Mid- to late-term follow-up of primary hip and knee arthroplasty: the UK SAFE evidence-based recommendations.

To review the evidence and reach consensus on recommendations for follow-up after total hip and knee arthroplasty. A programme of work was conducted, including: a systematic review of the clinical and cost-effectiveness literature; analysis of routine national datasets to identify pre-, peri-, and postoperative predictors of mid-to-late term revision; prospective data analyses from 560 patients to understand how patients present for revision surgery; qualitative interviews with NHS managers and orthopaedic surgeons; and health economic modelling. Finally, a consensus meeting considered all the work and agreed the final recommendations and research areas. The UK poSt Arthroplasty Follow-up rEcommendations (UK SAFE) recommendations apply to post-primary hip and knee arthroplasty follow-up. The ten-year time point is based on a lack of robust evidence beyond ten years. The term 'complex cases' refers to individual patient and surgical factors that may increase the risk for arthroplasty failure. For Orthopaedic Data Evaluation Panel (ODEP) 10A* minimum implants, it is safe to disinvest in routine follow-up from one to years post-non-complex hip and knee arthroplasty provided there is rapid access to orthopaedic review. For ODEP 10A* minimum implants in complex cases, or non-ODEP 10A* minimum implants, periodic follow-up post-hip and knee arthroplasty may be required from one to ten years. At ten years post-hip and knee arthroplasty, clinical and radiological evaluation is recommended. After ten years post-hip and knee arthroplasty, frequency of further follow-up should be based on the ten-year assessment; ongoing rapid access to orthopaedic review is still required. Complex cases, implants not meeting the ODEP 10A* criteria, and follow-up after revision surgery are not covered by this recommendation.

Association between outpatient follow-up and incidence of revision after knee and hip replacements: a population-based cohort study.

BACKGROUND: Follow-up visits 5 or 7 years after surgery were recommended for people having primary hip or knee replacement. The benefits of this practice to patients and the healthcare system, however, have not yet been specifically examined. The aim of this study was to investigate the association between long-term follow-up outpatient hospital visits and revision rates for patients who undergo primary knee or hip replacement surgery. METHODS: Cohorts were identified for patients undergoing knee or hip replacement surgery using medical records from primary care practices within the UK Clinical Practice Research Datalink (CPRD) GOLD dataset linked to hospital records from the English Hospital Episodes Statistics (HES) data. Two groups of patients were compared in terms of revision and mortality rates: those with at least one long-term (between five and 10 years since primary surgery) follow-up visit at the orthopaedic department ('Follow-up' group), and those without ('No follow-up' group). RESULTS: A total of 9856 (4349 in the Follow-up group) patients with knee replacement and 10,837 (4870 in the Follow-up group) with hip replacement were included in the analysis. For knee replacement, the incidence of revision was 3.6% for those followed-up and 0.6% for those not followed-up. An adjusted regression model confirmed the difference in the hazard ratio (HR) for revision was statistically significant (HR: 5.65 [95% CI 3.62 to 8.81]). Mortality at 4 years was lower for the Follow-up (17%) compared to the No follow-up group (21%), but this difference was not statistically significant (HR: 0.95 [0.84 to 1.07]). For hip replacement, the incidence of revision rates were 3.2 and 1.4% for the follow-up and not follow-up groups, respectively, the difference being statistically significant (HR: 2.34 [1.71 to 3.20]). Mortality was lower for the Follow-up (15%) compared to the No follow-up group (21%), but the difference was not statistically significant (HR: 0.91 [0.81 to 1.02]). CONCLUSION: Patients attending follow-up orthopaedic consultations show a higher risk of revision surgery compared to those who are not followed-up. A cause for this difference could not be identified in this study but a likely explanation is that surgeons play an effective role as ultimate arbitrators when identifying patients to be included in long-term follow-up lists.

A comparative study of patients presenting for planned and unplanned revision hip or knee arthroplasty.

