A Closer Look At The Percutaneous Calcaneal Displacement Osteotomy
Podiatric surgeons commonly perform an extraarticular calcaneal osteotomy on hindfoot deformities of the foot and ankle.1 One would typically perform this powerful osteotomy in conjunction with other procedures. Complications with the percutaneous calcaneal displacement osteotomy are rare.2-4 This is in contrast to the customary lateral approach of a calcaneal osteotomy as the surgeon may see complications that include wound dehiscence, sural nerve damage, sural neuritis, delayed union, non-union, infection and invasion of the medial neurovascular structures.2-6 Due to the thin soft tissue layer on the lateral aspect of the calcaneus, wound dehiscence is a common problem one encounters when performing the traditional lateral approach to the calcaneal osteotomy. Large incisions on the lateral aspect of the calcaneus can cause fibrosis in this area, leading to nerve symptoms. When performing this osteotomy open, the surgeon must be cautious about exiting the medial aspect of the calcaneus due to the neurovascular structures.6-7 When it comes to the percutaneous calcaneal displacement osteotomy technique, one would perform this procedure through four small stab incisions. The technique avoids major neurovascular structures. I have successfully completed more than 100 percutaneous calcaneal displacement osteotomies since the year 2000. With this procedure, I have been able to achieve radiographic evidence of osseous healing, minimize wound problems, avoid invading the neurovascular structures and provide pleasing cosmetic results to the surgical site. What Does The Research Reveal? Numerous authors have described the medial displacement osteotomy for the treatment of conditions such as calcaneal valgus deformities, posterior tibial tendon dysfunction and flexible flatfoot deformities with good results reported for adults and children.1-4,8-20 Posterior tibial tendon dysfunction occurs when the adult-acquired flatfoot becomes evident with the heel in a valgus position, the flattening of the medial longitudinal arch and forefoot abduction.14,16,21 Surgeons are currently using calcaneal osteotomies in combination with various ancillary procedures to treat posterior tibial tendon dysfunction.2,3,8-10,12-17,21-31 Flexible flatfoot is one of the most common orthopedic problems among children.17,18 Torosian, et. al., found that the medial slide calcaneal osteotomy is a simple and effective treatment for hindfoot valgus.19 When one detects valgus malalignment, medializing the calcaneus provides satisfactory outcomes.22 In advanced stages of the deformity, the medial column may be affected. Accordingly, there is a need for tendon transfers or joint fusions (in adults), and these are effective treatments when one combines them with the medial calcaneal displacement osteotomy.22 Mann and Myerson both describe a posterior calcaneal osteotomy in which one moves the posterior aspect of the calcaneus medially.3,9,26-28 Surgeons would frequently perform this type of osteotomy in conjunction with other bony or soft tissue procedures. Mann describes the foot as a tripod.3,9 The three legs consist of the first metatarsal head, the fifth metatarsal head and the calcaneus. If too much heel valgus is present, the tripod does not function properly and the medial aspect of the foot sags. Performing the posterior medial calcaneal displacement osteotomy places the calcaneus back into its correct position.3,9 One may often see a loss of hindfoot height after a calcaneal fracture.22 Performing the posterior calcaneal osteotomy enables the surgeon to shift the posterior aspect of the calcaneus plantarly to restore the height of the hindfoot.22 Authors have also reported that the posterior calcaneal slide osteotomy can correct abnormal heel alignment that is in varus.22,32 The objective of the osteotomy is to reposition the Achilles tendon, plantar fascia and the bone more laterally. The aforementioned deformities are indications for the open posterior calcaneal displacement osteotomy. These are the same indications for the percutaneous calcaneal displacement osteotomy. One may perform the percutaneous calcaneal displacement osteotomy on any patient who would experience a benefit from the traditional open calcaneal displacement osteotomy. There are no contraindications to a percutaneous calcaneal displacement osteotomy as opposed to an open calcaneal displacement osteotomy. However, the advantages are quicker soft tissue healing time and better cosmesis, minimal trauma to the local soft tissues and bone, less edema and fewer neurovascular complications. What You Should Look For In The Physical Exam And Imaging Studies One should first ensure a thorough physical examination, assessing vascular, neurological, dermatological and clinical biomechanical function. Radiologic evaluation of the foot is very important in assessing the entire foot deformity. Routine views of the foot should include anterior-posterior and lateral views.15,22,33,34 The anterior-posterior view allows one to evaluate loss of normal alignment of the talus and first metatarsal, and the degree of subluxation of the talus and navicular.35 From the lateral radiograph, one should measure the calcaneal pitch.35,36 According to a study by Smith, Sima and Reischl, this a very reliable radiographic angle in the evaluation of flatfoot and cavus deformities.35,36 One may also evaluate subluxation of the talonavicular and navicular cuneiform joints through lateral radiographs.35 Clinicians should obtain ankle radiographs as well including anterior-posterior, lateral and mortise views.15,22 These views will allow for proper assessment of the ankle joint for degenerative processes and malalignment.35 One should obtain a long axial