Henry Arthroplasty Hip

Abstract

The relevance of Henry's pelvic deltoid and its contribution to hip abductor strength is often not considered in hip arthroplasty. This small cadaveric study aimed to quantify the relative contributions of the pelvic deltoid muscles to abductor strength and to assess how different surgical approaches(anterolateral, direct lateral and posterior) impact on each of these muscle groups. We inspected the path of each approach and measured the cross-sectional area of the hip abductors, from which the contribution of each muscle to abductor moment was derived. We concluded that the posterior approach has the least impact on the pelvic deltoid and overall abductor moment.

Material and Methods

The study used a cadaveric model instead of the personalized magnetic resonance–based or rescaled generic computer models 13, 14 to allow a direct measurement of volumes as well as provide a clear visualization of structural damage to the tissues. Eleven formalin-fixed cadavers with no prior hip or pelvic surgery were made available by the Medical Education Anatomy Department of Newcastle University.

Three surgical approaches were selected as representative of posterior, lateral and

Results

All muscle measurements and calculated volumes are presented in Table 2. It is not known how far these measures differ from the population mean, and the assumption is made that our cadaveric material is representative of the population.

When examined in-situ, the gluteus maximus muscle consistently demonstrated a definite delineation of the direction of the muscle fibers, with the proximal fibers orientated in a horizontal direction and the lower middle to distal fibers directed more inferiorly.

Discussion

Henry first proposed the idea of a pelvic deltoid with an abductor component to the gluteus maximus in the early half of the 20th century, but this concept has seldom been discussed in the literature. The abduction moment of the proposed pelvic deltoid in our project accounted for almost half of the total hip abduction moment (pCSA ratios abductors: pelvic deltoid 1.19:1), which implies that this is a conceptually important consideration. Muscles of the pelvic deltoid also act as rotators

Acknowledgments

The authors would like to thank the staff of the Anatomy Department of the Newcastle University: Prof R Searle, Mrs C Harkness, Mr B Thomson, and Mrs H Mears for help and assistance with preparation and maintenance of the specimens.

No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.