Principles of surgical treatment of delayed carpal tunnel syndrome in malunion of the distal metaepiphysis of the radius

Introduction Delayed carpal tunnel syndrome (DCTS) in patients with malunited fracture of the distal metaepiphysis of the radius (DMR) develops from several weeks to months after the injury. The main treatment method for these patients is corrective osteotomy and fixation of the radius bone. However, the necessity and methods of median nerve decompression still remain controversial. Purpose To evaluate long-term results of surgical treatment of patients with a malunited distal radius fractures and concurrent delayed carpal tunnel syndrome, depending on the method of median nerve decompression, and to develop a treatment concept. Methods The results of treatment were studied in 33 patients (30 women and three men, average age 54.6 years) with malunited DMR fracture complicated by DCTS. All patients underwent corrective osteotomy of the distal radius and osteosynthesis with a volar locking plate. Open carpal tunnel release (OCTR) was performed in the first group of patients through a separate limited surgical approach (n = 19), while decompression of the median nerve was carried out through an extended flexor carpi radialis (EFCR) approach in the second group (n = 14). Patients were evaluated clinically (wrist range of motion, hand strength, VAS pain level, DASH score), radiographically, and electromyographically before surgery and one year after it. DCTS severity and DR deformity were compared. Results After the operation, patients in both groups showed improvement in clinical, radiographic and ENMG parameters. The average union time was 12 weeks. Better results were achieved in the first group: the hand grip strength increased significantly, as did daily activity and the amplitude of the M-response of the short muscle abducting the thumb. The most significant changes were observed in moderate and severe DCTS cases, as well as in the intermediate and predominantly dorsal DR deformity. Discussion The questions about the advisability of simultaneous decompression of the median nerve in patients with OCTR and the nature of the corresponding approaches do not have a clear answer. Most authors believe that it is sufficient to perform only corrective osteotomy and osteosynthesis. Our study showed the importance of a differentiated approach to solving this problem. Conclusions Corrective osteotomy and volar locking plate osteosynthesis in carpal tunnel release are reliable and effective treatments for malunited DMR fractures with concurrent delayed carpal tunnel syndrome. The best results were obtained after open carpal tunnel release from a separate limited approach in patients with moderate and severe deformity of the distal metaepiphysis of the radius, combined with “intermediate” and “predominantly dorsal deformity. In mild DCTS cases, as well as in cases of predominantly palmar DMR deformity, decompression of the median nerve can be performed from the main EFCR approach.