Mid-Term Results of a Modern Metal-on-Metal Hip Resurfacing Prosthesis Krikler S & Nelson R (2005) EFORT Oral presentation       A prospective single surgeon consecutive series of primary resurfacing implantations in a UK district general hospital setting. The surgeon resurfaces a range of patients including challenging cases as, in the event of failure, revision to a THR is relatively unchallenging. 345 resurfacings were performed (294 patients, 51 bilaterals), no cases lost to follow-up, mean age at operation 52 years (21-74 years) & 65% were male. There were 11 failures and 3 non-implant related deaths.     Mean follow-up was 29 months (3-79 months) with a Kaplan-Meier survivorship of 94% at 7 years post-op.   Of the re-operations there were 5 fractured necks of femur (all within 3 months of the index operation), 3 aseptic cup loosenings, 2 femoral head collapses and 1 joint infection. The fractured necks of femur and head collapse cases were revised to a stemmed large headed THR articulating with the retained metal acetabular component. The 3 loose cups were revised to a larger size to articulate with the original resurfacing femoral head and the single infected joint was revised to a traditional THR. This series is one of the longest using a currently available device with encouraging medium term results. The revision rates fall within the agreed national standards and reflect the challenging nature of the cases involved. The user remains cautiously optimistic about the long term results of this resurfacing device.       Hydroxyapatite-Coated Femoral Implants in Metal-on-Metal Resurfacing Hip Arthroplasty Lilikakis AK, Vowler SL & Villar RN (2005) Orthop Clin North Am. Apr; 36(2):pp215-22 (ix)       The authors report preliminary results of an uncemented, hydroxyapatite-coated femoral implant for metal-on-metal hip resurfacing. The survival rate of 70 implants after at least 2 years follow-up was 98.6%, with an excellent clinical outcome. There have been no femoral fractures, aseptic loosening, or radiolucencies around the stem. Thinning of the femoral neck at the inferomedial cup-neck rim has been a frequent radiological finding but with no clinical implication so far. Longer follow-up is needed to confirm the results.         Internal Interim Summary of Multi-Centre Clinical Audit Results Krikler S, Bishay M, Pring D, Spencer R & Nelson R (2005) Internal Corin Data Summary       Outcomes data was prospectively collected on a web based Outcome Measures Database (OMD). 4 UK surgeons collected clinical and radiological measures annually.  593 primary hip resurfacings were performed between Sept 1997 and Jan 2005 including 86 bilaterals. Mean age at surgery was 52 years with a mean follow-up of 84 months. At 7 years the Harris hip score mean value was 83 with a mean flexion at last review of 99 degrees. There were 14 revisions- 5 fractured neck of femurs, 5 aseptic cup loosenings, 2 collapsed femoral heads, 1 recurrent dislocation and 1 infection giving a Kaplan-Meier survivorship of 94% (+5.2) @ 6 to 7 years post-op. The 5 fractured necks of femur and 2 collapsed femoral heads were revised to large head stemmed devices retaining the original cup. The 5 cup loosenings were upsized retaining the same femoral heads. The recurrent dislocations and infection cases were both revised to traditional total hip replacements. No subsequent failures of these 14 revisions have been recorded. With acceptable post-op Harris Hip scores, hip flexion and survivorship results the participating surgeons remain cautiously optimistic regarding the long term performance of the Cormet hip resurfacing system in this young, demanding patient group.       Development, Validation and Multi-centre Follow-up of a Modern Metal-on-Metal Hip Resurfacing Prosthesis Nevelos J, Nelson R, Shelton J, Krikler S, Bishay M, Banan H, Pring D, Richardson J & Spencer R (2004) AAOS Scientific Exhibit SE005       The original device was the McMinn Resurfacing Hip (1991-1996) which was relaunched as the Cormet resurfacing hip in 1997. Cormet is available in an increased range of sizes with the cup coated in plasma sprayed titanium overlaid with hydroxyapatite. Cups are available as pegged or pegless and for the dysplastic hip. The IRC in Biomaterials, Queen Mary, University of London conducted two studies with Cormet. They looked firstly at the effect of heat treatment of the device under standard and severe conditions then at how bearing diameter affects bearing lubrication properties. Heat treatment is applied to orthopaedic devices to improve their surface wear characteristics and the study showed that there was no significant difference in the wear between heat treated and non-heat treated devices under standard and severe test conditions. The second study showed that bearing size did have an effect on the wear characteristics of the bearing with the larger diameter bearings having a lower long term wear rate than conventional 28mm bearing. Multi-Centre follow-up of prospectively collated data from September 1997 to November 2003 covers 342 patients, average age at op 55.5 years, 41 bilaterals, mean follow up 17 months. Mean modified Harris score at 5 years as a percentage is 86% with 13 revisions giving a Kaplan-Meier survivorship of 96% @ 7 years. Metal ion release data was collected via a standardized blood collection technique to ensure no metallic contamination. 39 patients with 7 bilateral cases followed up to 7 years. All patients had elevated levels of Cobalt and Chromium immediately post-op although the extent of increase was highly variable between individuals. The data showed a marked trend of decreasing ion levels after 4 years consistent with running-in wear. Patients <40 had slightly higher ion levels than those >60, perhaps linked to age related activity levels.       