A Novel Grading System of Destructive Lumbar Spondyloarthropathy Based on Evaluation of the Facet Joints.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To develop and evaluate a new grading system for destructive lumbar spondyloarthropathy (DLSA) by assessing bony destruction of the facet joints; to evaluate interrater reliability; and to determine the association between anteroposterior (AP) dural sac diameter at the lumbar level and the new grading. SUMMARY OF BACKGROUND DATA: The characteristics of DLSA are unknown, hindering clinical care and research. Imaging to determine the cause of DLSA may positively contribute to patient outcome or well-being by providing prognostic information. PATIENTS AND METHODS: In the magnetic resonance images (MRIs), we measured an axial midline AP dural sac diameter and evaluated bone destruction caused by amyloidosis at the level of the center of each lumbar disk of the lumbar spine. Two orthopedic surgeons independently evaluated each case at two-month intervals and assigned the grade by rating bone destruction at each lumbar level. Weighted κ and intraclass correlation coefficients for interrater reliability were calculated. In addition, the correlation between the AP diameter of the spinal dural sac at the lumbar level and the new MRI-based DLSA grade was examined. RESULTS: The sample size of 82 patients was reached by examining records of 118 consecutive patients. The mean (SD) age of the included patients was 65 (7.2) years, and 36 (43.9%) were women. The grading of DLSA showed moderate to good interrater reliability at both assessments (κ, 0.59-0.78). Intraclass correlation coefficient showed substantial to excellent agreement (intraclass correlation coefficient, 0.63-0.86). The AP diameter of the spinal dural sac at the lumbar level showed a significant correlation with the new grading ( P <0.001). CONCLUSIONS: The new MRI-based grading system for DLSA has good interrater reliability, although the strength of agreement varies somewhat. The new grading system correlates with AP dural sac diameter. Thus, this classification focused on facet erosion, which leads to functional incompetence may be helpful in surgical decision-making.

Association Between Simultaneous Bilateral Total Hip Arthroplasty Without Any Anticoagulant or Antiplatelet Therapy and Deep Venous Thrombosis: A Cohort Study.

BACKGROUND: The association of simultaneous bilateral total hip arthroplasty (THA) with postoperative deep venous thrombosis (DVT) remains controversial. The aim of the study is to determine whether simultaneous bilateral THA without chemoprophylaxis has a higher risk than unilateral THA without chemoprophylaxis. METHODS: This is a population-based retrospective cohort study of all adults who underwent primary THA without any anticoagulant or antiplatelet therapy between July 2012 and March 2021 at the Department of Orthopedic Surgery, Toranomon Hospital, Tokyo, Japan. The association of simultaneous bilateral THA with postoperative DVT was examined by unadjusted analysis and overlap propensity score weighting. The primary outcome was the incidence of DVT (confirmed by ultrasonography of the lower limb veins) within 7 days postoperatively. RESULTS: Of the 557 consecutive patients who underwent primary THA in the study period, 458 met the inclusion criteria. The mean (standard deviation) age of these patients was 67 (11.7) years, and 364 (79.5%) were women; 75 (16.4%) of the 458 patients underwent simultaneous bilateral THA, and 383 (83.6%), unilateral THA. A total of 64 patients (14.0%) developed a postoperative venous thromboembolism, all of which were a distal DVT. The overlap weighting analysis found no significant difference in the incidence of postoperative DVT complications among patients who underwent simultaneous bilateral THA and those who underwent unilateral THA (31.1 [13.6%] vs 22.9 [10.0%], respectively; risk ratio, 1.36; 95% confidence interval, 0.67 to 2.77; P = .40). CONCLUSIONS: Our findings indicate that the occurrence of DVT within 7 days after surgery is not significantly different between patients undergoing simultaneous bilateral THA or unilateral THA without any anticoagulant or antiplatelet therapy. LEVEL OF EVIDENCE: Level II-III.

Effect of loaded exercise for renal osteodystrophy.

