Current Concepts In Treating Hallux Valgus
In the search to find the perfect osteotomy for treating hallux valgus, podiatrists have developed an extensive surgical armamentarium, which includes modifications, as well as modifications of modifications of procedures, to the point where it has become dizzying. Ultimately, our experiences have led most of us to succumb to the fact that “one size does not fit all” when dealing with this common malady and no osteotomy is completely infallible. We all have our favorites and naturally tend to employ those procedures that we are most comfortable using. Debates and arguments concerning which is the superior osteotomy have been passionate and relentless. Yet what surgeons do agree upon is that a procedure is most effective when proper indications are considered to correct the level of deformity. There are several issues to consider when one evaluates the available options. Generally, what make a surgical procedure attractive are its reliability, stability, reproducibility, technical ease and adjustability. A reliable osteotomy is one that is consistently effective. A stable osteotomy is one that resists displacement and is conducive to rigid fixation. A reproducible osteotomy is one that produces consistently good results with the least amount of complications. A technically simple and adjustable osteotomy is one that has a low learning curve and allows easy intraoperative adjustment without the need for additional wedging or bone cuts. With that said, I believe the crescentic shelf osteotomy (CSO) and the proximal phalangeal osteotomy (OPPO) maintain these attributes, making them very desirable techniques to consider in the correction of hallux valgus. What Advantages Does The CSO Offer? In the early ‘90s, base wedge osteotomies constituted the majority of proximal procedures performed by podiatrists to correct moderate to severe hallux valgus. However, the drawbacks of the procedure became evident and included shortening, elevatus, over/under correction and loss of stability with fracture of the medial hinge. Despite these drawbacks, the base wedge osteotomy remains the principal technique for correcting moderate to severe hallux valgus in the podiatry community. On the other hand, the orthopedic gold standard included and perhaps still includes the crescentic (or the “dial in”) osteotomy. The technique provided a powerful tool to correct wide intermetatarsal angles with minimal shortening. One could also adjust the procedure in order to obtain exact correction without additional wedging and facilitate triplanar correction by angling the osteotomy in various directions. Nevertheless, the crescentic osteotomy was not without its own well-documented skeletons. They included sagittal instability and postoperative elevatus, likely due to poor osteotomy placement and difficulty in fixation. The CSO was developed in an effort to avoid some of the complications encountered with current proximal osteotomies. It emphasizes the advantages of the generic crescentic osteotomy and eliminates its shortcomings. The CSO converts the crescentic osteotomy into a very stable and reproducible construct by simply combining a dorsal to plantar crescentic osteotomy directed at a 90-degree angle to a medial to lateral transverse osteotomy at the base of the metatarsal. The latter provides a thick cortical shelf for seating of the cylindrical bone. By doing so, the CSO maintains length, allows precise intermetatarsal correction, allows triplanar correction, resists dorsal displacement, is easily fixated with screws, wires or a combination, and is technically less demanding. While over a decade has passed since its inception, the CSO continues to be a reliable technique. It has not only become accepted in podiatry circles, but also appears to be gaining steam in the orthopedic world where it has been presented nationally and internationally by orthopedic surgeons. How To Perform the CSO When considering the CSO, one can usually achieve adequate exposure with a dorsal medial approach. Perform distal soft tissue procedures with appropriate releases. The base of the metatarsal should be exposed and one should be able to identify the metatarsal cuneiform joint. Retract the long extensor tendon laterally. Employing a baby Homan retractor may be useful in retracting the dorsal flap. Surgeons will now have exposure of the proximal medial ridge as well as the lateral aspect of the metatarsal. Proceed to drive a 0.062-inch Kirschner guide wire transversely from medial to lateral at the level of the medial ridge, approximately 1 cm distal to the metatarsal cuneiform joint (MCJ). This should represent the apex of the two osteotomies. In order to provide pure transverse plane rotation, aim the wire directly at the second metatarsal. Direct it slightly plantar if plantarflexion is desired. Also keep in mind that the guide wire should be parallel to the MCJ when looking at it from an AP perspective. Remember, the CSO is a rotational osteotomy and not a translational osteotomy. Using a straight sagittal blade, make a plantar cut from medial to lateral, forming the plantar cortical shelf. Position the saw blade parallel to the guide wire axis and carry it distally until it exits through the plantar cortex. The bone cut creates the platform for the seating of the crescentic osteotomy. Disconnect the sagittal blade from the hand piece and leave it inside the osteotomy. This is necessary to protect the shelf from the crescentic cut and provides an additional landmark to ensure a 90-degree osteotomy. Using the oscillating saw with a crescentic blade, perform the crescentic bone cut dorsal to plantar and perpendicular to the shelf. One should gently rotate the crescentic blade clockwise and counterclockwise until it reaches the sagittal blade at the apex of the osteotomy. The male portion of the osteotomy (or the base of the distal metatarsal fragment) will appear cylindrical. Rotate the male portion laterally within the female counterpart to correct the intermetatarsal angle. Then clamp or temporarily fixate the osteotomy with a K-wire by anchoring it into the cortical shelf. Obtain fluoroscopic views in order to ensure proper reduction. One may tweak the correction angle until there is complete satisfaction with the alignment. Taking advantage of the thick cortical shelf, one can achieve stable permanent fixation by directing small or mini-fragment screws (or a combination thereof) obliquely into the plantar lateral tubercle, parallel from dorsal to plantar or by using a combination of the two by employing one oblique and one dorsal to plantar screw. Two screws are advised in