Key Pearls Of Calcaneal Osteotomies

Calcaneal osteotomies have been a mainstay of foot and ankle surgery for many years, and are critical in the realignment of significant foot deformities. Both varus and valgus deformities often require calcaneal deformities for correct alignment. Although a large number of calcaneal osteotomies have been described in the literature over the years, there are a few principal ones that tend to be more commonly used than others. One would perform the Dwyer osteotomy for frontal plane deformity of varus in the cavus foot. Surgeons often perform the Evans osteotomy for realignment of the adolescent valgus foot, but it is also used during adult flatfoot repairs. The sliding calcaneal osteotomy is commonly used to treat adult flatfoot. Each of these procedures has a unique powerful way of realigning the position of the heel with respect to the ground. Calcaneal osteotomies exert their effect through realigning the position of the heel at the time of heel strike. The Dwyer takes the heel out of varus by wedging the calcaneus from the lateral side of the heel. The Evans has multiple effects. It realigns the heel (taking it out of valgus) and reduces the abduction of the midtarsal joint. It plantarflexes the forefoot on the rearfoot. Correction occurs in all three planes. The sliding calcaneal osteotomy serves to center the valgus heel back under the leg. You can modify the procedure by using a varus opening wedge to produce frontal plane correction. Each of these procedures is technically straightforward. Understanding the proper indications for each of the procedures is essential. Yet there are also some key technical elements that can make a large difference in the outcomes. In order to ensure the best results for your patients, let’s take a closer look at these procedures, starting with the Dwyer osteotomy. How The Dwyer Osteotomy Works Dwyer described this osteotomy as both an opening medial osteotomy and a lateral closing wedge osteotomy. Either way, the procedure is designed to take the heel out of varus. Knowing this, the calcaneal axial X-ray would seem to be ideal for determining when you should perform this procedure. Although the X-ray may be useful, performing the Coleman block test is even more useful. It helps you differentiate between structural varus and varus created by plantarflexion of the first ray. In many cavus feet, it is the plantarflexion of the first ray that causes the inversion appearance of the heel that we see in stance. In order to perform the Coleman block test, you place a block under the lateral portion of the forefoot to neutralize the effect of first ray plantarflexion. If there is no true structural varus, the heel will come out of varus to a vertical position. Be aware that performing the Dwyer alone in these patients with a plantarflexed first ray will create increased stress beneath the sesamoids with focal pain. If you perform the Dwyer along with a dorsiflexory osteotomy in these patients, it will lead to excessive pronation and collapse of the foot. Worse than the poorly performed Dwyer is the unnecessary Dwyer osteotomy. Indeed, the indication must be very specific. Pertinent Pointers Of The Procedure The technique is based upon a lateral approach. The primary concern is the sural nerve, which splits into an anterior and posterior branch superiorly. Entrapment of the sural nerve is a complication that is truly disconcerting to the patient on a long-term basis. Although some bruising of the nerve is not uncommon and may result in short-term paresthesias, entrapment of the nerve often creates sufficient pain that the result is unsuccessful, regardless of the structural outcome. Make the curved incision from the superior surface of the calcaneus, 1 to 2 cm proximal to the upper margin of the bone, extending distally past the lower margin of the calcaneus. Carry the dissection down through the superficial fascia, which is mobilized enough to create room for resection of the wedge and possible insertion of staples. Proceed to make an incision in the periosteum and use a key elevator to reflect tissues subperiosteally. Use Crego elevators superiorly and inferiorly. Insert a flat Crego first and then insert a curved Crego to protect the medial structures. With the Cregos in place superiorly and inferiorly and Senn retractors proximally and distally, the site is now prepared for the osteotomy. Use a larger saw blade and constant irrigation. Make two cuts that will converge just prior to the medial side. Usually, I begin with approximately a 3/8-inch wedge, but this is clearly variable based upon the individual requirements. A common mistake is to fail to cut the entire dorsal and plantar surfaces, leaving something of a “C” shape, which is unable to bend and properly close the wedge. Maintaining the hinge is very helpful in preventing dorsal migration of the proximal fragment. However, if the hinge is cut through, you can reduce the deleterious effects by having two points of fixation to restrict rotation or shift. Once you’ve closed the osteotomy, take a look at the foot to determine if you have achieved frontal plane correction. If additional correction is necessary, perform reciprocal planning until you attain the desired alignment. There are a number of fixation options, any one of which can be acceptable. I commonly use two staples, but using a large screw or one or two Steinmann pins can also be very effective. If you use staples or screws, make every effort to ensure they are not prominent. Sometimes, it’s necessary to remove the hardware, but ideally we should try to minimize those occurrences. Postoperative care for these patients involves eight to 10 weeks in a cast with the first eight weeks