Developmental dysplasia of the hip can cause pain and premature osteoarthritis. However, the risk factors and timing for disease progression in young adults are not fully defined. This study identified the incidence and risk factors for contralateral hip pain and surgery after periacetabular osteotomy (PAO) on an index dysplastic hip. Patients followed for 2+ years after unilateral PAO were grouped by eventual contralateral pain or no-pain, based on modified Harris Hip Score, and surgery or no-surgery. Univariate analysis tested group differences in demographics, radiographic measures, and range-of-motion. Kaplan-Meier survival analysis assessed pain development and contralateral hip surgery over time. Multivariate regression identified pain and surgery risk factors. Pain and surgery predictors were further analyzed in Dysplastic, Borderline, and Non-dysplastic subcategories, and in five-degree increments of lateral center edge angle (LCEA) and acetabular inclination (AI). 184 patients were followed for 4.6±1.6 years, during which 51% (93/184) reported hip pain and 33% (60/184) underwent contralateral surgery. Kaplan-Meier analysis predicted 5-year survivorship of 49% for pain development and 66% for contralateral surgery. Painful hips exhibited more severe dysplasia than no-pain hips (LCEA 16.5º vs 20.3º, p<0.001; AI 13.2º vs 10.0º p<0.001). AI was the sole predictor of pain, with every 1° AI increase raising the risk by 11%. Surgical hips also had more severe dysplasia (LCEA 14.9º vs 20.0º, p<0.001; AI 14.7º vs 10.2º p<0.001) and were younger (21.6 vs 24.1 years, p=0.022). AI and a maximum alpha angle ≥55° predicted contralateral surgery. 5 years after index hip PAO, 51% of contralateral hips experience pain and 34% percent are expected to need surgery. More severe dysplasia, based on LCEA and AI, increases the risk of contralateral hip pain and surgery, with AI being a predictor of both outcomes. Knowing these risks can inform patient counseling and treatment planning

Symptomatic and non-symptomatic hip osteonecrosis related to sickle cell disease (SCD) has a high risk of progression to collapse and total hip arthroplasty (THA) in this disease has a high rate of complications. We asked question about the benefit of performing an IRM to detect and treat with cell therapy an early (stage I or II) contralateral osteonecrosis. 430 consecutive SCD adult (32 years, 18 to 51) patients (225 males) with bilateral osteonecrosis (diagnosed with MRI) were included in this study from 1990 to 2010. One side with collapse was treated with THA and the contralateral without collapse (stage I or II) treated with cell therapy. The volume of osteonecrosis was measured with MRI. For cell therapy, the average total number of mesenchymal stem cells (MSCs) counted as number of colony forming units-fibroblast injected in each hip was 160,000 ± 45,000 cells (range 75,000 to 210,000 cells). At the most recent FU (20 years, range 10 to 30), among the 430 hips treated with cell therapy, 45 hips (10.5%) had collapsed and had required THA at 10 years (range 5 to 14 years) and 380 hips (88%) were without collapse and asymptomatic (or with few symptoms) with a decrease percentage of necrosis on MRI from 45% to 11%. Among the 430 contralateral THA, 96 (22.3%) had required one revision, 28 had a re-revision, and 12 a third re-revision with aseptic loosening (85% of revisions) and/or infection (6% of revisions). Hips undergoing cell therapy were approximately three times less likely to undergo revision or re-revision surgery (p < 0.01) as compared with hips undergoing a primary THA. THA is the usual treatment of collapsed ON in patients with SCD. In this population, it is worth looking with MRI for an early stage on the contralateral hip and performing (when necessary) bone marrow cell implantation during the same anesthesia as for arthroplasty

