Keeping you up-to-date on recent headlines in orthopedic healthcare:


Sandcastle worm could yield a powerful medical adhesive ... Scientists have copied the natural glue secreted by a tiny sea creature called the sandcastle worm in an effort to develop a long-sought medical adhesive needed to repair bones shattered in battlefield injuries, car crashes and other accidents. They reported on the adhesive at the 238th National Meeting of the American Chemical Society (ACS). "This synthetic glue is based on complex coacervates, an ideal but so far unexploited platform for making injectable adhesives," says Russell Stewart, PhD, a bioengineer at the University of Utah (Salt Lake City). "The idea of using natural adhesives in medicine is an old one dating back to the first investigations of mussel adhesives in the 1980s. Yet almost 30 years later there are no adhesives based on natural adhesives used in the clinic." The traditional method of repairing shattered bones is to use mechanical connectors like nails, pins and metal screws for support until they can bear weight. But achieving and maintaining alignment of small bone fragments using screws and wires is challenging, Stewart said. For precise reconstruction of small bones, health officials have acknowledged that a biocompatible, biodegradable adhesive could be valuable because it would reduce metal hardware in the body while maintaining proper alignment of fractures. Stewart and colleagues duplicated the glue that sandcastle worms (Phragmatopoma californica) use while building their homes in intertidal surf by sticking together bits of sand and broken sea shells. The inch-long marine worm had to overcome several adhesive challenges in order to glue together its underwater house, and its ingenuity has served as a recipe for Stewart's research team in developing the synthetic adhesive. The challenge was to devise a water-based adhesive that remained insoluble in wet environments and was able to bond to wet objects. The team also concentrated on key details of the natural adhesive solidification process - a poorly timed hardening of the glue would make it useless. They learned the natural glue sets in response to changes in pH, a mechanism that was copied into the synthetic glue. The new glue, says Stewart has passed toxicity studies in cell culture. It is at least as strong as Super Glue and is twice as strong as the natural adhesive it mimics, he notes. Stewart has begun pilot studies focused on delivering bioactive molecules in the adhesive that could allow it to fix bone fragments and deliver medicines to the fracture site, such as antibiotics, pain relievers or compounds that might accelerate healing.

Spine fusion outcomes equivalent to those in hip and knee replacements... The first stage of a cost-utility analysis has shown that spine fusion provides excellent outcomes, according to Australian researchers. In a prospective, consecutive case series, William Sears, MBBS, an orthopedic surgeon at Macquarie University (Sydney, Australia) and his colleagues studied degenerative spondylolisthesis treated with spinal decompression and fusion. They compared these results to those of total joint arthroplasty and to age-matched population norms. They focused on one spine problem and one surgery to eliminate as many of the heterogeneous factors surrounding spine surgery as possible. Clinical inclusion criteria were neurogenic claudication, no previous surgery and failed conservative management. Patients had to have single-level spinal stenosis with investigator-defined unstable grade 1 or 2 degenerative slip. Two experienced surgeons performed posterior lumbar interbody fusion with an emphasis on correcting the deformity and restoring alignment. To measure outcomes, the researchers used the SF-12, a generic measure derived from the SF-36. The SF-12 allows comparison between different health conditions and, in particular, their management. The PCS-12 scores were similar for spines, hips and knees as well as population norms. "All groups started off significantly disabled ... the spines, hips and knees. There was no significant difference in terms of overlaps at last follow-up. They were slightly worse than the population norms but if one looks at the minimal important difference (defined as a difference of more than five points), there was none." Sears and colleagues found similar results for the mental component scores.

Endocrine Society calls for extension of Medicare coverage Of DXA bone density testing ... Hypogonadism, also known as testosterone deficiency, affects 4 million to 5 million men in the U.S. placing them at risk for developing osteoporosis. Despite the clear association of testosterone deficiency with low bone density and osteoporosis, Medicare does not provide coverage for bone density testing for these individuals. To address this concern, the Endocrine Society (Chevy Chase, Maryland) issued a Position Statement, endorsed by the National Osteoporosis Foundation, calling for Medicare coverage of bone density testing to be extended to this at-risk population. Bone mineral density, measured by dual energy X-ray absorptiometry (DXA), is an excellent predictor of the risk of fractures in both men and women. Nationally, Medicare currently provides coverage for DXA scans in men only when an individual has been previously diagnosed with osteoporosis, osteopenia or has had a vertebral bone fracture. This means that most men found to have osteoporosis are diagnosed only after a hip or spine fracture has already occurred. "The lack of Medicare coverage for DXA scans in men with hypogonadism results in underdiagnosis and undertreatment of osteoporosis, resulting in significant morbidity, mortality, and cost to society," said Robert Vigersky, MD, president of the Endocrine Society. "The Endocrine Society recommends widening the scope of Medicare coverage to include bone density scans for men with testosterone deficiency. The benefits of extending Medicare coverage of bone density testing in hypogonadal men should be more than enough incentive to change policy," said Vigersky. "Extended coverage can help prevent painful osteoporatic fractures and help reduce the high costs associated with those fractures."

Cannabis may have value in treating osteoporosis... Scientists investigating the effects of cannabis on bone health have found that its impact varies dramatically with age. The study has found that although cannabis could reduce bone strength in young people, it may protect against osteoporosis, a weakening of the bones, in later life. A team at the University of Edinburgh (Scotland) has shown that a molecule found naturally in the body, which can be activated by cannabis – called the type 1 cannabinoid receptor (CB1) - is key to the development of osteoporosis. It is known that when CB1 comes into contact with cannabis it has an impact on bone regeneration, but until now it was not clear whether the drug had a positive or negative effect. Researchers, funded by the Arthritis Research Campaign, investigated this by studying mice that lacked the CB1 receptor. The scientists then used compounds - similar to those in cannabis - that activated the CB1 receptor. They found that compounds increased the rate at which bone tissue was destroyed in the young. The study also showed, however, that the same compounds decreased bone loss in older mice and prevented the accumulation of fat in the bones, which is known to occur in humans with osteoporosis. The results are published in Cell Metabolism. Stuart Ralston, the Arthritis Research Campaign Professor of Rheumatology at the University of Edinburgh, who led the study, said: "This is an exciting step forward, but we must recognize that these are early results and more tests are needed on the effects of cannabis in humans to determine how the effects differ with age in people."

— Compiled by Holland Johnson, MDD