non-weightbearing. Procedures that may be performed along with the Dwyer include the dorsiflexory osteotomy of the first metatarsal, the Cole midfoot dorsiflexory osteotomy, the split tibialis anterior tendon transfer, digital fusions, etc. Insights On The Evans Osteotomy It would be fair to say the introduction of the Evans osteotomy revolutionized our care of the deformed flatfoot. Although Evans described it as a treatment for the rigid flatfoot, the procedure has been most commonly and successfully used for the flexible unstable foot. From the time the late Jim Ganley, DPM, first introduced the procedure in a teaching film and through his lectures, the Evans has undergone modifications that have improved its effectiveness and predictability. Evans serendipitously noted that over-shortening of a clubfoot led to the development of a flatfoot. He reasoned correctly that lengthening of the lateral column could correct the flatfoot deformity. The procedure he utilized relies on lengthening of the lateral column by interpositioning a bone graft to realign the midtarsal joint and achieve correction in three planes. The lengthening creates tension on the plantar calcaneocuboid ligaments. This tension plantarflexes the forefoot on the rearfoot. This creates a significant sagittal plane correction. Once thought of as just a transverse plane correction, the Evans creates powerful realignment in three planes. You begin the Evans procedure by making an oblique incision centered over the distal lateral calcaneus. In order to minimize scarring, your incision should follow the relaxed skin tension lines. Evans originally described this procedure with a longitudinal incision. This incision provides good exposure but thicker scarring. An important consideration is to avoid the intermediate dorsal cutaneous nerve superiorly and the sural nerve inferiorly. Deepen the incision through the superficial fascia. Make an L incision through the extensor digitorum brevis, which you should then retract distally, exposing the lateral surface of the calcaneus. Retract the sural nerve and peroneal tendons inferiorly. In order to prevent instability, avoid opening the calcaneocuboid joint. Use a saw to cut the calcaneus through from lateral to medial. Make the cut 1 cm proximal to the calcaneocuboid joint in order to minimize the risk to vital structures in the area. Use a lamina spreader to lengthen the lateral column. After attaining the desired correction, use a ruler to measure the width necessary for the graft. Why You Should Consider Allogeneic Grafts One of the modifications that has changed the Evans is using bone bank allogeneic graft as the primary graft material. While autogenous bone is the gold standard, taking bone from the iliac crest or the tibia involves risks that usually exceed the potential benefits. Given the fact that the calcaneus is so vascular, it is an excellent host site for allogeneic bone. Rarely, particularly in the adolescent patient, is healing of allogeneic Evans grafts a problem. Mahan and Hillstrom demonstrated the success of the allogeneic grafts in this procedure. Tricortical iliac crest is the preferred allogeneic graft, as you can combine the strength of its cortical surfaces with the more rapid healing of its interior cancellous architecture. I usually begin with a 16 to 18 mm piece from the Musculoskeletal Transplant Foundation. When treating adolescent patients, I often use a graft that is about 1 cm wide laterally and taper a couple of millimeters to facilitate insertion. Adults usually cannot tolerate grafts quite that large. One can also procure a graft for a Cotton osteotomy from the same basic graft. Using allogeneic bone minimizes risk to the patient and provides a consistently good result. After cutting the graft, insert it into the cut just above the lamina spreader, which is situated on the inferior aspect of the cut. Tap it into place with a mallet and bone tamp. Using a wider bone tamp is more effective at spreading the force of the mallet across the graft and preventing the graft from being crushed. Fixation is usually unnecessary, but if there is any question as to the stability of the graft, drive a .062 K-wire from the cuboid across the graft into the body of the calcaneus. What You Should Know About Post-Op Considerations And Adjunctive Procedures Postoperatively, you should emphasize eight to 10 weeks of non-weightbearing and have the patient follow that with two weeks of weightbearing. Emphasize isometric exercises in the cast approximately four to six weeks after surgery and have the patient begin range of motion exercises in a cam walker at six to eight weeks. Perform serial X-rays to ensure the progression of graft healing. Tendo-Achilles lengthening is usually necessary with this procedure and medial procedures are routine. Medial arch suspension (Young suspension, advancement of tibialis posterior, spring ligament advancement) and/or a Cotton osteotomy are the most common procedures. Keep in mind that fusions at the navicular cuneiform or first metatarsal cuneiform joints are sometimes necessary in the face of degenerative joint disease or severe instability, particularly in adult feet. How To Master The Sliding Calcaneal Osteotomy Another procedure that has great utility is the sliding calcaneal osteotomy. Described by Koutsogiannis, the procedure involves a lateral incision, a through and through osteotomy of the calcaneus, displacement of the tuberosity medially, and fixation with Steinmann pins. This procedure serves to put the foot back under the leg. When treating patients with genu valgum, one can use this procedure to realign the foot to the floor. The procedure has proven to be useful for adult tibialis posterior dysfunction