Biomedical subjects

John Rudan

Publications and source records attributed to John Rudan.

3 recordsLinked to original sources

PubMed2006

Fast assessment of acetabular coverage using stereoscopic volume rendering.

Previous CT-based methods of measuring acetabular coverage of the femoral head have either been labor-intensive or have required extensive preprocessing of the data prior to visualization. We propose a method of measuring acetabular coverage using stereoscopic digitally reconstructed radiographs that required very little labor or image preprocessing time. Taking a craniocaudal view of the pelvis, we measured both preoperative and postoperative CTs of 10 patients treated with transtrochanteric periacetabular osteotomy. Measurements were then made in both monocular and stereoscopic rendering modes. Our method is fast, easy, and provides an intuitive means of visualizing an orthopedic parameter that is important in the progression of early hip arthritis.

Canada↗

PubMed2004

Depot local anesthetic in polymethylmethacrylate bone cement: a preliminary study.

Acrylic bone cement has been used successfully as a slow-release depot for antibiotics after orthopaedic surgery. The feasibility of administering local anesthetics in this way was examined in this preliminary in vitro study. Discs weighing approximately 4 g were prepared from five brands of acrylic cement (40 g) containing as much as 2 g of anesthetic base. Elution of the anesthetics into saline was measured during 72 hours. Prilocaine eluted the fastest and bupivacaine the slowest, with lidocaine between them. The elution rates were greatest in the first hour, declining thereafter. Rates also depended on the brand of cement with the quickest elution from CMW3 and the slowest from Surgical Simplex P. Using cement as a depot, therapeutic levels of a drug should be achievable in vivo at a negligible risk of toxicity. Before in vivo trials it is necessary to optimize elution of drugs in relation to the cement (brand, microstructure, method of preparation) and the concentration of a drug in the cement above which the cements' mechanical and adhesive properties are compromised.

Anesthetics, Local↗

PubMed2002

The Kingston periacetabular osteotomy utilizing computer enhancement: a new technique.

OBJECTIVE: To develop a new periacetabular osteotomy technique that can be performed safely and reliably using computer-enhanced technology. MATERIALS AND METHODS: This technique uses a modified posterior approach with a trochanteric osteotomy. A 3D surface model is generated from CT data. The osteotomy is planned using custom software developed by our team. A dynamic reference body is fixed to the iliac crest and the pelvis is registered using an optically tracked probe (Optotrak, Northern Digital, Ontario, Canada). A tracked probe is used to mark the osteotomies in three dimensions. The posterior column is osteotomized between the sciatic notch and hip joint. The pubic ramus is osteotomized under fluoroscopic guidance. The acetabular fragment is rotated into a more appropriate position and fixed with pelvic reconstruction plates. Subjective and objective data are collected pre- and postoperatively. RESULTS: This procedure has been performed on eight patients. Average center-edge angle correction has been 17 degrees. The computer and optical guidance system has provided accurate information in seven of eight cases, and there have been no complications. CONCLUSIONS: This technique has enabled us to perform periacetabular osteotomies with safety and predictability. Using this computer-enhanced technique, periacetabular osteotomy may become a more common procedure in the practice of hip reconstruction surgeons.

Acetabulum↗