We have investigated whether control of balance is improved during stance and gait and sit-to-stand tasks after unilateral total hip replacement undertaken for osteoarthritis of the hip. We examined 25 patients with a mean age of 67 years (. sd. 6.2) before and at four and 12 months after surgery and compared the findings with those of 50 healthy age-matched control subjects. For all tasks, balance was quantified using angular measurements of movement of the trunk. Before surgery, control of balance during gait and sit-to-stand tasks was abnormal in patients with severe osteoarthritis of the hip, while balance during stance was similar to that of the healthy control group. After total hip replacement, there was a progressive improvement at four and 12 months for most gait and sit-to-stand tasks and in the time needed to complete them. By 12 months, the values approached those of the control group. However, trunk pitch (forwards-backwards) and roll (side-to-side) velocities were less stable (greater than the control) when walking over barriers as was roll for the sit-to-stand task, indicative of a residual deficit of balance. Our data suggest that patients with symptomatic osteoarthritis of the hip have marked deficits of balance in gait tasks, which may explain the increased risk of falling which has been reported in some epidemiological studies. However, total hip replacement may help these patients to regain almost normal control of balance for some gait tasks, as we found in this study. Despite the improvement in most components of balance, however, the deficit in the control of trunk velocity during gait suggests that a cautious follow-up is required after total hip replacement regarding the risk of a fall, especially in the elderly

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The purpose of this study was to evaluate spinopelvic mechanics from standing and sitting positions in subjects with and without femoroacetabular impingement (FAI). We hypothesize that FAI patients will experience less flexion at the lumbar spine and more flexion at the hip whilst changing from standing to sitting positions than subjects without FAI. This increase in hip flexion may contribute to symptomatology in FAI.

Aims. Adverse spinal motion or balance (spine mobility) and adverse pelvic mobility, in combination, are often referred to as adverse spinopelvic mobility (SPM). A stiff lumbar spine, large posterior standing pelvic tilt, and severe sagittal spinal deformity have been identified as risk factors for increased hip instability. Adverse SPM can create functional malposition of the acetabular components and hence is an instability risk. Adverse pelvic mobility is often, but not always, associated with abnormal spinal motion parameters. Dislocation rates for dual-mobility articulations (DMAs) have been reported to be between 0% and 1.1%. The aim of this study was to determine the early survivorship from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) of patients with adverse SPM who received a DMA. Methods. A multicentre study was performed using data from 227 patients undergoing primary total hip arthroplasty (THA), enrolled consecutively. All the patients who had one or more adverse spine or pelvic mobility parameter had a DMA inserted at the time of their surgery. The mean age was 76 years (22 to 93) and 63% were female (n = 145). At a mean of 14 months (5 to 31) postoperatively, the AOANJRR was analyzed for follow-up information. Reasons for revision and types of revision were identified. Results. The AOANJRR reported two revisions: one due to infection, and the second due to femoral component loosening. No revisions for dislocation were reported. One patient died with the prosthesis in situ. Kaplan-Meier survival rate was 99.1% (95% confidence interval 98.3 to 100) at 14 months (number at risk 104). Conclusion. In our cohort of patients undergoing primary THA with one or more factor associated with adverse SPM, DM bearings conferred stability at two years’ follow-up. Cite this article: Bone Joint J 2022;104-B(7):820–825

Aims. Pelvic incidence (PI) is a position-independent spinopelvic parameter traditionally used by spinal surgeons to determine spinal alignment. Its relevance to the arthroplasty surgeon in assessing patient risk for total hip arthroplasty (THA) instability preoperatively is unclear. This study was undertaken to investigate the significance of PI relative to other spinopelvic parameter risk factors for instability to help guide its clinical application. Methods. Retrospective analysis was performed of a multicentre THA database of 9,414 patients with preoperative imaging (dynamic spinopelvic radiographs and pelvic CT scans). Several spinopelvic parameter measurements were made by engineers using advanced software including sacral slope (SS), standing anterior pelvic plane tilt (APPT), spinopelvic tilt (SPT), lumbar lordosis (LL), and PI. Lumbar flexion (LF) was determined by change in LL between standing and flexed-seated lateral radiographs. Abnormal pelvic mobility was defined as ∆SPT ≥ 20° between standing and flexed-forward positions. Sagittal spinal deformity (SSD) was defined as PI-LL mismatch > 10°. Results. PI showed a positive correlation with parameters of SS, SPT, and LL (r-value range 0.468 to 0.661). Patients with a higher PI value showed higher degrees of standing LL, likely as a compensatory measure to maintain sagittal spine balance. There was a positive correlation between LL and LF such that patients with less standing LL had decreased LF (r = 0.49). Similarly, there was a positive correlation between increased SSD and decreased LF (r = 0.54). PI in isolation did not show any significant correlation with lumbar (r = 0.04) or pelvic mobility (r = 0.02). The majority of patients (range 89.4% to 94.2%) had normal lumbar and pelvic mobility regardless of the PI value. Conclusion. The PI value alone is not indicative of either spinal or pelvic mobility, and thus in isolation may not be a risk factor for THA instability. Patients with SSD had higher rates of spinopelvic stiffness, which may be the mechanism by which PI relates to THA instability risk, but further clinical studies are required. Cite this article: Bone Joint J 2022;104-B(3):352–358

