Division of Community Health, Faculty of Medicine, Memorial University of Newfoundland, 300 Prince Philip Drive, St John's, Newfoundland, A1B 3V6, Canada
SIR, We report two siblings with familiar articular hypermobility (FAH) and lone osteoarthritis (OA), in the propositus in the scapho-trapezio-trapezoid (STT) joints and in his sister in the scapho-trapezial (ST) joints. The role of occupational and recreational mechanical stresses in the genesis of this uncommon presentation of OA is examined [1, 2].
The propositus, a 55-yr-old Caucasian male (patient 1), was seen because of bilateral wrist pain. He recalled, as a youth, being able to appose the thumbs to the forearms, placing the palms on the floor with the knees fully extended and placing the hands behind the back and reaching up to the neck. At the age of 19 yr he started working in the stock room of a plumbing company, which involved lifting and moving heavy merchandise, and 10 yr later changing jobs, becoming a home heating mechanic. The job included moving and servicing 200-gallon fuel tanks. This involved reliance on wrenches and screwdrivers and the use of vibration tools to drill holes for pipes. After about 20 yr in this job he began to notice that the use of hand tools would bring on pain on the radial side of both wrists (the right hand was dominant), and he was no longer able to appose the thumbs to the forearms. With the passage of time, the pain became more intense and was precipitated by lesser amounts of exertion. He began to resort to trick manoeuvres to accomplish some of the tasks that ordinarily he would do without thinking; but after another 3 yr the use of tools caused so much discomfort that he was no longer able to work. Over the next 2 yr the duration of pain after physical activity lengthened until it was present continuously and was worse at change of weather. He also began to notice weakness in the hands and pain in the right shoulder on mobilization. He was referred to a neurologist because of suspected carpal tunnel syndrome. The neuromuscular examination was normal apart from the small bulk of his hand muscles. Past history revealed a hiatus hernia and reflux oesophagitis developing at the age of 22 yr and a right mastoidectomy at 31 yr. Around the age of 30 yr he twisted one knee and 10 yr later the other, each requiring a medial menisectomy a few days after the injury. There was no history of easy bruisability.
On examination his height was 178 cm and his weight 75 kg. The hard palate was somewhat narrowed but otherwise there were no dysmorphic features. The skin was not lax. The examination of the cardiac and ophthalmological systems was unremarkable. The ranges of movement (ROM) of the joints are recorded in Table 1.
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On examination, her height was 160 cm and her weight 55 kg. There was a high arched palate but no other dysmorphic features. The skin was not hyperdistensible. The examination of the cardiac and ophthalmological systems was unremarkable apart from slight myopia. The joint ROMs are recorded in Table 1.
Complete blood counts, ESR and tests for rheumatoid factor and antinuclear antibody were normal or negative. Nerve conduction studies were normal apart from a slight increase in palm-to-wrist latency on the right side. A skin biopsy examined for types I and III procollagen by protein electrophoresis revealed no abnormalities. Radiographs of the wrists showed narrowing of the ST joints with subchondral sclerosis, which was more advanced in the left wrist (Fig. 1b). Stress views in dorsiflexion and palmar flexion showed hypermobility of the lunatecapitate joints. The left scapholunate joint was widened and appeared unstable. MRI of both wrists showed multiple subchondral cysts in the carpals and some fluid in the right midcarpal and radiocarpal joints.
Other members of the family were contacted and interrogated concerning occupation, recreational activities and musculoskeletal complaints and asked to submit to screening for the nine-point Beighton scoring system for articular hypermobility [3]. Those whose joints were not examined were asked if they could now or had ever been able to perform the second and fifth diagnostic criteria of the Beighton system. Final hypermobility scores were estimated by summing current and historic criteria without duplication (Fig. 2). Polyarticular and pauciarticular hypermobility was common, particularly in the third generation. All of the sibship apart from the propositus were engaged in sedentary activities. The second subject (patient 2) and one niece were the only piano players, but the subjects' four brothers have been active in karate for years. Apart from the subjects and their mother, who had OA in a knee and in several interfacet joints, no participants had musculoskeletal complaints.
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Lone ST/STT OA is uncommon [1, 2] and occupationally induced OA of the upper extremities is said to be rare [7], but one of the authors (JRM) has observed isolated STT OA in two heavy equipment operators who also were loggers using chainsaws. Neither gave a history of hypermobility. In cases like these, there is no consensus on whether the degenerative process is the result of vibration-induced damage to the articular cartilage, heavy joint loading or both [7]. If heavy occupational stresses can cause STT OA in structurally normal joints, it is easy to imagine that lax or unstable joints would be more vulnerable to such stresses. Carpal instability (malalignment of one or more carpal bones in relation to each other or the radius) has been observed in generalized lax ligaments [8, 9]. Furthermore, STT OA has been associated with carpal instability [10, 11]. Some carpal instability was still present in the second subject and was perhaps present in both subjects earlier in life to a more marked degree, as joint ROM may diminish with age [12].
Considering how common FAH is [13], as this family shows, usually it is well tolerated. Few cases develop secondary OA and then, presumably, only under exceptional circumstances, such as unusual occupational and recreational mechanical stresses acting on susceptible joints. In the case of the propositus, there would have to be a strong suspicion that it was the exceptional demands of his occupation which were responsible for his OA. In the case of his affected sister, however, none of her activities, except possibly piano playing, stand out as a major determinant for her arthropathy. The selective involvement of only the ST/STT joints is puzzling but approximately 95% of wrist OA is said to be periscaphoid [14]. There would be a practical point in the early recognition of FAH if it provided an opportunity to give guidance on career and recreational choices [15], but the uncertainties surrounding the circumstances under which OA may develop in FAH impose limitations on the ability to do so. Still, there may be situations where categorical warnings may be justified. The hypermobile son-in-law of the propositus (Fig. 2, III:12) is a case in point. As his father-in-law used to be, he is a home heating mechanic, but so far has experienced no discomfort in the performance of his tasks.
We are indebted to Professor M. Byers, University of Washington, for the electrophoretic studies of the skin biopsy of patient 2, to Dr N. Turner for bringing the propositus to our attention, to Ms K. Hodgkinson for providing the pedigree, and to the family for their cordial participation in the study.
Notes
Correspondence to: J. R. Martin.
References
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