Soft-tissue chondroma.

Soft-tissue chondromas are rare and benign soft-tissue tumors. Over 95% occur in the hands and feet. They are seen in both sexes equally and mainly occur in patients aged 30-60 years. If excised fully, they do not reoccur, and no cases in the literature have reported malignant transformations.

Radiologic case study. Spontaneous osteonecrosis of the knee reclassified as insufficiency fracture.

Three questions need to be answered. First, does spontaneous osteonecrosis of the knee in fact exist? The answer is "probably," but much more rarely than initially believed. In five of the authors' most recent MRIs in patients with clinically diagnosed or radiographically suggested spontaneous osteonecrosis of the knee, only one patient's images fulfilled the criteria for spontaneous osteonecrosis (Figure 3). Three of the five had subchondral changes of either insufficiency fractures or true fractures, while one patient had equivocal findings. Second, will the actual diagnosis influence the treatment? The answer appears to be "no" because early subchondral fractures and early spontaneous osteonecrosis of the knee are treated conservatively and only the later changes of subchondral surface collapse are treated more aggressively with joint replacement. Third, is there any method of halting the progression of early subchondral changes before they progress into collapse, flattening, and loose-body formation? The answer appears to be "maybe" as non-weight-bearing conservative therapy has not consistently prevented progression of the disease. Whether new arthroscopic techniques can provide the necessary intervention to halt osteoarthritic sequelae remains unanswered. Thus, it appears most patients with what has been called spontaneous osteonecrosis of the knee actually have subchondral insufficiency fractures. The histologic findings of avascular areas in biopsy specimens appear to be a secondary phenomenon and not the primary cause. If diagnosed early enough, conservative therapy may lead to healing without subsequent collapse and fragmentation of the subchondral bone.

Radiologic case study. Secondary hyperparathyroidism, osteomalacia with a pseudofracture, and amyloid deposition.

The advancement of medical management of chronic renal failure has helped eliminate secondary hyperparathyroidism and osteomalacia. However, if a patient is recalcitrant, florid forms of both conditions can develop. Secondary amyloidosis is poorly understood but occurs in patients who are on long-term dialysis. As the survival rates for patients on long-term dialysis improve, it will be seen more frequently.

Radiologic case study. Traumatic dislocation of the knee.

Imaging in knee dislocation requires multiple modalities and a comprehensive assessment of ligaments, cartilage, bone, nerve, and vascular anatomy. Magnetic resonance imaging is essential in the work-up of these patients and MRA is a promising modality for detecting vascular injury.

The use of forced flexion/extension views in the obtunded trauma patient.

OBJECTIVE: To determine whether forced flexion/extension (F/E) films for "clearing" the cervical spine in unconscious or semiconscious patients are useful or actually dangerous. DESIGN AND PATIENTS: Of 810 patients admitted for blunt trauma over a 5-year period, 479 patients whose films and charts were available received passive F/E film views of the cervical spine. Of these, 447 were reviewed retrospectively in masked fashion for any exacerbation of neurological changes subsequent to the procedure and with respect to the final neurological status at discharge. RESULTS: Twenty-nine patients (6%) had various abnormalities including fractures and ligamentous injuries seen on the initial films. Following forced F/E films no change was made in the diagnosis of 23 patients. Of the remaining six patients, two required no treatment, two only required the use of a collar but two did have surgical intervention, this decision being based on the findings seen in the initial films. However, 285 films (59%) were judged inadequate due either to inadequate F/E (150 patients, 31%) or poor visualization (194 patients, 40%). There were three false positives all subsequently cleared by other studies and there were no false negatives. From the chart review, there were no complications or deaths attributable to the procedure. CONCLUSION: Although we were unable to find any complication or deaths directly attributable to the procedure, the clinicians abandoned passive F/E views in obtunded patients on the grounds of expense. Our present method of "clearing" a cervical spine in an obtunded patient is a cross-table lateral radiograph followed by a high-resolution thin-slice CT scan with sagittal and coronal reconstruction. We are against the use of routine MRI studies and of a forced F/E view in these patients.

Possible complications of anterior perforation of the vertebral body using cervical pedicle screws.

No previous studies have analyzed the possible complications of anterior perforation of the cervical vertebral body with pedicle screws. The objective of this study was to identify the possible implications of an anterior vertebral body perforation. Ten consecutive Euro-American cadavers (C2-C7) were used. The male-to-female ratio was 3:7. The average specimen age was 79.6 years (range: 65-97 years), and average height was 159 cm (range: 155-175 cm). Axial computed tomography scans through the isthmus of pedicles were taken. Five millimeter and 10 mm margins anterior to the vertebral bodies were defined. Within 5 mm anterior to the anterior cortex of the vertebral body, we found mostly muscles (at C2: m. longus colli and pharyngeal constrictors; at C3 and C4: m. scalenus medius, longus colli, pharyngopalatinus and pharyngeal constrictors; at C5 and C6: m. longus colli and longus capitis; and at C7: m. longus colli), except at C3, C4, and C7, where the pharynx and esophagus were within the margin. Between 6 and 10 mm, we found mostly hollow organs (at C2: pharynx and small veins; at C3 and C4: the same muscles as within the 5 mm margin, with addition of the pharynx and some small veins; at C5 and C6: pharynx, pharyngeal constrictors and the thyroid cartilage; and at C7: the esophagus). Except C2, there is no safe zone anterior to the cervical vertebral bodies in the cervical spine, which would allow bicortical purchase of pedicle screws without being close to important surrounding structures.