Mary K. Hastings

Effect of Achilles tendon lengthening on neuropathic plantar ulcers. A randomized clinical trial.

Background:Limited ankle dorsiflexion has been implicated as a contributing factor to plantar ulceration of the forefoot in diabetes mellitus. The purpose of this study was to compare outcomes for patients with diabetes mellitus and a neuropathic plantar ulcer treated with a total-contact cast with

Effect of Achilles Tendon Lengthening on Neuropathic Plantar Ulcers

BACKGROUND Limited ankle dorsiflexion has been implicated as a contributing factor to plantar ulceration of the forefoot in diabetes mellitus. The purpose of this study was to compare outcomes for patients with diabetes mellitus and a neuropathic plantar ulcer treated with a total-contact cast with and without an Achilles tendon lengthening. Our primary hypothesis was that the Achilles tendon lengthening would lead to a lower rate of ulcer recurrence. METHODS Sixty-four subjects were randomized into two treatment groups, immobilization in a total-contact cast alone or combined with percutaneous Achilles tendon lengthening, with measurements made before and after treatment, at the seven-month follow-up examination, and at the final follow-up evaluation (a mean [and standard deviation] of 2.1 +/- 0.7 years after initial healing). There were thirty-three subjects in the total-contact cast group and thirty-one subjects in the Achilles tendon lengthening group. There were no significant differences in age, body-mass index, or duration of diabetes between the groups. Outcome measures were time to healing of the ulcer, ulcer recurrence rate, range of dorsiflexion of the ankle, peak torque (strength) of the plantar flexor muscles, and peak plantar pressures on the forefoot. RESULTS Twenty-nine (88%) of thirty-three ulcers in the total-contact cast group and all thirty ulcers (100%) in the Achilles tendon lengthening group healed after a mean duration (and standard deviation) of 41 +/- 28 days and 58 +/- 47 days, respectively (p > 0.05). (One patient in the Achilles tendon lengthening group died before treatment was completed.) In the first seven months of follow-up, sixteen (59%) of the twenty-seven patients in the total-contact cast group who were available for follow-up and four (15%) of the twenty-seven patients in the Achilles tendon lengthening group who were available for follow-up had an ulcer recurrence (p = 0.001). At the time of the two-year follow-up, twenty-one (81%) of the twenty-six patients in the total-contact cast group and ten (38%) of the twenty-six patients in the Achilles tendon lengthening group had ulcer recurrence (p = 0.002). Compared with the group treated with the total-contact cast, the group treated with Achilles tendon lengthening had increased dorsiflexion and it remained increased at seven months (p < 0.001). Plantar flexor peak torque also decreased after Achilles tendon lengthening (p < 0.004), but it returned to baseline after seven months. Peak plantar pressures on the forefoot during barefoot walking were reduced (p < 0.0002) following Achilles tendon lengthening yet returned to baseline values within seven months after treatment. CONCLUSIONS All ulcers healed in the Achilles tendon lengthening group, and the risk for ulcer recurrence was 75% less at seven months and 52% less at two years than that in the total-contact cast group. Achilles tendon lengthening should be considered an effective strategy to reduce recurrence of neuropathic ulceration of the plantar aspect of the forefoot in patients with diabetes mellitus and limited ankle dorsiflexion (</=5 degrees ).

Accuracy and reliability testing of a portable soft tissue indentor

We have designed, built, and tested a portable indentor device that allows us to determine force/displacement (F/D) measurements on soft tissue in a clinical or research setting. The indentor system consists of a load cell mounted on a three-dimensional measurement device (Metrecom). The output of the load cell and the Metrecom are recorded and analyzed by software running on a notebook computer. The displacement calibration of the Metrecom gave an average error=0.005 mm [standard deviation (SD)=0.062)]. The force calibration of the load cell resulted in an average error=0.022 N (SD=0.049) and a linearity of 1.0062(R/sup 2/=0.9998). The indentor device was tested on six different human soft tissues by two different investigators. The interreliabilities and intrareliabilities were 0.99 [interclass correlation (ICC)] indicating that the results were repeatable by more than one investigator. F/D measurements from indentor testing on two materials were comparable to values measured using an Instron device (5.34 versus, 5.52 N/mm, and 0.98 versus 1.04 N/mm). The device was used to measure the soft tissue characteristics on the plantar surface of the foot of one subject. These data were used to calculate the effective Youngs modulus for the tissue using equations derived by Zheng et al. [1999] and indicated a wide range of values dependent upon the portion of the F/D curve used. All results indicate data from this portable indentor device are reliable, accurate, and sensitive enough to identify mechanical properties of human tissues.

