Hip Dysplasia in the Young Adult

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.

Development of modified Ilizarov hip reconstruction surgery for hip dysfunction treatment in adolescent and young adults

Background/objective

Hip dysfunction in young population caused by developmental dysplasia of the hip, congenital hip deformity or femur head necrosis severely affect the quality of life of young patients, and total hip replacement is the current widely accepted standard therapy for hip function reconstruction in adults, but not for young patients. Alternative safe and effective surgical method for hip function preservation/reconstruction for young patients is lacking. Ilizarov hip reconstruction osteotomy was an alternative method for preserving hip function but the surgical procedures were rather complicated using discomforting ring fixation at the hip region that prevents its wider acceptance and application. Here we reported a modified Ilizarov hip reconstruction surgery for hip dysfunction/deformity correction in adolescent and young adults using femoral shaft osteotomy and simplified unilateral external fixation configuration at the hip region with satisfactory clinical outcomes.

Methods

This is a retrospective study with five male and twelve female patients aged from 10 to 34 years old (mean 20.6 years) including 11 developmental dislocations of the hip and 6 femoral head necrosis. Modified Ilizarov hip reconstruction y surgery was performed using single-arm triangular configuration, threaded half pins on the femur and multiple drill hole guide for osteotomy. The mechanical axis and limb length were corrected spontaneously during the subsequent limb lengthening process in all patients. Preoperative and postoperative gross appearance, radiography of the hip and hip function assessment scores were recorded and compared during the follow-up period.

Results

The mean follow-up period was 64.3 months (12–87 months). Satisfactory hip appearance, hip and knee functions were achieved in all patients, none resulted in hip replacement surgery at the follow-up period. The mean preoperative and postoperative Harris hip scores were 45.92 ​± ​19.41 and 87.16 ​± ​5.31, respectively (p ​< ​0.01). Pin-track infections occurred in four patients, treated successfully with wound dressing care and oral antibiotics. Restricted range of motion of the knee was observed in eight patients, all gradually overcome by active functional exercises. Osteotomy site fracture of the middle femurs after removing external devices occurred in two patients due to unexpected fall, and complete healing was achieved after plaster fixation. Complications such as fixation device failure, knee dislocation, vessel or nerve impairments did not occur.

Conclusions

Modified Ilizarov hip reconstruction surgery significantly reduced the surgery time and discomforts to patients, avoided the disturbance of blood supply at the osteotomy sites. This modified method is a useful alternative for correction of hip deformities and reconstruction hip function in adolescent and young adults who are not suitable for conventional pelvis support surgery or hip replacement surgery.

Translational potential statement

The modified Ilizarov hip reconstruction surgery provides an alternative for hip replacement surgery with satisfactory clinical outcomes. This procedure is minimally invasive, safe and simple, with few complications compared to conventional pelvis support surgery, and it may be the first choice of surgery for the management of hip dysfunction in adolescent and young adults.

Characterization of version in the dysplastic hip and the need for subsequent femoral derotational osteotomy after periacetabular osteotomy

Hip dysplasia is a three-dimensional pathomechanical condition that is often more complex than the standard method of measuring lateral center edge angle (CEA) can quantify. Yet there is a paucity of literature examining the differences in version seen between dysplastic and non-dysplastic femoroacetabular impingement (FAI) hips, the relationship of acetabular and femoral version (FV) within dysplastic hips and the contribution of each of these factors to symptoms and outcomes of dysplasia treatment. We sought to describe the acetabular version (AcetV) and FV in dysplastic hips and quantify how these measurements compared with non-dysplastic FAI hips. We also sought to analyze the association of these factors with patient-reported outcomes (PROs) after periacetabular osteotomy (PAO) and determine the need for subsequent femoral derotational osteotomy after PAO. A total of 113 dysplastic patients who underwent PAO (92% female, mean age 24) were compared with 1332 (45% female, mean age 25) non-dysplastic FAI (CEA > 25°) patients. We found that dysplastic hips had a statistically higher AcetV and FV than non-dysplastic FAI hips. There was a very weak correlation between AcetV and FV in dysplastic hips, suggesting that patients with higher AcetV did not necessarily have higher FV. There was no association with AcetV or FV and patient outcomes in our very limited analysis of PROs after PAO, and only 5% of patients with excessive FV (>20°) required subsequent femoral derotational osteotomy, suggesting that in a majority of patients with hip dysplasia, FV may not impact the post-operative clinical course.

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.

Fast and automatic periacetabular osteotomy fragment pose estimation using intraoperatively implanted fiducials and single-view fluoroscopy

Accurate and consistent mental interpretation of fluoroscopy to determine the position and orientation of acetabular bone fragments in 3D space is difficult. We propose a computer assisted approach that uses a single fluoroscopic view and quickly reports the pose of an acetabular fragment without any user input or initialization. Intraoperatively, but prior to any osteotomies, two constellations of metallic ball-bearings (BBs) are injected into the wing of a patient's ilium and lateral superior pubic ramus. One constellation is located on the expected acetabular fragment, and the other is located on the remaining, larger, pelvis fragment. The 3D locations of each BB are reconstructed using three fluoroscopic views and 2D/3D registrations to a preoperative CT scan of the pelvis. The relative pose of the fragment is established by estimating the movement of the two BB constellations using a single fluoroscopic view taken after osteotomy and fragment relocation. BB detection and inter-view correspondences are automatically computed throughout the processing pipeline. The proposed method was evaluated on a multitude of fluoroscopic images collected from six cadaveric surgeries performed bilaterally on three specimens. Mean fragment rotation error was 2.4 ± 1.0 degrees, mean translation error was 2.1 ± 0.6 mm, and mean 3D lateral center edge angle error was 1.0 ± 0.5 degrees. The average runtime of the single-view pose estimation was 0.7 ± 0.2 s. The proposed method demonstrates accuracy similar to other state of the art systems which require optical tracking systems or multiple-view 2D/3D registrations with manual input. The errors reported on fragment poses and lateral center edge angles are within the margins required for accurate intraoperative evaluation of femoral head coverage.

Circumferential Labral Reconstruction for Irreparable Labral Tears in the Primary Setting: Minimum 2-Year Outcomes With a Nested Matched-Pair Labral Repair Control Group

PURPOSE

(1) To report minimum 2-year patient-reported outcome (PRO) scores of primary circumferential acetabular labral reconstruction using anterior tibialis allograft and the knotless pull-through technique in the setting of femoroacetabular impingement syndrome (FAIS) and irreparable labral tears and (2) to compare these PROs with a matched-pair primary labral repair group.

METHODS

Data were prospectively collected and retrospectively reviewed. Patients were included if they underwent primary circumferential labral reconstruction with anterior tibialis tendon allograft during February 2016 to April 2017 for irreparable labral tears and FAIS and had preoperative and minimum 2-year follow-up for modified Harris Hip Score (mHHS), Hip Outcome Score-Sport-Specific Subscale, Non-arthritic Hip Score, International Hip Outcome Tool 12 (iHOT-12), 12-Item Short Form Health Survey physical component and mental component, Veterans RAND 12-Item Health Survey physical component and mental component, and visual analog scale for pain. The exclusion criteria were previous ipsilateral hip conditions or surgical procedures, Tönnis grade 2 or higher, or dysplasia (lateral center-edge angle ≤ 18°). Labral tears were considered irreparable if the labrum appeared (1) to be mostly or completely calcified and (2) to be inadequate (nonviable) and not amenable for labral repair. The reconstruction group was matched 1:3 based on age, sex, and body mass index to a benchmark control group of hips undergoing labral repair from the same period. The minimal clinically important difference and patient acceptable symptomatic state for the mHHS and iHOT-12 score were calculated.

RESULTS

A total of 37 hips (37 patients) underwent circumferential labral reconstruction. There were 19 female patients (51.4%) and 18 male patients (48.6%). The mean age was 45.6 ± 11.6 years, and the average body mass index was 27.1 ± 5. At minimum 2-year follow-up, the circumferential labral reconstruction group showed statistically significant improvements in the mHHS, Non-arthritic Hip Score, Hip Outcome Score-Sport-Specific Subscale, iHOT-12 score, and visual analog scale score. All hips in the reconstruction group were successfully matched to 111 labral repair hips. At latest follow-up, improvements in all PROs between the 2 groups were comparable. The revision rates were 0% and 3.6% in the reconstruction and repair groups, respectively.

CONCLUSIONS

After primary hip arthroscopy, primary circumferential labral reconstruction using anterior tibialis allograft and the knotless pull-through technique in the setting of FAIS and irreparable labral tears resulted in significant improvements in several PROs at minimum 2-year follow-up and high patient satisfaction. Primary circumferential labral reconstruction reached comparable functional outcomes to those of a benchmark matched-pair primary labral repair control group.

