The pathomechanism of human coxarthrosis

Pattern of advancement in the zone of calcified cartilage detected in hand osteoarthritis

OBJECTIVE

Using high definition macroradiography the pattern of advancement in the zone of calcified cartilage (termed a ZCC step) was detected in osteoarthritic hand joints of patients and compared to the joint space width (JSW) measurement.

DESIGN

X5 macroradiographs were obtained of the osteoarthritic hands of 44 patients at baseline and at 18 months. The incidence of ZCC steps, identified as an advancement in the mineralized cartilage front into articular cartilage, was assessed at each articular surface. JSW was measured and was used to determine the difference in JSW between hands and groups of joints with and without ZCC steps at both X-ray visits.

RESULTS

ZCC steps were found at the convex articular surfaces in only 42 (48%) hand joints in 28 (64%) patients. Here, ZCC steps were present in 36 joints in the non-dominant hand, compared with 30 joints in the dominant hand. In the former, they were present in 22 DIP, six PIP and eight MCP joints and in 12 DIP, eight PIP and 10 MCP joints in the dominant hand. By 18 months, new ZCC steps had formed in 15 hands with and 17 hands without previous ZCC steps. At both X-ray visits no statistically significant difference in JSW was found between the hands and joint groups with and without ZCC steps.

CONCLUSION

In patients with ZCC steps, the pattern of distribution in the hand appeared to be related to that due to vascular changes, such as hyperlipidaemia, rather than to that associated with mechanical forces.

Rotational and translational loading of the temporomandibular joint

Following an introduction to the functional properties of a three-dimensional instantaneous helical axis pertaining to circular (rotatory) and linear (translatory) motions of the mandible, this feasibility study applied the concept of a mandibular average finite helical axis to the maneuver of cyclic opening and closing of the mouth in three healthy subjects. Through the accelerations and decelerations of a mandibular incisor point (instead of a mandibular condylar point) as well as the laws of physics, the kinetic reaction forces and reaction pressures in the upper and lower cavities of the temporomandibular joint (TMJ) were estimated over opening-closing distances of five and ten mm from centric occlusion. The translatory reaction pressures in the upper TMJ cavity (17-29 mm Hg) exceeded the rotatory reaction pressures in the lower TMJ cavity (5-12 mm Hg). The estimated reaction pressures were in close agreement with synovial fluid pressures measured in vivo in the TMJ of humans and pigs, and the biologic significance of frequent and/or prolonged increased TMJ hydrostatic pressures is discussed.

Advancement in the zone of calcified cartilage in osteoarthritic hands of patients detected by high definition macroradiography

OBJECTIVE

High definition macroradiography permits the advancement in the zone of calcified cartilage (described as a ZCC step) to be detected in osteoarthritic (OA) hand joints of patients. The pattern of their incidence and distribution was determined and compared to the joint space width (JSW) measurement.

DESIGN

Macroradiographs, x5 magnification, were obtained of the OA hands of 44 patients at baseline and at 18 months. The incidence of ZCC steps, identified as an advancement in the mineralized cartilage front into articular cartilage, was assessed at each articular surface. JSW was measured and was used to determine the difference in JSW between hands and groups of joints with and without ZCC steps at both X-ray visits.

RESULTS

ZCC steps were only found at the convex articular surfaces in 42 (48%) of hand joints in 28 (64%) patients. Here, ZCC steps were present in 36 joints in the non-dominant hand compared to 30 joints in the dominant hand. In the former, they were present in 22 DIP, six PIP and eight MCP joints and in 12 DIP, 8 PIP and 10 MCP joints in the dominant hand. By 18 months new ZCC steps had formed in 15 hands with and 17 hands without previous ZCC steps. At both X-ray visits no statistically significant difference in JSW was found between the hands and joint groups with and without ZCC steps.

CONCLUSION

Although ZCC steps and JSW loss were greater at the PIP joints, supporting a mechanical hypothesis for ZCC formation, their presence in joints, where JSW was larger, and their greater incidence in the non-dominant PIP joints, suggest that factors associated with vascular changes, related to subchondral bone remodeling, are responsible.¿copy¿

Intraosseous pressure in Kienböck's disease

Intraosseous pressure was measured in the lunate of 10 patients undergoing surgery for Kienböck's disease. Using the styloid process of the radius and the capitate as reference points of bone pressure, I found a stasis rather than arterial insufficiency in the lunate. This pattern was observed regardless of the stage of the disease according to Ståhl and regardless of the finding by technetium TC 99m-methylene diphosphonate scintigraphy. The significance of this finding is still unknown but questions the current concept that Kienböck's disease is caused by arterial insufficiency, because these results imply an interruption of the blood flow as a result of venous congestion.

