Minimally invasive surgery “markedly reduces” postoperative infection risk

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Minimally invasive surgery is generally considered to reduce blood loss and preserve surrounding
tissue, among other benefits. There is a dearth in the literature, however, on the association
between minimally invasive techniques and surgical site infections.

Research published in the Asian Spine Journal has found very low rates of postoperative infection following minimally invasive spinal surgery in comparison to open surgery.

“One of the worst complications of any orthopaedic or spinal operation is surgical site infection,
which can have devastating consequences,” lead author Arvind Kulkarni told Spinal News
International. “Hypothetically, it appears that the incidence of surgical site infection should be
minimal in minimally invasive surgery compared to open surgery—the reasons being lesser soft
tissue dissection, lesser destruction of tissues, lesser exposure of surface area to pathogens etc.”

Records from 1,043 patients (52% male, 48% female; 52.2 years average age) undergoing tubular
discectomies, decompressions and transforaminal interbody fusions at the Bombay Hospital and
Medical Research Centre in Mumbai, India, from January 2007 to January 2015 were used to find the
frequency of surgical site infection over the 12 months following each procedure.

Three patients from the cohort developed surgical site infection (0.29%; 0% for noninstrumented
surgeries, 1.07% for instrumented surgeris), all of whom had risk factors for infection (two patients
had diabetes and one was obese). In each case, potential causes for infection were described. One
surgery was particularly long, one involved the accidental puncture of the abdomen with a
guidewire, and one required the use of a power drill to create tracks for pedicle screws due to tough
bone.

The authors performed a literature review using a MEDLINE search to find reported rates of
infection in open surgery for comparison. The results they discovered varied from 0.7% to 16%
surgical site infection rates following open surgery. This makes for a 2 to 16 fold increase in
postoperative infection in comparison to the results for minimally invasive procedures in the present
study.

The researchers also used hospital records to work out the financial burden of the direct costs of
surgical site infection. “Infections after open spine surgery increase the health care utilisation cost
four-fold,” the authors write, commenting on that reported in the literature. Reporting on their
centre’s own results, the researchers note that the additional direct costs of surgical site infection
per 100 minimally invasive procedures was only US$2,678. This makes minimally invasive
procedures, they argue, financially appealing in comparison to open surgery, in terms of additional
healthcare utilisation costs.

The research was limited in a number of ways. Because if was a single-centre trial, the authors note,
longer operative times and steep learning curves associated with minimally invasive surgery might
lead to different results at different centres, depending on the experience of surgeons. Furthermore,
the lack of a control group of comparable open procedures at the institution weakens the groups’
conclusions. The tiny number of infections in the series, too, means that “a valid conclusion
regarding the risk factors cannot be extracted” and “do not represent every situation that could
arise in patients with surgical site infections.”

Future research efforts should be focused on expanding the application of minimally invasive
techniques, Kulkarni told Spinal News International, “The next steps should be more research and
innovation to make minimally invasive surgery possible for all indications in spine surgery, more
research to develop newer powerful antibiotics, and more efforts to stop antibiotic abuse and
standardise protocols for effective and safe use of prophylactic antibiotics.”

The authors conclude, in spite of the study’s limitations, that the “minimally invasive technique
markedly reduces the risk of postoperative infection when compared to other large open spine
surgery series.” As well as offering lower risk of infection, minimally invasive spinal surgery “can be
an effective tool to minimise hospital costs.”

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