A quasi-experimental evaluation of the association between implementation of Quality-Based Procedures funding for hip fractures and improvements in processes and outcomes for hip fracture patients in Ontario: an interrupted time series analysis.

PURPOSE: In 2013, Ontario introduced a patient-based funding model for hip fracture care (Quality-Based Procedures [QBP]). The association of QBP implementation with changes in processes and outcomes has not been evaluated. METHODS: We conducted a quasi-experimental study using linked health data for adult hip fractures as an interrupted time series. The pre-QBP period was from 2008 to 2012 and the post-QBP period was from 2014 to 2018; 2013 was excluded as a wash-in period. We used segmented regression analyses to estimate the association of QBP implementation with changes in processes (surgery in less than two days from admission, use of echocardiography, use of nerve blocks, and provision of geriatric care) and clinical outcomes (90-day mortality, 90-day readmissions, length of stay, and days alive at home). We estimated the immediate (level) change, trend (slope) postimplementation, and total counterfactual differences. Sensitivity analyses included case-mix adjustment and stratification by hospital type and procedure. RESULTS: We identified 45,500 patients in the pre-QBP period and 41,256 patients in the post-QBP period. There was a significant total counterfactual increase in the use of nerve blocks (11.1%; 95% confidence interval [CI], 6.2 to 16.0) and a decrease in the use of echocardiography (-2.5%; 95% CI, -3.7 to -1.3) after QBP implementation. The implementation of QBP was not associated with a clinically or statistically meaningful change in 90-day mortality, 90-day readmission, length of stay, or number of days alive at home. CONCLUSION: Evaluation of the QBP program is crucial to inform ongoing and future changes to policy and funding for hip fracture care. The introduction of the QBP Hip Fracture program, supported by evidence-based recommendations, was associated with improved application of some evidence-based processes of care but no changes in clinical outcomes. There is a need for ongoing development and evaluation of funding models to identify optimal strategies to improve the value and outcomes of hip fracture care. STUDY REGISTRATION: Open Science Framework ( https://osf.io/2938h/ ); first posted 13 June 2022.

RéSUMé: OBJECTIF: En 2013, l'Ontario a mis en place un modèle de financement axé sur les patient·es pour les soins suivant une fracture de la hanche (procédures fondées sur la qualité [PFQ]). L'association entre la mise en œuvre des PFQ et les changements dans les processus et les devenirs n'a pas été évaluée. MéTHODE: Nous avons mené une étude quasi expérimentale en utilisant des données de santé couplées pour les fractures de la hanche chez l'adulte comme une série chronologique interrompue. La période précédant les PFQ s'étendait de 2008 à 2012, et la période subséquente à l'implantation des PFQ allait de 2014 à 2018. L'année 2013 a été exclue en tant que période de rodage. Nous avons utilisé des analyses de régression segmentées pour estimer l'association entre la mise en œuvre des PFQ avec des changements aux processus (chirurgie en moins que deux jours suivant l'admission, utilisation de l'échocardiographie, utilisation de blocs nerveux et prestation de soins gériatriques) et des issues cliniques (mortalité à 90 jours, réadmissions à 90 jours, durée de séjour et jours de vie à domicile). Nous avons estimé le changement immédiat (niveau), la tendance (pente) après la mise en œuvre et les différences contrefactuelles totales. Les analyses de sensibilité comprenaient l'ajustement et la stratification de la combinaison de cas par type d'hôpital et par procédure. RéSULTATS: Nous avons identifié 45 500 patient·es dans la période pré-PFQ et 41 256 patient·es dans la période post-PFQ. Il y a eu une augmentation contrefactuelle totale significative de l'utilisation de blocs nerveux (11,1 %; intervalle de confiance [IC] à 95 %, 6,2 à 16,0) et une diminution de l'utilisation de l'échocardiographie (−2,5 %; IC 95 %, −3,7 à −1,3) après la mise en œuvre des PFQ. La mise en œuvre des PFQ n'a pas été associée à un changement cliniquement ou statistiquement significatif de la mortalité à 90 jours, de la réadmission à 90 jours, de la durée de séjour ou du nombre de jours de vie à domicile. CONCLUSION: L'évaluation du programme de PFQ est cruciale pour guider les changements actuels et futurs aux politiques et au financement des soins suivant une fracture de la hanche. La mise en place du programme de PFQ pour les fractures de la hanche, appuyée par des recommandations fondées sur des données probantes, a été associée à une meilleure application de certains processus de soins fondés sur des données probantes, mais à aucun changement dans les devenirs cliniques. Il est nécessaire d'élaborer et d'évaluer continuellement des modèles de financement afin de déterminer les stratégies optimales pour améliorer la valeur et les devenirs des soins suivant une fracture de la hanche. ENREGISTREMENT DE L'éTUDE: Open Science Framework ( https://osf.io/2938h/ ); première publication le 13 juin 2022.

How Does Radiographic Acetabular Morphology Change Between the Supine and Standing Positions in Asymptomatic Volunteers?