view to quantify the amount of valgus or varus present.35,37 Paley describes a method (modified from Salzman and el-Khoury’s method) in which the surgeon measures the alignment between the body of the calcaneus and the tibia in order to assess the degree of varus or valgus deformity.38 Clinicians should obtain all foot and ankle radiographs with the patient weightbearing and the knee extended. Also be sure to obtain comparative contralateral views.15,32,33,35 The knee should be fully extended because deformities of the hindfoot and midfoot are frequently associated with a tight gastrocnemius.22 Other Preoperative Considerations The equipment needed to perform the percutaneous calcaneal displacement osteotomy is minimal. The equipment includes a #15 blade, a curved Kelly hemostat, a straight hemostat, a large cannulated cancellous screw set and appropriate suture for closure. Equipment also includes a 12-inch flexible Gigli saw. The Gigli saw must be very flexible. If it is not, there is a good chance that the saw may become kinked around the curved superior edges of the calcaneus. When this occurs, it can make the procedure more difficult and increase the risk of injury to the soft tissue. A fluoroscopy unit will be necessary to perform this osteotomy. This procedure is designed to eliminate neurovascular compromise when performing a calcaneal osteotomy. Greene, et. al., performed a study evaluating the medial neurovascular structures that crossed the site of the traditional open calcaneal displacement osteotomy.6 In this study, they found that an average of four neurovascular structures crossed the osteotomy site and most were branches of the lateral plantar nerve and branches of the posterior tibial artery.9 In addition, the sensory branch of the lateral plantar nerve crossed the osteotomy in 86 percent of the subjects studied, Baxter’s nerve (a distal branch of the lateral plantar nerve) crossed in 95 percent of the specimens, and the posterior tibial artery distributed from zero to three branches that crossed the osteotomy at variable intervals.6 It is clear that surgeons must be concerned with a number of structures on the medial aspect of the foot when performing a calcaneal osteotomy. On the lateral aspect, the sural nerve and its branches are in the vicinity of the calcaneal displacement osteotomy. The approach of this procedure is through four small stab incisions that the surgeon would place away from neurovascular structures. One would make tunnels deep to the neurovascular structures that come into play when performing the osteotomy. The plantar aspect of the foot is also of concern. The origin of musculature, ligaments and nerves all are in very close proximity to the exit site of the saw. It is of the utmost importance not to violate these structures when exiting the plantar cortex whether one performs the procedure open or percutaneously. A Step-By-Step Guide To The Procedure Initially, one should emphasize supine positioning for the patient, allowing the patient’s foot to hang over the operating table. Typically, the surgeon would use four incisions, two on the lateral aspect of the heel and two on the medial aspect of the heel. Palpate the plantar medial calcaneal tubercle and make a small oblique (in the line of the osteotomy) stab incision just distal to the tubercle, inferior and posterior to the posterior tibial nerve. Using the curved hemostat, bluntly deepen the incision down to bone. Using the curved hemostat, with the curved end pointing toward the skin, proceed to make a tunnel toward the superior aspect of the calcaneus. Ensure the tunnel is deep to all of the neurovascular structures. It is important to keep the tip of the hemostat against the calcaneus while tunneling superiorly. Tent the skin at the superior medial aspect of the calcaneus. Make a stab incision along the resting skin tension lines. The tip of the curved hemostat exits the incision site. This is the site where one will introduce the Gigli saw. Open the tip of the hemostat and clamp a 12-inch flexible Gigli saw. Pull the hemostat inferiorly through the tunnel and through the inferior medial incision. One loop of the Gigli saw is now exiting the medial inferior incision. Unclamp the hemostat from the end of the Gigli saw. Redirect attention back to the superior medial incision. Using the straight hemostat, bluntly tunnel across the superior aspect of the calcaneus. Make this tunnel anterior to the Achilles tendon and posterior to the posterior facet of the calcaneus in Kagers’s triangle. Be sure to keep the hemostat on the superior aspect of the calcaneus while tunneling across. Tent the skin laterally and make a stab incision posterior to the peroneal tendons and sural nerve (along the resting tension skin lines). Remove the hemostat from the medial superior site and introduce the small straight hemostat from the superior lateral incision. Follow the tunnel and exit the superior medial incision site. Open the tips of the hemostat and place the free end of the Gigli saw into the tip. Clamp down and pull the hemostat and Gigli saw through the tunnel from superior medial to superior lateral. Exit the superior lateral incision, pulling the end of the Gigli saw through the incision. Unclamp the hemostat. Make the fourth stab incision at the lateral inferior location of the calcaneus. This incision should be in line with the proposed osteotomy. Bluntly deepen the lateral inferior incision to the calcaneal body. Once again, make a tunnel toward the superior lateral incision. Be sure to keep the tip of the hemostat against the body of the calcaneus. This tunnel will be deep to the neurovascular structures. Exit the superior lateral incision and open the tip of the hemostat. Insert the free loop of the Gigli saw into the tip of the