While THA is regarded as one of the most successful surgeries in medicine, recent studies have revealed that ideal acetabular cup implantation is achieved as little as 50% of the time. Malalignment of the acetabular component in THA may result in dislocation, reduced range of motion, or accelerated wear. Recently, robotic-assisted surgery has been introduced to reduce the errors in component placement. The purpose of this study is to longitudinally assess the accuracy of cup placement of a single surgeon at three points in time: directly following a total joint fellowship, after 10 years of experience with manual instrumentation, and directly after adopting robotic technology. Three hundred patients received THA at a single center by a single surgeon representing three series of 100 consecutive patients in each series. The first series A included the surgeon's first 100 THA patients following graduation from joint fellowship (2/2000–5/2002). The second series B included the surgeon's last 100 THA patients before adopting robotic technology (12/2010–1/2012) and the final series C included the surgeon's first 100 THA patients using robotic assistance (4/2012–4/2013). The post-operative abduction and version of the cup was measured using PACS imaging software from the AP and cross-table lateral radiographs. Abduction was measured using a transverse line at the level of the teardrop and the lateral opening angle of the cup relative to this reference line. Anteversion was measured using the ischial method described by Schmalzreid on the crosstable lateral view and accounts for pelvic flexion. The average inclination for the groups A, B, and C was 48.6 ± 7.6°, 37.4 ± 6.2°, and 39.6 ± 47.6°, respectively and for anteversion was 29.3 ± 10.3°, 26.6 ± 8.4°, and 23.6 ± 5.7°, respectively. The cup placement in the original series A was within the Lewinnek safe zone only 31% of the time. This increased to 45% in series B and up to 74% in series C (p < 0.05). With the robotic series C, the three-dimensional pre-operative plan was obtained from the software. The average error (final placement–plan) was −0.7 ± 2.1° for inclination and 1.1 ± 2.0° for version. 93% of the inclination measurements and 94% of the version measurements were within 5° of the plan and 100% of both measurements were within 10° of the plan. Of note, 8% of the robotic cases were actually planned outside of the Lewinnek safe zone to accommodate for patient deformity and optimize correction to achieve the targeted combined anteversion of the acetabular and femoral components. Robotic assistance in THA leads to significantly more precise acetabular cup placement. As measured by the Lewinnek safe zone, 10 years of experience resulted in a 45% increase in precision, while adding robotic assistance resulted in a 139% increase in precision compared to the surgeon's initial performance. With greater knowledge of ideal acetabular cup position, highly accurate techniques may allow surgeons to decrease the risk of dislocation, promote durability and improve the ability to restore appropriate leg length and offset

Introduction. The identification of biological markers associated to implant failure in THA (total hip arthroplasty) patients remains a challenge in orthopedic surgery. In this search, previous studies have been mainly focused on typical mediators associated to bone metabolism and inflammation. Our group has evaluated changes in serum levels of insulin-like growth factor binding protein-1 (IGFBP-1), a protein which is not directly related to bone homeostasis, in patients undergoing THA. Method. We assessed IGFBP-1 levels in serum obtained from 131 patients (58% female, 42 % male; age: 68 ± 13 years) who underwent THA in the Orthopedic Surgery and Traumatology Department of our institution. In this cohort, 57% of patients had metal on polyethylene (MoP) as hip-bearing surface combination, 17 % had ceramic on ceramic (CoC) and 26% of them did not have any prosthesis. A test based on an enzyme-linked immunosorbent assay (ELISA) was used to determine IGFBP-1 levels in serum obtained from these patients. Result. Our results showed a significant increase in IGFBP- 1 levels in MoP group as compared to CoC and control groups, in which no differences in quantified levels were detected. Further analysis revealed no significant differences in IGFBP-1 between cemented and non-cemented MoP bearings. We performed a ROC curve to evaluate the accuracy of serum IGFBP-1 in discriminating MoP from the rest of patients (area under the curve: 0.7; 95% confidence interval: 0,6-0.8; p<0.05) and established a cut-off value of 10.2 ng/ml, according to the Youden´s Index. Logistic regression analysis showed that patients with MoP bearing surfaces had a higher risk of increased IGFBP- 1 levels in serum (p<0.05, Odds Ratio: 6.7, 95% Confidence Interval 3.1 to 14.8). Conclusion. IGFBP- 1 levels are significantly elevated in THA patients with MoP bearing surfaces, suggesting that this protein might be a reliable biomarker for the outcome of patients implanted with MoP

