As knowledge of the performance and outcomes of hip arthroplasty with
metal-on-metal bearings increases, the guest commentaries below and
here revisit the many issues surrounding this type of
arthroplasty. We hope these opinion pieces will provide important information
to help readers arrive at their own answers to the many outstanding questions
regarding these treatments.
We still lack an ideal solution for the younger patient with hip
arthritis who tends to be a more active individual demanding more of their
Polyethylene wear is a major concern as younger patients often
attempt to maintain/regain their pre-operative level of activity.
Hip resurfacing has long been recognized as an attractive
concept particularly in patients who are likely to need revision hip
replacements in their lifetime. Due to improvements in materials, design, and
metal-on-metal (MoM) hip resurfacing arthroplasty gained
popularity in the last decade with perceived advantages of bone conservation
and relative ease of revision to a conventional
total hip replacement (THR) if it fails.
Hip resurfacing preserves proximal femoral bone stock, retains
proprioception, optimizes stress transfer to the proximal femur and, because of
the large diameter of articulation, offers inherent stability and optimal range
of movement. This leads to a lower risk of dislocation. Intra-operatively the
absence of femoral canal reaming in hip resurfacing theoretically reduces the
risks of fat embolism to the lung.
Shown are bilateral hip resurfacings using
the Smith & Nephew Birmingham Hip Resurfacing System.
Images: Haddad F
Although modern hip resurfacing has recognized early complications, such
as femoral neck fractures and avascular necrosis of the head, the early and
medium term results were encouraging. The technique attracted a great deal of
media attention and was rapidly taken up.
MoM hip resurfacing was initially used as an option in very active
people with advanced hip disease who would otherwise receive and are likely to
outlive a conventional primary THR. Initial success led to a widening of the
indications and to the use of resurfacing cups with standard femoral stems and
However, over the past few years concerns have been raised in relation
to reports of catastrophic soft tissue reactions resulting in implant failure
and associated complications. One implant has recently been withdrawn and hip
arthroplasty registries suggest worrying trends for others.
Consider merits of resurfacing
An intraoperative view of MoM disease
within the capsule.
We must be careful not to throw out the baby with the
bathwater. The concerning data in relation to stemmed/modular large-head
MoM hips (>36 mm) is likely to be related to the taper junction/trunnion and
to be a different failure mode than for resurfacing. Resurfacing failures seem
instead to relate to poor technique including component malposition, use in
unsuitable patients whose anatomy dictated malposition/edge bearing, and the
wide introduction of some unsatisfactory implants with sufficient in vivo
evaluation. The evidence from the literature is clear that all medical devices
depend on appropriate surgical technique and patient selection. It appears that
these simple rules affect the success of MoM hips more than other hip types.
Hip resurfacing remains a viable successful operation in younger males
with appropriate anatomy. Examples of cases associated with increased failure
rates include cup inclination angles greater than 55°, use of the procedure
in women and in those with small head sizes. Resurfacing has some additional
risk factors because of the retained head and neck. Thus, clinical results
currently best support the use of a resurfacing implant with a long track
record, positioned with a cup inclination angle of 45° or less and version
angle of 20° or less, to treat a man aged less than 65 years suffering from
osteoarthritis with a well-covered acetabulum and cam-shaped hips. In this
cohort, there may well still be advantages to resurfacing.
Hip function studied
We undertook a prospective randomized study of cementless THR with a
32-mm metal-on-polyethylene bearing versus MoM hip resurfacing in young adults
under the age of 55 years. Eighty patients were enrolled between 1999 and 2002.
All the patients have been followed clinically and radiographically up to a
minimum follow-up of 8 years and a mean of 10.1 years. In this cohort, there
have been no failures in the MoM articulation group and there has only been one
dislocation in the total hip group. A higher proportion of hip resurfacing
patients were running and involved in sport and heavy manual work after 5
years, 8 years and 10 years. The University College Hospital functional hip
score showed significantly higher function in hip resurfacing patients compared
with hip replacement patients; this was maintained at 1 year, 5 years and 8 to
10 years. We continue to use hip resurfacing in such patients.
Our knowledge of MoM bearings and their behavior is evolving rapidly.
There are currently major question marks over large-head MoM THR. However,
current data suggest that an appropriate surgical technique for hip resurfacing
in an appropriately selected cohort of patients using appropriate implants is
associated with a low incidence of adverse soft tissue reactions and good
Recent controversy regarding the recall of the ASR (DePuy Orthopaedics)
resurfacing prosthesis and in relation to trunnion related failures of large
head MoM prostheses have generated a great deal of uncertainty. Nevertheless,
devices that preserve bone stock, facilitate later revision and potentially
allow better functional recovery are attractive. MoM hip resurfacing remains a
good option in well-selected patients with appropriate anatomy under the care
of experienced and skilled surgeons.
- Amstutz HC, Grigoris P, Dorey FJ. Evolution and future of surface
replacement of the hip. J Orthop Sci. 1998; 3:169-186.
- Australian Orthopaedic Association National Joint Replacement
Registry. Annual Report. Adelaide, Australia: AOA; 2010.
- Daniel J, Pynsent PB, McMinn, DJ. Metal on metal resurfacing of the
hip in patients under the age of 55 with osteoarthritis. J Bone Joint
Surg Br. 2004;86:177-184.
- De Haan R, Pattyn C, Gill HS, et al. Correlation between
inclination of the acetabular component and metal ion levels in metal-on-metal
hip resurfacing replacement. J Bone Joint Surg Br.
- Grigoris P, Roberts P, Panousis K, Bosch H. The evolution of hip
resurfacing arthroplasty. Orthop Clin North Am.
- Haddad FS, Bull J. Hip resurfacing has superior sustained
functional outcomes when compared to total hip arthroplasty. Proceedings of the
75th Annual American Academy of Orthopaedic Surgeons Meeting. p. 428. San
- National Institute for Health and Clinical Excellence guidelines.
Hip disease - metal on metal hip resurfacing (TA44). June 2002.
- Fares Haddad, MCh(Orth), FRCS, can be reached at +44 20 7908 2251;
- Harry Benjamin-Laing, BSc(Hons), MBChB(Hons), MRCSEd, can be
reached at +44 20 3447 9413; email:
- Haddad and Benjamin-Laing are at the Department of Trauma &
Orthopaedic Surgery, University College Hospital, 235 Euston Road, London, NW1
2BU United Kingdom.
- Disclosures: Haddad is a paid consultant to Corin, Smith
& Nephew and Stryker. Benjamin-Laing has no relevant financial disclosures.