curved hemostat. Pull the hemostat back through the tunnel and out the lateral inferior incision. Release the hemostat. Hook the Gigli saw handles to the loops of the Gigli saw on the medial and lateral aspects of the foot. Pull the Gigli saw taut without kinking the saw and have equal amounts of the Gigli saw exiting each inferior incision. The Gigli saw should now be taut to the calcaneus and deep to all neurovascular structures across the superior aspect, and along the medial and lateral body of the calcaneus. Using fluoroscopy, take a lateral view of the foot. This will ensure proper placement of the saw. Check to ensure there are no kinks in the saw and that the saw is in the desired placement. The placement of the incisions ensures that one performs the osteotomy in the proper plane, which should have a posterior inclination at approximately 45 degrees to the plantar surface of the rearfoot.8 Grip the Gigli saw handles and perform the osteotomy. Have an assistant stabilize the lower leg. The assistant should stabilize the hindfoot and ankle, and dorsiflex the foot as the osteotomy is being performed. Doing so tightens the plantar fascia and Achilles, and helps stabilize the calcaneus. This will stabilize the rearfoot during the osteotomy. As the saw advances through the calcaneus, the surgeon should widen his or her arms to avoid harming the skin while making the cut. While advancing toward the plantar aspect of the calcaneus, take extreme care not to exit the calcaneus forcefully and violate the vital plantar structures. If necessary, one can take another lateral view when approaching the plantar cortex. Once the osteotomy is complete, cut one end of the Gigli saw at the incision site. Pull the opposite end of the saw out of the foot.11 Proceed to displace the free posterior calcaneus to the desired plane of correction. While displacing the osteotomy, have the assistant plantarflex the foot. This will loosen the plantar fascia and Achilles tendon, and allow one to manipulate the posterior aspect of the calcaneus into the desired position with very little resistance. Once it is in the desired position, dorsiflex the foot to tighten the plantar fascia and dorsiflex the Achilles tendon to lock the osteotomy in place. Proceed to drive two guide wires (from the large cannulated cancellous screw set) through the plantar posterior aspect of the adult foot or use two 0.062 smooth K-wires for a pediatric patient. The surgeon should attempt to purchase the subcortical bone just inferior to the posterior calcaneal facet. This bone allows for strong screw or K-wire purchase. Once again, check the screw or K-wire position with fluoroscopy using lateral and calcaneal axial views. It is very important not to violate the posterior facet of the calcaneus. Close all incisions. Pertinent Insights On Intraoperative Complications In regard to this procedure, there are few intraoperative complications. If the Gigli saw is not flexible enough, the surgeon may encounter kinks in the saw. It is also recommended to have a 1/4-inch straight osteotome present. Surgeons can insert this into the inferior medial incision to pry the osteotomy apart if they encounter any hangups when trying to manipulate the posterior aspect of the osteotomy. The surgeon who is not experienced in this particular procedure can use two 0.62 K-wires as guide wires in the calcaneus as an osteotomy guide. This is not necessary but can be helpful in guiding the surgeon through the osteotomy. Place the guide wires along the lines of the desired osteotomy position. If the surgeon needs to abort the percutaneous calcaneal displacement osteotomy, one can easily convert this to an open procedure by connecting the lateral incisions to produce the traditional incision for the open calcaneal displacement osteotomy. An unpublished study/review documented the percutaneous calcaneal displacement osteotomy on five cadaver specimens. Surgeons dissected out the neurovascular structures on all of the specimens after performance of the osteotomy. In all five cases, no neurovascular structure was traumatized. Key Postoperative Pearls When it comes to postoperative management, the surgeon should emphasize nonweightbearing in a below the knee posterior splint for two weeks. Ancillary procedures will dictate the remaining course of postoperative management. In regard to the first postoperative visit after a patient has undergone the osteotomy without adjunctive procedures, the surgeon may have the patient proceed with weightbearing in a cast boot for four more weeks. Physical therapy is recommended after six weeks in order to strengthen the musculature. In Summary The literature is full of good results of posterior displacement osteotomies. This osteotomy offers the same degree of correction as the open posterior displacement osteotomy and yields the same outcomes of biomechanical correction. Calcaneal osteotomies have and will remain a vital part in the surgical treatment of complex hindfoot deformities. The percutaneous calcaneal displacement osteotomy is a very effective way of reducing hindfoot deformities and minimizing postoperative complications. Dr. DiDomenico is affiliated with the Forum Health/Western Reserve Care System in Youngstown, Ohio. He is the Director of the Reconstructive Rearfoot and Ankle Surgical Fellowship within the Ankle and Foot Care Centers and the Ohio College of Podiatric Medicine. Dr. DiDomenico is a Fellow of the American College of Foot and Ankle Surgeons. For further reading, seee “How To Perform The Double Calcaneal Osteotomy” in the December 2004 issue of Podiatry Today or “Roundtable Insights On Adult-Acquired Flatfoot” in the June 2005 issue. Also check out the archives at www.podiatrytoday.com.
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