131.
Equally good fixation of cemented and uncemented cups in total joint
trapeziometacarpal prostheses: a randomized clinical RSA study with 2
years follow-up
Torben Bæk Hansen, Maiken Stilling
Department of Orthopaedics, Section of Hand Surgery, and The Orthopaedic
Research Unit Regional Hospital Holstebro, Denmark; Department of
Orthopaedics, Section of Hand Surgery, and The Orthopaedic Research Unit,
Regional Hospital Holstebro, Denmark.
Background:
Cup failure is a recognized problem in total trapeziometacarpal
(
TM) joint prosthesis. In theory this may be related to poor initial fixation in
uncemented implants, which may be predicted by radiostereometry (RSA).
Purpose / Aim of Study:
We investigated the early implant migration of
cemented trapezium cups in comparison with uncemented screw cups inserted
with a new insertion technique.
Materials and Methods:
In a prospective, parallel-group, randomized patient-
blinded clinical trial, we compared 32 hands in 28 patients (5 males) at a mean
age of 58 years (40-77) with Eaton stage 2 and 3 osteoarthritis of the TM joint.
Patients were randomised to surgery with A) a cemented DLC all-
polyethylene cup (PC) (n=16) or B) an uncemented hydroxyapatite-coated
chrome-cobalt Elektra screw cup (SC) (n=16) that was inserted without
threading of the bone. Stereo radiographs for evaluation of cup migration
(
primary effect size), and alongside DASH and pain scores were obtained
during 2 years follow-up.
Findings / Results:
The 2 year total translation (TT) was similar (p=0.19) with
0.24
mm (SD 0.10) for the PC (n=10) and 0.22mm (SD 0.20) for the SC
(
n=13). Judged by RSA one cup in each group turned loose, and one SC was
revised after 2 years. Grip strength, pain, and DASH scores were similar
between the two groups at all measure points.
Conclusions:
Early implant fixation and clinical outcome was equally good
with both cemented and uncemented cups by using a new cup insertion
technique of the uncemented cups. This is the first clinical RSA study on
trapezium cups and, although larger studies with longer follow-up are needed,
the method appears clinically useful as it detected the loose implants.