Aims. The aim of this study was to evaluate the diagnostic accuracy of the absolute synovial polymorphonuclear neutrophil cell (PMN) count for the diagnosis or exclusion of periprosthetic joint infection (PJI) after total hip (THA) or knee arthroplasty (TKA). Methods. In this retrospective cohort study, 147 consecutive patients with acute or chronic complaints following THA and TKA were included. Diagnosis of PJI was established based on the 2018 International Consensus Meeting criteria. A total of 39 patients diagnosed with PJI (32 chronic and seven acute) and 108 patients with aseptic complications were surgically revised. Results. Using receiver operating characteristic curves and calculating the area under the curve (AUC), an optimal synovial cut-off value of 2,000 PMN/µl was determined (AUC 0.978 (95% confidence interval (CI) 0.946 to 1)). Using this cut-off, sensitivity and specificity of absolute synovial PMN count for PJI were 97.4% (95% CI 91.2 to 100) and 93.5% (95% CI 88.9 to 98.1), respectively. Positive and negative predictive value were 84.4% (95% CI 72.7 to 93.9) and 99.0% (95% CI 96.7 to 100), respectively. Exclusion of 20 patients with acute complications improved specificity to 97.9% (95% CI 94.6 to 100). Different cut-off values for THA (< 3,600 PMN/µl) and TKA (< 2,000 PMN/µl) were identified. Absolute synovial PMN count correlated strongly with synovial alpha-defensin (AD) (r = 0.759; p < 0.001). With a positive AD result, no additional PJI could be identified in any case. Conclusion. Absolute synovial PMN count is a widely available, rapid, cost-effective, and accurate marker in PJI diagnostics, whereas synovial AD appears to be a surrogate parameter of absolute synovial PMN count. Despite limitations in the early postoperative phase, wear, and rheumatic diseases in confirming PJI, an absolute synovial PMN count below 2,000/µl is highly suitable for ruling out PJI, with specific cut-off values for THA and TKA. Cite this article: Bone Joint J 2023;105-B(4):373–381

Aims. Total hip arthroplasty (THA) is a common procedure to address pain and enhance function in hip disorders such as osteoarthritis. Despite its success, postoperative patient recovery exhibits considerable heterogeneity. This study aimed to investigate whether patients follow distinct pain trajectories following THA and identify the patient characteristics linked to suboptimal trajectories. Methods. This retrospective cohort study analyzed THA patients at a large academic centre (NYU Langone Orthopedic Hospital, New York, USA) from January 2018 to January 2023, who completed the Patient-Reported Outcomes Measurement Information System (PROMIS) pain intensity questionnaires, collected preoperatively at one-, three-, six-, 12-, and 24-month follow-up times. Growth mixture modelling (GMM) was used to model the trajectories. Optimal model fit was determined by Bayesian information criterion (BIC), Vuong-Lo-Mendell-Rubin likelihood ratio test (VLMR-LRT), posterior probabilities, and entropy values. Association between trajectory groups and patient characteristics were measured by multinomial logistic regression using the three-step approach. Results. Among the 1,249 patients, a piecewise GMM model revealed three distinct pain trajectory groups: 56 patients (4.5%) in group 1; 1,144 patients (91.6%) in group 2; and 49 patients (3.9%) in group 3. Patients in group 2 experienced swift recovery post-THA and minimal preoperative pain. In contrast, groups 1 and 3 initiated with pronounced preoperative pain; however, only group 3 exhibited persistent long-term pain. Multinomial regression indicated African Americans were exceedingly likely to follow trajectory groups 1 (odds ratio (OR) 2.73) and 3 (OR 3.18). Additionally, odds of membership to group 3 increased by 12% for each BMI unit rise, by 19% for each added postoperative day, and by over four if discharged to rehabilitation services (OR 4.07). Conclusion. This study identified three distinct pain trajectories following THA, highlighting the role of individual patient factors in postoperative recovery. This emphasizes the importance of preoperatively addressing modifiable risk factors associated with suboptimal pain trajectories, particularly in at-risk patients. Cite this article: Bone Jt Open 2024;5(3):174–183

