Sunday, May 15, 2011

Rock Climbers and Pulleys

Photo by groundzero

"There are only 3 real sports: bull-fighting, car racing and mountain climbing. All the others are mere games."— Ernest Hemingway

Critical to mountain and rock climbing are extraordinarily strong fingers, which can find small cracks in the rock, and propel the ardent climber skyward. Flexion of the fingers is generated by the flexor digitorum profundus and flexor digitorum superficialis (sublimus) tendons, which attach to the distal phalanx and middle phalanx, respectively. These tendons are held close to the underlying bone by five annular or "A" pulleys, that prevent bowstringing during flexion:

Figure courtesy of Nicros

Of the five annular pulleys, the A2 pulley is the most commonly injured. Injuries can vary from partial tears to complete tears. Rock climbers are particularly prone to pulley injuries, due to the tremendous load placed on the pulleys when the climber grips tightly, and levers himself upward. The traditional rock climbing grip ("crimp position"), which involves hyperflexion of the proximal interphalangeal (PIP) joint and hyperextension of the distal interphalangeal, puts high stress on these pulley structures. Tears can develop over time, or be acute in nature.

Pulley tears can be imaged using MRI or ultrasound. On ultrasound, a partially torn pulley is thickened and hypoechoic (Martinoli et al., Skel Rad 29, 387-291, 2000). On both ultrasound and MRI, complete pulley tears will manifest with an increased distance between the flexor tendon and the underlying bone, since the pulley is no longer holding the flexor tendon in place, with this sign accentuated during finger flexion. High resolution imaging will easily identify the normal A2 and A4 pulleys, allowing direct detection of pulley injuries.

In this case, a 36 avid rock climber complained of a painful ring finger, with pain maximal at the base of the finger. He began to notice the pain after a day of climbing, six weeks before seeking medical attention. Physical examination revealed swelling at the base of finger, but no bowstringing of the tendons. The patient was referred for an MRI to assess the A2 pulley, and to exclude a flexor tendon sheath ganglion cyst.

An axial intermediate image reveals diffuse thickening of the A2 pulley of the ring finger (red arrow). The pulley remains continuous, without focal discontinuity. The normal middle finger A2 pulley (green arrow) is also seen.

Here is the corresponding axial T2 fatsat image:

A coronal intermediate image depicts the abnormally thickened A2 pulley:

Sagittal images of the ring finger were also performed:

(A) Gradient echo and (B) T2 fatsat images show the abnormally thickened A2 pulley, along with local soft tissue edema. In normal patients, the A2 pulley cannot be seen on sagittal images, since it is a diaphanous structure tightly applied to the underlying flexor tendons.

MRI yields the diagnosis of a partial, interstitial tear of the A2 pulley with reactive local soft tissue inflammation, and allows proper treatment.

Treatment of partial pulley tears is usually conservative, although complete annular pulley ruptures may be addressed surgically. Rock climbers are tough individuals, and some of them will attempt to "climb through" partial pulley tears, but rest is the recommended approach.

Vic David MD