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The Lower Extremity – Supplement (Online Only)


THE THIGH

The Femoral Head and Hip Joint

FIGURE 7S-1, Apparent radiolucency of the femoral head in a 5-year-old boy (←) produced by superimposition of the normal irregularities of the acetabulum at this age ( ).

FIGURE 7S-2, A, Unusually large bilateral fovea capitis, which may be mistaken for osteochondritis dissecans. B, Tomogram of right hip.

FIGURE 7S-3, Large fovea capitis in a 26-year-old man.

FIGURE 7S-4, Simulated fracture or aseptic necrosis of the femoral head produced by the fovea capitis on plain film (A). B, No fracture is shown on the tomogram.

FIGURE 7S-5, The shadow of the posterior acetabular margin superimposed on the femoral head may simulate the density of vascular necrosis.

FIGURE 7S-6, Variation in the configuration of the femoral heads in a 5-year-old child.

FIGURE 7S-7, Unusual morphology of the femoral heads in a 26-year-old man, probably related to the fovea capitis.

FIGURE 7S-8, Degenerative spurring of the femoral neck that was mistaken for a subcapital fracture. A, Plain film. B, CT scan.

The Femoral Neck

FIGURE 7S-9, Simulated erosion of the right femoral neck in a 50-year-old man.

FIGURE 7S-10, A through C, Normal irregularities of the femoral necks, seen only in frog-leg projection (B, C).

FIGURE 7S-11, Asymmetric radiolucency of the right femoral neck (A) compared with the left (B), probably caused by asymmetry of position. Findings on MR imaging were normal.

FIGURE 7S-12, Examples of ringlike radiolucencies of the femoral necks with sclerotic borders. These common lesions are apparently of no clinical significance. There is evidence to suggest that they represent a subcortical pit formed by herniation of synovium through the cortical bone.

FIGURE 7S-13, A, B, Bilateral herniation pits in a 25-year-old man. C, Demonstration of pits on CT scan.

FIGURE 7S-14, Simulated periostitis of the femoral neck produced by the overlapping shadow of the greater trochanter.

The Trochanters

FIGURE 7S-15, Normal irregularities of ossification of the greater trochanter in a 12-year-old boy.

FIGURE 7S-16, Ossification variant of the greater trochanter simulating a fracture in a 15-year-old boy.

FIGURE 7S-17, Simulated cyst of the femoral neck produced in abduction by the shadow of the greater trochanter.

FIGURE 7S-18, “Tug” lesion below lesser trochanter, an enthesopathy.

The Shaft of the Femur

FIGURE 7S-19, The shadow of the fascia lata, which may simulate new bone formation.

FIGURE 7S-20, A, The shadow of the tensor fascia lata and iliotibial band on plain film. B, T2-weighted MR image.

FIGURE 7S-21, Muscle interleaved with fat may resemble a soft tissue mass, most commonly seen in women.

FIGURE 7S-22, Striking delineation of the muscles about the proximal femur in a young boy (A) and a 25-year-old athlete (B).

FIGURE 7S-23, Soft tissue companion shadow of the femur.

FIGURE 7S-24, Linear intramedullary densities in a 70-year-old woman. These are seen more frequently in elderly women without known disease and are apparently of no clinical significance.

The Distal End of the Femur

FIGURE 7S-25, Small “tug” lesion in an 11-year-old girl.

FIGURE 7S-26, Bilateral “tug” lesions of the femur, probably secondary to a pull of the vastus lateralis and vastus medialis muscles.

FIGURE 7S-27, Simulated lesions of the femur produced by the edge of the growth plates in tunnel views in a 10-year-old boy.

FIGURE 7S-28, Unusual variation of the medial distal femoral irregularity in a 10-year-old boy.

FIGURE 7S-29, Well-defined posterior femoral defect in a 12-year-old girl.

FIGURE 7S-30, A, B, Residual posterior distal femoral defects in an 18-year-old girl, which can be seen in the frontal projection (B) as radiolucencies that might be mistaken for evidence of disease.