Aims. Increasingly, patients with bilateral hip arthritis wish to undergo staged total hip arthroplasty (THA). With the rise in demand for arthroplasty, perioperative risk assessment and counselling is crucial for shared decision making. However, it is unknown if complications that occur after a unilateral hip arthroplasty predict complications following surgery of the contralateral hip. Patients and Methods. We used nationwide linked discharge data from the Healthcare Cost and Utilization Project between 2005 and 2014 to analyze the incidence and recurrence of complications following the first- and second-stage operations in staged bilateral total hip arthroplasty (BTHAs). Complications included perioperative medical adverse events within 30 to 60 days, and infection and mechanical complications within one year. Conditional probabilities and odds ratios (ORs) were calculated to determine whether experiencing a complication after the first stage of surgery increased the risk of developing the same complication after the second stage. Results. A total of 13 829 patients (5790 men and 8039 women) who underwent staged BTHAs were analyzed. The mean age at first operation was 62.9 years (14 to 95). For eight of the 12 outcomes evaluated, patients who experienced the outcome following the first arthroplasty had a significantly increased probability and odds of developing that same complication following the second arthroplasty, compared with those who did not experience the complication after the first surgery. This was true for digestive complications (OR 25.67, 95% confidence interval (CI) 13.86 to 46.08; p < 0.001), urinary complications (OR 6.48, 95% CI 1.7 to 20.73; p = 0.01), haematoma (OR 12.17, 95% CI 4.55 to 31.14; p < 0.001), deep vein thrombosis (OR 4.82, 95% CI 2.34 to 9.65; p < 0.001), pulmonary embolism (OR 12.03, 95% CI 2.02 to 46.77; p = 0.01), deep hip infection (OR 534.21, 95% CI 314.96 to 909.25; p < 0.001), superficial hip infection (OR 1574.99, 95% CI 269.83 to 9291.81; p < 0.001), and mechanical malfunction (OR 117.49, 95% CI 91.55 to 150.34; p < 0.001). Conclusion. The occurrence of certain complications after unilateral THA is associated with an increased risk of the same complication occurring after staged arthroplasty of the contralateral hip. Patients who experience these complications after unilateral hip arthroplasty should be appropriately counselled regarding their risk profile prior to undergoing staged contralateral hip arthroplasty. Cite this article: Bone Joint J 2019;101-B(6 Supple B):77–83

Introduction. Increasingly, patients with bilateral hip arthritis wish to undergo staged total hip arthroplasty. With the rise in demand for arthroplasty perioperative risk assessment and counseling is critical for shared decision making; however, it is unknown if complications that occur after a unilateral hip arthroplasty predict complications following surgery of the contralateral hip. Methods. We used nation-wide linked discharge data from the Hospital Cost and Utilization Project from 2005–2014 to analyze the incidence and recurrence of complications following the first and second stage operations in staged bilateral total hip arthroplasty (BTHAs). Complications included perioperative risks within 30–60 days, and infection and mechanical complications within one year. Conditional probabilities and odds ratios were calculated to determine whether experiencing a complication after the first stage of surgery increased the risk of developing the same complication after the second stage. Results. 13,829 patients who underwent staged BTHAs were analyzed. For 6 of the 11 outcomes evaluated, patients who experienced the outcome following the first arthroplasty had a significantly increased probability and odds of developing that same complication following the second arthroplasty, compared to those who did not experience the complication after the first surgery. This was true for digestive complications (OR=25.67, 95% CI=13.86–46.08, p<0.001), hematoma (OR=12.17, 95% CI=4.55–31.14, p<0.001), deep vein thrombosis (OR=4.82, 95% CI=2.34–9.65, p<0.001), pulmonary embolism (OR=12.03, 95% CI=2.02–46.77, p=0.01), hip infection (OR=2439.48, 95% CI=836.73–6759.85, p<0.001), and mechanical malfunction (OR=117.49, 95% CI=91.55–150.34, p<0.001). Conclusions. The occurrence of certain complications after unilateral total hip arthroplasty is associated with an increased risk that the same complication will occur after staged replacement of the contralateral hip. Patients who experience these complications after unilateral hip arthroplasty should be appropriately counseled regarding their risk profile prior to undergoing staged contralateral hip arthroplasty. Level of Evidence: Therapeutic Level III. Keywords: hip arthroplasty; bilateral; staged; joint replacement

