Oxford consensus on primary cam morphology and femoroacetabular impingement syndrome: part 1-definitions, terminology, taxonomy and imaging outcomes.

INTRODUCTION: Primary cam morphology is a mostly benign bony prominence that develops at the femoral head-neck junction of the hip, but it is highly prevalent in many athlete populations. In the small proportion of athletes for whom it is not benign, the resulting hip osteoarthritis can be debilitating. Clinicians, athletes, patients and researchers do not yet agree on important primary cam morphology elements. We aimed to ascertain and improve the level of agreement on primary cam morphology definitions, terminology, taxonomy and imaging outcome measures. METHODS: To collect and aggregate informed opinions, an expert panel-the Young Athlete's Hip Research Collaborative-rated primary cam morphology definition, terminology, taxonomy and imaging outcome statements through an online Delphi exercise followed by an online meeting to explore areas of tension and dissent. Reporting followed Conducting and REporting DElphi Studies. RESULTS: A diverse and inclusive Delphi panel (n=65 for rounds 1 and 2, representing 18 countries; 6 stakeholder groups; 40% women) agreed on 35 of 47 statements in 4 domains, while surfacing areas of tension and dissent. This Delphi panel agreed on four key issues essential to moving research and clinical care forward around primary cam morphology. They agreed on: (1) definition, confirming its conceptual attributes (tissue type, size, location, shape and ownership); (2) terminology-use 'morphology' and not terms with a negative connotation like 'lesion', 'abnormality' or 'deformity'; (3) taxonomy, distinguishing between primary and secondary cam morphology, and (4) imaging outcomes, a continuous bone/cartilage alpha angle on radial femoral head-neck MRI for primary cam morphology aetiology research. CONCLUSION: This consensus provides athletes, patients, clinicians and researchers with a strong foundation to guide more precise communication, better clinical decision-making and higher value research about primary cam morphology and its natural history.

Oxford consensus on primary cam morphology and femoroacetabular impingement syndrome: part 2-research priorities on conditions affecting the young person's hip.

INTRODUCTION: Primary cam morphology is highly prevalent in many athlete populations, causing debilitating hip osteoarthritis in some. Existing research is mired in confusion partly because stakeholders have not agreed on key primary cam morphology elements or a prioritised research agenda. We aimed to inform a more rigorous, inclusive and evidence-based approach to research on primary cam morphology and its natural history by working towards agreement on a set of research priorities for conditions affecting the young person's hip. METHODS: An international expert panel-the Young Athlete's Hip Research (YAHiR) Collaborative-rated research priority statements through an online two-round Delphi exercise and met online to explore areas of tension and dissent. Panellists ranked the prioritised research statements according to the Essential National Health Research (ENHR) ranking strategy. Reporting of results followed REPRISE (REporting guideline for PRIority SEtting of health). RESULTS: A diverse Delphi panel (n=65, Delphi rounds 1 and 2; three ENHR strategy surveys: n=49; n=44; n=42) from 18 countries representing six stakeholder groups, prioritised and ranked 18 of 38 research priority statements. The prioritised statements outlined seven research domains: (1) best practice physiotherapy, (2) rehabilitation progression and return to sport, (3) exercise intervention and load management, (4) primary cam morphology prognosis and aetiology, (5) femoroacetabular impingement syndrome prognosis and aetiology, (6) diagnostic criteria, and (7) screening. The panel recommended areas of tension and dissent for the research community to focus on immediately. CONCLUSION: While informing more rigorous, inclusive and evidence-based research, this consensus is a roadmap for researchers, policy-makers and funders to implement research dedicated to reducing the cost and burden of hip disease related to primary cam morphology.

Primary cam morphology; bump, burden or bog-standard? A concept analysis.

