Anterior Cruciate Ligament (ACL) Injuries
Prepared by
Dr. Edwin M. Tingstad, M.D.
Inland Orthopaedics Surgery
& Sports Medicine Clinic
A torn anterior cruciate ligament(ACL) is one of the most common knee ligament injuries. Approximately 1 in 3000 Americans will injure their ACLs. Our understanding of the anterior cruciate ligament and its importance to knee stability has increased greatly over the past 15 years. Techniques for diagnosing the injury and performing surgical reconstruction have become more reliable.
Anatomy
The normal anatomy of the human knee is depicted in Figures I and 2 below. There are four major ligaments that provide knee stability. The anterior cruciate ligament is located inside the knee joint next to the posterior cruciate ligament. The medial collateral ligament (MCL) and lateral collateral ligament (LCL) are on the outside of the knee joint. There are also two meniscal cartilages that act as shock absorbers and provide some stability. The articular cartilage lines the knee joint and allows for smooth, nearly frictionless motion. A torn anterior cruciate ligament is commonly associated with injury to one or more of these structures.
Mechanism of Injury
Injuries to the anterior cruciate ligament occur most often in athletic activities. The injury typically does not require a blow to the knee but instead involves a rapid change in direction or deceleration maneuver. Seventy percent of ACL injuries are not associated with contact. The individual will often hear a "pop" inside the knee. The injury is usually followed by increasing pain and swelling, as well as progressive inability to bear weight on the leg, for a short period of time.
Initial Management
The initial management of a patient with an anterior cruciate ligament injury is high individualized, but some general principles exist. Assuming no fractures are present, the patient is often allowed to bear weight on the extremity when pain and swelling and motion allow. Eighty percent of ACL injuries have significant bone bruising that may necessitate minimal weight bearing. You may be advised to wear a brace and/or use crutches depending on the severity of the injury. Application of ice to the knee, usually for 20 minutes 4-5 times per day, may aid in minimizing swelling for the first 3 days after the injury. Treatments will be started to help restore knee motion, maintain muscle strength and reduce swelling. If surgery is to be performed, it will be done after the acute inflammation (swelling) and restriction of motion that accompanies the injury have subsided, which generally takes about 2-3 weeks.
Your physician mayor may not choose to obtain an MRI (magnetic resonance imaging) scan of your knee. An MRI scan is not always necessary if the physician's clinical evaluation is evident. This is tailored to each patient.
Definitive Management
Approximately one-third of patients who injury the anterior cruciate ligament will experience relatively few problems and lead a fairly normal lifestyle. Another one¬ third will have problems with the knee with various athletic activities. These people could live with their knee satisfactorily if they are willing to give up those activities that cause problems. The remaining one-third of patients will have problems with their knee even with simple activities of daily living, such as stepping off a curb or changing directions while walking or jogging.
The decision to undergo reconstructive surgery for a tear of the anterior cruciate ligament is highly individualized. Patients who should consider undergoing anterior cruciate ligament reconstruction are those who plan to continue an active lifestyle, which places demands on the injured knee. Activities that require frequent changes in direction or speed (tennis, skiing, basketball, football, soccer, softball) will generally result in "giving way" episodes in a person with an anterior cruciate ligament deficient knee. These episodes may cause further injury to the menisci and articular cartilage of the knee and are thought to eventually result in degenerative arthritis. Patients who lead a more sedentary lifestyle or those who participate in "straight ahead" sports like jogging, swimming and cycling, may have little, if any, difficulty with their knee. They might prefer to treat their injury with a rehabilitation program alone. Sometimes, the decision to undertake anterior cruciate ligament reconstructive surgery depends on whether or not a patient is willing to forego activities which can cause episodes of knee instability. We advise patients to strongly consider anterior cruciate ligament reconstructive surgery if they plan to engage in activities that would place the knee at risk for instability episodes. Patients with old ("chronic") injuries to their anterior cruciate ligament should either avoid activities that cause buckling or consider ligament reconstruction. Regardless, of treatment a large percentage of patients with ACL injuries have been shown to have earlier onset of arthritis at 10-15 years after the injury.
