Biomedical subjects

William C Foster

Publications and source records attributed to William C Foster.

6 recordsLinked to original sources

PubMed2006

A novel "four-rod technique" for lumbo-pelvic reconstruction: theory and technical considerations.

STUDY DESIGN: Surgical technique with case example. OBJECTIVE: To report on a novel technique that allows for the placement of 4 separate longitudinal rods across the lumbo-pelvic junction. SUMMARY OF BACKGROUND DATA: Despite advances in surgical techniques and instrumentation, lumbo-pelvic fixation remains a significant challenge. Fusions to the pelvis create long lever arms and generate high forces across the lumbosacral junction, resulting in high rates of screw pullout and implant fracture. In the attempt to achieve better bony fixation, techniques described include the use of bone cement, hydroxyapatite, and expandable screws. Although this process has decreased the incidence of screw pullout, it has not addressed the problem of rod fracture at the lumbo-pelvic junction. METHOD: There are 4 separate longitudinal rods placed across the lumbo-pelvic junction that couples proximal lumbar screw anchors to 4 separate pelvic fixation points. Proximal lumbar fixation anchors are based on alternating Roy-Camille "straight ahead" screws and Magerl "lateral to medial converging" pedicle screws. There are 4 distal pelvic fixation anchors used based on 1 pair of Galveston-like screws and 1 pair of proximal iliac wing screws. RESULTS: Early results of both ex vivo and in vivo reconstruction show that careful insertion of the lumbar and pelvic screws allows for divergent placement of the pedicle screw heads in a manner that 2 longitudinal rods can be placed per side, resulting in a total of 4 longitudinal rods across the lumbo-pelvic junction. Selection of cross-links in various combinations allows for additional axial and torsional stability, depending on the desired reconstruction. CONCLUSION: Longer follow-up is necessary, and biomechanical and finite element studies are needed to show long-term efficacy of this technique, however, early results indicate that such a construct is feasible. Furthermore, depending on the general medical condition of the patient, immediate postoperative weight bearing is possible and reasonable.

Adult↗

PubMed2005

Intramuscular angiomatous tumors associated with periosteal changes and pain.

This case report discusses two cases in which patients present with the uncommon triad of extremity pain, focal periosteal reaction on imaging studies, and intramuscular hemangioma on pathologic examination. Both patients presented in this article were older than those previously reported in the literature. Neither patient reported complete resolution of pain following excision, although there was marked improvement.

Female↗

PubMed2004

Tumefactive lipedema with pseudoxanthoma elasticum-like microscopic changes.

BACKGROUND: Lipedema is a condition characterized by diffuse, bilaterally symmetrical, painful swelling of the legs and buttocks. Microscopically, there are dermal and septal edema, adipocyte degeneration, and numerous mast cells, features held in common with lipedematous alopecia. CASE REPORT: We present the case of a 60-year-old woman with a long history of bilateral leg masses with microscopic features of lipedema. In addition, elastic-fiber changes typical of pseudoxanthoma elasticum (PXE) were discovered within the subcutaneous septa in three separate specimens obtained from an affected extremity. The patient did not have other clinical findings of PXE, although there was a history of both hypertension and congestive heart failure. CONCLUSION: This tumefactive presentation of lipedema has not been previously described. Regarding the elastic-tissue abnormalities, the patient could have either a subclinical form of PXE, perhaps predisposing to lipedema, or secondary elastic-tissue changes resulting from the massive edema. If the latter is the case, then this could represent an unusual manifestation of localized acquired cutaneous PXE (calcific elastosis).

Adipose Tissue↗

PubMed2003

Spectral Doppler sonography of musculoskeletal soft tissue masses.

OBJECTIVE: To determine whether resistive indices obtained from spectral Doppler waveforms can be used to distinguish benign from malignant musculoskeletal soft tissue masses. METHODS: A retrospective review of Doppler sonograms was performed for 52 patients with 53 soft tissue masses. All masses showed internal flow on color or power Doppler sonography, and spectral Doppler sonography yielded waveforms from which resistive indices were calculated. This information was analyzed along with the histologic diagnosis of each lesion with significance set at P > .05. RESULTS: There were 19 benign lesions and 34 malignancies. The resistive indices of the benign masses ranged from 0.44 to 1.0 (mean +/- SD, 0.72 +/- 0.42), whereas the malignant masses had resistive indices ranging from 0.28 to 1.0 (mean, 0.62 +/- 0.36). There was no statistically significant (P > .05) difference between the resistive indices of benign and malignant lesions. CONCLUSIONS: Resistive indices cannot be used to distinguish benign from malignant musculoskeletal soft tissue masses.

