CLINICAL EXPERIENCE WITH CURRENT SURFACE ARTHROPLASTY
ON THE HIP - A BELGIUM EXPERIENCE

Koen A. DE SMET, M.D.
ANCA CLINIC
HEUSDEN, BELGIUM

The association between high volumetric wear, polyethylene particulate debris, osteolysis and loosening in total hip arthroplasty in young patients is well recognized and understood. This has resulted in an interest in alternative bearings, particularly in young and active patients. At our service, since the year 2000, only alumina ceramic bearings or metal-on-metal bearings are used in patients under the age of 75.

Metal-on-metal resurfacing is becoming more and more widely used all over the world. The history of failures with the Charnley teflon-on-teflon and the Wagner/Tharies metal-on-polyethylene prostheses makes resurfacing very controversial. With the introduction of a metal-on-metal resurfacing prosthesis and a refined instrumentation, it should be possible to avoid the problems of the earlier designs.

From September 1998 till April 2004 we performed 1,114 metal-on-metal Birmingham Hip Resurfacings (MMT, UK; Smith and Nephew, Memphis US). Other resurfacings are introduced on the Belgian market;

• Recap (Biomet, Warsaw US)

• Conserve Plus (Wright Medical; Arlington US)

• Durom (Zimmer, Warsaw US).

Small numbers of other resurfacings were performed, but technical and metallurgic differences in these devices make a choice very difficult. Metallurgy, low and high carbide-content, roughness, roundness and heat treatments become discussion points in our orthopaedic practice.

The results achieved with the new metal-on-metal resurfacing are starting to be published. Theoretical advantages are less bone destruction, less bone resection, normal femoral loading, and avoidance of stress shielding, maximum proprioceptive feedback and restoration of normal anatomy. In addition reduced risk of dislocation, less leg lengthening and easier revision should convince us to perform metal-on-metal resurfacing. If infection occurs a one stage revision and a less contaminated region is certain.

Beside these advantages of resurfacing, there is also the subjective "better feeling" and having a more "normal" joint then a total hip joint arthroplasty. This can be illustrated with functional scores and activity in comparison with a matched group of ceramic-on-ceramic total hip arthroplasty.

It is the author's conviction this is partially the result of the use of the large diameter femoral head; the "big ball effect".

All our patients are followed prospectively. Only 3 patients (4 prostheses) were lost to follow-up because they had died. All possible indications were included in our series. Only severe osteoporosis and to old patients were excluded. (Mean age 49.66, range 16 - 75)

The clinical results are excellent!  None of the early problems associated with the metal-on-polyethylene resurfacing are encountered.

Today, the complication rate is very low and only 3 revisions took place (1 low grade infection, 1 avascular necrosis and 1 femoral neck fracture). There were 2 dislocations (one after 4 months, one 2 years post-surgery). With further follow up a higher rate of complications and revisions is expectable.

Clinical perceptions/sensations in patients like creeping or peeping noises, clocking or clucking in the prosthesis, and groin pain because of local conflict with the implant are new features that can occur in resurfacing.

The first 250 cases (follow up 2 - 5 year; mean 2.61) were scored clinically and functionally. The outcome shows high Harris Hip scores (HHS total averaged 97.24 (41-100)) and a high percentage of strenuous activity (60.53; ADL 38.60; independent 0.88%).

Failures in resurfacing due to a technically demanding new procedure are a fact, and this potential problem is illustrated. Revision surgery in these cases however is in most cases restricted to primary arthroplasty.

De Smet K.A.. Pattvn C.. Verdonk R.. Early results of primary Birmingham hip resurfacing using a hybrid metal-on-metal couple. Hip International 2002; 12: 158-162.

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12/19/2004

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