Researchers at the University of Illinois recently published a study that adds to the existing findings on the negative effects of ankle-foot orthoses (AFOs) on balance and postural control. Researchers continue to validate that semi-rigid, non-articulated AFO devices will compromise balance, particularly when patients wear the devices bilaterally.
The study investigated the effects of semi-rigid, non-articulated AFO devices during several tests of balance in patients wearing AFOs bilaterally.1 Two of the clinical tests utilized the SMART Balance Master® (NeuroCom, USA) computerized force platform to perform the modified Clinical Test of Sensory Interaction on Balance and the limits of stability test. Another clinical test was the common Functional Reach Test, which one can easily perform in the office setting with a tape measure. Researchers noted a significant negative impact on balance when the patients wore the AFO devices in each of the clinical tests.
The authors speculated that the compromise in balance performance caused by the non-articulated AFO devices was due to restriction of proprioceptive input from the muscles, tendons and other tissues around the ankle joint.1 The researchers point out that by design, AFOs limit the motion of the ankle joint in one or more planes. They speculate that this limitation of motion has significant effects on balance, particularly in those patients who are already compromised. The researchers observed that “when active ankle joint movements were constrained by the AFOs … the center of gravity sway was significantly larger as compared to the conditions with no AFOs.” The study emphasized that bilateral AFO therapy magnified the negative effects of these devices on proprioception and balance control.
In terms of clinical implications, the researchers point out that semi-rigid non-articulated AFO devices negatively affected the ability to move, lean or reach. This could affect functional tasks such as picking up an object from a shelf, initiation of gait and other essential activities.1
The authors add that these negative effects of restricting ankle motion were also recently validated in a published study from Hadadi and colleagues.2 In this investigation, researchers measured a continuous decline in postural control when comparing soft ankle braces to a more restrictive semi-rigid brace. Despite how thin or flexible the plastic material is, one can expect a solid shell, non-articulated AFO to compromise proprioception and balance.
These two studies validate a position I have taken regarding the prescription of bilateral, non-articulated AFO devices to elderly patients at risk of falling (see http://www.podiatrytoday.com/blogged/still-looking-documentation-afos-ef...  and http://www.podiatrytoday.com/preventing-falls-elderly-where-dpms-can-hav...  ). To this date, no study has validated an AFO to improve balance in non-neurologic impaired elderly patients. Rather, numerous peer-reviewed published studies have revealed the opposite treatment effect.3
While AFOs have significant potential benefit to treat neurologic deficits and musculoskeletal injury, practitioners should be aware of the potential shortcomings of these devices and take appropriate measures to minimize the negative effects on balance. Dispensing bilateral AFOs has been a rare practice in podiatric medicine and other specialties.4 The most common pathologies for which podiatric physicians prescribe AFOs — adult-acquired flatfoot, dropfoot, and degenerative joint disease of the ankle and hindfoot — present unilaterally in most cases. As Panwalkar and Aruin point out, there is little need to brace the contralateral limb for the most common musculoskeletal conditions and this practice will only further compromise balance.1
Studies have shown that articulated devices are less likely to have negative effects on balance.3 Articulated AFOs preserve ankle motion and are less likely to inhibit the important proprioceptive input from the ankle joint mechanoreceptors and feedback from the muscle/tendon stretch receptors in the leg. If practitioners prescribe non-articulated devices, they should consider dispensing a cane to improve stability and provide proprioception from the hand. Research has shown the use of a cane improves balance significantly when there is preexisting compromise.5
1. Panwalkar N, Aruin AS. Role of ankle foot orthoses in the outcome of clinical tests of balance. Disabil Rehabil Assist Technol. 2012 Oct 19. [Epub ahead of print]
2. Hadadi M, Mazaheri M, Mousavi ME, Maroufi N, Bahramizadeh M, Fardipour S. Effects of soft and semi-rigid ankle orthoses on postural sway in people with and without functional ankle instability. J Sci Med Sport. 2011;14(5):370-5.
3. Ramstrand N, Ramstrand S. The effect of ankle-foot orthoses on balance-a systematic review. Official Findings of the State–of-the-Science Conference. J Prosthet Orthot 2010; 22(10):4-23.
4. Rubin G, Cohen E. Prostheses and orthoses for the foot and ankle. Clin Podiatr Med Surg. 1988; 5(3):695-719.
5. Richardson JK, Aston-Miller JA. Peripheral neuropathy. An often-overlooked cause of falls in the elderly. Postgraduate Medicine. 1996; 99(6):161-172.