Magnetic resonance imaging of labral cysts of the hip

Preoperative Paralabral Cysts Predict More Significant Chondral Damage but Not 2-Year Functional Outcomes Following Arthroscopic Labral Repair

PURPOSE

To investigate whether paralabral cysts identified incidentally on preoperative magnetic resonance imaging/arthrography predict 2-year functional outcomes after arthroscopic acetabular labral repair.

METHODS

Prospectively collected data for patients undergoing primary hip arthroscopy by a single surgeon from 2014 to 2020 were retrospectively reviewed. Included patients were ≥18 years and completed baseline patient-reported outcome measures (PROMs) with additional follow-up at 3, 6, 12, and 24 months. Exclusion criteria were labral debridement, hip dysplasia, advanced hip osteoarthritis (Tönnis > 1), or previous ipsilateral hip surgery. Patients were stratified based on the presence of paralabral cysts identified on magnetic resonance imaging/arthrography. Primary outcomes were International Hip Outcome Tool and modified Harris Hip Score. Secondary outcomes included other PROMs and the visual analog pain scale. Outcomes were compared between cohorts using linear mixed-effects models and Fisher's exact tests. Sensitivity analyses accounted for preoperative PROMs, nonlinear improvement trajectories, and relevant baseline characteristics.

RESULTS

Of the 182 included hips (47.8% female; mean ± standard deviation age, 36.9 ± 11.4), 30 (16.4%) had paralabral cysts. During the 2-year study period, there were no significant differences between patients with and without paralabral cysts in terms of International Hip Outcome Tool scores (weighted difference = 1.60; 95% confidence interval [CI], -5.09, 8.28; P = .64), modified Harris Hip Scores (weighted difference = 0.56; 95% CI, -4.16, 5.28; P = .82), or any secondary outcomes (except for HOS-Sports Subscale at 3 months [mean difference = -11.85; 95% CI, -22.85, -0.84; P = .035]). Furthermore, there were no significant differences in clinically meaningful outcomes (P > .05 for all), revision rates (P > .99), or conversion to total hip arthroplasty between cohorts (P > .99). These results held across all sensitivity analyses.

CONCLUSIONS

Although preoperative paralabral cysts were associated with worse cam impingement and more severe chondral damage observed intraoperatively, they did not predict 2-year functional outcomes or clinically meaningful improvements, suggesting that incidentally discovered paralabral cysts are not a contraindication for arthroscopic labral repair.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Compressive Femoral Mononeuropathy Secondary to Acetabular Labral Tear Associated With Paralabral Ganglion Cyst of an Osteoarthritic Hip: A Case Report

CASE

A 61-year-old man presented with a 5-year history of left hip pain and a 6-month history of left groin swelling associated with hypoesthesia and proximal muscle weakness. Radiograph of the left hip showed degenerative joint disease. Magnetic resonance imaging revealed a large, anteriorly displaced paralabral cyst of the left hip joint. Neurophysiologic studies were corroborative of left femoral mononeuropathy. Complete excision of the cyst along with total hip replacement were performed. At 4-year follow-up, there was complete remission with resolution of symptoms.

CONCLUSIONS

Our experience emphasizes the importance of identifying and addressing the underlying primary pathologic disease for a satisfactory functional outcome.

A posterior labral cyst associated with an anterior labral tear of the hip

Paralabral cysts are often associated with labral and other intraarticular hip pathology; MRI as well as diagnostic ultrasound can assist in diagnosis. Although often considered a coincidental finding, paralabral cysts can be a separate pain generator about the hip through compression of surrounding anatomy. They can also be initially mistaken for malignancy or other pathology by providers unfamiliar with their appearance. We present the case of an active 33-year-old female with right hip pain secondary to a large symptomatic posterior acetabular paralabral cyst with concomitant anterior labral tear. Following diagnosis on MRI, treatment included ultrasound-guided aspiration of the cyst, followed by arthroscopic anterior labral repair and separate cyst decompression from a posterior portal. The patient had complete resolution of her symptoms.

CT-guided aspiration and steroid injection of symptomatic paralabral cysts of the hip

PURPOSE

The objective of this article is to present the clinical use of aspiration and steroid injection under CT guidance for symptomatic paralabral cysts of the hip.

