Perform pre-operative clinical evaluation including coagulation profile, cardiac clearance, and blood cross-matching. Ensure 8-hour NPO status, prophylactic intravenous antibiotics (usually first-generation cephalosporins) administered 60 minutes prior to incision, and thromboembolic prophylaxis via mechanical compression devices.
Post-operative management involves early mobilization with physical therapy on day 1, strict pain management via multimodal analgesia, hematologic monitoring for blood loss, and prophylactic anticoagulation. Discharge criteria include stable vital signs, independent transfer, adequate pain control on oral medication, and surgical site stability.
Comprehensive Guide: Cemented Hemiarthroplasty for Pathologic Fracture
1. Introduction & Overview
Cemented hemiarthroplasty remains a cornerstone of orthopedic oncology and geriatric trauma surgery when addressing pathologic fractures of the proximal femur. Unlike traumatic fractures, pathologic fractures occur in bone weakened by underlying systemic or localized disease—most commonly metastatic carcinoma, multiple myeloma, or primary bone tumors.
In these patients, the primary objective is not merely union of the fracture, but the immediate restoration of weight-bearing function, pain relief, and the facilitation of adjuvant therapies (such as radiation or chemotherapy). A cemented hemiarthroplasty involves the replacement of the femoral head with a prosthetic implant, secured within the femoral canal using polymethylmethacrylate (PMMA) bone cement. This procedure is favored in the pathologic setting because it provides immediate mechanical stability, allowing for early mobilization in patients who may have limited life expectancy or compromised bone quality due to tumor infiltration.
2. Technical Specifications & Mechanisms
The success of a cemented hemiarthroplasty in the setting of malignancy relies on the principles of load sharing and biological fixation.
The Role of PMMA Cement
In pathologic fractures, the endosteal bone is often compromised by tumor-induced osteolysis. Press-fit or biological fixation implants are frequently insufficient because the surrounding bone lacks the structural integrity to support the implant.
* Interdigitation: PMMA cement interdigitates into the trabecular bone, creating a mechanical interlock that compensates for the poor bone quality.
* Immediate Stability: The polymerization of PMMA provides immediate structural support, allowing for full weight-bearing post-operatively.
* Thermal Effects: The exothermic reaction of PMMA polymerization can induce localized tumor cell necrosis, which may offer a marginal oncological benefit.
Implant Selection
- Monopolar vs. Bipolar: Bipolar hemiarthroplasty is generally preferred to reduce friction at the acetabular interface and decrease the rate of acetabular wear.
- Stem Design: Standard cemented stems are usually employed; however, in cases of significant proximal femoral bone loss, long-stemmed cemented implants may be required to bypass distal cortical defects.
| Component | Function in Pathologic Fracture |
|---|---|
| Bipolar Head | Reduces wear on existing healthy acetabular cartilage. |
| Cement Mantle | Bridges gaps created by osteolytic tumor lesions. |
| Stem | Distributes load to healthy distal diaphyseal bone. |
3. Clinical Indications & Usage
Primary Indications
- Metastatic Disease: The most common indication. Patients with lesions (e.g., from breast, lung, renal, or thyroid cancer) who have sustained a femoral neck or subtrochanteric fracture.
- Multiple Myeloma: Characterized by diffuse osteopenia, making biological fixation unreliable.
- Impending Fractures: Patients with Mirels' score ≥ 9 (indicating high risk of fracture) who require stabilization before a catastrophic break occurs.
- Failed Internal Fixation: Patients who previously underwent ORIF (Open Reduction Internal Fixation) that failed due to tumor progression.
Patient Selection Criteria
- Life Expectancy: Patients with a predicted survival of > 3 months.
- Functional Status: Patients who were ambulatory prior to the fracture.
- Systemic Status: Patients fit enough to tolerate anesthesia, despite the underlying malignancy.
4. Pre-Operative Preparation
Pre-operative planning is critical to avoid intraoperative complications such as massive hemorrhage or cement embolism.
- Imaging: Full-length femur radiographs, CT scan of the pelvis/femur to assess the extent of bone destruction, and staging scans (PET/CT) to assess systemic disease.
- Medical Optimization:
- Anemia: Correction of hemoglobin levels.
- Coagulation: Assessment of clotting factors (many cancer patients are on anticoagulants or have hypercoagulable states).
- Oncology Consultation: Coordination with the oncology team to determine if adjuvant radiation is needed post-operatively.
- Prophylactic Measures: Pre-operative administration of bisphosphonates or RANK-ligand inhibitors (denosumab) is often considered, though timing must be managed to avoid delayed healing.
5. The Procedure: Step-by-Step
The surgical approach is typically the Posterolateral (Moore) or Anterolateral (Watson-Jones) approach, depending on surgeon preference and tumor location.
- Exposure: The hip joint is exposed. In pathologic cases, the capsule is often infiltrated with tumor; a wide excision of the capsule and tumor tissue is performed to achieve local control.