Aims. This study aimed to evaluate the accuracy of implant placement with robotic-arm assisted total hip arthroplasty (THA) in patients with developmental dysplasia of the hip (DDH). Methods. The study analyzed a consecutive series of 69 patients who underwent robotic-arm assisted THA between September 2018 and December 2019. Of these, 30 patients had DDH and were classified according to the Crowe type. Acetabular component alignment and 3D positions were measured using pre- and postoperative CT data. The absolute differences of cup alignment and 3D position were compared between DDH and non-DDH patients. Moreover, these differences were analyzed in relation to the severity of DDH. The discrepancy of leg length and combined offset compared with contralateral hip were measured. Results. The mean values of absolute differences (postoperative CT-preoperative plan) were 1.7° (standard deviation (SD) 2.0) (inclination) and 2.5° (SD 2.1°) (anteversion) in DDH patients, and no significant differences were found between non-DDH and DDH patients. The mean absolute differences for 3D cup position were 1.1 mm (SD 1.0) (coronal plane) and 1.2 mm (SD 2.1) (axial plane) in DDH patients, and no significant differences were found between two groups. No significant difference was found either in cup alignment between postoperative CT and navigation record after cup screws or in the severity of DDH. Excellent restoration of leg length and combined offset were achieved in both groups. Conclusion. We demonstrated that robotic-assisted THA may achieve precise cup positioning in DDH patients, and may be useful in those with severe DDH. Cite this article: Bone Joint Res 2021;10(10):629–638

The metal on metal implants was introduced without the proper stepwise introduction. The ASR resurfacing hip arthroplasty (RHA) withdrawn due to high clinical failure rates and the large diameter head THA (LDH-THA) are also widely abandoned. Early (2 year) radiostereometry studies does not support early instability as cause of failure but more likely metal wear products. A possible advantage may be maintenance of bone mineral density (BMD). We present 5 year prospective follow up from a randomized series, aiming to report changes from baseline and to investigate links between implant micromotion, Cr & Co ions and BMD. Patients eligible for an artificial hip were randomized to RHA, Biomet LDH-THA or standard Biometric THA. 19, 17 and 15 patients completed 5 year follow-up. All followed with BMD of the femur, acetabulum and for RHA the collum. RHA and THA with whole blood Co and Co. LDH-THA only at 5 year. RHA had marker based RSA of both components, cup only for LDH-THA. Translations were compiled to total translation (TT= √(x. 2. +y. 2. +z. 2. )). Data were collected at baseline, 8 weeks, 6 months, 1, 2 and 5 years. Statistical tests: ANCOVA for TT movement, Spearman's correlation for BMD, Cr, Co and BMI to TT at 5 years. RSA: The 5 year median (25%to75%) RHA cup translations were X=-0.00(−0.49 to 0.19) Y=0.15(−0.03 to 0.20), z=0.24(−0.42 to 0.37) and TT 0.58 (0.16 to 1.82) mm. For the LDH-THA X=−0.33(−0.90 to 0.20) Y=0.28(0.02 to 0.54), z=0.43(−1.12 to −0.19) and TT 1.06 (0.97 to 1.72) mm. The TT was statistically different (p<0.05) for the two cups. The RHA femoral component moved X=0.37(0.21 to 0.56) Y=0.02(−0.07 to 0.11), z=-0.01(−0.07 to 0.26) and TT 0.48 (0.29 to 0.60) mm at 5 years. There was no TT movement from year 2. The mean (SD) acetabular BMD was diminished to 93(90–97)% for RHA and 97(93–99.9)% for THA, but LDH-THA maintained 99(95–103)%. Overall femoral BMD was unchanged at 5 years for all interventions, but both stemmed implants lost 17% at the calcar. Median (25%to75%) whole-blood Cr peaked in the LDH-THA group with 1.7 (0.9 to 3.1) followed by RHA 1.2 (0.8 to 5.0) and THA with 0.5 (0.4 to 0.7)ppb. For Co the highest levels were found in RHA with 1.6(0.8 to 4.7) followed by LDH-THA 1.2 (0.7–1.7) and THA 0.2 (0.2 to 0.6) ppb. The only correlations above +/−0.3 for TT were the RHA femoral component with a correlation of 0.47 to BMI, 0.30 to Co and Cr. The ASR cup conversely had a negative correlation of −0.60 to BMI and again, the LDH-THA cup had a negative correlation of −0.37 to Cr. In contrast to registered revision rates, we found significantly larger movement for the Biomet cup than the ASR cup. The metal ion levels were similar. The LDH-THA cup maintained the acetabular BMD best at 5 years, but the difference was small, we are limited by small numbers and the correlations between TT and the covariates showed no clear pattern

