Hip Revision Surgery: Procedure, Indications, Challenges, and Recovery

How is a hip revision done?

A hip revision is a complex surgical procedure performed to replace one or more components of a previous total hip replacement (arthroplasty) that have failed due to wear, loosening, infection, or other complications, requiring a highly individualized approach based on the specific reasons for failure.

Understanding Hip Revision Surgery

A hip revision surgery, also known as revision total hip arthroplasty (rTHA), is a procedure to repair or replace a failed hip implant. Unlike a primary hip replacement, which is performed on a native hip joint, a revision deals with the complexities of existing implants, altered bone structure, and scar tissue. It is generally more involved and technically challenging than the initial surgery.

Indications for Hip Revision

The necessity for a hip revision arises when the original hip replacement no longer functions effectively or causes significant pain. Common reasons include:

• Aseptic Loosening: The most frequent reason, where the implant components (femoral stem or acetabular cup) lose their stable fixation to the bone without infection. This can be due to wear debris causing osteolysis (bone loss), or simply mechanical failure of the bond over time.
• Polyethylene Wear: The plastic liner (polyethylene) between the femoral head and acetabular cup can wear down over time, producing debris that can lead to osteolysis and loosening.
• Infection: A periprosthetic joint infection (PJI) is a severe complication where bacteria colonize the implant surfaces, leading to pain, swelling, and systemic illness. Infection often requires a multi-stage revision.
• Recurrent Dislocation: If the femoral head repeatedly separates from the acetabular cup, revision may be necessary to address implant malposition, soft tissue imbalance, or patient factors.
• Periprosthetic Fracture: A fracture of the bone around the implant can occur due to trauma or bone weakness, often requiring revision to stabilize the fracture and/or replace the implant.
• Implant Malposition or Malalignment: Incorrect placement of components during the primary surgery can lead to instability, leg length discrepancy, or accelerated wear.
• Mechanical Failure of Components: Rare instances of implant fracture or breakage.
• Pain of Unknown Origin: Persistent pain despite a well-positioned, stable, and uninfected implant can sometimes lead to revision, though less common.

Pre-Surgical Assessment and Planning

Before a hip revision, a thorough evaluation is critical. This typically involves:

• Comprehensive Medical History and Physical Examination: Assessing overall health, previous surgeries, and current symptoms.
• Advanced Imaging:
  • X-rays: To assess implant position, signs of loosening, bone loss, and component wear.
  • CT Scans: Provides detailed bone anatomy and can better visualize bone loss, implant integrity, and alignment.
  • MRI Scans: Used cautiously due to metal artifact, but can assess soft tissues and aid in ruling out other pathologies.
  • Bone Scans: Can help identify infection or areas of increased bone turnover.
• Laboratory Tests: Blood tests (e.g., ESR, CRP, white blood cell count) to screen for infection. Aspiration (fluid removal) from the joint may be performed for culture and cell count if infection is suspected.
• Templating: Surgeons use specialized software and templates to plan the size and type of new implants, considering existing bone defects and the removal of previous components.
• Consultations: May involve infectious disease specialists (for infection cases), cardiologists, or other medical specialists depending on the patient's health.

The Surgical Procedure: Step-by-Step

The exact steps of a hip revision vary significantly based on the reason for failure, the extent of bone loss, and which components need replacement. However, a general outline includes:

1. Anesthesia and Incision:

   • The patient is typically given general anesthesia.
   • The surgeon usually uses the original incision, though it may be extended or a new incision made depending on the surgical approach (e.g., posterior, anterior, lateral).

2. Exposure and Dislocation:

   • Muscles and soft tissues are carefully retracted to expose the hip joint.
   • The hip joint is dislocated, separating the femoral head from the acetabular cup.

3. Removal of Failed Components: This is often the most challenging part of the surgery:

   • Femoral Stem Removal: If the femoral stem is loose, it might be removed relatively easily. If it is well-fixed (osseointegrated), specialized instruments (osteotomes, burrs, trephines) are used to carefully cut around the implant, or a femoral osteotomy (cutting the femur lengthwise) may be performed to facilitate removal without excessive bone damage.
   • Acetabular Cup Removal: The acetabular cup is similarly removed. If it's ingrown, it requires careful dissection and often the use of specialized tools to free it from the surrounding bone while preserving as much bone stock as possible.
   • Liner and Femoral Head Removal: These are typically easier to remove once the main components are accessed.

4. Bone Preparation and Grafting:

   • After component removal, the bone surfaces are meticulously cleaned of cement, scar tissue, and any remaining wear debris.
   • Addressing Bone Loss: Significant bone loss is common in revisions. The surgeon will prepare the bone bed for the new implants. Bone grafting (using the patient's own bone, donor bone, or synthetic bone substitutes) is often necessary to fill defects and provide a stable foundation for the new components. Metal augments or cages may also be used to reconstruct bone defects.
   • Reaming and Shaping: The acetabulum is reamed to a precise size and shape to accept the new cup. The femoral canal is prepared to accept the new stem, often requiring larger or longer stems to bypass areas of weakness or bone loss.

