Tonnis Angle Research Articles

PREOPERATIVE 3D MODELING AND PRINTING FOR GUIDING PERIACETABULAR OSTEOTOMY

Background:Achieving adequate acetabular correction in multiple planes is essential to the success of Periacetabular Osteotomy (PAO). Three-dimensional (3D) modeling and printing has the potential to improve preoperative planning by accurately guiding intraoperative correction.Hypothesis/Purpose:We, therefore, asked the following questions: 1) For a patient undergoing a PAO, does 3D-modeling with intraoperative 3D-printed models create a reproducible surgical plan to obtain predetermined parameters of correction including lateral center-edge angle (LCEA), anterior center-edge angle (ACEA), Tonnis angle, and femoral head extrusion index (FHEI), 2) Can 3D computer modeling accurately predict when a normalized FHEI can be achieved without the need for a concomitant femoral sided osteotomy?Methods:A retrospective review was conducted on forty-two (42) consecutive patients that underwent a PAO. 3D-modeling software was utilized to simulate a PAO in order to achieve normal LCEA, ACEA, Tonnis angle, and FHEI. If adequate FHEI was not achieved, a femoral osteotomy was simulated. 3D-models were printed as intraoperative guides. Preoperative, simulated, and postoperative ACEA, LCEA, Tonnis angle, and FHEI were measured and compared statistically.Results:40 patients had a traditional PAO, and 2 had an anteverting-PAO. The simulated LCEA, ACEA, Tonnis angle, and FHEI were within a median difference of 3º, 1º, 1°, and 0% of postoperative values, respectively and showed no statistical difference. Of those that had a traditional PAO, all thirty-four (34) patients were correctly predicted to need a traditional acetabular sided correction alone and the other six (6) were correctly predicted to need a concomitant femoral osteotomy for a correct prediction in 100% of patients.Conclusion:This study demonstrated that in PAO, 3D-modeling and printing allow the surgeon to accurately create a reproducible surgical plan to obtain predetermined postoperative hip coverage parameters. This new technology has the potential to improve preoperative/intra-operative decision making for hip dysplasia and other complex disorders of the hip.

Factors Associated with Failure following Hip Arthroscopy for FAI in Patients over 40

Hip arthroscopy is considered one option in preserving the hip. Previous studies have shown age may be a predictor of failure; however, it is unclear what factors lead to failure in older patient. The purpose of this study was to determine factors associated with conversion to total hip arthroplasty in patient over 40 undergoing hip arthroscopy. 268 patients were identified who were over 40 years of age, had primary hip arthroscopy for FAI with labral repair. All had minimum joint space of >2mm. There were 144 females and124 males, with an average age of 49±6. Hips were evaluated using the modified Harris hip score(mHHS), Hip Outcome Score (HOS), WOMAC and patient satisfaction (1 to 10; 10=very satisfied). Conversion to THA was confirmed by patients. 87 patients underwent THA. Patients who converted to THA were significantly older (50 vs 48;p=0.001), higher Tonnis angle (10.7 vs 6.8;p=0.016), lower lateral center edge (34 vs 37;p=0.044), larger alpha angle (77 vs 70;p=0.028). The following preoperative subjective complaints were associated with THA: stiffness interfering with activity were 3.7 [95%CI, 2-7] time more likely to convert to THA(p<0.001); weakness were 2.7[95%CI,1.5-5] times more likely to convert to THA(p=0.001) and loss of motion were 1.9{95%CI,1.1 to 3.2] times more likely to convert to THA. At arthroscopy, the presence of femoral cyst was not associated with THR, but patients with an acetabular cyst were 3.0 [95%CI,1.6-5.4] times more likely to convert to THA. Patients with microfracture were 10 [95%CI, 6-18] times more likely to convert to THR. Using regression analysis, preoperative weakness, microfracture, and acetabular cyst were independent predictors of THA (p<0.001, R2=0.408). Of the patients who did not have THA, at an average 7-year follow-up (5 to 11 years), the mean SF-12 PCS was 51.7±9, and mHHS was 85±17, HOS ADL was 89±15. The median WOMAC was 5 [95%CI 8.7-12.9] and median patient satisfaction with outcome was 10 [95%CI 8-9]. HOS-ADL PASS was achieved in 75% of patients. Factors associated with THR following arthroscopy in patients over 40 include age, symptoms of weakness, stiffness, and loss of motion, and microfracture and acetabular cysts at arthroscopy. Those patients who do not require THR, have excellent outcomes and high patient satisfaction.

