The MAKO Robotic arm is a haptic robotic system that can be used to optimise performance during total hip arthroplasty (THA). We present the outcome of the first 40 robotic cases performed in an NHS foundation trust along with the technique of performing robotic THA in our unit.

Forty consecutive patients undergoing robotic THA (rTHA) were compared to a case matched group of patients undergoing manual THA (m-THA). 2:1 blinded case matching was performed for age, sex, implants used (Trident uncemented socket and cemented Exeter stem, Stryker Mahwah, NJ, US) and surgeon grade. Comparisons were made for radiological positioning of implants, including leg length assessment, and patient reported functional outcome (PROMS). Pre- and post-operative radiographs were independently analysed by 2 authors.

All patients underwent THA for a primary diagnosis of osteoarthritis. No significant difference between groups was identified for post-operative leg length discrepancy (LLD) although pre-operatively a significantly higher LLD was highlighted on the MAKO group, likely due to patient selection. Significantly lower post-operative socket version was identified in the MAKO cohort although no difference in post-operative cup inclination was noted. However, there was significantly larger variance in post-op LLD (p=0.024), cup version (p=0.004) and inclination (p=0.05) between groups indicating r-THA was significantly less variable (Levene's test for homogeneity of variance). There was no significant difference in the number of cases outside of Lewinnek's ‘safe’ zone for inclination (p=0.469), however, there were significantly more cases outside Lewinnek's ‘safe’ zone for version (12.5% vs 40.3%, p=0.002) in the m-THA group.

We report the commencement of performance of MAKO robotic THA in an NHS institution. No problems with surgery were reported during our learning curve. Robotic THA cases had less variability in terms of implant positioning suggesting that the MAKO robot allows more accurate, less variable implant positioning with fewer outliers. Longer term follow-up of more cases is needed to identify whether this improved implant positioning has an effect on outcomes, but the initial results seem promising.

The Exeter V40 femoral stem is the most implanted stem in the NJR for primary THA. In 2004, the 44/00/125 stem was released for use in “cement-in-cement” revision cases. It has however been used ‘off-label’ as a primary stem when, for example, patient anatomy requires a smaller stem with a 44mm offset. We aimed to investigate survival of this stem in comparison to others in the range when used in primary THAs recorded in the NJR.

Analyses were performed using a dataset based on that used for the 2020 NJR annual report. Our exposure was the stem; the outcome was all-cause construct revision. Crude analyses were performed using Kaplan-Meier and adjusted using Cox models. The 44/00/125 stem was directly compared to other stems in the Exeter range.

We analysed 330,732 primary THAs using the Exeter V40 stem comprising 34.5% of the 958,869 THAs with complete information from the start of the NJR to 31 December 2018. The 44/00/125 stem was implanted in 2,158 primary THAs with 67.5% in female patients and a mean age of 67.8. The 10-year revision estimate for the 44/00/125 stem was 4.9% (95%CI 3.6, 6.8) and in constructs using an Exeter V40 stem was 2.8% (95%CI 2.7, 2.8). Controlling for age, sex and ASA demonstrated an increased overall hazard of revision for constructs using the 44/00/125 stem compared to constructs using other Exeter V40 femoral stems (HR 1.8 (95%CI 1.4, 2.3)).

Although the revision estimate is within the NICE 10-year benchmark, survivorship of constructs using the 44/00/125 stem appears to be lower than the rest of the Exeter V40 range. Attempts to control for age, sex and ASA will not take into account confounding by indication i.e. patients with more complex anatomy who may have a higher risk of revision. Surgeons and patients should be reassured by this but should be aware of the observed increased revision estimate and use the stem according to its indications.

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.

The principle function of the “short external rotator” muscle group is primarily as an abductor and extensor of the flexed hip and is better referred to as the “Quadriceps Coxa” (QC). The QC has a profound influenced on weight bearing rising and propulsive motions. The SPAIRE technique preserves Obturator Internus (OI) and Piriformis (P) resulting in improved stability of the hip and potentially improved recovery and function in patients undergoing hip arthroplasty.

Short term outcomes of the first 42 consecutive SPAIRE cases are compared with 86 consecutive cases using the traditional posterior approach that immediately preceded introduction of the technique. The purpose was to document the learning curve and confirm the safety of introducing SPAIRE into routine clinical practice.

The two groups were comparable and there was no statistically significant difference in length of stay, blood loss, intra-or post-operative complications nor radiological measurements relating to the femoral or acetabular components. Statistically significant differences were found for component usage (more uncemented acetabula for SPAIRE), length of operation (8 mins longer with SPAIRE); patient satisfaction was higher at 6 weeks and measured leg length discrepancy less in the SPAIRE group.

