Flexor Carpi Ulnaris Tendon Injection

Indications and Clinical Considerations

Flexor carpi ulnaris tendinitis is being seen with increasing frequency in clinical practice as golf and racquet sports have increased in popularity. The flexor carpi ulnaris tendon is susceptible to developing tendinitis at the distal portion. It is subject to repetitive motion that may result in microtrauma, which heals poorly because of the tendon’s avascular nature. Exercise and repetitive trauma are often implicated as the inciting factors of acute flexor carpi ulnaris tendinitis, and improper grip of golf clubs and tennis racquets as well as the prolonged use of a heavy hammer are common inciting causes. Tendinitis of the flexor carpi ulnaris tendon frequently coexists with bursitis, creating additional pain and functional disability. Calcium deposition around the tendon may occur if the inflammation continues, making subsequent treatment more difficult ( Fig. 79.1 ). Continued trauma to the inflamed tendon may ultimately result in tendon rupture.

The onset of flexor carpi ulnaris tendinitis is usually acute, occurring after overuse or misuse of the wrist joint. Inciting factors may include activities such as playing tennis or golf and prolonged use of a heavy hammer. Injuries ranging from partial to complete tears of the tendon can occur when the distal tendon sustains direct trauma while the wrist is in full radial deviation under load or when the wrist is forced into full radial deviation while under load. The pain of flexor carpi ulnaris tendinitis is constant and severe and is localized in the dorsoulnar aspect of the wrist. Significant sleep disturbance is often reported. Patients with flexor carpi ulnaris tendinitis will exhibit pain with resisted radial deviation of the wrist. A creaking or grating may be palpated when passively radially deviating the wrist. As mentioned, the chronically inflamed flexor carpi ulnaris tendon may suddenly rupture with stress or during vigorous injection procedures when inadvertent injection into the substance of the tendon occurs. Plain radiographs and magnetic resonance scanning are indicated for all patients with radial-sided wrist pain. Ultrasound imaging may also be useful in further delineating the cause of the patient’s wrist pain and functional disability.

On the basis of the patient’s clinical presentation, additional testing, including complete blood count, sedimentation rate, and antinuclear antibody testing, may be indicated. Magnetic resonance imaging and ultrasound imaging of the wrist are indicated if tendon rupture is suspected and to further confirm the diagnosis ( Fig. 79.2 ). Radionuclide bone scanning is useful to identify stress fractures of the wrist not seen on plain radiographs.

Clinically Relevant Anatomy

The flexor carpi ulnaris muscle is located in the forearm. Its primary action is to flex and adduct the wrist. The muscle has two heads, and their origins are at the medial epicondyle of the humerus and the medial margin of the olecranon process of the ulna. These heads are connected by a tendinous arch. Beneath this arch pass the ulnar nerve and ulnar artery. The flexor carpi ulnaris muscle traverses the forearm and enters Guyon canal adjacent to the ulnar nerve to insert on the pisiform bone and has secondary insertions via ligaments to the hamate and fifth metatarsal ( Fig. 79.3 ). The muscle also has secondary insertions on the third metacarpal and the tuberosity of the trapezium. The flexor carpi ulnaris muscle is innervated by the median nerve and receives its blood supply from the ulnar artery.