Changes in Satisfaction and Functional Outcomes between Years One and Two After Hip Preservation Surgery

Compare patient reported outcomes of pain, function, and satisfaction at 1-year and 2-years following hip preservation surgery. A cohort of 467 patients (61% female) from a multi-centered hip arthroscopy registry were analyzed for the purpose of this study. Subjects ranged from 18-72 years of age, averaged 161 pounds and were 67 inches tall. Patients had an average Tonnis Angle of 3.3, an alpha angle of 64.2, and a lateral center edge angle of 33.1. Surgical procedures included 183 (39.2%) chondroplasties, 13 (2.8%) acetabular microfractures, 180 (38.5%) acetabuloplasties, 81 (17.3%) femoral chondroplasties, 261 (55.9%) femoroplasties, 259 (55.5%) synovectomies, 233 (49.9%) labral repairs, 65 (8.1%) labral reconstructions, and 19 (4.1%) labral debridements. De-identified patient data from a multi-centered hip arthroscopy registry was analyzed. The data was collected from 7 individual surgical practices that each perform greater than 100 hip arthroscopy cases per year for a minimum of 8 years. Paired t-tests with an a priori alpha set at 0.05 determined if a significant change occurred for the International Hip Outcome Tool-12 (iHOT-12) and Visual Analog Scale (0-100) for patient satisfaction at 1-year versus 2-years post hip preservation surgery. The frequency of patients that surpassed the Patient Acceptable Symptomatic State (PASS) for the iHOT-12 were also reported and compared at 1-year and 2-years after hip preservation surgery. Patients achieve a high level of satisfaction and function at 1-year after surgery, and this is maintained at 2-year follow-up post-operatively.

A Semi-automatic Diagnosis of Hip Dysplasia on X-Ray Films.

Background: Diagnosis of hip joint plays an important role in early screening of hip diseases such as coxarthritis, heterotopic ossification, osteonecrosis of the femoral head, etc. Early detection of hip dysplasia on X-ray films may probably conduce to early treatment of patients, which can help to cure patients or relieve their pain as much as possible. There has been no method or tool for automatic diagnosis of hip dysplasia till now.Results: A semi-automatic method for diagnosis of hip dysplasia is proposed. Considering the complexity of medical imaging, the contour of acetabulum, femoral head, and the upper side of thigh-bone are manually marked. Feature points are extracted according to marked contours. Traditional knowledge-driven diagnostic criteria is abandoned. Instead, a data-driven diagnostic model for hip dysplasia is presented. Angles including CE, sharp, and Tonnis angle which are commonly measured in clinical diagnosis, are automatically obtained. Samples, each of which consists of these three angle values, are used for clustering according to their densities in a descending order. A three-dimensional normal distribution derived from the cluster is built and regarded as the parametric model for diagnosis of hip dysplasia. Experiments on 143 X-ray films including 286 samples (i.e., 143 left and 143 right hip joints) demonstrate the effectiveness of our method. According to the method, a computer-aided diagnosis tool is developed for the convenience of clinicians, which can be downloaded at http://www.bio-nefu.com/HIPindex/. The data used to support the findings of this study are available from the corresponding authors upon request.Conclusions: This data-driven method provides a more objective measurement of the angles. Besides, it provides a new criterion for diagnosis of hip dysplasia other than doctors' experience deriving from knowledge-driven clinical manual, which actually corresponds to very different way for clinical diagnosis of hip dysplasia.

Preoperative 3D Modeling and Printing for Guiding Periacetabular Osteotomy.

Achieving adequate acetabular correction in multiple planes is essential to the success of periacetabular osteotomy (PAO). Three-dimensional (3D) modeling and printing has the potential to improve preoperative planning by accurately guiding intraoperative correction. The authors therefore asked the following questions: (1) For a patient undergoing a PAO, does use of 3D modeling with intraoperative 3D-printed models create a reproducible surgical plan to obtain predetermined parameters of correction including lateral center edge angle (LCEA), anterior center edge angle (ACEA), Tonnis angle, and femoral head extrusion index (FHEI)? and (2) Can 3D computer modeling accurately predict when a normalized FHEI can be achieved without the need for a concomitant femoral-sided osteotomy? A retrospective review was conducted on 42 consecutive patients that underwent a PAO. 3D modeling software was utilized to simulate a PAO in order to achieve normal LCEA, ACEA, Tonnis angle, and FHEI. If adequate FHEI was not achieved, a femoral osteotomy was simulated. 3D models were printed as intraoperative guides. Preoperative, simulated and postoperative radiographic ACEA, LCEA, Tonnis angle, and FHEI were measured and compared statistically. A total of 40 patients had a traditional PAO, and 2 had an anteverting-PAO. The simulated LCEA, ACEA, Tonnis angle, and FHEI were within a median difference of 3 degrees, 1 degrees, 1 degrees, and 0% of postoperative values, respectively, and showed no statistical difference. Of those that had a traditional PAO, all 34 patients were correctly predicted to need a traditional acetabular-sided correction alone and the other 6 were correctly predicted to need a concomitant femoral osteotomy for a correct prediction in 100% of patients. This study demonstrates that for PAO surgery, 3D modeling and printing allow the surgeon to accurately create a reproducible surgical plan to obtain predetermined postoperative hip coverage parameters. This new technology has the potential to improve preoperative/intraoperative decision making for hip dysplasia and other complex disorders of the hip.

Tonnis Angle and Acetabular Retroversion Measurements in Asymptomatic Hips Are Predictive of Future Hip Pain: A Retrospective, Prognostic Clinical Study.

