Effectiveness of extensor carpi ulnaris tendon lengthening in treating four patients with tendinopathy

Dear Editor,

Extensor carpi ulnaris (ECU) tendinopathy results from chronic overuse or acute injury and can present clinically as painful subluxation over the distal ulna, stenosis of the tendon sheath due to inflammation, or simply tendinitis. Tendinopathy that does not respond to nonoperative measures is often treated with debridement, transposition of the tendon, or reconstruction of the 6th dorsal compartment. Some of these procedures require postoperative immobilization and a gradual return to full activity (Fram et al., 2018; Ruchelsman and Vitale, 2016; Wolfe et al., 2017). We have treated several cases of ECU tendinopathy with ECU tendon lengthening, a simple procedure that weakens the ECU.

The rationale behind this procedure is that ECU angles medially at the wrist before inserting on the base of the 5th metacarpal. The angle formed becomes more acute with the forearm in supination and the wrist in ulnar deviation. In this position, the tendon is maximally tensioned and is inclined to sublux medially if the sheath that contains it is incompetent. In any forearm position, the ECU remains dorsal and medial to the centre of the wrist and is therefore capable of ulnar deviation and wrist extension. However, the ECU is a powerful extensor only in supination, a position in which gravity alone tends to extend the wrist. The contribution of the ECU to ulnar deviation and extension is mimicked by that of the flexor carpi ulnaris and the extensor carpi radialis brevis, respectively (Brand and Hollister, 1999). Many activities of daily living occur along the dart-thrower’s arc from wrist extension and radial deviation to wrist flexion and ulnar deviation. The ECU may balance those muscles responsible for moving the wrist along the dart thrower’s arc, but does not directly contribute to this motion. As such, for many, the ECU may not be of absolute importance. The flexor carpi radialis is analogous to the ECU in this respect and is often sacrificed for ligament reconstruction of the thumb carpometacarpal joint or as a source of tendon graft. Caution is advised. ECU mediated extension and ulnar deviation may be important to highly competitive racquet athletes and the like. This same group may rely on the ECU for subtle balancing of forces at the wrist. An intact ECU tendon and ECU sheath also help to stabilize the ulna, which may be of particular importance in patients with rheumatoid wrist deformity.

Between 2009 and 2015, the senior author performed ECU tendon lengthening procedures in four patients. Three of the four patients complained of an insidious onset of ulnar-sided wrist pain, and one described an acute injury from a forehand tennis shot. This pain was described as tenderness along the ECU sheath in three patients and painful subluxation with forearm rotation and ulnar deviation in one patient. Three of the patients were male, and the average age at the time of surgery was 38. Conservative treatment prior to surgery with splinting and cortisone injections failed in all cases. Three of the surgeries were performed with local anaesthesia only. In each case, a longitudinal incision was made over the dorsoulnar distal forearm with the forearm in pronation. The ECU tendon was identified just proximal to the extensor retinaculum, the 6th dorsal compartment was opened, and the tendon was step-cut to enable Z-lengthening of approximately 2 cm. The tendon ends were sutured side-to-side with non-absorbable suture (Figure 1(a), (b), and (c)). The lengthened tendon was left in-situ in the opened 6th dorsal compartment. A soft bandage was applied, and light activities were encouraged immediately. A gradual return to full wrist-loading activity was allowed once the skin had healed. All patients had full range of motion 2 weeks after the operation and none required physical therapy. One patient reported mild pain at the base of the ipsilateral 5th metacarpal up to 9 months postoperatively. The others reported prompt and complete resolution of preoperative pain, noted no functional deficits or wrist weakness, were satisfied with the procedure, and to our knowledge, have not had any late complications. OPEN IN VIEWER

We believe that lengthening the ECU decreases tension in the tendon, which relieves painful stenosis or subluxation. Painless postoperative subluxation may occur. Subluxation or stenosis might be eliminated altogether by performing an ECU tenotomy (Figure 1(d)). However, the senior author favours lengthening over tenotomy to preserve some ECU function, in case the ECU should be called on as a donor tendon in the future, and because patients may be averse to a procedure that definitively eliminates the function of a body part. We recognize that neither of these potential benefits have been subjected to objective assessment. A prospective study including outcome measures is in order to determine the precise indications and efficacy of ECU lengthening.