LEVEL OF EVIDENCE

Level III, case-control study.

The Use of Bovine Xenogeneic Bone Graft for Dega Pelvic Osteotomy in Children with Hip Dysplasia: A Retrospective Study of 147 Treated Hips

Backgrounds: Dega pelvic osteotomy is commonly used to correct acetabular dysplasia in children with open triradiate cartilage. The use of bovine xenogeneic bone graft (Tutobone^®) for Dega osteotomy has not been reported so far. This study aimed to determine the clinical and radiological outcome in a large series of children with hip dysplasia who were treated by Dega osteotomy using a bovine xenogeneic block for stabilisation. Methods: A retrospective, single-centre study was conducted including 101 patients (147 hips) with different underlying diseases. The acetabular angle of Hilgenreiner (AA) and the lateral center-edge angle (LCA) were analysed to quantify the correction of acetabular indices. Graft incorporation was assessed using the Goldberg scoring system. Results: the mean preoperative AA improved from 28.1 (SD: 6.7) to 14.7 (SD: 5.1) after surgery (p < 0.001). The mean preoperative LCA improved from 9.9 (SD: 6.7) to 21.8 (SD: 6.8) postoperatively (p < 0.001). Both indices remained stable at the one-year follow-up examination. Graft incorporation was excellent with a mean Goldberg score of 6.6. Heterotopic ossification occurred in one hip without clinical relevance. Graft-related complications were not noted. Conclusions: Dega osteotomy using Tutobone^® is safe and effective in the treatment of acetabular dysplasia in children independent of the underlying disease.

Ottawa classification for symptomatic acetabular dysplasia assessment of interobserver and intraobserver reliability

Aims

The aim of the current study was to assess the reliability of the Ottawa classification for symptomatic acetabular dysplasia.

Methods

In all, 134 consecutive hips that underwent periacetabular osteotomy were categorized using a validated software (Hip2Norm) into four categories of normal, lateral/global, anterior, or posterior. A total of 74 cases were selected for reliability analysis, and these included 44 dysplastic and 30 normal hips. A group of six blinded fellowship-trained raters, provided with the classification system, looked at these radiographs at two separate timepoints to classify the hips using standard radiological measurements. Thereafter, a consensus meeting was held where a modified flow diagram was devised, before a third reading by four raters using a separate set of 74 radiographs took place.

Results

Intrarater results per surgeon between Time 1 and Time 2 showed substantial to almost perfect agreement among the raters (κappa = 0.416 to 0.873). With respect to inter-rater reliability, at Time 1 and Time 2 there was substantial agreement overall between all surgeons (Time 1 κappa = 0.619; Time 2 κappa = 0.623). Posterior and anterior rating categories had moderate and fair agreement at Time 1 (posterior κappa = 0.557; anterior κappa = 0.438) and Time 2 (posterior κappa = 0.506; anterior κappa = 0.250), respectively. At Time 3, overall reliability (κappa = 0.687) and posterior and anterior reliability (posterior κappa = 0.579; anterior κappa = 0.521) improved from Time 1 and Time 2.

Conclusion

The Ottawa classification system provides a reliable way to identify three categories of acetabular dysplasia that are well-aligned with surgical management. The term ‘borderline dysplasia’ should no longer be used.

Cite this article: Bone Joint Res. 2020;9(5):242–249.

The neoacetabulum in developmental dysplasia of the hip is covered with hyaline cartilage

The lack of adequate mechanical stimulation and appropriate contact between acetabulum and femoral head results with developmental dysplasia of the hip (DDH). In DDH, hip joint forms normally during the organogenesis, but deforms during the fetal development. Acetabulum remains comparable in width with normal acetabulum, but has increased length and decreased depth, resulting in a poor coverage of the femoral head. In cases of severe hip subluxation and luxation due to DDH, the femoral head articulates with the external side of the iliac bone, forming a neoacetabulum in the position that was genetically predetermined to become bony tissue. A neoacetabulum is therefore formed under intermittent mechanical pressure, but never has the depth of a physiological acetabulum due to different forces at this new location. Over time, the depth of the neoacetabulum increases, and a crest is formed that obstructs reposition of the femoral head into the anatomic acetabulum. We hypothesize that the neoacetabulum on the iliac bone in DDH patients is formed of hyaline cartilage, despite the lack of genetic predisposition for hyaline cartilage formation in this area. We assume that as the femoral head migrates during development in such patients, joint capsular tissue interposes between the external side of the iliac bone and the femoral head, and a cartilaginous metaplasia of the capsule follows. This results in elongation of the acetabular cartilage in the same direction as the femoral head migrated. This assumption is based on the finding that in patients with hip luxation such interposed joint capsule showed signs of cartilaginous transformation. Furthermore, in the inner part of such joint capsules, proteoglycan production was notably higher than that of other non-cartilaginous tissue. Also, high expression of cartilaginous genes, which are usually not expressed in this tissue, was observed. Confirmation of this hypothesis would put a new perspective on the pathogenesis of DDH and could lead to better management or even prevention of this condition.

Modified lateralized head sign: An accurate marker in diagnosing adult hip dysplasia

BACKGROUND

Although lateralized head sign (LHS) is considered indicative of structural instability, it lacks reproducibility, and its usefulness in diagnosing adult hip dysplasia is unknown. In this study, we proposed a modified LHS and aimed to determine its reliability and accuracy in diagnosing adult hip dysplasia.

METHODS

We reviewed anteroposterior pelvic radiographs of 94 patients (134 hips) with hip dysplasia. As controls, 133 normal hips were evaluated. We defined the modified lateralization distance (LD) as the horizontal distance between the medial aspect of the femoral head to the acetabular fossa. The sensitivity, specificity, and cutoff value of modified LD in diagnosing hip dysplasia were calculated using receiver operating characteristic curve analysis.

RESULTS

The sensitivity and specificity of the modified LD (79% and 87%, respectively) were higher than those of the conventional LD (63% and 80%, respectively). Diagnostic accuracy was further improved when patients were divided on the basis of sex. The sensitivity and specificity of the modified LD in men were 89% and 97%, respectively, with a cutoff value of 12 mm, while in women, they were 80% and 96%, respectively, with a cutoff value of 9.7 mm. Therefore, we defined the modified LHS as presentation with a modified LD ≥ 12 mm in men and ≥10 mm in women. Between three observers, the kappa value for intraobserver reliability was ≥0.9, while that for interobserver reliability was >0.8. The mean sensitivity and specificity of the modified LHS in diagnosing hip dysplasia were 85% and 99%, respectively.

CONCLUSIONS

Modified LHS-a horizontal distance between the medial aspect of the femoral head and the acetabular fossa ≥12 mm in men and ≥10 mm in women-is a clinically useful marker in detecting lateral femoral head subluxation indicative of hip dysplasia or structural hip instability.

Periacetabular osteotomy for hip dysplasia treatment through a mini-invasive technique. Our results at mid-term in 131 cases

BACKGROUND AND OBJECTIVE

Periacetabular osteotomy (PAO) is an accepted and worldwide technique recognized for residual dysplasia treatment and even in unstable hips with limited acetabular coverage. The aim of this study is to analyse the functional, radiological and complication results in patients treated with mini-invasive PAO.

MATERIAL AND METHODS

We performed a retrospective study in which we analysed 131 cases undergoing mini-invasive PAO at our centre. The degree of joint degeneration was evaluated with Tönnis scale, Wiberg angle, acetabular index (AI), anterior coverage angle (AC), joint space, complications and functional outcome with the Non-Arthritic Hip Score (NAHS) were analysed preoperatively and at the end of follow-up.

RESULTS

The average age was 32.3±9.5 (SD) years, 102 (77.9%) were female and 29 (22.1%) were male. 7.7±2.8 (SD) years follow up. The radiological parameters improved between the pre-surgical phase and the end of follow-up, Wiberg angle+18.5° (18.3° versus 36.8°, 95% CI 17.3 to 19.7), AC angle+13.5° (26.2° versus 39.7°, 95%CI 11.6 to 15.4) and the AI -11.1° (19.5° versus 8.4°; 95%CI -12.1 to -10,1). In addition, the functional results, with the NAHS scale, improved+31.3 points (60.7 pre-surgical versus 92 at the end of follow-up, 95% CI 28.7 to 33.8). The most common complication was transient lateral femoral cutaneous nerve hypoaesthesia in 10 cases (7%).