Background:This study evaluated the prevalence of radiographic abnormalities potentially indicative of femoroacetabular impingement on AP pelvic radiographs in asymptomatic adolescents and young adults and aimed to determine whether the abnormalities were predictive of future hip pain.Methods:AP pelvis images from scoliosis radiographs were obtained from patients 12 to 25 years of age free of any clinical hip/lower extremity symptoms between January 2006 and September 2009. The following radiographic abnormalities were collected: lateral center-edge angle of Wiberg >40° or <25°, Tönnis angle <0° or >10°, acetabular retroversion (crossover sign with a posterior wall sign), acetabular overcoverage (crossover sign without a posterior wall sign), and anterior offset alpha angle, calculated using alpha angle of Nötzli >50°. Patients were retrospectively followed (average 3.11 years) to identify those who subsequently developed hip pain.Results:Of the 233 patients (466 hips) who were asymptomatic at the time of radiographic evaluation, at least one radiographic abnormality was present in 60% (281/466) of the hips. Within that group of hips (n = 281), 69% (195/281) of hips demonstrated a single abnormality, whereas 31% (86/281) of hips were associated with multiple abnormalities. Among all hips (n = 466), a lateral center-edge angle <25° or >40° was the most common radiographic abnormality, present in 27% (127/466) of hips. Anterior offset alpha angle and acetabular overcoverage were the most common abnormalities to present together, found in 5% (25/466) of hips. In the multivariable model, a decreasing Tönnis angle (hazard ratio per 1-degree decrease: 1.25, 95% confidence interval, 1.10–1.42, P = 0.0006) and the presence of acetabular retroversion (hazard ratio: 3.55, 95% confidence interval, 1.15–10.95, P = 0.0272) were predictive of the development of future hip pain.Conclusions:Our study demonstrates a high prevalence of radiographic abnormalities indicative of femoroacetabular impingement in asymptomatic adolescents and young adults. A decrease in Tönnis angle and the presence of acetabular retroversion were predictive of future hip pain.

Periacetabular Osteotomy as a Salvage Procedure: Early Outcomes in Patients Treated for Iatrogenic Hip Instability.

A periacetabular osteotomy (PAO) can reduce pain and improve quality of life in patients with hip dysplasia. While its utility for patients without traditional radiographic parameters for hip dysplasia has not been previously established, the PAO may help treat patients with hip instability that does not improve following single or multiple hip arthroscopic procedures, or when such procedures lead to hip instability. A single-surgeon registry of patients at a single institution was queried to identify patients with a lateral center-edge angle (LCEA) of ≥24° and a Tönnis angle of <10° who underwent PAO because of hip pain and/or instability that failed treatment with hip arthroscopy. Descriptive summary statistics were reported on patient demographics, mean change in LCEA, and patient-reported outcome measures, including the modified Harris hip score (mHHS) and the International Hip Outcome Tool-33 (iHOT-33), at a minimum of 6 months of follow-up. Among 25 patients (mean age, 27.3 ± 6.9 years; 100% women), the mean LCEA increased from 27.2° (range, 24° to 37°) preoperatively to 39.0° ± 5.1° postoperatively (net increase, 11.8° ± 4.5°). Overall, the mean improvement in the mHHS was 11.5 ± 16.9 (preoperative, 59.4 ± 11.6; postoperative, 70.9 ± 20.6) and the mean improvement in the iHOT-33 was 23.8 ± 23.6 (preoperative, 32.2 ± 17.2; postoperative, 56.0 ± 30.0). Eighteen patients (72%) achieved a minimal clinically important improvement in mHHS (mean improvement, 17.4 ± 12.9) and iHOT-33 (mean improvement, 32.4 ± 19.1) scores. In comparison with 7 patients who did not show improvement, the 18 patients who showed improvement had significantly greater mean baseline patient-reported outcome scores. To our knowledge, these findings provide the first report on outcomes of PAO in patients with hip pain following arthroscopy who do not meet the traditional criteria for acetabular dysplasia. Early benefits in clinical outcomes suggest a novel surgical indication for PAO as a potential salvage option for selected patients; however, longer-term studies are needed. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Contralateral slip after unilateral slipped capital femoral epiphysis is associated with acetabular retroversion but not increased acetabular depth and overcoverage.

Overcoverage of the femoral head by the acetabulum, increased acetabular depth and retroversion have been associated with the etiology of slipped capital femoral epiphysis (SCFE). However, limited evidence exists about the impact of the acetabular morphology on the development of a contralateral slip following an initial presentation of unilateral SCFE. We aimed to investigate whether acetabular overcoverage as assessed by an increased lateral center-edge angle (LCEA) and low Tönnis angle, increased acetabular depth assessed by the acetabular depth-width ratio (ADR) and the presence of coxa profunda; and acetabular retroversion assessed by the presence of the crossover sign were associated with a contralateral slip in patients presenting with unilateral SCFE. We evaluated 250 patients with initial diagnosis of unilateral SCFE (average age, 12.5 ± 1.7 years), who had not undergone prophylactic fixation on the contralateral hip for a median follow-up of 49 months (interquartile range: 25-76 months). Endpoints were the development of a contralateral slip (70 patients, 28%) or skeletal maturity assessed by complete closure of the proximal femoral growth plate (180 patients, 72%). We measured the LCEA, Tönnis angle, ADR, and the coxa profunda sign on an anteroposterior pelvic radiograph. The crossover sign was assessed in 208 hips who had a secondary ossification center in the posterior acetabular rim. For each additional degree of LCEA, the odds of contralateral slip decreased 8% [odds ratio = 0.92; 95% confidence interval (CI), 0.87-0.98; P = 0.009]. Tönnis angle (P = 0.11), ADR (P = 0.20) and coxa profunda (p = 0.37) had no association with a contralateral slip. The presence of crossover sign increased two and half times the odds for a contralateral slip (odds ratio = 2.5; 95% CI = 1.12-5.64; P = 0.03). Acetabular retroversion, but not acetabular overcoverage or increased acetabular depth, was associated with contralateral SCFE development in patients with unilateral SCFE. Level of evidence: prognostic level II.

