Osteoarthritis revisited

Idiopathic osteoarthritis and contracture: causal implications

OBJECTIVE

To use the known association of idiopathic osteoarthritis with contracture as a means of searching for its cause. There are currently two theories concerning this association, one assuming that the contracture is a consequence of the osteoarthritis and the other that it precedes and causes the osteoarthritis. This study tested both theories.

METHODS

Flexion ranges in the 12 finger joints were obtained by goniometric measurement in two samples of normal female subjects, one group with a mean age of 22 years (25 subjects) and one with a mean age of 45 years (50 subjects). The results were compared with the known regional prevalence of osteoarthritis in the finger joints of women.

RESULTS

The older group showed evidence of reduced flexion range consistent with development of contracture in the extensor mechanism of the fingers. The distribution of the contracture showed a strong negative correlation with the regional prevalence of osteoarthritis.

CONCLUSIONS

An early dorsal contracture develops in the fingers of normal subjects, but it is neither a consequence of nor the cause of digital osteoarthritis. The most parsimonious explanation for the association is that both contracture and idiopathic osteoarthritis are independent consequences of failure to use the full movement range. If this hypothesis is correct, the disease could be preventable.

Rapid destructive osteo-arthritis of the hip

A case of an unusual destructive hip osteo-arthropathy with a plain-film record of rapid joint destruction is reported. In the absence of any laboratory or pathological support for other pathology this is thought to be an uncommon example of erosive or inflammatory osteo-arthritis in a large joint.

Intra-articular osteoid osteoma

Osteoid osteomas located within the capsule of a joint are uncommon and present challenging diagnostic difficulties. Twelve patients with an intra-articular osteoid osteoma were studied retrospectively to determine the spectrum of clinical and radiological findings. The features differ significantly from the well known classical hallmarks of the extra-articular lesion. The symptoms are non-specific with pain similar to other common joint disorders and the response to salicylate less precise. On plain radiography intra-articular lesions are difficult to identify, lacking the florid periosteal new bone and intense perifocal sclerotic reaction. A detectable focal lesion is commonly absent with considerable delay between the onset of symptoms and radiological detection of the tumour nidus. Bone scintigraphy and computed tomography (CT) are essential for an accurate and early diagnosis. These imaging techniques reveal abnormalities in bone and cartilage growth, new bone formation and sclerosis distant from the tumour on either side of the joint, and disruption of the articular surface. Radiological follow up after surgery shows that these changes can be reversible, especially when the diagnosis is made early.

Erosive osteoarthritis: is it a separate disease entity?

Erosive osteoarthritis (EOA) characteristically involves the hands of middle-aged women. The diagnosis is essentially radiological and depends upon the presence of articular surface erosions. This study investigates whether this radiological feature is a marker of a specific clinical entity. From a series of 500 consecutive patients attending a rheumatology clinic with symptomatic limb joint osteoarthritis, 24 were identified by radiological criteria to have EOA. These were age-sex matched with 24 patients from the same series who presented with osteoarthritis of the hand. Those with EOA had nearly twice as many radiographically abnormal joints in the hands as the controls (274: 144). This was almost entirely due to an increase in distal (134: 68) and proximal (79: 24) interphalangeal joint involvement, 71% of which were erosive. Erosions were found apart from the hands in both elbows of one patient with EOA. Otherwise only minor differences were present between the two groups in terms of distribution and incidence of osteoarthritic changes. There were no distinguishing serological or other clinical differences. This study has demonstrated that erosions in EOA are associated with more severe hand disease but are not apparently a marker of a separate disease entity. EOA appears to be an aggressive acute form of hand osteoarthritis and may represent the hand equivalent of similar forms of osteoarthritis in the shoulder, hip and knee.