AIMS: The aim of this study was to conduct a cross-sectional, observational cohort study of patients presenting for revision of a total hip, or total or unicompartmental knee arthroplasty, to understand current routes to revision surgery and explore differences in symptoms, healthcare use, reason for revision, and the revision surgery (surgical time, components, length of stay) between patients having regular follow-up and those without. METHODS: Data were collected from participants and medical records for the 12 months prior to revision. Patients with previous revision, metal-on-metal articulations, or hip hemiarthroplasty were excluded. Participants were retrospectively classified as 'Planned' or 'Unplanned' revision. Multilevel regression and propensity score matching were used to compare the two groups. RESULTS: Data were analyzed from 568 patients, recruited in 38 UK secondary care sites between October 2017 and October 2018 (43.5% male; mean (SD) age 71.86 years (9.93); 305 hips, 263 knees). No significant inclusion differences were identified between the two groups. For hip revision, time to revision > ten years (odds ratio (OR) 3.804, 95% confidence interval (CI) (1.353 to 10.694), p = 0.011), periprosthetic fracture (OR 20.309, 95% CI (4.574 to 90.179), p < 0.001), and dislocation (OR 12.953, 95% CI (4.014 to 41.794), p < 0.001), were associated with unplanned revision. For knee, there were no associations with route to revision. Revision after ten years was more likely for those who were younger at primary surgery, regardless of route to revision. No significant differences in cost outcomes, length of surgery time, and access to a health professional in the year prior to revision were found between the two groups. When periprosthetic fractures, dislocations, and infections were excluded, healthcare use was significantly higher in the unplanned revision group. CONCLUSION: Differences between characteristics for patients presenting for planned and unplanned revision are minimal. Although there was greater healthcare use in those having unplanned revision, it appears unlikely that routine orthopaedic review would have detected many of these issues. It may be safe to disinvest in standard follow-up provided there is rapid access to orthopaedic review. Cite this article: Bone Joint J 2022;104-B(1):59-67.

Setting up an arthroplasty care practitioner-led virtual clinic for follow-up of orthopaedic patients.

This article provides an overview of the set up for an arthroplasty care practitioner (ACP)-led virtual orthopaedic clinic (VOC). Suitable patients attend a local hospital for an X-ray and complete a questionnaire, but do not physically attend a clinic. This has been running successfully in a university teaching hospital and has led to cost savings, a reduction in outpatient waiting times and high levels of patient satisfaction. Similar clinics have the potential to become normal practice across the NHS. This article outlines the steps necessary to implement a successful VOC. The lessons learnt during this exercise may be useful for other ACPs when setting up a VOC.

Towards UK poSt Arthroplasty Follow-up rEcommendations (UK SAFE): protocol for an evaluation of the requirements for arthroplasty follow-up, and the production of consensus-based recommendations.

INTRODUCTION: Hip and knee arthroplasties have revolutionised the management of degenerative joint diseases and, due to an ageing population, are becoming increasingly common. Follow-up of joint prostheses is to identify problems in symptomatic or asymptomatic patients due to infection, osteolysis, bone loss or potential periprosthetic fracture, enabling timely intervention to prevent catastrophic failure at a later date. Early revision is usually more straight-forward surgically and less traumatic for the patient. However, routine long-term follow-up is costly and requires considerable clinical time. Therefore, some centres in the UK have curtailed this aspect of primary hip and knee arthroplasty services, doing so without an evidence base that such disinvestment is clinically or cost-effective. METHODS: Given the timeline from joint replacement to revision, conducting a randomised controlled trial (RCT) to determine potential consequences of disinvestment in hip and knee arthroplasty follow-up is not feasible. Furthermore, the low revision rates of modern prostheses, less than 10% at 10 years, would necessitate thousands of patients to adequately power such a study. The huge variation in follow-up practice across the UK also limits the generalisability of an RCT. This study will therefore use a mixed-methods approach to examine the requirements for arthroplasty follow-up and produce evidence-based and consensus-based recommendations as to how, when and on whom follow-up should be conducted. Four interconnected work packages will be completed: (1) a systematic literature review; (2a) analysis of routinely collected National Health Service data from five national data sets to understand when and which patients present for revision surgery; (2b) prospective data regarding how patients currently present for revision surgery; (3) economic modelling to simulate long-term costs and quality-adjusted life years associated with different follow-up care models and (4) a Delphi-consensus process, involving all stakeholders, to develop a policy document which includes a stratification algorithm to determine appropriate follow-up care for an individual patient. ETHICS AND DISSEMINATION: Favourable ethical opinion has been obtained for WP2a (RO-HES) (220520) and WP2B (220316) from the National Research Ethics Committee. Following advice from the Confidentiality Advisory Group (17/CAG/0122), data controllers for the data sets used in WP2a (RO-HES) - NHS Digital and The Phoenix Partnership - confirmed that Section 251 support was not required as no identifiable data was flowing into or out of these parties. Application for approval of WP2a (RO-HES) from the Independent Group Advising on the Release of Data (IGARD) at NHS Digital is in progress (DARS-NIC-147997). Section 251 support (17/CAG/0030) and NHS Digital approval (DARS-NIC-172121-G0Z1H-v0.11) have been obtained for WP2a (NJR-HES-PROMS). ISAC (11_050MnA2R2) approval has been obtained for WP2a (CPRD-HES).

