Lesions of the acetabular labrum: accuracy of MR imaging and MR arthrography in detection and staging

High prevalence of pelvic and hip magnetic resonance imaging findings in asymptomatic collegiate and professional hockey players

BACKGROUND

Prior retrospective studies have reported magnetic resonance imaging (MRI) findings of common adductor-abdominal rectus enthesopathy and acetabular labral tear in athletes treated for athletic pubalgia and hip pain. The true prevalence of these findings and association with symptoms in this population is unknown.

PURPOSE

This study was undertaken to determine the prevalence of pelvic and hip MRI findings and association with clinical symptoms in professional and collegiate hockey players.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

The study included 21 professional and 18 collegiate hockey players. Self-reported symptoms were measured using a modified Oswestry Disability Questionnaire. Participants underwent 3-T MRI evaluation of the pelvis and hips. The MRI scans were interpreted independently by 3 musculoskeletal radiologists in 2 sessions separated by 3 months using a 5-point Likert scale to assess for features associated with common adductor-abdominal rectus dysfunction and hip pathology. To estimate prevalence, MRI findings rated 4 or higher on 4 of the 6 interpretations were considered positive. A variance component analysis was applied to determine intrareader and interreader reliability and the lower 95% confidence limits (CLs).

RESULTS

No participants reported symptoms related to pelvic or hip disorders. The MRI findings of common adductor-abdominal rectus dysfunction were observed in 14 of 39 participants (36%) and hip pathologic changes in 25 of 39 (64%). There was moderate agreement between readings, with intrareader and interreader reliabilities ranging from 0.37 to 1.00. The interreader reliability was less for evaluation of hip pathologic abnormalities than for groin pathologic abnormalities, with the lowest reliability observed in reporting of hip osteochondral lesions (0.37 with lower 95% CL of 0.22) and fluid in the primary cleft (0.45 with lower 95% CL of 0.29) and perfect reliability in the absence of effusion and abdominal rectus tendon tears. Overall, 30 of 39 (77%) asymptomatic hockey players demonstrated MRI findings of hip or groin pathologic abnormalities.

CONCLUSION

Given the high prevalence of MRI findings in asymptomatic hockey players, it is necessary to cautiously interpret the significance of these findings in association with clinical presentation. Future investigations will determine whether these asymptomatic findings predict future disabilities.

Hip pain referral patterns in patients with labral tears: analysis based on intra-articular anesthetic injections, hip arthroscopy, and a new pain "circle" diagram

BACKGROUND

Fluoroscopically guided intra-articular (FGIA) anesthetic hip joint injections have been used to determine whether the hip joint is the source of a patient's hip pain. However, there have been no reports documenting the efficacy of their use for defining the pain referral patterns (PRPs) of patients with labral tears. The aim of this study was to determine the PRPs of patients with labral tears and evaluate a new pain "circle" diagram (PCD) developed for this analysis.

METHODS

Fifty-two patients were evaluated at our institution who had: 1) a preoperative FGIA anesthetic hip joint injection; 2) completed our PCD and a visual analog pain scale pre- and postinjection; 3) significant (≥ 80%) pain reduction after their FGIA injection; and 4) a labral tear and minimal (≤ grade II) degenerative joint disease, as documented by hip arthroscopy. The PCD had circles in which patients put an "X" in to indicate pain in the following locations: anterior superior spine, lateral peritrochanteric area, central groin, symphysis pubis, proximal inner thigh, anterior thigh, posterior iliac crest, sacroiliac joint, sciatic notch, and ischial tuberosity.

RESULTS

Based on the percentage of patients with significant (≥ 80%) pain reduction after administration of FGIA, 2 areas demonstrated substantially more and consistent presence of pain, which improved after injection. These were the central groin (P < 0.001) and the lateral peritrochanteric area (P = 0.02).

CONCLUSION

The most common locations of pain were the central groin and the lateral peritrochanteric area. The least common were the ischial tuberosity and the anterior thigh, which are 2 areas often associated with osteoarthritis of the hip. The use of the PCD combined with an FGIA anesthetic injection may help physicians reconcile the expectations of those patients with labral tears who believe that hip arthroscopy will treat their multiple areas of "hip" pain.