MATERIALS AND METHODS

Four cases of symptomatic paralabral cysts of the hip were treated with aspiration and steroid injection after MR examinations had been performed. The imaging characteristics of the cysts, including the location, size, extracapsular extension, and associated labral tears, were evaluated. Under CT guidance, an 18-gauge spinal needle punctured the cyst, and aspiration was performed using local anesthesia. After irrigation with 50 % diluted iodine contrast material, steroid alone or a mixture of steroid and 1 % lidocaine was injected into the cyst. CT images during and after the procedure, procedural reports, and medical records were reviewed for analysis.

RESULTS

Three cysts were located in the anteroinferior region, while one cyst was located in the posterior region. At the 1-month follow-up, symptom improvement had been achieved in all four patients. However, in the patient who had the largest cyst with extracapsular extension, symptoms recurred after 5 months, and the patient underwent surgery.

CONCLUSION

CT-guided aspiration and steroid injection were feasible for the treatment of symptomatic paralabral cysts of the hip. During the procedures, all four cysts collapsed.

Acetabular paralabral cyst as a rare cause of obturator neuropathy: a case report

An acetabular paralabral cyst is a benign soft tissue cyst usually seen in association with a tear of the acetabular labrum. Acetabular paralabral cysts are often the cause of joint pain, but they rarely cause compression of the adjacent neurovascular structures. We present a case of a 63-year-old male patient who had paresis and atrophy of right hip adductor muscles. Right obturator neuropathy was confirmed through an electrodiagnostic study. In addition, magnetic resonance imaging showed a paralabral cyst in the right acetabulum which extended to the pelvic wall. The patient underwent conservative treatment without surgical procedure. The pain was decreased after 1 month of conservative therapy. The pain was decreased at the 1-month follow-up. Follow-up electromyography showed polyphasic motor unit potentials in adductor magnus and adductor longus muscles. Based on the experience of this case, an acetabular paralabral cyst should be considered as one of the rare causes of obturator neuropathy.

Arthroscopic treatment of femoral nerve paresthesia caused by an acetabular paralabral cyst

This report describes a rare case of femoral nerve paresthesia caused by an acetabular paralabral cyst of the hip joint. A 68-year-old woman presented with a 6-month history of right hip pain and paresthesia along the anterior thigh and radiating down to the anterior aspect of the knee. Radiography showed osteoarthritis with a narrowed joint space in the right hip joint. Magnetic resonance imaging showed a cyst with low T1- and high T2-weighted signal intensity arising from a labral tear at the anterior aspect of the acetabulum. The cyst was connected to the joint space and displaced the femoral nerve to the anteromedial side. The lesion was diagnosed as an acetabular paralabral cyst causing femoral neuropathy. Because the main symptom was femoral nerve paresthesia and the patient desired a less invasive procedure, arthroscopic labral repair was performed to stop synovial fluid flow to the paralabral cyst that was causing the femoral nerve paresthesia. After surgery, the cyst and femoral nerve paresthesia disappeared. At the 18-month follow-up, the patient had no recurrence. There have been several reports of neurovascular compression caused by the cyst around the hip joint. To the authors' knowledge, only 3 cases of acetabular paralabral cysts causing sciatica have been reported. The current patient appears to represent a rare case of an acetabular paralabral cyst causing femoral nerve paresthesia. The authors suggest that arthroscopic labral repair for an acetabular paralabral cyst causing neuropathy can be an option for patients who desire a less invasive procedure.

Arthroscopic treatment of symptomatic paralabral cysts in the hip

Acetabular labral tears or paralabral cysts in the hip are frequently detected using magnetic resonance imaging or arthrography. Unlike parameniscal cysts in the knee and paralabral cysts in the shoulder, reports of the outcomes of surgical treatment for paralabral cysts in the hip recalcitrant to conservative management are limited in the literature.The authors report 2 cases of paralabral cysts in the hip that were treated with arthroscopic surgery. The patients presented with chronic hip pain, and preoperative magnetic resonance imaging showed paralabral cysts at the superior aspect of the acetabulum. After failure of conservative management for more than 6 months, arthroscopic surgery was performed while the patients were under general anesthesia and in a supine position on a fracture table. Arthroscopic examination confirmed the preoperative diagnosis of paralabral cysts with degenerative labral fibrillation or tears in both patients. Arthroscopic cyst decompression and debridement of the degenerative labral tissues were performed using an arthroscopic thermal probe and a shaver.Clinical outcomes, determined by the Harris Hip Score, Western Ontario and McMaster Universities Osteoarthritis Index score, and University of California, Los Angeles activity score, were satisfactory for the 2 patients at 2 and 3 years postoperatively, respectively. Magnetic resonance imaging obtained for 1 patient at 6 months postoperatively showed complete decompression of the paralabral cyst. The authors believe that arthroscopic treatment for symptomatic hip paralabral cysts is a safe and effective procedure with excellent clinical outcomes.

