Each week we will aim to bring out a concise email that provides 4-5 key pieces of information addressing a specific issue in clinical therapeutics.
This week: Atypical fractures and bisphosphonates
Bisphosphonates are used for patients with osteoporosis with the intent to reduce the incidence of fractures. Recently it has been suggested there is a link between long-term bisphosphonate use and atypical fractures in the subtrochanteric and shaft regions of the femur.
- Bisphosphonates have very prolonged effects upon bone metabolism that can persist for 5 – 10 years, acting by inducing the death of osteoclasts. It is possible that decreased osteoclast activity may lead to increased bone mineralisation and parts of the bones becoming brittle. Coupled with this long-lasting effect, reduced bone remodelling may also allow “micro-cracks” which can eventually lead to stress or fatigue fractures that occur with minimal or no trauma.
- The risk of atypical fracture is thought to increase with duration of bisphosphonate treatment. Many patients report prodromal pain prior to the fracture, usually for several weeks but in some cases for several years before the incident. Radiographic evidence has demonstrated an abnormal thickening of the lateral cortex of the femoral shaft. If pain is reported in the hip or thigh, it has been recommended that a plain radiograph should be taken and if pain persists an MRI scan performed. Ceasing the bisphosphonate should also be considered at this point.
- Bilateral fractures have been seen amongst patients with atypical fractures and it has been suggested that those who have already suffered a possible bisphosphonate fracture be carefully observed, especially if they report pain in the contralateral limb.
- After discontinuation of bisphosphonates risk of atypical fracture decreases more rapidly than might be expected (given their prolonged presence of these drugs in bone). In addition, the increased risk of fracture within the first year of bisphosphonate use tends to support the theory that bisphosphonates accumulate on bone and on fracture surfaces immediately after dosing, blocking the remodelling of these cracks (which can develop into stress fractures). As a result, it has been suggested that an approach to treatment that is based upon intermittent therapy may be of value.
- The risk of atypical fracture is small in comparison to the overall benefits of bisphosphonate therapy, t this stage awareness and monitoring appear to be the most important considerations with respect to atypical fractures.
Please consider these issues when preparing or interpreting RMMR reports or education sessions. Contributions of content or suggested topics are welcome and should be sent directly to email@example.com.