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Avulsion injuries are common among participants in organized sports, especially among adolescent participants. Imaging features of both acute and chronic avulsion injuries of the pelvis, knee, ankle and foot, shoulder, and elbow were evaluated to help distinguish these injuries from more serious disease processes such as neoplasm and infection. At radiography, acute injuries (ie, those resulting from extreme, unbalanced, often eccentric muscular contractions) may be associated with avulsed bone fragments, whereas subacute injuries have an aggressive appearance that may include areas of mixed lysis and sclerosis. Chronic injuries (ie, those resulting from repetitive microtrauma or overuse) or old inactive injuries may be associated with a protuberant mass of bone and may bear a striking resemblance to a neoplastic or infectious process. Although not usually required, computed tomography is helpful in the diagnosis if radiographic findings are equivocal or if the injury is not in the acute phase. MR imaging is best suited for the evaluation of injuries to muscles, tendons, and ligaments. Recognition of characteristic imaging features and familiarity with musculotendinous anatomy will aid in accurate diagnosis of avulsion injuries.

A modified technique was used for diagnostic aspiration of fluid from the hip in 185 patients who had previously undergone total hip arthroplasty. The aspiration needle was advanced past the lateral aspect of the shaft of the prosthesis and into the dependent portion of the joint. Fluid was successfully aspirated in 181 of 185 patients; thus the dry-tap rate was 2.2% (four of 185 patients). The modified technique was simple, could be performed quickly, and was effective for sampling joint fluid in patients with hip prostheses.

SCFE is the most common hip abnormality in adolescence. The subsequent development and severity of degenerative changes is related to the degree of slippage and to delay in diagnosis. Awareness of this diagnostic possibility in the population at greatest risk and knowledge of subtle and early radiographic findings will allow prompt diagnosis and treatment of SCFE. Follow-up radiographic examination should be used to evaluate for physeal fusion and any complications, including progression of the slip, hardware complications, chondrolysis, avascular necrosis, and secondary osteoarthritis.

Purpose: To evaluate magnetic resonance (MR) findings of surgically proved peroneal tendon tears., Materials and Methods: MR images, medical records, and surgical findings were retrospectively reviewed in the cases of 12 patients who underwent surgery because of suspected peroneal tendon tear (14 tendons). Sagittal and oblique axial T1-weighted spin-echo and T2-weighted fast spin-echo images were obtained in all patients., Results: At surgery, isolated peroneus longus tendon tears were seen in four patients, isolated peroneus brevis tendon tears in five, and both peroneus brevis and peroneus longus tendon tears in two. When correlated with surgical findings, findings at MR imaging were correct in 12 tendons. Findings were false-positive in two patients and false-negative in one, who underwent surgery anyway because unrelated abnormal MR findings were present. The most common MR finding was increased intra-substance signal intensity on T1- and T2-weighted images (11 tendons), in linear or rounded areas on oblique axial images (n = 11) and in linear areas along the longitudinal axis of the tendons on sagittal images (n = 7). Tendon distortion was noted in severe cases (five tendons). The most frequent surgical finding was a longitudinal tendon tear (split) (10 tendons)., Conclusion: MR imaging enabled detection of peroneus brevis and peroneus longus tendon tears.

Purpose: To elucidate the nature of a normally occurring cortical defect of the distal fibula., Materials and Methods: In patients with sprain and nonspecific ankle pain during a 2-year period, the authors reviewed ankle radiographs, computed tomographic (CT) scans, and magnetic resonance (MR) images. Cases were added from our file. Dried skeletons and cadavers were evaluated with radiography for the presence of this cortical defect., Results: Fifteen (1.8%) of 847 radiographs in 739 patients (male, 377; female, 362; age range, 15-84 years) showed a small cortical defect in the anterior aspect at the level of the distal tibiofibular joint. The age range of the subjects with the defect (male, four; female, 11) was 16-66 years. MR imaging in two patients showed a small low-signal-intensity area at the insertion site of the anterior tibiofibular ligament. Evaluation of 148 skeletons (75 subjects) revealed similar cortical defect in two cases (1.4%)., Conclusion: The cortical defect of the distal fibula, at the insertion site of the anterior tibiofibular ligament, has no clinical significance and should not be confused with neoplasm.