Can EOS imaging substitute traditional AP pelvis radiographs? A Comparative study

INTRODUCTION:Young patients followed for hip disorders often require serial imaging and incur significant radiation to the abdomen and pelvis. The EOS imaging system offers a low-radiation alternative. However, consistency with radiographic parameters from conventional radiographs (CR) have not been studied. We evaluated the reliability and validity of EOS imaging in comparison to CR in evaluating acetabular morphology.METHODS:48 hips (27 patients, 66.67% female, 14.4 ± 3.6 years old), indicated for open hip preservation procedure between 2015-2017, which had both EOS imaging and AP pelvis CR taken pre-operatively were examined. Both symptomatic and contralateral hips were measured, excluding hips with prior osteotomies.Three orthopaedic surgeons measured Tonnis angle, lateral center edge angle (LCEA), acetabular depth ratio (ADR), and extrusion index (EI) in both imaging modalities. Images were measured twice, two weeks apart. Reliability was assessed using intraclass correlation coefficients (ICC). Bland-Altman analysis was used to evaluate test-retest agreement and inter-modality agreement.RESULTS:Test-retest reliability was excellent for all raters on all tests (ICC range 0.8047 to 0.9714). Inter-rater reliability was also excellent for all measures on both modalities (ICC range 0.8593 to 0.9547). ICC values were consistent across EOS and CR.By Bland-Altman analysis, test-retest agreement was high, with no statistically significant mean differences in any test or modality (p > 0.6) except LCEA measured on EOS images (p = 0.02), which was 1.16° lower.Tonnis angle (p < 0.005) and ADR (p < 0.001) were statistically different from EOS to CR. Bias was also not uni-directional across tests: LCEA and ADR were, on average, higher on CR while Tonnis angle and EI were, on average, higher on EOS images. Reliability between the EOS and CR images was excellent for all raters on all tests (ICC range 0.8402 to 0.9458).DISCUSSION AND CONCLUSION:LCEA, ADR, EI, and Tonnis angle have consistently high test-retest reliability, test-retest agreement, and inter-observer reliability in both EOS imaging and CR to evaluate acetabular morphology. Inter-modality disagreement was observed between EOS and CR, but the difference was small and likely not clinically significant.When establishing acetabular morphology, these results suggest that EOS may provide an opportunity to minimize radiation exposure for patients followed long-term for hip pathology while maintaining the accuracy of diagnostic measures.Table 1.Reliability between EOS and traditional X-ray modalities for each of three raters, measured by the intra-class correlation coefficient (ICC).1 Table 2.Agreement between modalities in rater 2 at time point 1 using the Bland-Altman analysis of mean difference. Group means and standard deviation are shown for reference.

Can EOS Imaging Substitute for Conventional Radiography in Measurement of Acetabular Morphology in the Young Dysplastic Hip?

EOS imaging offers a low-radiation alternative to conventional radiography (CR) and has little to no magnification effects. However, it is unclear how radiographic measures may be affected using EOS. The present study aims to determine the reproducibility of measures of acetabular morphology on EOS images as compared with CR, and to directly compare the 2 imaging modalities. A total of 21 consecutive patients (66.7% female; 14.4±4.7 y) indicated for an open hip preservation procedure with both an anterior-posterior pelvis radiograph and EOS image performed preoperatively were included. Three orthopaedic surgeons measured Tönnis angle, lateral center edge angle (LCEA), acetabular depth-width ratio (ADR), and extrusion index (EI). Measurements were performed twice, 2 weeks apart. Reliability between observers and time points was measured using intraclass correlation coefficients, and agreement between time points and modalities was measured using Bland-Altman analysis. On EOS images, inter-rater reliability was 0.86 for Tönnis angle, 0.86 for LCEA, 0.74 for ADR, and 0.93 for EI. On CR, inter-rater reliability was 0.86 for Tönnis anlge, 0.90 for LCEA, 0.82 for ADR, and 0.84 for EI. In the agreement analysis, biases between imaging modalities were observed. On average, raters measured Tönnis angle and EI higher on EOS images than CR (2.22 degrees, 1.09%, respectively); and LCEA and ADR lower on EOS images than CR (1.54 degrees, 1.14% respectively). Limits of agreement (LOA) between modalities were similar to that of LOA observed in intra-rater analysis. Measures of acetabular morphology performed on EOS images have similarly high intra-rater and inter-rater reliability compared with CR. Measures performed on EOS also have similar intra-rater agreement as compared with CR. Intermodality agreement had similar LOA as intra-rater agreement on either individual imaging modality. Small biases between imaging modalities were detected. Level I-diagnostic study: investigating a diagnostic test.

