Aims. Leucocyte esterase (LE) has been shown to be an accurate marker of prosthetic joint infection (PJI), and has been proposed as an alternative to frozen section (FS) histology for intraoperative diagnosis. In this study, the intraoperative assessment of LE was compared with FS histology for the diagnosis of prosthetic hip infection. Patients and Methods. A total of 119 patients undergoing revision total hip arthroplasty (THA) between June 2015 and December 2017 were included in the study. There were 56 men and 63 women with a mean age of 66.2 years (27 to 88). Synovial fluid was collected before arthrotomy for the assessment of LE using enzymatic colourimetric strips. Between five and six samples were stained with haematoxylin and eosin for FS histology, and considered suggestive of infection when at least five polymorphonuclear leucocytes were found in five high-power fields. Results. The sensitivity and specificity of the LE assay were 100% and 93.8%, respectively; the positive (PPV) and the negative (NPV) predictive values were 79.3% and 100%, respectively. The mean time between the collection of the sample and the result being known was 20.1 minutes (. sd. 4.4). The sensitivity and specificity of FS histology were 78.3% and 96.9%, respectively; the PPV and the NPV were 85.7% and 94.9%, respectively. The mean time between the collection of the sample and the result being known was 27.2 minutes (. sd. 6.9). Conclusion. The sensitivity of LE assay was higher, with similar specificity and diagnostic accuracy, compared with FS histology. The faster turnaround time, its ease of use, and low costs make LE assay a valuable alternative to FS histology. We now use it routinely for the intraoperative diagnosis of PJI. Cite this article: Bone Joint J 2019;101-B:372–377

Aims. The purpose of this study was to validate the diagnosis of periprosthetic joint infection (PJI) in the Danish Hip Arthroplasty Register (DHR). Patients and Methods. We identified a cohort of patients from the DHR who had undergone primary total hip arthroplasty (THA) since 1 January 2005 and followed them until first-time revision, death, emigration or until 31 December 2012. Revision for PJI, as registered in the DHR, was validated against a benchmark which included information from microbiology databases, prescription registers, clinical biochemistry registers and clinical records. We estimated the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for PJI in the DHR alone and in the DHR when combined with microbiology databases. Results. In total, 1382 of the 37 826 primary THAs in the DHR were registered as having been revised for any cause once 26 patients with errors in registration had been excluded: 232 of these were for PJI. For this group, the sensitivity was 67%, specificity 95%, PPV 77%, and NPV 92%. Combining the data from the DHR with those from microbiology databases increased the sensitivity to 90% and also improved specificity (100%), PPV (98%) and NPV (98%). Conclusion. Only two thirds of revisions for PJI were captured in the DHR and only 77% of the PJI reported to the DHR could be confirmed to be infected. . Take home message: combining the data from the DHR with those from microbiology databases substantially improved the validity of the diagnosis of PJI and should enable future register-based studies. Cite this article: Bone Joint J 2016;98-B:320–5

In many papers, the diagnosis of pincer-type femoroacetabular impingement (FAI) is attributed to the presence of coxa profunda. However, little is known about the prevalence of coxa profunda in the general population and its clinical relevance. In order to ascertain its prevalence in asymptomatic subjects and whether it is a reliable indicator of pincer-type FAI, we undertook a cross-sectional study between July and December 2013. A total of 226 subjects (452 hips) were initially screened. According to strict inclusion criteria, 129 asymptomatic patients (257 hips) were included in the study. The coxa profunda sign, the crossover sign, the acetabular index (AI) and lateral centre–edge (LCE) angle were measured on the radiographs. The median age of the patients was 36.5 years (28 to 50) and 138 (53.7%) were women. Coxa profunda was present in 199 hips (77.4%). There was a significantly increased prevalence of coxa profunda in women (p < 0.05) and a significant association between coxa profunda and female gender (p < 0.001) (92% vs 60.5%). The crossover sign was seen in 36 hips (14%), an LCE > 40° in 28 hips (10.9%) and an AI < 0º in 79 hips (30.7%). A total of 221 normal hips (79.2%) (normal considering the crossover) had coxa profunda, a total of 229 normal hips (75.5%) (normal considering the LCE) had coxa profunda and a total of 178 normal hips (75.3%) (normal considering AI) had coxa profunda. When the presence of all radiological signs in the same subject was considered, pincer-type FAI was found in only two hips (one subject). We therefore consider that the coxa profunda sign should not be used as a radiological indicator of pincer-type FAI. We consider profunda to be a benign alteration in the morphology of the hip with low prevalence and a lack of association with other radiological markers of FAI. We suggest that the diagnosis of pincer-type FAI should be based on objective measures, in association with clinical findings. Cite this article: Bone Joint J 2015; 97-B:478–83

