Gluteus Maximus Transfer for Irreparable Hip Abductor Deficiency: A Systematic Review and Meta-Analysis

BACKGROUND

Gluteus maximus tendon transfer has recently been described as a treatment option for irreparable abductor tendon tears. The purpose of this study was to systematically review outcomes following gluteus maximus tendon transfer for hip abductor deficiency.

METHODS

The published literature was queried for outcomes following gluteus maximus transfer in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Outcomes of interest included preoperative and postoperative functional scores, resolution of pain and gait abnormalities, postoperative rehabilitation protocols, surgical complications, reoperation rates, and postoperative magnetic resonance imaging. In total, 10 studies with a total of 125 patients (76% women) with a mean age of 67 years (range, 30 to 87) were identified for inclusion.

RESULTS

Modified Harris Hip Score (+30.1 ± 6.6 [95% confidence interval: +15.5 to +46.5]) and Visual Analog Scale for pain (-4.1 ± 1.1 [95% confidence interval: -7.1 to -1.0]) were improved following gluteus maximus transfer, compared to preoperative levels. No significant improvement was noted in abduction strength and 33% of patients demonstrated a residual Trendelenburg gait postoperatively. The overall complication rate was 5.6% (7 of 125), with a reoperation rate of 1.6% (2 of 125).

CONCLUSIONS

Gluteus maximus tendon transfer for abductor insufficiency has demonstrated reliable outcomes at 3 years, with improvement in hip function and pain. However, patients demonstrate modest improvements in abduction strength, and a significant subset will continue to demonstrate a Trendelenburg gait postoperatively.

Prediction of 3-Dimensional Coverage Surface Area of the Femoral Head in Hip Dysplasia Through Conventional Computed Tomography

Background

Assessment of 3-dimensional (3D) femoral head coverage is critical in evaluating, preoperative planning, and treating hip dysplasia.

Purpose

To (1) propose a mathematical model to establish 3D femoral head coverage using conventional computed tomography (CT), (2) determine the correlation of 2D parameters with 3D coverage, and (3) characterize the patterns of dysplasia based on 3D morphology.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

We identified 30 patients (n = hips) with symptomatic dysplasia and 30 patients (n = hips) without dysplasia. Patients with dysplastic hips were matched with regard to sex, age, and body mass index to those with nondysplastic hips. Preoperative CTs were analyzed using 3D software, and 3D femoral head surface area coverage (FHSAC; in %) was assessed in 4 quadrant zones: anteromedial, anterolateral, posteromedial, and posterolateral. To assess lateral coverage of the femoral head, we introduced the anterolateral femoral head coverage angle (ALFC) and the posterolateral femoral head coverage angle (PLFC).

Results

Reduced femoral head coverage was more pronounced in dysplastic versus nondysplastic hips in the anterolateral quadrant (18% vs 40.7%, respectively) and posterolateral quadrant (35.8% vs 56.9%, respectively) (P < .0001 for both). Dysplastic hips had smaller ALFC and PLFC (18.4° vs 38.7°; P < .0001; 47.2° vs 72.3°; P = .0002). Anterolateral and posterolateral FHSAC were strongly correlated with the ALFC (r = 0.88; P < .0001) and the PLFC (r = 0.82; P < .0001) along with the lateral center-edge angle (anterolateral, r = 0.75; P < .0001; posterolateral, r = 0.73; P < .0001). Prediction models established for FHSAC had strong agreement with explanatory CT variables (anterolateral: r = 0.91; P < .0001; posterolateral: r = 0.90; P < .0001). The cutoff values for anterolateral and posterolateral FHSAC were 25% and 41%, respectively. In dysplastic hips, global deficiency was most common (15/30 hips), 9 hips showed an anterolateral deficiency, and 4 hips had a posterolateral deficiency pattern.

Conclusion

The ALFC and The PLFC were strongly correlated with 3D lateral FHSAC and were able to predict 3D coverage accurately.

Revealing a Natural Model of Pre-Osteoarthritis of the Hip Through Study of Femoroacetabular Impingement

Femoroacetabular impingement (FAI) is considered the mechanical cause of hip osteoarthritis (OA). Surgical intervention involves labrum repair and osteochondroplasty to remove the impingement, alleviating symptoms. Nevertheless, some patients progress to hip OA after surgery, indicating that factors other than mechanical abnormality are contributing to hip OA progression. This review article discusses our laboratory's studies on hip FAI and OA, undertaken to identify key molecular players in the progression of hip OA. Transcriptome analysis identified peroxisome proliferator activated receptor gamma (PPARγ) as a crucial molecule in early hip OA. PPARγ, widely expressed in chondrocytes, has a protective role in preventing OA, but its true mechanism remains unknown. We observed a dysregulation of DNA methyltransferase (DNMT) in the progression of hip OA, with high expression of DNMT1 and 3A and downregulation of DNMT3B. Moreover, we established that DNMT3A is the main molecule that is binding to PPARγ promoter CpG area, and hypermethylation of this area occurs during disease progression. This suggests that epigenetic changes are a main mechanism that regulates PPARγ expression. Finally, we developed a novel rabbit model of hip FAI and OA and are currently performing studies to validate our small-animal model to human FAI.

Arthritis Foundation/HSS Workshop on Hip Osteoarthritis, Part 2: Detecting Hips at Risk: Early Biomechanical and Structural Mechanisms

Far more publications are available for osteoarthritis of the knee than of the hip. Recognizing this research gap, the Arthritis Foundation (AF), in partnership with the Hospital for Special Surgery (HSS), convened an in-person meeting of thought leaders to review the state of the science of and clinical approaches to hip osteoarthritis. This article summarizes the recommendations gleaned from 5 presentations given in the "early hip osteoarthritis" session of the 2023 Hip Osteoarthritis Clinical Studies Conference, which took place on February 17 and 18, 2023, in New York City. It also summarizes the workgroup recommendations from a small-group discussion on clinical research gaps.

Team Approach: Hip Preservation Surgery

The evaluation and treatment of adolescents and young adults with hip pain has seen tremendous growth over the past 20 years. Labral tears are well established as a common cause of hip pain but often occur because of underlying bony abnormalities. Femoroacetabular impingement (FAI) and acetabular dysplasia are now well-established causes of hip osteoarthritis and are increasingly treated in the prearthritic stage in hopes of improving symptoms and prolonging the longevity of the native hip. Beyond FAI and acetabular dysplasia, this patient population can present with a complex and variable group of underlying conditions that need to be taken into account. Expertise in the conservative management of this population, including physical therapy, is valuable to maximize the success. Preoperative, surgical, and postoperative decision-making and care in this population is complex and evolving. A comprehensive, multidisciplinary approach to the care of this patient population has been used for over 20 years by our institution with great success. The purpose of this article is to review the "team-based approach" necessary for successful management of the spectrum of adolescent and young adult hip disorders.

Epigenetic dysregulation of articular cartilage during progression of hip femoroacetabular impingement disease

Femoroacetabular impingement (FAI) is an important trigger of hip osteoarthritis (OA). Epigenetic changes in DNA methyltransferase 3B (DNMT3B) attenuate catabolic gene expression in cartilage hemostasis. This study aimed to examine the articular chondrocyte catabolic state and DNMT3B and 4-aminobutyrate aminotransferase promoter (ABAT) expression during OA progression in FAI. Cartilage samples were collected from the impingement zone of 12 patients with cam FAI (early-FAI) and 12 patients with advanced OA secondary to cam FAI (late-FAI-OA). Five healthy samples were procured from cadavers (ND: nondiseased). Explants were cultured under unstimulated conditions, catabolic stimulus (IL1β), or anabolic stimulus (TGFβ). Histology was performed with safranin-O/fast-green staining. Gene expression was analyzed via qPCR for GAPDH, DNMT3B, ABAT, MMP-13, COL10A1. Methylation specific PCR assessed methylation status at the ABAT promoter. Cartilage samples in early-FAI and late-FAI-OA showed a histological OA phenotype and increased catabolic marker expression (MMP13/COL10A1, ND vs. early-FAI, p = 0.004/p < 0.001, ND vs. late-FAI-OA, p < 0.001/p < 0.001). RT-PCR confirmed DNMT3B underexpression (ND vs. early-FAI, p < 0.001, early-FAI vs. late-FAI-OA, p = 0.016) and ABAT overexpression (ND vs. early-FAI, p < 0.001, early vs. late-FAI-OA, p = 0.035) with advanced disease. End-stage disease showed ABAT promoter hypomethylation. IL1β stimulus accentuated ABAT promoter hypomethylation and led to further ABAT and catabolic marker overexpression in early-FAI and late-FAI-OA while TGFβ normalized these alterations in gene expression. Catabolic and epigenetic molecule expression suggested less catabolism in early-stage disease. Sustained inflammation induced ABAT promoter hypo-methylation causing a catabolic phenotype. Suppression of ABAT by methylation control could be a new target for therapeutic intervention to prevent OA progression in hip FAI.

The Impact of Age on Clinical Outcomes of Acetabular Microfracture During FAI Surgery

BACKGROUND

Full-thickness acetabular cartilage lesions are common findings during primary surgical treatment of femoroacetabular impingement (FAI).

PURPOSE

To evaluate clinical outcomes after acetabular microfracture performed during FAI surgery in a prospective, multicenter cohort.

STUDY DESIGN

Cohort Study; Level of evidence, 3.