Acetabular component positioning is commonly referenced with the pelvis in the supine position in direct anterior approach THA. Changes in pelvic tilt (PT) from the pre-operative supine to the post-operative standing positions have not been well investigated and may have relevance to optimal acetabular component targeting for reduced risk of impingement and instability. The aims of this study were therefore to determine the change in PT that occurs from pre-operative supine to post-operative standing, and whether any factors are associated with significant changes in tilt ≥13° in posterior direction. 13° in a posterior direction was chosen as that amount of posterior rotation creates an increase in functional anteversion of the acetabular component of 10°. 1097 THA patients with pre-operative supine CT and standing lateral radiographic imaging and 1 year post-operative standing lateral radiographs (interquartile range 12–13 months) were reviewed. Pre-operative supine PT was measured from CT as the angle between the anterior pelvic plane (APP) and the horizontal plane of the CT device. Standing PT was measured on standing lateral x-rays as the angle between the APP and the vertical line. Patients with ≥13° change from supine pre-op to standing post-op (corresponding to a 10° change in cup anteversion) were grouped and compared to those with a <13° change using unpaired student's t-tests. Mean pre-operative supine PT (3.8±6.0°) was significantly different from mean post-operative standing PT (−3.5±7.1°, p<0.001), ie mean change of −7.3±4.6°. 10.4% (114/1097) of patients had posterior PT changes ≥13° supine pre-op to standing post-op. A significant number of patients, ie 1 in 10, undergo a clinically significant change in PT and functional anteversion from supine pre-op to standing post-op. Surgeons should be aware of these changes when planning component placement in THA

Aims. Transfusion after primary total hip arthroplasty (THA) has become rare, and identification of causative factors allows preventive measures. The aim of this study was to determine patient-specific factors that increase the risk of needing a blood transfusion. Methods. All patients who underwent elective THA were analyzed retrospectively in this single-centre study from 2020 to 2021. A total of 2,892 patients were included. Transfusion-related parameters were evaluated. A multiple logistic regression was performed to determine whether age, BMI, American Society of Anesthesiologists (ASA) grade, sex, or preoperative haemoglobin (Hb) could predict the need for transfusion within the examined patient population. Results. The overall transfusion rate was 1.2%. Compared to the group of patients without blood transfusion, the transfused group was on average older (aged 73.8 years (SD 9.7) vs 68.6 years (SD 10.1); p = 0.020) and was mostly female (p = 0.003), but showed no significant differences in terms of BMI (28.3 kg/m. 2. (SD 5.9) vs 28.7 kg/m. 2. (SD 5.2); p = 0.720) or ASA grade (2.2 (SD 0.5) vs 2.1 (SD 0.4); p = 0.378). The regression model identified a cutoff Hb level of < 7.6 mmol/l (< 12.2 g/dl), aged > 73 years, and a BMI of 35.4 kg/m² or higher as the three most reliable predictors associated with postoperative transfusion in THA. Conclusion. The possibility of transfusion is predictable based on preoperatively available parameters. The proposed thresholds for preoperative Hb level, age, and BMI can help identify patients and take preventive measures if necessary. Cite this article: Bone Jt Open 2024;5(7):560–564

Dislocation is one of the most common complications in total hip arthroplasty (THA) and is primarily driven by bony or prosthetic impingement. The aim of this study was two-fold. First, to develop a simulation that incorporates the functional position of the femur and pelvis and instantaneously determines range of motion (ROM) limits. Second, to assess the number of patients for whom their functional bony alignment escalates impingement risk. 468 patients underwent a preoperative THA planning protocol that included functional x-rays and a lower limb CT scan. The CT scan was segmented and landmarked, and the x-rays were measured for pelvic tilt, femoral rotation, and preoperative leg length discrepancy (LLD). All patients received 3D templating with the same implant combination (Depuy; Corail/Pinnacle). Implants were positioned according to standardised criteria. Each patient was simulated in a novel ROM simulation that instantaneously calculates bony and prosthetic impingement limits in functional movements. Simulated motions included flexion and standing-external rotation (ER). Each patient's ROM was simulated with their bones oriented in both functional and neutral positions. 13% patients suffered a ROM impingement for functional but not neutral extension-ER. As a result, 48% patients who failed the functional-ER simulation would not be detected without consideration of the functional bony alignment. 16% patients suffered a ROM impingement for functional but not neutral flexion. As a result, 65% patients who failed the flexion simulation would not be detected without consideration of the functional bony alignment. We have developed a ROM simulation for use with preoperative planning for THA surgery that can solve bony and prosthetic impingement limits instantaneously. The advantage of our ROM simulation over previous simulations is instantaneous impingement detection, not requiring implant geometries to be analysed prior to use, and addressing the functional position of both the femur and pelvis

