Aluminum-induced neo-osteogenesis: a generalized process affecting trabecular networking in the axial skeleton.

To determine if aluminum-induced neo-osteogenesis occurs in the axial skeleton, we compared spinal bone density and vertebral histology of beagles treated with aluminum for 8 and 16 weeks to that of untreated normals. Administration of aluminum (1.25 mg/kg) did not alter serum calcium, phosphorus, or creatinine but did result in a significant elevation of vertebral bone density, measured by quantitative computed tomography, after both 8 (286.7 +/- 12.4 mg/ml) and 16 (361.7 +/- 46.5 mg/ml) weeks of treatment compared with controls (212.2 +/- 4.5 mg/ml). In accord with the increased bone density, biopsies from the spine displayed evidence of neo-osteogenesis, including the presence of woven bone, both mineralized and unmineralized, within the marrow space. The genesis of such woven bone units resulted after 16 weeks in a significant increase in trabecular bone volume, woven and lamellar (51.2 +/- 4.4 versus 32.4 +/- 1.2%; p less than 0.05), woven bone volume (9.1 +/- 3.6 versus 0 +/- 0%; p less than 0.05), and trabecular number (4.5 +/- 0.3 versus 3.5 +/- 0.2 per mm; p less than 0.05). In addition, scanning electron microscopic evaluation of the bone biopsies confirmed the existence of new trabecular plates that provided interconnections between existent units. These observations illustrate that aluminum-induced neo-osteogenesis positively influences trabecular networking in the axial skeleton. Such enhancement of bone histogenesis contrasts with the effects of other pharmacologic agents that solely alter the thickness of existing trabecular plates or rods within the vertebral spongiosa.

Long-term marginal zinc deprivation in rhesus monkeys. IV. Effects on skeletal growth and mineralization.

Skeletal maturation was evaluated from ages 1 to 3 y in rhesus monkeys that had been subjected to a diet marginally deficient in zinc (4 micrograms/g Zn) from conception through age 3 y. Skeletal development was assessed at 18, 24, 30, and 36 mo of age and compared with that of controls fed ad libitum. Skeletal maturation was determined by the presence of epiphyseal ossification centers. To evaluate endochondral bone mineralization the appearance of the zone of provisional calcification on the metaphyseal side of the growth plate and the width of the growth plate were observed. Marginal Zn deprivation was associated with delayed skeletal maturation in monkeys up to age 3 y. Defective mineralization of bone was evident in these monkeys up to age 6 mo. Between ages 6 mo and 3 y bone mineralization increased in some of the marginal-Zn monkeys to values that were only slightly below those for control monkeys.

Studies of marginal zinc deprivation in rhesus monkeys. V. Fetal and infant skeletal effects.

Skeletal maturation was evaluated in newborn and infant rhesus monkeys that had been subjected to a marginally zinc-deficient diet (4 ppm zinc) from conception through 12 months of postnatal life. Serial radiographic assessment of skeletal development was performed and compared to both ad libitum and pair-fed controls. Radiographs were obtained at birth and at 1, 3, 9, and 12 months of age. In each age group a maturation indicator was selected to identify individuals with abnormal skeletal maturation defined on the basis of presence of epiphyseal ossification centers. Animals were compared only within a given sex group. Additionally, to evaluate endochondral bone mineralization, the appearance of the zone of provisional calcification on the metaphyseal side of the growth plate and the width of the growth plate were assessed. A marginal level of zinc deprivation during gestation and during the 1st yr of life was found to be associated with significantly delayed skeletal maturation and defective mineralization. This abnormality of bone mineralization has many features similar to human rachitic syndromes and suggests that zinc plays an important role in endochondral bone formation.

The "numb cheek-limp lower lid" syndrome.

A patient developed isolated numbness, 1st confined to the lateral nose and upper lip, but later involving the cheek, lower lip, upper gingiva, and the palate. This numbness was later associated with paresis of the muscles of the upper lip and angle of the mouth and with ipsilateral lower lid droop (the "numb cheek-limp lower lid" syndrome). Squamous cell carcinoma was discovered infiltrating the infraorbital nerve and distal branches of the facial nerve. Cheek numbness associated with lower eyelid or upper lip weakness may herald a neoplasm affecting the infraorbital nerve and distal facial nerve branches.