METHODS

Patients with FAI who had failed nonoperative management were prospectively enrolled in a multicenter cohort. Preoperative and postoperative (mean follow-up, 4.3 years) patient-reported outcome measures were obtained with a follow-up rate of 81.6% (621/761 hips), including 54 patients who underwent acetabular microfracture. Patient characteristics, radiographic parameters, intraoperative disease severity, and operative procedures were analyzed. Propensity matching using linear regression was used to match 54 hips with microfracture to 162 control hips (1:3) to control for confounding variables. Subanalyses of hips ≤35 and >35 years of age with propensity matching were also performed.

RESULTS

Patients who underwent acetabular microfracture were more likely to be male (81.8% vs 40.9%; P < .001), be older in age (35.0 vs 29.9 years; P = .001), have a higher body mass index (27.2 vs 25.0; P = .001), and have a greater alpha angle (69.6° vs 62.3°; P < .001) compared with the nonmicrofracture cohort (n = 533). After propensity matching to control for covariates, patients treated with microfracture displayed no differences in the modified Harris Hip Score or Hip Disability and Osteoarthritis Outcome Score (P = .22-.95) but were more likely to undergo total hip arthroplasty (THA) (13% [7/54] compared with 4% [6/162] in the control group; P = .002), and age >35 years was associated with conversion to THA after microfracture. Microfracture performed at or before 35 years of age portended good outcomes with no significant risk of conversion to THA at the most recent follow-up.

CONCLUSION

Microfracture of acetabular cartilage defects appears to be safe and associated with reliably improved short- to mid-term results in younger patients; modified expectations should be realized when full-thickness chondral lesions are identified in patients >35 years of age.

Gluteus Maximus Transfer for Hip Abductor Deficiency

Hip abductor deficiency resulting from gluteus medius and minimus pathology is increasingly recognized as a generator of lateral-sided hip pain. In the setting of a failed gluteus medius repair or in patients with irreparable tears, transfer of the anterior portion of the gluteus maximus muscle can be performed to treat gluteal abductor deficiency. The classic description of the gluteus maximus transfer technique relies solely on bone tunnel fixation. This article describes a reproducible technique that incorporates the addition of a distal row to the tendon transfer, which may improve fixation by both compressing the tendon transfer to the greater trochanter and providing improved biomechanical strength to the transfer.

Greater hip abductor size in prearthritic patients with developmental dysplasia of the hip versus femoroacetabular impingement

Developmental dysplasia of the hip (DDH) and femoroacetabular impingement (FAI) are common hip pathologies and important risk factors for osteoarthritis, yet the disease mechanisms differ. DDH involves deficient femoral head coverage and a shortened abductor moment arm, so this study hypothesized that the cross-sectional area (CSA) of the gluteus medius/minimus muscle complex and the stabilizing iliocapsularis muscle would be larger in DDH versus FAI, without increased fatty infiltration. A longitudinal cohort identified prearthritic patients with DDH or FAI who underwent imaging before surgery. Patients with DDH and FAI (Cam, Pincer, or Mixed) were 1:1 matched based on age, sex, and body mass index. Magnetic resonance imaging was used to measure the gluteus medius/minimus complex and iliocapsularis in two transverse planes. Amira software was used to quantify muscle and noncontractile tissue. Paired samples t-tests were performed to compare muscle size and composition (p < 0.05). There were no differences in the iliocapsularis muscle. Patients with DDH had significantly larger CSA of the gluteus medius/minimus complex at both transverse planes, and the noncontractile tissue proportion did not differ. The mean difference in overall muscle CSA at the anterior inferior iliac spine was 4.07 ± 7.4 cm² (p = 0.005), with an average difference of 12.1%, and at the femoral head this was 2.40 ± 4.37 cm² (p = 0.004), with an average difference of 20.2%. This study reports a larger CSA of the gluteus medius/minimus muscle complex in DDH compared to FAI, without a difference in noncontractile tissue, indicating increased healthy muscle in DDH.

Acetabular coverage analysis of the proximal femoral head accurately characterizes dysplastic acetabular morphology

This study aimed to (1) measure acetabular sector angle (ASA) from proximal to distal positions along the axial femoral head axis, (2) identify acetabular deficiency patterns, and (3) correlate ASA at different axial positions with other radiological measurements in acetabular dysplasia. We identified 30 hips with dysplasia (lateral center edge angle [LCEA] <20°) and 30 hips without dysplasia (LCEA >25°) from a retrospective cohort. Anterior and posterior ASA (AASA, PASA) were measured in the axial computed tomography plane through the femoral head center (equatorial) and two axial positions above the equatorial line (intermediate and proximal). Deficiency patterns were identified using ASA cut-off values determined from receiver operating characteristic curves. Pearson's coefficients were used for correlations. Compared to non-dysplastic hips, AASA in dysplastic hips was significantly smaller in all levels: equatorial (46.1 ± 7.3 vs. 54.9 ± 8.5,° p < 0.001), intermediate (62.1 ± 11.2 vs. 69.0 ± 10.6,° p = 0.02), and proximal (102.9 ± 14.2 vs. 128.3 ± 23.0,° p < 0.001). According to proximal ASA (Pro-ASA) cut-off values in dysplastic hips, global deficiency was most prevalent (19/30, 63.3%), followed by anterior (6/30, 20%) and posterior (3/30, 10%) deficiency. There were strong correlations between acetabular anteversion and Eq-AASA (r = -0.74, p < 0.001) and LCEA and pro-PASA (r = 0.82, p < 0.001). Clinical significance: Acetabular sector angle provides insight into acetabular morphology and patterns of deficiency, providing essential information for precise acetabular reorientation.

Factors Associated With Disease Progression in the Contralateral Hip of Patients With Symptomatic Femoroacetabular Impingement: A Minimum 5-Year Analysis

BACKGROUND

Femoroacetabular impingement (FAI) is one of the most common causes of hip osteoarthritis, yet the factors controlling disease progression are poorly understood.

PURPOSE

To investigate rates of initial and subsequent symptoms in the contralateral hip of patients with FAI, and identify predictors of disease progression (symptom development and surgical intervention) in the contralateral hip.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

This prospective study included a minimum 5-year follow-up of the contralateral hip in 179 patients undergoing FAI surgery. Symptoms (moderate pain) and surgical progression were monitored. Univariate and multivariate analyses compared patient-specific and imaging characteristics of symptomatic patients with those who remained asymptomatic to identify factors associated with disease progression.

RESULTS

A total of 150 patients (84% follow-up) were followed for a mean of 7.1 years (range, 5-11 years). Thirty-nine of these patients (26% [39/150]) had contralateral hip symptoms at initial evaluation. Of those without contralateral hip symptoms at initial evaluation, 32% (36/111) had developed contralateral hip symptoms by latest follow-up. Those who developed symptoms during the study period had a lower anteroposterior head-neck offset ratio (0.153 vs 0.165; P = .005), decreased total arc of rotation in 90° of flexion (39.9° vs 51.1°; P = .005), and decreased external rotation in 90° of flexion (28.6° vs 37.1°; P = .003) compared with those who never developed symptoms. Age, sex, body mass index, alpha angle, lateral center-edge angle, internal rotation in flexion, and University of California, Los Angeles (UCLA), activity score were similar between these groups. Those with contralateral symptoms at initial evaluation progressed to contralateral surgery at a rate of 41% (16/39) and those who developed contralateral symptoms during the study period progressed to contralateral surgery at a rate of 28% (10/36). Among those with contalateral hip symptoms (either present initially or developed during study period)), younger age (24.6 vs 34.1 years; P < .001) and baseline UCLA activity score ≥9 (P = .003) were associated with progression to surgery. By Kaplan-Meier analysis, 64%, 54%, and 48% of patients remained free of contralateral hip symptoms at 2, 5, and 10 years.

CONCLUSION

At a mean follow-up of 7.1 years, significant symptoms in the contralateral hip of patients with FAI were present in approximately 50% of patients. FAI disease progression (symptom development and surgical intervention) was associated with decreased hip rotation arc, decreased external rotation, and decreased head-neck offset ratio. In symptomatic patients, younger age and UCLA activity score ≥9 were associated with progression to surgery. These findings represent important factors for patient counseling and risk modeling in FAI.

Elevated loading at the posterior acetabular edge of dysplastic hips during double-legged squat

Hips with developmental dysplasia (DDH) are at a heightened risk of premature hip osteoarthritis, which is often expedited by mechanically induced articular tissue damage. A prevalent form of damage in DDH is labral tears caused by abnormal loading at the shallow acetabular edge. Although the majority of reported DDH-related labral tears occur in the antero-superior acetabulum, posterior labral tears are prevalent in individuals whose lifestyle involves frequent high hip flexion tasks such as squatting. To better understand region-specific risks for chondrolabral damage during high hip flexion, we used image-based musculoskeletal models to compare acetabular edge loading (AEL) during double-legged squat between hips with symptomatic DDH (n = 10) and healthy controls (n = 10). Compared to controls, hips with DDH had higher instantaneous posterior AEL at the lowest point of squat (2.6 vs. 1.8 ×BW, p ≤ 0.04), and higher accumulative loading across the duration of the squatting motion (2.6 vs. 1.9 ×BW*s, p ≤ 0.04). Elevated posterior AEL coincided with increased net hip extension moments and posterior joint reaction forces, and was correlated with the severity of DDH acetabular deformity. Our findings suggest that posterior AEL is elevated in hips with symptomatic DDH during double-legged squat, which may contribute to chondrolabral damage in individuals who often perform such high hip flexion tasks. Clinical evaluation of DDH should consider patient-specific anatomy and lifestyle factors when establishing diagnoses and planning personalized treatment.