Smartphone-based apps that measure step-count and patient reported outcomes (PROMs) are being increasingly used to quantify recovery in total hip arthroplasty (THA). However, optimum patient-specific activity level before and during THA early-recovery is not well characterised. This study investigated 1) correlations between step-count and PROMs and 2) how patient demographics impact step-count preoperatively and during early postoperative recovery. Smartphone step-count and PROM data from 554 THA patients was retrospectively reviewed. Mean age was 64±10yr, BMI was 29±13kg/m2, 56% were female. Mean daily step count was calculated over three time-windows: 60 days prior to surgery (preop), 5–6 weeks postop (6wk), and 11–12 weeks postop (12wk). Linear correlations between step-count and HOOS12 Function and UCLA activity scores were performed. Patients were separated into three step-count levels: low (<2500steps/day), medium (2500-5500steps/day), and high (>5500steps/day). Age >65years, BMI >30, and sex were used for demographic comparisons. Student's t-tests determined significant differences in mean step-counts between demographic groups and in mean PROMs between step-count groups. UCLA correlated with step-count at all time-windows (p<0.01). HOOS12 Function correlated with step-count preoperatively and at 6wk (p<0.01). High vs low step count individuals had improved UCLA scores preoperatively (∆1.8,p<0.001), at 6wk (∆1.1,p<0.05), and 12wk (∆1.6,p<0.01), and improved HOOS12 Function scores preoperatively (∆8.4,p<0.05) and at 6wk (∆8.8,p<0.001). Younger patients had greater step-count preoperatively (4.1±3.0k vs 3.0±2.5k, p<0.01) and at 12wk (5.1±3.3k vs 3.6±2.9k, p<0.01). Males had greater step-count preoperatively (4.1±3.0k vs. 3.0±2.7k, p<0.001), at 6wk (4.5±3.2k vs 2.6±2.5k, p<0.001), and at 12wk (5.2±3.6k vs. 3.4±2.5k, p<0.001). Low BMI patients had greater step-count at 6wk (4.3±3.3k vs. 2.6±2.7k, p<0.01) and 12wk (5.0±3.6k vs. 3.6±2.6k, p<0.05). Daily step-count is significantly impacted by patient demographics and correlates with PROMs, where patients with high step count exhibit improved PROMs. Generic recovery profiles may therefore not be appropriate for benchmarking across diverse populations

Aims. The aim of this study was to determine whether total hip arthroplasty (THA) for chronic hip pain due to unilateral primary osteoarthritis (OA) has a beneficial effect on cognitive performance. Methods. A prospective cohort study was conducted with 101 patients with end-stage hip OA scheduled for THA (mean age 67.4 years (SD 9.5), 51.5% female (n = 52)). Patients were assessed at baseline as well as after three and months. Primary outcome was cognitive performance measured by d2 Test of Attention at six months, Trail Making Test (TMT), FAS-test, Rivermead Behavioural Memory Test (RBMT; story recall subtest), and Rey-Osterrieth Complex Figure Test (ROCF). The improvement of cognitive performance was analyzed using repeated measures analysis of variance. Results. At six months, there was significant improvement in attention, working speed and concentration (d2-test; p < 0.001), visual construction and visual memory (ROCF; p < 0.001), semantic memory (FAS-test; p = 0.009), verbal episodic memory (RBMT; immediate recall p = 0.023, delayed recall p = 0.026), as well as pain (p < 0.001) with small to large effect sizes. Attention, concentration, and visual as well as verbal episodic memory improved significantly with medium effect sizes over η. 2. partial. = 0.06. In these cognitive domains the within-group difference exceeded the minimum clinically important difference. Conclusion. THA is associated with clinically relevant postoperative improvement in the cognitive functions of attention, concentration, and memory. These data support the concept of a broad interaction of arthroplasty with central nervous system function. Cite this article: Bone Joint J 2022;104-B(3):331–340

