An anatomic consideration of the femoral nerve during direct anterior hip approach: A cadaveric study.

PURPOSE: This study aimed to investigate the distance and correlation between the anatomy of the anterior side of the hip joint and the femoral nerve. METHODS: Using ten fresh-frozen cadavers with twenty hip joints. We dissected and marked the femoral nerve in the inguinal area. Employing the direct anterior approach, we identified and marked study points, including the superior and inferior points of the anterior rim of the acetabulum, » point, half point, and ¾ point along an imagined line connecting the formers, the inferomedial and mid aspect of the femoral neck, and the soft spot. Coronal plane measurements gauged the distance between these points and the femoral nerve. The collected data were analyzed to assess the distance and correlation. RESULTS: In the coronal plane, the median distance between the inferior point of the anterior rim of the acetabulum and the femoral nerve was 0 millimeters (interquartile range [IQR] 0-0). Likewise, the median distance between the mid aspect of the medial side of the femoral neck and the femoral nerve was 0 millimeters (IQR 0-0). Additionally, the mean distance between the soft spot and the femoral nerve was 1.18 cm (SD 0.63). CONCLUSION: Surgeons approaching the hip joint via the direct anterior approach should be cautious at the inferior point of the anterior rim of the acetabulum and the mid aspect of the femoral neck. The soft spot at the anterior rim of the acetabulum remains safe from direct injury when surgeons use the correct technique during anterior retractor insertion.

Defining the Borderline Dysplastic Hip: High Variability in Acetabular Coverage and Femoral Morphology on Low-Dose Computed Tomography.

BACKGROUND: Borderline acetabular dysplasia is commonly radiographically defined as a lateral center-edge angle (LCEA) of 20° to 25°. While the variability of plain radiographic assessment of this population has been reported, an understanding of the variability of 3-dimensional (3D) hip morphology remains to be better defined. PURPOSE: To investigate the variability of 3D hip morphology present on low-dose computed tomography (CT) in the setting of symptomatic borderline acetabular dysplasia and to determine if plain radiographic parameters correlate with 3D coverage. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 2. METHODS: A total of 70 consecutive hips with borderline acetabular dysplasia undergoing hip preservation surgery were included in the current study. Plain radiographic evaluation included LCEA, acetabular inclination, anterior center-edge angle (ACEA), anterior wall index (AWI), posterior wall index (PWI), and alpha angles on anteroposterior, 45° Dunn, and frog-leg views. All patients underwent low-dose pelvic CT for preoperative planning, which allowed detailed characterization of 3D morphology relative to normative data. Acetabular morphology was assessed with radial acetabular coverage (RAC) calculated according to standardized clockface positions from 8:00 (posterior) to 4:00 (anterior). Coverages at 10:00, 12:00, and 2:00 were classified as normal, undercoverage, or overcoverage relative to 1 SD from the mean of normative RAC values. Femoral morphology was assessed with femoral version, alpha angle (measured at 1:00 increments), and maximum alpha angle. Correlation was assessed with the Pearson correlation coefficient (r). RESULTS: Lateral coverage (12:00 RAC) was deficient in 74.1% of hips with borderline dysplasia. Anterior coverage (2:00 RAC) was highly variable, with 17.1% undercoverage, 72.9% normal, and 10.0% overcoverage. Posterior coverage (10:00 RAC) was also highly variable, with 30.0% undercoverage, 62.9% normal, and 7.1% overcoverage. The 3 most common patterns of coverage were isolated lateral undercoverage (31.4%), normal coverage (18.6%), and combined lateral and posterior undercoverage (17.1%). The mean femoral version was 19.7°± 10.6° (range, -4° to 59°), with 47.1% of hips having increased femoral version (>20°). The mean maximum alpha angle was 57.2° (range, 43°-81°), with 48.6% of hips having an alpha angle ≥ 55°. The ACEA and AWI were poorly correlated with radial anterior coverage (r = 0.059 and 0.311, respectively), while the PWI was strongly correlated with radial posterior coverage (r = 0.774). CONCLUSION: Patients with borderline acetabular dysplasia demonstrate highly variable 3D deformities, including anterior, lateral, and posterior acetabular coverage; femoral version; and alpha angle. Plain radiographic assessments of anterior coverage are poorly correlated with anterior 3D coverage on low-dose CT.

The importance of acetabular morphometry in determining hip dysplasia / Importancia de la morfometría acetabular en la determinación de la displasia de cadera

SUMMARY: The aim of this study was to evaluate the relation between acetabulum morphological measurements and present the reference values of the acetabulum. The study had a retrospective design and was conducted with 234 healthy subjects (108 females; 126 males) aged 18-53 years over a period of 4 years from 2018 to 2022. Eleven measurements including the center- edge angle (CEA), acetabular angle (AA), acetabular depth (AD), acetabular width (AW), dept to width ratio (ADWR), Extrusion A (EA)-B (EB), Extrusion index (EI), the lateral subluxation (LS), peak to edge distance (PED), and roof obliquity (RO) were taken. The p<0.05 value was considered significant. A significant difference was found in CEA, AA, EB, LS, and RO values, while there was no significance in the AD, AW, ADWR, EI, and PED measurements in comparison with acetabular morphometry according to gender. Also, in the evaluation of acetabulum to age-related changes, there was a significant difference in values of the CEA, AA, AD, AW, ADWR, LS, and PED from decades 1 to 5. The knowledge of radiological acetabulum findings is paramount for the diagnosis of hip dysplasia and may be useful for prosthesis, orthopedic and forensic experts. Also, the most interesting finding was that ADWR increased based on age in a directly proportional trend. The most apparent change based on age was seen in CEA (between decades 3-4), LS (decades 1-5), PED (decades 2-4), AD, and AW (decades 2-5).

