Marius R. Schmid

The contour of the femoral head-neck junction as a predictor for the risk of anterior impingement

Impingement by prominence at the femoral head-neck junction on the anterior acetabular rim may cause early osteoarthritis. Our aim was to develop a simple method to describe concavity at this junction, and then to test it by its ability to distinguish quantitatively a group of patients with clinical evidence of impingement from asymptomatic individuals who had normal hips on examination. MR scans of 39 patients with groin pain, decreased internal rotation and a positive impingement test were compared with those of 35 asymptomatic control subjects. The waist of the femoral head-neck junction was identified on tilted axial MR scans passing through the centre of the head. The anterior margin of the waist of the femoral neck was defined and measured by an angle (alpha). In addition, the width of the femoral head-neck junction was measured at two sites. Repeated measurements showed good reproducibility among four observers. The angle alpha averaged 74.0 degrees for the patients and 42.0 degrees for the control group (p < 0.001). Significant differences were also found between the patient and control groups for the scaled width of the femoral neck at both sites. Using standardised MRI, the symptomatic hips of patients who have impingement have significantly less concavity at the femoral head-neck junction than do normal hips. This test may be of value in patients with loss of internal rotation for which a cause is not found.

Association of a Large Lateral Extension of the Acromion with Rotator Cuff Tears

BACKGROUND Factors predisposing to tearing of the rotator cuff are poorly understood. We have observed that the acromion of patients with a rotator cuff tear very often appears large on anteroposterior radiographs or during surgery. The purpose of this study was to quantify the lateral extension of the acromion in patients with a full-thickness rotator cuff tear and in patients with an intact rotator cuff. METHODS The lateral extension of the acromion was assessed on true anteroposterior radiographs made with the arm in neutral rotation. The distance from the glenoid plane to the lateral border of the acromion was divided by the distance from the glenoid plane to the lateral aspect of the humeral head to calculate the acromion index. This index was determined in a group of 102 patients (average age, 65.0 years) with a proven full-thickness rotator cuff tear, in an age and gender-matched group of forty-seven patients (average age, 63.7 years) with osteoarthritis of the shoulder and an intact rotator cuff, and in an age and gender-matched control group of seventy volunteers (average age, 64.4 years) with an intact rotator cuff as demonstrated by ultrasonography. RESULTS The average acromion index (and standard deviation) was 0.73 +/- 0.06 in the shoulders with a full-thickness tear, 0.60 +/- 0.08 in those with osteoarthritis and an intact rotator cuff, and 0.64 +/- 0.06 in the asymptomatic, normal shoulders with an intact rotator cuff. The difference between the index in the shoulders with a full-thickness supraspinatus tear and the index in those with an intact rotator cuff was highly significant (p < 0.0001). CONCLUSIONS A large lateral extension of the acromion appears to be associated with full-thickness tearing of the rotator cuff.

Association Between Rotator Cuff Abnormalities and Reduced Acromiohumeral Distance

OBJECTIVE The purpose of this study was to evaluate the association between rotator cuff abnormalities and reduced acromiohumeral distance. MATERIALS AND METHODS Acromiohumeral distance was measured on conventional radiographs and on MR images. Three age- and sex-matched patient groups each including 21 patients were stratified according to acromiohumeral distance on conventional radiographs (group 1, <or= 7 mm; group 2, 8-10 mm; group 3, > 10 mm). Acromiohumeral distance was related to the presence, location, and size of a rotator cuff tear and the degree of fatty degeneration of the muscle assessed on MR arthrography. The relative influence on acromiohumeral distance of the various MR arthrographic findings was assessed. Spearmans rank correlation and stepwise regression were used for statistical analysis. RESULTS In group 1 (acromiohumeral distance <or= 7 mm) full-thickness supraspinatus tendon tears were present in 90% (19/21) of the patients, infraspinatus tendon tears in 67% (14/21) of the patients, and subscapularis tendon tears in 43% (9/21) of the patients. The size of rotator cuff tendon tears and the degree of fatty degeneration in all rotator cuff muscles showed a significant negative correlation with acromiohumeral distance (p < 0.05). After stepwise regression, a significant relative influence on acromiohumeral distance remained for size of rotator cuff tear (p < 0.0001) and for degree of fatty degeneration of the infraspinatus muscle (p = 0.013). CONCLUSION Tendon tears and fatty muscle degeneration in the rotator cuff correlate with reduced acromiohumeral distance. Size of rotator cuff tear and degree of fatty degeneration of the infraspinatus muscle have the most pronounced influence on acromiohumeral distance.