Aims. Iliopsoas impingement occurs in 4% to 30% of patients after undergoing total hip arthroplasty (THA). Despite a relatively high incidence, there are few attempts at modelling impingement between the iliopsoas and acetabular component, and no attempts at modelling this in a representative cohort of subjects. The purpose of this study was to develop a novel computational model for quantifying the impingement between the iliopsoas and acetabular component and validate its utility in a case-controlled investigation. Methods. This was a retrospective cohort study of patients who underwent THA surgery that included 23 symptomatic patients diagnosed with iliopsoas tendonitis, and 23 patients not diagnosed with iliopsoas tendonitis. All patients received postoperative CT imaging, postoperative standing radiography, and had minimum six months’ follow-up. 3D models of each patient’s prosthetic and bony anatomy were generated, landmarked, and simulated in a novel iliopsoas impingement detection model in supine and standing pelvic positions. Logistic regression models were implemented to determine if the probability of pain could be significantly predicted. Receiver operating characteristic curves were generated to determine the model’s sensitivity, specificity, and area under the curve (AUC). Results. Highly significant differences between the symptomatic and asymptomatic cohorts were observed for iliopsoas impingement. Logistic regression models determined that the impingement values significantly predicted the probability of groin pain. The simulation had a sensitivity of 74%, specificity of 100%, and an AUC of 0.86. Conclusion. We developed a computational model that can quantify iliopsoas impingement and verified its accuracy in a case-controlled investigation. This tool has the potential to be used preoperatively, to guide decisions about optimal cup placement, and postoperatively, to assist in the diagnosis of iliopsoas tendonitis. Cite this article: Bone Jt Open 2023;4(1):3–12

Aims. Large acetabular bone defects encountered in revision total hip arthroplasty (THA) are challenging to restore. Metal constructs for structural support are combined with bone graft materials for restoration. Autograft is restricted due to limited volume, and allogenic grafts have downsides including cost, availability, and operative processing. Bone graft substitutes (BGS) are an attractive alternative if they can demonstrate positive remodelling. One potential product is a biphasic injectable mixture (Cerament) that combines a fast-resorbing material (calcium sulphate) with the highly osteoconductive material hydroxyapatite. This study reviews the application of this biomaterial in large acetabular defects. Methods. We performed a retrospective review at a single institution of patients undergoing revision THA by a single surgeon. We identified 49 consecutive patients with large acetabular defects where the biphasic BGS was applied, with no other products added to the BGS. After placement of metallic acetabular implants, the BGS was injected into the remaining bone defects surrounding the new implants. Patients were followed and monitored for functional outcome scores, implant fixation, radiological graft site remodelling, and revision failures. Results. Mean follow-up was 39.5 months (36 to 71), with a significant improvement in post-revision function compared to preoperative function. Graft site remodelling was rated radiologically as moderate in 31 hips (63%) and strong in 12 hips (24%). There were no cases of complete graft site dissolution. No acetabular loosening was identified. None of the patients developed clinically significant heterotopic ossification. There were twelve reoperations: six patients developed post-revision infections, three experienced dislocations, two sustained periprosthetic femur fractures, and one subject had femoral component aseptic loosening. Conclusion. Our series reports bone defect restoration with the sole use of a biphasic injectable BGS in the periacetabular region. We did not observe significant graft dissolution. We emphasize that successful graft site remodelling requires meticulous recipient site preparation. Cite this article: Bone Jt Open 2022;3(12):991–997