El objetivo de este estudio fue evaluar la relación entre las medidas morfológicas del acetábulo y presentar sus valores de referencia. El estudio tuvo un diseño retrospectivo y se realizó con 234 sujetos sanos (108 mujeres; 126 hombres) de 18 a 53 años de edad durante un período de 4 años, desde 2018 hasta 2022. Once mediciones que incluyeron el ángulo centro-margen (ACM), ángulo acetabular (AA), profundidad acetabular (PA), ancho acetabular (AC), relación de profundidad y ancho (RPAC), extrusión A (EA)-B (EB), índice de extrusión (IE), subluxación lateral (SL). Se midió la distancia al margen (DAM) y la oblicuidad del techo (OT). Se consideró significativo el valor de p<0,05. Se encontró una diferencia significativa en los valores de ACM, AA, EB, SL y OT, mientras que no hubo significación en las medidas de AA, AC, RPAC, IE y DAM en comparación con la morfometría acetabular según el sexo. Además, en la evaluación del acetábulo respecto a los cambios relacionados con la edad, hubo una diferencia significativa en los valores de ACM, AA, PA, AC, RPAC, SL y DAM de las décadas 1 a 5. El conocimiento de los hallazgos radiológicos del acetábulo es primordial para el diagnóstico de displasia de cadera y puede ser útil para expertos en prótesis, ortopedia y medicina forense. Además, el hallazgo más interesante fue que RPAC aumentó según la edad en una tendencia directamente proporcional. El cambio más aparente según la edad se observó en ACM (entre las décadas 3 y 4), LS (décadas 1 a 5), DAM (décadas 2 a 4), PA y AC (décadas 2 a 5).

Acetabular morphological variation in Asian patients with femoral neck fracture: A three-dimensional CT-based study.

AIMS: The acetabular morphology varies greatly among individuals, and hypoplasia is more common in Asia than in Europe. Dislocation after bipolar hip arthroplasty (BHA) for femoral neck fracture occurs at a constant rate, and is affected by the acetabular morphology. This study aimed to clarify individual differences in the acetabula of Asian patients with displaced femoral neck fractures. PATIENTS AND METHODS: Fifty patients with displaced femoral neck fractures were assessed (50 fractured hips, 50 non-fractured hips). On CT corrected by the anterior pelvic plane, the 100 hips were assessed regarding acetabular coverage (six parameters), acetabular depth (two parameters), and acetabular opening angle (four parameters). Additional parameters related to the fracture and sex were examined. The percentile of each parameter was shown for all hips. RESULTS: There was no patient with hip dysplasia defined as superior acetabular sector angle (SASA) less than 110° Compared with men, women had a significantly smaller anterior acetabular sector angle (AASA) (p = 0.016), and significantly larger acetabular inclination angle (p = 0.006) and acetabular index angle (p = 0.034). In the group with a normal SASA, seven hips (7.3%) had an anterior wall defect (AASA<50°) and five hips (5.2%) had a posterior wall defect (posterior acetabular sector angle<90°). CONCLUSION: Older adults with femoral neck fractures can have anterior wall and posterior wall defects, even if their SASA is normal. Hidden acetabular dysplasia may be related to post-BHA dislocation. So, our results suggest that is important to accurately evaluate the acetabulum of patients with femoral neck fracture before surgery.

Arthroscopic acetabular labrum suture.

It is essential to be aware of the anatomy and biomechanics of the acetabular labrum in order to understand why it should be conserved. Vascularization comes from the capsule and also from the bone. The joint side contains numerous nerve endings, which explains why labral lesions are painful. It is involved in joint stabilization by maintaining a negative pressure inside the joint able to resist distraction. It acts as a seal. There are two main suture techniques: trans- and peri-labral. Translabral suture is better suited to a wide and solid labrum free of degenerative lesions. Both techniques should be known, and may be associated. Results are comparable. It is essential to manage the underlying pathology responsible for the labral lesion. Joint degeneration is associated with poor prognosis. It needs to be recognized and discussed with the patient, to avoid unrealistic expectations.

Measuring the Acetabular Index: An Accurate and Reliable Alternative Method of Measurement.

OBJECTIVE. In children (4 months to 8 years old), radiographic measurements of the acetabular index are the preferred method to assess developmental hip dysplasia. However, the acetabular index has been criticized as having variable reliability owing to difficulty identifying the correct anatomic landmarks. An alternative method of measuring the acetabular index using the ischium is being proposed to avoid the variability of the triradiate cartilage line as a reference point. With the alternative method, the acetabular index is derived by measuring the angle between a line connecting the ischial tuberosi-ties and a line connecting the inferomedial and superolateral edges of the acetabulum. The purpose of this study was to evaluate the accuracy and reliability of this alternative method of measuring the acetabular index compared with the traditional method. MATERIALS AND METHODS. Children 4 months to 8 years old who presented for evaluation of developmental dysplasia of the hip were included. Two physicians, each using both the traditional and the alternative method, measured acetabular indexes on all radiographs. Accuracy was defined as mean absolute error less than 6°. Reliability was calculated by means of intraclass correlation coefficient (ICC). RESULTS. Pelvic radiographs of 40 children (324 hips) were included. The mean age was 23.7 months (range, 4-96 months) and mean acetabular index was 24.2° (range, 8-50°). The alternative method was associated with mean absolute error of 2.50°, which is significantly below the threshold of 6° (t < 0.001). Intrarater reliability for the traditional method was high (ICC, 0.81) and for the alternative method was very high (ICC, 0.92). Interrater reliability for the traditional method was high (ICC, 0.89) and for the alternative method was very high (ICC, 0.91). CONCLUSION. Measuring the acetabular index using the alternative method has very high accuracy and intrarater and interrater reliability.

