Cement Spacer: Mobility, Precautions, Risks, and Recovery

Can you walk with a cement spacer?

Yes, walking with a cement spacer is often possible, but it is typically undertaken with significant limitations, strict weight-bearing precautions, and under close medical and physical therapy supervision due to the temporary and often fragile nature of the implant.

Understanding the Cement Spacer: Purpose and Function

A cement spacer, specifically an antibiotic-laden cement spacer, is a critical component in the management of periprosthetic joint infection (PJI), a serious complication following joint replacement surgery (arthroplasty). Unlike a permanent joint implant, a spacer is a temporary device designed to fulfill several vital roles:

• Antibiotic Delivery: It is impregnated with antibiotics that leach directly into the surrounding tissue, targeting the infection locally. This direct delivery is often more effective than systemic antibiotics alone.
• Space Maintenance: It preserves the anatomical space between the bones where the joint once was, preventing the soft tissues from contracting and scarring, which would complicate the subsequent definitive (second-stage) joint replacement surgery.
• Limited Mobility: While temporary, it provides some degree of mechanical stability, allowing for early, controlled mobilization of the limb, which is crucial for preventing stiffness and muscle atrophy.

Commonly used in the hip and knee, the spacer is typically made from bone cement (polymethyl methacrylate or PMMA) molded into a shape resembling the original joint components.

Immediate Post-Operative Mobility and Weight-Bearing

Following the insertion of a cement spacer, immediate mobility and weight-bearing protocols are highly individualized and depend on several factors:

• Surgeon's Protocol: The specific instructions from the orthopedic surgeon are paramount, as they are tailored to the patient's unique situation, the stability of the spacer, and the severity of the infection.
• Joint Location:
  • Knee Spacer: Patients are often allowed partial weight-bearing (e.g., 20-50% of body weight) with the aid of crutches or a walker. Full weight-bearing is generally discouraged due to the risk of spacer fracture or subsidence.
  • Hip Spacer: Weight-bearing restrictions for hip spacers can be more stringent, often requiring non-weight bearing or touch-down weight-bearing, given the higher forces transmitted through the hip joint during gait.
• Spacer Design: Some spacers are more robust and designed to allow for limited weight-bearing, while others are more fragile and require strict non-weight bearing.
• Patient Factors: Bone quality, muscle strength, pain tolerance, and overall health status influence the prescribed weight-bearing status.

The primary goal during this initial phase is to allow for controlled, protected movement to prevent joint stiffness and muscle weakness, without jeopardizing the spacer's integrity or the infection treatment. Assistive devices like walkers, crutches, or even wheelchairs are essential tools to manage weight-bearing.

The Goals of Ambulation with a Spacer

Walking with a cement spacer is not about achieving full functional recovery, but rather about:

• Maintaining Joint Motion: Preventing severe contractures and preserving range of motion in the affected joint.
• Minimizing Muscle Atrophy: Engaging the surrounding musculature to prevent significant strength loss, which would impede recovery after the definitive joint replacement.
• Promoting Circulation: Gentle movement can aid in local blood flow, potentially assisting in the healing process and reducing swelling.
• Improving Patient Comfort: Controlled ambulation can contribute to a sense of normalcy and independence, improving the patient's psychological well-being during a challenging treatment period.
• Preparing for the Next Stage: The ability to move, even with limitations, helps prepare the limb for the second surgery and subsequent, more intensive rehabilitation.

Potential Risks and Complications of Walking on a Spacer

Despite its benefits, walking on a cement spacer carries inherent risks that necessitate strict adherence to medical advice:

• Spacer Fracture or Dislocation: The cement spacer is not designed to withstand the full physiological loads of normal walking or impact activities. Excessive weight-bearing or sudden movements can cause the spacer to crack, break, or dislodge, leading to instability, pain, and potentially requiring earlier surgical intervention.
• Pain and Instability: Even with appropriate weight-bearing, patients may experience pain or a feeling of instability, which can limit their ability to walk.
• Loosening: Over time, the spacer may loosen from the bone, particularly with inappropriate weight-bearing, which can compromise its function.
• Incomplete Infection Eradication: While not directly caused by walking, complications like spacer fracture can lead to further surgical procedures that might disrupt the antibiotic delivery and compromise infection treatment.
• Soft Tissue Irritation: The spacer may irritate surrounding soft tissues, causing discomfort or inflammation.

Rehabilitation and Physical Therapy Protocols

Physical therapy is an integral part of managing mobility with a cement spacer. A skilled physical therapist will:

• Assess and Monitor: Continuously evaluate the patient's range of motion, strength, pain levels, and adherence to weight-bearing precautions.
• Educate on Precautions: Reinforce the surgeon's weight-bearing restrictions and teach safe movement patterns.
• Gait Training: Instruct on the proper use of assistive devices (walker, crutches) and teach a modified gait pattern that minimizes stress on the spacer.
• Range of Motion Exercises: Guide the patient through gentle, controlled exercises to maintain joint flexibility without stressing the spacer.
• Strengthening Exercises: Focus on isometric or light resistance exercises for surrounding muscles, often performed in non-weight bearing positions, to prevent significant muscle atrophy.
• Balance Training: Incorporate activities to improve balance and proprioception within the safe limits of weight-bearing.

The rehabilitation program is highly individualized, progressing cautiously to ensure the integrity of the spacer and the ongoing treatment of the infection.

Transition to Definitive Joint Replacement

The period of walking with a cement spacer is temporary, typically lasting for several weeks to months, depending on the resolution of the infection. Once the infection is confirmed to be eradicated (through blood tests and sometimes aspiration of joint fluid), the patient will undergo a second surgery.

During this definitive surgery, the cement spacer is removed, and a new, permanent joint prosthesis (e.g., a total knee or hip replacement) is implanted. Following this second surgery, a more intensive and prolonged rehabilitation program will commence, aimed at restoring full joint function, strength, and range of motion.

Important Considerations and Patient Education

For anyone with a cement spacer, understanding and adhering to medical advice is paramount:

• Strict Adherence to Instructions: Never exceed the prescribed weight-bearing limits or attempt activities not approved by your surgeon or physical therapist.
• Pain is a Warning Sign: Any new or increasing pain, instability, or mechanical issues should be reported immediately to your medical team.
• Monitor for Infection: Remain vigilant for signs of recurrent infection, such as fever, chills, increased pain, redness, or drainage around the surgical site.
• Realistic Expectations: Understand that the cement spacer is a bridge to recovery, not the final solution. The goal is to manage infection and prepare for the next stage of treatment.
• Communication is Key: Maintain open communication with your orthopedic surgeon, infectious disease specialist, and physical therapist throughout the entire process.

Walking with a cement spacer is a carefully managed phase of treatment for a complex condition. With diligent adherence to medical guidance and a committed approach to rehabilitation, patients can navigate this period safely and effectively, paving the way for a successful definitive joint replacement.