Knee Imaging Following Anterior Cruciate Ligament Reconstruction: The Surgeon's and Radiologist's Perspectives.

Anterior cruciate ligament (ACL) tears are common injuries that if left untreated can result in chronic instability, cartilage damage, meniscal tears, and ligamentous injuries, eventually leading to early osteoarthritis. ACL reconstruction surgeries are therefore increasingly being performed. Despite the fact that most patients achieve excellent postoperative results, patients can present with recurrent instability and pain. These patients often undergo imaging with radiographs, magnetic resonance imaging, and/or computed tomography. An understanding of the imaging appearance of the normal ACL reconstruction and common causes of failure is therefore essential for the interpreting radiologist. This article reviews surgical techniques for ACL reconstruction, highlighting recent technical advances, the normal imaging appearance after ACL reconstruction, etiologies for reconstruction failure, and the diagnosis of these with the aid of imaging.

Lipidus migrans-a radiology imaging feature after ankle injury.

We present an uncommon imaging feature with fluid fat tracking within the tendon sheath of the flexor hallucis longus (FHL) after traumatic injury to the ankle joint. We propose a coined medical term "lipidus migrans" to define the presence of floating fat in a tendon sheath. This is due to lipohemarthrosis from intra-articular fracture of the ankle with leakage of fluid fat into the tendon sheath. Communication between the FHL tendon sheath and ankle joint can occur in up to 25% of patients. Radiologists should be aware of the presence of lipidus migrans as a potential posttraumatic complication after intra-articular ankle fracture and that fat in the tendon sheath may mimic fracture fragments or even a tendon sheath tumor.

Growth plate injury at the base of the coracoid: MRI features.

PURPOSE: To assess the MRI features of growth plate injury at the base of the coracoid process. MATERIALS AND METHODS: Subjects were identified through retrospective search of our department imaging database and teaching files and the teaching files of two outside academic institutions. The coracoid base growth plate was examined with attention to widening, irregularity, abnormal signal intensity of the growth plate, and the presence of adjacent soft tissue edema. The apposing coracoid and scapular bony surfaces were examined for signal intensity and morphology. RESULTS: Shoulder MRIs in eight patients with coracoid base growth plate disturbances were retrospectively reviewed (7 males, 1 female, mean age 15 years). Growth plate injury manifested as widening, irregularity and increased signal, apposing bony marrow edema and hypertrophy, and surrounding soft tissue edema. Five subjects were athletes (football, archery, basketball, swimming, rugby), two had a history of neuromuscular disorders, and one subject presented after a fall. Clinical indications included: rule out labral tear (n = 3), rule out rotator cuff tear or fracture after fall (n = 1), nonspecific pain (n = 1), shoulder subluxation, rule out glenoid pathology (n = 1, patient with underlying neuromuscular disorder), muscular dystrophy with shoulder pain (n = 1), and impingement (n = 1). Coracoid growth plate injury was not suspected clinically in any of the patients. CONCLUSION: Awareness of the imaging appearance of coracoid base growth plate injury can aid in a more accurate diagnosis of shoulder MRI studies in young pediatric athletes. While uncommon, coracoid growth plate injury should be considered when assessing children with shoulder symptomatology.

Evaluation of Chondrocalcinosis and Associated Knee Joint Degeneration Using MR Imaging: Data from the Osteoarthritis Initiative.