patients. Surgeons often combine it with medial procedures such as tendon repair, FDL transfer, Cotton osteotomy and limited medial column fusions. It is very valuable as an adjunct to the medial repair without some of the disadvantages associated with the Evans osteotomy. One of the advantages of the procedure is its technical simplicity. You would take a lateral approach through the superficial fascia and periosteum. Use the power saw to cut through the medial side of the calcaneus. Make sure the cut is oriented to include the majority of the tuberosity. Your cut should be somewhat oblique in order to help prevent shift of the posterior fragment superiorly. Unresolved equinus will likely result in the same proximal shift. Lengthening of the heel cord, if necessary, should be done prior to the osteotomy. Once you complete the osteotomy, shift the posterior fragment medially about 1 cm. It is still unclear how best to determine the correct amount of shift. Once you’ve completed the shift, the osteotomy is fixed in position. My own preference is to use two Steinmann pins, usually 7/64. Many people prefer using internal fixation with a large screw. In my own experience, too many of these screws need to be removed. This outweighs the advantages of the internal fixation. I remove the Steinmann pins at about seven to eight weeks if the X-rays demonstrate satisfactory consolidation. Weightbearing usually begins progressively at that time along with physical therapy. Key Tips About Modifications And Potential Complications One can modify this procedure by inserting a bone graft wedge to invert the heel. This can be used effectively, particularly when genu valgum is contributing to the deformity. Typically, I use two pieces of iliac crest graft, which I cut into a wedge shape with the wide side being approximately 4 mm. You can modify this based upon the deformity. Obviously, excessive inversion would be a major problem. Keep in mind that this is a powerful modification that should only be used on an occasional basis. Complications can include shift of the posterior fragment proximally, sural nerve entrapment, delayed or non-union and diffuse heel pain. In Summary Calcaneal osteotomies have a high rate of healing. The highly vascular calcaneus is key to the alignment of the foot and leg. Each of these osteotomies needs to be performed for the proper circumstances. The technique needs to be exact and the postoperative care and follow-up must be thorough in order to maximize optimal results. Dr. Mahan is the Associate Dean for Research and is a Professor in the Department of Surgery at the Temple University School of Podiatric Medicine. He is a Diplomate of the American Board of Podiatric Surgery, a Fellow of the American College of Foot and Ankle Surgeons, and a member of the faculty of the Podiatry Institute. CE Exam 108 Choose the single best response to each question listed below: 1. The Evans calcaneal osteotomy provides what type of correction? a. transverse plane only b. lateral column only c. correction in three planes d. midtarsal only 2. The Dwyer osteotomy a. is performed for varus deformity b. is always performed with a first metatarsal osteotomy c. does not require fixation d. is best performed through a medial exposure 3. The Evans osteotomy is performed technically with: a. a longitudinal skin incision b. an opening wedge osteotomy c. almost always with medial procedures d. rarely with a TAL 4. A sliding calcaneal osteotomy is best used: a. for transverse plane deformities b. with other procedures c. for juvenile flatfoot d. as an isolated procedure 5. What test should you use to determine whether a Dwyer osteotomy is necessary in a cavus foot? a. Hubscher maneuver b. Kellikian push up c. Coleman block d. Young maneuver 6. The sliding calcaneal osteotomy is effective for: a. patients with genu varum b. patients with genu valgum c. excessive internal tibial torsion d. peroneal spastic flatfoot 7. Fixation strategies for the Dwyer osteotomy are: a. staple b. Steinmann pin c. large fragment screw d. All of the above 8. In regard to the Evans osteotomy, all of the following are true except: a. Fixation is used when the graft is unstable b. The graft is tapered to facilitate insertion c. The medial cortex of the calcaneus is left intact d. The peroneal tendons are retracted inferiorly 9. In regard to the medial calcaneal slide osteotomy, all of the following are true except: a. The approach is lateral b. The sural nerve may become entrapped c. The peroneal tendons are anterior to the osteotomy d. The posterior calcaneus is shifted 1 inch laterally 10. Effects of the Evans osteotomy include all of the following except: a. increased calcaneal inclination angle b. decreased cuboid abduction angle c. increased coverage of the talar head by the navicular d. relaxation of the tendo Achilles Instructions for Submitting Exams Fill out the postage-paid card that appears on the following page or log on to www.podiatrytoday.com and respond electronically. 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.
 

References:

References 1. Mahan KT, Flannigan KP. Pathologic pes valgus disorders. Part I: Pes plano valgus deformity. In: Banks A, Downey MS, Martin DE, Miller SJ. eds. McGlamry’s Comprehensive Textbook of Foot and Ankle Surgery. 3rd ed. Philadelphia: Lippincott William & Wilkins, 2001:799. 2. Mahan KT, Flannigan KP. Pathologic pes valgus disorders. Part II: Tibialis posterior dysfunction. In: Banks A., Downey MS, Martin DE, Miller SJ eds. McGlamry’s Comprehensive Textbook of Foot and Ankle Surgery. 3rd ed. Philadelphia: Lippincott William & Wilkins, 2001, 862. 3. Mahan KT, Hillstrom HJ. Bone grafting in foot and ankle surgery: a review of 300 cases. JAPMA 88:109, 1998.