Extreme hip motion in professional ballet dancers: dynamic and morphological evaluation based on magnetic resonance imaging.

OBJECTIVE: To determine the prevalence of femoroacetabular impingement (FAI) of the cam or pincer type based on magnetic resonance imaging (MRI) in a group of adult female professional ballet dancers, and to quantify, in vivo, the range of motion (ROM) and congruence of the hip joint in the splits position. MATERIALS AND METHODS: Institutional review board approval and informed consent from each volunteer were obtained. Thirty symptomatic or asymptomatic adult female professional ballet dancers (59 hips) and 14 asymptomatic non-dancer adult women (28 hips, control group) were included in the present study. All subjects underwent MRI in the supine position, while, for the dancers, additional images were acquired in the splits position. Labral abnormalities, cartilage lesions, and osseous abnormalities of the acetabular rim were assessed at six positions around the acetabulum. A morphological analysis, consisting of the measurement of the α angle, acetabular depth, and acetabular version, was performed. For the dancers, ROM and congruency of the hip joint in the splits position were measured. RESULTS: Acetabular cartilage lesions greater than 5 mm were significantly more frequent in dancer's hips than in control hips (28.8 vs 7.1%, p = 0.026), and were mostly present at the superior position in dancers. Distribution of labral lesions between the dancers and the control group showed substantially more pronounced labral lesions at the superior, posterosuperior, and anterosuperior positions in dancers (54 lesions in 28 dancer's hips vs 10 lesions in 8 control hips). Herniation pits were found significantly more often (p = 0.002) in dancer's hips (n = 31, 52.5%), 25 of them being located in a superior position. A cam-type morphology was found for one dancer and a retroverted hip was noted for one control. Femoroacetabular subluxations were observed in the splits position (mean: 2.05 mm). CONCLUSION: The prevalence of typical FAI of the cam or pincer type was low in this selected population of professional ballet dancers. The lesions' distribution, mostly superior, could be explained by a "pincer-like" mechanism of impingement with subluxation in relation to extreme movements performed by the dancers during their daily activities.

Noninsertional Achilles tendinopathy treated with gastrocnemius lengthening.

BACKGROUND: Surgery is frequently considered an option for refractory, symptomatic noninsertional Achilles tendinopathy. Gastrocnemius equinus can result in mechanical overload of the Achilles tendon and may be a factor in its etiology. Our hypothesis was that reducing load transmission to the Achilles tendon by gastrocnemius lengthening (Strayer procedure) may be an effective treatment. MATERIALS AND METHODS: A prospective case series of all patients with a minimum 1-year symptomatic noninsertional Achilles tendinopathy who underwent gastrocnemius lengthening was evaluated before surgery, and at 1 and 2 years after surgery. There were 14 patients (17 tendons). RESULTS: One year after surgery, the median American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot score was 100 points, as compared to 71 points preoperatively (p < 0.001). The median total Foot Function Index (FFI) decreased significantly from 39 to 12 points at 1 year (p < 0.001) and remained stable (12 points) at 2 years. An electronic goniometer recorded a mean gain in ankle dorsiflexion of 13 degrees. At 1 year after surgery the MRI in all eight patients (ten tendons) with a preoperative MRI demonstrated a decrease in signal hyperintensity and tendon size, signifying an improvement of the tendinopathy. At 2 years after surgery, patient satisfaction assessment revealed that all but one patient was satisfied with the result and 11 of the 14 (79%) patients were able to resume their previous sporting activities. There were no complications. CONCLUSION: Gastrocnemius lengthening was an effective treatment for chronic Achilles noninsertional tendinopathy. Two-year results show good to excellent clinical outcome.

MRI-based assessment of hip joint translations.

To better understand movement limitations and, to some extent, the pathogenesis of osteoarthritis, it is important to quantitatively measure femoroacetabular translations to assess if any joint subluxation occurs. In this paper, we aim at measuring hip joint displacements from magnetic resonance images (MRI) based on a surface registration technique. Because this measurement is related to the location of the hip joint center (HJC), we investigate and compare different HJC estimation approaches based on patient-specific 3D bone models. We estimate the HJC based on a simulated circumduction while minimizing inter-articular distance changes. Measurements of femoroacetabular translations during low amplitude abductions (80 samples) and extreme flexions (60 samples) in female professional dancers, which is a population potentially exposed to femoroacetabular impingements, do not show any significant subluxation.

MR arthrography of acetabular cartilage delamination in femoroacetabular cam impingement.