Achados em ressonância magnética artrográfica de indivíduos com lesão do labrum acetabular

OBJETIVO: Descrever os achados em artro RM de sujeitos com suspeita de lesão do labrum acetabular. MÉTODO: Foram analisadas 108 artro RM de quadris em 2007/2008. Dois radiologistas independentemente analisaram as imagens e foi considerada a resposta comum entre eles. Com base em seus pareceres observou-se o local e estadiamento das lesões labrais e condrais, as alterações anatômicas, e a presença de tendinite e bursite trocantérica. RESULTADO: As lesões labrais grau I ocorreram em 41% dos casos, grau II em 31%, e grau III em 29%. O IFA tipo cam foi frequente em 36% dos casos, tipo pincer em 11%, e IFA misto em 13%, nestes casos 57% apresentaram lesão labral grau III, A lesão condral grau I foi observada em 51% acetábulos, as de grau II em 13%, e grau III em 18%. CONCLUSÃO: As alterações morfológicas que provocam IFA do tipo cam foram as mais prevalentes. Em relação ao grau de lesão labral e condral foram predominantes as lesões grau I independente da presença ou do tipo de IFA, exceto em IFAs mistos onde houve predomínio de lesão labral grau III. Não foi observada uma relação entre o grau de lesão labral e condral.

Three-dimensional magnetic resonance imaging of joints

Magnetic resonance (MR) imaging is one of the most commonly used imaging modality for evaluating patients with joint pain. Musculoskeletal MR protocols at most institutions consist of 2-dimensional fast spin echo (FSE) sequences repeated in multiple planes. Three-dimensional sequences have also been used to evaluate the musculoskeletal system and have many potential advantages over 2-dimensional FSE sequences. Three-dimensional sequences acquire thin continuous slices through joints with high in-plane spatial resolution, which minimize the effects of partial volume averaging. Newly developed 3-dimensional isotropic resolution sequences can also be used to create high-quality multiplanar reformat images that allow joints to be evaluated in any orientation after a single acquisition. Preliminary results on the use of 3-dimensional isotropic resolution sequences for evaluating the musculoskeletal system are encouraging. However, additional studies are needed to document the advantages of 3-dimensional sequences before they can replace currently used 2-dimensional FSE sequences for evaluating the musculoskeletal system in clinical practice.

Clinical cartilage imaging of the knee and hip joints

OBJECTIVE

MRI is commonly used to evaluate the articular cartilage of the knee and hip joints in clinical practice. This article will discuss the advantages and limitations of currently available MRI techniques for evaluating articular cartilage.

CONCLUSION

Because of its high spatial resolution, multiplanar capability, and excellent tissue contrast, MRI is the imaging technique of choice for evaluating the articular cartilage of the knee and hip joints.

Arthroscopic treatment of labral tears after a previous pemberton osteotomy

We present 3 patients followed at our institution for developmental hip dysplasia for an average of 20 years. Each patient underwent a Pemberton pelvic osteotomy for developmental hip dysplasia and remained symptom-free during childhood. All 3, however, returned as young adults at an average 12 years from surgery with delayed onset of ipsilateral hip pain associated with a damaged labrum. The purpose of this report is to describe the late presentation of 3 symptomatic young adults with a history of childhood pelvic osteotomy. All the 3 patients were subsequently diagnosed with and successfully treated for symptomatic acetabular labral damage. All patients were informed that data concerning their case would be submitted for publication.

Arthroscopic management of pincer-type impingement

Femoroacetabular impingement is a disorder associated with labrochondral injury and the development of osteoarthritis. Although femoroacetabular impingement is a 3-dimensional disorder with variable size and extent of impingement between individuals, there are 2 primary types of hip impingement: Cam-type and Pincer-type. Cam-type impingement is the result of asphericity of the femoral head-neck junction whereas Pincer-type impingement results from acetabular overcoverage. This paper will focus on Pincer-type pathology. The pathomechanics and most common subtypes of pincer impingement, typical patient presentation, radiographic and imaging findings, surgical indications, intraoperative findings, and specific arthroscopic surgical techniques will be described.