We evaluated triple-phase bone scintigraphy in the differential diagnosis of peri-prosthetic infection in 46 patients with a total hip replacement or bipolar hemiarthroplasty who were due for revision surgery. There were 18 men and 28 women, with a mean age at operation of 64.6 years (28 to 81). We defined peri-prosthetic infection as an increased uptake of radioisotope in all the phases of triple-phase bone scintigraphy and validated these results against the histological and/or microbiology results in every case. The positive and negative predictive values for the presence of infection were 83% and 93%, respectively. The diagnostic sensitivity was 88% and the specificity was 90%. This study indicates that triple-phase bone scintigraphy is a useful tool in the detection of peri-prosthetic infection and offers a cost-effective method of screening

We analysed follow-up data from 18 486 primary total hip arthroplasties performed between 1967 and 2001 to assess the validity of clinical procedures in diagnosing loosening of prosthetic components. Sensitivity, specificity and predictive values were estimated with the radiological definition of loose or not loose as the ‘gold standard’.

The prevalence of acetabular loosening increased from 0.6% to 13.9% during the period of the study and that of femoral loosening from 0.9% to 12.1%. Sensitivities and positive predictive values were low, suggesting that clinical procedures could not replace radiological assessment in the identification of loose prostheses. Specificities and negative predictive values were constantly above 0.86. The possibility of there being a prosthesis which is not loose in asymptomatic patients was consequently very high, particularly during the first five to six years after operation.

The necessity of periodic clinical and radiological follow-up examinations of asymptomatic patients during the first five to six years after operation remains questionable. Symptomatic patients, however, require radiological assessment.

In this meta-analysis we included 32 English-language articles published between January 1975 and June 2004 on the diagnostic performance of plain radiography, subtraction arthrography, nuclear arthrography and bone scintigraphy in detecting aseptic loosening of the femoral component, using criteria based on the Cochrane systematic review of screening and diagnostic tests.

The mean sensitivity and specificity were, respectively, 82% (95% confidence interval (CI) 76 to 87) and 81% (95% CI 73 to 87) for plain radiography and 85% (95% CI 75 to 91) and 83% (95% CI 75 to 89) for nuclear arthrography. Pooled sensitivity and specificity were, respectively, 86% (95% CI 74 to 93) and 85% (95% CI 77 to 91) for subtraction arthrography and 85% (95% CI 79 to 89) and 72% (95% CI 64 to 79) for bone scintigraphy. Although the diagnostic performance of the imaging techniques was not significantly different, plain radiography and bone scintigraphy are preferred for the assessment of a femoral component because of their efficacy and lower risk of patient morbidity.

Plasma levels of cobalt and chromium ions and Metal Artefact Reduction Sequence (MARS)-MRI scans were performed on patients with 209 consecutive, unilateral, symptomatic metal-on-metal (MoM) hip arthroplasties. There was wide variation in plasma cobalt and chromium levels, and MARS-MRI scans were positive for adverse reaction to metal debris (ARMD) in 84 hips (40%). There was a significant difference in the median plasma cobalt and chromium levels between those with positive and negative MARS-MRI scans (p < 0.001). Compared with MARS-MRI as the potential reference standard for the diagnosis of ARMD, the sensitivity of metal ion analysis for cobalt or chromium with a cut-off of > 7 µg/l was 57%. The specificity was 65%, positive predictive value was 52% and the negative predictive value was 69% in symptomatic patients. A lowered threshold of > 3.5 µg/l for cobalt and chromium ion levels improved the sensitivity and negative predictive value to 86% and 74% but at the expense of specificity (27%) and positive predictive value (44%).

Metal ion analysis is not recommended as a sole indirect screening test in the surveillance of symptomatic patients with a MoM arthroplasty. The investigating clinicians should have a low threshold for obtaining cross-sectional imaging in these patients, even in the presence of low plasma metal ion levels.