We performed bone histomorphometric analysis of biopsy specimens from two patients with hyper- and hypoparathyroidism and a history of long-term hemodialysis (HD) because of diabetes. Case 1, a 53-year-old man with hyperparathyroidism, had been on HD for 22 years, and Case 2, a 54-year-old woman with hypoparathyroidism, for 20 years. Intact parathyroid hormone levels were 1070 and 3 pg/mL, respectively. Case 1 had mixed renal osteodystrophy (fibrous tissue volume to total volume [Fb.V/TV], 5.21%; osteoid volume to bone volume [OV/BV], 19.8%), and Case 2 had adynamic renal osteodystrophy (Fb.V/TV, 0%; OV/BV, 0.54%). Case 1 showed cortical bone thinning (cortical width, 0.2 mm) and porosis (cortical porosity, 14.1%), but case 2 did not (cortical width, 0.84 mm; cortical porosity, 11.6%). Trabecular connectivity of cancellous bone was preserved in both patients, with a bone volume to total volume of 18.2% in case 1 and 35.1% in case 2. Both patients had been doing daily strength training and treadmill walking (2-3 h/day) for over 10 years. Although case I showed cortical thinning and porosis, we suggest that long-term loaded exercise therapy may help to preserve cancellous trabecular bone in both hyperparathyroidism and hypoparathyroidism.

Dialysis-related carpal tunnel syndrome in the past 40 years.

PURPOSE AND METHOD: Patients on hemodialysis develop carpal tunnel syndrome (CTS) due to an accumulation of dialysis-related ß2 microglobulin (ß2m) amyloid (DRA). In Japan, dialysis technology has progressed remarkably in the past 40 years and has increased the time until patients require surgery for CTS. However, unclear is whether the time from the start of hemodialysis to the first surgery for CTS is associated with ß2m clearance by the different hemodialysis techniques. Therefore, we retrospectively evaluated ß2m clearance, serum ß2m levels, and the change in the length of this period in patients across 4 periods according to the year that first surgery for CTS was performed: period 1, 1982-1989; period 2, 1990-1999; period 3, 2000-2009; and period 4, 2010-2019. RESULT: A total of 222 patients who met the selection criteria were included. Mean ß2m clearance was -1.8 ± 16.7% in period 1, and improved to 65.4 ± 8.6% in period 3. Accordingly, the serum ß2m value after hemodialysis decreased significantly. The time from the start of hemodialysis to the first surgery for CTS was 12.4 ± 2.9 years in period 1 but increased to 21.8 ± 6.3 years in period 3. In multivariable linear regression analysis, the significant factors contributing to ß2m clearance were periods 2, 3, and 4. In particular, the relation between removal of ß2m and the extension of the dialysis vintage in period 1 and 2 was remarkable compared with periods 3 and 4. CONCLUSION: Our findings indicate that improvement of ß2m clearance via advances in dialysis technology might result in a significant extension in the time between starting HD and the first surgery for CTS.

Long-term use of glucocorticoid exacerbates bone lesions in postmenopausal women with rheumatoid arthritis.

Glucocorticoid-induced osteoporosis is osteoporosis arising due to long-term use of glucocorticoids. Despite decades of intense research, the effects of long-term use of glucocorticoids in humans on bone cells and bone structural changes remain unclear. We performed post-mortem histomorphometric analysis of bone from two female patients with rheumatoid arthritis aged 64 and 85 years. Our two patients had been treated with glucocorticoids for 19 and 14 years, respectively. In Case 1, all markers of cancellous bone volume were markedly decreased compared with the age-matched reference range. Connectivity of cancellous bone trabecula was absent. Only a few island bones were noted. There was prominent thinning of the cortical bone and extension of the bone marrow cavity into the cortical bone with prominent cortical porosis. Cortical nodes between the endocortical surface and the trabecula disappeared due to endocortical resorption. Stoppage of lamellar structure was observed because the bone resorption by osteoclasts surpassed bone formation by osteoblasts. Empty lacunae characterised by disappearance of osteocytes were visible. In Case 2, all volume markers of cancellous bone were decreased to the same extent as Case 1. However, cortical porosis was more prominent than Case 1. These two cases suggest that use of glucocorticoid therapy >10 years can induce severe osteoporosis in elderly rheumatoid arthritis women with higher disease activity and that the disappearance of cancellous bone is the common characteristic. The 85-year-old woman was characterised by cortical porosis.

Case report: Osteomalacia due to bisphosphonate treatment in a patient on hemodialysis.

