Therapeutic strategies distinguish community based primary care physicians from rheumatologists in the management of osteoarthritis

Using an osteoarthritis (OA) case study, we described the drug therapy that primary care physicians prescribe for uncomplicated OA of the hip, and for OA complicated by a history of gastropathy or renal insufficiency. To produce "gold standard" criteria against which to interpret previous results, the same instrument was administered to 126 rheumatologists selected at random from the membership of the American College of Rheumatology. Virtually all rheumatologists prescribed nonsteroidal antiinflammatory drugs (NSAID); 76% specified doses large enough to have significant antiinflammatory effects. In contrast, 65% of the primary care physicians recommended NSAID therapy in a suboptimal antiinflammatory dose (p = 0.055 for the rheumatologist-primary care physician difference). For OA complicated by a history of either gastropathy or renal insufficiency, rheumatologists were more likely than primary care physicians to adopt a therapeutic strategy that did not inhibit prostaglandin synthesis (p < 0.001 for both). Differences also were noted in the ancillary therapies employed by the 2 groups for managing uncomplicated OA. Educational interactions between rheumatologists and primary care physicians could benefit by recognition of the differing perspectives on NSAID dosing, the avoidance of NSAID induced side effects, and ancillary therapies that appear to differentiate subspecialists and generalists.

Treatment of knee osteoarthritis: relationship of clinical features of joint inflammation to the response to a nonsteroidal antiinflammatory drug or pure analgesic

Our randomized double blinded comparison of acetaminophen versus analgesic and antiinflammatory doses of ibuprofen in the treatment of 182 subjects with knee osteoarthritis (OA) systematically evaluated soft tissue tenderness and joint swelling. Improvement in these signs of joint inflammation was associated with lessening of disability (p = 0.02), and reduction in rest pain (p = 0.07), but not with the drug treatment regimen. Thus, joint tenderness and swelling, presumptive evidence of synovitis, may not be a priori indications for use of an antiinflammatory drug, or predict greater responsiveness to treatment with an antiinflammatory drug than to a pure analgesic, in symptomatic treatment of patients with knee OA.

Reduction of the severity of canine osteoarthritis by prophylactic treatment with oral doxycycline

OBJECTIVE

In vitro studies have indicated that levels of neutral metalloproteinases in osteoarthritic (OA) cartilage are elevated and that doxycycline (doxy) inhibits collagenolytic and gelatinolytic activity in extracts of OA cartilage. The purpose of the present study was to test the effect of oral doxy administration on the severity of cartilage degeneration in OA.

METHODS

OA was induced in 12 adult mongrel dogs by transection of the anterior cruciate ligament (ACL) 2 weeks after dorsal root ganglionectomy. Six dogs received doxy orally from the day after ACL transection until they were killed 8 weeks later; the other 6 served as untreated OA controls.

RESULTS

The unstable knee of each untreated dog exhibited extensive full-thickness cartilage ulceration of the medial femoral condyle. In sharp contrast, cartilage on the distal aspect of the femoral condyle of the unstable knee was grossly normal in 2 doxy-treated dogs, and exhibited only thinning and/or surface irregularity in the others. Degenerative cartilage lesions on the medial trochlear ridge, superficial fibrillation of the medial tibial plateau, and osteophytosis were, however, unaffected by doxy treatment. Collagenolytic activity and gelatinolytic activity in cartilage extracts from OA knees of untreated dogs were 5-fold and 4-fold greater, respectively, than in extracts from dogs given doxy.

CONCLUSION

Prophylactic administration of doxy markedly reduced the severity of OA in weight-bearing regions of the medial femoral condyle. It remains to be determined whether administration of doxy after OA changes have developed is also effective.

Prevalence of cartilage shards in synovium and their association with synovitis in patients with early and endstage osteoarthritis

It has been suggested that incorporation of shards of fibrillated cartilage into the synovium is a cause of synovitis in osteoarthritis (OA). We examined the prevalence with which fragments of cartilage are seen in synovium, and their association with synovitis, in patients with endstage OA and early OA of the knee. Samples of synovium were obtained from 12 patients with endstage OA who were undergoing knee joint replacement and 30 with only mild/moderate radiographic changes of OA who exhibited articular cartilage changes of OA at arthroscopy. The presence of cartilage shards was sought in synovium from the medial and lateral tibiofemoral compartments and the suprapatellar pouch of each patient. Comparable volumes of the synovial lining from patients with endstage and early OA were examined, and tissue mononuclear cell infiltration was graded as an indicator of synovitis. Cartilage shards were seen in synovium from 7 of 12 patients with endstage OA, all of whom had synovitis. No topographic relationship was found between shards and mononuclear cell infiltration. In contrast, cartilage fragments were not seen in synovium from any of the 30 patients with early OA, although 9 of them had full thickness cartilage ulcers and 17 had evidence of synovitis.

