Flat Feet (Pes Planus).
What are flat feet?
Flat feet — medically termed pes planus — describe a foot in which the medial longitudinal arch is reduced or absent during standing, producing increased contact between the plantar surface of the foot and the ground. The condition exists on a spectrum from a mildly reduced arch to a completely collapsed foot, and its clinical significance varies accordingly.
Flat feet are extremely common — affecting approximately 20 to 30% of the general adult population — and the majority of people with flat feet have no pain or functional limitations at all. The presence of flat feet on assessment is a finding, not automatically a diagnosis requiring treatment. The relevant clinical question is whether the flat foot architecture is contributing to the patient's symptoms or limiting their function.
Flexible versus rigid flat feet — the most important distinction
This distinction determines what physiotherapy can realistically achieve and guides the management approach.
Flexible flat feet — the most common type — are characterised by a normal or near-normal arch when the foot is non-weight-bearing, which collapses when weight is applied. The underlying bony and joint structure is normal — the arch collapse reflects reduced muscular support and ligamentous laxity rather than structural deformity. Flexible flat feet respond well to physiotherapy — intrinsic foot muscle strengthening can meaningfully restore arch height and reduce the associated symptoms. This is the type where physiotherapy has the most to offer.
Rigid flat feet — where the arch is absent or severely reduced in both weight-bearing and non-weight-bearing positions — reflect fixed bony or joint deformity. Tarsal coalition (abnormal fusion of two or more tarsal bones), severe posterior tibial tendon dysfunction, and congenital deformities produce rigid flat feet. Physiotherapy and orthotic management address the consequences of the deformity but cannot structurally correct the underlying bony architecture. Severe rigid flat feet may ultimately require surgical reconstruction — see our flatfoot reconstruction page.
What causes flat feet?
In children, flat feet are extremely common and typically normal — most children have flat feet until the medial arch develops between ages 4 and 8, and the majority develop a normal arch without intervention. Persistent flat feet in older children and adults reflect a combination of genetic predisposition, ligamentous laxity, muscle weakness and in some cases structural factors.
Adult-acquired flat foot — where the arch progressively collapses in an adult who previously had normal arches — is most commonly caused by posterior tibial tendon dysfunction (PTTD), where failure of the primary dynamic arch support allows progressive collapse. Joint hypermobility is a significant contributor to flexible flat feet — generalised ligamentous laxity removes the passive arch support that normally supplements muscular effort during standing. Obesity increases the load on the arch structures beyond their capacity. Pregnancy — through the combined effects of weight gain and relaxin-mediated ligamentous laxity — commonly produces a temporary or permanent increase in foot pronation.
What symptoms do flat feet cause?
Most flat feet cause no symptoms. When symptoms do occur they typically include medial arch and heel pain from plantar fascia and arch muscle overload, plantar fasciitis, inner ankle pain from posterior tibial tendon overload, and fatigue in the feet and lower legs after prolonged standing. The altered foot mechanics of flat feet also contribute to downstream problems — excessive pronation at the foot increases internal tibial rotation during gait, which elevates stress at the medial knee and can contribute to patellofemoral pain, shin splints and metatarsalgia.
How are flat feet assessed?
A physiotherapist will conduct a thorough evaluation to assess the extent and nature of the flat foot, including gait analysis, the navicular drop test measuring arch height change from sitting to standing, and assessment of associated symptoms and functional limitations. The Jack's test — passive extension of the big toe — assesses the integrity of the plantar fascia windlass mechanism that is central to dynamic arch function. Strength testing of the posterior tibial tendon, intrinsic foot muscles and hip stabilisers identifies the specific muscular deficits contributing to arch collapse.
How can physiotherapy help?
Physiotherapy addresses both the local foot mechanics and the proximal lower limb contributors to flat foot symptoms. The approach targets strengthening, orthotic support and load management in a combination calibrated to the individual's arch type, symptom pattern and functional goals.
