Jul-09
Study Cites Link Between Higher Triglycerides And Diabetic Neuropathy
By Brian McCurdy, Senior Editor
A recently published study in Diabetes suggests a correlation between elevated triglyceride levels and diabetic neuropathy, lending credence to the idea that hyperlipidemia is a factor in the progression of diabetic neuropathy.
The study involved 427 patients with diabetic neuropathy. Researchers analyzed patients’ sural nerve myelinated fiber density (MFD), nerve conduction velocities, vibration perception thresholds, clinical symptom scores and visual analogue scale for pain.
The study defined a loss of greater than or equal to 500 fibers/mm2 in sural nerve MFD over 52 weeks as progressing diabetic neuropathy. A MFD loss of less than or equal to 100 fibers/mm2 during the same time interval signified non-progressing neuropathy, according to the study.
At the 52-week follow-up, the cohort with progressing neuropathy demonstrated a 25 percent decrease in MFD from baseline while those with non-progressing neuropathy remained unchanged, according to the study. Researchers added that among all the variables they tested, elevated triglycerides and decreased peroneal motor nerve conduction velocity at baseline had a significant correlation with a loss of MFD at 52 weeks.
The study authors concluded that in patients with mild/moderate diabetic neuropathy, there was a correlation between elevated triglycerides and MFD loss, which was independent of disease duration, age and control of diabetes. Researchers say the study results suggest that hyperlipidemia is “instrumental” in the progression of diabetic neuropathy.
A Closer Look At The Possible Impact Of Triglycerides
David Armstrong, DPM, PhD, says monitoring triglyceride levels will not be effective in identifying the day-to-day progression of diabetic neuropathy. However, he says the study data do appear to indicate that the presence of higher triglycerides signifies an elevated risk of developing neuropathy as well as a higher risk of the condition becoming worse.
In regard to lowering triglyceride levels, the most effective methods are likely the same as those for lowering the risk of other cardiovascular events, according to Dr. Armstrong, a Professor of Surgery and Director of the Southern Arizona Limb Salvage Alliance (SALSA) at the University of Arizona College of Medicine in Tucson, Ariz. He says a healthy diet, certain statins, omega 3 fatty acids and fibrates might be helpful in reducing triglycerides.
Anthony Yung, DPM, notes the Diabetes study raises awareness of managing the other aspects of the disease process in patients with diabetic neruropathy and not just with regards to hyperglycemia. He emphasizes that diabetic neuropathy develops from multifactorial causes and most treatments have a relatively poor success rate of 30 to 60 percent.
“Elucidating the underlying cause of one person’s diabetic neuropathy, whether it be hyperglycemia or hypercholestermia, would be an exciting step in the treatment of diabetic neuropathy and perhaps lead to better treatment outcomes,” says Dr. Yung, who practices at Kitsap Podiatry and at Harrison Memorial Hospital, both in Silverdale, Wash.
Dr. Armstrong feels that further research should investigate the specific causal link between diabetic neuropathy and triglycerides. He says studies should answer the question of whether inflammation and oxidative stress are involved in the equation, and if both are related factors.
Dr. Yung says the Diabetes study is a data set analysis and a prospective study could further validate these findings by specifically looking at the effect of triglycerides on diabetic neuropathy.
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How Does Low-Dye Taping Affect Plantar Pressure?
By Lauren Grant, Editorial Assistant
A recent study published in BMC Musculoskeletal Disorders examines the effects of low-Dye taping on patients with excessive pronation during and following mild exercise sessions.
The study followed 12 patients who had excessive pronation. Patients walked for 10 minutes at a normal pace while researchers used an F-Scan (Tekscan) to record patients’ plantar pressure at four different points of the session. The study found that the only significant difference immediately after the application of low-Dye taping was reduced lateral forefoot peak plantar pressure but this effect wore off shortly after a 10-minute walk.
Neither David J. Levine, DPM, CPed, nor Howard Dananberg, DPM, were surprised by this finding from the study as both cite the short-term effect of low-Dye taping. “Once the adhesive on the tape loses some of its traction, the effects of taping will be diminished,” adds Dr. Levine, who is in private practice in Frederick, Md.
The study authors did note that low-Dye taping seemed to facilitate a medial to lateral shift in pressure in the midfoot that was maintained after 20 minutes of exercise.
“Podiatrists have used low-Dye taping for many years in an attempt to control the excessive medial shift in weight associated with excessive pronation,” explains Dr. Dananberg, who is in private practice with the Bedford Podiatry Group in Bedford, N.H. “These authors have shown that medial to lateral weight shift does occur with low-Dye taping just as podiatrists have believed since the method of taping was introduced to the profession over 50 years ago.”
