Preliminary research suggests that impaired balance in patients with diabetic peripheral neuropathy (DPN) may improve with proprioceptive stimulation from foot orthoses.
Postural instability is common in patients with diabetic neuropathy, said David Levine, DPM, CPed, who is in private practice in Frederick, MD.
“Balance issues occur as we age, but add in diabetes and other medical conditions and balance becomes even more of an issue,” he said.
There have been concerns that the soft materials used in orthoses often prescribed for patients with DPN may reduce somatosensory input on the foot’s plantar surface and reduce postural stability. But a study from the Netherlands suggests this concern may be unwarranted.
In the September 2007 Prosthetics and Orthotics International, researchers from the University of Groningen in the Netherlands published a study assessing 30 patients with DPN (aged 37-82 years) and 10 healthy controls (aged 27-51 years).
Postural stability was evaluated in a shoe without insoles, a shoe plus flat insole with a low Shore A value (15°), and a shoe plus flat insole with a higher Shore A value (30°). Researchers performed assessments in four conditions: eyes open, eyes closed, and these conditions with and without a dual task (mental arithmetic).
Patients had significantly increased postural instability compared with controls (p < 0.05) and with eyes closed compared with eyes open (p < 0.05); the latter finding was more pronounced in patients with DPN. No significant effects were found for insoles or dual tasks for the total group or for insoles in the DPN group.
Another study from the same institution published in the July 2008 Journal of Rehabilitation Research & Development investigated the effects of vibrating insoles on standing balance in 17 patients with DPN and 15 individuals without diabetes or impaired sensation.
Participants stood for 60 seconds on vibrating insoles placed on a force plate. Vibrations were not perceptible to participants. Investigators assessed effects of the insoles under four conditions: eyes open, eyes closed, and these conditions with and without a dual task.
Vibrating insoles improved standing balance in subjects with neuropathy when attention was distracted, the condition most often associated with impaired balance and falls in real-world settings. Researchers found no effects of vibration on balance in healthy participants.
A 2006 Boston University study published in the Annals of Neurology found that vibrating insoles significantly reduced postural sway in 15 patients with diabetic neuropathy, 15 patients with stroke, and 15 healthy elderly control subjects.
The evidence is still preliminary, however, a point noted in a review published in July in the Journal of Geriatric Physical Therapy. Researchers at Children’s Hospitals and Clinics of Minnesota reviewed six articles on interventions, including vibrating insoles, used to minimize balance dysfunction in people with DPN. Apart from lower extremity strengthening exercises, which received a fair recommendation, all interventions lacked evidence to either support or disprove their effect on balance in DPN.
Some practitioners aren’t sure that the value of orthoses for patients with DPN involves balance, which, in addition to reduced proprioception, can be affected by vision problems, weakness, or medication side effects.
“I see orthoses as more of an aid for protection, cushioning, and prevention of diabetic foot complications rather than for helping balance,” said Dennis Janisse, CPed, president and CEO of National Pedorthic Services in Milwaukee, WI.
Orthopedic issues may also be balance mediators that can be addressed orthotically.
“Combinations of leg length discrepancy and peripheral neuropathy are issues that shouldn’t be overlooked. Many of these patients may also have had a joint replacement, which quickly adds a lot of factors that can make ambulating even a short distance a challenge,” Levine said.
Footwear selection, he noted, can also affect balance.
“Assessing footwear is an important step to take before starting to think about orthotics,” Levine said. “Prescribing a shoe with a wider base of support might be all that’s necessary. If an orthotic device is made for a poorly supportive shoe or a shoe that doesn’t fit well, the orthotic won’t help. The shoe, after all, is the ultimate orthotic.”
Sponsored by an educational grant from Levy & Rappel