In the majority of patients with slipped upper femoral epiphysis only one hip is involved at primary diagnosis. However, the contralateral hip often becomes involved over time. There are no reliable factors predicting a contralateral slip. Whether or not the contralateral hip should undergo prophylactic fixation is a matter of controversy. We present a number of essential points that have to be considered both when choosing to fix the contralateral hip prophylactically as well as when refraining from surgery and instead following the patients with repeat radiographs

The aim of this study was to investigate the incidence of dysplasia in the ‘normal’ contralateral hip in patients with unilateral developmental dislocation of the hip (DDH) and to evaluate the long-term prognosis of such hips. A total of 48 patients (40 girls and eight boys) were treated for late-detected unilateral DDH between 1958 and 1962. After preliminary skin traction, closed reduction was achieved at a mean age of 17.8 months (4 to 65) in all except one patient who needed open reduction. In 25 patients early derotation femoral osteotomy of the contralateral hip had been undertaken within three years of reduction, and later surgery in ten patients. Radiographs taken during childhood and adulthood were reviewed. The mean age of the patients was 50.9 years (43 to 55) at the time of the latest radiological review. In all, eight patients (17%) developed dysplasia of the contralateral hip, defined as a centre-edge (CE) angle < 20° during childhood or at skeletal maturity. Six of these patients underwent surgery to improve cover of the femoral head; the dysplasia improved in two after varus femoral osteotomy and in two after an acetabular shelf operation. During long-term follow-up the dysplasia deteriorated to subluxation in two patients (CE angles 4° and 5°, respectively) who both developed osteoarthritis (OA), and one of these underwent total hip replacement at the age of 49 years. In conclusion, the long-term prognosis for the contralateral hip was relatively good, as OA occurred in only two hips (4%) at a mean follow-up of 50 years. Regular review of the ‘normal’ side is indicated, and corrective surgery should be undertaken in those who develop subluxation. Cite this article: Bone Joint J 2014; 96-B:1161–6

Aims. The purpose of this study was to examine whether leg-length discrepancy (LLD) following unilateral total hip arthroplasty (THA) affects the incidence of contralateral head collapse and subsequent THA in patients with bilateral osteonecrosis, and to determine factors associated with subsequent collapse. Patients and Methods. We identified 121 patients with bilateral non-traumatic osteonecrosis who underwent THA between 2003 and 2011 to treat a symptomatic hip, and who also exhibited medium-to-large lesions (necrotic area ≥ 30%) in an otherwise asymptomatic non-operated hip. Of the 121 patients, 71 were male (59%) and 50 were female (41%), with a mean age of 51 years (19 to 71) at the time of initial THA. All patients were followed for at least five years and were assessed according to the presence of a LLD (non-LLD vs LLD group), as well as the LLD type (longer non-operated side vs shorter non-operated side group). Results. Overall, 68 hips (56%) became painful and progressed to collapse at a mean of 2.6 years (0.2 to 13.8), resulting in 59 THAs (49%). The five-year collapse-free survival rate for the non-LLD group was 59% (95% confidence interval (CI) 46.8 to 71.8) compared with 45% (95% CI 32.9 to 57.5) for the LLD group (p = 0.036), and 66% (95% CI 55.2 to 77.2) for the longer non-operated side group compared with 32% (95% CI 19.1 to 44.9) for the shorter non-operated side group (p < 0.001). Multivariate regression analyses found that large lesions had a higher risk of collapse than medium-size lesions (odds ratio (OR) 4.19, 95% confidence interval (CI) 1.69 to 10.38; p = 0.002). Meanwhile, patients with a LLD < 3 mm (OR 0.20, 95% CI 0.08 to 0.52; p = 0.001) or a longer non-operated leg (OR 0.11, 95% CI 0.04 to 0.28; p < 0.001) after THA were less likely to experience a subsequent collapse. Conclusion. We found that LLD may be a modifiable risk factor for femoral head collapse. Minimizing LLD and particularly avoiding a shorter non-operated limb after THA may lead to a lower risk of collapse of the asymptomatic hip in patients with bilateral non-traumatic osteonecrosis. Cite this article: Bone Joint J 2019;101-B:303–310

