Background: -The excellent survivorship of the Exeter stem is thought, in part, to be related to limited subsidence of the stem within the cement mantle due to it’s polished, double taper design. The subsidence within the cement mantel is seen as a necessary part of the optimum transmission of load into the cement and hence the bone. The long Exeter stems do not all mimic the same double taper geometry as the standard 150mm stem. There is no published evidence that the long stem Exeter implant exhibits the same subsidence within the cement mantel as the standard stem.

Method: -Using digitised x-rays and a computer aided design package we measured the subsidence of 35 standard Exeter stems and 40 long stems. Measurements were taken from the initial postoperative radiograph and repeated at intervals up to 5 years. The long stem implants were all used in cemented revisions without the use of impaction grafting. None of the implants exhibited radiological loosening at the last follow-up x-ray available.

Results: -The analysis of the standard length stems illustrated that the method was able to demonstrate subsidence within the cement mantel, at rates comparable to that in the published literature. However the long stem implants exhibited a significantly reduced subsidence rate (at 12 months P< 0.0001).

Conclusion: -This study suggests that the subsidence of the long stem Exeter implant does not mirror that of the standard length stem. The loss of the fully tapered geometry of the longer stem Exeter implants may account for the reduced subsidence of the implant at the prosthesis/cement interface. The longevity of the standard length stem is, to a certain extent, thought to arise from a limited subsidence at this interface. This raises concerns that the survivorship of the longer stem implants should not be extrapolated from the excellent results of its shorter length relation.

Retention of well fixed bone cement at the time of a revision THA is an attractive proposition, as its removal can be difficult, time consuming and may result in extensive bone stock loss or fracture. Previously reported poor results of cemented revision THA, however, have tended to discourage Surgeons from performing ‘cement in cement’ revisions, and this technique is not in widespread use.

Since 1989 in Exeter, we have performed a ‘cement within cement’ femoral stem revision on 354 occasions. An Exeter polished tapered stem has been cemented into the existing cement mantle on each occasion.

Clinical and radiological follow up of 5 years or longer is available for 156 cases. On no occasion has a cement in cement femoral stem had to be re-revised during this time for subsequent aseptic loosening.

This has encouraged the refinement of this technique, including the development of a new short stem designed specifically for cement within cement revisions. This stem is designed to fit into an existing well fixed cement mantle of most designs of cemented femoral components or hemi-arthroplasties, with only limited preparation of the proximal mantle required. The new stem greatly simplifies cement in cement revision and minimises the risk of distal shaft perforation or fracture, which is otherwise a potential hazard when reaming out distal cement to accommodate a longer prosthesis.

Retention of well fixed bone cement at the time of a revision THA is an attractive proposition, as its removal can be difficult, time consuming and may result in extensive bone stock loss or fracture. Previously reported poor results of cemented revision THA, however, have tended to discourage Surgeons from performing “cement in cement” revisions, and this technique is not in widespread use.

Since 1989, we have performed a cement within cement femoral stem revision on 354 occasions. The indications for in cement revision included facilitating acetabular revision, replacement of a monoblock stem with a damaged or incompatible head, revision of hemiarthroplasty to THA, component malposition and broken stem. Cement in cement revision was only performed in the presence of well fixed cement with an intact bone-cement interface. An Exeter polished tapered stem was cemented into the existing cement mantle on each occasion.

Follow up of 5 years or longer is available for 175 cases, and over 8 years in 41. On no occasion has a cement in cement femoral stem had to be re-revised during this time for subsequent aseptic loosening. Advantages include preservation of bone stock, reduced operating time, improved acetabular exposure and early post operative full weight bearing mobilisation. This technique has not been used for 1 stage revision of infection.

This experience has encouraged the refinement of this technique, including the development of a new short stem designed specifically for cement within cement revisions. This stem is designed to fit into an existing well fixed cement mantle of most designs of cemented femoral component or hemi-arthroplasty, with only limited preparation of the proximal mantle required. The new stem greatly simplifies cement in cement revision and minimises the risk of distal shaft perforation or fracture, which is otherwise a potential hazard when reaming out distal cement to accommodate a longer prosthesis.

