Prospective comparative study of scaphocapitate arthrodesis with and without lunate excision for stage IIIB Kienböck’s disease

Abstract Introduction Kienböck’s disease is a progressive avascular necrosis of the lunate that causes wrist pain and functional impairment. Surgical intervention is often needed for advanced stage IIIB disease to relieve symptoms and preserve the carpal structure. Scaphocapitate (SC) arthrodesis is an established technique, but the value of lunate excision versus preservation remains debated. This study prospectively compared the outcomes of SC arthrodesis performed with and without lunate excision. Materials and methods This prospective comparative study included 38 patients with stage IIIB Kienböck’s disease, who were allocated to receive SC arthrodesis with lunate preservation ( n  = 19) or lunate excision ( n  = 19). The follow-up time was 84 months. The primary outcome measure was pain intensity, which was assessed via the visual analogue scale (VAS) for pain. The secondary outcomes included wrist function evaluated by the modified Mayo wrist score (MMWS) and patient-rated wrist evaluation (PRWE), grip strength, wrist range of motion (ROM), and radiographic parameters such as ulnar variance, the carpal height ratio (CHR), the carpal ulnar distance (CUD), and the radioscaphoid (RS) angle. The union rate, time to union, time to return to work, and incidence of postoperative complications were also recorded. Results Both groups demonstrated significant postoperative improvement in pain (VAS pain score, p  = 0.001). At 84 months, the preservation group achieved superior pain control, with a lower mean VAS score (5 versus 12, p  = 0.001). The preservation group also maintained a greater CUD (30 mm versus 23 mm, p  = 0.001) and exhibited later onset of degenerative changes. MMWS improved from 49 to 73 in the preservation group and from 48 to 72 in the excision group. The PRWE scores decreased from 69 to 21 in the preservation group and from 67 to 24 in the excision group. The final grip strength reached 88% of that of the contralateral side in the preservation group and 84% in the excision group, with no significant difference in ROM. The union rates were 93% for preservation and 91% for excision. The excision group presented higher rates of degenerative changes (16 versus 8 cases) and nonunion (2 versus 1). No major differences were found in the infection rate, sympathetic reflex dystrophy, or return to work. Conclusions SC arthrodesis provides reliable long-term pain relief in patients with stage IIIB Kienböck’s disease. Lunate preservation provides superior pain control and carpal alignment, reduces degenerative sequelae, and is recommended where feasible.