External Validation of the FEAR Index in Borderline Acetabular Dysplasia

Background

Given the lack of established, externally validated criteria for the diagnosis of unstable hips, the Femoro-Epiphyseal Acetabular Roof (FEAR) index has been proposed as a useful tool for identifying hips with instability in the setting of borderline acetabular dysplasia.

Purposes

To (1) determine the external performance of the FEAR index in identifying hips with a clinical diagnosis of instability in the setting of borderline dysplasia and (2) assess the performance of the FEAR index compared with acetabular inclination or physeal scar angle alone.

Study Design

Cohort study (diagnosis); Level of evidence, 3.

Methods

The authors reviewed 176 patients with borderline acetabular dysplasia (lateral center-edge angle, 20°-25°). A positive FEAR index was defined as ≥5°. An alternative threshold ≥2° was also assessed. Significant instability was determined by the senior surgeon based on the combination of patient and radiographic features; unstable hips were treated with periacetabular osteotomy (with or without hip arthroscopy), and stable hips were treated with isolated hip arthroscopy.

Results

Only 18% of borderline hips had a positive FEAR index. The ≥5° positive FEAR index threshold had a sensitivity of 33% (23/70) and specificity of 92% (98/106) in predicting the clinical diagnosis of instability. The ≥2° FEAR index threshold had a sensitivity of 39% (27/70) and specificity of 89% (94/106) in predicting the clinical diagnosis of instability. No alternative threshold for the FEAR index resulted in high levels of sensitivity and specificity. A threshold of -5° was required to reach an adequate sensitivity of 74%. The FEAR index remained a significant predictor of hip instability even after controlling for acetabular inclination (odds ratio, 1.12; P < .001) or physeal scar angle (odds ratio, 1.6; P < .001).

Conclusion

In the current study, a positive FEAR index was generally indicative of the presence of clinical instability, but the FEAR index alone remained inadequate to fully define the instability of a given hip, as it demonstrated low sensitivity (only 33%) in the external validation. The FEAR index is best used in the context of other clinical and radiographic features.

Otto Aufranc Award: Identification of Key Molecular Players in the Progression of Hip Osteoarthritis Through Transcriptomes and Epigenetics

BACKGROUND

This study aimed: (1) to compare the transcriptome profile of articular cartilage in cam-FAI (early stage) to advanced OA secondary to cam-FAI (late stage) and (2) to investigate epigenetic changes through the expression of DNA methylation enzymes DNMT3B, DNMT1, and DNMT3A and peroxisome proliferator-activated receptor gamma (PPARγ) in human cartilage samples during the progression of hip OA.

METHODS

Full-thickness cartilage samples were collected from the anterolateral head-neck junction (impingement zone) of 22 patients (9 early-FAI and 13 late-FAI). RNA sequencing and in vitro cartilage cultures with histological analysis and immunohistochemistry staining for PPARγ and DNMT3B were performed. Target gene validation was confirmed with RT-PCR.

RESULTS

Fifty genes and 42 pathways were identified differentially between early and late-FAI (fold change <-1.5 or >1.5, P < .01). PPARγ and DNMT3B were gradually suppressed with disease progression. Contrarily, disease progression induced expression of DNMT1/3A.

CONCLUSION

By comparing comprehensive gene expression in early and late stage hip degeneration at the whole-genome level, distinct transcriptome profiles for early and late stage disease were identified along with key molecular contributors to the progression of hip OA. Preservation of endogenous PPARγ may have therapeutic potential to delay or prevent hip OA.

A Novel Model of Hip Femoroacetabular Impingement in Immature Rabbits Reproduces the Distinctive Head-Neck Cam Deformity

BACKGROUND

Femoroacetabular impingement (FAI) is a leading cause of hip pain in young adults and often leads to degenerative osteoarthritis (OA). A small animal model of hip deformities is crucial for unraveling the pathophysiology of hip OA secondary to FAI.

PURPOSES

To (1) characterize a new minimally invasive surgical technique to create a proximal femoral head-neck deformity in a skeletally immature rabbit model and (2) document the effect of an injury to the medial proximal femoral epiphysis on head-neck morphology at 28 days after the injury.

STUDY DESIGN

Controlled laboratory study.

METHODS

Six-week-old New Zealand White rabbits (n = 10) were subjected to right hip surgery, with the left hip used as a control. An epiphyseal injury in the medial femoral head was created using a 1.6-mm drill. Hips were harvested bilaterally at 28 days after surgery. Alpha and epiphyseal shaft angles were measured on radiographs. Alpha angles at the 1- and 3-o'clock positions were measured on the oblique axial plane of micro-computed tomography images. Bone bar formation secondary to growth plate injuries was confirmed using alcian blue hematoxylin staining.

RESULTS

All hips in the study group showed a varus-type head-neck deformity, with lower epiphyseal shaft angles on anteroposterior radiographs versus those in the control group (133°± 8° vs 142°± 5°, respectively; P = .022) and higher epiphyseal shaft angles on lateral radiographs (27°± 12° vs 10°± 7°, respectively; P < .001). The mean alpha angles in the study group were higher at both the 1- (103°± 14° vs 46°± 7°, respectively; P < .002) and 3-o'clock (99°± 18° vs 35°± 11°, respectively; P < .002) positions than those in the control group. Alcian blue hematoxylin staining of all hips in the study group indicated that the injured physis developed a bony bar, leading to growth plate arrest on the medial femoral head.

CONCLUSION

The proposed model led to growth arrest at the proximal femoral physis, resulting in a femoral head-neck deformity similar to human FAI.

CLINICAL RELEVANCE

Our novel small animal model of a femoral head-neck deformity is a potential platform for research into the basic mechanisms of FAI disease progression and the development of disease-modifying therapies.

Patients With Symptomatic Sequelae of Slipped Capital Femoral Epiphysis Have Advanced Cartilage Wear at the Time of Surgical Intervention

BACKGROUND

Slipped capital femoral epiphysis (SCFE) is a common hip problem in children. The resulting deformity can cause impingement similar to cam-type idiopathic femoroacetabular impingement (FAI). Although there are similarities between FAI and SCFE, deformity patterns, severity, and time of onset of symptoms varies, which may impact management. The purpose of this study was to describe patterns of articular cartilage damage in patients undergoing surgical hip dislocation for sequelae of SCFE in comparison to patients undergoing arthroscopic surgery for primary FAI.

METHODS

Patients were identified who underwent surgical treatment for hip pain due to primary FAI (cam type) or sequelae of SCFE. Clinical data and radiographic measurements were recorded. Cartilage was assessed intraoperatively. Severity was classified using the modified Beck classification, while location was classified into 6 sectors. Statistical analysis was performed to test for differences in demographic and radiographic characteristics between the SCFE and FAI patients. χ2 or Fisher exact tests were used to evaluate trends in patterns of acetabular and femoral cartilage wear between SCFE and FAI groups.

RESULTS

The SCFE group had 28 hips compared with 304 in the FAI group. SCFE patients were younger (19 vs. 32, P<0.001), had higher body mass index (30±5.9 vs. 24±4.8, P<0.001), and were more often male (61% vs. 27%, P<0.001). Deformity severity based on α-angle was higher in the SCFE group [AP 74 vs. 55 (P=0.001) and Dunn 72 vs. 58 (P<0.001)]. There were no significant differences with regards to lateral center edge angle, anterior center edge angle, or Tonnis angle. In both groups the most common locations for cartilage lesions in both groups were the anterior peripheral and superolateral peripheral regions with fewer but more widely distributed femoral head lesions. The SCFE group had higher rates of femoral head and superolateral central cartilage lesions compared with the FAI group. There was no statistical difference between high-grade femoral or acetabular cartilage lesions between groups.

CONCLUSIONS

Patients with SCFE were younger at the time of surgery and presented with more severe deformity based on radiographic α-angle compared to patients with FAI. Our results suggest higher prevalence of femoral head lesions and more diffuse cartilage injury in patients with SCFE. This study can be used to support early surgical intervention in patients with symptomatic sequelae of SCFE due to risk of premature joint damage.

LEVEL OF EVIDENCE

Level III-prognostic study.

Acetabular Edge Loading During Gait Is Elevated by the Anatomical Deformities of Hip Dysplasia

Developmental dysplasia of the hip (DDH) is a known risk factor for articular tissue damage and secondary hip osteoarthritis. Acetabular labral tears are prevalent in hips with DDH and may result from excessive loading at the edge of the shallow acetabulum. Location-specific risks for labral tears may also depend on neuromuscular factors such as movement patterns and muscle-induced hip joint reaction forces (JRFs). To evaluate such mechanically-induced risks, we used subject-specific musculoskeletal models to compare acetabular edge loading (AEL) during gait between individuals with DDH (N = 15) and healthy controls (N = 15), and determined the associations between AEL and radiographic measures of DDH acetabular anatomy. The three-dimensional pelvis and femur anatomy of each DDH and control subject were reconstructed from magnetic resonance images and used to personalize hip joint center locations and muscle paths in each model. Model-estimated hip JRFs were projected onto the three-dimensional acetabular rim to predict instantaneous AEL forces and their accumulative impulses throughout a gait cycle. Compared to controls, subjects with DDH demonstrated significantly higher AEL in the antero-superior acetabulum during early stance (3.6 vs. 2.8 × BW, p ≤ 0.01), late stance (4.3 vs. 3.3 × BW, p ≤ 0.05), and throughout the gait cycle (1.8 vs. 1.4 × BW^*s, p ≤ 0.02), despite having similar hip movement patterns. Elevated AEL primarily occurred in regions where the shallow acetabular edge was in close proximity to the hip JRF direction, and was strongly correlated with the radiographic severity of acetabular deformities. The results suggest AEL is highly dependent on movement and muscle-induced joint loading, and significantly elevated by the DDH acetabular deformities.

