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.

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.

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.

Average total weight of surgical waste and CO2 carbon footprint of orthopedic surgery in France, estimated on the basis of a representative panel.

BACKGROUND: Reduction of waste and carbon footprint can be optimized. Awareness of carbon sources and quantification of the waste are two key parameters. To our knowledge, there is no study in France on waste production by the surgical team during the operation in orthopedic surgery, in a global scope. Therefore, we performed an observational investigation aiming to: (1) quantify and characterize the weight of the wastes generated after a panel of orthopedic procedures, (2) calculate the CO2 footprint generated by these wastes and extrapolate the figure at the national scale. HYPOTHESIS: Waste production is highly variable according to the types of procedures and infectious clinical waste is still a predominant source of waste and CO2 emission. MATERIALS AND METHODS: It is a comparative and prospective study in which a total of 14 procedures were selected as a representative panel: arthroplasties (hip, knee), spine fusions, arthroscopic procedures (shoulder, knee), nerve release, forefoot osteotomies, trauma procedures. The main outcome was the average total weight of waste for each of the fourteen categories (280 measurements: 140 times 2, at the end of each procedure), expressed in kilograms (kg), and the proportions of infectious clinical waste (ICW) and household wastes (HW), expressed in percentages. Ten measures were prospectively recorded for each type of procedure in a single teaching hospital from January to September 2022. The theoretical carbon footprint generated by the treatment of the wastes was estimated in kilograms of CO2 equivalent (KgEqCO2). The national extrapolation of the carbon footprint was performed by collecting the total number of procedures in France in 2021 using the VisuChir tool. RESULTS: A total of 937kg of waste were produced for the 140 procedures, amongst which 514kg of ICW (54.8%) and 423kg of HW (45.2%). The overall median waste weight was 5.9kg (Q1: 4.4, Q3: 8.1), ranging from 1.8kg to 18.3kg. The overall median waste weight for HW was 2.8kg (Q1: 2.5, Q3: 3.4), ranging from 1.8kg to 17.8kg. The overall median waste weight for ICW was 3.8kg (Q1: 2.7, Q3: 4.8), ranging from 0.8kg to 7.2kg. The knee surgeries were responsible for the heaviest waste weight; the least waste-productive procedures were the foot and the carpal tunnel release. The median proportions of ICW varied from 39% for the total knee replacements to 72% for the femoral nails. There was a significant inverse correlation between the total waste weight and the proportion of ICW: r=-0.47, p<10-4. The total median estimated carbon footprint was 4.3KgCO2Eq (Q1: 3.1, Q3: 5.8), ranging from 1.59KgCO2Eq (Q1: 1.5, Q3: 1.8) and 7.07KgCO2Eq (Q1: 6.7, Q3: 8.17). The total median estimated carbon footprint was 3.5KgCO2Eq for ICW (Q1: 2.5, Q3: 4.5) and 0.76KgCO2Eq (Q1: 0.54, Q3: 1.3) for HW. The national median estimated carbon footprint was 10.1 million KgEqCO2 in 2021 for orthopedic surgery. CONCLUSION: Our study revealed that in most cases more than half of the wastes were ICW. The total estimated national carbon footprint for orthopedic procedures was 10 million kilograms. The reduction of the ICW constitutes a cornerstone, as they are responsible for more carbon emissions. LEVEL OF EVIDENCE: III; prospective comparative observational in vivo study.

How to Best Identify Acetabular Retroversion on Radiographs: Thresholds to Guide Clinical Practice.

BACKGROUND: Acetabular retroversion is associated with impingement and instability. An adequate interpretation of acetabular version and coverage on radiographs is essential to determine the optimal treatment strategy (periacetabular osteotomy vs hip arthroscopic surgery). The crossover sign (COS) has been associated with the presence of acetabular retroversion, and the anterior wall index (AWI) and posterior wall index (PWI) assess anteroposterior acetabular coverage. However, the radiographic appearance of the acetabulum is sensitive to anterior inferior iliac spine (AIIS) morphology and pelvic tilt (PT), which differs between the supine and standing positions. PURPOSE: To (1) identify differences in the acetabular appearance between the supine and standing positions among patients presenting with hip pain; (2) determine factors (acetabular version, AIIS morphology, and spinopelvic characteristics) associated with the crossover ratio (COR), AWI, and PWI; and (3) define relevant clinical thresholds to guide management. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Patients who presented to a hip preservation surgical unit (n = 134) were included (mean age, 35 ± 8 years; 58% female; mean body mass index, 27 ± 6). All participants underwent supine and standing anteroposterior pelvic radiography to assess the COS, COR, AWI, and PWI as well as standing lateral radiography to determine standing PT. Computed tomography was used to measure supine PT, acetabular version, and AIIS morphology. Acetabular version was measured at 3 transverse levels, corresponding to the 1-, 2-, and 3-o'clock positions. The correlation between radiographic characteristics (COR, AWI, and PWI) and acetabular version, AIIS morphology, and PT was calculated using the Spearman correlation coefficient. Receiver operating characteristic curve analysis was performed to define thresholds for the COR, AWI, and PWI to identify retroversion (version thresholds: <10°, <5°, and <0°). RESULTS: The COS was present in 55% of hips when supine and 30% when standing, with a mean difference in the COR of 12%. The supine COR (rho = -0.661) and AWI/PWI ratio (rho = -0.618) strongly correlated with acetabular version. The COS was more prevalent among patients with type 2 AIIS morphology (71%) than among those with type 1 AIIS morphology (43%) (P = .003). COR thresholds of 23% and 28% were able to identify acetabular version <5° (sensitivity = 81%; specificity = 80%) and <0° (sensitivity = 88%; specificity = 85%), respectively. An AWI/PWI ratio >0.6 was able to reliably identify acetabular version <0° (sensitivity = 83%; specificity = 84%). In the presence of a COR >30% and an AWI/PWI ratio >0.6, the specificity to detect retroversion was significantly increased (>90%). CONCLUSIONS: The presence of the COS was very common among patients with hip pain. False-positive results (high COR/normal version) may occur because of AIIS morphology/low PT. Relevant thresholds of COR >30% and AWI/PWI ratio >0.6 can help with diagnostic accuracy. In cases in which either the COR or AWI/PWI ratio is high, axial cross-sectional imaging can further help to avoid false-positive results.