Intrinsic foot muscle strengthening — the short foot exercise, toe spreading, and progressive resistance work for the foot intrinsics — directly strengthens the muscles that actively support the medial arch. These muscles atrophy with prolonged orthotic dependence and their strengthening is the most important active component of flat foot rehabilitation. This is particularly valuable for flexible flat feet where the underlying bony structure is normal and muscular support can meaningfully change arch height.
Posterior tibial tendon strengthening — the primary dynamic arch supporter — is central to management of PTTD-related flat foot. Progressive calf and posterior tibial strengthening restores the dynamic arch support and reduces progressive collapse.
Hip abductor and gluteal strengthening addresses the proximal contributor to foot pronation — weak hip abductors allow dynamic hip adduction during stance which increases foot pronation regardless of the foot's intrinsic structure. Addressing this proximal pattern is one of the most effective and most frequently overlooked interventions for flat foot-related lower limb symptoms.
Orthotic management — semi-rigid or custom orthotics with medial arch support — provides mechanical support for the arch during the strengthening program and may be used long-term for severe flexible or rigid flat feet where strengthening alone is insufficient. The goal for flexible flat feet is progressing toward reduced orthotic dependence as intrinsic strength improves — not permanent passive dependence on external support.
Footwear assessment — shoes with adequate arch support, a firm heel counter and appropriate motion control properties — reduces the mechanical demand on the arch during daily activities.
Clinical Pilates provides an excellent environment for progressive foot and lower limb strengthening. Real time ultrasound can assist in assessing posterior tibial tendon function and deep intrinsic foot muscle activation.
Our physiotherapists Eliane Machado and Emma Cameron both have experience in foot conditions and are members of the Australian Physiotherapy Association. Eliane's doctoral research in lower limb biomechanics is directly relevant to the gait analysis and foot loading assessment underpinning flat foot management.
To book or find out more, call us on 07 3706 3407 or book online below. We see patients from across Brisbane's southside including Tarragindi, Coorparoo, Holland Park, Greenslopes and Mt Gravatt.
Flat feet — medically termed pes planus — describe a foot in which the medial longitudinal arch is reduced or absent during standing, producing increased contact between the plantar surface of the foot and the ground. The condition exists on a spectrum from a mildly reduced arch to a completely collapsed foot, and its clinical significance varies accordingly.
Flat feet are extremely common — affecting approximately 20 to 30% of the general adult population — and the majority of people with flat feet have no pain or functional limitations at all. The presence of flat feet on assessment is a finding, not automatically a diagnosis requiring treatment. The relevant clinical question is whether the flat foot architecture is contributing to the patient's symptoms or limiting their function.
Flexible versus rigid flat feet — the most important distinction
This distinction determines what physiotherapy can realistically achieve and guides the management approach.
Flexible flat feet — the most common type — are characterised by a normal or near-normal arch when the foot is non-weight-bearing, which collapses when weight is applied. The underlying bony and joint structure is normal — the arch collapse reflects reduced muscular support and ligamentous laxity rather than structural deformity. Flexible flat feet respond well to physiotherapy — intrinsic foot muscle strengthening can meaningfully restore arch height and reduce the associated symptoms. This is the type where physiotherapy has the most to offer.
Rigid flat feet — where the arch is absent or severely reduced in both weight-bearing and non-weight-bearing positions — reflect fixed bony or joint deformity. Tarsal coalition (abnormal fusion of two or more tarsal bones), severe posterior tibial tendon dysfunction, and congenital deformities produce rigid flat feet. Physiotherapy and orthotic management address the consequences of the deformity but cannot structurally correct the underlying bony architecture. Severe rigid flat feet may ultimately require surgical reconstruction — see our flatfoot reconstruction page.
What causes flat feet?
In children, flat feet are extremely common and typically normal — most children have flat feet until the medial arch develops between ages 4 and 8, and the majority develop a normal arch without intervention. Persistent flat feet in older children and adults reflect a combination of genetic predisposition, ligamentous laxity, muscle weakness and in some cases structural factors.
