The bunion deformity is one of the most common deformities that podiatric foot and ankle surgeons treat. As with other conditions, the conservative and surgical measures vary based on the patient’s expectations and the surgeon’s experience. Although there are limited conservative options available such as shoe modifications and prescription orthoses, most podiatric physicians would agree that surgical correction is often necessary for a symptomatic bunion deformity. While there are several considerations in choosing the appropriate surgical procedure, one should ultimately focus on achieving the greatest correction for the longest period of time. Although numerous types of procedures are at the surgeon’s disposal, factors such as patient compliance, health and occupation can all influence how one corrects the deformity. In addition, the more severe the deformity is, the greater the challenge of correction. Accordingly, let us review some key points on preoperative evaluation and surgical intervention for severe hallux valgus deformities. Multiple articles and texts have addressed the causes of bunion deformities. Over the past century, there seems to have been a shift from a focus on external causes such as shoe gear and activities to more intrinsic factors such as genetics and biomechanics of the lower extremity. In my training, I once heard that to be a good surgeon, one must also have a strong knowledge of biomechanics. In a sense, this is very true. Failure to address concurrent or contributing factors can doom a well-executed surgical intervention. Specific examples include metatarsus adductus, first ray hypermobility and a flexible pes planus deformity. Any of these conditions and numerous others may require more intervention than simply correcting the first ray and associated soft tissue structures. Accordingly, one should never underestimate biomechanics associated with bunion deformities. Ankle, subtalar, midtarsal and first ray range of motion directly affect the outcome of this type of surgery. In severe cases, ankle equinus may require concurrent correction via a gastroc recession or Achilles tendon lengthening. One may need to address abnormal pronation with an orthotic or possibly correct it with a separate surgery. In cases like these, the most difficult task is not the procedure itself but attempting to explain to the patient how the biomechanical issues directly affect the outcome of the bunion surgery and why the ancillary procedure(s) is necessary.
Essential Diagnostic Pointers
Clinicians typically take radiographs with patients standing in their normal angle and base of gait. In many cases, the patient may alter his or stance due to pain from the bunion itself or pain from other causes such as subluxation of the second metatarsophalangeal joint. Be aware that even a slight adjustment on the part of the patient can alter the structural alignment on the radiograph. The anterior-posterior (AP) view enables the podiatric surgeon to evaluate the intermetatarsal angle, which is increased in cases of severe hallux valgus. When measuring this angle, one should also assess any concurrent metatarsus adductus. Adductus will clinically increase the intermetatarsal angle and can affect the procedure(s) required. The AP view also shows the position of the tibial sesamoid. The larger the deformity is, the greater lateral displacement of this sesamoid. In cases of a severe deformity, a lateral release may be insufficient and complete removal of the sesamoid may be required. The sesamoid-metatarsal complex may also be arthritic and surgical anatomic realignment may be impossible. This can also require sesamoid removal. Surgeons should also assess the length of the first metatarsal. It should be within 1 to 2 mm of the length of the second metatarsal. Based on this measurement, if one anticipates excess shortening, address it peri-operatively. Grafting may be necessary in a metatarsocuneiform arthrodesis or one may prefer an opening wedge osteotomy over a closing wedge. The AP view also allows the surgeon to assess deformity within the proximal phalanx, which may require an osteotomy as well. This view also enables surgeons to see arthrosis of the first metatarsophalangeal joint and/or severe articular deviation. The lateral radiograph can provide evidence of first ray elevation. The dorsal cortex of the first metatarsal should be parallel with that of the second metatarsal. One may see dorsal spurring. This ectopic bone can be present at the first metatarsophalangeal joint or metatarsocuneiform joint. This sign in either joint strongly suggests instability of the first ray. Clinically, one may see hyperkeratotic tissue beneath the second metatarsal. This indicates a maldistribution of pressure. In protracted cases, subluxation of the lesser metatarsophalangeal joint(s) is often present. The sesamoid axial view will show arthrosis within the joint complex and also allows the surgeon to see any erosion of the anatomic grooves on the plantar aspect of the metatarsal head. It can also provide evidence of fusion of the two sesamoids and deviation of the sesamoid complex. Remember that even though we refer to the movement of the sesamoids as “lateral,” it is really a rotation about the metatarsal head. This article cannot fully cover all of the well documented radiographic angles associated with hallux valgus deformity. While these angular limits do not provide absolute rules for what procedure to choose, they can serve as a guide. The proximal articular set angle is a controversial area within our specialty. Personally, I have found the articular surface is rarely severe enough to warrant specific surgical correction.
