Knee Replacement: Exercises to Avoid, Risks, and Safe Alternatives

What exercises are not good after knee replacement?

After total knee replacement (TKA), certain exercises and activities are contraindicated due to the risk of accelerating implant wear, causing instability, or leading to periprosthetic complications. High-impact movements, deep knee flexion, and activities involving twisting or pivoting should generally be avoided to protect the prosthetic joint and ensure long-term surgical success.

Understanding Total Knee Arthroplasty (TKA) and Exercise

Total Knee Arthroplasty (TKA), commonly known as knee replacement surgery, is a highly effective procedure designed to relieve pain and restore function in individuals with severe knee arthritis. The surgery replaces damaged bone and cartilage with prosthetic components, typically made of metal alloys and high-grade plastics. While TKA significantly improves quality of life, the new joint has specific biomechanical limitations and vulnerabilities that necessitate a careful approach to exercise. The primary goals post-surgery are to regain mobility, strength, and function while preserving the integrity and longevity of the implant.

General Principles for Exercise After TKA

Before delving into exercises to avoid, it's crucial to understand the overarching principles guiding post-TKA activity:

• Protect the Implant: The prosthetic components, particularly the polyethylene liner, are subject to wear over time. High-impact or repetitive shear forces can accelerate this wear.
• Prevent Instability: The soft tissues surrounding the new joint (ligaments, capsule) need time to heal and adapt. Extreme ranges of motion or uncontrolled movements can compromise stability.
• Avoid Falls: A fall, especially in the early post-operative period, can lead to severe complications like periprosthetic fractures or implant dislocation.
• Listen to Your Body: Pain is a critical indicator. Any sharp, persistent, or increasing pain during or after an activity warrants immediate cessation and medical consultation.
• Follow Professional Guidance: Your orthopedic surgeon and physical therapist are your primary resources for personalized exercise prescriptions and limitations. Their advice is paramount.

Exercises and Movements to Avoid After Knee Replacement

Based on the biomechanical considerations of a prosthetic knee joint, the following types of exercises and specific movements are generally not recommended after TKA:

• High-Impact Activities:

  • Running and Jogging: The repetitive ground reaction forces place significant stress on the implant, accelerating wear of the polyethylene component.
  • Jumping and Plyometrics: Activities like box jumps, jumping jacks, or any explosive movements involve high impact and uncontrolled landing forces that can damage the implant or surrounding bone.
  • High-Impact Sports: Sports such as basketball, volleyball, soccer, and racquet sports (without significant modification) involve sudden starts, stops, jumps, and pivots that are detrimental to the prosthetic knee.

• Deep Knee Flexion and Extreme Ranges of Motion:

  • Deep Squats (below 90 degrees): While some functional flexion is necessary, consistently squatting deeply can put excessive stress on the posterior aspect of the implant and surrounding soft tissues. This can also lead to patellofemoral tracking issues.
  • Full Kneeling: Direct pressure on the patella and the anterior aspect of the knee joint can be painful and potentially damage the implant or surrounding tissues. While some individuals may eventually tolerate brief, modified kneeling, it's generally discouraged.
  • Leg Press with Excessive Depth: Similar to deep squats, pressing the sled too far back can force the knee into extreme flexion, increasing stress on the implant.

• Twisting and Pivoting Motions:

  • Sports with Lateral Movement and Rotational Forces: Activities like golf (without proper swing modification), tennis, skiing (especially downhill), and dance forms that involve rapid turns can create shear and rotational forces on the knee, potentially leading to loosening of components or instability.
  • Pivoting on the Affected Leg: Any movement where the foot is planted, and the body rotates around the knee, should be avoided. This puts unnatural rotational stress on the prosthesis.

• Heavy Lifting with Poor Form or Excessive Load on the Knee:

  • Heavy Leg Extensions: While controlled leg extensions can be part of rehabilitation, performing them with very heavy weights can create excessive anterior shear forces on the tibia relative to the femur, potentially stressing the tibial component of the implant.
  • Very Heavy Squats or Leg Presses: While light to moderate resistance is beneficial, attempting maximal lifts with heavy loads can place undue compressive and shear stress on the prosthetic joint.

• Activities with High Risk of Falling:

  • Downhill Skiing: The combination of speed, uneven terrain, and the risk of falls makes this a high-risk activity for individuals with TKA.
  • Ice Skating/Rollerblading: These activities require significant balance and agility, and falls can lead to severe injuries to the prosthetic knee.
  • Uneven Terrain Hiking (especially challenging trails): While walking on even terrain is encouraged, navigating highly uneven, slippery, or steep trails increases the risk of falls.

Understanding the Risks

Engaging in the contraindicated exercises listed above can lead to several serious complications:

• Accelerated Implant Wear: The most common long-term issue, leading to the need for revision surgery.
• Component Loosening: The bond between the implant and bone can weaken over time due to excessive stress, causing pain and instability.
• Periprosthetic Fracture: A fracture of the bone around the implant, often caused by falls or high-impact trauma.
• Dislocation: Although less common in knee replacements than hip replacements, extreme movements or trauma can lead to instability.
• Pain and Inflammation: Overuse or inappropriate activity can cause pain, swelling, and inflammation around the joint.

Safe Exercise Alternatives

Instead of the contraindicated activities, focus on exercises that promote strength, flexibility, and cardiovascular health while protecting the knee:

• Low-Impact Aerobics: Walking (on level ground), cycling (stationary or road bike), swimming, elliptical training.
• Strength Training: Leg raises, hamstring curls (seated or standing), glute bridges, wall slides, partial squats (within a safe range of motion), and light leg presses, all with controlled movements and appropriate resistance.
• Flexibility and Balance: Gentle stretching, tai chi, and specific balance exercises prescribed by your physical therapist.
• Aquatic Exercises: Water provides buoyancy, reducing stress on the joint while allowing for a full range of motion.

When to Consult Your Healthcare Professional

It is imperative to maintain ongoing communication with your orthopedic surgeon and physical therapist. Consult them immediately if you experience:

• Sudden or severe pain in the knee.
• Increased swelling, redness, or warmth around the joint.
• Any feeling of instability, clicking, or grinding.
• Difficulty bearing weight on the affected leg.
• Any questions or concerns about specific exercises or activities.

Conclusion

While knee replacement surgery offers a new lease on life for many, it requires a lifelong commitment to protecting the new joint. Understanding and adhering to the guidelines regarding contraindicated exercises is crucial for the longevity of your implant and your continued well-being. Prioritize low-impact activities, avoid deep knee flexion and twisting motions, and always defer to the expert advice of your medical team to ensure a successful and active future with your new knee.