Bunion deformities vary greatly with over 50 types of bunion surgery presented in the literature.1 Indeed, the list of procedures seems to be getting longer and more complicated. However, in my experience, I think there are a few key factors one needs to understand and master in order to treat any type and size of bunion. When discussing bunion deformity, the main considerations are primarily the intermetatarsal angle and hallux abductus angle. However, there are three other deformities we also need to consider.
The first is hallux angular deformity. This is the measure of the angle at the base of the proximal phalanx in comparison to the head of the proximal phalanx. This number should be parallel or zero. If there is a large angular relationship present, there is usually a lateral deviation of the head of the proximal phalanx, which will increase the visual bunion deformity, possibly necessitating an Akin procedure.
A second deformity is the relative sesamoid position. In my hands, I measure this in millimeters. When considering an osteotomy, if one cannot move the head of the metatarsal laterally far enough to correct the sesamoid position to zero (meaning the tibial sesamoid in comparison to the metatarsal head is zero), a head osteotomy may not be the ideal correction.
Finally, frontal plane correction is a relatively new idea. However, realignment of the sesamoid complex under the metatarsal head and proper alignment of the metatarsal head and crista position are important parts of good bunion correction.2
Upon physical examination, one must consider the level of deformity, both in the first metatarsal and in the proximal phalanx. The quality and position of the great toe joint and laxity of the first ray are also important. These are the main contributors to our assessment with the intermetatarsal angle and laxity of the first ray being of greatest importance.
Secondary factors may include tracking of the joint, crepitus and arthritic changes. One must also examine the quality of the surrounding skin, pedal pulses, neurological status and overall foot deformity, but this is beyond the discussion of this particular article.
Keys To Diagnostic Imaging For Bunion Deformities
The three most common radiographic views for bunion deformities are anterior-posterior, lateral and medial oblique. It is important to load the foot at the time of these radiographs in order to see the arch position and any elevation of the first ray. The intermetatarsal angle, sesamoid position and hallux abductus angle are all evident with standard radiographs. Additionally, a sesamoid axial view shows sesamoid position and frontal plane changes of the metatarsal head. A lateral radiograph with foot alignment corrected to a neutral heel position may reveal possible elevatus of the first ray, which may be detected on a standard lateral view.
3-D computed tomography (CT) of the foot may give a more detailed multiplane analysis of the bunion including degenerative changes of the metatarsocuneiform joint, metatarsophalangeal joint (MPJ) and sesamoid complex. Assessment of 3-D alignment issues and cystic changes are possible as well.
Magnetic resonance imaging (MRI) is fairly rare for bunions but one may obtain MRIs in cases of cystic changes and possible soft tissue laxity of the ray, especially with conditions such as rheumatoid arthritis, tophaceous gout and other systemic arthridities.
Procedure Choice: What The Surgeon Needs To Know
After collecting all of the examination and radiologic information, it is time to decide on the type of bunion surgery indicated for the patient. Over the course of 20 years, I have performed numerous different procedures including multiple head osteotomies, multiple base osteotomies, fusions of the MPJ and metatarsal-cuneiform joint, and the Lapidus procedure. I have found that I only need three procedures to treat any size or level of deformity without exception.
My mainstay procedure is the Lapidus bunionectomy. This may be due to the fact that I see more difficult or complicated bunion cases, or it may be that I am highly aware of the risk of recurrence related to bunion surgery and therefore prefer this fusion. However, I also have found that in cases of patients who are not a good candidate for a Lapidus procedure, have a relatively small deformity or have a stable first ray, a head osteotomy is also an excellent option. One should take caution to not assume an osteotomy is the only surgical option for patients because of the lack of ability to perform a Lapidus bunionectomy.
I have also found that a first MPJ fusion is a very powerful option for bunions that may be related to arthritis of the joint or a very severe bunion deformity, which may not do well with a Lapidus or an osteotomy. It is rare for me to perform an Akin osteotomy of the great toe unless there is a fairly severe lateral angular deformity in the proximal phalanx.
Which Osteotomy Should Surgeons Choose?
While there is a multitude of first metatarsal head osteotomies for bunion correction, I find base osteotomies do not allow for stabilization of the first metatarsal and are difficult with respect to correction of frontal plane and elevatus deformities. Therefore, I mainly use a head osteotomy for corrections without major deformity and without major laxity of the first ray.
My preferred technique is a minimally invasive osteotomy with screw and plate fixation. Currently, I utilize the miniBunion™ (CrossRoads Extremity Systems) because of the ease of use and limited incision of one centimeter or less. The through-and-through osteotomy allows for triplanar correction with lateral shift, frontal plane rotation of the metatarsal head and the ability to plantarflex the metatarsal head to correct elevatus. This is true three-dimensional realignment.
In rare cases of moderate arthritis of the metatarsal head, I will perform a traditional Austin bunionectomy through an extended incision in order to debride the arthritic changes in the joint. I currently find very limited need for an open osteotomy.
With the aforementioned miniBunion procedure, one makes a medial one cm incision at the proximal head of the first metatarsal. Then the surgeon performs an osteotomy and fits a plate into the metatarsal shaft, allowing lateral shift of the metatarsal head.