BACKGROUND: No publications have reported on osteomalacia in patients receiving intermittent cyclical therapy with etidronate (a bisphosphonate) and undergoing long-term hemodialysis (HD). CASE PRESENTATION: We report on a 46-year-old Japanese man admitted to our hospital for further examination of left forearm pain. Maintenance HD was started at age 24 years, and the man had been on HD since then. At age 38 years, surgical parathyroidectomy was performed for secondary hyperparathyroidism; iliac crest bone biopsy performed at the same time showed osteitis fibrosa. The active vitamin D3 preparation calcitriol was started, and intermittent cyclical etidronate therapy was introduced 2 years later for osteoporosis. At age 45 years, the patient stopped taking calcitriol because of hypercalcemia but continued with etidronate. At age 46 years, a pseudofracture with a Looser zone occurred in the left ulna, and left femur bone biopsy revealed osteomalacia. Etidronate was discontinued, and calcitriol was restarted; open reduction and internal fixation with an angular stability plate were performed. Union of the bone was achieved 10 months after the operation. At age 49 years, a lumber bone biopsy confirmed improved bone morphometry. CONCLUSIONS: We believe that intermittent cyclical etidronate therapy without administration of active vitamin D3 during long-term HD might have induced osteomalacia, resulting in the ulna insufficiency fracture. Therefore, we propose that administration of active vitamin D3 is essential to prevent osteomalacia in patients on long-term HD who are receiving bisphosphonates and have potential vitamin D3 deficiency.

New bone-like tissue formation in calcific tendinopathy: A case report.

Currently, the pathogenesis of nontraumatic heterotopic ossification (HO), e.g., bone-like tissue in calcific tendinopathy remains unclear. Here, we report a 75-year-old, right-handed Japanese woman who had been on hemodialysis for 3 years and was admitted to our hospital to evaluate pain and swelling of the right forearm. She worked as a cook, and her main job over the 3 most recent years had been the frequent and continuous shredding of cabbage. A radiograph showed the highly radiopaque material on the dorsal aspect of the right wrist and in the right shoulder. The biopsy of this radiopaque material revealed HO with marrow, as well as calcified material. Histomorphometric analysis of the HO identified a severe type of osteitis fibrosa with a fibrous tissue volume to total volume of 19.8% (>0.5% required for diagnosis) and an osteoid volume to bone volume of 20.0% (>15% required for diagnosis). We found more woven bone-like tissue than lamellar bone-like tissue. However, the intact parathyroid hormone level was 3-times the normal upper limit with 203 pg/mL, but histomorphometric analysis of the right iliac crest revealed normal bone structure. These findings indicate that the frequent and continuous shredding action with the right hand contributed to the nontraumatic HO localized on the dorsal aspect of the right wrist.

Diaphyseal femoral fracture due to severe vitamin D3 deficiency and low parathyroid hormone levels on long-term hemodialysis: a case report.

INTRODUCTION: Currently, there are no reports of diaphyseal femoral fracture equivalent to atypical femoral fractures (AFFs) in patients receiving long-term hemodialysis (HD). CASE REPORT: A 56-year-old Japanese man receiving long-term HD for 34 years was admitted to our hospital due to a delay in postoperative healing. The patient began maintenance hemodialysis at 22 years of age. The patient then underwent surgical parathyroidectomy (PTX) for secondary hyperparathyroidism at 43 years of age, which resulted in decreased levels of parathyroid hormone (PTH). Thereafter, this patient's serum 1,25(OH)2 D3 level was very low because active vitamin D3 derivative was not administered. At 54 years of age, a transverse fracture of the femoral shaft equivalent to AFF occurred. Surgery with open reduction and internal fixation using intramedullary nailing was performed; however, the delay of postoperative healing continued for 16 months. A left iliac crest bone biopsy was performed and showed osteoid-like lesion and an increase of woven bone. The patient received active vitamin D3 derivative and recombinant human PTH (1-34) derivative. Twenty-nine months after the first surgery, a reoperation was performed. Simultaneously, a right iliac crest bone biopsy was performed. Bone morphometrical improvement was confirmed. Six months after resurgery, the bone union was achieved. Severe vitamin D3 deficiency and decreased levels of PTH may induce a higher osteoid state and an increase of woven bone, which may then attribute to the development of diaphyseal femoral fracture and impairment of postoperative bone healing. It is hypothesized that treatment with active vitamin D3 and teriparatide acetate may be a therapeutic option via the accelerated formation of lamellar bone for refractory diaphyseal femoral fracture of long-term dialysis.

[Osteoarthritis].

Osteoarthritis (OA) is the most common cause of arthritis, and is associated with significant pain and disability. Epidemiological study showed a large number of the eldery in Japan suffered OA, especially OA of the knee. Rapid diagnosis and conservative treatments those includes patient education, weight loss, exercise, physical and occupational therapy are effective at early stage. Pharmacologic treatment are acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs) including cyclooxygenase-2 (COX-2) selective agents. Surgery of the joint arthroplasty significantly reduces knee and hip pain, and restores the functions of the patient at the end stage.