Imaging of sports-related hip and groin injuries

A normally functioning hip joint is imperative for athletes who use their lower extremities with running, jumping, or kicking activities. Sports-related injuries of the hip and groin are far less frequent than injuries to the more distal aspect of the extremity, accounting for less than 10% of lower extremity injuries. Despite the lower incidence, hip and groin injuries can lead to significant clinical and diagnostic challenges related to the complex anatomy and biomechanical considerations of this region. Loads up to 8 times normal body weight have been documented in the joint in common daily activities, such as jogging, with significantly greater force expected during competitive athletics. Additionally, treatment for hip and groin injuries can obviate the participation of medical and surgical specialties, with a multidisciplinary approach frequently required. Delay in diagnosis and triage of these injuries may cause loss of time from competition and, potentially, early onset of degenerative changes. Magnetic resonance imaging (MRI) of the hip has proven to be the gold standard for the diagnosis of sports-related hip and groin injuries in the setting of negative radiographs. With its exquisite soft tissue contrast, multiplanar capabilities, and lack of ionizing radiation, MRI is unmatched in the noninvasive diagnosis of intra-articular and extra-articular pathology, as well as intraosseous processes. This review focuses on MRI of common athletic injuries of the hip and groin, including acetabular labral tears, femoral acetabular impingement syndrome, muscle injuries around the hip and groin (including athletic pubalgia), and athletic osseous injuries.

Paralabral cysts in the hip joint: findings at MR arthrography

PURPOSE

The purpose of this research was to retrospectively characterize paralabral cysts of the hip as seen at MR arthrography.

MATERIALS AND METHODS

After Institutional Review Board approval, 704 patients who had MR arthrography were identified over a 3-year period and 40 patients were identified as having a cyst or fluid collection at the hip by MR report. MR images from these 40 patients were retrospectively reviewed by three radiologists where 18 were found to have a paralabral cyst, which were characterized as follows: location, configuration, contrast filling, size of the cyst, extent, direction, and whether associated osseous changes were present. In addition, the acetabular labrum was assessed for tears and, if present, the location and pattern were characterized.

RESULTS

Paralabral cysts were located anterosuperiorly in 56%, anteriorly in 22%, posterosuperiorly in 17%, and anteroinferiorly in 6% of cases. The vast majority (94%) were multilocular and filled with intra-articular contrast medium. The average dimensions were 8 × 7 × 11 mm. The paralabral cyst demonstrated extracapsular extension in 72% of cases, with 39% located between the ilium and gluteus minimus, and 22% between the ilium and iliopsoas. Remodeling of the ilium adjacent to the cyst was observed in 50% of these cases. A labral tear was at the base of the labrum adjacent to the cyst in 78% of cases, while the tear was isolated to the body of the labrum in 22%. Tears were most commonly anterosuperior (55%) or anterior (28%) in location.

CONCLUSION

Our results show that paralabral cysts of the hip are most commonly located anterosuperiorly, are multilocular, fill with intra-articular contrast medium, have average dimensions up to 11 mm, and often extend extracapsularly between muscle and bone where they may remodel the adjacent ilium.

Identification of acetabular labral pathological changes in asymptomatic volunteers using optimized, noncontrast 1.5-T magnetic resonance imaging

BACKGROUND

Acetabular labral tears as a source of potential hip pain have received a great deal of attention in recent literature. The gold standard for identifying acetabular labral tears is hip arthroscopy, but recent advances in optimized, noncontrast magnetic resonance imaging (MRI) have proven effectiveness in identifying intra-articular hip pathological changes without the invasive nature of hip arthroscopy or gadolinium-enhanced arthrography. There are little data in the literature on imaging results in an asymptomatic population.