Hip surgeons and leg length inequality after primary hip replacement.

BACKGROUND:: This study reports the results of 2 separate surveys of British Hip Society (BHS) members relating to leg length inequality (LLI) after primary total hip replacement (THR). SURVEY 1:: Investigates the members' opinions on the effect of LLI on the outcome of THR and explores the acceptable limits of LLI. SURVEY 2:: Reports on the intraoperative techniques currently used by BHS members to minimise LLI after THR. RESULTS - SURVEY 1:: 97% of all surgeons completing the survey believed that LLI can affect the outcome of THR. RESULTS - SURVEY 2:: All surgeons reported using at least 1 intraoperative technique for assessing leg length with a median of 5 techniques. Over 50% of surgeons use 2 or more tests. CONCLUSION - SURVEY 1:: 89% of surgeons agreed that 15 mm of LLI after primary uncomplicated THR was always acceptable. 90% of surgeons felt that LLI more than 22.74 mm was never acceptable. CONCLUSION - SURVEY 2:: Despite the multiple published papers on various methods of assessing leg length intraoperatively, the problem of LLI post THR persists. This study highlights the need for further research to develop a simple intraoperative technique with high accuracy and reproducibility.

Revision surgery for leg length inequality after primary hip replacement.

BACKGROUND: We discuss the surgical results of revision surgery for patients with refractory symptomatic leg length inequality (LLI) after primary hip replacement. METHODS: This is a retrospective review of 21 patients who underwent revision for LLI after primary total hip replacement. All of them were referred to a tertiary clinic between 2006 and 2015. Leg length was measured, to the nearest mm, using Woolson's validated X-ray technique which references to centre of femoral rotation, the acetabular teardrop and the midpoint of the lesser trochanter. The post-operative clinical assessment using a modified D'Aubigne and Postel scoring system investigated the pain, function, and satisfaction after surgery. RESULTS: The mean pre-revision LLI was 16.2 mm (8-30 mm). The mean post revision operation leg length inequality was 2.0 mm (12 mm short to 9 mm long). The mean post-operative D'Aubigne and Postel scores, achieved at a mean 12 months (6-30 months), were; pain 5.2 (3-6), function 4.6 (3-6) and satisfaction 4.4 (3-5). Following revision surgery 20 out of 21 (95%) patients were satisfied with the improvement in LLI. CONCLUSION: Revision surgery for LLI, while it may not resolve all of the pain that the patient presents with, it is a successful treatment for patients who do not respond to conservative management of their LLI.

Hip stem fatigue: : The implications of increasing patient mass.

General trends of increasing body mass index have been observed in many western countries along with an increasing demand for joint replacement. Standards have been developed for testing the fatigue properties of femoral stems; however, the loads that these apply are based on a historic patient weight and may not be valid in the current patient population. Several fatigue tests were conducted using distally fixed titanium alloy stems positioned according to the ISO standard but with a cyclic load based on a current 75th percentile patient sample. Smaller sized stems (currently not weight restricted) fractured in; 30,000 cycles, while larger sized stems were found to have excellent durability under loads simulating walking and stumbling. The results suggest that while the fatigue properties of medical grade titanium are very good, the ISO pre-clinical durability testing standard does not represent the influence of femoral offset or stem size sufficiently to reflect safe design practice.

Pain relief management following proximal femoral fractures: Options, issues and controversies.

