Muscle atrophy before and after total hiparthroplasties (THA) has been previously described in Anterior Minimal Invasive Surgery and in patients with osteoarthritis1,2,3. Our objective was to assess muscle atrophy in patients after THA with a standard posterolateral approach compared to the controlateral side without a hiparthroplasty. Secondary objectives were to determine differences in muscle atrophy between Resurfacing hip arthoplasty (RHA), Metal-on-Metal hiparthroplasty (MoM) and ceramic-on-polyethylene hiparthroplasty (Co-P) and assess correlation of muscle atrophy with demographics and clinical sores.

Patients with a unilateral THA, 3 to 6 years after surgery, of an existing cohort of a randomized controlled trial comparing resurfacing hip arthroplasty (RHA) (N=28) and conventional MoM uncemented hiparthroplasty (MoM THA) (N=17) with a control group (N=16) with ceramic-on-polyethylene hip arthroplasty were included. All patients underwent a MRI with standard MARS (metal artifact reduction sequence) protocol, completed questionnaires and were clinically evaluated. The modified Goutallier score4was used to determine muscle atrhophy in individual muscles (gluteus minimus, -medius, -maximus, piriformis, iliopsoas, adductors, pectineus, tensor...

Significant atrophy (see figures 1,2,3) was found in the obturator internus (85% of patients), quadratus femoris (65% of patients), piriformis (74% of patients), obturator externus (40% of patients), iliopsoas (11% of patients), gluteus medius (3% of patients) and, in a lesser degree (goutallier 2), atrophy was also found in the gluteus maximus. There was a significant (p<0,05) higher median atrophy score of the iliopsoas and gluteus maximus muscle in the RHA group compared to the CoP group (see frequency tables, figure 4). There was no...

Muscle atrophy is a common finding around the hip joint in asymptomatic patients after THA using a posterolateral approach, but doesn’t seem to have a relation with patient satisfaction or clinical outcome. There is a significant higher degree of muscle atrophy in the iliopsoas and gluteus maximus after RHA compared to CoP THA. This may be explained by a more extensive exposure during surgery.

[1]Rasch et al. Persisting muscle atrophy two years after replacement of the hip. J Bone Joint Surg (BR) 2009;91-B:583-8 [2]Bremer et al. Soft-tissue changes in hip abductor muscles and tendons after total hip replacement: Comparison between the direct anterior and the transgluteal approaches. J Bone Joint Surg (Br) 2011;93-B:886-9. [3]Muller et al. Age-related appearance of muscle trauma in primary total hip arthroplasty and the benefit of a minimally invasive aproach for patients older than 70 years. International Orthopaedics (SCIOT) 2011; 35:165-171. [4]Engelken et al. Assesment...

1Department of Radiology Rijnstate hospital Arnhem, currently employed at the VUMC medical center Amsterdam. 2Department of Radiology and Orthopaedics Rijnstate hospital Arnhem. Correspondence: [email protected]