PURPOSE: To retrospectively assess the frequency and performance of magnetic resonance (MR) arthrography to help diagnose acetabular cartilage delamination in femoroacetabular impingement (FAI). MATERIALS AND METHODS: Institutional review board approval and informed consent were waived for this retrospective study. Forty-four consecutive patients with FAI of the cam type were included (mean age, 30.7 years; range, 16-49 years), including 30 men (mean age, 30.5 years; range, 16-49 years) and 14 women (mean age, 31.4 years; range, 18-48 years). The inclusion criteria were no previous surgery, surgery within 3 months after MR imaging, and availability of a detailed surgical report with acetabular cartilage findings. MR arthrographic findings were assessed independently by two blinded readers. Findings at surgery served as reference standard. Sensitivity, specificity, accuracy, and kappa statistics for interobserver agreement were calculated. RESULTS: At surgery, acetabular cartilage delamination was seen in 23 (52%) of 44 patients (mean size of cartilage flap from acetabular rim, 7.6 mm; range, 2-30 mm). At MR, patients with fluid signal intensity under the cartilage delamination had a respective sensitivity, specificity, and accuracy of 22%, 95%, and 57% for reader 1 and 30%, 95%, and 61% for reader 2. A hypointense line in the acetabular cartilage on sagittal three-dimensional double-echo steady-state images with water excitation demonstrated moderate diagnostic performance (respective sensitivity, specificity, and accuracy were 70%, 57%, and 64% for reader 1 and 70%, 62%, and 66% for reader 2). Hypointense areas in the acetabular cartilage were quite specific on both coronal intermediate-weighted fat-saturated images (respective sensitivity, specificity, and accuracy were 52%, 90%, and 70% for reader 1 and 74%, 90%, and 82% for reader 2) and coronal T1-weighted images (respective sensitivity, specificity, and accuracy were 35%, 90%, and 61% for reader 1 and 61%, 95%, and 77% for reader 2). CONCLUSION: Cartilage delamination is common in patients undergoing surgery for FAI. Fluid under the cartilage delamination is a specific but rare finding. Hypointense areas in the acetabular cartilage seen on intermediate-weighted fat-saturated or T1-weighted images appear to be helpful diagnostic criteria.

Internal knee derangement assessed with 3-minute three-dimensional isovoxel true FISP MR sequence: preliminary study.

PURPOSE: To prospectively evaluate the accuracy of magnetic resonance (MR) imaging of the knee performed by using a three-dimensional (3D) isovoxel sequence involving an acquisition time of approximately 3 minutes, with surgery as the reference standard. MATERIALS AND METHODS: The study was institutional review board approved. Written informed consent was obtained from all patients. Thirty knees of 29 patients (14 women, 15 men; mean age, 41 years) were prospectively examined by using a 3D isovoxel true fast imaging with steady-state precession (FISP) sequence with water excitation and secondary multiplanar reformations. All patients underwent arthroscopy within 12 days after true FISP MR imaging. Two blinded readers evaluated the MR images. Accuracy for detection of cartilage defects and anterior cruciate ligament (ACL) and meniscal tears, interobserver agreement, and intermethod agreement were calculated. RESULTS: Overall sensitivity, specificity, and accuracy of isovoxel true FISP imaging for the diagnosis of cartilage defects were 45%, 83%, and 76%, respectively, for reader 1 and 63%, 82%, and 83%, respectively, for reader 2. Averaged (for readers 1 and 2) sensitivity, specificity, and accuracy of isovoxel true FISP imaging were, respectively, 80%, 95%, and 90% for diagnosis of ACL tear; 100%, 82%, and 90% for diagnosis of medial meniscal tear; and 83%, 83%, and 83% for diagnosis of lateral meniscal tear. The standard MR sequences used at the authors' institution had overall sensitivities, specificities, and accuracies of 39%, 83%, and 71%, respectively, for reader 1 and 37%, 85%, and 76%, respectively, for reader 2. Averaged sensitivity, specificity, and accuracy of the standard MR sequences were, respectively, 70%, 100%, and 90% for diagnosis of ACL tear; 96%, 77%, and 85% for diagnosis of medial meniscal tear; and 83%, 77%, and 78% for diagnosis of lateral meniscal tear. CONCLUSION: The diagnostic performance of knee MR imaging performed by using a 3D water excitation isovoxel true FISP sequence and an imaging time of approximately 3 minutes is comparable to the diagnostic performance of the MR sequences used as standards at the authors' institution.

Articular cartilage defects detected with 3D water-excitation true FISP: prospective comparison with sequences commonly used for knee imaging.

