A Review of Knee Injuries Affecting the Medial StructuresKnee injuries can really lay an athlete low. Those injuries affect the medial side of the knee most often (the side closest to the other knee). The soft tissues involved are first the superficial medial collateral ligament, then the deep medial collateral ligament, and finally, the posterior oblique ligament.
The medial ligament is one continuous structure with these three separate parts that all attach to different places along the knee but all work together to stabilize the medial side of the joint.
Each of these ligaments is important in stabilizing the knee for actions needed in sports like skiing, ice hockey, and soccer. For example, in these activities, the athlete must be able to bend the knee while rotating and changing directions quickly. Planting the foot and moving the knee in the opposite direction can cause a tear to any of these stabilizing soft tissues.
What can be done about medial knee injuries? Well, surprisingly, treatment is more and more conservative (nonoperative). The medial collateral ligament has a rich blood supply that makes healing without surgery possible. The torn ligament goes through all the normal stages of healing and eventually fills in with fibrous scar tissue.
The anatomy and biomechanics of these ligaments actually help determine the best treatment approach. Each portion (superficial, deep, or posterior) has its own purpose and function. For example, the superficial and deep portions of this ligament work together to keep the knee joint from sliding into a knock-kneed (valgus) position. At the same time, the posterior aspect of the ligament does the same thing when the knee is in a slightly flexed position (from zero up to 30 degrees of knee flexion).
Understanding the anatomy and function of the separate parts of this medial ligament guides the surgeon in first deciding whether or not surgery is needed and secondly, what kind of repair or reconstruction is needed. Some injuries when left untreated can increase the risk of another injury. All of these factors are taken into consideration when arriving at a plan of care.
Another thing the surgeon pays attention to is the grade of ligament injury. This is a way to classify how severe is the injury. The classification scale goes from grade I (mild joint laxity from a strained but not torn ligament) to grade II (partial tear of one or more portions of the ligament with separation or gapping of the joint with stress testing), and grade III (complete rupture of the ligament and more than 10 millimeters of joint laxity or gapping).
The injury is graded using both clinical tests (stress testing of the joint) and imaging studies such as X-rays and MRIs. Measuring how much the joint gaps (separates) helps determine the grade.
From animal studies, we now know that putting the leg in a brace or splint and staying off it is not such a good idea. Patients who start early motion actually have improved healing (faster with better results). The actual rehab program depends on how severe the injury is. Grades I and II are treated with controlled motion and protected weight-bearing. Grade III requires a slightly different protocol but can still be successfully managed without surgery.
Surgery may be necessary for some patients. Each individual is examined and evaluated on a case-by-case basis before making this decision. Surgery is more likely when there is more than one ligament damaged. If the anterior cruciate ligament (ACL) inside the knee is torn, then surgery is almost always required.
Of course the type of surgery depends on the specific damage. The surgeon may be able to simply repair the ligament by sewing the ends together. Sometimes it's necessary to augment the repair by using donated tissue grafts sewn into the healing natural ligament to help strengthen it.
Newer reconstruction techniques have been developed that have led to better results than ever before. Reconstruction is used with grade III (ruptured) ligaments and completely replaces the damaged tissue with grafts taken from a donor bank or from one of the patient's own tendons.
After surgery, early motion and strengthening are the keys to a good result. A physical therapist will guide them through the necessary exercises and advice regarding precautions. A hinged brace is used right away that allows protected movement.
The therapist supervises and progresses the rehab program on a week-by-week basis. Usually full weight-bearing is achieved around six to seven weeks after surgery. Special attention is paid to the way the patient walks as it is important to restore a normal gait (walking) pattern without compensatory movement.
Strengthening exercises are performed until full knee motion and joint stability are restored. Another aspect of rehab is proprioceptive training. Proprioceptive exercises are designed to restore the knee's accurate sense of position. It's important that the knee respond to the tiniest bit of motion in order to prevent future injuries.
Eventually it is possible to walk for two miles at a fast pace without a limp. At that point, jogging, squatting, and plyometrics are introduced. Plyometrics involve making fast changes with momentum (speed).
In summary, all grades of medial collateral ligament injuries from mild to severe are successfully treated today. Conservative (nonoperative) care is usually the first step even with grade III injuries.
Surgery may be needed if conservative care is unsuccessful in restoring knee stability. This is especially likely if other structures of the knee (e.g. anterior cruciate ligament) have been damaged at the same time. From the very start of recovery and rehab, patients are warned to be patient because it can take up to nine months before they can get back to full speed on the field, ice, or court.
Coen A. Wijdicks, PhD, et al. Injuries to the Medial Collateral Ligament and Associated Medial Structures of the Knee. In The Journal of Bone & Joint Surgery. May 2010. Vol. 92-A. No. 5. Pp. 1266-1280.
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