Biomedical subjects

John L Masonis

Publications and source records attributed to John L Masonis.

4 recordsLinked to original sources

PubMed2004

Zirconia femoral head fractures: a clinical and retrieval analysis.

Zirconia femoral heads provide increased fracture strength, but 343 zirconia head failures have been documented since 2000. Retrieval analysis of 6 fractured heads, 4 suspect heads, 4 control zirconia heads, and 2 failed alumina heads was performed. Zirconia failures have been isolated to heads sintered in a "tunnel" furnace introduced in 1998. The monoclinic composition at the taper surface of fractured and nonfractured heads was significantly elevated (21% to 68%) compared to that of control zirconia heads (less than 5%). Electron microscopy identified circular fracture footprints unique to the zirconia heads produced in the tunnel furnace. Cobalt chrome heads were used in the urgent revision setting due to Morse taper damage. Partial capsulectomy was performed in an effort to reduce future third body wear. Monoclinic phase transformation following implantation remains a potential mechanism of ceramic head failure. We recommend that patients with recalled zirconia heads be advised of a potential fracture risk.

Adult↗

PubMed2003

Spinal osteochondroma presenting as atypical spinal curvature: a case report.

STUDY DESIGN: The case of an 8-year-old girl with hereditary multiple exostosis presenting with atypical spinal curvature is reported. OBJECTIVE: To describe a case of spinal curvature caused by an osteochondroma, illustrating the need for careful evaluation of patients with hereditary multiple exostosis presenting with "scoliosis." SUMMARY OF BACKGROUND DATA: Osteochondromas have been known to arise in the spinal canal and to present with symptoms of neural compression. Spinal curvature is a rare presenting sign of osteochondromas. METHODS: The patient's medical and radiographic history is reviewed as well as the medical literature. RESULTS: An 8-year-old girl with hereditary multiple exostosis was referred for possible thoracotomy and anterior decompression of a T4 osteochondroma thought to be causing an atypical "scoliosis." Further examination, review of the radiographs, and computed tomography scan showed a large L4 osteochondroma encroaching on the neural elements. The patient's neurologic symptoms and spinal curvature resolved in the 2 years after surgical excision of the lumbar osteochondroma. CONCLUSIONS: Patients with hereditary multiple exostosis and spinal curvature require further diagnostic evaluation to ensure that an osteochondroma in the spinal canal is not the cause of that curvature.

Child↗

PubMed2003

Subtrochanteric shortening and derotational osteotomy in primary total hip arthroplasty for patients with severe hip dysplasia: 5-year follow-up.

Twenty-one primary hip arthroplasties were performed in Crowe grade 3 or 4 hip dysplasia using a subtrochanteric shortening osteotomy. Average patient age was 48.2 years. Average follow-up was 5.8 years (minimum, 2 years). Femoral fixation was cemented in 10 hips and uncemented in 11 hips. All acetabular components were uncemented, with 33% requiring structural autograft. Ninety-one percent of femoral osteotomies healed without complication. Two osteotomy nonunions required revision. Two acetabular revisions were performed for malposition and polyethylene failure. Three patients experienced postoperative dislocation. One cemented femoral component was revised for loosening. However, no neurologic deficiencies were identified. Harris hip score improved from 32.5 to 73.6. Limp improved in 60% of patients and dependence on assistive walking device improved in 40% of patients. Subtrochanteric shortening osteotomy is a safe and predictable method of restoring the anatomic hip center in high developmental hip dislocation. However, the complication rate in these patients is higher than primary hip arthroplasty for osteoarthritis.

Adult↗

PubMed2002

Surgical approach, abductor function, and total hip arthroplasty dislocation.

Dislocation is a leading early complication of total hip arthroplasty. The effect of surgical approach on instability and abductor function is a controversial topic. A comprehensive literature review was done to evaluate the correlation of surgical approach and primary total hip arthroplasty dislocation. Two hundred sixty clinical studies were identified between 1970 and 2001. Four prospective studies were identified but individually they contained insufficient power or control groups to reach statistical significance regarding surgical approach and dislocation. Fourteen studies involving 13,203 primary total hip arthroplasties met the inclusion criteria based on variables previously shown to affect stability. These studies were evaluated with respect to surgical approach and dislocation. The combined dislocation rate for these studies was 1.27% for the transtrochanteric approach, 3.23% for the posterior approach (3.95% without posterior repair and 2.03% with posterior repair), 2.18% for the anterolateral approach, and 0.55% for the direct lateral approach. Eight studies involving 2455 primary total hip arthroplasties evaluated postoperative limp. The incidence of postoperative limp was 4% to 20% for patients who had the lateral approach and 0% to 16% for patients who had the posterior approach. The quality of the literature regarding surgical approach, dislocation rates, and abductor function is limited. Larger controlled prospective studies are needed to investigate the potential benefits of the posterior approach in lieu of a dislocation rate six times higher than the direct lateral approach for primary total hip arthroplasty.

Arthroplasty, Replacement, Hip↗