Aims. Septic arthritis of the hip often leads to irreversible osteoarthritis (OA) and the requirement for total hip arthroplasty (THA). The aim of this study was to report the mid-term risk of any infection, periprosthetic joint infection (PJI), aseptic revision, and reoperation in patients with a past history of septic arthritis who underwent THA, compared with a control group of patients who underwent THA for OA. Methods. We retrospectively identified 256 THAs in 244 patients following septic arthritis of the native hip, which were undertaken between 1969 and 2016 at a single institution. Each case was matched 1:1, based on age, sex, BMI, and year of surgery, to a primary THA performed for OA. The mean age and BMI were 58 years (35 to 84) and 31 kg/m. 2. (18 to 48), respectively, and 100 (39%) were female. The mean follow-up was 11 years (2 to 39). Results. The ten-year survival free of any infection was 91% and 99% in the septic arthritis and OA groups, respectively (hazard ratio (HR) = 13; p < 0.001). The survival free of PJI at ten years was 93% and 99% in the septic arthritis and OA groups, respectively (HR = 10; p = 0.002). There was a significantly higher rate of any infection at ten years when THA was undertaken within five years of the diagnosis of septic arthritis compared with those in whom THA was undertaken > five years after this diagnosis was made (14% vs 5%, respectively; HR = 3.1; p = 0.009), but there was no significant difference in ten-year survival free of aseptic revision (HR = 1.14; p = 0.485). The mean Harris Hip Scores at two and five years postoperatively were significantly lower in the septic arthritis group compared with the OA group (p = 0.001 for both). Conclusion. There was a ten-fold increased risk of PJI in patients with a history of septic arthritis who underwent THA compared with those who underwent THA for OA with a ten-year cumulative incidence of 7%. The risk of any infection had a strong downward trend as the time interval between the diagnosis of septic arthritis and THA increased, highlighted by a 3.1-fold higher risk when THAs were performed within five years of the diagnosis being made. Cite this article: Bone Joint J 2022;104-B(2):227–234

Aims. Pelvic tilt is believed to affect the symptomology of osteoarthritis (OA) of the hip by alterations in joint movement, dysplasia of the hip by modification of acetabular cover, and femoroacetabular impingement by influencing the impingement-free range of motion. While the apparent role of pelvic tilt in hip pathology has been reported, the exact effects of many forms of treatment on pelvic tilt are unknown. The primary aim of this study was to investigate the effects of surgery on pelvic tilt in these three groups of patients. Methods. The demographic, radiological, and outcome data for all patients operated on by the senior author between October 2016 and January 2020 were identified from a prospective registry, and all those who underwent surgery with a primary diagnosis of OA, dysplasia, or femoroacetabular impingement were considered for inclusion. Pelvic tilt was assessed on anteroposterior (AP) standing radiographs using the pre- and postoperative pubic symphysis to sacroiliac joint (PS-SI) distance, and the outcomes were assessed with the Hip Outcome Score (HOS), International Hip Outcome Tool (iHOT-12), and Harris Hip Score (HHS). Results. The linear regression model revealed a significant negative predictive association between the standing pre- and postoperative PS-SI distances for all three groups of patients (all p < 0.001). There was a significant improvement in all three outcome measures between the pre- and postoperative values (p < 0.05). Conclusion. There is a statistically significant decrease in pelvic tilt after surgery in patients with OA of the hip, dysplasia, and femoroacetabular impingement. These results confirm that surgery significantly alters the pelvic orientation. Pelvic tilt significantly decreased after total hip arthroplasty, periacetabular osteotomy, and arthroscopy/surgical hip dislocation. The impact of surgery on pelvic tilt should be considered within the therapeutic plan in order to optimize pelvic orientation in these patients. Cite this article: Bone Joint J 2022;104-B(9):1025–1031