Adult-acquired flat foot — where the arch progressively collapses in an adult who previously had normal arches — is most commonly caused by posterior tibial tendon dysfunction (PTTD), where failure of the primary dynamic arch support allows progressive collapse. Joint hypermobility is a significant contributor to flexible flat feet — generalised ligamentous laxity removes the passive arch support that normally supplements muscular effort during standing. Obesity increases the load on the arch structures beyond their capacity. Pregnancy — through the combined effects of weight gain and relaxin-mediated ligamentous laxity — commonly produces a temporary or permanent increase in foot pronation.
What symptoms do flat feet cause?
Most flat feet cause no symptoms. When symptoms do occur they typically include medial arch and heel pain from plantar fascia and arch muscle overload, plantar fasciitis, inner ankle pain from posterior tibial tendon overload, and fatigue in the feet and lower legs after prolonged standing. The altered foot mechanics of flat feet also contribute to downstream problems — excessive pronation at the foot increases internal tibial rotation during gait, which elevates stress at the medial knee and can contribute to patellofemoral pain, shin splints and metatarsalgia.
How are flat feet assessed?
A physiotherapist will conduct a thorough evaluation to assess the extent and nature of the flat foot, including gait analysis, the navicular drop test measuring arch height change from sitting to standing, and assessment of associated symptoms and functional limitations. The Jack's test — passive extension of the big toe — assesses the integrity of the plantar fascia windlass mechanism that is central to dynamic arch function. Strength testing of the posterior tibial tendon, intrinsic foot muscles and hip stabilisers identifies the specific muscular deficits contributing to arch collapse.
How can physiotherapy help?
Physiotherapy addresses both the local foot mechanics and the proximal lower limb contributors to flat foot symptoms. The approach targets strengthening, orthotic support and load management in a combination calibrated to the individual's arch type, symptom pattern and functional goals.
Intrinsic foot muscle strengthening — the short foot exercise, toe spreading, and progressive resistance work for the foot intrinsics — directly strengthens the muscles that actively support the medial arch. These muscles atrophy with prolonged orthotic dependence and their strengthening is the most important active component of flat foot rehabilitation. This is particularly valuable for flexible flat feet where the underlying bony structure is normal and muscular support can meaningfully change arch height.
Posterior tibial tendon strengthening — the primary dynamic arch supporter — is central to management of PTTD-related flat foot. Progressive calf and posterior tibial strengthening restores the dynamic arch support and reduces progressive collapse.
Hip abductor and gluteal strengthening addresses the proximal contributor to foot pronation — weak hip abductors allow dynamic hip adduction during stance which increases foot pronation regardless of the foot's intrinsic structure. Addressing this proximal pattern is one of the most effective and most frequently overlooked interventions for flat foot-related lower limb symptoms.
Orthotic management — semi-rigid or custom orthotics with medial arch support — provides mechanical support for the arch during the strengthening program and may be used long-term for severe flexible or rigid flat feet where strengthening alone is insufficient. The goal for flexible flat feet is progressing toward reduced orthotic dependence as intrinsic strength improves — not permanent passive dependence on external support.
Footwear assessment — shoes with adequate arch support, a firm heel counter and appropriate motion control properties — reduces the mechanical demand on the arch during daily activities.
Clinical Pilates provides an excellent environment for progressive foot and lower limb strengthening. Real time ultrasound can assist in assessing posterior tibial tendon function and deep intrinsic foot muscle activation.
Our physiotherapists Eliane Machado and Emma Cameron both have experience in foot conditions and are members of the Australian Physiotherapy Association. Eliane's doctoral research in lower limb biomechanics is directly relevant to the gait analysis and foot loading assessment underpinning flat foot management.
To book or find out more, call us on 07 3706 3407 or book online below. We see patients from across Brisbane's southside including Tarragindi, Coorparoo, Holland Park, Greenslopes and Mt Gravatt.
