Michael R. Terk

MRI of the achilles tendon: A comprehensive review of the anatomy, biomechanics, and imaging of overuse tendinopathies

The Achilles tendon is the largest tendon in the body; it plays an important role in the biomechanics of the lower extremity. It can withstand great forces, especially during sporting exercises and pivoting. The pathologies related to the Achilles tendon are diverse and many carry undesirable consequences. We retrospectively analyzed the images of patients who underwent examinations of the ankle/foot region to review the anatomy of the Achilles tendon and its surroundings and to search for pathologies consistent with overuse injuries. The anatomy of the tendon is described from origin to insertion. The imaging characteristics of the Achilles tendon including pitfalls are reviewed. We also describe the Achilles overuse injuries: paratenonitis, tendinosis, tendon tear, atypical tear, tendon re-tear, retrocalcaneal bursitis, retro-Achilles bursitis, Haglunds deformity, and tendon calcification. We present other entities like tendon ossification and failed transplanted Achilles tendon, with emphasis on MRI.

Patella Alta: Lack of Correlation Between Patellotrochlear Cartilage Congruence and Commonly Used Patellar Height Ratios

OBJECTIVE The purposes of this study were to assess the degree of patellotrochlear chondral overlap (patellotrochlear index), correlate it with the Insall-Salvati and modified Insall-Salvati indexes, and determine the association between these measurements and patellofemoral chondral defects. MATERIALS AND METHODS Sagittal 1.5-T and 3-T MR images of 100 consecutively registered patients with symptoms were analyzed, and the Insall-Salvati index, modified Insall-Salvati index, patellotrochlear index, and patellophyseal index (ratio of the height of patella above the physeal line to the length of the patellar articular cartilage) were calculated. The upper and lower limits of 2 SDs were used to define patella alta and baja, and the correlation coefficient curves were plotted to compare techniques. The indexes in normal knees were compared with those in knees with severe chondral defects. RESULTS The mean patellotrochlear index was 0.49 +/- 0.15 (SD) (range, 0-0.88). On the basis of calculation of 2 SDs, patella alta was determined to have a patellotrochlear index less than 0.18 and patella baja, an index greater than 0.80. Weak correlation was found between the measured patellotrochlear index and Insall-Salvati index (r = -0.224) and between the patellotrochlear index and modified Insall-Salvati index (r = -0.073). A strong correlation was found between the patellotrochlear index and patellophyseal index (r = -0.813). A statistically significant (p < 0.05) difference in the modified Insall-Salvati index and patellophyseal index was found between knees with normal and those with severe cartilage defects. CONCLUSION Our results indicate that the commonly used Insall-Salvati and modified Insall-Salvati indexes do not correlate with patellotrochlear articular cartilage congruence. We did find an association between the modified Insall-Salvati and patellophyseal indexes and the presence of severe chondral defects.

Analysis of the patellofemoral region on MRI: association of abnormal trochlear morphology with severe cartilage defects.

OBJECTIVE The objective of our study was to assess patellofemoral measurements on MRI and to correlate the measurements with different grades of cartilage defect. MATERIALS AND METHODS Axial and sagittal MR images of 100 patients with various pathologic knee conditions were analyzed. The patients were divided into two age groups: < 40 years and > or = 40 years. Patellar measurements of facet asymmetry, the patella-to-patellar tendon ratio, and the amount of patellotrochlear cartilage overlap were obtained in each subject. Similarly, trochlear measurements of the ventral trochlear prominence, trochlear depth, facet asymmetry, sulcus angle, and lateral inclination were obtained. Axial and sagittal MR images were reviewed to grade the severity of focal cartilage defects in the patellofemoral region on the basis of the depth of the lesion. Measurements in knees without a chondral defect were compared with knees with mild and severe chondral defects. RESULTS There was a statistically significant difference in the trochlear measurements of the ventral prominence (p = 0.012), trochlear depth (p = 0.001), sulcus angle (p = 0.208), and lateral inclination (p = 0.154) between normal knees and knees with severe cartilage defects in patients younger than 40 years. No significant difference was seen in the patellar measurements between normal knees and knees with severe cartilage defects. CONCLUSION There is an association between abnormal trochlear morphology and severe patellofemoral cartilage defects in patients younger than 40 years.