Aims. Pelvic incidence (PI) is considered an important anatomical parameter for determining the sagittal balance of the spine. The contribution of an abnormal PI to hip osteoarthritis (OA) remains controversial. In this study, we aimed to investigate the relationship between PI and hip OA, and the difference in PI between hip OA without anatomical abnormalities (primary OA) and hip OA with developmental dysplasia of the hip (DDH-OA). Methods. In this study, 100 patients each of primary OA, DDH-OA, and control subjects with no history of hip disease were included. CT images were used to measure PI, sagittal femoral head coverage, α angle, and acetabular anteversion. PI was also subdivided into three categories: high PI (larger than 64.0°), medium PI (42.0° to 64.0°), and low PI (less than 42.0°). The anterior centre edge angles, posterior centre edge angles, and total sagittal femoral head coverage were measured. The correlations between PI and sagittal femoral head coverage, α angle, and acetabular anteversion were examined. Results. No significant difference in PI was observed between the three groups. There was no significant difference between the groups in terms of the category distribution of PI. The DDH-OA group had lower mean sagittal femoral head coverage than the other groups. There were no significant correlations between PI and other anatomical factors, including sagittal femoral head coverage, α angle, and acetabular anteversion. Conclusion. No associations were found between mean PI values or PI categories and hip OA. Furthermore, there was no difference in PI between patients with primary OA and DDH-OA. From our evaluation, we found no evidence of PI being an independent factor associated with the development of hip OA. Cite this article: Bone Joint J 2021;103-B(11):1656–1661

Aims. Cross-table lateral (CTL) radiographs are commonly used to measure acetabular component anteversion after total hip arthroplasty (THA). The CTL measurements may differ by > 10° from CT scan measurements but the reasons for this discrepancy are poorly understood. Anteversion measurements from CTL radiographs and CT scans are compared to identify spinopelvic parameters predictive of inaccuracy. Methods. THA patients (n = 47; 27 males, 20 females; mean age 62.9 years (SD 6.95)) with preoperative spinopelvic mobility, radiological analysis, and postoperative CT scans were retrospectively reviewed. Acetabular component anteversion was measured on postoperative CTL radiographs and CT scans using 3D reconstructions of the pelvis. Two cohorts were identified based on a CTL-CT error of ≥ 10° (n = 11) or < 10° (n = 36). Spinopelvic mobility parameters were compared using independent-samples t-tests. Correlation between error and mobility parameters were assessed with Pearson’s coefficient. Results. Patients with CTL error > 10° (10° to 14°) had stiffer lumbar spines with less mean lumbar flexion (38.9°(SD 11.6°) vs 47.4° (SD 13.1°); p = 0.030), different sagittal balance measured by pelvic incidence-lumbar lordosis mismatch (5.9° (SD 18.8°) vs -1.7° (SD 9.8°); p = 0.042), more pelvic extension when seated (pelvic tilt -9.7° (SD 14.1°) vs -2.2° (SD 13.2°); p = 0.050), and greater change in pelvic tilt between supine and seated positions (12.6° (SD 12.1°) vs 4.7° (SD 12.5°); p = 0.036). The CTL measurement error showed a positive correlation with increased CTL anteversion (r = 0.5; p = 0.001), standing lordosis (r = 0.23; p = 0.050), seated lordosis (r = 0.4; p = 0.009), and pelvic tilt change between supine and step-up positions (r = 0.34; p = 0.010). Conclusion. Differences in spinopelvic mobility may explain the variability of acetabular anteversion measurements made on CTL radiographs. Patients with stiff spines and increased compensatory pelvic movement have less accurate measurements on CTL radiographs. Flexion of the contralateral hip is required to obtain clear CTL radiographs. In patients with lumbar stiffness, this movement may extend the pelvis and increase anteversion of the acetabulum on CTL views. Reliable analysis of acetabular component anteversion in this patient population may require advanced imaging with a CT scan. Cite this article: Bone Joint J 2021;103-B(7 Supple B):59–65

