There are many procedures for hallux valgus and there are varying definitions of what constitutes a successful procedure. Accordingly, this author examines why bunionectomies fail, expounds on pertinent factors that impact healing and reduce recurrence risk, and explains how to advise patients on potential pitfalls of their surgery.
Hallux valgus reportedly occurs in 23 to 35 percent of the shoe-wearing population.1 We know that bunions are more prevalent in shoe wearing populations, older people and in women.1 To that end, bunion surgery is commonplace for the podiatric surgeon. In the literature, more than 100 procedures have been reported in the correction of hallux valgus, which means that there is no “gold standard” surgical approach to the correction of the deformity. Many of those 100 procedures have fallen out of favor. However, many options and their variations are well accepted and surgeons utilize them regularly.
A common question that patients ask me is, “What is the success rate for bunion surgery?” That is a good question that I have trouble answering.
The best I can tell my patients is that it works most of the time. Certainly, there are subjective and objective parameters to consider when deeming a bunion surgery successful. Most of us will opine that the surgeon is much more critical than the patient when determining good results. For the patient, pain must resolve and the appearance should be acceptable. From the surgeon’s perspective, success is based on a combination of appearance, function, range of motion of the great toe joint, and radiographic analysis.
Just like any other surgery, bunion surgery can fail. A list of the more common complications leading to failure include: loss of correction, under- or over-correction, delayed union, malunion or non-union of osteotomy or fusion, joint stiffness, nerve entrapment, and excessive shortening of the first metatarsal leading to lesser metatarsal overload. As we all know, other complications may include hardware failure/irritation, infection, prolonged swelling, deep venous thrombosis and complex regional pain syndrome. Luckily, most of these serious complications are relatively rare.
The most popular techniques that podiatric surgeons employ include distal metatarsal osteotomies, which are popular due to their consistent good results and uncomplicated postoperative protocol. Unfortunately, this type of technique, which we all feel very comfortable and confident with, cannot fix all bunion deformities. If an Austin type bunionectomy can fix 95 percent of bunion deformities, then you will have at least a 5 percent failure rate. This assumes that you have no complications every time you perform an Austin bunionectomy.
Of course, this is all theoretical and the point that I am making is that to be a skilled surgeon, you have to know when you can do your “favorite” procedure and when you need to do something that you are less comfortable performing. Remember the old adage: if all you have is a hammer, then everything is a nail.
Keys To Appropriate Procedure Selection
So how do you choose the appropriate bunion procedure to perform? Is it based on evaluation of the intermetatarsal angle on X-ray? Do you take measurements? Do you use templates? How does the clinical exam play a role in your decision making?
I personally feel that the flexibility (or lack thereof) of the first ray and metatarsophalangeal joint (MPJ) is the most important element that one needs to evaluate when selecting a procedure. Unfortunately, this is often an intraoperative finding that arises after performing the modified McBride procedure. Therefore, intraoperative decisions have to happen. I teach my residents that you cannot just go through the technical aspect of an Austin bunionectomy without performing range of motion of the great toe joint and/or evaluating where the proximal phalanx aligns to the metatarsal head.
I generally think of two types of bunion deformities. There is a functional bunion, which tends to be very flexible. You can manually reduce the functional deformity by taping the foot (squeezing the metatarsal heads together) or increase the deformity by sticking your thumb in the interspace, causing splay. A structural bunion deformity is typically a rigid deformity that one cannot easily manipulate. A radiographic clue may be an intermetatarsal joint between the first and second metatarsals, or a patient with metatarsus adductus.
As a general rule, surgeons can correct functional bunions with distal metatarsal osteotomies and structural ones need proximal osteotomies or fusion of the first tarsometatarsal joint (i.e. Lapidus). Certainly, there are exceptions to the rules and surgeons may base decisions on other factors such as first metatarsal length, quality of the cartilage and the amount of intermetatarsal correction that will be necessary to get the first metatarsal head over the sesamoids, thereby obtaining a congruent joint.
Why Bunion Surgeries Fail And How To Avoid The Pitfalls
My personal feeling is that the number one reason that a bunion “comes back” is that one never completely corrected it. This may in part be due to choosing a procedure that was inadequate to correct the deformity. Surgeon error is not the only cause for failure. Patient non-adherence and other tangibles most definitely play a role.
So what does it take to “correct the deformity”? Most will say reduction of the intermetatarsal angle. I do feel that is important but not as critical as having the metatarsal head over the sesamoids and having a congruent first metatarsophalangeal joint.
If you do not have a congruent joint, you will be doomed to having a recurrent deformity over time. The buckling effect on the first metatarsal will eventually cause splay and an increase in the intermetatarsal angle. Even if the surgeon performs a Lapidus bunionectomy and the great toe joint is not congruent, splaying will occur at the intercuneiform joint. Now we are seeing more surgeons employ an intermetatarsal “spot weld” technique in addition to fusing the first tarsometatarsal joint by fusing the base of the first and second metatarsal to eliminate the potential intercuneiform splay.
