EXTENDED REPORT

Idiopathic osteoarthritis and contracture: causal implications

P Jones¹, C J Alexander², J Stewart³, N Lynskey¹

¹ Department of Rheumatology, Queen Elizabeth Hospital, Rotorua, New Zealand
² Department of Anatomy with Radiology, School of Medicine, University of Auckland, Auckland, New Zealand
³ Biostatistics Unit, Department of Community Health, University of Auckland

Correspondence to:
Correspondence to:
Dr Peter Jones
Associate Professor, Department of Rheumatology, Queen Elizabeth Hospital, PO Box 1342, Whakaue Street, Rotorua, New Zealand

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.

Abbreviations: DIP, distal interphalangeal joint; MCP, metacarpo-phalangeal joint; PIP, proximal interphalangeal joint

Keywords: contracture; osteoarthritis

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