Several years ago, I saw a middle aged patient for a second opinion regarding his knee. Another orthopedist told him that he needed surgery to replace a torn anterior cruciate ligament (ACL). I examined his knee –everything appeared normal. There was no laxity or looseness. What sort of problems are you having with it, I inquired? “None,” he replied.

“Then why do you want surgery?” I responded.

“Because it is torn”.  The other doctor warned him that he might have future problems.

In a situation like this, I always wonder who is loonier –doctor or patient. Not everyone who tears an ACL needs reconstructive surgery, but more about this later.

The cruciate ligaments –anterior and posterior – are important central ligaments within the knee joint ( see diagram below). Like a cruciate screw head, they are in the center of the knee and they add stability. The ACL prevents the tibia (leg bone) from translating forward on the femur (thigh bone). The ends of these two bones form the knee joint. The PCL prevents backward instability. Also, the ACL restrains abnormal knee rotation.

The ACL is more commonly injured. The trauma is usually substantial-not from a minor sprain. Tears can occur from pivoting on one foot while running, decelerating, changing direction, or after landing from a jump. Blunt trauma like a clip in a football game while the victum’s foot is planted can do it as well. Or a ski injury—a twist to the knee or a fall– as the ski bindings fail to release.

A pop is commonly felt and may be heard. Swelling gradually occurs and the knee can blow up. If the knee is drained with a needle, blood is removed. This combination of a pop and bleeding tells me that the knee injury is more serious than a slight sprain.

On exam, we may find a positive drawer sign. The tibia displaces forward just like a dresser drawer is pulled out.

X-rays need to be performed to rule out a fracture and sometimes a chip fracture can be diagnosed. The ligament is not visualized on a routine x-ray and therefore, the next step is an MRI to make the diagnosis. We need to learn if the cruciate is indeed torn or if there is an associated meniscus tear. And,  if the ACL is torn: to what extent and where?

“us” above-middle – is the ACL : from an early 20th Century German Textbook. 

If it is torn right off of the bone in children, it is frequently directly repairable.Surgery should be performed fairly soon (it is no emergency, though). Frequently, when the injury occurs  lower down on the ligament at the tibial attachment, a sizable chunk of bone is broken off and this should be –and can be fairly easily – surgically repaired. This ligament fracture  is more common in children, but can be seen in teens or adults.

The most common problem is an ACL tear through the mid-portion of the ligament. Here the blood supply is frequently skimpy. Think of the ACL circulation as an hour glass. It is better at the top and bottom, but thin in the middle. Thus, repairing the ligament is this level will commonly not succeed. Most ACL tears are in the mid portion of the ligament and not repairable. I do not recommend attempting to repair the ligament if it is torn here. Moreover, the arthroscopic appearance of the torn ligament is that of a rag mop, and it would be like trying to stitch together scrambled eggs—an exercise in futility!

So, given that most people tear the ACL in an area that is unrepairable—what to do? The ACL reconstruction is a great operation. Performed mainly arthroscopically, a graft is inserted through a tunnel in the tibia into the knee joint and secured with a screw into the femur –thus replacing the torn and functionless ligament. But the operation is not without potential risks-infection, stiffness, graft failure, etc. and the recuperation is relatively lengthy. Athletes who have this operation are out for the remainder of the season.

Who requires this operation? Certainly athletes involved in high school, college, or professional sports or athletes who have to cut, pivot, or jump. Or, older patients who participate in intense sports. Also, people who have a very prominent drawer sign with pain or people who later develop a trick knee that buckles and gives way— at risk for producing a new injury.

So getting back to our friend in the first paragraph, should you have the ACL reconstruction because—like Mount Everest—it is there ? ( the surgery is available ) Or are there alternatives. In this respect—and again this is my opinion – I tend to be more conservative than some of my colleagues.

Not everyone requires the operation. And, this is not just my opinion, but a stated fact in the orthopaedic literature. In a study in 1993 involving almost 300 patients, 62 were able to function satisfactorily without an ACL.