BACKGROUND: The radiographic appearance of the acetabulum differs between the supine and standing positions in patients with hip conditions. The pelvis undergoes a change in tilt when transitioning between positions, resulting in variations in version and acetabular coverage. However, the extent of these variations in well-functioning volunteers without compensatory patterns caused by pain is unknown. QUESTIONS/PURPOSES: We performed this study to (1) quantify differences in radiographic acetabular measurements when transitioning between supine and standing among asymptomatic, well-functioning volunteers; (2) assess differences in pelvic tilt between positions; and (3) test whether individual anatomic parameters are associated with the change in tilt. METHODS: This was a prospective, single-center study performed at an academic referral center. One hundred volunteers (students, staff, and patients with upper limb injuries) with well-functioning hips (Oxford hip score ≥ 45) were invited to participate. A total of 45% (45) of them were female, their mean age was 37 ± 14 years, and their mean BMI was 25 ± 2 kg/m2. Supine and standing AP pelvic radiographs were analyzed to determine numerous acetabular parameters including the lateral center-edge angle (LCEA), acetabular index (AI), anterior wall index (AWI), posterior wall index (PWI), crossover sign (COS), crossover ratio (COR), posterior wall sign (PWS), ischial spine sign (ISS), and femoroepiphyseal acetabular roof index (FEAR), as well as pelvic parameters including the sacrofemoral-pubic angle (SFP). Spinopelvic parameters were measured from lateral standing spinopelvic radiographs. Radiographic measurements were performed by one hip preservation research fellow and a fellowship-trained staff surgeon. Differences in parameters were determined, and correlations between postural differences and morphological parameters were tested. Clinically important differences were defined as a difference greater than 3° for acetabular angle measurements and 0.03 for acetabular ratio measurements, based on previous studies. RESULTS: Lateral coverage angles did not show a clinically important difference between positions. AWI decreased when standing (0.47 ± 0.13 versus 0.41 ± 0.14; p < 0.001), whereas acetabular retroversion signs were more pronounced when supine (COS: 34% [34 of 100], PWS: 68% [68 of 100], and ISS: 34% [34 of 100] versus COS: 19% [19 of 100], PWS: 38% [38 of 100], and ISS: 14% [14 of 100]; all p values < 0.05). Pelvic tilt increased by a mean of 4° ± 4° when standing, but the range of change was from -15° to 7°. The change in AWI (ρ = 0.47; p < 0.001), PWI (ρ = -0.45; p < 0.001), and COR (ρ = 0.52; p < 0.001) between positions correlated with ΔSFP. Volunteers with spinal imbalance (pelvic incidence lumbar lordosis > 10°) demonstrated greater change in pelvic tilt (ΔSFP) (-7° ± 3° versus -4° ± 4°; p = 0.02) and a greater reduction in AWI (by 10%). These volunteers demonstrated reduced standing lumbar lordosis angles (45° ± 11° versus 61° ± 10°; p = 0.001). CONCLUSION: Acetabular version increases from supine to standing because of an increase in pelvic tilt. The change in pelvic tilt between positions exhibited substantial variability. Individuals with reduced lumbar lordosis for a given pelvic incidence value demonstrated greater pelvic mobility. No features on supine radiographs were associated with the change in tilt. CLINICAL RELEVANCE: Performing standing radiographs in addition to supine views can help identify aberrant physiologic patterns in patients with diagnostic dilemmas and might thus help with management. Normative data of pelvic tilt change can help clinicians identify patients who demonstrate excessive change in tilt that contributes to abnormal hip pathomechanics.

Which Acetabular Measurements Most Accurately Differentiate Between Patients and Controls? A Comparative Study.

BACKGROUND: Acetabular morphology is an important determinant of hip biomechanics. To identify features of acetabular morphology that may be associated with the development of hip symptoms while accounting for spinopelvic characteristics, one needs to determine acetabular characteristics in a group of individuals older than 45 years without symptoms or signs of osteoarthritis. Previous studies have used patients with unknown physical status to define morphological thresholds to guide management. QUESTIONS/PURPOSES: (1) To determine acetabular morphological characteristics in males and females between 45 and 60 years old with a high Oxford hip score (OHS) and no signs of osteoarthritis; (2) to compare these characteristics with those of symptomatic hip patients treated with hip arthroscopy or periacetabular osteotomy (PAO) for various kinds of hip pathology (dysplasia, retroversion, and cam femoroacetabular impingement); and (3) to assess which radiographic or CT parameters most accurately differentiate between patients who had symptomatic hips and those who did not, and thus, define thresholds that can guide management. METHODS: Between January 2018 and December 2018, 1358 patients underwent an abdominopelvic CT scan in our institution for nonorthopaedic conditions. Of those, we considered 5% (73) of patients as potentially eligible as controls based on the absence of major hip osteoarthritis, trauma, or deformity. Patients were excluded if their OHS was 43 or less (2% [ 28 ]), if they had a PROMIS less than 50 (1% [ 18 ]), or their Tönnis score was higher than 1 (0.4% [ 6 ]). Another eight patients were excluded because of insufficient datasets. After randomly selecting one side for each control, 40 hips were left for analysis (age 55 ± 5 years; 48% [19 of 40] were in females). In this comparative study, this asymptomatic group was compared with a group of patients treated with hip arthroscopy or PAO. Between January 2013 and December 2020, 221 hips underwent hip preservation surgery. Of those, eight were excluded because of previous pelvic surgery, and 102 because of insufficient CT scans. One side was randomly selected in patients who underwent bilateral procedure, leaving 48% (107 of 221) of hips for analysis (age 31 ± 8 years; 54% [58 of 107] were in females). Detailed radiographic and CT assessments (including segmentation) were performed to determine acetabular (depth, cartilage coverage, subtended angles, anteversion, and inclination) and spinopelvic (pelvic tilt and incidence) parameters. Receiver operating characteristics (ROC) analysis was used to assess diagnostic accuracy and determine which morphological parameters (and their threshold) differentiate most accurately between symptomatic patients and asymptomatic controls. RESULTS: Acetabular morphology in asymptomatic hips was characterized by a mean depth of 22 ± 2 mm, with an articular cartilage surface of 2619 ± 415 mm 2 , covering 70% ± 6% of the articular surface, a mean acetabular inclination of 48° ± 6°, and a minimal difference between anatomical (24° ± 7°) and functional (22° ± 6°) anteversion. Patients with symptomatic hips generally had less acetabular depth (20 ± 4 mm versus 22 ± 2 mm, mean difference 3 mm [95% CI 1 to 4]; p < 0.001). Hips with dysplasia (67% ± 5% versus 70% ± 6%, mean difference 6% [95% CI 0% to 12%]; p = 0.03) or retroversion (67% ± 5% versus 70% ± 6%, mean difference 6% [95% CI 1% to 12%]; p = 0.04) had a slightly lower relative cartilage area compared with asymptomatic hips. There was no difference in acetabular inclination (48° ± 6° versus 47° ± 7°, mean difference 0.5° [95% CI -2° to 3°]; p = 0.35), but asymptomatic hips had higher anatomic anteversion (24° ± 7° versus 19° ± 8°, mean difference 6° [95% CI 3° to 9°]; p < 0.001) and functional anteversion (22° ± 6° versus 13°± 9°, mean difference 9° [95% CI 6° to 12°]; p < 0.001). Subtended angles were higher in asymptomatic at 105° (124° ± 7° versus 114° ± 12°, mean difference 11° [95% CI 3° to 17°]; p < 0.001), 135° (122° ± 9° versus 111° ± 12°, mean difference 10° [95% CI 2° to 15°]; p < 0.001), and 165° (112° ± 9° versus 102° ± 11°, mean difference 10° [95% CI 2° to 14°]; p < 0.001) around the acetabular clockface. Symptomatic hips had a lower pelvic tilt (8° ± 8° versus 11° ± 5°, mean difference 3° [95% CI 1° to 5°]; p = 0.007). The posterior wall index had the highest discriminatory ability of all measured parameters, with a cutoff value of less than 0.9 (area under the curve [AUC] 0.84 [95% CI 0.76 to 0.91]) for a symptomatic acetabulum (sensitivity 72%, specificity 78%). Diagnostically useful parameters on CT scan to differentiate between symptomatic and asymptomatic hips were acetabular depth less than 22 mm (AUC 0.74 [95% CI 0.66 to 0.83]) and functional anteversion less than 19° (AUC 0.79 [95% CI 0.72 to 0.87]). Subtended angles with the highest accuracy to differentiate between symptomatic and asymptomatic hips were those at 105° (AUC 0.76 [95% CI 0.65 to 0.88]), 135° (AUC 0.78 [95% CI 0.70 to 0.86]), and 165° (AUC 0.77 [95% CI 0.69 to 0.85]) of the acetabular clockface. CONCLUSION: An anatomical and functional acetabular anteversion of 24° and 22°, with a pelvic tilt of 10°, increases the acetabular opening and allows for more impingement-free flexion while providing sufficient posterosuperior coverage for loading. Hips with lower anteversion or a larger difference between anatomic and functional anteversion were more likely to be symptomatic. The importance of sufficient posterior coverage was also illustrated by the posterior wall indices and subtended angles at 105°, 135°, and 165° of the acetabular clockface having a high discriminatory ability to differentiate between symptomatic and asymptomatic hips. Future research should confirm whether integrating these parameters when selecting patients for hip preservation procedures can improve postoperative outcomes.Level of Evidence Level III, prognostic study.