BACKGROUND: Cam morphology, a distinct bony morphology of the hip, is prevalent in many athletes, and a risk factor for hip-related pain and osteoarthritis. Secondary cam morphology, due to existing or previous hip disease (eg, Legg-Calve-Perthes disease), is well-described. Cam morphology not clearly associated with a disease is a challenging concept for clinicians, scientists and patients. We propose this morphology, which likely develops during skeletal maturation as a physiological response to load, should be referred to as primary cam morphology. The aim of this study was to introduce and clarify the concept of primary cam morphology. DESIGN: We conducted a concept analysis of primary cam morphology using articles that reported risk factors associated with primary cam morphology; we excluded articles on secondary cam morphology. The concept analysis method is a rigorous eight-step process designed to clarify complex 'concepts'; the end product is a precise definition that supports the theoretical basis of the chosen concept. RESULTS: We propose five defining attributes of primary cam morphology-tissue type, size, site, shape and ownership-in a new conceptual and operational definition. Primary cam morphology is a cartilage or bony prominence (bump) of varying size at the femoral head-neck junction, which changes the shape of the femoral head from spherical to aspherical. It often occurs in asymptomatic male athletes in both hips. The cartilage or bone alpha angle (calculated from radiographs, CT or MRI) is the most common method to measure cam morphology. We found inconsistent reporting of primary cam morphology taxonomy, terminology, and how the morphology is operationalised. CONCLUSION: We introduce and clarify primary cam morphology, and propose a new conceptual and operational definition. Several elements of the concept of primary cam morphology remain unclear and contested. Experts need to agree on the new taxonomy, terminology and definition that better reflect the primary cam morphology landscape-a bog-standard bump in most athletic hips, and a possible hip disease burden in a selected few.

Consensus recommendations on the classification, definition and diagnostic criteria of hip-related pain in young and middle-aged active adults from the International Hip-related Pain Research Network, Zurich 2018.

There is no agreement on how to classify, define or diagnose hip-related pain-a common cause of hip and groin pain in young and middle-aged active adults. This complicates the work of clinicians and researchers. The International Hip-related Pain Research Network consensus group met in November 2018 in Zurich aiming to make recommendations on how to classify, define and diagnose hip disease in young and middle-aged active adults with hip-related pain as the main symptom. Prior to the meeting we performed a scoping review of electronic databases in June 2018 to determine the definition, epidemiology and diagnosis of hip conditions in young and middle-aged active adults presenting with hip-related pain. We developed and presented evidence-based statements for these to a panel of 37 experts for discussion and consensus agreement. Both non-musculoskeletal and serious hip pathological conditions (eg, tumours, infections, stress fractures, slipped capital femoral epiphysis), as well as competing musculoskeletal conditions (eg, lumbar spine) should be excluded when diagnosing hip-related pain in young and middle-aged active adults. The most common hip conditions in young and middle-aged active adults presenting with hip-related pain are: (1) femoroacetabular impingement (FAI) syndrome, (2) acetabular dysplasia and/or hip instability and (3) other conditions without a distinct osseous morphology (labral, chondral and/or ligamentum teres conditions), and that these terms are used in research and clinical practice. Clinical examination and diagnostic imaging have limited diagnostic utility; a comprehensive approach is therefore essential. A negative flexion-adduction-internal rotation test helps rule out hip-related pain although its clinical utility is limited. Anteroposterior pelvis and lateral femoral head-neck radiographs are the initial diagnostic imaging of choice-advanced imaging should be performed only when requiring additional detail of bony or soft-tissue morphology (eg, for definitive diagnosis, research setting or when planning surgery). We recommend clear, detailed and consistent methodology of bony morphology outcome measures (definition, measurement and statistical reporting) in research. Future research on conditions with hip-related pain as the main symptom should include high-quality prospective studies on aetiology and prognosis. The most common hip conditions in active adults presenting with hip-related pain are: (1) FAI syndrome, (2) acetabular dysplasia and/or hip instability and (3) other conditions without distinct osseous morphology including labral, chondral and/or ligamentum teres conditions. The last category should not be confused with the incidental imaging findings of labral, chondral and/or ligamentum teres pathology in asymptomatic people. Future research should refine our current recommendations by determining the clinical utility of clinical examination and diagnostic imaging in prospective studies.

Hip replacement.

Total hip replacement is a frequently done and highly successful surgical intervention. The procedure is undertaken to relieve pain and improve function in individuals with advanced arthritis of the hip joint. Symptomatic osteoarthritis is the most common indication for surgery. In paper 1 of this Series, we focus on how patient factors should inform the surgical decision-making process. Substantial demands are placed upon modern implants, because patients expect to remain active for longer. We discuss the advances made in implant performance and the developments in perioperative practice that have reduced complications. Assessment of surgery outcomes should include patient-reported outcome measures and implant survival rates that are based on data from joint replacement registries. The high-profile failure of some widely used metal-on-metal prostheses has shown the shortcomings of the existing regulatory framework. We consider how proposed changes to the regulatory framework could influence safety.

