Characteristics and Identification of Wound Types: Neuropathic Wounds
Introduction[edit | edit source]
This article provides information for rehabilitation professionals who are new to wound care or have been away from the practice and need a review of wound type identification. This article will not go into specifics on wound assessment or treatment.
The five most common types of chronic wounds include (1) arterial ulcers, (2) venous insufficiency ulcers or venous wounds, (3) neuropathic wounds, or diabetic foot ulcers, (4) pressure injuries, formerly known as pressure ulcers, and (5) non-healing surgical wounds.
The terms ulcer and wound will be used interchangeably throughout this article.
Due to the large amount of information to be presented, this topic has been divided into three separate pages. This page will cover neuropathic wounds. To learn more about arterial wounds and venous insufficiency ulcers, please see this article. To learn more about pressure injuries and non-healing surgical wounds, please see this article.
Neuropathic Wounds[edit | edit source]
Neuropathic ulcers (also known as diabetic ulcers) form as the result of a type of peripheral neuropathy (PN). Diabetic neuropathy is commonly seen in patients with diabetes. More severe PN will cause impaired or absent sensation in the foot. If left unchecked, this lack of sensation will cause tissue and skin breakdown over the bony pressure points of the foot, leading to eventual wound formation. Additionally, PN can result in more minor scrapes or cuts. If the patient is not aware of these minor injuries, they can also develop into neuropathic wounds. 
Diabetes[edit | edit source]
- Diabetes is very common condition and has increasing prevalence; more than 8.5% of people over the age of 18 have diabetes worldwide
- Previously, diabetes was considered a problem of higher-income countries, however rates are now rising more quickly in low- and middle-income countries
- Diabetes is being diagnosed more commonly in a younger population
- More than 25% of people with diabetes will develop a diabetic foot ulcer (DFU). Once an ulcer is present, the five-year survival rate is approximately 45%
- Diabetes inhibits all phases of wound healing and increases the susceptibility to infection
- Prolonged hyperglycaemia is toxic to cells and this results in damage to multiple organ systems
- Lower extremity neuropathy is one of the most common impairments
- Other common sites of complications: kidneys, eyes, heart, brain, and gums
Diabetic neuropathy[edit | edit source]
Three types of diabetic neuropathy: neuropathy symptoms will progress with disease severity:
- Sensory. 30 to 50% of patients with diabetes, aged 40 or older, have some level of sensory impairment. Initially, the patient may report intermittent feelings of "aching" or "tingling" in a stocking and glove distribution. Sensory neuropathy will progress from a loss of superficial sensation to a loss of protective sensation to a total loss of sensation. A total loss of sensation puts the patient at high risk of tissue injury and damage.
- Motor. Motor neuropathy is seen as weakness, loss of coordination, or lack of proprioception during a motor task. It causes atrophy of the intrinsic foot muscles, which leads to toe deformities and an increased pressure over bony prominences of the forefoot, heel, and metatarsal heads. This increased pressure leads to calluses, blisters, and then open wounds, especially when combined with sensory neuropathy. Severe motor neuropathy may lead to foot drop.
- Autonomic. Autonomic neuropathy affects the integumentary system, cardiovascular system, gastrointestinal system, and the genitourinary system. Clinical presentation includes: lack of sweating, hair loss, nail thickening, severely dried skin. Extreme skin dryness can cause the formation of fissures in the skin, which act as an entry point for bacteria. Patients with more severe diabetes are often unable to mount a sufficient immune response to invading bacteria which increases their risk for infection.
The following optional video compares the different types of diabetic neuropathy.
The neuropathic foot[edit | edit source]
According to Allan et al., the development of common foot deformities in persons with diabetes is not well understood. There is an association between (1) muscle weakness and (2) limited joint mobility and the formation of foot deformities. However, there did not appear to be a definitive association with the formation of foot deformities and (1) intrinsic foot muscle atrophy, (2) muscle imbalance, and a (3) reduction in nerve function.