Independent association of joint space narrowing and osteophyte formation at the knee with health-related quality of life in Japan: a cross-sectional study.

OBJECTIVE: To clarify the individual associations of joint space narrowing (JSN) and osteophytosis at the knee with quality of life (QOL) in Japanese men and women using a large-scale population-based cohort from the Research on Osteoarthritis Against Disability (ROAD) study. METHODS: The associations of minimum joint space width (JSW) and osteophyte area in the medial compartment of the knee with QOL parameters, such as the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), were examined. Minimum JSW and osteophyte area in the medial compartment of the knee were measured using a computer-aided system for the diagnosis of knee osteoarthritis. RESULTS: Of the 3,040 participants in the ROAD study, the present study included 2,039 participants age 40 years or older who completed the questionnaires (741 men and 1,298 women with a mean ± SD age of 68.6 ± 10.9 years). Multiple regression analysis after adjustment for age and body mass index showed that minimum JSW was significantly associated with scores on the pain domains of the WOMAC in men and women, while osteophyte area was significantly associated with scores on the physical function domains of the WOMAC in men and women. CONCLUSION: The findings of this cross-sectional study using a large-scale population from the ROAD study indicate that JSN and osteophytosis are independently associated with QOL.

Health-related quality of life in subjects with low back pain and knee pain in a population-based cohort study of Japanese men: the Research on Osteoarthritis Against Disability study.

STUDY DESIGN: Cross-sectional surveys of health-related quality of life (QOL) in subjects with low back pain and knee pain using a population-based cohort. OBJECTIVE: The purpose of the present study was to clarify the impact of low back pain and knee pain on QOL in men. In addition, we analyzed the impacts of vertebral fracture (VFx), lumbar spondylosis, and knee osteoarthritis (OA) on the magnitude of QOL loss in men with low back pain and knee pain. SUMMARY OF BACKGROUND DATA: Low back pain and knee pain are major public health issues causing disability among the elderly men, but there were no population-based studies to compare the impact of low back pain on QOL with that of knee pain in Japanese men. METHODS: From 3040 participants in the Research on Osteoarthritis Against Disability study, data from 767 men older than 40 years who completed questionnaires (mean age = 69.7 years) were examined. To carry out the QOL assessment, the Medical Outcomes Study Short Form 8 (SF-8) and EuroQol (EQ-5D) were used. We examined the association of low back pain and knee pain with QOL. Furthermore, we also examined the presence of VFx and the severity of lumbar spondylosis and knee OA with the magnitude of QOL loss in men with low back pain and knee pain, respectively. RESULTS: The impact of low back pain on QOL was larger than that of knee pain. In men with low back pain, there were few associations between Kellgren-Lawrence grade and QOL, whereas VFx was associated with physical QOL. For men with knee pain, Kellgren-Lawrence grade equal to 4 knee OA was associated with QOL. CONCLUSION: This study revealed that low back pain has a larger impact than knee pain on QOL. Furthermore, low back pain with VFx is strongly associated with physical QOL loss.

[Recent progress in orthopaedic managements of osteoporosis-related fractures].

Recent progress in orthopaedic treatment of osteoporosis-related fractures was reviewed. In the treatment of femoral neck fractures, impacted or nondisplaced type is treated by three cannulated cancellous pins. Displaced type of femoral neck fracture is treated by bipolar prosthesis. Results of femoral neck fractures are influenced by the complications of each patients. Osteoporotic spine fractures are commonly healed within 2 or 3 months. Spinal compression with paraparesis or paraplegia is unusual complication in burst type of spine fractures. Surgical decompression, bone grafting and stabilization with instrumentation can result in some correction of deformity and neurogenic recovery. Distal radius fractures are common fractures in the eldery. Recently advances includes external fixation and plate fixation for the comminuted fractures in the distal radius. Treatments of osteoporosis-related fractures are still difficult problems to be resolved.

Neutrophil CD64 expression as a diagnostic marker for local infection and crystal-induced arthritis.