ACL Reconstruction - Options
Reconstruction of the anterior cruciate ligament is a surgical procedure performed in an operating room usually under general or spinal anesthesia. The technique for this surgery is referred to as "arthroscopically assisted ligament reconstruction." This is, an incision is made to obtain the tissue to be used in the reconstruction, but the actual ligament replacement surgery is done with the arthroscope. The ligament reconstruction is performed by removing the remnant of the tom ligament from the knee and then replacing it with biologic tissue. The replacement may come from one of several sources. These include your patellar tendon or hamstring tendons (called "auto grafts") or tissue from tissue banks (called "allograft"). The decision about which graft source to use should be made by the patient in conjunction with their treating physician. Figure 3 depicts an anterior cruciate ligament reconstruction using patellar tendon graft fixed with one screw at each end of the graft.
Pre-Operative
The initial evaluation and treatment is used to discuss treatment options and outline a rehabilitation plan. Often an MRI is ordered or therapy is arranged to facilitate regaining motion and strength. Regardless, of the treatment chosen this is a critical component of treatment program. If the decision is made to proceed to surgery then the timing of this is decided upon. Further appointments are arranged around the rehabilitation and surgery dates if chosen.
If surgery is chosen a separate pre-operative visit is scheduled a few days before surgery. You will be given a paperwork packet containing your insurance information, surgical consent form, and pre-operative orders for the hospital. Take these with you when you go to the hospital for your pre-operative visit.
You will also be given a specific time to arrive at the pre-operative surgery desk at the hospital on the day of surgery. Not uncommonly, however, the operative schedule proceeds either slower or faster than we anticipate. For this reason it is important that we have a means of contacting you on the day of surgery in case there is a last minute change of schedule. We know changes in schedules are frustrating and we will try diligently not to alter yours. REMEMBER, eat or drink nothing after midnight on the day of surgery.
The Day of Surgery
When you arrive in the pre-operative holding area, you will be asked to change into a hospital gown and make yourself comfortable on a gurney; (most patients prefer to leave their underwear on during the procedure, and this is fine). You will meet your anesthesiologist in the pre-operative holding area, and options for anesthesia will be discussed. You will be asked to initial your knee with a marker, and a compressive stocking will be placed on your other leg. Your knee will be prepared for surgery first by shaving the hair from the operative site and then by scrubbing it with an antibacterial soap. We ask that we do the shaving just before the surgery as it may reduce the chance of infection. From the pre-operative holding area, you will be taken to the operating room. A tourniquet will be placed around your thigh, and it is occasionally inflated for a portion of the surgery. Your extremity will be draped in a sterile manner that allows to work in a completely sterile field.
The surgical time is approximately two hours. If one or both of the menisci (knee cartilage) are tom, the surgery will take slightly longer in order to remove or repair the damaged structures. After the reconstruction is completed, a light dressing, the cold therapy unit, and a brace may be applied.
From the operating room you will be transferred to a recovery area for approximately one or two hours. Local anesthetics will be injected into the knee joint at the end of the operation to reduce post-operative discomfort. Often a nerve block is performed at the end of the surgery. Pain medication as needed is available in the recovery room. Occasionally, nausea may occur from the anesthesia, and medication is available to help control it. The decision of whether to stay in the hospital will be discussed prior to your surgery.
During the first 24-48 hours you should limit your walking as much as possible. The leg should be elevated on 2 or 3 pillows above the level of your heart. The leg does not need to be elevated during sleep. We suggest using the cold therapy unit, applied over the dressing, for 20 to 30 minutes each hour. Once you are ready for sleep, discontinue cold therapy treatment. Cold therapy treatment is the most effective within the first 48 hours of surgery. If braced, we encourage you to wear the brace at all times except when doing the exercises you were shown by the therapist (which are not necessary the first night). When you do get up, for example, to go to the bathroom, use your crutches. Keep your incision and dressing dry. It is common to experience some bloody drainage from the knee for the first 24-36 hours. If this occurs, simply reinforce the dressing with a sterile gauze if the fluid is bothersome.