The majority of proximal femoral fractures occur in the elderly population. Safe and adequate pain relief is an integral part of the overall management of hip fractures. Inherent difficulties in the assessment of pain in elderly need to be taken into account and unique considerations should be made regarding the effective analgesia due to different elderly physiology, and their response to trauma and subsequent surgery. The pain management should start as soon as possible and special emphasis should be paid to contemporary methods of regional anaesthesia whilst a multimodal approach should be adopted in the perioperative period. The present review summarises the contemporary treatment options and controversies pertaining to the management of pain in elderly patients with proximal femoral fractures.

Unilateral total hip replacement patients with symptomatic leg length inequality have abnormal hip biomechanics during walking.

BACKGROUND: Symptomatic leg length inequality accounts for 8.7% of total hip replacement related claims made against the UK National Health Service Litigation authority. It has not been established whether symptomatic leg length inequality patients following total hip replacement have abnormal hip kinetics during gait. METHODS: Hip kinetics in 15 unilateral total hip replacement patients with symptomatic leg length inequality during gait was determined through multibody dynamics and compared to 15 native hip healthy controls and 15 'successful' asymptomatic unilateral total hip replacement patients. FINDING: More significant differences from normal were found in symptomatic leg length inequality patients than in asymptomatic total hip replacement patients. The leg length inequality patients had altered functions defined by lower gait velocity, reduced stride length, reduced ground reaction force, decreased hip range of motion, reduced hip moment and less dynamic hip force with a 24% lower heel-strike peak, 66% higher mid-stance trough and 37% lower toe-off peak. Greater asymmetry in hip contact force was also observed in leg length inequality patients. INTERPRETATION: These gait adaptions may affect the function of the implant and other healthy joints in symptomatic leg length inequality patients. This study provides important information for the musculoskeletal function and rehabilitation of symptomatic leg length inequality patients.

Hip contact forces in asymptomatic total hip replacement patients differ from normal healthy individuals: Implications for preclinical testing.

BACKGROUND: Preclinical durability testing of hip replacement implants is standardised by ISO-14242-1 (2002) which is based on historical inverse dynamics analysis using data obtained from a small sample of normal healthy individuals. It has not been established whether loading cycles derived from normal healthy individuals are representative of loading cycles occurring in patients following total hip replacement. METHODS: Hip joint kinematics and hip contact forces derived from multibody modelling of forces during normal walking were obtained for 15 asymptomatic total hip replacement patients and compared to 38 normal healthy individuals and to the ISO standard for pre-clinical testing. FINDINGS: Hip kinematics in the total hip replacement patients were comparable to the ISO data and the hip contact force in the normal healthy group was also comparable to the ISO cycles. Hip contact forces derived from the asymptomatic total hip replacement patients were comparable for the first part of the stance period but exhibited 30% lower peak loads at toe-off. INTERPRETATION: Although the ISO standard provides a representative kinematic cycle, the findings call into question whether the hip joint contact forces in the ISO standard are representative of those occurring in the joint following total hip replacement.

Long-term results of a total knee prosthesis utilising an all polyethylene tibial component.

INTRODUCTION: The aim of this study was to assess the long-term performance of a cemented total knee replacement utilising an All Polyethylene Tibial (APT) component and in addition to perform an engineering analysis of any failures to help refine surgical technique. MATERIALS AND METHODS: A total of 26 patients had a total knee replacement performed using a cemented Depuy Press Fit Condylar (PFC) APT component and a cruciate retaining femoral component. At final review all patients were assessed using The Knee Society Score together with radiographs. An engineering analysis simulated loading conditions of the implants that failed and these were compared with the performance of a modular metal-backed Tibial (MBT) component. RESULTS: A total of 20 patients were reviewed at mean time of 116 months following surgery. Knee Society Knee Scores and Function Scores in this cohort were 84/100 and 58/100, respectively. Two patients required revision for tibial component failure. Pre-operatively both had valgus deformities and in each case the tibial tray had been lateralised leaving a gap on the medial side where the APT component had no rigid support. The engineering analysis demonstrated that the volume of highly strained cancellous bone was greater in the APT design compared with the MBT design when a model with a 3 mm medial gap was loaded. The stiffer MBT base plate acted more rigidly and shielded the stress applied to the proximal tibial cancellous bone. CONCLUSION: The APT component demonstrated satisfactory clinical and radiographic performance at long-term follow up. Appropriate cortical support of the APT component is important. The implant should be used with a degree of caution in patients with severe deformities and osteoporosis.

