Static and dynamic mechanical causes of hip pain

Return to Play Following Hip Arthroscopy

Femoroacetabular impingement may be particularly disabling to the high-demand athlete, especially those with significant cutting and pivoting requirements. If nonoperative treatment fails to adequately alleviate symptoms or sufficiently restore function in the athlete, hip arthroscopy can lead to improved pain, improved range of motion, and high rates of return to play with proper postoperative rehabilitation. The rate of return to previous level of competition is also high with accurate diagnosis and well-executed correction of deformity. A clear understanding of the etiology, diagnosis, management, and outcomes is essential for clinicians to optimally help patients to return to play.

Quantification and correlation of hip capsular volume to demographic and radiographic predictors

PURPOSE

The purpose of this study was to develop a novel method to quantify hip capsular volume in patients undergoing hip arthroscopic surgery, utilizing magnetic resonance arthrogram (MRA) and to determine whether there are demographic or radiological factors that are associated with capsular volume.

METHODS

A retrospective review was performed from 2006 to 2014 of consecutive patients who presented with hip pain and received a hip MRA and plain radiographs. All patients were suspected of soft tissue injury due to underlying femoroacetabular impingement (FAI). A novel technique using Osirix MD for the quantification of capsular and femoral head volumes was described.

RESULTS

Ninety-seven patients met the study criteria and were included for analysis. The average total capsular volume (including the femoral head) measured 79.89 ± 20.35 cm(3), average femoral head volume 46.68 ± 12.32 cm(3), and average true capsular volume measured 33.20 ± 12.58 cm(3). Average total capsular:femoral head volume ratio was 1.74 ± 0.27. Significant differences were seen between genders for total capsular volume (P < 0.01), femoral head volume (P < 0.01), and true capsular volume (P < 0.01). Total capsular volume:femoral head ratio was greater for females, but was not statistically significant (n.s.). Femoral head volume significantly correlated with alpha angle (P < 0.01), height (P < 0.01), BMI (P < 0.01), BMI (P = 0.02), and age (P < 0.01). Total capsular volume significantly correlated with height (P < 0.01), BMI (P = 0.01), and age (P < 0.01). Age was also correlated with true capsular volume (P = 0.011). No significant differences in capsular volumes were found between normal and abnormal radiographic measurements.

CONCLUSION

The current study describes a reproducible radiographic measurement for hip capsule volumes from MRAs. Only gender was predictive of total capsular volume, femoral head volume, and true capsular volume. There were no macroscopic anatomical differences evident on MRA. This method showed good intra- and inter-observer reliability and can aid in future research regarding hip capsule volumes. This novel technique may potentially allow clinicians a readily available and reliable method to detect large and redundant capsules, a possible predisposition for hip micro-instability.

LEVEL OF EVIDENCE

Retrospective case series, Level IV.

Restriction in hip internal rotation is associated with an increased risk of ACL injury

PURPOSE

Evidence suggests that femoroacetabular impingement (FAI) in athletes may increase the risk of anterior cruciate ligament (ACL) injury. This study correlates ACL injury with hip range of motion in a consecutive series of elite, contact athletes and tests the hypothesis that a restriction in the available hip axial rotation in a dynamic in silico model of a simulated pivot landing would increase ACL strain and the risk of ACL rupture.

METHODS

Three hundred and twenty-four football athletes attending the 2012 NFL National Invitational Camp were examined. Hip range of internal rotation was measured and correlated with a history of ACL injury and surgical repair. An in silico biomechanical model was used to study the effect of FAI on the peak relative ACL strain developed during a simulated pivot landing.

RESULTS

The in vivo results demonstrated that a reduction in internal rotation of the left hip was associated with a statistically significant increased odds of ACL injury in the ipsilateral or contralateral knee (OR 0.95, p = 0.0001 and p < 0.0001, respectively). A post-estimation calculation of odds ratio for ACL injury based on deficiency in hip internal rotation demonstrated that a 30-degree reduction in left hip internal rotation was associated with 4.06 and 5.29 times greater odds of ACL injury in the ipsilateral and contralateral limbs, respectively. The in silico model demonstrated that FAI systematically increased the peak ACL strain predicted during the pivot landing.

CONCLUSION

FAI may be associated with ACL injury because of the increased resistance to femoral internal axial rotation during a dynamic maneuver such as a pivot landing. This insight may lead to better interventions to prevent ACL injury and improved understanding of ACL reconstruction failure.

LEVEL OF EVIDENCE

Cohort study, Level IV.

Prevalence of Cam-Type Morphology in Elite Ice Hockey Players

BACKGROUND

Femoroacetabular impingement (FAI) has been increasingly recognized as a cause of hip pain in athletes at all levels of competition, specifically ice hockey players.

PURPOSE/HYPOTHESIS

The purpose of this study was to define the prevalence of cam and pincer radiographic deformity in elite ice hockey players. The hypothesis was that elite hockey players will have a higher prevalence of radiographic hip abnormalities compared with the general population.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Anteroposterior and frog-leg lateral radiographs on 137 elite ice hockey players were prospectively obtained during the 2014-2015 preseason entrance examinations. Study participants included National Hockey League roster players as well as the respective farm team members. Demographic data were collected, including age, position, shooting side, and any history of hip pain or hip surgery. Patients with a history of hip surgery were excluded from the analysis. A single sports medicine fellowship-trained orthopaedic surgeon used standard radiographic measurements to assess for the radiographic presence of cam or pincer deformity. Radiographs with an alpha angle ≥55° on a frog-leg lateral view were defined as cam-positive. Each participant underwent a preseason physical examination with an assessment of hip range of motion and impingement testing.

RESULTS

A total of 130 elite ice hockey players were included in the analysis; 180 (69.4%) hips met radiographic criteria for cam-type deformity. The prevalence in right and left hips was 89 (69.5%) and 91 (70.0%), respectively; 70 (60.8%) players demonstrated bilateral involvement. Hips with cam deformity had a mean alpha angle of 67.7° ± 8.3° on the right and 68.9° ± 9.0° on the left. Of the patients with alpha angles ≥55°, 5.6% (5/89) had a positive anterior impingement test of the right hip, while 11% (10/91) had positive anterior impingement test of the left. Players with radiologic cam deformity had a statistically significant deficit in external rotation of the right hip, as well as in both internal and external rotation of the left hip, compared with those with normal alpha angles. When assessing for crossover sign, 64 of 107 (59.8%) had a positive radiographic finding. Forty-one players (38.3%) had evidence of a crossover sign of the right hip and 42 (39.3%) of the left. When comparing position players, goalies had the highest prevalence of cam-type deformity (93.8%) and the least acetabular coverage.

CONCLUSION

The study data suggest that elite ice hockey players have a significantly higher prevalence of radiographic cam deformity in comparison to what has been reported for the general population.

Differences in anatomical parameters between the affected and unaffected hip in patients with bilateral cam-type deformities

BACKGROUND

It is still unclear why many individuals with bilateral cam deformities demonstrate only unilateral symptoms of femoroacetabular impingement, thus symptoms may be attributed to additional anatomical parameters. The purpose was to examine patients with bilateral cam deformities, with unilateral symptoms, and compare anatomical hip joint parameters between their affected (symptomatic) hip and their contralateral, unaffected (asymptomatic) hip.