Diabetes can result in multiple foot deformities:
- Pes cavus: a varus hindfoot, high calcaneal pitch, high-pitched midfoot and plantarflexed and adducted forefoot
- Hallux valgus (also known as a bunion): deformity of the great toe into abduction valgus and pronation associated with a bony prominence on the inner edge of the metatarsal
- Hammer toe: plantar flexion of the distal and middle interphalangeal joint in comparison to the proximal phalanx
- Claw toe: dorsal flexion of the metatarsophalangeal joint, associated with hammer toe
- Mallet toe: flexion of the distal phalanx over the middle phalanx due to a contracture at the distal interphalangeal joint
- Charcot foot (also known as rocker bottom deformity): non-infectious destruction of bone and joint tissue including loss of foot arches
Neuropathic screening[edit | edit source]
- Single-point perception test
- Light touch assessment
- Deep touch or deep pressure assessment
- Hot/cold discrimination test
- Two-point discrimination test
- Assess foot and leg for atrophy
- Strength and endurance assessment
- Coordination assessment
- Proprioception assessment
- Balance assessment
Special topic: Semmes-Weinstein monofilament examination (SWME)
SWME is a single-point perception test. It is the current gold standard for screening for diabetic neuropathy. Research has found the SWME to be a significant and independent predictor for future foot ulceration in patients with diabetes. It may also be useful in the prediction and prognosis of lower extremity amputation.
- It is simple to perform, affordable, and a readily available screening tool
- The most commonly used is the 5.07 monofilament, which applies 10 grams of pressure
- A thin nylon rod is used to manually assess the foot and determine if there is any degree of sensory loss
- If the patient can feel the monofilament, protective sensation is intact; if they are unable to feel the monofilament, protective sensation is absent and they are at a high risk for developing an ulcer
Please view the following optional video for quick demonstration of a neuropathic foot screening.
Formation of diabetic wounds[edit | edit source]
Three types of stress that lead to diabetic wounds:
- Low pressure over a long period of time. Examples include: too narrow or too short shoes, foot deformities that press into the edges of the shoes
- Direct mechanical injury. Occurs when an individual with sensory neuropathy steps on an object and is unable to feel it. Examples include: a tack, a piece of glass, a splinter, a small stone, a piece of their shoe insole
- Repeated pressure and friction. Chronic irritation in the same spot leads to callus formation. If a callus is not managed and beings to harden, this callus itself can become a source of isolated pressure and result in underlying haemorrhages, abscess formation, and eventual ulcers.
Neuropathic wound characteristics[edit | edit source]
- 71% of neuropathic ulcers are located on the forefoot: they are most common on the (1) third metatarsal head, (2) great toe, and then the (3) first and fifth metatarsal heads.
- Hypertrophic nails (thickened, brittle, crumbly, and or ragged nails)
- Onychomycosis may be present: a fungal infection that presents as a yellowish or brownish nails, the nail may separate from the nail bed
- Callus. Common in high-pressure, high-friction areas like the tips or outer surfaces of the toes and the metatarsal heads. Tends to be yellowish-grey in colour and may be either flat or raised. Often becomes hard and a potential source of wound formation.
Diabetic foot wounds characteristics:
- Typically occur on the plantar surface of the foot
- Commonly, the entire periphery of the wound will be surrounded by callus
- Often accompanied by foot deformities
- Possible visible bleeding under the skin, which will appear black, brown, or purple, almost like a bruise
- The wound bed is often pale with irregular granulation
- Neuropathy will be present
Neuropathic wound management[edit | edit source]
The three most important factors for diabetic wound management:
- Offloading. Neuropathic wounds need to be fully offloaded as much as possible to allow for healing. The method of offloading may transition as the wound heals and closes. This includes offloading related dressing and other devices. It is important to note that the use of crutches, canes, or walkers do not provide sufficient offloading on their own, but they may be used as an adjunct to an offloading device for gait and balance. Diabetic shoes should only be used to offload areas of high pressure over intact skin, not to offload open wounds. A trained physiotherapist, podiatrist, or orthotist should be consulted to determine an appropriate offloading device.