Dr. Levine concurs. “With the foot taped, there is a restriction of motion, especially the motion consistent with pronation. Therefore, the shift will be from medial to lateral,” he maintains.
He says there are some variables that are impossible to account for. “Sometimes by taping the foot, the first ray is more stable and this also promotes the medial to lateral shift,” adds Dr. Levine.
When it comes to his own clinical experience with low-Dye taping, Dr. Dananberg says it is a “simple and inexpensive method of care” that can be helpful for a variety of conditions.
“I believe the retention straps around the heel assist in preventing the foot from elongating during the second half of the stance phase of the gait cycle and this is its predominant effect,” explains Dr. Dananberg. “An elongating foot places tension on the plantar fascia and is visible as an excessively pronating foot.”
Can Prefab Orthoses Relieve Pain?
By Brian McCurdy, Senior Editor
The efficacy of prefabricated orthoses has often been the subject of debate as has the comparison of prefab and custom devices. A recent study in the Journal of the American Podiatric Medical Association finds that over-the-counter orthoses can relieve certain types of pain and alter foot shape.
Researchers evaluated two types of prefabricated insoles in 41 patients. According to the study, they assessed the following parameters: foot, knee, hip and back pain; balance; and reduction in flexible deformities such as hammertoes and hallux valgus.
The study authors found that by week four, the use of arch supports caused a significant reduction in certain types of foot pain associated with hallux valgus as well as pain in the arch area, knee and back. Radiographs also revealed changes in foot position, including a statistically significant increase in arch height, an increase in the calcaneal declination angle and a decrease in the first-second metatarsal angle. The study says participants did not exhibit a significant improvement in balance when wearing prefabricated orthoses.
Are there particular conditions in which OTC devices could have an impact? Scott Spencer, DPM, has found that prefab orthotics can work well for patients with plantar fasciitis or heel spurs. As he notes, some patients can benefit from OTC orthoses if they have fascia strain or strain of the intrinsic muscles of the foot that presents as medial longitudinal arch pain. Dr. Spencer has also found that better quality OTC orthotics can be useful in treating children with calcaneal apophysitis.
Other advantages to OTC orthoses include lower cost and efficacy in treating growing children who may need two or three orthoses per year to accommodate growth, according to Dr. Spencer.
Otherwise, Dr. Spencer is a strong proponent of custom orthotics. He says one of the drawbacks of prefab devices is the lack of accommodation for subtle differences in patients’ feet. Prefab orthoses also have downsides in terms of quality and control of foot motion, according to Dr. Spencer, an Associate Professor of Orthopedics/ Biomechanics at the Ohio College of Podiatric Medicine.
“Most OTC devices that are available at pharmacies are more for cushioning and less about motion control,” points out Dr. Spencer. “There are some very good OTC devices available to professionals and they are good because they do provide some motion control.”
Can Bone Morphogenetic Protein Bolster Post-Op Healing?
By Brian McCurdy, Senior Editor
Nonunion can be a significant complication for patients undergoing reconstructive foot and ankle surgery. However, a recent study in the Journal of Foot and Ankle Surgery shows that appropriately selected patients who receive bone morphogenetic protein (BMP) during surgery can progress to healing.
Researchers studied 35 patients who had received BMP as an adjunct to 38 reconstructive foot and ankle surgeries. These surgeries included forefoot surgery, ankle fusion, tibiotalocalcaneal fusion and distal tibial osteotomies.
The study authors say the overall incidence of successful healing was 84.21 percent but they acknowledge a statistically significant decrease in bone healing for patients over 50. The study authors noted that patients’ age had a “profound predictive value” for healing. Four of the six patients who did not heal had diabetes and were over the age of 60, according to the study. In addition, the study authors note that out of the 10 patients who had postoperative drainage, only 50 percent successfully healed whereas 96 percent of the remaining 28 patients had successful post-op healing.
Study co-author Lawrence DiDomenico, DPM, says one should not use BMPs in areas of resected tumors or in patients who have known sensitivity to the active substance or collagen. He adds that one should not use BMPs in patients who are not skeletally mature (less than 18 years old), women who are possibly pregnant, or in patients with an active infection or a dysvascular limb.
What About Cost-Effectiveness?
Bone morphogenetic proteins are “pricey,” acknowledges Dr. DiDomenico, the Director of the Reconstructive Rearfoot and Ankle Surgical Fellowship within the Ankle and Foot Care Centers and the Ohio College of Podiatric Medicine. Therefore, he recommends that podiatric surgeons reserve the use of BMPs for patients who have a high risk of unsuccessful bone healing.
Researchers note that patients require relatively high doses of BMP for the procedure to be effective. The authors say before one can calculate a cost-benefit ratio, one should ask whether the operation will fail without BMP and if the cost of one dose of BMP would exceed the cost of subsequent care if the surgery fails.