Total hip replacements (THRs) provide pain relief and improved function to thousands of patients suffering from end-stage osteoarthritis, every year. Over 800 different THR constructs were implanted in the UK in 2017. To ensure reliable implants are used, a NICE revision benchmark of 5% after 10 years exists. Given the 10-year cumulative mortality of patients under 55 years of age receiving THRs is only 5% and that a recent study suggests 25-year THR survival of 58%, we aim to produce revision estimates out to 30 years that may guide future long-term benchmarks.

The local database of the Princess Elizabeth Orthopaedic Centre (PEOC), Exeter, holds data on over 20,000 patients with nearly 30-years follow-up with contemporary prostheses. A previous study suggests that the results of this centre are generalisable if comparisons restricted to the same prostheses. Via flexible parametric survival analysis, we created an algorithm using this database, for revision of any part of the construct for any reason, controlling for age and gender. This algorithm was applied to 664,761 patients in the NJR who have undergone THR, producing a revision prediction for patients with the same prostheses as those used at this centre.

Using our algorithm, the 10-year predicted revision rate of THRs in the NJR was 2.2% (95% CI 1.8, 2.7) based on a 68-year-old female patient; well below the current NICE benchmark. Our predictions were validated by comparison to the maximum observed survival in the NJR (14.2 years) using restricted mean survival time (P=0.32). Our predicted cumulative revision estimate after 30 years is 6.5% (95% CI 4.5, 9.4). The low observed and predicted revision rate with the prosthesis combinations studied, suggest current benchmarks may be lowered and new ones introduced at 15 and 20 years to encourage the use of prostheses with high survival.

Aims

The aim of this study was to report the initial results of the Exeter V40 stem, which became available in 2000.

Aims

We present a minimum 20-year follow-up study of 382 cemented Exeter Universal total hip arthroplasties (350 patients) operated on at a mean age of 66.3 years (17 to 94).

The purpose of this paper was to review the 8 to 11 year follow-up results of the Exeter Universal Hip in primary joint replacement in Palmerston North, New Zealand, where the prosthesis has been in use since 1989. The first 216 Exeter Hips implanted in Palmerston North by six Orthopaedic surgeons, across four hospitals, were analysed. Each surgeon had varying experience with the implant used. A total of 88 primary hips were available for clinical evaluation, functional assessment and radiological review. The Orthowave software programme was used to collect data. Survivorship was determined by using revision as an endpoint. Ninety percent of patients had an excellent functional outcome at time of follow-up. Infection rates were 2.3%. Dislocation rates were high at 14.7%. The survivorship of the Exeter Universal stem at 8–11 years was 95.5%. The overall survivorship of the hips including acetabular revisions was 92%. We have found an excellent survivorship of the Exeter Universal stem at eight to eleven years. The most significant complication was dislocation. The small numbers of this study, and the large numbers lost to follow-up, influence the final results

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 June 2023 Hip & Pelvis Roundup³⁶⁰ looks at: Machine learning to identify surgical candidates for hip and knee arthroplasty: a viable option?; Poor outcome after debridement and implant retention; Can you cement polyethylene liners into well-fixed acetabular shells in hip revision?; Revision stem in primary arthroplasties: the Exeter 44/0 125 mm stem; Depression and anxiety: could they be linked to infection?; Does where you live affect your outcomes after hip and knee arthroplasties?; Racial disparities in outcomes after total hip arthroplasty and total knee arthroplasty are substantially mediated by socioeconomic disadvantage both in black and white patients.

Aims

This study aimed to assess the carbon footprint associated with total hip arthroplasty (THA) in a UK hospital setting, considering various components within the operating theatre. The primary objective was to identify actionable areas for reducing carbon emissions and promoting sustainable orthopaedic practices.