Key Considerations In Selecting A Procedure
There are numerous surgical options when it comes to reconstruction of the severe bunion deformity. In my opinion, all of the procedures mentioned below can address a large hallux valgus deformity. However, it is important to have a frank discussion with the patient about the postoperative course and expectations following surgery. A first metatarsocuneiform arthrodesis may simply not be an option in everyone who radiographically requires it. The same thing can be said about a base wedge osteotomy. Partial correction with relief of pain can be an acceptable outcome if the patient understands the realistic goals of the surgery and the postoperative course is more manageable. It can never be overstated that any of the procedures listed below may require concurrent correction of deformity. An example of this would be inadequate correction due to the failure to address significant metatarsus adductus. In this type of foot, a large bunion may be present but the intermetatarsal angle is not large enough to allow significant lateral movement of the distal aspect of the first metatarsal. Another example would be recurrence of the deformity due to a flexible pes planus foot type. This especially seems to be the case in juvenile patients.
Assessing The Merits Of Common Osteotomies
Surgical experience also plays a large role in which procedures one can successfully perform. In my hands, I seem to have had greater success with base osteotomies as opposed to proximal arthrodesis. This is not to say one is necessarily better than the other. One can make numerous arguments for any type of surgical procedure and the goal is simply a positive outcome for both the surgeon and the patient. Distal osteotomies. These procedures can still play a large role in correcting severe hallux valgus. Although many surgeons would argue to the contrary, it is my opinion that a well executed and fixated Austin procedure can provide a great deal of correction. This is especially the case if the surgeon feels a fibular sesamoidectomy is warranted. Shifting the apex of the osteotomy slightly in a more proximal direction can achieve increased lateral translation. In certain patients, performing an additional Akin (phalangeal) osteotomy can achieve even greater correction. Again it is incumbent on the surgeon to assess the expectations of the patient. An easier postoperative period with relief of pain may be acceptable even with the clinical appearance of residual hallux deviation. Midshaft osteotomies. Midshaft osteotomies, such as the classic Scarf and modifications thereof, can allow even more lateral translation of the capital fragment. The surgeon may typically allow weightbearing assuming he or she has achieved adequate fixation of the osteotomy. Some increased scar formation can result with excessive dissection but this is usually not problematic. I have also experienced troughing with this type of procedure but, in retrospect, this was most likely a result of my surgical technique as opposed to inherent weaknesses of the procedure. Slight alterations in the osteotomy quickly alleviate this problem. Proximal osteotomies. Closing or opening base wedge osteotomies allow a very large correction of the intermetatarsal angle. The most common complications I have found with this procedure include non-union, loss of fixation/correction and iatrogenic elevatus. One may also encounter overcorrection with this procedure. It is always better to remove a small wedge and reciprocally plane the osteotomy until achieving correction. Remember that fixation will compress the site even further so take this into account when planning the procedure. In an opening wedge osteotomy, grafting may be necessary but I have been able to employ an alternative that seems to work well. The wedge is medially based but the opposite side is still somewhat wide. It is more of a trapezoid shape. When removing this entire wedge, one can simply flip it over and automatically place the first metatarsal into a rectus position. Of course, with this type of procedure, one does lose the small amount of structural stability provided by leaving the cortical hinge intact but this seems to be negligible. Strict non-weightbearing is a necessity so the patient must understand about the need for compliance. Due to the position of the osteotomy at the base, the lever arm is very long and weightbearing can easily result in frank displacement or gradual deformation of the bone cut. Gradual deformation is a subtle complication that can decrease range of motion of the joint and accelerate the onset of arthrosis. In my patients who are using even partial, protected weightbearing, I employ a first ray cutout to further offload the area.