Chondral lesions of the hip: microfracture and chondroplasty

Hip arthroscopy has become increasingly popular over the past several years as the techniques have evolved to be able to address both the peripheral and central compartments of the hip. The main indications for hip arthroscopy 10 years ago were diagnostic and debridement procedures such as removal of loose bodies, labral resection, synovectomy, and cartilage debridement. Advances in this field have now expanded to include reconstruction and repair of the labrum, recontouring of the acetabulum and head-neck junction, cartilage salvage, and repair and releases of the tendons around the hip joint. We detail in this article chondral injuries that occur in the hip joint and arthroscopic procedures to address these issues. We routinely perform chondroplasty in cases where there is a partial thickness tear of articular cartilage. Full thickness defects are addressed with microfracture which follows closely the guidelines established for the knee. As our understanding of chondral injuries and their causes grows, future efforts will focus on prevention.

The role of multidetector CT arthrography in the investigation of suspected intra-articular hip pathology

The aim of this study was to evaluate the role of multidetector CT (MDCT) arthrography in the diagnosis of intra-articular hip pathology. A retrospective review of 96 patients who had undergone CT hip arthrography was performed. Data regarding the presence of a labral tear, paralabral cyst, chondral loss, acetabular version, femoral morphology and fibrocystic change were collected. We detected 28 labral tears (24 anterior, 2 anterolateral, 1 lateral and 1 posterolateral). An abnormal labral-chondral transitional zone was seen in 9 patients and 4 patients had surface labral fraying. We identified three paralabral cysts. Acetabular cartilage loss was detected in 45 and femoral cartilage loss in 9 patients. An abnormal anterior femoral head and neck junction was present in 18 hips and fibrocystic change in 8. Acetabular retroversion was present in 11 hips. 63 sets of patient notes were reviewed, of which 49 were in-patients with abnormal MDCT arthrogram findings. Surgical correlation was available in 27 patients. There was a discrepancy between the findings of a labral tear in one patient (false negative, 90% sensitivity and 100% specificity) and the presence of acetabular cartilage loss (88% sensitivity and 100% specificity) and femoral cartilage loss (94% sensitivity and 100% specificity) in three patients. MDCT arthrography affords accurate detection of intra-articular hip pathology.

Magnetic resonance arthrography of the hip: technique and spectrum of findings in younger patients

Magnetic resonance(MR) imaging is the reference imaging technique in the evaluation of hip abnormalities. However, in some pathological conditions-such as lesions of the labrum, cartilaginous lesions, femoroacetabular impingement, intra-articular foreign bodies, or in the pre-operative work-up of developmental dysplasia of the hip-intra-articular injection of a contrast medium is required to obtain a precise diagnosis. This article reviews the technical aspects, contraindications, normal appearance and potential pitfalls of MR arthrography, and illustrates the radiological appearance of commonly encountered conditions.

Femoro-acetabular impingement: can indirect MR arthrography be considered a valid method to detect endoarticular damage? A preliminary study

To assess the effectiveness of indirect Magnetic Resonance arthrography (i-MRa) in the detection of chondral and labral lesions related to femoro-acetabular impingement (FAI) a series of 21 hip joints in 17 patients with a clinical diagnosis of FAI were examined either with standard MR imaging, i-MRa and direct-MR arthrography (d-MRa). Sensitivity and accuracy of i-MRa in detecting chondral, labral and tardive lesions were calculated and compared with standard MR. The agreement in detecting endoarticular damage between i-MRa and d-MRa and the interobserver agreement was assessed by K statistic (p<0.05). Finally the presence of trocanteric bursitis was evaluated. I-MRa showed higher values of both sensivity and accuracy than standard MR in detecting chondral damage, with an increase to 92% for the first item and 95% for the second. The same was noticed in labrum evaluation with an increase to 88% and 90% respectively. The level of agreement between i-MRa and d-MRa in detection of chondral lesions was excellent, substantial for the labral damage and absolute for early osteoarthritic changes. An excellent interobserver agreement resulted in detection of both chondral and labral damages with i-MRa. In 6 hips (28,5%) we also found the presence of peri-trochanteric soft tissue inflammation that indicated the possibility of extrarticular involvement in FAI. Indirect-MRa can be considered a valid method of assessing endoarticular damage related to FAI, in comparison to d-MRa. It should be performed instead of standard MR if d-MRa is not available.