A radiographic comparison of erosive osteoarthritis and idiopathic nodal osteoarthritis

Clinical, radiographic and histologic features suggest that inflammation is central to the pathogenesis of erosive osteoarthritis (OA). Since mediators of inflammation may activate osteoclasts and stimulate release of metalloproteinases in joint cartilage, we hypothesized that patients with erosive OA may have more joint space narrowing and less proliferative bone response (osteophytes, sclerosis) than those with idiopathic nodal OA. Hand radiographs of 33 patients with erosive OA and 33 age and sex matched patients with nodal OA were evaluated for prevalence and severity of joint space narrowing, osteophytes, subchondral sclerosis, subchondral cysts, erosions and subchondral collapse. While the prevalence and severity of OA was greater at each joint in erosive OA than in nodal OA, significant differences (p less than 0.05) were confined largely to the interphalangeal joints. Among patients with erosive OA, radiographic features of OA were more severe in joints with erosive changes than in joints that did not show erosive change (p less than 0.01 in most cases). Notably, when joints with erosive change were excluded, only joint space narrowing was more severe in patients with erosive OA than in the corresponding joints of patients with nodal OA (p less than 0.001). Our analysis did not support the hypothesis that inflammatory mediators modify chondro or osteoneogenesis in erosive OA.

Reduction of joint pain in patients with knee osteoarthritis who have received monthly telephone calls from lay personnel and whose medical treatment regimens have remained stable

OBJECTIVE

We previously reported that monthly telephone contact by lay personnel, to promote self-care for patients with osteoarthritis (OA), was associated with improved joint pain and physical function after 1 year of followup. The present study was a secondary analysis to determine whether improvement was contingent on intensified medical treatment.

METHODS

We reanalyzed control/treatment group differences in all 40 subjects with radiographically confirmed knee OA who had had no changes in antirheumatic drug therapy or institution of physical therapy during the period of observation.

RESULTS

Group differences in measured pain remained significant (effect size [ES] = 0.65 SD, P less than 0.01). The same trend was observed for physical function (ES = 0.53 SD, P not significant).

CONCLUSION

The findings in this reanalysis suggest that periodic telephone support interventions are effective enough to be regarded as an adjunctive treatment for OA.

Impairment of osteophyte formation in hyperglycemic patients with type II diabetes mellitus and knee osteoarthritis

OBJECTIVE

Since insulin is a potent growth factor for connective tissue, the present study was designed to investigate whether radiographic features of knee osteoarthritis (OA) in patients with poorly controlled, insulin-resistant type II diabetes mellitus differ from those in nondiabetic controls with knee OA.

METHODS

Radiographs from 25 female patients with diabetes and knee OA were compared with those from 48 female controls who were similar with respect to age, weight, and duration of OA symptoms.

RESULTS

Although the 2 groups were similar with respect to the frequency and severity of joint space narrowing, subchondral sclerosis, and geodes, osteophytes were less common in the patients with diabetes (P = 0.044), and spurring, when present, tended to be "marked" less often in the diabetic patients than in the controls.

CONCLUSION

The data suggest that diminished availability of insulin at the cellular level or diabetic microvascular disease attenuates the chondro- and osteogenesis required for osteophyte formation in the joints of patients with OA.

