Development of a novel method for surgical implant design optimization through noninvasive assessment of local bone properties

• Published in: Medical engineering & physics 2011-03, Vol.33 (2), p.256-262
• Main Authors: Schiuma, D, Brianza, S, Tami, A.E
• Format: Article
• Language: English
• Subjects: Algorithms; Biological and medical sciences; Biomechanical Phenomena; Bone Density - physiology; Bone implants; Bone mineral density; Bone Plates; Bone Screws; Cadaver; Cadavers; Computed tomography; Diseases of the osteoarticular system; Fracture Fixation, Internal - methods; High resolution CT; Humans; Humerus; Humerus - diagnostic imaging; Humerus - surgery; Implant optimization; Internal Fixators; Locking implants; Medical sciences; Minimally Invasive Surgical Procedures - methods; Osteoporosis; Osteoporosis. Osteomalacia. Paget disease; Prosthesis Design - instrumentation; Prosthesis Design - methods; Prosthesis Failure; Radiology; Screws’ direction; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Technology. Biomaterials. Equipments; Tomography, X-Ray Computed - methods
• ISSN: 1350-4533; 1873-4030
• DOI: 10.1016/j.medengphy.2010.09.024

Abstract A method was developed to improve the design of locking implants by finding the optimal paths for the anchoring elements, based on a high resolution pQCT assessment of local bone mineral density (BMD) distribution and bone micro-architecture (BMA). The method consists of three steps: (1) partial fixation of the implant to the bone and creation of a reference system, (2) implant removal and pQCT scan of the bone, and (3) determination of BMD and BMA of all implant-anchoring locations along the actual and alternative directions. Using a PHILOS plate, the method uncertainty was tested on an artificial humerus bone model. A cadaveric humerus was used to quantify how the uncertainty of the method affects the assessment of bone parameters. BMD and BMA were determined along four possible alternative screw paths as possible criteria for implant optimization. The method is biased by a 0.87 ± 0.12 mm systematic uncertainty and by a 0.44 ± 0.09 mm random uncertainty in locating the virtual screw position. This study shows that this method can be used to find alternative directions for the anchoring elements, which may possess better bone properties. This modification will thus produce an optimized implant design.