Swelling and Knee Function


The most read post on this blog deals with “Swelling, Effusion, Edema and Bruising – What’s the difference?”.  I will take the concept one step further and discuss how knee swelling or joint effusions impact your ability to control your knee extension when you walk.

So, you injure your knee and develop swelling inside the joint.  You may notice your knee giving way.  That means when you transfer weight onto your injured leg the knee buckles.  This is due to the quadriceps (front of your thigh) not contracting efficiently and hence not controlling the knee in extension.  Knee extension is vital in walking because it stabilizes the leg to accept the transferred weight from the opposite leg when you are in stance phase of gait.  If the knee is unable to go fully straight while stepping onto it you have difficulty swinging the other leg through to take another step.

This happens because of the swelling (and possibly pain too) within the joint.  A neural reflex is set up by distension of the joint structures.  It passes through the spinal cord and back to inhibit the quadriceps.  It is then difficult to contract them at the right time and with sufficient speed during the gait cycle.  Hence, unsafe walking and difficulty going up and down stairs, for example.  You may notice immediate deterioration of your ability to contract the quadriceps following injury with a joint effusion.

To regain quadriceps function and hence to restore normal and safe walking you must control the swelling (see earlier post on this topic), avoid increasing it by careful activity modification and do specific exercises to regain normal quadriceps function.  Physical therapists will instruct you in specific neuromuscular reeducation exercises to restore the quadriceps recruitment pattern.  Such exercises may include seated quad sets, straight leg raises or short arc quad recruitment.  These may be done with neuromuscular electrical stimulation (not TENS – that’s for pain and totally different type of current form) to facilitate recruitment of the muscle.  In addition, you will be given terminal knee extension exercises in standing such as straightening the knee against a wall with a towel roll behind your knee against the wall or fully extending your knee against tension created by an elastic sports cord.

So, controlling swelling in a joint is necessary to regain function of the muscles moving that joint.  This process is used in all knee injuries that result in joint effusions as well as in all postoperative rehabilitation, for example, following ACL reconstruction, meniscus repairs and debridement as well as total knee replacements.

What have you found helpful in the past?

What worked for you?  What didn’t?

Post your comments here so other people can learn from your experiences.  We would love to here from you.

3 thoughts on “Swelling and Knee Function

  1. Good information for all to understand and especially trying to pass it on to patients with TKR surgery in terms of easy understanding for patients who get frustrated with lack of extension or strength in their quads. A mixture of the above will help achieve those goals along with patients understanding the importance of controlling their swelling due to overactivity or the lack of. Everyone has to experiment what works best for them.

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  2. Thank you for reminding me how important my leg extension is. After my knee replacement, and after my PT was completed, I still work on strengthening my quads and straightening my leg. It’s good to hear this though so I don’t get lazy! Thank you!

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