How Is Variability in Femoral and Acetabular Version Associated With Presentation Among Young Adults With Hip Pain?

BACKGROUND: Acetabular and femoral version contribute to hip pain in patients with femoroacetabular impingement (FAI) or dysplasia. However, definitions and measurement methods of femoral version have varied in different studies, resulting in different "normal" values being used by clinicians for what should be the same anatomic measurement. This could result in discrepant or even inappropriate treatment recommendations. QUESTIONS/PURPOSES: In patients undergoing hip preservation surgery, (1) what is the range of acetabular and femoral version at presentation, and how much do two commonly used measurement techniques (those of Murphy and Reikerås) differ? (2) How are differences in acetabular and femoral version associated with clinical factors and outcomes scores at the time of presentation? METHODS: This was a retrospective analysis of data gathered in a longitudinally maintained database of patients undergoing hip preservation at a tertiary care referral center. Between June 2020 and December 2021, 282 hips in 258 patients were treated for an isolated labral tear (9% [26 hips]), hip dysplasia (21% [59 hips]), FAI (52% [147 hips]), mixed FAI and dysplasia (17% [47 hips]), or pediatric deformity (slipped capital femoral head epiphysis or Perthes disease; 1% [3 hips]) with hip arthroscopy (71% [200 hips]), periacetabular osteotomy (26% [74 hips]), surgical hip dislocation (2.5% [7 hips]), or femoral derotation osteotomy (0.5% [1 hip]). We considered those with complete radiographic data (CT including the pelvis and distal femur) and patient-reported outcome scores as potentially eligible. Exclusion criteria were age younger than 18 or older than 55 years (5 hips, 3 patients), signs of hip osteoarthritis (Tönnis grade ≥ 2; 0), pediatric deformity (slipped capital femoral head epiphysis or Perthes disease; 3 hips, 3 patients), previous femoral or acetabular osteotomy (2 hips, 2 patients), avascular necrosis of the femoral head (0), history of neuromuscular disorder (Ehlers-Danlos syndrome; 3 hips, 3 patients) or rheumatoid disease (ankylosing spondylitis; 1 hip, 1 patient), and when CT did not include the knees (19 hips, 19 patients). Based on these criteria, 249 hips in 227 patients were included. Of patients with bilateral symptomatic hips, one side was randomly selected for inclusion, leaving 227 hips in 227 patients for further analysis. The patients' median age (range) was 34 years (19 to 55 years), the median BMI (range) was 27 kg/m2 (16 to 55 kg/m2), and 63% (144) were female; they were treated with hip arthroscopy (in 74% [168]) or periacetabular osteotomy (in 23% [52]). Patients underwent a CT scan to measure acetabular version and femoral version using the Murphy (low < 10°; normal: 10° to 25°; high > 25°) or Reikerås (low < 5°; normal: 5° to 20°; high > 20°) technique. The McKibbin index was calculated (low: < 20°; normal: 20° to 50°; high > 50°). Based on the central acetabular version and femoral version as measured by Murphy, hips were grouped according to their rotational profile into four groups: unstable rotational profile: high (high acetabular version with high femoral version) or moderate (high acetabular version with normal femoral version or normal acetabular version with high femoral version); normal rotational profile (normal acetabular version with femoral version); compensatory rotational profile (low acetabular version with high femoral version or high acetabular version with low femoral version); and impingement rotational profile (low acetabular version with low femoral version): high (low acetabular version with low femoral version) or moderate (low acetabular version with normal femoral version or normal acetabular version with low femoral version). Radiographic assessments were manually performed on digitized images by two orthopaedic residents, and 25% of randomly selected measurements were repeated by the senior author, a fellowship-trained hip preservation and arthroplasty surgeon. Interobserver and intraobserver reliabilities were calculated using the correlation coefficient with a two-way mixed model, showing excellent agreement for Murphy technique measurements (intraclass correlation coefficient 0.908 [95% confidence interval 0.80 to 0.97]) and Reikerås technique measurements (ICC 0.938 [95% CI 0.81 to 0.97]). Patient-reported measures were recorded using the International Hip Outcome Tool (iHOT-33) (0 to 100; worse to best). RESULTS: The mean acetabular version was 18° ± 6°, and mean femoral version was 24° ± 12° using the Murphy technique and 12° ± 11° with the Reikerås method. Eighty percent (181 of 227) of hips had normal acetabular version, 42% (96 of 227) to 63% (142 to 227) had normal femoral version per Murphy and Reikerås, respectively, and 67% (152 to 227) had a normal McKibbin index. Patients with an impingement profile (low acetabular version or femoral version) were older (39 ± 9 years) than patients with an unstable (high acetabular version or femoral version; 33 ± 9 years; p = 0.004), normal (33 ± 9 years; p = 0.02), or compensatory (high acetabular version with low femoral version or vice versa; 33 ± 7 years; p = 0.08) rotational profile. Using the Murphy technique, femoral version was 12° greater than with the Reikerås method (R2 0.85; p < 0.001). There were no differences in iHOT-33 score between different groups (impingement: 32 ± 17 versus normal 35 ± 21 versus compensated: 34 ± 20 versus unstable: 31 ± 17; p = 0.40). CONCLUSION: Variability in femoral version is twice as large as acetabular version. Patients with an impingement rotational profile were older than patients with a normal, compensatory, or unstable profile, indicating there are other variables not yet fully accounted for that lead to earlier pain and presentation in these groups. Important differences exist between measurement methods. This study shows that different measurement methods for femoral anteversion result in different numbers; if other authors compare their results to those of other studies, they should use equations such as the one suggested in this study. LEVEL OF EVIDENCE: Level III, prognostic study.

