Management of Pelvic Fracture in a Patient on Oral Bisphosphonates
Immediate Action: Discontinue Bisphosphonate Therapy
Stop the oral bisphosphonate immediately upon diagnosis of the pelvic fracture. 1, 2 This is critical because bisphosphonates inhibit osteoclast function and bone remodeling, which can significantly impair fracture healing, particularly in atypical insufficiency fractures associated with long-term bisphosphonate use. 1, 2, 3
Determine if This is an Atypical Insufficiency Fracture
Evaluate the fracture for characteristic features of bisphosphonate-associated atypical fractures: 4, 5, 1
- Minimal or no trauma history - these fractures often occur spontaneously or with trivial trauma 4, 5
- Transverse fracture pattern with no or minimal comminution 4, 3
- Cortical thickening or beaking at the fracture site on imaging 4, 1
- Prodromal pain in the pelvis or hip region prior to fracture 4
- Duration of bisphosphonate use - most cases occur after years of therapy, though cases have been reported after as little as 4 years 4, 5
Order a bone scan to assess for bilateral involvement and rule out other associated fractures, as atypical fractures can be bilateral. 4
Metabolic Workup
Perform comprehensive laboratory evaluation: 1, 3
- Serum calcium, vitamin D (25-OH-D), and parathyroid hormone levels 6
- Renal function (creatinine, estimated GFR) 6
- Bone turnover markers if available 7
Correct any vitamin D deficiency immediately - target serum 25(OH)D level ≥32 ng/mL, as deficiency impairs fracture healing and calcium absorption. 6 Use vitamin D3 2,000 IU daily if levels >15 ng/mL, or vitamin D2 50,000 IU weekly for 8-12 weeks if <15 ng/mL. 6
Treatment Strategy
Conservative Management (First-Line for Stable Fractures)
Initiate conservative treatment with calcium and vitamin D supplementation (calcium 1,000-1,200 mg/day and vitamin D 600-800 IU/day for maintenance after repletion). 8, 5 This approach has demonstrated fracture healing in bisphosphonate-associated pelvic insufficiency fractures. 5
- Partial weight-bearing activity as tolerated 1
- Pain management with appropriate analgesics 8
- Monitor healing with serial imaging 1
Surgical Management Considerations
If the fracture is unstable, displaced, or fails to heal with conservative management, surgical fixation may be required. 1, 3 However, recognize that:
- Delayed union or nonunion is expected in bisphosphonate-associated fractures due to the drug's long half-life and persistent inhibition of bone remodeling 4, 1, 2
- Compression plating may be superior to intramedullary nailing for atypical fractures, as it addresses both the biologic and mechanical etiologies by achieving bone-on-bone contact 3
- Combined fixation techniques (plate plus intramedullary support) may offer advantages for complex fractures 1
Alternative Osteoporosis Management
Do not restart bisphosphonates. 4, 5, 1 Consider alternative anti-resorptive therapy once the fracture has healed:
- Denosumab 60 mg subcutaneously every 6 months is the preferred alternative, as it was successfully used in a documented case of bisphosphonate-associated pelvic fracture 4
- Teriparatide may be considered for severe osteoporosis, though evidence is limited in this specific context 8
- Continue calcium and vitamin D supplementation indefinitely 8, 6
Key Clinical Pitfalls
Avoid restarting bisphosphonates even after fracture healing, as the underlying pathophysiology of impaired bone remodeling persists with continued use. 1, 2 The risk of atypical fractures increases with duration of bisphosphonate therapy, affecting approximately 2.3 per 10,000 patients. 4
Do not assume all pelvic fractures in bisphosphonate users are atypical - typical osteoporotic fractures still occur and may benefit from different management strategies. 1, 2 The distinction lies in the radiographic features and clinical presentation described above.
Monitor the contralateral side for prodromal symptoms or radiographic changes, as bilateral involvement is common in atypical fractures. 4, 1