Another common occurrence after general anesthesia is a low-grade fever during the first 24-48 hours post-operatively. The fever is usually below 1000 and slowly abates. Tylenol works quite well to keep it in check. If your fever is greater than 1000 and associated with shaking chills and increasing knee pain, please let us know, as this may be an early indicator of infection. It's also important to cough and take deep breaths regularly during the first 24 hours (we recommend 10 deep breaths per hour during waking hours). Movement of ankle also assists in decreasing swelling and is recommended as much as possible.
Post-Operative Rehabilitation
ACL Reconstruction
General Overview : The 8-12 Months Following Surgery
Your newly reconstructed graft undergoes a biologic transformation from the time of implantation to almost one year post-operatively. Studies indicate that your graft may initially be stronger than a normal ACL but quickly loses its original strength and reaches its lowest point by one month. It then gradually regains strength over the next 6-8 months. The exact numbers are controversial, but the general trend is illustrated below.
Your rehabilitation after surgery is designed to re-establish motion and strength during this remodeling. Initially, activities are permitted which cause the least strain on the reconstructed ligament. Gradually, over time, activities are increased ultimately leading to sport specific training. The priority is to obtain range of motion (ROM) first followed by strengthening. The following time-line summarizes our approach to your rehabilitation and can serve as a quick reference guide. The concept is to permit mild load to promote normal healing and avoid excessive load that might be harmful.
1. Immediate Post-op Period: 1st Week
The main goals in the first week after surgery are to allow incisions to heal and for you to recover from the overall effects of the surgery. We suggest ice to help control swelling, allow weightbearing as tolerated with two crutches, and focus on motion exercises,-_A high priority in motion is to achieve full extension. That is why we suggest you sleep in the brace with it locked in extension. We begin knee rehabilitation right after surgery. Some people progress quite rapidly, while other make gains more slowly. Your ability to incorporate them into your daily routine depends on your general recovery.
1st Week Summary |
Goals |
1. Recovery from surgery
2. Decrease swelling
3. Achieve full extension |
General Insructions |
1. Protected weightbearing with two crutches
2. Brace locked in full extension for sleeping and ambulating
3. May remove brace for exercise
4. When sitting, place roll under heal to promote full extension |
Exercises |
1. Passive range of motion (ROM) from 0-90°
2. Patellar mobilization
3. Ice treatment
4. Co-contraction hamstring / quadriceps
5. Heel pumps |
2. Early Protective Phase: 2nd-8th Week
The early protective phase occurs from the second to the eighth week and corresponds to a time when your graft is undergoing large biologic transformations. It is a transition period where the emphasis shifts from range of motion and weightbearing to the beginning to strengthening of your muscles and maintaining generalized aerobic conditioning by the end. During exercises, we emphasize that the foot be in contact with the floor (closed chain). We would like to see you have no effusion (swelling in the knee) and a full range of motion by the end of week 8, but not everyone achieves this goal.
Summary: Weeks 2 - 4 |
Goals |
1. Progressive decrease in swelling
2. Progressive increase in ROM (0-115)
3. Initiate strengthening
4. Aerobic conditioning |
General Insructions |
1. Brace locked in full extension for sleeping, may begin to unlock for ambulating
2. May weight bear as tolerated. Let pain and swelling determine the transition from 2 crutches to 1 to none |
Exercises |
1. Continue patellar mobilization
2. Hamstring / Gastrocnemius stretching
3. Knee dips, hamstring curls
4. 4-plane straight leg raises
5. Co-contractions hamstring / quadriceps
6. Proprioception training |
Conditioning |
Stationary bike - adjust seat height to accommodate ROM |
Summary: Weeks 5 - 8 |
General Insructions |
1. Full extension achieved, may discontinue use of brace altogether |
Exercises |
1. Leg press 60-100
2. Six-inch step ups
3. Machine hip flex / ext / abduction / adduction |
Conditioning |
1. Stationary bike
2. Nordic Track / Stairmaster
3. Pool walking |
3. Moderate Protection Phase: 9th-12th Week
This period is characterized by a gradual but steady gain in strength and fitness. If you have not yet reached the goals of the early protective phase, this is the time to achieve them. Again, all strengthening exercises emphasize closed chain activities. Open chain, such as leg extension with weights while the foot is out, causes too much strain on the graft and may be detrimental.