How to Screen for Lumbar Spine Stiffness in Patients Awaiting Total Hip Arthroplasty.

BACKGROUND: This study aimed to (1) define the prevalence of spinopelvic abnormalities among patients who have hip osteoarthritis (OA) and controls (asymptomatic volunteers) and (2) identify factors that reliably predict the presence of lumbar spine stiffness. METHODS: This is a prospective, cross-sectional, case-cohort study of patients who have end-stage primary hip OA, who underwent primary total hip arthroplasty (THA). Patients were compared with a cohort of asymptomatic volunteers, matched for age, sex, and body mass index (BMI), serving as a control group. Spinopelvic pathologies were defined as: lumbar spine flatback deformity (difference of 10 or more degrees for pelvic incidence minus lumbar lordosis angle), a standing sagittal pelvic tilt of 19° or more and lumbar spine stiffness (lumbar flexion of less than 20° between both postures). RESULTS: The prevalence of spinopelvic pathologies was similar between patients and controls (flatback deformity: 16% versus 10%, P = .209; standing pelvic tilt >19°: 17% versus 24%, P = .218; lumbar spine stiffness: 6% versus 5%, P = .827). Age over 65 years-old and standing lumbar lordosis angle less than 45° were associated with high sensitivity and specificity for identifying lumbar spine stiffness (age >65 years: 82% and 66%; standing lumbar lordosis angle <45°: 85% and 73%). CONCLUSION: The presence of end-stage hip osteoarthritis was not associated with increased prevalence of adverse spinopelvic characteristics compared to matched, asymptomatic volunteers. Age and LLstanding are the strongest predictors of lumbar spine flexion and can guide clinical practice on when to obtain additional radiographs for patients who have hip OA before arthroplasty to identify at-risk patients. LEVEL OF EVIDENCE: II (prospective, cohort study).

National Institute of Health and Care Excellence Guidelines for Displaced Intracapsular Hip Fractures: Examining Satisfaction With the Guidelines and Effects on Outcomes.

BACKGROUND: The objectives of the study were to: (1) evaluate satisfaction with the new 2023 National Institute of Health and Care Excellence (NICE) criteria for selecting total hip arthroplasty (THA) over hemiarthroplasty and surgical recommendations for treatment of displaced intracapsular hip fractures; (2) describe why THA is performed when NICE criteria are not met; and (3) determine whether satisfaction with these guidelines is associated with improved outcomes. METHODS: A retrospective chart review of patients who had a displaced intracapsular hip fracture treated with THA at a single tertiary academic center between 2010 and 2022 was performed. Preoperative patient characteristics were reviewed to determine if the indication for THA met NICE criteria. Operative details, perioperative complications, reoperation, and revision arthroplasty within 12 months of surgery were recorded. RESULTS: Data from 196 patients (63% women; age 67 ± 10 years) were used. There were 161 THAs (82.1%) that satisfied NICE criteria. The 2 most common reasons for performing a THA when NICE criteria were not met (n = 35) included preoperative radiographic osteoarthritis (Tönnis grade ≥ 2; 48.6%) and decreased patient age (< 65 years; 31.5%). Satisfaction with the NICE criteria was associated with fewer perioperative complications (0.6 versus 37.1%; P < .001), reoperations (0.6 versus 31.4%; P < .001), and revisions (0.6 versus 28.6%; P < .001). The most common reason for revision was periprosthetic fracture, possibly secondary to the use of uncemented femoral stems (171 of 196, 87.2%). CONCLUSIONS: Satisfaction with the new NICE criteria is associated with improved perioperative outcomes. Further studies are necessary to determine if preexisting hip osteoarthritis and younger age merit consideration in patient selection.

Lower Rates of Reoperation Following Partial or Complete Revision Arthroplasty Compared to Debridement, Antibiotics, and Implant Retention for Early Postoperative and Acute Hematogenous Periprosthetic Hip Infection.

BACKGROUND: This study aimed to: 1) compare treatment outcomes between debridement, antibiotics, and implant retention (DAIR) and partial or complete revision arthroplasty (RA) for early postoperative and acute hematogenous total hip arthroplasty periprosthetic joint infection (PJI) and 2) identify factors associated with treatment outcome. METHODS: The study consisted of a retrospective cohort of patients who underwent surgery for PJI between 2004 and 2021. There were 76 patients (74.5%) who underwent DAIR and 26 patients (25.5%) who underwent RA. Treatment success was defined as treatment eradication at a minimum of a 2-year follow up. Bivariate regression analysis was used to assess the effect of different factors on treatment outcomes. Kaplan-Meier survivorship was performed to compare survivorship between cohorts. RESULTS: At a mean follow-up of 8.2 years (range, 2.2 to 16.4), significantly more DAIR failed treatment (DAIR, 50 [65.8%]; 10 [38.5%]; P = .015). The 8-year Kaplan-Meier survivorship was 35.1% [95% confidence interval (CI), 24.3 to 45.9] for patients treated with DAIR and 61.5% [95% CI, 42.9 to 80.1] for those treated with RA (log rank = 0.039). Bivariate regression analysis showed performing a RA was associated with a higher likelihood of treatment success (odds ratio 4.499, 95% CI 1.600 to 12.647, P = .004), whereas a higher body mass index was associated with treatment failure (odds ratio 0.934, 95% CI 0.878 to 0.994, P = .032). CONCLUSIONS: To reduce the rate of recalcitrant infection following early postoperative or acute hematogenous total hip arthroplasty PJI, RA may be of benefit over DAIR. This is especially relevant in the early postoperative period, when components can be readily exchanged.

How Do Spinopelvic Characteristics Change Post-Total Hip Arthroplasty? A Longitudinal Assessment Raising Awareness of the Postoperative Period.