What Mid-term Patient-reported Outcome Measure Scores, Reoperations, and Complications Are Associated with Concurrent Hip Arthroscopy and Periacetabular Osteotomy to Treat Dysplasia with Associated Intraarticular Abnormalities?

BACKGROUND

Periacetabular osteotomy (PAO) is a well-accepted treatment for acetabular dysplasia, but treatment success is not uniform. Concurrent hip arthroscopy has been proposed for select patients to address intraarticular abnormalities. The patient-reported outcomes, complications, and reoperations for concurrent arthroscopy and PAO to treat acetabular dysplasia remain unclear.

QUESTIONS/PURPOSES

(1) What are the functional outcome scores among select patients treated with PAO plus concurrent hip arthroscopy at mid-term follow-up? (2) What factors are associated with conversion to THA or persistent symptoms (modified Harris hip score ≤ 70 or WOMAC pain subscore ≥ 10)? (3) What proportion of patients underwent further hip preservation surgery at mid-term follow-up? (4) What are the complications associated with the procedure?

METHODS

Between November 2005 and December 2012, 78 patients (81 hips) who presented with symptomatic acetabular dysplasia-defined as a lateral center-edge angle less than 20° with hip pain for more than 3 months that interfered with daily function-had undergone unsuccessful nonsurgical treatment, had associated intraarticular abnormalities on MRI, and underwent combined hip arthroscopy and PAO. Eleven patients did not have minimum 4-year follow-up and were excluded, leaving 67 patients (70 hips) who met our inclusion criteria and had a mean follow-up duration of 6.5 ± 1.6 years. We retrospectively evaluated patient-reported outcomes at final follow-up using the University of California Los Angeles (UCLA) activity score, the modified Harris Hip Score (mHHS), and the WOMAC pain subscore. Conversion to THA or persistent symptoms were considered clinical endpoints. Repeat surgical procedures were drawn from a prospectively maintained database, and major complications were graded according to the validated Clavien-Dindo classification (Grade III or IV). Student t-tests, chi-square tests, and Fisher exact tests identified the association of patient factors, radiographic measures, and surgical details with clinical endpoints. For patients who underwent bilateral procedures, only the first hip was included in our analyses.

RESULTS

At final follow-up, the mean mHHS for all patients improved from a mean ± SD of 55 ± 19 points to 85 ± 17 points (p < 0.001), the UCLA activity score improved from 6.5 ± 2.7 points to 7.5 ± 2.2 points (p = 0.01), and the WOMAC pain score improved from 9.1 ± 4.3 points to 3.2 ± 3.9 points (p < 0.001). Three percent (2 of 67) of patients underwent subsequent THA, while 21% (15 of 70) of hips were persistently symptomatic, defined as mHHS less than or equal to 70 or WOMAC pain subscore greater than or equal to 10. Univariate analyses indicated that no patient demographics, preoperative or postoperative radiographic metrics, or intraoperative findings or procedures were associated with subsequent THA or symptomatic hips. Worse baseline mHHS and WOMAC pain scores were associated with subsequent THA or symptomatic hips. Seven percent (5 of 67) of patients underwent repeat hip preservation surgery for recurrent symptoms, and 4% (3 of 67) of patients had major complications (Clavien-Dindo Grade III or IV).

CONCLUSION

This study demonstrated that concurrent hip arthroscopy and PAO to treat symptomatic acetabular dysplasia (with intraarticular abnormalities) has good clinical outcomes at mid-term follow-up in many patients; however, persistent symptoms or conversion to THA affected almost a quarter of the sample. We noted an acceptable complication profile. Further study is needed to directly compare this approach to more traditional techniques that do not involve arthroscopy. We do not use isolated hip arthroscopy to treat symptomatic acetabular dysplasia.

LEVEL OF EVIDENCE

Level IV, therapeutic study.

Editorial Commentary: Reach Over the Top and Preserve the Hip Labrum

There is increasing interest in fine tuning of hip arthroscopy to improve the long-term outcomes of femoroacetabular impingement (FAI) surgery. Recently, some advocated for rim trimming and labral refixation without taking down the labrum, using a so-called over-the-top technique. Although some studies have already reported on the outcomes of this procedure, very few have focused on how maintaining an unharmed chondrolabral junction may decrease cartilage wear over time. Preserving labral attachment should be the standard of care in the treatment of FAI, to keep the suction seal working normally.

Short-term Clinical Outcomes of Hip Arthroscopy Versus Physical Therapy in Patients With Femoroacetabular Impingement: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Background:

Both physical therapy (PT) and surgery are effective in treating femoroacetabular impingement (FAI), but their relative efficacy has not been well established until recently. Several randomized controlled trials (RCTs) comparing the early clinical outcomes of these treatments have been published, with contradictory results.

Purpose/Hypothesis:

The purpose of this study was to perform a meta-analysis of RCTs that compared early patient-reported outcomes (PROs) of hip arthroscopy versus PT in patients with symptomatic FAI. The hypothesis was that surgical treatment of FAI leads to better short-term outcomes than PT.

Study Design:

Systematic review; Level of evidence, 1.

Methods:

In March 2019, a systematic review was performed to identify RCTs comparing hip arthroscopy and PT in patients with symptomatic FAI. A total of 819 studies were found among 6 databases; of these, 3 RCTs met eligibility (Griffin et al, 2018; Mansell et al, 2018; and Palmer et al, 2019). All 3 RCTs reported international Hip Outcome Tool--33 (iHOT-33) scores, and 2 reported Hip Outcome Score (HOS)–Activities of Daily Living (ADL) and HOS-Sport results. In a random-effects meta-analysis, between-group differences in postintervention scores were assessed according to intention-to-treat and as-treated approaches. Quality was assessed with CONSORT, CERT, TiDieR, and the Cochrane Collaboration tool.

Results:

The 3 RCTs included 650 patients with FAI; the mean follow-up ranged from 8 to 24 months. All studies reported PRO improvement from baseline to follow-up for both PT and surgery. The quality of the Griffin and Palmer studies was good, with minimal bias. In the Mansell study, a 70% crossover rate from PT to surgery increased the risk of bias. The meta-analysis demonstrated improved iHOT-33 outcomes with surgery compared with PT for intention-to-treat (mean difference [MD], 11.3; P = .046) and as-treated (MD, 12.6; P = .007) analyses. The as-treated meta-analysis of HOS-ADL scores favored surgery (MD, 12.0; P < .001), whereas the intention-to-treat analysis demonstrated no significant difference between groups for HOS-ADL (MD, 3.9; P = .571).

Conclusion:

In patients with FAI, the combined results of 3 RCTs demonstrated superior short-term outcomes for surgery versus PT. However, PT did result in improved outcomes and did not appear to compromise the surgical outcomes of patients for whom therapy failed and who progressed to surgery.

The Hip Arthroscopy Post-less Procedure Impingement (HAPPI) Technique: Achieving Distraction With Standard Hip Tables at Zero Additional Cost

Hip arthroscopy is becoming a more common treatment for femoroacetabular impingement, labral tears, and a variety of other hip pathologies. Unlike arthroscopy of the shoulder and knee, hip arthroscopy requires a significant amount of traction to gain access into the joint. Historically, traction has been achieved with the use of a perineal post. The use of a perineal post in hip arthroscopy can cause several avoidable complications such as neuropraxias (i.e., the pudendal nerve), vaginal or scrotal injuries, and perineal skin injuries. Several articles have been proposed using post-less techniques to obtain hip traction, but many of these techniques are expensive and require the purchase of new equipment. The purpose of this Technical Note is to describe a post-less technique for hip arthroscopy, the HAPPI technique (hip arthroscopy post-less procedure impingement), which is more affordable and does not require the addition of any special equipment. In addition, we will review some pearls and pitfalls, as well as advantages and disadvantages of the proposed technique.

Distinct Pattern of Inflammation of Articular Cartilage and the Synovium in Early and Late Hip Femoroacetabular Impingement

BACKGROUND

The molecular mechanism of how femoroacetabular impingement (FAI) morphology leads to hip osteoarthritis (OA) is yet to be determined. The expression and location of inflammation-related molecules during early- and late-stage FAI have not been previously described. Moreover, the characterization of intra-articular inflammation away from the cam deformity as well as the nature of adjacent synovial tissue have also not been extensively reported.

HYPOTHESIS

Early-stage FAI has a similar expression of inflammation-related markers in the head-neck and acetabular cartilage but less synovitis than late-stage FAI.

STUDY DESIGN

Controlled laboratory study.

METHODS

Head-neck cartilage, acetabular cartilage, and synovial samples were obtained from patients undergoing hip preservation surgery for the treatment of symptomatic cam FAI (early FAI group; n = 15) and advanced OA secondary to cam FAI (late FAI group; n = 15). Samples procured from healthy young adult donors served as the control group (n = 7). Cartilage degeneration was assessed by histology, and the expression of inflammation-related proteins (interleukin-1 beta [IL-1β], matrix metalloproteinase-13 [MMP-13], a disintegrin and metalloproteinase with thrombospondin motifs-4 [ADAMTS-4], type II collagen [COL2], and aggrecan neoepitope [NITEGE]) was measured by immunostaining. Synovial samples in the early and late FAI groups were examined for synovitis and the expression of IL-1β.