Introduction. The Exeter Hip femoral component remains largely unchanged from the original design, introduced in 1970. It is a highly polished, modular, double tapered stem and has undergone various minor modifications to surface, modularity and most recently the taper; changed to the current V40. TM. design in 2000. The effect of any design modification cannot easily be foreseen and greater emphasis is now placed on ensuring appropriate monitoring for such implants. Methods. We present the results of the first 540 V40. TM. Exeter THAs performed in our Centre between December 2000 and May 2002. All patients were reviewed prospectively at 1, 5 and 10 years following surgery. Results. Ten years after surgery there are no revisions for aseptic loosening and no evidence of aseptic loosening in any hip. The fate of every implant is known and all patients remain under review. One hundred and forty-five patients (26.9%) died before 10 years and of the remaining 395 stems, 374 (94.7%) remain in situ, 11 were revised (2.7%). Three were revised for infection, one for recurrent dislocation and one implant failed at the neck of the prosthesis. Ten were exchanged using cement-in-cement techniques to aid acetabular revision. There were ten periprosthetic fractures: six requiring stem revision, two underwent ORIF and two had already healed by the time the patients presented for follow-up. There was no radiographic evidence of failure preceding the periprosthetic fractures. All radiographs and pain scores were analysed as part of long-term follow-up, and are discussed. Discussion. There were no revisions for aseptic loosening. Previous studies from this centre reviewing the Original and Universal series have demonstrated the stem to provide a predictable and reproducible long term outcome with 100% survival well beyond10 years for aseptic loosening. Conclusion. The polished V40. TM. Exeter stem continues to perform well and survival has remained comparable to the Universal series

Introduction. Historical studies have reported incidences of taper corrosion in retrieved MoP hips of 20–50%. These studies relied on visual assessments, rather than using modern analytical techniques. Patients/Materials and Methods. The Northern Retrieval Registry was initiated to routinely analyse all retrieved hips. The volumetric wear rates of retrieved Exeter head tapers were measured using a coordinate measuring machine using validated methods and compared to the available results obtained from an ongoing study of failed MoM prostheses. Power analysis suggested that we would need at least fifty Exeter head tapers to provide significant results. Non-parametric tests were used to assess differences. We have previously identified head diameter/offset/taper angle and taper surface roughness as variables associated with taper wear. The effect of bearing material combination remains unquantified. These design variables were entered into a multiple regression model following log normalisation of taper wear. Results. 56 consecutively retrieved Exeter head tapers underwent assessment. 36 were of size 28mm. Primary causes for revision were acetabular loosening/periprosthetic fractures. Mean duration in vivo was 87 (1 – 252) months. Median total volumetric wear was 0.29mm. 3. with a wear rate of 0.07mm. 3. /year. There were 353 MoMs. Median taper wear rates for 28mm MoM was 0.07, for 36mm was 0.11, for 38–44mm was 0.31, for 45 – 48mm was 0.52, for 49–52 was 0.55mm and for >52mm was 1.36mm. 3. /year. While Exeter taper wear was significantly lower than the MoM group as a whole (p<0.001), regression modelling indicated that bearing diameter had the greatest influence on taper wear. Discussion. Contrary to previous literature reports, significant material loss at the taper junction of conventional arthroplasties is not commonly observed. Exeter hips appear to be protected to some extent by the smaller head size and lower taper roughness when compared to contemporary MoM devices. The effect of the bearing combination remains under investigation

We evaluated an operative technique, described by the Exeter Hip Unit, to assist accurate introduction of the femoral component. We assessed whether it led to a reduction in the rate of leg-length discrepancy after total hip arthroplasty (THA). A total of 100 patients undergoing THA were studied retrospectively; 50 were undertaken using the test method and 50 using conventional methods as a control group. The groups were matched with respect to patient demographics and the grade of surgeon. Three observers measured the depth of placement of the femoral component on post-operative radiographs and measured the length of the legs. There was a strong correlation between the depth of insertion of the femoral component and the templated depth in the test group (R = 0.92), suggesting accuracy of the technique. The mean leg-length discrepancy was 5.1 mm (0.6 to 21.4) pre-operatively and 1.3 mm (0.2 to 9.3) post-operatively. There was no difference between Consultants and Registrars as primary surgeons. Agreement between the templated and post-operative depth of insertion was associated with reduced post-operative leg-length discrepancy. The intra-class coefficient was R ≥ 0.88 for all measurements, indicating high observer agreement. The post-operative leg-length discrepancy was significantly lower in the test group (1.3 mm) compared with the control group (6.3 mm, p < 0.001). The Exeter technique is reproducible and leads to a lower incidence of leg-length discrepancy after THA. Cite this article: Bone Joint J 2015;97-B:154–9