BACKGROUND: Spinopelvic characteristics, including sacral slope (SS), are commonly evaluated in different positions pre-total hip arthroplasty (THA). This study aimed to: 1) investigate the change in spinopelvic parameters at 7 days (early) and 1-year post-THA; and 2) identify patient characteristics associated with a change in SS of more than 7° post-THA. METHODS: We prospectively studied 250 patients who underwent unilateral THA [132 women, age 66 years (range, 32 to 88)] and underwent biplanar images preoperatively and at 7 days and 1-year post-THA. Parameters measured included pelvic incidence, standing lumbar lordosis, SS, and proximal femoral angle (PFA). A SS change ≥ 7° was considered the threshold as it would result in more than a 5° change in cup orientation. RESULTS: Early post-THA SSstanding remained within ± 6º from preoperative measurements in 75% of patients, reduced by ≥ 7° in 9%, and increased by ≥ 7° in 16%. Those that showed a reduction in SS had the lowest PFA and the highest SS pre-THA (P = .028, .107, and < 0.001, respectively). From 7 days until the 1-year mark, pelvic tilt increased, SS reduced (mean: -4º, range: -29 to 17º, P < .001), and patients stood with greater hip extension ΔPFAstanding (mean 7°, range: -34 to 37°, P < .001). At 1 year, SSseated had remained within ± 6º, relative to the pre-THA value, in 49% of patients. CONCLUSIONS: Standing spinopelvic characteristics, especially SSstanding, remain within ±6° in three-quarters of patients both early- and at 1-year post-THA. In the remaining cases, pelvic tilt changes significantly. In 9% of cases, SS reduces ≥ 7° early THA, probably due to the alleviation of fixed-flexion contractures. The SSseated changes by ≥ ± 7° in almost 50% of cases in this study, and its clinical value as a preoperative planning tool should be questioned. LEVEL OF EVIDENCE: Level II, diagnostic study.

Impact of Offset and Leg Length on Functional Outcomes Post-Total Hip Arthroplasty: How Accurate Should Coronal Reconstruction Be?

BACKGROUND: Accurate hip reconstruction is associated with improved biomechanical behavior following total hip arthroplasty (THA). However, whether this is associated with improved patient-reported outcomes (PROs) is unknown. HYPOTHESIS/PURPOSE: This study aimed to: 1) describe the ability to reconstruct coronal geometry during THA without advanced technology; 2) assess whether restoration of global offset (GO) and leg length (LL) is associated with improved PROs; and 3) investigate whether increased femoral offset (FO) to compensate for reduced acetabular offset (AO) influences PROs. METHOD: This was a prospective, multicenter, consecutive cohort study of 500 patients treated with primary THA without robotics or navigation. The Oxford Hip score (OHS) was obtained preoperatively and at 1-year follow-up. Supine anteroposterior pelvic radiographs were analyzed to determine AO, FO, GO, and LL relative to the native contralateral side. Contour plots for ΔOHS based on ΔLL and ΔGO were created, and ΔOHS was calculated within and outside various ranges (±2.5, ±5, or ±10 mm). RESULTS: In the operated hip, mean FO increased by 3 ± 6 mm (range, -16 to 27), while AO decreased by 2 ± 4 mm (range, -17 to 10). The contour graph for ±2.5 mm zones showed the best outcomes (ΔOHS >25) with GO and LL centered on 0 ± 2.5 mm (P < .01). However, only 10% achieved such reconstruction. When GO and LL differences were within ±10 mm, ΔOHS was superior when both AO and FO were within ±5 mm (mean: 24 ± 10; range, -5 to 40) compared with when FO was above 5 mm to compensate for a reduction in AO (mean: 22 ± 11; range, -10 to 46; P = .040). CONCLUSIONS: The PROs were associated with biomechanical reconstruction, and the best clinical improvement can be expected when GO and LL differences are both within 2.5 mm. Maintenance of AO is important, as compensation by increasing FO is associated with inferior OHS.

Periprosthetic fracture following anterior approach or dislocation after posterior approach: which one is the lesser evil?

INTRODUCTION: The most common approaches in total hip arthroplasty (THA) have different complication profiles; anterior-approach (AA-THA) has an increased risk of periprosthetic fractures (PPF); posterior-approach (PA-THA) is associated with higher dislocation risk. However, the relative severity of one versus the other is unknown. This study aims to compare outcome of patients who suffered PPF after AA-THA with those that sustained dislocation after PA-THA. METHODS: This is a retrospective, single-center, multi-surgeon, consecutive case-series of primary THA patients. In a cohort of 9867 patients who underwent THA, 79 fulfilled the approach-specific, post-operative complication criteria, of which 44 were PPF after AA-THA and 35 with dislocation after PA-THA (age 67.9 years (range: 38.0-88.1), 58.2% women). Outcome included complication- and revision- rates, and patient-reported outcomes including Oxford Hip Score (OHS). RESULTS: At 5.8 years follow-up (range: 2.0-18.5), reoperation was more common in the dislocation after PA-THA group (23/35 vs. 20/44; p = 0.072). Change of surgical approach occurred in 15/20 of patients with PPF after AA-THA, but none in those with dislocation after PA-THA. Following re-operation, complication rate was greater in the PPF group (9/20 vs. 4/23; p = 0.049). At latest follow-up, OHS were superior in the PPF after AA-THA group [42.6 (range: 25.0-48.0) vs. 36.6 (range: 21.0-47.0); p = 0.006]. CONCLUSION: Dislocation following PA-THA is more likely to require revision. However, PPF following AA-THA requires more often a different surgical approach and is at higher risk of complications. Despite the increased surgical burden post-operative PROMs are better in the peri-prosthetic fracture group, especially in cases not requiring reoperation. LEVEL OF EVIDENCE: III, case-control study.

Prevalence of anemia and association with outcome in joint arthroplasty - is there a difference between primary and revision cases?