PURPOSE

The objective of this study was to use an optimized, noncontrast 1.5-T MRI protocol to identify hip abnormalities, including paralabral cysts, in asymptomatic volunteers.

STUDY DESIGN

Case series (prevalence); Level of evidence, 4.

METHODS

In this study, 42 hips in asymptomatic patients with an average age of 34 years (range, 27-43 years) were prospectively imaged with optimized, noncontrast 1.5-T MRI scans. Two fellowship-trained musculoskeletal radiologists interpreted the scans at 2 different points in time and commented on the presence of labral abnormalities including paralabral cysts. The results were analyzed for both interobserver and intraobserver reliability.

RESULTS

Acetabular paralabral cysts were identified in 11 of 42 (26.2%) and 9 of 42 (21.4%) hips by the 2 respective radiologists, with an interobserver reliability of 90.5% (κ = .74) and intraobserver reliability of 95.2% (κ = .87). In addition, acetabular labral tears were identified in 36 of 42 (85.7%) and 34 of 42 (80.9%) hips, with an interobserver reliability of 90.5% (κ = .70) and intraobserver reliability of 95.2% (κ = .83).

CONCLUSION

Utilizing an optimized, noncontrast 1.5-T MRI protocol, we report the previously undescribed prevalence of acetabular labral pathological abnormalities and paralabral cysts in a young, asymptomatic population. This emphasizes the importance of correlating patient symptoms with history and physical examination when evaluating patients with hip pain and radiographic abnormalities as defined by MRI criteria. These data demonstrate that labral tears can occur without symptoms.

Paralabral cysts of the hip: sonographic evaluation with magnetic resonance arthrographic correlation

This retrospective study demonstrates the sonographic appearance paralabral cysts of the hip with magnetic resonance (MR) arthrography as the reference standard. Consensus review by 2 musculoskeletal radiologists was used to assess the paralabral cysts and determine their characteristics. The 3 paralabral cysts seen on sonography and confirmed with MR arthrography in this study were anechoic or hypoechoic, lobulated, and filled with contrast on MR imaging. A labral tear was also noted in all cases on both sonography and MR arthrography. Sonographic assessment for an anterior hip paralabral cyst and labral tear may be of diagnostic benefit.

MR arthrographic appearance of the postoperative acetabular labrum in patients with suspected recurrent labral tears

OBJECTIVE

The objective of our study was to evaluate the MR arthrographic appearance of the acetabular labrum in patients with a suspected recurrent acetabular labral tear after previous arthroscopic resection of a labral tear.

CONCLUSION

The labrum after excision will appear shortened on MR arthrography. A recurrent labral tear can be diagnosed by the identification on MR arthrography of a new line to the labral surface, an enlarged and distorted labrum, or a new paralabral cyst.

Proximal sciatic nerve intraneural ganglion cyst

Intraneural ganglion cysts are nonneoplastic, mucinous cysts within the epineurium of peripheral nerves which usually involve the peroneal nerve at the knee. A 37-year-old female presented with progressive left buttock and posterior thigh pain. Magnetic resonance imaging revealed a sciatic nerve mass at the sacral notch which was subsequently revealed to be an intraneural ganglion cyst. An intraneural ganglion cyst confined to the proximal sciatic nerve has only been reported once prior to 2009.

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.

Prognostic value of magnetic resonance arthrography for Czerny stage II and III acetabular labral tears

PURPOSE

To assess the intraobserver reliability and prognostic value of magnetic resonance arthrography (MRA) on the basis of postoperative outcome measures following arthroscopic acetabular labral debridement (partial limbectomy).

METHODS

Between January 1999 and November 2000, 24 patients (13 females, 11 males) with an average age of 37.1 years (range, 21 to 56 years) underwent hip arthroscopy for the treatment of presumed acetabular labral tears. All patients underwent preoperative MRA and/or magnetic resonance imaging (MRI); images were evaluated by a single musculoskeletal radiologist on 2 independent occasions. Hip arthroscopy was performed on all patients. Outcomes were assessed by means of the Modified Harris Hip Score (MHHS) and the Short Form-36 (SF-36) questionnaires, which were completed by patients an average of 24.1 months (range, 12 to 55 months) postoperatively. The accuracy of the initial read, as well as the prognostic value of the Czerny MRA classification system for stage II (intrasubstance tears) and stage III (complete avulsions) acetabular labral tears, was assessed.