Purpose: To review experience with the imaging features of hamstring injuries., Materials and Methods: Imaging findings in 18 male and four female patients with clinically proved hamstring injuries were reviewed. The patients' ages ranged from 13 to 61 years (mean, 26 years). Radiography, conventional tomography, computed tomography (CT), and magnetic resonance (MR) imaging were performed., Results: Plain radiographs obtained less than 1 week after injury were normal or showed avulsion of an ischial apophysis. Plain radiographs and conventional tomograms obtained more than 1 week but less than 3 months after injury were confusing, because callus and osteolysis were present. CT helped identify a healing avulsion of an ischial apophysis. MR imaging was helpful no matter how long after the injury it was performed. It provided a means to evaluate muscle, tendon, and bone., Conclusion: Familiarity with the variable appearance of hamstring injuries over time and with different modalities facilitates accurate characterization.

To identify magnetic resonance (MR) imaging characteristics of normal patellar tendons and those affected by tendinitis, the authors evaluated MR images obtained in 10 healthy volunteers, in 50 patients who underwent MR imaging for evaluation of knee structures other than the patellar tendon, in 11 patients with patellar tendinitis, and in two athletes with patellar tendon injuries. Normal tendons had uniformly low signal intensity on T1-, T2-, and proton-density-weighted images and displayed distinct margins, and the anteroposterior (AP) diameter slightly increased proximally to distally. It was concluded that the AP diameter of a normal tendon, in its proximal portion, should not exceed 7 mm. In patellar tendinitis, the tendon showed increased signal intensity on T1-, T2-, and proton-density-weighted images and increased AP diameter proximally. The margins of affected tendons were indistinct, especially posterior to the thickened segment. In all groups studied, women had thicker proximal tendons than did men.

Scintigraphy was used after injection of technetium-99m methylene diphosphonate (MDP) and indium-111-labeled white blood cells (WBCs) to assess for the presence of osteomyelitis in 97 patients who had undergone prior surgical procedures. Thirty-four patients with abnormal In-111-labeled WBC patterns underwent restudy with Tc-99m albumin colloid (AC). Scintigraphic findings were considered positive for osteomyelitis whenever localization of In-111-labeled WBCs exceeded Tc-99m AC activity in extent or focal intensity (discordant pattern). Ten of 12 patients with culture-proved osteomyelitis had discordant patterns; two had false-negative (concordant) patterns. The cases of 20 of 22 patients without infection who were considered to have osteomyelitis on the basis of patterns of In-111-labeled WBCs and Tc-99m MDP were reclassified correctly on the basis of concordant patterns of In-111-labeled WBCs and Tc-99m AC. Radiocolloid images improved the overall scintigraphic specificity for osteomyelitis from 59% without bone marrow imaging to 92%; sensitivity decreased from 94% to 88%.

Radiographs and clinical records of 61 patients with calcaneal fractures were studied. Twenty-one patients had diabetes mellitus, and 40 were nondiabetic. All diabetic patients were insulin dependent for more than 5 years and had clinically evident peripheral neuropathy. Eighteen of the diabetic patients had no history of significant trauma. Fourteen had calcaneal insufficiency avulsion (CIA) fractures limited to the posterior third of the calcaneus. The fracture pattern in this group occurred in the same plane as a fatigue-type calcaneal fracture. Fragments of the posterior tuberosity were usually displaced 10-30 mm and were frequently rotated. The mean time from diagnosis of diabetes mellitus to CIA fracture was 20 years. Fractures in the nondiabetic group and in the three diabetic patients with a history of trauma did not resemble the CIA pattern. In the nondiabetic group, there were no insufficiency fractures; 39 fractures occurred with significant force (eg, motor vehicle accident or fall from height), and 33 had extension to subtalar or calcaneocuboid joints.

