Some people recall hearing a "pop." Others remember feeling the affected knee give out. Regardless of their recollections, whatever they were doing generally came to a sudden stop.
Each year, knee injuries sideline hundreds of thousands of athletes and non-athletes. Many are almost as good as new following treatment and rehabilitation. Top athletes overcoming knee injuries include Minnesota Vikings running back Adrian Peterson and Washington Redskins quarterback Robert Griffin III.
While there are different types of knee injuries, the ones affecting four fibrous bands of ligaments holding the kneecap (patella), shinbone (tibia) and thigh bone (femur) together are particularly troublesome.
When you hear about an athlete being out for the season with a knee injury, the announcer is often talking about an injury of the anterior cruciate ligament, or ACL. It often occurs when the knee is twisted out of its normal position.
And, that is the ligament you don't want injured. For starters, it is the one knee ligament that cannot heal on its own. In addition, it can't be stitched back together. Women are more likely to suffer an ACL injury than men, and ACL injuries are associated with team sports like football, volleyball and soccer.
Many patients opt for rehabilitation alone, which can compensate for the injury by building up the knee. Others -- particularly athletes -- may choose physical therapy and surgery, which often involves reconstructing the ACL with tissue taken from the patient's kneecap or hamstring. Sometimes, tissue is harvested from a cadaver.
"When it comes to ACL reconstruction, one size does not fit all," says Walt Lowe, MD, chairman of the Department of Orthopaedic Surgery at The University of Texas Health Science Center at Houston (UTHealth) Medical School and medical director of the Memorial Hermann IRONMAN Sports Medicine Institute.
Lowe, who performs about 400 ACL reconstructions a year, says, "You have to consider injury to surrounding tissue, how active the patient plans to be, how the patient might respond to a rigorous rehabilitation program as well as a host of other issues."
In the Texas Medical Center, Lowe says surgeons are collaborating with physical therapists and researchers in an effort to extend the life of reconstructed ACLs and reduce the failure rate.
When patients are referred to Lowe, who is the head team physician for the Houston Texans, Houston Rockets and the University of Houston Cougars, he begins by examining X-rays of the injured ACL and reviewing the patient's medical history. He will also order a Magnetic Resonance Imaging (MRI) scan.
Depending on the patient's goal, rest and physical therapy may be sufficient. An example of this would be a person who sustained an injury in a fall and does not plan to participate in sporting activities in the future. Athletes and people whose jobs involve demanding physical activities may require more aggressive therapy.
In the latter, Lowe, who completed a fellowship at the Kerlan-Jobe Orthopaedic Clinic in Los Angeles, typically recommends one of three surgical procedures.
The most common procedure performed by Lowe is the bone-patellar tendon-bone autograft. Similar to a ligament, a tendon is another tough connective tissue. Return to play is usually faster with this procedure.
In this case, Lowe uses the patient's own patella tendon to create a new ACL, which comprises a strip of tendon with two tiny bones at each end. One end is from the patella and one end is from the tibia. During the procedure, it is secured with screws inside tunnels that are drilled in the anatomic location of the original ACL's attachment.
Lowe sometimes will create a new ACL with tissue taken from the patient's hamstrings. Because this replacement comprises soft tissue and no bone, rehabilitation typically isn't as rigorous at the onset. The hamstring is a group of tendons comprising three posterior thigh muscles.
If harvesting tissue from the patient isn't the ideal option, Lowe can use donated tissue to reconstruct the ACL.
Each of these operations has benefits and risks. The bone-patellar tendon-bone autograft is strong but can be more painful during the post-operative period. The hamstring autograft generally involves a less rigorous rehabilitation but it may take longer to return to athletic competition. Using donated tissue speeds the return to everyday activities but takes the longest when it comes to returning to sporting activities.
All these procedures are performed with the aid of a tiny fiber optic television camera and slender instruments that can be inserted through three small incisions. These arthroscopic procedures reduce scarring and the risk of infection when compared to open procedures.
Rehabilitation typically takes six to nine months and the intensity varies depending on the procedure.
There are three things in particular that UTHealth doctors at Memorial Hermann are doing in an effort to extend the life of reconstructed ACLs.
"We enhance the healing process. We know which drugs to use and which to avoid. Once the procedure is over, we use plasma rich platelets or the patient's own bone marrow stem cells to speed healing," says Lowe, who is the holder of the Edward T. Smith, MD Chair in Orthopaedic Surgery at UTHealth. "These are called biologics."
Second, it is important that surgeons place the replacement ACL in the exact footprint of the original. This is something that requires an experienced surgeon and is critical to the healing process. It is the only technique that allows the knee to function with its normal internal motion after the completion of the procedure. If the ACL is not reconstructed in this anatomic fashion, then the knee will not move and behave as it did before the injury.
Third, Lowe says, it is important that rehabilitation be designed with the intent of enhancing the function of the reconstructed ACL and not just to get the patient on his or her feet as soon as possible. Once the procedure has been completed, the most important step in achieving an outstanding result is specific and guided physical therapy over the following six to nine months.
Lowe and Memorial Hermann IRONMAN Sports Medicine Institute physical therapist Russ Paine meet with patients following surgery to outline the goals of physical therapy, which include restoring function and motion as soon as possible and making sure patients are adequately prepared for the next step.
Paine says therapists also prepare patients for the mental aspects of ACL recovery, which is particularly important for athletes who need the confidence to put pressure back on their reconstructed ACL.
Materials provided by University of Texas Health Science Center at Houston. Note: Content may be edited for style and length.
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