SPAIRE has been used routinely for all routine arthroplasties for over two years. RCTs are ongoing to document the effect of SPAIRE on recovery, long term function and activity level. If the potential benefits are confirmed SPAIRE may become the default technique for hip arthroplasty operations through a posterior approach for elective and hip fracture cases.

Introduction

Impaction bone grafting for reconstitution of acetabular bone stock in revision hip surgery has been used for nearly 30 years. We report results in a group of patients upon whom data has been collected prospectively with a minimum ten year follow-up.

Mortality following hip arthroplasty is affected by a large number of confounding variables each of which must be considered to enable valid interpretation.

The aim of this study was to establish whether it is possible to determine a true cause-and-effect relationship between the risk of mortality and data that are routinely collected by the NJR and to establish the degree to which variation in the mortality rate could be explained by each variable.

Relevant variables available from the 2011 NJR data setwere included in a Cox model.

We carried out two analyses:

Firstly, we conducted an analysis of data collected from the NJR data set used in preparation of the NJR's 8th Annual Report (2011) looking for an association between the variables collected and the risk of mortality.

Secondly, as social deprivation is also known to influence mortalityrates but is not routinely collected as part of the NJR data set, a further analysis was performed which included social deprivation data derived from partial postcodes.

Mortality rates in hip arthroplasty patients were lower than in the age matched population across all hip types. Age at surgery, ASA grade, diagnosis, gender, provider type, hip type and lead surgeon grade all had a significant effect on mortality. Schemper's statistic showed that only 18.98% of the variation in mortality was explained by the variables available in the NJR data set.

It is inappropriate to use Registry data to study an outcome affected by a multitude of confounding variables when these cannot be adequately accounted for in the available data set.

Acetabular impaction grafting (AIG) for the reconstruction of acetabular defects in total hip arthroplasty has the potential to recreate anatomy whilst also allowing the restoration of bone stock. The incorporation of impacted, morcellised bone graft has been demonstrated in histological studies and is a well established technique in revision hip surgery where there is loss of bone stock. We have studied our results of fullAIG when used in primary total hip arthroplasty, with particular emphasis on the results of AIG in cavitary and segmental defects.

Between 1995 and 2003, 129 cemented primary THAs were performed using full acetabular impaction grafting to reconstruct acetabular deficiencies. These were classified as cavitary in 74 and segmental in 55 hips. Eighty-one patients were reviewed at mean 9.1 (6.2–14.3) years post-operatively. There were seven acetabular component revisions due to aseptic loosening, and a further 11 cases that had migrated »5 mm or tilted »5° on radiological review — ten of which reported no symptoms. Kaplan–Meier analysis of revisions for aseptic loosening demonstrates 100% survival at nine years for cavitary defects compared to 82.6% for segmental defects. Our results suggest that the medium-term survival of this technique is excellent when used for purely cavitary defects but less predictable when used with large rim meshes in segmental defects.

The management of patients with displaced intra-capsular hip fractures is usually a hip hemiarthoplasty procedure. NICE guideline 124 published in 2011 suggested that Total Hip Replacement (THR) surgery should be considered in a sub group of patients with no cognitive impairment, who walk independently and are medically fit for a major surgical procedure.

The Royal Devon and Exeter Hospital manages approximately 550 patients every year who have sustained a fracture of neck of femur, of which approximately 90 patients fit the above criteria. Prior to the guideline less than 20% of this sub-group were treated with a THR whereas after the guideline over 50% of patients were treated with THR, performed by sub-specialist Hip surgeons.

This practice is financially viable; there is no apparent difference in the overall cost of treating patients with THR. The effect of adoption of the NICE guideline was examined using 100 % complete data from 12 month post operative follow up. Only the Hemi-arthroplasty patients were significantly less likely to have stepped down a rung of independent living. Both THR and Hemi-arthroplasty patients were significantly less likely to have stepped down a rung of walking ability, but there was no significant difference between THR and Hemi-arthroplasty groups. Revision rates remained negligible.

The management of patients with displaced intra-capsular hip fractures is usually a hip hemiarthoplasty procedure. NICE guideline 124 published in 2011 suggested that Total Hip Replacement (THR) surgery should be considered in a sub group of patients with no cognitive impairment, who walk independently and are medically fit for a major surgical procedure.

