An exploratory study on differences in cumulative plantar tissue stress between healing and non-healing plantar neuropathic diabetic foot ulcers.

BACKGROUND: Mechanical stress is important in causing and healing plantar diabetic foot ulcers, but almost always studied as peak pressure only. Measuring cumulative plantar tissue stress combines plantar pressure and ambulatory activity, and better defines the load on ulcers. Our aim was to explore differences in cumulative plantar tissue stress between people with healing and non-healing plantar diabetic foot ulcers. METHODS: We analyzed a subgroup of 31 patients from a randomized clinical trial, treated with a removable offloading device for their plantar diabetic forefoot ulcer. We measured in-device dynamic plantar pressure and daily stride count to calculate cumulative plantar tissue stress at the ulcer location and associated this with ulcer healing and ulcer surface area reduction at four weeks (Student's t and chi-square test for significance, Cohen's d for effect size). FINDINGS: In 12 weeks, 68% (n = 21) of the ulcers healed and 32% (n = 10) did not. No statistically significant differences were found for cumulative plantar tissue stress, plantar pressure or ambulatory activity between people with healed and not-healed ulcers. Cumulative plantar tissue stress was 25% lower for people with healed ulcers (155 vs. 207 MPa·s/day; P = 0.71; Effect size: d = 0.29). Post-hoc analyses in the 27 patients who self-reported to be adherent to wearing the device showed that cumulative plantar tissue stress was 49% lower for those who reached ≥75% ulcer surface area reduction at four weeks (140 vs. 275 MPa·s/day; P = 0.09; d = 0.76); smaller differences and effect sizes were found for peak pressure (24%), peak pressure-time integral (30%) and ambulatory activity (26%); (P-value range: 0.14-0.97; Cohen's d range: 0.14-0.70). INTERPRETATION: Measuring cumulative plantar tissue stress may provide insight beyond that obtained from plantar pressure or ambulatory activity alone, with regard to diabetic foot ulcer healing using removable offloading devices. These explorative findings provide baseline data for further studies on this relevant topic.

The effect of flexor tenotomy on healing and prevention of neuropathic diabetic foot ulcers on the distal end of the toe.

BACKGROUND: Flexor tenotomy is a minimally invasive surgical alternative for the treatment of neuropathic diabetic foot ulcers on the distal end of the toe. The influence of infection on healing and time to heal after flexor tenotomy is unknown. Flexor tenotomy can also be used as a prophylactic treatment. The effectiveness as a prophylactic treatment has not been described before. METHODS: A retrospective study was performed with the inclusion of all consecutive flexor tenotomies from one hospital between January 2005 and December 2011. RESULTS: From 38 ulcers, 35 healed (92%), with a mean time to heal of 22 ± 26 days. The longest duration for healing was found for infected ulcers that were penetrating to bone (35 days; p = .042). Cases of prophylactic flexor tenotomies (n=9) did not result in any ulcer or other complications during follow-up. CONCLUSIONS: The results of this study suggest that flexor tenotomy may be beneficial for neuropathic diabetic foot ulcers on the distal end of the toe, with a high healing percentage and a short mean time to heal. Infected ulcers that penetrated to bone took a significantly longer time to heal. Prospective research, to confirm the results of this retrospective study, should be performed.

The validity and reliability of diagnosing foot ulcers and pre-ulcerative lesions in diabetes using advanced digital photography.

BACKGROUND: The goal of this study was to determine the validity and reliability of assessing the presence of plantar foot ulceration and pre-ulcerative lesions in diabetes patients from digital photographs that were produced using a new photographic foot imaging device. METHODS: In 32 diabetes patients who had a foot ulcer or were at high risk of ulceration (a total of 60 feet), high-quality photographic images of the plantar foot surface were collected. Each foot was assessed live, from photographs 2 weeks later, and again 4 weeks later for the presence of an ulcer, abundant callus, or the absence of signs. Each foot was assessed by four independently operating foot care specialists. Agreement scores were calculated using κ values (range, 0-1). Sensitivity and specificity scores were also calculated. RESULTS: Foot ulceration was cumulatively scored 59 times, callus 78 times, and absence of signs 149 times during live assessment. Agreement with photographic assessment was very good for ulcer (κ = 0.87) and absence of signs (κ = 0.83) and good for callus (κ = 0.61). Sensitivity and specificity were high for ulcer (88% and 98%, respectively), callus (69% and 89%, respectively), and absence of signs (both 90%). Intra-observer agreement between repeated photographic assessments was good to excellent for all outcomes and observers (κ between 0.70 and 1.00). Inter-observer agreement for photographic assessments was good for ulcer (κ = 0.72-0.88) and absence of signs (κ = 0.59-0.75) and moderate to good for callus (κ = 0.48-0.73). For live assessment, inter-observer agreement scores were only slightly higher. CONCLUSIONS: The data illustrate that diabetic foot ulcers and pre-ulcerative lesions can be diagnosed in a valid and reliable manner by trained professionals from digital photographs produced with the foot imaging device. This supports the intended use of the device as a telemedical monitoring tool in the home environment for early detection of diabetic foot disease and prevention of severe complications in high-risk diabetes patients.