A review of symptomatic leg length inequality following total hip arthroplasty.

Leg length inequality (LLI) following total hip replacement is a complication which features increasingly in the recent literature. The definition of LLI is complicated by lack of consensus regarding radiological measurement, clinical measurement and the incomplete relationship between LLI and associated symptoms. This paper reviews 79 reports relating to LLI post hip replacement, detailing definitions and classification and highlighting patient populations prone to symptomatic LLI. While there is no universal definition of LLI, there is a broad consensus that less than 10 mm of difference on AP view plain radiographs is clinically acceptable. There are few techniques described that consistently produce a postoperative LLI of less than this magnitude. Where postoperative LLI exists, lengthening appears to cause more problems than shortening. In cases of mild LLI, non-surgical management produces adequate outcomes in the majority of cases, with functional LLI cases doing better than those with true LLI. Operative correction is effective in half of cases, even where nerve palsy is present, and remains an important option of last resort. Poor outcomes in patients with LLI may be minimised if individuals at risk are identified and counselled appropriately.

Assessing reproducibility for radiographic measurement of leg length inequality after total hip replacement.

Leg length inequality (LLI) as a result of total hip replacement can cause considerable morbidity. Although LLI was described when the technique was popularised in the 1960s, it remains a significant challenge to arthroplasty surgeons. This study reviews the established practice for the measurement of LLI on plain antero-posterior radiograph, and compares these techniques to two methods used locally. The radiographs of 35 patients were measured using four techniques. All four methods yielded an interclass correlation co-efficient of ≥0.90 for inter reader reliability. This study shows that the four methods are comparable for reliability, while a composite method, measuring from the centre of femoral rotation to the inferior teardrop and then to the lesser trochanter, has the added advantage of providing extra information on component position as well as an overall measure of LLI.

Contact surface motion paths associated with leg length inequality following unilateral total hip replacement.

In the past, there has been little research into leg length inequality (LLI) and its effect on hip arthroplasty bearing longevity. This investigation aimed to determine the effects of post-operative LLI on hip motions during gait and to postulate the subsequent influence on the wear of the artificial hip joint replacement. Motion data from a clinical gait analysis were processed with an in-house computational model to plot graphs showing the movement of loci of 20 points on the femoral head during one gait cycle for two cohorts: 19 LLI patients and 38 normal healthy patients. Loci paths were quantified by calculating the aspect ratio (AR) of the path shape. It was found that on average, LLI patients had a reduction in flexion/extension and abduction/adduction. Furthermore, the AR of LLI patients was found to be 8% smaller than the normal group. The shorter, more multidirectional, motion paths in LLI patients would suggest the potential for greater wear in a polyethylene bearing compared to an asymptomatic, non-LLI patient. The results have potential implications towards preclinical wear testing of joint replacements.

Iliopsoas tendonitis caused by overhang of a collared femoral prosthesis.

Pain after total hip arthroplasty can be due to a variety of causes, one of the less common being iliopsoas tendonitis. We report an unusual case of iliopsoas tendonitis caused by overhang of the femoral calcar by a collared femoral prosthesis resulting in impingement on the iliopsoas tendon. An ultrasound-guided corticosteroid and local anesthetic diagnostic injection to the site of impingement confirmed the diagnosis with temporary symptom relief. Revision of the femoral stem to a collarless prosthesis resulted in immediate and complete resolution of symptoms.

