The Ageing Foot

Original Editor - Ewa Jaraczewska based on the course by Helene Simpson

Top Contributors - Ewa Jaraczewska, Jess Bell and Kim Jackson  

Introduction

One in four older adults have foot pain. Foot pain can affect walking and contribute to falling and functional disability in older adults. The aetiology of foot pain is often multifactorial. Foot pain may be caused by musculoskeletal pathologies, as well as vascular and Neurological Disorders, but the three major foot problems in older adults are pain, neuropathy, and deformities. The most common orthopaedic deformities in the elderly include hallux valgus, prominent metatarsal heads, and an abnormal medial arch structure. Overall, foot deformities and other foot conditions are highly prevalent in adults aged over 65 years, which is significant as these conditions are associated with frailty and decreased physical activity.This article will discuss age related changes in the foot and suggested therapeutic interventions to improve balance, decrease risk for falls, and prevent or reduce skin and functional changes. It highlights the need for education and remediation regarding footwear advice in older adults.

Risk factors

The following are risk factors for foot problems in older adults:

• Gender (women are more frequently affected than men)
• Obesity
• Chronic conditions, including diabetes and osteoarthritis
• Peripheral neuropathy
• Neurological disorders (e.g. stroke, Parkinson's)
• Lower extremity oedema (can be related to vascular or cardiac pathology)
• Inappropriate footwear
• Underlying geriatric syndromes and conditions

Age-Related Changes in the Foot

Physiological changes

Skin

Weight-bearing activities place specific demands on the skin of the foot's plantar surface. The foot has certain features to accommodate these loads: the epidermis is thicker in the foot compared to other parts of the body; the dermis is around 3mm thick and has adipose tissue that can resist sheer forces; and the fingerprint-like pattern of the epidermis helps to generate enough friction during walking. However, all aspects of the skin change as a person ages. These changes affect not only the superficial skin but also the local vascular response, thermoregulation, sensory perception, and injury response, and they include:

• Flattening of the dermo-epidermal junction
• Decreased contact between the dermis and epidermis, which causes the skin to separate along this interface
• Loss of elastin and collagen fibres in the dermis. The dermis becomes atrophic. There is a reduction of fibroblasts, and the collagen becomes disorganised. The remaining collagen fibres become thicker and stiffer.
• Limited ability by the dense collagen to recoil, which leads to increased compression and development of hyperkeratosis (corns and calluses)
  • Hyperkeratosis is defined as increased thickness of the outer layer of the skin
• Alteration in the mechanical properties of the plantar skin, leading to increased hardness and dryness
• A reduction in the density of sweat glands, which contributes to impaired thermoregulation
• Loss of subcutaneous fat and decreased dermal vascularity, leading to poor thermoregulation
• Reduced sensation to touch, pressure, and vibration due to decreased mechanoreceptors (Meissner and Pacini corpuscles)

Overall, the thickening of the exterior layer of the skin and the presence of calluses may lead to the development of plantar lesions, causing severe pain and disability. The best management strategies are custom-made orthotics, which support the medial arch and unload the metatarsal heads.

Soft Tissue

The role of the plantar soft tissue is to protect underlying blood vessels and nerves and to reduce the shear forces that occur while walking. Ageing has a direct impact on the foot's soft tissues, causing progressive stiffness. In particular, it affects the tissue at the big toe, first, third, and fifth metatarsal heads, and the heel. The metatarsal pad becomes slower to recover after being compressed. Similarly, the heel pad dissipates more energy when compressed, the plantar fascia demonstrates less recoil due to stiffness. The consequences of the soft tissue ageing process are:

• Range of motion reduction (especially in ankle dorsiflexion)
• Achilles tendon complaints
• Changes in gait pattern: more pull-off vs pushing-off, less propulsion
• Increased risk of falls

Range of Motion

The ageing process affects joint physiology, leading to joint stiffness. Changes include:

• Reduction in the water content of the cartilage
• Reduction in the synovial fluid volume and proteoglycans
• Bonding of the collagen fibres

A decreased ankle dorsiflexion and subtalar joint inversion-eversion range in older adults contribute to their reduced ability to perform dynamic tasks, maintain static standing balance, and perform functional activities.

Hallux Valgus deformity

Muscle Strength

Progressive changes in skeletal muscle mass (sarcopenia), metabolism and functional capacity are typical in the ageing population. Older adults experience a reduction in the size and number of muscle fibres in their foot muscles. Large, slow-twitch motor units develop and type II fibres become denervated. These changes indicate the presence of age-related atrophy, which can be exacerbated by wearing poorly fitting footwear long-term. The consequences of atrophy of the foot muscles in the elderly include:

• Decreased ankle plantar flexor strength (causes difficulty rising onto the toes)
• Weakness of the toe plantar flexors, which negatively affects the grasping function of the toes during weight-bearing activities (impaired static and dynamic balance and functional ability, increased risk of falls)
  • toe grip strength (TGS) decreases by 30% in older patients compared to younger patients
  • toe grip weakness has been associated with developing forefoot deformities and disorders
• Development of toe deformities (hallux valgus and lesser toe deformities)
  • They alter weight distribution under the foot when walking
• Lower ambulatory performance

Arches of the foot

Biomechanical Changes

Age-related changes in soft tissue, range of motion, and muscle strength lead to the following biomechanical changes:

