Bunions: Are Proximal Osteotomies Necessary?

Author(s): 
By John McCord, DPM, and Mark Hofbauer, DPM

Yes, if the procedure is done correctly, it is a valuable adjunct to bunion correction, says John McCord, DPM. Who will ever forget the memorable autistic man played by Dustin Hoffman in the film Rain Man? My favorite scene was when he refused to fly on any airline but Quantas because that carrier had no history of accidents. I reflect on that scene when I talk with colleagues in podiatry who refuse to consider performing proximal osteotomies while correcting bunion deformities. Their logic makes as much sense as the Rain Man in that they will choose a head osteotomy even though it won’t correct the deformity. Proximal osteotomies were the gold standard in podiatry until metatarsal head osteotomies became popular in the mid-‘70s. Mostly, we performed transverse closing wedge procedures to correct high IM angles. We secured these with stainless steel wire and, in most cases, they worked well. Then the hinge/axis concept was introduced and it helped to prevent elevatus of the first metatarsal. Screw fixation was also introduced and this required an oblique Juvara osteotomy. Why Distal Osteotomies Aren’t The Answer With Severe IM Angles Metatarsal head or distal osteotomies were easy to perform and became the favored procedures. You could think two dimension and achieve a relative correction of a high IM angle without much danger of a surgical complication. Proximal osteotomies demand that you think three dimensions and work with templates preoperatively. A poorly executed proximal osteotomy could result in severe elevatus of the first metatarsal and subsequent hallux limitus. A poorly executed head osteotomy just kind of takes care of itself in time. The problem with distal osteotomies is that they don’t really correct the deformity. They are okay when the IM angle isn’t severe but anything over 16 degrees will fail unless you correct the deformity at its source, the proximal aspect of the first metatarsal. There have been variations of the metatarsal head osteotomies with long legs that stretch back to the proximal shaft. If the deformity approaches 18 degrees, these are unstable because of troughing. The solution is that we should all be capable of performing proximal first metatarsal head osteotomies or willing to refer cases with high IM angles to colleagues who can do the job right. I don’t look forward to the patients who come in with high IM angles. These patients tend to be young people who have had juvenile hallux abducto valgus. The best solution is to select a procedure which corrects the hallux valgus plus an appropriate osteotomy to correct the metatarsus primus varus. In these cases, I go by the patient’s apparent needs rather than my limitations or desire for an easy trouble free operation. It is best to correct the deformity and its underlying cause so the patient doesn’t have to face a series of operations. I went for a long period of time in the ‘80s in which I avoided performing the dreaded closing wedged osteotomy. I had created a few elevated metatarsals and had encountered a few non-compliant patients who liked to bear weight before things had healed. I reasoned that it was better to err on the side of caution and risk a recurrence than to do what was needed at a higher risk. Then I looked back at 10 years of my easy metatarsal head osteotomies and was appalled at the numbers of recurrence and unsatisfactory results. The worst results occurred with patients who had IM angles of around 18 degrees. Revisiting The Proximal Osteotomy And Emphasizing Compliance I revisited the proximal osteotomy and took a few internal fixation courses. I made templates by tracing X-rays, AP and lateral views. I now do this with a digital camera which is much easier. I bring the templates into surgery with me. My OR looks like a third-grade art project sometimes with templates hanging everywhere. I take my time getting to know the patients. If any seem like they will be a compliance problem, I counsel them into waiting to have the procedure done. Most are better off being left alone than undergoing surgery, walking too early and winding up crippled. If the patient is compliant, has a bunion with a high IM angle and is in good health, I talk to him or her about a proximal osteotomy as an option. I talk about the risk factors and prepare the patient for at least three months on crutches. I talk about the consequences of non-compliance and show pictures of patients who have walked too early and developed complications. I emphasize that it is better to not have the operation if they’re not going to be able to maintain post-op compliance. Some go away for a few years until they mature or their lives are more stable. Key Considerations For Ensuring Treatment Success The hinge/axis concept is a simple one. You would make the osteotomy so the axis of rotation is perpendicular to the supporting surface rather than the metatarsal shaft. You would proceed to drill the pilot hole perpendicular to the supporting surface. When you have closed the osteotomy, the metatarsal head moves in a lateral direction, correcting the high IM angle. (If the axis of the osteotomy is perpendicular to the metatarsal shaft, the head moves up when it is closed. This causes first metatarsal elevatus, which quickly leads to hallux limitus, a situation in which the patient would have been better off without any surgery.) I use the oblique (Juvara) procedure and secure the osteotomy with two cortical screws and a longitudinal K-wire, which helps to maintain the first toe correction. You can remove the K-wire after about three weeks. I keep the patient off-weightbearing until there is evidence of healing of the osteotomy. This takes two to three months in a healthy young adult. Be aware that the osteotomy may never heal in an elderly patient with osteoporosis. Overweight patients are at high risk for failure. I discuss weight loss in these cases. No matter how careful you are about placing the osteotomy, mistakes can happen. If I notice that I have created a metatarsal elevatus on intraoperative X-rays, I break through the medial cortical hinge and angle the distal segment down into a correct position. It is a lot easier to do that and explain it to patients than to tell them they will need another