Recognition of minor adult hip dysplasia: which anatomical indices are important?

The incidence of subsequent hip arthroscopy after rectus-sparing periacetabular osteotomy

Aims

Periacetabular osteotomy (PAO) is the preferred treatment for symptomatic acetabular dysplasia in adolescents and young adults. There remains a lack of consensus regarding whether intra-articular procedures such as labral repair or improvement of femoral offset should be performed at the time of PAO or addressed subsequent to PAO if symptoms warrant. The purpose was to determine the rate of subsequent hip arthroscopy (HA) in a contemporary cohort of patients, who underwent PAO in isolation without any intra-articular procedures.

Methods

From June 2012 to March 2022, 349 rectus-sparing PAOs were performed and followed for a minimum of one year (mean 6.2 years (1 to 11)). The mean age was 24 years (14 to 46) and 88.8% were female (n = 310). Patients were evaluated at final follow-up for patient-reported outcome measures (PROMs). Clinical records were reviewed for complications or subsequent surgery. Radiographs were reviewed for the following acetabular parameters: lateral centre-edge angle, anterior centre-edge angle, acetabular index, and the alpha-angle (AA). Patients were cross-referenced from the two largest hospital systems in our area to determine if subsequent HA was performed. Descriptive statistics were used to analyze risk factors for HA.

Results

A total of 16 hips (15 patients; 4.6%) underwent subsequent HA with labral repair and femoral osteochondroplasty, the most common interventions. For those with a minimum of two years of follow-up, 5.3% (n = 14) underwent subsequent HA. No hips underwent total hip arthroplasty and one revision PAO was performed. Overall, 17 hips (4.9%) experienced a complication and 99 (26.9%) underwent hardware removal. All PROMs improved significantly postoperatively. Radiologically, 80% of hips (n = 279) reached the goal for acetabular correction (77% for acetbular index and 93% for LCEA), with no significant differences between those who underwent subsequent HA and those who did not.

Conclusion

Rectus-sparing PAO is associated with a low rate of subsequent HA for intra-articular pathology at a mean of 6.2 years' follow-up (1 to 11). Acetabular correction alone may be sufficient as the primary intervention for the majority of patients with symptomatic acetabular dysplasia.

Radiographic quantification of the normal and near-normal coxofemoral conformation in Labrador Retrievers and German Shepherds: a comparative study

BACKGROUND

Canine hip dysplasia (CHD) is a multifactorial disease affecting large breed dogs with associated joint laxity and incongruity that predisposes them to osteoarthritis. The purpose of the study is to objectively compare the conformation of normal and near-normal coxofemoral joints (CFJS) in Labrador Retrievers versus German Shepherds on the extended ventrodorsal radiograph. Investigated groups were categorized as normal and near-normal CFJS according to the morphometric criteria established by the FCI scoring system. Center-edge (CE) angle, Norberg angle (NA), indices of dorsal AFH coverage width and area, acetabular slope (AS) angle, and inclination angle were determined for each group. CE angle and AS angle were modified from previously described human techniques. The width and area of dorsal AFH coverage were standardized by the corresponding femoral head diameter and area. Variables were compared between groups using an unpaired, two-tailed t-test. A Spearman correlation coefficient determined the relationship between selected variables.

RESULTS

In Labradors, CE angle (lateral coverage) and dorsal AFH coverage area index (dorsal coverage) were greater in normal versus near-normal CFJS. In German Shepherds, lateral AFH coverage (CE angle and NA) was greater in normal versus near-normal hip joints; whereas, dorsal AFH coverage did not differ between the two groups. Lateral AFH coverage was greater in normal versus near-normal CFJS of both breeds. In Labradors, the inclination angle was greater in near-normal versus normal CFJS. Normal CFJS of Labradors revealed greater lateral and dorsal AFH coverages compared to German Shepherds. Near-normal joints of Labradors showed greater lateral AFH coverage compared to those of German Shepherds; whereas, dorsal AFH coverage did not differ between the two breeds. A steeper acetabular slope angle was noted in normal and near-normal CFJS of German Shepherds compared to Labrador Retrievers. The inclination angle of near-normal joints was greater in Labrador Retrievers compared to German Shepherds.