- Femoral Neck Resection: The femoral neck is cut at the appropriate level. If the tumor involves the neck, the resection may be more proximal.
- Preparation of the Femoral Canal: The canal is cleared of tumor tissue and debris. This is a crucial step; vigorous curettage of the canal is performed to ensure the cement mantle can bond to healthier bone.
- Canal Sealing: A distal cement restrictor is inserted to ensure a pressurized cement mantle.
- Cementing: PMMA is introduced in a retrograde fashion. The stem is inserted in the correct version (usually 10-15 degrees of anteversion).
- Reduction and Closure: The prosthetic head is reduced into the acetabulum. The hip is checked for stability and range of motion. The wound is closed in layers, often over a drain to prevent hematoma formation, which is a risk in vascular metastatic tumors.
6. Post-Operative Recovery Protocol
Recovery is tailored to the patient’s overall prognosis.
- Day 0-1: Early mobilization is the priority. Physical therapy begins with bedside sitting and standing. Full weight-bearing is encouraged as tolerated, facilitated by the immediate stability of the cement.
- DVT Prophylaxis: Given the hypercoagulable state of cancer patients, aggressive chemical and mechanical prophylaxis (LMWH or aspirin, plus SCDs) is mandatory.
- Pain Management: Multimodal pain control including nerve blocks, NSAIDs (if not contraindicated), and opioids.
- Long-term: Transition to home health or rehabilitation facility. Monitoring for local recurrence via periodic radiographs.
7. Potential Complications
While highly effective, the procedure carries specific risks:
- Cement Embolism: The most feared intraoperative complication. High-pressure cementing in a canal filled with marrow and tumor debris can force emboli into the venous system, causing sudden hypotension or cardiac arrest.
- Intraoperative Hemorrhage: Metastatic lesions (particularly renal cell carcinoma) are highly vascular. Control of bleeding is essential.
- Periprosthetic Fracture: If the tumor has progressed significantly by the time of surgery, the distal bone may be too weak to support the stem.
- Infection: Patients undergoing chemotherapy or radiation have compromised immune systems, increasing the risk of surgical site infection (SSI).
8. Alternative Treatments
- Internal Fixation (Gamma Nail/DHS): Often used if the femoral head is uninvolved or if the patient is too medically frail for arthroplasty. However, hardware failure rates are higher in the presence of extensive lysis.
- Total Hip Arthroplasty (THA): Indicated if there is pre-existing acetabular disease (e.g., protrusio or metastatic involvement of the acetabulum).
- Megaprosthesis: Reserved for cases where the proximal femur has been completely destroyed and requires resection and replacement with a modular segmental prosthesis.
9. FAQ: Frequently Asked Questions
1. Why use cemented fixation rather than cementless?
Cemented fixation is superior in pathologic cases because the bone is often osteoporotic or infiltrated by tumor, meaning it cannot provide the "press-fit" required for cementless implants.
2. What is the biggest risk during the procedure?
The biggest immediate risk is cement embolism. Surgeons mitigate this by using canal lavage, distal restrictors, and careful monitoring of hemodynamics during cement insertion.
3. How long does the patient have to wait to walk?
Most patients are encouraged to weight-bear as tolerated on the day of surgery or the first post-operative day.
4. Does the cement kill the cancer cells?
The heat generated by the curing PMMA (exothermic reaction) can reach temperatures that are cytotoxic to tumor cells, potentially providing a secondary therapeutic effect.
5. What if the cancer has spread to the acetabulum?
If the acetabulum is involved, a hemiarthroplasty will likely fail. In these cases, a total hip arthroplasty (THA) is the gold standard.
6. Are there specific cancers that bleed more?
Yes, renal cell carcinoma and thyroid cancer are notoriously hypervascular, often requiring pre-operative embolization by interventional radiology.
7. What is the success rate of this surgery?
Success in this context is defined as pain relief and restoration of function. Over 85-90% of patients report significant pain relief and improved mobility.
8. Will the patient need radiation after surgery?
Often, yes. Orthopedic surgeons usually coordinate with radiation oncologists to deliver localized radiation to the surgical site to prevent local tumor progression.
9. What is a "Mirels' Score"?
It is a scoring system used to predict the risk of pathologic fracture in long bones. A score of 9 or higher is a strong indication for prophylactic stabilization.
10. Can this surgery be performed on patients with stage IV cancer?
Yes. In stage IV patients, the goal is palliative—to improve quality of life and reduce pain for the remainder of their life.
10. Conclusion
Cemented hemiarthroplasty for pathologic fracture is an essential limb-salvage and palliative procedure. By providing immediate structural stability, it transforms the lives of patients suffering from bone metastases, allowing them to remain mobile and participate in their own care. While the procedure requires meticulous planning to manage the unique challenges of oncology patients, the outcomes regarding pain relief and functional restoration are highly favorable. As systemic therapies for cancer continue to improve, the role of the orthopedic surgeon in maintaining skeletal integrity remains as vital as ever.