ACL tears

Sunday, April 29, 2012

The knee is the largest joint in the body but it is held together by a ligament that is only an inch and a half long and less than a half inch wide. There is a lot expected of the anterior cruciate ligament (ACL) but the engineer who designed the knee probably didn’t expect 240 pound running backs to cut on a dime or 6 ½ foot power forwards to jump through the roof. About 100,000 people tear their ACLs every year but few do it on national television in the middle of the NBA playoffs. Every Chicago Bull fan held their breath and then sighed sadly as Derrick Rose, the league’s MVP, was taken off the court with a damaged knee that will take an operation and months of physical therapy to heal.

The knee is a hinge joint and is held together by four ligaments. The medical collateral and lateral collateral ligaments keep the knee from swinging side to side while the ACL and posterior cruciate prevent it from sliding front and back. The quads and hamstrings also provide support and together with the ligaments, allow the body to walk, jump, and squat and do all the things the legs are supposed to do. But the knee is vulnerable to injury since there is no bony protection for stability and it depends on those ligaments to keep it stable form the torque applied especially when pivoting and cutting. All of that is plenty to expect, especially from an ACL that has an area of only 2 square inches.

Damage to the knee can happen with no contact, usually from changing direction or landing from a jump when the knee is extended and the player tries to pivot at the same time. It can also happen when a player gets hit, but that is a high impact injury and it can also cause damage to the MCL and the medical meniscus or cartilage. This is the terrible triad of O’Donoghue, named after the Oklahoma orthopedic surgeon who repaired blown knees before the discovery of the arthroscope.

The diagnosis is relatively easy. The player can often hear of feel the ligament pop and there is intense pain. In sports, the trainer often rushes onto the court to examine the knee before it fills with blood and becomes so painful that the exam is fruitless. If the initial injury is ignored, the knee will continue to swell, give way and become increasing painful. For most athletes, the next diagnostic step is an MRI, to look at the anatomy, find the injury and sort out a treatment plan. But before any surgery is considered, one of the great advances in physical therapy has been the concept of pre-hab. When the knee becomes inflamed, the quads and hamstrings shut down and start to weaken. Pre-hap works on strengthening those muscles before the operation because there will be more muscle loss after the operation.

In athletes, the ACL has to be repaired to allow them to return to competition, otherwise an unstable knee will continue to buckle when placed under any stress. There are a variety of ways to fix the ACL but often a graft is done to replace the ligament by crafting a ‘new’ one one from another ligament from the hamstring or patellar tendons. In some cases, allografts, or pieces of tendon from a cadaver are used to replace the damaged ACL. Post op is when the patient has to really work at getting better and rehabbing the knee joint. The first few weeks are devoted to getting range of motion back to the knee while teaching the quadriceps muscle how to work again. Then there are the months of regaining strength and agility. No matter how technically good the surgeon, the success of the operation depends on the devotion and dedication of the patient to the almost year-long battle to restore the knee to where it was before the injury.

An ACL injury to an elite athlete is a disaster. It costs them a year of their competitive life with no guarantee that the knee will be physically the same. The next big challenge is mental and emotional. Will the athlete trust the knee enough to perform without the split second hesitation that is the difference between making a play and being a half step late. For Derrick Rose, his teammates and his fans, the answer to that challenge will be a year away and will depend upon a piece of tissue 1½ inches long and a ½ wide.

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