[Mid-term results after scaphoid excision and four-corner wrist arthrodesis using K-wires for advanced carpal collapse].

AIM: Successful four-corner fusion after scaphoid excision provides pain relief und preserves an acceptable movability of the wrist. However, this treatment option for advanced carpal collapse is not without complications, such as malunion, hardware impingement or incomplete correction of lunate extension. K-wires, staples, Herbert screws or, recently, locking plates are all possible fixation techniques after scaphoid excision. Only a few studies including mid-term results using K-wires are available. The aim of our study was to evaluate clinical and radiological mid-term results after scaphoid excision and four-corner arthrodesis using K-wires for stage II and III scapholunate and scaphoid non-union advanced collapse.

METHOD: Twelve wrists of 11 patients (4/SNAC II degrees, 3/SNAC III degrees, 0/SLAC II degrees, 5/SLAC III degrees) were treated operatively by scaphoid excision and four-corner arthrodesis. Four K-wires were used for osteosynthesis. After an average follow-up of 60.25 months, reexamination included subjective, objective and radiological values. Clinical examinations covered wrist motion, grip strength and pinch strength. These parameters were compared with preoperatively collected data and values of the unaffected side. The DASH score (disabilities of the arm, shoulder and hand), Cooney score and the visual analogue scale (VAS 0-10) were analysed. Radiographic assessment of consolidation was verified by conventional X-rays. The carpal height was compared to the preoperative value by assessing the Youm index.

RESULTS: All patients were satisfied, pain relief was reported and displayed on VAS from 7.4 (5-10) to 1.4 (0-5). The mean flexion-extension arc of 76.3 +/- 28.8 degrees (59.7% of the opposite wrist), preoperatively 75 +/- 17.3 degrees, was documented. The average total arc of ulnar and radial deviation was 37.5 +/- 9.2 degrees (51% of the opposite wrist). The preoperative value was 33.5 +/- 9.8 degrees. Further clinical evaluation yielded a mean grip strength of 39.3 kp (89.5% of the anaffected side) and pinch strength of 7.6 kp (81.7%). Total DASH score and Cooney score averaged 15 and 74.17 points, respectively. Osseus consolidation was observed radiologically in all patients already after 6 weeks. The Youm index decreased from 0.55 +/- 0.054 to 0.51 +/- 0.057. The radiolunate joint space remained unaltered in height. There were no infections. Except for wire removal, no additional surgery was necessary.

CONCLUSION: Scaphoid excision and four-corner arthrodesis for advanced collapse of the wrist enjoy great satisfaction by the patients, with a high degree of pain reduction. This method shows persistent strength and movability in mid-term-results. Compared to alternative fixation techniques, the use of K-wires is a low-risk and low-cost treatment option, although removal of the K-wires is commonly necessary.