Dislocations remain a significant problem, especially after revision hip surgery. Revision of components, particularly in elderly patients with co-morbidities, can be fraught with complications. The surgeon’s options are sometimes restricted, particularly when the acetabular and femoral components are well fixed. Increased head lengths are often utilised to increase tissue tension, and thus improve stability. As a niche solution we have designed a low cost modular femoral neck extender. They are manufactured from medical grade Cobalt-Chrome, conforming to ISO 200, CE mark and EN46001 standards. Available in three incremental lengths and with different connecting Morse tapers, increases in effective neck lengths of up to 49 mms can be achieved. When both the original acetabular and femoral components are well orientated, the resultant increased tissue tension imparts stability to the hip. We present a series of five patients where we have used a femoral neck extender to achieve stability of a total hip replacement. Four patients had had multiple previous dislocations. One patient was unstable at the time of revision surgery because of a high hip centre. The average age of the patients was 72 years, and the number of previous dislocations averaged four. The average follow-up after surgery was 22 months. No patients have redislocated their hips. We present our novel femoral neck extenders as an elegant and cost effective solution to convert an unstable hip to a stable hip, especially when the patient has well fixed and orientated components not in themselves requiring revision.
Dislocations remain a significant problem, especially after revision hip surgery. Revision of components, particularly in elderly patients with co-morbidities, can be fraught with complications. The surgeon’s options are sometimes restricted, particularly when the acetabular and femoral components are well fixed. Increased head lengths are often utilized to increase tissue tension, and thus improve stability. As a niche solution we have designed a low cost modular femoral neck extender. They are manufactured from medical grade Cobalt-Chrome, conforming to ISO 200, CE mark and EN46001 standards. Available in 3 incremental lengths and with different connecting Morse tapers, increases in effective neck lengths of up to 49 mm can be achieved. When both the original acetabular and femoral components are well orientated, the resultant increased tissue tension imparts stability to the hip. We present a series of 5 patients where we have used a femoral neck extender to achieve stability of a total hip replacement. 4 patients had had multiple previous dislocations. 1 patient was unstable at the time of revision surgery because of a high hip centre. The average age of the patients was 72 years, and the number of previous dislocations averaged 4. The average follow-up after surgery was 22 months. No patients have redislocated their hips. We present our novel femoral neck extenders as an elegant and cost effective solution to convert an unstable hip to a stable hip, especially when the patient has well fixed and orientated components not in themselves requiring revision.
Whole blood metal ion levels remain a concern in those patients undergoing total hip replacement with metal bearing surfaces. The determination of baseline reference levels are essential if useful information can be gleaned from in vivo studies of functioning implants. We set out to prospectively determine chromium and cobalt metal ion concentrations in patients undergoing total hip replacement to determine reference levels of these metal ions. 100 patients with normal renal function, no occupational or environmental exposure to cobalt and chromium, and an absence of implanted metals were recruited into the study. Metal ion levels were determined using two different assay methods. Both ICP-MS (Inductively Coupled Plasma Mass Spectroscopy) and GFAAS (Graphite Furnace Atomic Adsorption Spectroscopy) are well recognized analytical techniques for the quantification of trace elements. Levels were correlated with gender, age and place of residence. There was considerable variability in whole blood metal ion levels, with the ICPMS being more sensitive and consistent than the GFAAS method. Direct comparison of concentration levels determined by the two methods revealed no significant correlation. There was no correlation with age, gender and place of residence Our findings would favour the use of the ICP-MS to determine reference levels and as a baseline for metal ion surveillance pre-operatively in patients undergoing metal-on-metal total hip replacements. We also determined that changes in whole blood metal ion levels are more significant than actual levels in patients who have undergone total hip replacement.
Whole blood metal ion levels remain a concern in those patients undergoing total hip replacement with metal bearing surfaces. The determination of baseline reference levels are essential if useful information can be gleaned from in vivo studies of functioning implants. We set out to prospectively determine chromium and cobalt metal ion concentrations in patients undergoing total hip replacement to determine reference levels of these metal ions. 100 patients with normal renal function, no occupational or environmental exposure to cobalt and chromium, and an absence of implanted metals were recruited into the study. Metal ion levels were determined using two different assay methods. Both ICP-MS (Inductively Coupled Plasma Mass Spectroscopy) and GFAAS (Graphite Furnace Atomic Adsorption Spectroscopy) are well recognised analytical techniques for the quantification of trace elements. Levels were correlated with gender, age and place of residence. There was considerable variability in whole blood metal ion levels, with the ICP-MS being more sensitive and consistent than the GFAAS method. Direct comparison of concentration levels determined by the two methods revealed no significant correlation. There was no correlation with age, gender and place of residence. Our findings would favour the use of the ICP-MS to determine reference levels and as a baseline for metalion surveillance pre-operatively in patients undergoing metal-on-metal total hip replacements. We also determined that changes in whole blood metal ion levels are more significant than actual levels in patients who have undergone total hip replacement.
