Destruction and deformity in both PIP and MP joints are not uncommon and cause sever disabilities. Arthroolasty of the MP joint combined with arthrodesis of the PIP joint are the usual choice for this condition. Some motion in ulnar digits provides great benefits for rheumatoid patients. We report implant arthroplasty of the PIP joint and also simultaneous replacement of PIP and MP joint in same finger.
Twenty-five joints in 15 patients underwent PIP arthroplasty either with silicone or surface replacement implant. Twelve PIP joints in 6 patients used Silicone implant (6 Swanson and 6 Avanta) alone and mean follow up was 42(6–84) months. New cementless surface implant (Self Locking Finger Joint, SLFJ) were developed and clinically used for about 3 years. Because of the stem design, SLFJ are able to use both PIP and MP joint simultaneously or combined with silicone implant. Four PIP joints in 3 patients used SLFJ alone and 6 patients underwent both PIP and MP joint with implant simultaneously. Combination of SLFJ PIP and silicone MP was 4 finger in 2 hand, SLFJ PIP and SLFJ MP was 3 finger in 2 hand, silicone PIP and SLFJ MP was 3 finger in 2 patients and silicone PIP and silicone MP was 1 finger. Mean follow up for SLFJ in either PIP or MP was 18(4–37) months.
Average arc of the PIP with silicone implant alone was 38(10–50 ° and SLFJ alone was 55(45–60) °. One PIP SLFJ dislocates immediate after surgery and was converted silicone later on. Of 7 SLFJ with combined PIP and MP arthroplasties, 2 PIP lost motion completely, one PIP move only 15°, 4 PIP move 75 °in average. Four silicone PIP combined with MP arthroplasties move 45°in average. One PIP SLFJ had breakage in stem legs, which believed to occur during interaction of stem insertion from both side of the basal phalanx, and was seen at immediate post op X-ray. There was one instability in index replaced with SLFJ for sever Swan neck deformity and no infection. Patient satisfaction for simultaneous replacement in PIP and MP joint were excellent except one whose age was 72.
Stability of the PIP joint in index finger is important for pinch and PIP motion of ring and little fingers are required for grip motion. Although arthrodesis of the PIP joint were performed more often and functional improvement usually obtained compared to pre-operative condition, ulnar 2 digits better to preserve some motion in the PIP joint as long as there is a possibility, and especially for the young patients. The results of the simultaneous replacement in PIP and MP joint seems discourage, however, when considering the severity of the deformities of this series, there is a good chance in the future. We will improve implant design and surgical technique as well as post-operative therapy, and continue to challenge the simultaneous replacement of PIP and MP joint.