Neurogenic acceleration of osteoarthrosis. The effects of previous neurectomy of the articular nerves on the development of osteoarthrosis after transection of the anterior cruciate ligament in dogs

The development of osteoarthrosis in unstable knee joints of dogs after transection of the anterior cruciate ligament is greatly accelerated when the afferent nerve fibers from the ipsilateral hindlimb have been interrupted by dorsal root ganglionectomy before transection. The purpose of the current study was to determine whether partial loss of the afferent fibers from the knee joints of dogs, accomplished by neurectomy of the primary articular nerves before transection of the ligament, also accelerates the development of osteoarthrosis. Osteoarthrosis did not develop in dogs that had had transection of the medial, posterior, and lateral articular nerves to the left knee joint but had an intact anterior cruciate ligament. Osteoarthrosis developed in all dogs that had had transection of the anterior cruciate ligament. However, the osteoarthrotic lesions, as gauged by histological and macroscopic criteria, were more frequent and severe in dogs that had had neurectomy before transection than in those that had intact sensory nerves and an unstable joint (p less than or equal to 0.05). A subchondral fracture occurred in three dogs that had had neurectomy and had an unstable joint but in none of the dogs that had intact sensory nerves and an unstable joint.

Structure-function relationships in indium-111 radioimmunoconjugates

Conjugates formed by reaction of monoclonal antibody B72.3 with benzyl isothiocyanate derivatives of four amino polycarboxylate chelators (NTA, EGTA, EDTA, DTPA) were labeled with indium-111 and administered iv to athymic mice bearing antigen-positive (LS174T) and antigen-negative (A375) human tumor xenografts. Conjugate immunoreactivities, antibody dose, and xenograft size were controlled, so that the effects of varying chelate structure could be evaluated under conditions where immunological and physiological factors were effectively held constant. Tissue distribution and excretion of the radiometal at 24 and 48 h postinjection were shown to correlate directly with chelate thermodynamic stability (NTA less than EGTA less than EDTA less than DPTA). Radioactivity levels in the blood and the LS174T xenograft increased, while kidney levels and excretion levels decreased, with increasing chelate stability. The kidney was the only normal organ that accumulated non-antibody-bound 111In, uptake of radioactivity into all other tissues, and in particular the liver, being unaffected by changes in chelate structure. Mean transferrin saturation in the tumor-bearing athymic mice was found to be 65%. It is proposed that uptake of free 111In by serum transferrin is precluded in this model, leading to the observed renal localization of unbound label. Kidney:blood and kidney:LS174T activity ratios at 48 h postinjection provided the most sensitive indices of conjugate instability in vivo, spanning 50- and 20-fold ranges, respectively, between the least stable and the most stable conjugate. It is concluded that this antigen/antibody system and mouse model are well-suited to structure-function studies of immunoglobulin labels.

Hypothesis: can type IX collagen "glue" together intersecting type II fibers in articular cartilage matrix? A proposed mechanism

Type IX collagen is crosslinked to the surface of type II collagen molecules, and has been proposed as the glue that binds the collagen network of cartilage matrix. However, there is as yet no evidence that the crosslinks that have been described to date provide interfibrillar connections, and the only mechanism proposed for such connections between intersecting fibers is unlikely on stereochemical grounds. We propose that both type IX collagen and an intermediary molecule are necessary for network stabilization and that proteoglycans are likely candidates for the role of intermediary.

Correlation of serum concentrations of ibuprofen stereoisomers with clinical response in the treatment of hip and knee osteoarthritis

Stereoselective pharmacokinetic measurements of the active enantiomer, S-ibuprofen, were correlated with clinical response in 45 participants in a randomized double blinded 4 week comparison of ibuprofen, 1200 or 2400 mg/day, for treatment of hip or knee osteoarthritis. Ibuprofen dose correlated with S-ibuprofen area under the serum concentration curve (AUC), trough and average concentration, but not with clinical outcome. AUC of S-ibuprofen correlated with improvement in disability, rest pain and in the physician's global assessment (p = 0.02, 0.08, and 0.10, respectively), and negatively with the subject's weight and creatinine clearance (p = 0.09 and 0.07, respectively). Some individual variation in responsiveness to ibuprofen (and other nonsteroidal antiinflammatory drugs) may be attributed to pharmacokinetic differences.

