Dear OTW Reader: Seven Modes of Metal-on-Metal Hip Failure…These College Students 5x More Likely to Have Shoulder Instability…Another Look at Outpatient Joint Replacement…New Leadership at SBi and SI Bone…Two Reasons Patients Have Higher Rates of Medial Meniscus Injury and more….
The Seven Modes of MOM Failure…
Timothy Wright, Ph.D., Kirby Chair of Orthopedic Biomechanics at Hospital for Special Surgery (HSS), and Douglas Padgett M.D., chief of Adult Reconstruction and Joint Replacement with HSS, have just completed a study that gives the first comprehensive look at the modes of failure in metal-on-metal (MOM) total hip replacements.
Dr. Wright tells OTW, “There is a long history of analyzing retrieved implants and making observations about the kinds of damage you see on the surface…but little comprehensive information about the mechanism behind the damage. I think it’s fair to say that we don’t have our arms around the problem yet…not from an implant standpoint, a surgical technique standpoint, a manufacturing standpoint, or from a patient standpoint (do they have host factors that make them more susceptible to damage?). One of the things that is still unclear is metal ion concentrations in the blood. Yes, patients with higher levels are often symptomatic, but there are also patients with low levels who are symptomatic.
“We looked at how we could begin to match our observations of the damage modes on the surface with quantitative measurements of how much the component wore in the damaged areas as well as with other factors such as metal ion levels, MRI imaging, and the surgical positioning of components, manufacturer, and head size. We found seven distinct damage modes, some of them obvious as to the underlying mechanisms of failure. For example, 100% of the heads were scratched, probably due to hard chunks of carbide from the metal component or due to spicules (tiny spike-like structures which are found in many organisms—sponges, for example) of bone.
This is important because in the second part of our study, we are working with a company that has the technology to tell us where material has been removed. So if I’m staring at the head, where is the geometry altered? If you now take the descriptors of what the surface looks like, together with how the material was removed, it gives us more confidence in trying to understand mechanisms.”
Freddie H. Fu, M.D. Wins Sports Award
The distinguished chair of the Department of Orthopedic Surgery at the University of Pittsburgh—Dr. Freddie Fu—is being honored with the 2012 Dapper Dan Sports Leadership Award for his efforts to improve the health of athletes. Dapper Dan was founded in 1936 by Pittsburgh Post-Gazette sports editor Al Abrams. Over time the organization has evolved from a businessmen’s sports club into a substantial charity. Dr. Fu is credited with helping to establish the Sports and Preventive Medicine Institute in 1985. He also was instrumental in the establishment of the University of Pittsburgh’s Sports Medicine Fellowship Program. Dr. Fu is known far and wide for his novel surgical techniques for treating sports-related knee and shoulder injuries, as well as his extensive scientific and clinical research in the biomechanics realm. Dapper Dan, a charitable organization with six fundraising events per year, will bestow this honor on Dr. Fu March 12, 2012 at the annual Dapper Dan Sportsman of the Year Dinner.
Risk of Shoulder Instability 5x Greater in These College Students
U.S. Army LTC Brett Owens, M.D. followed West Point cadets from 2006-2010, comparing cadets with a history of shoulder instability and dislocation to those without such a prior injury. They found that those cadets with a prior history of glenohumeral joint instability were more than five times more likely to experience future instability than their classmates. Dr. Owens told OTW, “Before our study, there was only anecdotal evidence of high incidence shoulder instability at West Point…but no one knew how common it was or the risk factors involved. And in the prevention arena, most of the work had been focused on ACL injuries…despite the fact that shoulder instability is also a common reason athletes seek orthopedic care. In our study we had data on 700 individuals (1, 400 shoulders). And one of the advantages of our institution is the ability to conduct strict surveillance because it is a closed community.
We were able to correlate baseline characteristics with a history of instability, with those that had ligamentous laxity. Our population is similar to the U.S. collegiate athlete population, and we are hoping that folks who care for young athletes will find our research applicable. There are two important messages I have for my colleagues. First, this work reinforces the importance of early stabilization of first time dislocators. Secondly, we must focus on primary prevention. Most shoulder instability research has been on surgical treatments, but no one has looked at primary prevention. Once you injure yourself you are in a different category; those never before injured are the ones to target for prevention.”
