So a patient presents with forefoot pain, worse in the am upon awakening, with 1st weight bearing that would improve somewhat during the day, but would again get worse toward the end of the day and with increased activity. It began insidiously a few months ago (like so many problems do) and is getting progressively worse. Rest, ice and ibuprofen can offer some relief. You may see a dropped metatarsal head and puffiness and prominence in that area on the plantar surface of the foot, maybe not. Maybe you do a diagnostic ultrasound and see a lesion of the plantar plate as well? How did it get there?
Lets look at the anatomy of the short flexors of the foot, as well as some biomechanics of the foot, ankle and hip.
The flexor digitorum brevis (FDB) is innervated by the medial plantar nerve and arises from the medial aspect of the calcaneal tuberosity, the plantar aponeurosis (ie: plantar fascia) and the areas bewteen the plantar muscles. It travels distally, splitting at the metatarsal phalangeal articulation (this allows the long flexors to travel forward and insert on the distal phalanges); the ends come together to divide yet another time and each of the 2 portions of that tendon insert onto the middle of the middle phalanyx (1)
As a result, in conjunction with the lumbricals, the FDB is a flexor of the metatarsophalangeal and proximal interphalangeal joints. In addition, it moves the axis of rotation of the metatasophalangeal joints dorsally, to counter act the function of the long flexors, which, when tight or overactive, have a tendency to drive this articulation anteriorly .Do you see any subtle extension of the metatarsophalangeal joint and flexion of the proximal interphalangeal joints on your exam?
We know that the FDB contracts faster than the other intrinsic muscles (2), playing a role in postural stability (3) and that the flexors temporally should contract earlier than the extensors (4), assumedly to move this joint axis posteriorly and allow proper joint centration. When this DOES NOT occur, the metatarsal heads are driven into the ground, causing irritation and pain.
If there is also a loss of ankle rocker this problem is made (much) worse. Why? Because, with the loss of one rocker, another must make up for the loss: ankle rocker decreases, forefoot rocker has to increase; this equals increased metatarsal head pressure.
If you have been with us for any length of time, you know that ankle rocker and hip extension are intimately related, as one should equal the other, something we call “The “Z” angle”, that you have probably (hopefully?) read about here before.
So what is the fix? Getting the FDB back on line for one.
How about the toe waving exercise?
How about the lift spread reach exercise?
How about retraining ankle rocker and improving hip extension?
How about an orthotic with a metatarsal pad in the short term?
How about some inflammation reducing modalities, like acupuncture, ice laser and pulsed ultrasound.
Maybe some herbal or enzymatic anti inflammatories?
Dr Ivo Waerlop, one of The Gait Guys.
#gait #footpain #metatarsalgia #metatarsalpain #anklerocker #hipextension #thegaitguys
2. Tosovic D1, Ghebremedhin E, Glen C, Gorelick M, Mark Brown J.The architecture and contraction time of intrinsic foot muscles.J Electromyogr Kinesiol. 2012 Dec;22(6):930-8. doi: 10.1016/j.jelekin.2012.05.002. Epub 2012 Jun 27