CONCLUSIONS

Overall, normal and near-normal CFJS of German Shepherds had lesser AFH coverage and steeper acetabular slope angle compared to Labrador Retrievers. Labrador Retrievers and German Shepherds with CE-angles < 27° and < 21.8°, dorsal AFH coverage width indices < 51 and < 49%, and/or dorsal AFH coverage area indices < 53 and < 50%, respectively, may be consistent with CHD. Thus, the authors would recommend excluding subjects with lower values from breeding. Validating the reported measurements is still warranted.

Patients With Low-Grade Lumbosacral Transitional Vertebrae Demonstrate No Difference in Achievement of Clinical Thresholds After Hip Arthroscopy for Femoroacetabular Impingement Syndrome

PURPOSE

To compare clinical outcomes at 2 years following primary hip arthroscopy (HA) for femoroacetabular impingement syndrome (FAIS) between patients with and without low-grade lumbosacral transitional vertebra (LSTV).

METHODS

We performed a retrospective matched-cohort analysis of patients who underwent primary HA for FAIS from 2011 to 2018 with minimum 2-year follow-up. LSTV was graded on preoperative radiographs using the Castellvi classification. Patients with grades I and II LSTV were matched 1:1 with controls on age, sex, and body mass index. Radiographic markers of FAIS morphology were measured. Pre- to postoperative improvement in the modified Harris Hip Score (mHHS) and Non-Arthritic Hip Score (NAHS) as well as 2-year achievement rates for the minimum clinically-important difference, substantial clinical benefit, and patient acceptable symptom state were compared between patients with versus without LSTV. The Wilcoxon signed-rank test was used for intergroup mean comparisons and the Cochran-Mantel-Haenszel test for categorical variables.

RESULTS

In total, 58 patients with LSTV were matched to 58 controls. Among LSTV patients, 48 were Castellvi type 1 (82.8%) and 32 (55.2%) had bilateral findings. No significant differences were found between groups with respect to radiographic markers of FAIS, including alpha angle (P = .88), lateral center edge angle (P = .42), or crossover sign (P = .71). Although patients with LSTV had greater improvement in NAHS at 2-year follow-up compared with control patients (P = .04), there were no significant differences in modified Harris Hip Score improvement (P = .31) or achievement of the minimum clinically-important difference (P = .73), substantial clinical benefit (P = .61), or patient acceptable symptom state (P = .16).

CONCLUSIONS

Patients with low-grade LSTV had greater 2-year improvement in NAHS than controls, whereas no significant differences were observed in achievement of clinical thresholds at 2-year follow-up. There were no differences between groups with respect to any measured radiographic markers of FAIS morphology. Importantly, the findings of this study are underpowered and should be viewed with caution in the greater context of the LSTV literature.

LEVEL OF EVIDENCE

III; retrospective comparative study.

Modified FCI (Fédération Cynologique Internationale) Scoring of the Coxofemoral Joint in Labrador Retrievers Without and With Hip Dysplasia

The objective is to propose a modified FCI scoring protocol of the canine hip joint via: (1) providing morphometric criteria of each score; (2) quantifying the extent of lateral and dorsal acetabular femoral head (AFH) coverage; (3) evaluating the steepness of cranial acetabular edge (acetabular index angle) and inclination angle (IA) in normal and dysplastic coxofemoral joints of Labrador Retrievers. The long-term goal is to achieve a selective breeding protocol using parental phenotypically healthy coxofemoral joints based on the standard extended-leg VD radiograph to help reduce the prevalence of CHD among offspring. Investigated populations were classified into normal (grade A) and dysplastic coxofemoral joints (grades B to E) based on the morphometric criteria previously established by the conventional FCI scoring system. Center-edge (CE) angle, Norberg angle (NA), indices of dorsal AFH coverage width and area, acetabular index angle, and inclination angle were determined for each group. Variables were compared between groups using ANOVA. Spearman correlation coefficient was used to determine the linear relationship between selected variables. Overall, all radiographic measurements differed significantly (P < 0.0001) among the five tested groups using ANOVA test. Dorsal AFH coverage area index was the only measure that differed significantly (P ≤ 0.007) between every two consecutive groups using Tukey's test. Significant correlations were identified between the Norberg and CE angles (r s = 0.95, P < 0.0001), the width and area of dorsal AFH coverage (r s = 0.96, P < 0.0001), and the radiographic techniques utilized to assess lateral vs. dorsal AFH coverage (r s ≥ 0.80, P < 0.0001). Evaluation of CE-angle, dorsal AFH coverage area index and acetabular index angle is recommended during selective breeding to include parents with radiographically healthy joints and reduce the incidence of hip dysplasia among offspring. Dogs with CE-angle <27°, dorsal AFH coverage area index <53%, and/or acetabular index angle >9° may be consistent with hip dysplasia and are recommended to be excluded from potential breeding groups. Re-evaluation of coxofemoral joints with borderline values located between near-normal and mildly dysplastic coxofemoral joints is strongly recommended to be performed after 6 months.