Occasionally, vertebral body lesions are encountered that are ill suited to the standard posterolateral approach to biopsy. The authors used a transpedicular approach to spine biopsy in six such cases. The authors suggest that this approach be used when the location of the lesion does not allow easy access by means of the posterolateral approach.

Fifteen patients with shoulder instability and nine asymptomatic volunteers were studied with magnetic resonance (MR) imaging. The shoulder joint was visualized by means of arthroscopy or surgery in all patients. Ten patients had abnormalities of the glenoid labrum. Two musculoskeletal radiologists interpreted the MR images of the patients and volunteers without knowledge of the clinical history or surgical results. The surgical and arthroscopic results were used as the standard of reference in symptomatic patients. Observer A achieved a sensitivity of 44.4% and a specificity of 66.7%; observer B had a sensitivity of 77.8% and a specificity of 66.7%. In addition to the poor sensitivities and specificities, there was substantial intra- and interobserver variability. Assuming that the shoulders of the asymptomatic volunteers were normal, the specificities were 100.0% and 88.9% for observers A and B respectively. In this small study, axial MR imaging was relatively insensitive and nonspecific in the evaluation of labral lesions. Further study will be necessary to determine the utility and limits of MR imaging in this regard.

Computed tomography (CT) and magnetic resonance (MR) imaging are extremely useful in the accurate diagnosis of anterior knee pain, a common complaint arising from numerous causes (including fracture, chondromalacia patellae, and alignment and tracking abnormalities). Plain CT is effective for evaluating intraosseous lesions of the knee. Although CT arthrography provides excellent visualization of the patellar articular cartilage, the technique is expensive and invasive. Cine CT is an excellent method for assessing patellofemoral tracking and alignment. Kinematic MR imaging can also perform this function. In addition, MR imaging can provide valuable information concerning the status of patellar cartilage. Although MR imaging can accurately show high-grade chondromalacia patellae, it is less accurate in the detection of low-grade disease. The authors believe that MR imaging and plain radiography offer radiologists the greatest latitude in making a specific diagnosis of the cause of anterior knee pain; however, CT is a useful alternative.

The authors prospectively studied 250 consecutive thoracic and lumbar spinal radiographic examinations and 56 dried skeletons to elucidate the peculiar target appearance in the pedicle of T-12 and occasionally T-11. Target pedicles were seen in 13 of the spines (23%) and in 85 of the 250 radiographic examinations (34%). Similar target pedicles were observed at T-11 in two radiographic examinations and in one spine. Anatomic correlation revealed that the inferior and lateral tubercles contribute to the ring shadow within the pedicle.

Epidural injection of steroid and local anesthesia can be used to treat low back pain. The injection is best performed with fluoroscopic control, with needle placement documented by means of a limited epidurogram. The technique was used in 116 patients; there were only three failures (2.5%) and one complication.

Arthrotomography was used to study the glenoid labrum in 8 patients with problems of shoulder instability. In 4 patients, an anterior lesion of the labrum was noted radiographically. The abnormality was confirmed at surgery in 3 of the 4. In 1 of the 3, anterior capsular detachment was also demonstrated radiographically and confirmed surgically. One patient had voluntary posterior subluxation: radiographically, the labrum was normal, and at surgery no abnormalities could be found. The technique, which is simple to perform is described and radiographic anatomy discussed.

Chondrolysis of the hip following slipped capital femoral epiphysis (SCFE) is reviewed and 3 cases are presented. The roentgenographic findings and early symptoms may serve to warn the radiologist and clinician of the onset of chondrolysis. Chondrolysis without SCFE is rare. Unfortunately the etiology is not well understood, and often the clinical course cannot be altered.