Effects of shooting position on X-ray evaluation index of developmental hip dysplasia

Objective To explore the impacts of the imaging positions on the sagittal tilt of the pelvis and the imaging parameters of the hip joint. Methods From December 2015 to October 2016, a total of 78 female DDH patients (DDH group) who received Bernese periarticular osteotomy were enrolled, aged 28.41±9.91 years (range 18-49 years) with 135 hips. There were 21 cases on one side and 57 cases on both sides. Another 26 female volunteers without spinal and hip disease were enrolled as the control group, aged 23.54±5.58 years (range 18-49 years) with 52 hips. X-ray films of the anterior and posterior pelvis were performed in both groups. The pelvic sagittal tilt was evaluated by measurement (pubic symphysis to sacrococcygeal distance, PSSC), with lateral center-edge angle of Wiberg (LCEA), Tonnis angle (TA), and Sharp angle (angle of Sharp, SA) assessed the degree of hip dysplasia and assessed the horizontal positional relationship between the femoral head and the acetabulum using tear drop distance (TD). All data were measured twice by two measurers independently. The correlation between hip parameters and X-ray position was analyzed. Results The average PSSC in the supine and standing positions of the control group were 53.73±16.22 mm and 36.45±14.21 mm, respectively with significant difference-17.28±8.07 mm (t=-10.913, P=0.000). The PSSC of the supine and standing positions of the DDH group were 56.76±13.54 mm and 48.62±15.44 mm, respectively with significant difference-8.13±13.02 mm (t=-5.516, P=0.000). The PSSC of the standing DDH group was larger than that in the control group. There was no significant difference in the PSSC between the two groups in the supine position. Furthermore, there were no significant difference in the supine and standing PSSC between the unilateral and bilateral DDH patients (P>0.05). In the control group, the hip in supine and standing position, LCEA averaged 30.33°±4.69° and 29.70°±3.83° (P>0.05), and TA averaged 4.05°±3.51° and 4.36°±3.07° (P>0.05), respectively. SA averaged 40.53°±4.34° and 41.79°±3.16° (P>0.05), and TD averaged 6.80±0.98 mm and 6.65±1.30 mm (P>0.05), respectively. In the DDH group, the hip in supine and standing positions, LCEA averaged 3.07°±12.07° and 1.69°±12.11° (P 0.05), respectively. SA averaged 48.01°±4.68° and 48.49°±4.74° (P>0.05), respectively, and TD averaged 10.51±3.51 mm and 10.93±4.23 mm (P>0.05), respectively. Conclusion From supine to standing, the pelvis backward is the main trend in sagittal plane. In standing, the pelvis of female DDH patients is forward contrast with normal women. There was no difference in pelvic tilt between unilateral and bilateral DDH patients. Female DDH patients from the supine to standing, hip coverage decreased, while the femoral head appeared horizontally outward. The hip joint of DDH patients is unstable. Key words: Hip dislocation, congenital; Pelvis; Photogrammetry; Osteotomy

Reliability and normative values of common adult radiographic parameters for hip preservation in the developing pelvis

AbstractAnterior–posterior (A/P) radiography of the pelvis is essential to the diagnosis and treatment of developmental dysplasia of the hip (DDH). Multiple well-defined parameters of adult hip morphology with good reliability are readily available. The purpose of this study was to determine normative values and observed reliability for 10 common adult hip parameters in the developing pelvis of male and female patients aged 6 months–16 years. One hundred and fifty-eight standardized A/P pelvic radiographs were randomly selected from an existing trauma patient database and stratified into five age groups. Mean values or presence of categorical values and the observed reliability of 10 adult hip parameters (acetabular index/angle, pelvic width index, lateral center edge angle, Tonnis angle, acetabular to femoral head distance, femoral head diameter, coxa profunda/protrusio, ischial spine sign, crossover sign and posterior wall sign) were determined. Minimal differences in all parameters were observed between male and female patients. The observed inter-rater reliability of continuous parameters was 0.77–0.99. The observed intra-rater reliability was 0.7–0.99 with a combined intra-rater reliability of 0.88–0.99. The observed inter-rater reliability of categorical variables was 0.64–1.0. The intra-rater reliability of categorical variables was 0.83–1.0. Normative values for 10 common adult hip parameters were determined for male and female patients in the developing pelvis. Reliable knowledge of these values and their relationship to the age of the patient and/or stage of pelvic development associated may provide additional information to aid the treatment of DDH.

The Reliability of Commonly Used Radiographic Parameters in the Evaluation of the Pre-Arthritic Hip: A Systematic Review.