order to prevent rotation. Crossed K-wires have also been used with excellent results, particularly if the patient is compliant. Postoperative care for the proximal CSO is consistent with other basilar osteotomies. This involves immobilization in a short leg, non-weightbearing cast for four to six weeks pending radiographic union. This is followed by two to four weeks of progressive weightbearing with a CAM walker. What You Should Know About The OPPO Interestingly, despite its drawbacks, the Akin phalangeal osteotomy is a procedure that has evaded any challengers since its inception 79 years ago. The technique and its modifications consist of a transverse or obliquely oriented, medially-based wedge resectional osteotomy that is generally fixated with suture, steel wires or screws. Disadvantages of the Akin procedure include instability, shortening, under/over correction with excessive or sub-optimal bone resection, intraarticular fracture and plantar angulation caused by extensor pull and nonunion. The oblique proximal phalangeal osteotomy (OPPO) was recently introduced as an alternative to the Akin procedure. (The residents prefer to call it the “swivel” osteotomy.) It consists of a single oblique osteotomy directed proximal dorsal to plantar distal and offers many advantages to the Akin procedure. The OPPO eliminates the need for bone resection and with a single cut allows phalangeal displacement by rotating the phalanx to the desired position. The construct results in minimal shortening, is technically simple, adjustable and very conducive to rigid fixation. How You Can Attain The Best Results For An OPPO One would perform the OPPO after completing the first metatarsal procedures. Reflect the capsuloperiosteal tissue off the base of the proximal phalanx and shaft. However, be sure to leave the medial soft tissue capsular structures intact in order to facilitate plication and preservation of blood supply to the bone. Perform the osteotomy 25 to 30 degrees to the longitudinal bisection of the proximal phalanx from dorsal proximal to plantar distal. It is important to perform the osteotomy at a gradual angle in order to facilitate the farthest distal exit as possible. This will avoid varus or valgus displacement along the Z axis. Plantarflexion of the hallux will aid in accessing this position. One will often see a small dorsal tubercle of bone located at the base of the phalanx. This represents the anatomic attachment of the dorsal capsule and short extensor tendon. If this is present, begin the osteotomy directly proximal to this tubercle. After completing the osteotomy, rotate the phalanx to the desired position and clamp or temporarily fixate it from dorsal to plantar with a 0.062-inch K-wire. Obtain fluoroscopic views in order to ensure correction. Using standard AO technique, one can accomplish rigid fixation with one or two 2.7-mm screws or a combination of a 2.7-mm screw and a 2.0-mm screw. After inserting the initial 2.7-mm screw, one may easily utilize a second 2.0-mm screw by employing the 0.62-in. K-wire drill hole used during temporary fixation as the pilot. Postoperative care includes immediate weightbearing in a postoperative shoe if one has combined the OPPO with a distal procedure. A loose-fitting stable running shoe is permitted between weeks six and eight. Are There Other Potential Uses For The OPPO? The OPPO procedure is versatile and allows for various other uses. For instance, the OPPO may be useful in complementing the metatarsal with an excessively deviated PASA if the surgeon elects to avoid executing a PASA reducing osteotomy. Surgeons may also employ this procedure to correct hallux interphalangeus of up to 25 degrees or use it as an alternative to the dorsiflexory wedge osteotomy in the correction of hallux limitus, which is notorious for its difficulty in fixation. In this scenario, the maneuver is technically easy and simply consists of sliding the proximal phalanx proximally to the desired position. One can pare off excess overhanging bone in the joint. This feature suggests its use as a sensible adjunct to other procedures by elevating the phalanx, shortening the lever arm and indirectly lengthening the long flexor tendon. Lastly, one may consider the OPPO when correcting residual transverse plane malunion deformities of the proximal phalanx after a failed hallux valgus repair. Surgeons can easily appreciate the advantage of being able to correct the deformity precisely with little to no shortening while using stable fixation. Is The Distal CSO The Answer For An Increased PASA? A common consequence of basilar rotational osteotomies is an increase in the proximal articular set angle (PASA), which is also known as the distal metatarsal articular angle (DMAA). One may correct this by performing a distal CSO. This procedure employs the same osteotomy described above but it is performed at the head of the metatarsal and in reverse. Fixate the osteotomy with a mini fragment screw, K-wire or absorbable pin. Its advantages are similar to the proximal CSO. It is adjustable, technically easy to perform and results in little to no shortening. However, one should be aware of the potential long-term implications of all PASA reducing osteotomies. Recent studies indicate that these osteotomies may be linked to sub first metatarsal arthritis due to the displacement of the plantar cristae. In Conclusion Treatment options for hallux valgus can be confusing in today’s world, particularly with the rapid evolution of procedures and available technology. The crescentic shelf and oblique proximal phalangeal osteotomies offer exciting alternatives to traditional podiatric surgical techniques. In our hands, we have found the procedures very reliable with minimal complications and they have stood the test of time. Dr. Cohen is Chief of the Podiatry Section and Director of the Podiatric Primary Medicine and Surgical Residency Programs at the Veterans Affairs Medical Center in Miami. He is a Diplomate of the American Board of Podiatric Surgery and is a Fellow of the American College of Foot and Ankle Surgeons.
References 1. Cohen M, Roman A, Ayres M, Freedline A. The crescentic shelf osteotomy. J Foot Ankle Surg 32:209-226, 1993. 2. Akin OF. The treatment of hallux valgus: a new operative procedure and its results. Med Sentinel 33:678-679, 1925. 3. Cohen M. The Oblique Proximal Phalangeal Osteotomy in the correction of hallux valgus. J Foot Ankle Surg 42: 282-289, 2003. 4. Breslauer C, Cohen M. Effect of proximal articular set angle-correcting osteotomies on the hallucal sesamoid apparatus: a cadaveric and radiographic investigation. J Foot Ankle Surg 40:366-373, 2001.