Rationale

The distal ulna is commonly dorsally prominent in RA due to incompetent ligamentous stabilizers of the DRUJ and volar extensor carpi ulnaris (ECU) subluxation, causing carpal supination and a caput ulna deformity. This deformity can cause attritional ruptures of extensor tendons, pain, and limitation in forearm pronation and supination.¹ Surgical treatment initially focused upon resection arthroplasty, as described by Darrach;² however, this treatment can lead to painful complications and newer surgical treatments have been developed, including a semi‐constrained total DRUJ arthroplasty.¹,³

Clinical comment

Treatment of DRUJ pathology with resection arthroplasty relies upon local tissue stabilization to prevent symptomatic radioulnar impingement. Semi‐constrained prostheses, which include an ulnar stem and link to the radius at the sigmoid notch, as described by Scheker,³ do not rely upon soft tissue stabilization in patients that have demonstrated incompetent tissue quality, and may help prevent complications in the RA patient.

Available literature and quality of the evidence

No studies have directly compared prosthetic arthroplasty to resection arthroplasty. Level IV studies have evaluated patient outcomes both with total DRUJ arthroplasty and distal ulna resection arthroplasty in RA patients.

Findings

With regards to distal ulna resection, Fraser et al. in 1999 evaluated the outcomes in RA patients and in post‐traumatic patients and found that RA patients had improved pain, with 34 of 37 wrists pain free, and an increase in grip strength (average of 0.8 kg).⁴ Additionally, Rana and Taylor evaluated 86 wrists in 70 RA patients treated with distal ulnar resection, reporting 95% pain‐free wrists after surgery, improvement in forearm pronation and supination in all, and improvement in grip strength in 88%.⁵ Within these case series, the authors did not find substantial pain or functional limitations from the previously described complications of distal ulna resection, including ulnar drift of the carpus, radioulnar impingement and ulnar instability. They reported ulnar clicking, without significant pain, and progressive ulnar drift of the carpus, without an influence on the patient’s overall result.⁴,⁵

When evaluating the semi‐constrained DRUJ arthroplasty, Galvis and colleagues in 2014 evaluated a case series of RA patients who underwent 19 total DRUJ arthroplasties. At an average of 39‐month follow‐up, these patients demonstrated decreased pain from Visual Analog Scale (VAS) of 7.4 to 2.2, improvement in pronation from 56° to 78°, and improved supination of from 56° to 72°. No progression of ulnar carpal drift or tendon ruptures occurred; however, tendon irritation was seen in one patient.⁶ Additional studies have evaluated patient outcomes after DRUJ arthroplasty; however, these studies were not specific to RA patients.

Resolution of clinical scenario

• There is incomplete evidence to conclusively support DRUJ arthroplasty over resection arthroplasty.
  
• Technical rationale including decreased reliance on incompetent soft tissue structures and decreased risk of radioulnar impingement support DRUJ arthroplasty as a reasonable alternative to DRUJ resection arthroplasty, specifically in the younger and less debilitated RA patient.
  
• Additionally, total DRUJ arthroplasty could be considered as a salvage option for a symptomatic resection arthroplasty if adequate ulnar length is maintained.
  
• Longer follow‐up studies will be helpful in supporting DRUJ arthroplasty as a primary procedure for DRUJ deformity in RA.