Radiographs play a central role in the evaluation of the extent of arthritic change and the quantification of morphological parameters characteristic of femoroacetabular impingement (FAI) and/or dysplasia. Reporting of these parameters is widespread in the literature, occasionally as an instrument for data pooling in collaborative research endeavors. Yet, the metrological properties of commonly used radiographic descriptors of acetabular and femoral architecture relevant to the field of hip preservation have not been reviewed systematically. The purpose of the present review was twofold: (1) to identify the current body of data available on the reliability of commonly used radiographic descriptors of the pre-arthritic hip and (2) to collate best practices and methodological pearls and pitfalls from the existing investigations that have explored the reliability of these radiographic measures. Article screening methodology involved an extensive search of 2 databases (PubMed Central, Embase). Metrological reliability data and best practices and frequencies with which these practices have been reported in existing investigations were extracted from the methods of the included studies. The radiographic parameters that were chosen as a focus for the present review were based on a discussion among a number of experienced hip-preservation surgeons. Forty-three articles met all inclusion criteria and were included in this review. Eleven recurring components of study design were isolated from the included investigations as being critical for minimizing bias in the assessment of the reliability of these radiographic morphological parameters. Sixteen (37.2%) of the included studies reported the use of at least 1 quality-control measure for ensuring radiographic integrity. The radiographic parameters with the most reliability data included the lateral center-edge angle (22 studies), the Tönnis angle (14 studies), and the alpha angle (18 studies). Categorical markers of acetabular retroversion and the extent of osteoarthritis have been less-frequently studied with respect to their reliability, with the exception of the crossover sign, which was evaluated in 11 of the included studies. The radiographic parameter with the most metrological evidence in support of its reliability was the lateral center-edge angle (with 22 [100%] of 22 studies reporting acceptable reliability), whereas the Tönnis grade of osteoarthritis consistently demonstrated subpar interrater and intrarater reliability. Side-arm investigations for testing reliability may be needed by individual studies to prove the validity of data-pooling practices as collaborative endeavors continue to become more widespread.

Prevalence of radiologic acetabular dysplasia in asymptomatic Asian volunteers.

The purpose of this study was to evaluate the prevalence of acetabular dysplasia in an asymptomatic Asian population as one of the most important risk factors of hip osteoarthritis. From December 2014 to March 2015, we investigated the data of 200 asymptomatic volunteers (400 hips) aged 18–50 years recruited from our institution. Pelvic radiographs were taken and reviewed by two experienced orthopaedic surgeons. Lateral centre-edge (LCE) angle, Sharp angle, Tonnis angle and acetabular depth-to-width ratio (AD/WR) were measured. We investigated the mean values and identified the statistical differences between the sexes and evaluated the prevalence and bilaterality of acetabular dysplasia defined by each parameter. Mean LCE angle, Sharp angle, Tonnis angle and AD/WR were 26.2°, 41.3°, 8.5° and 0.28, respectively. All parameters showed more dysplastic results in females than in males and were statistically significantly different, except for AD/WR. When defined acetabular dysplasia as LCE angle <20°, Sharp angle >45°, Tonnis angle >14° or AD/WR <0.25, the prevalence of acetabular dysplasia by each parameter was 15.0%, 12.8%, 13.3% and 12.8%, respectively. There was a higher prevalence in females than in males; however, only Sharp and Tonnis angles showed significant differences. The bilaterality of acetabular dysplasia was 18.6–39.5% for all subjects. There is high prevalence of asymptomatic dysplastic hips in the Asian population.

Are femoroacetabular impingement tomographic angles associated with the histological assessment of labral tears? A cadaveric study.

PurposeThis study sought to investigate the association between tomographic femoroacetabular impingement (FAI) angles and histologically evaluated labral tears. The authors hypothesized that cadavers presenting with cam and pincer morphologies would present a higher prevalence of acetabular labral tears.MethodsTwenty fresh cadavers were submitted to computed tomography. Standard FAI angles were measured, including the alpha angle, femoral version, acetabular version, Tonnis angle and center-edge angle. A cam lesion was defined as an alpha angle greater than 50o. A pincer lesion was defined as a center-edge angle greater than 40o, a Tonnis angle less than 0o or acetabular version less than 0o. After dissection, three fragments of each acetabulum, corresponding to the antero-superior, superior and postero-superior acetabular rim, were obtained. These fragments were submitted to routine histological preparation. Each slide was evaluated for possible labral tears. Tears were classified according to their Seldes type.ResultsThe mean age of the cadavers was 50.2 years (SD: 7.4; 13 males). Sixteen (80%) of the cadavers had a cam lesion, and eight cadavers (40%) had a pincer lesion. Histologically, 16 (80%) of the cadavers had a labral tear in at least one region. According to the Seldes classification, 60.7% and 28.6% of these labral tears were type 1 and type 2, respectively. A mixed type of labral tear (10.7%), which represented a new form of Seldes tear, was described. Cadavers with a labral tear had significantly higher alpha angles than other cadavers (53.29o vs 49.33o, p = 0.01). Pincer lesions were not associated with labral tears. We found no association between pincer or cam lesions and Seldes classification.ConclusionCadavers presenting with higher alpha angles had a higher incidence of labral tears. No association was found between FAI and Seldes classification.Clinical relevanceThis study demonstrated a high prevalence of FAI abnormalities associated with histological alterations in a cadaveric sample. Joint damage may be present in the early stages of FAI.

