166 / 245
166
· DOS Abstracts
2 year results with Electra bi-metal screw cup in
total trapeziometacarpal arthroplasty evaluated
with RSA
Lene Dremstrup, Maiken Stilling, Lone Kirkeby, Torben Bæk Hansen
University Clinic for Hand, Hip and Knee Surgery,Department of Clinical
Medicine, Hospital Unit West, Holstebro, Aarhus University, Aarhus
Background:
Cup failure is a recognized problem in total trapeziometacarpal
(TM) joint prosthesis, which may be related to cup design and bone quality.
Purpose / Aim of Study:
To evaluate cup migration and clinical outcome with
the Elektra bi-metal TM screw cup.
Materials and Methods:
Case-study of the first 50 patients (50 hands, 42
females) with Eaton stage 2-4 osteoarthritis of the TM joint scheduled for
surgery with the Elektra bi-material (CoCr/TA6V) metal-on-metal gridblast-
ed hydroxyapatite-coated TM screw cup (Nov 2011 thru June 2014). Bone
Mineral Density (BMD) was measured pre-operative in the trapezium. Cup mi-
gration (model-based RSA), DASH score and function were measured at base-
line, 3 months, 1 and 2 years. Total Translation (TT) of the cup was calculated as
square root (x^2+y^2+z^2).
Findings / Results:
Patients were mean 57 years (range 43-71). All patients
received the planned surgery and there were no intraoperative complications.
TT cup migration at 2 years follow-up was mean 0.47 (sd 0.9) mm, and there
was no increase in migration from 3 months to 2 years (p>0.19). At 2 years fol-
lowup 3 cups (8%) had progressive migration above 1mm and might be loose.
4 cups were revised within the follow-up period, 3 due to aseptic loosening of
which 2 also had pseudotumour, and 1 due to pain. 1 cup dislocated and had
closed reduction. DASH score improved a mean 30 (sd 25) to 1 year (p=0.000).
Pre-operative BMD measurements are ongoing.
Conclusions:
Elektra bi-metal screw cup fixation was acceptable for most im-
plants (92%) up to 2 years as measured by RSA, and the functional results im-
proved significantly. The cup could be inserted in all patients and there were no
intraoperative complications. However 8% were revised within 2 years and of
these 2 had pseudotumour.
No conflicts of interest reported
117.