Another Look at Outpatient Joint Replacement
Dr. Richard Berger, a hip and knee surgeon at Midwest Orthopaedics at Rush, has been doing over 1, 200 joint replacement operations a year for the last several years…and 75% of those are outpatient.
Said Dr. Berger to OTW: “At Rush we are routinely doing outpatient joint replacement, and in doing so are giving patients not only better health, but more and earlier independence. For patients having their hip or knee replacement complete before noon, 96% are able to go home the day of surgery. In fact, we have had such success that we have been able to now include just about all patients in this outpatient protocol—regardless of their age. It’s a win-win for everyone—patients get the benefit of being less dependent on others and hospitals save money and bed space.
So why hasn’t this caught on? Because it’s currently very complicated, and requires a team approach that includes anesthetists, physical therapy, discharge planners, etc. We have ten years of data showing that this is a safe, effective approach to joint replacement. I believe that as more surgeons become facile at the surgery and feel more comfortable with the team approach to short stay after joint replacement, this short stay will start to catch on. Once there are enough places around the country doing outpatient total joints, I believe it will become commonplace.”
Michael P. Simpson New President, CEO at SBi
Small Bone Innovations, Inc. (SBi), a leading, privately held orthopedics company focused exclusively on arthroplasty and joint-related trauma technologies and treatments for the small bones and joints, has appointed Michael P. Simpson as President and Chief Executive Officer, effective February 21, 2012.
Mr. Simpson’s appointment enables Anthony G. Viscogliosi, SBi’s Founder, Chairman and CEO since 2005, to step up to the new position of Executive Chairman. Mr. Simpson held several senior executive positions during his nine year career at Orthofix, Inc., a unit of Orthofix International NV. During Mr. Simpson’s career as a division President at Orthofix, an orthopedic devices company with $575 million-plus revenues in 2011, he managed the global development and distribution internationally of the product portfolio, including foot and ankle technologies, with full P&L responsibility.
These ACL Patients Have Higher Rates of Medial Chondral Injury
Guillaume Dumont, M.D. and Philip Wilson, M.D. are orthopedic surgeons with the University of Texas Southwestern Medical Center in Dallas, Texas. Dr. Dumont told OTW, “Our recent study found that children who had delayed treatment of an ACL injury more than 150 days were more likely to experience a medial meniscus tear or chondral injury in their knee. Additionally, children more than 15 years old had a higher rate of associated medial meniscus injury. We examined the effect of the child’s weight, something that had not been looked at previously; we found that children with ACL tears who weighed more than 143 pounds had an increased rate of medial and lateral meniscal tears at the time of surgery. A complete physical examination of the knee, and often an MRI are important in identifying ligamentous and cartilage injuries in the knee. Our study helped identify factors that are often associated with increased rates of meniscus and chondral injuries. In the future, it would be beneficial to investigate long term functional outcomes in patients who had ACL reconstructions as children.
We know that with ACL reconstruction and a good rehabilitation program, patients have improved knee stability—however at this point we do not know the long term risk of knee arthritis and overall knee function twenty years down the line. We should be vigilant about treating our patients with ACL tears to minimize the risk of further cartilage injury, and consider surgical reconstruction even in young patients. It is important to emphasize that surgeons treating pediatric patients with ACL tears should feel comfortable dealing with open growth plates to avoid injuring them.”
Daniel Cher, M.D., W. Carlton Reckling, M.D. Join SI-Bone
Dr. Daniel Cher, an internist with over 15 years of clinical affairs and research experience in a variety of medical device technology companies, has been named Vice President of Clinical Affairs at SI-Bone. Dr. W. Carlton Reckling, an orthopedic spine surgeon with over 17 years of spine surgery and clinical research experience, was named Vice President of Medical Affairs. Dr. Cher has developed clinical and regulatory strategies, designed and led clinical trials, and directed clinical research. He has worked at early-stage companies developing new minimally invasive therapies for interventional neuroradiology and for spine surgery. Dr. Reckling has worked as a spine surgeon in Wyoming and Colorado, where he utilized a number of minimally invasive therapies for different spinal surgical procedures. Both physicians will work with multiple parties to develop a consensus diagnostic process for identification of SI joint conditions.