The contralateral femur is frequently used for preoperative templating of total hip arthroplasty assuming femoral symmetry. We aimed to define the degree of asymmetry between left and right proximal femurs and whether if affected by demographics parameters. A CT-scan based modeling and analytics system of 346 CT-scans was used for this study, including pelvis and bilateral femora from 211 men and 135 women (mean age 61 ±16 years, mean BMI 26± 5 kg/m. 2). The femoral neck shaft angle (NSA), femoral offset (FO), femoral neck version (FNV), femoral length (FL), canal flare index (CFI) and femoral head diameter (FHD) were calculated for each patient. We then, analyzed symmetry based on absolute differences(AD) and percentage of asymmetry(%AS). An asymmetry >2% was found for NSA (mean AD=2.9°; mean %AS=2.3; p=0.03), FO (AD=3.8mm; %AS=9.1; p=0.01), FNV (AD=5.1°; %AS=46.7; p=0.001) and CFI (AD=0.2mm; %AS=5.4; p=0.7). Percentage of asymmetry was <2% for FL (AD=3.6mm; %AS=0.8; p=0.7) and FHD (AD=0.3mm; %AS=1.2; p=0.8). No correlation and predictive value was found between either AD or %AS and age, ethnicity, gender, height, weight or BMI. Our data support assumptions of substantial asymmetry of the proximal femur which is not affected by demographics or proximal femoral size. Clinical relevance: Upper femurs are not symmetric. Preoperative planning on contralateral femur might be affected this geometrical bias

There is still no clear consensus regarding which cup position might provide better functional performance for developmental dysplasia of the hip (DDH). This study aimed to evaluated the feasibility and efficacy of acetabular mirroring reconstruction for DDH in total hip arthroplasty (THA). The study reviewed 96 patients (96 hips) with unilateral Crowe type-II/III DDH undergoing either visualized navigation-assisted mirroring reconstruction with augment according to the rotation center and biomechanical structure of the contralateral normal hips (Mirroring group, 51 hips) or high hip center reconstruction (HHC group, 45 hips) in THA from 2020 to 2023. The functional and radiographic results were analyzed between the groups during a mean follow-up period of 27.5 and 28.9 months (a minimum follow-up of 12 months). The Harris hip score at the last follow-up significantly improved in both groups, while it was significantly higher in the mirroring group (P<0.001). In the HHC group, the rotation center height and greater trochanter height were significantly increased in the affected hip (P<0.001; P<0.001) and the abductor lever arm was significantly decreased in the affected hip compared to that in the contralateral normal hip (P<0.001), whereas in the mirroring group no significant statistical differences were observed between two sides. The limping occurred in 7 patients (13.7%) in the mirroring group and 14 patients (31.1%) in the HHC group (P=0.040). A multiple logistic regression demonstrated mirroring reconstruction could reduce the incidence of postoperative limping (P=0.020). Both mirroring and HHC reconstruction could improve the functional performance of THA, whereas mirroring reconstruction could offer superior biomechanical results and gait improvement as compared with HHC reconstruction, meeting the higher requirements of functional recovery

