Wednesday, May 5, 2010

Bone Graft substitutes updates

Aesculap Implant Systems launches new demineralized bone matrix 
Aesculap Implant Systems, LLC announced in a press release the recent launch of its ProSpace DBM-D.
ProSpace DBM-D is a demineralized bone matrix available in two forms, “flowable” paste or “moldable” putty, the company stated The moldable putty contains cortical-cancellous chips which creates a 3-D scaffold for optimized osteoconduction.
ProSpace DBM-D pastes and putties serve as bone void filler in many surgical applications. Unique features associated to this product allow for room temperature storage and re-hydration with a choice of fluids, including patient’s own blood, sterile water or saline.
It is manufactured for Aesculap by RTI Biologics, Inc. 

Using rh-BMP-2 may not guarantee fusion in all cases
Shen HX.Spine. 35(7):747-753. April 2010.
A large consecutive case series of multilevel fusions treated with recombinant human bone morphogenetic-2 yielded a 10.2% pseudarthrosis rate at 6 months.
“Since the risk of pseudarthrosis increases with the number of fusion levels, a long fusion lever arm may biomechanically overwhelm the biologic advantage of rhBMP-2,” the authors wrote in their abstract. “While rhBMP-2 is known to enhance fusion rates, it does not guarantee fusion in all situations.”
Pseudarthrosis rates after anterior cervical fusion range from 0% to 20% for single-level fusions and up to 50% for multilevel fusions, according to the abstract. Some researchers have theorized that rhBMP-2 may decrease the pseudarthrosis rate.
Growing array of bone graft substitutes now available in the United States
Knowing the properties of available bone graft substitutes helps orthopedic surgeons choose appropriate products.
Musculoskeletal allografts are used every day in orthopedic surgery. Last year, more than 1.3 million musculoskeletal allografts were distributed in the United States, according to the American Academy of Orthopaedic Surgeons.
Although use of these biologic materials is common, the field is rapidly changing and orthopedic surgeons need to stay up-to-date on the issues surrounding musculoskeletal allograft tissue.
Among the issues: safety, efficacy, sterilization methods, donor and allograft availability and recall status.
To increase allograft tissue awareness in the orthopedic community, the American Academy of Orthopaedic Surgeons (AAOS) regularly communicates information on the subject to its members via courses and at its Web site (aaos.org).
Earlier this year, the AAOS Orthopaedic Device Forum, Committee on Patient Safety and Committee on Biological Implants Tissue Work Group prepared materials on bone graft substitutes and musculoskeletal allografts for distribution at the AAOS 73rd Annual Meeting.
Among those educational materials was a chart summarizing information about current bone graft substitutes, such as their composition, mechanisms of action and FDA status. With permission from the AAOS, Orthopedics Today is publishing the chart of commercially available bone graft substitutes now available in the United States.
The staff of Orthopaedic Research Laboratories and Lutheran Hospital, a Cleveland Clinic facility, created the chart, contacted all the companies listed and compiled the information about their products.
For more information:
  • Greenwald AS, Boden SD, Goldberg VM, et al. Bone graft subsitutes: facts, fictions and applications. SE#72. Presented at the American Academy of Orthopaedic Surgeons 73rd Annual Meeting. March 22-26, 2006. Chicago.
  • Joyce MJ, Greenwald AS, Boden SD, Heim C, et al. Safety of musculoskeletal allograft tissue. SE #73. Presented at the American Academy of Orthopaedic Surgeons 73rd Annual Meeting. March 22-26, 2006. Chicago.

Despite a variety of bone graft substitute options, an ideal solution eludes surgeons
Understanding available bone graft alternatives and properly selecting them yields optimal results.
by Susan M Rapp
When the acetabulum is at risk for instability or compromised bone growth related to revision arthroplasty, using a bone graft substitute may make good clinical sense, according to a surgeon at the Hospital for Special Surgery.  
Surgeons can choose from materials made of calcium sulfate, calcium phosphate and synthetic substances, as well as a few bone morphogenetic proteins (BMP) and cell-based options, all of which are being used increasingly in hip arthroplasty revision surgery.
However, they vary greatly in terms of their osteoinductivity and osteoconductivity, Bostrom said.

Ultimate substitute

During a presentation at the Current Concepts in Joint Replacement Spring Meeting, Bostrom discussed bone grafting substitute options.
Calcium-based graft substitutes are one option for porous materials, with hydroxyapatite and tricalcium phosphate in forms like pellets, granules and block, among calcium phosphate-based products. These are resorbed over time and new bone forms on top of them.
Plaster of Paris-like calcium sulfate products involve a different biologic process and get dissolved through a chemical process.
Surgeons have also reported success using bone-bank supplied demineralized bone matrix (DBM) in the acetabulum comparable to that of autograft.

Factoring in bone growth

Osteoinductive bone graft substitutes include recombinant human BMP-2 on a resorbable collagen sponge (Infuse, Medtronic Sofamor Danek) and BMP- 7 (Osteogenic Protein-1, Stryker Biotech).
Though mainly indicated for spine and long bone fracture applications, using them in the acetabulum is usually limited to pelvic discontinuities, he said.
Platelet concentration systems that enhance tissue repair factors like fibroblast growth factor and platelet-derived growth fact by four or five times are also available.

For more information:
  • Mathias P.G. Bostrom, MD, can be reached at the Hospital for Special Surgery, 535 East 70th St., New York, NY 10021; 212-606-1000; e-mail: Bostromm@hss.edu. He has no direct financial interest in any product or company mentioned in the article.
Reference:
  • Bostrom MPG. Allograft alternatives: Bone substitutes & beyond. #100. Presented at the 9th Annual Current Concepts in Joint Replacement Spring 2008 Meeting. May 18-21, 2008. Las Vegas.