CONCLUSION

The mini-invasive PAO approach is a reproducible technique, it allows restoration of acetabular coverage and provides an improvement in functional scales as confirmed by our series.

Sleep quality and nocturnal pain in patients with femoroacetabular impingement and acetabular dysplasia

Background

Femoroacetabular impingement (FAI) syndrome and acetabular dysplasia (AD) are common pathologies that lead to pain in the young adult hip. Nocturnal pain in these patients is often reported, yet little is known regarding the effect of these hip pathologies on overall sleep quality. The purpose of this study was to evaluate sleep quality in patients with AD and FAI syndrome.

Methods

This cross-sectional study consisted of 115 patients who complained of hip pain secondary to either FAI syndrome or AD. One hundred fifteen patients with hip pain secondary to FAI syndrome and AD were assessed using the Hip Outcome Score (HOS), Modified Harris Hip Score (mHHS), and then Hip disability and Osteoarthritis Outcome Score (HOOS). Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI). Multiple linear regression, with adaptive LASSO variable selection, was used to assess factors associated with sleep quality.

Results

Of the 115 patients, 62 had a diagnosis of FAI syndrome and 53 with AD. The mean age was 34.55 ± 11.66 (age range: 14 to 58 years), 76.52% had an ASA classification of 1 (ASA range: 1 to 3), and all Tonnis grades were either 0 or 1. The mean PSQI global score for all patients was 8.46 ± 4.35 (PSQI range: 0 to 21), indicating poor sleep quality. The adaptive LASSO-penalized least squares multiple linear regression revealed that HOOS Pain, SF-12 Role Emotional, and SF-12 Mental Health significantly predicted Sleep Quality (Adjusted R2 = 0.4041). Sleep quality improved as pain, emotional problems, and mental health improved.

Conclusion

Patients with symptomatic FAI syndrome and AD have poor sleep quality. Worsening pain from a patient’s hip pathology is associated with poor sleep, even prior to the onset of osteoarthrosis of the hip. Patients presenting with hip pain from FAI syndrome and AD should be screened for sleep disturbance and may benefit from a multidisciplinary treatment approach.

Assessment of Disability Related to Hip Dysplasia Using Objective Measures of Physical Performance

Background:

Lower extremity physical performance measures (PPMs), which can objectively quantify functional ability, are an attractive adjuvant to patient-reported outcome (PRO) instruments. However, few tests have been validated for use in hip instability.

Purpose:

To evaluate 4 different PPMs for their ability to differentiate between young adults with hip dysplasia indicated for treatment with periacetabular osteotomy (PAO) and asymptomatic controls and to test inter- and intratest reliability and relationship with popular hip PRO instruments.

Study Design:

Cohort study (diagnosis); Level of evidence, 2.

Methods:

A total of 24 symptomatic patients aged 15 to 39 years (100% female) with hip dysplasia (lateral center-edge angle <25°) indicated for treatment with PAO completed the visual analog scale (VAS) for pain, Hip disability and Osteoarthritis Outcome (HOOS) Pain subscale, HOOS Short Version (HOOS PS), International Hip Outcome Tool Short Version (iHOT-12), modified Harris Hip Score (mHHS), Patient Reported Outcome Measurement Information System (PROMIS) physical function (PF) and pain interference (PI), and 4 physical function tests: (1) self-selected walking speed (SSWS), sit-to-stand 5 times (STS5), (3) 4-square step test (FSST), and (4) timed stair ascent (TSA). A further 21 young, asymptomatic adults aged 18 to 39 years (91% female) also underwent testing. Between-group comparisons were made with unpaired t test with Bonferroni-Holm correction. Inter- and intrarater reliability was assessed in 38 participants by repeating PPMs at a second visit and using 2 raters. Spearman rank correlation coefficients were used to determine associations between PPMs and PRO instruments.

Results:

Significant differences between patients with hip dysplasia and controls were observed for all PRO instruments (HOOS Pain, 47.8 vs 99.2; HOOS PS, 61.9 vs 99.2; iHOT-12, 32.2 vs 99.2; mHHS, 54.5 vs 90.6; PROMIS PF, 41.4 vs 65.6; and PROMIS PI, 62.0 vs 39.1 [all P < .001]), and all PPMs (SSWS, 1.21 vs 1.53 m/s; STS5, 10.85 vs 5.95 s; FSST, 6.59 vs 4.03 s [all P < .001]; and TSA, 4.58 vs 3.29 s [P = .002]). All 4 PPMs demonstrated excellent intra- and intertest reliability (intraclass correlation coefficient, 0.83-0.99). STS5, FSST, and TSA were correlated highly (r > 0.5) with physical function PRO instruments, including PROMIS PF, mHHS, and iHOT-12.

Conclusion:

Patients with symptomatic hip dysplasia demonstrated significant impairment on functional testing compared with asymptomatic controls, and performance measure testing demonstrated excellent test-retest reliability. Timed stair ascent and sit-to-stand testing in particular were correlated strongly with physical function PRO instruments. PPMs may be a viable and well-received adjuvant to PRO instrument administration for patients with nonarthritic hip conditions, and investigation of the ability of PPMs to assess surgical outcomes for hip dysplasia is warranted.

PROMIS Versus Legacy Patient-Reported Outcome Measures in Patients Undergoing Surgical Treatment for Symptomatic Acetabular Dysplasia

BACKGROUND

No previous study has investigated how the Patient-Reported Outcomes Measurement Information System (PROMIS) performs compared with legacy patient-reported outcome measures in patients with symptomatic acetabular dysplasia treated with periacetabular osteotomy (PAO).

PURPOSE

To (1) measure the strength of correlation between the PROMIS and legacy outcome measures and (2) assess floor and ceiling effects of the PROMIS and legacy outcome measures in patients treated with PAO for symptomatic acetabular dysplasia.

STUDY DESIGN

Cohort study (Diagnosis); Level of evidence, 2.

METHODS

This study included 220 patients who underwent PAO for the treatment of symptomatic acetabular dysplasia. Outcome measures included the Hip disability and Osteoarthritis Outcome Score (HOOS) pain, HOOS activities of daily living (ADL), modified Harris Hip Score (mHHS), PROMIS pain, and PROMIS physical function subsets, with scores collected preoperatively and/or postoperatively at a minimum 12-month follow-up. The change in mean scores from preoperatively to postoperatively was calculated only in a subgroup of 57 patients with scores at both time points. Distributions of the PROMIS and legacy scores were compared to evaluate floor and ceiling effects, and Pearson correlation coefficients were calculated to evaluate agreement.

RESULTS

The mean age at the time of surgery was 27.7 years, and 83.6% were female. The mean follow-up time was 1.5 years. Preoperatively, neither the PROMIS nor the legacy measures showed significant floor or ceiling effects. Postoperatively, all legacy measures showed significant ceiling effects, with 15% of patients with a maximum HOOS pain score of 100, 29% with a HOOS ADL score of 100, and 21% with an mHHS score of 100. The PROMIS and legacy instruments showed good agreement preoperatively and postoperatively. The PROMIS pain had a moderate to strong negative correlation with the HOOS pain (r = -0.66; P < .0001) and mHHS (r = -0.60; P < .0001) preoperatively and the HOOS pain (r = -0.64; P < .0001) and mHHS (r = -0.64; P < .0001) postoperatively. The PROMIS physical function had a moderate positive correlation with the HOOS ADL (r = 0.51; P < .0001) and mHHS (r = 0.49; P < .0001) preoperatively and a stronger correlation postoperatively with the HOOS ADL (r = 0.56; P < .0001) and mHHS (r = 0.56; P < .0001).

CONCLUSION

We found good agreement between PROMIS and legacy scores preoperatively and postoperatively. PROMIS scores were largely normally distributed, demonstrating an expanded ability to capture variability in patients with improved outcomes after treatment.

Developmental Dysplasia of the Hip in Adolescents and Young Adults

Developmental dysplasia of the hip (DDH) in adolescents and young adults can cause notable pain and dysfunction and is a leading cause of progressive hip osteoarthritis in affected patients. Recognition of the clinical symptoms and radiographic presentation of DDH in adolescents and young adults are paramount for early management. Plain radiographs are critical for making proper diagnosis, whereas three-dimensional imaging including MRI and/or CT detects intra-articular pathology and better characterizes hip morphology. Management of early, symptomatic DDH includes nonsurgical modalities and open joint preservation techniques. Arthroscopic management can be used as an adjunct for symptomatic treatment and for addressing intra-articular pathology, but it alone does not correct the underlying osseous dysplasia and associated instability. The periacetabular osteotomy has become the mainstay of efforts to redirect the acetabulum and preserve the articular integrity of the hip; however, the proximal femur is also a potential source of pathology that should be considered. Open hip procedures are technically demanding yet provide the opportunity for pain relief, improved function, and preservation of the hip joint.