Morphological consistency of bilateral hip joints in adults based on the X-ray and CT data.

PURPOSE: The application of the anatomical parameters of the contralateral hip joint to guide the preoperative template of the affected side relies on the bilateral hip symmetry. We investigated the bilateral hip symmetry and range of anatomical variations by measurement and comparison of bilateral hip anatomical parameters. METHODS: This study included 224 patients (448 hips) who were diagnosed with osteoarthritis (OA) and avascular necrosis (AVN) of the femur head, and underwent bilateral primary total hip arthroplasty (THA) in our hospital from January 2012 to August 2020. Imaging data included 224 patients X-ray and 30 CT data at the end of the cohort. Anatomical parameters, including the acetabular abduction angle and trochanteric height, were measured using the Noble method. Postoperative measurements included stem size, difference of leg length and offset. RESULTS: Except for the isthmus width, there were no significant differences in the anatomical morphology of the hip joint. Among the demographic factors, there was a correlation between body weight and NSA. Among various anatomical parameters, a correlation was present between medullary cavity widths of T + 20, T, and T - 20. The difference in the use of stem size is not due to the morphological difference of bilateral medullary cavity, but due to the different of 1- or 2-stage surgery. CONCLUSION: Bilateral symmetry was present among the patients with normal morphology of the hip medullary cavity, theoretically confirming the feasibility of structural reconstruction of the hip joint using the hip joint on the uninjured side. Additionally, the difference in the morphology of the hip medullary cavity is not present in a single plane but is synergistically affected by multiple adjacent planes.

Acetabular Bone Defect in Total Hip Arthroplasty for Crowe II or III Developmental Dysplasia of the Hip: A Finite Element Study.

BACKGROUND: The purpose of this study was to establish the finite element analysis (FEA) model of acetabular bone defect in Crowe type II or III developmental dysplasia of the hip (DDH), which could evaluate the stability of the acetabular cup with different types of bone defects, different diameters of femoral ceramic heads, and the use of screws and analyze the stress distribution of screws. METHODS: The FEA model was based on the CT scan of a female patient without any acetabular bone defect. The model of acetabular bone defect in total hip arthroplasty for Crowe II or III DDH was made by the increasing superolateral bone defect area of the acetabular cup. Point A was located in the most medial part of the acetabular bone defect. A 52 mm PINNACLE cup with POROCOAT Porous coating was implanted, and two screws (the lengths were 25 mm and 40 mm) were implanted to fix the acetabular cup. The stability of the acetabular cup and the von Mises stress of point A and screws were analyzed by a single-legged stance loading applied in 1948 N (normal working). The different diameters of the femoral ceramic head (28 mm, 32 mm, and 36 mm) were also analyzed. RESULTS: The von Mises stress of point A was gradually increased with the increasing uncoverage values. When the uncoverage values exceeded 24.5%, the von Mises stress of point A without screws increased significantly, leading to instability of the cup. Screws could effectively reduce the von Mises stress of point A with uncoverage values of more than 24.5%. However, the peak von Mises stress in the screws with the uncoverage values that exceeded 24.5% was considerably increased. The diameter of the femoral ceramic head had no significant effect on the von Mises stress and the stability of the acetabular cup. CONCLUSIONS: We recommend that uncoverage values of less than 24.5% with or without screw is safe for patients with Crowe II or III DDH.

Automatic Characterization of Pelvic and Sacral Measures from 200 Subjects.

BACKGROUND: An understanding of pelvic and acetabular morphology and orientation is required for accurate surgical reconstruction of the hip and spine, as well for component placement in a total hip arthroplasty. Our objectives were to develop an automated system for measuring pelvic and sacral orientations utilizing computed tomographic (CT) scans and to characterize these measures across 200 asymptomatic subjects. METHODS: An automated feature recognition algorithm was created to identify acetabular and pelvic orientation across 200 scans generated for non-musculoskeletal conditions. Three-dimensional models were generated from CT data to serve as inputs to the algorithm. Acetabular orientation was defined by comparing a plane fit to the acetabular rim with the anterior pelvic plane. Pelvic inclination, pelvic tilt, and sacral slope were defined as the angles between landmarks identified across the pelvis: pubic tubercles, acetabular center, left and right anterior superior iliac spines, and sacral plate. RESULTS: The mean sacral slope was 36.49°, the mean pelvic tilt was 15.60°, and the mean pelvic incidence was 52.05°. The mean sacropubic angle was 32.48° and the mean pelvic-Lewinnek angle was 8.93°. Significant differences between male and female subjects were observed in the sacral slope (mean difference, 4.72°; p < 0.05), pelvic tilt α (mean difference, 4.17°; p < 0.05), pelvic tilt γ (mean difference, 3.06°; p < 0.05), and the pelvic-Lewinnek angle (mean difference, 1.76°; p < 0.05). The comparison of acetabular orientation measures with those in a prior study of the same cohort yielded intraclass correlation coefficients (ICCs) all above 0.97. The validation of sacral orientation via manual measurement also yielded ICC values all at or above 0.97. CONCLUSIONS: Our algorithm showed a high degree of consistency in acetabular orientation measures with respect to a prior study of the same cohort. The measures of pelvic orientation were found to be accurate and reliable when compared with manual measurements of the same data set. All measurements of pelvic orientation were consistent with the means reported in the literature. CLINICAL RELEVANCE: An accurate and reproducible, automated technique for determining pelvic and acetabular orientation provides a way to characterize these measures as an aid in clinical diagnosis and preoperative planning.