RESULTS

Twenty-two of 23 tears (96%) were detected on the initial read. On the basis of intraoperative findings, 1 false-positive MRA, 1 false-negative MRA, and 1 incident of MRA overstaging were reported. On repeat interpretation, 23 of 23 (100%) tears were identified, and intraobserver reliability for recording the presence of a tear was excellent (kappa coefficient = 0.96). No difference was noted in outcomes between patients with or without arthroscopic evidence of chondromalacia (all P > .29), or between patients older or younger than 30 years (all P > .34). Likewise, no difference in outcome was seen between 15 patients with Czerny stage II tears revealed on MRA versus 9 patients with Czerny stage III tears (all P > .79).

CONCLUSIONS

MRA is sensitive and accurate for the detection of acetabular labral tears, with excellent intraobserver reliability. Arthroscopic partial limbectomy is successful in two thirds of patients. Patients with Czerny stage II and III tears do not appear to have significantly different outcomes following arthroscopic labral debridement.

LEVEL OF EVIDENCE

Level IV, prognostic case series.

The painful hip: new concepts

Hip pain is a common condition, and the work-up often includes imaging. This article reviews the normal MR anatomy of the hip and the imaging findings of internal derangements, snapping hip, and femoral acetabular impingement. We will describe the role of MR arthrography in evaluating the patient with suspected labral and articular cartilage abnormalities, as well as the pitfalls in interpretation. We will review the causes of a snapping hip, and the role of sonography in evaluating and guiding treatment of the snapping iliopsoas tendon. We will also review the radiographic and MRI signs of femoroacetabular impingement (FAI), a cause of early degenerative joint disease and hip pain.

MR imaging of tumors and tumor-like lesions of the hip

In conclusion, a wide variety of tumors and tumor-like conditions have a predilection for the hip. The imaging evaluation of these lesions begins with radiographs. Radiographs can depict the extent of disease; any characteristic calcifications; and osseous changes, such as remodeling,periosteal reaction, or destruction. MR imaging has emerged as the preferred imaging modality of choice for evaluating osseous and soft tissue masses of the hip by providing information for diagnosis and staging. The MR imaging signal characteristics and enhancement patterns of malignant and benign hip tumors permit specific diagnoses in some cases. Synovial-based tumor-like processes of the hip can be characterized by MR signal characteristics, such as the hemosiderin within PVNS or the cartilage within synovial chondromatosis. Finally, MR imaging can serve to exclude underlying osseous or soft tissue tumors when radiographs display aggressive features of tumor-like processes.

Technical Considerations in MR Imaging of the Hip

MR imaging of the hip presents technical difficulties seldom encountered when imaging other joints. The imager is responsible for surrounding bony and soft tissue structures susceptible to many maladies that can mimic hip pain related to an intra-articular derangement. The anatomic nature of the hip and pelvis present difficulties with application and use of local receiver coils. A lack of hip joint capaciousness and distensibility presents obstacles to acquiring diagnostic images with direct and indirect arthrography. Imagers must strive to improve diagnostic accuracy and maximize the information provided to referring clinicians in each MR imaging report in order to help choose the most appropriate therapeutic course. In this article, the authors review technical considerations specific to patient subsets and suspected causalgia of pain or dysfunction about the hip.

Imaging of the Acetabular Labrum

The acetabular labrum is a critical structure within the hip joint. It is a significant cause of pain, and it plays an integral role in the development of osteoarthritis. This article reviews the normal anatomy, imaging techniques, and normal MR appearance of the labrum. The clinical presentation of labral tears and their association with developmental dysplasia and femoroacetabular impingement are discussed. The controversy regarding the presence or absence of a sublabral sulcus also is addressed.

Magnetic resonance imaging of the hip: detection of labral and chondral abnormalities using noncontrast imaging

PURPOSE

Traditional imaging techniques have limited ability to detect subtle chondral and labral injuries of the hip. We performed a retrospective review of patients who underwent magnetic resonance imaging (MRI) of the hip and subsequent hip arthroscopy in order to evaluate the ability of optimized, noncontrast MRI to identify tears of the acetabular labrum and defects in articular cartilage.

