53 Case 27 Clinical Presentation 40-year-old man presents with acute shoulder pain and normal findings on radiographs.
54 RadCases Musculoskeletal Radiology Imaging Findings (,) Coronal images of the shoulder demonstrate complete discontinuity of the supraspinatus tendon (S). Retraction of the tendon creates a fluid-filled gap (asterisk). Differential Diagnosis Full-thickness rotator cuff tear: Magnetic resonance imaging (MRI) findings of cranial caudal tendon disruption extending to both the bursal and articular margins with tendon retraction creating a fluid-filled gap are consistent with a full-thickness tear. Pearls & Pitfalls On frontal radiographs, a humeral head abutting the undersurface of the acromion is diagnostic of a full-thickness rotator cuff tear. Smaller, chronic full-thickness rotator cuff tears may be difficult to diagnose on MRI in the absence of a joint effusion or without intra-articular contrast. Essential Facts Full-thickness tears of the rotator cuff, which are common in the athletic shoulder, result from impingement by the adjacent bony structures: the acromion, clavicle, humeral head, and glenoid fossa. The supraspinatus tendon is the most commonly involved structure. Initially, tendonosis develops in a hypovascular region termed the critical zone. If untreated, this condition may eventually lead to a tear. If untreated, this condition may eventually lead to a tear. The typical mechanism is tensile overuse related to overhead throwing. It is important to report the amount of tendon retraction and fatty atrophy, as this will affect management.
81 Case 41 Clinical Presentation 57-year-old woman presents with chronic knee pain.
82 RadCases Musculoskeletal Radiology Imaging Findings (, ) Radiographs of the knee show joint space narrowing, sclerosis, and extensive osteophyte formation ( arrows ) predominantly involving the medial femorotibial and patellofemoral compartments. No osteopenia is present. Differential Diagnosis Osteoarthrosis : the pattern of joint space narrowing with sclerosis and osteophyte formation is typical of osteoarthrosis. Neuropathic joint: destructive bony fragmentation, articular collapse, and subluxation are absent in this patient. Calcium phosphate dihydrate (CPPD) arthropathy: the absence of chondrocalcinosis, extensive subcortical cystic change, and disproportionate patellofemoral arthropathy dismisses this diagnosis. Pearls & Pitfalls weight-bearing radiograph will improve the detection of early joint space narrowing. Several causes of secondary cartilage damage may be associated with atypical osteoarthrosis. Essential Facts Osteoarthrosis results from articular cartilage damage caused by repetitive microtrauma that occurs throughout life. It tends to involve specific synovial joints during specific decades of a person s life and depends in part on the patient s body habitus and level of physical activity. In the knee joints, joint space narrowing is typically asymmetric and most commonly involves the medial femorotibial compartment and possibly the patellofemoral compartment. The presence of osteophytes, bone sclerosis, and subchondral cysts and the absence of inflammatory features such as erosions suggest this diagnosis. s the joint space narrows, the osteophytes become larger, bone sclerosis increases, and the formation of subchondral cysts, or geodes, may be seen.
195 Case 98 Clinical Presentation 32-year-old woman presents with chronic pain in the right hip.
196 RadCases Musculoskeletal Radiology Imaging Findings (,) Radiographs of the pelvis and right hip show a hypoplastic/dysplastic-appearing lateral acetabular roof containing sclerosis and cystic change (black arrows). This process allows superior subluxation of the femoral head, which is shortened and remodeled with an inferior osteophyte (white arrow). The left hip is normal. Differential Diagnosis Developmental hip dysplasia: Unilateral superior subluxation of the hip secondary to an underdeveloped acetabulum is representative of developmental hip dysplasia. Essential Facts Pearls & Pitfalls Developmental hip dysplasia is more common in the left hip and can be associated with labral tears along the anterosuperior quadrant of the acetabulum. Neuromuscular diseases may radiographically mimic this condition. In developmental hip dysplasia, the acetabulum partially covers the femoral head. In severe cases, superior subluxation of the hip is present. The center edge angle is used to quantify acetabular coverage of the femoral head. The angle is formed by two lines, each originating at the center of the femoral head; one line extends vertically, and the second extends to the lateral acetabulum. Coverage of the femoral head is considered adequate if the angle measures 25 degrees. The cause of this condition is controversial. It most likely develops in utero and is related to the fetal position. The process is typically unilateral. Patients present with anterior inguinal pain, painful clicking, transient locking, and instability of the hip. This condition is more common in women and may progress to osteoarthrosis and superior subluxation if untreated.