Peripheral Tear of the Triangular Fibrocartilage: Depiction with MR Arthrography of the Distal Radioulnar Joint

OBJECTIVE Although central tears of the triangular fibrocartilage are easily seen on imaging, peripheral tears of the ulnar attachment are frequently missed. The aim of this study was to evaluate the accuracy of MR arthrography of the distal radioulnar joint in depiction of peripheral tears of the triangular fibrocartilage. MATERIALS AND METHODS Forty-one patients (18 women, 23 men; mean age, 38 years; age range, 18-60 years) underwent MR arthrography and wrist arthroscopy. For MR arthrography, iopamidol (300 mg I/mL) and gadopentetate dimeglumine (4 mmol/L) were injected into the distal radioulnar joint. Consensus review of both MR arthrograms and conventional arthrograms was performed by two experienced musculoskeletal radiologists. Presence or absence of communicating and noncommunicating tears of the ulnar attachment of the triangular fibrocartilage was recorded. Arthroscopy was used as the standard of reference for determining sensitivity, specificity, and accuracy in detection of tears of the ulnar attachment. RESULTS At MR arthrography, communicating tear of the ulnar attachment was diagnosed in three patients, noncommunicating tear in 19 patients, and normal attachment in 19 patients. Arthroscopy revealed peripheral tear of the triangular fibrocartilage in all three patients with communicating tear, in 14 of 19 patients with noncommunicating tear, and in three of 19 patients with normal attachment. The sensitivity was 85% (17/20), specificity was 76% (16/21), and accuracy was 80% (33/41). CONCLUSION MR arthrography of the distal radioulnar joint is accurate in depiction of peripheral tears of the ulnar attachment of the triangular fibrocartilage. These tears often appear as noncommunicating tears extending from the distal radioulnar joint into the triangular fibrocartilage.

Is Impingement the Cause of Jumper’s Knee? Dynamic and Static Magnetic Resonance Imaging of Patellar Tendinitis in an Open-Configuration System

Background Chronic overload is considered the main cause of patellar tendinitis, but it has been postulated that impingement of the inferior patellar pole against the patellar tendon during knee flexion could be responsible. Hypothesis The role of the patellar pole in patellar tendinitis can be determined by dynamic magnetic resonance imaging. Study Design Case-control study. Methods We compared 19 knees with patellar tendinitis and 32 asymptomatic knees of age-matched subjects using an open-configuration magnetic resonance imaging system. Dynamic sagittal images were obtained from full extension to 100° of flexion with and without activation of the quadriceps muscle. The following measurements were made from the images: tendon-patella angle, anteroposterior diameter of the tendon, signal difference-to-noise ratio, the shape of the inferior patellar pole, and the location of the patellar tendon insertion. Results The tendon-patella angle was not significantly different between groups at any flexion angle, with or without quadriceps muscle activation. The insertion site of the patellar tendon differed significantly but not the shape of the inferior pole of the patella. The volume and the signal difference-to-noise ratio of zones of increased intratendinous signal as well as the anteroposterior diameter of the proximal patellar tendon were increased in symptomatic knees. Conclusions The relationship between the patella and the patellar tendon was identical in both groups; therefore, chronic overload seems to be a major cause of patellar tendinitis.

Therapeutic efficacy of facet joint blocks.

OBJECTIVE The objective of our study was to investigate outcome predictors of short- and medium-term therapeutic efficacy of facet joint blocks. MATERIALS AND METHODS Forty-two patients with chronic lower back pain who were undergoing facet joint blocks at one (n = 29) or two (n = 13) levels were analyzed. All patients underwent MRI or CT of the lumbar spine within 5 months before the facet joint blocks. The facet joint blocks were performed under fluoroscopic guidance. A small amount (< 0.3 mL) of iodinated contrast agent, 0.5 mL of local anesthetics and 0.5 mL of steroids, were injected. The initial pain response was prospectively assessed using a visual analogue scale. Additional data, including short-term effect (> 1 week) and medium-term effect (> 3 months), were collected by a structured telephone interview. CT and MRI were reviewed with regard to the extent of facet joint abnormalities. Multiple logistic regression analyses were conducted to identify outcome predictor for efficacy of facet joint blocks. RESULTS A positive immediate effect was seen in 31 patients (74%). A positive medium-term effect was found in 14 patients (33%). Pain alleviated by motion (p = 0.035) and the absence of joint-blocking sensation (p = 0.042) predicted pain relief. However, the extent of facet joint osteoarthritis on MRI and CT was not a significant predictor for outcome (p = 0.57-0.95). CONCLUSION Facet joint blocks appear to have a beneficial medium-term effect in one third of patients with chronic lower back pain and may therefore be a reasonable adjunct to nonoperative treatment. However, outcome appears to depend on clinical, not on morphologic, imaging findings.