METHODS

Twenty participants (n=20) with unilateral symptoms, but bilateral cam deformities, underwent CT imaging to measure their affected and unaffected hip's: axial and radial alpha angles, femoral head-neck offset, femoral neck-shaft angle, medial proximal femoral angle, femoral torsion, acetabular version, center-edge angle; and a physical examination (hip flexion, straight-leg raise, internal rotation, external rotation) to ascertain clinical signs.

FINDINGS

The affected hips demonstrated limited motions during physical examination, compared with unaffected hips (effect size=0.550 to 0.955). The affected hips had significantly lower femoral neck-shaft angles (mean 125° (SD 3)) and lower medial proximal femoral angles (mean 79° (SD 4)), compared with the unaffected hips (mean 127° (SD 3), P=0.001, effect size=0.922; and mean 81° (SD 4), P=0.011, effect size=0.632; respectively). There were no differences in cam deformity parameters (axial and radial alpha angles, femoral head-neck offset), femoral torsion, acetabular version, and center-edge angle, between affected and unaffected hips.

INTERPRETATION

A decreased femoral neck-shaft angle or medial proximal femoral angle can be implemented as a diagnostic predictor, to determine which hip may be at a greater risk of developing early symptoms.

Open-MRI measures of cam intrusion for hips in an anterior impingement position relate to acetabular contact force

Open MRI in functional positions has potential to directly and non-invasively assess cam femoroacetabular impingement (FAI). Our objective was to investigate whether open MRI can depict intrusion of the cam deformity into the intra-articular joint space, and whether intrusion is associated with elevated acetabular contact force. Cadaver hips (9 cam; 3 controls) were positioned in an anterior impingement posture and imaged using open MRI with multi-planar reformatting. The β-angle (describing clearance between the femoral neck and acetabulum) was measured around the entire circumference of the femoral neck. We defined a binary "MRI cam-intrusion sign" (positive if β < 0°). We then instrumented each hip with a piezoresistive sensor and conducted six repeated positioning trials, measuring acetabular contact force (F). We defined a binary "contact-force sign" (positive if F > 20N). Cam hips were more likely than controls to have both a positive MRI cam-intrusion sign (p = 0.0182, Fisher's exact test) and positive contact-force sign (p = 0.0083), which represents direct experimental evidence for cam intrusion. There was also a relationship between the MRI cam-intrusion sign and contact-force sign (p = 0.033), representing a link between imaging and mechanics. Our findings indicate that open MRI has significant potential for in vivo investigation of the cam FAI mechanism.

Current Concepts in Hip Preservation Surgery: Part II--Rehabilitation

CONTEXT

Successful treatment of nonarthritic hip pain in young athletic individuals remains a challenge. A growing fund of clinical knowledge has paralleled technical innovations that have enabled hip preservation surgeons to address a multitude of structural variations of the proximal femur and acetabulum and concomitant intra-articular joint pathology. Often, a combination of open and arthroscopic techniques are necessary to treat more complex pathomorphologies. Peri- and postoperative recovery after such procedures can pose a substantial challenge to the patient, and a dedicated, thoughtful approach may reduce setbacks, limit morbidity, and help optimize functional outcomes.

EVIDENCE ACQUISITION

PubMed and CINAHL databases were searched to identify relevant scientific and review articles through December 2014 using the search terms hip preservation, labrum, surgical dislocation, femoroacetabular impingement, postoperative rehabilitation, peri-acetabular osteotomy, and rotational osteotomy. Reference lists of included articles were reviewed to locate additional references of interest.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 4.

RESULTS

Hip preservation procedures and appropriate rehabilitation have allowed individuals to return to a physically active lifestyle.

CONCLUSION

Effective postoperative rehabilitation must consider modifications and precautions specific to the particular surgical techniques used. Proper postoperative rehabilitation after hip preservation surgery may help optimize functional recovery and maximize clinical success and patient satisfaction.

MRI for the preoperative evaluation of femoroacetabular impingement

Femoroacetabular impingement (FAI) refers to a condition characterized by impingement of the femoral head–neck junction against the acetabular rim, often due to underlying osseous and/or soft tissue morphological abnormalities. It is a common cause of hip pain and limited range of motion in young and middle-aged adults. Hip preservation surgery aims to correct the morphological variants seen in FAI, thereby relieving pain and improving function, and potentially preventing early osteoarthritis. The purpose of this article is to review the mechanisms of chondral and labral injury in FAI to facilitate an understanding of patterns of chondrolabral injury seen on MRI. Preoperative MRI evaluation of FAI should include assessment of osseous morphologic abnormalities, labral tears, cartilage status, and other associated compensatory injuries of the pelvis. As advanced chondral wear is the major relative contraindication for hip preservation surgery, MRI is useful in the selection of patients likely to benefit from surgery.

Teaching points

• The most common anatomical osseous abnormalities predisposing to FAI include cam and pincer lesions.

• Morphological abnormalities, labral lesions, and cartilage status should be assessed.

• In cam impingement, chondral wear most commonly occurs anterosuperiorly.

• Pre-existing advanced osteoarthritis is the strongest predictor of poor outcomes after FAI surgery.

• Injury to muscles and tendons or other pelvic structures can coexist with FAI.

Sonographic prevalence of groin hernias and adductor tendinopathy in patients with femoroacetabular impingement

BACKGROUND

Femoroacetabular impingement (FAI) is a common debilitating condition that is associated with groin pain and limitation in young and active patients. Besides FAI, various disorders such as hernias, adductor tendinopathy, athletic pubalgia, lumbar spine affections, and others can cause similar symptoms.

PURPOSE

To determine the prevalence of inguinal and/or femoral herniation and adductor insertion tendinopathy using dynamic ultrasound in a cohort of patients with radiographic evidence of FAI.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This retrospective study consisted of 74 patients (36 female and 38 male; mean age, 29 years; 83 symptomatic hips) with groin pain and radiographic evidence of FAI. In addition to the usual diagnostic algorithm, all patients underwent a dynamic ultrasound examination for signs of groin herniation and tendinopathy of the proximal insertion of the adductors.

RESULTS

Evidence of groin herniation was found in 34 hips (41%). There were 27 inguinal (6 female, 21 male) and 10 femoral (9 female, 1 male) hernias. In 3 cases, inguinal and femoral herniation was coexistent. Overall, 5 patients underwent subsequent hernia repair. Patients with groin herniation were significantly older than those without (33 vs 27 years, respectively; P = .01). There were no significant differences for any of the radiographic or clinical parameters. Tendinopathy of the proximal adductor insertion was detected in 19 cases (23%; 11 female, 8 male). Tendinopathy was coexistent with groin herniation in 8 of the 19 cases. There were no significant differences for any of the radiographic or clinical parameters between patients with or without tendinopathy. Patients with a negative diagnostic hip injection result were more likely to have a concomitant groin hernia than those with a positive injection result (80% vs 27%, respectively). Overall, 38 hips underwent FAI surgery with satisfactory outcomes in terms of score values and subjective improvement.

CONCLUSION

The results demonstrate that groin herniation and adductor insertion tendinopathy coexist frequently in patients with FAI. Although the clinical effect is yet unclear, 5 patients underwent hernia repair. Dynamic ultrasound is a useful tool to detect such pathological abnormalities. Diagnostic hip injections can be helpful to differentiate between the sources of pain.

