The knee joint is a frequent source of problems requiring the attention of an orthopaedic surgeon.
The joint is primarily formed by the two large bones of the lower limb, the femur (thigh bone) and the tibia (shin bone). The patella (kneecap) articulates with the femur at the front of the knee. The fibula joins with the tibia on the lateral (outside) side of the knee. Together, the femur, tibia and patella make three compartments (medial, lateral and patellofemoral). Each of the bones has a bearing surface of articular or hyaline cartilage. In addition, there is a meniscus in each of the medial and lateral compartments. The menisci are like cushions or spacers and are made of fibrocartilage. They are often simply referred to as the cartilages.
The direction of movement of the bones is controlled by the ligaments and the muscles make the joint move. The major ligaments are the anterior and posterior cruciate ligaments and the medial and lateral collateral ligaments. In addition, the collateral ligaments have important associated ligaments towards the back of the knee. The major muscle groups are the quadriceps at the front of the thigh and the hamstring muscles at the back. Muscles attach to bones via tendons. The main tendons around the knee are the quadriceps and patellar tendons which attach to the top and bottom of the patella respectively. The iliotibial band is like a tendon on the lateral side of the knee.
There is a wide range of pathology and problems in the knee.
The menisci can be torn as a result of an injury, although most meniscal tears are the result of a degenerative process and a specific injury may not be recalled. Not all meniscal tears require treatment, but if they do, this is usually done by arthroscopy. The tear can either be resected (cut out) or repaired.
The articular cartilage can wear away. This is called osteoarthritis. Treatment depends on the severity of the disease and can range from quadriceps strengthening exercises to a realignment procedure called an osteotomy or to joint replacement. Isolated injuries may also occur causing local defects for which there may be specific treatment to try to restore the surface. Osteochondritis dissecans is a condition that involves an area of articular cartilage and the underlying bone and usually occurs in teenagers. The appropriate treatment depends on many factors.
The bone underlying the articular cartilage may occasionally be affected by a condition called avascular necrosis in which the blood supply to an area of bone becomes disrupted. It may recover spontaneously or deteriorate to the point that intervention such as joint replacement may need to be considered. The cause of avascular necrosis is poorly understood.
Ligaments can be torn. Medial collateral ligament injuries usually heal without surgery but may require bracing. Anterior cruciate ligament injuries are often treated by reconstruction, but there are also situations in which they do not need surgical intervention. Posterior cruciate ligament injuries are not usually treated with reconstruction unless they are combined with other injuries or have been causing instability. Lateral ligament injuries are often associated with other injuries and may require surgery.
The patellofemoral joint is a frequent source of problems. There can be the same articular cartilage problems as in other parts of the knee. In addition, there can be problems with instability of the patella as well as maltracking of the patella in its groove in the femur. Physiotherapy is often the first-line treatment for many of these problems, but surgery may be required for recurrent dislocation of the patella. There are a variety of stabilization procedures that can be used depending on the specific problems of an individual.
Tendons can be torn and usually require repair. However, the more common problem is tendinopathy that results in local pain and which is usually treated without surgery, although surgical intervention may occasionally be required for symptoms that fail to resolve. The iliotibial band can impinge on the lateral aspect of the femur causing pain with running. It can usually be managed without surgery but surgical release is sometimes performed in chronic situations
The term knee reconstruction is commonly used to refer to reconstruction of the anterior cruciate ligament (ACL). This ligament is in the middle of the knee and controls the movement of the two main bones of the knee, the tibia and femur (Fig. 1). It is particularly important for twisting and turning movements that occur in football, netball, basketball and snow skiing.
Rupture (tearing) of the ACL can therefore lead to instability. This is felt as giving way with certain activities, usually those that involve a sudden change in direction. When giving way occurs, there is a risk of damage to the cartilages (menisci) and this, in turn, puts the knee at risk of developing premature osteoarthritis. Although it is an aim of reconstructive surgery, it is unclear whether anterior cruciate ligament reconstruction actually reduces the risk of developing osteoarthritis.
The main reason for reconstructing the ACL is to stop or to prevent instability. In many situations, this instability can be predicted soon after the injury occurs and a decision made to operate without waiting for the instability to develop. However, in other cases, it may be less clear and people may choose to rehabilitate their knee and try to return to their normal activities without surgery. Whether they can get back to their normal activities without surgery depends on many factors – how much healing of the torn ACL takes place, other injuries to the knee, the intrinsic stability of the knee, rehabilitation, and the individual’s ability to modify their activities.
It is important to remember that ACL reconstruction is almost always an elective procedure. From a medical point of view, there is no rush to make a decision, provided the knee is not giving way.
Figure 2: Knee locking exercise using a towel to support the heel
If ACL reconstruction is to be performed, it is essential to prepare the knee for surgery. The key is to get back full extension (straightening) of the knee. Although it may feel that there is something in the front of the knee that is blocking full extension, this is rarely the case, particularly after the initial injury. A key component is to reduce swelling by regular icing and wearing a compression bandage or sleeve. Having the heel supported on a rolled towel and using the quadriceps muscle at the front of the thigh to lock the knee out straight is the key exercise (Fig. 2). Flexion (bending) is also important and riding an exercise bike will help this, together with strengthening the quadriceps muscle.