operation as soon as the first heals. When I have to break the hinge, I always opt for three point fixation. It’s important to consider the proximal articular set angle when you’re selecting a proximal osteotomy. If it is over 7 degrees, you must correct it, usually by performing a head osteotomy. You can do this in conjunction with a base osteotomy if there is adequate length. If there isn’t adequate length, the crescentic osteotomy is an option. I’ve never cared much for crescentic osteotomies because they are difficult to stabilize. Why You Should Be Wary Of Diaphyseal Osteotomies Mid-first metatarsal shaft or diaphyseal osteotomies may have a place in the sun, but I’m not sure where. These are popular with the so-called minimally invasive foot surgeons. You would use a bone drill to cut through the metatarsal, mid-shaft. The osteotomy or bone cut is not fixated. The distal half of the first metatarsal is simply left to “float.” The patient gets back into his or her shoes and walks out. These osteotomies are secured with really good bandages while the distal segment signals for a left turn, then a right turn and so on until it heals or doesn’t heal. I’ve repaired a few of these and it isn’t fun. The patient usually responded to an ad which touts the ease of minimally invasive foot surgery. Some turn out okay but there are too many complications, so I prefer more traditional techniques for correcting high IM angles. Final Notes I have a series of young patients, mostly males with juvenile hallux valgus deformities, who have enjoyed excellent results after proximal first metatarsal osteotomies. This procedure is a valuable adjunct to correction of bunion deformities. Learn to do them right if you’re going to try them or refer them to an experienced colleague. Don’t try to fly Quantas from Ohio to L.A. Dr. McCord is a Diplomate with the American Board of Podiatric Surgery. He practices at the Centralia Medical Center in Centralia, Wash. No, Mark Hofbauer, DPM, believes the metatarsal cuneiform joint fusion better addresses mechanical dilemmas and has proven long-term results. Controversy abounds concerning procedure selection for hallux abducto valgus deformity even today amid the ever-growing literature on the deformity and its treatment. Invariably, new procedures tend to come and go because of the surgeon’s desire to try something new and less so because of proven results over a long period of time. Unfortunately, inappropriate procedure selection tends to be the most important factor in recurrent hallux abducto valgus deformity among patients who return to the office five years after the original procedure. By reviewing the mechanics of hallux abducto valgus (see “Addressing The Altered Mechanics Of Hallux Abducto Valgus Deformity” on page 46) and long-term results (and potential complications) of procedures, we can better understand appropriate procedure selection. The purpose of this article is not to argue that the closing base wedge osteotomy is a bad procedure. Rather, it is my viewpoint that there is a better way to address this deformity in most patients. Too often, procedures are selected based on surgeon comfort level, rather than which procedures would provide the best long-term result for the patient. Too often, I find myself at a conference where someone will say, “I do base wedge osteotomies and they all do great.” To me, what this usually means is that once the patient has completed his non-weightbearing course, is back in a shoe and there is radiographic evidence that the osteotomy has healed, the patient was then discharged and was considered a great result. However, it takes five years to evaluate whether these types of patients have good long-term results. I base this statement on years and years of retrospective studies looking at effective procedure selection based on a five-year follow-up. After 13 years of performing all types of hallux abducto valgus repair and analyzing data of each procedure type, I have come to some conclusions concerning procedure selection. The patient’s foot type and mechanics are the two primary factors you should consider when choosing a procedure. Don’t consider your comfort level or the patient’s desire to remain weightbearing when selecting a procedure. In choosing the correct procedure, podiatric surgeons have placed a high level of importance on radiographic findings, which include intermetatarsal angle, metatarsus primus elevatus, metaductius, long or short first metatarsal, PASA or DASA hallux abductus angle and others. what they find radiographically. However, I believe radiographic findings (including intermetatarsal angles) are much less important than clinical findings or mechanics. Breaking It Down To Degrees Of Deformity And Hypermobility What I have found is that patients usually fall into one of the following categories and you can choose the appropriate procedure based on these categories. Category one: the patient with hallux abducto valgus deformity with any degree of hypermobility. This tends to be the most common type of hallux abducto valgus deformity we see in our office on a daily basis. The most optimal procedure for this patient is the first metatarsal cuneiform joint fusion. Regardless of the intermetatarsal angle, if you don’t address the hypermobility in these patients, the risk of long-term recurrence is a significant possibility. Recent studies have shown theoretically that any reduction in the intermetatarsal angle will decrease the hypermobility of the first ray. However, I have not found this to be true clinically in all people. All too often, surgeons will perform a head osteotomy or base wedge osteotomy for these patients. If the procedure is performed properly, short-term results always look great. However, a number of these patients develop recurrence and require a second special procedure that now becomes much more difficult. This scenario of recurrent hallux abducto valgus deformity is most common among younger patients. This recurrence is usually the result of using a less aggressive procedure despite presenting hypermobility. Category two: the patient who has a mild hallux abducto valgus deformity with no hypermobility. A head-type osteotomy would be an excellent procedure selection for these patients. Hypermobility is not a factor and you can ensure sufficient correction of