FIGURE 7S-31, Residuum of posterior femoral defect in a 46-year-old man, with a thin rim of bone.

FIGURE 7S-32, A, Apparent lucent lesion in the medial femoral condyle. B, Repositioned film shows no abnormality, the change being caused by alteration in beam direction.

FIGURE 7S-33, Simulated cysts of the lateral femoral condyles, more exaggerated on the left.

FIGURE 7S-34, Normal irregular contours of the distal femoral epiphyses in a 4-year-old girl.

FIGURE 7S-35, Normal developmental irregularities of the condyles in a 12-year-old boy, which should not be mistaken for osteochondritis.

FIGURE 7S-36, Simulated osteochondritis dissecans in an 11-year-old boy. Note that the irregularities are not seen in the frontal projection (top left), are well demonstrated in the tunnel projection (top center), and are seen posteriorly in the lateral projection (top right). Gradient echo, T2*-weighted MR images show normal appearance of the articular cartilage and subchondrial bone ( bottom left and right ).

FIGURE 7S-37, Simulated osteochondritis dissecans in a 10-year-old boy. A, Plain film. B, T2-weighted MR image.

FIGURE 7S-38, Apparent ossification variant of the medial femoral condyle in a 13-year-old boy. A, AP projection shows faint radiolucency. B, Lateral projection shows no abnormality. C, Coronal gradient echo, T2*-weighted MR image shows signal alteration in area of interest. D, Sagittal gradient echo T2*-weighted image shows a subchondral defect, but was not related to the patient's symptoms.

FIGURE 7S-39, Accessory ossification center of the distal femoral epiphysis, seen in lateral projection.

FIGURE 7S-40, A, B, Bilateral similar excrescences on the articular surfaces of the lateral condyles simulating intraarticular osteophytes.

FIGURE 7S-41, A, Simulated lesion of the anterior surface of the femoral condyle produced by rotation. B, Normal appearance on repeat examination.

FIGURE 7S-42, Bilateral cyamellae in shallow popliteus grooves.

FIGURE 7S-43, Huge cyamella.

FIGURE 7S-44, Lateral meniscal ossicle.

FIGURE 7S-45, The meniscal ossicle in the posterior horn of the medial meniscus.

FIGURE 7S-46, Ossicle in Hoffa's fat pad.

FIGURE 7S-47, Some normal individuals show true asymmetry in the height of the medial and lateral compartments. Top left, A 48-year-old man. Standing films show asymptomatic symmetric narrowing of the medial compartments. Top right, Films of the same person 10 years later show no change in compartment height. Gradient echo, T2*-weighted coronal and sagittal MR images obtained at this time (bottom) show normal articular cartilage. These variations are probably related to known normal differences in thickness of articular cartilage in normal persons.

THE PATELLA

FIGURE 7S-48, Unusual patterns of ossification of the patella in a 6-year-old boy.

FIGURE 7S-49, Left, Accessory ossification center in an 8-year-old boy diagnosed as a fracture. Right, Film made 1 month later, after no treatment, shows progressive closure of the secondary center.

FIGURE 7S-50, Variation in development of the patella in an 11-year-old child with cerebral palsy, possibly the result of traction by the quadriceps and the patellar tendons. These centers often close, leaving an elongated patella.

FIGURE 7S-51, Accessory patellar ossification center, seen in tangential projection in a 2-year-old boy.

FIGURE 7S-52, Segmented patella showing poor definition of septa in the oblique projection (right).

FIGURE 7S-53, Bilateral dorsal patellar defects in a 13-year-old girl.

FIGURE 7S-54, Dorsal defects in an elderly man. These defects are seen more commonly in young people but occasionally persist into later life. Top left, Frontal view. Top right, Lateral view. Bottom, Tangential views.

FIGURE 7S-55, Simulated fracture of the upper pole of the patella, produced by a small flangelike projection.

FIGURE 7S-56, Unusual caudal extensions of the patella in an adult.

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