Equally good fixation of cemented and uncemented cups in total trapeziometacarpal joint prostheses. A randomized clinical RSA study with 2-year follow-up.
OBJECTIVE
Cup failure is a recognized problem in total trapeziometacarpal (TM) joint prostheses; it may be related to poor fixation, which can be revealed by radiostereometric analysis (RSA). We compared the early implant migration of cemented trapezium cups to that of uncemented screw cups.


METHODS
In a prospective, parallel-group, randomized patient-blinded clinical trial, we included 32 hands in 28 patients (5 males) with a mean age of 58 (40-77) years and with Eaton stage-2 or -3 osteoarthritis of the trapeziometacarpal joint. Patients were randomized to surgery with a cemented DLC all-polyethylene cup (C) (n = 16) or an uncemented hydroxyapatite-coated chrome-cobalt Elektra screw cup (UC) (n = 16). Uncemented cups were inserted without threading of the bone. Stereoradiographs for evaluation of cup migration (primary effect size) and DASH and pain scores were obtained during 2 years of follow-up.


RESULTS
The 2-year total translation (TT) was similar (p = 0.2): 0.24 mm (SD 0.10) for the C (n = 11) and 0.19 mm (SD 0.16) for the UC (n = 11). Variances were similar (p = 0.4). Judged by RSA, 2 UC cups and 1 C cup became loose (TT > 1 mm). Both UC cups were found to be loose at revision. Grip strength, pain, and DASH scores were similar between groups at all measurement points.


CONCLUSIONS
Early implant fixation and clinical outcome were equally good with both cup designs. This is the first clinical RSA study on trapezium cups, and the method appears to be clinically useful for detection of loose implants.
Department of Orthopaedics, Section of Hand Surgery, and Orthopaedic Research Unit, Holstebro Regional Hospital, Holstebro, Denmark. tbhansen@dadlnet.dk
Torben Baek
TB
Hansen
Maiken
M
Stilling
D000328:Adult; D000368:Aged; D019643:Arthroplasty, Replacement / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods; D005260:Female; D005384:Finger Joint / Q000601:surgery*; D005500:Follow-Up Studies; D006801:Humans; D007595:Joint Prosthesis / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000601:surgery; D011475:Prosthesis Failure / Q000209:etiology; D013933:Thumb / Q000601:surgery*