Risk of anterior cruciate ligament fatigue failure is increased by limited internal femoral rotation during in vitro repeated pivot landings

BACKGROUND

A reduced range of hip internal rotation is associated with increased peak anterior cruciate ligament (ACL) strain and risk for injury. It is unknown, however, whether limiting the available range of internal femoral rotation increases the susceptibility of the ACL to fatigue failure.

HYPOTHESIS

Risk of ACL failure is significantly greater in female knee specimens with a limited range of internal femoral rotation, smaller femoral-ACL attachment angle, and smaller tibial eminence volume during repeated in vitro simulated single-leg pivot landings.

STUDY DESIGN

Controlled laboratory study.

METHODS

A custom-built testing apparatus was used to simulate repeated single-leg pivot landings with a 4×-body weight impulsive load that induces knee compression, knee flexion, and internal tibial torque in 32 paired human knee specimens from 8 male and 8 female donors. These test loads were applied to each pair of specimens, in one knee with limited internal femoral rotation and in the contralateral knee with femoral rotation resisted by 2 springs to simulate the active hip rotator muscles' resistance to stretch. The landings were repeated until ACL failure occurred or until a minimum of 100 trials were executed. The angle at which the ACL originates from the femur and the tibial eminence volume were measured on magnetic resonance images.

RESULTS

The final Cox regression model (P = .024) revealed that range of internal femoral rotation and sex of donor were significant factors in determining risk of ACL fatigue failure. The specimens with limited range of internal femoral rotation had a failure risk 17.1 times higher than did the specimens with free rotation (P = .016). The female knee specimens had a risk of ACL failure 26.9 times higher than the male specimens (P = .055).

CONCLUSION

Limiting the range of internal femoral rotation during repetitive pivot landings increases the risk of an ACL fatigue failure in comparison with free rotation in a cadaveric model.

CLINICAL RELEVANCE

Screening for restricted internal rotation at the hip in ACL injury prevention programs as well as in individuals with ACL injuries and/or reconstructions is warranted.

Hip Arthroscopy in High-Level Baseball Players

PURPOSE

To report the results of hip arthroscopy among high-level baseball players as recorded by outcome scores and return to baseball.

METHODS

All patients undergoing hip arthroscopy were prospectively assessed with the modified Harris Hip Score. On review of all procedures performed over a 12-year period, 44 hips were identified among 41 intercollegiate or professional baseball players who had achieved 2-year follow-up.

RESULTS

Among the 41 players, follow-up averaged 45 months (range, 24 to 120 months), with a mean age of 23 years (range, 18 to 34 years). There were 23 collegiate (1 bilateral) and 18 professional (2 bilateral) baseball players, including 10 Major League Baseball players. Of the 8 Major League Baseball pitchers, 6 (75%) also underwent ulnar collateral ligament elbow surgery. Improvement in the modified Harris Hip Score averaged 13 points (from 81 points preoperatively to 94 points postoperatively); a paired-samples t test determined that this mean improvement of 13 points was statistically significant (P < .001). Players returned to baseball after 42 of 44 procedures (95%) at a mean of 4.3 months (range, 3 to 8 months), with 90% regaining the ability to participate at their previous level of competition. There were no complications. Three players (1 bilateral) underwent repeat arthroscopy.

CONCLUSIONS

This study supports the idea that arthroscopic treatment for a variety of hip pathologies in high-level baseball players provides a successful return to sport and improvement in functional outcome scores.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Hip pain in dancers

Dancers require extreme ranges of motion in their hips. They require this for many styles and performances. Hip pain and hip injury in dancers can lead to lost work and performance time. There are many potential causes for hip pain in the dancer, including dysplasia, hyperlaxity, both intra- and extra-articular impingement, and soft tissue injuries. This article will review the current literature on these topics in dancers and how they can be applied to the dancer patient.

The Hyperflexible Hip: Managing Hip Pain in the Dancer and Gymnast

Context:

Dance, gymnastics, figure skating, and competitive cheerleading require a high degree of hip range of motion. Athletes who participate in these sports use their hips in a mechanically complex manner.

Evidence Acquisition:

A search of the entire PubMed database (through December 2013) and additional searches of the reference lists of pertinent articles.

Study Design:

Systematic review.

Level of Evidence:

Level 3.

Results:

Whether innate or acquired, dancers and gymnasts have some hypermobility that allows their hips to be placed in potentially impinging or unstable positions required for their given activity. Such extremes of motion can result in both intra-articular and extra-articular impingement as well as compensatory osseous and muscular pathology. In addition, dancers and gymnasts are susceptible to impingement-induced instability. Dancers with innate generalized hyperlaxity are at increased risk of injury because of their activities and may require longer recovery times to return to play. Both nonoperative and operative treatments (arthroscopic and open) have an important role in returning flexibility athletes to their preoperative levels of sport and dance.

Conclusion:

Because of the extreme hip motion required and the compensatory soft tissue laxity in dancers and gymnasts, these athletes may develop instability, impingement, or combinations of both. This frequently occurs in the setting of subtle pathoanatomy or in patients with normal bony anatomy. With appropriate surgical indications and the correct operative technique, the treating surgeon can anticipate high levels of return to play for the gymnast and dancer with hip pain.

Current Concepts in Hip Preservation Surgery: Part I

Context:

An evolution in conceptual understanding, coupled with technical innovations, has enabled hip preservation surgeons to address complex pathomorphologies about the hip joint to reduce pain, optimize function, and potentially increase the longevity of the native hip joint. Technical aspects of hip preservation surgeries are diverse and range from isolated arthroscopic or open procedures to hybrid procedures that combine the advantages of arthroscopy with open surgical dislocation, pelvic and/or proximal femoral osteotomy, and biologic treatments for cartilage restoration.

Evidence Acquisition:

PubMed and CINAHL databases were searched to identify relevant scientific and review articles from January 1920 to January 2015 using the search terms hip preservation, labrum, surgical dislocation, femoroacetabular impingement, peri-acetabular osteotomy, and rotational osteotomy. Reference lists of included articles were reviewed to locate additional references of interest.

Study Design:

Clinical review.

Level of Evidence:

Level 4.

Results:

Thoughtful individualized surgical procedures are available to optimize the femoroacetabular joint in the presence of hip dysfunction.

Conclusion:

A comprehensive understanding of the relationship between femoral and pelvic orientation, morphology, and the development of intra-articular abnormalities is necessary to formulate a patient-specific approach to treatment with potential for a successful long-term result.

Patient-specific anatomical and functional parameters provide new insights into the pathomechanism of cam FAI

BACKGROUND

Femoroacetabular impingement (FAI) represents a constellation of anatomical and clinical features, but definitive diagnosis is often difficult. The high prevalence of cam deformity of the femoral head in the asymptomatic population as well as clinical factors leading to the onset of symptoms raises questions as to what other factors increase the risk of cartilage damage and hip pain.

QUESTIONS/PURPOSES

The purpose was to identify any differences in anatomical parameters and squat kinematics among symptomatic, asymptomatic, and control individuals and if these parameters can determine individuals at risk of developing symptoms of cam FAI.