Inflammatory Osteolysis in Diabetic Neuropathic (Charcot) Arthropathies of the Foot

Objective: Osteolysis and low bone mineral density (BMD) are underappreciated consequences of several chronic diseases that may elevate the risk for fracture. The purpose of this study was to assess tarsal BMD associated with acute inflammation (ie, inflammatory osteolysis) in individuals with chronic diabetes mellitus (DM), peripheral neuropathy (PN), and recent-onset neuropathic (Charcot) arthropathy (NCA) of the foot. Research Design and Methods: This was a case-control study of 32 people (11 men, 21 women) with DM, PN, and NCA of the foot or ankle. The subjects with DM, PN, and NCA were compared with 64 age-, sex-, and race-matched control subjects (24 men, 40 women) without DM, PN or NCA. Within the first 3 weeks of cast immobilization, BMD was estimated in both calcanei using quantitative ultrasonometry. Acute inflammation was confirmed by comparing skin temperature differences between the feet of the subjects with DM, PN, and NCA and the feet of the control subjects. Results: Skin temperature differences averaged 6.7°F (SD=4.0°F) (involved foot minus noninvolved foot) in the feet of the subjects with DM, PN, and NCA compared with 0.0°F (SD=1.3°F) in the feet of the control subjects. Calcaneal BMD averaged 384 mg/cm2 (SD=110) in the involved feet and 467 mg/cm2 (SD=123) in the noninvolved feet of the subjects with DM, PN, and NCA and 545 mg/cm2 (SD=121) in combined right and left feet of the control subjects. Conclusions: Inflammation in individuals with DM, PN, and NCA may contribute to or exacerbate a rapid loss of BMD. Inflammatory osteolysis may be a prominent factor responsible for both the spontaneous onset of neuropathic fracture and the insidious and progressive foot deformity that is the hallmark of the chronic Charcot foot.

Weight-bearing versus nonweight-bearing exercise for persons with diabetes and peripheral neuropathy: a randomized controlled trial.

OBJECTIVE To determine the effects of weight-bearing (WB) versus nonweight-bearing (NWB) exercise for persons with diabetes mellitus (DM) and peripheral neuropathy (PN). DESIGN Randomized controlled trial with evaluations at baseline and after intervention. SETTING University-based physical therapy research clinic. PARTICIPANTS Participants with DM and PN (N=29) (mean age ± SD, 64.5±12.5y; mean body mass index [kg/m(2)] ± SD, 35.5±7.3) were randomly assigned to WB (n=15) and NWB (n=14) exercise groups. All participants (100%) completed the intervention and follow-up evaluations. INTERVENTIONS Group-specific progressive balance, flexibility, strengthening, and aerobic exercise conducted sitting or lying (NWB) or standing and walking (WB) occurred 3 times a week for 12 weeks. MAIN OUTCOME MEASURES Measures included the 6-minute walk distance (6MWD) and daily step counts. Secondary outcome measures represented domains across the International Classification of Functioning, Disability and Health. RESULTS The WB group showed greater gains than the NWB group over time on the 6MWD and average daily step count (P<.05). The mean and 95% confidence intervals (CIs) between-group difference over time was 29m (95% CI, 6-51) for the 6MWD and 1178 (95% CI, 150-2205) steps for the average daily step count. The NWB group showed greater improvements than the WB group over time in hemoglobin A1c values (P<.05). CONCLUSIONS The results of this study indicate the ability of this population with chronic disease to increase 6MWD and daily step count with a WB exercise program compared with an NWB exercise program.

Removable cast walker boots yield greater forefoot off-loading than total contact casts

BACKGROUND Elevated plantar loading has been implicated in the etiology of plantar ulceration in individuals with diabetes mellitus and peripheral neuropathy. Total contact casts and cast walker boots are common off-loading strategies to facilitate ulcer healing and prevent re-ulceration. The purpose of this study was to compare off-loading capabilities of these strategies with respect to plantar loading during barefoot walking. METHODS Twenty-three individuals with diabetes, peripheral neuropathy, and plantar ulceration were randomly assigned to total contact cast (n=11) or removable cast walker boot (n=12). Each subject underwent plantar loading assessment walking barefoot and wearing the off-loading device. Analysis of covariance was used to compare loading patterns in the off-loading devices for the whole foot, hindfoot, midfoot, and forefoot while accounting for walking speed and barefoot loading. FINDINGS For the foot as a whole, there were no differences in off-loading between the two techniques. Subjects wearing cast walker boots had greater reductions in forefoot peak pressure, pressure-time integral, maximum force, and force-time integral with respect to barefoot walking. Healing times were similar between groups, but a greater proportion of ulcers healed in total contact casting compared to cast walker boots. INTERPRETATION In subjects with diabetes, peripheral neuropathy, and plantar ulceration, cast walker boots provided greater load reduction in the forefoot, the most frequent site of diabetic ulceration, though a greater proportion of subjects wearing total contact casts experienced ulcer healing. Taken together, the less effective ulcer healing in cast walker boots despite superior forefoot off-loading suggests an important role for patient compliance in ulcer healing.