The usefulness of neutrophil CD64 expression was examined in diagnosing local infection, including soft tissue, bone, and joint infections. Among 99 patients suspected of local infection, 31 were confirmed and 68 patients were not. The CD64 level of patients with local infection was significantly higher than in those without infection [4,193 ± 1,132 vs. 1,017 ± 59 molecules/cell (mean ± standard deviation); p < 0.001]. The area under the curve of CD64 calculated by receiver operating characteristic curve analysis was larger than that of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), or white blood cell (WBC) count. In addition, CD64 levels of patients with crystal-induced arthritis remained within cutoff value (2,000 molecules/cell). These data suggest that measuring CD64 expression can be a useful diagnostic marker for local musculoskeletal infection and crystal-induced arthritis.

Impact of knee and low back pain on health-related quality of life in Japanese women: the Research on Osteoarthritis Against Disability (ROAD).

Although knee and low back pain are major public health issues, little information is available on their impact on the quality of life (QOL). We have investigated the impact of knee and low back pain on the QOL in Japanese women by assessing the associations between knee pain and low back pain and various QOL domains using measures such as the Medical Outcomes Study Short Form-8, EuroQOL, and the Western Ontario and McMaster Universities Osteoarthritis Index. From the 3,040 Japanese women participating in the Research on Osteoarthritis Against Disability (ROAD) study, we analyzed data on 1,369 women >40 years old (mean age 68.4 years). We further examined the associations of Kellgren-Lawrence (KL) grade at the knee and lumbar spine and the presence of vertebral fracture (VFx) with the magnitude of QOL loss in women with knee pain and low back pain, respectively. Knee pain and low back pain were found to be significantly associated with lower QOL scores among the women comprising the study cohort. In women with knee pain KL = 4, knee osteoarthritis was strongly associated with the magnitude of QOL loss. For women with low back pain, no significant associations were found between KL grade and magnitude of QOL loss, while there was a moderate association between the latter and VFx.

Percutaneous carpal tunnel release compared with mini-open release using ultrasonographic guidance for both techniques.

PURPOSE: To compare the outcomes of percutaneous carpal tunnel release (PCTR) and mini-open carpal tunnel release (mini-OCTR) using ultrasonographic guidance for both techniques. METHODS: We included 74 hands of 65 women with idiopathic carpal tunnel syndrome (age, 52-71 y; mean, 58 y). Thirty-five hands of 29 women had the PCTR (release with a device consisting of an angled blade, guide, and holder, along a line midway between the median nerve and ulnar artery (safe line) under ultrasonography (incision, 4 mm), and 39 hands of 36 women had the mini-OCTR (release along the safe line, distally under direct vision (incision, 1-1.5 cm) and proximally under ultrasonography, using a device consisting of a basket punch and outer tube. RESULTS: Assessments at 3, 6, 13, 26, 52, and 104 weeks showed no significant differences in neurologic recovery between the groups (p > .05). The PCTR group had significantly less pain, greater grip and key-pinch strengths, and better satisfaction scores at 3 and 6 weeks (p < .05), and less scar sensitivity at 3, 6, and 13 weeks (p < .05). There were no complications. CONCLUSIONS: The PCTR provides the same neurologic recovery as does the mini-OCTR. The former leads to less postoperative morbidity and earlier functional return and achievement of satisfaction. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic III.

Patient education for the treatment of ulnar neuropathy at the elbow.

OBJECTIVE: To assess the effect of patient education, the simplest conservative treatment of ulnar neuropathy at the elbow, and establish its indication. DESIGN: Patients with ulnar neuropathy at the elbow were treated by education. Its effects and factors affecting outcome were investigated. The length of the treatment was at least 3 months. If the symptoms were improving, the follow-up was lengthened. All of the improved patients were followed up at least for 1 year after they reached a plateau of improvement to check recurrence. SETTING: Patients were selected from an outpatient clinic of a general hospital. PARTICIPANTS: Patients (N=77; 80 nerves) with ulnar neuropathy at the elbow diagnosed clinically and electrophysiologically. INTERVENTIONS: Patient education on the pathophysiology and activity modification to unload the ulnar nerve from mechanical stress. MAIN OUTCOME MEASURES: Outcomes were graded as excellent, good, fair, or poor with use of the modified Akahori's classification system. Patient satisfaction was graded as 1 (low) to 5 (high). Repeat nerve conduction studies were performed in those who gave consent, and results were graded as excellent, good, fair, or poor. RESULTS: Fifty-three nerves (66%) had excellent or good outcomes. Multivariate logistic regression analysis revealed that degenerative change (graded as normal, mild, moderate, or severe) was associated with the outcome, while age, sex, side, duration and severity of the disease, diabetes, dislocation of the nerve, and smoking were not. Excellent or good outcomes were obtained in 43 (80%) of 54 nerves with no or mild degeneration and 10 (38%) of 26 nerves with moderate or severe degeneration. Recurrence was less frequent in the former (2 of 43 nerves, 5%) than the latter (4 of 10, 40%). The outcomes strongly correlated with the satisfaction scores and repeat nerve conduction study results. CONCLUSIONS: Patient education is effective for a considerable number of patients with ulnar neuropathy at the elbow. Whether this is indicated depends on the grade of elbow degeneration. Those who have no or mild degeneration respond better to this treatment with a lower rate of recurrence than those with more severe degeneration regardless of age, sex, side, duration and severity of the disease, presence or absence of diabetes and dislocation of the nerve, and smoking status.

