Zimmer | Mayo Conservative Hip Prosthesis | Which Medical Device

Description

From Which Medical Device

Designed by Morrey in 1984, this conservative bone preserving femoral component has the longest track record in short stem devices. This is a neck-retaining device. The Mayo stem has a proximal wide trapezoidal cross-section in order to gain multipoint contact within cortical bone, and is wedge shaped in both the antero-posterior and medio-lateral planes. In order for this to be stable an intact femoral neck ring is mandatory. The surface of the titanium implant was initially grit blasted with mesh pads to encourage osseointegration, but now comes with a hydroxyapatite coating.

In contrast to some other proximal loading devices, the stem of the Mayo hip touches the lateral cortex. Although intended for alignment, there can be some stress response in the lateral cortex and stress shielding proximally (1). Perforation of the lateral cortex is a recognised complication (2) and some authors have reported a high incidence of malalignment (3). The stem ranges from 81 to 107mm in length (measured from the base of the neck) and has a 12/14 taper.

Despite this, results from the originator are excellent with a 98.2% survival of the stem without mechanical loosening at ten years (4).

For further information on short femoral stems, read our article on What's Available in Short Stem Hip replacements.

References

(1) Chen H, Morrey BF, An K, Luo Z. Bone Remodeling Characteristics of a Short-Stemmed Total Hip Replacement. J Arthroplasty. 2009, 24(6), 945-50.

(2) F. Falez, F. Casella, G. Panegrossi, F. Favetti, C. Barresi. Perspectives on metaphyseal conservative stems. J Orthop Traumatol. 2008 March; 9(1): 49–54.

(3). Gilbert RE, Salehi-Bird S, Gallacher PD, Shaylor P. The Mayo Conservative Hip: experience from a district general hospital. Hip Int. 2009 Jul-Sep;19(3):211-4.

(4) Morrey BF, Adams RA, Kessler M. A conservative femoral replacement for total hip arthroplasty. A prospective study. J Bone Joint Surg [Br] 2000;82-B:952-8.