The Exeter Stem (Howmedica, UK) has been in use for over 35 years. Over the years it has undergone several modifications with the most recent being a highly polished, tapered stem in 1986. The manufacturers quote a rate of 0.0006%. In the current literature there are 16 (or less) instances of fractures of the Orthinox stem. We present a case of fracture of an Orthinox Exeter Stem 9 years after insertion. Our patient, BB, presented, aged 62, with symptoms & signs consistent with OA right hip. THR was performed through a lateral approach utilising a trochanteric osteotomy. A size 0 37.5 stem was inserted. Radiographs were very satisfactory. She suffered a post operative DVT/PTE from which she recovered uneventfully. She was independently mobile at 6 month review and was discharged at the 2 year stage pain free. Aged 71, BB presented to outpatient clinic with a several month history of generalised groin pain. She had a Trendelenberg gait. Considerable pain was experienced on axial compression of the limb. Radiographs revealed a midstem fracture with cement loosening proximally. No trauma was reported. She underwent revision surgery through a posterior approach. Acetabular component was rigidly fixed. This was revised to a pressfit Trident (Zimmer, UK) cup with screws & polyethylene liner. An extended trochanteric osteotomy was used to remove the broken stem. An uncemented Restoration (Stryker, UK) stem was inserted with a 28mm head. Post-operative recovery was unremarkable and at 6 months osteotomy has healed. The stem was sent to Stryker UK Laboratories for analysis. They reported the stem broke in fatigue with the origin on the antero-lateral surface. No material or manufacturing defects seen. Dimensionally correct. Fracture may be due to abnormal bending stresses secondary to proximal loosening and firm distal fixation. Our case demonstrates a set of circumstances that led to inevitable fatigue and stem fracture. The method of failure should reinforce the radiograph appearances that may cause concern or be acted upon

Femoral stem varus has been associated with poorer results. We report the incidence of varus/valgus malalignment of the Exeter polished, double taper design in a multicentre prospective study. The surgical outcomes at a minimum of five year and complication rates are also reported. A multicentre prospective study of 987 total hip replacements was undertaken to investigate whether there is an association between surgical outcome and femoral stem malalignment. The primary outcome measure was the change in the Oxford hip score (OHS) at five years. Secondary outcomes included the rate of dislocation and revision. The incidence of varus and valgus malignment were 7.1% and 2.6% respectively. There was no significant difference in OHS between neutral and malaligned femoral stems at 5 years (neutral, mean = 40.2; varus, mean 39.3, p = 0.465; valgus, mean = 40.9, p = 0.605). There was no significant difference in dislocation rate between the groups (p = 0.66). There was also no significant difference in revision rate (p = 0.34). This study provides evidence that the Exeter stem is extremely tolerant of varus and valgus malalignment, both in terms of outcome and complication rate

Recent NICE guidance recommends use of a well proven cemented femoral stem for hip hemiarthroplasty in management of fractured neck of femur. The Exeter Trauma Stem (ETS) has been designed based on the well proven Exeter hip stem. It has a double taper polished stem design, proclaimed to share geometry and surface finish with the Exeter hip. This study investigated the surface finish of the two stems in order to investigate the hypothesis that they were different. Two ETS and two Exeter stems were examined using a profilometer with a sensitivity of one nanometer. Macroscopic visual inspection showed that the two Exeter stems had significantly smoother surface finish than the ETS stems. The roughness average (RA) values on the ETS stems were approximately an order of magnitude higher than those of the Exeter stems, mean of 0.235μm compared with 0.025μm (p<0.0001). This difference in surface finish has implications for the biomechanical functioning of the stem. Previous change of the Exeter stem to a matt surface-finish in 1976 resulted in a significant increase in stem failure rates and an understanding of the importance of the polished surface-finish in order to function within a taper-slip philosophy. By changing the surface finish in the ETS stem, longevity of the implant may similarly be affected. Clinical results have yet to be published demonstrating this. We recommend the manufacturer reconsiders the surface finish of the ETS stem to ensure it functions as well as the Exeter primary stem with which it shares a design philosophy

The Exeter Trauma Stem (ETS) is a monoblock unipolar prosthesis currently in use throughout various orthopaedic departments. It can be a useful procedure for specialty trainees in developing modern cementation techniques in hip arthroplasty. We propose that in order for this procedure to be a valid training tool that, as well as having a standardized surgical approach and operative technique, outcomes should be easily assessed and should be similar if performed by either a trainee or consultant. All ETS procedures carried out at our institution from January 2009 until September 2011 were reviewed retrospectively. Patient demographics and operative details were recorded from patient notes. Radiographic evaluation involved the Barrack cementation grading system, Dorr's criteria, stem alignment and leg length measurement. There was no significant difference in operative time between ETS performed by consultant or by specialty trainee. On postoperative x-ray, cement mantles were Barrack grade A or B in 55.6% (trainees) versus 61.9% (consultants). Stem alignment was neutral in 50% and varus in 50% of cases for trainees, versus 28.6% and 71.4% of cases for consultants. In total, 69.2 % of patients had lengthening of the operated limb with a mean increase of 10.4mm (2–25) for trainees and 9.3mm (2–18) for consultants. Both trainees and consultants can attain a good cement mantle. However, from our results stem alignment is less accurate by trainees with half being placed in varus. Our results highlight the difficulty of obtaining correct leg length positioning with the ETS with trainees and consultants having similar discrepancies. The ETS is a useful procedure for orthopaedic trainees to attain adequate skills in modern cementation techniques with similar post-operative radiographic outcomes to consultants. The tendency for trainees to be less accurate with stem positioning could be improved with supervision or careful pre-operative templating

