ACL Injuries & Treatment

Watch the video on ACL Repairs & Recovery from WCNY

What is the ACL?  

ACL stands for Anterior Cruciate Ligament of the knee and it is one of four major ligaments in the knee.  The knee is the largest and most complex joint in your body.  It depends on four primary ligaments as well as multiple muscles, tendons and secondary ligaments to function properly.  There are two ligaments on the sides of the knee: the medial collateral ligament (MCL) on the “inner” medial side and the lateral collateral ligament (LCL) on the “outer” side of the knee.  These two are crossed (cruciate means “cross”)  ligaments in the center of the knee, the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL).

Why is the ACL so Important?

The ACL connects the anterior (front) part of the tibia (shin bone) to the posterior (back) part of the femur (thigh bone).  It prevents the tibia from sliding forward on the femur but more importantly when cutting, pivoting, or turning to the opposite side, it prevents that knee from giving out in a twisting fashion, which is very important for cutting and pivoting sports such as soccer, basketball, football, etc. This is the reason the ACL is so important in these types of sports.  When it is torn, many times, athletes in these sports cannot return to play without their knee continuously giving way on them.  Each time the knee gives way it can cause further damage to the cartilage on the end of the bone (the articular cartilage) or more commonly the meniscus cartilage, which is the “shock absorber” cartilage in the knee that helps protect the articular cartilage.  If the articular cartilage wears down, that is what arthritis is.

How is the ACL Injured?

One of the common ways for the ACL to be injured is by a direct blow to the knee, which commonly happens in football.  In this case, the knee is forced into an abnormal position that results in the tearing of one or more knee ligaments.  However, by far, most ACL tears actually happen without contact between the knee and another object.  Such noncontact injuries happen when the running, jumping, cutting athlete changes direction or hyperextends their knee when landing from a jump.  These movements are common to all agility sports.

What are the signs of an ACL Tear?

In many cases, when the ACL is torn, the athlete/injured person will feel the knee give way with an audible “pop.” The injury is usually associated with a moderate amount of pain and continued activity is usually not possible. Over the next several hours, the knee becomes very swollen and walking becomes difficult.  The swelling and pain usually increase over the first two days and then begins to gradually subside over a period of several weeks.

How is an ACL Tear Diagnosed?

Discomfort after an ACL tear is usually severe enough that the injured person will seek medical attention.  The physician will examine the knee, and, in most cases, be able to identify which ligaments are injured.  However, there are may also be injuries to the joint surface or other areas that are more difficult to diagnose.  At times, swelling may make it difficult to diagnose a tear.  This will necessitate the use of an MRI scan or arthroscope to ensure than accurate diagnosis is made.

Will I need Surgery?

The most frequent question after an ACL injury is “Will I need surgery?”  The answer varies from person to person.  Many factors must be considered by the patient and the surgeon when determining the appropriate treatment.  These factors include the activity level and expectations of the patient, the presence of associated injuries (cartilage tears, etc.) and the amount of abnormal knee laxity.  A young patient with an ACL tear and knee laxity who wants to return to competitive sports is more likely to require surgery for a satisfactory outcome.  The older patient who can return to limited activity is less likely to require surgical stabilization.  In either scenario, rehabilitation of the knee begins with exercises to help decrease the swelling and pain as well as restore full range of motion through physical therapy and/or athletic training services. This is followed by strengthening exercises for the muscles around the knee.  Return to sports with or without a brace is allowed only after range of motion, leg strength, balance, and coordination have returned to near normal.

Preparation of a new ACL in the operating room.

How are ACL Tears Treated Surgically?

Once the ACL tears, it is almost never able to be repaired.  The ligament almost “shreds like a torn rope” and is usually not repairable unless it is torn directly off of the bone, but that is very rare.  In the past, when repairs were being attempted more commonly, the failure rates were very high, so a reconstruction (remake a new ligament from another piece of tissue) procedure was developed.  During a reconstruction, a surgeon will take a piece of tissue (a “graft”) from another portion of the patient’s body or a donated piece of tissue from a cadaver and prepare it to fit inside the injured knee so that it is roughly the same size as the original ligament.  Once that is done, the surgeon drills tunnels in the tibia (shin bone) and femur (thigh bone) in order to feed the new ligament into place in the correct location in the center of the knee.  There are then various forms of fixation methods where the reconstructed ligament is secured into position until it can heal, grow new blood vessels and turn into a new ligament over the course of 2-6 months.  The most common sources of grafts utilize in order of most to least common are:  1) Bone-Patellar Tendon-Bone (BTB), 2) Hamstring, 3) Quadriceps Tendon, 4) Cadaver Tendon.  So, the surgery is not an ACL repair the vast, vast majority of the time, but it is an ACL RECONSTRUCTION.  It is less important WHAT graft is used and more important WHERE the surgeon places the graft and what the surgeon feels most comfortable utilizing in his or her hands.