Remember, the sesamoids and the base of the proximal phalanx of the great toe are fixed in space. The sesamoids are anatomic but the metatarsal is not. When the sesamoids are visible under the first metatarsal head, we know the periarticular soft tissues are all in alignment. For example, the extensor tendon apparatus is going to be located directly over the long flexor tendons. If the metatarsal head is not sitting over the sesamoids, the flexor and extensor tendons are going to be lateral to the the long axis of the great toe joint, leading to buckling of the joint. The opposite effect occurs with over-correction of a bunion in which the tibial sesamoid is medial to the metatarsal head, causing buckling of the toe (in the opposite direction) and leading to hallux varus.
Over-shortening of the first metatarsal can lead to serious problems. The patient may be thrilled that the bunion is gone (i.e. bump gone and toe straight), but the resultant pain under the second metatarsal head can be challenging to treat. Typically, the first and third metatarsal should be about the same length with the second metatarsal slightly longer. When the first metatarsal is the same length as the fourth metatarsal, there is a likelihood of lesser metatarsalgia. Over-shortening may be a result of osteopenia, inadequate fixation of the osteotomy, a poorly executed osteotomy or the patient started out with a short first metatarsal prior to surgery. Of course, it may be a combination of many factors. Certain osteotomy types, such as the Mitchell procedure, are known to cause excessive shortening.
In my experience, delayed union and non-unions are relatively rare even with a Lapidus procedure. Certainly, risks for this complication are higher in smokers, patients with diabetes and those with vitamin D deficiency.
Malunion of a distal metatarsal osteotomy occurs on occasion. It typically involves excessive dorsiflexion or plantarflexion. In both cases, a non-purchasing toe may develop. Malunions typically occur after the patient starts to walk altwhough a poorly executed osteotomy and fixation can certainly be the cause.
When a patient presents to the office with a failed bunion surgery, the most important elements of evaluation should include: what failed (loss of correction, malunion, shortening, stiff joint, etc.) and why? Certainly, the “why” is your best educated guess after examining the patient and looking at before and after X-rays. Often, we do not have the luxury of preoperative X-rays. Sometimes, I will take an X-ray of the contralateral foot to get an idea of what the normal anatomy looks like.
When I have to repair a sagittal plane malunion of the first metatarsal, my go-to procedure is usually the sagittal Z osteotomy. It affords correction in the sagittal plane where I can raise or lower the first metatarsal head. In addition, I can lengthen the bone at the same time if necessary. Rarely would I need to shorten the bone but I can do that if necessary.
If I need to fix the malunion in the transverse plane and alter length, I will consider a Mau/Ludloff oblique-type osteotomy. These osteotomies are not very stable and require immobilization but are very versatile. You can shorten, lengthen, translate and swivel. Not many osteotomies allow one to manipulate the bone in that many directions.
A challenging scenario involves patients who are happy with their bunionectomy but have developed lesser metatarsalgia. If the great toe joint is moving well, the patient is happy with the results and the joint is congruent, I find it difficult to address the first metatarsal surgically. I learned never to destroy normal anatomy but rather fix the abnormal anatomic segment. So the “textbook” answer would be to lengthen the first metatarsal versus shortening the second metatarsal.
My experience with lengthening the first metatarsal is that it is fraught with complications and leads to stiffening of the great toe joint. Therefore, I tend to shorten the “relatively long” second and third metatarsal (if necessary). Shortening lesser metatarsals leads to other problems such as floating toes due to the lack of flexor power. Certainly, we try to minimize this with postoperative splinting and physical therapy. I make it a priority to explain to patients that pain will resolve under the second metatarsal head but the toe may float. They need to be aware of that. The last thing that you want to hear from your patient after surgery is that, “You never told me ...” (see the sidebar “What To Include In Patient Consent Forms” at right).
For cases in which there is arthritis in the great toe joint, don’t forget about an arthrodesis for bunionectomy. A fusion can correct even large bunions and of all the different bunionectomy options out there, this is the one in which you can have the greatest confidence that the bunion will not come back. Just like any other fusion that we do, position means everything. With a properly positioned great toe, patients can run and wear most shoes without any limitations.
Bunion surgery will fail and we all have to address it, whether it is our own failure or due to someone else. Take the time to figure out why the bunion surgery failed and make an extra effort not to “reinvent the wheel,” but ensure that the same mistake does not happen twice. I personally do not think there is a perfect type of bunionectomy to perform but whatever you do and however you cut the bone, make sure the metatarsal head is repositioned over the sesamoids and that your joint is congruent. How do you know that the joint is congruent? The medial base of the proximal phalanx rests in the sagittal groove of the metatarsal head.
Dr. Fishco is board-certified in foot surgery and reconstructive rearfoot and ankle surgery by the American Board of Podiatric Surgery. He is in private practice in Phoenix. Dr. Fishco is also a faculty member of the Podiatry Institute.
Dr. Fishco pens a monthly blog for Podiatry Today. For more info, visit www.podiatrytoday.com/blogs/william-fishco-dpm-facfas .
1. Nix S, Smith M, Vicenzino B. Prevalence of hallux valgus in the general population: a systematic review and meta-analysis. J Foot Ankle Res. 2010 Sep 27;3:21.