Validation of hip osteoarthritis diagnosis recording in the UK Clinical Practice Research Datalink.

PURPOSE: The diagnosis of hip osteoarthritis is subject to several uncertainties, especially in primary care. The aims of this study were to determine (i) the diagnostic accuracy of coding of hip osteoarthritis by primary care physicians in the UK Clinical Practice Research Datalink (CPRD), (ii) the relative influence of radiographic and clinical parameters on diagnostic accuracy, and (iii) the accuracy of the diagnosis date. METHODS: An extract of all patients aged over 65 years, with a Read code for hip osteoarthritis listed between January 1995 and December 2014, was obtained from CPRD. A random sample was selected of 170 participants. A questionnaire concerning data in medical records on relevant clinical and radiographic criteria used to establish the diagnosis of hip osteoarthritis was distributed to primary care physicians of participants. Using diagnostic criteria, we formulated thresholds for diagnosis based on clinical, radiographic, and combined grounds. RESULTS: One hundred nineteen completed questionnaires were returned (70% response rate). The positive predictive value (PPV) of hip osteoarthritis codes, based on radiological criteria, was 79.8%. The PPV, based on clinical criteria, was 79.0%, with substantial but not complete overlap. Overall 12% of diagnoses were not confirmed. In 42% of cases, there was disparity between date of diagnosis in CPRD and the medical record. Median difference in date was ±425 days (interquartile range, 18-1448 days). CONCLUSIONS: Despite the difficulties in reaching a diagnosis of hip osteoarthritis in primary care, CPRD Read codes have a sufficiently high PPV for most research uses. However, the accuracy of diagnosis date may not be as reliable.

ASA class is associated with early revision and reoperation after total hip arthroplasty: an analysis of the Geneva and Swedish Hip Arthroplasty Registries.

Background and purpose - Data from several joint replacement registries suggest that the rate of early revision surgery after primary total hip arthroplasty (THA) is increasing. The ASA class, now widely recorded in arthroplasty registries, may predict early revision. We investigated the influence of ASA class on the risk of revision and other reoperation within 3 months and within 5 years of primary THA. Patients and methods - We used data from the Geneva and Swedish Hip Arthroplasty Registries, on primary elective THAs performed in 1996-2016 and 2008-2016, respectively. 5,319 and 122,241 THAs were included, respectively. Outcomes were all-cause revision and other reoperations evaluated using Kaplan-Meier survival and Cox regression analyses. Results - Within 3 months after surgery, higher ASA class was associated with greater risk of revision and other reoperation. 3-month cumulative incidences of revision by ASA class I, II, and III-IV respectively, were 0.6%, 0.7%, and 2.3% in Geneva and 0.5%, 0.8%, and 1.6% in Sweden. 3-month cumulative incidences of other reoperation were 0.4%, 0.7%, and 0.9% in Geneva and 0.2%, 0.4%, and 0.7% in Sweden. Adjusted hazard ratios (ASA III-IV vs. I) for revision within 3 months were 2.7 (95% CI 1.2-5.9) in Geneva and 3.3 (CI 2.6-4.0) in Sweden. Interpretation - Assessment of ASA class of patients prior to THA will facilitate risk stratification. Targeted risk-reduction strategies may be appropriate during the very early postoperative period for patients identified as at higher risk. Systematically recording ASA class in arthroplasty registries will permit risk adjustment and facilitate comparison of revision rates internationally.

The effect of patient age at intervention on risk of implant revision after total replacement of the hip or knee: a population-based cohort study.