Diagnostic sensitivity and specificity of dynamic three-dimensional CT analysis in detection of cam and pincer type femoroacetabular impingement

Background

Cam and pincer-type morphologies can cause femoroacetabular impingement syndrome (FAI) and can be measured on plain radiographs using the alpha angle and the center edge angle. As an addition to plain radiographs and to assess femoroacetabular impingement, it is possible to visualize the interplay of the acetabular and femoral morphology by means of dynamic three-dimensional simulation of hip joint. Therefore, the objective of this study is to compare alpha angles and center edge angles on plain radiographs with the dynamic computerized tomography (CT) analysis in patients with complaints of femoroacetabular impingement.

Methods

All patients from our prospective cohort from 2012 to 2015 who underwent radiographs and a dynamic CT analysis for FAI were selected. Cam type morphologies were measured with the alpha angle and pincer type morphologies with lateral center-edge angle on radiographs and with CT analysis. The dynamic CT analysis also calculated position and size of impingement of femur and acetabulum. Intra-operative assessment was used to confirm impingement. Sensitivity, specificity and predictive values were calculated compared with respect to the intra-operative assessment.

Results

A total of 127 patients were included. 90 cam morphologies and 45 pincer morphologies were identified intra-operatively.

The sensitivity and specificity for cam morphology measured with radiographs was 84 and 72% compared to 90 and 43% with three dimensional dynamic analyses. The sensitivity and specificity for pincer morphology measured with radiographs was 82 and 39% compared to 84 and 51% with three dimensional dynamic analyses.

Conclusions

Diagnostic accuracy is comparable in three-dimensional dynamic analysis of CT scans and radiographs representing FAI caused by cam or pincer type morphology.

Level of evidence

IV

Gait kinematics of the hip, pelvis, and trunk associated with external hip adduction moment in patients with secondary hip osteoarthritis: toward determination of the key point in gait modification

Background

A larger daily cumulative hip loading, which is the product of the external hip adduction moment (HAM) impulse during gait and the number of steps per day has been identified as a factor associated with the progression of secondary hip osteoarthritis (OA). The cause of the increased HAM impulse in patients with hip OA has not been identified. The purpose of this study was to identify the gait parameters associated with HAM impulse during gait in patients with secondary hip OA.

Methods

Fifty-five patients (age 22–65 years) with mild-to-moderate secondary hip OA participated in this cross-sectional study. The HAM impulse during gait was measured using a three-dimensional gait analysis system. To identify the gait parameters associated with HAM impulse, hierarchical multiple regression analysis was performed. The first model (basic model) included body weight and stance phase duration. The second models included gait parameters (gait speed; ground reaction force [GRF] in frontal plane; and hip, pelvic, and trunk angle in frontal plane) and hip pain in addition to the basic model.

Results

Body weight and stance phase duration explained 61% of the variance in HAM impulse. In the second model, which took into account body weight and stance phase duration, hip adduction angle (9.4%), pelvic tilt (6.5%), and trunk lean (3.2%) in addition to GRF explained the variance in the HAM impulse. Whereas larger hip adduction angle and pelvic tilt toward the swing limb were associated with a larger HAM impulse, larger trunk lean toward the stance limb was associated with smaller HAM impulse.

Conclusion

In patients with excessive hip adduction and pelvic tilt toward the swing limb during gait, gait modification may contribute to the reduction of hip joint loading.

Regional muscle changes in adult dysfunctional hip conditions of femoroacetabular impingement and hip dysplasia

OBJECTIVE

To analyze regional muscle CT density and bulk in femoroacetabular impingement (FAI) and hip dysplasia (HD) versus controls.

MATERIALS AND METHODS

Patients who obtained perioperative CT imaging for FAI and HD before surgery were retrospectively studied. Asymptomatic controls included for comparison. Two readers independently evaluated regional hip muscle [iliopsoas (IP), rectus femoris (RF), gluteus minimus (Gm), and medius (GM)] density, muscle area, and muscle circumference. Inter-observer reliability calculated using intra-class correlation coefficient (ICC).

RESULTS

A consecutive series of 25 FAI patients, 16 HD patients, and 38 controls were recruited in the study. FAI patients had significantly greater Gm and GM circumferences as well as greater RF and IP areas on the normal side compared to the asymptomatic control group (p values 0.004, 0.032, 0.033, and 0.028, respectively). In addition, Gm and RF circumferences and RF area were significantly larger (p values 0.029, 0.036, and 0.014, respectively) in FAI patients on the affected side compared to the control group. HD patients had significantly smaller Gm and GM circumferences on the affected side than normal side measurements in FAI group (p values 0.043 and 0.003, respectively). Normal side GM circumference was also smaller in HD patients than normal side FAI hips (p value 0.02). There was no significant difference between the measurements on normal and abnormal sides in each disease group. No significant difference was found between measurements of HD compared to controls (p > 0.05). No muscle density differences were seen among different groups. There was moderate to excellent inter-reader reliability for all measurements except Gm muscle density.

CONCLUSIONS

Muscle analysis was able to quantify differences among patients with FAI, HD, and asymptomatic controls. These changes could indicate either a muscle imbalance contributing to the pathology or disuse atrophy, which may have implications for specific muscle-strengthening therapies and rehabilitation procedures in such patients.

Intraoperative evaluation of acetabular cup position during anterior approach total hip arthroplasty: are we accurately interpreting?

INTRODUCTION

Intraoperative radiographic evaluation during total hip arthroplasty (THA) has shown to improve the accuracy of acetabular component placement, however, differences in interpretation based on radiographic technique has not been established. This study aims to determine if differences exist in the interpretation of acetabular component abduction and anteversion between different radiographic projections.

METHODS

55 consecutive direct anterior THAs in 49 patients were prospectively enrolled. Target anteversion and abduction was defined by the Lewinnek zone. Fluoroscopy was used to direct acetabular component placement intraoperatively. After final cup implantation, fluoroscopic posterior-anterior hip and pelvis images were obtained for analysis. After completion of the procedure, an anterior-posterior plain pelvis radiograph was obtained in the operating room. Acetabulum component abduction and anteversion were postoperatively determined using specialised software on each of the 3 image acquisition methods.

RESULTS

Average acetabular cup abduction for intraoperative fluoroscopic posterior-anterior hip (FH), intraoperative fluoroscopic posterior-anterior pelvis (FP), and postoperative, standard, anteroposterior pelvis radiographs (PP) was 40.95° ± 2.87°, 38.87° ± 3.82° and 41.73° ± 2.96° respectively. The fluoroscopic hip and fluoroscopic pelvis tended to underestimate acetabular cup abduction compared to the postoperative pelvis (p < 0.001). Average acetabular cup anteversion for FH, FP, and PP was 19.89° ± 4.87°, 24.38° ± 5.31° and 13.36° ± 3.52° respectively. Both the fluoroscopic hip and fluoroscopic pelvis overestimated anteversion compared to the AP pelvis, with a 6.38° greater mean value measurement for FH (p < 0.001), and an 11° greater mean value measurement for FP (p < 0.001).

CONCLUSIONS

Fluoroscopic technique and differences between radiographic projections may result in discrepancies in component position interpretation. Our results support the use of the fluoroscopic posterior-anterior hip as the choice fluoroscopic imaging technique.

What factors affect fluoroscopy use during Bernese periacetabular osteotomy for acetabular dysplasia?

Periacetabular osteotomy (PAO) is the treatment of choice for acetabular dysplasia in the skeletally mature. Little is known about factors affecting fluoroscopy use in PAO. Therefore, we strived to determine patient and surgery factors are associated with the amount of fluoroscopy time and radiation dose during PAO. We performed a retrospective review of 378 patients who underwent PAO between January 2012 and August 2017. The mean age was 21.7 years and 326 (86%) were females. A total of 85 patients underwent concomitant arthroscopy and 60 underwent open arthrotomy. We recorded fluoroscopy time in minutes and radiation dose area product (DAP) in mGy·m². Multivariate general linear modeling identified independent predictors of fluoroscopy time and radiation dose. Mean fluoroscopy time was 1.21 minutes and mean fluoroscopy DAP was 0.71 mGy·m². Multivariate predictors of increased fluoroscopy time were male gender (P = 0.001), surgeon (P < 0.001) and whether an arthroscopy was performed (P < 0.001). Multivariate predictors of increased fluoroscopy DAP were increased body mass index (BMI) (P = 0.001), surgeon (P < 0.001) and whether an arthroscopy was performed (P < 0.001). Patients undergoing hip arthroscopy concomitant to PAO are at higher risk of longer fluoroscopy time and higher radiation dose. Other factors affecting fluoroscopy time included male gender and surgeon, while radiation dose was further affected by surgeon and BMI. Our findings can facilitate discussion about the risk of radiation exposure during PAO.