- Blood glucose control. Proper blood glucose management is necessary for wound healing and the prevention of potential future complications. Patient education is essential. A diabetologist, endocrinologist, or dietitian can provide thorough education and training to encourage patient success.
- Daily foot care and self-inspection. Prevention is key for diabetic wounds. This is best accomplished with daily patient self-inspection. Patient training and education should be bolstered through an inspection by healthcare providers every three to 12 months, depending on their risk level.
Resources[edit | edit source]
- Manchester Oxford Foot Questionnaire -- PDF for clinical use
- International Working Group on the Diabetic Foot (IWGDF) -- website
- IWGDF Guideline on offloading foot ulcers in persons with diabetes
- Johns Hopkins diabetes self management patient education materials
- Multilingual diabetes handouts (Arabic, Chinese, English, Lao, Somali, Spanish, Tagalog, Vietnamese)
Additional Optional Reading:
- Boghossian J, Miller J, Armstrong D. Offloading the diabetic foot: toward healing wounds and extending ulcer-free days in remission. Chronic Wound Care Management and Research. 2017 Jul 14;4:83-8.
References[edit | edit source]
- Palmer, D. Characteristics and Identification of Wound Types. Physiotherapy Wound Care Programme. Plus. 2022.
- Wound Source. Neuropathic Ulcers and Wound Care: Symptoms, Causes, and Treatments. Available from: https://www.woundsource.com/blog/neuropathic-ulcers-and-wound-care-symptoms-causes-and-treatments (accessed 19/09/2022).
- Lin X, Xu Y, Pan X, Xu J, Ding Y, Sun X, Song X, Ren Y, Shan PF. Global, regional, and national burden and trend of diabetes in 195 countries and territories: an analysis from 1990 to 2025. Scientific reports. 2020 Sep 8;10(1):1-1.
- YouTube. Diabetic Neuropathy, Animation. Available from: https://www.youtube.com/watch?v=CyOdY5L-YeE [last accessed 20/09/2022]
- Allan J, Munro W, Figgins E. Foot deformities within the diabetic foot and their influence on biomechanics: A review of the literature. Prosthetics and orthotics international. 2016 Apr;40(2):182-92.
- Mekonnen B, Wirtu A, Kebede M, Tilahun A, Degaga T. Diabetics-Related Foot Deformity: Prevalence, Risk Factors, Knowledge and Practice. Trends Anat Physiol 4: 010, 2021.
- Physiopedia. Pes caves. Available from: https://physio-pedia.com/Pes_cavus (accessed 19/09/2022).
- Liu, Jiayi, Yuan, Xiaoyong, Liu, Jin, Yuan, Geheng, Sun, Yalan, Zhang, Donghui, Qi, Xin et al. Risk Factors for Diabetic Peripheral Neuropathy, Peripheral Artery Disease, and Foot Deformity Among the Population With Diabetes in Beijing, China: A Multicenter, Cross-Sectional Study. Frontiers in Endocrinology, 2021.
- Feng Y, Schlösser FJ, Sumpio BE. The Semmes Weinstein monofilament examination is a significant predictor of the risk of foot ulceration and amputation in patients with diabetes mellitus. Journal of vascular surgery. 2011 Jan 1;53(1):220-6.
- Castellano VK, Jackson RL, Zabala ME. Contact Mechanics Modeling of the Sem-mes-Weinstein Monofilament on the Plantar Surface of the Foot. Int J Foot Ankle. 2021;5:055.
- YouTube. Diabetic foot examination - OSCE guide | Geeky Medics. Available from: https://www.youtube.com/watch?v=vwIyulPnXcg [last accessed 20/09/2022]
- Xiang J, Wang S, He Y, Xu L, Zhang S, Tang Z. Reasonable glycemic control would help wound healing during the treatment of diabetic foot ulcers. Diabetes Therapy. 2019 Feb;10(1):95-105.