The Rule of 3 means that it takes 3 stresses on a tissue that can cause it to be injured. When one patient overly pronates (Stress #1), they can injure 27-28 structures (at least they will start complaining). And, each stress can be the most important, and its reversal the most curative, but you do not know which one when you are starting treatment. The body injures weak spots. The Rule of 3 investigation can discover why an area is weak, and the treatment can eliminate this weakness. Some athletes have 3 or 4 weak spots to start that need to be worked on through different injuries in different years or athletic seasons. But with each weak area that we help, we are adding to the years this athlete can participate in a healthy active lifestyle.
I will use 2 examples today for the Rule of 3 that are very common in a Podiatric practice. Both of these injuries are commonly tied, and thus treated, with our first stress of over pronation. These injuries involve the tibial sesamoid and the posterior tibial tendon. With over-pronation, the medial column of the foot and ankle are stressed. The Rule of 3 teachs us to work on the over-pronation but look for several other stresses to the injured area that we can treat.
First, let's look at the tibial sesamoid. The patient developed it in overuse with excessive uphill running while training for the upcoming cross country season. Gait evaluation revealed the over-pronation (Stress #1) only in running, and not walking. Therefore, as the patient healed with a CAM walker, orthotic devices were being made for his return to running in 3-4 months. One of my Golden Rules of practice (a rule that is yours that you never want to ignore) is that any bone pain can be caused by poor bone health. A low Vitamin D level was found causing transient osteopenia (Stress #2). The third stress found was in the high arched nature of his foot and the pressure of a plantar flexed first metatarsal (Stress #3). So, even though the pronation needed to be corrected, a dancer's pad (aka reverse Morton's extension) was needed to even the alignment across the metatarsal heads so the first metatarsal head did not take as much pressure. This proved to be quite standard for stresses: global biomechanics (over pronation), local biomechanics (plantarflexed first metatarsal), and general health issues (vitamin D deficiency).
Plantarflexed First Metatarsal makes the sesamoid more plantarly exposed. Dancer's padding can off weight the first by spreading the weight more onto the 2nd through 4th metatarsals.
The next example I will use is the posterior tibial tendon. Over-pronation can put large demands on the posterior tibial tendon to decelerate subtalar joint pronation (Stress #1). Our custom orthotic devices, along activity modifications and possibly complete rest in a CAM walker, can reduce symptoms perfectly. But what are other stressors that commonly need to be fixed? One stress on the posterior tibial tendon is direct weakness in the tendon more than just that it got fatigued during running (Stress #2). And, how does achilles weakness possibly strain the posterior tibial tendon? A huge number of my athletes do not have ideal achilles strength. So, if the achilles fatigues in running, all of the other muscles that plantar flex the ankle joint will be recruited to help the achilles (Stress #3). So, in the workup of posterior tibial pain, think about over-pronation, think about post tibial strength, and think about achilles strength. If you find all 3, it may be one, two, or three that need to be corrected before the patient feels better. And, by correcting these weak spots, you are minimizing their possibility of re-injury.
Remember to test the strength of the posterior tibial tendon separate of the anterior tibial tendon. The posterior tibial tendon is tested with the ankle plantarflexed, one hand stabilizing laterally, and then the patient asked to push medially against your hand while you slowly push laterally. The Anterior Tibial tendon is tested ankle in neutral position (more dorsiflexed) and the foot pushed medially.
