The Effectiveness of a Modified Wedge Shoe in Reducing Pressure at the Area of Previous Great Toe Ulceration in Individuals wi

Introduction Nearly 15 percent of individuals with diabetes will develop foot ulceration,[1] and faulty foot ulcer healing is considered a major cause of diabetes-related lower-extremity amputation.[2] Sensory loss and repetitive walking stress lead to foot injury, ulceration, and faulty healing.[3,4] Plantar ulcerations develop over areas of highest foot pressure,[3,5,6] and the effective reduction of pressure (offloading) is considered essential in the healing of plantar ulcers.[7] The great toe is one of the most common locations of foot ulceration in individuals with diabetes mellitus and other neuropathic conditions. Ulcerations at the great toe have been associated with high pressure resulting from hallux limitus and claw toe deformities.[8–10] The contact cast has been found to be the most effective method in healing foot ulcers.[11–13] The cast is effective because it reduces pressure over the ulcer area, imposes continuous offloading, reduces edema, and limits patient activity. While considered the gold standard, the cast is not widely used because of the skills required for application and concern about secondary skin lesions. As a result of these concerns, a variety of alternative offloading methods have been recommended in the management of great toe ulcerations.[14–17] Short leg walker boots, surgical shoes, and surgical shoes with wedge soles (OrthoWedge or half shoe) have been found to be useful in a variety of multidisciplinary settings because they are relatively simple to apply. Short leg walkers are rigid, removable, plastic, walking boots that have a soft foot bed and a rocker sole. Walkers have been found to be as effective as casts in reducing plantar pressure[18,19] but not as effective as contact casts in ulcer healing.[12] The generalizability of these studies is limited, because the design of total contact casts varies between clinicians, and the design of short leg walkers varies among manufacturers. Surgical shoes with a soft foot bed have been used to accommodate the fit of wound dressings and provide pressure relief in the ulcerated foot. A surgical shoe has been found to reduce foot pressure when compared to a standard shoe.[20,21] A wedge sole surgical shoe was found to be more effective than a standard surgical shoe in reducing forefoot pressure[18] and has been shown to promote foot ulcer healing.[22] An OrthoWedge shoe has been found to be less effective than a total contact cast or a short leg walker in ulcer healing.[12] The placement of the wedge sole, proximal to the metatarsal area, is believed to shift weight bearing from the forefoot to the rearfoot. This study compares the effectiveness of a wedge shoe, modified wedge shoes, a short leg walker, and a surgical shoe in reducing walking pressure over the area of previous diabetes related great toe ulceration. Method Twelve volunteer subjects (7 men and 5 women; mean age 53.8±13.9 years) who had histories of diabetes mellitus and histories of neuropathic great toe ulceration participated in the study. Individuals with histories of foot amputation or surgical debridement of underlying bone were excluded from the study. Subjects did not have a current ulcerations, Charcot deformities, amputations, or gait instability. The F-Scan system (Tekscan, Inc., Boston, Massachusetts) was used to measure in-shoe walking pressure. Pressure sensors were 1mm thick and had a resolution of 3.9 sensels/cm2. F-Scan computer software was used to graphically display pressure distributions during walking and measure peak pressure. Custom software was used to measure the pressure time integral over the previously ulcerated area. Data was recorded at a sampling rate of 50 hertz. The F-Scan system has been shown to provide good reliability for measuring in-shoe pressure during walking trials.[23] Sensors were trimmed to fit the shape of the foot, held to the foot by a thin sock, attached to a transducer on the subject’s leg, and connected to a computer via a 30-feet long cable. Sensors were calibrated on each subject prior to the walking trials. This study used a repeated-measures design with the order of treatments randomly assigned. Each subject participated in all trials and served as his or her own control. Subjects were required to give informed consent, and the study was approved by the Louisiana State University Health Sciences Center Institutional Review Board. Prior to testing, each subject’s feet were assessed for foot injuries, and heavy plantar calluses were trimmed. The subjects performed practice walks in each of the treatment footwear and were given instruction to walk consistently at their self-selected paces. After sensor calibration, subjects walked 30 feet during three trials in each footwear treatment condition. Measurements of pressure were recorded using a midgait method.[24] The six treatment conditions (Figures 1 and 2) included the following: 1) a surgical shoe (Darco® medical surgical shoe, Huntington, West Virginia); 2) a short leg walker (Pacesetter II, Carapace, Tulsa, Oklahoma); 3) a wedge shoe (OrthoWedgeTM, Darco, Huntington, West Virginia); 4) a wedge shoe modified with a quarter-inch polyethylene insert (firm #2 Plastazote®, AliMed, Dedham, Massachusetts); 5) a wedge shoe modified with a quarter-inch polyethylene insert, with a one and one-quarter-inch diameter relief under and a quarter-inch build-up behind the area of previous great toe ulceration. The surgical shoe, the short leg walker, and the unmodified wedge shoe are supplied with 3/16-inch foam footbeds of similar firmness (28, 34, 30, shore A durometer, respectively). Mean peak pressure, the mean pressure time integral, and mean contact time were recorded from a total of 15 steps (5 steps x 3 trials). The mean gait cycle time was recorded from the midgait cycle of three steps (1 step x 3 trials). A standardized 2x2 and 8x8 sensil window was used to measure peak pressure and pressure time integral, respectively. A one-way analysis of variance for repeated measures and a Duncan’s multiple comparisons test (p