PURPOSE: Anemia has been shown to be a modifiable pre-operative, patient factor associated with outcome following arthroplasty. The aims of this retrospective study were to (1) ascertain the prevalence of preoperative anemia in patients undergoing primary and revision hip and knee arthroplasty at a tertiary referral center and (2) to test the association with outcome and whether it differs between primary and revision cases. METHODS: All hip and knee primary and revision arthroplasties performed at a Canadian academic, tertiary-care, arthroplasty center between 2012 and 2017 were included in this study. The study group consisted of 5944 patients, of which 5251 were primary Total Hip and Knee Arthroplasties or Hip Resurfacings and 693 were revision arthroplasties (65% hip revisions/35% knee revisions). Anemia was classified as per WHO definition (hemoglobin < 130 g/L for men and < 120 g/L for women). All anemic patients were grouped into mild, moderate or severe anemia. Length-of-stay, perioperative transfusion-rate, 90-day readmission, overall complication rate and reoperation rates were recorded. The effect of preoperative anemia and the effect of severity of the anemia was evaluated through multivariable regression analysis controlling for relevant covariates. RESULTS: Preoperatively, 15% (786/5251) of the primary patients and 47% (322/693) of the revision arthroplasty patients were anemic preoperatively. Anemic revision patients were 3.1 times more likely (95% CI: 1.47-6.33) to obtain blood transfusions during the hospital stay, compared to a 4.9 times higher risk in primary patients. The odds ratio to sustain any postoperative complication if anemic was 1.5 times higher (95% CI: 0.73-3.16) in revision patients and 1.7 in primary cases. In addition, the 90-day readmission rate among both groups was 1.6 times higher in anemic patients. Furthermore, anemic revision patients had a 5.3 days longer length of stay (95% CI: 2.63-7.91), compared to only 1 additional day in anemic primary patients (95% CI: 0.69-1.34). CONCLUSION: In this study cohort, the prevalence of anemia in patients awaiting revision arthroplasty was 3 times higher (46.6%) than in primary arthroplasty patients (18.7%). Preoperative anemia was associated with similarly, inferior outcomes in both groups. To reduce postoperative complications and the "burden" associated with anemia, these findings strongly recommend optimizing the preoperative hemoglobin in all arthroplasty patients. However, revision patients are affected more frequently, and particular attention must therefore be taken to this growing group in the future. LEVEL OF EVIDENCE: Level III.

Change in cup orientation from supine to standing posture: a prospective cohort study of 419 total hip arthroplasties.

BACKGROUND AND PURPOSE: Arthroplasty surgeons traditionally assess cup orientation after total hip arthroplasty (THA) on supine radiographs. Contemporary hip-spine analyses provide information on standing, functional cup orientation. This study aims to (i) characterize cup orientations when supine and standing; (ii) determine orientation differences between postures; and (iii) identify factors associated with magnitude of orientation differences. METHODS: This is a 2-center, multi-surgeon, prospective, consecutive cohort study. 419 primary THAs were included (57% women; mean age: 64 years, standard deviation [SD] 11). All patients underwent supine and standing antero-posterior pelvic and lateral spinopelvic radiographs. Cup orientation and spinopelvic parameters were measured. Target cup orientation was defined as inclination/anteversion of 40°/20° ± 10°. A change in orientation (Δinclination/Δanteversion) between postures > 5° was defined as clinically significant. Variability was defined as 2 x SD. RESULTS: Inclination increased from 40° (supine) to 42° (standing) corresponding to a Δinclination of 2° (95% confidence interval [CI] 2-3). Anteversion increased from 25° (supine) to 30° (standing) corresponding to a Δanteversion of 5° (CI 5-6). When supine, 69% (CI 65-74) of THAs were within target, but only 44% (CI 39-49) were within target when standing, resulting in a further 26% (CI 21-30) being out of target when standing. From supine to standing, a clinically significant change in anteversion (> 5°) was seen in 47% (CI 42-52) of cases. Δanteversion was higher in women than in men (6°, CI 5-7 vs 5°, CI 4-5) corresponding to a difference of 1° (CI 1-2), which was dependent on tilt change, standing cup anteversion, age, and standing pelvic tilt. CONCLUSION: Cup inclination and version increase upon standing but significant variability exists due to patient factors.

The Safety and Efficacy of the Anterior Approach Total Hip Arthroplasty as per Body Mass Index.

BACKGROUND: Obesity is associated with component malpositioning and increased revision risk after total hip arthroplasty (THA). With anterior approaches (AAs) becoming increasingly popular, the goal of this study was to assess whether clinical outcome post-AA-THA is affected by body mass index (BMI). METHODS: This multicenter, multisurgeon, consecutive case series used a prospective database of 1,784 AA-THAs (1,597 patients) through bikini (n = 1,172) or standard (n = 612) incisions. Mean age was 63 years (range, 20-94 years) and there were 57.5% women, who had a mean follow-up of 2.7 years (range, 2.0-4.1 years). Patients were classified into the following BMI groups: normal (BMI < 25.0; n = 572); overweight (BMI: 25.0-29.9; n = 739); obese (BMI: 30.0-34.9; n = 330); and severely obese (BMI ≥ 35.0; n = 143). Outcomes evaluated included hip reconstruction (inclination/anteversion and leg-length, complications, and revision rates) and patient-reported outcomes including Oxford Hip Scores (OHS). RESULTS: Mean postoperative leg-length difference was 2.0 mm (range: -17.5 to 39.0) with a mean cup inclination of 34.8° (range, 14.0-58.0°) and anteversion of 20.3° (range, 8.0-38.6°). Radiographic measurements were similar between BMI groups (P = .1-.7). Complication and revision rates were 2.5% and 1.7%, respectively. The most common complications were fracture (0.7%), periprosthetic joint infection (PJI) (0.5%), and dislocation (0.5%). There was no difference in dislocation (P = .885) or fracture rates (P = .588) between BMI groups. There was a higher rate of wound complications (1.8%; P = .053) and PJIs (2.1%; P = .029) among obese and severely obese patients. Wound complications were less common among obese patients with the 'bikini' incision (odds ratio 2.7). Preoperative OHS was worse among the severely obese (P < .001), which showed similar improvements (Change in OHS; P = .144). CONCLUSION: AA-THA is a credible option for obese patients, with low dislocation or fracture risk and excellent ability to reconstruct the hip, leading to comparable functional improvements among BMI groups. Obese patients have a higher risk of PJIs. Bikini incision for AA-THA can help minimize the risk of wound complications.

Is Outcome of Total Hip Arthroplasty for Hip Fracture Inferior to That of Arthritis in a Contemporary Arthroplasty Practice?

