Ideal Femoral Head Size in Total Hip Arthroplasty Balances Stability and Volumetric Wear

Abstract

Background: Over the last several years, a trend towards increasing femoral head size in total hip arthroplasty to improve stability and impingement free range of motion has been observed. Purpose: The specific questions we sought to answer in our review were: (1) What are the potential advantages and disadvantages of metal-on-metal, ceramic-on-ceramic, and metal-on-polyethylene bearings? (2) What is effect that femoral head size has on joint kinematics? (3) What is the effect that large femoral heads have on bearing surface wear? Methods: A PubMed search and a review of 2012 Orthopaedic Research Society abstracts was performed and articles were chosen that directly answered components of the specific aims and that reported outcomes with contemporary implant designs or materials. Results: A review of the literature suggests that increasing femoral head size decreases the risk of postoperative dislocation and improves impingement free range of motion; however, volumetric wear increases with large femoral heads on polyethylene and increases corrosion of the stem in large metal-onmetal modular total hip arthroplasty (THA); however, the risk of potentially developing osteolysis or adverse reactions to metal debris respectively is still unknown. Further, the effect of large femoral heads with ceramic-on-ceramic THA is unclear, due to limited availability and published data. Conclusions: Surgeons must balance the benefits of larger head size with the increased risk of volumetric wear when determining the appropriate head size for a given patient.

Do Complication Rates Differ by Gender After Metal-on-metal Hip Resurfacing Arthroplasty? A Systematic Review

“…Because this intervention has expanded its indications to higher-demand patient populations, including younger and more active individuals, there is an increasing need to develop implants with improved longevity and durability. In comparison to conventional metal-on-polyethylene bearing surfaces, MoM bearing surfaces have demonstrated diminished volumetric wear while allowing larger femoral head sizes and thereby decreased dislocation risk [8,35]. This led to early adoption and high rates of use [31,32,36].…”

“…These articulations were thought to minimize wear and subsequent osteolysis, allow for larger head sizes, and decrease dislocation rates. MoM bearing surfaces also led to the reintroduction of hip resurfacing arthroplasty (HRA), a more bone-conserving procedure, which in the past had performed poorly with metal-on-polyethylene bearing surfaces [8,35]. At its height, the use of MoM THA and HRA accounted for approximately 35% of all hip arthroplasties with nearly 31% of HRA being implanted in women [36].…”

Is There a Benefit to Head Size Greater Than 36 mm in Total Hip Arthroplasty?

“…Large femoral head bearings have several advantages including a larger head-neck ratio, increased range of motion, greater jump distance, decreased impingement, and resultant increased stability [4,11,14,43]. Nevertheless, dislocation continues to be among the most common complications of THA [36,41].…”

“…Biomechanical as well as clinical data suggests improved range of motion as well as stability with increasing femoral head sizes [4,11,14]. The bulk of the clinical literature however has compared head sizes less than or equal to 36-mm, with a paucity of data evaluating larger articulations, particularly in a high risk patient population [2,15,22,24,31,32,47].…”

MRI Findings Associated with Recalled Modular Femoral Neck Rejuvenate and ABG Implants

“…For decades now, it has been known that metal-on-PE hips have generated PE wear particles secondary to linear and volumetric wear of the PE liner [27]. Further, increased volumetric wear has been positively correlated with increasing femoral head size [28], limiting the use of larger femoral heads which provide the benefits of decreased dislocation rates and greater options for restoring appropriate hip offset and leg length. These wear particles are known to generate a cellular response and release of osteoclaststimulating cytokines leading to osteolysis, implant loosening, and ultimate necessity of implant revision [29].…”