Fixation consists of a screw in the metatarsal shaft and a second screw in the metatarsal head. Each screw is associated with its own plate. The surgeon first places the proximal screw in the shaft and then rotates the metatarsal head to obtain triplane correction prior to placement of the metatarsal head screw. If there is a need for further intermetatarsal angle correction following head fixation, the surgeon can tighten the proximal screw in the shaft to shift the metatarsal head further laterally.
Assuming reasonable bone strength, there is immediate weightbearing with either of the distal head osteotomies I perform with transfer into a stiff athletic shoe at four to five weeks post-surgery. The patient can resume wearing regular shoes at six to eight weeks post-surgery. I prefer not to rush the patient into an athletic shoe too early as the patient often has pain with increased activity and sometimes has great toe stiffness during ambulation. However, I favor the minimally invasive bunion surgery because the joint is not opened or stripped. In my experience, bone healing is faster and range of motion is dramatically better.
What Would Make For An Ideal Lapidus Procedure?
The Lapidus bunionectomy is increasingly in the spotlight with the advent of the Lapiplasty® (Treace Medical Concepts) option. The Lapiplasty procedure offers ease of surgical planning and implementation with specifically-designed guides and jigs. This may appeal to surgeons who did not previously perform the Lapidus procedure. The Lapiplasty procedure is also considered an improved procedure due to three-dimensional correction of the first metatarsal.
I appreciate the Lapiplasty option but having over 20 years of experience with the Lapidus procedure, I believe most surgeons correct the first metatarsal in three dimensions already. I perform my Lapidus bunionectomy through a two-incision approach with the proximal incision dorsal over the first metatarsocuneiform joint. I debride the joint to subchondral bone and then fenestrate and shingle the area. One would perform deformity correction through a lateral shift of the metatarsal with frontal plane rotation and plantarflexion as necessary. I rarely have to but surgeons do have the ability to remove a small lateral wedge at the base as necessary for very large deformities.
I helped design a staple and plate system (Dynaforce Lapidus Implant System, CrossRoads Extremity Systems), which utilizes a dorsal staple and medial “Z” plate with internal staple and screw fixation of the plate. I prefer this method because the Nitinol staples allow for constant compression that is not possible with pure plate fixation. If there is hypermobility of the intercuneiform joint following the primary dorsal staple placement, one can cross the screw in the medial cuneiform and first metatarsal screws into the second cuneiform and second metatarsal base. In my experience, this is superior fixation for very hypermobile first rays.
I will open the great toe joint only after I correct and stabilize the metatarsocuneiform joint. At that point, if there is still a medial eminence to remove or if there needs to be better alignment of the toe, I perform a medial incision, remove the eminence and perform an internal-based lateral release and lateral collateral ligament release with medial capsular imbrication. In rare cases of very severe deformity of the great toe with a trackbound joint, I will open the first MPJ and perform a lateral capsular and ligamentous release prior to fixation of the first metatarsocuneiform joint in order to get better correction and alignment of the first ray.
Now I also often utilize a bone marrow aspirate concentrate from the heel in Lapidus procedures and first MPJ fusions. I have found my rate of nonunion to be very low as a result. I am sure the improved fixation has something to do with the improved rate of nonunion but
I truly believe my fusions heal faster and with less complications due to the addition of the bone aspirate concentrate.
For the first postoperative week, I prefer patients to be either non-weightbearing or have only limited weightbearing in order to allow the soft tissue to settle, and to limit edema and pain.
Following a one week cast change and dressing change, I allow weightbearing as tolerated by the patient. I emphasize to patients to not bear weight more than necessary in order to limit edema and that they should not use pain medication to allow more weightbearing. Their body is attempting to tell them to slow down and limit activity.
I place my Lapidus and first MPJ fusion patients into an athletic shoe as early as four weeks post-surgery, but more commonly at five to six weeks post-surgery. I will often order a CT scan at the five-week point to make sure the fusion is solidly progressing prior to this shoe gear change. In my experience, the CT scan can show delayed healing, even if the radiographs suggest good apposition and healing progression. In these cases, we have the patient slow down a bit longer and until eight to 10 weeks post-op to allow further bony consolidation.
There are many ways to treat a bunion deformity. What works for one does not have to work for all. Nonetheless, I believe that a solid distal osteotomy, first MPJ fusion and Lapidus bunionectomy are ideal options in the treatment of any size bunion deformity. Fixation options and systems differ. The surgeon needs to choose the system that works best for him or her. Finally, augmentation with bone aspirate concentrates improves fusion rates in my hands and solid internal fixation allows most, if not all, bunion surgery patients to bear weight at a very early stage with minimal complications and rapid healing.
Dr. Baravarian is an Assistant Clinical Professor at the UCLA School of Medicine. He is the Director and Fellowship Director at the University Foot and Ankle Institute in Los Angeles (https://www.footankleinstitute.com/podiatrist/dr-bob-baravarian ).
Dr. Baravarian has disclosed that he is a consultant for CrossRoads Extremity Systems and OSSIO.
1. Baravarian B. Hallux valgus and bunion surgery. Clin Podiatr Med Surg. 2014;31(2):xiii-xiv.
2. Dayton P, Cifaldi A, Egdorf R. Why frontal plane correction is a vital component of bunion surgery. Podiatry Today. 2017;30(7):28-34.