The “Trick Knee” – Not Magical, Just Unstable – Boyd W. Haynes III, MD

Orthopaedic & Spine Center

Ever heard someone mention that they have a “trick knee” and wondered what they meant?  The term “trick knee” is used to describe an unstable knee that can buckle or give-way without warning.  This can be very disconcerting when it happens, even causing a person to fall to the ground when their knee buckles.  When this occurs, the individual may feel a great deal of pain or may feel only a mild discomfort, depending on the underlying cause of the knee instability.  After recovering from the scare of their knee buckling, they usually go about their business and forget about their knee until the next time it buckles under them.

While the trick knee may be painful, it tends not to be so bothersome that the owner runs immediately to their Orthopaedic Specialist to get the problem fixed.  Hence, the unreliability of the knee becomes a “trick” (replicated over and over) in the long-term.  Folks will continue to deal with the instability and unpredictability of how their knee will behave, rather than going to the doctor.  Eventually, however, there will come a time that the knee will give-way and the person will scare or injure themselves enough by falling to get the problem addressed.  That is when I get involved.

“Trick knee” is really a catch-all term for those physiological conditions that make the knee unstable, such as a torn Anterior Cruciate Ligament (ACL), a torn meniscus or patellar (kneecap) instability.   The treatment I recommend will depend on the diagnosis I make, for these differing issues will need specific treatment regimens.

ACL Tears

Most often, the patients I see have a trick knee caused by an ACL tear.  This usually occurs when the ACL is injured and does not heal properly, causing significant knee instability.  Patients will learn how to compensate for this knee instability, even learning how to continue to play sports without pivoting off of the affected knee.  My job is to figure out if the tear is new or older in nature and to discuss with the patient any therapies that may have been used for prior treatment.  I will also ask the patient about their activity level and goals for the future, based on their age.

Older patients who do not wish to participate in vigorous activities may do just fine with physical therapy, bracing, icing and taking anti-inflammatory medications.  Treatment goals will be to strengthen the quadriceps and the other muscles that support and protect the knee, while reducing inflammation and pain.  However, if conservative treatment does not afford pain relief and increased stability, surgery may need to be considered

Younger patients who want to live an active lifestyle are almost always candidates for surgery to repair the torn ACL.  Done as an outpatient arthroscopic procedure, I repair or replace the torn ACL with an Allograft (material from a cadaver).  The Allograft acts as scaffolding upon which new tissue can grow.  This procedure is very successful for most of my patients and they usually are able to return to sports or the activities they enjoy after surgery. 

Recovery time depends on age, general health/condition and patient motivation, but most patients can return to full activity, including sports, in 4 months.  Patients will walk on crutches for a few days, but start rehabilitation of the knee shortly after surgery, to increase strength and range of motion.  You may return to driving once you are off narcotics and are able to be safely behind the wheel.  Most return to work within a week. 

Meniscal Tears

The meniscus is composed of cartilage that acts as a cushion in the knee joint.  There are two menisci on both sides of the knee joint.  When a meniscus tears, knee pain and instability can result.  Because there is a poor blood supply to the menisci, they do not heal well on their own.  Menisci do not need a traumatic event to tear and they can erode just from regular use and age.

Conservative treatment predicates rest, icing, anti-inflammatory medications, bracing and physical therapy.  Treatment goals are to reduce pain and inflammation while building better knee and leg musculature to support the knee.  Surgical treatment is done on an outpatient basis and involves arthroscopically accessing the knee joint and removing the pieces of torn meniscus and “cleaning –up” any tissue debris within the joint.  Recovery times depend on the individual, but patients are usually walking and back to all activities in a few weeks.  Return to work and driving both occur in less than a week.

Patellar (kneecap) Instability

The Patella (kneecap) is connected to muscles at the top and bottom which cause the kneecap to glide over the knee joint as the knee is bent and straightened.  There is a track, called the femoral groove, in which the patella normally moves, that helps to keep it in proper alignment.  Sometimes this groove is too shallow and the kneecap can become off-track or even completely dislocated.  This can cause pain and instability of the knee.

Conservative treatment will involve reduction or putting the kneecap back in place.  I do that in the office and it usually just involves me putting pressure on the kneecap to get it back into proper position.  I usually will prescribe bracing to keep the kneecap in place while we build strength and reduce pain and inflammation (a common theme in this article).  Physical therapy to start and then a regular exercise program will help to accomplish the goals of building strength and helping the knee to stabilize. Recovery time is usually 1-3 months.

However, if the kneecap becomes completely dislocated, the backside of it and the femur (thighbone) can become damaged, requiring surgical repair, done arthroscopically and as an outpatient procedure.  I may also need to tighten or release certain tendons or ligaments that are pulling the kneecap off-track.  The surgery is quite helpful for this condition when it does not respond to conservative treatment.  Recovery time is variable depending the treatment necessary but is usually between 6 to 12 weeks.  Return to work and driving are similar to ACL surgery.

Now that you know the underlying conditions that cause a “trick knee”, it is easy to understand that there is nothing magical or fun about its unreliability.  Do yourself a favor and have it examined by a fellowship-trained Orthopaedist who can recommend a solution to make your trick knee disappear for good. 

Boyd W. Haynes, III, MD is a fellowship-trained and board-certified Orthopaedic Specialist with Orthopaedic & Spine Center in Newport News, Virginia.  Named a “Top Doc for 2012 & 2013” by a survey of Hampton Roads Physicians, Dr. Haynes’ practice is focused primarily on sports-related injuries and disorders, and on total and partial joint replacements of the hip and knee, including the MAKOplasty surgical system. Call 757-596-1900 to make an appointment. Visit www.osc-ortho.com to learn more about OSC and Dr. Haynes.