METHODS

Forty-three participants (n = 43) were recruited and divided into three groups: symptomatic (12), asymptomatic (17), and control (14). Symptomatic participants presented a cam deformity (identified by an elevated alpha angle on CT images), pain symptoms, clinical signs, and were scheduled for surgery. The other recruited volunteers were blinded and unaware whether they had a cam deformity. After the CT data were assessed for an elevated alpha angle, participants with a cam deformity but who did not demonstrate any clinical signs or symptoms were considered asymptomatic, whereas participants without a cam deformity and without clinical signs or symptoms were considered healthy control subjects. For each participant, anatomical CT parameters (axial alpha angle, radial alpha angle, femoral head-neck offset, femoral neck-shaft angle, medial proximal femoral angle, femoral torsion, acetabular version) were evaluated. Functional squat parameters (maximal squat depth, pelvic range of motion) were determined using a motion capture system. A stepwise discriminant function analysis was used to determine which of the parameters were most suitable to classify each participant with their respective subgroup.

RESULTS

The symptomatic group showed elevated alpha angles and lower femoral neck-shaft angles, whereas the asymptomatic group showed elevated alpha angles in comparison with the control group. The best discriminating parameters to determine symptoms were radial alpha angle, femoral neck-shaft angle, and pelvic range of motion (p < 0.001).

CONCLUSIONS

In the presence of a cam deformity, indications of a decreased femoral neck-shaft angle and reduced pelvic range of motion can identify those at risk of symptomatic FAI.

On-Ice Functional Assessment of an Elite Ice Hockey Goaltender After Treatment for Femoroacetabular Impingement

BACKGROUND

Femoroacetabular impingement (FAI) is a major cause of performance inhibition in elite-level athletes. The condition is characterized by pain, osseous abnormalities such as an increased alpha angle, and decreased range of motion at the affected hip joint. Arthroscopic surgical decompression is useful in reshaping the joint to alleviate symptoms. Functional kinematic outcomes of sport-specific movements after surgery, however, are presently unknown.

HYPOTHESIS

The ability of an ice hockey goaltender to execute sport-specific movements would improve after arthroscopic surgery.

STUDY DESIGN

Clinical research.

LEVEL OF EVIDENCE

Level 5.

METHODS

An ice hockey goaltender was evaluated after arthroscopic correction of FAI on the symptomatic hip. Passive range of motion and radiographic parameters were assessed from a computed tomography-derived 3-dimensional model. An on-ice motion capture system was also used to determine peak femoral shock and concurrent hip joint postures during the butterfly and braking movements.

RESULTS

Maximum alpha angles were 47° in the surgical and 61° in the nonsurgical hip. Internal rotation range of motion was, on average, 23° greater in the surgically corrected hip compared with contralateral. Peak shock was lower in the surgical hip by 1.39 g and 0.86 g during butterfly and braking, respectively. At peak shock, the surgical hip demonstrated increased flexion, adduction, and internal rotation for both tasks (butterfly, 6.1°, 12.3°, and 30.8°; braking, 14.8°, 19.2°, and 41.4°).

CONCLUSION

On-ice motion capture revealed performance differences between hips after arthroscopic surgery in a hockey goaltender. Range of motion and the patient's subjective assessment of hip function were improved in the surgical hip. While presenting as asymptomatic, it was discovered that the contralateral hip displayed measurements consistent with FAI. Therefore, consideration of preemptive treatment in a presently painless hip may be deemed beneficial for young athletes seeking a long career in sport, and future work is needed to determine the costs and benefits of such an approach.

CLINICAL RELEVANCE

Surgical treatment of symptomatic FAI can achieve pain relief and improved kinematics of the hip joint with athletic activities. Additional studies are necessary to determine whether improved kinematics enhance the longevity of the native hip and alter the progression of osteoarthritic changes in those with asymptomatic FAI deformity.

Subtrochanteric osteotomy for femoral mal-torsion through a surgical dislocation approach

Missed torsional femur deformities may contribute to reasons for failure after open and more likely arthroscopic hip preservation surgery. A number of surgical approaches have been described for addressing torsion abnormalities. This report describes a subtrochanteric osteotomy technique in a consecutive series of patients with complex hip pathologies, for which intertrochanteric osteotomy is not suitable and precise derotation is required. Subtrochanteric derotation was performed, always in combination with a surgical hip dislocation, in accordance with the authors’ preferred technique. Before osteotomy, a localized decortication was executed. Application of a 4.5-mm broad or narrow plate was undertaken with dynamic compression of the osteotomy. Twenty-eight consecutive subtrochanteric derotational osteotomies were performed in 26 patients. Twenty-one females and five males were treated at an average age of 21.4 years (range, 12–43). Underlying diagnoses included dysplasia, arthrogryposis, cerebral palsy, Down’s syndrome, instability and impingement. The decision to perform derotation was for antetorsion over 20° or less than 0° (retrotorsion). Patients were followed clinically and radiographically till final follow-up. All patients went on to successful osteotomy union. There were two initial failures: one delayed union prompting revision fixation in a chronic smoker and one plate failure due to self-accelerated weight-bearing in a patient status post successful contralateral derotational osteotomy. Rotational deformity of the femur must be considered in the patient undergoing hip preservation surgery. This technique of subtrochanteric derotational osteotomy, with adjunctive surgical hip dislocation, is applicable and reproducible in the setting of complex hip pathologies. Level of evidence: IV, case series.

Prevalence of radiographic parameters predisposing to femoroacetabular impingement in young asymptomatic Chinese and white subjects

BACKGROUND

Osteoarthritis of the hip is five to ten times more common in white people than in Chinese people. Little is known about the true prevalence of femoroacetabular impingement or its role in the development of osteoarthritis in the Chinese population. A cross-sectional study of both white and Chinese asymptomatic individuals was conducted to compare the prevalences of radiographic features posing a risk for femoroacetabular impingement in the two groups. It was hypothesized that that there would be proportional differences in hip anatomy between the white and Asian populations.

METHODS

Pelvic computed tomography scans of 201 subjects (ninety-nine white Belgians and 102 Chinese; 105 men and ninety-six women) without hip pain who were eighteen to forty years of age were assessed. The original axial images were reformatted to three-dimensional pelvic models simulating standardized radiographic views. Ten radiographic parameters predisposing to femoroacetabular impingement were measured: alpha angle, anterior offset ratio, and caput-collum-diaphyseal angle on the femoral side and crossover sign, ischial spine projection, acetabular anteversion angle, center-edge angle, acetabular angle of Sharp, Tönnis angle, and anterior acetabular head index on the acetabular side.

RESULTS

The white subjects had a less spherical femoral head than the Chinese subjects (average alpha angle, 56° compared with 50°; p<0.001). The Chinese subjects had less lateral acetabular coverage than the white subjects, with average center-edge angles of 35° and 39° (p<0.001) and acetabular angles of Sharp of 38° and 36° (p<0.001), respectively. A shallower acetabular configuration was predominantly present in Chinese women.

CONCLUSIONS

Significant differences in hip anatomy were demonstrated between young asymptomatic Chinese and white subjects. However, the absolute size of the observed differences appears to contrast with the reported low prevalence of femoroacetabular impingement in Chinese individuals compared with the high prevalence in white populations.