PURPOSE: To prospectively compare the accuracy of three-dimensional (3D) water-excitation (WE) true fast imaging with steady-state precession (FISP) in the diagnosis of articular cartilage defects with that of sequences commonly used to image the knee, with arthroscopy or surgery as the reference standard. MATERIALS AND METHODS: This study protocol was institutional review board approved. Written informed consent was obtained from all patients. Thirty knees in 29 patients (mean age, 56 years; range, 18-86 years) were prospectively evaluated by using sagittal 3D WE true FISP with two section thicknesses (1.7 mm [true FISPthin] and 3.0 mm [true FISPthick]), two-dimensional (2D) intermediate-weighted spin-echo with fat saturation, 2D fast short inversion time inversion-recovery, 3D WE double-echo steady-state, and 3D fat-saturated fast low-angle shot sequences. Cartilage defects were graded on magnetic resonance images and during surgery with a modified Noyes scoring system. Contrast-to-noise ratio (CNR) and CNR efficiency were calculated. Sensitivity, specificity, and accuracy were assessed. Interobserver agreement was determined with kappa statistics, and quantitative results were evaluated with the Wilcoxon signed rank test. RESULTS: The performance of 3D WE true FISPthick (sensitivity, specificity, and accuracy, respectively, were 52%, 93%, and 71% for reader 1 and 65%, 88%, and 76% for reader 2) and 3D WE true FISPthin (sensitivity, specificity, and accuracy, respectively, were 58%, 94%, and 75% for reader 1 and 63%, 80%, and 71% for reader 2) sequences was no different than that of other sequences in the detection of circumscribed defects. Three-dimensional WE true FISP sequences had a significantly (P<.0033) higher CNR and CNR efficiency between cartilage and fluid than the corresponding sequences with the same section thickness. CONCLUSION: Three-dimensional WE true FISP enables high contrast between joint fluid and articular cartilage and a diagnostic performance that is comparable with that of standard sequences.

Bone marrow changes on STIR MR images of asymptomatic feet and ankles.

The purpose of this study was to evaluate the prevalence, pattern and size of bone marrow changes on short-tau inversion recovery (STIR) magnetic resonance (MR) images of asymptomatic feet and ankles. In 78 asymptomatic volunteers (41 women, 37 men; median age 47 years; range 23-83 years) sagittal STIR MR images of hindfoot and midfoot were reviewed for various patterns of high signal changes in bone marrow. The size of these bone marrow changes was measured, and signal intensity was rated semi-quantitatively using a scale from 0 (=normal) to 10 (=fluid-like). Fifty percent (39/78) of all volunteers had at least one bone marrow change. Thirty-six percent (28/78) of all volunteers had edema-like changes, 26% (20/78) had necrosis-like changes, and 5% (4/78) had cyst-like changes. The long diameters of all changes varied between 4 mm and 16 mm (median 7.5 mm). The median signal intensity for all changes was 5.0 (range 1-10). Bone marrow changes on STIR MR images are commonly detected in asymptomatic feet and ankles. However, such changes tend to be small (<1 cm) or subtle.

Diagnosis of articular cartilage abnormalities of the knee: prospective clinical evaluation of a 3D water-excitation true FISP sequence.

PURPOSE: To prospectively evaluate the accuracy of three-dimensional (3D) water-excitation true fast imaging with steady-state precession (FISP) in the assessment of cartilage abnormalities of the knee, by using surgery as the reference standard. MATERIALS AND METHODS: The study was approved by the hospital institutional review board. Written informed consent was obtained from all patients. Twenty-nine patients (30 knees) with a mean age of 56 years (range, 18-86 years) were prospectively evaluated with a sagittal 3D true FISP magnetic resonance (MR) sequence. The mean interval between MR imaging and surgery was 1 day (range, 0-9 days). During surgery, the articular surfaces of the knee were evaluated by using a modified Noyes score. The MR images were evaluated by two blinded readers on two separate occasions. Diagnostic performance was evaluated by setting the cutoff for abnormality between grade 1 (intact cartilage surface) and grade 2 (cartilage defects). Statistical methods used included calculation of sensitivity, specificity, and accuracy, with 95% confidence intervals (Wilson score method) and calculation of kappa values with standard errors. RESULTS: Overall sensitivity, specificity, and accuracy for the two readers and the two evaluations ranged from 56% to 66%, 78% to 93%, and 71% to 75%, respectively. Interobserver agreement was substantial for both the first (kappa = 0.73) and the second (kappa = 0.65) evaluation. Intraobserver agreement was almost perfect (kappa = 0.84) for reader 1 and moderate (kappa = 0.60) for reader 2. CONCLUSION: The 3D water-excitation true FISP MR sequence allows assessment of the articular cartilage of the knee with moderate-to-high specificity and low-to-moderate sensitivity.

