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Hallux Valgus

Hallux valgus is caused by hypermobility at the tarsal metatarsal joint. That is the joint right about here, that’s the joint that separates the first metatarsal from the cuneiform, so the junction of the midfoot and the forefoot, and over time, as weight bearing occurs, you develop laxity. Therefore, instead of this being a rigid stabilizer when the first metatarsal head strikes the ground, it actually drifts off. Well, as the first metatarsal head drifts off, that is going to decrease the medial longitudinal arch.

She came to see me because her bunion was bothering her, and was rubbing in her shoe and her second toe was bothering her, but she said, oh yes, I sort have been losing my arch over time. Also, as the arch collapses here, there is also a problem with the Achilles tendon.

As the arch drifts down, you can sort of think of the heel as drifting up, shortening the distance for the Achilles tendon mechanism to work. It becomes contracted. It begins to overload the forefoot even more, more hypermobility develops, more bunion problems. Here is an example of that hypermobility that I’m talking about. Here, we’re looking from the side of the lady’s foot. What I’ve done here is demonstrate that I have the first metatarsal aligned with the other metatarsals. As you can see, here is the first metatarsal.

When I try to displace the first metatarsal dorsally with my thumb, you can see how that rises up and now you can’t see across the foot, you can just barely see the second toe here, where before you could see it clearly. Another thing you can notice is that bunion, which looks prominent there, looks even more prominent here, because as that metatarsal drifts up, it is also drifting out, so if you were looking at this slide, it’s drifting out into your direction, so it’s going to rub even harder in the shoe. Again, as the hypermobility develops back here at the tarsal metatarsal joint and this first metatarsal drifts medially and up, hallux valgus develops.

Because this first metatarsal head doesn’t touch the ground well, weight goes to the second metatarsal, a lot of overload occurs at the second metatarsal head and the second MTP joint. That weakens the structures on the plantar aspect of that joint and the toe begins to cockup or hammer-up, and there this lady circled her point of pain. This is constantly rubbing in her shoe. Also, the arch side begins to worsen, again, as the first metatarsal comes up, the arch starts to hit the ground.

So what’s the treatment for this? Well it needs to be directed at the primary problem, then we can also deal with the secondary manifestations. We need an orthotic to support the arch, we need to deal with that arch sag and that hypermobility that is going along at the tarsal metatarsal joint.

We need to do physical therapy. They need to strengthen the posterior tibial tendon, as I said before, that is the tendon that is going to help support the arch. They also need to work on the peroneus longus tendon. As we get later in the talk, the peroneus longus tendon runs along the lateral border of the foot, it then runs under the arch of the foot to attach to the base of the first metatarsal, so you can imagine if that tendon pulls hard, if there is active contraction, it’s going to pull the first metatarsal down.

The other thing is, appropriate shoe wear. They have to be in shoes that fit the shape of their foot. When someone has a hallux valgus deformity, they are very wide through here. They tend to get shoes that narrow and taper here so that there is rubbing.

Another reason why people get hammertoes is they have neuromuscular problems which usually manifest as pes cavus or a very high arched foot. But as this mechanical overload occurs and it’s tendon imbalance occurs, what are some of the secondary things that happen? Well, the fat pad migrates. You can imagine if your toes go from being straight to being curled up, you start to thin out the padding under those metatarsal heads. You are pulling it distal, you are pulling it beyond the metatarsal heads, so now you don’t have the normal cushion to take the weight bearing surfaces. Also, as your toes curl up, as the proximal phalanx in each toe extends, the first metatarsal head is effectively driven down through the bottom of the floor, again, now you’re pushing that metatarsal head out the bottom of the foot so to speak, and that hurts, and then you get the callous formation, that is the obvious manifestation of too much weight and too small an area. So what do we need to do to treat this? Well, we need to offload the metatarsal head and this slide over here showing you some very simple things that can be done for this, they are called metatarsal pads. These have a sticky back adhesive, you can put them directly into patient’s shoes, you can send them to a shoe shop, they can do that for you as well. But the idea here and I described this as you want to make the metatarsal heads float. You don’t want the metatarsal heads to hit the ground so hard. Again, too much pressure, inflammation of the joint, the toes are curling up.