What are the considerations for a partial hip replacement in a patient with a potential diagnosis of multiple myeloma?

Considerations for Partial Hip Replacement in a Patient with Suspected Multiple Myeloma

A definitive diagnosis of multiple myeloma must be established before proceeding with partial hip replacement surgery to prevent catastrophic complications and ensure optimal patient outcomes. 1

Diagnostic Evaluation Before Surgery

Before considering partial hip replacement in a patient with suspected multiple myeloma, the following diagnostic workup is essential:

1. Complete Multiple Myeloma Workup:

   • Serum and urine protein electrophoresis to detect monoclonal protein
   • Quantification of immunoglobulins (IgG, IgA, IgM)
   • Serum-free light chain measurement
   • Bone marrow aspiration and biopsy (crucial to confirm ≥10% clonal plasma cells) 1

2. Comprehensive Bone Assessment:

   • Complete skeletal survey including pelvis, spine, skull, humeri, and femurs
   • MRI or CT scan of the hip and affected areas
   • Consider whole-body MRI to identify additional lesions 1

3. Laboratory Tests:

   • Complete blood count (to assess for anemia)
   • Serum calcium (to check for hypercalcemia)
   • Renal function tests (to evaluate for renal insufficiency)
   • β2-microglobulin and serum albumin (for prognostic assessment) 1

Surgical Considerations

If multiple myeloma is confirmed, several specific considerations must guide the surgical approach:

Preoperative Considerations:

• Disease Status Assessment: Determine if the patient has active symptomatic myeloma requiring systemic therapy before surgery 1
• Bone Quality Evaluation: Multiple myeloma causes osteolytic lesions that significantly compromise bone integrity and implant fixation 2
• Fracture Risk: Assess for impending pathological fractures in other locations 3, 2
• Bisphosphonate History: Evaluate prior bisphosphonate exposure due to increased risk of atypical femoral fractures with prolonged use 3

Surgical Technique Modifications:

• Implant Selection: Consider cemented prostheses due to poor bone quality and osteolytic lesions 2
• Extended Fixation: May require longer-stem implants or augmentation with methyl methacrylate to achieve adequate fixation 2
• Prophylactic Fixation: Consider stabilizing other areas at risk of pathological fracture during the same procedure 4, 2

Perioperative Management:

• Blood Product Availability: Ensure adequate blood products are available due to potential for increased bleeding 2
• Infection Prevention: Heightened attention to infection prevention due to immunocompromised state 2
• Multidisciplinary Approach: Coordinate with hematology/oncology team regarding timing of chemotherapy relative to surgery 5

Postoperative Considerations

• Rehabilitation Protocol: Modified weight-bearing status may be necessary based on bone quality and extent of disease 2
• Systemic Therapy: Initiation of appropriate myeloma therapy if not already started 1, 5
• Bisphosphonate Therapy: Consider for prevention of skeletal-related events, but monitor for complications 3
• Surveillance: Regular radiographic follow-up to monitor for implant loosening or disease progression 2

Potential Complications

• Implant Failure: Higher risk due to poor bone quality and continued disease activity 2
• Periprosthetic Fracture: Increased risk due to weakened bone 4, 2
• Infection: Higher susceptibility due to immunocompromised state 2
• Disease Progression: Continued osteolysis may compromise long-term implant stability 2

Common Pitfalls to Avoid

1. Proceeding without definitive diagnosis: Never perform elective arthroplasty without confirming multiple myeloma diagnosis and disease extent
2. Underestimating bone destruction: Standard implants may fail due to extensive osteolysis
3. Neglecting systemic disease management: Coordination with hematology/oncology is essential
4. Inadequate preoperative planning: Failure to anticipate need for specialized implants or bone cement
5. Aggressive rehabilitation: Standard protocols may lead to periprosthetic fractures in weakened bone

In summary, partial hip replacement in patients with suspected multiple myeloma requires comprehensive diagnostic evaluation, careful surgical planning, and close multidisciplinary collaboration to optimize outcomes and minimize complications.