Adult↗

PubMed2002

Imaging of fatty tumors: distinction of lipoma and well-differentiated liposarcoma.

PURPOSE: To review the reliability of computed tomographic (CT) and magnetic resonance (MR) imaging features in distinguishing lipoma and well-differentiated liposarcoma. MATERIALS AND METHODS: CT (n= 29) and MR (n = 40) images and radiographs (n = 28) of 60 patients with histologically verified fatty tumors (35 lipomas and 25 well-differentiated liposarcomas) were retrospectively reviewed in 31 females and 29 males (mean age, 56 years; age range, 1-88 years). Images were assessed for adipose tissue content, and non-fatty component was classified (thin and/or thick septa and nodular and/or globular components) as absent, mild, moderate, or pronounced. Also assessed were signal intensity and tissue attenuation of the fatty components and non-adipose elements. RESULTS: Statistically significant imaging features favoring a diagnosis of liposarcoma included lesion larger than 10 cm (P <.001), presence of thick septa (P =.001), presence of globular and/or nodular non-adipose areas (P =.003) or masses (P =.001), and lesion less than 75% fat (P <.001). The most statistically significant radiologic predictors of malignancy were male sex, presence of thick septa, and associated non-adipose masses, which increased the likelihood of malignancy by 13-, nine-, and 32-fold, respectively. Both lipoma and liposarcoma demonstrated thin septa and regions of increased signal intensity on fluid-sensitive MR images. CONCLUSION: A significant number of lipomas will have prominent non-adipose areas and will demonstrate an imaging appearance traditionally ascribed to well-differentiated liposarcoma. Features that suggest malignancy include increased patient age, large lesion size, presence of thick septa, presence of nodular and/or globular or non-adipose mass-like areas, and decreased percentage of fat composition.

Adipose Tissue↗

PubMed2002

Intramuscular myxoma: characteristic MR imaging features.

OBJECTIVE: The purpose of our study was to identify the characteristic MR imaging features of intramuscular myxoma. MATERIALS AND MATERIALS: We retrospectively reviewed the MR imaging features of 20 patients with intramuscular myxoma. Clinical assessment included the age and sex of the patient and location of the tumor. Radiologic evaluation included the lesion size and shape, border definition, signal on T1- and T2-weighted or fluid-sensitive MR sequences, enhancement pattern, presence or absence of a fat rind, and presence or absence of increased signal in the adjacent muscle on T2-weighted or fluid-sensitive MR sequences. RESULTS: The mean age of patients presenting with intramuscular myxoma was 61 years (range, 15-85 years; median, 64 years). The mean lesion size was 6.9 cm (range, 3-17 cm; median, 6.3 cm). A peritumoral fat rind was present in 13 of the patients (65%) with myxoma, and an increased signal in the adjacent muscle on fluid-sensitive sequences was present in 11 patients (55%). Intramuscular myxomas were homogeneously low in signal intensity on T1-weighted MR sequences in 19 patients (95%), with all lesions showing a high signal intensity on T2-weighted or fluid-sensitive MR sequences. Twelve of the myxomas had well-defined borders, and eight had borders that were partially ill defined. Of the 11 lesions imaged after gadolinium administration, six (55%) showed intense heterogeneous enhancement. CONCLUSION: Findings of a mass that on MR images shows a perilesional fat rind, the signal intensity of fluid, and an increased signal in the adjacent muscle on T2-weighted or fluid-sensitive MR sequences are strongly suggestive of intramuscular myxoma. The degree of lesion enhancement varies but is most frequently intense and heterogeneous. Although the recognition of these features likely will not obviate biopsy of any individual lesion, it will allow more accurate prebiopsy diagnosis and preoperative planning.

Adolescent↗