Protrusio acetabuli: joint loading with severe pincer impingement and its theoretical implications for surgical therapy

Severe pincer impingement (acetabular protrusio) is an established cause of hip pain and osteoarthritis. The proposed underlying pathomechanism is a dynamic pathological contact of the prominent acetabular rim with the femoral head-neck junction. However, this cannot explain the classically described medial osteoarthritis in these hips. We therefore asked: (1) Does an overload exist in the medial aspect of the protrusio joint? and (2) What is the influence of three contemporary joint-preserving procedures on load distribution in protrusio hips? In vivo force and motion data for walking and standing to sitting were applied to six 3D finite element models (normal, dysplasia, protrusio, acetabular rim trimming, acetabular reorientation, and combined reorientation/rim trimming). Compared with dysplasia, the protrusio joint resulted in opposite patterns of von Mises stress and contact pressure during walking. In protrusio hips, we found an overload at the medial margin of the lunate surface (54% higher than normal). Isolated rim trimming further increased the medial overload (up to 28% higher than protrusio), whereas acetabular reorientation with/without rim trimming reduced stresses by up to 25%. Our results can be used as an adjunct for surgical decision making in the treatment of acetabular protrusio.

Subject-specific patterns of femur-labrum contact are complex and vary in asymptomatic hips and hips with femoroacetabular impingement

BACKGROUND

Femoroacetabular impingement (FAI) may constrain hip articulation and cause chondrolabral damage, but to our knowledge, in vivo articulation and femur-labrum contact patterns have not been quantified.

PURPOSE

In this exploratory study, we describe the use of high-speed dual-fluoroscopy and model-based tracking to dynamically measure in vivo hip articulation and estimate the location of femur-labrum contact in six asymptomatic hips and three hips with FAI during the impingement examination. We asked: (1) Does femur-labrum contact occur at the terminal position of impingement? (2) Could range of motion (ROM) during the impingement examination appear decreased in hips with FAI? (3) Does the location of femur-labrum contact coincide with that of minimum bone-to-bone distance? (4) In the patients with FAI, does the location of femur-labrum contact qualitatively correspond to the location of damage observed intraoperatively?

METHODS

High-speed dual-fluoroscopy images were acquired continuously as the impingement examination was performed. CT arthrogram images of all subjects were segmented to generate three-dimensional (3-D) surfaces for the pelvis, femur, and labrum. Model-based tracking of the fluoroscopy images enabled dynamic kinematic observation of the 3-D surfaces. At the terminal position of the examination, the region of minimal bone-to-bone distance was compared with the estimated location of femur-labrum contact. Each patient with FAI underwent hip arthroscopy; the location of femur-labrum contact was compared qualitatively with damage found during surgery. As an exploratory study, statistics were not performed.

RESULTS

Femur-labrum contact was observed in both groups, but patterns of contact were subject-specific. At the terminal position of the impingement examination, internal rotation and adduction angles for each of the patients with FAI were less than the 95% confidence intervals (CIs) for the asymptomatic control subjects. The location of minimum bone-to-bone distance agreed with the region of femur-labrum contact in two of nine hips. The locations of chondrolabral damage identified during surgery qualitatively coincided with the region of femur-labrum contact.

CONCLUSIONS

Dual-fluoroscopy and model-based tracking provided the ability to assess hip kinematics in vivo during the entire impingement examination. The high variability in observed labrum-femur contact patterns at the terminal position of the examination provides evidence that subtle anatomic features could dictate underlying hip biomechanics. Although femur-labrum contact occurs in asymptomatic and symptomatic hips at the terminal position of the impingement examination, contact may occur at reduced adduction and internal rotation in patients with FAI. Use of minimum bone-to-bone distance may not appropriately identify the region of femur-labrum contact. Additional research, using a larger cohort and appropriate statistical tests, is required to confirm the findings of this exploratory study.

Factors associated with the failure of arthroscopic surgery treatment in patients with femoroacetabular impingement: A cohort study

OBJECTIVE

The aim of this study was to evaluate the association of the anatomical and functional characteristics with therapeutic failure in patients with femoroacetabular impingement, who underwent hip arthroscopy.

MATERIALS AND METHODS

A cohort study was performed on 179 patients with femoroacetabular impingement who underwent hip arthroscopy between 2004 and 2012. The demographic, anatomical, functional, and clinical information were recorded. A logistic regression model and ANCOVA were used in order to compare the described characteristics with the treatment outcomes of the hip arthroscopy.

RESULTS

The median time of follow-up for symptoms was 13 months (8-30), and the mean time of follow-up after surgery was 23.83 ± 9.8 months. At the end of the follow-up 3.91% of the patients were considered as a therapeutic failure. The WOMAC score in pain and functional branches, as well as the total WOMAC score, showed significant differences (P<.05). The mean WOMAC score was higher (0 to 100 with 0 being a perfect score) in the group of patients who failed after surgery as compared with the group who meet the requirements for a successful treatment, 65.9 vs 48.8, respectively (mean difference 17.0; 95% CI; 1.3-32.6; P=.033).

CONCLUSION

The poor functional state prior to arthroscopic treatment of femoroacetabular impingement, mainly due to preoperative pain, assessed using the WOMAC scale, is associated with a higher therapeutic failure rate.

Prevalence and characteristics of cam-type femoroacetabular deformity in 100 hips with symptomatic acetabular dysplasia: a case control study

Background

Cam-type femoroacetabular deformity in acetabular dysplasia (AD) has not been well clarified. The primary purpose of this study was to determine the prevalence and characteristics of femoroacetabular deformity in symptomatic AD patients.

Methods

We retrospectively reviewed the cases of 86 women (92 hips) and eight men (eight hips) with symptomatic AD. The mean patient age was 37.9 (range, 14–60) years. All participants underwent lateral cross-table and lateral whole-spine radiographic examinations to measure the alpha angle and pelvic tilt. Pelvic computed tomography scans were used to measure femoral anteversion. The patients were classified into two groups: AD only group, containing hips with an alpha angle less than 55°; and AD with cam-type femoroacetabular deformity (AD + cam-type deformity) group, containing hips with an alpha angle greater than or equal to 55°.

Results

Of the patients with AD, 40 hips displayed additional radiographic evidence of cam-type morphology, while 60 hips had exclusive AD morphology. The patients in the AD + cam-type deformity group had significantly increased forward pelvic tilt in the standing position (p =0.023) and decreased femoral anteversion (p =0.047) compared with the AD only group.

Conclusions

Our data revealed that 40% of patients with AD also had radiographic evidence of cam-type femoroacetabular deformity. Greater forward pelvic tilt in the standing position and decreased femoral anteversion seemed to be associated with the cam-type deformity in these patients. These results indicate the morphological features that are most likely to induce secondary symptoms to developmental hip dysplasia. It is suggested that the symptoms in the AD + cam-type deformity group could arise through femoroacetabular impingement (FAI) after periacetabular osteotomy, because a predisposition was present preoperatively.

Evaluating the quality of Internet information for femoroacetabular impingement

PURPOSE

The Internet has become a ubiquitous source of medical information for both the patient and the physician. However, the quality of this information is highly variable. We evaluated the quality of Internet information available for femoroacetabular impingement (FAI).