Exeter Trauma Stem (ETS) is one of the most common implants used for treating displaced intracapsular hip fractures in the UK. We previously performed a radiographic audit of these implants which showed good placement was difficult. This was in particular relation to leg length discrepancy (LLD). This study reviewed the clinical outcomes of these patients, in particular looking at the relation of leg length discrepancy to outcome. We performed a clinical review of patients at 3 months and 1 year post ETS for hip fracture. Oxford hip score (OHS), Trendelenberg test, Visual Analogue Score (VAS) and walking aids required were recorded. Leg length discrepancy was determined radiographically on initial post op X-ray. This was recorded as Even (+/− 5mm), 6-10mm Long and >10mm long. Seventy-two patients were reviewed at 3 months and 21 at 1 year. Mean VAS was 1.6. At 3 months 66% were Trendelenberg positive. Of those Trendelenberg positive at 3 months only 42% remained positive at 1 year. Mean OHS at 3months and 1 year was 30.8 and 32.1 respectively. On radiographic review 38 implants were Even, 24 were 6-10mm Long and 10 implants were >10mm Long. There was no correlation between leg length discrepancy and either VAS or Trendelenberg test. 45 patients ambulated independently pre-op. Of these only 8 ambulated independently post-op, 18 used a stick and 11 a Zimmer frame. There was no correlation between post operative leg length discrepancy and either Visual Analogue Score, OHS or Trendelenberg test. Mean pain score was very low. There was however almost 10% of patients with a VAS greater than 6. 80% of patients dropped one ambulatory level post-op, this is consistent with previous studies. The ETS provides good pain relief with a low complication rate in the vast majority of patients

The aim of this study was to characterise noise associated with ceramic-on-ceramic total hip arthroplasty (THA). A questionnaire was constructed to assess noise associated with THA. 116 patients responded. All had ceramic-on-ceramic hybrid THA at Glasgow Royal Infirmary between 2005 and 2007 using a Trident prosthesis and Exeter stem. Oxford Hip Questionnaires (OHS) were also completed by the patients. 16.4% of respondents reported noise associated with their ceramic hip. The vast majority reported onset at least 1 year after implantation. The most common noise types were ‘clicking’ (47%) or ‘grinding’ (42%), while ‘squeaking’ was least frequently reported (11%). Noise was most commonly brought on by bending and during sit to stand movements. No correlation was identified between the incidence of noise and any patient specific factor or demographic variable. The mean OHS at questionnaire follow-up was 39 and there was no significant difference in OHS when comparing noisy and silent hips (p=0.65). Only 1 patient limited social or recreational activities and overall patients felt the noise had minimal effect on their quality of life. Acetabular component inclination angles were compared on post-operative x-rays. There was no significant difference (p=0.51) in inclination angles of the noisy (47.1°±6.3°, range 30–57°) and silent hips (47.8°±6.1°, range 35–68°). The groups were further analysed for deviation out with the desirable inclination range of 40–45°. Of the noisy hips, a total of 73% were out with this range compared to 63% in the silent hip group. The incidence of noise within this ceramic-on-ceramic THA group did not appear to be related to patient specific factors, patient reported outcome (OHS) or acetabular inclination angles. Subjective appraisal of the noise revealed that ‘squeaking’ was not common but patients tended to report ‘clicking’ and ‘grinding’ more. The precipitation of noise with bending activities reinforces a possible mechanical cause

Introduction. There is much current debate concerning wear and corrosion at the taper junctions of large head total hip replacements, particularly metal-on-metal hips. Is such damage a modern concern or has it always occurred in total hip replacement but not previously noted. To investigate this five explanted V40 Exeter femoral stems (Stryker Howmedica) were obtained following revision surgery at a single centre. In all cases, the 24–26 mm femoral heads were still attached. Hypothesis. In conventional ‘small head’ modular hip prostheses such as the Exeter, negligible wear and corrosion is seen at the taper junction of explanted devices. Methods. The articulating surface and the taper junction of each femoral heads was measured using a Mitutoyo LEGEX322 co-ordinate measuring machine (CMM) In each case a wear map was generated and the wear volume from the contact surface was calculated using a bespoke MATLAB program. The accuracy of such measurements has been previously shown to be within 0.5mm3. Results. Wear analysis of the articulating surfaces found unworn surfaces with each femoral head having less than 1 mm. 3. volumetric wear. All tapers had minimal wear with volumetric wear of less than 0.5 mm. 3. . Discussion and Conclusion. The wear volumes measured fall within the CMM measuring accuracy of 0.5mm. 3. Furthermore all tapers showed low wear volumes indicating that the taper junction had functioned correctly and distributed the load across the length of the truneon. Significance. This work adds to the growing evidence that taper problems in modern hip prostheses are associated with increasing head diameter and smaller taper dimensions