Detection of migratory silicone pseudotumor with use of magnetic resonance imaging.

A patient with silicone gel breast implants, who experienced capsular contracture of the left breast that was treated by closed capsulotomy, sought medical attention because of numbness and pain in the left medial forearm and hand. Inflammatory masses subsequently developed in the left anterior axillary and antecubital regions. Magnetic resonance imaging revealed silicone pseudotumors, and mammography confirmed implant rupture and gel extrusion along fascial planes into the axillary region.

Computed tomography of hamstring muscle strains.

Acute hamstring muscle strains occurring in ten college athletes were evaluated using computed tomography to identify the location and characteristics of these common injuries. Acute muscle strains appeared as areas of hypodensity within the muscle 1-2 d following injury. This suggests that inflammation and edema are the major component of injury, not bleeding as commonly assumed. Injuries were seen most commonly in the proximal and lateral portions of the hamstring muscle group, particularly in the biceps femoris.

Outcome analysis of noninstrumented anterior cervical discectomy and interbody fusion in 348 patients.

STUDY DESIGN: Twenty-one outcome and outcome-relevant variables (fusion and patient satisfaction) were evaluated in a subset of 348 of 514 patients operated on by one surgeon during a 22-year period, using Cloward's anterior cervical discectomy and dowel interbody fusion. Minimum patient follow-up was 2 years; average length of follow-up was 5.2 years. This retrospective analysis is accompanied by a comprehensive review of the literature (1975-1996) of noninstrumented anterior cervical fusions, excluding fibular grafts alone in the interbody space. OBJECTIVES: To provide data on outcome (with regard to patient satisfaction and radiologically supported fusion) and risks of noninstrumented anterior cervical discectomy and fusion for intractable cervical nerve root and spinal cord compression symptoms at single or multiple levels, using the results from a single surgeon. METHODS: Three experienced spine radiologists determined fusion rates in one to five levels in 348 patients on the basis of the results of plain film analysis. Patient self-assessment was used to determine degree of patient satisfaction and other related variables. From a comprehensive review of the literature, 43 clinical reports meeting requirements for comparison of findings with those in the current study were selected from more than 1600 reports. RESULTS: The mean fusion rate for 348 patients in the current study ranged from 75% (multilevel) to 88% (one level; n = 202). The overall fusion rate was 83%. The persistent complication rate was 0.1%, and patient self-assessments showed that 78% were satisfied with the outcome and that 83% returned to work. The overall fusion rate for 2037 patients evaluated in the comprehensive literature review is 92%. CONCLUSIONS: Results of this study indicate that better outcome in noninstrumented anterior cervical discectomy and fusion is associated with solid fusion, fewer fused levels, nonsmoking patients, higher education levels, and absence of secondary economic gain. There was no correlation between fusion status and bone graft source or use of cervical collar.

Characteristic CT manifestations of uncommon spinal disorders.

This article identifies many disorders seen on CT scans of the spine that should be recognized to avoid submitting the patient to additional diagnostic tests or even surgery. These disorders are not easily categorized, however, and could best be described as normal variants and pitfalls in CT diagnosis of the spine.

The shoulder impingement syndrome: prevalence of radiographic findings and correlation with response to therapy.

The shoulder impingement syndrome is believed to be caused by compression of the rotator cuff tendons and subacromial bursa between the humeral head and structures that make up the coracoacromial arch. Plain film findings were tabulated for 36 patients, 22-81 years old, who had signs and symptoms of an acute impingement syndrome. The most common radiographic abnormalities were subacromial bony proliferation in 68%, degenerative changes in the greater tuberosity of the humerus in 66%, and degenerative joint disease in the acromioclavicular joint in 66%. There was evidence of calcium deposition in the rotator cuff in 37%, inferiorly oriented acromioclavicular osteophytes in 32%, and degenerative changes of the lesser humeral tuberosity in 29%. The acromiohumeral space was narrowed in only 21%. The radiographic findings were scored blindly and compared to the treatment outcome of 6 weeks of medical therapy. There was no statistically significant correlation between any of the radiographic findings and the response to medical therapy. The results suggest that radiographic findings are extremely common in patients with the acute impingement syndrome, but that they are not useful as prognostic indicators of the short-term response to medical treatment.