The Inverse Relationship Between Labral Size and Acetabular Coverage: Does It Protect the Cartilage in the Dysplastic Hip?

PURPOSE

The aims of this study were to confirm the relationship between osseous coverage and labral size and to investigate the severity of intra-articular damage in borderline dysplastic hips in correlation to labral size.

METHODS

Patients treated with primary hip arthroscopy for symptomatic labral tears between 2010 and 2018 were considered for this study. Patients were included if they had preoperative radiographic measures and intraoperative assessments of the labra and cartilage. The study group was divided into borderline dysplastic and nondysplastic groups via 3 measurements: lateral center edge angle (LCEA), acetabular index (Ax), and anterior center edge angle (ACEA). Undercoverage was defined as LCEA ≤ 25°, Ax ≥ 10°, and ACEA ≤ 20°. The labrum was measured in four quadrants: anterosuperior (AS), anteroinferior (AI), posterosuperior (PS), and posteroinferior (PI). Additionally, to assess cartilage damage in borderline dysplastic hips, hips with average labral size in the top quartile were compared to hips with average labral size in the bottom quartile.

RESULTS

A total of 1765 hips (1589 patients) were included in the study. The mean LCEA, Ax, and ACEA between the borderline dysplastic and nondysplastic groups were significantly different (P < .001). According to the Ax classification, there was significant evidence that borderline dysplastic hips had larger labra (P < .05). Among the dysplastic group, there was significantly more cartilage damage according to the Outerbridge classifications along both the acetabulum and femoral head in hips with labra in the upper quartile (P =.011 and .005, respectively).

CONCLUSION

An inverse relationship may exist between acetabular depth and labral size. Additionally, specifically in borderline dysplastic hips, a relatively large labrum correlates with worse intra-articular damage compared to borderline dysplastic hips with a relatively small labrum. Larger labral size may indicate a higher degree of instability in patients with borderline dysplasia.

LEVEL OF EVIDENCE

Level III, case-control study.

Can the Femoro-Epiphyseal Acetabular Roof (FEAR) Index Be Used to Distinguish Dysplasia from Impingement?

BACKGROUND

Classifying hips with structural deformity on the spectrum from impingement to dysplasia is often subjective and frequently inexact. Currently used radiographic measures may inaccurately predict a hip's morphological stability in borderline hips. A recently described radiographic measure, the Femoro-Epiphyseal Acetabular Roof (FEAR) index, has demonstrated an ability to predict stability in the borderline hip. This measure is attractive to clinicians because procedures can be used on the basis of a hip's pathomechanics. This study was designed to further validate and characterize the FEAR index in a skeletally immature population, in hips with dysplasia/femoroacetabular impingement (FAI), and in asymptomatic hips.

QUESTIONS/PURPOSES

(1) What are the characteristics of the FEAR index in children and how does the index change with skeletal maturation? (2) How does the FEAR index correlate with clinical diagnosis and surgical treatment in a large cohort of symptomatic hips and asymptomatic controls? (3) How does the FEAR index correlate with clinical diagnosis in the borderline hip (lateral center-edge angle [LCEA] 20°-25°) group?