Low dose prednisone treatment does not reduce the severity of osteoarthritis in dogs after anterior cruciate ligament transection

It was reported recently that oral administration of prednisone, 0.3 mg/kg/day, decreased osteophyte size and cartilage ulceration in dogs with osteoarthritis (OA) produced by "stab" transection of the anterior cruciate ligament. Since this dose would be equivalent to 17 mg/day for a 70-kg human, our study was performed to determine whether a lower, clinically more realistic, dose of prednisone also had ameliorating effects on OA in the canine model. Following arthrotomy and transection of the anterior cruciate ligament 10 adult mongrel dogs were each given prednisone, 0.1 mg/kg/day, begun either 0, 2, or 4 weeks after arthrotomy and continued until sacrifice 12 weeks after surgery; 7 others underwent the identical surgical procedure but received no prednisone and served as OA controls. No differences were noted between dogs treated with prednisone and the controls with respect to size or extent of osteophytes, severity of synovial inflammation, morphologic changes of OA in articular cartilage, or in vitro synthesis of glycosaminoglycans. Increases in cartilage thickness in the OA knee were similar in the 2 groups, as were increases in H2O content and uronic acid concentration. Regardless of the interval between arthrotomy and start of treatment, the low dose of prednisone used here did not reduce the severity of OA in this model.

Transection of the anterior cruciate ligament in the dog: a model of osteoarthritis

Study of the early stages of osteoarthritis (OA) in humans presents numerous difficulties, since the patient commonly does not seek medical attention until pathologic changes are far advanced and articular cartilage has already been extensively lost. Investigators have, therefore, used animal models to obtain information about the early changes in articular cartilage, bone, and synovium. Among the most widely studied of these models is the cruciate-deficient dog. This report validates the cruciate-deficient dog as a model of progressive OA and emphasizes that, before full-thickness loss of articular cartilage, OA is marked by a phase of cartilage hypertrophy associated with a striking increase in synthesis of matrix macromolecules by the chondrocyte (compensatory repair). It reviews evidence that some nonsteroidal antiinflammatory drugs (NSAIDs) and deafferentation of the unstable limb may accelerate cartilage loss in OA, and examines the relationship of synovitis and of changes in subchondral bone to the changes in articular cartilage.

Osteoarthritic changes in canine articular cartilage, subchondral bone, and synovium fifty-four months after transection of the anterior cruciate ligament

Anterior cruciate ligament transection (ACLT) in the dog results in osteophyte formation and in morphologic, metabolic, biochemical, and biomechanical changes in the articular cartilage of the unstable knee that mimic those of human osteoarthritis (OA). However, in dogs studied up to 2 years after ACLT, the changes have appeared to be self-limiting, which has led to the suggestion that this is a model of cartilage damage and repair, rather than of OA. To ascertain whether changes in articular cartilage and subchondral bone of dogs subjected to ACLT lead to progressive changes of OA, we studied 3 dogs for 54 months after ACLT. Arthrotomy was performed in the dogs to visualize and then transect the anterior cruciate ligament. When the dogs were killed, full-thickness ulceration of the articular cartilage was seen on the medial femoral condyle and tibial plateau of the unstable knee, while cartilage in other regions was thicker than that of the contralateral knee, consistent with hypertrophic cartilage repair. Synovial infiltration by mononuclear cells was not more severe than that seen in dogs killed at earlier intervals after ACLT, although gross fibrotic thickening of the capsule was apparent in each dog. Histomorphometric studies revealed a marked increase in subchondral bone volume and active bone formation. These findings show that the changes that develop in the canine knee joint after ACLT are progressive and are unambiguously those of OA.

Radiographic grading of the severity of knee osteoarthritis: relation of the Kellgren and Lawrence grade to a grade based on joint space narrowing, and correlation with arthroscopic evidence of articular cartilage degeneration

We examined standing knee radiographs of 92 patients who had chronic knee pain and radiographic evidence of mild or moderate osteoarthritis (OA) according to the Kellgren and Lawrence (K/L) criteria. Because the K/L criteria overemphasize osteophytosis relative to joint space narrowing (JSN), we graded OA severity also with a scoring system that placed greater emphasis on JSN than on osteophytes. In each case, the articular cartilage was visualized directly at arthroscopy. Of 17 patients whose radiographic findings were normal by both the K/L criteria and our JSN-weighted criteria, 7 had advanced tibiofemoral and/or patellofemoral compartment changes of OA seen at arthroscopy, emphasizing the insensitivity of the radiograph for detecting early articular cartilage loss. In addition, tibiofemoral JSN was common in the presence of normal articular cartilage. The JSN-weighted scale provided no advantage over the K/L criteria for assessing the severity of articular cartilage changes of OA.

