Sham surgery (placebo surgery) is a faked surgical intervention that omits the step thought to be therapeutically necessary.
In clinical trials of surgical interventions, sham surgery is an important scientific control. This is because it isolates the specific effects of the treatment as opposed to the incidental effects caused by anesthesia, the incisional trauma, pre- and postoperative care, and the patient's perception of having had a regular operation. Thus sham surgery serves an analogous purpose to placebo drugs, neutralizing biases such as the placebo effect.
A number of studies done under IRB-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.
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.
In 1939 Fieschi introduced internal mammary ligation as a procedure to improve blood flow to the heart. Not until a controlled study was done two decades later could it be demonstrated that the procedure was only as effective as the sham surgery.
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 holes into the skull demonstrated such interventions ineffective and possibly harmful. Subsequently, over 90% of surveyed investigators believed that future neurosurgical interventions (i.e. gene transfer therapies) should be evaluated by sham-controlled studies as these are superior to open-control designs, and have 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 only or enter the brain. In March 2013 a sham surgical study of a popular but biologically inexplicable venous balloon angioplasty procedure for multiple sclerosis showed the surgery was no better than placebo.
Moseley and coworkers studied the effect of arthroscopic surgery for osteoarthritis 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. In a recent study it was found, that arthroscopic partial meniscectomy does not offer any benefit over sham (or fake) surgery in relieving symptoms of knee locking or catching in patients with degenerative meniscal tears.
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.
- Stolberg SG (April 25, 1999). "Sham Surgey Returns as a Research Tool". The New York Times. Retrieved May 1, 2009.
- Cobb LA, Thomas GI, Dillard DH, Merendino KA, Bruce RA (1959). "An evaluation of internal-mammary-artery ligation by a double-blind technic". New England Journal of Medicine. 260 (22): 1115–8. doi:10.1056/NEJM195905282602204. PMID 13657350.
- Kim SY, Frank S, Holloway R, Zimmerman C, Wilson R, Kieburtz K (September 2005). "Science and Ethics of Sham Surgery. A Survey of Parkinson Disease Clinical Researchers". Arch Neurol. 62 (9): 1357–60. doi:10.1001/archneur.62.9.1357. PMID 16157742.
- Moseley JB, O'Malley K, Petersen NJ, Menke TJ, Brody BA, Kuykendall DH, Hollingsworth JC, Ashton CM, Wray NP (2002). "A controlled trial of arthroscopic surgery for osteoarthritis of the knee". New England Journal of Medicine. 347 (2): 81–8. doi:10.1056/NEJMoa013259. PMID 12110735.
- Sihvonen R, Englund M, Turkiewicz A, Järvinen TL: Mechanical Symptoms and Arthroscopic Partial Meniscectomy in Patients With Degenerative Meniscus Tear: A Secondary Analysis of a Randomized Trial. Ann Intern Med. 2016 Feb 9