METHODS

A total of 220 participants with symptomatic investigational hips with a clinical diagnosis of dysplasia or FAI between January 2008 and January 2018 were retrospectively collected from the senior author's practice. Investigational hips were excluded if they had any femoral head abnormalities preventing LCEA measurement (for example, Perthes disease), Tönnis osteoarthritis grade greater than 1, prior hip surgery, or prior femoral osteotomy. In the 220 participants, 395 hips met inclusion criteria. Once exclusion criteria were applied, 15 hips were excluded due to prior hip surgery or prior femoral osteotomy, and 12 hips were excluded due to femoral head deformity. A single hip was then randomly selected from each participant, resulting in 206 investigational hips with a mean age of 13 ± 3 years. Between January 2017 and December 2017, 70 asymptomatic control participants were retrospectively collected from the senior author's institutional trauma database. Control hips were included if the AP pelvis film had the coccyx centered over the pubic symphysis and within 1 to 3 cm of the superior aspect of the symphysis. Control hips were excluded if there was any fracture to the pelvis or ipsilateral femur or the participant had prior hip/pelvis surgery. After exclusion criteria were applied, 16 hips were excluded due to fracture. One hip was then randomly selected from each participant, resulting in 65 control hips with a mean age of 16 ± 8 years. Standardized standing AP pelvis radiographs were used to measure the FEAR index, LCEA, and Tönnis angle in the investigational cohort. Standardized false-profile radiographs were used to measure the anterior center-edge angle (ACEA) in the investigational cohort. Two blinded investigators measured the FEAR index with an intraclass correlation coefficient of 0.92 [95% CI 0.84 to 0.96]. Question 1 was answered by comparing the above radiographic measures in age subgroups (childhood: younger than 10 years; adolescence: 10 to 14 years old; maturity: older than 14 years) of dysplastic, FAI, and control hips. Question 2 was answered by comparing the radiographic measures in all dysplastic, FAI, control hips, and a subgroup of operatively or nonoperatively managed dysplasia and FAI hips. Question 3 was answered by comparing the radiographic measures in borderline (LCEA 20°-25°) dysplastic, FAI, and control hips.

RESULTS

The FEAR index was lower in older dysplastic of hips (younger than 10 years, 6° ± 9°; 10 to 14 years, 4° ± 10°; older than 14 years, 5° ± 9°; p < 0.001) and control hips (younger than 10 years, -6° ± 5°; 10 to 14 years, -15° ± 4°; older than 14 years, -16° ± 7°; p < 0.001). The diagnosis and age groups were independently correlated with the FEAR index (p < 0.001). The relationship between the FEAR index and diagnosis remained consistent in each age group (p = 0.11). The FEAR index was higher in all dysplastic hips (mean 5° ± 10°) than in asymptomatic controls (mean -13° ± 7°; p < 0.001) and FAI hips (mean -10° ± 11°; p < 0.001). Using -1.3° as a cutoff for FAI/control hips and dysplastic hips, 81% (112 of 139) of hips with values below this threshold were FAI/control, and 89% (117 of 132) of hips with values above -1.3° were dysplastic. The receiver operator characteristics area under the curve (ROC-AUC) was 0.91. Similarly, the FEAR index was higher in borderline dysplastic hips than in both asymptomatic borderline controls (p < 0.001) and borderline FAI hips (p < 0.001). Eighty-nine percent (33 of 37) of hips with values below this threshold were FAI/control, and 90% (37 of 41) of hips with values above -1.3° were dysplastic. The ROC-AUC for borderline hips was 0.86.

CONCLUSION

The FEAR index was associated with the diagnosis of hip dysplasia and FAI in a patient cohort with a wide age range and with varying degrees of acetabular deformity. Specifically, a FEAR index greater than -1.3° is associated with a dysplastic hip and a FEAR index less than -1.3° is associated with a hip displaying FAI. Using this reliable, developmentally based radiographic measure may help hip preservation surgeons establish a correct diagnosis and more appropriately guide treatment.

LEVEL OF EVIDENCE LEVEL

III, diagnostic study.

The association of BMI and physical activity on acetabular dysplasia in children

BACKGROUND

Acetabular dysplasia is an important pre-disposing factor for osteoarthritis of the hip. However, it is not completely known how acetabular dysplasia develops during childhood.