The therapeutic approaches of community based primary care practitioners to osteoarthritis of the hip in an elderly patient

Predispositions to prescribe a pure analgesic, a cyclooxygenase inhibiting nonsteroidal antiinflammatory drug (NSAID) or a nonacetylated salicylate for a fictitious, uncomplicated case of osteoarthritis (OA) were surveyed in a sample of 152 community based primary care practitioners who had been characterized with respect to medical education and practice characteristics. Only 2 respondents (1%) prescribed a pure analgesic; 35% prescribed subantiinflammatory doses of cyclooxygenase inhibiting NSAID. The remainder (64%) recommended nonacetylated salicylates and cyclooxygenase inhibiting NSAID in doses large enough to achieve an antiinflammatory effect. Past participants in postgraduate rheumatology electives prescribed more costly regimens than those who had not participated (p = 0.05). When the case was altered to include a history of previous peptic ulcer, 44% chose cyclooxygenase inhibiting NSAID with adjunctive prophylaxis against NSAID induced gastropathy (e.g., misoprostol). When the complication was changed to renal insufficiency, recommendations for sulindac increased 3-fold over those for the uncomplicated case (34 vs 11%), and were most common among more recent medical school graduates and past participants in rheumatology electives (p less than 0.05 for both). The potential effects of educational and practice variables on the therapeutic strategies and costs of OA care in the community merit further systematic study.

Doxycycline inhibits type XI collagenolytic activity of extracts from human osteoarthritic cartilage and of gelatinase

Doxycycline was shown to inhibit digestion of exogenous type XI collagen by homogenates of human osteoarthritic cartilage in vitro. On SDS-PAGE, the cleavage products generated by cartilage extracts were larger and less abundant, indicating less complete cleavage, when doxycycline (10 or 30 microM) was added to the samples. The inhibitory effect was concentration dependent. Purified gelatinase from canine kidney epithelial cells, which also digests type XI collagen, was inhibited in a similar manner by doxycycline. If tetracyclines inhibit this metalloproteinase activity in articular cartilage in vivo, they could modify cartilage breakdown in osteoarthritis.

Comparison of an antiinflammatory dose of ibuprofen, an analgesic dose of ibuprofen, and acetaminophen in the treatment of patients with osteoarthritis of the knee

BACKGROUND

The optimal short-term, symptomatic therapy for osteoarthritis of the knee has not been fully determined. Accordingly, we compared the efficacy of a nonsteroidal antiinflammatory drug, ibuprofen, given in either an antiinflammatory dose (high dose) or an analgesic dose (low dose), with that of acetaminophen, a pure analgesic.

METHODS

In a randomized, double-blind trial, 184 patients with chronic knee pain due to osteoarthritis were given either 2400 or 1200 mg of ibuprofen per day or 4000 mg of acetaminophen per day. They were evaluated after a washout period of three to seven days before the beginning of the study, and again after four weeks of treatment. The major measures of outcome included scores on the pain and disability scales of the Stanford Health Assessment Questionnaire (range of possible scores, 0 to 3), scores on the visual-analogue scales for pain at rest and pain while walking, the time needed to walk 50 ft (15 m), and the physician's global assessment of the patient's arthritis.

RESULTS

Seventy-eight percent of the patients completed four weeks of therapy. No significant differences were noted among the three treatment groups with respect to failure to complete the trial because of noncompliance or adverse events. All three groups had improvement in all major outcome variables, and the groups did not differ significantly in the magnitude of improvement in most variables. The mean improvement (change) in the scores on the pain scale of the Health Assessment Questionnaire was 0.33 with acetaminophen (95 percent confidence interval, 0.14 to 0.52), 0.30 with the low dose of ibuprofen (95 percent confidence interval, 0.09 to 0.51), and 0.35 with the high dose of ibuprofen (95 percent confidence interval, 0.13 to 0.57). Side effects were minor and similar in all three groups.

CONCLUSIONS

In short-term, symptomatic treatment of osteoarthritis of the knee, the efficacy of acetaminophen was similar to that of ibuprofen, whether the latter was administered in an analgesic or an antiinflammatory dose.