Tenotomy of the iliopsoas tendon has been described as an effective procedure to treat refractive groin pain induced by iliopsoas tendinitis. However, the procedure forces the rectus femoris to act as the primary hip flexor and little is known about the long-term effects of this procedure on the peri-articular muscle envelope (PAME). Studies suggest that iliopsoas tenotomy results in atrophy of the iliopsoas and decreased hip flexion strength with poorer outcomes, increasing the susceptibility for secondary tendinopathy. The aim of this study is to describe changes in the PAME following psoas release. All patients who presented for clinical examination at our hospital between 2016 and 2021 were retrospectively reviewed. Patients who presented after psoas tenotomy with groin pain and who were unable to actively lift the leg against gravity, were included. Pelvic MRI was taken. Qualitative muscle evaluation was done with the Quartile classification system. Quantitative muscle evaluation was done by establishing the cross-sectional area (CSA). Two independent observers evaluated the ipsi- and contralateral PAME twice. The muscles were evaluated on the level: iliacus, psoas, gluteus minimus-medius-maximus, rectus femoris, tensor fasciae lata, piriformis, obturator externus and internus. For the qualitative evaluation, the intra- and inter-observer reliability was calculated by using kappastatistics. A Bland-Altman analysis was used to evaluate the intra- and inter-observer reliability for the quantitative evaluation. The Wilcoxon test was used to evaluate the changes between the ipsi- and contra-lateral side. 17 patients were included in the study. Following psoas tenotomy, CSA reduced in the ipsilateral gluteus maximus, if compared with the contralateral side. Fatty degeneration occurred in the tensor fascia latae. Both CSA reduction and fatty degeneration was seen for psoas, iliacus, gluteus minimus, piriformis, obturator externus and internus. No CSA reduction and fatty degeneration was seen for gluteus medius and rectus femoris. Conclusions/Discussion. Following psoas tenotomy, the PAME of the hip shows atrophy and fatty degeneration. These changes can lead to detrimental functional problems and may be associated with debilitating rectus femoris tendinopathy. In patients with psoas tendinopathy, some caution is advised when considering an iliopsoas tenotomy

It is anecdotally thought that a good outcome from the first of staged total hip arthroplasties (THAs) is predictive of benefit on the contralateral side. The objective was to determine whether outcome from the first THA could be used to predict outcome from the second, contralateral THA. A retrospective cohort study of consecutive patients undergoing staged THAs at a UK arthroplasty centre over 25-years (1995–2020). A control THA group was identified and matched for age, gender, BMI, implant and diagnosis. One-year patient-reported outcome data was available for 91% 1543/1700. 1700 patients who underwent staged THA were compared to 1700 matched controls. Preoperative status was comparable for pain, function, and modified Harris hip score (mHHS, mean 41 SD 13 for both groups). At one year, there was a 2% dissatisfaction rate in all groups (first of staged THAs, second of staged THAs and controls). Groups were similar in terms of pain, function and mHHS (mean 88 SD 11 for all groups). For every 100 patients undergoing staged THAs, 87 had a bilateral good outcome (mHHS >70 both), 11 had unilateral poor outcome (mHHS >70 one, <70 other) and 2 had bilateral poor outcome (mHHS <70 both). If the first THA had a good outcome, the relative risk of a bad outcome was 20% less than for controls (RR 0.8 95% CI 0.6–1.1). If the first THA had a poor outcome, the risk of a second poor outcome was 4.5 times higher (RR 4.5 95% CI 3.2–6.4), increasing from 6% to 29% (absolute risk). Patients undergoing staged THAs with a good outcome from the first THA were less likely to have a bad outcome with the second. Risk of a poor outcome after a previous successful THA was 6% but rose to almost 30% with a previous poor outcome. This remained after correcting for patient variables including gender, age, BMI and diagnosis, indicating a potentially novel independent risk factor for poor outcome from staged THA