OBJECTIVE

To study the prevalence of acetabular dysplasia and its association with body mass index (BMI) and physical activity in 9 year old children.

DESIGN

The population for this cross-sectional study was drawn from the ongoing prospective cohort study: Generation R. 9,778 mothers with a delivery date from March 2002 until January 2006 were enrolled. In a random subgroup of these children Dual-energy X-ray absorptiometry (DXA) scanning was performed at age 9.

EXPOSURES

BMI, standardized for the Dutch population and categorized in four groups based on extended international Obesity Task Force cut-offs: underweight, normal, overweight and obesity. Physical activity was based on time spent on playing outdoors, playing sports and walking/cycling to school.

MAIN OUTCOMES AND MEASURES

The degree of acetabular dysplasia was determined with the centre-edge angle (CEA) and acetabular depth-width ratio (ADR) in DXA images of the hip.

RESULTS

1,188 DXA images of children's hips were available for analysis. The median age of the children was 9.86 years. Prevalence of dysplasia and mild dysplasia was respectively 6.3%; 25.6% with CEA and 4.8%; 25.0% with ADR. BMI was negatively associated with mild dysplasia (OR 0.80 CI 0.71-0.90). Obese children showed less mild dysplasia compared to normal children (OR 0.48 CI 0.24-0.97) in unadjusted analysis. Physical activity represented by walking to school showed a statistically significant negative association with mild dysplasia (OR 0.87 CI 0.76-0.99). After adjustment for age, ethnicity, sex, first born, breech presentation, birthweight, gestational age and Caesarean section, the patterns of association with dysplasia remained for both BMI and physical activity.

CONCLUSIONS

In this study, being overweight and light physical activity were negatively associated with the development of (mild) acetabular dysplasia at the age of 9 years.

Computer-Aided System Application Value for Assessing Hip Development

Purpose

A computer-aided system was used to semiautomatically measure Tönnis angle, Sharp angle, and center-edge (CE) angle using contours of the hip bones to establish an auxiliary measurement model for developmental screening or diagnosis of hip joint disorders.

Methods

We retrospectively analyzed bilateral hip x-rays for 124 patients (41 men and 83 women aged 20-70 years) who presented at the Affiliated Zhongshan Hospital of Dalian University in 2017 and 2018. All images were imported into a computer-aided detection system. After manually outlining hip bone contours, Tönnis angle, Sharp angle, and CE angle marker lines were automatically extracted, and the angles were measured and recorded. An imaging physician also manually measured all angles and recorded hip development, and Pearson correlation coefficients were used to compare computer-aided system measurements with imaging physician measurements. Accuracy for different angles was calculated, and the area under the receiver operating characteristic (AUROC) curve was used to represent the diagnostic efficiency of the computer-aided system.

Results

For Tönnis angle, Sharp angle, and CE angle, correlation coefficients were 0.902, 0.887, and 0.902, respectively; the accuracies of the computer-aided detection system were 89.1, 93.1, and 82.3%; and the AUROC curve values were 0.940, 0.956, and 0.948.

Conclusion

The measurements of Tönnis angle, Sharp angle, and CE angle using the semiautomatic system were highly correlated with the measurements of the imaging physician and can be used to assess hip joint development with high accuracy and diagnostic efficiency.

Constitutional morphological features and risk of hip osteoarthritis: a case-control study using standard radiographs

OBJECTIVES

To evaluate the risk of association with hip osteoarthritis (OA) of 14 morphological features measured on standard antero-posterior pelvis radiographs.

METHODS

A case-control study of 566 symptomatic unilateral hip OA cases and 1108 controls without hip OA, using the Genetics of OA and Lifestyle database. Unaffected hips of cases were assumed to reflect pre-OA morphology of the contralateral affected hip. ORs with 95% CI adjusted for confounding factors were calculated using logistic regression. Hierarchical clustering on principal component method was used to identify clusters of morphological features. Proportional risk contribution (PRC) of these morphological features in the context of other risk factors of hip OA was estimated using receiver operating characteristic analysis.