METHODS

Four popular search engines were used to collect 100 Web sites containing information on FAI. Web sites were evaluated based on authorship, various content criteria, and the presence of Health On the Net Code of Conduct (HONcode) certification. By use of a novel evaluation system for quality, Web sites were also classified as excellent, high, moderate, poor, or inadequate and were subsequently analyzed. Web sites were evaluated as a group, followed by authorship type, by HONcode certification, and by quality level.

RESULTS

Of the Web sites, 73 offered the ability to contact the author, 91 offered a considerable explanation of FAI, 54 provided surgical treatment options, 58 offered nonsurgical treatment options, 27 discussed possible complications, 11 discussed eligibility criteria, 31 discussed rehabilitation, 67 discussed a differential diagnosis, and 48 included peer-reviewed citations. We categorized 40 Web sites as academic, 33 as private, 9 as industry, 9 as public education, and 9 as blogs. Our novel quality evaluation system classified 16 Web sites as excellent, 18 as high, 17 as moderate, 18 as poor, and 31 as inadequate. Only 8% of all evaluated Web sites contained HONcode certification.

CONCLUSIONS

We found that the quality of information available on the Internet about FAI was dramatically variable. A significantly large proportion of Web sites were from academic sources, but this did not necessarily indicate higher quality. Sites with HONcode certification showed as much variability in quality as noncertified sites.

CLINICAL RELEVANCE

This study increases clinician competence in the available Internet information about FAI and helps them to confidently guide patients to formulate appropriate medical decisions based on high-quality information.

An increase in cranial acetabular version with age: implications for femoroacetabular impingement

This cadaveric study aimed to determine if acetabular retroversion demonstrates predictable changes with age that could inform understanding of factors that may contribute to the pathophysiology of femoroacetabular impingement. Two-hundred forty pelves were divided into young and old groups. Version was measured at the cranial (5mm below superior rim), central (transverse of acetabulum), and caudal (5mm above inferior rim) locations. The data showed a significant difference between young (10±10°) and old (13±9°) cranial version (P=.02). Cranial retroversion increases with age and may reflect a developmental component in the etiology of the focal rim impingement lesion or ossification of the damaged labrum. Global acetabular retroversion does not appear to change with age and may reflect a congenital etiology.

Femoroacetabular impingement in elite ice hockey players

PURPOSE

The purpose of this study is to evaluate the presence of clinical and radiological femoroacetabular impingement (FAI) in elite ice hockey players and compare it to a control group of non-athletes.

METHODS

Forty participants (20 non-athletes and 20 elite ice hockey athletes) underwent an evaluation of their hip joint, including assessment of range of motion and special provocative impingement tests. Two musculoskeletal radiologists assessed MRIs completed on each participant for radiological findings associated with FAI, including alpha angle, acetabular version angle, acetabular depth, and/or a lateral centre edge angle, and findings of labral and cartilage degeneration. A comparative analysis of the clinical and radiological findings was subsequently completed.

RESULTS

There was a significant difference in the radiological CAM impingement measured by mean alpha angle between both groups (non-athletes: 43.2 degrees, SD 9.7; and athletes: 54.2 degrees, SD 12 (p = 0.003)). There were no statistically significant differences between the groups upon evaluating PINCER impingement. There were no statistically significant differences in clinical examination findings between both groups.

CONCLUSION

MRI evidence suggests that CAM impingement is more common in the elite ice hockey athlete in comparison with non-athletes. However, as this is a pilot study examining findings in asymptomatic individuals, there is a need for a longitudinal prospective cohort study. In keeping with this, sufficient, long-term follow-up is required to assess at what point, if any, these subjects with radiological findings become symptomatic.

Clinical and morphologic factors associated with suture anchor refixation of labral tears in the hip

BACKGROUND

The acetabular labrum is critical to hip function. Surgical options for treatment of a damaged labrum include removal, debridement, and refixation using suture anchors.

QUESTIONS/PURPOSES

The purpose of this study is to determine if certain patient demographic and osseous morphological factors result in increased labral damage requiring refixation.

METHODS

Data was collected prospectively from a consecutive series of 334 procedures performed from August 2010 to June 2011 for femoroacetabular impingement. Demographic data, including age, sex, and race, was collected from patient charts. Three-dimensional (3D) CT scans were reviewed to retrieve alpha angles, acetabular version, femoral version, and lateral center edge angle on the symptomatic hip.

RESULTS

In 238 (71.3%) of the procedures, the labrum required refixation using suture anchors with a mean of 2.74 anchors being used. Of males, 78.8% required suture anchors and 62.3% of females required suture anchors. Among procedures requiring suture anchors, significantly more suture anchors were used in males (2.92) than females (2.47). Regression analysis showed a positive association between alpha angle, acetabular retroversion at 1 and 2 o'clock, and the number of suture anchors used. The mean alpha angle in the cohort that required suture anchors (63.1°) was significantly greater than the cohort that did not (59.4°).

CONCLUSION

This study found femoral deformities to contribute more to labral damage than acetabular deformities and highlighted the importance of preoperative 3D CT scans. This study provides demographic and morphologic factors to review preoperatively to evaluate if extensive labral damage is present and if suture anchor refixation will be required.

A review of femoroacetabular impingement and hip arthroscopy in the athlete

Femoroacetabular impingement (FAI) is increasingly recognized as a pathological condition of the hip in athletes. Although it is not always symptomatic, the bone structure leading to FAI and its associated pathology can result in significant pain and performance decline in athletes. Recognition of athletes with symptomatic FAI is of the utmost importance, as prompt treatment is necessary in order to maintain desired sports activity levels and preserve joint function. This review explores the recent evidence on the evaluation, recognition, and treatment of femoroacetabular impingement, and discusses conservative management, postoperative rehabilitation, and treatment in the pediatric and master athlete populations.

Interventions for hip pain in the maturing athlete: the role of hip arthroscopy?

Context:

Femoroacetabular impingement (FAI) alters hip mechanics, results in hip pain, and may lead to secondary osteoarthritis (OA) in the maturing athlete. Hip impingement can be caused by osseous abnormalities in the proximal femur or acetabulum. These impingement lesions may cause altered loads within the hip joint, which result in repetitive collision damage or sheer forces to the chondral surfaces and acetabular labrum. These anatomic lesions and resultant abnormal mechanics may lead to early osteoarthritic changes.

Evidence Acquisition:

Relevant articles from the years 1995 to 2013 were identified using MEDLINE, EMBASE, and the bibliographies of reviewed publications.

Level of Evidence:

Level 4.

Results:

Improvements in hip arthroscopy have allowed FAI to be addressed utilizing the arthroscope. Adequately resecting the underlying osseous abnormalities is essential to improving hip symptomatology and preventing further chondral damage. Additionally, preserving the labrum by repairing the damaged tissue and restoring the suction seal may theoretically help normalize hip mechanics and prevent further arthritic changes. The outcomes of joint-preserving treatment options may be varied in the maturing athlete due to the degree of underlying OA. Irreversible damage to the hip joint may have already occurred in patients with moderate to advanced OA. In the presence of preexisting arthritis, these patients may only experience fair or even poor results after hip arthroscopy, with early conversion to hip replacement. For patients with advanced hip arthritis, total hip arthroplasty remains a treatment option to reliably improve symptoms with good to excellent outcomes and return to low-impact activities.