BACKGROUND: Total joint replacements for end-stage osteoarthritis of the hip and knee are cost-effective and demonstrate significant clinical improvement. However, robust population based lifetime-risk data for implant revision are not available to aid patient decision making, which is a particular problem in young patient groups deciding on best-timing for surgery. METHODS: We did implant survival analysis on all patients within the Clinical Practice Research Datalink who had undergone total hip replacement or total knee replacement. These data were adjusted for all-cause mortality with data from the Office for National Statistics and used to generate lifetime risks of revision surgery based on increasing age at the time of primary surgery. FINDINGS: We identified 63 158 patients who had undergone total hip replacement and 54 276 who had total knee replacement between Jan 1, 1991, and Aug 10, 2011, and followed up these patients to a maximum of 20 years. For total hip replacement, 10-year implant survival rate was 95·6% (95% CI 95·3-95·9) and 20-year rate was 85·0% (83·2-86·6). For total knee replacement, 10-year implant survival rate was 96·1% (95·8-96·4), and 20-year implant survival rate was 89·7% (87·5-91·5). The lifetime risk of requiring revision surgery in patients who had total hip replacement or total knee replacement over the age of 70 years was about 5% with no difference between sexes. For those who had surgery younger than 70 years, however, the lifetime risk of revision increased for younger patients, up to 35% (95% CI 30·9-39·1) for men in their early 50s, with large differences seen between male and female patients (15% lower for women in same age group). The median time to revision for patients who had surgery younger than age 60 was 4·4 years. INTERPRETATION: Our study used novel methodology to investigate and offer new insight into the importance of young age and risk of revision after total hip or knee replacement. Our evidence challenges the increasing trend for more total hip replacements and total knee replacements to be done in the younger patient group, and these data should be offered to patients as part of the shared decision making process. FUNDING: Oxford Musculoskeletal Biomedical Research Unit, National Institute for Health Research.

Physical activity during adolescence and the development of cam morphology: a cross-sectional cohort study of 210 individuals.

INTRODUCTION: Cam morphology is a strong risk factor for the development of hip pain and osteoarthritis. It is increasingly thought to develop in association with intense physical activity during youth; however, the aetiology remains uncertain. The study aim was to characterise the effect of physical activity on morphological hip development during adolescence. METHODS: Cross-sectional study of individuals aged 9-18 years recruited from Southampton Football Club Academy (103 male) with an age-matched control population (52 males and 55 females). Assessments included questionnaires and 3 Tesla MRI of both hips. Alpha angle, epiphyseal extension and epiphyseal tilt were measured on radial images. RESULTS: Alpha angle and epiphyseal extension increased most rapidly between ages 12 and 14 years. Soft-tissue hypertrophy at the femoral head-neck junction preceded osseous cam morphology and was first evident at age 10 years. The greatest increase and highest absolute values of alpha angle and epiphyseal extension were colocalised at 1 o'clock. Maximum alpha angles were 6.7 degrees greater in males than females (p=0.005). Compared with individuals who play no regular sport, alpha angles were 4.0 degrees higher in individuals who play sport for a school or club (p=0.041) and 7.7 degrees higher in individuals competing at a national or international level (p=0.035). There was no association with leg dominance . CONCLUSIONS: Sporting activity during adolescence is strongly associated with the development of cam morphology secondary to epiphyseal hypertrophy and extension with a dose-response relationship. Males participating in competitive sport are at particularly elevated risk of developing cam morphology and secondary hip pathology.

The Relationship Between Polyethylene Wear and Periprosthetic Osteolysis in Total Hip Arthroplasty at 12 Years in a Randomized Controlled Trial Cohort.

BACKGROUND: Polyethylene acetabular components are common in hip arthroplasty. Highly cross-linked polyethylene (HXLPE) has lower wear than ultra-high molecular weight polyethylene (UHMWPE). Evidence suggests that wear particles induce inflammation causing periprosthetic osteolysis contributing to implant loosening with wear rates of 0.05 mm/y were considered safe. We aimed to compare incidence and volume of periacetabular osteolysis between HXLPE and UHMWPE using computed tomography. METHODS: Initially, 54 hips in 53 patients were randomized to HXLPE or UHMWPE acetabular liner. At 10 years, 39 hips in 38 patients remained for the radiostereometric analysis' demonstrating significantly lower wear in the HXLPE group. At 12 years, 14 hips in 13 patients were lost to follow-up leaving 25 hips for computed tomography assessment. Images were reconstructed to detect osteolysis and where identified, areas were segmented and volumized. RESULTS: Osteolysis was observed in 8 patients, 7 from the UHMWPE group and only 1 from the HXLPE group (Fisher exact, P = .042). There was no correlation between the amount of polyethylene wear and osteolysis volume; however, the radiostereometric analysis-measured wear rate in patients with osteolysis from both groups was significantly higher than overall average wear rate. CONCLUSION: This data demonstrates lower incidence of periacetabular osteolysis in the HXLPE group of a small cohort. Although numbers are too low to estimate causation, in the context of lower wear in the HXLPE group, this finding supports the hypothesis that HXLPE may not elevate osteolysis risk, and hence does not suggest that HXLPE wear particles are more biologically active than those generated by earlier generations of polyethylene.