BACKGROUND: Outcome of total hip arthroplasty (THA) for femoral neck fractures (FNF) has been associated with higher complication rates. However, THA for FNF is not always performed by arthroplasty surgeons. This study aimed to compare THA outcomes for FNF to osteoarthritis (OA). In doing so, we described contemporary THA failure modes for FNF performed by arthroplasty surgeons. METHODS: This was a retrospective, multisurgeon study from an academic center. Of FNFs treated between 2010 and 2020, 177 received THA by an arthroplasty surgeon [mean age 67 years (range, 42 to 97), sex: 64.4% women]. These were matched (1:2) for age and sex with 354 THAs performed for hip OA, by the same surgeons. No dual-mobilities were used. Outcomes included radiologic measurements (inclination/anteversion and leg length), mortality, complications, reoperation rates and patient-reported outcomes including Oxford Hip Score. RESULTS: Postoperative mean leg-length difference was 0 mm (range, -10 to -10 mm), with a mean cup inclination and anteversion of 41 and 26°, respectively. There was no difference in radiological measurements between FNF and OA patients (P = .3). At a 5-year follow-up, mortality rate was significantly higher in the FNF-THA group compared to the OA-THA group (15.3 versus 1.1%; P < .001). There was no difference in complications (7.3 versus 4.2%; P = .098) or reoperation rates (5.1 versus 2.9%; P = .142) between the groups. Dislocation rate was 1.7%. Oxford Hip Score at the final follow-up was similar [43.7 points (range, 10 to 48) versus 43.6 points (range, 10 to 48); P = .030]. CONCLUSION: THA for the treatment of FNF is a reliable option and is associated with satisfactory outcomes. Instability was not a common reason of failure, despite not using dual-mobility articulations in this at-risk population. This is likely due to THAs being performed by the arthroplasty staff. When patients live beyond 2 years, similar clinical and radiographic outcomes with low rates of revision can be expected compared to elective THA for OA. LEVEL OF EVIDENCE: III, case-control study.

Sacral Slope Change From Standing to Relaxed-Seated Grossly Overpredicts the Presence of a Stiff Spine.

BACKGROUND: Several authors propose that a change in sacral slope of ≤10° between the standing and relaxed-seated positions (ΔSSstanding→relaxed-seated) identifies a patient with a stiff lumbar spine and has suggested the use of dual-mobility bearings for such patients undergoing a total hip arthroplasty (THA). The aim of this study was to assess how accurately ΔSSstanding→relaxed-seated can identify patients with a stiff spine. METHODS: A prospective, multicentre, consecutive cohort series of 312 patients had standing, relaxed-seated, and flexed-seated lateral radiographs prior to THA. ΔSSstanding→relaxed-seated was determined by the change in sacral slope between the standing and relaxed-seated positions. Lumbar flexion (LF) was defined as the difference in lumbar lordotic angle between standing and flexed-seated. LF ≤20° was considered a stiff spine. The predictive value of ΔSSstanding→relaxed-seated for characterizing a stiff spine was assessed. RESULTS: A weak correlation between ΔSSstanding→relaxed-seated and LF was identified (r2 = 0.13). Eighty six patients (28%) had ΔSSstanding→relaxed-seated ≤10° and 19 patients (6%) had a stiff spine. Of the 86 patients with ΔSSstanding→relaxed-seated ≤10°, 13 had a stiff spine. The positive predictive value of ΔSSstanding→relaxed-seated ≤10° for identifying a stiff spine was 15%. CONCLUSION: In this cohort, ΔSSstanding→relaxed-seated ≤10° was not correlated with a stiff spine. Using this simplified approach could lead to a 7-fold overprediction of patients with a stiff lumbar spine and abnormal spinopelvic mobility, unnecessary use of dual-mobility bearings, and incorrect component alignment targets. Referring to patients with ΔSSstanding→relaxed-seated ≤10° as being stiff is misleading. The flexed-seated position should be used to effectively assess a patient's spine mobility prior to THA.

Delayed mobilization following admission for hip fracture is associated with increased morbidity and length of hospital stay.

BACKGROUND: Current national guidelines on caring for hip fractures recommend early mobilization. However, this recommendation does not account for time spent immobilized waiting for surgery. We sought to determine timing of mobilization following hip fracture, beginning at hospital admission, and evaluate its association with medical complications and length of hospital stay (LOS). METHODS: We performed a retrospective review of prospectively collected data for 470 consecutive patients who underwent surgery for a hip fracture between September 2019 and August 2020 at an academic, tertiary-referral hospital. Outcomes of interest included time from hospital admission to mobilization, complication rate and LOS. We used a binary regression analysis to determine the effect of different surgical and patient factors on the risk of a postoperative medical complication. RESULTS: The mean time from admission to mobilization was 2.8 ± 2.3 days (range 3 h-14 d). There were 125 (26.6%) patients who experienced at least 1 complication. The odds of developing a complication began to increase steadily once a patient waited more than 3 days from admission to mobilization (odds ratio 2.15, 95% confidence interval 1.42-3.25). Multivariate regression analysis showed that prefracture frailty (ß = 0.276, p = 0.05), and timing from hospital admission to mobilization (ß = 0.156, p < 0.001) and from surgery to mobilization (ß = 1.195, p < 0.001) were associated with complications. The mean LOS was 12.2 ± 10.7 days (range 1-90 d). Prolonged wait to mobilization was associated with longer LOS (p = 0.01). CONCLUSION: Comprehensive guidelines on timing of mobilization following hip fracture should account for cumulative time spent immobilized.

Selective THA-approach use amongst junior surgeons improves safety of introducing the anterior approach: a prospective, multi-surgeon, comparative, study.

BACKGROUND: Learning curves associated with independent practice and anterior approach total hip arthroplasty (AA-THA) has been associated with inferior outcome. This study compared outcome of junior, fellowship-trained, surgeons who perform THA through both anterior and posterior (PA) approach, with senior surgeons who perform either AA or PA, to determine whether: 1. Fellowship training and selective practice allows for safe introduction of AA into practice; and 2. Whether selective approach-use influences outcome. METHODS: This is a prospective, consecutive study comparing the first 800 THAs of two junior, dual-approach, surgeons (AA/PA: 455/345), with 400 THAs cases of two senior, single-approach, surgeons (AA/PA: 200/200), between 2018 and 2020. Most patients were female (54.4%), mean age was 65 years-old (range 19-96) and mean BMI was 29 kg/m2 (range 16-66). Outcome included radiologic measurements (inclination/anteversion and leg-length), complication- and revision rates, and patient-reported outcomes including Oxford Hip Score (OHS). RESULTS: At 3.1 years (range 2.0-6.8) follow-up, there were 43 complications (3.6%), including 27 re-operations (2.3%); with no difference between junior and senior surgeons for AA-THA (Junior: 8/455 vs. Senior: 3/200; p = 0.355) or PA-THA (Junior: 11/345 vs. Senior: 5/200; p = 0.400). Amongst juniors, there was no difference in complications (AA:8/455 vs. PA:11/345; p = 0.140) and in ΔOHS (AA:20.5 ± 7.7 vs. PA:20.5 ± 8.0; p = 0.581) between approaches. CONCLUSION: Contemporary training and selective approach-use minimizes the learning curve, allowing junior staff to have equivalent outcome to established, senior surgeons in both AA and PA. We would advocate for selective approach use amongst junior arthroplasty surgeons when introducing the AA into independent practice.