Conclusion:

Advances in the knowledge base and treatment techniques of intra-articular hip pain have allowed surgeons to address this complex clinical problem with promising outcomes. Traditionally, open surgical dislocations for hip preservation surgery have shown good long-term results. Improvements in hip arthroscopy have led to outcomes equivalent to open surgery while utilizing significantly less invasive techniques. However, outcomes may ultimately depend on the degree of underlying OA. When counseling the mature athlete with hip pain, an understanding of the underlying anatomy, degree of arthritis, and expectations will help guide the treating surgeon in offering appropriate treatment options.

Two or more impingement and/or instability deformities are often present in patients with hip pain

BACKGROUND

Damage to the hip can occur due to impingement or instability caused by anatomic factors such as femoral and acetabular version, neck-shaft angle, alpha angle, and lateral center-edge angle (CEA). The associations between these anatomic factors and how often they occur in a painful hip are unclear but if unaddressed might explain failed hip preservation surgery.

QUESTIONS/PURPOSES

We determined (1) the influence of sex on the expression of impingement-related or instability-related factors, (2) the associations among these factors, and (3) how often both impingement and/or instability factors occur in the same hip.

METHODS

We retrospectively reviewed a cohort of 170 hips (145 patients) undergoing MR arthrography of the hip for any reason. We excluded 58 hips with high-grade dysplasia, Perthes' sequelae, previous surgery, or incomplete radiographic information, leaving 112 hips (96 patients). We measured femoral version and alpha angles on MR arthrograms. Acetabular anteversion, lateral CEA, and neck-shaft angle were measured on pelvic radiographs.

RESULTS

We observed a correlation between sex and alpha angle. Weak or no correlations were observed between the other five parameters. In 66% of hips, two or more (of five) impingement parameters, and in 51% of hips, two or more (of five) instability parameters were found.

CONCLUSIONS

Patients with hip pain frequently have several anatomic factors potentially contributing to chondrolabral damage. To address pathologic hip loading due to impingement and/or instability, all of the anatomic influences should be known. As we found no associations between anatomic factors, we recommend an individualized assessment of each painful hip.

Elevation in circulating biomarkers of cartilage damage and inflammation in athletes with femoroacetabular impingement

BACKGROUND

Femoroacetabular impingement (FAI) is one of the most common causes of early cartilage and labral damage in the nondysplastic hip. Biomarkers of cartilage degradation and inflammation are associated with osteoarthritis. It was not known whether patients with FAI have elevated levels of biomarkers of cartilage degradation and inflammation.

HYPOTHESIS

Compared with athletes without FAI, athletes with FAI would have elevated levels of the inflammatory C-reactive protein (CRP) and cartilage oligomeric matrix protein (COMP), a cartilage degradation marker.

STUDY DESIGN

Controlled laboratory study.

METHODS

Male athletes with radiographically confirmed FAI (n = 10) were compared with male athletes with radiographically normal hips with no evidence of FAI or hip dysplasia (n = 19). Plasma levels of COMP and CRP were measured, and subjects also completed the Short Form-12 (SF-12) and Hip Disability and Osteoarthritis Outcome Score (HOOS) surveys.

RESULTS

Compared with controls, athletes with FAI had a 24% increase in COMP levels and a 276% increase in CRP levels as well as a 22% decrease in SF-12 physical component scores and decreases in all of the HOOS subscale scores.

CONCLUSION

Athletes with FAI demonstrate early biochemical signs of increased cartilage turnover and systemic inflammation.

CLINICAL RELEVANCE

Chondral injury secondary to the repetitive microtrauma of FAI might be reliably detected with biomarkers. In the future, these biomarkers might be used as screening tools to identify at-risk patients and assess the efficacy of therapeutic interventions such as hip preservation surgery in altering the natural history and progression to osteoarthritis.

Management of labral tears of the hip in young patients

Our understanding of labral tears in young patients has evolved significantly in recent years. Successful outcome depends on addressing all bony impingement to improve the intra-articular environment, and prevent further damage to the labrum and articular cartilage. Improved clinical outcomes are associated with labral repair; in cases of a deficient labrum, arthroscopic reconstruction techniques have been developed, with promising clinical outcomes. This article reviews the anatomy of the acetabular labrum, and discusses the pathogenesis of labral tears as well as various treatment options, including arthroscopic labral repair and reconstruction.

The approach to the evaluation and surgical treatment of mechanical hip pain in the young patient: AAOS exhibit selection

The mechanical causes of hip pain in a young athlete often reflect a complex combination of static and dynamic factors. A comprehensive diagnostic approach is paramount to the development of a rational treatment strategy that will address all underlying pathologic factors. The goals of this paper are to highlight the pertinent biomechanical factors of the hip joint in femoroacetabular impingement and to discuss the clinical history, physical examination, and radiographic findings that are essential to formulating a proper diagnosis and an effective treatment plan. In addition, the current literature and reported outcomes of femoroacetabular impingement surgery in athletic patients are reviewed.

Adductor tenotomy as a treatment for groin pain in professional soccer players

Chronic, exercise-related groin pain is a debilitating condition. Nonoperative treatment has limited efficacy, but surgical intervention on the adductor-abdomino complex may be used to alleviate symptoms and allow return to play (RTP). The purpose of this study was to report the outcome of adductor tenotomy and hernioplasty for professional soccer players with groin pain. Between 2000 and 2006, a total of 155 professional and recreational soccer players with recalcitrant groin pain (with or without lower abdominal pain) and resistance to conservative treatment were included in this retrospective analysis. Ninety-six patients were treated with adductor tenotomy and 59 patients were treated with combined adductor tenotomy and hernioplasty. No difference in pre- or postoperative parameters was detected between groups, apart from abdominal wall muscle defects revealed during ultrasound for patients in the combined group. The RTP time and subjective and objective outcome measures were compared. A combined score was developed to evaluate outcomes that consisted of overall satisfaction (50%), RTP time (15%), and Tegner scores (35%). Mean RTP was 11 weeks (range, 4-36 weeks). Postoperative Tegner score remained 8.2 (same as the preinjury Tegner score). Subjective outcome was rated 4.3 of 5. The combined score indicated 80% of good or excellent results for both groups. Surgical intervention allows RTP at the same level in professional soccer players following failure of nonoperative treatments. Athletes with adductor syndrome and accompanying sportsman's hernia may benefit from adductor tenotomy alone.

Novel CT-based three-dimensional software improves the characterization of cam morphology

BACKGROUND

Incomplete correction of femoral offset and sphericity remains the leading cause for revision surgery for symptomatic femoroacetabular impingement (FAI). Because arthroscopic exploration is technically difficult, a detailed preoperative understanding of morphology is of paramount importance for preoperative decision-making.

QUESTIONS/PURPOSES

The purposes of this study were to (1) characterize the size and location of peak cam deformity with a prototype CT-based software program; (2) compare software alpha angles with those obtained by plain radiograph and CT images; and (3) assess whether differences can be explained by variable measurement locations.

METHODS

We retrospectively reviewed the preoperative plain radiographs and CT scans of 100 symptomatic cam lesions treated by arthroscopy; recorded alpha angle and clockface measurement location with a novel prototype CT-based software program, CT, and Dunn lateral plain radiographs; and used ordinary least squares regressions to assess the relationship between alpha angle and measurement location.