RESULTS

All morphological features showed right-left symmetry in controls. Each feature was associated with hip OA after adjusting for age, gender and body mass index. Increased sourcil angle had the strongest association (OR: 6.93, 95% CI 5.16 to 9.32). Three clusters were identified. The PRC varied between individual features, as well as between clusters. It was 35% (95% CI 31% to 40%) for all 14 morphological features, compared to 21% (95% CI 19% to 24%) for all other well-established risk factors.

CONCLUSIONS

Constitutional morphological variation strongly associates with hip OA development and may explain much of its heritability. Relevant morphological measures can be assessed readily on standard radiographs to help predict risk of hip OA. Prospective studies are required to provide further support for causality.

A Multicenter Study of Radiographic Measures Predicting Failure of Arthroscopy in Borderline Hip Dysplasia: Beware of the Tönnis Angle

BACKGROUND

Hip arthroscopy has been previously demonstrated to be an effective treatment for adult mild hip dysplasia. There are many radiographic parameters used to classify hip dysplasia, but to date few studies have demonstrated which parameters are of most importance for predicting surgical outcomes.

PURPOSE

To identify preoperative radiographic parameters that are associated with poor outcomes in the arthroscopic treatment of adult mild hip dysplasia.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Radiographic analysis was performed in patients with mild hip dysplasia who underwent arthroscopic surgery between 2009 and 2015. Preoperative radiographic measurements included lateral center edge angle, Tönnis angle, neck shaft angle, anterior center edge angle, alpha angle, femoral head extrusion index, and acetabular depth-to-width ratio. Failure was defined as failure to achieve the minimal clinically important difference (MCID) utilizing the modified Harris Hip Score or as the need for secondary operation. The equal variance t test was used to analyze radiographic parameters. Statistical significance was determined using a P value of .05.

RESULTS

A total of 373 hips underwent analysis with an average follow-up of 41 months (range, 24-102 months). Of these, 46 hips (12%) required secondary operation, and 95 (25%) failed to meet the MCID. The overall failure rate was 32.4%. There was no single measurement or combination thereof associated with failure to reach the MCID. Higher preoperative Tönnis angles were associated with secondary operation, with a mean of 6.7° (95% CI, 5.3°-8.1°) in the secondary operation group versus 4.8° (95% CI, 4.4°-5.3°) in the nonsecondary operation group (P = .006). The odds ratio was 1.12 (95% CI, 1.0-1.2; P = .05) per degree increase in Tönnis angle for secondary operation. In patients with a Tönnis angle >10°, 84% required secondary operation.

CONCLUSION

Higher Tönnis angles portend a higher risk for revision surgery. The probability of secondary operation was increased by a magnitude of 1.12 with each degree increase in the Tönnis angle. In patients with a Tönnis angle >10°, 84% required a secondary operation.

Is the Femoro-Epiphyseal Acetabular Roof (FEAR) index on MRI a relevant predictive factor of instability in a borderline dysplastic hip?

AIMS

A borderline dysplastic hip can behave as either stable or unstable and this makes surgical decision making challenging. While an unstable hip may be best treated by acetabular reorientation, stable hips can be treated arthroscopically. Several imaging parameters can help to identify the appropriate treatment, including the Femoro-Epiphyseal Acetabular Roof (FEAR) index, measured on plain radiographs. The aim of this study was to assess the reliability and the sensitivity of FEAR index on MRI compared with its radiological measurement.

PATIENTS AND METHODS

The technique of measuring the FEAR index on MRI was defined and its reliability validated. A retrospective study assessed three groups of 20 patients: an unstable group of 'borderline dysplastic hips' with lateral centre edge angle (LCEA) less than 25° treated successfully by periacetabular osteotomy; a stable group of 'borderline dysplastic hips' with LCEA less than 25° treated successfully by impingement surgery; and an asymptomatic control group with LCEA between 25° and 35°. The following measurements were performed on both standardized radiographs and on MRI: LCEA, acetabular index, femoral anteversion, and FEAR index.

RESULTS

The FEAR index showed excellent intraobserver and interobserver reliability on both MRI and radiographs. The FEAR index was more reliable on radiographs than on MRI. The FEAR index on MRI was lower in the stable borderline group (mean -4.2° (sd 9.1°)) compared with the unstable borderline group (mean 7.9° (sd 6.8°)). With a FEAR index cut-off value of 2°, 90% of patients were correctly identified as stable or unstable using the radiological FEAR index, compared with 82.5% using the FEAR index on MRI. The FEAR index was a better predictor of instability on plain radiographs than on MRI.

