Sham surgery is a faked operative intervention that omits the step thought to be therapeutically necessary. In controlled studies sham surgery is performed in the control population to assess the effect of the intervention under study by neutralizing the placebo effect

Placebo effect

Placebo effect may refer to:* Placebo effect, the tendency of any medication or treatment, even an inert or ineffective one, to exhibit results simply because the recipient believes that it will work...

 and reducing bias

Bias

Bias is an inclination to present or hold a partial perspective at the expense of alternatives. Bias can come in many forms.-In judgement and decision making:...

. Contrary however to a placebo, typically exemplified by the inert "sugar pill", sham surgery involves a real surgical intervention

Surgery

Surgery is an ancient medical specialty that uses operative manual and instrumental techniques on a patient to investigate and/or treat a pathological condition such as disease or injury, or to help improve bodily function or appearance.An act of performing surgery may be called a surgical...

 to compensate for the effect of anesthesia

Anesthesia

Anesthesia, or anaesthesia , traditionally meant the condition of having sensation blocked or temporarily taken away...

, the incisional trauma, and pre- and postoperative care and to maintain the illusion of a regular operation. Thus sham surgery has an inherent risk and conflicts with the ethical principle of primum non nocere

Primum non nocere

is a Latin phrase that means "First, do no harm". The phrase is sometimes recorded as .Nonmaleficence, which derives from the maxim, is one of the principal precepts of medical ethics that all medical students are taught in medical school and is a fundamental principle for emergency medical...

.

Human research

The placebo-controlled trial is the gold standard of medical research. Therefore, when testing results of a surgical procedure, sham surgery serves as the intervention in the control population. However, the use of sham surgery in human research is controversial as it places high ethical and high research standards into conflict. Such surgery has the potential to harm the subject, however, alternative research designs without sham surgery are scientifically less rigorous. Proponents argue that surgical interventions need to be tested as critically as medical interventions. Because of the ethical concerns, sham-operated controlled studies are rarely performed in humans.

A number of studies done under IRB

Institutional review board

An institutional review board , also known as an independent ethics committee or ethical review board , is a committee that has been formally designated to approve, monitor, and review biomedical and behavioral research involving humans with the aim to protect the rights and welfare of the...

 approved settings have delivered important and surprising results. With the progress in minimally invasive surgery sham procedures can be more easily performed as the sham incision can be kept small similarly to the incision in the studied procedure.

Examples

In a number of situations, sham-controlled interventions have identified interventions that are useless but had been believed by the medical community to be helpful based on studies without the use of sham surgery. Thus in 1939 Fieschi introduced internal mammary ligation as a procedure to improve blood flow to the heart. Not until a sham-controlled study was done two decades later could it be demonstrated that the procedure was ineffective. In neurosurgery, cell-transplant surgical interventions were offered in many centers in the world for patients with Parkinson disease until sham-controlled experiments involving the drilling of burr

Burr (cutter)

Burrs are small cutters used in die grinders, rotary tools or dentist's drills. The name may be considered appropriate when their small sized head is compared to that of a seed of the burr fruit or the teeth compared to a metal burr.To maintain the correct surface speed and cutting conditions...

 holes into the skull

Human skull

The human skull is a bony structure, skeleton, that is in the human head and which supports the structures of the face and forms a cavity for the brain.In humans, the adult skull is normally made up of 22 bones...

 demonstrated such interventions ineffective and possibly harmful. Subsequently over 90% of surveyed investigators believed that future neurosurgical interventions (ie. gene transfer therapies) should be evaluated by sham-controlled studies as these are superior to open-control designs, and half found it unethical to conduct an open-control study because the design is not strong enough to protect against the placebo effect and bias. Kim et al. point out that sham procedures can differ significantly in invasiveness, for instance in neurosurgical experiments the investigator may drill a burr hole to the dura mater

Dura mater

The dura mater , or dura, is the outermost of the three layers of the meninges surrounding the brain and spinal cord. It is derived from Mesoderm. The other two meningeal layers are the pia mater and the arachnoid mater. The dura surrounds the brain and the spinal cord and is responsible for...

 only or enter the brain.

In a classic experiment in orthropedic surgery Moseley and coworkers studied the effect of arthroscopic surgery for osteoarthritis

Osteoarthritis

Osteoarthritis also known as degenerative arthritis or degenerative joint disease, is a group of mechanical abnormalities involving degradation of joints, including articular cartilage and subchondral bone. Symptoms may include joint pain, tenderness, stiffness, locking, and sometimes an effusion...

 of the knee establishing two treatment groups and a sham-operated control group. They found that patients in the treatment arms did no better than those in the control group. The fact that all three groups improved equally points to the placebo effect in surgical interventions.

Ethical considerations

While some ethicists reject sham-surgery in controlled trials, others maintain that such trials are ethically acceptable but should conform to certain restrictions. Such restrictions include that the research question is important and cannot be answered by other forms of research, further the risk of the sham procedure should be kept as minimal as possible and the informed consent

Informed consent

Informed consent is a phrase often used in law to indicate that the consent a person gives meets certain minimum standards. As a literal matter, in the absence of fraud, it is redundant. An informed consent can be said to have been given based upon a clear appreciation and understanding of the...

needs to be appropriate with subjects being aware of the risks and that they may receive placebo surgery.

Animal research

Sham surgery has been widely used in surgical animal models. Historically, studies in animals also allowed the removal or alteration of an organ; using sham-operated animals as control, deductions could be made about the function of the organ. Sham interventions can also be performed as controls when new surgical procedures are developed.