Pediatric Flatfoot: When Do You Treat It?
Key Insights On The Pathomechanics Of Flatfoot
One should neutralize pathomechanical forces acting on the child’s foot from the earliest weightbearing in order to allow normal development of bone and soft tissue without undue stress and establish optimum foot function in stance and gait. The functional requirement of a stable platform once the child has begun to stand and for the stance phase of gait is compromised in the flat foot. Later, once the child has achieved propulsive gait, the ability of the foot to convert to a rigid lever is also altered in the flat foot.
A careful musculoskeletal exam including gait analysis will allow the clinician to build on information obtained in the history to identify the superstructural and pedal comorbidities that lead to compensation in the already challenged toddler foot. Experts agree that a positive family history of a consequential flat foot, evidence of a compensated, acquired flatfoot through skilled biomechanical evaluation and compromised gait function all elevate the index of suspicion in a pediatric flat foot and strongly suggest that one should consider treatment.
The presence of comorbidities in the biomechanical exam in the form of deviations from the normal for the child’s age marks these feet as “at risk” and provide a clear rationale for the astute clinician to act and to intervene on the child’s behalf. Unless and until these comorbidities resolve and cease to exert an untoward effect on the malleable foot compensating at the base of support, the physician should institute treatment.
Common comorbidities contributing to pediatric acquired pes planovalgus include residual transverse plane torsional problems such as femoral and tibial torsion and metatarsus adductus. Soft tissue components such as excessive internal hip rotation and pseudo torsion at the knee may also lead to pedal compensation. Frontal plane malalignments such as rearfoot and forefoot varus, tibial and genu varum may precipitate compensation. Sagittal plane contributions include equinus and limitations of dorsiflexion necessary for smooth excursion of the leg over the planted foot in gait. These may occur at the level of the foot, the gastroc-soleus complex, the hamstring and the iliopsoas muscles.
Numerous joints in the foot with sagittal plane dominance — such as the midtarsal joint, first ray and metatarsophalangeal joints — facilitate compensation and may lead to acquired deformities of the foot.
Systemic ligamentous laxity, as a component of a syndrome such as Marfan’s syndrome or as a familial or individual body type predisposes the child’s foot to be the compensatory site for superstructural influences.
Pertinent Pearls On Identifying Flatfoot
The weightbearing component of the lower extremity exam provides key information to identify the acquired pes plano valgus deformity and grade its severity. Decreased medial longitudinal arch height (navicular differential or drop) from off to on weightbearing is a useful screening tool. Significant drop with other changes such as medial and plantar prominence of the talus, abduction of the midfoot and frontal plane rotation of the hallux signal the presence of compensation and the abnormal foot position often associated with the onset of deformities.
Assessment of the relaxed calcaneal stance position (RCSP) to determine the degree of heel valgus on weightbearing is useful in grading severity. Systems such as the Valmassy formula can help the clinician to determine when heel valgus is excessive for a young child of a particular age.4 High heel valgus may indicate a frontal planal dominance to the deformity and, in some cases, may be associated with changes in the transverse plane such as medial talar deviation and midfoot abduction.