Takeaway: Many references (including those online) are updating their facts to correctly identify retinacula as a thickening of the fascia of the leg.

“I hate walkers,” muttered Dr. Gary Chimes, my friend and physiatrist. “The only thing they’re good for is making you walk like an elderly person.”

Gary is right. You know the posture: upper body hunched forward, head looking at the ground, too much continuous pressure through the arms and shoulders. Then there’s the lower body. Are the hips moving? Not so much. Often the knees are flexed, shortening the tibialis anterior and hamstrings. Most importantly, and of particular interest, is the shuffling of the feet. Is there any plantar and dorsiflexion happening? If there is, it’s extremely limited and potentially limiting long-term recovery because those last items, the flexor retinacula at the ankles, play a much bigger role in walking than most people realize. 

Understanding the Retinacula

Presented in the anatomy texts as separate bands of tissue, retinacula are decidedly not separate or discrete structures. They are a thickening in the crural fascia, the much larger fascial sheath of the leg. While it’s quite possible to dissect the foot and ankle and make it look exactly like a textbook—I’ve done it myself—reviews of the literature in dozens of papers and myriad textbooks show no clear consensus on the exact size and shape, or topography if you will, of retinacula. In fact, sometimes the individual details vary. 

What is good is that today many references (including those online) are updating their facts to correctly identify retinacula as thickening of the fascia of the leg. What is less-than-good is that they are still referred to physiologically as both a tendon stabilizer and pulley system for the tendons of the tibiotarsal joint. While it is a matter of record that injuries to retinacula, like tears, can lead to subluxations/dislocations of the tendon, these are more extreme injuries than the typical ankle strains and sprains. 

The pulley model goes all the way back to Andreas Vesalius in Padua, Italy, circa 1543. As much as there is to admire and be grateful for regarding Vesalius, this model is past its expiration date. So perhaps it’s fitting that a group led by Carla Stecco at the University of Padua in 2010 performed a study on retinacula that has been instrumental to our change in thinking.

The group used dissection, histological and immunohistochemical analysis, and MRIs to examine seven healthy ankles and 17 with sprains in their history. Overall, the area known as the retinaculum was easily identifiable in all subjects due to the aforementioned thickening. The retinaculum has three layers of collagen fibers that alternate in orientation and are separated by a thin layer of loose connective tissue. This is in keeping with the overall histology of the entire crural fascia, but a crucial difference is that in the area of the retinaculum, the collagen is thicker and the loose connective tissue thinner. It’s so thin it was concluded that any effect on tendon stability would be minimal at best, and too weak to function like a pulley.¹

From a topographical anatomy standpoint, it may be more useful to imagine retinacula as forming a series of porticos, or a corrugated roof, that houses the tendons, allowing them to slide underneath without bowing, slackening, or becoming entangled with their neighbors. 

Even more interesting is that retinacula were not truly separable from the entire crural fascia and the deep fascia of the foot and lower leg. With such profound connections to their associated epimysium of the muscles of the lower leg, including the deep posterior compartment, a reassessment was in order. Remember, the majority of free nerve endings that transmit proprioceptive information are found in both the superficial fascia and the muscle-wrapping layer of the epimysium. This suggests a strong theory that the primary function of retinacula is to transmit proprioceptive information from the ankle to the knee, the hip, and the rest of the body with every step you take.

Mobilize

Armed with this knowledge, let’s go back to our elderly person with the walker and perform a pathological hot take. Trust me, it’s a logical one.

Combining our new understanding of the function of retinacula with our knowledge that the purpose of hyaluronan in the epimysial layers is to keep things sliding and the free nerve endings happy (see “Hyaluronan Makes the Body Glide,” Massage & Bodywork May/June 2023, page 76), it is easy to hypothesize that any long-term use of a walker (3 months or more) is going to create densifications within the fascia ankle and other aspects of the foot and lower leg because the person using the walker is going to be shuffling their feet. This decreases the stimulating shearing motions necessary for the fasciacytes to keep the hyaluronan smooth and slick. It also disrupts the feedback loop from the ankle to the rest of the body.

Now, I’m not saying we should do away with walkers. Rehab devices have their purpose as long as we don’t get too dependent on them. That obviously creates a feedback loop that only serves to further decrease proprioception and encourage further dependence. 

What is vital is to do manual interventions that increase ankle mobility in all ranges of motion. And be sure the person we’re treating understands the importance of this for their recovery. I also encourage them to do regular, functional proprioceptive exercises daily. Simple things, like slowly pedaling the feet before getting out of bed or a chair, can reap excellent long-term benefits. As their confidence improves, I show them how to work with yoga straps to provide resistance as well as safe, self-assisted stretching for the whole leg to encourage improved proprioceptive relationships throughout the crural fascia. There is also taping, which in this instance is thought to promote proper collagen reformation.

Of course, these strategies will work well with anyone recovering from an ankle injury. As always, work within individual limitations and resist the urge to do too much too fast. Daily mindful efforts can have them putting their best foot forward in no time. 

Note

1. Carla Stecco et al., “The Ankle Retinacula: Morphological Evidence of the Proprioceptive Role of the Fascial System,” Cells Tissues Organs 192, no. 3 (2010): 200–210, https://karger.com/cto/article-abstract/192/3/200/90946/The-Ankle-Retinacula-Morphological-Evidence-of-the.