This has clearly been my experience with my patients. Many patients with an ACL tear have stable knees as other surrounding structures of the knee  may also provide stability. If these patients have reasonably stable knees and, like the man above, few or no symptoms, I do not encourage reconstructive surgery. Instead, I rehab their knee with an intense exercise and strengthening program –emphasizing the hamstring muscles and a custom made brace for sports that stabilizes the knee. Most patients consider this brace to be comfortable and it worn by many athletes. I have had many patients who have returned to various sports and skiing after this treatment and most have done very well. For example, an attorney friend that I treated about twenty years ago, has had no long term trouble and has long since returned to skiing black diamond trails while wearing his brace.

After an ACL injury is diagnosed by an MRI, I do recommend standard arthroscopic surgery to evaluate the knee. Basic arthroscopy is a relatively minor procedure and the recovery is quick. I want to see the extent of the tear or if the ACL is repairable. Sometimes the MRI is incorrect and the tear is not as bad as reported. Sometimes there is an associated meniscal tear which I treat. I also believe that washing our the knee and removing blood clots and the scarred damaged rag mop of a ligament relieves pain and hastens recovery and rehab. This has been my overwhelming experience. If the ACL is completely torn and un-repairable, it is of absolutely no use. A wad of scar tissue forms-we call it the ACL stump- and it can probably produce some knee discomfort. Therefore, I remove the scarred stump as it is functionless.

Next, I sent my patients for PT to rehab their knee. Most feel better after this minor operation and are walking normally within two weeks. A brace is custom made and eventually they return to sports and, hopefully, a normal lifestyle. They are watched carefully. If their knee loosens up; if they re-injure their knee; if they simply do not do well –if their knee still goes out or buckles, I recommend a reconstruction. One valid criteria –for me – is how do they do during normal, daily activity. If a patient can, say, ski successfully while wearing a brace, but if his or her knee constantly buckles while going up steps, this is unacceptable. One realistically cannot constantly wear a brace. So, this patient should consider an ACL reconstruction.

Again, 60-70 % of these patients can avoid this operation. If someone is middle aged, a weekend athlete-golf or doubles tennis, etc. – or has a sedentary job, it is certainly reasonable to first try the conservative approach. Especially if their knee is fairly stable.

What patients do I recommend have a reconstruction early on ? A young athlete. Perhaps someone in their late teens or in their 20’s – 30’s who plays organized contact sports, skis, or plays competitive tennis. Someone who has 60 years ahead of them probably should have the surgery. Or, a policeman, fireman, or construction worker who may not be able to wear a brace and who may perhaps be in harm’s way if they cannot rely on their knee function.

Thus, every individual case needs to have treatment recommendations tailored to their medical exam findings and their future requirements.

Why do some doctors believe that everyone (outside of the elderly population) should have an ACL reconstruction? There is a feeling that re-injuries will occur and eventually lead to the development of osteoarthritis of the knee. While, this view may be valid, I do not believe that this is always the case. Many of my patients have done well with rehab/bracing and have not re-injured their knees. Nor, have follow-up x-rays years later demonstrated arthritis. Moreover, whenever I do a total knee replacement on someone –with severe arthritis: obviously–I almost always find an intact ACL. So, if isolated ACL tears always lead to osteoarthritis, why don’t more people undergoing total knee replacements have absent ACL’s ? Finally, some recent studies have shown that ACL reconstructive surgery does not necessarily prevent osteoarthritis in the long term.

Again, the above opinions are mine and do reflect my bias, albeit based on thirty years of experience in treating these injuries. Medicine can be in art and sometimes there is no right or wrong opinion.

But if you injure your ACL at least be informed about your condition and your options. Possibly seek a second opinion before rushing into reconstructive surgery. And remember, an ACL reconstruction is not an emergency operation in most cases. In fact, many orthopedists recommend delaying the procedure for a few weeks after an injury so that the knee swelling can decrease and the knee can somewhat recover from the insult. So, in most cases, there is no rush.Please note: these articles are for general information. They are not intended to serve as medical advice or treatment for a specific problem. Diagnosis and treatment of a problem can only be accomplished in person by a qualified physician.