In recent years the majority of X-ray departments have moved to a digital format of recording and archiving radiographs. These digital images (as with previous ‘films’) have a built in magnification factor (variable with each patient), which, may cause errors in templating for joint replacement surgery. Placing a marker of known size at the same level as the joint in question allows calculation of the magnification. This may help to restore hip offset in total hip replacement. To establish the magnification factor for digital radiographs taken in our unit. To assess the usefulness of marker images in accurate preoperative templating. Preoperative marker radiographs were identified retrospectively. The apparent size of the marker was measured on digital image. This value was used to calculate the magnification of the image. The scaled X-ray was up loaded to a digital templating software programme. This software uses a ‘scaling tool’ to calculate the magnification of the image. The hip joint templating tool was the used to calculate the offset of the proximal femur, this was performed with the calculated magnification and also an assumed magnification of 120%. The recommended offset of Exeter V40 stem was noted for both values. Images were identified for 40 patients with markers. The average magnification was 122% for both PACS and Orthoview with a range 113% – 129% and a standard deviation of 4%. The median value for magnification was 120%. The average change in offset between calculated and estimated magnification was 1.275mm with a maximum change of 3mm. In two cases this difference resulted in a change in the recommended offset (5%). The use of marker radiographs is widely described. In this small series the magnification is the same as previously reported in other studies. The difference in offset between calculated and estimated magnification was relatively small and caused a change in the recommended offset in only two patients. Variation in the use of the templating tool in our software can produce a much greater change in offset. Marker radiographs will only be useful as part of a standardised method of pre-operative templating

The use of impaction bone grafting during revision arthroplasty of the hip in the presence of cortical defects has a high risk of post-operative fracture. Our laboratory study addressed the effect of extramedullary augmentation and length of femoral stem on the initial stability of the prosthesis and the risk of fracture.

Cortical defects in plastic femora were repaired using either surgical mesh without extramedullary augmentation, mesh with a strut graft or mesh with a plate. After bone impaction, standard or long-stem Exeter prostheses were inserted, which were tested by cyclical loading while measuring defect strain and migration of the stem.

Compared with standard stems without extramedullary augmentation, defect strains were 31% lower with longer stems, 43% lower with a plate and 50% lower with a strut graft. Combining extramedullary augmentation with a long stem showed little additional benefit (p = 0.67). The type of repair did not affect the initial stability. Our results support the use of impaction bone grafting and extramedullary augmentation of diaphyseal defects after mesh containment.

The role of vacuum mixing on the reduction of porosity and on the clinical performance of cemented total hip replacements remains uncertain. We have used paired femoral constructs prepared with either hand-mixed or vacuum-mixed cement in a cadaver model which simulated intra-operative conditions during cementing of the femoral component. After the cement had cured, the distribution of its porosity was determined, as was the strength of the cement-stem and cement-bone interfaces.

The overall fraction of the pore area was similar for both hand-mixed and vacuum-mixed cement (hand 6%; vacuum 5.7%; paired t-test, p = 0.187). The linear pore fractions at the interfaces were also similar for the two techniques. The pore number-density was much higher for the hand-mixed cement (paired t-test, p = 0.0013). The strength of the cement-stem interface was greater with the hand-mixed cement (paired t-test, p = 0.0005), while the strength of the cement-bone interface was not affected by the conditions of mixing (paired t-test, p = 0.275). The reduction in porosity with vacuum mixing did not affect the porosity of the mantle, but the distribution of the porosity can be affected by the technique of mixing used.

Impacted morsellised allografts have been used successfully to address the problem of poor bone stock in revision surgery. However, there are concerns about the transmission of pathogens, the high cost and the shortage of supply of donor bone. Bone-graft extenders, such as tricalcium phosphate (TCP) and hydroxyapatite (HA), have been developed to minimise the use of donor bone. In a human cadaver model we have evaluated the surgical and mechanical feasibility of a TCP/HA bone-graft extender during impaction grafting revision surgery.

A TCP/HA allograft mix increased the risk of producing a fissure in the femur during the impaction procedure, but provided a higher initial mechanical stability when compared with bone graft alone. The implications of the use of this type of graft extender in impaction grafting revision surgery are discussed.