5. Implant Insertion:

   • Acetabular Component: A new acetabular cup is inserted, often a larger size or a specialized revision cup designed to address bone defects. It may be cemented or uncemented (press-fit) with screw fixation for stability. A new liner is then placed into the cup.
   • Femoral Component: A new femoral stem is inserted into the femur. Revision stems are often longer, tapered, or modular to provide better fixation in compromised bone. The stem can be cemented or uncemented.
   • Femoral Head: A new femoral head (ball) is placed onto the stem. The size and neck length are chosen to optimize joint stability and leg length.

6. Reduction and Stability Check:

   • The new femoral head is reduced (placed) into the new acetabular liner.
   • The surgeon performs range-of-motion tests to check for stability, proper tracking, and to ensure leg length is appropriate.

7. Wound Closure:

   • The surgical site is irrigated to remove debris.
   • The muscle layers, fascia, and skin are meticulously closed in layers. A drain may be placed to remove excess fluid.

Types of Hip Revision (Based on Scope)

• Isolated Component Revision: Only one part of the original implant is replaced (e.g., only the acetabular liner for wear, or only the femoral stem for loosening).
• Partial Revision: Two components are replaced (e.g., femoral head and liner, or acetabular cup and liner).
• Total Revision: All three major components (acetabular cup, liner, and femoral stem) are replaced. This is the most common type.
• Two-Stage Revision for Infection: If infection is present, a highly specialized two-stage approach is often used.
  • Stage 1: Removal of all infected components, debridement of infected tissue, and insertion of an antibiotic-impregnated cement spacer. The patient then undergoes a prolonged course of intravenous antibiotics.
  • Stage 2: Once the infection is deemed eradicated (after several weeks or months), a second surgery is performed to remove the spacer and implant new, permanent hip components.

Potential Challenges and Considerations

Hip revision surgery is more complex than primary hip replacement due to:

• Bone Loss: The most significant challenge. Previous surgery and implant failure often lead to substantial bone defects, requiring advanced reconstruction techniques and specialized implants.
• Scar Tissue: Extensive scar tissue from previous surgery makes dissection more difficult and increases the risk of nerve or blood vessel injury.
• Infection Risk: Revisions carry a higher risk of infection compared to primary replacements.
• Longer Operative Time: The surgery typically takes longer due to the complexity of removing existing implants and reconstructing bone.
• Increased Blood Loss: Often associated with more bleeding than primary surgery.

Post-Operative Recovery and Rehabilitation

Recovery from a hip revision is generally longer and more demanding than from a primary hip replacement.

• Hospital Stay: Typically 3-7 days, depending on the complexity of the surgery and the patient's recovery.
• Pain Management: Aggressive pain management is crucial, often involving a combination of medications.
• Physical Therapy: Initiates soon after surgery.
  • Early Mobility: Gentle exercises to prevent stiffness and improve circulation.
  • Progressive Strengthening: Gradually increasing exercises to rebuild strength in the hip and surrounding muscles.
  • Weight-Bearing Restrictions: Often more stringent than primary hip replacements, especially if bone grafting or complex fixation was used. Restrictions can range from touch-down weight-bearing to partial weight-bearing for several weeks or months.
• Assistive Devices: Crutches or a walker are used for an extended period.
• Long-Term Rehabilitation: May involve outpatient physical therapy for several months. Full recovery can take 6-12 months, or even longer for very complex cases.

Risks and Complications

While generally safe, hip revision surgery carries risks, including:

• Infection: Higher risk than primary hip replacement.
• Dislocation: Risk of the new hip dislocating can be higher, especially in cases of severe soft tissue damage or bone loss.
• Nerve or Blood Vessel Damage: Due to extensive dissection and scar tissue.
• Blood Clots: Deep vein thrombosis (DVT) or pulmonary embolism (PE).
• Heterotopic Ossification: Abnormal bone growth in the soft tissues around the hip.
• Leg Length Discrepancy: Can occur despite efforts to equalize leg lengths.
• Continued Pain: While the goal is pain relief, some patients may experience persistent discomfort.
• Re-Revision: The possibility that the revised hip may also fail over time, requiring further surgery.

Conclusion

Hip revision surgery is a sophisticated and highly individualized procedure designed to restore function and alleviate pain in patients with failed hip replacements. Its success relies on meticulous pre-operative planning, advanced surgical techniques to manage bone loss and implant removal, and a dedicated post-operative rehabilitation program. Patients undergoing hip revision should seek care from experienced orthopedic surgeons specializing in complex joint replacement.