Diabetic Flat Foot
The foot is a highly-specialised structure. It endures much resilience and smoothness while performing many functions. In general, the foot works to support major loads, absorb shock and strong impacts, stabilises the lower limb, allows for balancing, accommodating and sensitizing the foot.
Diabetic feet are the target of almost all chronic complications to which a diabetic patient is subjected; neuropathy, peripheral vascular disease, dermatological conditions, foot deformity and wounds. Feet are known to be one of the primary causes of diabetic toe, foot and leg amputation and disability.
In Singapore, it is estimated that approximately, 1 in 6 diabetic patients will develop a foot and ankle problem. Other studies indicate that ulcers involving the diabetic feet are associated with mortality rate increase. At Singapore Diabetic Foot Centre, we know that diabetic foot or leg amputations can be avoided with the correct and most comprehensive diabetic foot care, offloading and advice available.
Many diabetic patients are concerned about the appearance of their foot arch shape, specifically flatfoot. It is assumed that the foot arches can be pushed up or corrected with insoles, most of the time with disregard to the diabetic condition underlying.
Flatfoot presents as either congenital/hereditary (inherited) or due to external factors (developed over time) whether a patient is diabetic or not. Studies show that diabetic patients are at an increased risk of flat foot or progressive medial arch lowering due to the long-term effects that diabetes, and specifically peripheral neuropathy, has on the soft tissues of the body.
From a young age, weaknesses across the feet can develop. This can be observed when the effectiveness of a toddler’s balance and walking skill is reduced. This is likely due to ligament laxity which allows the foot bones to shift and displace during development. Therefore, flatfoot can be observed at a young age and if it is left untreated it can become a problem for patients, especially those who end up with diabetes. These patients normally observe that they have flatfoot since young, it basically means they were not treated.
External factors (developed over time)
Diabetic patients whose blood sugar control is not well-maintained will start to experience neuropathy (numbness) and a reduction in their vascular supply to the feet. The feet change shape with the patients demonstrating insufficiency in their foot ligaments, particularly the spring-ligament complex, the talocalcaneal interosseous ligament, and the deltoid ligament. Tendons become calcified and harden into a less flexible position putting the patients at increased risk of diabetic foot complications. The main tendon affected is the posterior tibial tendon which holds up and functions a person’s foot arch, the disease of this tendon will allow the foot arch to collapse, often with pain.
Patients should look for changes in their foot function and structure:
- Arches lowering
- Clawing of toes/hammer toe development
- Painful areas of the feet
- Instability in the feet and ankles
- Inability to perform exercises or foot movements that were previously ok to do
- Areas of high pressure building up i.e. callus and corns
How diabetes leads to flatfoot:
- A foot can change from a flexed to a stiff structure if the bone structure and ligament or muscle support underlying is intact. In diabetic patients, this is found to be largely changed
- Neuropathy (numbness) leads to disarrangement of the intrinsic foot muscles, resulting in a loss of muscle, soft tissue and joint mobility in the foot
- These changes promote a collapse of the transverse and medial longitudinal arch creating more pressure on the metatarsal and toe region of the foot
- With increased foot-ankle complex stiffness and forefoot pressure, plantar areas of the foot produce more areas of hyper-keratinization (callus/corns) in response to mechanical pressure, friction and joint deformities
- These high-pressure areas develop underlying wounds or skin break down which are unable to heal due to the altered architecture of the diabetic foot
- With such advanced changes in the foot and ankle structure, patients may be experiencing adult acquired flatfoot deformity or a more severe diabetic complication i.e. Charcot foot
What can be done for diabetic flatfoot conditions?
Diabetic patients must undergo a comprehensive lower limb analysis to ensure the correct diagnosis is obtained. Many diabetic patients present to clinic with seemingly normal musculoskeletal pains in the lower limbs but on extensive examination may be neuro-vascular in nature or due specifically to their diabetic condition.
Podiatrists are skilled in determining the differences between a diabetic musculoskeletal condition and that of a more serious underlying disorder. X-rays may be obtained for ruling out underlying arthritic conditions and comprehensive assessment including pressure plate analysis must be carried out for patients who are to be offloaded adequately.
Orthopaedic changes in the diabetic foot lead to a loss in patient’s motor abilities that leads to joint instability and muscle imbalance which ultimately can induce foot and ankle dislocations or fractures that will lead to severe deformities of the lower extremity.
Diabetic patients must act fast if they suspect they have flatfoot, especially if they notice it develops within a short period or that they develop pain, redness or swelling within their foot.