Clinical Evidence

The BIRMINGHAM HIP^* Resurfacing (BHR^*) has demonstrated exceptional clinical results worldwide. High survival rates of 98% or better were achieved in clinical centres around the world. ^1,2,3,4,5

In addition, the recently published Australian Orthopaedic Association National Joint Replacement Registry reports BHR as having the lowest revisions per 100 observed 'component' years when comparing all resurfacing implants used in the country. ⁶

Other clinical studies have focused on predictive measurements to project long-term survivorship of the resurfaced femoral head. Researchers at the University of Oxford, England used roentgen stereophotogrammetric analysis (RSA) to measure the stability of the femoral head. At 24 months, the total three-dimensional migration of the head was not statistically significant at 0.2mm.

Previous studies have shown that implants that loosen quickly have rapid early migration. According to the authors, these results suggest the BHR femoral component is an inherently stable device predicting a good long-term performance. ^7,8

It is widely accepted that the Bone Mineral Density (BMD) of the proximal femur generally decreases after cementless THA using standard designs of femoral components. However, BMD studies conducted at Osaka University, Japan reported the post-operative BMD in the proximal femur was significantly greater in patients treated with the BHR system compared to the conventional system. The patients treated with the BHR system demonstrated preservation of the BMD in Gruen zone 1 and an increase in zone 7.

These results suggest that transfer of load to the proximal femur was more normal after surface replacement with the BHR system. These findings also show the BHR system preserves the bone stock of the proximal femur after surgery. ⁹

Survivorship: Results Comparable Globally

Author		Site		n		Survival		Follow Up (months)
Shimmin et al 1		Melbourne		231		99.14 %		33 (25-52)
Ebied et al 2		Liverpool		100		99.00 %		17 (mean)
De Smet et al 3		Ghent		200		99.50 %		6 - 42
Treacey et al 4		Birmingham		144		98.00 %		60 (minimum)
McMinn et al 5		Birmingham		1,626		98.4 %		60 (minimum)

Australian Joint Registry. Published Figures

Australian Nation Joint Registry Annual Report 2006 (Clinical Results)6 :
Resurfacing Hip systems requiring revision.

Resurfacing Head		Number Revised		Total Number		% Revised		Observed Component Years		Revisions per 100 Observed Component Years
ASR		18		503		3.6		446		4.0
Adept		0		19		0.0		3		0.0
BHR		126		5799		2.2		13487		0.9
Conserve Plus		2		48		4.2		82		2.4
Cormet 2000		14		333		4.2		649		2.2
Durom		12		423		2.8		451		2.7
Recap		2		41		4.9		41		4.9
Total		177		7205		2.5		15179		1.2

Additional Radiographic Studies

Autor		Type		n		Findings
Glyn-Jones et al 7		RSA		22		Femoral migration < 0.2mm at 2 Years
Itayem et al 8		RSA		20		Vertical migration femoral component < 0.01mm at 5 Years Vertical migration acetabular component < 0.03mm at 5 Years
Kishida et al 9		BMD		26		BMD preserved / improved in proximal femur at 2 years