Activity Monitoring: Can It Bolster Patient Compliance?

By Katherine Holtz-Neiderer, DPM, and David G. Armstrong, DPM, MSc

Repetitive stress is a major contributing factor to the rise of most foot problems. In the high-risk diabetic foot clinics at the Southern Arizona Veterans Affairs Medical Center, the most common of these severe complications is the diabetic foot wound. The prime etiology of diabetic foot ulcers is the combination of neuropathy and repetitive moderate stress (walking). Diabetic foot wounds often lead to a host of other maladies including sepsis, amputation and premature death. It has also been shown that people undergoing amputation have higher healthcare costs.1,2 When it comes to treating patients with diabetic foot ulcers, one must address pressure and repetitive stress (activity). One can address pressure externally (through shoe gear modification, bracing or casting) or internally via physical therapy and/or surgery.3, 4 However, manipulating repetitive stress (activity) has been tougher as it has been quite difficult to measure. In the past, most pedometers merely gave a readout of the steps patients took but gave no information about when that activity started or stopped. In the past few years, we and others have tested and utilized many models of accelerometers/pedometers that range in complexity from more basic models to very sophisticated devices that have enabled us to surpass these early hurdles. We believe we are now at a point where we can begin dosing activity as we might dose a drug. We have used several of these monitoring devices and some hold potential practical applications now and in the future. A Closer Look At The Pedometer Options An early predecessor that we used was the Sportbrain (Sportbrain, Campbell, Calif.). It is worn on the waistband or belt and uses a lithium battery, which lasts three months. The Sportbrain counts the number of steps and the time that they were taken. The information is then uploaded via the Internet where the clinician and patient can both view and analyze the data. This requires a monthly monitoring fee to access the data. The Biotrainer Pro (IM Systems, Baltimore, Md.) is another waistband monitor that has a biaxial acceleration sensor. Similar to the Sportbrain, the Biotrainer Pro measures the number of steps and the time when they were taken. One can also take the patient’s caloric measurements when entering the weight and height of the patient into the computer. It uses an AAA battery and can measure up to three months of data. The most sophisticated device that we have used is the Dynastream Amp 331 (Dynastream Innovations, Inc., Alberta, Canada). This device uses an inertial sensor and is held in a nylon sleeve worn around the ankle. The Dynastream Amp 331 measure critical locomotion details such as the distance traveled, speed, cadence and stride length. It also tracks the number of steps the patient takes and the time they were taken. It also computes energy expenditure. The device even documents standing and milling as the information is blocked into one of three activities: inactive, active and locomotion. Recording time is a drawback to the device as it can only record one week of data at a time. What Does The Future Hold For Pedometers? At our facility, we are currently working on transmitting information via phone line similar to the holter monitor or blood sugar readings. By using a LCD screen and a regular phone line, we can eliminate a computer requirement. With this system in place, we should not be limited by time constraints. We also plan on using it to send patients questionnaires and other forms. Pedometers have been used in a variety of clinical situations. They have been used to quantify claudication and evaluate changes in activity in people with chronic obstructive pulmonary disease, and as a biofeedback mechanism in weight loss studies. Activity monitoring could also be used for pre- and postoperative assessment. A prospective surgical patient could wear the monitor before surgery as an activity baseline and then postoperative monitoring could help a surgeon adjust the amount of activity and measure when the amount of activity returns to baseline. An athlete who undergoes reconstructive foot surgery could use monitor driven goals rather than allowing pain to be his or her guide. One can also use the pedometer to regulate weightbearing compliance immediately postoperatively.5 What The Studies Have Revealed In Assessing Patient Compliance In regard to compliance, a few studies have shown that combining pedometers with medical equipment can be useful in gauging patient compliance. In a trial conducted by our group, a BioTrainer Pro activity monitor was worn by the patient and an additional monitor was attached to a removable cast walker.6 The results were quite surprising. Patients with open wounds on the soles of their feet wore their removable cast walkers for only 28 percent of the total activity they took per day. Even the subset of patients most adherent to the offloading regimen still only wore the device for 60 percent of their total daily activity. These results may help to partially explain why certain wound care strategies fail due to ineffective offloading strategies. In another study, one group wore a removable cast-walker and the other group wore a total contact cast (TCC). Using activity monitor data, the researchers showed that while both groups took a similar amount of steps, the TCC group healed earlier. One can surmise that this was the case because people wearing TCCs were not able to easily remove their offloading device.7 In an additional study, patients wore the Sportbrain and kept logs of when they wore their therapeutic shoes and custom-molded orthotics. Only a fraction of patients wore their protective shoes while at home as compared to when they walked in the community.8 Chantelau, et. al., showed that high-risk patients who wore their therapeutic footwear were significantly less likely to ulcerate than those who did not.9 These three studies helped to explain the important role of compliance in treatment regimens. Using Pedometers To Help Monitor Patients With Diabetic Neuropathy We feel one of the most important uses for pedometers is for diabetic/neuropathic patients, who are at the highest risk for plantar ulceration. For these patients, one could prescribe a maximum amount of activity (like leasing a car) and once their monitor approaches the limit, they must find an alternative mode of transportation (i.e., wheelchair, scooter, bed rest). These high-risk patients who have a history of ulceration need less cumulative stress on a plantar wound before they will reulcerate.10 This is due to an increase of so-called advanced glycosylation end-products (AGEs) in patients with diabetes. This increase correlates with the severity of other systemic complications such as retinopathy and renal failure.11 A decrease in capillary flow to diabetic skin may also be associated with a failure to rebound after repetitive stress. Even if they are able to achieve decreased activity and stress with therapeutic footwear and accommodative orthotics, diabetics with previous ulcerations have a higher chance of recurrence. Matrix reorganization may be compromised by non-enzymatic glycosylation of tissue proteins, which is affiliated with chronically increased glucose levels that one would see in some patients with diabetes.12 A chronically low amount of plantar pressure may cause tissue atrophy. Mueller and Maluf suggested that tissues will atrophy and become more brittle in response to chronically low levels of plantar stress.10 In contrast, it has been shown that progressive loading in healthy animals has resulted in tissue hypertrophy as shown by increases in collagen fiber diameter and reorganization.12 This suggests that promoting a slow increase in activity, which one could monitor with a pedometer, among diabetics with a previous ulceration could help improve tissue durability. Case Study: Detecting Changes In Activity That Lead To An Adverse Event Our center is currently conducting studies involving activity monitoring on several hundred high-risk patients. We have a mountain of activity data on these patients and one patient case hints at the potential impact of using pedometers in assessing patient activity and compliance. The patient is a 58-year-old gentleman who has a long history of diabetes and previous ulceration underneath his fourth metatarsal phalangeal joint. The accompanying charts show both long-term trends in activity over days or weeks (the top bar) and activity over a 24-hour period (the bottom bar). In the top right chart, you can see his activity on an ordinary day. It is quite consistent from day to day as he generally rises at 7 a.m. and retires at 9 p.m. with no overtly excessive bouts of activity (“activity pulses”). A couple of months into this observational project, the patient presented to the medical center emergency room with complaints of a “blister” forming on the bottom of his foot a few days earlier. He subsequently had swelling of his leg and a fever. He noted that he had not been wearing his prescriptive shoe gear as advised but noted no other significant differences in his day-to-day activity. While he did not notice any differences in his activity, we see that his activity monitor registered very unusual activity within 24 hours of his reported blister formation and symptoms (see the bottom left chart). Imagine now if we could teach a computer to identify these pulses of activity, perhaps merging these activity pulses with dermal thermographic signatures (which we have shown in previous studies can act as a surrogate marker for inflammation). This could then electronically notify both the patient and caregiver so they could take the appropriate action (reduced activity, offloading, modification of footwear) to prevent the development of a deleterious event. We believe this is part of the future of high quality, proactive diabetic foot care. In Conclusion Activity monitors may play a significant role in diagnosis as well as motivation. Monitors may give us the ability to dose activity pre- and postoperatively. They may enable us to facilitate a more gradual shift to full activity for patients who have a healed plantar ulcer and limit excessive periods of excessive plantar pressure that can lead to skin breakdown in high-risk patients. Dr. Armstrong is the Director of Research and Education within the Department of Surgery, Podiatry Section, within the Southern Arizona Veterans Affairs Medical Center in Tuscon, Ariz. He is a Visiting Senior Lecturer of Medicine in the Department of Medicine at the Manchester Royal Infirmary at the University of Manchester in the United Kingdom. Dr. Armstrong is also a member of the Board of Directors for the American Diabetes Association. Dr. Holtz-Neiderer is in the first year of a three-year research fellowship with Dr. Armstrong. Editor's Note: For a related article, see “Ten Emerging Innovations In Podiatric Care” in the August 2001 issue or check out the archives at



