I learned early in my training from my teachers and mentors that understanding body planes in lower extremity biomechanics is a key to getting good results. The influences on the foot from the superstructure in the transverse, frontal and sagittal planes are instrumental in causing compensation in the foot, often leading to symptoms. We often focus on foot pathology in isolation and, in doing so, fail to recognize the major contribution of superstructural influences on foot position and function.
Green and Carol were among the first to call attention to the importance of body planes in understanding patient pathology.1 They reminded us that deformities in certain planes will compensate at joints that have dominance in that same plane. This is the foundation for linking plane-based compensation to plane-based etiology.
Once the compensated foot undergoes a full evaluation to determine the plane(s) of compensation, the work begins of determining the cause of the compensation.
The comprehensive lower extremity biomechanical and superstructural exam will yield many of these etiologies. For example, the child with a femoral antetorsion and a high motion lax foot type will often exhibit medial migration of the talus over the calcaneus at the subtalar joint and abduction of the cuboid on the calcaneus at the midtarsal joint. In another case, the athlete with tight hamstrings and an acquired pes plano valgus will demonstrate low calcaneal inclination, a broken cyma line and navicular-cuneiform sag, contributing to an acute bout of plantar fasciitis.
Identifying this causal relationship between plane of deformity and plane of compensation makes us smarter clinicians. In the case of the child with the underlying femoral antetorsion causing the transverse plane compensatory pes valgus, an orthosis with flanges will help manage the foot in this plane. I might also add a gait plate extension to induce out-toe in this child, anticipating that once the orthosis controls foot compensation, the proximal torsion — which was masked by the abducted pes valgus — will now be evident as an in-toe gait.
In the case of the athlete with plantar fasciitis associated with a sagittal plane pes valgus as compensation for hamstring equinus, an orthosis (with minimal plaster and calcaneal pitch) which controls this foot without addressing the equinus influence will be difficult to tolerate and likely unsuccessful. A heel raise to mitigate the influence of the equinus on the acute symptoms and improve the ability of the patient to tolerate the control is indicated. Simultaneously, a stretching program to relieve the hamstring influence should commence.
In both of the above cases, had the doctor failed to look at the superstructure thoroughly in the biomechanical exam, he or she would have missed the critical femoral torsion and hamstring equinus. Orthoses made for these patients without this knowledge could lead to problems such as unanticipated in-toe in the child and failure for the athlete to tolerate the orthosis.
Understanding body planes also plays an important role in surgical planning. A procedure that realigns a bone or joint in a particular plane or planes is best indicated when the deforming force and resultant compensation are in that same plane or planes. Choosing a procedure that fails to correct the plane of the deformity may lead to poor results.
In summary, podiatric physicians should assess patient compensation with reference to body planes and work back from there to find the causes of those compensations. Only then can your management plan address both the cause and the effect.
1. Green D, Carol A. Planal dominance. JAPMA 1984; 74(2):98-103.