RESULTS

Head-neck cartilage in the early FAI group showed significantly more degeneration than the control group and an increased expression of inflammation-related proteins (IL-1β: 69.7% ± 18.1% vs 20.2% ± 4.9%, respectively; MMP-13: 79.6% ± 12.6% vs 25.3% ± 9.5%; ADAMTS-4: 83.9% ± 12.2% vs 24.3% ± 11.1%; NITEGE: 89.7% ± 7.7% vs 39.8% ± 20.5%) (P < .001). Head-neck and acetabular cartilage in the early and late FAI groups showed a similar degree of degeneration. Moreover, a similar expression of inflammation-related proteins was observed between the early and late FAI groups for head-neck cartilage (IL-1β: 69.7% ± 18.1% vs 72.5% ± 13.2%; MMP-13: 79.6% ± 12.6% vs 71.4% ± 18.8%; ADAMTS-4: 83.9% ± 12.2% vs 82.6% ± 12.5%; COL2: 93.6% ± 3.9% vs 92.5% ± 5.8%; NITEGE: 89.7% ± 7.7% vs 95.7% ± 4.7%) and acetabular cartilage (IL-1β: 83.3% ± 24.8% vs 80.7% ± 15.6%; MMP-13: 94.3% ± 9.7% vs 85.2% ± 12.3%; ADAMTS-4: 98.5% ± 2.3% vs 98.4% ± 3.4%; COL2: 99.8% ± 0.7% vs 99.7% ± 1.1%; NITEGE: 96.7% ± 6.7% vs 99.2% ± 2.2%). In contrast, synovitis was minimal with a low expression of IL-1β in the early FAI group compared with the late FAI group.

CONCLUSION

Hip cartilage exhibited an OA phenotype in patients with early-stage FAI, similar to what was observed in hip OA secondary to FAI. Severe synovitis was only evident with late-stage FAI.

CLINICAL RELEVANCE

This study supports the concept that early hip impingement is associated with cartilage degeneration and catabolism.

Dysplastic hip anatomy alters muscle moment arm lengths, lines of action, and contributions to joint reaction forces during gait

Developmental dysplasia of the hip (DDH) is characterized by abnormal bony anatomy, which causes detrimental hip joint loading and leads to secondary osteoarthritis. Hip joint loading depends, in part, on muscle-induced joint reaction forces (JRFs), and therefore, is influenced by hip muscle moment arm lengths (MALs) and lines of action (LoAs). The current study used subject-specific musculoskeletal models and in-vivo motion analysis to quantify the effects of DDH bony anatomy on dynamic muscle MALs, LoAs, and their contributions to JRF peaks during early (~17%) and late-stance (~52%) of gait. Compared to healthy hips (N = 15, 16-39 y/o), the abductor muscles in patients with untreated DDH (N = 15, 16-39 y/o) had smaller abduction MALs (e.g. anterior gluteus medius, 35.3 vs. 41.6 mm in early stance, 45.4 vs. 52.6 mm late stance, p ≤ 0.01) and more medially-directed LoAs. Abduction-adduction and rotation MALs also differed for major hip flexors such as rectus femoris and iliacus. The altered MALs in DDH corresponded to higher hip abductor forces, medial JRFs (1.26 vs. 0.87 × BW early stance, p = 0.03), and resultant JRFs (5.71 vs. 4.97 × BW late stance, p = 0.05). DDH anatomy not only affected hip muscle force generation in the primary plane of function, but also their out-of-plane mechanics, which collectively elevated JRFs. Overall, hip muscle MALs and their contributions to JRFs were significantly altered by DDH bony anatomy. Therefore, to better understand the mechanisms of joint degeneration and improve the efficacy of treatments for DDH, the dynamic anatomy-force relationships and multi-planar functions of the whole hip musculature must be collectively considered.

Inflammatory Response of Articular Cartilage to Femoroacetabular Impingement in the Hip

BACKGROUND

Femoroacetabular impingement (FAI) has been proposed as an etiologic factor in up to 50% of hips with osteoarthritis (OA). Inflammation is thought to be one of the main initiators of OA, yet little is known about the origin of intra-articular inflammation in FAI hips.

HYPOTHESIS

Articular cartilage from the impingement zone of patients with FAI has high levels of inflammation, reflecting initial inflammatory process in the hip.

STUDY DESIGN

Controlled laboratory study.

METHODS

Head-neck cartilage samples were obtained from patients with cam FAI (cam FAI, early FAI; n = 15), advanced OA secondary to cam FAI (FAI OA, late FAI; n = 15), and advanced OA secondary to developmental dysplasia of the hip (DDH OA, no impingement; n = 15). Cartilage procured from young adult donors (n = 7) served as control. Safranin O-stained sections were assessed for cartilage abnormality. Tissue viability was detected by TUNEL assay. Immunostaining of interleukin 1β (IL-1β), catabolic markers (matrix metalloproteinase 13 [MMP-13], a disintegrin and metalloproteinase with thrombospondin motif 4 [ADAMTS-4], aggrecan antibody to C-terminal neoepitope [NITEGE]), and an anabolic marker (type II collagen [COL2]) was performed to evaluate molecular inflammation and metabolic activity. The average percentage of immunopositive cells from the total cell count was calculated. Kruskal-Wallis test followed by Steel-Dwass post hoc test was used for multiple comparisons.

RESULTS

Microscopic osteoarthritic changes were more prevalent in cartilage of cam FAI and FAI OA groups compared with DDH OA and control groups. Cartilage in cam FAI and FAI OA groups, versus the DDH group, had higher expression of inflammatory molecules IL-1β (69.7% ± 18.1% and 72.5% ± 13.2% vs 32.7% ± 14.4%, respectively), MMP-13 (79.6% ± 12.6% and 71.4% ± 18.8% vs 38. 5% ± 13.3%), ADAMTS-4 (83.9% ± 12.2% and 82.6% ± 12.5% vs 45.7% ± 15.5%), and COL2 (93.6% ± 3.9% and 92.5% ± 5.8% vs 53.3% ± 21.0%) (P < .001). Expression of NITEGE was similar among groups (cam FAI, 89.7% ± 7.7%; FAI OA, 95.7% ± 4.7%; DDH OA, 93.9% ± 5.2%; P = .0742). The control group had minimal expression of inflammatory markers. Inflammatory markers were expressed in all cartilage zones of early and late FAI but only in the superficial zone of the no impingement group.

CONCLUSION

Cartilage from the impingement zone in FAI is associated with a high expression of inflammatory markers, extending throughout all cartilage zones.

CLINICAL RELEVANCE

Inflammation associated with FAI likely has a deleterious effect on joint homeostasis. Further clinical and translational studies are warranted to assess whether and how surgical treatment of FAI reduces molecular inflammation.

Editorial Commentary: The Competitive Dancer's Hip-An Acquired Flexible Attitude to a High-Performance Hip

Competitive dancers have a high prevalence of hip injuries. The dancer's hip is a unique scenario in which hip impingement is associated with compensatory soft-tissue laxity. Particularly in these athletes, normal osseous hip morphology with symptomatic femoroacetabular impingement may be observed. The repetitive training, including extreme daily hip range of motion, results in compensatory soft-tissue laxity and secondary impingement-induced subluxation. Peculiarly, hip impingement in dancers occurs in the posterosuperior aspect of the hip and extra-articularly between the anterior inferior iliac spine and the distal femoral neck (subspinous impingement). Normal or even dysplastic hips might impinge during extreme range of motion. An atypical osteochondroplasty, including a subtle distal-based femoral resection, anterior inferior iliac spine decompression, and excellent management of the capsule, should be considered in this population for a successful outcome. Hip dysplasia should always be ruled out in these athletes, and if present, a periacetabular osteotomy should be indicated.

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.

Activity Level Maintenance at Midterm Follow-up Among Active Patients Undergoing Periacetabular Osteotomy

BACKGROUND

For active patients undergoing periacetabular osteotomy (PAO), returning to and maintaining a high level of activity postoperatively is a priority.

PURPOSE

To evaluate the maintenance of activity levels at midterm follow-up in active patients treated with PAO for symptomatic acetabular dysplasia.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Patients who underwent PAO for symptomatic acetabular dysplasia between June 2006 and August 2013 were identified by a retrospective review of our prospective longitudinal institutional Hip Preservation Database. All patients with a preoperative University of California, Los Angeles (UCLA) score of ≥7 and a potential minimum 5 years of follow-up were included in the study. Functional outcome measures were the UCLA score, modified Harris Hip Score (mHHS), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). The maintenance of high activity levels was defined as a UCLA score of ≥7 at final follow-up. Radiographic parameters were measured. Statistical significance was defined as a P value <.05.

RESULTS

A total of 66 hips (58 patients) were included. The mean age was 25.3 years (range, 14-47 years), the mean body mass index was 23.9 kg/m² (range, 19-32 kg/m²), and 72% were female. The mean follow-up was 6.8 years (range, 5-11 years). There were 67% of patients who maintained a UCLA score of ≥7. Patient-reported outcomes improved postoperatively from preoperatively for the mHHS (88 ± 14 vs 67 ± 17, respectively; P < .001) and WOMAC (89 ± 15 vs 73 ± 20, respectively; P < .001). The lateral center-edge angle, anterior center-edge angle, and acetabular inclination were significantly improved at final follow-up (P < .001). Only 4 patients (7%) cited postoperative activity limitations as being caused by hip pain. There were no conversions to total hip arthroplasty.