MR arthrography of the shoulder, hip, and wrist: evaluation of contrast dynamics and image quality with increasing injection-to-imaging time.

OBJECTIVE: The purpose of our study was to investigate the contrast dynamics and the relationship between visualization of intraarticular structures and time elapsed between intraarticular injection of contrast agent and MRI in symptomatic patients referred for MR arthrography of the shoulder, hip, and wrist. SUBJECTS AND METHODS: Our local ethics committees and the national drug administration approved this multicentric study. We prospectively studied 11 shoulders, 11 hips, and 10 wrists. After the intraarticular gadolinium injection, patients underwent a baseline MR arthrography protocol (time point [TP] 1) and subsequent MRI at another four time points (TP 2-TP 5) up to 240 minutes. The course of contrast-to-noise ratio (CNR) over time was calculated. Three observers assessed the degree of visualization of different intraarticular structures and the overall image quality at each time point using a 3-point scale and a 5-point scale, respectively. RESULTS: For all joints, CNR measurements showed peak CNR at TP 1 (21 minutes) and TP 2 (45 minutes) with a subsequent, near-logarithmic decline of CNR values over time. Visualization of different anatomic structures decreased over time. Overall image quality was insufficient for diagnostic purposes at TP 3 (96 minutes) in three (27%) of 11 shoulders and in three (27%) of 11 hips. In two (20%) of 10 wrists, image quality was insufficient at TP 2 (45 minutes). CONCLUSION: For MR arthrography, the degree of visualization of intraarticular structures depends on the time elapsed between contrast injection and MRI. MR arthrography of the shoulder and hip should be performed within 90 minutes, and MR arthrography of the wrist should be performed within 45 minutes, after intraarticular injection.

Improved visualization of collateral ligaments of the ankle: multiplanar reconstructions based on standard 2D turbo spin-echo MR images.

The purpose of the study was to evaluate the visualization of the collateral ankle ligaments on multiplanar reconstructions (MPR) based on standard 2D turbo spin-echo images. Coronal and axial T2-weighted turbo spin-echo and MPR angled parallel to the course of the ligaments of 15 asymptomatic and 15 symptomatic ankles were separately analyzed by two musculoskeletal radiologists. Image quality was assessed in the asymptomatic ankles qualitatively. In the symptomatic ankles interobserver agreement and reader confidence was determined for each ligament. On MPR the tibionavicular and calcaneofibular ligaments were more commonly demonstrated on a single image than on standard MR images (reader 1: 13 versus 0, P=0.002; reader 2: 14 versus 1, P=0.001 and reader 1: 13 versus 2, P=0.001; reader 2: 14 versus 0, P<0.001). The tibionavicular ligament was considered to be better delineated on MPR by reader 1 (12 versus 3, P=0.031). In the symptomatic ankles, reader confidence was greater with MPR for all ligaments except for the tibiocalcanear ligament (both readers) and the anterior and posterior talofibular ligaments (for reader 2). Interobserver agreement was increased with MPR for the tibionavicular ligament. Multiplanar reconstructions of 2D turbo spin-echo images improve the visualization of the tibionavicular and calcaneofibular ligaments and strengthen diagnostic confidence for these ligaments.

Prospective evaluation of two different injection techniques for MR arthrography of the hip.

The aim of the study was to evaluate prospectively the technical feasibility and discomfort of two different injection techniques for MR arthrography of the hip. Sixty-one consecutive patients undergoing MR arthrography of the hip (68 hips) were randomly injected either at the femoral head (36 hips) or the femoral neck (32 hips). The patients rated discomfort during and 0-72 h after arthrography using a visual analogue scale (VAS, 0="did not feel anything", 100="unbearable"). The volume injected, the distance between the needle tract and the neurovascular bundle, the duration of the procedure and the extra-articular contrast leakage were measured. No significant differences were found for the volume injected, the distance between the needle tract and the neurovascular bundle, or the procedure duration. Volume of extra-articular contrast leakage was statistically significantly different (head 1+/-2 cm(3), neck 3+/-5 cm(3), P=0.024). The VAS score for needle advancement was significantly different (head 25+/-20, neck 19+/-23, P=0.031). No significant differences were found for the VAS score regarding delayed discomfort. Before the examination the arthrography-related discomfort was overestimated by 74% (50/68), correctly anticipated by 22% (15/68) and underestimated by 4% (3/68) of the patients. MR-related discomfort was overestimated by 32% (22/68), correctly anticipated by 57% (39/68) and underestimated by 10% (7/68) of the patients. Both hip puncture techniques were well tolerated. The neck injection technique produced less discomfort and was associated with greater extra-articular contrast leakage.