We report the outcome of 320 primary Total Hip Arthroplasties (THA) with minimum 10-year follow-up (range 10–17 years, mean 12.6 years), performed by a single surgeon in Tauranga New Zealand, with the Exeter Contemporary Flanged all-polyethylene cup and Exeter femoral stem via a posterior approach. The aim of the study is to compare the results with the published results from the design centre and create a baseline cohort for further outcomes research in this centre. All patients were prospectively followed at 6 weeks, 1 year, 5 years, 10 years, (and 15 years when available). Of 333 cases that matched the inclusion criteria, 13 procedures in 12 patents were excluded because of concomitant bone grafting and/or supplementary cage fixation, leaving 320 primary THA procedures in 280 patients, including 26 bilateral procedures in 13 patients. Mean follow-up of the surviving cases was 12.6 (range 5.0-17.1) years. There were 12 revisions – 2 for fracture, 5 for instability, 1 for impingement pain and 4 for infection. There were no revisions for aseptic cup loosening. Kaplan-Meier survivorship with revision for aseptic loosening as the endpoint was 100% at 15.0 years (with minimum 40 cases remaining at risk). All-cause acetabular revision in 12 cases result in a Kaplan-Meier survival of 95.9% (95% CI: 93.5 to 98.3%). Cemented THA with the Exeter Contemporary Flanged cup and the Exeter stem is a durable combination with results that can be replicated outside of the design centre. The Exeter Contemporary Flanged cup has excellent survivorship at 15 years when used with the Exeter stem. Cemented THA with well-proven components should be considered the benchmark against which newer designs and materials should be compared

Aims. Acetabular fractures are associated with long-term morbidity. Our prospective cohort study sought to understand the recovery trajectory of this injury over five years. Methods. Eligible patients at a level I trauma centre were recruited into a longitudinal registry of surgical acetabular fractures between June 2004 and August 2019. Patient-reported outcome measures (PROMs), including the 36-Item Short Form Health Survey (SF-36) physical component summary (PCS), were recorded at baseline pre-injury recall and six months, one year, two years, and five years postoperatively. Comparative analyses were performed for elementary and associated fracture patterns. The proportion of patients achieving minimal clinically important difference (MCID) was determined. The rate of, and time to, conversion to total hip arthroplasty (THA) was also established. Results. We recruited 251 patients (253 fractures), with a 4:1 male to female ratio and mean age of 46.1 years (SD 16.4). Associated fracture patterns accounted for 56.5% of fractures (n = 143). Trajectory analysis showed all timepoints had significant disability versus baseline, including final follow-up (p < 0.001). Elementary fractures had higher SF-36 PCS at six months (p = 0.023) and one year (p = 0.007) compared to associated fractures, but not at two years (p = 0.135) or five years (p = 0.631). The MCID in SF-36 PCS was observed in 37.3% of patients (69/185) between six months and one year, 26.9% of patients (39/145) between one and two years, and 23.3% of patients (20/86) between two and five years, highlighting the long recovery potential of these injuries. A significant proportion of patients failed to attain the MCID after five years (38.1%; 40/105). Conversion to THA occurred in 13.1% of patients (11/110 elementary and 22/143 associated fractures). Approximately two-thirds of THAs (21/33 patients; 63.6%) were performed within two years of index surgery. Conclusion. Acetabular fractures significantly impact physical function. Recovery trajectory is often elongated beyond one year, with two-thirds of our patients displaying persistent clinically relevant long-term disability. Cite this article: Bone Joint J 2024;106-B(1):69–76

Acetabular implant position is important for the stability, function, and long-term wear properties of a total hip arthroplasty (THA). Prior studies of acetabular implant positioning have demonstrated a high percentage of outliers, even in experienced hip surgeons, when conventional instruments are used. Computer navigation is an attractive tool for use in THA, as it has been shown to improve the precision of acetabular component placement and reduce the incidence of outliers. However, computer navigation with imageless, large-console systems is costly and often interrupts the surgeon's workflow, and thus, has not been widely adopted. Another method to improve acetabular component positioning during THA is the use of fluoroscopy with the direct anterior approach. Studies have demonstrated that the supine position of the patient during surgery facilitates the use of fluoroscopic guidance, thus improving acetabular component position. A handheld, accelerometer-based navigation unit for use in total hip replacement has recently become available to assist the surgeon in positioning the acetabular component during anterior approach THA, potentially reducing the need for intra-operative fluoroscopic studies. We sought to compare the radiographic results of direct anterior THA performed with conventional instrumentation vs. handheld navigation to determine the accuracy of the navigation unit, and to see whether or not there was a reduction in the fluoroscopic time used during surgery. Furthermore, we timed the use of the navigation unit to see whether or not it required a substantial addition to surgical time. Our results demonstrate that a handheld navigation unit used during anterior approach THA had no difference with regard to acetabular cup positioning when compared to fluoroscopically assisted THA, but led to a reduction in the use of intra-operative fluoroscopy time