Aims. Hip arthroplasty aims to accurately recreate joint biomechanics. Considerable attention has been paid to vertical and horizontal offset, but femoral head centre in the anteroposterior (AP) plane has received little attention. This study investigates the accuracy of restoration of joint centre of rotation in the AP plane. Methods. Postoperative CT scans of 40 patients who underwent unilateral uncemented total hip arthroplasty were analyzed. Anteroposterior offset (APO) and femoral anteversion were measured on both the operated and non-operated sides. Sagittal tilt of the femoral stem was also measured. APO measured on axial slices was defined as the perpendicular distance between a line drawn from the anterior most point of the proximal femur (anterior reference line) to the centre of the femoral head. The anterior reference line was made parallel to the posterior condylar axis of the knee to correct for rotation. Results. Overall, 26/40 hips had a centre of rotation displaced posteriorly compared to the contralateral hip, increasing to 33/40 once corrected for sagittal tilt, with a mean posterior displacement of 7 mm. Linear regression analysis indicated that stem anteversion needed to be increased by 10.8° to recreate the head centre in the AP plane. Merely matching the native version would result in a 12 mm posterior displacement. Conclusion. This study demonstrates the significant incidence of posterior displacement of the head centre in uncemented hip arthroplasty. Effects of such displacement include a reduction in impingement free range of motion, potential alterations in muscle force vectors and lever arms, and impaired proprioception due to muscle fibre reorientation. Cite this article: Bone Joint Res 2022;11(3):180–188

Aims. 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. Methods. This study investigated patients with preoperative posterior hypermobility, defined as a change in sacral slope (SS) from standing to sitting (ΔSS. stand-sit. ) ≥ 30°. Radiological spinopelvic parameters, including SS, pelvic incidence (PI), lumbar lordosis (LL), PI-LL mismatch, anterior pelvic plane tilt (APPt), and spinopelvic tilt (SPT), were measured on preoperative imaging, and at six weeks and a minimum of one year postoperatively. The severity of bilateral hip osteoarthritis (OA) was graded using Kellgren-Lawrence criteria. Results. A total of 136 patients were identified as having preoperative spinopelvic hypermobility. At one year after THA, 95% (129/136) of patients were no longer categorized as hypermobile on standing and sitting radiographs (ΔSS. stand-sit. < 30°). Mean ΔSS. stand-sit. decreased from 36.4° (SD 5.1°) at baseline to 21.4° (SD 6.6°) at one year (p < 0.001). Mean SS. seated. increased from baseline (11.4° (SD 8.8°)) to one year after THA by 11.5° (SD 7.4°) (p < 0.001), which correlates to an 8.5° (SD 5.5°) mean decrease in seated functional cup anteversion. Contralateral hip OA was the only radiological predictor of hypermobility persisting at one year after surgery. The overall reoperation rate was 1.5%. Conclusion. Spinopelvic hypermobility was found to resolve in the majority (95%) of patients one year after THA. The increase in SS. seated. was clinically significant, suggesting that current target recommendations for the hypermobile patient (decreased anteversion and inclination) should be revisited. Cite this article: Bone Joint J 2021;103-B(12):1766–1773

Femoral stem design affects periprosthetic bone mineral density (BMD), which may impact long term survival of cementless implants in total hip arthroplasty (THA). The aim of this study was to examine proximal femoral BMD in three morphologically different uncemented femoral stems designs to investigate whether one particular design resulted in improved preservation of BMD. 119 patients were randomized to receive either a proximally coated dual taper wedge stem, a proximally coated anatomic stem or a fully coated collarless triple tapered stem. Dual energy x-ray absorptiometry scans (Lunar iDXA, GE Healthcare, Madison, WI) assessed BMD across the seven Gruen zones pre-operatively, and post-operatively at 6-weeks, 1-year, and 2-years comparing the unoperated contralateral femur as a control. BMD increased in zones one (2.5%), two (17.1%), three (13.0%), five (10%) and six (17.9%) for all stems. Greater preservation of BMD was measured on the lateral cortex (zone 2) for both the dual taper wedge and anatomic stems (p = 0.019). The dual taper wedge stem also demonstrated preservation of BMD in the medial calcar (zone 7) whilst the anatomic and triple taper stem declined in this region, however this was not statistically significant (p = 0.059). BMD decreased on average by 2.1% in the mid-diaphysis region, distal to the stem tip (zone 4) for all implants. All stems performed equivalently at final follow-up in all patient reported outcome measures. Implant design was shown to impact BMD changes. All stems preserved bone at the metaphyseal level in early follow-up, which theoretically indicates favorable implant fixation. There was no significant stress shielding observed, however longer follow-up is required to elucidate the impact of this finding on implant survivorship