Diagnostic performance of MR arthrography after rotator cuff repair.

OBJECTIVE: The objective of this study was to investigate the diagnostic performance of MR arthrography after rotator cuff repair. MATERIALS AND METHODS: MR arthrographic examinations of the shoulder performed after rotator cuff repair and before revision surgery were retrospectively analyzed in 48 patients (31 males, 17 females; mean age, 50.3 years; age range, 17-69 years). Full-thickness and partial-thickness defects of the supraspinatus, infraspinatus, and subscapularis tendons were diagnosed independently by two radiologists. Revision surgery served as the standard of reference. RESULTS: Observer 1 correctly recognized five of eight intact supraspinatus tendons, 10 of 19 partial-thickness defects, and 19 of 21 full-thickness defects. For observer 2, the numbers were three of eight, eight of 19, and 18 of 21. The corresponding numbers for the infraspinatus tendon for observer 1 were 28 of 31, 0 of three, and 14 of 14 tendons. For observer 2, they were 28 of 31, two of three, and 11 of 14. For the subscapularis tendon, observer 1 made the correct diagnosis in 18 of 31, five of six, and nine of 11 tendons. The results for observer 2 were 26 of 31, one of six, and 10 of 11 tendons. Interobserver agreement (weighted kappa) was 0.47 for the supraspinatus, 0.64 for the infraspinatus, and 0.20 for the subscapularis tendons, respectively. CONCLUSION: Postoperative full-thickness defects of the rotator cuff are reliably diagnosed with MR arthrography. The diagnostic performance for partial-thickness defects is only moderate.

Recanalization of acute and subacute femoropopliteal artery occlusions with the rotarex catheter: one year follow-up, single center experience.

PURPOSE: To assess the efficacy and safety of a new rotational catheter for percutaneous removal of fresh and organized thrombi in the femoropopliteal artery. METHODS: Forty-one limbs in 38 patients (age 56--90 years, mean 75.6 years) with acute, subacute or chronic femoropopliteal occlusions of 1--180 days' duration (mean 31.6 days) were treated with the Rotarex device. The Fontaine stage was mainly IIB (Rutherford 2--3, 22 patients) or III (Rutherford 4, 14 patients). The length of occlusion varied from 2 to 35 cm (mean 13.1 cm). After recanalization percutaneous transluminal angioplasty (PTA) was performed if there was a residual stenosis of >25%. Patients were followed up with color Doppler ultrasound at 48 hr and clinically with Doppler pressures and oscillometry at 3, 6, and 12 months. RESULTS: After an average of two passages with the Rotarex catheter all but two limbs required PTA for residual stenosis >25%. Five patients needed additional stenting. Major complications were one groin hematoma requiring blood transfusion and one arteriovenous fistula spontaneously thrombosing after unsuccessful primary prolonged balloon dilation. Distal embolizations occurred in 10 patients; 6 clinically relevant emboli were aspirated. All occlusions were technically successfully recanalised there were 2 early reocclusions after 1 day and two at 2 weeks. Brachial-ankle indices improved from an average of 0.41 before to 0.93 after recanalization. Primary and secondary patency rates were 62% / 84% after 6 months and 39% / 68% after 1 year. The amputation-free survival at 12 months was 100%. CONCLUSION: The Rotarex mechanical thrombectomy device is an efficient, quick, easy to handle, and safe tool for the treatment of acute, subacute or even chronic peripheral arterial thromboembolic occlusions. It can be used for short or long occlusions with equal success, provided the obstruction is not heavily calcified and has been safely passed with a guidewire first.

First report of an accessory popliteal muscle: detection with MRI.

During an MRI examination of the knee in a 48-year-old patient suffering from degenerative changes of a partly resected medial meniscus and concomitant osteoarthritis of the knee joint, an unusual variant of an accessory muscle in the popliteal fossa was found. To our best knowledge this muscle has never been described before. Because of the close relationship to the popliteal muscle with regard to course and localisation in the deep popliteal fossa ventral to the popliteal artery, the term "accessory popliteal muscle" is proposed.