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Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XXXVIII | Pages 40 - 40
1 Sep 2012
Oliver MC Railton P Faris P Kinniburgh D Parker R MacKenzie J Werle J Powell J
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Purpose

Elevated blood metal ions are associated with the early failure of the Hip Resurfacing Arthroplasty. The aim of this study was to analyse our prospective database of Hip Resurfacing Arthroplasty patients, to independently review the outliers with elevated blood metal ions and to determine whether a screening program would be of value at our institution.

Method

In 2004 a ten year prospective longitudinal study was set up to evaluate the clinical effectiveness and safety of Metal on Metal Hip Resurfacings in young, active adults with degenerative hip disease.

Six hundred and four patients have enrolled in this multi-surgeon prospective study with strict inclusion criteria for Hip Resurfacing Arthroplasty. All have received the same implant design. All have completed validated functional outcome questionnaires at baseline, three and six months, then annually. A sub-cohort of 196 patients underwent whole blood chromium and cobalt analysis at the same time periods.

Metal on metal bearings have a running in period of a minimum of six months before a steady state wear pattern is attained. We chose five parts per billion for Cobalt or Chromium as our threshold value. This value corresponds to the workplace exposure limit in the United Kingdom to Cobalt in whole blood. Therefore patients with ion levels greater than five parts per billion after six months were recalled for independent review, including further metal ion analysis.


Orthopaedic Proceedings
Vol. 90-B, Issue SUPP_III | Pages 454 - 454
1 Aug 2008
Fletcher RJ O’Brien A Oliver MC Rajaratnam S Southgate C Tavakkolizadeh A Shepperd JAN
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We report a consecutive series of 200 patients who underwent Dynesys flexible stabilisation in the management of intractable lower back pain.

Methods: Patients were only accepted for the study if exhaustive conservative management had failed. They underwent operation between September 2000 and March 2003. Patients were divided into two groups:

Group 1 - Cases where implantation was used as an adjunct to other procedures including decompression, discectomy, or posterior lumbar interbody fusion. (32 male, 36 female, Mean age 56years (range 31–85)).

Group 2 - Patients with back pain and/or sciatica in which no other procedure was used. (65 male 67 female, Mean age 58years (range 27–86))

All patients were profiled prospectively using the Oswestry Disability Index (ODI), SF36 and Visual Analogue Scale (VAS). Patients were reviewed post-operatively using the same measures at 3, 6 & 12 months, and yearly thereafter. Follow-up was 95% at 2 to 5 years.

Results: Group 1 – Mean ODI fell from 54 pre-op to 24 at four years

Group 2 – Mean ODI fell from 49 pre-op to 28 at four years

Similar trends were observed in both groups with a fall in VAS and improvement in SF36.

Discussion: Indications can only be defined following clinical outcome. Perceived indications were based on contemporary understanding of the biomechanical effects of the construct. Further investigation of these variables is clearly desirable. Screw failures (15%) have detracted from the overall success. The virtue of flexible stabilisation over fusion includes avoidance of domino effect, reversibility and possible healing of a painful segment. The key issue is whether it is as effective and this requires prospective randomised controlled investigation, both against fusion, and conservative management. We feel our results in this difficult group of patients are reasonable and continue to use it in our practice.