Diagnostic Imaging Europe
October 2003
Cover Story
Imaging illuminates climbing injuries
Rock climbers put immense stress on ligaments, tendons, and joint capsules, but careful use of ultrasound can help them
By: Andrea Klauser, M.D.
Climbing is a rapidly expanding sport, no longer the domain of a small number of elite rock scalers. Improved safety of climbing equipment, coupled with more artificial climbing walls and indoor rock climbing facilities, has helped attract an increasing number of recreational climbers. Media coverage on television and the Internet has further sparked public interest.1-5
Patients with injuries related to climbing now present more frequently. Better recognition of injury patterns and awareness of the role imaging can play will help improve patient management.
The upper extremities are the major site of injuries and overuse syndromes in sport climbing. The entire body weight is often suspended on one or two fingerholds, especially in overhanging wall climbs. About 75% of sport climbers present with upper extremity overuse syndromes or injuries. Approximately 60% of injuries involve the fingers or wrist, while the remaining 40% are equally divided between the elbow and the shoulder.6,7 Complaints primarily relate to ligaments, tendons, and joint capsules, which adapt more slowly to the stresses than muscle tissue.
Acute injuries often involve finger flexor tendons and finger flexor pulleys. MRI,8,9 CT,10 and ultrasound11-14 have all been used to assess finger pulley injuries. Ultrasound is more readily available and less expensive than either CT or MRI.
Chronic overuse syndromes present mainly as swelling and pain in the finger joints and as epicondylitis in the elbow. Both the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints can be injured, although the PIP joint is involved most often. A common cause of injury is the so-called crimp grip on small handholds, which involves hyperextension of the DIP joint with hyperflexion of the PIP joint.
Physical examination is used first to differentiate between overuse and traumatic injury. But clinical diagnosis can be limited by pain and soft-tissue swelling. Early symptoms of overuse include morning stiffness and fine motor deficits, while chronic signs include capsular swelling and pain on pressure.
Swelling of the finger joints can be irreversible in climbers who participate in the sport for a long time. MRI and ultrasound will reveal adaptive hypertrophy of collateral ligaments and chronic joint effusions (Figure 1). X-rays can show early degenerative changes consisting of small lateral osteophytes and joint area enlargement.15,16
Shear forces between the tendon and its sheath can cause flexor tenosynovitis, especially during the crimp grip. Tendons are especially prone to overuse, because their adaptation processes are much slower. Clinical findings include tenderness and swelling over the volar base of the proximal phalanges and the palm. Ultrasound shows a focal distended hypoechoic area between the tendon and its sheath. The sheath can be thickened and a color Doppler examination may reveal hyperemia (Figure 2).
Isolated flexor tenosynovitis is seen on MRI as a circumscribed thickening of the tendon sheath with increased signal intensity, owing to a high fluid content (Figure 3). The flexor tendon is also seen lying close to the phalanx, without increased tendon-phalanx distance.
Localized pain in the middle phalanx is a highly specific indicator of insertion tendinitis of the flexor digitorum superficialis tendon. This is caused by special training programs that lead to local overuse. Patients with overuse injuries should reduce the amount of climbing they are doing and make appropriate changes to their climbing style and training schedule. Nonsteroidal anti-inflammatory medications and rehabilitation programs are sometimes necessary.
CLIMBER'S FINGER
The crimp grip can produce very high forces on the A2 pulley located at the base of the proximal phalanx.17 A2 pulley rupture, also known as climber's finger, is the most common injury among climbers and can be found in 50% to 69% of extreme rock climbers. A4 pulley ruptures are found with increasing frequency (Figure 4),9 possibly as a result of the change to higher climbing levels with smaller grips, where an extension of the metacarpophalangeal (MCP) and PIP joint and flexion of the DIP to 90 degrees to 120 degrees is often used by the climber. The ring and middle fingers are the most common sites for this injury.
Climbers typically report an audible "pop" at the time of injury at the proximal phalanx. Severe pain is usually followed by swelling over the volar aspect of the proximal phalanx. This can persist for a few months and makes clinical diagnosis difficult. With a rupture of the A2 pulley, the flexor tendon is bowstringed to a varying extent across the proximal phalanx during finger flexion against resistance. Detectable bowstringing usually provides a clear diagnosis, but this is predominantly evident only in complete rupture of all three pulleys (A2, A3, and A4). Isolated rupture of the A2 pulley can be present with pain and swelling but without clinically evident tendon bowstringing.