Prevalence of knee osteoarthritis, lumbar spondylosis, and osteoporosis in Japanese men and women: the research on osteoarthritis/osteoporosis against disability study.

Musculoskeletal diseases, especially osteoarthritis (OA) and osteoporosis (OP), impair activities of daily life (ADL) and quality of life (QOL) in the elderly. Although preventive strategies for these diseases are urgently required in an aging society, epidemiological data on these diseases are scant. To clarify the prevalence of knee osteoarthritis (KOA), lumbar spondylosis (LS), and osteoporosis (OP) in Japan, and estimate the number of people with these diseases, we started a large-scale population-based cohort study entitled research on osteoarthritis/osteoporosis against disability (ROAD) in 2005. This study involved the collection of clinical information from three cohorts composed of participants located in urban, mountainous, and coastal areas. KOA and LS were radiographically defined as a grade of > or =2 by the Kellgren-Lawrence scale; OP was defined by the criteria of the Japanese Society for Bone and Mineral Research. The 3,040 participants in total were divided into six groups based on their age: < or =39, 40-49, 50-59, 60-69, 70-79, and > or =80 years. The prevalence of KOA in the age groups < or =39, 40-49, 50-59, 60-69, 70-79, and > or =80 years 0, 9.1, 24.3, 35.2, 48.2, and 51.6%, respectively, in men, and the prevalence in women of the same age groups was 3.2, 11.4, 30.3, 57.1, 71.9, and 80.7%, respectively. With respect to the age groups, the prevalence of LS was 14.3, 45.5, 72.9, 74.6, 85.3, and 90.1% in men, and 9.7, 28.6, 41.7, 55.4, 75.1, and 78.2% in women, respectively. Data of the prevalence of OP at the lumbar spine and femoral neck were also obtained. The estimated number of patients with KOA, LS, and L2-L4 and femoral neck OP in Japan was approximately 25, 38, 6.4, and 11 million, respectively. In summary, we estimated the prevalence of OA and OP, and the number of people affected with these diseases in Japan. The ROAD study will elucidate epidemiological evidence concerning determinants of bone and joint disease.

Zonal gene expression of chondrocytes in osteoarthritic cartilage.

OBJECTIVE: To determine the chondrocyte metabolism in respective zones of osteoarthritic (OA) cartilage. METHODS: OA cartilage was obtained from macroscopically intact areas of 4 knee joints with end-stage OA. The cartilage was divided into 3 zones, and gene expression profiles were determined in the respective zones by a custom-designed microarray that focused on chondrocyte-related genes. For the genes whose expression was significantly different among the zones, the expression was compared between OA and control cartilage in the respective zones by an analysis using laser capture microdissection and real-time polymerase chain reaction (PCR). For some genes, the correlation of expression was investigated in specific cartilage zones. RESULTS: A total of 198 genes (approximately 40% of those investigated) were found to be expressed at significantly different levels among the zones. Expression of 26 of those genes was evaluated by laser capture microdissection and real-time PCR, which confirmed the validity of microarray analysis. The expression of cartilage matrix genes was mostly enhanced in OA cartilage, at similar levels across the zones but at different magnitudes among the genes. The expression of bone-related genes was induced either in the superficial zone or in the deep zone, and positive correlations were found among their expression in the respective zones. The expression of 5 proteinase genes was most enhanced in the superficial zone, where their expression was correlated, suggesting the presence of a common regulatory mechanism(s) for their expression. CONCLUSION: In OA cartilage, the metabolic activity of chondrocytes differed considerably among zones. Characteristic changes were observed in the superficial and deep zones.