Primary Prosthetic Replacement of the Distal Radioulnar Joint (DRUJ) in Rheumatoid Arthritis Using the First Choice Hemi-DRUJ Resurfacing Implant

Abstract

Objective/Hypothesis: In rheumatoid arthritis, resection of the ulnar head has been the gold standard for pain and dysfunction in the distal radioulnar joint (DRUJ). The ulnar head is today, however, considered to be essential for the wrist function and alternatives are being investigated. We present a 5-year clinical and radiological follow-up of a primary hemi-DRUJ resurfacing implant. Materials and Methods: Between November 2006 and October 2010, 12 female rheumatoid arthritis patients, mean age 59 years (range, 39-72 years), were operated with an uncemented metal hemiprosthesis (First Choice, Ascension Orthopedics, Texas, USA). Ten patients had a concomitant partial or total wrist fusion. A follow-up protocol was designed before study start, and clinical and radiographic data were recorded prospectively at 1, 2, and 5 years. Results: One patient was revised after 2 years due to a suspected low-grade infection, and 1 patient was reoperated due to reduced forearm rotation. All patients were subjectively and objectively stable at the 5-year follow-up. Pronation/supination remained unchanged from preoperatively to final follow-up, whereas grip strength and subjective outcome (DASH, VAS pain) improved. Radiographically, a remodeling of the sigmoid notch was seen in half of the patients with a minor radial shift of the prosthesis into the radius in some patients. With the remodeling, a gradual increase of the contact area between the prosthetic head and the sigmoid notch was seen over time with 79% of bony contact after 1 year and 90% after 5 years. Bone resorption around the collar of the prosthesis was noted in all but one patient. In 3 of 11 patients, the resorption was within 2 to 4 mm from the collar and in 3 of 11 patients between 4 and 7 mm. Only one patient showed a major resorption of 20 mm, and this was seen already at 2 years. This patient was the only one showing a subsidence of more than 2 mm. No radiolucent zone greater than 1 mm around the ulnar stem was observed. In 1 patient a thin zone, indicative of a loosening membrane was noted after 1 year, but no deterioration was seen over time. This patient scored VAS 0 both at rest and during activity and a DASH score of 3. Conclusions: The preliminary results of the prosthesis in rheumatoid patients are encouraging, and the patients report minimal discomfort, an acceptable range of forearm rotation, and a well-functioning stable wrist. The concept of using a hemiprosthesis thus seems to be appropriate also for the rheumatoid DRUJ, at least as seen in this medium-term study. The important finding that no major DRUJ instability was encountered is promising, and in the short/medium perspective, it is possible to achieve dynamic and static stability with a reasonable range of motion (ROM) and minimal discomfort without competent primary stabilizers. Longer follow-ups are of course necessary, especially evaluating the osseous reaction of the nonsubstituted subchondral bone on the radial side, as well as the long-term stability of the joint.