First Ray Mechanics
The first ray is very important for the function of the medial arch. The first ray acts as shock absorber and a rigid lever. When you land from taking a step, the arch acts to absorb impact, the ball of the foot slightly moves away from the heel. At take off, the ball of the foot migrates towards the heel in the supinatory phase of gait, to help stabilize the foot for propulsion. At toe off plantarflexion of the ankle arises and subsequent plantar flexion of the metatarsal head and dorsiflexion of the toes, which activates the windlass mechanism.
When the foot is too rigid or too mobile, a predisposition to injury can result. When too rigid, the arch cannot absorb shock. A rigid foot type does not allow for the calcaneus to pronate. Perhaps when a tissue cannot dissipate load to other parts of the body, the area of load becomes locally overloaded. That could result in injuries to that area. If injuries do arise from weakness in the foot and ankle, here at InStride, we can help treat you back to function!
On the other hand, a hypermobile foot does not allow the arch to get back to a “stiffened” position at toe off, leading to further stretch on the medial arch. That can lead to issues from over lengthening. Too much or too little of either motion at the wrong time of the gait cycle leads to inefficient foot function.
First Ray Insufficiency is when the first ray is not stable enough to resist ground reaction forces. Ground reaction forces push up, “elevates/ dorsiflexes ” the first ray. This can lead to jamming of the joint at toe off, leading to osteoarthritis in the joint, or overloading metatarsal heads 2-5. When joints 2-5 are overloaded it can cause neuromas, stress fractures and metatarsalgia.
With first ray insufficiency, failure of the first ray to properly plantarflex relative to the hallux, the ability for the first metatarsophalangeal joint to dorsiflex is inhibited. When the first metatarsal cannot dorsiflex, the windlass mechanism cannot engage. The windlass mechanism is not able to engage the foot and becomes unstable and injuries of the foot can happen.
When the windlass mechanism is engaged the plantar fascia shortens. When the windlass mechanism is disengaged, the plantar fascia lengthens. This could be perhaps a precursor in plantar fascia injuries due to the prolonged lengthening of the fascia band. This traction force is one of the reason heel spurs can arise.
The first ray is important in walking and running. This complex can become weakened from wearing narrow footwear. Narrow footwear can weaken the first ray by inhibiting muscles from properly functioning. The muscle that helps to support the arch and flex the big toe is the abductor hallicus. If that muscle cannot work over a regular basis when walking and running it becomes weakened. Injuries such as plantar fasciitis, bunions, hallux limitus and other foot injuries can be cause by problems with the first ray function. Here at InStride, we can help you strengthen your foot and ankle to improve this deficit.