CONCLUSION

The FEAR index measured on MRI is less reliable and less sensitive than the FEAR index measured on radiographs. The cut-off value of 2° for radiological FEAR index predicted hip stability with 90% probability. Cite this article: Bone Joint J 2019;101-B:1578-1584.

The management of the painful borderline dysplastic hip

Improved imaging and the evolution of surgical techniques have permitted a rapid growth in hip preservation surgery over the last few decades. The management of the painful borderline dysplastic hip however remains controversial. In this review, we will identify the pertinent issues and describe the patient assessment and treatment options. We will provide our own recommendations and also identify future areas for research.

Arthroscopic Treatment of Iliopsoas Snapping in Patients With Radiographic Acetabular Dysplasia Using Iliopsoas Fractional Lengthening and Capsular Plication

PURPOSE

The purpose of this study was to evaluate the greater than 2-year patient-reported outcomes (PROs) and patient satisfaction of patients who were treated with hip arthroscopy for snapping iliopsoas tendons that were painful with concomitant acetabular dysplasia and who underwent iliopsoas lengthening for symptomatic iliopsoas tendon snapping with concomitant capsular plication and treatment of hip impingement. Secondary measures included observation of the change in the Tönnis grade at greater than 2 years' follow-up.

METHODS

Between July 2009 and December 2011, data on patients with a lateral center-edge angle (LCEA) of less than 25° (range, 19°-24°) who underwent hip arthroscopy with central-compartment iliopsoas fractional lengthening and capsular plication were prospectively collected and retrospectively reviewed. Interportal capsular repair was performed using between 2 and 5 simple sutures. Patients also underwent procedures to treat hip impingement pathology. All patients had preoperative and minimum 2-year postoperative PRO measures: modified Harris Hip Score, Hip Outcome Score-Activities of Daily Living subscale, Hip Outcome Score-Sports-Specific subscale, and Non-arthritic Hip Score. The visual analog scale score and patient satisfaction with surgery (from 0 to 10) were also collected. Radiographs were analyzed preoperatively and at latest follow-up to assess progression of the Tönnis grade.

RESULTS

We analyzed 32 patients who met the inclusion criteria (30 female and 2 male patients; mean age, 25 years). The mean LCEA and anterior center-edge angle were 21.6° and 25.5°, respectively. Four patients required revision arthroscopy for labral retears. Among the 28 patients who did not undergo revision surgery, the modified Harris Hip Score, Hip Outcome Score-Activities of Daily Living subscale, Hip Outcome Score-Sports-Specific subscale, and Non-arthritic Hip Score improved from 68.7 to 83.5, from 64.9 to 86.6, from 71.6 to 86.7, and from 52.6 to 75.8, respectively (P < .001). The visual analog scale score improved from 5.6 preoperatively to 1.9 at latest follow-up (P < .001). The mean patient satisfaction rating was 8.0. There was no radiographic progression of the Tönnis grade at final follow-up.

CONCLUSIONS

This study showed that patients with an LCEA of less than 25° and associated painful iliopsoas snapping can be treated by addressing concomitant pathology and performing central-compartment fractional lengthening of the iliopsoas tendon with concomitant capsular plication and have high satisfaction, improvement in PROs, and improved pain scores, without significant progression of osteoarthritis.

LEVEL OF EVIDENCE

Level IV, case series.

Preservation of the rectus femoris origin during periacetabular osteotomy does not compromise acetabular reorientation

BACKGROUND

The early recovery period after periacetabular osteotomy (PAO) can be limited by pain and activity restrictions. Modifications of the Bernese PAO, including sparing the rectus tendon and discontinuing routine arthrotomy, may accelerate early postoperative recovery compared with the standard approach.

QUESTIONS/PURPOSES

Does a modified approach for PAO (1) lead to improved pain control immediately after surgery; (2) lead to improved ambulation during the hospital stay; (3) lead to shorter stays, less blood loss, and shorter surgical times; and (4) compromise acetabular correction?