The John Charnley Award: Highly crosslinked polyethylene in total hip arthroplasty decreases long-term wear: a double-blind randomized trial.

BACKGROUND: The use of highly crosslinked polyethylene (HXLPE) is now commonplace for total hip arthroplasty. Hip simulator studies and short-term in vivo measurements suggest that the wear rate of some types of HXLPE is significantly less than conventional ultrahigh-molecular-weight polyethylene (UHMWPE). However, there are few long-term data to support its use. QUESTIONS/PURPOSES: The aim of this study was to measure the long-term steady-state wear of HXLPE compared with UHMWPE liners in a prospective, double-blind, randomized controlled trial using radiostereometric analysis. METHODS: Fifty-four patients were randomized to receive hip arthroplasties with either UHMWPE liners or HXLPE liners. Complete followup was available on 39 of these patients (72%). All patients received the same cemented stem and an uncemented acetabular component. Three-dimensional penetration of the head into the socket was determined at 10 years using a radiostereometric analysis system, which has an in vivo accuracy of <0.1 mm. Oxford Hip Scores were compared between the groups. RESULTS: At 10 years there was significantly less wear of HXLPE (0.003 mm/year; 95% confidence interval [CI], ±0.010; SD 0.023; range, -0.057 to 0.074) compared with UHMWPE (0.030 mm/year; 95% CI, ±0.012; p<0.001; SD 0.0.27; range, -0.001 to 0.164). The volumetric penetration from 1 to 10 years for the UHMWPE group was 98 mm3 (95% CI, ±46 mm3; SD 102 mm3; range, -4 to 430 mm3) compared with 14 mm3 (95% CI, ±40 mm3; SD 91 mm3; range, -189 to 242 mm3) for the HXLPE group (p=0.01). CONCLUSIONS: This study demonstrates that HXLPE has little detectable steady-state in vivo wear. This may result in fewer reoperations from loosening; however, careful clinical followup into the second decade still needs to be performed. LEVEL OF EVIDENCE: Level I, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Neuropathic pain is a feature in patients with symptomatic femoral acetabular impingement.

Femoral acetabular impingement syndrome (FAIS) is a cause of hip pain thought to be nociceptive, although pain phenotypes e.g., burning, pain attacks, prickling, numbness etc., are reported, mimicking neuropathic pain. Although no lesion to the somatosensory system is identified, neuropathic pain (NeP) may explain why nociceptive-focussed treatments are not always successful. OBJECTIVE: To identify NeP in patients with FAIS and investigate if related to poorer outcomes. DESIGN: A secondary analysis of the Femoral Acetabular Impingement Trial (FAIT). Outcome of interest: PainDETECT questionnaire; secondary outcomes of interest; International Hip Outcome Tool (iHOT33), Hospital Anxiety and Depression Scale (HADS) and VAS 'average pain over a month', at baseline and 8 months follow-up. Intervention (surgery or physiotherapy) were pooled. RESULTS: 173 data sets at baseline; 123 at 8 months follow-up. Baseline painDETECT identified three groups: 69% nociceptive, 19% unclear and 12% neuropathic pain phenotypes. Baseline, median scores were higher for the neuropathic group compared to the nociceptive group demonstrating borderline anxiety (9.5(5.3 to 14.2), 5(3 to 8), higher normal values for depression (7.5(2.3 to 11.8), (4(2 to 9), higher average pain (7 (6 to 8), 5(4 to 6) and lower iHOT33 14.2(9 to 21.1), 38.4(26.2 to 55.7). Post treatment, there was a median change in the neuropathic score in both iHOT33 (40.8 (25 to 76.5) with a median difference of 24.13 (CI 95% 10.46 to 45.92) and average pain 4.5(1.5 to 7) with a median difference of 2 (CI 95% 1 to 5) but to a lesser amount than the nociceptive group, iHOT33 (64(38.2 to 86.6) with a median difference of 15.50 (CI 95% 6.41 to 21.82) and average pain 3(1 to 5.7) with a median difference of 1 (CI 95% 0.5 to 1). CONCLUSION: NeP exists in symptomatic FAIS patients and is associated with increased average pain, and functional limitations. Nociceptive-targeted treatment improves hip function and pain but with less improvement in the NeP group when compared to the nociceptive group. Pain phenotyping before intervention may improve outcomes. CONTRIBUTION OF PAPER.

Clinical diagnosis of femoroacetabular impingement.