MRI of hip osteoarthritis and implications for surgery

Osteoarthritis of the hip joint is caused by a combination of intrinsic factors and extrinsic factors. Different surgical techniques are being performed to delay or halt osteoarthritis. Success of salvage procedures of the hip depends on the existing cartilage and joint damage before surgery; the likelihood of therapy failure rises with advanced osteoarthritis. For imaging of intra-articular hip pathology, MR imaging represents the best technique because of its ability to directly visualize cartilage, superior soft tissue contrast, and the prospect of multidimensional imaging. This article gives an overview on the standard MR imaging techniques used for diagnosis of hip osteoarthritis and their implications for surgery.

MR imaging of overuse injuries of the hip

The aim of this article is to emphasize the importance of MR imaging in the evaluation of chronic hip pain and overuse injuries. Image interpretation of the hip can be difficult because of the complex anatomy and the varied pathology that athletes can present with, such as labral and cartilaginous injuries, surrounding soft tissue derangement involving muscles or tendons, and osseous abnormalities. The differential diagnosis in adults is diverse and includes such common entities as stress fracture, avulsive injuries, snapping-hip syndrome, iliopsoas bursitis, femoroacetabular impingement syndrome, tendinosis, and tears of the gluteal musculature.

Acetabular labral tears in patients with sports injury

Background

We wanted to investigate acetabular labral tears and their correlation with femoroacetabular impingement in patients with sports injury.

Methods

Among 111 patients who were diagnosed with the acetabular labral tears after arthroscopic treatment from January 2004 to December 2007, we selected 41 patients with sports injury. There were 12 cases of Taekwondo injury, 5 of golf injury, 4 of soccer injury, 3 of gymnastics injury, 2 of Hapkido injury, 2 of aerobics injury, 2 of rock-climbing injury, 2 of fitness training injury and 9 of other sports injuries. We checked the subtypes of acetabular labral tears and the accompanying femoroacetabular impingement. For the cases with accompanying femoroacetabular impingement, we investigated the subtypes according to the types of sports, gender and age. At last follow-up, we checked the Harris Hip Score (HHS), the Hip Outcome Score (HOS) sports scale and the percentage of patients who returned to their sports activity.

Results

The average age of symptomatic onset was 26 years (range, 12 to 65 years). The ratio of males to females was 29 : 12. An average duration of the hip pain was 17 months (range, 1 to 60 months). The degenerative type of acetabular labral tears was the most prevalent with 32 cases (78%), and there were 9 cases (22%) of the partial tear type. Thirty cases (73%) were accompanied by femoroacetabular impingement. The average age of the 23 cases (56%) of the cam-type was 23 years (range, 12 to 48 years), and it was more likely to occur in men (87%) and for people practicing martial arts such as Taekwondo or Hapkido. An average age of the 5 cases (12%) of the pincer-type was 26 (range, 16 to 43 years), it usually occurred in women (60%) and for non-martial arts such as golf and gymnastics. There were 2 cases of the mixed type (cam + pincer-type). At 27 months follow-up, the HHS was 61 to 92 points, the HOS sports scale increased 43 to 75%, and the rate of returning to sports was 71%.

Conclusions

In spite of the early expression of symptoms and the short duration of the acetabular labral tears, the high rate of degenerative acetabular labral tears in sports patients is likely associated with repetitive injury after the expression of symptoms. Femoroacetabular impingement in sports patients is seemed to be a cause of the early occurrence of acetabular labral tears. Because the possibility of acetabular labral tears is high in femoroacetabular impingement, sports patients may need to undergo early screening for the diagnosis and care of femoroacetabular impingement.

Cartilage damage in femoroacetabular impingement (FAI): preliminary results on comparison of standard diagnostic vs delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC)

OBJECTIVES

To study the three-dimensional (3D) T1 patterns in different types of femoroacetabular impingement (FAI) by utilizing delayed gadolinium-enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC) and subsequent 3D T1 mapping. We used standard grading of OA by Tonnis grade on standard radiographs and morphological grading of cartilage in MRI for comparative analysis.

