Revision Total Hip Arthroplasty: Understanding, Reasons, and Recovery

Can you replace a replaced hip?

Yes, it is definitively possible to replace a previously replaced hip, a complex surgical procedure known as revision total hip arthroplasty (THA). This advanced intervention addresses issues arising from the initial hip replacement, aiming to alleviate pain, restore function, and improve quality of life.

Understanding Revision Total Hip Arthroplasty (THA)

Revision total hip arthroplasty is a surgical procedure in which some or all of the components of a previously implanted hip prosthesis are removed and replaced with new ones. Unlike a primary hip replacement, which is performed on a native, diseased hip joint, revision surgery is performed on a hip that has already undergone prosthetic implantation. It is a more intricate and demanding procedure than the initial surgery, often requiring specialized surgical skills, advanced planning, and specific implant designs.

Common Reasons for Revision Hip Surgery

A primary hip replacement is designed to last many years, often 15-20 years or more. However, various factors can lead to its failure, necessitating a revision. The most common reasons include:

• Aseptic Loosening: This is the most frequent cause, where the implant components become loose from the surrounding bone without infection. This can be due to wear debris causing bone loss (osteolysis), or simply the mechanical failure of the bond between the implant and bone over time.
• Periprosthetic Joint Infection (PJI): An infection around the implant, which can be acute (occurring soon after surgery) or chronic (developing months or even years later). This often requires a two-stage surgery: removal of the infected components and a temporary antibiotic spacer, followed by re-implantation of new components after the infection is cleared.
• Instability/Recurrent Dislocation: The femoral head (ball) repeatedly comes out of the acetabular component (socket). This can be due to implant malposition, soft tissue imbalance, or patient-specific factors.
• Periprosthetic Fracture: A fracture of the bone around the hip implant, often caused by trauma or stress on weakened bone.
• Component Wear: Over time, the bearing surfaces (e.g., polyethylene liner) can wear down, leading to increased friction, debris production, and potential loosening.
• Implant Malposition: The original components were not ideally placed, leading to biomechanical issues, pain, or instability.
• Pain of Unknown Origin: Persistent pain despite no obvious mechanical or infectious cause, sometimes requiring exploration.

The Complexity of Revision Hip Surgery

Revision THA is significantly more challenging than a primary hip replacement for several reasons:

• Altered Anatomy: The presence of scar tissue, previous surgical approaches, and potential bone loss makes identifying normal anatomical structures more difficult.
• Compromised Bone Stock: The bone around the original implant may be damaged, weakened, or deficient, making it challenging to achieve stable fixation of new components. Bone grafting (autograft or allograft) or specialized implants may be necessary.
• Component Removal: Explanting (removing) the well-fixed original components can be difficult and carries a risk of further bone damage or fracture.
• Increased Blood Loss: Due to scar tissue and longer operative times, blood loss can be higher.
• Longer Operative Time: Revision surgeries typically take longer than primary replacements.
• Higher Risk Profile: The cumulative risks of surgery are generally higher for revision procedures.

Surgical Procedure Overview

The specific steps of a revision THA vary greatly depending on the reason for failure and the extent of bone loss. However, general stages include:

• Pre-operative Assessment: Extensive imaging (X-rays, CT scans, MRI, bone scans) is crucial to assess the condition of the existing components, bone stock, and identify the cause of failure. Blood tests are also performed, especially if infection is suspected.
• Anesthesia: Typically general anesthesia, sometimes combined with spinal or epidural anesthesia.
• Incision: Often the original surgical incision is used, but it may be extended or a new incision may be necessary.
• Exposure: The surgeon carefully navigates through scar tissue to expose the hip joint and existing prosthesis.
• Component Removal: The failed components are carefully removed. This can be a delicate process, especially if they are well-fixed or if there is significant bone ingrowth. Specialized tools are often required.
• Debridement and Bone Preparation: Any remaining cement, fibrous tissue, or infected material is removed. The bone is then prepared to accept the new components, which may involve reaming, shaping, and potentially bone grafting.
• New Component Implantation: New prosthetic components are selected and implanted. These are often larger, longer, or more modular than primary implants to compensate for bone loss or provide greater stability. Custom implants may also be used in complex cases.
• Closure: The surgical site is irrigated, and the layers of tissue are meticulously closed.

Recovery and Rehabilitation

Recovery from revision hip surgery is often more demanding and prolonged than from a primary hip replacement.

• Hospital Stay: Typically longer, ranging from a few days to over a week, depending on complexity and recovery progress.
• Pain Management: Aggressive pain management strategies are crucial.
• Physical Therapy: Intensive physical therapy is paramount. It begins almost immediately after surgery, focusing on regaining range of motion, strength, and mobility.
• Weight-Bearing Restrictions: Patients may have more stringent or prolonged weight-bearing restrictions compared to primary THA, especially if extensive bone grafting or complex fixation was performed.
• Assistive Devices: Crutches or a walker are used for an extended period.
• Long-Term Rehabilitation: Full recovery can take 6-12 months or even longer. While significant improvement in pain and function is expected, the level of function may not always reach that of a successful primary THA.

Risks and Potential Complications

While generally safe, revision hip surgery carries higher risks than primary hip replacement. Potential complications include:

• Infection: Higher risk of periprosthetic joint infection (PJI).
• Dislocation: The risk of the new hip dislocating is higher than after a primary replacement.
• Nerve or Vascular Damage: Increased risk due to scar tissue and altered anatomy.
• Periprosthetic Fracture: Fracture of the femur or pelvis during component removal or insertion.
• Blood Loss: Potentially higher, sometimes requiring blood transfusions.
• Leg Length Discrepancy: Can occur despite efforts to equalize leg length.
• Deep Vein Thrombosis (DVT) and Pulmonary Embolism (PE): Blood clots are a risk with any major surgery.
• Continued Pain: Some patients may experience persistent pain even after a technically successful revision.
• Aseptic Loosening (Recurrence): The revised implant can also eventually loosen.

Prognosis and Longevity

The success rate of revision hip surgery is generally good, with most patients experiencing significant pain relief and improved function. However, the outcomes vary depending on the reason for the revision:

• Infection: Outcomes for infection-related revisions are often less predictable due to the persistent risk of recurrence.
• Mechanical Failure: Revisions for aseptic loosening or wear generally have good outcomes.

The longevity of a revised hip implant is generally shorter than that of a primary hip replacement, particularly if there was significant bone loss or multiple prior surgeries. While many revision implants last 10-15 years or more, subsequent revisions become increasingly complex and risky.

Conclusion: A Viable but Complex Solution

Replacing a replaced hip is a well-established and often necessary procedure that can significantly improve the lives of patients suffering from a failed primary hip replacement. While it is a more complex and demanding surgery with a higher risk profile and a longer, more challenging recovery than the initial procedure, it offers a viable solution for restoring mobility and alleviating chronic pain. Patients considering revision THA should seek evaluation from an experienced orthopedic surgeon specializing in complex joint replacement to ensure a thorough assessment and individualized treatment plan.