Partial pressures of oxygen and carbon dioxide in bone and their correlation with bone-blood flow: effect of decreased arterial supply and venous congestion on intraosseous oxygen and carbon dioxide in an animal model

Pathological changes in bone have been related to a preceding impediment of the arterial or venous bone circulation and hypoxia. In this study, we analyzed the feasibility of mass spectrometry in measuring intraosseous oxygen and carbon dioxide. The partial pressures were also measured in intraosseous blood samples, and blood flow in bone was measured with the radioactive microspheres technique. The average partial pressure of oxygen in the lateral femoral condyle was 34 +/- 1.6 mm Hg when measured in intraosseous blood samples and 36.3 +/- 2.3 mm Hg when measured with the on-line mass spectrometer, with significant correlation between the methods. The absolute value of the partial pressure of carbon dioxide measured in situ with mass spectrometry was correlated with the value in the withdrawn blood. There was no significant difference in partial pressures of oxygen and carbon dioxide between the two sides or between repetitive measurements. Arterial occlusion resulted in severe hypoxia, whereas more moderate changes followed venous occlusion.

Arteriovenous shunting is not associated with venous congestion in bone. Knee tamponade studied with 15-microns and 50-microns microspheres in immature dogs

Blood flow in the hind-limb bones of 8 immature labrador dogs with unilateral knee joint tamponade at 75 percent of the mean arterial pressure was measured with 15-microns and 50-microns microspheres to determine whether or not arteriovenous shunting occurs in bone with venous congestion caused by increased outflow resistance. The intraosseous pressure was 43 percent of the mean arterial pressure in the experimental distal femoral epiphysis versus 14 percent in the control knee (P less than 0.001). No pressure changes were found in the distal femoral metaphysis. Regional blood flow with 15-microns microspheres decreased centrally in the distal femoral epiphysis and increased centrally in the proximal tibial epiphysis. Metaphyseal blood flow was largely unchanged. A net shift in the preferred embolization site of 50-microns microspheres relative to that of 15-microns microspheres from central to peripheral regions occurred within both juxtaarticular epiphyses, indicating arteriolar vasodilation, but the relation between the uptake of the two microsphere sizes was unchanged when the epiphyses and other bony flow compartments were viewed in toto. The result speaks against the hypothesis of arteriovenous shunting in intraosseous hypertension.

Oxygen consumption, diffusing capacity and blood flow of the synovial membrane in osteoarthritic rabbit knee joints

In osteoarthritis the changes of the synovial membrane may seriously alter the oxygen transfer characteristics from the capillaries of the membrane to the synovial fluid and hence impede or deprive the joint cartilage of its sole source of oxygen. In the present study we have estimated the blood flow (Q), diffusing capacity (DO2) and oxygen consumption (VO2) of the synovial membrane in the chronic non effusive stage of experimental osteoarthritis. In 14 osteoarthritic knee joints we found a statistically significant increase in oxygen consumption, compared to previously reported results from normal joints, whereas the diffusing capacity and the blood flow were unchanged. The implication of this is that the partial pressure difference required to overcome the increased oxygen consumption was increased with a factor 4.3 and that the oxygenation of the joint cartilage was reduced with approx. 30 Torr.

Subchondral bone formation in arthrosis. Polychrome labeling studies in mice

We used polychrome sequential labeling to study the dynamics of subchrondral bone sclerosis during developing arthrosis in knee joints of male STR/1N mice. This technique, using four different colored vital markers, gives detailed information about the site and time of new bone formation in the subchondral bone. In arthrotic joints, we found fluorescent bands arranged excentrically around the marrow cavities always pointing towards the cartilage lesions. The linear separation between the first label and the anatomic surface of the bone marrow cavity varied considerably between the experimental groups. In arthrotic joints, we found bone growth rates 3-4 times greater than in control joints. We also found that the degenerative process in cartilage and subchondral bone was a local phenomenon, because in areas with normal cartilage next to the sclerotic lesions appositional bone growth rates were unaffected.

Diagnosis of aseptic osteonecrosis of the femoral head by percutaneous transtrochanterian needle biopsy

A technique is described whereby aseptic osteonecrosis of the femoral head can be investigated before definite radiological signs do develop. Qualitative and quantitative data are presented supporting the generalisation of this method and its implications are discussed.

Osteoarthritis. Aggravating factors and therapeutic measures

Clinical criteria for diagnosis of osteoarthritis are not yet formally established; at present, diagnosis is usually made through physical and radiologic examination and evaluation of synovial fluid. Severe trauma and possibly repeated microtrauma, excessive activity, inactivity, and obesity are believed to aggravate symptoms. Treatment objectives are to reduce pain and improve, or at least preserve, function. Antiinflammatory agents provide relief for many patients, although gastrointestinal reactions may accompany their use. Antispasmodics may be helpful for pain caused by muscle spasm, and intraarticular injections of depocorticosteroids are useful for inflammation. Agents that provide analgesia are an appropriate part of the therapeutic program. Patients should be taught to protect weakened joints through use of orthotics, strengthening exercises, and proper body movement and posture. A supportive physician who encourages a healthy life-style and positive outlook will see better physical as well as emotional results with these patients.