Surgery: The Machine Analogy Misconception

30 May 2021

Surgery as a treatment option brings up a lot of mixed emotions amongst patients. It is often the last resort. Something that carries with its risks and pain but should definitely work. This ties in with our sense that something complicated and riskier should be better than something simpler and risk-free. This creates an unrealistic expectation of surgical procedures to deliver miracles. Recently, Spine discuss several articles on how back surgeries fail.

Of course, as with most things, there are always two sides of the story. There will be surgical cases where too much was promised, and too little is delivered. But there is often too a case of the patient simply expecting too much either refusing to understand the risks and possible outcomes or simply (which often I believe is the case) the patient not having a firm enough grasp of the situation and implications.

As this is a musculoskeletal site, lets focus on orthopaedic surgeries as an example.

What Does Surgery Generally Achieve?

Most of the surgeries, do one of the four things below.

  1. The removal of some part that causes an obstruction, impediment or impingement – for example – disc bulges (Removal)
  2. The replacement of some part that has failed or deteriorated for examples spinal discs (Adding)
  3. The strengthening of some part, for example – adding cement into vertebral body. (Enhancing)
  4. The weakening of a part, for example, tight muscles or severing inflamed tendons in the wrist (Weakening)

Complicated surgeries will combine two or more of these things. All of this seems simple enough. So where do we go wrong? Our tendency to over simplify the situation.

Comprehension Through Analogy: How It Misleads Us

One of our most common tool we reach for to understand something is comprehension through analogy. We use somewhat similar alternative to explain key concepts. Like the human heart is the “engine” for the human body. The eyes are like video cameras. This helps narrows the gap in our understanding of new complex idea or concept. Unfortunately, analogies can sometime mislead us.

Human Parts Are Not As Easily Replacable

One common area is spinal disc replacement (Removal and Adding). The new hi-tech disc doesn’t work as well as their original human discs. Patients are often surprised at that reality. Unlike, cars or computers where parts are easily replaceable. In fact with very specific numbered replacements parts. Parts in machine are relatively simple and have very precise functions and operated within a very specific range of conditions.

Not so for the human body. In our human body, each part usually have several functions and interacts with the rest of the body in very unique ways. This helps us to be adaptable to our surroundings. Currently, no replacement spinal disc has the same degree of freedom movement as a real human spinal disc. This implies a slight impairment to your body’s actual biomechanics. Something and somewhere else will adapt to compensate for the slightly reduced degree of movement.

Fixing The Faulty Part May Not Address The Problem

Fixing the faulty part does fix the underlying problem. In a machine when a part fails, it is usually because of poor quality rather than the machine operating beyond its specifications (thought that does happen. In fact, some machines are designed with some parts to be the designated failure points so that it is easily replaced and cheaply). Replacing a poor quality part if easy and usually eliminates the problem.

However, in the human body, parts fail not because of poor quality but often somehow it is not being used in the correct manner. Like sitting a poor posture leading to back pain. Solving the pain is only a short term solution if the external cause – poor posture is not corrected. This situation occurs less frequently for machine. Machines are usually used for the purposes they are designed for. If your coffee maker is crushed because you used it as a door stopper is not something covered under the manufacturer’s warranty.

While some machines are large and more difficult to build (not something you can hammer out at your workbench) doesn’t mean they are complex by any means. At least not relative to human body. Complex machines are far more difficult to repair and a point of failure can have far reaching and heavy consequences. Something that is beginning to show up in complex systems that we are building. So use analogies carefully. They help us understand a new complex topic but remember it is no substitute to actual understanding. Take you time and find out as much as you can about your pain and condition, and especially the solutions proposed.