TYPE OF STUDY

Retrospective review of a consecutive sample.

METHODS

Between January 1997 and July 2000, 92 patients had MRI of the hip, followed by arthroscopic surgery of that hip by 1 of 2 surgeons (R.B., D.E.P.). Two musculoskeletal MR radiologists blinded to the initial MRI and surgical findings, independently interpreted the studies, looking for the location and degree of articular cartilage and acetabular labral pathology.

RESULTS

Of the 92 patients studied, each of 2 radiologists correctly identified 83 (94%) and 84 (95%) of the 88 labral tears present at surgery, respectively. There was 92% interobserver agreement on the MRI studies. For articular cartilage defects on the femoral head and acetabulum, there was good agreement (92% and 86% within 1 grade) between MRI and surgical grading and between the 2 MR readers (kappa of 0.8 for femoral head cartilage and 0.7 for acetabular cartilage).

CONCLUSIONS

This study shows that noncontrast MRI of the hip, using an optimized protocol, can noninvasively identify labral and chondral pathology. Such information may facilitate deciding which patients warrant surgical intervention, thus preserving hip arthroscopy as a therapeutic tool.

LEVEL OF EVIDENCE

Level II, Development of Diagnostic Criteria Study.

Arthroscopic intervention in early hip disease

Advancement in diagnostic and therapeutic applications for hip arthroscopy have dispelled previous myths about early hip disease. Arthroscopic findings have established the following facts: Acetabular labral tears do occur; acetabular chondral lesions do exist; tears are most frequently anterior and often associated with sudden twisting or pivoting motions; and labral tears often occur in association with articular cartilage lesions of the adjacent acetabulum or femoral head, and if present for years, contribute to the progression of delamination process of the chondral cartilage. Magnetic resonance arthrography represents an improvement over conventional magnetic resonance imaging, it does have limitations when compared with direct observation. Although indications for hip arthroscopy are constantly expanding, the most common indications include: labral tears, loose bodies, chondral flap lesions of the acetabular or femoral head, synovial chondromatosis, foreign body removal, and crystalline hip arthropathy (gout, pseudogout, and others). Contraindications include conditions that limit the potential for hip distraction such as joint ankylosis, dense heterotopic bone formation, considerable protrusio, or morbid obesity. Complication rates have been reported between 0.5 and 5%, most often related to distraction and include sciatic or femoral nerve palsy, avascular necrosis, and compartment syndrome. Transient peroneal or pudendal nerve effects and chondral scuffing have been associated with difficult or prolonged distraction. Meticulous consideration to patient positioning, distraction time and portal placement are essential. Judicious patient selection and diagnostic expertise are critical to successful outcomes. Candidates for hip arthroscopy should include only those patients with mechanical symptoms (catching, locking, or buckling) that have failed to respond to conservative therapy. The extent of articular cartilage involvement has the most direct relationship to surgical outcomes. Improvements in technique and instrumentation have made hip arthroscopy an efficacious way to diagnose and treat a variety of intra-articular problems.

[Unusual "lipid cysts" in the acetabular labrum of patients with hip joint osteoarthrosis]

Diagnostic pathological examination of surgical specimens from patients with hip joint osteoarthrosis occasionally exhibits as yet undescribed pseudocysts consisting of folded granular membranes in necrotic or chondroid tissues. When stained with Sudan red, the content of these cysts indicates the presence of lipid substances. The presence of S100 protein-positive cells with intracytoplasmic fat vacuoles as well as such cells in the walls indicate that they develop from fat inclusions occurring in the chondroid cells of the labrum. Two different wall structures were detected by electron microscopy. The first type exhibited small walls of a granular material similar to the endoplasmic reticulum that surrounds intracytoplasmic fat globules. The second type consisted of broad layers of very tiny granules indicating a more advanced stage of the development of these cysts. The reason for the occurrence of these "chondrocytogenic lipid cysts" remains unknown-it may be assumed that they are due to mechanical labrum destruction that occurs in osteoarthrosis.