METHODS

We retrospectively reviewed all 75 patients who underwent PAO for developmental dysplasia of the hip between August 2009 and May 2013. The control group included 44 consecutive patients who underwent a standard Bernese PAO with rectus takedown (RT). The study group consisted of 31 consecutive patients who underwent PAO using a modified rectus-sparing (RS) approach without routine arthrotomy. The groups were similar in age, body mass index, and American Society of Anesthesiologists score, but the RT group was comprised of a greater percentage of men than the RS group. Outcome variables were collected from patient charts and included inpatient pain, inpatient ambulation as well as length of stay, estimated blood loss, surgical time, and postoperative radiographic measurements. Cohen's f(2) was used to calculate the effect size in the regression analysis and effects were considered small for values<0.15, moderate for 0.15 to 0.34, and large for values>0.35.

RESULTS

Patients who underwent PAO with a RS approach had less overall pain (RT median 4 versus RS median 2); however, the difference may not have been perceptible to the typical patient (p=0.001, f2=0.059). Patients treated with the RS approach ambulated similar distances during the hospital stay with a median 11 feet (interquartile range [IQR], 0-72.5) for the RT group and a median 30 feet (IQR, 0-100) for the RS group (p=0.215, f2=0.095). Patients in the RT group had a median length of stay of 4 days (IQR, 4-5) compared with a median 3 days (IQR, 3-4) in the RS group (p<0.001). The median estimated blood loss was greater (p=0.010) in the RT group (median, 500 mL; IQR, 350-700) versus the RS group (median, 300; IQR, 250-500). The median surgical time was longer (p<0.001) in patients undergoing PAO with the RT approach (median, 159.5 minutes; IQR, 145.5-177) compared with the RS approach (median, 103 minutes; IQR, 75-114). Acetabular reorientation based on postoperative radiographs was not compromised by the modified approach.

CONCLUSIONS

The approach modification was straightforward to implement in all patients and did not compromise acetabular fragment mobilization or final positioning. Two of the three key variables that the approach might have influenced-pain and length of stay-were below the minimum clinically important difference and different by only a fraction of a day, respectively. The difference in ambulation was of only modest clinical importance. More definitive evidence for clinical superiority in terms of pain, ambulation, and return of muscle function will likely require more sophisticated instruments such as gait analysis, muscle strength testing, and longer-term outcome studies with sensitive instruments.

LEVEL OF EVIDENCE

Level III, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Superiority of the modified Tönnis angle over the Tönnis angle in the radiographic diagnosis of acetabular dysplasia

The aim of this study was to evaluate the limitations of the Tönnis angle as one of the most commonly used parameters in the diagnosis of acetabular dysplasia, and to explore the feasibility of the modified Tönnis angle in the diagnosis of acetabular dysplasia. A total of 224 patients (120 females and 104 males) with 448 hips, aged between 15 and 83 years (median, 45.0 years), were selected for the measurement of the center-edge (CE) and Tönnis angles. To evaluate the relative position of the medial edge of the acetabular sourcil, a new parameter, known as the center-medial-edge (CME) angle, was designed. As an improvement of the Tönnis angle, a new angle preliminarily termed the modified Tönnis angle was created. In addition, the degree of clarity of the medial edge of the acetabular sourcil on radiograph was evaluated, and the hips were divided into the clear-edge and blurred-edge groups. The hips belonging to the blurred-edge group could not be used for Tönnis angle measurements. All measurements were performed digitally using the tool of the picture-archiving communication system. Among the 448 acetabular sourcils, 142 had a blurred medial edge (31.7%). The mean value of the CME angle was 37.94°, with a range of 21.76–63.99°. The 95% prediction interval of the modified Tönnis angle was estimated to be −6.39 to 11.73°. The correlation coefficients were −0.838 between the CE and Tönnis angles, 0.889 between the Tönnis and modified Tönnis angles and −0.905 between the CE and modified Tönnis angles. In conclusion, the modified Tönnis angle can substitute for the Tönnis angle without joint space narrowing and subluxation of the hip, particularly when the Tönnis angle cannot be measured due to a blurred medial edge of the acetabular sourcil on pelvic radiograph.