The borderline dysplastic hip: when and how is it abnormal?

Borderline acetabular dysplasia refers to mildly sub-normal patterns of acetabular shape and coverage that might predispose children to mechanical dysfunction and instability. Borderline dysplasia generally includes children with a lateral center edge angle (CEA) of 18-24°. Some children with borderline radiographic measurements have normal joint mechanics and function while others benefit from acetabular reorienting surgery. Although radiographic findings of borderline dysplasia might suggest instability, the ultimate diagnosis is based on history and physical exam in addition to imaging. Children with borderline acetabular dysplasia sometimes benefit from other cross-sectional imaging studies such as MR imaging to evaluate for secondary evidence of instability, including damage along the acetabular rim, or labral degeneration and hypertrophy. CT is also helpful for depiction of 3-D acetabular morphology for preoperative assessment and planning. Pediatric radiologists are often the first to identify borderline or mild dysplasia on radiographs. It is imperative that pediatric radiologists serve as effective consultants and offer appropriate recommendations as part of a cohesive multidisciplinary approach to this complex patient population.

Understanding Painful Hip in Young Adults: A Review Article

A wide number of disorders, including pathologies outside the hip, can cause and refer pain to hip. However, determining the cause of a painful hip can be a major challenge to orthopedic surgeons. Failure to diagnose and appropriately investigate pathologies of the hip in adults may result in delayed management and prolonged patient morbidity. A systematic approach to investigating the etiology of hip pain in adults (e.g., history, careful clinical and radiographic examination), will help identify the majority of clinically important pathologies which can cause hip pain. Conservative treatment and selective use of injection therapies has proven quite successful for the treatment of most causes of hip pain.

Evaluating and managing acetabular dysplasia in adolescents and young adults

Hip dysplasia is a developmental deformity in which abnormal acetabular or proximal femoral growth causes structural instability of the hip joint due to inadequate bony coverage of the acetabulum over the femoral head. Skeletally mature adolescents or young adults with underlying acetabular dysplasia may present with activity-related groin or lateral hip pain and a limp. This article reviews the current understanding of the disease and better treatment options for correcting acetabular dysplasia in symptomatic adolescents and young adults before secondary osteoarthritis develops.

Gender and disease severity determine proximal femoral morphology in developmental dysplasia of the hip

In this computed tomography (CT) morphological study we describe the way the proximal femoral morphology differs with worsening degrees of developmental dysplasia of the hip (DDH) and describe gender differences in patients with DDH. Forty-nine male patients with DDH were matched with 49 females with DDH, using age and the Crowe classification of DDH severity. The femoral length, anteversion, neck-shaft angle, offset, neck length, canal-calcar ratio, canal flare index, lateral center-edge angle, alpha angle, pelvic tilt, and pelvic incidence were measured for each patient on their pre-operative CT scans, prior to total hip arthroplasty surgery. Femoral anteversion and neck length were 16° and 47 mm, 25°and 36 mm, 26° and 43 mm, and 44° and 36 mm, for Crowe I and III males and Crowe I and III females, respectively. The mean male anteversion was 22° (±14), compared to 30° (±15.5) in females (p = 0.02, Confidence Interval: 1.6-14.9). Gender differences in femoral length, neck length and offset lost significance when height-normalized and no other significant gender differences were found. In conclusion, femoral neck length reduces with increasing DDH severity, whilst anteversion tends to increase. Male patients with DDH have significantly less femoral anteversion, which has important implications for osteotomy and arthroplasty surgery in DDH. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Osteoarthritis

Osteoarthritis is a leading cause of disability and source of societal cost in older adults. With an ageing and increasingly obese population, this syndrome is becoming even more prevalent than in previous decades. In recent years, we have gained important insights into the cause and pathogenesis of pain in osteoarthritis. The diagnosis of osteoarthritis is clinically based despite the widespread overuse of imaging methods. Management should be tailored to the presenting individual and focus on core treatments, including self-management and education, exercise, and weight loss as relevant. Surgery should be reserved for those that have not responded appropriately to less invasive methods. Prevention and disease modification are areas being targeted by various research endeavours, which have indicated great potential thus far. This narrative Seminar provides an update on the pathogenesis, diagnosis, management, and future research on osteoarthritis for a clinical audience.

Protein biomarkers in serum and urine for determining presence or absence of hip dysplasia in a canine model

This study compares serum and urine concentrations of relevant protein biomarkers among adult dogs with or without radiographic canine hip dysplasia (CHD). Adult (≥2 years of age), client-owned dogs (n = 74) radiographically categorized as having at least "good" hips (n = 49) or having "mild," "moderate," or "severe" hip dysplasia (n = 25) by the Orthopedic Foundation for Animals (OFA). Urine and serum samples were obtained from each dog at a single time-point and processed and analyzed for relevant protein biomarkers. Urinary concentrations of CTX-II (p < 0.001) and TIMP-1 (p = 0.002) were significantly lower in dogs with CHD compared to dogs with no CHD. ROC curve analyses were successful in establishing a panel of four biomarkers (urinary CTX-I and II, serum MMP-9, and serum PIICP) with high discriminatory capability for the presence or absence of hip dysplasia in adult dogs (AUC = 0.89). Urine and serum biomarkers can distinguish adult dogs with radiographic CHD from those with no CHD with a sensitivity of 0.95 and specificity of 0.77 using ROC analysis with AUC 0.89. Clinical Significance: This finding suggests that this simple, minimally invasive diagnostic technique has potential for discriminating dysplastic dogs from dogs with normal hips, with possible translational application to humans based on similar etiopathogenesis. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 9999:1-5, 2019.

The Addition of Hip Arthroscopy to Periacetabular Osteotomy Does Not Increase Complication Rates: A Prospective Case Series

BACKGROUND

Previous studies on periacetabular osteotomy (PAO) reported complication and reoperation rates of 5.9% and 10%, respectively. Hip arthroscopy is increasingly utilized as an adjunct procedure to PAO to precisely treat associated intra-articular pathology. The addition of this procedure has the potential of further increasing complication rates.

PURPOSE

To determine the rates of complication and reoperation of combined hip arthroscopy and PAO for the treatment of acetabular deformities and associated intra-articular lesions.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Using a prospective database, the authors retrospectively reviewed 248 hips (240 patients) that underwent combined hip arthroscopy and PAO between 2007 and 2016. Data were collected at scheduled follow-up visits at approximately 1 month, 3 to 4 months, and 1 and 2 years after surgery. Mean follow-up from surgery was 3 years (range, 1-8 years). A total of 220 PAOs were done for symptomatic acetabular dysplasia, 18 for symptomatic acetabular retroversion, and 10 for combined acetabular dysplasia and acetabular retroversion. Central compartment arthroscopy was performed for treatment of intra-articular chondrolabral pathology in all cases. Select cases underwent femoral head-neck junction osteochondroplasty either arthroscopically before the PAO or through an open approach after it. Complications were graded according to the modified Dindo-Clavien complication scheme, which was validated for hip preservation procedures. Reoperations (excluding hardware removal) were recorded.

RESULTS

Grade III complications occurred among 7 patients (3%) while there were no grade IV complications. Grade III complications included deep infection (n = 3), wound dehiscence (n = 1), hematoma requiring exploration (n = 1), symptomatic heterotopic ossification requiring excision (n = 1), and deep venous thrombosis (n = 1). There were 13 reoperations (5%), and 3 were repeat hip arthroscopy. Univariate Cox hazard models were used to estimate the relative risk factors for complication and reoperation. Increased age (per decade) showed over twice the increased likelihood for complications (hazard ratio, 2.5; 95% CI, 1.67-3.74). Also, preoperative diagnosis of acetabular retroversion, not acetabular dysplasia, showed >3 times the increased risk of reoperation (hazard ratio, 3.05; 95% CI, 1.41-6.61).

CONCLUSION

The rate of complications reported is comparable (3%) with previously published complication rates of PAO without hip arthroscopy. In this cohort, increasing age and diagnosis of acetabular retroversion were associated with higher complication and reoperation rates.