Aims. The complex relationship between acetabular component position and spinopelvic mobility in patients following total hip arthroplasty (THA) renders it difficult to optimize acetabular component positioning. Mobility of the normal lumbar spine during postural changes results in alterations in pelvic tilt (PT) to maintain the sagittal balance in each posture and, as a consequence, markedly changes the functional component anteversion (FCA). This study aimed to investigate the in vivo association of lumbar degenerative disc disease (DDD) with the PT angle and with FCA during postural changes in THA patients. Methods. A total of 50 patients with unilateral THA underwent CT imaging for radiological evaluation of presence and severity of lumbar DDD. In all, 18 patients with lumbar DDD were compared to 32 patients without lumbar DDD. In vivo PT and FCA, and the magnitudes of changes (ΔPT; ΔFCA) during supine, standing, swing-phase, and stance-phase positions were measured using a validated dual fluoroscopic imaging system. Results. PT, FCA, ΔPT, and ΔFCA were significantly correlated with the severity of lumbar DDD. Patients with severe lumbar DDD showed marked differences in PT with changes in posture; there was an anterior tilt (-16.6° vs -12.3°, p = 0.047) in the supine position, but a posterior tilt in an upright posture (1.0° vs -3.6°, p = 0.005). A significant decrease in ΔFCA during stand-to-swing (8.6° vs 12.8°, p = 0.038) and stand-to-stance (7.3° vs 10.6°,p = 0.042) was observed in the severe lumbar DDD group. Conclusion. There were marked differences in the relationship between PT and posture in patients with severe lumbar DDD compared with healthy controls. Clinical decision-making should consider the relationship between PT and FCA in order to reduce the risk of impingement at large ranges of motion in THA patients with lumbar DDD. Cite this article: Bone Joint J 2020;102-B(11):1505–1510

Aims. Thresholds for operative eligibility based on body mass index (BMI) alone may restrict patient access to the benefits of arthroplasty. The purpose of this study was to evaluate the relationship between BMI and improvements in patient-reported outcome measures (PROMs), and to determine how many patients would have been denied improvements in PROMs if BMI cut-offs were to be implemented. Methods. A prospective cohort of 3,449 primary total hip arthroplasties (THAs) performed between 2015 and 2018 were analyzed. The following one-year PROMs were evaluated: hip injury and osteoarthritis outcome score (HOOS) pain, HOOS Physical Function Shortform (PS), University of California, Los Angeles (UCLA) activity, Veterans Rand-12 Physical Component Score (VR-12 PCS), and VR-12 Mental Component Score (VR-12 MCS). Positive predictive values for failure to improve and the number of patients denied surgery in order to avoid a failed improvement were calculated for each PROM at different BMI cut-offs. Results. There was a trend to improved outcomes in terms of pain and function improvements with higher BMI. Patients with BMI ≥ 40 kg/m. 2. had median (Q1, Q3) HOOS pain improvements of 58 points (interquartile range (IQR) 41 to 70) and those with BMI 35 to 40 kg/m. 2. had median improvements of 55 (IQR 40 to 68). With a BMI cut-off of 30 kg/m. 2. , 21 patients would have been denied a meaningful improvement in HOOS pain score in order to avoid one failed improvement. At a 35 kg/m. 2. cut-off, 18 patients would be denied improvement, at a 40 kg/m. 2. cut-off 21 patients would be denied improvement, and at a 45 kg/m. 2. cut-off 21 patients would be denied improvement. Similar findings were observed for HOOS-PS, UCLA, and VR-12 scores. Conclusion. Patients with higher BMIs show greater improvements in PROMs. Using BMI alone to determine eligibility criteria did not improve the rate of clinically meaningful improvements. BMI thresholds prevent patients who may benefit the most from surgery from undergoing THA. Surgeons should consider PROMs improvements in determining eligibility for THA while balancing traditional metrics of preoperative risk stratification. Cite this article: Bone Joint J 2020;102-B(6):683–692

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The aim of this study was to evaluate the reliability and validity of a patient-specific algorithm which we developed for predicting changes in sagittal pelvic tilt after total hip arthroplasty (THA).

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Cemented hemiarthroplasty is an effective form of treatment for most patients with an intracapsular fracture of the hip. However, it remains unclear whether there are subgroups of patients who may benefit from the alternative operation of a modern uncemented hemiarthroplasty – the aim of this study was to investigate this issue. Knowledge about the heterogeneity of treatment effects is important for surgeons in order to target operations towards specific subgroups who would benefit the most.