The diagnosis of femoroacetabular impingement (FAI) syndrome is made based on a combination of clinical symptoms, physical examination findings, and imaging studies. A detailed assessment of each of these components is important to differentiate FAI from other intra- and extra-articular hip disorders. Clinical and physical examination findings must be viewed collectively because no single pathognomonic finding exists for FAI. Nevertheless, common components of the history and physical examination do suggest a diagnosis of FAI.

Diagnostic imaging of femoroacetabular impingement.

Imaging studies play a key role in establishing the diagnosis of femoroacetabular impingement (FAI). When clinical examination is suggestive of FAI, radiographic evidence should confirm the diagnosis. Imaging findings must be evaluated in the context of the patient's clinical presentation and recreational activities. Plain radiographic evaluation remains the initial diagnostic modality. Three-dimensional imaging such as MRI and CT often is obtained for the evaluation of labral and cartilage pathology, definition of bony anatomy, and surgical planning.

Clinical trials in orthopaedics and the future direction of clinical investigations for femoroacetabular impingement.

Femoroacetabular impingement (FAI) represents a heterogeneous group of disorders that affect a diverse patient population. The natural history of the disease, the role of nonsurgical management, the indications for surgery, optimal surgical techniques, and the predictors of treatment outcomes need to be further defined. To date, clinical research reports have included primarily surgical case series. Future clinical investigations are needed to establish improved clinical evidence to guide patient care. Most urgent is the need to better understand the potential role of standardized nonsurgical treatment options for FAI and to define the predictors of surgical and nonsurgical outcomes. Future randomized controlled trials and large observational cohort studies targeted at these clinical research deficiencies will strengthen the evidence and improve informed decision making regarding the management of symptomatic FAI.

Coronal-plane leg alignment in adolescence and the effects of activity: A full leg length MRI study.

The aim of this study was to explore the association between developing coronal-plane leg alignment and activity levels during adolescence. We performed a cross-sectional cohort study with individuals from soccer club academies and an age-matched control population. Outcome measures were the hip knee angle (HKA), medial proximal tibial physeal angle (MPTPhyA), lateral distal femoral physeal angle (LDFPhyA) on full leg length magnetic reasonance imagine scans, and the physical activity questionnaire (PAQ) score. The cohort comprised 57 elite male soccer players, 34 male and 34 female controls aged 11-21 years. Mean HKA became more varus with age, with little change after 16 years or skeletal maturity. Skeletally mature elite male soccer players were significantly more varus than male controls with a HKA 2.28° less than male controls (p < 0.001). Skeletally mature male controls had a HKA 1.34° less than female controls (p < 0.001). A negative correlation existed between HKA and PAQ score (coefficient -0.24, p = 0.029). A positive correlation existed between HKA and MPTPhyA (coefficient 0.32, p = 0.008). In conclusion, high activity levels during adolescence are associated with the development of varus leg alignment. Mean HKA becomes more varus with age until skeletal maturity. The development of varus alignment may represent a physiological adaptation to load at the proximal tibial physis. Clinical Significance: A time period may exist for intervention before the development of varus leg alignment in young athletes, such as training load modification or proximal tibial morphology monitoring.

Assessing a 12-month course of oral alendronate for adults with avascular necrosis of the hip: MANTIS RCT with internal pilot.