Recombinant human bone morphogenetic protein 2-induced heterotopic ossification of the retroperitoneum, psoas muscle, pelvis and abdominal wall following lumbar spinal fusion

A 45-year-old man presented with vertebral collapse at L5 as an initial manifestation of multiple myeloma and underwent spinal fusion surgery using recombinant human bone morphogenetic protein-2 (rhBMP-2). Subsequent computed tomography (CT) scans and X-rays revealed heterotopic ossification of the left psoas muscle, pelvis, and anterior abdominal wall. While the occurrence of heterotopic ossification has previously been reported when rhBMP-2 has been used for spinal fusion surgery, this case demonstrates that it can occur to a much greater degree than previously seen.

Diagnostic Utility of MRI and MR Arthrography for Detection of Ligamentum Teres Tears: A Retrospective Analysis of 187 Patients With Hip Pain

OBJECTIVE The purpose of this study was to compare the diagnostic utility of MRI and MR arthrography for ligamentum teres tears in patients with hip pain. MATERIALS AND METHODS This is a retrospective study involving 187 patients who underwent MRI or MR arthrography for hip pain. This study included 103 male and 84 female patients with average age of 39 years. Three experienced musculoskeletal radiologists reviewed the MRI and MR arthrography studies to assess the ligamentum teres tears. The criteria for diagnosing normal or abnormal (i.e., ligament), partial or degenerative or complete tear of ligamentum teres were defined on the basis of several imaging characteristics. The MRI and MR arthrography results were correlated with arthroscopy, which served as the reference standard. Statistical analysis was performed to calculate the diagnostic yield, diagnostic accuracy, and diagnostic performance of MRI and MR arthrography in detecting partial or degenerative and complete ligamentum teres tears. Overall comparative performance of MRI and MR arthrography was assessed using Kruskal-Wallis test. RESULTS For partial ligamentum teres tears, MRI showed lower sensitivity, specificity, and positive predictive value (0.41, 0.75, and 0.32, respectively) as compared to MR arthrography (0.83, 0.93, and 0.76, respectively), whereas the negative predictive value of MRI (0.82) was comparable to that of MR arthrography (0.95). No statistically significant difference (p < 0.05) could be identified between MRI and MR arthrography for diagnosing complete ligamentum teres tears. CONCLUSION Hip MRI is equally suited for diagnosis of complete ligamentum teres tears when compared with MR arthrography. By contrast, for partial or degenerative ligamentum teres tears, MR arthrography offers the advantage of better arthroscopic correlation.

Multiple occult wrist bone injuries and joint effusions: prevalence and distribution on MRI

This study aims (1) to assess the prevalence and distribution of multiple occult injuries of the carpal bones and the distal forearm in patients with wrist pain and negative radiographs following trauma and (2) to evaluate the distribution and significance of joint effusions in the wrists with multiple osseous injuries. One hundred and thirty-one subjects, 74 men and 57 women, were consecutively examined in two institutions. All were acute trauma patients with negative X-rays whose clinical examination suggested possible fracture at the wrist or the distal forearm. Magnetic resonance (MR) wrist imaging was performed with and without fat saturation sequences. The MR images were analysed for detection of occult trabecular contusions and cortical discontinuity in the carpus, the distal forearm and the metacarpal bases. The prevalence and distribution of the injuries were assessed along with the distribution of joint effusions. Eight patients were excluded due to inadequate image quality. Two patients had bilateral injury. A total of 125 wrists were analysed. Seventy-eight (62.4%) wrists had occult bone injuries. Among these 78, 53 (68%) wrists had more than one injured bone. Twenty-five wrists (32%) had one injured bone. The highest number of injured bones per wrist was six. Injuries with a visible fracture line were seen in 29 (37.1%) wrists on MRI. The distal radius was the most frequent location for occult fracture line (11 cases). The injuries without a fracture line (contusion) were present in 49 (63%) wrists; they were detected more frequently in the scaphoid (35 cases). The lunate (29 cases) and the triquetrum (26 cases) were almost equally affected. The bone that was less frequently injured was the pisiform (four cases). Joint effusions were present in all 53 wrists with multiple bone lesions but more often situated in the ulnocarpal space [27 (50.3%) wrists]. There was no correlation between effusions in multiple locations (grades III and IV) and multiple bone injuries. This study revealed the presence of multifocal trabecular contusions without correlation with increased joint effusions in patients with negative radiographs and persistent pain. The clinical significance of these findings deserves further investigation.

