A new linked elbow prosthesis for patients with small bone structure
Dr. Keiichiro Nishida, Associate Professor of Department of Human Morphology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, has developed a new linked elbow prosthesis (PROSNAP) in cooperation with Kyocera Medical (Osaka, Japan) which possesses a unique assembly system, initially to be used for the relatively small bony structure of Japanese patients.
PROSNAP has been in clinical use in Japan since November 2007, and the clinical results of total elbow arthroplasty (TEA) for the reconstruction of problematic rheumatoid arthritis (RA) elbow joints using the PROSNAP elbow prosthesis were recently published in the Journal of Shoulder and Elbow Surgery.
TEA has become a reliable procedure for the reconstruction of damaged RA elbows. However, previous reports have described a number of issues related to linked elbow prosthesis, including intraoperative fracture, prosthesis disassembly, or polyethylene wear and late failure of the locking mechanism. In the PROSNAP system, bone grafting between the anterior flange and the humerus is deemed unnecessary by selecting the proper size of the modular flange. The shaft at the joint portion of the humeral component is fitted, with a snap-in system, into the UHMWPE sleeve of the ulnar component, allowing the assembly of each component after cement fixation.
In the current report, the short-term clinical results of 17 elbows in 14 RA patients replaced with a PROSNAP elbow were evaluated with the mean follow-up period 47.7 months (range, 32-69 months). The preoperative conditions of the elbows were arthritis mutilans (n=10), an ankylosed or stiff elbow with a preoperative range of motion of 45 degrees or less (n=4), and loosening of a primary total elbow arthroplasty (n=3). The mean Mayo Elbow Performance Index improved from 57.6 points preoperatively to 97.1points postoperatively. Complications were noted in 1 elbow (6%) with postoperative fracture. The authors concluded that the PROSNAP elbow prosthesis can be safely implanted through a relatively easy procedure and provides satisfactory short-term clinical outcomes for the reconstruction of severely damaged RA elbows.