250 words max Long polished cemented femoral stems, such as the Exeter Hip Revision stem, are one option available to the revision hip arthroplasty surgeon. When proximal bone stock is compromised, distal fixation is often relied upon for stability of the femoral component. In such circumstances, torsional forces can result in debonding and loosening. This study compared the torsional behaviour of a cemented polished and featureless (plain) stem with cemented, polished stems featuring fins or flutes. Nine torsional tests were carried out on each of these three different stem designs. The finned stem construct was significantly stiffer than the fluted stem (mean 24.5 Nm/deg v 17.5 Nm/deg). The plain stem mean stiffness was less than the featured stems (13 Nm/deg), but wide variability lead to no statistically significant difference. The maximum torque of the finned (30.5 Nm) and fluted stems (29 Nm) was significantly higher than the plain stem (10.5 Nm); with no significance to the difference between the finned and fluted stems. Distal stem features may provide a more reliable and greater resistance to torque in polished, cemented revision hip stems. Finned stem features may also increase the stiffness of the construct. Consideration should thus be given to the incorporation of distal stem features in the design of revision hip stems

Recent guidance recommends the use of a well-proven cemented femoral stem for hemiarthroplasty in the management of fractures of the femoral neck, and the Exeter Trauma Stem (ETS) has been suggested as an example of such an implant. The design of this stem was based on the well-proven Exeter Total Hip Replacement stem (ETHRS). This study assessed the surface finish of the ETS in comparison with the ETHRS. Two ETSs and two ETHRSs were examined using a profilometer with a precision of 1 nm and compared with an explanted Exeter Matt stem. The mean roughness average (RA) of the ETSs was approximately ten times higher than that of the ETHRSs (0.235 μm (0.095 to 0.452) versus 0.025 μm (0.011 to 0.059); p < 0.001). The historical Exeter Matt stem roughness measured a mean RA of 0.973 μm (0.658 to 1.159). The change of the polished Exeter stem to a matt surface finish in 1976 resulted in a high stem failure rate. We do not yet know whether the surface differences between ETS and ETHRS will be clinically significant. We propose the inclusion of hemiarthroplasty stems in national joint registries. Cite this article: Bone Joint J 2013;95-B:173–6

Aim. The aim of this study was to determine the medium term survivorship and function of the Exeter Universal Hip Replacement when used in younger patients, a group that is deemed to place high demands on their arthroplasties. Since 1988 The Exeter Hip Research Unit has prospectively gathered data on all patients who have had total hip replacements at the Princess Elizabeth Orthopaedic Hospital. There were 130 Exeter Universal total hip replacements (THR) in 107 patients who were 50 years or younger at the time of surgery and whose surgery was performed at least 10 years before. Mean age at surgery was 42 years (range 17-50 years.) Six patients who had 7 THRs had died, leaving 123 THRs for review. Patients were reviewed at an average of 12.5 years (range 10-17 years). No patient was lost to follow-up. Results. At review, 12 hips had been revised. Of these, 9 were for aseptic loosening of the acetabular component and one cup was revised for focal lysis and pain. One hip was revised for recurrent dislocation. One femoral component required revision in 1 case of infection. Radiographs showed that a further 11 (10%) of the remaining acetabular prostheses were loose but that no femoral components were loose. Survivorship of stem and cup from all causes was 94%, at an average of 12.5 years. Survivorship of stem only from all causes was 99% and from aseptic loosening was 100%. Conclusion. The Exeter Universal Stem is shown to perform extremely well in the younger patient. No femoral component became loose and only 9 acetabular components were revised for aseptic loosening

Introduction Femoral offset is the perpendicular distance from the centre line of the femur to the centre of rotation of the femoral head. In total hip replacement this is important for maintaining the correct leg length and creating a stable hip with well balanced soft tissues. We studied the effect of hip rotation on the measurement of femoral offset and its subsequent effect on choice of femoral stem. Method A series of saw-bone models labelled with radio-opaque markers was prepared. Serial x-rays were taken as each model was rotated though +15° internal rotation, 0°, −15° and −30° external rotation. At 0° the model was in the anatomical position. The resultant offset was measured from each x-ray. Results Offset was significantly different when measured at different angles of rotation (p< 0.0001 Fried-man 2-way analysis of variances). Offset was greatest when measured at +15°. The greatest difference was encountered at −30° (up to 14mm). For the Exeter hip system this could lead to the selection of a stem 2 sizes too small. Even between 0° and −15°, where rotation is not readily identified on x-ray, differences of up to 7mm were found, which could still lead to the selection of an incorrect stem