METHODS

dGEMRIC was obtained from ten asymptomatic young-adult volunteers and 26 symptomatic FAI patients. MRI included the routine hip protocol and a dual-flip angle (FA) 3D gradient echo (GRE) sequence utilizing inline T1 measurement. Cartilage was morphologically classified from the radial images based on the extent of degeneration as: no degeneration, degeneration zone measuring <0.75 cm from the rim, >0.75 cm, or total loss. T1 findings were evaluated and correlated.

RESULTS

All FAI types revealed remarkably lower T1 mean values in comparison to asymptomatic volunteers in all regions of interest. Distribution of the T1 dGEMRIC values was in accordance with the specific FAI damage pattern. In cam-types (n=6) there was a significant drop (P<0.05) of T1 in the anterior to superior location. In pincer-types (n=7), there was a generalized circumferential decrease noted. High inter-observer (intra-observer) reliability was noted for T1 assessment using intra-class correlation (ICC):intra-class coefficient=0.89 (0.95).

CONCLUSIONS

We conclude that a pattern of zonal T1 variation does seem to exist that is unique for different sub-groups of FAI. The FA GRE approach to perform 3D T1 mapping has a promising role for further studies of standard MRI and dGEMRIC in the hip joint.

Arthroscopic repair of delaminated acetabular articular cartilage in femoroacetabular impingement

Lesions to articular cartilage can be difficult to treat and directly impact surgical outcome in hip arthroscopy. This article describes a direct cartilage suture repair technique for a young, active individual with full-thickness acetabular cartilage delamination. Lesions of this type are commonly seen with femoroacetabular impingement. A 17-year-old boy presented with bilateral hip pain greater in the right than left. Arthroscopic intervention for the right hip included direct cartilage repair for the cartilage lesion, osteoplasty for femoroacetabular impingement, repair for an anterior labral tear, capsular plication for iliofemoral ligament laxity, and psoas lengthening. Twelve weeks postoperatively, a standard capsular plication, osteoplasty, and chondroplasty were performed on the left hip. At follow-up, the patient reported feeling 95% normal. He noted that the right and left hips were essentially the same. Symptoms consisted of stiffness after prolonged sitting and mild pain following sports. The patient reported being pain free 90% of the time, with pain 2/10 at worst. He scored a 96 on the modified Harris Hip Score, 93 on the Hip Outcome Score Activities of Daily Living subscale, and 81 on the Hip Outcome Score Sports subscale. Overall, the patient was satisfied with the outcome. The direct cartilage repair, in addition to osteoplasty, anterior superior labral repair, iliofemoral capsular plication, and psoas lengthening, produced an excellent outcome in this young, active patient.

[Radiological diagnosis of femoroacetabular impingement]

Femoroacetabular impingements (FAI) are due to an anatomical disproportion between the proximal femur and the acetabulum which causes premature wear of the joint surfaces. An operation is often necessary in order to relieve symptoms such as limited movement and pain as well as to prevent or slow down the degenerative process. The result is dependent on the preoperative status of the joint with poor results for advanced arthritis of the hip joint. This explains the necessity for an accurate diagnosis in order to recognize early stages of damage to the joint. The diagnosis of FAI includes clinical examination, X-ray examination and magnetic resonance imaging (MRI). The standard X-radiological examination for FAI is carried out using two X-ray images, an anterior-posterior view of the pelvis and a lateral view of the proximal femur, such as the cross-table lateral or Lauenstein projections. It is necessary that positioning criteria are adhered to in order to avoid distortion artifacts. MRI permits an examination of the pelvis on three levels and should also include radial planned sequences for improved representation of peripheral structures, such as the labrum and peripheral cartilage. The use of contrast medium for a direct MR arthrogram has proved to be advantageous particularly for representation of labrum damage. The data with respect to cartilage imaging are still unclear. Further developments in technology, such as biochemical-sensitive MRI applications, will be able to improve the diagnosis of the pelvis in the near future.

