Abstract
Objective
Although silicone finger implant has several disadvantages including loss of motion, implant breakage and osteolysis, Swanson or other silicone prosthesis are still most widely accepted in the world. Osseointegrated implant showed great improvement as for as stem fixation, however, still used silicone joint with high incidence of fracture. Cement-less surface type finger joint prosthesis has been developed and clinical trial has carried out. Ninety three joint replacement in 30 hands with mean follow up about 2 years are reported.
Materials & methods
The endoprosthesis consists of 3 different parts; two titanium joint anchor (fixture) in proximal and distal, titanium joint head in proximal, and HMWDP joint socket in distal. The joint anchor has tapered self tapping screw in joint side surface and has two flat long legs attached toward canal side which spread and compressed to intramedural canal firmly by turning a locking screw within the joint anchor. Each joint component is fixed to the anchor within a square hole. The MP joint component has anatomical head but semiconstrained toward volar dislocation by deep dorsal roof shape of the joint socket. Each socket has 2 different thickness. Because of cement less joint fixture mechanism and design, this endoprosthesis system is able to preserve collateral ligament and adjust the tension of collateral ligament. Twenty-six patients (24 women and 3 men) with average age of 59. 8years(range 35–80 years) were operated. Four patients were operated in both hands. Total of 93 joints were operated in 30 hands, average 3. 1 joints in one hand (4 in 16, 3 in 5, 2 in 5 and 1 in 4).
Results
Follow up averaged 23. 9 (range 14–37) months. The average arc of motion was 47(20–85) ° and extension lag was significantly improved in most cases. Ulnar deviation recurred moderately about 25%, and 2 cases complained pain with flexion contracture. There were 3 dislocations and 2 loosening with fracture of the leg.
Discussion
Surface type endoprosthesis preserving surrounding soft tissue is the optimal design in large implant arthroplasties. This new finger joints prosthesis provided cement-less joint fixture mechanism and surface type design and preliminary results were satisfactory. Although further follow up and more cases are required, this finger joint prosthesis has proven to be a very good alternative to silicone implant replacement especially for the young patients.