Development, Validation and Multi-centre Follow-up of a Modern Metal-on-Metal Hip Resurfacing Prosthesis Nevelos J, Ahmad Y, Shelton J, Krikler S, Bishay M, Banan H, Pring D, Richardson J & Spencer R. (2003) AAOS Scientific Exhibition Abstract       Modern metal-on-metal hip resurfacing began in the early 1990’s with the McMinn Resurfacing Hip. Released in 1997, the Cormet Resurfacing Hip is a development of the McMinn hip. In addition to clinical follow-up wear testing was carried out with the effects of metallurgy and bearing diameter tested under standard and severe conditions. Metal ion release, a concern with all metal-on-metal bearings, is also analysed in a 5 year study. Between September 1997 and November 2002 209 primary resurfacings took place in six centres. 207 patients were followed up with no loss to follow-up. The average age at operation was 52.9 years. There were 2 bilateral cases and 5 revisions with a revision rate of 2.3% at 5 years. Mean follow-up was 32.5 months with an average Harris hip score at last review of 78. Survivorship for Cormet was 98.9 at 3 years and 97.7 at 5 years. Wear testing has shown that heat treatments do not increase wear and that larger bearings have lower wear than 28mm bearings. Also it was demonstrated that metal ion levels decrease over time. This device has been validated in vitro and the medium term results are very encouraging.       Early Results of Total Hip Resurfacing via an Antero-lateral Approach Bishay M (2003) EFORT Oral presentation       Data collated prospectively on the use of Cormet is presented by a single user from Sept 1999 to July 2002. All implantations were undertaken via an antero-lateral modified Hardinge approach. 102 resurfacings were performed in 98 patients with an average age of 42 years at operation. Mean pre-op Harris Hip score was 58. Postoperatively 91 patients had a Harris Hip Scores >92 and the remaining patients had a Harris Hip score between 84 and 90. All working patients returned to employment within 8 weeks, the self employed within 3-4 weeks. There was 1 cup dislodgement at 3 months post-op, which was subsequently revised to a larger size. The antero-lateral approach is quite adequate for exposure and preparation and implantation of the resurfacing component. Hip resurfacing should be considered as a treatment option in young adults with arthritic hips. However cases must be monitored for possible future complications particularly those related to metal ion levels in young females of child bearing potential.         Interim Clinical Results of the Cormet Resurfacing Hip       In 1997 the McMinn Resurfacing hip was redeveloped and relaunched as the Cormet Resurfacing hip with the critical design features being retained. Clinical results of the McMinn Resurfacing hip have been published previously with a 97.4% survivorship at 6-7years. 7 surgeons followed the Cormet Hip Resurfacing in the UK from September 1997 to May 2002. 191 cases were implanted with mean follow-up of 15.5 months and the average of the recipient was 51.7 years. The Kaplan-Meier survivorship survival rate was 98.83% at 49 months and 97.2% at 3 years. There were 5 failures in this series - 2 fractured necks of femur, 1 dislocation and 2 acetabular loosenings. The Cormet Resurfacing hip system offers an attractive solution for the treatment of hip arthritis in the younger, more active patient group.       Metal-on-Metal Resurfacing of the Hip with Hybrid Fixation - Our First 100 Consecutive Cases McMinn DJW, Pynsent PB, De Cock CAEM, Isbister ES & Treacy RBC. (2000) SICOT Oral Presentation       The authors wished to determine if metal-on-metal resurfacing arthroplasty of the hip performed better than historic metal on polyethylene resurfacing designs. Clinical and radiological assessment of the first 100 of 811 hybrid resurfacings was undertaken with a patient follow-up of 45-61 months. Ave age at op was 48.5 years. All procedures were conducted via a posterior approach without trochanteric osteotomy. Clinical and radiological outcomes are excellent with no cases of dislocation, femoral neck fracture, avascular necrosis or osteolysis. There was one infection and one femoral loosening. Early to medium term assessment indicate much better outcomes than historical metal/polyethylene resurfacings.       Results of Metal-on-Metal Hip Resurfacing McMinn DJW, Pynsent PB, De Cock CAEM, Isbister ES & Treacy RBC (2000) JBJS 82-B (Orthopaedic Proceedings Suppliment II)       From March 1994 1085 consecutive resurfacings were performed by the same surgeon, 294 were McMinn Resurfacings and 791 were Birmingham Hip Resurfacings. The mean age at operation was 53 years. Of the 294 McMinn Resurfacings there were 5 failures- 2 infections, 2 cup loosenings and one femoral head collapse in a patient with pre-existing AVN. Of the 791 Birmingham Hip Resurfacings there were 5 failures- 4 femoral neck fractures and one collapsed femoral head from AVN. The cumulative survivorship in this group was 98% @ 5-6 years. Analysis of the migration of the cup was undertaken using the Nunn method. Migration of the resurfacing cup was 0.015mm/yr N.S.D. to Harris Galante cups. On the femoral side migration of the cemented resurfacing component was compared to that of the Exeter cemented stem using the Walker method. The resurfacing components migrated significantly less than the Exeter components, 0.031mm/yr and 0.098 respectively (p=0.022). Of 206 Birmingham patients (27 bilateral) surveyed the mean time taken to return to work post-operatively was 7.1 weeks and 169 patients were participating in recreational sport. Hip resurfacing using metal-on-metal hybrid fixed components offers a viable treatment for the young patient with hip arthritis.