Two Types of Silicone Implants Used in Arthroplasty of the Distal Interphalangeal Joint

Background: Silicone implant arthroplasty of the distal interphalangeal (DIP) joint is one of the effective approaches for treating symptomatic osteoarthritis accompanied by severe pain or developed deformity. This study aimed to evaluate and compare the clinical outcomes of DIP joint arthroplasty using SWANSON and SBi silicone implants. Methods: A retrospective cohort study was conducted, including 39 SWANSON and 19 SBi implants for DIP joint arthroplasty via dorsal approach. Preoperative and postoperative objective and subjective measures, including range of motion of the DIP joint, grip strength, pain score, Quick Disabilities of the Arm, Shoulder, and Hand scores, and satisfaction, were compared. In addition, the relation between the length of middle phalanx resection and postoperative joint instability was assessed. Results: The median follow-up period in the SWANSON and the SBi implant groups was 25 (interquartile range: 24-34) and 28 (24-56) months, respectively. Postoperative pain score and satisfaction with the SBi implant were better than those with the SWANSON implant, whereas no other significant differences were observed in other outcomes. The mean length of middle phalanx resection was significantly greater in the SBi implant (3.9 mm) compared with the SWANSON implant (2.9 mm), and a higher incidence of postoperative joint instability was observed in the SBi implant. Two cases of revision surgeries after failure were required in the SBi implants used in index fingers. Conclusion: The SBi implant showed higher patient satisfaction compared with the SWANSON implant; however, postoperative problems such as a tendency toward lateral instability and concerns regarding durability were suggested.