The direct anterior approach (DAA) is a popular minimally invasive approach for total hip arthroplasty (THA). It usually involves ligation of the lateral femoral circumflex artery's ascending branch (a-LFCA), which contributes to the perfusion of the tensor fasciae latae (TFL) muscle. Periarticular muscle status and clinical outcome were assessed after DAA-THA after a-LFCA preservation versus ligation. We evaluated surgical records of 161 patients undergoing DAA-THA with tentative preservation of the a-LFCA by the senior author between May and November 2021. Among 92 eligible patients, 33 (35 hips) featured successful preservation, of which 20 (22 hips, 13 female) participated in the study. From 59 patients with ligated a-LFCA, 26 (27 hips, 15 female) were enrolled, constituting the control group. MRI and clinical examinations were performed at 17–26 months to analyze volume and fatty infiltration of the TFL, gluteus medius and gluteus minimus muscles relative to the contralateral non-THA hip (15 preserved, 18 ligated). Clinical and radiographic data was retrospectively extracted from patient files. Patient-reported outcomes (PROMs) were added from the THA registry. There was a relative difference in TFL muscle volume of -6.27 cm. 3. (−9.89%, p=0.018) after a-LFCA preservation versus -8.6 cm. 3. (=11.62%, p=0.002) after ligation, without group differences (p>0.340). a-LFCA preservation showed lower relative TFL fatty infiltration (p=0.10). Gluteal muscle status was similar between sides and groups. Coxa valga morphology was more frequent in a-LFCA preservation (83%) than ligation (17%). Clinical outcomes showed high patient satisfaction in both groups, without difference in PROMs, but less anterolateral soft-tissue swelling after a-LFCA preservation (p<0.001). Despite excellent clinical results in both groups, preservation of the a-LFCA was associated with less TFL fatty infiltration and soft tissue swelling. Provided there is no compromise of intraoperative access we recommend a-LFCA preservation for DAA-THA

The purpose of this study was to assess the variability in implant position between sides in patients who underwent staged, bilateral THA and whether variation from one side to the other affected patient-reported outcomes. A retrospective review was conducted on 207 patients who underwent staged, bilateral THA by the same surgeon from 2017–2022. Leg length, acetabular height, cup version, and coronal and sagittal stem angles were assessed radiographically and compared to the contralateral THA. Surgical approach and technology utilization were further assessed for their impact on variability. Linear regression was used to model the relationship between side-to-side variability and patient-reported outcome measures (PROMS). Between sides, mean radiographic leg length varied by 4.6mm (0.0–21.2), acetabular height varied by 3.3mm (0.0–13.7), anteversion varied by 8.2° (0.0 to 28.7), coronal stem alignment varied by 1.1° (0.0 to 6.9), and sagittal angulation varied by 2.3° (0.0 to 10.5). The anterior approach resulted in more variability in stem angle position in both the coronal (1.3° vs. 1.0°, p=0.036) and sagittal planes (2.8° vs. 2.0° p=0.012) compared to the posterior approach. The posterior approach generally led to more anteversion than the anterior approach. Use of robotics or navigation for acetabular positioning did not increase side-to-side variability in cup-related position or leg length. Despite considerable side-to-side variability, Hip dysfunction and osteoarthritis outcome scores (HOOS JR) were not affected by higher levels of position inconsistency. Staged, bilateral THA results in considerable variability in component position between sides. The anterior approach leads to more side-to-side variability in sagittal stem angle and cup anteversion than the posterior approach. Navigation and robotics do not improve the consistency of component position in bilateral THA. Variation in implant position was not associated with differences in PROMs, suggesting that despite variability, patients can tolerate these differences between sides