Aims. Contemporary outcomes of primary total hip arthroplasties (THAs) with highly cross-linked polyethylene (HXLPE) liners in patients with inflammatory arthritis have not been well studied. This study examined the implant survivorship, complications, radiological results, and clinical outcomes of THA in patients with inflammatory arthritis. Methods. We identified 418 hips (350 patients) with a primary diagnosis of inflammatory arthritis who underwent primary THA with HXLPE liners from January 2000 to December 2017. Of these hips, 68% had rheumatoid arthritis (n = 286), 13% ankylosing spondylitis (n = 53), 7% juvenile rheumatoid arthritis (n = 29), 6% psoriatic arthritis (n = 24), 5% systemic lupus erythematosus (n = 23), and 1% scleroderma (n = 3). Mean age was 58 years (SD 14.8), 66.3% were female (n = 277), and mean BMI was 29 kg/m. 2. (SD 7). Uncemented femoral components were used in 77% of cases (n = 320). Uncemented acetabular components were used in all patients. Competing risk analysis was used accounting for death. Mean follow-up was 4.5 years (2 to 18). Results. The ten-year cumulative incidence of any revision was 3%, and was highest in psoriatic arthritis patients (16%). The most common indications for the 15 revisions were dislocations (n = 8) and periprosthetic joint infections (PJI; n = 4, all on disease-modifying antirheumatic drugs (DMARDs)). The ten-year cumulative incidence of reoperation was 6.1%, with the most common indications being wound infections (six cases, four on DMARDs) and postoperative periprosthetic femur fractures (two cases, both uncemented femoral components). The ten-year cumulative incidence of complications not requiring reoperation was 13.1%, with the most common being intraoperative periprosthetic femur fracture (15 cases, 14 uncemented femoral components; p = 0.13). Radiological evidence of early femoral component subsidence was observed in six cases (all uncemented). Only one femoral component ultimately developed aseptic loosening. Harris Hip Scores substantially improved (p < 0.001). Conclusion. Contemporary primary THAs with HXLPE in patients with inflammatory arthritis had excellent survivorship and good functional outcomes regardless of fixation method. Dislocation, PJI, and periprosthetic fracture were the most common complications in this cohort with inflammatory arthritis. Cite this article: Bone Joint J 2023;105-B(7):768–774

Aims. The duration of systemic antibiotic treatment following first-stage revision surgery for periprosthetic joint infection (PJI) after total hip arthroplasty (THA) is contentious. Our philosophy is to perform an aggressive debridement, and to use a high local concentration of targeted antibiotics in cement beads and systemic prophylactic antibiotics alone. The aim of this study was to assess the success of this philosophy in the management of PJI of the hip using our two-stage protocol. Methods. The study involved a retrospective review of our prospectively collected database from which we identified all patients who underwent an intended two-stage revision for PJI of the hip. All patients had a diagnosis of PJI according to the major criteria of the Musculoskeletal Infection Society (MSIS) 2013, a minimum five-year follow-up, and were assessed using the MSIS working group outcome-reporting tool. The outcomes were grouped into ‘successful’ or ‘unsuccessful’. Results. A total of 299 two-stage revision THAs in 289 patients met the inclusion criteria, of whom 258 (86%) proceeded to second-stage surgery. Their mean age was 68.1 years (28 to 92). The median follow-up was 10.7 years (interquartile range (IQR) 6.3 to 15.0). A 91% success rate was seen in those patients who underwent reimplantation, decreasing to 86% when including those who did not proceed to reimplantation. The median duration of postoperative systemic antibiotics following the first stage was five days (IQR 5 to 9). There was no significant difference in outcome between those patients who were treated with antibiotics for ≤ 48 hours (p = 0.961) or ≤ five days (p = 0.376) compared with those who were treated with longer courses. Greater success rates were seen for Gram-positive PJIs (87%) than for Gram-negative (84%) and mixed-Gram PJIs (72%; p = 0.098). Conclusion. Aggressive surgical debridement with a high local concentration of targeted antibiotics at the time of first-stage revision surgery for PJI of the hip, without prolonged systemic antibiotics, provides a high rate of success, responsible antibiotic stewardship, and reduced hospital costs. Cite this article: Bone Joint J 2023;105-B(5):511–517