Introduction & methods: The aim of this study was to determine the medium term survivorship and function of the Exeter Universal Hip Replacement when used in younger patients, a group that is deemed to place high demands on their arthroplasties. Since 1988, The Exeter Hip Research Unit has prospectively gathered data on all patients who have had total hip replacements at the Princess Elizabeth Orthopaedic Hospital. There were 130 Exeter Universal total hip replacements (THR) in 107 patients who were 50 years or younger at the time of surgery and whose surgery was performed at least 10 years before. Mean age at surgery was 42y (range 17y to 50y.) Six patients who had 7 THRs had died leaving 123 THRs for review. Patients were reviewed at an average of 12.5 years (range 10 – 17 years). No patient was lost to follow up. Results: At review, 12 hips had been revised. Of these, 9 were for aseptic loosening of the acetabular component and one cup was revised for focal lysis and pain. One hip was revised for recurrent dislocation. One femoral component required revision in 1 case of infection. Radiographs showed that a further 11(10%) of the remaining acetabular prostheses were loose but that no femoral components were loose. Survivorship of stem and cup from all causes was 92.7%, at an average of 12.5 years. Survivorship of stem only from all causes was 99% and from aseptic loosening was 100%. Conclusion: The Exeter Universal Stem is shown to perform extremely well in the younger patient. No femoral component became loose and only 9 acetabular components were revised for aseptic loosening

Introduction The effect of hip rotation on the measurement of femoral offset is determined firstly using artificial bones in an anatomical study and then in a patient population. Its effect on the choice of femoral component in total hip arthroplasty is discussed. Methods Radiographs were taken of a series of saw bone models rotated through a range of angles. The resultant offset was then measured Standardised and Control (unstandardised) radiographs of the pelvis were taken of patients presenting to orthopaedic outpatients. Femoral offset was measured from each radiograph. Results In the anatomical study angles of rotation differed significantly with respect to measurement of offset (p< 0.0001 Friedman 2-way analysis of variance by ranks). The greatest measurement of offset was at 15 degrees internal rotation. Offset decreased with external rotation. The clinical study had power of 80%. Femoral offset was increased in all the standardised x-rays compared with their controls (n=108, mean=7.64, SD=5.55, 95% CI (6.58,8.70)). A one-sample t-test was performed to see if the standardised and control films were greater than 5mm different (t=14.30 (107df), p< 0.01). Conclusions The clinical study confirmed the findings of the anatomical study. A standardised AP radiograph of the pelvis improves the measurement of femoral offset. For surgeons using the Exeter hip system failure to account for offset could lead to the selection of a stem two sizes too small with regards to offset. Lesser degrees of rotation, not readily identified by looking at the radiograph, could still lead to the selection of an incorrectly sized stem. Offset has been shown to increase the range of movement, abductor strength and stability of the hip joint whilst decreasing the rate of wear. It therefore benefits patients to account for offset, ensuring a correctly sized hip replacement

The aim of this study was to determine the medium term survivorship and function of the cemented Exeter Universal Hip Replacement when used in younger patients. Since 1988 The Exeter Hip Research Unit has prospectively gathered data on all patients who have had total hip replacements at the Princess Elizabeth Orthopaedic Hospital. There were 88 Exeter Universal total hip replacements (THR) in 71 patients who were 50 years or younger at the time of surgery and whose surgery was performed at least 10 years before. 25 surgeons performed the surgery. Mean age at surgery was 43 years (range 24 to 50 years. ) 5 patients who had 7 THRs had died leaving 81 THRs for review. Patients were reviewed in clinic at an average of 11. 4 years (10 – 13 years). No patient was lost to follow up. At review, 8 hips had been revised. 5 cases were for loose cemented metal backed acetabular prosthesis. Two femoral components were revised for infection and one for aseptic loosening. Radiographs showed that a further 10 (13%) acetabular prosthesis were loose and that 3 femurs showed significant osteolysis. Overall 10-year survivorship of stem and cup from all causes was 93%. The 10-year survivorship of stem only from all causes was 98% and from aseptic loosening was 99%. The Exeter Universal Stem performs extremely well in the younger patient. However the high failure rate of the cemented metal backed Exeter acetabular component has compromised the overall results in this series