The Hip Suction Seal, Part I: The Role of Acetabular Labral Height on Hip Distractive Stability.

BACKGROUND: The acetabular labrum has been found to provide a significant contribution to the distractive stability of the hip. However, the influence of labral height on hip suction seal biomechanics is not known. HYPOTHESIS: The smaller height of acetabular labrum is associated with decreased distractive stability. STUDY DESIGN: Descriptive laboratory study. METHODS: A total of 23 fresh-frozen cadaveric hemipelvises were used in this study. Hips with acetabular dysplasia or femoroacetabular impingement-related bony morphologic features, intra-articular pathology, or no measurable suction seal were excluded. Before testing, each specimen's hip capsule was removed, a pressure sensor was placed intra-articularly, and the hip was fixed in a heated saline bath. Labral size was measured by use of a digital caliper. Maximum distraction force, distance to suction seal rupture, and peak negative pressure were recorded while the hip underwent distraction at a rate of 0.5 mm/s. Correlations between factors were analyzed using the Spearman rho, and differences between groups were detected using Mann-Whitney U test. RESULTS: Of 23 hips, 12 satisfied inclusion criteria. The maximum distraction force and peak negative pressure were significantly correlated (R = -0.83; P = .001). Labral height was largely correlated with all suction seal parameters (maximum distraction force, R = 0.69, P = .013; distance to suction seal rupture, R = 0.55, P = .063; peak negative pressure, R = -0.62, P = .031). Labral height less than 6 mm was observed in 5 hips, with a mean height of 6.48 mm (SD, 2.65 mm; range, 2.62-11.90 mm; 95% CI, 4.80-8.17 mm). Compared with the 7 hips with larger labra (>6 mm), the hips with smaller labra had significantly shorter distance to suction seal rupture (median, 2.3 vs 7.2 mm; P = .010) and significantly decreased peak negative pressure (median, -59.3 vs -66.9 kPa; P = .048). CONCLUSION: Smaller height (<6 mm) of the acetabular labrum was significantly associated with decreased distance to suction seal rupture and decreased peak negative pressure. A new strategy to increase the size of the labrum, such as labral augmentation, could be justified for patients with smaller labra in order to optimize the hip suction seal. CLINICAL RELEVANCE: The height of the acetabular labrum is correlated with hip suction seal biomechanics. Further studies are required to identify the clinical effects of labral height on hip stability.

Lateral Center-Edge Angle Is Not Predictive of Acetabular Articular Cartilage Surface Area: Anatomic Variation of the Lunate Fossa.

BACKGROUND: Surgical treatment of symptomatic femoroacetabular impingement (FAI) and dysplasia requires careful characterization of acetabular morphology. The lateral center-edge angle (LCEA) is often used to assess lateral acetabular anatomy. Previous work has questioned the LCEA as a surrogate for acetabular contact/articular cartilage surface area because of the variable morphology of the lunate fossa. HYPOTHESIS: We hypothesized that weightbearing articular cartilage of the acetabulum would poorly correlate with LCEA secondary to significant variation in the size of the lunate fossa. STUDY DESIGN: Cohort study (Diagnosis); Level of evidence, 3. METHODS: Patients with 3D CT imaging undergoing either hip arthroscopy or periacetabular osteotomy for FAI or symptomatic hip instability were retrospectively identified. The LCEA and femoral head diameter were measured on an anteroposterior pelvis radiograph. Patients were grouped according to their lateral acetabular coverage as undercoverage (LCEA, <25°), normal coverage (LCEA, 25°-40°), or overcoverage (LCEA, >40°). Patients were randomly identified until each group contained 20 patients. The articular surface area was measured from preoperative 3D CT data. Linear regression analysis was performed to examine the relationship between articular surface area and LCEA. Continuous and categorical data were analyzed utilizing analysis of variance and chi-square analysis. Statistical significance was set at P < .05. RESULTS: No difference in age (P = .52), body mass index (BMI) (P = .75), or femoral head diameter (P = .66) was noted between groups. A significant difference in articular surface area was observed between patients with undercoverage and those with overcoverage (20.4 cm2 vs 24.5 cm2; P = .01). No significant difference was identified between the undercoverage and normal groups (20.4 cm2 vs 23.3 cm2; P = .09) or the normal and overcoverage groups (23.3 cm2 vs 24.5 cm2; P = .63). A moderate positive correlation was observed between LCEA and articular surface area across all patients (r = 0.38; P = .002) but not when patients with undercoverage were excluded (r = 0.02; P = .88). Significant variation in surface area was observed within each group such that no patient in any group was outside of 2 SDs of the means of the other groups. When patients were categorized into quartiles established by the articular surface area for the entire population, 40% of patients with overcoverage were observed in the first or second quartile (lower area). CONCLUSION: Lateral acetabular undercoverage based on the LCEA (<25°) correlates with decreased acetabular surface area. Normal or increased acetabular coverage (LCEA, >25°), however, is not predictive of increased, normal, or decreased acetabular surface area.

Which Acetabular Landmarks are the Most Useful for Measuring the Acetabular Index and Center-edge Angle in Developmental Dysplasia of the Hip? A Comparison of Two Methods.