OBJECTIVES: To evaluate the ability of different MRI sequences to detect chondrocalcinosis within knee cartilage and menisci, and to analyze the association with joint degeneration. METHODS: Subjects with radiographic knee chondrocalcinosis (n = 90, age 67.7 ± 7.3 years, 50 women) were selected from the Osteoarthritis Initiative and matched to controls without radiographic chondrocalcinosis (n = 90). Visualization of calcium-containing crystals (CaC) was compared between 3D T1-weighted gradient-echo (T1GE), 3D dual echo steady-state (DESS), 2D intermediate-weighted (IW), and proton density (PD)-weighted fast spin-echo (FSE) sequences obtained with 3T MRI and correlated with a semiquantitative CaC score obtained from radiographs. Structural abnormalities were assessed using Whole-Organ MRI Score (WORMS) and logistic regression models were used to compare cartilage compartments with and without CaC. RESULTS: Correlations between CaC counts of MRI sequences and degree of radiographic calcifications were highest for GE (rT1GE = 0.73, P < 0.001; rDESS = 0.68, P < 0.001) compared to other sequences (P > 0.05). Meniscus WORMS was significantly higher in subjects with chondrocalcinosis compared to controls (P = 0.005). Cartilage defects were significantly more frequent in compartments with CaC than without (patella: P = 0.006; lateral tibia: P < 0.001; lateral femur condyle: P = 0.017). CONCLUSIONS: Gradient-echo sequences were most useful for the detection of chondrocalcinosis and presence of CaC was associated with higher prevalence of cartilage and meniscal damage. KEY POINTS: • Magnetic resonance imaging is useful for assessing burden of calcium-containing crystals (CaC). • Gradient-echo sequences are superior to fast spin echo sequences for CaC imaging. • Presence of CaC is associated with meniscus and cartilage degradation.

Elbow Imaging in Sport: Sports Imaging Series.

Elbow pain is a frequent presenting symptom in athletes, particularly athletes who throw. The elbow can be injured as a result of acute trauma, such as a direct blow or a fall onto an outstretched hand or from chronic microtrauma. In particular, valgus extension overload during the throwing motion can precipitate a cascade of chronic injuries that can be debilitating for both casual and high-performance athletes. Prompt imaging evaluation facilitates accurate diagnosis and appropriate targeted interventions.

Soft-tissue aneurysmal bone cyst with translocation t(17;17)(p13;q21) corresponding to COL1A1 and USP6 loci.

We present the case of a 46-year-old woman with no significant past medical history who developed left mid-thigh pain and fullness. Imaging demonstrated a mineralized soft-tissue mass, which increased in size during a year of monitoring, but retained a circumscribed appearance. The mass was located in the medial soft tissues of the thigh, separate from the bone on imaging studies, and this finding was confirmed during excision. The mass showed gross and microscopic features of an aneurysmal bone cyst. This diagnosis was supported by cytogenetic analysis revealing a t(17;17)(p13;q21) translocation corresponding to the USP6 and COL1A1 loci. Soft-tissue aneurysmal bone cyst is a rare entity, with fewer than 25 reports in the literature. Limited cytogenetic information about these tumors is available. To our knowledge, the USP6 and COL1A1 rearrangement has only previously been described in a pediatric soft-tissue aneurysmal bone cyst. We also discuss the differential diagnosis of ossifying soft-tissue lesions.

Lesser tuberosity avulsions in adolescents.

BACKGROUND: Subscapularis tendon avulsions of the lesser tuberosity are relatively rare and often missed acutely and their characteristic appearance is frequently not recognized or is misinterpreted for an osteochondroma or a neoplastic process. QUESTIONS/PURPOSES: This report reviews our experience with six adolescents who had subscapularis tendon avulsions of the lesser tuberosity. METHODS: Six male adolescents (12-15 years) presented with shoulder pain following history of trauma during amateur sport. Clinical notes including range of motion, strength tests, and pain assessment were reviewed along with imaging studies pre- and post treatment. Treatment consisted of either surgical or conservative measures. RESULTS: Two of the six patients had a large avulsion that simulated an exostosis of the proximal humerus that was misdiagnosed as an osteochondroma at two different outside institutions. All six cases were diagnosed with subscapularis tendon avulsion of the lesser tuberosity following clinical and imaging evaluation at our institution. Five of the patients underwent surgical repair and fixation of the tendon and the lesser tuberosity with suture anchors. One patient was treated conservatively. All patients had a good outcome with recovery of full shoulder strength and motion upon follow-up. CONCLUSION: Clinicians should have a high index of suspicion of lesser tuberosity avulsions in adolescents who present with loss of internal rotation and anterior shoulder pain following traumatic injuries. In addition, an osseous fragment or exostosis along the inferomedial humeral head should suggest a subscapularis tendon avulsion and also should not be confused with an osteochondroma or a neoplastic process.