By W. Ben Kibler, M.D.
Tennis players occasionally hear their bodies making strange sounds on, and sometimes off, the court. These sounds are described as a popping, snapping, or crunching, and are usually associated with movement of a joint. Players may be concerned that these sounds could be evidence of damage to a muscle, tendon, or joint, and that continued play may worsen the condition. There are several guidelines to help you determine whether the sounds are significant for injury.
The major guideline is presence or absence of pain associated with the sound. Painless noise is quite common. The exact cause is unknown, but it probably represents changes in pressure within a joint as it is moved, or sliding of a muscle over a smooth bony prominence. It is common in young tennis players, especially teenage female players. There is no evidence that continued painless popping of joints leads to later joint damage. The most commonly non-painful “noisy” joints are the fingers, neck, knee, and ankle.
Painful noise should be taken more seriously. Cracking, snapping, or crunching that is worse in the morning, after sitting down, or at the beginning of a match, can indicate muscle inflexibility or tendinitis in its early stages, or muscle inflexibility. Painful noise that increases during the day or the match can indicate an injury to a muscle or a joint structure, such as a cartilage or ligament. In any case, a painful noise should be evaluated by a Sports Medicine specialist.
Other important guidelines include the presence of swelling, loss of muscle strength, or a decrease in joint motion. This also indicates the need for further evaluation.
There are several areas in tennis players where painful noise is common:
Shoulder: “Snapping scapula,” a popping or crunching along the inner border of the shoulder blade near the spine, is usually caused by a muscle or flexibility imbalance that may be corrected by exercise. Painful popping or clunking in the shoulder may indicate injury to the labrum, a cartilage-like structure between the bones, or it may represent mild instability of the joint.
Wrist: Several tendons can have a tendency to snap out of their normal positions as the wrist moves during tennis strokes. Many times, the tendons can actually be seen moving in and out of their normal positions.
Hip: The large muscle on the outside of the hipbone commonly slides over the prominence of the bone as the leg is rotated. This is almost always due to inflexibility, and is treated with exercises.
Knee: Knees can be noisy, whether they are injured or not. Most of the time, the crunching and cracking sounds that they make are harmless. Loose fragments in the joint have been known to make noise, but the sharp pain that they sometimes cause make the noise a secondary problem.
Painful noise around the kneecap that is worse with continued use or stooping suggests an abnormality in the normal movement of the kneecap in its groove on the front of the thigh bone, or femur. Possible causes include bone spurs, ligament damage, or muscle imbalance. A painful pop inside the knee joint, caused by twisting or rotating the joint, usually accompanied by joint swelling, indicates an injury to a ligament (most often the anterior cruciate ligament—the ACL) or to a meniscus. These two structures are vitally important to knee function, so early recognition and treatment is important. A meniscus injury involves the crescent-shaped cartilage that is found on both sides of the knee joint. It is a shock absorber and a stabilizer. When meniscus cartilage is torn, it can catch on the end of the femur and occasionally make a clicking sound. The medial meniscus, the one on the inner side of the knee, is the one most often affected.
Ankle: Ruptures of the Achilles tendon at the back of the ankle produce a characteristic pop or crack. These occur as the player starts to sprint or change direction, and the player feels as if they were hit on the ankle by a tennis racket. These most often require surgical repair. The ankle joint itself will painfully pop or crack if the ligaments are loose from repeated ankle sprains, or the tendons on the outside or inside corners of the joint slide out of their normal positions.
In summary, most snaps, crackles, and pops in tennis players are nonpainful, and do not represent any danger with continued use. However, due to the often vigorous nature of tennis play, injuries can occur that cause painful noises. These should be evaluated and treated by a Sports Medicine specialist, to allow the tennis player to return to the courts as soon as possible.