BACKGROUND: People with avascular necrosis of the hip have very limited treatment options currently available to stop the progression of this disease; this often results in the need for a hip replacement. There is some weak evidence that a class of drugs called bisphosphonates may delay the course of the disease, and this trial was commissioned and set up to provide robust evidence regarding the use of bisphosphonates in adults aged ≥ 18 years with this condition. OBJECTIVES: The aim of the Managing Avascular Necrosis Treatments: an Interventional Study ( MANTIS ) trial was to evaluate the clinical effectiveness and cost-effectiveness of a 12-month course of alendronate in the treatment of avascular necrosis. DESIGN: This was a 66-month, definitive, multisite, two-arm, parallel-group, placebo-controlled, double-blind, randomised controlled trial, with an internal pilot phase. SETTING: Eight secondary care NHS hospitals across the UK. PARTICIPANTS: Planned trial size - 280 adult patients with avascular necrosis. INTERVENTION: Participants in the intervention group received 70 mg of alendronate (an oral bisphosphonate) weekly for 12 months. MAIN OUTCOMES: The main outcomes were Oxford Hip Score at 12 months (short-term outcome) and the time to decision that a hip replacement is required at 36 months (long-term outcome). RESULTS: Twenty-one patients were recruited and randomised to receive either the intervention drug, alendronate, or a placebo-matched tablet. LIMITATIONS: This trial was principally limited by low disease prevalence. Other limitations included the late disease stage at which participants were identified and the rapid progression of the disease. FUTURE WORK: This trial was limited by a low recruitment rate. Avascular necrosis of the hip should be treated as a rare disease. Future trials would need to recruit many more sites and recruit over a longer time period, and, for this reason, a registry may provide a more effective means of collecting data pertaining to this disease. CONCLUSIONS: The MANTIS trial was terminated at the end of the pilot phase, because it did not meet its go/no-go criteria. The main issue was a poor recruitment rate, owing to a lower than expected disease prevalence and difficulties in identifying the condition at a sufficiently early stage. Those patients who were identified and screened either were too advanced in their disease progression or were already taking medication. We would not recommend that a short-term interventional study is conducted on this condition until its prevalence, geographic foci and natural history and better understood. The difficulty of acquiring this understanding is likely to be a barrier in most health-care markets. One means of developing this understanding would be the introduction of a database/registry for patients suffering from avascular necrosis of the hip. TRIAL REGISTRATION: The trial is registered as ISRCTN14015902. FUNDING: This project was funded by the National Institute for Health and Care Research ( NIHR ) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 26, No. 43. See the NIHR Journals Library website for further project information.

WHAT WAS THE QUESTION?: The Managing Avascular Necrosis Treatments: an Interventional Study ( MANTIS ) trial was designed to compare ways of treating patients with avascular necrosis who are seeking to slow down the deterioration of their condition. Alendronate is a drug routinely available across the NHS in both tablet and injection form, and doctors and scientists believe that it might prevent ongoing hip deterioration and result in fewer patients requiring a total hip replacement. WHAT DID WE DO?: This trial attempted to compare alendronate taken as a tablet with an identical-looking tablet that did not contain any of the drug (a placebo) to find out if alendronate reduced the number of patients requiring a hip replacement and having pain (compared with patients who did not get alendronate). WHAT DID WE FIND?: Patients were willing to participate in the trial but we were able to recruit only a small number to the study. The main reason for this was difficulty in identifying potentially suitable patients and approaching them at the right point in their medical care. This was more challenging than anticipated, particularly because the NHS sites and professionals that patients with this condition seek out are extremely variable in the UK. It was also difficult to locate and identify patients with the condition at an early enough stage, and before they had already started taking the drug. WHAT DOES THIS MEAN?: More information on patients with this rare condition, such as NHS referral pathways, and an understanding of how the condition progresses may help to improve our understanding of this patient group. This information could also help us determine whether or not there is scope to carry out the study in a different way that might enable these patients to be more easily identified.

Primary stability of a proximally coated and tapered stem.

AIMS: The aim of this prospective cohort study was to evaluate the early migration of the TriFit cementless proximally coated tapered femoral stem using radiostereometric analysis (RSA). METHODS: A total of 21 patients (eight men and 13 women) undergoing primary total hip arthroplasty (THA) for osteoarthritis of the hip were recruited in this study and followed up for two years. Two patients were lost to follow-up. All patients received a TriFit stem and Trinity Cup with a vitamin E-infused highly cross-linked ultra-high molecular weight polyethylene liner. Radiographs for RSA were taken postoperatively and then at three, 12, and 24 months. Oxford Hip Score (OHS), EuroQol five-dimension questionnaire (EQ-5D), and adverse events were reported. RESULTS: At two years, the mean subsidence of the head and tip for the TriFit stem was 0.38 mm (SD 0.32) and 0.52 mm (SD 0.36), respectively. The total migration of the head and tip was 0.55 mm (SD 0.32) and 0.71 mm (SD 0.38), respectively. There were no statistically significant differences between the three to 12 months' migration (p = 0.105) and 12 to 24 months' migration (p = 0.694). The OHS and EQ-5D showed significant improvements at two years. CONCLUSION: The results of this study suggest that the TriFit femoral stem achieves initial stability and is likely to be stable in the mid and long term. A long-term outcome study is required to assess late mechanisms of failure and the effects of bone mineral density (BMD) related changes. Cite this article: Bone Joint J 2021;103-B(4):644-649.