TREATMENT AND DIAGNOSIS

FINGER PULLEY INJURIES IN ROCK CLIMBING

By Marie Brookes MCSP and Dr Mike Brookes BMedSci

INTRODUCTION Rock climbing has seen a massive growth in popularity over the last twenty years. A progressive improvement with safety equipment and the development of all weather climbing walls has seen a shift in the injury patterns associated with climb- ing. Traditional rock climbing was associat- ed with fractures, mostly of the lower limbs, due to falls. Lower limb injury is now relatively uncommon compared to upper limb injury. The change in injury pattern is thought to be associated with the increase in difficulty of climbs, especially climbing walls, where routes are often overhanging, requiring dynamic moves and large strains on the hands. Unfortunately, evolution has meant that the human hands are no longer designed to be weight-bearing structures, and repetitive climbing is causing a large number of overuse-type injuries to the fin- gers. A survey at a rock climbing meeting showed that 50% of a reported 115 injuries involved the hand and wrist, with the majority involving the finger tendon pul- leys (1,2). Another study suggests that 30% of finger injuries in climbing are due to tendon pulley ruptures (3).

ANATOMY AND PHYSIOLOGY The tendons of flexor digitalis superficialis and profundus are held against the pha- langes by a fibrous sheath. This sheath is reinforced along its length by a thick fibrous ring and cruciform pulleys. There are five ring-shaped pulleys (A1-5) and three cruciform pulleys (C1-3). The pulleys are designed to keep the tendon against the bone and to prevent bow-stringing.

BIOMECHANICS OF INJURY Different grips used in climbing provoke

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different forces on the tendons and the pulleys. The crimp grip (see Box 1) is the most common grip used in climbing. Unfortunately, this position also puts the finger pulleys at greatest risk of injury. The crimp grip requires approximately 90 degrees of flexion at the proximal inter- phalangeal (PIP) joint, producing a resul- tant force at right angles to the A2 pulley. If the weight of the body is suddenly loaded onto the A2 pulley, the resultant force (in the region of 450 N) is enough to tear the pulley (4). Chronic overuse of the tendons also predisposes the pulley to rup- ture when suddenly shock loaded.

DIAGNOSIS Climbers often report characteristic symp- toms of acute onset of pain associated with sudden forceful loading of the fingers and a ‘popping’ noise or sensation (5). There is often swelling around the middle or proximal phalanx. The bowstring appear- ance used to be considered indicative of a pulley rupture. However, current consensus

is that the bowstring phenomenon is only visible in high grade injuries (multiple pul- ley ruptures) (5,6).

An algorithm developed by Schoffl (5) (Fig.1) suggests using radiographs to exclude the presence of bony injury before ultrasound examination. High-frequency ultrasound allows good visualisation of the structure of superficial tendons and surrounding tissue (7), and is non-inva- sive, non-irradiating and considerably cheaper than MRI and CT. The added ben- efit is that ultrasound imaging is dynam- ic. Klauser et al give the sensitivity of ultrasound for depiction of finger pulley injuries as 98% and specificity as 100% (3). MRI remains the gold standard imag- ing modality and should be used if the ultrasound diagnosis is unclear.

TREATMENT OPTIONS A pulley-injury grading score system has been developed by Schoffl et al in 2003. This grades pulley injuries on a score of 1-

BOX 1: RELATIONSHIP BETWEEN GRIP TYPE AND FORCE VECTORS AT THE PIP JOINT

GRIP Open

FINGER POSITION PIPJ

FORCE VECTOR AT PIPJ

10N 10N 10N

= resultant force on A2 pulley

Crimp 10N PIPJ 10N 14N