Much has been written about treatment advances for knee injuries. Yet, the knee is a relatively simple anatomic structure and most of the surgical techniques applied to the knee are simple as compared to the hand. From the advances made in fiberoptics for knee arthroscopy came advances in hand surgery when the same principles were put into play. In fact Dr. Ikutsu's first endoscopic carpal tunnel releases were performed with knee arthroscopy equipment!
Knee Ligament Injury
Knee injuries are frequently associated with sports activity. Diagnosis is usually fairly straightforward. Treatment will vary depending on your age and activity level. The knee has four
significant ligaments: the inner and outer (medial and lateral) collateral ligaments and the anterior and posterior (front and back) cruciate, or crossing, ligaments in the center of the knee. Any or all of these can be injured. Additionally the menisci, or “mobile knee cartilage”, are important disks that act as bearings transmitting weight from the thigh bone portion of the knee to the tibial or lower portion of the knee. Skeletally immature people, i.e. teenagers younger than about age 17, are more likely to break bone at a growth plate than they are to tear a ligament. However, many teens also disrupt their ACL. Adults on the other hand are more likely to tear a ligament than to break a bone with similar stresses. This is because the growth area is the weakest part of the limb in youths.
We separate ligament injuries into three categories:
- Grade 1- stretching injury with minor fiber damage and no loss of stabilizing function. These are the most painful and they usually heal completely within 3-6 weeks. Some limited bracing is beneficial for reducing discomfort. The knee usually isn’t swollen with this injury.
- Grade 2- There is usually swelling. There is some fiber tearing and the knee can be stretched open just a little bit by the examiner. A torn meniscus may be hidden behind this- but not usually. This also hurts quite a bit and more so on stress testing by the doctor or trainer.
- A grade 3 ligament injury is complete disruption. The knee opens up like a book when stressed. Directly at the time of injury there is some pain. Over the next few days it does not hurt nearly as much as a grade 1, but there may be some feeling of instability. A grade 3 MCL tear, however, is often associated with partial or complete disruption of the anterior cruciate ligament and an injury of the meniscus. This has been termed the “terrible triad”.
Treatment of Sprains
A grade 1 sprain requires Ace wrap, ice, and oral anti-inflammatory medication such as meloxicam or ibuprofen. A person may walk on it; they will probably have to cut back on any running or jumping for about 3 weeks while the discomfort subsides. Gentle cycling and straight-leg-raising (quad sets) are good for maintaining muscle strength.
With a grade 2 injury a person should probably wear a hinged knee brace in order to prevent muscle atrophy (wasting) from a cast or immobility-which takes a long time to regain muscle bulk. Straight-leg raising, known as quad sets, should be done at one’s home several times a day. It is not necessary to use any weights, just the weight of the leg is really enough.
With a grade 3 ligament injury it is important to determine whether it is an isolated injury of the collateral ligament (MCL or LCL) or if there is also injury of the meniscus and the anterior cruciate ligament (ACL). An isolated MCL tear is actually best treated nonoperatively in a hinged knee brace for about 6-12 weeks during which time a person can be bearing all of their weight fully, i.e. no cane or crutches, as long as they are comfortable. Most people need at least a cane for a couple of weeks, though, in addition to anti-inflammatory medication plus/minus some topical icing. No formal physical therapy is really necessary as long as a person does quad sets at home to maintain muscle bulk. Usually within a few weeks some active range of motion exercises are recommended with a progressively larger arc. If the meniscus is torn, some symptoms will persist and arthroscopy will be necessary to repair the meniscus, i.e. it is best to sew it back into position if it is repairable. Anterior cruciate ligament reconstruction is highly recommended at the time of repair of the torn meniscus if the injuries occur simultaneously. There is a very high rate of re-tearing of the meniscus if it is repaired without also reconstructing the anterior cruciate ligament. Note, an ACL disruption cannot usually be “repaired”; it must be reconstructed using a substitute tendon.
Anterior Cruciate Ligament Injury (ACL)
The hallmark of this injury is severe swelling occurring within about an hour or so of the injury. An Ace wrap and ice help reduce this. This is quite painful. It is beneficial just to insert a sterile needle in the knee and withdraw the blood after the first day. ACL injury is usually a complete grade 3 disruption. Physical exam is best and most revealing within an hour or so of injury. The knee is not yet very swollen and the injured person is less likely to involuntarily tighten his muscle. The surgeon or trainer assesses for a positive Lachman sign or A positive "pivot shift". These are both tests causing the knee to partially shift out of alignment or "subluxate". Many people are not examined soon enough after injury such as a skier who returns home with a swollen knee a few days after skiing. With swelling and pain it may be necessary to have an MRI scan to evaluate the ligament and the menisci. Partial injuries occur but are hard to diagnose. Partial tears of the cruciate usually progress to become complete grade 3 disruptions of the ACL. Disruption of the ACL is accompanied by some injury to either the inner or outer menisci in about half the cases. For the people who do not get reconstruction of the cruciate ligament, a certain percentage will go on to tear the meniscus later in association with excessive motion of the knee resulting in a feeling of the knee giving out. This occurs in a person whose knee is unstable enough for subluxation to occur when pivoting, such as turning abruptly around a corner. ACL injuries occur much more frequently in women than in men in most studies with a risk up to a high as six-fold for females over males.
