[Chronic lunotriquetral instability of the wrist. Presentation of our method of treatment].

PURPOSE OF THE STUDY

One of the causes of pain on the ulnar side of the wrist is post-traumatic lunotriquetral (LTq) instability, which is difficult to detect on radiographs. For diagnosis, arthroscopic examination is most reliable. The methods for treatment of LTq instability include mere immobilization, ligament reconstructions and LTq joint stabilization with Kirschner's wires in acute conditions, and stabilization of the LTq joint by tenodesis or arthrodesis. In this study our method of treating chronic isolated injury to the lunotriquetral ligament is described.

MATERIAL

The group comprised 43 wrists with isolated lunotriquetral ligament injuries diagnosed by arthroscopy. In 19 patients with persisting complaints, stabilization was performed using our original method. At 4 months after surgery, the results were evaluated by the method of Green and O'Brien.

METHODS

Access to the LTq joint was gained through the fifth extensor compartment. At about 3 cm proximal to the ulnar head, one third of the extensor capri ulnaris (ECU) tendon was detached, without doing damage to the tendinous sheath on the ulnar head, and stretched distally up to the triquetrum-hamate joint level. Using a 3.2-mm drill, a tunnel was made on the dorsal side of the triquetrum, starting at the distal third of the ulnar side of the triquetrum and opening at the attachment site of the dorsal LTq ligament. In the middle part of the dorsal side of the lunate, a groove 4 mm deep and 6 mm long was made with a cutter and a two-suture Mitek anchor was inserted in its radial side. The graft was passed through the tunnel in the triquetrum, tightened up and inserted in the groove on the lunate, and sutured to the anchor. The rest of the tendon was reinserted to the ECU tendon. After suturing the dorsal structures and skin, a high plaster cast reaching up above the elbow was applied for 4 weeks, followed by application of a short plaster splint for another 2 weeks.

RESULTS

Using the method of Green and O'Brien, we assessed pain, function (return to full activity), range of motion and grip strength. An excellent result was recorded in 48%, good in 42% and satisfactory in 10% of the patients; there were no poor results.

DISCUSSION

Our method gives better results than the published methods of tenodesis, because it secures stability of both the triquetrum and lunate bones. Also, these methods restrict motion to a lesser degree than LTq joint arthrodesis.

CONCLUSIONS

LTq instability of the wrist is a limiting condition for the patient's daily activities. It appears when, for gripping, the hand is positioned in dorsal flexion and ulnar duction. The diagnosis and therapy are complicated and only arthroscopy is reliable for LTq instability detection. The method described here provides an option for treating this disorder with good outcome and, in case of failure, does not interfere with a subsequent LTq joint arthrodesis.