Outcome analysis of ulnar shortening osteotomy for ulnar impaction syndrome

Abstract

BaCKGROund: Ulnar-sided wrist pain is a common problem in the upper extremity. It affects a broad patient population and can be difficult to treat. Ulnar impaction syndrome (UIS) is major cause of ulnar-sided wrist pain and a number of different operations have been used to correct it, including ulnar shortening osteotomy (USO). OBJeCtive: To retrospectively review functional outcomes and complication rates of USO for UIS at the Hand and Upper Limb Centre (London, Ontario) over a two-year period. MethOdS: Twenty-eight patients who underwent USO between 2007 and 2009 participated in the present study. Ulnar variance pre-and postsurgery was assessed using standard radiographic examination. Patientrated outcomes were measured using a visual analogue scale (VAS) for pain and the Disabilities of the Arm, Shoulder and Hand (DASH) survey for functional outcomes. Objective grip strength and range of motion were compared with the contralateral extremity. ReSultS: On average, USO achieved a 3.11 mm reduction in ulnar variance. Nonunion occurred in five patients and required a secondary bone grafting procedure. All USO eventually healed. Overall, pain improved by 47.2% and the mean DASH score after surgery was 37.21. Flexion, extension and supination range of motion decreased by 10° compared with the unaffected side. Eleven patients (39%) elected to undergo a second surgery for hardware removal. Patients receiving compensation from the Workplace Safety and Insurance Board experienced significantly higher residual pain (VSA 5.24 versus 1.97) and disability levels (DASH 60.23 versus 25.70). Smokers also experienced worse outcomes in terms of pain (VSA 4.43 versus 2.36) and disability (DASH 51.06 versus 29.67). In this cohort, smoking was not associated with a higher rate of nonunion. COnCluSiOn: USO is effective in reducing pain in UIS and improves disability, at the price of a small decrease in range of motion. Smokers and people receiving compensation from the Workplace Safety and Insurance Board, however, have significantly worse subjective outcomes (VAS and DASH), but similar objective outcomes (range of motion).

Ulnar Resection Length: A Risk Factor for Nonunion in Ulnar Shortening Osteotomy

“…In these small studies, the range of ulnar resection lengths is quite variable. The 5.5 mm resection cutoff is certainly higher than in many other series 2,6,7,26 and may be larger than the norm in general practice which is a limitation of this study. When reporting the actual length of ulnar resection in the operative notes, all surgeons in the cohort measured resection length to the nearest 0.5 mm based on preoperative templating and confirmatory intraoperative measurements.…”

“…This study, although still relatively small, was powered to identify the association between large resection lengths (≥5.5 mm) and subsequent nonunion. While a 5.5 mm resection is certainly higher than in many other series, 2,6,7 the knowledge that resecting greater than 5.5 mm increases the odds of nonunion remains clinically relevant, especially when using the Acumed and Medartis systems which have cutting guides with an allowable resection length of 10 and 8 mm, respectively. Ulnar resection decreases bony abutment and stress through the ulnocarpal joint and simultaneously provides stability to the DRUJ.…”

“…In the literature, nonunion rates following ulnar shortening osteotomies are reported from 0% 7 to 18%. 1,2 Assuming a 2-sided test, alpha of 0.05, power of 0.8, nonunion rate of 1% in the smaller resection group, and nonunion rate of 20% in the larger resection group, it was determined that a total of 78 patients would be needed to detect a significant difference ( P < .05) in bony union between groups. Thus, a minimum of 52 patients would be needed for the smaller resection group and a minimum of 26 patients in the larger resection group.…”

“…Ulnar shortening osteotomy (USO) is a widely accepted surgical procedure for multiple conditions resulting in ulnar-sided wrist pain, including ulnar impaction syndrome, triangular fibrocartilage (TFCC) tears, lunotriquetral ligament tears, and malunited distal radius fractures. [1][2][3][4][5][6] These conditions may result from static or dynamic positive ulnar variance, which creates distal ulnar abutment through the TFCC and carpus. 4,5,7 Biomechanical studies have shown that even with neutral ulnar variance, the ulnocarpal articulation transfers a considerable amount of stress over a relatively small area.…”

“…[3][4][5]9,10 Outcome studies on USO have been favorable with wide adoption for refractory ulnar-sided wrist pain. 2,3,6,9,10 The reported rates of complications such as nonunion, delayed union, and removal of hardware have varied considerably in the literature. Nonunion, a serious complication typically requiring reoperation, has reported rates ranging from 0% to 18% following USO.…”