Knee Arthroscopic Surgery

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Knee Arthroscopic Surgery

Normal results
Morbidity and mortality rates


Knee arthroscopic surgery is a procedure performed through small incisions in the skin to repair injuries to tissues such as ligaments, cartilage, or bone within the knee joint area. The surgery is conducted with the aid of an arthroscope, which is a very small instrument guided by a lighted scope attached to a television monitor. Other instruments are inserted through three incisions around the knee. Arthroscopic surgeries range from minor procedures such as flushing or smoothing out bone surfaces or tissue fragments (lavage and debridement ) associated with osteoarthritis, to the realignment of a dislocated knee and ligament grafting surgeries. The range of surgeries represents very different procedures, risks, and aftercare requirements.

While the clear advantages of arthrocopic surgery lie in surgery with less anesthetic, less cutting, and less recovery time, this surgery nonetheless requires a very thorough examination of the causes of knee injury or pain prior to a decision for surgery.


There are many procedures that currently fall under the general surgical category of knee arthroscopy. They fall into roughly two groups—acute injuries that destabilize the knee, and pain management for floating or displaced cartilage and rough bone. Acute injuries are usually the result of traumatic injury to the knee tissues such as ligaments and cartilage through accidents, sports movements, and some overuse causes. Acute injuries involve damage to the mechanical features, including ligaments and patella of the knee. These injuries can result in knee instability, severe knee dislocations, and complete lack of knee mobility. Ligament, tendon, and patella placements are key elements of the surgery. The type of

treatment for acute injuries depends in large part on a strict grading system that rates the injury. For instance, grades I and II call for rest, support by crutches or leg brace, pain management, and rehabilitation. Grades III and IV indicate the need for surgery. Acute injuries to the four stabilizing ligaments of the knee joint—the anterior


Anterior cruciate ligament (ACL)— A crossing ligament that attaches the femur to the tibia and stabilizes the knee against forward motion of the tibia.

Knee surgery— Refers primarily to knee repair, replacement or revision of parts of the knee, both tissue and bond, and includes both arthroscopic and open surgeries.

Lateral release surgery— Release of tissues in the knee that keep the kneecap from tracking properly in its groove (sulcus) in the femur; by realigning or tightening tendons, the kneecap can be forced to track properly.

Meniscus— The fibrous cartilage within the knee joint that covers the surfaces of the femur and the tibia as they join the patella.

cruciate ligament (ACL), the posterior cruciate ligament (PCL), the medial collateral ligament (MCL), and the lateral collateral ligament (LCL)—as well as to the “tracking,” or seating of the patella, can be highly debilitating.

Treatment of these acute injuries include such common surgeries as:

  • Repairs of a torn ligament or reconstruction of the ligament.
  • Release of a malaligned kneecap. This involves tendon surgery to release and fit the patella better into its groove.
  • Grafts to ligaments to support smoother tracking of the knee with the femur.

Pain management surgeries, on the other hand, are used to relieve severe discomfort of the knee due to osteoarthritis conditions. These treatments aim at relieving pain and instability caused by more chronic, “wear and tear” kinds of conditions and involve minor and more optional surgical procedures to treat cartilage and bone surfaces. These include arthroscopic techniques to remove detached or obtruding pieces of cartilage in the joint space such as the meniscus (a fibrous cushion for the patella), to smooth aged, rough surface bone, or to remove parts of the lining of the joint that are inflamed.

Treatment distinctions between arthroscopic surgery for acute injuries and those for pain management are important and should be kept in mind. They have implications for the necessity for surgery, risks of surgery, complications, aftercare, and expectations for improvement. Arthroscopic surgery for acute injuries is less controversial because clear dysfunction and/or severe instability are measurable indications for surgery and easily identifiable. Surgery indications for pain management are largely for chronic damage and for the milder grades or stages of acute injuries (severity Grade I and II). These are controversial due to the existence of pain management and rehabilitation alternatives. Arthroscopic surgery for pain management is currently under debate.


