Potential Causes of Knee Instability

Knee instability isn’t a minor concern. You don’t know when it might happen next, and it can easily lead to a fall that could result in a serious injury. 

Our board-certified orthopedic surgeon and musculoskeletal specialist physicians at Urgently Ortho in Scottsdale, Arizona, can correctly diagnose the cause of your knee instability and develop a treatment plan. 

Ligament injuries and patellar injuries are two common reasons for knee instability.  

Ligament Injuries

Knee instability is often caused by ligament injuries. You have four ligaments at the knee joint. 

Ligament injuries have different degrees of severity. They require the expertise of orthopedic specialists who develop treatment plans based on the type and severity of the injury.

If the diagnosis is a tear in a ligament, the injury could range from a small tear to a complete tear, which means the ligament is severed. Partial or complete tears to any of the knee ligaments usually cause knee instability as well as pain. 

If the tear is small, conservative treatments may work well. If the tear is major or the ligament is completely severed, you will almost always need surgery because of the instability it creates.  

If you’ve only stretched or sprained a ligament, you’ve damaged the fibers due to overuse or sudden trauma, and you may or may not have instability. If it’s a minor sprain, you may simply need to use the RICE method: rest, ice, compression, and elevation. If it’s more severe, you may need a cortisone injection and/or a knee brace and other treatment 

ACL tears

The knee injury you may hear about the most is tears of the ACL, or anterior cruciate ligament. It’s in the middle of your knee and stops the shin bone from slipping in front of your thigh bone

A significant ACL tear or severed ACL means your sports season is over. You have severe pain and swelling at the knee and may hear a pop. It might have happened when you landed wrong from a jump or twisted your knee awkwardly when pivoting on the racquetball court. You can’t bear weight on it, and you have instability when the inflammation calms down. Surgery to reconstruct the ACL is almost always recommended unless age or medical conditions contraindicate it. 

PCL tear

You can feel your posterior cruciate ligament, or PCL, the thick rope of tissue across the back of your knee, joining your shin to your thigh and keeping your knee stable. A tear may occur when the front of your shinbone sustains a traumatic hit. Your knee is likely to feel unstable. 

MCL tear 

Your MCL, or medial collateral ligament, is a thick tissue on the inside of your knee that keeps the joint from moving inward and buckling. If it’s torn, the joint will become looser. 

LCL tear 

Your lateral collateral ligament helps hold your knee in place by preventing your knee from making too much side-to-side movement. When it’s torn, the knee can give way when it moves inward; the ligament no longer can hold the joint in place. 

Patellar Instability

Your ligaments and tendons help keep your kneecap (patella) in place. If they’re loosened or torn by a traumatic injury or from wear and tear, you can develop knee instability. Your genetics via your bone structure may also contribute to patellar instability. 

Patellar tendon tear 

The patellar tendon joins your quadricep muscle to your shin bone at the base of the kneecap. It’s part of the mechanism that allows your knee to straighten. A tear in this tendon is often caused while playing sports when landing awkwardly and straightening the leg with force or from wear and tear of the tendon over time.  

Partial dislocation

A damaged ligament that’s become loosened can result in a partial knee dislocation, also called subluxation, causing knee instability. 

Call Urgent Ortho for an appointment if you have knee instability and for all of your orthopedic needs. 

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