Statistical shape modeling of femur shape variability in female patients with hip dysplasia

Although increasing evidence suggests that abnormal femur geometry in developmental dysplasia of the hip (DDH) may contribute to intra-articular damage and the development of hip osteoarthritis, a comprehensive 3D description of femoral abnormalities in DDH remains incomplete. Statistical shape modeling (SSM) was used to quantify three-dimensional (3D) geometric variation among femurs in female patients with DDH and control subjects. SSM correspondence points (n = 8,192) were placed on each femur using a gradient descent energy function to derive mean DDH and control femoral shapes and principal component analysis (PCA) was then used to describe shape variation. PCA results were associated with common 2D radiographic measures of femur shape using general linear models. For patients with DDH, the first eight principal components (modes) captured 90.9% of the cumulative variance accounted for (VAF). Notably, mode 2 captured 23.6% VAF and described variation in femoral version, the neck-shaft angle, and femoral neck length, while mode 3 captured 16.4% VAF and described variation in femoral version, femoral head size, and femoral offset. SSM captured complex geometric deformities in DDH, which may not be fully described by 2D measures of the acetabulum and proximal femur alone. By determining the primary shape variations among femurs in cases of DDH, SSM may further understanding of pathologies on the femoral side of dysplastic hips, in context with more commonly recognized acetabular deformities. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Combined Lateral Osseolabral Coverage Is Normal in Hips With Acetabular Dysplasia

PURPOSE

To compare the lateral osseolabral coverage between groups of patients with different degrees of acetabular bony coverage using a magnetic resonance imaging parameter known as the combined lateral center-edge angle (cLCEA).

METHODS

The cLCEA was measured among a consecutive series of patients presenting to a dedicated hip preservation surgeon with a magnetic resonance imaging scan. The cLCEA was measured using a coronal T1 or proton density image and was defined as the angle subtended by (1) a line through the center of the femoral head and orthogonal to the transverse line passing through the teardrops of both hips and (2) an oblique line drawn from the center of the femoral head to the free edge of the lateral acetabular labrum. The average difference between the lateral center-edge angle (LCEA) and the cLCEA was calculated and compared between groups based on acetabular bony coverage: dysplasia (LCEA <20°), borderline dysplasia (LCEA 20°-24.9°), normal coverage (LCEA 25°-39.9°), and overcoverage (LCEA ≥40°).

RESULTS

In total, 341 patients (386 hips) were included. There were no significant differences in cLCEA between hips with normal acetabular coverage and dysplasia (P = .10) or borderline dysplasia (P = .46). Despite the large difference in mean LCEA between dysplasia (14.8° ± 3.9°) and acetabular overcoverage (43.1° ± 2.8°), the mean cLCEA values exhibited only a modest difference (44.7° ± 4.9° vs 52.7° ± 4.5°, respectively). Concordantly, hips with dysplasia exhibited the largest difference between mean LCEA and cLCEA (delta = 29.9° ± 4.7°) and hips with acetabular overcoverage had the smallest difference between measures (9.6° ± 5.2°).

CONCLUSIONS

With decreasing acetabular bony coverage, there is increasing labral size such that the total osseolabral coverage, measured by the combined LCEA, remains equivalent between hips with normal acetabular coverage versus dysplasia.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Outcomes of Hip Arthroscopy With Concomitant Periacetabular Osteotomy, Minimum 5-Year Follow-Up

PURPOSE

To report minimum 5-year follow-up results of concomitant hip arthroscopy followed by periacetabular osteotomy (PAO) to treat acetabular dysplasia and intra-articular pathology, such as femoroacetabular impingement syndrome and labral tears.

METHODS

Data were prospectively collected from October 2010 to December 2012. Patients were included in this study if they underwent concomitant hip arthroscopy and PAO and if they had preoperative scores documented for the following measures: modified Harris Hip Score (mHHS), Nonarthritic Hip Score (NAHS), Hip Outcome Score-Sports-Specific Subscale (HOS-SSS), and pain on a visual analog scale (VAS). Patients who underwent reverse PAO to address acetabular retroversion were excluded. Follow-up was considered complete with these outcomes collected after surgery, as well as the abbreviated International Hip Outcome Tool and patient satisfaction on a 0-10 scale. Significance was set at P = .05.

RESULTS

Sixteen patients were eligible, all of whom had complete follow-up at a minimum of 5 years after surgery. There were 13 female subjects. The average age of the patients was 23.5 ± 6.8 years (range, 12.3-35.3 years), and the average body mass index was 24.3 ± 5.6 (range, 14.8-34.2). The mean lateral center-edge angle increased from 14.2° to 31.8° (P < .0001), and the anterior center-edge angle increased from 11.9° to 28.6° (P < .0001). The Tönnis angle of acetabular inclination decreased from 19.3° to 2.6° (P < .0001). The alpha angle decreased from 55.7° to 41.0° (P < .0001). All preoperative radiographs were Tönnis ≤1, and there was no progression of arthritis in radiographs taken at the latest clinical visit. All patient-reported outcomes scores demonstrated significant improvement from preoperative baseline to the minimum 5-year follow-up scores (mHHS, P < .001; NAHS, P < .001; HOS-SSS, P = .001). The VAS score decreased from a preoperative mean of 5.8 to 3.1 at the latest follow-up (P = .007). No conversion to total hip arthroplasty was reported.

CONCLUSIONS

Concomitant hip arthroscopy and PAO appears to be a safe and effective procedure with favorable mid-term outcomes that are durable compared to the short-term.

LEVEL OF EVIDENCE

Level IV, case series.

Musculoskeletal models with generic and subject-specific geometry estimate different joint biomechanics in dysplastic hips

Optimizing the geometric complexity of musculoskeletal models is important for reliable yet feasible estimation of joint biomechanics. This study investigated the effects of subject-specific model geometry on hip joint reaction forces (JRFs) and muscle forces in patients with developmental dysplasia of the hip (DDH) and healthy controls. For nine DDH and nine control subjects, three models were created with increasingly subject-specific pelvis geometry, hip joint center locations and muscle attachments. Hip JRFs and muscle forces during a gait cycle were compared among the models. For DDH subjects, resultant JRFs from highly specific models including subject-specific pelvis geometry, joint locations and muscle attachments were not significantly different compared to models using generic geometry in early stance, but were significantly higher in late stance (p = 0.03). Estimates from moderately specific models using CT-informed scaling of generic pelvis geometry were not significantly different from low specificity models using generic geometry scaled with skin markers. For controls, resultant JRFs in early stance from highly specific models were significantly lower than moderate and low specificity models (p ≤ 0.02) with no significant differences in late stance. Inter-model JRF differences were larger for DDH subjects than controls. Inter-model differences for JRF components and muscle forces were similar to resultant JRFs. Incorporating subject-specific pelvis geometry significantly affects JRF and muscle force estimates in both DDH and control groups, which may be especially important for reliable estimation of pathomechanics in dysplastic hips.

Automatic hip geometric feature extraction in DXA imaging using regional random forest

BACKGROUND

Hip fracture is considered one of the salient disability factors across the global population. People with hip fractures are prone to become permanently disabled or die from complications. Although currently the premier determiner, bone mineral density has some notable limitations in terms of hip fracture risk assessment.

OBJECTIVES

To learn more about bone strength, hip geometric features (HGFs) can be collected. However, organizing a hip fracture risk study for a large population using a manual HGFs collection technique would be too arduous to be practical. Thus, an automatic HGFs extraction technique is needed.

METHOD

This paper presents an automated HGFs extraction technique using regional random forest. Regional random forest localizes landmark points from femur DXA images using local constraints of hip anatomy. The local region constraints make random forest robust to noise and increase its performance because it processes the least number of points and patches.

RESULTS

The proposed system achieved an overall accuracy of 96.22% and 95.87% on phantom data and real human scanned data respectively.

CONCLUSION

The proposed technique's ability to measure HGFs could be useful in research on the cause and facts of hip fracture and could help in the development of new guidelines for hip fracture risk assessment in the future. The technique will reduce workload and improve the use of X-ray devices.

