Secrets To Performing Bunion Surgeries That Will Stand The Test Of Time

William Fishco DPM FACFAS

I am sitting in the Louisville airport waiting to catch a plane back to Phoenix. I thought this would be a good time to write my next blog. I had a great morning of giving lectures for the Kentucky Podiatric Medical Association where I spoke for a couple hours on various surgical and non-surgical topics. One lecture was on bunion surgery and I thought I would share some of my thoughts regarding the dreaded complication of recurrent or failed bunionectomy.

Why do bunionectomies fail? To simplify matters, either one never adequately repaired the deformity (residual deformity) or the deformity came back (recurrence). If the bunion came back immediately, then the correction was not adequate (unstable). If the deformity came back over 20 years later, I do not necessarily call that a failure. Let us face it. A lot can happen to feet in 20 years.

So what is the goal of bunion surgery? In simple terms … bump gone, toe straight. Sounds simple enough, right? I am convinced that the two main criteria that are necessary for a good outcome that will last for years include having the metatarsal head over the sesamoids and having a stable congruent joint.

In residency, we learned to do an adductor tendon transfer to grab the medial joint capsule and “derotate” the sesamoids. As we know now, the sesamoids are fixed in space. They do not move. So the only way to get the sesamoids under the metatarsal head is to put the metatarsal head over the sesamoids. If the metatarsal head is not over the sesamoids, then the pull of the flexor tendons will be lateral to the axis of joint motion, which leads to a deforming buckling force causing abduction of the hallux. This buckling phenomenon not only causes abduction of the hallux but also a force to spread the first metatarsal away from the second (increase in intermetatarsal angle).

The joint needs to be stable and congruent. An Akin osteotomy may straighten the toe’s appearance but it does not affect joint congruency. An aggressive lateral capsulotomy may allow you to straighten the toe after a medial capsulorrhaphy. However, that maneuver will destabilize the joint and may lead to a varus deformity. Destabilization of a joint is never a good thing.

I do believe in doing a lateral release of the fibular sesamoid ligament and adductor tendon. I am not as aggressive as I used to be with the release. I feel that as long as the fibular sesamoid is mobile and one can position the metatarsal head over the sesamoid, then the surgeon’s job is done. On occasion, if the sesamoid is frozen, then I will use a metatarsal elevator. With a longstanding deformity, I may do a tenotomy of the short flexor tendon at the distal pole of the fibular sesamoid. I rarely remove a sesamoid due to the instability that it causes.

So what osteotomy do you do? I do not think it matters too much. Whatever you decide to do, make sure you get reproducible and consistent results in adequately placing the metatarsal head over the sesamoids and establishing a congruent joint. Certainly it is important to allow stability of the medial column with your bunionectomy. Accordingly, one should avoid excessive shortening or sagittal plane malposition of the capital fragment.

What is the best fixation for a distal metatarsal osteotomy? Again, I do not think it matters. As long as you instill stability and sound principles of fixation, then you will get primary bone healing. In my opinion, K-wires are as effective as screws. When there is not adequate fixation, secondary bone healing occurs. This may lead to malposition of the capital fragment with possible excessive shortening. This can lead to other problems such as metatarsalgia, a non-purchasing hallux, and hallux malleus. Often times when this occurs, patients may be quite happy with the bunion surgery as the bump is gone but think they developed a new, unrelated problem.

Do you use fluoroscopy when doing a bunionectomy? When I first got into practice, I thought it was a sign of weakness to use fluoroscopy intraoperatively for a bunionectomy. After I got burned a few times, I started to use it. Today, I always use fluoroscopy not only to make sure my fixation (screw or K-wire) is properly positioned but also to make sure I have a congruent joint. I want to make sure my metatarsal head is over the sesamoids and that the base of the proximal phalanx is going to be seated correctly on the metatarsal head.

Before closing the wound, evaluate range of motion of the great toe joint. Certainly, if the toe is still tracking in abduction, you will need to do more soft tissue work (assuming that the metatarsal head is over the sesamoids). Occasionally, I will nibble off some bone on the medial condyle of the base of the proximal phalanx. That will sometimes help that problem. If you do not have an adequate lateral release, then you may need to do more work with the short flexor tendon and/or the fibular sesamoid.

After I am happy with the range of motion of the toe, alignment of the joint and position of the metatarsal head over the sesamoids, then I will consider an Akin osteotomy if the great toe is touching the second toe.

In short, it is not about removal of the bump, shifting the head over as far as you can or reducing the intermetatarsal angle. It is about establishing a stable congruent joint with the metatarsal head overlying the sesamoids. If you follow these two basic principles, you should get good results that pass the test of time.

Comments

I read your article "Secrets to performing bunion surgeries that will stand the test of time." In the article, you state that the two main criteria are for the metatarsal head to be overlying the sesamoids and establishing a stable congruent joint. What are some of the potential problems for not using fluoroscopy and over shaving the metatarsal, leaving the sesamoids exposed?

Thank you.

I don't think it is mandatory that you use fluoroscopy intraoperatively as a direct examination of the base of the proximal phalanx can be observed whether or not it is seated correctly on the metatarsal head. I like to use fluoroscopy to confirm adequate correction and that certain parameters are met (i.e.: reduction of intermetatarsal angle, joint is congruous, and hardware is in the ideal position).

The medial condyle should be sitting in the sagittal groove. If an excessive medial eminence is removed, then the medial condyle of the base of the proximal phalanx will not be stable on the metatarsal head, leading to over correction (varus deformity). In simple terms, the proximal phalanx will slip medially as there is no means for the base of the proximal phalanx to "stay on track."

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