Effect of Metatarsal Pad Placement on Plantar Pressure in People with Diabetes Mellitus and Peripheral Neuropathy

Background: Standard prevention and treatment strategies to decrease peak plantar pressure include a total contact insert with a metatarsal pad, but no clear guidelines exist to determine optimal placement of the pad with respect to the metatarsal head. The purpose of this study was to determine the effect of metatarsal pad location on peak plantar pressure in subjects with diabetes mellitus and peripheral neuropathy. Methods: Twenty subjects with diabetes mellitus, peripheral neuropathy, and a history of forefoot plantar ulcers were studied (12 men and eight women, mean age = 57 ± 9 years). CT determined the position of the metatarsal pad relative to metatarsal head and peak plantar pressures were measured on subjects in three footwear conditions: extra-depth shoes and a 1) total contact insert, 2) total contact insert and a proximal metatarsal pad, and 3) total contact insert and a distal metatarsal pad. The change in peak plantar pressure between shoe conditions was plotted and compared to metatarsal pad position relative to the second metatarsal head. Results: Compared to the total contact insert, all metatarsal pad placements between 6.1 mm to 10.6 mm proximal to the metatarsal head line resulted in a pressure reduction (average reduction = 32 ± 16%). Metatarsal pad placements between 1.8 mm distal and 6.1 mm proximal and between 10.6 mm proximal and 16.8 mm proximal to the metatarsal head line resulted in variable peak plantar pressure reduction (average reduction = 16 ± 21%). Peak plantar pressure increased when the metatarsal pad was located more than 1.8 mm distal to the metatarsal head line. Conclusions: Consistent peak plantar pressure reduction occurred when the metatarsal pad in this study was located between 6 to 11 mm proximal to the metatarsal head line. Pressure reduction lessened as the metatarsal pad moved outside of this range and actually increased if the pad was located too distal of this range. Computational models are needed to help predict optimal location of metatarsal pad with a variety of sizes, shapes, and material properties.

Progression of Foot Deformity in Charcot Neuropathic Osteoarthropathy

BACKGROUND Charcot neuropathic osteoarthropathy associated foot deformity can result in joint instability, ulceration, and even amputation. The purpose of the present study was to follow patients with and without active Charcot osteoarthropathy for as long as two years to examine the magnitude and timing of foot alignment changes. METHODS We studied fifteen subjects with Charcot osteoarthropathy and nineteen subjects with diabetes mellitus and peripheral neuropathy without Charcot osteoarthropathy for one year; eight of the subjects with osteoarthropathy and five of the subjects with diabetes and peripheral neuropathy were followed for two years. Bilateral weight-bearing radiographs of the foot were made at baseline for all subjects, with repeat radiographs being made at six months for the osteoarthropathy group and at one and two years for both groups. Radiographic measurements included the Meary angle, cuboid height, calcaneal pitch, and hindfoot-forefoot angle. RESULTS The Meary angle, cuboid height, and calcaneal pitch worsened in feet with Charcot osteoarthropathy over one year as compared with the contralateral, uninvolved feet and feet in patients with diabetes and peripheral neuropathy. Cuboid height continued to worsen over the two-year follow-up in the feet with Charcot osteoarthropathy. These feet also had a greater change in the hindfoot-forefoot angle at one year as compared with the feet in patients with diabetes and peripheral neuropathy and at two years as compared with the contralateral, uninvolved feet. CONCLUSIONS In patients with Charcot neuropathic osteoarthropathy, radiographic alignment measurements demonstrate the presence of foot deformity at the time of the initial clinical presentation and evidence of progressive changes over the first and second years. The six-month data suggest worsening of medial column alignment prior to lateral column worsening. This radiographic evidence of worsening foot alignment over time supports the need for aggressive intervention (conservative bracing or surgical fixation) to attempt to prevent limb-threatening complications.

Tarsal and Metatarsal Bone Mineral Density Measurement Using Volumetric Quantitative Computed Tomography

A new method for measuring bone mineral density (BMD) of the tarsal and metatarsals is described using volumetric quantitative computed tomography (VQCT) in subjects with diabetes mellitus and peripheral neuropathy. VQCT images of a single foot were acquired twice from eight subjects (mean age 51 [11 SD], seven males, one female). The cortical shells of the seven tarsal and five metatarsal bones were identified and semiautomatically segmented from adjacent bones. Volume and BMD of each bone were measured separately from the two acquired scans for each subject. Whole-bone semiautomatic segmentation measurement errors were determined as the root mean square coefficient of variation for the volume and BMD of 0.8% and 0.9%, respectively. In addition to the whole-bone segmentation methods, we performed atlas-based partitioning of subregions within the second metatarsal for all subjects, from which the volumes and BMDs were obtained for each subregion. The subregion measurement BMD errors (root mean square coefficient of variation) within the shaft, proximal end, and distal end were shown to vary by approximately 1% between the two scans of each subject. The new methods demonstrated large variations in BMDs between the 12 bones of the foot within a subject and between subjects, and between subregions within the second metatarsal. These methods can provide an important outcome measure for clinical research trials investigating the effects of interventions, aging, or disease progression on bone loss, or gain, in individual foot bones.

Magnetic resonance imaging measurement reproducibility for calf muscle and adipose tissue volume.

To describe a new semiautomated method for segmenting and measuring the volume of the muscle, bone, and adipose (subcutaneous and intermuscular) tissue in calf muscle compartments using magnetic resonance (MR) images and determine the intrarater and interrater reproducibility of the measures.