CONCLUSION

The majority (67%) of active patients returned to preoperative or higher activity levels after PAO at midterm follow-up.

Surgical Treatment of Gluteus Medius Tears Augmented With Allograft Human Dermis

Greater trochanteric pain syndrome can be caused by gluteus medius and minimus tendinopathy/tears and chronic trochanteric bursitis. Specifically, moderate-to-severe abductor tendon tears can cause severe lateral hip pain, limp, and abnormal gait. A variety of open and endoscopic techniques to treat glut abductors hip tears have been described. The use of scaffolds, such as acellular human dermal allograft, to augment tendon repair, already has been successfully reported in rotator cuff repairs of the shoulder. Still, the use of acellular human dermal allograft in the hip has been limited. However, there are some clinical scenarios in which augmentation of abductors hip tendon repair with scaffold is indicated. Chronic or massive gluteus tears or revision cases may benefit from augmentation with a scaffold. The purpose of this technical note and accompanying video is to describe our indications, pearls, and pitfalls of repair of moderate to severe gluteus tears via a minimally invasive technique augmented with acellular human dermal allograft.

The Pattern of Acetabular Cartilage Wear Is Hip Morphology-dependent and Patient Demographic-dependent

BACKGROUND

Acetabular cartilage damage has been described in patients with femoroacetabular impingement (FAI). However, most reports of articular cartilage damage in hip FAI have been focused on the acetabular cartilage and derived from single-center, retrospective studies of relatively small patient cohorts. Identifying patterns of articular cartilage wear is important in patient selection, treatment prognosis, and determining whether patterns of intraarticular cartilage wear are secondary to abnormal hip morphology. Using a multicenter, observational cohort, we sought to determine whether there was a specific pattern of cartilage wear across acetabular and femoral articular cartilage among patients with symptomatic FAI.

QUESTIONS/PURPOSES

(1) Is there is a specific pattern of cartilage wear in the acetabulum and femoral head, assessed during hip arthroscopy, in cam FAI, pincer, and mixed-type hip pathologies? (2) Are there specific patterns of cartilage wear associated with duration of symptoms, age, and/or body mass index (BMI)?

METHODS

A multicenter observational cohort and a hip preservation database from a senior author were used to identify 802 patients who underwent hip arthroscopy for the treatment of symptomatic FAI. The diagnosis of cam, pincer, or mixed-type FAI was determined by each treating surgeon at each institution using the minimum basic criteria of pain in the affected hip for a period of > 3 months, hip ROM, and radiographic findings. Acetabular and femoral head cartilage lesions were classified arthroscopically by location and severity for each group (cam, pincer, or mixed FAI). Cartilage wear was classified using the Beck classification and defined as cartilage lesions greater than Grade 1 (normal macroscopically sound cartilage). The assessment of cartilage wear was performed arthroscopically by experienced hip preservation surgeons who are a part of ANCHOR, a multicenter group that uses a longitudinally maintained database to investigate issues related to hip preservation surgery. Clinical characteristics, radiographic findings, and acetabular and femoral head damage by location and severity of wear were reported based on patient diagnoses of cam (n = 472), mixed (n = 290), and pincer (n = 40) FAI hip pathologies. Wald chi-square tests were used to test for differences in the presence of wear in each cartilage quadrant across hip pathologies, duration of symptoms, age, and BMI. One-way analysis of variance tests were used to test for differences in average grade of wear in each cartilage quadrant across hip pathologies, duration of symptoms, age, and BMI. A bivariate logistic regression model was used to identify factors independently associated with the presence of cartilage wear in the acetabulum and femoral head. Acetabular cartilage wear was present in 743 of 802 patients (93%) in the cohort. Femoral head cartilage wear was observed in only 130 (16%).

RESULTS

We found significant associations between acetabular patterns of wear and FAI hip pathologies; specifically, we observed more frequent and severe debonding of acetabular cartilage in patients with symptomatic cam (93%, 1.7 ± 1.1 grade) and mixed (97%, 1.7 ± 1.2 grade) FAI compared with Pincer (75%, 1.5 ± 0.9 grade) FAI hip pathologies (p < 0.001). Superolateral peripheral cartilage lesions occurred more frequently and with greater severity in patients with cam (90% [416 of 472] prevalence, 3.1 ± 1.1 grade) and mixed (91% [260 of 290] prevalence, 3.1 ± 1.1 grade) FAI than in pincer (60% [24 of 40] prevalence, 2.2 ± 1.1 grade) FAI hip pathologies (p < 0.0001). Conversely, patients with pincer FAI most commonly demonstrated cartilage lesions with an even distribution at the anterior and superolateral acetabular rim: 64% (25 of 40) (mean grade 2.1 ± 1.0) and 60% (24 of 40) mean grade 2.2 ± 1.1, respectively. Age was associated with increased presence of wear in both the acetabulum (odds ratio [OR], 1.05; 95% confidence interval [CI], 1.2-1.7; p = 0.005) and femoral head (OR, 1.08; 95% CI, 1.6-1.1; p < 0.001). BMI was associated with a greater presence of wear only in the femoral head (OR, 1.1; 95% CI, 1.2-1.1; p = 0.002). Specifically, compared with patients with a BMI < 30 kg/m, patients with a BMI ≥ 30 kg/m presented with more frequent and more severe lesions in the posterior peripheral acetabular rim (42% [47 of 117] versus 26% [171 of 677], p = 0.0006; grade 1.9 ± 1.3 versus grade 1.4 ± 0.9, p < 0.001), the anterolateral femoral head (22% [20 of 117] versus 9% [60 of 67], p = 0.006), and the anteromedial femoral head (15% [16 of 117] versus 6% [39 of 677], p = 0.002; grade 1.3 ± 0.8 versus grade 1.1 ± 0.6, p = 0.04). In general, we found that older patients (≥ 50 years old) presented with more frequent and more severe lesions in both the acetabulum and femoral head. We found no association between hip pathology and cartilage wear patterns in the examined femoral heads.

CONCLUSIONS

Hip morphology affects the pattern of acetabular cartilage wear. More frequent and severe cartilage lesions were observed in patients with symptomatic FAI cam and mixed-type hip pathologies. Surgical attempts to restore normal anatomy to avoid FAI should be performed to potentially improve long-term joint homeostasis. Increasing age is an independent risk for cartilage wear in both the acetabulum and femoral head. Additionally, increased BMI is an independent risk factor for cartilage wear in the femoral head. In the future, prospective studies should provide further insight into the pathomechanics of early degenerative changes associated with hip FAI deformities.

LEVEL OF EVIDENCE

Level III, prognostic study.

Psychometric Properties of Patient-Reported Outcome Measures for Periacetabular Osteotomy

BACKGROUND

Appropriate patient-reported outcome measures are paramount to determine the clinical relevance of change experienced by patients after a surgical procedure. The purpose of this study was to evaluate the psychometric properties of 3 patient-reported outcome measures (Hip disability and Osteoarthritis Outcome Score [HOOS], modified Harris hip score, and Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC]) in a large population of patients treated with periacetabular osteotomy for symptomatic developmental dysplasia of the hip.

METHODS

Patients who underwent a periacetabular osteotomy for acetabular dysplasia between October 2011 and October 2016 completed multiple questionnaires preoperatively and at the 1-year follow-up. Internal consistency for subscores was evaluated with the Cronbach alpha. Validity was assessed against the Short Form-12. Interpretability included the calculation of the distribution of scores, floor and ceiling effects, and the minimal clinically important difference. Responsiveness was assessed by correlating the score changes with the Global Perceived Effect score.

RESULTS

Of 294 patients, 246 (84%) were female. The median age was 21 years (interquartile range, 17 to 29 years). All WOMAC and HOOS subscores demonstrated adequate internal consistency, and none of the modified Harris hip score components did. All scores except the WOMAC stiffness score exhibited adequate validity and interpretability, with no floor and ceiling effects over 15%. For the HOOS subscores, the minimal clinically important difference was 10.3 for pain, 10.2 for symptoms, 12.6 for sports and recreation, 11.2 for quality of life, and 10.8 for activities of daily living. The minimal clinically important difference for the modified Harris hip score was 7.4. For the WOMAC subscores, the minimal clinically important difference was 10.8 for pain, 12.9 for stiffness, 10.8 for physical, and 10.4 for total. All scores demonstrated adequate responsiveness.

CONCLUSIONS

The HOOS, WOMAC, and modified Harris hip score have adequate psychometric properties for use in patients undergoing periacetabular osteotomy, with minor shortcomings. Among the scores analyzed, the HOOS appears to be the most appropriate measure of patient-reported outcome in patients undergoing periacetabular osteotomy.

CLINICAL RELEVANCE

By establishing the psychometric properties of patient-reported outcome measures for periacetabular osteotomy, this study enables a more informed choice of measures for clinical practice and research. The estimated minimal clinically important difference values will facilitate understanding the importance of change in patient-reported outcomes after a surgical procedure in a clinical setting and sample size calculation for further studies.

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.

Editorial Commentary: The Hip-Spine Connection in Patients Undergoing Hip Arthroscopy: Should We Learn From Total Hip Replacement and Counsel Patients Differently If They Have Had Previous Back Surgery?