Magnetic resonance arthrography

Magnetic resonance arthrography is widely used throughout the world for joint imaging. It extends the capabilities of conventional MR imaging because contrast solution distends the joint capsule, outlines intraarticular structures, and extends into soft tissue tears and defects. MR arthrography exploits the natural advantages gained from a joint effusion and can be performed on any joint.

Optimization of the contrast mixture ratio for simultaneous direct MR and CT arthrography: an in vitro study

Objective

This study was designed to determine the optimal mixture ratio of gadolinium and iodinated contrast agent for simultaneous direct MR arthrography and CT arthrography.

Materials and Methods

An in vitro study was performed utilizing mixtures of gadolinium at six different concentrations (0.625, 1.25, 2.5, 5.0, 10 and 20 mmol/L) and iodinated contrast agent at seven different concentrations (0, 12.5, 25, 37.5, 50, 75 and 92-99.9%). These mixtures were placed in tissue culture plates, and were then imaged with CT and MR (with T1-weighted sequences, proton-density sequences and T2-weighted sequences). CT numbers and signal intensities were measured. Pearson's correlation coefficients were used to assess the correlations between the gadolinium/iodinated contrast agent mixtures and the CT numbers/MR signal intensities. Scatter diagrams were plotted for all gadolinium/iodinated contrast agent combinations and two radiologists in consensus identified the mixtures that yielded the optimal CT numbers and MR signal intensities.

Results

The CT numbers showed significant correlation with iodinated contrast concentrations (r = 0.976, p < 0.001), whereas the signal intensities as measured on MR images showed a significant correlation with both gadolinium and iodinated contrast agent concentrations (r = -484 to -0.719, p < 0.001). A review of the CT and MR images, graphs, and scatter diagram of 42 combinations of the contrast agent showed that a concentration of 1.25 mmol/L gadolinium and 25% iodinated contrast agent was the best combination for simultaneous CT and MR imaging.

Conclusion

A mixture of 1.25 mmol/L gadolinium and 25% iodinated contrast agent was found to be optimal for simultaneous direct MR arthrography and CT arthrography.

A comprehensive review of hip labral tears

The hip labrum has many functions, including shock absorption, joint lubrication, pressure distribution, and aiding in stability, with damage to the labrum associated with osteoarthritis. The etiology of labral tears includes trauma, femoroacetabular impingement (FAI), capsular laxity/hip hypermobility, dysplasia, and degeneration. Labral tears present with anterior hip or groin pain, and less commonly buttock pain. Frequently, there are also mechanical symptoms including clicking, locking, and giving way. The most consistent physical examination finding is a positive anterior hip impingement test. Because of the vast differential diagnosis and the need for specialized diagnostic tools, labral tears frequently go undiagnosed during an extended period of time. Evaluation usually begins with plain radiographs to assess for dysplasia, degeneration, and other causes of pain. While magnetic resonance imaging (MRI) and computed tomography scans are unreliable for diagnosis, magnetic resonance arthrography (MRA) is the diagnostic test of choice, with arthroscopy being the gold standard. Typically, treatment begins conservatively with relative rest and non-steroid anti-inflammatory agents, with physical therapy (PT) being controversial. Often, surgical treatment is necessary, which entails, arthroscopic debridement of labral tears and surgical repair of associated structural problems.

Arthroscopy of the hip in children and adolescents

Intra-articular abnormalities of the hip, such as labral tears, loose bodies, chondral lesions, ligamentum teres tears and femoral acetabular impingement are increasingly being recognized in the pediatric age group. Evaluation for these abnormalities starts with a good history and physical exam. Radiographic imaging with plain films and magnetic resonance imaging help confirm the clinical impression. Arthroscopy of the hip can be utilized to diagnose and treat these abnormalities. Arthroscopy of the hip is a challenging procedure with a learning curve that requires a thorough knowledge of the anatomy of the hip. The hip is a deeply recessed joint that has a large muscular envelope, thick joint capsule and convex and concave surfaces of the femoral head and acetabulum, respectively. The normal anatomy may be distorted due to childhood developmental disorders such as hip dysplasia, Legg-Calve-Perthes Disease and Slipped Capital Femoral Epiphysis that adds additional challenges to the arthroscopist. Isolated intra-articular abnormalities occur rarely and an underlying morphologic abnormality should be identified which also requires management. Complications can be minimized with attention to detail.