As the American population ages and a trend toward performing total hip arthroplasty (THA) in younger patients continues, the number of Americans undergoing THA is projected to increase over time. The advent of the bundled payment system combined with the current medical utilization climate has placed considerable pressure on surgeons to produce excellent results with early functional recovery and short hospital stays. The US obesity epidemic has transcended into the arthroplasty patient population and surgeons must assess whether obesity is a risk factor for poor outcomes in THA and determine how it should be managed. We performed a recent literature review to determine how obesity impacts outcomes in total hip arthroplasty and what must be done to improve outcomes in the obese arthroplasty patient. Our goal is to answer 3 questions: does obesity increase the complication rate in THA, if obesity matters how obese is too obese, and what must be done to improve outcomes in the obese patient?. Ultimately, obesity has been shown to correlate with increased post-operative complications in THA. The arthroplasty surgeon must optimise the obese patient prior to surgery by identifying associated comorbidities and consider malnutrition screening with counseling. Notice should be taken of the degree of obesity as patients with BMI > 40 have demonstrated much higher complication rates. Strong consideration should be given to avoiding direct anterior approach in the obese patient. Healthy weight loss must be encouraged with appropriate patient counseling and treatment in order to achieve success with THA in obese patients.  

Aims. To investigate the extent of bone development around the scaffold of custom triflange acetabular components (CTACs) over time. Methods. We performed a single-centre historical prospective cohort study, including all patients with revision THA using the aMace CTAC between January 2017 and March 2021. A total of 18 patients (18 CTACs) were included. Models of the hemipelvis and the scaffold component of the CTACs were created by segmentation of CT scans. The CT scans were performed immediately postoperatively and at least one year after surgery. The amount of bone in contact with the scaffold was analyzed at both times, and the difference was calculated. Results. The mean time between the implantation and the second CT scan was two years (1 to 5). The mean age of the patients during CTAC implantation was 75 years (60 to 92). The mean scaffold-bone contact area increased from 16% (SD 12.6) to 28% (SD 11.9). The mean scaffold-bone distance decreased from a mean of 6.5 mm (SD 2.0) to 5.5 mm (SD 1.6). None of the CTACs were revised or radiologically loose. Conclusion. There was a statistically significant increase of scaffold-bone contact area over time, but the total contact area of the scaffold in relation to the acetabular bone remained relatively low. As all implants remained well fixed, the question remains to what extend the scaffold contributes to the observed stability, in relation to the screws. A future design implication might be an elimination of the bulky scaffold component. This design modification would reduce production costs and may optimize the primary fit of the implant. Cite this article: Bone Joint J 2024;106-B(4):359–364

Aims. Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are common orthopaedic procedures requiring postoperative radiographs to confirm implant positioning and identify complications. Artificial intelligence (AI)-based image analysis has the potential to automate this postoperative surveillance. The aim of this study was to prepare a scoping review to investigate how AI is being used in the analysis of radiographs following THA and TKA, and how accurate these tools are. Methods. The Embase, MEDLINE, and PubMed libraries were systematically searched to identify relevant articles. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for scoping reviews and Arksey and O’Malley framework were followed. Study quality was assessed using a modified Methodological Index for Non-Randomized Studies tool. AI performance was reported using either the area under the curve (AUC) or accuracy. Results. Of the 455 studies identified, only 12 were suitable for inclusion. Nine reported implant identification and three described predicting risk of implant failure. Of the 12, three studies compared AI performance with orthopaedic surgeons. AI-based implant identification achieved AUC 0.992 to 1, and most algorithms reported an accuracy > 90%, using 550 to 320,000 training radiographs. AI prediction of dislocation risk post-THA, determined after five-year follow-up, was satisfactory (AUC 76.67; 8,500 training radiographs). Diagnosis of hip implant loosening was good (accuracy 88.3%; 420 training radiographs) and measurement of postoperative acetabular angles was comparable to humans (mean absolute difference 1.35° to 1.39°). However, 11 of the 12 studies had several methodological limitations introducing a high risk of bias. None of the studies were externally validated. Conclusion. These studies show that AI is promising. While it already has the ability to analyze images with significant precision, there is currently insufficient high-level evidence to support its widespread clinical use. Further research to design robust studies that follow standard reporting guidelines should be encouraged to develop AI models that could be easily translated into real-world conditions. Cite this article: Bone Joint J 2022;104-B(8):929–937