The Spine Journal 11 (2011) 131–132

Commentary

A steep learning curve is a good thing!

Edward C. Benzel, MDa,b,*, R. Douglas Orr, MDb

aDepartment of Neurosurgery, Cleveland Clinic, 9500 Euclid Ave, S40, Cleveland, OH 44195, USAbCenter for Spine Health, Neurological Institute, Cleveland Clinic, 9500 Euclid Ave, S40, Cleveland, OH 44195, USA

Received 15 December 2010; accepted 17 December 2010

COMMENTARY ON: Wang B, L€u G, Patel

DOI of original ar

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Author disclosure

* Corresponding a

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USA. Tel.: (216) 444

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doi:10.1016/j.spinee.2

AA, et al. An evaluation of the learning curve fora complex surgical technique: the full endoscopic interlaminar approach for lumbar disc hernia-tions. Spine J 2011:11:122–30 (in this issue).

According to BusinessDictionary.com, the definition oflearning curve is as follows: ‘‘A graphical representationof the common sense principle that the more one doessomething the better one gets at it. A learning curve showsthe rate of improvement in performing a task as a functionof time (or number of repetitions of the task at hand).’’ Botha steep and shallow learning curves are depicted in theFigure. Let us consider the aforementioned definition oflearning curve and characterization of both the steep andshallow learning curves depicted in the Figure. Clearly, ifone is interested in rapid skill acquisition as manifestedby an objective increase in proficiency following a limitednumber of repetitions, a steep learning curve is desired. Be-cause the rapid acquisition of skills is usually considered tobe desirable, a steep learning curve must be considered ‘‘agood thing.’’

In this issue of The Spine Journal, Wang et al. [1] usea common but incorrect interpretation of the slope ofa learning curve. Although the term ‘‘steep learning curve’’has been widely used to describe procedures that are diffi-cult to learn, such is not correct. As stated, learning curve isa graphical representation derived from the plotting of pro-ficiency as a function of time or the number of repetitions.As a result, a procedure with which one becomes proficientwith a small number of repetitions is, by definition, associ-ated with a steep learning curve. A procedure such as de-scribed by Wang et al., which requires many repetitions

ticle: 10.1016/j.spinee.2010.12.006.

status: not applicable.

s: none.

uthor. Center for Spine Health, Neurological Insti-

c, 9500 Euclid Ave, S40, Cleveland, OH 44195,

-7381; fax: (216) 445-9999.

enzele@ccf.org (E.C. Benzel)

nt matter � 2011 Elsevier Inc. All rights reserved.

010.12.012

of the task at hand for the surgeons to become proficient,is associated with a shallow learning curve. The former isgood. The latter is bad.

A shallow learning curve is reflective of a technicallydemanding task that is somewhat difficult to master. Thisis neither good nor bad. It is simply an indicative of the na-ture of the task being studied and extent to which one must‘‘practice’’ to become proficient. A learning curve, how-ever, that is excessively shallow and prolonged necessitatesthe exposure of multiple patients (while ‘‘practicing’’), inthe case of surgical learning curves, to an increased chanceof complications and, hence, to increased risk to the pa-tients being treated. Therefore, in general, shallow learningcurves are a bad thing.

Wang et al. use the term steep learning curve inaccu-rately because the learning curve they observed is indeedshallow. Regardless of their definition of steep and shallow,the learning curve they observed is not optimal. Further-more, the procedure they studied was not compared withother more conventional techniques. Conventional discec-tomy and microdiscectomy are considered by most to begold standard treatments associated with low risk and mor-bidity and good outcomes. Therefore, the employment oftechniques that are associated with shallow learning curves(with an associated morbidity and risk) and that ultimatelyare not proven to provide a significant clinical advantageover the ‘‘gold standard’’ treatments should be questioned.

So, what have Wang et al. taught us? First, they haveprovided a nice demonstration of objective learning curveestablishment. They have provided a true learning curveanalysis. Second, they have demonstrated that good out-comes can be obtained with the endoscopic interlaminar ap-proach for lumbar disc herniation—apparently as good as‘‘gold standard’’ approaches. Third and finally, they havedemonstrated that imprecise anatomic orientation and

Figure. A plot showing proficiency as a function of number of repetitions.

The upper curve shows a steeper slope, and proficiency is achieved in few

repetitions. The lower, shallower plot represents a procedure that takes

many more repetitions to become proficient.

132 E.C. Benzel and R.D. Orr / The Spine Journal 11 (2011) 131–132

manipulation inside the spinal canal are key factors associ-ated with learning curve aberrations (shallow learningcurve).

Learning curve assessments are critical in this era inwhich new technologies and new clinical procedures areused with an increasing frequency. We must all attempt to

understand the risks associated with shallow learningcurves and step back and contemplate the wisdom of‘‘pushing technology envelopes’’ when conventional proce-dures, which are of proven efficacy and effectiveness, are incommon use and readily accessible. This is not to say that‘‘envelopes’’ should not be pushed. Such ‘‘envelopes,’’however, should be ‘‘pushed’’ by a select few clinicianresearchers—and not by the masses. Learning curve analyses,as performed by Wang et al., are critical in the presentationof such new technologies and procedures in the literature.

If steep learning curves without significant risk to ourpatients cannot be achieved by astute clinician researchers,new technologies and new procedures should, in good con-science, not be introduced in our literature. Moving for-ward, we should perhaps begin demanding learning curveanalyses, such as provided by Wang et al., when newtechnologies and new procedures are submitted forpublication—as a requisite for acceptance. Unless the valueof such a new technology or procedure is evident, a shallowlearning curve may be unacceptable.

Reference

[1] Wang B, L€u G, Patel AA, et al. An evaluation of the learning curve for

a complex surgical technique: the full endoscopic interlaminar ap-

proach for lumbar disc herniations. Spine J 2011;11:122–30.