2009 Knee Society Presidential Guest Lecture: Polyethylene wear in total knees.

Knee arthroplasties in young and active patients place a substantial increase in the lifetime tribological demand and potential for wear-induced osteolysis. Polyethylene materials have advanced in recent years, reducing the potential for oxidative degradation and delamination failure. It is timely to consider tribological design variables and their potential to reduce surface wear and the long-term risk of osteolysis. The influence of reduced cross shear in rotating platform mobile-bearing knee designs and reduced surface wear area in low conforming fixed-bearing knees has been investigated. A reduction in cross shear substantially reduced wear in both multidirectional pin-on-plate studies and in rotating platform mobile-bearing designs in knee simulator studies. A reduction in bearing surface contact area substantially reduced surface wear in multidirectional pin-on-plate simulations and in low conforming fixed-bearing knee designs in knee simulator studies. This offers potential for a paradigm shift in knee design predicated by enhanced mechanical properties of new polymer materials. We describe two distinct low-wearing tribological design solutions: (1) a rotating platform design solution with reduced cross shear provides reduced wear with conformity and intrinsic stability; and (2) a low conformity fixed bearing with reduced surface area, provides reduced wear, but has less intrinsic stability and requires good soft tissue function.

The effect of hyaluronic acid and phospholipid based lubricants on friction within a human cartilage damage model.

The lubricating abilities of different formulations of high molecular weight hyaluronic acid (HA), dipalmitoyl phosphatidylcholine (DPCC) and mixtures of both HA and DPCC were assessed in an in vitro model. Levels of start-up friction were determined using an osteoarthritis (OA) damaged human cartilage model set within a specially designed friction rig. To examine the long term benefits of HA, the extent of penetration of HA into cartilage tissue was investigated using fluorescently labelled HA and confocal microscopy. It was found that in this model, all formulations of HA and the majority of DPCC lubricants reduced friction (HA 5 and 10 mg ml(-1), DPPC 200 mg ml(-1) reductions of 51.9%, 46.7% and 46.5% respectively), compared to a Ringers solution control. Lubrication was found not to be concentration dependent for HA formulations, but concentration was key for DPCC lubrication (100 mg ml(-1) reduced friction by only 15.9%). By combining HA and DPCC (HA/DPPC; 5 mg ml(-1)/100 mg ml(-1) and 10 mg ml(-1)/200 mg ml(-1)), a further improvement was noted (69.5% and 61.9%, respectively) as the mean levels of friction were reduced by up to a further 17% than the most effective individual formulation (HA 5 mg ml(-1)). Penetration of HA into bovine cartilage by up to 300 microm from the surface was observed over a 48 h period. It was observed that HA specifically targeted the chondrocytes as it was primarily found within the lacunae surrounding the cells.

Effect of swing phase load on metal-on-metal hip lubrication, friction and wear.

There is renewed interest in metal-on-metal (MOM) total hip replacements (THRs), however, variable wear rates have been observed clinically. It is hypothesised that changes in soft tissue tensioning during surgery may alter loading of THRs during the swing phase of gait leading to changes in fluid film lubrication, friction and wear. This study aimed to assess the effect of swing phase load on the lubrication, friction and wear of MOM hip replacements. Theoretical lubrication modelling was carried out using elastohydrodynamic theory. All the governing equations were solved numerically for the lubricant film thickness between the articulating surfaces under the transient dynamic conditions with low and high swing phase loads. Friction testing was completed using a single axis pendulum simulator, simplified loading cycles were applied with low and high swing phase loads. MOM hip replacements were tested in a hip simulator, modified to provide different swing phase loading regimes; a low (100 N) and a high load (as per ISO 14242-1; 280 N). Results demonstrated that the performance of MOM bearings is highly dependent on swing phase load. Hence, changes in the tension of the tissues at surgery and variations in muscle forces may increase swing phase load, reduce lubrication, increase friction and accelerate wear. This may explain some of the variations that have been observed with clinical wear rates.

Comparative wear under different conditions of surface-engineered metal-on-metal bearings for total hip arthroplasty.

Metal-on-metal hip arthroplasties have demonstrated low wear rates. However, the ion release and toxicity of the metal wear particles remains a concern. Modifying the surface of metal bearings with thick chromium nitride (CrN) coatings has the potential to further reduce wear and ion release, and improve the biocompatibility of wear particles produced. The aim of this study was to investigate the application of surface engineering technology to modify metal-on-metal (MOM) bearings to reduce wear and improve the functional biocompatibility of metal-on-metal prostheses. CrN-on-CrN bearings had lower wear rates in comparison to metal-on-metal bearings, particularly under adverse loading conditions. CrN-on-CrN bearings produced similar nanometer-sized particles to metal-on-metal bearings, however, CrN wear particles were less cytotoxic when cocultured with macrophage and fibroblast cells.