Apparent avascular necrosis of the hip: appearance and spontaneous resolution of MR findings in renal allograft recipients

The sensitivity of magnetic resonance (MR) imaging in the detection of avascular necrosis (AVN) of the hip and natural history of the MR findings were determined prospectively in renal allograft recipients, a group at risk for development of the disease. One hundred four patients were studied up to 24 months after transplantation. In 25 hips in 14 patients, MR findings were consistent with AVN. Pain developed in seven hips in four patients; in each hip, the MR images showed abnormality before the onset of symptoms. Plain radiographs showed abnormality in all hips that became painful; however, the plain radiographs of 17 of 18 asymptomatic hips in which MR imaging showed evidence of AVN showed no abnormality over a mean follow-up period of 16 months. All MR lesions in the symptomatic hips were larger than those in the asymptomatic cohort. MR lesions in seven hips (in five asymptomatic patients) regressed in size; in six hips, the MR images returned to normal. The findings suggest that some patients with MR evidence of AVN of the hip have spontaneous improvement.

The presence of cartilage matrix glycoprotein in serum as determined by immunolocation analysis is not a sensitive indicator of "early" osteoarthritis of the knee

Widespread effort is being devoted to the search for a serologic "marker" that could aid in the early diagnosis of osteoarthritis and in following the progression of the disease in response to treatment. It is obvious that such a marker would have its greatest utility in patients with mild or early osteoarthritis. CMGP is a disulfide-bonded 550,000 dalton cartilage matrix glycoprotein with a half-life of only 48 to 72 hours that has been found, through immunolocation analysis, in the serum of dogs with experimentally induced osteoarthritis and in the synovial fluid of patients with osteoarthritis but not other types of arthritis. To determine whether detection of CMGP in serum might be of value in identifying patients with "early" osteoarthritis, we examined serum samples from 26 patients with knee pain who had articular cartilage lesions of osteoarthritis at arthroscopy but whose knee radiographs were normal or showed only mild or moderate osteoarthritis. CMGP was identified by immunolocation analysis with specific antibodies. Eleven patients (42%) were seropositive for CMGP. In two, the degenerative cartilage lesions visualized at arthroscopy were mild (grade 2); in the other nine they were more severe (grade 3 or 4). However, 10 of the 15 seronegative patients also had grade 3 or 4 cartilage degeneration. Thus, this serum assay for CMGP was often negative in this group of patients in the presence of well-defined cartilage degeneration.

Relationship between arthroscopic evidence of cartilage damage and radiographic evidence of joint space narrowing in early osteoarthritis of the knee

We examined the relationship between articular cartilage degeneration, as visualized arthroscopically, and joint space narrowing (JSN) in standing anteroposterior knee radiographs of 161 patients with chronic knee pain. The majority of these patients had radiographic findings of mild osteoarthritis. Twenty-five (33%) of the 76 patients in the series whose radiographs showed tibiofemoral JSN had grossly normal articular cartilage in both tibiofemoral compartments at arthroscopy (false-positive). The specificity of medial JSN for the presence of medial compartment articular cartilage degeneration was 0.61, i.e., only 61% of patients with normal (grade 0) medial compartment cartilage had a normal medial joint space. Of 22 patients with greater than 50% medial JSN, 9 (41%) had normal articular cartilage in the medial compartment at arthroscopy. Of 6 patients with greater than 50% lateral JSN, 3 (50%) had normal lateral compartment articular cartilage at arthroscopy. Among 36 patients with greater than 25% JSN who had neither medial nor lateral compartment articular cartilage degeneration, JSN was associated with articular cartilage degeneration in the patellofemoral compartment in 8 (22%), with meniscus degeneration in 18 (50%), and with both in 8 (22%). Thus, in these patients with chronic knee pain, radiographic evidence of JSN in the tibiofemoral compartment did not permit confident prediction of the status of the articular cartilage.

The effect of intertrabecular fluid on femoral head mechanics

The effect of intraosseous fluid on the mechanical characteristics of bone is unclear. To determine the potential effects of alteration in the fluid boundary conditions of the femoral head, a decompression procedure was performed. The stiffness of femoral heads from normal adult mongrel dogs was measured after the heads were subjected to a physiologic mechanical load. When the fluid boundary conditions were altered by drilling the femoral neck, femoral head stiffness was reduced by more than 30% (p = 0.045). Refilling of the femoral specimen with saline restored the stiffness to the baseline value. These observations demonstrate that in vitro changes of fluid boundary conditions can alter the mechanical integrity of the femoral head. Alteration in osseous fluid boundary conditions in vivo could affect joint integrity and be of pathogenetic significance in joint disease.