Aims. A recent report from France suggested an association between the use of cobalt-chrome (CoCr) femoral heads in total hip arthroplasties (THAs) and an increased risk of dilated cardiomyopathy and heart failure. CoCr is a commonly used material in orthopaedic implants. If the reported association is causal, the consequences would be significant given the millions of joint arthroplasties and other orthopaedic procedures in which CoCr is used annually. We examined whether CoCr-containing THAs were associated with an increased risk of all-cause mortality, heart outcomes, cancer, and neurodegenerative disorders in a large national database. Methods. Data from the National Joint Registry was linked to NHS English hospital inpatient episodes for 374,359 primary THAs with up to 14.5 years' follow-up. We excluded any patients with bilateral THAs, knee arthroplasties, indications other than osteoarthritis, aged under 55 years, and diagnosis of one or more outcome of interest before THA. Implants were grouped as either containing CoCr or not containing CoCr. The association between implant construct and the risk of all-cause mortality and incident heart failure, cancer, and neurodegenerative disorders was examined. Results. There were 158,677 individuals (42.4%) with an implant containing CoCr. There were 47,963 deaths, 27,332 heart outcomes, 35,720 cancers, and 22,025 neurodegenerative disorders. There was no evidence of an association between patients with CoCr implants and higher rates of any of the outcomes. Conclusion. CoCr-containing THAs did not have an increased risk of all-cause mortality, or clinically meaningful heart outcomes, cancer, or neurodegenerative disorders into the second decade post-implantation. Our findings will help reassure clinicians and the increasing number of patients receiving primary THA worldwide that the use of CoCr-containing implants is not associated with significant adverse systemic effects. Cite this article: Bone Joint J 2022;104-B(3):359–367

Aims. The aim of this study is to report the long-term outcomes of instrumented femoral revisions with impaction allograft bone grafting (IBG) using the X-change femoral revision system at 30 years after introduction of the technique. Methods. We updated the outcomes of our previous study, based on 208 consecutive revisions using IBG and the X-change femoral revision system in combination with a cemented polished stem, performed in our tertiary care institute between 1991 and 2007. Kaplan-Meier survival analyses were used to determine the survival rate of the revisions with endpoint revision for any reason and aseptic loosening. Secondary outcomes were radiological loosening and patient-reported outcome measures. Results. Mean age at revision total hip arthroplasty (THA) was 64.9 years (30 to 86). The most prevalent diagnosis for the femoral revision was aseptic loosening. At review in May 2021, 81 patients (85 hips) were still alive and 118 patients (120 hips; 58%) had died. Three patients (3 hips; 1%) were lost to follow-up at 11, 15, and 16 years after surgery, respectively. Data of all deceased and lost patients were included until final follow-up. The mean follow-up was 13.4 years (0 to 28). During the follow-up, 22 re-revisions were performed. The most common reason for re-revision was infection (n = 12; 54%). The survival with endpoint re-revision for any reason was 86% (95% confidence interval (CI) 79 to 91) at 20 years and 74% (95% CI 43 to 89) at 25 years after surgery. The survival for endpoint re-revision for aseptic loosening was 97% (95% CI 91 to 99) after both 20 and 25 years. Conclusion. We conclude that femoral IBG is a valuable technique that can reconstitute femoral bone loss in the long term. After 25 years of follow-up, few re-revisions for aseptic loosening were required. Also, the overall revision rate is very acceptable at a long follow-up. This technique is especially attractive for younger patients facing femoral revisions with extensive bone loss. Cite this article: Bone Joint J 2022;104-B(9):1039–1046

