DOS 2017

222

· DOS Abstracts

Greater interlimb difference in hip muscle mass

in patients with metal-on-metal hip arthroplasty

compared to metal-on-polyethylene hip arthro-

plasty at midterm follow-up.

Mette Hjorth Holm, Inger Mechlenburg, Marianne Tjur, Kjeld Søballe, Maiken

Stilling

Orthopaedic Research Department, Aarhus University Hospital

Background:

Metal-on-metal (MoM) total hip arthroplasty (THA) and hip re-

surfacing arthroplasty (HRA) was presumed to provide superior functional out-

comes compared to metal-on-polyethylene (MoP) THA.

Purpose / Aim of Study:

To compare muscle mass and power, block-step test

and patient reported outcomes between MoM THA/HRA and MoP THA pa-

tients.

Materials and Methods:

51 MoM THA/HRA (33 male) and 23 standard MoP

THA (8 male) patients participated in a cross- sectional study mean 6.5 (0.6

– 12.5) years postoperative. Muscle mass was measured by total- body Dual

energy X-ray Absorption scans and muscle power in a Leg Extensor Power Rig.

Block- step test estimates were obtained with an Inertial Measurement Unit.

Clinical outcome scores were Harris Hip Score (HHS) and The Copenhagen Hip

and Groin Outcome Score (HAGOS).

Findings / Results:

MoM THA/HRA patients had a greater interlimb difference

in hip muscle mass compared to MoP THA patients (P=0.02), but otherwise, the

interlimb differences in muscle masses and power was similar (P>0.05). Muscle

mass of the thigh and calf area in both legs, and muscle power in both legs was

higher in MoM THA/HRA patients compared to MoP THA patients (P<0.009).

Block step time asymmetry when ascending was lower in MoM THA/HRA pa-

tients compared to MoP THA patients (P=0.03). HHS and HAGOS were similar

between groups (P>0.07).

Conclusions:

MoM THA/HRA patients had a higher interlimb difference in hip

muscle mass which could be related to surgical factors, or to an inflammatory

response to the metal wear debris. Furthermore, MoM THA/HRA patients had

less block-step time asymmetry when ascending compared with MoP patients.

No conflicts of interest reported

174.