Reliability of a New Radiological Parameter Named the Modified Tönnis Angle for the Evaluation of Acetabular Dysplasia in Adults

Objectives: To evaluate the reliability of Tonnis angle and modified Tonnis angle on pelvic radiographs in adults. Patients and Methods: Conventional anterior-posterior pelvic radiographs of patients were selected from the picture archiving communication system (PACS) in the department of medical radiology of the Second Hospital of Shandong University. Tonnis angle and modified Tonnis angle were measured. All measurements were performed by two experienced observers who worked independently of each other. These measurements were performed again after one month. They were performed digitally using tools of the PACS. Reliability of Tonnis angle and modified Tonnis angle was assessed by intraclass correlation coefficients and Bland-Altman plot. Results: A total of 142 patients (79 females and 63 males) with 284 hips were selected. Tonnis angle and modified Tonnis angle were measured on the 284 hips by two observers. Intraclass correlation coefficients (ICCs) for intraobserver agreement of measurements were 0.962 and 0.983 for Tonnis angle, and 0.971 and 0.984 for modified Tonnis angle. ICCs for interobserver agreement of measurements were 0.936 for Tonnis angle and 0.932 for modified Tonnis angle. Bland-Altman plot suggested good interobserver agreement of measurements for Tonnis angle and modified Tonnis angle. Conclusion: Reliability of Tonnis angle and modified Tonnis angle was good according to ICCs and the Bland-Altman plot.

Femoral nerve palsy is a mythic complication of Pavlik harness treatment for developmental dysplasia of the hip

Introduction Femoral nerve palsy (FNP) is reported as a potential complication of Pavlik harness treatment for developmental dysplasia of the hip (DDH). It is known to be transient, as it often resolves following strap adjustment to decrease hip flexion, which may jeopardize the treatment success. The purpose of this study was to report the incidence of this potential complication, to identify any possible associated risk factors and to evaluate its outcome without any specific strap release. Materiel et methodes A retrospective chart review was conducted on all DDH patients who underwent Pavlik harness treatment for DDH between August 1997 and June 2015 by a single physician. Our treatment protocol includes biweekly visits to the clinic for strap adjustment and evaluation of bilateral active knee extension as an indirect indicator of femoral nerve palsy during the entire treatment duration, 3 months in average. Femoral nerve palsy (FNP) was defined as a partial or total deficit in active knee extension anytime during or following the completion of Pavlik harness treatment. All cases of femoral nerve palsy were identified and reviewed. In unilateral cases, the DDH hip was compared to the non-affected side. All hips with femoral nerve palsy were compared to the remaining hips of the series and any possible risk factor for paralysis was recorded, including age, patient's size, severity according to Tonnis and hip flexion angle in the harness. Statistical analysis was undertaken. Resultats Fifty-three cases of femoral nerve palsy of various severity were identified from a group of 473 children with 527 hips treated for DDH (10%) at an average age of 3.9 months. Ninety-three percent of them presented during the first 2 weeks of treatment. FNP was more common in older and larger children with the most severe Tonnis type and a hip flexion angle in the harness above 90 degrees (P Discussion FNP is a fairly common complication of Pavlik harness treatment for DDH. It is most observed in higher Tonnis types, but its presence by itself is not predictive of treatment failure. The most significant risk factors for FNP seem to be DDH severity and hip flexion angle in the harness. FNP resolves spontaneously before completion of treatment without any specific measures and therefore does not require any strap release or harness discontinuation.

Surgery for Femoroacetabular Impingement in Skeletally Immature Patients: Radiographic and Clinical Analysis

Objectives:The improved recognition of symptomatic femoroacetabular impingement (FAI) has lead to an emphasis of early diagnosis and treatment in the adolescent population. The purpose of this study was to evaluate the radiographic and clinical outcomes in patients with open physes that underwent hip arthroscopy for the treatment of symptomatic FAI. Additionally, we describe the three-dimensional (3D) pathomorphology in this unique population.Methods:We retrospectively reviewed 39 hips (28 patients; 75% male) with a mean age 15.8 years (range, 12.8-19.3 years) with FAI, who additionally demonstrated open physes on pre-operative radiographs. Radiographic parameters included the lateral center edge (LCE), Tonnis angle, AP and lateral alpha angle and head-neck offset ratio (HNOr). Each patient also underwent a pre-operative CT scan, which was utilized for the evaluation for femoral and acetabular measurements and simulated range of motion (ROM) to impingement. Preoperative and post-operative functions were evaluated prospectively using the modified Harris Hip Score (mHHS) and pain on a visual analogue scale (VAS). All patients participated in organized athletics and 50% were in multiple sports year round.Results:All patients (100%) within this cohort had open femoral neck and iliac crest physis. The ischial tuberosity and greater trochanteric physes were open in 95% and 54% of the hips respectively. Although there was no significant difference between pre-operative and post-operative LCE and Tonnis angles, the alpha angle and HNOr were significantly improved (39.7° vs. 61.7°; p<0.001 and 0.19 vs. 0.17; p<0.001). Mean femoral version was 17.6°±7.4°, while the acetabular version at the 1:30 and 3:00 positions were 1.0°±6.7° and 14.0°±4.1°. The mean maximum alpha angle was 72.0°±12.1° and was located on average at the 1:15 position. Simulated ROM to bony impingement was 121.6°±12.1° for flexion, 33.8°±13.3° for internal rotation in 90 degrees of flexion. Mean follow-up was 18.6 months (range, 6.3 - 55.8 months). There was a mean 23.0-point improvement in the mHHS (pre-operative 69.4, post-operative 92.4; p<0.001) and a mean decrease of 3.5 points in the VAS for pain (pre-operative 5.2, post-operative 1.7; p<0.001). 93% percent of patients returned to their preinjury level of sports participation and did not feel limited by their hip. Multivariate analysis demonstrated that a greater pre-operative LCEA correlated with a greater change in the mHHS score (r=0.374, p=0.038). Similarly, a greater pre-operative AP alpha angle and change in the AP alpha angle also correlated with a greater change in the VAS pain score (r=0.411, p=0.038 and r=0.426,p=0.019, respectively). No major complications were noted, but 3 hips (2 patients) underwent revision hip arthroscopy during the follow-up period secondary to further development of cam-type FAI. There were no cases physeal growth arrest, growth disturbance, avascular necrosis.Conclusion:The arthroscopic approach for the treatment of FAI in adolescents with open physes is a safe and effective and has a high return to sports rate. Risk for recurrent FAI in the presence of open growth plates was noted. Young, highly athletic adolescent patients with a larger FAI pathomorphology demonstrate the most predictable improvement in clinical outcomes after arthroscopicy.