• The lowering of the medial longitudinal arch
• Reduced midfoot and metatarsal mobility
• Flatter and more dynamically pronated feet
• Planus foot posture
• Less plantarflexed calcaneus at the toe-off phase of gait
• Less propulsive gait pattern

Physiotherapy Intervention

General Principles

1. Do not focus on just the foot
2. Assess the kinetic chain: look at posture, weight distribution, and centre of mass distribution
3. Offer a programme which includes stretching and strengthening
4. Use manual techniques to reduce tissue stiffness
5. Stimulate the plantar sensors
6. Assess footwear
7. Be careful when choosing orthotics for medial arch support: do not make the foot stiffer

Therapeutic Interventions

Manual Techniques

Manual techniques mobilisation of the stiff foot and stimulating the plantar sensory receptors to increase proprioception and improve balance.

Mobilisation techniques can be one or more of the following:

• Mobilisation with movement: application of gentle pain-free overpressure to an end-range movement
• Anterior/posterior talocrural joint mobilisation in weight-bearing and non-weight-bearing positions, which aims to for improving DF range of motion
• Subtalar joint mobilisation for eversion and inversion
• Mid-tarsal mobilisation for pronation and supination of the midfoot

Plantar-sensory treatments may include the following:

• Plantar massage
• Whole-body vibration
• Textured surface-stimulation treatment

According to Hu et al., patients with chronic ankle instability may have better postural control after applying plantar-sensory treatments. Plantar massage and long-term whole-body vibration were found to be the most effective.

A randomized clinical trial by McKeon and Wikstrom, found that sensory-targeted ankle rehabilitation strategies improved single-leg postural control. One treatment was sufficient for the change to occur. However, it did not offer a long-lasting effect.

Stretching

Calf muscle stretching is recommended to reduce pressure on the forefoot.

The following complications may be associated with an increased forefoot pressure:

• excessive pressure on the plantar aspect of the forefoot
• an increased plantar pressure due to premature forefoot with ground contact
• limited arterial perfusion to the forefoot plantar tissue for a prolonged time could increase the risk of ulceration or delayed foot ulcer healing

Calf muscles stretching outcomes:

• several weeks of calf muscle stretch training improves ankle joint flexibility and dorsiflexion range of motion
• reduction in the pathological forefoot pressures
• improvement in dynamic gait pattern

Strengthening of the Foot Intrinsic Muscles

Strengthening: toe strengthening exercises to improve the strength of the intrinsic muscles of the foot, increase the stability of the arch, and improve the toe-off phase of gait and balance during ambulation.

The roles of the intrinsic muscles of the foot include the following:

• stabilise the foot during balance on one foot
• support the medial longitudinal arch
• maintain concavity during walking
• stabilise the tarsal and metatarsal bones
• control the amount and speed of pronation of the foot

Examples of toe strengthening exercises include using toes to scrunch up the towel while the rest of the foot remains in contact with the ground.

Footwear and Orthotics

Footwear assessment:

Ill-fitting shoes are one of the major underlying causes of foot problems in the older population.

• Tight footwear can lead to callus formations or corns with skin hyperkeratosis and ulceration.
• Tight and narrow footwear is linked to the development of hallux valgus deformity, or bunion.
• Dorsal foot pain, as one of the symptoms of lesser toe deformities, such as hammertoes, tends to get worse with ill-fitting footwear.

O'Rourke et al. found that older adults often wear incorrectly fitting shoes or shoes with unsafe features, like slippers. Wearing slip-on slippers means the toe must grab even more to hang onto the slipper. This can contribute to the drop of the medial arch and the development of hammer toes.

Footwear modification:

• Soft to cushion the foot and supportive to prevent the foot from collapsing.
• Wider and higher-toe box shoes.
• Foot inserts improve arch support, facilitate balance and decrease the width of the foot during weight-bearing manoeuvres.
• Metatarsal pads and splits can help to limit the need for extra-depth shoes.
• Higher collars offer better support for balance.
• Extra-depth shoes are recommended for hammertoes or mid-foot arthrosis.
• Low-heeled footwear reduces the risk of falls.
• Athletic shoes and sneakers are associated with the lowest fall risk.
• Slip-resistant soles are recommended inside and outside the household to reduce the risk of falls.

Orthotics:

Introduction to Orthotics: collaboration with an orthotist to make a custom-made orthosis that supports the medial arch without increasing foot stiffness. The proper orthotics should allow for increased shock absorption capacity in the foot.

• Customised foot orthosis with medial longitudinal and transverse arch supports on the plantar pressure redistributes plantar pressure and contact area and enhances the functional support of the mid-foot.
• Rigid medial arch support orthoses provide better feedback to improve stability in flat foot patients.
• Foot orthoses with arch support help to redistribute plantar foot pressure and relieve foot pain.
• Medial forefoot and rearfoot postings should be considered in addition to arch support for more aggressive flatfoot posture correction.

The following video discusses how progression in age effect feet and person's mobility.

Resources

• Frailty as an Outcome Predictor After Ankle Fractures: Where Are We Now?
• Does the shoe really fit? Characterising ill-fitting footwear among community-dwelling older adults attending geriatric services: an observational cross-sectional study.