References 1. American Diabetes Association. Consensus Development Conference on Diabetic Foot Wound Care. Diabetes Care. 1999;22(8):1354. 2. International Consensus on the Diabetic Foot. Paper presented at: International Working Group on the Diabetic Foot, 2003; Noordwijkerhout, Netherlands. 3. Armstrong DG, Lavery LA, Vazquez JR, et al. Clinical Efficacy of the First Metatarsophalangeal Joint Arthroplasty as a Curative Procedure for Hallux Interphalangeal Joint Wounds in Persons with Diabetes. Diabetes Care. 2003(In Press). 4. Armstrong DG, Frykberg RG. Classification of Diabetic Foot Surgery: Toward a Rational Definition. Diabet Med. 2003;20(4):329-331. 5. Armstrong DG, Boulton AJM. Activity Monitors: Should We Begin Dosing Activity as We Dose a Drug? J Amer Podiatr Med Assn. 2001;91:152-153. 6. Armstrong DG, Lavery LA, Kimbriel HR, Nixon BP, Boulton AJ. Activity Patterns of Patients With Diabetic Foot Ulceration: Patients with active ulceration may not adhere to a standard pressure off-loading regimen. Diabetes Care. Sep 2003;26(9):2595-2597. 7. Armstrong DG, Nguyen HC, Lavery LA, van Schie CH, Boulton AJM, Harkless LB. Offloading the Diabetic Foot Wound: A Randomized Clinical Trial. Diabetes Care. 2001;24:1019-1022. 8. Armstrong DG, Abu Rumman PL, Nixon BP, Boulton AJM. Continuous activity monitoring in persons at high risk for diabetes-related lower extremity amputation. J Am Podiatr Med Assoc. 2001;91:451-455. 9. Chantelau E, Kushner T, Spraul M. How effective is cushioned therapeutic footwear in protecting diabetic feet? A clinical study. Diabetic Medicine. 1990;7(4):335-339. 10. Maluf KS, Mueller MJ. Novel Award 2002. Comparison of physical activity and cumulative plantar tissue stress among subjects with and without diabetes mellitus and a history of recurrent plantar ulcers. Clin Biomech (Bristol, Avon). Aug 2003;18(7):567-575. 11. Sell DR, Lapolla A, Odetti P, Fogarty J, Monnier VM. Pentosidine formation in skin correlates with severity of complications in individuals with long-standing IDDM. Diabetes. 1992;41(10):1286-1292. 12. Sanders JE, Goldstein BS. Collagen fibril diameters increase and fibril densitites decrease in skin subjected to repetitive compressive and shear stresses. J Biomech. 2001;34(12):1581-1587.


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