the intermetatarsal angle. Category three: the patient who presents with a moderate hallux abducto valgus deformity with a wide first metatarsal and no hypermobility. This tends to be a less common type of presentation, which you can address adequately with a simple head osteotomy that allows for intermetatarsal correction. Since hypermobility is not a factor with these patients, you’ll find that recurrence following a head osteotomy is minimal. Category four: the patient who presents with a moderate to severe hallux abducto valgus deformity and no hypermobility. This type of patient presentation does lend itself to a closing base wedge osteotomy. Likewise, you can address this type of foot deformity with less risk of complication by utilizing the metatarsal cuneiform joint fusion. However, this type of foot is rarely seen. I’m sure many will question this statement. However, upon evaluating patients who have developed recurrent hallux abducto valgus deformity five years after the initial procedure — even those patients who have had a perfect intermetatarsal correction with a base wedge osteotomy — it is obvious some type of hypermobility or instability component was missed and that led to the deformity recurrence. What About Complications With The Closing Base Wedge Osteotomy? Indeed, this category of patients requires much discussion on the subject of appropriate procedure selection. For example, should we consider a metatarsal cuneiform joint fusion over a closing base wedge osteotomy for these patients? Closing base wedge osteotomy performed with either K-wires or screws or the combination of both tends to have the highest complication rate of any bunion procedure described in the literature over the years. These complications include breaking of the cortical hinge at the apex of the osteotomy. Regardless of fixation, this tends to be a common occurrence. When the cortical hinge is broken in this type of procedure, complications, including shorting elevatus and delayed union, are commonplace. There have been reports of long-term morbidity and less than optimal patient satisfaction, and many cases have required complete reconstruction of this area utilizing bone grafts. Even those patients who progress with a normal course and have radiographic evidence of healing at the base wedge osteotomy site will at times go on to metatarsus primus elevatus. The (sequella) of this problem includes first MPJ stiffness as well as lesser metatarsalgia. Many will argue the use of two screws will prevent this metatarsus elevatus from happening. However, the mechanics associated with the weightbearing forces, with regard to the placement of this osteotomy, lead to this complication as well as viscoelastic changes of the metatarsal and metatarsal elevatus in the long term. Key Benefits Of Employing Metatarsal Cuneiform Joint Fusion Many will argue that you can completely close the intermetatarsal angle with the closing base wedge osteotomy and obtain plantarflexion of the first ray as well. While I do agree that you can achieve both with a closing base wedge osteotomy, exact precision of placing the metatarsal where it needs to be is much more difficult when compared to doing the same maneuver with the metatarsal cuneiform joint fusion. It is impossible with a closing base wedge osteotomy to rotate the first ray out of varus or valgus and allow for rectus alignment of the christa and the metatarsal head. Likewise, you can achieve a plantarflexed position much more adequately with the metatarsal cuneiform joint fusion than the closing base wedge osteotomy. Another factor to consider is the positioning of the sesamoid underneath the first metatarsal head with plantarflexion of the metatarsal obtained with an osteotomy versus plantarflexion of the entire ray at the metatarsal cuneiform joint with first metatarsal phalangeal fusion. Long-term radiographic evidence in patients with metatarsal cuneiform joint fusion identify the sesamoid apparatus in a more anatomical location as opposed to patients who underwent the closing base wedge osteotomy and had a plantarflexed first metatarsal in which the sesamoid apparatus is displaced anteriorly. For this reason, tibial sesamoiditis is much more common in patients who underwent the closing base wedge osteotomy. Addressing Non-Union Rates Of The Lapidus Procedure Opponents of the Lapidus procedure have argued for years that non-union is a major factor associated with the procedure that is not a concern with the closing base wedge osteotomy. Upon considerable review of literature, you will find the rate of non-union in metatarsal cuneiform joint fusion is anywhere from 7 to 12 percent and the majority of these are radiographic non-union as opposed to clinical non-union. Less than 2 to 4 percent of the patients who present with a radiographic non-union have clinical symptoms and require a second procedure. Therefore, it is apparent, even in a category four patient who would do well with a closing base wedge osteotomy, the increased risk of complication and inability to place the metatarsal exactly where you would desire further supports using the metatarsal cuneiform joint fusion over a closing base wedge osteotomy. Final Thoughts As we continue to learn more about the mechanics of hallux abducto valgus deformity and the long-term results of the procedures we perform, the goal obviously should be to strive for the procedure most likely to provide the best long-term outcome for the patient. After evaluating foot types and mechanics, it appears to me the closing base wedge osteotomy has very limited application. It is also clear that you can treat category four patients with the metatarsal cuneiform joint fusion and have less risk of complications. For those who don’t want to believe recurrence happens to them or that complications are not that common, always remember the literature does not lie. Patients with recurrent hallux abducto valgus deformity usually end up in someone else’s office seeking a different solution for their new problems. Dr. Hofbauer is a Diplomate of the American Board of Podiatric Surgery and a Fellow of the American College of Foot and Ankle Surgeons. He is on the staff of the Foot And Ankle Institute of Western Pennsylvania and has a private practice in McMurray, Pa.

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