Disorders of the adult hip and spine are common, and there is evidence that there is a hip-spine connection in patients with hip femoroacetabular impingement (FAI). Many reports have shown that patients undergoing lumbar fusion and subsequent total hip arthroplasty have a higher risk of complications and worse outcomes following total hip arthroplasty. However, there has been a paucity of research on the effect of a history of lumbar spine surgery in patients undergoing hip arthroscopy for the treatment of FAI. Variations in lumbar lordosis, pelvic incidence, tilt, and sacral slope may modify the degree of FAI, symptoms, and patient-reported outcomes following hip arthroscopy. In the future, we should continue our efforts to better understand the impact that limited range of motion in the spine has in joint mechanics of the hip and the possibility of affecting patient-reported outcomes after hip arthroscopy. Future studies incorporating novel imaging technology, such as EOS, may be an objective way of assessing the effect of abnormal spine-pelvic function in patients with hip FAI.

Arthroscopic Hip Joint Assessment can Impact the Indications for PAO Surgery

BACKGROUND

The purpose of this study was to analyze clinical, radiographic and intraoperative disease characteristics of patients with symptomatic acetabular dysplasia in which periacetabular osteotomy (PAO) was contraindicated due to advanced intraarticular findings at the time of disease staging hip arthroscopy (HA).

METHODS

A prospective cohort was used to identify all patients who were scheduled for a PAO and concomitant hip arthroscopy for the treatment of symptomatic acetabular dysplasia. From a total of 286 patients (286 hips), 11 patients (11 hips) were identified in whom the PAO was contraindicated due to the intraarticular findings of a disease-staging hip arthroscopy. Clinical characteristics, radiographic and intraoperative findings were analyzed and compared to those patients in whom the joint was judged to be appropriate for PAO surgery.

RESULTS

11 patients (11/286 or 4%), in whom a PAO was contraindicated after joint assessment with HA, were identified and included in this study. There were nine females and two males. All patients were potential candidates for PAO surgery. The PAO was contraindicated in these cases due to severe articular cartilage damage on both the femoral head and acetabulum. The patients when compared to those in which the PAO was performed, were significantly older (42.3 years (IQR, 38.1-46.8) vs. 24 years (IQR, 19-34)) (p<0.001) and had more severe dysplasia with a lower median lateral center-edge angle (LCEA, 12.9° vs. 17.7°, p=0.001) and lower anterior center-edge angle (ACE, 14.4° vs. 20.3°, p=0.021).

CONCLUSIONS

Patients in which the PAO was contraindicated, compared to those in which PAO was performed, were older and had significant more severe dysplasia. The main cause of intraoperative disqualification for PAO was advanced articular cartilage disease.Level of Evidence: IV.

Photopolymerizable Injectable Cartilage Mimetic Hydrogel for the Treatment of Focal Chondral Lesions: A Proof of Concept Study in a Rabbit Animal Model

BACKGROUND

In this study, we investigate the in vitro and in vivo chondrogenic capacity of a novel photopolymerizable cartilage mimetic hydrogel, enhanced with extracellular matrix analogs, for cartilage regeneration.

PURPOSE

To (1) determine whether mesenchymal stem cells (MSCs) embedded in a novel cartilage mimetic hydrogel support in vitro chondrogenesis, (2) demonstrate that the proposed hydrogel can be delivered in situ in a critical chondral defect in a rabbit model, and (3) determine whether the hydrogel with or without MSCs supports in vivo chondrogenesis in a critical chondral defect.

STUDY DESIGN

Controlled laboratory study.

METHODS

Rabbit bone marrow-derived MSCs were isolated, expanded, encapsulated in the hydrogel, and cultured in chondrogenic differentiation medium for 9 weeks. Compressive modulus was evaluated at day 1 and at weeks 3, 6, and 9. Chondrogenic differentiation was investigated via quantitative polymerase reaction, safranin-O staining, and immunofluorescence. In vivo, a 3 mm-wide × 2-mm-deep chondral defect was created bilaterally on the knee trochlea of 10 rabbits. Each animal had 1 defect randomly assigned to be treated with hydrogel with or without MSCs, and the contralateral knee was left untreated. Hence, each rabbit served as its own matched control. Three groups were established: group A, hydrogel (n = 5); group B, hydrogel with MSCs (n = 5); and group C, control (n = 10). Repair tissue was evaluated at 6 months after intervention.

RESULTS

In vitro, chondrogenesis and the degradable behavior of the hydrogel by MSCs were confirmed. In vivo, the hydrogel could be delivered intraoperatively in a sterile manner. Overall, the hydrogel group had the highest scores on the modified O'Driscoll scoring system (group A, 17.4 ± 4.7; group B, 13 ± 3; group C, 16.7 ± 2.9) ( P = .11) and showed higher safranin-O staining (group A, 49.4% ± 20%; group B, 25.8% ± 16.4%; group C, 36.9% ± 25.2%) ( P = .27), although significance was not detected for either parameter.

CONCLUSION

This study provides the first evidence of the ability to photopolymerize this novel hydrogel in situ and assess its ability to provide chondrogenic cues for cartilage repair in a small animal model. In vitro chondrogenesis was evident when MSCs were encapsulated in the hydrogel.

CLINICAL RELEVANCE

Cartilage mimetic hydrogel may offer a tissue engineering approach for the treatment of osteochondral lesions.

Concurrent femoral head reduction and periacetabular osteotomies for the treatment of severe femoral head deformities

AIMS

The aims of this study were to review the surgical technique for a combined femoral head reduction osteotomy (FHRO) and periacetabular osteotomy (PAO), and to report the short-term clinical and radiological results of a combined FHRO/PAO for the treatment of selected severe femoral head deformities.

PATIENTS AND METHODS

Between 2011 and 2016, six female patients were treated with a combined FHRO and PAO. The mean patient age was 13.6 years (12.6 to 15.7). Clinical data, including patient demographics and patient-reported outcome scores, were collected prospectively. Radiologicalally, hip morphology was assessed evaluating the Tönnis angle, the lateral centre to edge angle, the medial offset distance, the extrusion index, and the alpha angle.

RESULTS

The mean follow-up was 3.3 years (2 to 4.6). The modified Harris Hip Score improved by 33.0 points from 53.5 preoperatively to 83.4 postoperatively (p = 0.03). The Western Ontario McMasters University Osteoarthritic Index score improved by 30 points from 62 preoperatively to 90 postoperatively (p = 0.029). All radiological parameters showed significant improvement. There were no long-term disabilities and none of the hips required early conversion to total hip arthroplasty.

CONCLUSION

FHRO combined with a PAO resulted in clinical and radiological improvement at short-term follow-up, suggesting it may serve as an appropriate salvage treatment option for selected young patients with severe symptomatic hip deformities.

Proceedings of the signature series symposium "cellular therapies for orthopaedics and musculoskeletal disease proven and unproven therapies-promise, facts and fantasy," international society for cellular therapies, montreal, canada, may 2, 2018

The Signature Series Symposium "Cellular Therapies for Orthopaedics and Musculoskeletal Disease Proven and Unproven Therapies-Promise, Facts and Fantasy" was held as a pre-meeting of the 26^th International Society for Cellular Therapy (ISCT) annual congress in Montreal, Canada, May 2, 2018. This was the first ISCT program that was entirely dedicated to the advancement of cell-based therapies for musculoskeletal diseases. Cellular therapies in musculoskeletal medicine are a source of great promise and opportunity. They are also the source of public controversy, confusion and misinformation. Patients, clinicians, scientists, industry and government share a commitment to clear communication and responsible development of the field. Therefore, this symposium convened thought leaders from around the world in a forum designed to catalyze communication and collaboration to bring the greatest possible innovation and value to patients with musculoskeletal conditions.

Trends of hip arthroscopy in the setting of acetabular dysplasia

Hip arthroscopy is increasingly utilized in the treatment of symptomatic intra-articular hip pathology. Unaddressed development dysplasia of the hip (DDH) is thought to be associated with failure after hip arthroscopy. The aims of this study were (i) to identify the prevalence of previous failed hip arthroscopy in patients undergoing a periactebaular osteotomy (PAO) for the treatment of symptomatic acetabular dysplasia, (ii) report on the temporal trend of failed ipsilateral hip arthroscopy in patients undergoing PAO and (iii) to determine clinical and radiographic characteristics associated with utilization of isolated hip arthroscopy in patients with acetabular dysplasia. We identified 139 patients undergoing PAO who had a history of a prior ipsilateral hip arthroscopy. A comparison group of 1505 patients with a diagnosis of acetabular dysplasia, who underwent PAO alone without any prior ipsilateral surgery during the study period was used. Clinical characteristics, radiographic and intraoperative findings were compared between cohorts. From 2008 to 2015, the rate of previous failed hip arthroscopy in patients undergoing subsequent PAO increased steadily until 2013 with a maximum of 12%. Patients in the study group had mild dysplasia with significantly higher LCEA (17.2° versus 11.3°; P < 0.001) and ACEA (15.6° versus 10.8°; P < 0.001), a lower acetabular inclination (14.0° versus 19.0°; P < 0.001). The findings illustrate a constant increase in the rate of failed hip arthroscopy in the setting of acetabular dysplasia from 2008 till 2013. Female sex and mild dysplasia were associated with use of isolated hip arthroscopy in the setting of acetabular dysplasia.

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.

Arthroscopic Management for Acetabular Rim Stress Fracture and Osteochondritis Dissecans in the Athlete With Hip Dysplasia

Intra-articular lesions are common in patients with acetabular hip dysplasia. Rim stress fractures (RSFs) have also been described in patients with acetabular hip dysplasia. This lesion is believed to be a result of an unfused secondary ossification center or a stress fracture that could be caused by repetitive impingement of an abnormal-shaped femoral head-neck junction. In addition, osteochondritis dissecans of the acetabulum is a rare condition that can also result from impingement and has been described in patients with hip dysplasia. Here, we describe an arthroscopic technique for internal fixation of osteochondritis dissecans of the acetabulum and concomitant RSF associated with hip dysplasia in a rhythmic gymnast.