Aims. The primary aim was to determine the influence of COVID-19 on 30-day mortality following hip fracture. Secondary aims were to determine predictors of COVID-19 status on presentation and later in the admission; the rate of hospital acquired COVID-19; and the predictive value of negative swabs on admission. Methods. A nationwide multicentre retrospective cohort study was conducted of all patients presenting with a hip fracture to 17 Scottish centres in March and April 2020. Demographics, presentation blood tests, COVID-19 status, Nottingham Hip Fracture Score, management, length of stay, and 30-day mortality were recorded. Results. In all, 78/833 (9.4%) patients were diagnosed with COVID-19. The 30-day survival of patients with COVID-19 was significantly lower than for those without (65.4% vs 91%; p < 0.001). Diagnosis of COVID-19 within seven days of admission (likely community acquired) was independently associated with male sex (odds ratio (OR) 2.34, p = 0.040, confidence interval (CI) 1.04 to 5.25) and symptoms of COVID-19 (OR 15.56, CI 6.61 to 36.60, p < 0.001). Diagnosis of COVID-19 made between seven and 30 days of admission to hospital (likely hospital acquired) was independently associated with male sex (OR 1.73, CI 1.05 to 2.87, p = 0.032), Nottingham Hip Fracture Score ≥ 7 (OR 1.91, CI 1.09 to 3.34, p = 0.024), pulmonary disease (OR 1.68, CI 1.00 to 2.81, p = 0.049), American Society of Anesthesiologists (ASA) grade ≥ 3 (OR 2.37, CI 1.13 to 4.97, p = 0.022), and length of stay ≥ nine days (OR 1.98, CI 1.18 to 3.31, p = 0.009). A total of 38 (58.5%) COVID-19 cases were probably hospital acquired infections. The false-negative rate of a negative swab on admission was 0% in asymptomatic patients and 2.9% in symptomatic patients. Conclusion. COVID-19 was independently associated with a three times increased 30-day mortality rate. Nosocomial transmission may have accounted for approximately half of all cases during the first wave of the pandemic. Identification of risk factors for having COVID-19 on admission or acquiring COVID-19 in hospital may guide pathways for isolating or shielding patients respectively. Length of stay was the only modifiable risk factor, which emphasizes the importance of high-quality and timely care in this patient group. Cite this article: Bone Joint J 2021;103-B(5):888–897

Aims. Some patients presenting with hip pain and instability and underlying acetabular dysplasia (AD) do not experience resolution of symptoms after surgical management. Hip-spine syndrome is a possible underlying cause. We hypothesized that there is a higher frequency of radiological spine anomalies in patients with AD. We also assessed the relationship between radiological severity of AD and frequency of spine anomalies. Methods. In a retrospective analysis of registry data, 122 hips in 122 patients who presented with hip pain and and a final diagnosis of AD were studied. Two observers analyzed hip and spine variables using standard radiographs to assess AD. The frequency of lumbosacral transitional vertebra (LSTV), along with associated Castellvi grade, pars interarticularis defect, and spinal morphological measurements were recorded and correlated with radiological severity of AD. Results. Out of 122 patients, 110 (90.2%) were female and 12 (9.8%) were male. We analyzed the radiographs of 122 hips (59 (48.4%) symptomatic left hips, and 63 (51.6%) symptomatic right hips). Average age at time of presentation was 34.2 years (SD 11.2). Frequency of LSTV was high (39% to 43%), compared to historic records from the general population, with Castellvi type 3b being the most common (60% to 63%). Patients with AD have increased L4 and L5 interpedicular distance compared to published values. Frequency of pars interarticularis defect was 4%. Intraclass correlation coefficient for hip and spine variables assessed ranged from good (0.60 to 0.75) to excellent (0.75 to 1.00). Severity of AD did not demonstrate significant correlation with frequency of radiological spine anomalies. Conclusion. Patients with AD have increased frequency of spinal anomalies seen on standard hip radiographs. However, there exists no correlation between radiological severity of AD and frequency of spine anomalies. In managing AD patients, clinicians should also assess spinal anomalies that are easily found on standard hip radiographs. Cite this article: Bone Joint J 2021;103-B(8):1351–1357

Aims. Modular dual mobility (MDM) acetabular components are often used with the aim of reducing the risk of dislocation in revision total hip arthroplasty (THA). There is, however, little information in the literature about its use in this context. The aim of this study, therefore, was to evaluate the outcomes in a cohort of patients in whom MDM components were used at revision THA, with a mean follow-up of more than five years. Methods. Using the database of a single academic centre, 126 revision THAs in 117 patients using a single design of an MDM acetabular component were retrospectively reviewed. A total of 94 revision THAs in 88 patients with a mean follow-up of 5.5 years were included in the study. Survivorship was analyzed with the endpoints of dislocation, reoperation for dislocation, acetabular revision for aseptic loosening, and acetabular revision for any reason. The secondary endpoints were surgical complications and the radiological outcome. Results. The overall rate of dislocation was 11%, with a six-year survival of 91%. Reoperation for dislocation was performed in seven patients (7%), with a six-year survival of 94%. The dislocations were early (at a mean of 33 days) in six patients, and late (at a mean of 4.3 years) in four patients. There were three intraprosthetic dissociations. An outer head diameter of ≥ 48 mm was associated with a lower risk of dislocation (p = 0.013). Lumbrosacral fusion was associated with increased dislocation (p = 0.004). Four revision THAs (4%) were further revised for aseptic acetabular loosening, and severe bone loss (Paprosky III) at the time of the initial revision was significantly associated with further revision for aseptic acetabular loosening (p = 0.008). Fourteen acetabular components (15%) were re-revised for infection, and a pre-revision diagnosis of reimplantation after periprosthetic joint infection (PJI) was associated with subsequent PJI (p < 0.001). Two THAs had visible metallic changes on the backside of the cobalt chromium liner. Conclusion. When using this MDM component in revision THA, at a mean follow-up of 5.5 years, there was a higher rate of dislocation (11%) than previously reported. The size of the outer bearing was related to the risk of dislocation. There was a low rate of aseptic acetabular loosening. Longer follow-up of this MDM component and evaluation of other designs are warranted. Cite this article: Bone Joint J 2021;103-B(7 Supple B):66–72