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The number of revision arthroplasties being performed in the elderly is expected to rise, including revision for infection. The primary aim of this study was to measure the treatment success rate for octogenarians undergoing revision total hip arthroplasty (THA) for periprosthetic joint infection (PJI) compared to a younger cohort. Secondary outcomes were complications and mortality.

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This study aims to assess the relationship between history of pseudotumour formation secondary to metal-on-metal (MoM) implants and periprosthetic joint infection (PJI) rate, as well as establish ESR and CRP thresholds that are suggestive of infection in these patients. We hypothesized that patients with a pseudotumour were at increased risk of infection.

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The aim of this study was to understand the experience of mature patients who undergo a periacetabular osteotomy (PAO), a major hip-preserving surgical procedure that treats symptomatic hip dysplasia by realigning the acetabulum. Our aim was to improve our understanding of how the operation affected the lives of patients and their families, with a long-term goal of improving their experience.

The interaction between the lumbosacral spine and the pelvis is dynamically related to positional change, and may be complicated by co-existing pathology. This review summarises the current literature examining the effect of sagittal spinal deformity on pelvic and acetabular orientation during total hip arthroplasty (THA) and provides recommendations to aid in placement of the acetabular component for patients with co-existing spinal pathology or long spinal fusions. Pre-operatively, patients can be divided into four categories based on the flexibility and sagittal balance of the spine. Using this information as a guide, placement of the acetabular component can be optimal based on the type and significance of co-existing spinal deformity. Cite this article: Bone Joint J 2015;97-B:1017–23

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Total hip arthroplasties (THAs) are performed by surgeons at various stages in training with varying levels of supervision, but we do not know if this is safe practice with comparable outcomes to consultant-performed THA. Our aim was to examine the association between surgeon grade, the senior supervision of trainees, and the risk of revision following THA.

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The aim of the study was to compare two methods of calculating pelvic incidence (PI) and pelvic tilt (PT), either by using the femoral heads or acetabular domes to determine the bicoxofemoral axis, in patients with unilateral or bilateral primary hip osteoarthritis (OA).

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Spinopelvic mobility plays an important role in functional acetabular component position following total hip arthroplasty (THA). The primary aim of this study was to determine if spinopelvic hypermobility persists or resolves following THA. Our second aim was to identify patient demographic or radiological factors associated with hypermobility and resolution of hypermobility after THA.

Aims. The place of thromboprophylaxis in arthroplasty surgery remains controversial, with a challenging requirement to balance prevention of potentially fatal venous thrombo-embolism with minimising wound-related complications leading to deep infection. We compared the incidence of fatal pulmonary embolism in patients undergoing elective primary total hip arthroplasty (THA) between those receiving aspirin, warfarin and low molecular weight heparin (LMWH) for the chemical component of a multi-modal thromboprophylaxis regime. Patients and Methods. A prospective audit database was used to identify patients who had died within 42 and 90 days of surgery respectively between April 2000 and December 2012. A case note review was performed to ascertain the causes of death. Results. During this period 7983 THAs were performed. The rate of mortality was 0.43% and 0.58% at 42 and 90 days respectively. The groups comprised 1571 patients (19.7%) on warfarin, 1838 (23.0%) on LMWH and 4574 (57.3%) on aspirin. The 90-day mortality for these three groups was 0.38%, 1.09% and 0.43% respectively. The higher mortality rate for LMWH was significant (p < 0.05). There were six fatal pulmonary emboli (PEs) (0.08%). A total of three occurred within 42 days, all in the LMWH group. A total of three occurred between 42 and 90 days; one on warfarin, two on LMWH. The leading causes of death in all three groups were lower respiratory tract infections and myocardial infarction. Conclusion. We confirmed that fatal PE following elective THA with a multi-modal prophylaxis regime is rare. We further found that LMWH conferred no benefit over aspirin in this context, and is associated with a higher all-cause rate of mortality. Take home message: This study proposes that aspirin may be an appropriate thromboprophylaxis agent when used as part of a multi-modal regimen, suggesting current guidelines should be reviewed. Cite this article: Bone Joint J 2016;98-B:585–8

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One-stage revision hip arthroplasty for periprosthetic joint infection (PJI) has several advantages; however, resection of the proximal femur might be necessary to achieve higher success rates. We investigated the risk factors for resection and re-revisions, and assessed complications and subsequent re-revisions.

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Rotational acetabular osteotomy (RAO) has been reported to be effective in improving symptoms and preventing osteoarthritis (OA) progression in patients with mild to severe develomental dysplasia of the hip (DDH). However, some patients develop secondary OA even when the preoperative joint space is normal; determining who will progress to OA is difficult. We evaluated whether the preoperative cartilage condition may predict OA progression following surgery using T2 mapping MRI.