BACKGROUND: The acetabular index and center-edge angle are widely used radiographic parameters. However, the exact landmarks for measuring these parameters are not clearly defined. Although their measurement is straightforward when the lateral osseous margin of the acetabular roof coincides with the lateral end of the acetabular sourcil, where these two landmarks disagree, recommendations have differed about which landmark should be used. Using a radiographic parameter with high reliability for predicting residual hip dysplasia helps avoid unnecessary treatment. QUESTIONS/PURPOSES: We aimed to (1) compare two landmarks (the lateral osseous margin of the acetabular roof and the lateral end of the acetabular sourcil) for measuring the acetabular index and center-edge angle with respect to intraobserver and interobserver reliability and the predictability of residual hip dysplasia in patients with developmental dysplasia of the hip (DDH) and (2) evaluate longitudinal change in the acetabular edge's shape after closed reduction with the patient under general anesthesia. METHODS: Between February 1985 and July 2006, we performed closed reduction with the patient under general anesthesia as well as cast immobilization in 116 patients with DDH. To be included in this study, a patient had to have dislocated-type DDH. We excluded patients with a hip dislocation associated with neuromuscular disease, arthrogryposis, or congenital anomalies of other organs or systems (n = 9); hips that underwent osteotomy within 1 year since closed reduction (n = 8); hips that underwent open reduction because of re-dislocation after closed reduction (n = 4); and hips with Type III or IV osteonecrosis according to Bucholz-Ogden's classification (n = 4). Ninety-one patients were eligible. We excluded 19% (17 of 91) of the patients, who were lost to follow-up before they were 8 years old, leaving 81% (74 of 91 patients) with full preoperative and most-recent data. Ninety-seven percent (72 patients) were girls and 3% (two patients) were boys. The mean ± standard deviation age was 14.0 months ± 6.4 months (range 3-40 months) at the time of closed reduction and 12.1 years ± 2.3 years (range 8.0-16.0 years) at the time of the latest follow-up examination, the duration of which averaged 11 years ± 2.2 years (range 6.5-15.4 years). To investigate whether longitudinal change in the acetabular edge's shape differed among hips with DDH, contralateral hips, and control hips, we identified control participants after searching our hospital's database for patients with a diagnosis of congenital idiopathic hemihypertrophy from October 2000 to November 2006 who had AP hip radiographs taken at 3 years old and then at older than 8 years. From 29 patients who met these criteria, we randomly excluded two male patients to match for sex because girls were predominant in the DDH group. We excluded another female patient from the control group because of a hip radiograph that revealed unacceptable rotation. Eventually, 26 patients were assigned to the control group. Control patients consisted of 24 girls (92%) and two boys (8%). The demographic characteristics of control patients was not different from those of 67 patients with unilateral DDH, except for laterality (left-side involvement: 64% [43 of 67] in the DDH group versus 38% [10 of 26] in the control group; odds ratio 1.7 [95% confidence interval, 1.0-2.8]; p = 0.035). The acetabular index and center-edge angle at 3 years old were measured using the lateral osseous margin of the acetabular roof (AIB and CEAB) and the lateral end of the acetabular sourcil (AIS and CEAS). The treatment outcome was classified as satisfactory (Severin Grade I or II) or unsatisfactory (Grade III or IV). The intraclass correlation coefficient (ICC) was used to compare the intraobserver and interobserver reliability of each method. We compared the predictability of residual hip dysplasia of each method at 3 years old as a proxy using the area under the receiver operating characteristic (AUC) curve. To evaluate longitudinal change in the acetabular edge's shape, we compared the proportion of hips showing coincidence of the two landmarks between 3 years old and the latest follow-up examination. To investigate whether the longitudinal change in the acetabular edge's shape differs among hips with DDH, contralateral hips, and control hips, we compared the proportion of coincidence among the three groups at both timepoints. RESULTS: Intraobserver and interobserver reliabilities were higher for the CEAB (ICC 0.96; 95% CI, 0.94-0.98 and ICC 0.88; 95% CI, 0.81-0.92, respectively) than for the CEAS (ICC 0.81; 95% CI, 0.70-0.88 and ICC 0.69; 95% CI, 0.55-0.79, respectively). The AIB (AUC 0.88; 95% CI, 0.80-0.96) and CEAB (AUC 0.841; 95% CI, 0.748-0.933) predicted residual hip dysplasia better than the AIS (AUC 0.776; 95% CI, 0.67-0.88) and CEAS (AUC 0.72; 95% CI, 0.59-0.84) (p = 0.03 and p = 0.01, respectively). The proportion of hips showing coincidence of the two landmarks increased from 3 years old to the latest follow-up examination in hips with DDH (37% [25 of 67] to 81% [54 of 67]; OR = 8.8 [95% CI, 3.1-33.9]; p < 0.001), contralateral hips (42% [28 of 67] to 85% [57 of 67]; OR = 16.5 [95% CI, 4.2-141.9]; p < 0.001), and control hips (38% [10 of 26] to 88% [23 of 26]; OR = 14 [95% CI, 2.1-592.0]; p = 0.001). The proportion of coincidence in hips with DDH was not different from that in the contralateral hips and control hips at both timepoints. CONCLUSIONS: Measuring the acetabular index and center-edge angle at 3 years old using the lateral osseous margin of the acetabular roof has higher reliability for predicting residual hip dysplasia than that using the lateral end of the acetabular sourcil in patients with DDH treated with closed reduction. Measuring the acetabular index and center-edge angle at an early age using the lateral end of the sourcil may lead to overdiagnosis of residual hip dysplasia and unnecessary treatment. LEVEL OF EVIDENCE: Level III, diagnostic study.