Aims. Total hip arthroplasty (THA) patients undergoing or having a prior lumbar spine fusion (LSF) have an increased risk of mechanical complications. The aim of this registry-based, retrospective comparative cohort study is to assess the longer term survival of THA in patients who have undergone a LSF during a 17-year period (2000 to 2017). Methods. A registry-based population study was conducted on 679 patients who underwent both THA and LSF surgeries. Patients were identified from the regional arthroplasty data base and cross linked to patients with LSF from the regional hospital discharge database between 2000 and 2017. Demographic data, diagnosis leading to primary THA, primary implant survival, perioperative complications, number and causes of failure, and patients requiring revision arthroplasty were collated and compared. For comparison, data from 67,919 primary THAs performed during the same time time period were also retrieved and analyzed. Results. Patients undergoing THA and LSF showed homogeneous demographic data compared to those undergoing THA alone, but a significantly lower eight-year THA implant survival (96.7 vs 96.0, p = 0.024) was observed. Moreover, THA plus LSF patients showed increased incidence of mechanical complications in the first two years after THA surgery compared to THA alone patients. Conclusion. This registry-based population study shows that approximately 679 (1%) THA patients were subjected to LSF. Patients undergoing THA and LSF have an increased risk of mechanical complications with their THA and a slightly increased risk of revision arthroplasty. Cite this article: Bone Joint J 2021;103-B(3):486–491

Aims. The purpose of this study is to evaluate early outcomes with the use of a smartphone-based exercise and educational care management system after total hip arthroplasty (THA) and demonstrate decreased use of in-person physiotherapy (PT). Methods. A multicentre, prospective randomized controlled trial was conducted to evaluate a smartphone-based care platform for primary THA. Patients randomized to the control group (198) received the institution’s standard of care. Those randomized to the treatment group (167) were provided with a smartwatch and smartphone application. PT use, THA complications, readmissions, emergency department/urgent care visits, and physician office visits were evaluated. Outcome scores include the Hip disability and Osteoarthritis Outcome Score (HOOS, JR), health-related quality-of-life EuroQol five-dimension five-level score (EQ-5D-5L), single leg stance (SLS) test, and the Timed Up and Go (TUG) test. Results. The control group was significantly younger by a mean 3.0 years (SD 9.8 for control, 10.4 for treatment group; p = 0.007), but there were no significant differences between groups in BMI, sex, or preoperative diagnosis. Postoperative PT use was significantly lower in the treatment group (34%) than in the control group (55.4%; p = 0.001). There were no statistically significant differences in complications, readmissions, or outpatient visits. The 90-day outcomes showed no significant differences in mean hip flexion between controls (101° (SD 10.8)) and treatment (100° (SD 11.3); p = 0.507) groups. The HOOS, JR scores were not significantly different between control group (73 points (SD 13.8)) and treatment group (73.6 points (SD 13); p = 0.660). Mean 30-day SLS time was 22.9 seconds (SD 19.8) in the control group and 20.7 seconds (SD 19.5) in the treatment group (p = 0.342). Mean TUG time was 11.8 seconds (SD 5.1) for the control group and 11.9 (SD 5) seconds for the treatment group (p = 0.859). Conclusion. The use of the smartphone care management system demonstrated similar early outcomes to those achieved using traditional care models, along with a significant decrease in PT use. Noninferiority was demonstrated with regard to complications, readmissions, and ED and urgent care visits. This technology allows patients to rehabilitate on a more flexible schedule and avoid unnecessary healthcare visits, as well as potentially reducing overall healthcare costs. Cite this article: Bone Joint J 2021;103-B(7 Supple B):91–97