A Stereolithography-Based 3D Printed Hybrid Scaffold for In Situ Cartilage Defect Repair

Damage to articular cartilage can over time cause degeneration to the tissue surrounding the injury. To address this problem, scaffolds that prevent degeneration and promote neotissue growth are needed. A new hybrid scaffold that combines a stereolithography-based 3D printed support structure with an injectable and photopolymerizable hydrogel for delivering cells to treat focal chondral defects is introduced. In this proof of concept study, the ability to a) infill the support structure with an injectable hydrogel precursor solution, b) incorporate cartilage cells during infilling using a degradable hydrogel that promotes neotissue deposition, and c) minimize damage to the surrounding cartilage when the hybrid scaffold is placed in situ in a focal chondral defect in an osteochondral plug that is cultured under mechanical loading is demonstrated. With the ability to independently control the properties of the structure and the injectable hydrogel, this hybrid scaffold approach holds promise for treating chondral defects.

Current and novel injectable hydrogels to treat focal chondral lesions: Properties and applicability

Focal chondral lesions and early osteoarthritis (OA) are responsible for progressive joint pain and disability in millions of people worldwide, yet there is currently no surgical joint preservation treatment available to fully restore the long term functionality of cartilage. Limitations of current treatments for cartilage defects have prompted the field of cartilage tissue engineering, which seeks to integrate engineering and biological principles to promote the growth of new cartilage to replace damaged tissue. Toward improving cartilage repair, hydrogel design has advanced in recent years to improve their utility. Injectable hydrogels have emerged as a promising scaffold due to their wide range of properties, the ability to encapsulate cells within the material, and their ability to provide cues for cell differentiation. Some of these advances include the development of improved control over in situ gelation (e.g., light), new techniques to process hydrogels (e.g., multi-layers), and better incorporation of biological signals (e.g., immobilization, controlled release, and tethering). This review summarises the innovative approaches to engineer injectable hydrogels toward cartilage repair. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:64-75, 2018.

Biological treatment of the knee with platelet-rich plasma or bone marrow aspirate concentrates

- Knee pathologies including focal cartilage injuries, osteoarthritis (OA), and ligament injuries are common. The poor regeneration and healing potential of cartilage has led to the search for other treatment modalities with improved healing capacity. Furthermore, with an increasing elderly population that desires to remain active, the burden of knee pathologies is expected to increase. Increased sports participation and the desire to return to activities faster is also demanding more effective and minimally invasive treatment options. Thus, the use of biologic agents in the treatment of knee pathologies has emerged as a potential option. Despite the increasing use of biologic agents for knee pathology, there are conflicting results on the efficacy of these products. Furthermore, strong data supporting the optimal preparation methods and composition for widely used biologic agents, such as platelet-rich plasma (PRP) and bone marrow aspirate concentrate (BMAC), largely remain absent from the literature. This review presents the literature on the most commonly employed biologic agents for the different knee pathologies.

Innovations in Joint Preservation Procedures for the Dysplastic Hip "The Periacetabular Osteotomy"

The Bernese periacetabular osteotomy is an effective treatment for symptomatic developmental dysplasia in the prearthritic young adult hip. Refinements in the periacetabular osteotomy technique and perioperative management have markedly improved the clinical outcomes and recovery in these patients. We will review the clinical presentation of acetabular dysplasia, indications for surgery, perioperative management, and contemporary refinements in technique including refined acetabular reduction, adjunctive hip arthroscopy, femoral head-neck osteochondroplasty, femoral procedures, and rapid recovery protocols. In well-selected patients, this reconstructive osteotomy should be considered safe and effective in alleviating pain and improving hip function in patients with symptomatic acetabular dysplasia.

Viability and Tissue Quality of Cartilage Flaps From Patients With Femoroacetabular Hip Impingement: A Matched-Control Comparison

Background:

Chondrolabral damage is commonly observed in patients with cam-type femoroacetabular impingement (FAI). Chondral flap reattachment has recently been proposed as a possible preservation technique.

Purpose/Hypothesis:

The purpose of this study was to determine the viability and tissue quality of chondral flaps from patients with FAI at the time of arthroscopy. It was hypothesized that chondral flaps from patients with cam lesions of the hip would exhibit less viability and greater tissue degeneration than would those of a matched control group.

Study Design:

Cohort study; Level of evidence, 2.

Methods:

Patients with cam-type FAI who were treated with hip arthroscopy between 2014 and 2016 were asked to participate in this study. The cartilage lesions were localized and classified intraoperatively according to Beck classification. A chondral flap (study group) and a cartilage sample (control group) were obtained from each patient for histologic evaluation. Cellular viability and tissue quality were examined and compared in both groups. Cellular viability was determined with live/dead staining, and tissue quality was evaluated using safranin O/fast green, hematoxylin and eosin (H&E) staining, and immunohistochemistry for collagen II. Osteoarthritis Research Society International (OARSI) grading was used for quality assessment, and Image J software was used to calculate the percentage of tissue viability and Col II stain.

Results:

A total of 10 male patients with a mean age of 38.4 years (range, 30-55 years) were enrolled. All chondral flaps were classified as Beck grade 4. The mean cellular viability of the chondral flaps was reduced (54.6% ± 25.6%), and they were found to be degenerated (OARSI grade, 4 ± 1.27). Control samples also had reduced viability (38.8% ± 30.3%) and were degenerative (OARSI grade, 3.5 ± 1.38). There was no statistically significant intergroup difference for viability (P = .203) or OARSI grade (P = .645), nor was there an intragroup correlation between viability and OARSI grade (P > .05). A significant negative correlation (r = −0.9, P = .035) was found between OARSI grade and collagen II percentage scale in 5 selected samples.

Conclusion:

Despite appearing normal macroscopically, the chondral flaps from patients with cam-type FAI displayed loss of viability and tissue degeneration. In addition, control samples obtained away from the injury area also displayed cartilage damage and degeneration. Careful consideration should be taken when attempting to reattach the chondral flap.

Analysis of Cell Therapies Used in Clinical Trials for the Treatment of Osteonecrosis of the Femoral Head: A Systematic Review of the Literature

BACKGROUND

Osteonecrosis of the femoral head (ONFH) is associated with regional loss of cells within bone, often resulting in pain and mechanical collapse. Our purpose was to analyze the cell-therapies used in clinical trials for the treatment of ONFH with regard to (1) cell-sources, (2) collection techniques, (3) cell-processing, (4) qualitative and quantitative characterizations, and (5) delivery methods.

METHODS

A systematic review of the current literature on the use of cell therapies for the treatment of ONFH was performed. Studies with a level-of-evidence III or higher were evaluated. A total of 1483 articles were screened. Eleven studies met the criteria to be included in this review.

RESULTS

Ten studies used bone-marrow, and 1 study used blood as the cell-source. Nine studies used freshly isolated tissue-derived nucleated cells from bone-marrow, mixed bone marrow-derived nucleated cells, 1 study used mixed blood-derived nucleated cells, and 1 study used culture-expanded cells derived from bone marrow aspirate. Cell dose varied from 2-million to 3-billion cells. Qualitative cell characterization of injected cells using surface markers was done by 5 studies using CD34. Two studies assayed the cell-population using a colony-forming-unit assay.

CONCLUSION

There is a lack of standardization with respect to the quantitative and qualitative characterization of methods for cell-harvest, cell-processing, and cell-transplantation/delivery. Cell-therapy holds promise as a means of restoring local cell populations that are made deficient because of injury or disease. However, the orthopedic community and patients will benefit greatly by a greater investment in blinded, randomized, controlled trials and clinical effectiveness trials that embrace rigorous standards.

Evidence for the Use of Cell-Based Therapy for the Treatment of Osteonecrosis of the Femoral Head: A Systematic Review of the Literature

BACKGROUND

Cell-therapy has been promoted among the therapeutic arsenal that can aid in bone formation and remodeling, in early stages of osteonecrosis of the femoral head (ONFH). The purpose of this systematic review was to assess the evidence supporting the (1) clinical efficacy; (2) structural modifying effect, as evaluated radiographically; (3) revision rates; and (4) safety of cell-therapy for the treatment of ONFH.

METHODS

A systematic review was performed including studies with a level-of-evidence of III or higher. A total of 1483 articles were screened. Eleven studies met the criteria for inclusion in this review (level-of-evidence: 6 level-I, 1 level-II, and 4 level-III), including 683 cases of ONFH.

RESULTS

All 10 studies that reported patient-reported outcomes showed improved outcomes in the cell-therapy groups compared with the control group. Overall, 24.5% (93/380 hips) that received cell-therapy showed radiographic progression compared with 40% (98/245 hips) in the control group. Nine of 10 studies that reported failure rates showed a lower total hip arthroplasty conversion rate in the cell-therapy group 16% (62/380 hips) compared with the control group 21% (52/252 hips). There was a low complication rate (<3%) with no major adverse effects.

CONCLUSION

Cell-therapies for the treatment of ONFH have been reported to be safe and suggest improved clinical outcomes with lower disease progression rate. However, there was substantial heterogeneity in the included studies, and in the cell-based therapies used. Specific clinical indications and cell-therapy standardization are required because studies varied widely with respect to cell sourcing, cell characterization, adjuvant therapies, and assessment of outcomes.