The Royal Devon and Exeter Hospital manages approximately 600 patients every year who have sustained a fracture of neck of femur, of which approximately 90 patients fit the above criteria. Prior to the guideline less than 20% of this sub-group were treated with a THR whereas after the guideline over 50% of patients were treated with THR, performed by sub-specialist Hip surgeons. This change was achieved by active leadership, incorporation of ‘Firebreak’ lists, looking for cases, flexible use of theatre time and operating lists and the nomination of an individual senior doctor who was tasked with a mission to improve practice.

This practice is financially viable; the Trust makes over £1000 per THR for fracture. Complete outcome data at 120 days show significantly fewer patients stepping down a rung in terms of both independent living and independent walking.

We present 346 consecutive revision procedures for aseptic loosening with acetabular impaction bone grafting (AIBG) and a cemented polyethylene cup. Defects were contained with mesh alone. Mean follow up of 6.6 years, range 8 days-13 years. The Oxford Hip (OHS) and Harris Hip (HHS) scores were collected prospectively. Radiological definition of cup failure was either > 5mm displacement, or > 5° rotation. Cox regression analysis was performed on ten separate patient and surgical factors to determine their significance on survivorship.

Kaplan Meier survivorship at 10 years (42 cases remaining at risk) for aseptic loosening was 87% (95% confidence Interval (CI): 81.6 to 92.2) and 85.6% (95% CI: 80.3 to 90.9) for all revisions. These results are comparable to other reported series utilising AIBG. However, there were 88 cases (25%) that exceeded the radiological migration parameters, but their functional scores were not significantly different to the non-migrators: OHS p=0.273, HHS p=0.16. The latest post-operative mean OHS was 33 (SD 10.66). Female gender (p=0.039), increasing graft thickness (p=0.006) and the use of mesh (p=0.037) were significant risk factors for revision, but differing techniques in graft preparation, including artificial graft expanders (p=0.73), had no significant effect when analysed using Cox regression.

Favourable long-term results have been reported with the standard Exeter cemented stem. We report our experience with a version for use in smaller femora, the Exeter 35.5 mm stem. Although, also a collarless polished taper, the stem is slimmer and 25 mm shorter than a standard stem.

Between August 1988 and August 2003, 192 primary hip arthroplasties were performed in 165 patients using the Exeter 35.5 mm stem. Clinical and operative data were collected prospectively. Clinical evaluation was by the Charnley, Harris and Oxford hip scores and radiographs were analysed post-operatively and at latest follow up.

The mean age at time of operation was 53 years (18 to 86), with 73 patients under the age of 50 years. The diagnosis was osteoarthritis in 91, hip dysplasia in 77, inflammatory arthritis in 18, septic arthritis of the hip in three, secondary to Perthes disease in two and avascular necrosis of the hip in one patient. The fate of every implant is known.

At a median follow-up of 8 years (5 to 19), survivorship with revision of the femoral stem for aseptic loosening as the endpoint was 100%. Fifteen cases (7.8%) underwent further surgery 11 for acetabular revision, one for stem fracture and three others.

Although, smaller than a standard Exeter Universal polished tapered cemented stem—with a shorter, slimmer taper—the performance of the Exeter 35.5 mm stem was equally good even in this young, diverse group of patients.

Impaction bone grafting (IBG) of the acetabulum in cemented primary total hip replacement is a useful technique in the management of acetabular deficiencies. It has the capacity to restore anatomy and bone stock with good long-term outcome. We present 125 consecutive cases of IBG with a cemented polyethylene component. All patients who received full IBG of the acetabulum in primary cemented Exeter total hip replacements and who underwent surgery between August 1995 and August 2003 were identified. All operative and follow-up data was collected prospectively and no patients were lost to follow-up. All patients underwent pre-operative and regular post-operative hip scores with the Harris, Oxford and the modified Charnley scoring systems. Data on indication, surgical technique, socket position and migration and revision was reviewed at a mean follow-up of 7.6 (range 5 to13.4) years.

Between August 1995 and August 2003, 113 patients (85 females) with an average age of 67.8 (range 22.9–99.2) years underwent 125 primary Exeter cemented total hip replacements with IBG of acetabular defects. Acetabular defects were classified according to the AAOS classification as cavitatory in 62 hips and as segmental, requiring application of a rim mesh prior to IBG, in 63 hips. Life tables were constructed demonstrating 86.4% survival of the acetabular component at 13.4 years with revision for any reason as the endpoint and 89.3% survival with revision for aseptic loosening as the endpoint. Of the seven patients who underwent revision for aseptic loosening, all had pre-operative segmental acetabular defects requiring application of a rim mesh. No patient who underwent IBG for a cavitatory defect required revision surgery for aseptic loosening. Survival of the Exeter cemented femoral component was 100% at 13.4 years with revision for aseptic loosening as the endpoint. There were 11 radiographic failures of the acetabular component, which have not been revised at latest review. One of these is symptomatic but not fit for revision surgery, two were asymptomatic at time of death and eight are asymptomatic but under review.