A New, Innovative Way to Treat ACL Injuries

Dr. Pietropaoli is involved in the emerging field of regenerative medicine, continuing to introduce our patients to new biologic and regenerative treatments as options other than surgery or in addition to surgery to aid in faster recovery.  For the ACL reconstruction procedure he uses a graft from the patient called bone-patellar tendon-bone. The new ACL is made from a strip of the patient’s own knee cap tendon, called the patellar tendon, along with an attached piece of bone from the knee cap and an attached piece of bone from the shin bone (tibia).  Dr. Pietropaoli works with the several different methods of ACL reconstruction: most commonly bone-patellar tendon-bone, but also quadriceps tendon, hamstring tendons or even donated cadaver allograft tissue when necessary. His go-to is the bone-patellar tendon-bone, which he believes is by far the most commonly used graft for professional athletes. After harvesting the bone-patellar tendon-bone graft for the reconstruction during the surgery, Dr. Pietropaoli goes inside the knee using an arthroscope. He threads a small camera into the knee that projects magnified video to a large flat screen monitor in the operating suite.

The new aspect to this procedure was an addition to the biologics. The biologics were platelet rich plasma and bone marrow aspirate, or stem cells. These are used to speed up the recovery and enhance the overall outcome.  Dr. Pietropaoli has performed hundreds of PRP injections, mostly in the office but also in the operating room.  Dr. Pietropaoli is the first surgeon in central New York utilizing bone marrow concentrate stem cells.  “It takes six months to a year to get back to playing sports on the field, so the goal with the PRP and stem cells is to see if we can get people back quicker and with less pain and stronger,” Dr. Pietropaoli says. “The goal of the biologics is to enhance and improve the procedure we already do.”  For the PRP portion of the procedure, blood is drawn from the patient’s arm. The blood is sterilely placed into a machine that can separate out the platelets, stem cells, white blood cells and plasma fluid from the whole blood. The platelets are concentrated into a much smaller volume to be injected into the affected area.  Platelets contain growth factors that are released into the area to aid and speed up the healing process. The PRP aids in recruiting other cells to help the body heal faster.

Stem cells are cells that have not differentiated into any type of tissue yet. They can turn into muscles, bones, cartilage, hair or skin depending on the location and environment where injected. It’s not 100 percent yet, but scientists are coming up with promising protocols, according to Dr. Pietropaoli.  Dr. Pietropaoli has used PRP to treat many ailments, injecting it into the tendon or muscle that has degenerated or is injured or not healing. Once the PRP is injected, the growth factors are released. This stimulates new blood vessels and cells to come into the area, improving and speeding up the healing process.  It can sometimes take up to three separate injections spaced six to eight weeks apart to get the full affect with PRP. With the addition of the new bone marrow procedure, the combination allows for even better and faster healing, possibly eliminating the need for injections.

What happens after Surgery?

Rehabilitation of the knee after ACL reconstruction requires time and hard work.  Time off from work varies depending on job type. Desk job employees can return in one or two weeks, whereas construction workers usually are not able to return to work for approximately three to six months.  The same is true for athletes where return to full athletics can take 6-12 months to fully recover.
The rate of rehabilitation may take even longer, depending on the specific requirements of the individual’s sport/activity and rate of recovery.  The overall success rate for ACL surgery is very good.  Many studies have shown that over 90% of patients are able to return to sports or workplace activities without any symptoms of knee instability.  Although some patients do complain of stiffness and pain after surgery, these problems have been minimized by current surgical techniques and aggressive rehabilitation.

Who is at Risk?

Interestingly, the anterior cruciate ligament is about five to eight times more commonly torn in females vs. males.  Although males are certainly at risk, it has been scientifically proven that ACL tears are 5 to 10 times more common in women than men.  Some of the reason for this is biological, as women have female hormones that make their ligaments looser and women have a wider pelvis so that they can have babies. That increases “the Q–angle” of their knees that makes them more knock kneed, which puts a lot more stress on ACLs.  Women also tend to run, jump and cut in a more upright position and don’t naturally bend their knees in activities, whereas bending the knee in jumping or running is safer and can be taught.



Victory Sports Medicine & Orthopedics includes strength and conditioning training services, where athletes are taught preventive measures.  The prevention program generates performance enhancement, such as jumping higher, running faster and core strengthening.  Dr. Pietropaoli believes there is no perfect surgery, so any prevention an athlete or any person can employ will serve them well.  Victory Sports Medicine & Orthopedics’ ACL injury prevention program (Sportsmetrics) teaches male and female athletes how to run, cut, jump and land correctly as well as other strategies. It also strengthens and teaches proper mechanics. This is a six-week, intense program that is three days a week and has been scientifically proven to cut the risk of serious knee injuries by 50 to 75 percent.  “We have also found that by the end of this rigorous program, the athlete’s performance is increased as well,” according to Dr. Pietropaoli. “We even had a basketball player who could not dunk prior to the program be able to dunk a basketball in games after the program.”


Watch the video of Dr. Marc Pietropaoli  discussing knee arthroscopy surgery and ACL injuries & repairs.

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References: American Orthopedic Society for Sports Medicine (2006).