Bisphosphonates: Discontinue After How Many Years?
Blanketing patients with bisphosphonates is increasingly being shown to be problematic, say researchers from the Warren Alpert Medical School of Brown University. “Atypical femur fractures are on the rise, ” says Travis Blood, M.D., a resident in orthopedic surgery at Brown. Along with Drs. Feller, Cohen, Born, and Hayda, Dr. Blood set out to see if there was a time limit that should be assigned to the use of bisphosphonates. He tells OTW, “We are seeing a vast increase in these low-energy fractures throughout the American health system. And, despite the lack of clarity as to the exact mechanism of these fractures, patients are routinely told to take bisphosphonates. For our study, we went through the current literature—47 studies—and found that bisphosphonates can help prevent fragility fractures in the spine, distal radius, and femoral neck. The problem is that no one has fully examined the long term side effects of these drugs, until recently.”
“While there is no long term data showing exactly how long people should take bisphosphonates, we do know that problems are arising in these patients at the 8-10 year mark. There is no difference between men and women as far as side effects, but there is a higher prevalence of fractures in patients taking long term steroids.”
“An atypical femur fracture usually occurs in older adults, and typically begins on the lateral cortex of the femur. This is thought to be due to an accumulation of small stress fractures that do not heal under bisphosphonate therapy. With the constant tensional forces pulling on the lateral side of the femur, these fractures propagate towards the medial cortex—and may actually cause a breakage of the medial cortex.”
“We have been fixing complete atypical fractures with an intramedullary nail, but what is to be done about the contralateral side? If the patient has this kind of fracture and is on bisphosphonates then the treating physician must always obtain X-rays of the other side. If the patient is in pain, but the X-ray doesn’t show a fracture, then you should get an MRI. Then, if the fracture is present on MRI and the person is in pain then we will fix it prophylactically. If a fracture appears on the MRI, but the person is not in pain then a trial of conserve treatment is recommended.”
“Even though these are rare fractures the numbers are telling. One study (Shane et al., 2010) found that for those taking bisphosphonates for more than two years the fracture rate was 2 per 100, 000 patient-years; as it increased to eight years of bisphosphonate use that number jumped to 78 per 100, 000. Another study (Dell et al., 2012) found that at the eight-year mark the fracture rate increased to 113 per 100, 000.”
“One option is to stop prescribing these drugs, but with the proven benefit in reduction of fragility fractures it is better that we develop a system to monitor the medication side effects. We could also shorten the timeframe that patients use bisphosphonates. Ideally, researchers would do a study where patients stop the drug and give the body a chance to recover then restart them in an attempt to prevent the long term complications. Perhaps then patients who halted use of these drugs continue taking calcium and vitamin D and get DEXA scans to monitor bone quality. There is still a lot we don’t know.”
Alert: Diabetics Nearly 19 Times More Likely to Experience Infection After ACL Surgery
Any new information on hazardous postop infections can potentially save lives. Now, researchers from the MOON Group (Multicenter Orthopaedics Outcomes Network) have answered a significant question regarding infection: Does diabetes increase the risk of infection after anterior cruciate ligament reconstruction (ACLR)? Kurt Spindler, M.D., an orthopedic surgeon at Cleveland Clinic’s Department of Orthopaedic Surgery and Cleveland Clinic Sports Health, tells OTW, “It’s actually been challenging to identify risk factors in those who undergo ACLR because of the low rates of infection. Diabetes, on the other hand, is increasingly rapidly. My colleagues and I examined data from the MOON cohort from 2002-2005 and identified patients with postoperative infections. We looked at age, body mass index, smoking status, history of diabetes, and graft choice for each patient.”
“While we suspected that diabetics are at increased risk as compared to non-diabetics, it was surprising to find that patients with diabetes were 18.8 times more likely to have an infection after undergoing ACLR.”
“We also found that use of bone-tendon-bone autograft is associated with lower risk of infection after ACLR, while patient age, BMI [body mass index], and smoking status are not associated with infection risk in these patients.”
“Orthopedic surgeons should be extra careful with diabetic patients: meticulous with your surgical technique, timely with the preoperative antibiotics, and thorough when it comes to postoperative wound management. And by all means, counsel patients regarding their increased risk and the importance of controlling their glucose levels.”
Poly Debris in Osteolytic Cysts in TAR?
While the role of polyethylene (PE) debris in total hip surgery has been thoroughly studied, its role in total ankle replacement (TAR) is unclear. Murray J. Penner, M.D. of St. Paul’s Hospital at the University of British Columbia, tells OTW, “This is definitely the most important issue facing the advancement of TAR as a viable treatment solution for ankle arthritis. To this end, I undertook a retrospective review of 22 of my revision and re-operation TAR cases, specifically examining the histopathology retrieved from osteolytic lesions. We found evidence of PE in 10 cases and no PE in 12 cases; reports were unavailable for 4 cases.”
“The early onset of osteolysis in TAR, often within the first year, together with the minimal presence of PE debris found in retrieval specimens and the typical lack of visible bearing wear strongly suggest that the cause of osteolysis in TAR is complex and due to factors other than just PE wear debris. The factors may include bone injury, stress shielding, fluid pressure, and micro-motion. There may be an initial injury to bone from the preparation and implantation on the talus and we know that injury to talar bone is often associated with cystic change, as seen in talar osteochondral cystic lesions. Additionally, studies have demonstrated that the micromotion of TAR components at the time of implantation is typically significantly greater than what is acceptable for bony ingrowth. This is relevant since the hip and knee literature suggests that micromotion, along with fluid pressure at the bone-implant interface, may contribute to osteolysis. Finally, due to complex backside geometry of many TAR component designs, it is difficult to get broad surface contact across the entire bone-implant interface. This means there may be large areas that are not in good contact with bone, and these areas will therefore experience stress shielding. This may contribute to bone resorption since the bone is not being loaded. A specific patient’s response to these potential initial and ongoing injuries to the bone-implant interface, mixed with stress shielding and fluid pressure may explain why osteolytic cysts occur in close to 20% of cases within the first year after surgery.”
“We are now initiating a multicenter protocol to study the histology retrieved from an osteolytic cyst or revision total ankle. We absolutely need to solve this problem, but small numbers aren’t going to cut it. Even a busy ankle replacement surgeon may do only 30 cases per year and substantially fewer revision cases. Preliminary data from our study should be hopefully within two years.”