More than five and a half million people visit orthopedic surgeons each year because of knee problems. Over 650,000 arthroscopic surgeries are performed annually; 85% of them are for knee surgery. One very common knee injury is a torn anterior cruciate ligament (ACL) that often occurs in athletic activity. The most common source of ACL injury is skiing. Approximately 350,000 people in the United States sustain a torn or ruptured ACL each year. Research indicates that ACL injuries are on the rise in the United States due to the increase in sport activity.

The incidence of ACL injuries in women is two to eight times greater than in men. While the exact causes are not clear, differences in anatomy, strength, or conditioning are thought to play major roles. Women also seem to be more prone to patella-femoral syndrome (PFS), which is the inability of the patella to track smoothly with the femur. PFS is due primarily to development of tendons that influence the ways in which the knee tracks in movement. It can also be due to misalignments to other parts of the lower body like foot pronation. Other ligament surgeries can be caused by injury or overuse.

Knee dislocations are a focus of recent research because of their increasing frequency. Incidences range from 0.001% to 0.013% of all patients evaluated for orthopedic injuries. Many of these injuries heal without treatment and go undetected. Many people with multiple traumas in accidents have knee dislocations that go undiagnosed. Knee dislocations are of special concern, especially in traumatic injury, because their early diagnosis is required if surgery is to be effective. Knee dislocations in the morbidly obese individuals often occur spontaneously and may be associated with artery injury. This surgery involves complications related to the obesity. Finally, knee dislocations have been reported to occur in up to 6% of trampoline-associated accidents.


Arthroscopic surgery for acute injuries

The knee bone sits between the femur and the tibia, attached by four ligaments that keep the knee stable as the leg moves. These ligaments can be damaged or torn through injuries and accidents. Once damaged, they do not offer stability to the knee and can cause buckling, or allow the knee to “give way.” Ligaments can also “catch” and freeze the knee or make the knee track in a different direction than its leg movement, causing the knee to dislocate. Traumatic injuries such as automobile accidents may cause more than one ligament injury, necessitating multiple repairs to ligaments.

Four arthroscopic procedures relate to damage to each of the four ligaments that stabilize the knee joint movement. The four procedures are:

  • Anterior cruciate ligament (ACL). A front-crossing ligament attaching the femur to the tibia through the knee; this ligament keeps the knee from hyperextension or being displaced back from the femur. The ACL is a rather large ligament that can withstand 500 lbs (227 kg) of pressure. If it is torn or becomes detached, it remains that way and surgery is indicated. In the most severe cases, a graft to the ligament is necessary to reattach it to the bone. The surgery can use tissue from the patient, called an autograft, or from a cadaver, called an allograft. The patella tendon, which connects the patella to the tibia, is the most commonly used autograft. ACL reconstructive surgery involves drilling a tunnel into the tibia and the femur. The graft is then pushed through the tunnels and secured by stapling or sutures.
  • Posterior cruciate ligament (PCL). A back-crossing ligament that attaches the front of the femur to back of the tibia behind the knee that keeps the knee from hyperextension or being displaced backward. PCL injuries are not as frequent as ACL injuries. These injuries are largely due to falls directly on the knee or hitting the knee on the dashboard of a car in an accident. Both displace the tibia too far back and tear the ligament. Surgery to the PCL is rare, because the tear can usually be treated with rest and with rehabilitation. If surgery is required, it is usually to reattach the PCL to the tibia bone.
  • Medial collateral ligament (MCL). This is an inside lateral ligament connecting the femur and tibia and stabilizing the knee against lateral dislocation to the left or to the right. The injury is usually due to external pressure against the inside of the knee. In the case of a grade I or II collateral ligament tear, doctors are likely to brace the knee for four to six weeks. A grade III tear may require surgery to repair ligament tear and is followed by three months of bracing. Physical therapy may be necessary before resuming full activity.
  • Lateral collateral ligament (LCL). An outside lateral ligament connecting the femur and tibia and stabilizing the knee against lateral dislocation. In the case of a grade I or II collateral ligament tear, doctors are likely to brace the knee for four to six weeks. A Grade III tear may require surgery to reattach the ligament to bone. Surgery will be followed by three months of bracing. Physical therapy may be necessary before resuming full activity.