This is the largest series of IBG in the acetabulum in cemented primary THR. Our results suggest that the medium term survival of this technique is good, particularly when used for cavitatory defects. Although there were radiographic failures, these are largely asymptomatic and may not require revision.

Removal of well-fixed cement at the time of revision THA for sepsis is time consuming and risks bone stock loss, femoral perforation or fracture. We report our experience of two-stage revision for infection in a series of cases in which we have retained well-fixed femoral cement.

All patients underwent two-stage revision for infection. At the first stage the prostheses and acetabular cement were removed but when the femoral cement mantle demonstrated good osseo-integration it was left in-situ. Following Girdlestone excision arthroplasty (GEA), patients received local antibiotics delivered by cement spacers, as well as systemic antibiotics. At the second stage the existing cement mantle was reamed, washed and dried and then a femoral component was cemented into the old mantle.

Sixteen patients (M:F 5:11) had at least three years follow-up (mean 80 months – range 43 to 91). One patient died of an unrelated cause at 53 months. Recurrence of infection was not suspected in this case. The mean time to first stage revision was 57 months (3 to 155). The mean time between first and second stages was nine months (1 to 35). Organisms were identified in 14 (87.5%) cases (5 Staphylococcus Aureas, 4 Group B Streptococcus, 2 Coagulase negative Staphylococcus, 2 Enterococcus Faecalis, 1 Escheria Coli). At second stage, five (31.2%) acetabulae were uncemented and 11 (68.8%) were cemented. There were two complications; one patient dislocated 41 days post-operatively and a second patient required an acetabular revision at 44 days for failure of fixation. No evidence of infection was found at re-revision. One patient (1/16, 7%) has been re-revised for recurrent infection. Currently no other patients are suspected of having a recurrence of infection (93%).

Retention of a well-fixed femoral cement mantle during two-stage revision for infection and subsequent cement-in-cement reconstruction appears safe with a success rate of 93%. Advantages include a shorter operating time, reduced loss of bone stock, improved component fixation and a technically easier second stage procedure.

Restoration of an anatomical hip centre frequently requires limb lengthening, which increases the risk of nerve injury in the treatment of Crowe 4 DDH. The objective was to perform a prospective evaluation of SDTSO with Cemented Exeter Femoral Component.

15 female patients (18 hips – 3 bilateral) with a mean age at time of operation of 51 years were followed-up for a mean of 77 months (11 to 133). 16 cemented and 2 uncemented acetabular components were implanted. Exeter cemented DDH stems were used in all cases. No patient was lost to follow-up.

Charnley-d'Aubigné-Postel scores for pain, function and range of movement were improved from a mean of 2, 2, 3 to 5, 4, 5 respectively. One osteotomy failed to unite at 14 months and was revised successfully. Clinical healing was achieved at a mean of 6 months and radiological at a mean of 9 months. The mean length of the excised segment was 3cm and the mean true limb lengthening was 2cm. A 3.5mm DCP plate with unicortical screws was used to reduce the osteotomy, and intramedullary autografting was performed in all cases. Mean subsidence was 1mm and no stem was found loose at the latest follow-up. No sciatic nerve palsy was observed and no dislocation.

Cemented Exeter femoral components perform well in the treatment of Crowe IV DDH with SDTSO. Transverse osteotomy is necessary to achieve derotation and reduction can be maintained with a DCP plate. Intramedullary autografting prevents cement interposition at the osteotomy site.

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.

The aim of this study was to evaluate the cost of implants used in a large series of peri-prosthetic femoral fractures and assess its financial impact in the era of Payment by Results

We evaluated the clinical demographic and economical data associated with 202 patients with peri-prosthetic fractures of the proximal femur in two orthopaedic centers of excellence. All fractures were classified preoperatively according to the Vancouver classification. The patients were followed up until radiographic confirmation of fracture union and post-operative outcome was recorded with reference to the patients’ mobility and any complications.

The mean age of the patients operated was 81.2 years (range 33–100 years). 55% of the patients in our series were graded type B3 and 25% type B2. 80% of all fractures underwent revision. 71 percent of the fractures united within 8.4 months. 112 patients had impaction femoral grafting. Our implant cost alone for revision varied from 1900 pounds to as high as 3500 pounds without taking in to account the cost of cement and allograft (femoral heads and struts).

