25th May 2022
Chronic wounds are one of the most adverse healthcare issues facing modern medicine and represent a silent epidemic. Roughly two percent of people will develop a chronic wound their lifetime in the developed world1 though prevalence increases with age.2 Chronic wounds are classified as skin ulcerations – typically around the gaiter area – that do not show signs of healing within 30 days.3
Hard to heal wounds require frequent medical attention to promote healing and prevent infection, and this contributes significantly to overall healthcare costs. Chronic wounds cost global healthcare systems billions to treat every year – more than US$10 billion in the United States4 and £8 billion in the United Kingdom.5
Venous leg ulcers (VLUs) account for 70 percent of all chronic leg ulcers6 and are often caused by chronic venous insufficiency (CVI)7 or chronic venous hypertension – a condition that occurs when the veins in the leg do not adequately allow blood to flow back up to the heart. CVI causes substantial ankle oedema (swelling) and changes in the skin’s structure, which can ultimately lead to ulceration.8 This is typically due to impairments in the calf muscle pump.
The role of the calf muscle pump
The calf muscle pump is the motive force that allows the return of venous blood from the lower limbs back to the heart.9 Venous blood flow to the heart from the lower extremities relies on the emptying of the venous plexus (an area where multiple veins assemble) in the calf muscles during the plantar flexion. Sufficient venous blood flow is also dependent on a competent valvular system without any obstruction.10
If these factors are met, venous blood can successfully flow back towards the heart. However, if the venous plexus cannot be emptied, either due to obstruction or impairment of the muscle pump, this increases capillary pressure causing subsequent oedema, liposclerosis, pigmentation, and ultimate skin ulceration.11
It has been hypothesised that when ulceration develops, an impaired muscle pump can prevent the healing of a leg ulcer. Various studies – Simka and Araki et al. – have explored the effects of calf muscle pump impairment on VLU healing and found significant evidence to suggest failure of the calf muscle pump is directly linked to delayed healing.
A literature review of calf muscle pump impairments and VLU healing
Araki et al:
In an evaluation of VLUs, Araki et al.11 studied three groups of patients with different degrees of CVI. Patients’ levels of CVI were measured using air-plethysmography – a non-invasive examination that quantifies venous reflux and obstruction by calculating volume changes in the leg12 – and colour-flow duplex ultrasonography – an ultrasound using high-frequency sound waves to investigate blood flow speed and the structure of veins.13
Araki et al. studied 69 limbs across 55 male patients between the ages of 35 and 86; the mean age was 61. Each patient was categorised based on recommendations from the Society for Vascular Surgery and the International Society for Cardiovascular Surgery. Limbs were subsequently grouped according to their symptoms: chronic swelling, induration, hyperpigmentation, and no history of ulceration; previously ulcerated limbs with healed ulcers at the time of testing; active ulcers at the time of testing.
The study found that patients with active ulcers had a significant deterioration in muscle pump ability. Akari et al. claimed that ulceration, due to severe venous insufficiency, is primarily caused by a defective muscle pump. Impaired muscle contraction was also found to be negatively impacted by the present ulcer.
Simka et al:
Marian Simka investigated the relationship between calf muscle pump impairment and delayed healing of VLUs, also using air-plethysmography.14 This method was chosen as it can effectively evaluate components of venous hemodynamics relevant to VLU healing, including calf muscle pump function and venous obstruction.12
Simka studied 59 legs with open ulcers across a total of 48 patients between the ages of 33 and 87 to determine the ability of the calf muscle pump and the level of ulcer healing. Results showed that ulcers in patients with an insufficient muscle pump were larger and slower to heal. Simka states that defective calf muscle pumps are a common occurrence in patients with VLUs, often resulting in delayed healing.
It was concluded that patients with impaired muscle pumps were more likely to receive specialised treatment for their ulcers due to the stubbornness of healing, making self-management more challenging. It was also reported that calf muscle pump failure was, in some cases, related to decreased ankle mobility from painful ulceration in the area. In such cases, muscle pump failure can be reversible with increased mobility to promote blood flow.
Treatment for VLUs is also found to be more successful in patients with a sufficient muscle pump, as measured with the air-plethysmography.
Simka et al:
Simka later investigated VLU healing in another air-plethysmographic assessment of calf muscle pumps. 129 patients between the ages of 33 and 88 years were studied. Each patient had active leg ulcers at varying stages – ranging from one week to 25 years – and of varying sizes – between 1cm and 30cm. The results showed muscle pump failure in 42.6 percent of patients.
Patients with impaired pumps were older, had larger ulcers and experienced prolonged healing times. Calf muscle pump failure was more common in patients who had begun the treatment following unsuccessful, non-specialised care for prolonged periods. Even patients with a good clinical prognosis – those with small ulcers or with a short history of ulceration – showed a correlation between insufficiency of muscle pump and delayed healing.
Plethysmographic results suggest that ulcers with poor prognosis, combined with a lack of quick recovery following standard management, should be considered for advanced therapies.
Early intervention to manage the burden
These studies indicate a direct link exists between calf muscle pump ability and VLU healing, where defective pumps lead to harder to heal VLUs. Patients with calf muscle pump impairments are more likely to require specialised treatment and have less success managing the healing process independently at home.
As well as having significant negative impacts on the quality of life for these patients, delayed healing contributes to much higher healthcare costs, requiring more time and resources from healthcare professionals through specialised treatment. Routine plethysmographic assessment could help reduce this burden by identifying patients with calf muscle pump impairments sooner and referring them to specialised treatment earlier. Simka notes that calf muscle impairments can be reversed – indicating an early diagnosis of CVI could help prevent the development of hard to heal VLUs. This has the potential to save global healthcare systems money and time, both of which are gradually diminishing as our ageing population grows.