Patello-femoral syndrome (PFS)

The patella rests in a groove on the femur. Anything but a good fit can cause the patella to be unstable in its movement and very painful. Some individuals have chronic problems with the proper tracking of the patella with the femur. This may be associated with conditions related to physical features like foot pronation, or to types of body development in exercising or overuse of muscles. In the case of damage, an examination of the cartilage surrounding the patella can identify cartilage that increases friction as the patella moves. Smoothing the damaged cartilage can increase the ease of movement and eliminate pain. Finally, a tendon can occasionally make the patella track off center of the femur. By moving where the tendon is attached through lateral release surgery, the patella can be forced back into its groove.

Pain management with lavage and debridement

In addition to the ligament and patella surgeries that are largely required for traumatic injuries, arthroscopic surgery treats the wear and tear injuries related to a torn meniscus, which is the crescent-shaped cartilage that cushions the knee, as well as injuries to the surface of bone that makes joint movement painful. These are related to osteoarthritis and rheumatoid arthritis.

In lavage and debridement, the surgeon identifies floating or displaced tissue pieces and either flushes them out with a solution applied with arthroscopy or smoothes the surface of bone to decrease pain. These two surgical treatments are controversial because research has not indicated that alternatives to surgery are not as successful.

All of the above procedures are conducted through the visualization offered by the lighted arthroscope that allows the surgeon to follow the surgery on a television monitor. Instruments only about 0.15 in (4 mm) thick are inserted in a triangular fashion around the knee. The arthroscope goes in one incision, and instruments to cut and/or smooth and to engage in other maneuvers are put through the other incisions. In this fashion, the surgeon has magnification, perspective, and the ability to make tiny adjustments to the tissue without open surgery. The triangular approach is highly effective and safe.


Disease and injury can damage joints, ligaments, cartilage, and bone surfaces. Because the knee carries most of the weight of the body, this damage occurs almost inevitably as people age, due to sports injuries and through accidents.

The diagnosis of knee injuries or damage includes a medical history, physical examination, x rays, and the additional, more detailed imaging techniques with MRI or CT scan. Severe or chronic pain and/or knee instability initially brings the patient to an orthopedic physician. From there, the decision is made for surgery or for rehabilitation. Factors that influence the decision for surgery are the likelihood for repair and recovery of function, the patient’s health and age, and, most importantly, the willingness of the patient to consider changes in lifestyle, especially as this relates to sport activity. Arthroscopic viewing is the most accurate tool for diagnosis, as well as for some repairs. The surgeon may provide only a provisional diagnosis until the actual surgery but will apprise the patient of the most likely course the surgery will take.

Arthroscopic surgery can be performed under local, regional, or general anesthetic. The type used depends largely upon the severity of damage, the level of pain after surgery, patient wishes, and patient health. The surgery is brief, less than two hours. After closing the incisions, the leg will be wrapped tightly and the patient is taken to recovery. For most same-day surgeries, individuals are allowed to leave once the anesthetic effects have worn off. Patients are not allowed to drive. Arrangements for pick up after surgery are mandated.

Unlike open surgery, arthroscopic surgery generally does not require a hospital stay. Patients usually go home the same day. Any crutches or canes required prior to surgery will be needed after surgery. Follow-up visits will be scheduled within about a week, at which point dressings will be removed.


Ligament- and patella-tracking surgeries

Arthroscopic surgery for severe ligament damage or knee displacement often involves ligament grafting. In some cases, this includes taking tissue from a tendon to use for the graft and drilling holes in the femur or tibia or both. Aftercare involves the use of crutches for six to eight weeks. A rehabilitation program for strengthening is usually suggested. Recovery times for resumed athletic activity are highly dependent on age and health. The surgeon often makes very careful assessments about recovery and the need for rehabilitation.

Patella-tracking surgeries offer about a 90% chance that the patella will no longer dislocate. However, many people have continued swelling and pain after surgery. These seem to be dependent upon how carefully the rehabilitation plan is developed and/or adhered to by the patient.

Lavage and debridement surgeries

Elevation of the leg after surgery is usually required for a short period. A crutch or knee immobilizer adds additional stability and assurance when walking. Physical therapy is usually recommended to strengthen the muscles around the knee and to provide extra support. Special attention should be paid to any changes to the leg a few days after surgery. Swelling and pain to the leg can mean a blood clot has been dislodged. If this occurs, the physician should be notified immediately. Getting out of bed shortly after surgery decreases the risk of blood clots.