The effect of knowledge of localizing symptoms and signs in the detection of fractures was studied. Forty radiographs of the extremities were examined twice by seven radiologists; the sessions were separated by 4 months. In 26 cases, a subtle fracture was present; 14 cases were normal. In half of the cases at each session, the precise location of pain, tenderness, or swelling was provided. The observer was asked to determine if the case was normal or abnormal (provide the exact location of the fracture) and to indicate the degree of confidence in the diagnosis. Responses were converted to a numeric scale for analysis. Analysis of receiver operator characteristic parameters indicates that clues regarding location of trauma facilitate detection of fractures. The improvement is based largely on an increased true-positive rate without an increased false-positive rate, regardless of the decision criteria of the radiologist (overall willingness to "overread" or "underread"). This has direct clinical applicability and reinforces the plea of radiologists for precise clinical information.

Six patients with diabetes mellitus sustained neuropathic fractures. All had depressed or absent pain sensation in their legs. Four patients had unusual avulsion fractures in the posterior tubercle of the calcaneus. One had sustained six fractures within a period of six months. In 4 patients the fractures were followed by or associated with neuroarthropathy. The incidence and etiology of such fractures are discussed.

Patients with seronegative and patients with seropositive rheumatoid arthritis (RA) have clinical, genetic, and immunologic differences. This study was undertaken to determine whether the two populations differ radiologically. Seventeen patients with seronegative RA were closely matched with seropositive control subjects. Radiographs of the hands and wrists were studied blindly, and disease severity was quantified with use of a modification of the Beaver Creek grading sheet. The following distinguishing features were also evaluated: osteosclerosis, new bone formation, carpal predominance, ankylosis (fusion), symmetry, and classical erosions. Seropositive patients had more severe disease, with larger and more numerous erosions, while the seronegative group had more osteosclerosis, carpal predominance, fusion, and new bone formation. Symmetry was equal in both groups. Although there were definite quantitative and qualitative differences between the two populations, radiologists should be cautious in using these criteria because of the great deal of overlap between the two groups.

The sagittal diameter of the cervical spinal canal is traditionally evaluated when an expansile intraspinal lesion is suspected. Some workers have concluded that the normal sagittal diameter gradually decreases from C1 to C7 in some people, while in others it decreases from C1 to C3 and remains nearly constant from C4 to C7. The authors' study of 158 young individuals with no evidence of cervical cord lesions showed that gradual widening of the lower canal and even ballooning of the mid-canal are frequently seen in normal children 10 years old or younger, and occasionally in persons up to 18 years of age. The mechanism by which the canal attains a funnel-shaped appearance in adults is discussed.

Cranial settling occurs in about 5-8% of patients with rheumatoid arthritis, sometimes resulting in severe neurological problems or even death. It is caused by collapse of the supporting structures at the craniovertebral junction, mainly the lateral masses of C1. Twelve cases are presented; 2 patients with severe neurological problems were treated surgically.

We used arthrotomography to study the glenoid labrum in 114 patients. Sixty-nine of the patients had anatomic instability of the shoulder (including recurrent dislocation and subluxation of the shoulder), and 45 patients had functional instability of the shoulder (denoted by chronic pain, clicking of the joint, and the sensation that an unstable condition exists without the objective signs of it). Labral tears were revealed arthrotomographically in 86% of the patients with anatomic instability, while only 40% of the patients with functional instability had labral abnormalities, and these were primarily of minor severity. Fifty-six patients (44 of whom had anatomic instability; 12, functional instability) required surgery. The surgical findings were correlated with the arthrotomographic findings, and no false-positive results were revealed. However, arthrotomography demonstrated only part of the pathologic condition of two patients. These results confirm that there is a strong correlation between labral pathologic conditions and anatomic instability of the shoulder. Arthrotomographic studies have a great impact on the selection of therapy in cases of both anatomic and functional instability of the shoulder.

Three Down syndrome patients with posterior atlantooccipital (AO) subluxation are described. All are asymptomatic. The subluxation becomes manifest during active extension of the neck and reduces in flexion. Methods of assessing posterior AO subluxation are discussed. The abnormality is attributed to ligamentous laxity in patients with Down syndrome.