Novel model for the induction of postnatal murine hip deformity

Acetabular dysplasia is a common, multi-etiological, pre-osteoarthritic (OA) feature that can lead to pain and instability of the young adult hip. Despite the clinical significance of acetabular dysplasia, there is a paucity of small animal models to investigate structural and functional changes that mediate morphology of the dysplastic hip and drive the subsequent OA cascade. Utilizing a novel murine model developed in our laboratory, this study investigated the role of surgically induced unilateral instability of the postnatal hip on the initiation and progression of acetabular dysplasia and impingement up to 8-weeks post-injury. C57BL6 mice were used to develop titrated levels of hip instability (i.e., mild, moderate, and severe instabillity or femoral head resection) at weaning. Joint shape, acetabular coverage, histomorphology, and statistical shape modeling were used to assess quality of the hip following 8 weeks of destabilization. Acetabular coverage was reduced following severe, but not moderate, instability. Moderate instability induced lateralization of the femur without dislocation, whereas severe instability led to complete dislocation and pseudoacetabulae formation. Mild instability did not result in morphological changes to the hip. Removal of the femoral head led to reduced hip joint space volume. These data support the notion that hip instability, driven by mechanical loss-of-function of soft connective tissue, can induce morphometric changes in the growing mouse hip. This work developed a new mouse model to study hip health in the murine adolescent hip and is a useful tool for investigating the mechanical and structural adaptations to hip instability during growth. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Upsloping lateral sourcil: a radiographic finding of hip instability

While radiographic findings of frank hip dysplasia are well defined, there is a lack of diagnostic criteria for patients with radiographically ‘normal’ hips who have borderline morphologic deficits and clinical instability. In this study, we aim to define and validate a new radiographic finding associated with hip instability known as the upsloping lateral sourcil (ULS). Patients (316) were reviewed for lateral center edge angles, generalized joint laxity assessed with the Beighton Hypermobility Score and the presence of the ULS. The ULS was defined as a caudal-to-cranial inclination of the middle-to-far lateral aspect of the acetabular sourcil with loss of the normal lateral acetabular concavity. The prevalence of the ULS correspondingly increased with the degree of under-coverage as defined by LCEA. Within the normal coverage group, hips with a ULS had smaller LCEAs than those without ULS (29° versus 32°, P < 0.001). Among hips with a ULS, 59.00% had generalized joint laxity. The association between the ULS finding and generalized joint laxity was statistically significant (P < 0.01). The ULS is seen with higher prevalence in patients with clinical hip laxity and radiographically decreasing LCEA and may serve as an adjunctive finding in patients presenting with hip pain and instability. The ULS may help to characterize patients with borderline hip dysplasia and laxity that fall outside conventional imaging criteria for dysplasia.

The 'low-volume acetabulum': dysplasia in disguise

Although there are well described radiological criteria for diagnosing DDH, our experience has highlighted that a new sub-category of hips exists in which the classic radiographic characteristics for DDH may be normal but the coverage of the femoral head is compromised. The purpose of this study was to validate a simple radiographic measurement method for calculating the depth of the acetabulum in order to detect individuals with 'low-volume' acetabuli and under-covered femoral heads. We identified 24 patients who were suspected of having low-volume acetabuli and compared their radiographs with those of 150 patients with non-dysplastic hips. The radiographic indices measured included the lateral center-edge (CE) angle, the anterior CE angle, the femoral neck-shaft angle, the extrusion index, integrity of the Shenton's line, the crossover sign, and ischial spine sign. We have developed a novel, but a simple method, named the 'coverage index' (CI) to identify the presence of a low-volume acetabulum on plain radiographs. Comparisons were made between the low-volume hips and the non-dysplastic hips. The radiographic parameters indicative of developmental dysplasia of the hip (DDH) were within normal limits in all patients with low-volume acetabuli and therefore these hips could not be classified as 'dysplastic' based on the traditional radiological parameters. There was no difference between the mean radius of the femoral head in two groups. The mean CI was significantly greater in the non-dysplastic group compared with the low-volume acetabula cohort (1.62 ± 0.117 in non-dysplastic group versus 1.07 ± 0.11 in low-volume hips) (P = 0.0001). Orthopaedic surgeons should be aware of a hip abnormality in which the femoral head coverage is deficient, yet all the conventional parameters for measuring coverage, including the center edge angle, are within normal limits. We have introduced a simple radiographic measurement method that may help surgeons identify these patients using the anteroposterior radiographs of the hip.

Concomitant Arthroscopy With Labral Reconstruction and Periacetabular Osteotomy for Hip Dysplasia

In the setting of true hip dysplasia, the high prevalence of intra-articular pathology may lead to recurrent symptoms and failure after periacetabular osteotomy (PAO). Femoral neck osteochondroplasty, microfracture, removal of loose bodies, and labral repair are examples of procedures that are performed with concomitant arthroscopy. When damage to the labrum is too severe to repair, reconstruction instead of extensive debridement before PAO can be more effective in restoring the labral seal to maintain joint lubrication and chondral protection. This Technical Note describes a method for concomitant hip arthroscopy with circumferential labral reconstruction with allograft and PAO.

Value of Computed Tomography-Based Three-Dimensional Pre-operative Planning in Cup Placement in Total Hip Arthroplasty With Dysplastic Acetabulum

Objects: To investigate the value of CT-based 3D templating software for pre-operative planning in patients with acetabular dysplasia undergoing total hip arthroplasty (THA) with a minimum follow-up of 2 years. Methods: We performed a retrospective review of a single surgeon's cohort of patients with Crowe I to III developmental dysplastic hip (49 hips in 41 patients) who underwent cementless primary THA and were available for follow-up at a mean of 2.7 years after THA. We analyzed the accuracy of cup size prediction, the reliability of pre- and post-operative cup orientation and position of reconstructed rotation center using CT-based 3D templating software. Post-operative Harris Hip Score and lower limb discrepancy was obtained at the last follow-up. Results: The sizes of 71% of the cup components (35/49) were estimated exactly, and 100% of the cup size estimates were accurate to within one-cup size. There was good reproducibility of pre- and post-operative position of reconstructed rotation center (correlation coefficient r = 0.396 for vertical position, p = 0.005; r = 0.326 for horizontal position, p = 0.024). There was no substantial agreement between the planned acetabular orientation and that measured post-operatively (correlation coefficient -0.174 for inclination and 0.045 for anteversion). There were 44 (90%) excellent or good results according to HHS. Seven patients (14%) reported lower limb discrepancy. Conclusions: Pre-operative CT-based 3D templating made it possible to predict accurate cup size and achieve reproducible cup position in patients with dysplastic acetabulum. The reproducibility of cup orientation could not be demonstrated in this study.

Reliability of and Correlation Between Measurements of Acetabular Morphology

The authors sought to determine the intra- and interrater reliability of contemporary measures of acetabular morphology among a group of hip surgeons and to determine the correlations between measures of acetabular morphology. On 2 separate occasions, 3 hip surgeons independently performed blinded evaluations of anteroposterior pelvic radiographs of 40 patients. The lateral center-edge angle, medial center-edge angle, acetabular arc, extrusion index, acetabular index, Sharp's angle, posterior wall sign, crossover sign, femoro-epiphyseal acetabular roof index, acetabular wall indexes, and delta angle were assessed. A linear mixed model was used for variance estimation, and kappa and intra-class correlation coefficients were assessed for reliability. Pearson correlation coefficients were calculated for all possible pairs of radiographic measures. The acetabular index had the greatest interrater agreement (0.90; 95% confidence interval [CI], 0.84-0.93), whereas the lateral center-edge angle had the higher intrarater agreement (0.96; 95% CI, 0.92-0.98). The acetabular arc angle had the lowest interrater agreement (0.44; 95% CI, 0.29-0.57), and the Sharp's angle had the lowest intrarater agreement (0.66; 95% CI, 0.41-0.84). The posterior wall sign had an interrater agreement of 0.35 (95% CI, 0.11-0.54) and an intrarater agreement of 0.68 (95% CI, 0.49-0.86). The crossover sign had an interrater agreement of 0.66 (95% CI, 0.43-0.84) and an intrarater agreement of 0.85 (95% CI, 0.52-0.89). The acetabular index, lateral center-edge angle, and extrusion index presented with high coefficients of correlation. In addition, acetabular anteversion correlated with severity of dysplasia. Commonly used parameters such as the acetabular index, lateral center-edge angle, and extrusion index are reliable radiographic parameters to assess acetabular morphology. However, correlation between measures suggests that they may be redundant in quantifying acetabular morphology. [Orthopedics. 2018; 41(5):e629-e635.].

Can Salter osteotomy correct late diagnosed hip dysplasia: A retrospective evaluation of 49 hips after 6.7 years?

BACKGROUND

Surgical treatment of late diagnosed development dysplasia of the hip (DDH) remains challenging with several methods being described. We therefore retrospectively evaluated the outcome of Salter innominate osteotomy (SIO) in patients with fully-grown bone, to evaluate whether this surgical procedure allows sufficient acetabular correction.

MATERIAL AND METHODS

Between 2004-2012 SIO had been performed in 45 patients (49 hips) with late diagnosed DDH. The evaluation included pre- and postoperative radiographs (n=49), the complication rate (n=49) and the clinical outcome (WOMAC, HHS, UCLA) (n=34).