RESULTS

The software determined a mean alpha angle of 70.8° at 1:23 o'clock and identified 60% of maximum alpha angles between 12:45 and 1:45. The CT and plain radiographs underestimated by 5.7° and 8.2°, respectively. The software-based location was anterosuperior to the mean CT and plain radiograph measurement locations by 41 and 97 minutes, respectively. Regression analysis confirmed a correlation between alpha angle differences and variable measurement locations.

CONCLUSIONS

Software-based three-dimensional (3-D) imaging generated alpha angles larger than those found by plain radiograph and CT, and these differences were the result of location of measurement. An automated 3-D assessment that accurately describes the location and topography of FAI may be needed to adequately characterize preoperative deformity.

Anterior inferior iliac spine morphology correlates with hip range of motion: a classification system and dynamic model

BACKGROUND

The anterior inferior iliac spine (AIIS) contributes to hip dysfunction in patients with symptomatic impingement and resection of a prominent AIIS can reportedly improve function. However, the variability of the AIIS morphology and whether that variability correlates with risk of associated symptomatic impingement are unclear.

QUESTIONS/PURPOSES

We characterized AIIS morphology in patients with hip impingement and tested the association between specific AIIS variants and hip range of motion.

METHODS

We evaluated three-dimensional CT reconstructions of 53 hips (53 patients) with impingement and defined three morphological AIIS variants: Type I when there was a smooth ilium wall between the AIIS and the acetabular rim, Type II when the AIIS extended to the level of the rim, and Type III when the AIIS extended distally to the acetabular rim. A separate cohort of 78 hips (78 patients) with impingement was used to compare hip range of motion among the three AIIS types.

RESULTS

Mean hip flexion was limited to 120°, 107°, and 93° in hips with Type I, Type II, and Type III AIIS, respectively. Mean internal rotation was limited to 21°, 11°, and 8° in hips with Type I, Type II, and Type III AIIS, respectively.

CONCLUSIONS

When the AIIS is classified into three variants based on the relationship between the AIIS and the acetabular rim in patients with impingement, Type II and III variants are associated with a decrease in hip flexion and internal rotation, supporting the rationale for considering AIIS decompression for variants that extend to and below the rim.

Return to sport in Australian football league footballers after hip arthroscopy and midterm outcome

PURPOSE

To study the return to sport in a series of professional athletes in a single sport (Australian Rules Football), operated on arthroscopically for hip joint pathology.

METHODS

We performed a retrospective review of the senior author's surgical database starting in 2003. All of the patients who were Australian Football League (AFL) professional players with a minimum of 2 years' follow-up were included. Intra-articular pathologies were identified and treated. All patients were prospectively assessed with the modified Harris Hip Score (MHHS) and the Non-Arthritic Hip Score (NAHS). In addition, information about the active participation of the patients in their teams and return to professional sport was obtained from AFL registers and team physicians.

RESULTS

Since 2003, the senior author has operated on 36 male professional AFL players; 26 of 27 with at least 2 years' follow-up were available for review. The mean age at the time of surgery was 22.1 years (range, 16 to 30 years), and 8 patients had bilateral pathology; therefore 34 hips were operated on. This report refers to those 26 players and 34 hips. All but 1 of the patients returned to play professionally. By the last survey (October 2011), 16 patients (62%) were still playing professional AFL football, and they have been playing for a mean of 52.5 months after surgery. Ten patients had retired from professional football, but they had all returned to play professionally after surgery. Only one of them retired for causes related to hip disability. There was a significant improvement in preoperative outcome scores. The MHHS and NAHS improved from 83.6 to 98 and from 85.3 to 97.1, respectively, in the players who were still playing (P < .05). Rim lesions were present in 33 hips (97%). Femoral osteochondroplasty was performed in 26 hips (76%).

CONCLUSIONS

Arthroscopic treatment of intra-articular pathologies in professional athletes resulted in a 96% rate of return to elite-level sport and a durable increase in the MHHS and NAHS.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Correlation of clinical and magnetic resonance imaging findings in hips of elite female ballet dancers

PURPOSE

To understand why professional female ballet dancers often complain of inguinal pain and experience early hip osteoarthritis (OA). Goals were to examine clinical and advanced imaging findings in the hips of dancers compared with those in a matched cohort of nondancers and to assess the femoral head translation in the forward split position using magnetic resonance imaging (MRI).

METHODS

Twenty professional female ballet dancers and 14 active healthy female individuals matched for age (control group) completed a questionnaire on hip pain and underwent hip examination with impingement tests and measurement of passive hip range of motion (ROM). All had a pelvic 1.5 T MRI in the back-lying position to assess femoroacetabular morphologic features and lesions. For the dancers, additional MR images were acquired in the split position to evaluate femoroacetabular congruency.

RESULTS

Twelve of 20 dancers complained of groin pain only while dancing; controls were asymptomatic. Dancers' passive hip ROM was normal. No differences in α neck angle, acetabular depth, acetabular version, and femoral neck anteversion were found between dancers and controls. MRI of dancers while performing splits showed a mean femoral head subluxation of 2.05 mm. MRI of dancers' hips showed labral tears, cartilage thinning, and herniation pits, located in superior and posterosuperior positions. Lesions were the same for symptomatic and asymptomatic dancers. Controls had proportionally the same number of labral lesions but in an anterosuperior position. They also had 2 to 3 times fewer cartilage lesions and pits than did dancers.

CONCLUSIONS

The results of our study are consistent with our hypothesis that repetitive extreme movements can cause femoral head subluxations and femoroacetabular abutments in female ballet dancers with normal hip morphologic features, which could result in early OA. Pathologic changes seen on MRI were symptomatic in less than two thirds of the dancers.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Femoroacetabular impingement

Both arthroscopic and open operative treatment of femoroacetabular impingement (FAI) can reproducibly relieve hip pain with correction of the underlying osseous deformity and treatment of the associated labral pathology, particularly in patients without substantial articular cartilage injury at the time of surgery. Between 75% and 90% of athletes undergoing FAI surgery return to sports at their pre-injury level of function. There is no peer-reviewed evidence to date reporting on the efficacy of nonoperative treatment and return to play with FAI. Successful operative treatment of impingement requires appropriate and complete correction of the mechanical injury that led to the symptomatic labral pathology. Early intervention prior to the onset of irreversible chondral damage is critical to the long-term success of FAI surgery. Complex deformities involving combinations of static and dynamic mechanical factors often coexist, so careful preoperative evaluation of the underlying structural anatomy is critical to successful treatment planning.

Arthroscopic hip preservation surgery

The technical advances in arthroscopic surgery of the hip, including the improved ability to manage the capsule and gain extensile exposure, have been paralleled by a growth in the number of conditions that can be addressed. This expanding list includes symptomatic labral tears, chondral lesions, injuries of the ligamentum teres, femoroacetabular impingement (FAI), capsular laxity and instability, and various extra-articular disorders, including snapping hip syndromes. With a careful diagnostic evaluation and technical execution of well-indicated procedures, arthroscopic surgery of the hip can achieve successful clinical outcomes, with predictable improvements in function and pre-injury levels of physical activity for many patients.

This paper reviews the current position in relation to the use of arthroscopy in the treatment of disorders of the hip.

Cite this article: Bone Joint J 2013;95-B:10–19.