Utility of pre-operative haemoglobin concentration to guide peri-operative blood tests for hip and knee arthroplasty: A decision curve analysis.

OBJECTIVE: Assess the prognostic value of pre-operative haemoglobin concentration (Hb) for identifying patients who develop severe post-operative anaemia or require blood transfusion following primary total hip or knee, or unicompartmental knee arthroplasty (THA, TKA, UKA). BACKGROUND: Pre-operative group and save (G&S), and post-operative Hb measurement may be unnecessary for many patients undergoing hip and knee arthroplasty provided individuals at greatest risk of severe post-operative anaemia can be identified. METHODS AND MATERIALS: Patients undergoing THA, TKA, or UKA between 2011 and 2018 were included. Outcomes were post-operative Hb below 70 and 80 g/L, and peri-operative blood transfusion. Logistic regression assessed the association between pre-operative Hb and each outcome. Decision curve analysis compared strategies for selecting patients for G&S and post-operative Hb measurement. RESULTS: 10 015 THA, TKA and UKA procedures were performed in 8582 patients. The incidence of blood transfusion (4.5%) decreased during the study. Using procedure specific Hb thresholds to select patients for pre-operative G&S and post-operative Hb testing had a greater net benefit than selecting all patients, no patients, or patients with pre-operative anaemia. CONCLUSIONS: Pre-operative G&S and post-operative Hb measurement may not be indicated for UKA or TKA when adopting restrictive transfusion thresholds, provided clinicians accept a 0.1% risk of patients developing severe undiagnosed post-operative anaemia (Hb < 70 g/L). The decision to perform these blood tests for THA patients should be based on local institutional data and selection of acceptable risk thresholds.

Hip arthroscopy after periacetabular osteotomy for acetabular dysplasia - incidence and clinical outcome.

BACKGROUND: The periacetabular osteotomy (PAO) is the treatment of choice for acetabular dysplasia and has demonstrated improvement in patient reported outcomes measures (PROMs) as well as acceptable long-term survival. However, acetabular dysplasia is also associated with intra-articular lesions that can negatively impact clinical outcome. This study aimed to analyse the incidence, operative findings, and outcomes of hip arthroscopy after PAO. METHODS: This is a single center retrospective study by querying our hip preservation prospectively collected database from 2006 to 2020. All patients having undergone hip arthroscopy after a PAO, with a minimal follow-up of one year, were identified. 202 PAOs were done with a mean age of 28.3 years (12.7 - 53.6) including 39 males and 167 females. Failure was defined as conversion to hip replacement. Demographics, surgical findings, reoperations, and PROMs (pre and post operatively at the last follow-up point only for hips not converted to hip replacement). RESULTS: Fifteen hips in 15 patients (7.4%) out of 202 PAOs underwent a hip arthroscopy at a mean time of 3.9 years (0.3-10.3) after PAO. There were 2 males, 13 females and the mean age was 29.8 years (18.5-45). 12 hips had no radiological osteoarthritis (Tönnis 0) and 3 hips had early osteoarthritis (Tönnis 1). At time of arthroscopy, all hips had a labral tear, 9 had a chondral damage ≥ Beck 4. Eight hips had labral debridement, 7 had labral repair, 2 had resection of adhesions and 4 underwent a femoral osteochondroplasty. Four hips (27%) were converted to a hip replacement at a mean time of 1.8 years(0.5-3.2) after hip arthroscopy. Patients converted to hip replacement were significantly older (p = 0.01), had a lower post-PAO LCEA (p = 0.01) and a higher post-PAO Tönnis angle (p = 0.02). There were no significant improvements in PROMs. CONCLUSION: This study reports a hip arthroscopy reoperation rate after PAO of 7.4%. All three types of dysplasia (uncovered anteriorly, posteriorly, or globally) were present in this cohort. Twenty seven percent of patients were converted to hip replacement and PROMs were not significantly improved by hip arthroscopy. Therefore, this procedure should be approached with some caution.

Cup orientation following posterior approach THA - the effect of different visual aids and pelvic supports.

INTRODUCTION: This study aims to compare cup inclination achieved (1) Using two orientation guides, whilst using the same 3-point pelvic positioner and (2) Using two types of pelvic positioners, whilst measuring intra-operative cup inclination with an inclinometer. MATERIALS AND METHODS: This is a prospective, diagnostic cohort study of a consecutive series of 150 THAs performed through a posterior approach. Two types of 3-point pelvic positioners were used (Stulberg and modified Capello Hip Positioners) and the cup was positioned freehand using one of two orientation guides (mechanical guide or digital inclinometer). Intra-operative inclination was recorded, radiographic cup inclination and anteversion were measured from radiographs. The differences in inclination due to pelvic position (ΔPelvicPosition) and orientation definitions (ΔDefinition) were calculated. Target radiographic inclination and anteversion was 40/20° ± 10°. RESULTS: There was no difference in radiographic cup inclination/ (p = 0.63) using a mechanical guide or digital inclinometer. However, differences were seen in ΔPelvicPosition between the positioners ((Stulberg: 0° ± 5 vs. Capello: 3° ± 6); p = 0.011). Intra-operative inclination at implantation was different between positioners and this led to equivalent cases within inclination/anteversion targets (Stulberg:84%, Capello:80%; p = 0.48). CONCLUSIONS: With the pelvis securely positioned with 3-point supports, optimum cup orientation can be achieved with both alignment guides and inclinometer. Non-optimal cup inclinations were seen when intra-operative inclinations were above 40° and below 32°, or the ΔPelvicPosition was excessive (> 15°; n = 2). We would thus recommend that the intra-operative cup inclination should be centered strictly between 30° and 35° relative to the floor. Small differences exist between different type of pelvic positioners that surgeons need to be aware off and account for.