CT attenuation numbers in the lumbar spine and their utility in diagnosing disc disease.

Normal CT attenuation values for various structures in the lumbar spine were obtained on several CT scanners. The wide range of normal makes using absolute CT numbers unreliable. The utility and pitfalls of using CT attenuation numbers in the lumbar spine are discussed and several examples are illustrated. CT numbers used as absolute values can be misleading, whereas, when used as relative values for comparison with other structures, they can be quite valuable.

Synovial chondromatosis of the temporomandibular joint diagnosed by magnetic resonance imaging: report of a case.

A case of synovial chondromatosis of the temporomandibular joint with extracapsular extension is described. Temporomandibular joint magnetic resonance imaging proved invaluable in establishing a definitive diagnosis.

CT of the lumbar spine: normal variants and pitfalls.

Benign variants in the appearance of the lumbar spine on CT may be confused with significant lesions. Here such benign processes and their distinguishing features are illustrated.

Diagnosis by computed tomography of temporomandibular joint meniscus displacement.

CT may be a practical alternative to arthrography for diagnosing displacement of the meniscus in the TMJ. In a study of 75 patients, 69 were diagnosed by CT to have meniscal displacement. Thirty-four diagnoses were subsequently confirmed by surgery or arthrography. Disadvantages of CT are cost (almost twice as much as an arthrogram), inability to diagnose perforations, and inability to judge meniscus dynamics, which can be done by fluoroscopy. Advantages are patient comfort, safety, and decreased total radiation dose. Continued research and clinical correlation will be needed to determine the role of CT in the diagnosis of meniscus displacement of the TMJ. However, initial results are promising, and CT may quickly replace arthrography as the diagnostic procedure of choice.

Osteoid osteoma: radionuclide diagnosis.

The double-density sign, seen on radionuclide bone scans, is described for diagnosing osteoid osteomas and for localizing the nidus. Its use in differentiating the nidus of an osteoid osteoma from osteomyelitis is also described. The utility of computed tomography in localization of the nidus is also illustrated. The double-density sign was helpful in diagnosing seven cases of surgically confirmed osteoid osteoma.

Pigmented villonodular synovitis: a report of MR imaging in two cases.

Although magnetic resonance (MR) imaging has been used to evaluate many musculoskeletal lesions, the MR appearance of pigmented villonodular synovitis (PVNS) has not been described in detail. The authors describe two cases of PVNS in the knee imaged with both computed tomography and MR. In both cases parts of each lesion had very low signal intensity on both short repetition time (TR)/echo time (TE) sequences and long TR/TE sequences. Other portions of both lesions had intermediate signal intensity (equal to or higher than that of muscle but lower than that of fat) on short TR/TE sequences and increasing signal intensity on longer TR/TE images. In one case, the lesion also had a cystic component that showed MR changes typical of complex fluid. The authors propose that the MR signal characteristics demonstrated in these cases may be explained by the unique tissue components of the lesion, particularly hemosiderin and fat.

Correlation of magnetic resonance imaging and surgical findings in patients with meniscal perforation.

Advancement of surgical techniques has made it necessary to accurately diagnose internal derangements. Arthrography and computerized tomography have been used to diagnose the majority of temporomandibular joint disorders; however, these methods have had their disadvantages. Magnetic resonance imaging utilizing surface coils has greatly improved the ability to diagnose meniscus abnormalities without using interarticular injections or ionizing radiation. Ninety-two patients (184 joints) were evaluated by means of magnetic resonance imaging (MRI). Thirty-one patients (39 joints) were diagnosed as having meniscus perforation. Retrospective reviews of 15 patients (20 joints) with a perforated meniscus diagnosed by magnetic resonance imaging preoperatively demonstrated a 65% correlation between the radiographic diagnosis and the surgical findings.