The technique for reconstruction involves taking a piece of tendon (usually from the same knee, but sometimes from the other knee) and using this to replace the torn ligament (Fig. 3). The tendon graft is usually taken from the hamstrings on the inside of the thigh or from the patellar tendon at the front of the knee. It can also be taken from the quadriceps tendon, just above the patella (kneecap). Occasionally allografts are used. These are tendon grafts taken from cadavers (people who have died). In recent years, there has been increased interest and media coverage of synthetic grafts, specifically the LARS device. The role of the LARS remains unclear, but there are concerns because of problems seen when synthetic ligaments were used in the late eighties.
Figure 3: A. Drilling | B. Tendon graft in place
From your point of view, there is a vertical or oblique scar on the front of the knee together with two small scars from stab incisions that allow the arthroscope and surgical instruments to be introduced into the knee. If additional surgery is required to repair a cartilage, a further incision may be made towards the back of the knee on either the outside or inside. A small area of the skin on the outside (lateral side) of the knee is usually numb after surgery. Sometimes there is numbness on the shin. Although the numbness can be permanent, the area of numbness usually gets smaller with time and does not usually cause any problems.
Surgery is usually performed under a spinal anaesthetic. At the end of the operation, the area affected by the surgery is infiltrated with a local anaesthetic. Sometimes an epidural block or a femoral nerve block is also used. If this is the case you will notice numbness and tingling in your legs when you wake up. This gradually wears off over 8 hours or so. After leaving the recovery area pain control can usually be achieved with tablets alone. Anti-inflammatory medication is often used to help with pain control, so it is important that you tell your anaesthetist if you have ever had a history of stomach ulcers or bleeding, as this medication may not be appropriate in that situation.
You will be awake within 20 minutes of the operation and should be able to eat and drink after approximately 2 to 3 hours. On return to the ward after the operation, an inflatable cuff (Cryo-Cuff) is placed around the knee. This is filled with iced water to help control swelling. Patients find this very comfortable. Depending on your surgeon’s preference, you may have 1 or 2 drains placed in the knee joint so that unwanted blood does not accumulate and inhibit recovery. These drain tubes are usually removed the day after surgery.
A physiotherapist will teach you exercises to get the knee out straight (extension) and regain function in the quadriceps muscle at the front of the thigh as well as make sure that you are confident walking with the aid of crutches. A brace or splint is usually required.
You will usually go home in the morning after surgery. Following surgery, you will be provided with information regarding rehabilitation. This outlines the rate of progression. Rehabilitation can be undertaken either independently or under the supervision of a physiotherapist.
It is very important to rest during the first week after surgery in particular. This means spending most of the time on a bed or couch with the leg elevated and regular icing of the knee. The main aim during this phase is to restore full extension of the knee.
The time of work that is required will vary according to your job. If it is mainly deskwork, then patients may be able to work within 2 weeks. If heavy manual work is involved, it may be 2 to 3 months before one can consider a return to work. In general, crutches are required for up to 2 weeks.
In terms of returning to sport, most patients are able to recommence some of their activities by 4 months. By 6 months, the majority of patients are able to gradually resume training for their original sports with a view to returning to play from 9 or 10 months. However, improvement continues for another 6 to 12 months after that.
Frequently Asked Questions
The word arthritis literally means “joint inflammation.” Arthritis refers to a group of more than 100 rheumatic diseases and other conditions that cause pain, stiffness, and swelling in joints.
Rheumatoid arthritis is a disease that damages the lining surrounding our joints while also destroying our bones, tissue, and joints over time.
Osteoarthritis is a progressive condition that slowly damages the cartilage surrounding the ends of bones and is common in the hip, knee, and spine.
Arthroscopic surgery is a surgical procedure that is commonly performed to diagnose and treat problems within the joint. By using high-tech cameras, the orthopedic surgeon inserts a small instrument, called an arthroscope, into the joint.
The arthroscope contains a fiber optic light source and small television camera that allow the surgeon to view the joint on a television monitor and diagnose the problem, determine the extent of injury, and make any necessary repairs.
Joint replacement surgery is a surgical procedure that is performed to replace an arthritic or damaged joint with a new, artificial joint, called a prosthesis. Joint replacements can be performed on every joint in the body, but most commonly performed in the knee, hip, shoulder, and elbow.
Joints contain cartilage, a soft, rubbery gel-like coating on the ends of bones, where they articulate, that protects joints and facilitates movement and over time, or if the joint has been injured, the cartilage wears away and the bones of the joint start rubbing together. As the bones rub together, bone spurs may form, and the joint becomes stiff and painful. Most people have joint replacement surgery when they can no longer control the pain with medication and other treatments and the pain is significantly interfering with their lives.