The risks of arthroscopic surgery are much less than open surgery, but they are not nonexistent. The risk of any surgery carries with it danger in the use of anesthesia, including heart attacks, strokes, pneumonia, and blood clots. The risks are rare, but they increase with the age of the patient. Blood clots are the most common dangers, but they occur infrequently in arthroscopic surgery. Other risks include infections at the surgery site or at the skin level, bleeding, and skin scars.

Risks related specifically to arthroscopic surgery are largely ones related to injury at the time of surgery. Arteries, veins, and nerves can be injured, resulting in discomfort in minor cases and leg weakness or decreased sensation in more serious complications. These injuries are rare. One major risk of arthroscopic surgery to the knee for conditions related to tissue tears is that the pain may not be relieved by the operation; it may even become worse.

Normal results

Normal results of ligament surgery are pain, initial immobility and inflexibility, bracing of the leg, crutch dependence, with increasing mobility and flexibility with rehabilitation. Full recovery to the level of prior physical activity can take up to three months.


Surgery is performed by an orthopedic surgeon, a specialist in joint and bone surgery, trained in arthroscopic surgery. Arthoscopic surgery is usually performed in a general hospital with an outpatient operating suite.

With ACL surgery, pain in the front of the knee occurs in 10-20% of individuals. Limited range of motion occurs in less than 5% due to inadequate placement of the graft. A second surgery may be necessary.

Research indicates that the pain-relieving effects for arthroscopic partial menisectomy (removal of torn parts of cartilage) and debridement (the abrasion of cartilage to make it smooth) are not very reliable. Pain relief varies between 50% and 75%, depending upon the age, activity level, degree of damage, and extent of follow-up. One study indicates that the two surgical procedures, lavage and debridement, fared no better than no surgical procedure in relieving pain. The participants were divided into three groups for arthroscopic surgery: one third underwent debridement, a second third underwent lavage, and the remaining third likewise were anesthetized and had three incisions made in the knee area, though no procedure was performed. All three groups reported essentially the same results. Each had slightly less pain and better knee movement. The non-procedure had the best results. Debates about normal expectations from minor arthroscopic surgery continue with many surgeons believing that arthroscopic surgery of the knee should be restricted to acute injuries.

Morbidity and mortality rates

Complications occur in less than 1% of arthroscopic surgeries. Different procedures have different complications. In general, morbidity results mostly from medically induced nerve and vascular damage; death or amputations almost never occur. Graft infection may occur, along with other types of infection largely due to microbes introduced with instruments. The latter cases are becoming increasingly rare as the science of arthroscopic surgery develops.


Whether or not surgical treatment is the best choice depends on a number of factors and alternatives. Age and the degree of injury or damage are key to deciding


  • Are there rehabilitation alternatives to this surgery?
  • Will this surgery allow me to return to sports?
  • How much success have you had with this surgery in eliminating pain?
  • Is this injury one that I can live with if I pursue a change in lifestyle?
  • How long will post-operative rehabilitation take and how can I help in moving it along faster?

whether to have surgery or rehabilitation. The physician calibrates the severity of acute injuries and either proceeds to a determined treatment plan immediately or recommends surgery. Alternatives for acute ligament injuries depend on the severity of injury and whether the patient can make lifestyle changes and is willing to move away from athletic activities. This decision becomes paramount for many people with collateral and cruciate injuries.

According to the American Association of Orthopedic Surgeons, conservative treatment for acute injuries involves RICE: Rest, Ice, Compression, Elevation, as well as a follow-up rehabilitation plan. The RICE protocol involves resting the knee to allow the ligament to heal, applying ice two or three times a day for 15–20 minutes, compression with a bandage or brace, and elevation of the knee whenever possible. Rehabilitation requires range-of-motion exercises to increase flexibility, braces to control joint immobility, exercise for quadriceps to support the front of the thigh, and upper thigh exercise with a bicycle.

For arthritis-related damage and pain management, anti-inflammatory medication, weight loss, and exercise can all be crucial to strengthening the knee to relieve pain. Evidence suggests that these alternatives work as well as surgery.



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Nancy McKenzie, PhD