Delamination cysts: a predictor of acetabular cartilage delamination in hips with a labral tear

The treatment and prognosis of labral tears of the hip depend primarily on whether there is concomitant injury of the adjacent acetabular articular cartilage. We asked whether a delamination cyst on the preoperative plain radiographs correlated with delamination of the acetabular articular cartilage at the time of hip arthroscopy. We reviewed the preoperative radiographs of 125 consecutive hips that had a labral tear at hip arthroscopy for the presence of a delamination cyst. A delamination cyst was defined as an acetabular subchondral cyst either directly adjacent to a lateral acetabular cyst or in relation to a subchondral crack in the anterosuperior portion of the acetabulum. All patients with acetabular cartilage delamination at arthroscopy were identified. There were 16 patients with delamination cysts on radiographs and 15 patients with cartilage delamination at arthroscopy. A delamination cyst on the preoperative anteroposterior and/or frog lateral radiographs of the hip accurately predicted acetabular cartilage delamination, especially in hips with labral tears not caused by a major trauma. A delamination cyst is a previously unrecognized and novel radiographic sign that can preoperatively identify acetabular cartilage delamination in patients with labral tears, thereby facilitating the selection of the appropriate surgery and determining prognosis.

LEVEL OF EVIDENCE

Level II, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Acetabular labral tears

Acetabular labral tears rarely occur in the absence of a structural osseous abnormality. Labral tears are frequently associated with lesions of acetabular cartilage such as delamination. Hip arthroscopy is the preferred operative approach in the treatment of labral injuries in the absence of substantial structural osseous abnormalities.

[Imaging in developmental dysplasia of the hip]

Modern imaging techniques are an invaluable tool for assessing pathomorphological changes of the hip. Thorough diagnostic analysis and therapeutic decision making mainly rely on correct interpretation of conventional radiographic projections as well as more modern techniques, including magnetic resonance arthrography. This article gives an overview of the imaging techniques that are routinely used for assessing pathological conditions of the hip, with a special focus on diagnostic findings in developmental dysplasia of the hip as well as in femoroacetabular impingement.

Athletic pubalgia and "sports hernia": optimal MR imaging technique and findings

Groin injuries are common in athletes who participate in sports that require twisting at the waist, sudden and sharp changes in direction, and side-to-side ambulation. Such injuries frequently lead to debilitating pain and lost playing time, and they may be difficult to diagnose. Diagnostic confusion often arises from the complex anatomy and biomechanics of the pubic symphysis region, the large number of potential sources of groin pain, and the similarity of symptoms in athletes with different types or sites of injury. Many athletes with a diagnosis of "sports hernia" or "athletic pubalgia" have a spectrum of related pathologic conditions resulting from musculotendinous injuries and subsequent instability of the pubic symphysis without any finding of inguinal hernia at physical examination. The actual causal mechanisms of athletic pubalgia are poorly understood, and imaging studies have been deemed inadequate or unhelpful for clarification. However, a large-field-of-view magnetic resonance (MR) imaging survey of the pelvis, combined with high-resolution MR imaging of the pubic symphysis, is an excellent means of assessing various causes of athletic pubalgia, providing information about the location of injury, and delineating the severity of disease. Familiarity with the pubic anatomy and with MR imaging findings in athletic pubalgia and in other confounding causes of groin pain allows accurate imaging-based diagnoses and helps in planning treatment that targets specific pathologic conditions.

Results of arthroscopic iliopsoas tendon release in competitive and recreational athletes

BACKGROUND

An arthroscopic iliopsoas tendon release will alleviate painful snapping of the tendon. One question that remains is whether athletes can return to sports after this procedure. This study presents the results of 5 competitive and 10 recreational athletes who had an arthroscopic release of their iliopsoas tendon.