A Closer Look At Arthrodesis Techniques
Arthrodesis techniques have experienced a resurgence of popularity among podiatric surgeons over the last two decades. The first metatarsal cuneiform arthrodesis can address hypermobility of the first ray. It can also provide more options in fixation than the base wedge procedures, which can provide a more aggressive postoperative course. In some cases, I have allowed almost immediate (protected) weightbearing due to patient compliance and security of fixation. It is possible to achieve a great deal of correction with this procedure but keep in mind there are increased risks of complications and technical difficulty as well. First metatarsophalangeal joint arthrodesis can be an invaluable weapon in the podiatric surgical armamentarium. In cases of severe arthrosis, an arthrodesis can yield improved appearance and also relieve pain. Even in cases of a very significant deformity without severe arthrosis, performing an arthrodesis of the great toe can yield excellent surgical results. One would consider this procedure in patients with soft tissue contractures (including the skin structures) and altered range of motion of the hallux. In this type of clinical scenario, the arthrodesis can be the most predictable procedure. A postoperative loss of range of motion is not usually an issue with these patients because arthrosis or subluxation of the first MPJ has already restricted motion significantly. Even though one can obtain much correction, a more proximal procedure may still be necessary for complete realignment. Implant arthroplasty is still a viable option in many surgeons’ hands. These procedures can also provide significant relief of pain for appropriately selected patients. As with any surgical procedure, certain complications can be inherent with this form of correction. A more proximal procedure may still be required to achieve full correction.
Surgical intervention for a severe hallux valgus deformity can be a difficult but very rewarding task for the podiatric foot and ankle surgeon. Ensuring appropriate clinical and radiographic examination, and realistic patient expectations can significantly enhance surgical outcomes. Relieving pain and providing realignment are the two greatest goals in achieving correction of severe bunion deformities. Dr. Burks is a Fellow of the American College of Foot and Ankle Surgeons and is board certified in foot and ankle surgery. Dr. Burks practices in Little Rock, Ark. Editor’s note: For related articles, check out www.podiatrytoday.com.
CE Exam #133 Choose the single best response to each question listed below. 1. Which of the following directly affects bunion surgery outcomes? a) Subtalar range of motion b) First ray range of motion c) Ankle range of motion d) All of the above 2. Which of the following statements is false? a) When measuring the intermetatarsal angle on the anterior-posterior (AP) view, one should also assess any concurrent metatarsaus adductus. b) The intermetatarsal angle is of no consideration in surgical planning for severe hallux valgus. c) Metatarsus adductus may negatively impact the clinical appearance of the bunion deformity. d) None of the above 3. Which of the following statements is true? a) The larger the bunion deformity, there will be a greater lateral displacement of the tibial sesamoid. b) In cases of severe bunion deformity, a lateral release of the tibial sesamoid is sufficient. c) Complete removal of the tibial sesamoid is never required in cases of severe bunion deformities. d) All of the above 4. The sesamoid axial view of a large bunion deformity can show … a) Any erosion of the anatomic grooves on the plantar aspect of the metatarsal head. b) Arthrosis within the joint complex. c) Evidence of fusion of the two sesamoids and deviation of the sesamoid complex. d) All of the above 5. In regard to distal osteotomies, the author says … a) These procedures are rarely used in cases of severe hallux valgus. b) Shifting the apex of the osteotomy slightly more proximally decreases lateral translation. c) A well-executed and fixated Austin procedure can provide a great deal of correction in cases of severe hallux valgus, especially if a fibular sesamoidectomy is warranted. d) None of the above 6. In regard to midshaft osteotomies … a) They allow less lateral translation of the capital fragment than distal osteotomies. b) They have more successful outcomes when surgeons emphasize strict non-weightbearing for one month post-op. c) One may see increased scar formation with excessive dissection but this is usually not problematic. d) None of the above 7. Which of the following is a common complication of proximal osteotomies? a) Non-union b) Loss of fixation/correction c) Iatrogenic elevatus d) All of the above 8. The first metatarsal cuneiform arthrodesis … a) Provides more options in fixation than the base wedge procedures. b) Doesn't address first ray hypermobility. c) Can facilitate a great deal of correction but has an increased risk of complications and technical difficulty. d) A and C e) None of the above 9. An arthrodesis of the great toe … a) Should be reserved only for cases of severe arthrosis. b) May be indicated for patients with soft tissue contractures (including skin structures) and altered range of the hallux. c) Can provide an improved appearance but has minimal impact in relieving pain. d) None of the above Instructions for Submitting Exams Fill out the enclosed card that appears on the following page or fax the form to NACCME at (610) 560-0502. Within 60 days, you will be advised that you have passed or failed the exam. A score of 70 percent or above will comprise a passing grade. A certificate will be awarded to participants who successfully complete the exam. Responses will be accepted up to 12 months from the publication date.