Summary: Weeks 9 - 12 |
Goals |
1. Achieve full and symmetric ROM with no effusion
2. Progressive increase in strength and fitness |
Exercises |
1. Step ups / step downs
2. Leg press in full ROM
3. Knee dips
4. Lunges
5. Calf raises
6. Hamstring curls
7. Continue stretching hamstrings, gastroc / soleus and hip flexors |
Conditioning |
Add pool jogging |
4. Light Activity Phase: 13th-20th Week
This period provides the first opportunity to begin phasing into your desired sport. We begin to allow agility drills and sport-specific training at a light (half speed) level.
Summary: Weeks 13 - 20 |
Goals |
1. Progressively increasing mobility, agility and strength |
Exercises |
1. Light agility drills
2. Plyometrics
3. Phase into sport specific training and drills by the end of the period |
Conditioning |
1. Jogging
2. Road biking |
5. Return to Full Activity Phase: 6th-8th Month
During this period, you are preparing to return to your desired sport. All of the previous exercises and conditioning are continued while running, and agility drills are added as well as sport-specific training.
You do not necessarily have to wear a sports brace when you return to your sport. No study has conclusively shown that the brace prevents injury to your graft or to a normal ACL. If you are returning to a high risk sport, such as basketball, football or singles tennis, many patients have found that wearing a sports brace for the first year is comforting
Criteria for Return to Full Activity:
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Clearance by Dr. Tingstad
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Full and symmetric range of motion
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Good muscle strength and control (usually quadriceps and hamstring strength within 10% compared to the unaffected limb)
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Functional hop test within 85% of the unaffected limb
ACL Reconstruction
Most Frequently Asked Questions
1. When can I shower?
You may shower as long as you cover the incision with plastic and keep it dry until your sutures are removed in the office. After this, you may shower without covering the incision. Please wait 2 weeks from the time of surgery before you immerse the knee in water.
2. How many incisions will I have?
The answer to this question depends on what graft is used and what type of fixation. If we use your patellar tendon, you will have a 3" incision on the front of your knee and a small incision above your kneecap. Sometimes we need an additional I" incision on the outside of your knee. If your menisci need repairing, you will have additional 1-2" incisions corresponding to which meniscus is repaired.
3. How long do I use crutches?
We like you to use crutches for the first week and as long as is necessary for balance. The length of time they are to be used depends on the extent of further surgery.
4. Can I put weight on my leg?
You are permitted to weight bear as tolerated on your leg from the first day after surgery, as long as you have your brace on, and it is locked in extension. We prescribe that you use the brace for one month when weightbearing, and use the crutches as described above.
5. When can I drive?
(2-6 weeks) Driving depends on which leg is operated upon and whether your car has an automatic or manual transmission. If it is your left leg, and you have an automatic, you may drive when you are comfortable. If it is your right leg or a manual transmission, it takes longer, perhaps two-ten weeks depending on the individual. We ask that you practice in a vacant area to be sure you are safe before driving on the main road. Reflexes are slowed for a prolonged period after surgery.
6. Will I always need a brace?
We have you wear a post-operative brace for one month to help you achieve full extension. When returning to your sport, some patients wear a sport brace for the first year if it is a high risk sport, such as basketball, football or tennis. A few individuals will use the brace longer. However, most are brace-free after they have completed their rehabilitation.
7. Does my brace stay locked or unlocked?
For the first week, your brace remains locked for both ambulation and sleeping. As you begin to ambulate more and need the crutches less, your athletic trainer will unlock the brace for walking and begin to encourage a more normal gait pattern. This can occur between the 2nd and the 4th week. The brace remains locked in full extension while sleeping for one month.