Risks and complications


When dealing with adverse outcomes, it needs to be established that all questions, have been answered, options discussed and risks and complications of reasonable occurrence have been made known - the strangest or most unusual thing imaginable has probably happened to someone, somewhere so all possibilities cannot be discussed.In the strictest definition, risks are any situation that exposes one to danger and a complication is anything that has made something more difficult. This definition can be very broad and sometimes it may not be very clear if an occurrence is a complication or not. The obvious implication of this is medico-legal liability which, while an important consideration should not get in the way of good doctor-patient relations. As a lecturer and convener on open communication (risk management) workshops and as the clinical director of a tertiary orthopaedic referral center, the author has gathered some insights in this regard. Feelings of desertion after an adverse outcome are a major contributor to litigious intent (Hickson1994). Patients want to be informed of errors (Hobgood et al 2002, Gallagher et al 2003). Approximately 10% of patients admitted to hospital experience an adverse event but two thirds of claims come from patients who experience adverse outcomes not related to error (Studdert 2000, Localio 1991, Bismark 2006).

General Risks

The general risks relevant to any procedure under general or regional (eg. spinal anesthesia) include heart problems, lung problems, stroke and blood clots. Any of these are potentially fatal and the surgeon would usually defer to the anesthesiologists’ assessment of the risk of the procedure. In general if the patient’s premorbid state is healthy these risks are small.

Heart problems

When the patient goes under anesthesia, there can be blood loss or blood pooling because the circulation slows down. Therefore a patient who has a borderline cardiac problems can sustain a heart attack because this slowed down circulation is not able to maintain sufficient flow to the heart.

Lung problems

When a patient is under anesthesia, the normal protective reflexes like coughs are bypassed and the patient may not be able to breathe sufficiently well. This can result in reduced oxygen in the blood leading to effects on the brain and heart.


Both the blood flow and oxygen carrying capacity of the circulatory system can be affected leading to a patient sustaining a stroke under anesthesia.

Blood clots

Blood clots in the venous system (deep vein thrombosis) can happen when a patient is in a resting position for a long period of time. Such blood clots are mostly harmless but can occasionally cause the blood vessels to become dysfunctional (post-phlebitic syndrome) or travel to the lungs and cause death (pulmonary embolism).

Specific Risks

Some risks that are common to most orthopedic operations are blood loss, infection, blood clots, nerve and vessel injury and joint stiffness.

Blood loss

As a rule all operations entail some blood loss. Tourniquet use can minimize this but excessive tourniquet use can cause muscle and nerve injury. Blood transfusions are often required if hemoglobin levels drop below 10g/dl in unwell patients during surgery. Typical primary knee and hip surgery can lose 1.5l of blood and often fitness to undergo this surgery is dependent on the ability to lose this amount of blood.


In most elective operations the risk of surgery is 1-2 % in orthopaedics. In high risk situations like resections around the buttocks, surgery after radiation and surgery for infection, the risk of infection is much higher. Surgery involving bulk allografts can be as high as 10% and require long-term suppressive antibiotics as a rule.

Blood clots

As covered above, blood clots or deep vein thrombosis occur whenever blood becomes stagnant, there is vessel injury or blood becomes thick. This Virchow’s triad is quite prevalent in knee and hip surgery and especially so for tumour surgery. The need for anticoagulation needs to be balanced with the need for surgery and therefore in Asians where the risk of blood clots is low, knee surgery is often done without blood thinners but hip surgery often requires blood thinners where the risk of bleeding is low.

Injury to nerves or blood vessels

It should be apparent that any operation around a vessel or nerve runs the risk of nerve or vessel injury. This can be attributable to the surgery itself (eg. if the nerve or vessel is trapped in a scar or tumor) or it can happen when a patient has been lying in an awkward position for too long (eg. Saturday night palsy).

Joint stiffness

Whenever operations are done around a joint, it is necessary for the patient to move the joint vigorously. Often patients have the idea that a physiotherapist or a machine will move the joint for them and then will not move the joint on their own. Such patients will invariably not have a good range of motion. It is important that patients must move their own joints in order to achieve good range.

Very occasionally some patients will develop stiffness in the joint despite good surgical placement of implants or successful surgery to the joints. While most times this is related to inactivity and poor patient motivation in moving the joint, this form of arthrofibrosis can happen despite good effort. This is rare and happens in less than 5 percent of patients.

Failure of surgery

This is a broad term and encompasses all levels of failure which ultimately does not solve the problem. They are usually best discussed in the context of the operation being undertaken.

In arthroplasty surgery, implant failure occurs in a small number of patients. Generally, 95% of patients are still functional at 15 years after surgery– those are pretty good odds.

Persistent pain can happen in the knee after a joint replacement. This can be due to implants being too large, implants being malpositioned, implants being unbalanced or pain being referred to the knee from the hip or spine. It is an uncommon occurrence. In general, if the implants are in good placement then physical therapy and stretching can resolve this issue. The hip and spine should be evaluated. Rarely is the cause a patellar abnormality. Often, if the patella has not been resurfaced at the first surgery this will be offered in a secondary fashion. Personally I have done this very rarely and concede that it provides a poorly reproducible outcome.

Implant loosening can happen after a few years and usually require a revision.

Dislocations of hip replacements are a low risk occurrence but can be common in replacements done after tumor resections about the hip.Fractures around an implant are a risk of implant surgery especially if the implants used are uncemented.