Orthopedic interface

Spalazzi JP, Doty SB, Moffat KL, Levine WN and Lu HH. Development of controlled matrix heterogeneity on a triphasic scaffold for orthopedic interface tissue engineering. Tissue Eng. 2006 12 3497-3508. 

Moffat, K. L., Wang, 1. N., Rodeo, S. A., and Lu, H. H. 2009b. Orthopedic interface tissue engineering for the biological fixation of soft tissue grafts. Clin. Sports Med. 28 157-176. 

Adapted from Dickerson, D.A., Misk, T.N., Sickle, D.C.V., Brenr, G.J., Nanma, E.A., 2013. In vitro and in vivo evalnation of orthopedic interface repair using a tissue scaffold with a continuous hard tissue-soft tissue transition. Journal of Orthopaedic Surgery and Research 8, 18. http //dx.doi.org/10.1186/1749-799X-8-18. 

Other than generating artificial grafts for orthopedic interface repair, hydroxyapatite has been incorporated to the screws as an osteoconductive component used for fixation... 

Biomaterial scientists and engineers are currently investigating novel formulations and modifications of existing materials that elicit specific, timely, and desirable responses from surrounding cells and tissues to support the osseointegration of the next generation of orthopedic and dental biomaterials (Ratner, 1992). Enhanced deposition of mineralized matrix at the bone-implant interface provides crucial mechanical stability to implants. Proactive orthopedic and dental biomaterials could consist of novel formulations that selectively enhance osteoblast function (such as adhesion, proliferation and formation of calcium-containing mineral) while, at the same time, minimize other cell (such as fibroblast) functions that may decrease implant efficacy (e.g., fibroblast participation in callus formation and fibrous encapsulation of implants in vivo). 

In-Vivo Percutaneous Implant Experiment. The principle of percutaneous attachment has extensive application in many biomedical areas, including the attachment of dental and orthopedic prostheses directly to skeletal structures, external attachment for cardiac pacer leads, neuromuscular electrodes, energy transmission to artificial heart and for hemodialysis. Several attempts to solve the problem of fixation and stabilization of percutaneous implants(19) have been made. Failures were also attributed to the inability of the soft tissue interface to form an anatomic seal and a barrier to bacteria. In the current studies, the effect of pore size on soft tissue ingrowth and attachment to porous polyurethane (PU) surface and the effect of the flange to stem ratio and biomechanical compliance on the fixation and stabilization of the percutaneous devices have been investigated.(20)... 

While much recent work has been described to develop polyacetals for drug delivery applications, and historically they have been used as implant materials, more recently, they have been examined as potential scaffold materials in tissue engineering. Implants of Delrin (polyoxymethylene) to repair heart valves were examined, but there was too much swelling in vivo [127]. However, this polyacetal has been used as an orthopedic implant [128] and as an orthopedic implant-coating material [129,130] to interface with bone tissue as this polyacetal has a similar modulus to bone. Ultrasound is used in the diagnosis of osteoporosis and porous polyacetal blocks were found useful to gain insights into bone porosity and ultrasonic properties [131]. 

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