The majority of adults over age 30 are not active enough to warrant reconstruction of the anterior cruciate ligament and they are not very symptomatic if it goes untreated beyond the initial first day of anti-inflammatory medication, rest, ice, and perhaps an Ace wrap over the course of a few weeks maintaining range of motion. Many ACL disruptions occur in even minor skiing injuries. The partially flexed position of the knee during skiing prevents symptoms from a torn ACL in the non-competitive skier. Instability symptoms from an anterior cruciate ligament disruption occur with the knee almost completely straight. While skiing one’s knees are bent beyond the point of instability symptoms most of the time. In fact, this is the basis of the clinical test for ACL deficiency- the Lachman test and the pivot shift test. It is more likely to bother someone who has to jump a lot such as rebounding a basketball, blocking or spiking during volleyball, or perhaps pivoting during soccer or running in football. If a person has the combined anterior cruciate and meniscal tear and they are relatively sedentary most of the time, i.e. not a competitive athlete, it makes sense to trim the meniscus when it is not a bucket handle or repairable tear (10% of meniscal injuries) and monitor for symptoms of instability rather than jump right in for expensive reconstructive surgery that takes many months to fully recuperate from.
Teenagers should probably be given the option of ACL reconstruction. It is not necessary to be done emergently. Reconstruction is helpful in prevention of deterioration of the knee in a very active individual in the future. Not everyone needs an intact anterior cruciate ligament however.
About 100,000 anterior cruciate ligament reconstructions are done in the United States yearly. ACL reconstruction is probably best handled using one's own tissue for reconstruction. In recent years a lot of allograft ligament reconstructions have been offered across the nation. An allograft ligament reconstruction involves a ligament harvested from someone who has died unexpectedly (like an auto accident) and is kept freeze dried or, in some cases, almost fresh to be inserted as the graft ligament. In young athletes, allograft has a high rate of failure compared to using one's own tissue; in fact, it fails twice as often. The use of an allograft has a much better potential outcome in a less active, older patient undergoing ACL reconstruction than in the younger patient. Use of an allograft tendon also carries with it the remote chance of transmission of viral illness such as AIDS and the remote chance of tissue rejection or other bizarre infections. There is probably less pain for the patient who uses an allograft tendon and the surgery is certainly much faster because no time has to be spent harvesting it. Overall, the price is about the same either way. The allograft tendon itself is more costly, where as using one's own tissue requires a longer surgery time.
Time to Recovery
Initially, a tendon graft used for ligament reconstruction of the ACL is much stronger than the original, particularly if the surgeon uses a bone-tendon-bone graft using the middle third of the patellar tendon. Within a few weeks, the ligament becomes much weaker than the original. This weakness is due to the elimination of circulation from the person's own graft and the complete lack of circulation in the allograft. It takes about a year to regain the strength of the original ligament. During the first six months of healing, a person should avoid jumping and pivoting. Running on a level surface can be begun within six weeks of the operation. Some athletes are being allowed back on the field in just a few months. This is not logical and it is not medically advisable because of the greater risk of failure of the weakened ligament.
The Posterior Cruciate Ligament (PCL)
The posterior cruciate ligament, or PCL, is injured much less frequently than the anterior cruciate ligament. It is difficult to diagnose except on an MRI scan. Physical exam is frequently similar to that for the anterior cruciate ligament. The symptoms may be vague and the outcome of treatments in the form of reconstruction is less predictable than for the anterior cruciate ligament. Generally the anterior cruciate ligament and the posterior cruciate ligament are not damaged simultaneously except in a knee dislocation wherein all 4 of the main ligaments are torn. Fortunately knee dislocation is a very rare injury. A high percentage of these cases are complicated by damage to the popliteal artery bringing up the risk of loss of one’s leg unless a diagnosis is made promptly.
Most people don’t have long-term symptoms from medial collateral ligament injury even if it is a grade 3. There might be some minor feelings of soreness at times and some increased laxity but it doesn’t typically result in any long-term problem. Full recovery takes about 6 weeks for a grade 1 injury, perhaps 3-6 months in a grade 3 injury with grade 2 somewhere in between. The diagnosis is made on the basis of physical exam and x-rays ruling out a broken bone.
Anterior and Posterior Cruciate Ligaments
The hallmark of this injury is severe swelling occurring within about an hour or so of the injury. An Ace wrap and ice help reduce this. This is quite painful. It is beneficial just to insert a sterile needle in the knee and withdraw the blood after the first day. Over the following week the person works on regaining his motion. If feeling unstable particularly upon resumption of athletic activities over the next couple of months, surgery may be indicated- sooner if a torn meniscus has been identified. An ACL reconstruction is probably best handled using one’s own tissues for reconstruction, i.e. the middle third of their patellar tendon or the middle third of the quadriceps tendon or the hamstring tendons. Many people are choosing to use cadaver graft which is placed in a tissue bank from people who died in trauma who had been healthy beforehand but had requested their body parts be put to good use. There is a remote chance of AIDS and a remote chance of tissue rejection. The cost is slightly greater with the donor tissue (allograft). There is probably less pain for the patient and the surgery is faster. In the long run research suggests that one’s own tissue is a little bit better but they are quite similar functionally. The tendon graft reconstruction is initially much stronger than the original and more likely to come loose from the anchoring sites in the bone above and below than to rupture. Within a few weeks because the circulation has been eliminated from the graft or in the case of an allograft which obviously has no circulation, the ligament becomes much weaker than the original. In fact, it takes about 1 year to regain the strength of the original ligament. Thus, during at least the first 6 months of healing a person needs to be avoiding jumping and pivoting, though running on level surfaces can be begun within about 6 weeks of the operation. Some athletes are being allowed back on the field in just a few months, this is not logical and it is not medically advisable because of the greater risk of failure of the weakened ligament.
You can request one of my brochures on anterior cruciate ligament injury or meniscal injury by contacting us.