HYPOTHESIS

Athletes can return to full participation in their sport after an arthroscopic iliopsoas tendon release.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Fifteen athletes (2 college, 3 high school, 10 recreational) with painful snapping hips and no pain relief after anesthetic magnetic resonance arthrography had an ultrasound evaluation of their iliopsoas tendon and an anesthetic injection into the psoas bursa. In all 15 patients, the injection relieved their hip pain, and in 10 patients, real-time imaging demonstrated snapping of the tendon. All hips were assessed with Byrd's 100-point hip scoring system before the release and at 1.5, 3, 6, and 12 months after surgery.

RESULTS

Preoperative hip scores averaged 41 and 44 points for the competitive and recreational athletes, respectively. After surgery, the 2 groups used crutches for 4 weeks, and had 6-week scores that averaged 87 and 63 points. At 6 months, their scores averaged 94 and 98 points, and at 12 months, 96 and 97 points, and none had recurrence of their snapping or pain. All 15 athletes returned to full participation in their sport at an average of 9 months after surgery.

CONCLUSION

A return to college, high school, and recreational sports can be expected after an arthroscopic release of the iliopsoas tendon.

Clinical presentation of femoroacetabular impingement in adolescents

Femoroacetabular impingement (FAI) is a recently recognized hip disorder resulting from an abnormal morphology of the proximal femur and acetabulum. This morphology results in increased hip contact forces with hip motion, specifically flexion. This may lead to labral-cartilage injury and pain. The purpose of this study is to describe the clinical presentation and diagnosis of FAI as a cause of hip pain in adolescents.Thirty-five patients with FAI as the etiology of chronic hip pain from one institution were reviewed. The common symptoms, physical examination, and radiographic findings were analyzed.The age range was 13 to 18 years. There were 30 girls and 5 boys. All patients complained of anterior groin pain. All patients performed a sport/activity that contributed to the symptoms such as dancing. Patients had decreased flexion and limited internal rotation on physical examination. All patients had a positive impingement test. Fifteen patients (43%) had primarily pincer impingement with a crossover sign or acetabular retroversion. Cam impingement was the primary type in 2 patients (6%). There were findings of cam and pincer in 18 patients (51%). Sixteen of 28 patients had a positive labral tear on magnetic resonance imaging (57%). Femoroacetabular impingement is a cause of hip pain in the adolescent population. The diagnosis can be derived from reproducible history, physical examination, and radiographic findings. It is more common in female adolescents, and pincer type is more prevalent.

Embryology of the acetabular labral-chondral complex

Damage to and repair of the acetabular labral-chondral complex are areas of clinical interest in the treatment of young adults with pain in the hip and in the prevention of degenerative arthritis of the hip. There are varying theories as to why most acetabular tears are located anterosuperiorly. We have studied the prenatal development of the human acetabular labral-chondral complex in 11 fetal hips, aged from eight weeks of gestation to term. There were consistent differences between the anterior and posterior acetabular labral-chondral complex throughout all ages of gestation. The anterior labrum had a somewhat marginal attachment to the acetabular cartilage with an intra-articular projection. The posterior labrum was attached and continuous with the acetabular cartilage. Anteriorly, the labral-chondral transition zone was sharp and abrupt, but posteriorly it was gradual and interdigitated. The collagen fibres of the anterior labrum were arranged parallel to the labral-chondral junction, but at the posterior labrum they were aligned perpendicular to the junction. We believe that in the anterior labrum the marginal attachment and the orientation of the collagen fibres parallel to the labral-chondral junction may render it more prone to damage than the posterior labrum in which the collagen fibres are anchored in the acetabular cartilage. The anterior intra-articular projection of the labrum should not be considered to be a pathological feature.

Magnetic resonance imaging of the hip

Standard magnetic resonance imaging (MRI) as well as MR arthrography (MRA) have been important diagnostic tools to assess for a spectrum of clinical presentations related to the hip. MRA has allowed the radiologist to closely examine intracapsular structures such as the acetabular labrum. In this article, we provide a general review of soft tissue and osseous anatomy of hips, especially focusing on the MR appearances of the acetabular labrum and the osseous morphology of the greater trochanter and ischial tuberosity with their muscle and tendon attachments. In addition, current topics in recent literature will be discussed such as femoroacetabular impingement (FAI) and rotator cuff tears of the hip.