Hospital resource utilization for peri-prosthetic fractures is quite high compared to the reimbursement received. This is due to hospital stay and rehabilitation needs, theatre utilization, implant cost and higher readmission rates. There are neither reference costs available nor any special tariffs for these complex fractures. The reimbursement for internal fixation of these fractures could range from £2336 to £4230 and for emergency revision hip replacement is £5928. More than 50% of the reimbursement money would just be necessary to meet the implant costs. For uncemented revisions this equation is even worse. Current HRG codes for the treatment of peri-prosthetic fractures are unrealistic and new treatment algorithms and special tariffs have to be introduced to help manage these fractures.

The review of the first 325 Exeter Universal hips reported good long term survivorship despite the majority of cups being metal backed. We have reviewed the long term performance of the concentric all-polyethylene Exeter cups used with the Universal Exeter stem.

Clinical and radiographic outcomes of 263 consecutive primary hip arthroplasties in 242 patients with mean age 66 years (range, 18 to 89) were reviewed. 118 cases subsequently died none of whom underwent a revision. Eighteen hips have been revised; thirteen for aseptic cup loosening, three for recurrent dislocation and two for deep infection. Three patients (four hips) were lost to follow-up. The minimum follow-up of the remaining 123 hips was 10 years (mean 13.3 years, range 10–17). Radiographs demonstrated 4 (4%) of the remaining acetabular prostheses were loose. The Kaplan Meier survivorship at 14.5 years with endpoint revision for all causes is 91.5% (95% CI 86.6 to 96.2%). With endpoint revision for aseptic cup loosening, survivorship is 93.3% (CI 88.8 to 97.8%).

This series included a number of complex cases requiring bone blocks and/or chip autograft for acetabular deficiencies. The concentric all polythene Exeter cup and Exeter stem has excellent long term results particularly when factoring in the complexity of cases in this series.

The review of the first 325 Exeter Universal hips reported good long term survivorship despite the majority of cups being metal backed. We have reviewed the long term performance of the concentric all-polyethylene Exeter cups used with the Universal Exeter stem.

Clinical and radiographic outcomes of 263 consecutive primary hip arthroplasties in 242 patients with mean age 66 years (range, 18 to 89) were reviewed. 118 cases subsequently died none of whom underwent a revision. Eighteen hips have been revised; thirteen for aseptic cup loosening, three for recurrent dislocation and two for deep infection. Three patients (four hips) were lost to follow-up. The minimum follow-up of the remaining 123 hips was 10 years (mean 13.3 years, range 10–17). Radiographs demonstrated 6 (6%) of the remaining acetabular prostheses were loose. The Kaplan Meier survivorship at 14.5 years with endpoint revision for all causes is 91.5% (95% CI 86.6 to 96.2%). With endpoint revision for aseptic cup loosening, survivorship is 93.3% (CI 88.8 to 97.8%).

This series included a number of complex cases requiring bone blocks and/or chip autograft for acetabular deficiencies. The concentric all polythene Exeter cup and Exeter stem has excellent long term results particularly when factoring in the complexity of cases in this series.

There is evidence that recommends the retention of a well-fixed cement mantle at the time of revision hip arthroplasty. The cement-cement interface has been proven to have a greater shear strength than a new bone-cement interface after removing the old cement mantle.

This study reviewed a series of acetabular revision procedures with a minimum 2 year follow-up where the original cement mantle was left intact. From 1988 to 2004, 61 consecutive cement-in-cement revisions of the acetabular component were performed at our institution. Outcome was based on functional assessment using the Oxford, Charnley, and Harris scoring systems as well as radiographic analysis using the DeLee and Charnley criteria.

In total 61 procedures were performed in 59 patients (40 female and 19 male), whose mean age at surgery was 75 years (range 40 to 99 years). 47 hips (77%) were performed for recurrent dislocation, 12 for polyethylene wear associated with other reasons for revision (aseptic stem loosening in 8, stem fracture in 2, femoral periprosthetic fracture in 1, subluxation in 1), 1 for unexplained pain, and 1 for disarticulation (intraprosthetic dislocation) of a constrained liner. No case was lost to follow-up. There was a significant improvement in the functional scores from the pre-operative status with the patients maintaining a low level of pain. There was one re-revision for aseptic cup loosening at 7 years, with 1 further case of radiological loosening identified at the latest review. There were 6 further cases of dislocation 4 of which were treated with further in-cement revisions. All other cases showed well-fixed components on radiographic analysis and no evidence of failure at the most recent follow up.

The cement-in-cement revision technique can be used in selected cases of acetabular revision surgery, providing satisfactory functional outcomes backed up by good radiographic results. Blood loss and surgical time are also significantly decreased.