Ultrasound is an attractive approach for direct visualization of joint, tendon, and soft-tissue injuries of the hand. High-resolution ultrasound allows intact pulleys to be viewed directly as well.18 Due to indirect imaging criteria and direct measurement of the tendon-phalanx distance, ultrasound has high sensitivity in characterizating pulley rupture. Evaluation with dynamic ultrasound can distinguish among incomplete, complete, and combined pulley rupture.11
An indirect but reliable sign of pulley injury on MRI is a fluid-rich space with high signal intensity between the phalanx and tendon. This increased tendon-phalanx space can help differentiate pulley tears from isolated flexor tenosynovitis.
Ultrasound of the hand is performed with the patient in the supine position, moving from the head of the metacarpals to the distal phalanges in both transverse and longitudinal planes. A gel standoff pad may improve penetration of the beam in high-frequency ultrasound. This pad can be especially helpful for dynamic ultrasound examinations, which are mandatory for an exact measurement.
Dynamic measurements are performed on extended fingers that start at rest and then are forced into flexion against the fingertips (approximately 10 degrees in the DIP joint and 40 degrees in the PIP, with extension of the MCP joint).
Measurements of tendon-phalanx distance to diagnose tendon bowstringing are performed at the base of the proximal phalanx for A2 pulley rupture and at the middle of the intermediate phalanx for the A4 pulley. Changes in TP distance with forced flexion can be used as signs of complete or incomplete rupture:
Therapy options range from surgical repair to conservative treatments, as determined by the amount of bowstringing and the degree of pulley injury.9 A missed diagnosis of pulley rupture can lead to persistent pain, abstinence from climbing, and finally restricted range of motion.
Collateral ligament injury of the PIP joint is common. Collateral ligaments in finger joints can be strained or torn when climbers slip while one of their fingers is fixed on a small hold. Clinical examination excludes instability of the joint, and x-ray can show a bony extraction. Ultrasound shows joint effusions and thickened capsular structures. Chronic joint instability may make surgical intervention necessary to correct severe instability.
Ultrasound can also enable early and exact diagnosis of other climbing-related overuse syndromes, when clinical diagnosis is difficult.19 Differential diagnosis in PIP joint swelling includes overuse in terms of focal tenovaginitis, pulley hypertrophy, ganglion cysts, and increased joint fluid. In addition, extensor hood injuries, flexor unit strains, tendinosis at the insertion of flexor digitorum profundus, and superficialis can be demonstrated well on ultrasound.
LARGER JOINTS
Carpal tunnel syndrome is the most common wrist problem encountered in climbers. Approximately 10% of elite climbers suffer from this complaint.20 Ultrasound and MRI21,22 can reveal thickened cross-sectional areas of the muscle bellies and tendon sheaths of the flexor digitorum profundus and superficialis at the carpal tunnel. Treatment options include conservative management with reduction of training load, nonsteroidal anti-inflammatory agents, and physical therapy, as well as splinting or surgical decompression for severe cases.
Soft-tissue elbow injuries common to climbers include medial and lateral epicondylitis, anterior elbow pain, and triceps tendinitis. The superficial finger flexors, wrist flexors, and the pronator teres muscle insert at the medial epicondyle of the elbow, and medial epicondylitis is a frequent and well-known overuse problem. High stress in climbing leads to insertion tendinitis due to microtrauma. Lateral epicondylitis develops as an overuse syndrome of the wrist and finger extensors and the supinator muscle, which insert on the lateral epicondyle.
Anterior elbow pain, or climber's elbow, is described as tendinitis of the biceps or brachialis muscle. This is caused by repeated flexion and pronation of the elbow, particularly during long traverses on climbing walls. Triceps tendinitis and injuries occur when the arms and elbows are extended to push the body higher. Ultrasound reveals thickened muscle insertion, loss of echogenicity, hyperemia, and a small intratendinous or intraligamentous hypoechoic area (Figure 5).23
Nerve entrapment syndromes are also seen in climbers. These include sulcus nervi ulnaris syndrome and supinator syndrome with compression of the ramus profundus nervi radialis, which can become inflamed and swollen due to excessive climbing.20
Climbers should stretch all forearm muscles in their daily exercise program. Strains of the musculotendinous junction and so-called flexor unit strain are starting to occur more often in climbers. Musculotendinous junction strain is a characteristic pain over the middle and distal third of the forearm. It probably corresponds to strains or tears within the common muscle belly of the flexor digitorum profundus (FDP). Flexor unit strain is used to describe severe pain beginning at the proximal phalanx or distal palm traveling through the flexor system to the insertion at the medial epicondyle. This tends to be caused by using "pocket" type holds.7
Ultrasound provides an early and exact diagnosis in most overuse injuries related to climbing, which is helpful when planning therapeutic strategies. ultrasound information can help climbers modify their technique and exercise habits, and should therefore be used as the primary imaging modality for overuse injuries.
DR. KLAUSER is a staff radiologist at University Hospital Innsbruck in Austria.
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