Knee Replacement: Pre-Operative Exercises, Safety, and Recovery Preparation

How to exercise when you need a knee replacement?

Exercising before a knee replacement, often referred to as "pre-habilitation" or "pre-hab," is a critical step in preparing your body for surgery and optimizing your post-operative recovery, focusing on maintaining muscle strength, joint mobility, and overall fitness while carefully managing pain and avoiding further joint damage.

Understanding the Need for Knee Replacement

Total Knee Arthroplasty (TKA), commonly known as knee replacement surgery, is a procedure to resurface a knee damaged by arthritis, injury, or other conditions. It involves replacing the worn-out bone and cartilage with prosthetic components. While surgery is the ultimate solution for severe cases, the period leading up to it offers a crucial window to prepare your body. Pre-habilitation can significantly improve surgical outcomes, reduce hospital stays, and accelerate rehabilitation.

The Goals of Pre-Operative Exercise

Engaging in targeted exercise before knee replacement surgery serves several vital purposes:

• Maintain or Improve Muscle Strength: Strong muscles surrounding the knee (quadriceps, hamstrings, glutes, calves) provide support and stability, which are crucial for walking and daily activities post-surgery.
• Preserve Joint Range of Motion (ROM): While severely arthritic knees may have limited ROM, gentle exercises can help prevent further stiffness and make post-operative flexibility easier to regain.
• Reduce Pain and Inflammation: Appropriate, low-impact exercise can sometimes alleviate symptoms by improving blood flow and muscle function, though pain management remains a primary concern.
• Enhance Cardiovascular Fitness: Better heart and lung health improves surgical tolerance and overall recovery.
• Improve Balance and Stability: Stronger muscles and better proprioception (body awareness) reduce the risk of falls, both before and after surgery.
• Educate and Prepare: Familiarity with exercises and movement patterns used in pre-hab can make post-operative physical therapy more effective and less daunting.

Core Principles for Safe Exercise

Exercising with a compromised knee requires a cautious, informed approach. Adhere to these principles:

• Listen to Your Body: Pain is a critical indicator. If an exercise causes sharp, increasing, or persistent pain, stop immediately. Mild discomfort is acceptable, but sharp pain is a warning sign.
• Prioritize Low-Impact Activities: High-impact movements put excessive stress on the joint. Opt for exercises that minimize pounding and twisting.
• Focus on Controlled, Smooth Movements: Jerky or uncontrolled motions can exacerbate pain or damage.
• Gradual Progression: Start with a manageable intensity and duration, gradually increasing as your body adapts and pain allows.
• Consistency is Key: Regular, short bouts of exercise are often more beneficial than infrequent, intense sessions.
• Proper Form: Incorrect technique can lead to injury. If unsure, seek guidance from a physical therapist.
• Consult Your Healthcare Team: Always discuss your exercise plan with your orthopedic surgeon and physical therapist. They can provide personalized recommendations and modifications based on your specific condition.

Recommended Exercise Categories

The following categories and examples are generally safe and beneficial, but always consult with your physical therapist for a tailored program.

Low-Impact Aerobic Exercise

These activities improve cardiovascular health without excessive joint stress.

• Walking: If pain allows, walking on a flat, even surface is excellent. Use supportive footwear. Consider using walking poles for added stability and reduced knee load.
• Stationary Cycling: A recumbent or upright stationary bike is ideal. Set resistance low and focus on smooth, circular pedal strokes. Ensure the seat height allows for only a slight bend in the knee at the bottom of the pedal stroke.
• Aquatic Exercises/Swimming: Water provides buoyancy, reducing the load on your joints. Walking in water, gentle kicking, and swimming (freestyle or backstroke) are excellent options.
• Elliptical Trainer: If available and pain-free, an elliptical can provide a good full-body workout with minimal impact.

Strength Training

Focus on strengthening the muscles supporting the knee, hips, and core, often using non-weight-bearing or reduced-weight-bearing exercises.