Is Labral Size Predictive of Failure With Repair in Hip Arthroscopy?

PURPOSE: To assess whether labral size is predictive of labral repair failure or shows an association with patient outcomes after hip arthroscopy. METHODS: We performed a retrospective chart review of patients who underwent arthroscopic hip labral repair. Labral size was measured in 4 quadrants with an arthroscopic probe. The average size across torn labral segments was assessed for failure as determined by the change in patient-reported outcomes, the rate at which subjects achieved the minimal clinically important difference and patient acceptable symptomatic state, and the need for additional surgery. Outcomes were evaluated for any continuous correlation as well as significant differences between the middle 50% of labral sizes and classes of labral sizes derived from upper and lower quartile and decile ranges. Included hips were those from patients aged between 18 and 55 years with 2-year postoperative follow-up and lateral center-edge angles between 25° and 40°. RESULTS: The study included 571 hips. Labral width did not show a significant difference between hips requiring revision and those not requiring revision (P = .4054). No significant correlation was found between labral width and the change in the International Hip Outcome Tool 12 score (R2 = 0.05780), modified Harris Hip Score (R2 = 0.19826), or Nonarthritic Hip Score (R2 = 0.23543) from preoperatively to 2 years postoperatively. Hips with labral sizes in the upper decile of our cohort showed significantly decreased improvement in the International Hip Outcome Tool 12 score (P = .0287) and Nonarthritic Hip Score (P = .0490) compared with the middle 50% of labral sizes. No statistically significant difference was found in the rate at which the groups achieved the minimal clinically important difference or patient acceptable symptomatic state. CONCLUSIONS: Hypertrophic labra in the largest 10th percentile showed lower postoperative outcome scores. However, no detectable clinical benefit was found in terms of patient-perceived clinical difference or acceptable symptomatic state. For most patients, labral size does not appear to significantly alter patient outcomes or the need for arthroplasty. LEVEL OF EVIDENCE: Level IV, retrospective case series.

Characterization of dimensional, morphological and morphometric features of retrieved 3D-printed acetabular cups for hip arthroplasty.

BACKGROUND: Three-dimensional (3D) printing of porous titanium implants is increasing in orthopaedics, promising enhanced bony fixation whilst maintaining design similarities with conventionally manufactured components. Our study is one of the first to non-destructively characterize 3D-printed implants, using conventionally manufactured components as a reference. METHODS: We analysed 16 acetabular cups retrieved from patients, divided into two groups: '3D-printed' (n = 6) and 'conventional' (n = 10). Coordinate-measuring machine (CMM), electron microscopy (SEM) and microcomputed tomography (micro-CT) were used to investigate the roundness of the internal cup surface, the morphology of the backside surface and the morphometric features of the porous structures of the cups, respectively. The amount of bony attachment was also evaluated. RESULTS: CMM analysis showed a median roundness of 19.45 and 14.52 µm for 3D-printed and conventional cups, respectively (p = 0.1114). SEM images revealed partially molten particles on the struts of 3D-printed implants; these are a by-product of the manufacturing technique, unlike the beads shown by conventional cups. As expected, porosity, pore size, strut thickness and thickness of the porous structure were significantly higher for 3D-printed components (p = 0.0002), with median values of 72.3%, 915 µm, 498 µm and 1.287 mm (p = 0.0002). The median values of bony attachment were 84.9% and 69.3% for 3D-printed and conventional cups, respectively (p = 0.2635). CONCLUSION: 3D-printed implants are designed to be significantly more porous than some conventional components, as shown in this study, whilst still exhibiting the same shape and size. We found differences in the surface morphologies of the groups, related to the different manufacturing methods; a key finding was the presence of partially molten particles on the 3D-printed cups.

The anatomical properties of the indirect head of the rectus femoris tendon: a cadaveric study with clinical significance for labral reconstruction surgery.

BACKGROUND: Acetabular labral tear is a common pathology. In some clinical situations, primary labral repair may not be possible and labral reconstruction is indicated. PURPOSE AND CLINICAL RELEVANCE: Describe the anatomy of the indirect head of the rectus femoris (IHRF) tendon with clinical application in arthroscopic labral reconstruction surgery. METHODS: Twenty-six cadaver hips were dissected. Thirteen measurements, each with clinical relevance to arthroscopic labral reconstruction using an IHRF tendon graft were taken on each hip. All measurements were taken in triplicate. Mean values, standard deviations and intra-observer reliability were calculated. RESULTS: The mean footprint of the direct head of the rectus femoris tendon was 10.6 mm × 19.6 mm. The width and thickness at the confluence of both heads were 10.9 mm and 6.9 mm, respectively. The mean total length of the footprint and "free portion" of the IHRF was 55.3 mm, the mean cranial to caudal footprint measured at the 12 o'clock, 1 o'clock, and 2 o'clock positions were 22.3 mm. The mean length of the Indirect Head footprint alone was 38.1 mm. The mean length of IHRF tendon suitable for grafting was 46.1 mm and the mean number of clock face sectors covered by this graft was 3.3 clock face sectors. Intra-observer reliability was ≥ 0.90 for all recorded measurements. The origin of the IHRF on the acetabulum fans out posteriorly, becoming thinner and wider as the origin travels posteriorly. The tendon footprint is firmly attached on the lateral wall of the ilium and becomes a free tendon overlying the acetabular bone as it travels anteriorly and distally towards its muscular attachment. CONCLUSION: The IHRF tendon is in an ideal location for harvesting and contains the appropriate thickness, length and triangular architecture to serve as a safe and local graft source for acetabular labral reconstruction surgery.