RESULTS

Mean age at surgery was 27.6 (16-51) with a follow-up of 6.7±2.7 (0.9-11.0) years. Radiologically, a good acetabular correction with a significant improvement of the Center Edge angle (15.4° to 34.9°), sharps angle (45.7° to 32.0°) and migration percentage (33.2% to 14.4%) (p<0.001) was found. Clinical results revealed a WOMAC of 13.9±13.3, UCLA of 7.8±2.1 and HHS of 85.0±11.8. Complications were noted for 10 patients (20%) with 7 (14%) requiring revision.

CONCLUSION

The results demonstrated that SIO achieved a satisfying acetabular correction and good clinical results in late diagnosed DDH. It therefore might be an option in some cases, although periacetabular osteotomy techniques are currently preferable used as they allow a wider range of acetabular correction.

LEVEL OF EVIDENCE

IV, retrospective observational study.

Universal or selective ultrasound screening for developmental dysplasia of the hip? A discussion of the key issues

PURPOSE

To summarize recent developments and provide recommendations as to whether universal or selective programmes are advisable.

METHODS

A literature review was performed and preference given to studies with higher levels of evidence. All programmes reviewed included clinical screening.

RESULTS

Recent studies underline the need for high quality screening programmes to promote the early detection of developmental dysplasia of the hip (DDH). A small number of cases may be missed clinically but with universal ultrasound screening programmes the late presentation rates appear to be virtually zero. Contemporary studies show treatment rates with universal screening programmes which are now lower than those with selective ultrasound. There is little agreement over the criteria used for selective programmes. Alternative outcome measures, such as the first operation rate or the percentage undergoing major (open) surgery are both lowest with universal ultrasound screening programmes. Furthermore, a significant reduction in the rate of surgery for DDH later in life was seen after the introduction of universal ultrasound screening, whereas the defined criteria for selective screening may not detect the majority of patients who require late surgery. Abduction bracing with modern orthoses is associated with a zero rate of avascular necrosis (AVN), whereas closed reduction techniques have an overall risk of 10%.

CONCLUSION

On clinical grounds, if future studies confirm that hip abduction in flexible orthoses is not associated with AVN, it may be time for a paradigm shift of screening for DDH towards a universal ultrasound protocol. The costs associated both with each type of screening programme and with the management of late presenting cases are also important but may be secondary to clinical benefit.

The interface between periacetabular osteotomy, hip arthroscopy and total hip arthroplasty in the young adult hip

Hip pain is highly prevalent in both the younger and the elderly population. In older patients, pain arising from osteoarthritis (OA) is most frequent, whereas in younger patients, non-degenerative diseases are more often the cause of pain. The pain may be caused by hip dysplasia and femoroacetabular impingement (FAI).Abnormal mechanics of the hip are hypothesized by some authors to cause up to 80% of OA in the hip. Therefore, correction of these abnormalities is of obvious importance when treating young patients with hip pain.Hip dysplasia can be diagnosed by measuring a CE angle < 25° on a plain standing radiograph of the pelvis.Dysplastic or retroverted acetabulum with significant symptoms should receive a periacetabular osteotomy (PAO).FAI with significant symptoms should be treated by adequate resection and, if necessary, labrum surgery.If risk factors for poor outcome of joint-preserving surgery are present (age > 45 to 50 years, presence of OA, joint space < 3 mm or reduced range of motion), the patient should be offered a total hip arthroplasty (THA) instead of PAO.THA can be performed following PAO with outcomes similar to a primary THA.Hip arthroscopy is indicated in FAI (cam and pincer) and/or for labral tears. Cite this article: EFORT Open Rev 2018;3:408-417. DOI: 10.1302/2058-5241.3.170042.

Canine hip dysplasia: A natural animal model for human developmental dysplasia of the hip

Developmental dysplasia of the hip (DDH) in humans is a common condition that is associated with hip pain, functional limitations, and secondary osteoarthritis (OA). Surgical treatment of DDH has improved in the last decade, allowing excellent outcomes at short- and mid-term follow-up. Still, the etiology, mechanobiology, and pathology underlying this disease are not well understood. A pre-clinical animal model of DDH could help advance the field with a deeper understanding of specific pathways that initiate hip joint degeneration secondary to abnormal biomechanics. An animal model would also facilitate different interventional treatments that could be tested in a rigorous and controlled environment. The dog model exhibits several important characteristics that make it valuable as a pre-clinical animal model for human DDH. Dogs are naturally prone to develop canine hip dysplasia (CHD), which is treated in a similar manner as in humans. Comparable to human DDH, CHD is considered a pre-OA disease; if left untreated it will progress to OA. However, progression to OA is significantly faster in dogs than humans, with progression to OA within 1-2 years of age, associated with their shorter life span compared to humans. Animal studies could potentially reveal the underlying biochemical pathway(s), which can inform refined treatment modalities and provide opportunities for new treatment and prevention targets. Herein, we review the similarities and differences between the two species and outline the argument supporting CHD as an appropriate pre-clinical model of human DDH. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1807-1817, 2018.

Does Severity of Acetabular Dysplasia Influence Clinical Outcomes After Periacetabular Osteotomy?-A Case-Control Study

BACKGROUND

Detailed characterization of factors influencing post-periacetabular osteotomy (PAO) outcome could guide treatment offered.

METHODS

Using a prospective, multicenter database of PAOs, 61 hips/patients (51 females) with lesser dysplasia (acetabular index < 15° and lateral center-edge angle > 15°) were case-control matched for age, gender, body mass index, Tönnis grade, and joint congruency (P = .6-.9) with a "comparison group" of pronounced dysplasia (n = 183), aiming to assess whether severity of acetabular dysplasia has an effect on outcome following PAO and/or the ability to achieve desired acetabular correction.

RESULTS

At 4 ± 1.5 years, no differences in complication or reoperation rates were detected between the groups (P = .29). Lesser dysplastic hips had inferior Hip Disability and Osteoarthritis Outcome Score, both preoperatively (52 vs 59) and postoperatively (73 vs 78); however, similar improvements were seen. Among the lesser dysplastic hips, those that required a femoral osteochondroplasty at PAO had significantly inferior preoperative Hip Disability and Osteoarthritis Outcome Score (48 ± 18). Increased ability to achieve optimum correction was seen (80% vs 59%, P = .4) in lesser dysplasia.

CONCLUSION

A PAO is safe and efficacious in the treatment of lesser dysplasia. Further study on the identification of the optimum treatment modality for the mildly dysplastic hips with cam deformity is required.

Factors increasing risk of failure following hip arthroscopy: a case control study

We aimed to identify factors such as pre-arthroscopy and intra-operative variables that were associated with failure of hip arthroscopy as a joint preserving operation. We performed a retrospective analysis of a database containing 344 consecutive hip arthroscopies performed at our institution. Forty-four hips were identified that underwent a subsequent arthroplasty procedure following their hip arthroscopy (cases). Sixty-six control hips (hip arthroscopy with no subsequent arthroplasty) were randomly selected from the same database. Cases and controls were matched for age, sex and follow-up (P = 0.59, 0.48, 0.10, respectively). Pre-operative radiographs/MRI scans plus intra-operative findings were analysed to identify factors associated with failure. Both a lower centre edge angle and higher acetabular index on pre-operative radiographs were associated with higher rates of failure (P < 0.001). The presence of any acetabular wear at operation was also associated with failure (P < 0.001). Highest rates of failure were seen in hips with both features of dysplasia on pre-operative radiographs and any intra-operative acetabular wear (relative risk: 5, odds ratio: 9.13, P < 0.001). Dysplastic features on pre-operative radiographs and the finding of acetabular wear at hip arthroscopy increase the risk of subsequent arthroplasty. Identification of these features pre-operatively with evolving imaging techniques would improve the results of hip arthroscopy as joint preserving surgery.

Advanced Concepts in Hip Morphology, Associated Pathologies, and Specific Rehabilitation for Athletic Hip Injuries

Hip and groin injuries comprise up to 17% of athletic injuries and can pose rehabilitation challenges for many athletes. Injuries involving abnormal femoral acetabular morphology, reduced range of motion, and decreased lumbopelvic strength and endurance also may increase the risk of injury to lower extremities and delay return to play if proper rehabilitation does not take place. The rehabilitation of athletic hip injuries requires a multifaceted interdisciplinary approach that manages the interplay of multiple factors to restore preinjury function and facilitate return to play. Emphasis should be placed on activity modification, preservation of the arcs of range of motion, functional strengthening of the lumbopelvic core, and optimization of proprioceptive and neuromechanical strategies. Communication between providers and the injured athlete also is crucial to ensure that proper therapeutic approaches are being applied.