by Berlet et al. In this study we report our technique and the outcomes of treatment in these three patients. SURGICAL TECHNIQUE

Traumatic separation of a type I bipartite patella: a report of four knees.

Four knees in three patients with traumatic separation of a Type I bipartite patella are reported. Sudden anterior knee pain and an audible pop occurred at the time of the injury and the patients had aching or dull pain before the traumatic episode. Previous aching or dull pain led us to differentiate this type of injury from a usual transverse fracture. A round fracture line seen on the radiographs also led us to differentiate this type of injury from a stress fracture. Accordingly, the diagnosis of a traumatic separation of a Type I bipartite patella was confirmed. This is the first report of a traumatic separation of a Type I bipartite patella to our knowledge.

Function of the shoulder muscles during arm elevation: an assessment using positron emission tomography

Although 2‐deoxy‐2‐[18F]fluoro‐D‐glucose (FDG) positron emission tomography (PET) has been used for the assessment of skeletal muscle activities, its application to the shoulder muscles is only sparse. The purpose of this study was to investigate the activities of the shoulder muscles during arm elevation using PET. Six healthy volunteers performed an arm elevation exercise before and after FDG injection. The exercise consisted of 200 repetitions of arm elevation in the scapular plane with a 0.25‐kg weight fixed to the wrist on both arms. PET examination was performed 50 min after FDG injection. For control data, PET scan was repeated for each subject on a separate day without any exercise. The volume of interest was established for each shoulder muscle. The subscapularis was divided into three portions (superior, middle, and inferior). The standardized uptake value (SUV) was calculated in each muscle to quantify its activity. The SUVs increased significantly after exercise in the deltoid, supraspinatus, and the superior portion of subscapularis. Among three divided portions of the subscapularis, the SUV of the superior one‐third was significantly greater than the rest of the muscle after exercise. Our current study clearly indicated that there were two functionally different portions in the subscapularis muscle and the superior one‐third played an important role during arm elevation in the scapular plane.

Pigmented villonodular synovitis of the knee with lesions of the bursae.

Five patients with pigmented villonodular synovitis of the knee associated with lesions of the posterior periarticular bursae were treated by posterior exploration, excision of the bursal tissue, and routine anterior synovectomy of the knee. It was hypothesized that complete excision of the posterior periarticular bursae would reduce the high recurrence rate of pigmented villonodular synovitis of the knee. To completely excise the periarticular lesions, two posterior oblique skin incisions were used. In all patients, periarticular lesions were seen clearly on computed tomography scans after air arthrography and on magnetic resonance imaging scans. The patients were followed up for 6.9 years on average (range, 3.3–8.1 years) after surgery. One of five patients required reoperation because of recurrence. Two of five patients required manual mobilization after release of the intraarticular adhesion. However, in the remaining three patients, who started continuous passive motion exercise immediately after surgery, full range of motion was restored within 3 months after the operation. Complete excision of the periarticular lesions is recommended to reduce the high recurrence rate, and continuous passive motion exercise immediately after surgery also is recommended to prevent reduction of range of motion.

Reliability and validity of the Japanese version of the short questionnaire to assess health-enhancing physical activity (SQUASH squash) scale in older adults

[Purpose] We tested the reliability and validity of the Japanese version of the Short Questionnaire to Assess Health-enhancing Physical Activity scale in asymptomatic older adults and sought to confirm discriminator validity in women with osteoarthritis. [Subjects] The participants included an asymptomatic comparison group (men and women) and women with knee or hip osteoarthritis. [Methods] The test-retest method was used to assess reliability. The International Physical Activity Questionnaire was chosen to assess criterion-related validity. Discriminator validity was assessed by comparing the asymptomatic and osteoarthritis groups. [Results] Mean age for the asymptomatic groups was 63 ± 6 years for men (n = 23) and 61 ± 7 years for women (n = 51), and it was 63 ± 9 years for the osteoarthritis group (n = 32). The total score and scores for all items, except for heavy housework items, were significantly correlated with the retest. Criterion-related validity showed significantly weak to moderate correlations between the respective scale categories. For discriminator validity, the total scores and scores for bicycle commuting, light housework, and three leisure items differed significantly between the asymptomatic and osteoarthritis groups. [Conclusion] The Short Questionnaire to Assess Health-enhancing Physical Activity scale is a reliable and valid measure in asymptomatic older adults, and can discriminate between osteoarthritic and asymptomatic women.

Osteochondritis dissecans of the knee in identical twins: a report of two cases

We report the second case of osteochondritis dissecans (OCD) of the knee in identical twins (bilaterally in one and unilaterally in the other). Fixations with bio-absorbable pins, cylindrical osteochondral graft, and osteochondral mosaicplasty were all successful and bone union was achieved. We considered that genetic factors remain essential even if other factors (particularly repetitive trauma) are mainly responsible for the occurrence of OCD.

Assessment of articular cartilage of the lateral tibial plateau in varus osteoarthritis of the knee

This study describes the soft X-ray examinations of 24 lateral tibial plateaus obtained during total knee arthroplasty for varus osteoarthritis. The average thickness of the articular cartilage was 3.5 min and ranged from 2.1 to 5.0. We considered that 21 out of the 24 lateral tibial plateaus had well preserved articular cartilage. Within the well preserved articular cartilage, bony protuberances of various sizes were found in five cases. All lateral tibial plateaus except one showed osteophyte formation. We considered that 12 of the 24 lateral tibial plateaus had large osteophytes. Ten of these 12 lateral tibial plateaus had well preserved articular cartilage. Large osteophyte formation may not necessarily be a contra-indication of high tibial osteotomy (HTO) or unicompartmental knee arthroplasty (UKA). Cases with a bony protuberance may not be suitable for HTO or UKA, because the overlying articular cartilage is thin and inadequate for supporting load.

Bony island within the articular cartilage of the knee in a child: a rare condition for early osteoarthritis

Articular cartilage is a specific type of connective tissue composed of hydrated proteoglycans within a matrix of collagen fibrils. In the elderly population, it shows degenerative changes that may results in osteoarthritis. The more severe form of osteoarthritis occasionally demonstrates bone formation within the cartilage, which is designated as a bony protuberance, however, such lesions are rare in children. This report presents the case of a 10-year-old boy with a bony protuberance within the articular cartilage of the knee. The patient initially complained of knee pain and he subsequently developed flexion contracture. Radiological and arthroscopic examinations revealed a bony protuberance in the articular cartilage and degenerative changes of the cartilage above it. He was successfully treated by the removal of the bony protuberance and osteochondral grafting. The bony protuberance may have caused cartilage degradation since the thickness of the cartilage above it was thinner than that around the lesion. The bony protuberance within the articular cartilage formed in the younger population may be a possible cause of osteoarthritis. This case is a noteworthy with regard to the pathogenesis of osteoarthritis.