Magnetic resonance imaging of the hip: sports-related injuries

Normal hip disorders do not account for a large proportion of exercise-related injuries, but they can pose a clinical dilemma because symptoms tend to be nonspecific. Conventional radiographs may demonstrate some causes of hip pain, such as stress fractures and degenerative joint disease. Magnetic resonance imaging (MRI) of the hip has proven valuable in the diagnosis of radiographically occult osseous abnormalities and periarticular soft-tissue disorders such as stress fractures, avulsion injuries, musculotendinous abnormalities, and bursitis. Conventional MRI has been less useful in the evaluation of intra-articular lesions, including acetabular labral tears, intra-articular loose bodies, and cartilage lesions. Visualization of intra-articular structures and their abnormalities can be improved by injection of diluted gadolinium, which distends the capsule and leaks into labral tears. This article focuses on the use of conventional radiography and MRI in recreational and professional athletes with painful hip joints. Where possible, MRI is compared with other diagnostic modalities such as bone scan and computed tomography.

Protocols in sports magnetic resonance imaging

Magnetic resonance imaging, with its multiplanar imaging capability and superior soft-tissue contrast, has become the preferred method for imaging sports-related injuries. Advances in gradient technology, receiver coils, and imaging software have allowed the imaging of the injured athlete to take place quickly and at high resolution. Understanding the tissues being imaged, the underlying anatomy, and the capabilities of today's scanners is crucial to the design of intelligent and efficient protocols.

Imaging of hip disorders in athletes

Normal hip joint function is fundamental in running-, jumping-, and kicking-based sporting activities. Hip disorders do not account for a large portion of exercise-related injuries, but they can pose a clinical dilemma since symptoms tend to be non-specific. Conventional radiographs may demonstrate some causes of hip pain, such as stress fractures and degenerative joint disease. Magnetic resonance (MR) imaging of the hip has proven valuable in the diagnosis of radiographically occult osseous abnormalities and periarticular soft tissue disorders such as stress fractures, avulsion injuries, musculotendinous abnormalities, and bursitis. Conventional MR imaging has been less useful in the evaluation of intra-articular lesions including acetabular labral tears, intra-articular loose bodies, and cartilage lesions. The visualization of intra-articular structures and their abnormalities can be improved by the injection of diluted Gadolinium, which distends the capsule and leaks into labral tears. This article will focus on the use of conventional radiography and MR imaging in recreational and professional athletes with painful hip joints, and where possible it will compare MR imaging with other diagnostic modalities such as bone scan and CT.

From the RSNA Refresher Courses. Radiological Society of North America. Chronic adult hip pain: MR arthrography of the hip

This article describes the technique for performance and interpretation of magnetic resonance arthrography of the hip. A description of normal anatomy of the hip is presented, and the appearance of the abnormal labrum is discussed. Labral detachments and tears are the most common clinically significant abnormalities to be identified. These abnormalities are recognized on the basis of the presence of contrast material at the acetabular-labral interface or within the substance of the labrum. Many varied appearances of the labrum have been identified within the asymptomatic population, and the correlation of these appearances is contrasted with those of the abnormal labrum in symptomatic patients. To date, it is difficult to draw conclusions regarding the significance of an absent labrum or of a sulcus at the acetabular-labral junction. Experience suggests that an absent labrum in a symptomatic individual is pathologic and that a sulcus at the anterosuperior acetabular-labral junction may be a normal variant.

Current concepts in magnetic resonance imaging of the adult hip and pelvis

MRI is the diagnostic imaging modality of choice for most disorders of the hip and pelvis in the setting of nondiagnostic plain radiographs. Quality images of the entire pelvis with high-resolution images of the affected hip are recommended. Intravenous gadolinium is administered in cases of suspected soft-tissue or bone infection. MR arthrography enables assessment of the joint space and the acetabular labrum. With MRI, the radiologist has the ability to stage pathological conditions of the hip and pelvis in such a way as to determine prognosis and influence therapeutic decisions.

Association of paralabral cysts with acetabular disorders

OBJECTIVE

Acetabular labral tears may cause considerable pain and predispose patients to premature osteoarthritis. Therefore, early and accurate examination is required. Acetabular labral tears are difficult to view on MR images. We report the association of paralabral ganglion cysts detected on MR imaging with surgically proven acetabular labral disorders.

CONCLUSION

Paralabral cysts may be associated with labral disorders. The appearance of a paralabral cyst on MR imaging is a useful indirect sign of acetabular labral abnormality. Use of this sign may enable earlier and more accurate examination of labral disorders.