MR arthrography in calcific tendinitis of the shoulder: diagnostic performance and pitfalls

The purpose was to assess the diagnostic performance of MR arthrography to diagnose calcific tendinitis of the shoulder and to assess the reasons for diagnostic errors. Standard MR arthrograms of 22 patients with calcific tendinitis and 61 controls were retrospectively analyzed by two independent and blinded radiologists. All cases were consecutively collected from a database. Conventional radiographs were available in all cases serving as gold standard. The supraspinatus was involved in 16, the infraspinatus in four and the subscapularis in two patients. All diagnostic errors were analyzed by two additional readers. Reader 1 correctly detected 12 of the 22 shoulders with and 42 of the 61 shoulders without calcific tendinitis (sensitivity 0.55, specificity 0.66). The corresponding values for reader 2 were 13 of 22 and 40 of 61 cases (sensitivity 0.59, specificity 0.69). Inter-rater agreement (kappa-value) was 0.42. Small size of the calcific deposits and isointensity compared to the surrounding tissue were the most important reasons for false negative results. Normal hypointense areas within the supraspinatus tendon substance and attachment were the main reason for false positive results. In conclusion, MR arthrography is insufficient in the diagnosis of calcific tendinitis. Normal hypointense parts of the rotator cuff may mimic calcific deposits and calcifications may not be detected when they are isointense compared to the rotator cuff. Therefore, MR imaging should not be interpreted without corresponding radiographs.

Real-time MR-guided joint puncture and arthrography: preliminary results.

Abstract. The purpose of this study was to evaluate interactive MR-guided joint puncture with intra-articular application of contrast agent. MR-guided arthrography of the shoulder joint was successfully performed in three patients using an interactive guidance system implemented in an open-configuration MR system. Visualization of the needle pathway and contrast inflow was comparable to that with conventional X-ray fluoroscopy. The position of the intra-articular needle tip was accurately confirmed and subsequent MR arthrography was diagnostic in all cases.

3D MR gastrography: exoscopic and endoscopic analysis of the stomach.

Abstract. The aim of this study was to evaluate the feasibility of MR gastrography, based on 3D MRI following the oral administration of Gd-DOTA-enriched blueberry juice, in order to depict alterations of the gastric wall. The stomachs of three volunteers and three patients were examined on a 1.5-T MR system. Following ingestion of 400 ml of blueberry juice spiked with 2 ml of Gd-DOTA, each subject underwent 3D MR imaging in three positions: 45 ° left lateral decubitus, supine, and 45 ° right lateral decubitus. In each position, a coronal 3D SPGR acquisition consisting of 60 continuous 2-mm slices was acquired over a 35-s breathhold (TR/TE = 4.0/1.8 ms, 40 ° flip angle, 0.5 excitations, voxel size of 1.25 × 1.66 × 2.00 mm). Multiplanar reformats (MPR), maximum intensity projections (MIP), surface shaded displays (SSD), and virtual intraluminal endoscopic views (VIE) were calculated. Magnetic resonance gastroscopy was tolerated well by all subjects without adverse effects. Based on the 3D MRI data sets acquired in various patient positions, all regions of the stomach and the proximal duodenum were visualized to good advantage. Whereas MPR and MIP provided a morphologic overview, SSD and VIE images permitted analysis of the gastric mucosa. Normal mucosa could be differentiated from the course and irregular pattern characterizing carcinomatous infiltration. The 3D SPGR data sets acquired following ingestion of oral Gd-DOTA-spiked blueberry juice permits exoscopic and virtual endoscopic viewing of the stomach.

Imaging findings predicting the outcome of cervical facet joint blocks

To determine which cross-sectional imaging findings predict the short-term outcome of cervical facet joint blocks (FJB) and to evaluate the effect of combined intra-/periarticular versus periarticular injection on pain. Fifty facet joints in 37 patients were included in the study. Single, unilateral FJBs in 24 patients, and bilateral single level FJBs in 13 patients were performed, respectively. In all patients, pain relief was assessed using a visual analogue scale. All computed tomography (CT) examinations were blindly reviewed by two radiologists. Osteoarthritis was rated using the Kellgren classification. The presence of combined intra-/periarticular vs. sole periarticular injection of contrast was evaluated. Kellgren Grades 0 (n=23), 1 (n=5), 2 (n=3), 3 (n=9), and 4 (n=10) were found. Mean pain relief after injection was 35% (range: 0–100%). 40% of all injections were combined intra-/periarticular. There was neither a statistically significant difference between pain relief and combined intra-/periarticular versus sole periarticular injection (p=0.64) nor the grade of osteoarthritis (p=0.49). Pain relief after cervical FJBs does not correlate with morphologic alterations seen on CT. Periarticular FJBs are not less successful than combined intra-/periarticular FJBs.