By Stephanie Kramer
Most practitioners are aware that diabetic foot ulcers have a high recurrence rate, but might be surprised by findings epublished in April suggesting a relatively large number of subsequent ulcers occur at new locations, including the contralateral foot.
Although other studies have investigated the likelihood of ulcer recurrence in patients with diabetes, the authors of the current study believe that clearly defining the term “recurrence” could help aid prevention.
“I was really surprised by the lack of a uniform definition in the literature,” said lead author Hedvig Örneholm, MD, PhD, a resident in the Department of Orthopedics at Lund University in Sweden. “No one has defined what a ‘new’ ulcer is. The literature refers to ulcers as new, recurrent, or plantar ulcer without distinguishing location.”
Researchers at Skane University Hospital and Lund University in Sweden analyzed the occurrence of subsequent ulcers in 617 diabetic patients with a healed forefoot ulcer who visited the hospital foot-care clinic between 1983 and 2012.
After the initial ulcer healed, clinicians fitted all patients with custom-made footwear for both feet and assessed them at 12 and 24 months for recurrent (defined as occurring at the same site as the initial ulcer) and other new ulcers. Patients were seen by an interdisciplinary team consisting of a diabetologist, orthopedic surgeon, diabetes nurse, orthotist, and chiropodist. They also received oral and written instructions for self-care.
Investigators collected data on the development, characteristics, and outcome of subsequent foot ulcers. During the two-year follow-up, 42% of patients developed a subsequent foot ulcer. Of these, 8% developed a foot ulcer at the same site, while 34% developed one elsewhere (112 on the same foot, 99 on the contralateral foot). The patients who died during the two-year follow-up period were analyzed separately; of those 87 patients, none had a recurrent ulcer, but 30 had developed ulcers in new locations—16 on the same foot as the initial ulcer and 14 on the contralateral foot.
Risk of new ulceration was similar for patients whose initial ulcers required major surgical debridement or amputation prior to complete healing and those who healed without surgery. That finding contrasts with a 1998 Italian study in which patients treated nonsurgically developed new ulcers at the same site as the healed ulcer, while those treated surgically developed ulcers at new locations.
A smaller ulcer at baseline was associated with a lower risk of having a recurrent or new ulcer, Örneholm said. No other predictors were identified as having a significant association with ulcer development; however, the database was not designed for such an analysis, she said.
Örneholm noted that inadvertent effects of offloading the initial ulcer might be a contributing factor.
“If you relieve pressure in one place, you might increase pressure in a new place,” she said.
The researchers did not discuss other factors such as peak plantar pressure, pressure-time interval, or shear that might influence ulcer development. The findings were epublished in April 2017 by Wound Repair and Regeneration.
Jaap van Netten, PhD, who is a human movement scientist at Queensland University of Technology in Brisbane, Australia, said the high number of recurrent ulcers in different locations reported by the Swedish authors is surprising.
“The results are a signal that the first year is really important after an ulcer heals. An ulcer is not healed. It’s in remission. It’s basically waiting for a new ulcer to develop,” van Netten said. “Your patients are in remission, with one out of two getting an ulcer within a year.”
A critical analysis of risk factors would have been welcome, van Netten noted. Despite this limitation, van Netten said the study makes an important contribution, highlighting the challenges clinicians face in preventing recurrent foot ulcers.
“It makes it harder to predict where the next ulcer will occur,” van Netten said.
Patients themselves tend to be more focused on the primary ulcer location, he continued.
“I think the study is really a message to clinicians and patients that they should look at both feet every day and not focus on the previous ulcer location,” van Netten said. “As a clinician, you cannot focus on the previous location alone. You must take a holistic look at the patient.”
Örneholm H, Apelqvist J, Larsson J, et al. Recurrent and other new foot ulcers after healed plantar forefoot diabetic ulcer. Wound Repair Regen 2017 Apr 1. [Epub ahead of print]
Piaggesi A, Schipani E, Campi F, et al. Conservative surgical approach versus nonsurgical management for diabetic neuropathic foot ulcers: a randomized trial. Diabet Med 1998;15(5):412-417.