An Anatomical Study of the Anterosuperior Capsular Attachment Site on the Acetabulum.

BACKGROUND: Despite the fact that many surgeons perform partial capsular detachment from the anterosuperior aspect of the acetabulum to correct acetabular deformities during hip arthroscopy, few studies have focused on whether these detachments influence hip joint stability. The aim of this study was to investigate the capsular attachment on the anterosuperior aspect of the acetabulum. We hypothesized that the attachment on the inferior aspect of the anterior inferior iliac spine (AIIS) is wide and fibrocartilaginous and might have a substantial role in hip joint stability. METHODS: Fifteen hips from 9 cadavers of Japanese donors were analyzed. Eleven hips were analyzed macroscopically, and the other 4 were analyzed histologically. In all specimens, the 3-dimensional morphology of the acetabulum and AIIS was examined using micro-computed tomography (micro-CT). RESULTS: Macroscopic analysis showed that the widths of the capsular attachments varied according to the location, and the attachment width on the inferior edge of the AIIS was significantly larger than that on the anterosuperior aspect of the acetabulum. Moreover, the capsular attachment on the inferior edge of the AIIS corresponded with the impression, which was identified by micro-CT. Histological analysis revealed that the hip joint capsule on the inferior edge of the AIIS attached to the acetabulum adjacent to the proximal margin of the labrum. In addition, the hip joint capsule attached to the inferior edge of the AIIS via the fibrocartilage. CONCLUSIONS: The capsular attachment on the inferior edge of the AIIS was characterized by an osseous impression, large attachment width, and distributed fibrocartilage. CLINICAL RELEVANCE: It appeared that the capsular attachment on the inferior edge of the AIIS was highly adaptive to mechanical stress, on the basis of its osseous impression, attachment width, and histological features. Anatomical knowledge of the capsular attachment on the inferior edge of the AIIS provides a better understanding of the pathological condition of hip joint instability.

Retrospective study of 16 acetabular fractures with involvement of the quadrilateral plate treated with an anterior intrapelvic modified Rives-Stoppa approach. / Estudio retrospectivo sobre 16 fracturas de acetábulo con afectación de la lámina cuadrilátera tratadas con un abordaje anterior intrapélvico de Rives-Stoppa modificado.

GOAL: To report our experience with the use of Stoppa approach for fractures of the acetabulum with quadrilateral plate involvement. MATERIAL AND METHOD: Retrospective study; level iv. All patients were operated in a third level trauma center. The surgical team was experienced in the management of pelvic fractures. Data about patients, injuries, treatment features and clinical and radiological results were collected. We performed a statistical analysis; both descriptive and analytical. RESULT: 16 patients integrated the sample. 15 suffered associated fracture patterns. Anatomical plates were used in 15. Four required extended approaches. Reduction was anatomical in 9. 7 suffered some complication, needing the additional surgical procedures in 4. The surgical site infection rate was particularly high, appearing in 3. DISCUSSION: Radiological results were within the previously reported. We had a high complication rate, particularly infection. This outcome may be influenced by the special complexity of our cases and the adaptation process to a new technique. CONCLUSSION: Using the Stoppa approach we achieved lots of good or anatomical reductions. However, is an exigent and not without complications technique.

Morphometry and morphology of the acetabulum within the black African population of South Africa / Morfometría y morfología del acetábulo dentro de la población africana negra de Sudáfrica

The acetabulum is the large cup-shaped cavity on the lateral surface of the hip bone, which articulates with the head of the femur to form the hip joint. The morphometry and morphology of the acetabulum is important in the diagnosis and treatment of hip joint injuries and disease. Population specific differences exist regarding the acetabulum, therefore, this study aimed to document the morphometry and morphology of the acetabulum within a Black African population in Kwa-Zulu Natal, South Africa. A total of 100 dry hip bones (R= 44; L= 56) from the University of KwaZulu-Natal (Westville and NRMSOM campuses) were examined for this study. The hip bones, with documented sex, were all from the Black African population. A sliding digital caliper was used to measure the acetabular diameter, depth and acetabular notch width. The morphology of the acetabular margin was document in accordance with Govsa et al. (2005). Statistical analysis was conducted using SPSS version 24 software. A p-value of less than 0.05 was considered statistically significant. The means and standard deviations of the morphometric measurements for the entire population were as follows: (a) acetabular diameter of 54.84 ± 4.18 mm, (b) acetabular depth of 31.30 ± 3.18 mm and (c) acetabular notch width of 21.72 ± 2.98 mm. The observed shapes of the acetabular margin that were angular (41 %), curved (22 %), irregular (23 %) and straight (14 %). Knowledge of the anatomy of the acetabulum is useful to surgeons, prosthetists, anthropologists and forensic anthropology experts. The morphometry and morphology of the Black African population group of KwaZulu-Natal presented with differences when compared to other population groups studied in literature.