Tibial subacute osteomyelitis with intraosseous abscess: an unusual complication of intraosseous infusion.

Intravenous (IV) access is a critical step in patient care, especially in the emergency and/or trauma setting. Recently, intraosseous (IO) infusion has re-emerged as a recommended alternative to central venous access in both the pediatric and the adult patient. We present the case of an older adult male patient several months after emergency tibial IO infusion, now with left shin pain, and the MRI and culture findings diagnostic of subacute osteomyelitis with IO abscess, an unusual complication of IO infusion.

Adult onset glycogen storage disease type II (adult onset Pompe disease): report and magnetic resonance images of two cases.

Glycogen storage disease type II (GSDII), also referred to as Pompe disease or acid maltase deficiency, is a rare inherited condition caused by a deficiency in acid alpha-glucosidase (GAA) enzyme activity (Tinkle and Leslie. GeneReviews, 2008. http://www.genetests.org). The condition is often classified by age of presentation, with infantile and late onset variants (Laforet et al. J Neurology 55:1122–8, 2000). Late onset tends to present with progressive proximal muscle weakness and respiratory insufficiency (Winkel et al. J Neurology 252:875–84, 2005). We report two cases of biopsy confirmed adult onset GSDII, along with key Magnetic Resonance (MR) images.

Radiological and clinical characterization of the lysosomal storage disorders: non-lipid disorders

Lysosomal storage diseases (LSDs) are a large group of genetic metabolic disorders that result in the accumulation of abnormal material, such as mucopolysaccharides, glycoproteins, amino acids and lipids, within cells. Since many LSDs manifest during infancy or early childhood, with potentially devastating consequences if left untreated, timely identification is imperative to prevent irreversible damage and early death. In this review, the key imaging features of the non-lipid or extralipid LSDs are examined and correlated with salient clinical manifestations and genetic information. Disorders are stratified based on the type of excess material causing tissue or organ dysfunction, with descriptions of the mucopolysaccharidoses, mucolipidoses, alpha-mannosidosis, glycogen storage disorder II and cystinosis. In addition, similarities and differences in radiological findings between each of these LSDs are highlighted to facilitate further recognition. Given the rare and extensive nature of the LSDs, mastery of their multiple clinical and radiological traits may seem challenging. However, an understanding of the distinguishing imaging characteristics of LSDs and their clinical correlates may allow radiologists to play a key role in the early diagnosis of these progressive and potentially fatal disorders.

MRI of the cuboid bone: Analysis of changes in diabetic versus non-diabetic patients and their clinical significance

OBJECTIVES (1) To investigate the association between diabetes and marrow changes in the cuboid; and (2) to evaluate the influence of age, gender, body mass index (BMI) and use of insulin in the occurrence of marrow changes in the cuboid. RESEARCH DESIGN AND METHODS MR and X-ray foot examinations of 237 patients [94 males, 143 females; mean age, 47.1 years (range 16-93 years)], five of whom underwent bilateral examinations, were reviewed. MR and radiographic studies were analyzed for the presence of marrow edema and fractures in the cuboid. Findings were correlated with demographic data (age, gender) and clinical information (BMI and use of insulin). RESULTS Two hundred and forty two feet - 69 diabetic and 173 non-diabetic - were retrospectively evaluated. There was a higher prevalence of marrow edema and fractures in the diabetic cuboid (n=31, 45%) compared to non-diabetic cuboid (n=25, 14%, p=0.02). A fracture line was seen in fourteen (20%) diabetic cuboid bones compared to 4 (2%) in non-diabetic cuboid bones (p<0.0001). Eleven (79%) cases of cuboid fractures in the diabetic population were radiographically occult. Multivariate data analysis revealed an adjusted odds ratio of 4.416 (95% CI; 2.307, 8.454) for the relationship between marrow changes (edema and fractures) in the cuboid and diabetes. For each year of age, the odds of changes in the cuboid increased by 2.2% (95% CI; 1.001, 1.044). CONCLUSION Despite not bearing weight, the cuboid bone is more vulnerable to marrow edema and fractures in diabetic patients compared to non-diabetic patients. Age seems to be an influential factor.