The Dancers Hip: The Hyperflexible Athlete: Anatomy &amp; Arthroscopic Clinical Outcomes

Objectives:Competitive Dance places high demands on the hips joints and return to these activities after surgical management of intra-articular pathology is not well documented.Methods:Between 2008 and 2016, hip arthroscopy was performed for 63 competitive dancers (78 hips) with a mean age 21.0 years. Specific types of dance performed included 54 studio dance and 43 high kick dance. Morphology included Cam-type FAI (99%), Pincer-type FAI (45%), Subspine impingement (83%), Borderline dysplasia (9%), Dysplasia (10%), and Normal (5%). The mean preoperative LCE angle was 29.9 deg, alpha angle was 52.3 deg (Lateral), and offset ratio was 0.16. A positive Cross-over (COS) and Posterior Wall (PW) sign were present in 60% of hips, and the mean Tonnis angle was 3.2 deg. Outcomes were evaluated with MHHS, SF-12 scores, VAS scores.Results:At mean 19.7 months follow-up, the mean outcome improvements were 23.5 points (MHHS), 10.4 points (SF-12), 3.8 points (VAS), (p<.01 for each). MHHS improved from 60.5 points, preoperatively, to 84.0 points at most recent f/u (p<0.01). Sixty-seven percent returned to their prior level of competitive dance, 22% returned to limited or modified dance, and 10% were unable to return to dance, included 1 retirement. Procedures performed included 95% labral repairs, 10% labral debridements, 99% femoral resections, 55% rim resections, 83% subspine decompressions, and 68% capsular plications.Conclusion:Hip pain in dancers can be challenging secondary to high demands placed on the hips. A specific arthroscopic approach addressing subtle osseous abnormalities and capsular laxity led to significantly improved outcomes for competitive dancers. Eighty Nine percent of Dancers ultimately returned to competitive Dance, although only 67% returned to their pre-injury competitive level.

Etiological importance of training frequency, age and prevalance of Femoroacetabular İmpingement(FAİ) in pediatric male athletes

Femoroacetabular impingement (FAİ) is a prearthrozic disease that causes hip pain in adolescent-adult patients. The aim of the study is, determining the prevalence of asymptomatic radiographic findings of FAİ, to examine the evaluation of prevalence difference according to age groups and the impact of the levels of physical activity at developmental period on the development of asymptomatic FAİ.Materials-Methods:In our study, we included 214 pediatric athletes from 8 football teams operating in Istanbul between 11-18 years of age in September 2015- January 2016. Ethics Committee approval was obtained for our study. AP pelvis and Frog-leg radiographs, curriculum vitae of the athletes, their injuries, and their realtime complaints have been questioned. The alpha angle, CE angle, Tonnis angle, collodiaphyseal angle is measured from the resulting AP and Frog leg radiographs and terms of morphological abnormalities (FAİ, dysplasia and coxa vara…) was noted. Also athletes dominant feet, weekly training period and the years they play soccer was noted. The obtained data were analyzed by one-way ANOVA and Student-T test.Results:The average age of the 214 pediatric male athletes that included was 15(10-18). Asymptomatic FAİ prevalence of all ages was %29.9, % 0 in the range of 10-12 years, %13.1 in the range of 13-15 years, %45.7 in the 15-18 age range. These findings showed that significantly increased prevalence of FAİ in line with age in pediatric athletes statistically (p <0.05). The mean right hip alpha angle of all athletes was 50.7, left alpha angle was 50.3, right-CE angle was 28.6, left CE angle was 29.5, right Tönnis Angle 6.6, left Tönnis angle 5.0, right neck-shaft angle 133.9, left neck-shaft angle 134.7 degrees found. There was 7 acetabular dysplasia, 56 athletes with CAM type FAS, 4 athletes Pincer type FAS, and 4 combined FAS was found. There was no significant statistical relationship in the prevalences of FAİ between the number of years he worked as an athlete or the side which they hit the ball. However a positive correlation was found between weekly training hours (p <0.05). There were no statistical relationship between morphological abnormalities and previous injuries.Discussion:Among the etiology oriented researches, investigation for developmental factors still continues. İn our study, it is found that the sports activities in the pediatric period that are accused can be a factor in FAİ development due to the positive correlation between pediatric athletes age ang training frequency.