El acetábulo es una cavidad grande, en forma de copa, ubicada en la superficie lateral del hueso coxal, que se articula con la cabeza del fémur para formar la articulación coxofemoral. La morfometría y morfología del acetábulo son importantes en el diagnóstico y tratamiento de las lesiones y enfermedades de las articulaciones de la cadera. Existen diferencias específicas de la población con respecto al acetábulo, por lo tanto, este estudio tuvo como objetivo documentar la morfometría y la morfología del acetábulo en una población Africana negra, perteneciente a Kwa-Zulu Natal, Sudáfrica. Para este estudio se examinaron un total de 100 huesos coxales secos (Right = 44; Left = 56) de la Universidad de KwaZulu-Natal (campus de Westville y NRMSOM). Los huesos coxales, con sexo documentado, eran todos de población africana negra. Se utilizó un calibrador digital deslizante para medir el diámetro acetabular, la profundidad y el ancho de la incisura acetabular. La morfología del margen acetabular anterior se documentó de acuerdo con Govsa et al. (2005). El análisis estadístico se realizó utilizando el software SPSS versión 24. Un valor de p inferior a 0,05 se consideró estadísticamente significativo. Las medias y desviaciones estándar de las medidas morfométricas para toda la población fueron las siguientes: (a) diámetro acetabular de 54,84 ± 4.18 mm, (b) profundidad acetabular de 31,30 ± 3,18 mm y (c) ancho de la incisura acetabular de 21,72 ± 2,98 mm. Las formas observadas del margen acetabular fueron angulares (41 %), curvas (22 %), irregulares (23 %) y rectas (14 %). El conocimiento de la anatomía del acetábulo es útil para cirujanos, antropólogos y expertos en antropología forense. La morfometría y morfología del grupo poblacional de África negra de KwaZulu-Natal presentaron diferencias cuando se compararon con otros grupos poblacionales estudiados en la literatura.

Acetabular erosion following bipolar hemiarthroplasty: A Role for the size of femoral head?

INTRODUCTION: Femoral neck fractures are the most frequent fractures in the elderly and hemiarthroplasty is the treatment of choice. The objective of this study is to identify predictive factors of acetabular erosion after bipolar hemiarthroplasty in a mobile independent population during a follow-up of ten years. MATERIALS AND METHODS: This multicenter study started in 1997 ending in 2007. Data were prospectively collected and retrospectively analyzed. Inclusion criteria were: age > 60 and < 85 years, BMI < 35, normal Abbreviated MiniMental Test score, ability to walk 0.8 km and live independently, non-pathological fracture, hip with no or minimal osteoarthritic changes, and availability of clinical and radiological follow-up. For each Patient were recorded: demographic data, comorbidities, time from fracture to surgery, characteristics of the implant, duration of surgery. Patients included underwent clinical and radiological follow-up at a minimum of ten years. RESULTS: Overall, 209 Patients met inclusion criteria. A press-fit implant was performed in 172 subjects; in contrast a cemented prosthesis was implanted in 37 patients. Nineteen patients underwent implant revision to total hip arthroplasty for acetabular erosion and pain. Classification of X-ray using Baker criteria showed a grade 0 in 54.5%, a grade 1 in 19.6%, a grade 2 in 18.1% and a grade 3 in 7.6%. Multivariate analysis revealed that the size of the femoral head (FH) was the only predictive factor of a higher risk of acetabular erosion. The Kaplan-Meier survival curve verified the risk of implant revision in Group 1 (FH sized > 48 mm) and Group 2 (FH sized < 48 mm). The probability of implant revision for acetabular erosion at ten years from surgery were 5.5% in Group 1 and 15.6% in Group 2. CONCLUSION: In bipolar hemiarthroplasty smaller head size lead to a polar wear implying a higher risk of acetabular erosion and migration; in our population this risk was consistent with the use of implant head < 48 mm diameter. Considering the absolute risk of a smaller FH size, the surgeon must evaluate the accuracy of measurement of the caliber, since as reported in previous studies, it can significantly underestimate the size.

Non-equivalent Results from Different Anteversion Measurements Methods for the Evaluation of the Acetabular Cup Orientation in Total Hip Arthroplasty.

OBJECTIVE: To determine the comparability among 10 radiographic anteversion methods for acetabular cup orientation in total hip arthroplasty (THA) found in the literature and the "gold" standard of assessing the anteversion with CT. METHODS: This is a retrospective study that blindly compares 10 different conventional radiographic anteversion measurements with the "gold" standard, the measurement of anteversion on the transverse plane of the 3-D images made with CT. The patient archiving and communications system (PACS) was systematically searched for subjects that had undergone a CT angiogram of the abdomen and lower extremities, including the pelvis, had at least one THA in situ and had undergone anterior-posterior (AP) and cross-lateral pelvic radiography between January 2013 and August 2016 in the Diakonessenhuis Hospital Utrecht/Zeist, a non-academic institution. CT scans of patients (n = 16) were systematically collected. Three observers independently measured cup anteversion from radiographs, using a total of 10 different methods, and measured the "gold" standard on CT images. The outcomes of the 10 radiographic anteversion were compared in terms of linear correlation with the "gold" standard on CT images. RESULTS: The correlations of the radiographic measured anteversions with the "gold" standard measured on CT images were 0.528 for the method of Liaw, 0.556 for Wan, 0.562 for the cross-lateral method, 0.586 for Hassan, 0.594 for Dorr, 0.602 for Lewinnek, 0.624 for Widmer, 0.671 for the lateral CT, 0.747 for Ackland, and 0.771 for the method of Riten Pradham. CONCLUSION: Anteversion measurement methods represent different projectional angles of the acetabular cup in different planes around different axes. Therefore, they differ from the "gold" standard and are not interchangeable, as is shown by this study. We consider the anatomical anteversion in the transverse plane rotating around the longitudinal axis as the "gold" standard and recommend avoiding using the term anteversion for other projectional angles in different planes.