There is much saying about bunions being only responsible due to genetic predisposition, in my opinion genetic by itself is rarely the cause of any condition. The epigenetics is what influence the genetic pathological predisposition of diseases to be expressed. Epigenetics is entirely influenced by environmental, emotional, and biomechanical factors the person has been exposed throughout their lives. The genetic inclined individual though, will have a much rapid development of bunions then a not genetic predisposed person once the foot mechanics is altered.
Mechanism of Dysfunction
The main predisposing factor for the development of bunions is the impaired foot mechanics caused by a compromised of the arches (see Flat foot page for detailed information) particularly the inner arch, therefore allowing the weight bearing stress to migrate further down the foot altering pedal action forces resulting in torsional force to the first metatarsal deviating and rotating medially, hence the appearance of the bunion deformity.
Is important to point out that the main misalignment is not at the level of the deformity (first metatarsophalangeal joint (big toe), is at the joint prior, at the first metatarsal cuneiform joint.
The entire lower extremity biomechanical chain must be evaluated as part of the foot/bunion analyses as per the neurological and mechanical influences of the spine, hip and knee.
Clinical assessment to identify the key joint dysfunctions of the Ankle/Foot following by three set of X-ray analysis.
Anterior – Posterior (AP) X-ray ankle view is essential for proper diagnosing the master joint of the ankle (Tibia-Talus) as the origin of poor arch mechanics starts from a dysfunctional ankle joint leading to hypermobility compensations that causes the appearance of the bunion.
Lateral Xray view is important to check the degree of the total arch compromised, specially the medial arch as per the direct influence it has with this deformity.
AP Xray foot view, aids to complete the total analysis of the transverse and lateral arches and is crucial to analyse the degree of the main bunion misaligned joint (first metatarsal cuneiform).
Due to the influences the foot arches have in the development of bunions, arch rehabilitation must be incorporated as part of the overall treatment.
Foot Arch treatment: Specific adjustments of key bones of the ankle and foot followed by a rehabilitation regime to strengthen the entire soft tissue arch support of the foot. In addition, application of tape and corrective orthotics may be needed as part of the early rehab program.
There are five direct important misalignments that needs to be addressed to aid on the reversion this deformity.
1 – First metatarsophalangeal joint (big toe) capsule bulge reduction
2 – Adjustment of the main bunion misaligned joint (first metatarsal cuneiform)
3 – Adjustment of the First metatarsophalangeal joint
4 – Reposition medially of the sesamoids bones
5- Adjustment of the sesamoids
Depending on the level of arch compromised and chronicity of the bunion a minimum of 6 weeks up to 12 weeks of treatment care may be necessary to resolve this deformity.