Total Hip Arthroplasty (THA) surgery is a physical and cognitive challenge for surgeons. Data on stress levels, cognitive and physical load of orthopaedic surgeons, as well as ergonomic impact, are limited. With and without the use of an automated impaction device, operational efficiency and the surgeon's ergonomic, mental, and physical load was investigated. In a total of thirty THA procedures, a standard manual technique was compared with an automated impaction device. Three computerized cognitive tasks (Simon, pattern comparison, and pursuit rotor) and five physical tests (isometric wall-sit, plank-to-fatigue, handgrip, supra-postural task, and shoulder endurance) were used to assess psychophysiological load of the surgeon. Surgeon's cortisol concentration was evaluated from saliva samples. Postural risk was assessed by Rapid Upper Limb Assessment (RULA) and Rapid Entire Body Assessment (REBA). Efficiency was assessed by timing surgical steps and instrumentation flow. Cognitive performances after automated impaction showed faster response times and lower error rates with a greater time-on-target (+1.5 s) and a lower mouse deviation from target (−1.7 pixels). Manual impaction showed higher physical exhaustion in the isometric wall-sit test (10.6% vs. 22.9%), plank-to-fatigue (2.2% vs. 43.8%), the number of taps in the supra-postural task (−0.7% vs. −7.7%), handgrip force production in the dominant (−6.7% vs. −12.7%) and contralateral hand (+4.7% vs. +7.7%), and in shoulder endurance (−15s vs. −56s). An increase of 38.2% in salivary cortisol concentration between the midday (1.31 nmol/l) and afternoon session (1.81 nmol/l) was observed with manual impaction. After using automated impaction, salivary cortisol concentration decreased (−51.2%). Manual broaching time was on average 6′20’’ versus 7’3’’ with automated impaction. RULA of manual impaction scored 6 for cup impaction and 5 for femoral broaching, versus 3 and 3 for automated impaction, respectively. REBA of manual impaction scored 9 for cup impaction and 5 for femoral broaching, versus 4 and 3 for automated impaction, respectively. Automated impaction lowers surgeons’ cognitive and physical fatigue and leads to reduced stress and improved ergonomics without loss of surgical efficiency

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

Aims. Surgical treatment of young femoral neck fractures often requires an open approach to achieve an anatomical reduction. The application of a calcar plate has recently been described to aid in femoral neck fracture reduction and to augment fixation. However, application of a plate may potentially compromise the regional vascularity of the femoral head and neck. The purpose of this study was to investigate the effect of calcar femoral neck plating on the vascularity of the femoral head and neck. Methods. A Hueter approach and capsulotomy were performed bilaterally in six cadaveric hips. In the experimental group, a one-third tubular plate was secured to the inferomedial femoral neck at 6:00 on the clockface. The contralateral hip served as a control with surgical approach and capsulotomy without fixation. Pre- and post-contrast MRI was then performed to quantify signal intensity in the femoral head and neck. Qualitative assessment of the terminal arterial branches to the femoral head, specifically the inferior retinacular artery (IRA), was also performed. Results. Quantitative MRI revealed a mean reduction of 1.8% (SD 3.1%) of arterial contribution in the femoral head and a mean reduction of 7.1% (SD 10.6%) in the femoral neck in the plating group compared to non-plated controls. Based on femoral head quadrant analysis, the largest mean decrease in arterial contribution was in the inferomedial quadrant (4.0%, SD 6.6%). No significant differences were found between control and experimental hips for any femoral neck or femoral head regions. The inferior retinaculum of Weitbrecht (containing the IRA) was directly visualized in six of 12 specimens. Qualitative MRI assessment confirmed IRA integrity in all specimens. Conclusion. Calcar femoral neck plating at the 6:00 position on the clockface resulted in minimal decrease in femoral head and neck vascularity, and therefore it may be considered as an adjunct to laterally-based fixation for reduction and fixation of femoral neck fractures, especially in younger patients. Cite this article: Bone Jt Open 2021;2(8):611–617

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