Atirition Ruptures of Flexor Tendons in Rheumatoid Arthritis Caused by Bony Spurs in the Carpal Tunnel

The term “ attrition “ rupture of tendons was coined by Vaughan-Jackson who, in 1948, reported two cases of rupture of extensor tendons through attrition at the inferior radio-ulnar joint. These ruptures were caused by bony irregularities at the distal end of the ulna. Spontaneous ruptures of flexor tendons in rheumatoid arthritis were fully described by Lame and Vainio in 1955. Pathomechanics of spontaneous tendon ruptures in rheumatoid arthritis-In this disease both flexor and extensor tendons may undergo spontaneous ruptures in five principal ways. 1) Granulomatous rheumatoid tissue invades the tendon along the vincular vessels and in time softens the tendon, which finally ruptures with strain. 2) Occlusion by hypertrophic rheumatoid tissue around the vincular vessels causes localised infarcts in the tendon a few millimetres proximally and distally from the entrance of the vessel. This tendon infarct may in time behave like an intratendinous nodule (Vaughan-Jackson 1968). 3) Rupture may occur from attrition over bony spurs (Vaughan-Jackson 1948, 1962). 4) Spontaneous flexor tendon ruptures may be caused by pressure from the carpal ligament on the already weakened tendons (Straub 1959). 5) Tendons may also rupture after local steroid injections (Moberg 1965). According to Henderson and Lipscomb (1961) both degeneration by tenosynovitis and fraying of the tendons over adjacent bony structures cause attrition of the tendon. Linscheid and Lipscomb (1962) found that in rheumatoid arthritis the flexor pollicis longus tendon ruptures near its insertion into the distal phalanx. They also noted ruptures of the tendon under the annular ligament or near the point where the tendon joins the muscle. They thought that spontaneous tendon ruptures in rheumatoid arthritis are the result of mechanical attrition of a tendon already weakened by tenosynovial inflammation. Fowler (1963) believed that rupture by attrition of flexor tendons occurred in the vicinity of the hook of the hamate bone and the trapezium. Lipscomb (1965) found that flexor tendons ruptured in the carpal tunnel or within the finger area-that is, in the region where the tendon is surrounded by synovial membrane. James (1949) presented a case of flexor tendon rupture caused by a sharp bony spicule in a case of Kienb#{246}ck’s disease; the bony spicule had pierced the floor of the carpal tunnel. The case was not regarded as one of rheumatoid arthritis. We have found no reference in the literature to attrition ruptures of flexor tendons from bony prominences or spurs in the carpal tunnel in rheumatoid arthritis, though Moberg (1965) and Rasmussen and Sneppen (1967) reported both extensor and flexor tendon ruptures. Distribution of tendon ruptures-The commonest tendon ruptures in patients with rheumatoid arthritis occur in the extensor tendon at the ulnar border of the dorsal aspect of the hand. Next in order of frequency is rupture of the extensor pollicis longus tendon, and least common are those of the flexor tendons. Moberg (1965) reported thirteen cases ofspontaneous tendon ruptures in rheumatoid arthritis treated by operation : in seven the rupture was of the flexor pollicis longus and in two the profundus tendon of the index finger was affected. In the remaining four cases rupture was of extensor tendons. According to Rasmussen and Sneppen (1967) extensor tendons are ruptured more often than flexor tendons. In their series of forty-three cases of tendon rupture, extensor tendons were affected in thirty-six, flexor pollicis longus in three, the profundus tendon of the index