DOS 2016

180

· DOS Abstracts

Posterior or anterolateral approach in hip joint

arthroplasty - impact on frontal plane moment.

Marianne Tjur, Asger R. Pedersen, William Sloth, Kjeld Søballe, Nina D. Lorenzen,

Maiken Stilling

Orthopaedic Research Unit, Aarhus University Hospital; Hammel

Neurorehabilitation Centre and University Research Clinic, Aarhus University;

Hammel Neurorehabilitation Centre and University Research Clinic, Aarhus

University; Orthopaedic Research Unit, Aarhus University Hospital; Orthopaedic

Research Unit, Aarhus University Hospital; Orthopaedic Research Unit, Aarhus

University Hospital

Background:

Anterolateral (AL) surgical approach in hip joint arthroplasty (HJA)

necessitates division of the hip abductor muscle complex, which may compro-

mise normal postoperative gait observed in the frontal plane moment (FPM).

Purpose / Aim of Study:

To compare FPM during early and late stance after

HJA by either AL or posterior (POST) surgical approach, and clarify if pain is a

potential cause of decreased FPM.

Materials and Methods:

28 patients were prospectively included and rand-

omized to AL (ad modum Watson) or POST (ad modum Moore) surgical ap-

proach with HJA. 3D gait analysis (Vicon) was performed before surgery (BL)

and 3 and 12 months postoperative. Ground reaction force (GRF) was sampled

at 2000 Hz using an OR6-7 AMTI force plate (FP). Peak GRF was extracted for

early and late stance, respectively, after which FPM and lateral trunk inclination

(TI) corresponding to peak GRF was defined. Patients self-reported pain (VAS)

was obtained during clinical examinations related to the gait analysis. The overall

difference between surgical approaches was tested with a linear mixed model.

Findings / Results:

An overall different effect of surgical approach on FPM for

the affected leg was found during early stance (p=0.006). From BL to 3 months,

average FPM decreased by 125 Nmm/kg in the AL group (CI -213;-37.4),

while no significant change of FPMwas seen in the POST group (CI -81.6;78.4).

From 3 to 12 months, the change of FPM in the AL group was not significant

(CI -34.2;148), whereas FPM in the POST group increased by 136 Nmm/kg (CI

56.3;216). VAS scores did not differ between approach groups (p=0.69).

Conclusions:

Hip FPM during early stance was decreased after HJA utilizing AL

compared to POST surgical approach. No effect was found during late stance

phase. There was no indication of postoperative pain being the cause of de-

creased FPM in early stance.

No conflicts of interest reported

131.