Complications of Knee Surgery

Orthopaedic and sports service of the Maussins

Despite considerable progress in the field of knee surgery, surgical complications still exist. Every operation, as small as it may be, carries a wide range of risks from the most insignificant to the most serious (including fatal complications). Surely, discussing these complications with a patient does not mean that they will occur, but, by the same token, the failure to discuss these potential complications with the patient will not make them disappear…
Patients are encouraged to ask their surgeon about potential complications, and the surgeon should be forthcoming in his responses. Knee conditions are not life or death situations. Knee surgery pertains to quality of life. Therefore, it is incumbent upon the patient to decide whether surgery is reasonable or not. To reach such a decision, the patient will use the information provided by the surgeon.

The lists of possible complications is longer than that which can be practically enumerated by the surgeon. Fortunately, complications are usually rare and benign.


Intra-operative Complications

During particularly difficult cases, a major artery (e.g. the popliteal artery) or a major nerve (e.g. peroneal nerve) may be injured. As serious as these complications are, they are rare. Also rare are fractures of the tibia or of the femur, a tear of the patellar tendon or quadriceps tendon. The ligaments on either side of the knee can also be injured.


Post-operative Complications

Pain. Pain in the days following surgery is usually quite tolerable. Current surgical techniques such as arthroscopies and current post operative regimens, such as early mobilization have made most knee operations more patient friendly. Doctors are also more attuned to pain and are more eager than ever before to find ways to minimize it. Persistent pain following surgery can be due to a hematoma. Admittedly, there are times where persistent pain does not have an obvious cause.

Hematomas. Just about any operation can lead to some bleeding, especially if a blood thinner has to be used to prevent blood clots. A hematoma is usually apparent from the skin discoloration over it. It appears somewhat blue, then green, and then yellow and then regains its normal color. On occasion, blood collects inside the knee joint itself. If this is significant enough, a needle may need to be injected into the joint or, sometimes, another operation is required.

Infection. Infections are potential complications after any operation. When an infection occurs in the knee joint, it must be taken very seriously. Telltale signs include swelling, fever, and either persistent or new drainage through the incision site. The patient must keep the surgeon aware of such findings. Prior to instituting antibiotics, an attempt is usually made to identify the bacteria that are causing the infection. The knee joint usually has to be surgically washed out. The combination of a surgical lavage and antibiotics will often lead to a cure.

Phlebitis. This is the formation of a blood clot within a vein. It can occur despite the use of blood thinners. The main risks associated with phlebitis is propagation of the blood clot from the vein up into the lungs ("pulmonary embolus").

RSD (Reflex Sympathetic Dystrophy). This mysterious condition manifests itself by undue pain, stiffness and occasional swelling. Some believe that this condition is particularly prevalent in anxious patients. The recovery from RSD can be lengthy (months or even years) and can be incomplete.

Stiffness. This is a potential complication of any joint operation. In the case of the knee, a patient may have difficulty fully straightening or bending the knee. The stiffness is due to abnormal scar formation within the joint and may require further intervention (either a "manipulation under anesthesia" whereby the knee is gently straightened or bent, or surgical release of this dense scar tissue). Post operative physical therapy plays a major role in preventing this complication.

Skin Complications. The scar itself can remain painful. There can be numbness and/or pain on either side of the scar. In certain cases, the wound itself may fail to heal.


Complications Specific to a Particular Operation

Certain operations are associated with very specific complications. For example, prostheses carry a risk of wear and loosening. In the case of an osteotomy, the bone that has been cut may not heal (pseudoarthrosis), or the bone fragments may displace in an undesirable manner.


Surgical Results

It is not possible to guarantee a good result regardless of the operation. There are a number of reasons for this:

- An operation does not always reach the desired goal: a patella may dislocate even if the operation is designed to stabilize it. A knee may remain unstable even after surgical repair or reconstruction of the ligament. Pain may sometimes persist even after operation designed to eliminate it.
- Certain pains cannot be completely cured by an operation: an osteotomy, for example, does not cure arthritis, but, hopefully, lessens the pain. The removal of a meniscus can cure a locked knee, but the operation itself may increase the risk of arthritis in the future…
- The surgical complications listed above can compromise the results of any operations.

The complications just described are the ones most likely to be encountered after knee surgery. By and large they are not serious and only exceptionally do they lead to arthritis, locking of the knee, or amputation. Most are of short duration, lead to minor inconveniences, and resolve uneventfully.

Complications of Anesthesia

(The following is from SFAR, the French Society for Anesthesia)

Knee surgery requires anesthesia, either general or regional, and this itself can be a source of complications.


What are the possible risks and downsides of general anesthesia?

Nausea and vomiting at the end of the operation has become less common with the use of modern techniques and medications. The risk of "aspiration" (passage of food products into the lungs) is extremely rare as long the patient has been compliant and has not eaten or drunk anything prior to the surgery.

A sore throat can ensue from the passage of the "endotracheal" tube during general anesthesia. This same tube can damage teeth, wherefore the importance of informing the anesthesiologist of any fragile tooth. Some pain and redness can occur at the site of the intravenous line. This is usually transient.

The positioning on the operating table can lead to pressure on certain nerves. This can result in numbness or even motor weakness of the effected limb. This is also usually transient. In the hours following surgery, patients may have a temporary, partial memory loss and decreased ability to concentrate. Unpredictable, serious complications such as a major allergy, cardiac arrest or asphyxiation are exceedingly rare. They occur in every few hundred thousand cases.

What are the risks and downsides to regional anesthesia?

Headaches can occur and may last a few days. These require bedrest and often resolve spontaneously.

Inability to urinate occasionally occurs and may require a very temporary catheter.

Pain at the site of the regional anesthesia (e.g. lower back) can occur.

Regional anesthesia involves an injection in and about the spine, and, in certain cases may need to be repeated two or more times before adequate anesthesia is obtained.

Certain narcotics such as morphine can lead to itching.

Very rarely, there can be a temporary compromise of sight or hearing.

As with general anesthesia, there can be transient compromise of memory and concentration.

More worrisome complications such as convulsions, cardiac arrest, paralysis, or loss of sensation are exceedingly rare.A few scattered cases have been described whereas hundreds of thousands of regional anesthetics are administered yearly without serious complications.