Aims. Adverse local tissue reactions associated with abnormal wear considerably slowed down the general use of metal-on-metal (MoM) hip resurfacing arthroplasty (HRA), now limited to a few specialized centres. In this study, we provide the clinical results of 400 consecutive MoM HRAs implanted more than 20 years ago in one such centre. Methods. A total of 355 patients (400 hips) were treated with Conserve Plus HRA between November 1996 and November 2000. There were 96 female (27%) and 259 male patients (73%). Their mean age was 48.2 years (SD 10.9). The University of California, Los Angeles (UCLA) hip scores and 12-item Short Form Survey (SF-12) quality of life scores were reported. Survivorship was assessed using Kaplan-Meier analyses. Results. The mean follow-up was 16.5 years (0.1 to 24.0), including 34 patients (37 hips) who died. The mean UCLA hip scores were 9.3 (2 to 10), 9.1 (3 to 10), 9.0 (3 to 10), and 6.9 (2 to 10) for pain, walking, function, and activity, respectively. The mean SF-12 scores were 48.4 (16.0 to 62.1) for the physical component and 48.5 (10.5 to 66.5) for the mental component, and did not differ from those of the general population of the USA. A total of 60 hips in 55 patients were revised. Using revision for any indication as the endpoint, the Kaplan-Meier survivorship was 83.5% at 20 years. A diagnosis of developmental dysplasia (hazard ratio (HR) 2.199 (95% confidence interval (CI) 1.140 to 4.239); p = 0.019) and a low BMI (HR 0.931 (95% CI 0.873 to 0.994); p = 0.032) were risk factors for revision. Female sex was a risk factor only because of hip dysplasia and small component size. There were no cases of metal sensitivity associated with revision surgery. Radiological analysis showed persistent fixation in all but one hip. Conclusion. The 83.5% 20-year survivorship of this initial series surpasses that of total hip arthroplasties in use 20 years ago in these young patients, suggesting satisfactory lifelong durability of the device for almost all of the remaining patients. Cite this article: Bone Joint J 2021;103-B(7 Supple B):25–32

Aims. Prosthetic joint infection (PJI) and aseptic loosening in total hip arthroplasty (THA) can present with pain and osteolysis. The Musculoskeletal Infection Society (MSIS) has provided criteria for the diagnosis of PJI. The aim of our study was to analyze the utility of F18-fluorodeoxyglucose (FDG) positron emission tomography (PET) CT scan in the preoperative diagnosis of septic loosening in THA, based on the current MSIS definition of prosthetic joint infection. Patients and Methods. A total of 130 painful unilateral cemented THAs with a mean follow-up of 5.17 years (. sd. 1.12) were included in this prospective study. The mean patient age was 67.5 years (. sd. 4.85). Preoperative evaluation with inflammatory markers, aspiration, and an F18 FDG PET scan were performed. Diagnostic utility tests were also performed, based on the MSIS criteria for PJI and three samples positive on culture alone. Results. The mean erythrocyte sedimentation rate, C-reactive protein, and white cell count were 47.83 mm/hr, 25.21 mg/l, and 11.05 × 10. 9. /l, respectively. The sensitivity, specificity, accuracy, negative predictive value, and false-positive rate of FDG PET compared with MSIS criteria were 94.87%, 38.46 %, 56.38%, 94.59 %, and 60.21%, respectively. The false-positive rate of FDG PET compared with culture alone was 77.4%. Conclusion. FDG PET has a definitive role in the preoperative evaluation of suspected PJI. This the first study to evaluate its utility based on MSIS criteria and compare it with microbiology results alone. However, FDG PET has a high false-positive rate. Therefore, we suggest that F18 FDG PET is useful in confirming the absence of infection, but if positive, may not be confirmatory of PJI. Cite this article: Bone Joint J 2019;101-B:910–914