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Promising results seen with large-diameter heads for MoM THA
Cicek H. Acta Orthop Belg. 2010. 76(6):758-765.
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A retrospective study examining metal-on-metal total hip arthroplasty performed with large-diameter femoral heads shows better Harris Hip scores and significant improvements in range of motion. However, Turkish researchers call for longer follow-up data to support these results.
The study included 32 women and 22 men who underwent primary cementless procedures using large-diameter heads. The researchers followed the patients for a mean of 48.6 months.
In addition to discovering improved function, the researchers found a significant correlation between postoperative Harris Hip score and age; with younger patients having better results. The study revealed three cases of 1-mm-thick radiolucency which the researchers detected in asymptomatic acetabula. One hip was revised due to displacement, according to the study abstract. The researchers also found heterotopic ossification in one hip. Overall, they discovered no cases of loosening, deep infection or dislocation.
“Although the inherent stability and the functional results of large anatomical heads are encouraging, longer follow-up data and larger series are essential to evaluate the real advantages of this type of prosthesis over conventional femoral heads,” the researchers wrote.
Metal-on-metal total hip arthroplasty with large-diameter femoral heads has the advantages of maintaining better stability, minimizing the risk of postoperative dislocation, acquiring increased range of motion and expecting a low wear of metal-on-metal articulation for longer prosthesis survival. But concerns about metal-on-metal surfaces, particularly on the release of metal ions and their adverse results in young and active patients, have been increasing.
Recently, the new generation of ceramic-on-ceramic total hip arthroplasty with 36 mm head has made competitive results in this patient population.
If patients have the indication to use ceramic-on-ceramic bearing, we now do not recommend use of metal-on-metal implant.
– Weidong Xu, MD
Department of Orthopedics
Changhai Hospital
Shanghai
Disclosure: He has no relevant financial disclosures.