Knee Surgery: Understanding Squishy Sounds, Fluid Accumulation, and When to Be Concerned

Why does my knee make a squishy sound after surgery?

A "squishy" sound or sensation in the knee after surgery is most commonly attributed to the presence of excess fluid within or around the joint capsule, known as effusion or edema, which is a normal part of the body's inflammatory and healing response.

Understanding Post-Surgical Knee Sounds

The human knee is a complex joint, and any surgical intervention, no matter how minor, initiates a cascade of physiological responses aimed at healing. During this recovery period, it's common to experience various sensations and sounds that were not present pre-surgery. A "squishy" sound or feeling is a specific complaint that warrants an explanation grounded in anatomy and post-operative physiology.

Common Causes of Post-Surgical Knee Squishiness

The primary reason for a squishy sound or sensation after knee surgery is the accumulation of fluid. This can be categorized into several mechanisms:

• Joint Effusion (Fluid within the Joint Capsule):
  • Inflammatory Response: Surgery is a controlled trauma. The body responds by sending inflammatory mediators and immune cells to the site, leading to increased blood flow and permeability of blood vessels. This results in the leakage of plasma and other fluids into the joint space.
  • Synovial Fluid Overproduction: The synovium, a membrane lining the joint capsule, produces synovial fluid to lubricate the joint. Post-surgery, inflammation can stimulate the synovium to produce excess fluid, which can accumulate and create a squishy sensation as it moves or is compressed.
  • Lymphatic System Overload: The lymphatic system is responsible for draining excess fluid and waste products from tissues. After surgery, the volume of fluid to be drained increases significantly, and the lymphatic vessels themselves might be temporarily impaired or overwhelmed, leading to fluid retention.
• Edema (Swelling in Surrounding Soft Tissues):
  • Beyond the joint capsule, the soft tissues (muscles, tendons, ligaments, skin) around the knee will also experience swelling due to the surgical trauma. This generalized edema can contribute to a squishy feeling when the area is palpated or moved, especially if the fluid is trapped between tissue layers.
• Hematoma (Blood Accumulation):
  • While less common to cause a "squishy sound" specifically, a hematoma (a collection of blood outside blood vessels) can sometimes form after surgery. If significant, it can contribute to the overall fluid accumulation and altered tissue consistency, potentially contributing to the sensation.
• Early Scar Tissue Formation:
  • As the body heals, it lays down collagen to form scar tissue. In its early, less organized stages, this new tissue can be soft and somewhat fluid-filled, potentially contributing to a squishy or "boggy" feel, though it typically doesn't produce a distinct sound.
• Gas Bubbles (Less Common for "Squishy"):
  • Occasionally, small gas bubbles can form within the joint or surrounding tissues, which can cause popping or crackling sounds (crepitus). While not typically described as "squishy," it's a possibility for post-surgical sounds. However, fluid accumulation is a much more common cause of a squishy sensation.

Is It Normal? When to Be Concerned

A mild, non-painful squishy sound or sensation that gradually improves over weeks to a few months post-surgery is often considered a normal part of the healing process. The body is working to resorb the excess fluid and remodel tissues.

However, you should contact your surgeon or physical therapist immediately if the squishy sound or sensation is accompanied by any of the following:

• Increased or sudden onset of pain.
• Significant increase in swelling.
• Redness or warmth around the knee.
• Fever or chills.
• Pus or drainage from the incision site.
• Inability to bear weight or perform prescribed exercises.
• A new, persistent, or worsening limitation in your range of motion.
• A feeling that the knee is unstable or "giving way."

These symptoms could indicate a complication such as infection, deep vein thrombosis (DVT), or a mechanical issue requiring medical attention.

What You Can Do

While the body manages the healing process, you play a crucial role in supporting it:

• Follow Post-Operative Instructions: Adhere strictly to your surgeon's and physical therapist's guidelines regarding weight-bearing, activity restrictions, and exercise protocols. These are designed to optimize healing and minimize complications.
• R.I.C.E. Protocol: Continue to apply Rest, Ice, Compression (e.g., elastic bandage or compression sleeve, if advised), and Elevation as recommended. This helps manage swelling and inflammation.
• Gentle Range of Motion: Perform prescribed gentle range of motion exercises to help circulate fluid, prevent stiffness, and encourage lymphatic drainage.
• Hydration and Nutrition: A well-hydrated body with adequate nutritional support is better equipped for healing and managing fluid balance.
• Communication: Maintain open communication with your healthcare team. Report any new or concerning symptoms promptly.

Conclusion

A squishy sound or sensation in the knee after surgery is a common experience, primarily due to the body's natural inflammatory response and the accumulation of fluid within and around the joint. While often a normal and temporary aspect of recovery, it's essential to monitor your symptoms closely. Always prioritize communication with your healthcare providers to ensure your recovery is progressing safely and effectively. They are your best resource for personalized advice and reassurance throughout your rehabilitation journey.