Bisphosphonate-related atypical femoral fracture: Managing a rare but serious complication
ABSTRACT
Atypical femoral fracture is a rare but serious complication of long-term bisphosphonate therapy. Although the benefit of preventing osteoporotic fractures greatly outweighs the risk of atypical fracture in bisphosphonate users, concern about atypical fracture risk has led to a decrease in bisphosphonate use. What are the risks, and how do we treat atypical femoral fracture?
KEY POINTS
- The benefits of bisphosphonate therapy in reducing fracture risk outweigh the risk of atypical fracture.
- Bisphosphonate use for longer than 5 years greatly increases the risk of atypical femoral fracture.
- Treatment of atypical femoral fracture varies depending on whether the patient has pain and whether the fracture is complete or incomplete.
Intramedullary nailing for complete fracture
Intramedullary nailing is the first-line treatment for complete atypical femoral fracture, although the risk of delayed healing and revision surgery may be somewhat higher than with typical femoral fracture.46 Prophylactic intramedullary nailing should be considered for a patient with intractable pain.2
A radiograph of the opposite leg should be obtained routinely, looking for an asymptomatic fracture. Bisphosphonates should be discontinued and calcium and vitamin D continued. Teriparatide therapy can be considered as an alternative treatment.
Conservative management for incomplete fracture without pain
Incomplete atypical femoral fracture unaccompanied by pain can be followed conservatively.47 In addition to stopping antiresorptive therapy, patients need to avoid high-impact and repetitive-impact activities such as jumping or running. If pain occurs, patients should begin protected weight-bearing exercise.
,Treatment is uncertain for incomplete fracture with pain
For patients with incomplete atypical femoral fracture and pain, treatment is controversial. Regimens that include 2 to 3 months of protected weight-bearing exercise, a full metabolic bone workup, calcium and vitamin D supplementation, and anabolic bone agents have produced some success. Some authors have reported poor results from conservative care, with few patients achieving pain relief or signs of complete healing.48,49 Additionally, if an incomplete fracture is found in the opposite femur, protected weight-bearing of both legs may not be possible.
Patients with incomplete fracture should be monitored regularly with radiography and physical examination. If there is progression of the fracture, escalation of pain, or failure to heal within 2 to 3 months, then surgical treatment is necessary.
Prophylactic placement of an intramedullary nail to prevent completion of the fracture and allow a return to full weight-bearing is generally advised.50 A long locking plate can be used if bone deformities make it difficult to place an intramedullary nail; however, nails are preferred because they allow formation of endochondral callus, which can be helpful in these difficult-to-heal fractures.
Results from retrospective reviews have shown that surgically treated patients with bisphosphonate-associated incomplete atypical femoral fracture were more likely than those treated nonsurgically to be pain-free (81% vs 64%) and have radiographic healing (100% vs 18% at final follow-up).46 Results have also been positive for those with complete atypical femoral fracture. At 6 months, 64% of surgically treated patients were pain-free and 98% were radiographically healed.51
The unusual geometry of the femur in patients with atypical femoral fracture and the presence of intramedullary cortical callus makes the placement of an intramedullary femoral rod more complex than in typical femoral fracture.8
Intramedullary nailing of atypical femoral fracture is a challenge for even the most experienced surgeon, and vigilance is imperative to avoid iatrogenic fracture and malunion.
MANY QUESTIONS REMAIN
We need more studies on the pathophysiology of bisphosphonate-associated atypical femoral fracture, the value of periodic screening with DXA, and which factors predict high risk (eg, Asian ethnicity, use of certain medications, femoral geometry). In addition, we need more data on the success of conservative management of incomplete fracture, including use of teriparatide.