• Quadriceps Strengthening:
  • Quad Sets: Lie on your back, straighten your leg, and press the back of your knee into the floor by tightening your thigh muscle. Hold for 5-10 seconds, relax.
  • Straight Leg Raises: Lie on your back with one knee bent. Keep the affected leg straight and slowly lift it a few inches off the floor, keeping the quadriceps tight. Lower slowly.
  • Knee Extensions (Machine or Resistance Band): Use a leg extension machine with light weight, or a resistance band. Perform controlled, partial movements if full extension causes pain.
  • Wall Slides: Stand with your back against a wall, feet shoulder-width apart. Slowly slide down the wall as if sitting in a chair, only going as far as comfortable (often a shallow squat). Push back up.
• Hamstring Strengthening:
  • Hamstring Curls (Seated or Prone): Use a leg curl machine with light weight, or perform standing hamstring curls with a resistance band.
  • Glute Bridges: Lie on your back with knees bent, feet flat. Lift your hips off the floor, squeezing your glutes, until your body forms a straight line from shoulders to knees.
• Gluteal and Hip Strengthening:
  • Clamshells: Lie on your side with knees bent and stacked. Keeping your feet together, lift your top knee towards the ceiling.
  • Side-Lying Leg Lifts (Hip Abduction): Lie on your side with legs straight. Lift your top leg towards the ceiling, keeping it straight and avoiding rolling your hips back.

Flexibility and Range of Motion (ROM)

Gentle movements to maintain existing flexibility and prevent further stiffness.

• Heel Slides: Lie on your back. Slowly slide your heel towards your buttocks, bending your knee as far as comfortable without pain. Then, slide it back down.
• Gentle Hamstring Stretches: While seated or lying, gently stretch your hamstrings, avoiding excessive knee strain. Do not force the stretch into pain.
• Calf Stretches: Perform standing calf stretches against a wall, keeping the knee slightly bent or straight depending on the calf muscle targeted.

Balance Training

Important for preventing falls, but must be done with extreme caution and support.

• Standing on One Leg (with Support): Hold onto a sturdy surface (countertop, chair) and practice standing on one leg for short durations. Gradually increase time and reduce support as tolerated.
• Heel-to-Toe Walking: Walk by placing the heel of one foot directly in front of the toes of the other, as if on a tightrope. Maintain close proximity to a wall or counter for support.

Exercises to Avoid

Certain exercises can exacerbate knee pain or cause further damage when a knee replacement is imminent:

• High-Impact Activities: Running, jumping, plyometrics, high-impact aerobics (e.g., step aerobics).
• Deep Squats or Lunges: These can place excessive compressive and shear forces on an already damaged joint.
• Sports Involving Pivoting or Sudden Stops/Starts: Basketball, tennis, soccer, skiing, racquetball.
• Any Exercise Causing Sharp, Increasing, or Persistent Pain: This is the most crucial rule. Do not push through significant pain.
• Heavy Lifting with Lower Body: Especially if it puts direct strain on the knee joint.

Important Considerations and Red Flags

• Pain Management: Use ice packs after exercise to reduce inflammation and pain. Follow your doctor's recommendations for pain medication.
• Swelling and Inflammation: Monitor for increased swelling, redness, or warmth around the knee. These could be signs of overexertion or further irritation.
• Instability: If your knee feels like it's giving way, stop the activity and consult your doctor.
• Cross-Training: While focusing on the knee, don't neglect upper body and core strength. This can aid in daily tasks and overall fitness.
• Weight Management: Losing even a small amount of weight can significantly reduce stress on the knee joint and improve surgical outcomes.

The Role of a Healthcare Professional

Exercising when you need a knee replacement is not a DIY project. It is essential to work closely with:

• Your Orthopedic Surgeon: To understand your specific diagnosis, surgical plan, and any contraindications for exercise.
• A Physical Therapist (PT): A PT is invaluable for developing a personalized pre-habilitation program. They can assess your current function, prescribe appropriate exercises, teach correct form, help manage pain, and guide your progression safely. They will also be crucial for your post-operative rehabilitation.

Conclusion

Pre-habilitation is a powerful tool in preparing for knee replacement surgery. By strategically engaging in low-impact, strengthening, and flexibility exercises, you can improve your physical condition, reduce pain, and set the stage for a smoother and faster recovery. Remember that consistency, caution, and close collaboration with your healthcare team are paramount to exercising safely and effectively on your journey towards a healthier, more mobile knee.