ACL Tears-That Terrible Pop You Felt in Your Knee

We hear it all the time, "I felt this pop in my knee."  It may occur skiing, playing basketball, soccer, or even while at work.  Rest assured that when you feel it, you will know something happened in your knee.  The "pop" sensation is often followed by swelling, instability, and a trip to see me!

So what is the ACL (Anterior Cruciate Ligament)?  The ACL is one of two ligaments that sit the in center of our knee in a crossing pattern. (The name "cruciate" comes from the Latin cruci or crux meaning cross.)  The ACL is responsible for what is called anterior/posterior stability or you knee shifting forwards and backwards, as well as some rotational movements.  Often individuals tear the ligament with a non-contact injury like twisting their knee, pivoting, or shifting with their leg planted.  All of these movements cause the femur bone and tibia bone, where the ACL attaches, to shift and put stress on the ligament.  If the stress becomes too great the ligament will give resulting in an ACL tear.

Usually after the tear, one will experience a period of reduced range of motion, swelling, and instability.  This is often when the patient is seen for their first in office appointment. X-ray studies are almost always negative in ACL tears. Physical exam findings will show swelling and positive testing for laxity or looseness in the knee. Often, patients are sent for MRI scans which will confirm the diagnosis of an ACL tear, and rule out an other injury to the meniscus or other ligaments.

Most patients will begin a short course of physical therapy to regain range of motion. It is always recommended that patients have a return of their range of motion and a reduction of their swelling before under going ACL reconstructive surgery.  Motion before surgery always dictates motion after surgery, so it is much easier to rehab a knee if the motion was full before surgery.   At this point a lot of individuals are feeling significantly better, their swelling is down and motion is back; they are thinking--"Why am I having surgery?"  Which is not  a terrible question.  So let me answer it.

The ACL stabilizes the knee from shifting whether that be big noticeable shifts or small more micro-shifting. Each time the knee shifts there is potential for injury or tearing to the meniscus, and damage to the articular cartilage on the ends of the bones.  The more times the knee shifts the more damage or at least risk for damage a patient accumulates.

Ok, now you have decided to have surgery right?  Well the first decision you have to make is what type of tissue to use to reconstruct the ACL.  This is a bit of a hot topic but I will break it down for you with the speech I usually give patients.  Autograft (your own tissue) vs Allograft (cadaver) has been debated and honestly if you ever have a chance to use your own tissue you probably should.  There are always disease transmission risks with any cadaver tissue--they are very small! However if you are that 1 in Million person you will not care what the odds were.  Also there are multiple studies that show there is an increased risk of graft failure in allografts compared with autografts.  Here are a few example studies:  1.  Autograft vs Allograft ACL Reconstructions: A Prospective, Randomized Clinical Study with Minimum 10 Year Follow-up         2.  Prospective Comparative Study of ACL Reconstruction Between Using Hamstring Autograft and Soft Tissue Allograft

There are 3 types of autografts most surgeons choose from: patella tendon, hamstring, and quadriceps.  All have pros and cons and in a good surgeon's hands would be fine choices for your graft.  I will just give you a run down of each.  Patella tendon, also know as a BTB graft has been around the longest and is considered the gold standard we compare everything else too.  It takes a small portion of the patella tendon from the front of the knee and usually also a piece of bone from both the patella and the tibia "(shin bone) to form the graft.  This is a strong graft similar to a native ACL however some patients especially those older than teens tend to get some knee cap pain from this graft.  Hamstring tendon grafts have also been around a long time and  take a small piece of the hamstring from the back of the thigh from it's attachment on the shin bone.  This does not involve removing any bone, but does not act as much like a native ACL and some think it can stretch a bit.  A quadriceps tendon graft removes a small portion of the central quadriceps tendon with or without a small piece of the patella bone.  The quad graft is a newer graft and fewer surgeons are using it on a regular basis, it does have similar properties to a native ACL.

Courtesy of Arthrex Inc

Surgery involves removing the old torn ACL and drilling bone tunnels in the tibia and femur.  These
tunnels will allow for the graft to be pulled into the knee and secured with metal buttons or screws that come in a variety or materials.  Rehab protocols will vary by surgeon, some will place patients in post operative braces and on crutches, some will begin physical therapy with in days or weeks.  The most important thing to remember when it comes to rehabilitation is that it will take 9-12 months for the graft to mature and heal.  That means a slow return to activities!  I cannot stress that enough.  I could do a whole separate blog on ACL rehab. If you take nothing else from this remember that everyone will heal at a different rate and it is important to listen to your body and doctor.  Often a return to full athletic sport may take up to one year depending on the sport and athlete.  

    

Inject Or Not To Inject? That's the Question...

We have all been there before, that pain that will not go away.  It seems to wake you up at night, hurts when you take that first step, maybe even seems to catch your breath.  That's when you call me, or at least someone like me. (Or if your my family member or friend, you text in a panic :)  It is human nature to want a pill, cream, or patch to take the hurt away.  None of us are immune, and if you are in my family you tend to get hurt a little more often!

Many times I have seen a patients in a similar situation and they too want the aching or stabbing to stop in their given joint.  The topic of steroid injections comes up often in this scenario. Where steroid injections can be helpful in reducing pain, they should also be approached as an infrequent or one time treatment.  Steroids are not a benign medication and should not be treated like they are a Flintstones vitamin.  Unfortunately, I do see some people who have had many injections over the course of their lives into the same area.  This is not necessarily the best practice when it comes to our joints.

Using my uncle as an example: he had terrible arthritis of his knees.  He had limped around for years in pain, failed injections. therapy, and knee scopes.  If he had chosen to get steroid injections every 3-6 months in his knees for years he would have only treated his symptoms.  Instead he treated the problem and got both knees replaced and is very happy.  Having one or two steroid injections get you through an injury maybe helpful. However, for someone with a chronic arthritic problem, continued injections do not addressing their underlying problems.

Also, studies have shown that repeated steroid injections to the same area in a short amount of time can be destructive to the tissues.  Detrimental Effect of Repeated and Single Subacromial Corticosteroid Injections on the Intact and Injured Rotator Cuff, in the American Journal of Sports Medicine tests one and three steroid injections in the shoulders of rats.  The researchers had rats with both non injured shoulders and some with rotator cuff tears. Then they either gave them saline injections, one steroid injection, or three steroid injections over 3 weeks. The rotator cuffs were then tested for failure.  The single injection rats took 17% less load to cause the cuffs to fail then the saline group, and the triple injection took 32% less load to fail.1  Also, they found the bone volume was decreased in the triple injection group and the stiffness of the cuff tissue decreased by 50% in the triple injection group.1   What does it all mean?  Multiple injections can cause damage to the tissues within the joint. 
  
I wish I could tell you that everything that made you feel better was good for you.  But that just in not true, or responsible.  Steroid injections have a great place in orthopedics and medicine but often get overused because people want a quick fix.  Remember to look for a solution to the problem if possible.  As with everything there are always gray areas and it is best to discuss this with your provider individually.  


Sources:

1. Maman, E., Pritsch, T., & Morag, G. et al (2015, July 27). Detrimental Effect of Repeated and Single Subacromial Corticosteroid Injections on the Intact of Injured Rotator Cuff: A Biomechanical and Imaging Study in Rats. The American Journal of Sports Medicine, 44(1), 177-182.