Treatment of Bone Infarcts Involving Distal Femur and Proximal Tibia Through Articular Surfaces
Bone infarcts involving the distal femur and proximal tibia with articular surface extension should be managed conservatively with observation and symptomatic pain control in most cases, as these lesions typically have a benign prognosis and do not require surgical intervention unless complicated by pathological fracture or malignant transformation.
Initial Diagnostic Approach
- Confirm the diagnosis with MRI, which consistently shows typical features of bone infarcts and obviates the need for other investigations in most cases 1
- Obtain standard radiographs to assess for high-density lesions in the center of the marrow cavity, though these may be normal initially 1
- Perform core biopsy if there is any suspicion of malignant transformation, particularly given the rare but documented risk of sarcoma development in necrotic bone 2
- Screen for multifocal disease, as bone infarcts are multifocal in over half of cases and usually accompanied by multiple foci of epiphyseal avascular necrosis 1
Risk Factor Assessment
- Investigate for known risk factors including trauma, sickle cell disease, steroid intake, alcohol abuse, gout, liver cirrhosis, and long-term bisphosphonate therapy 3, 4
- Recognize that bone infarcts are a marker for systemic avascular necrosis, requiring investigation for other foci that may have function-threatening effects 1
Conservative Management (Primary Treatment)
- Implement symptomatic pain control with NSAIDs or acetaminophen for the approximately 50% of patients who experience symptoms 1
- Monitor with serial imaging to assess for stability and rule out complications 1
- Counsel patients on the generally good prognosis of bone infarcts per se, with the exception of the very low risk of malignant transformation 1
Surgical Indications (Rare)
Surgery is indicated only in specific circumstances:
- Pathological fracture through the infarct requires fracture stabilization with intramedullary nailing for diaphyseal involvement 2
- For proximal tibial fractures with articular depression, consider open reduction with highly impacted bone allograft and locking plate fixation, which may allow immediate weight bearing 5
- Intramedullary interlocking nailing is appropriate for metaphyseal-diaphyseal junction fractures, with stabilization alone (without augmentation) leading to fracture healing 2
Surgical Technique for Articular Involvement
When surgical intervention is necessary for fractures through bone infarcts involving articular surfaces:
- Use an anterolateral approach with appropriate incision for tibial plateau involvement 5
- Create a small window in the bone using an awl, and reduce the articular surface under radiographic imaging 5
- Prepare structural bone allograft by taking large pieces of bone with bone rongeur forceps, avoiding cartilage 5
- Highly impact the bone graft under the articular surface using a trocar and hammer to provide structural support 5
- Fixate with angular stable locking plate to maintain reduction 5
Postoperative Management
- Allow immediate weight bearing when highly impacted bone allograft technique is used for articular fractures 5
- Follow patients for 6-12 months with clinical and radiological assessment to confirm fracture healing 2
- Monitor for the rare possibility of malignant transformation during long-term follow-up 2
Critical Pitfalls to Avoid
- Do not assume upper limb involvement or isolated diaphyseal lesions are bone infarcts without thorough investigation, as these locations are so rare they warrant diagnostic reappraisal 1
- Do not dismiss new onset lower limb pain in patients on long-term bisphosphonates, as atypical insufficiency fractures can occur in weight-bearing areas including the proximal tibia and distal femur 4
- Do not overlook periosteal reaction on radiographs, which may be the first and only radiographic change in bone infarcts 1
- Do not fail to screen for other sites of avascular necrosis, as bone infarcts are usually a marker for systemic disease 1