Essential Insights On The Medial Slide Calcaneal Osteotomy
Both pediatric and adult-acquired flatfoot deformities, particularly posterior tibial tendon dysfunction (PTTD) stage II, remain difficult to treat and there is much controversy in regard to the optimal form of treatment. Patients usually present with increased pain and swelling along the medial aspect of the ankle or rearfoot. The foot generally maintains an abducted forefoot position and a decrease in the height of the medial longitudinal arch. Sometimes patients can perform a double heel raise but cannot perform a single heel raise. This signifies posterior tibial tendon pathology.
The success of conservative treatment options such as immobilization, rest, ice, nonsteroidal anti-inflammatory drugs (NSAIDs), ankle foot orthoses or physical therapy depends on the stage of the deformity, duration and severity of symptoms. After one has exhausted all conservative measures, treating physicians may consider surgical options, taking into account the severity of the deformity, flexibility and planal dominance as well as the patient’s age and functional demands.
The surgical correction of stage II PTTD often requires soft tissue augmentation of the posterior tibial tendon along with structural or bony reconstruction. Koutsogiannis first suggested sliding the calcaneus medially as a treatment for flexible pes planus.1 Surgeons may employ the medial slide calcaneal osteotomy to treat flatfoot deformities in both the adult and pediatric patient but it is rarely in use as an isolated procedure. Surgeons commonly perform the medial slide calcaneal osteotomy in conjunction with a flexor digitorum longus tendon transfer, lateral column lengthening or a medial cuneiform osteotomy or arthrodesis.
The surgeon also needs to address any equinus deformity associated with the pathology. When it comes to lengthening the gastrocnemius-soleus complex, there are many surgical techniques one can use. We prefer a percutaneous Achilles tendon hemi-sectioning technique or endoscopic gastrocnemius recession when appropriate. The medial slide calcaneal osteotomy alters the pull of the gastrocnemius-soleus muscle group slightly medial to the axis of the subtalar joint. This effectively places the Achilles tendon medially and increases the varus pull on the hindfoot while correcting the rearfoot valgus alignment. Transfer of the flexor digitorum longus tendon aids in restoring the inversion function of the posterior tibial tendon.2
Conventional fixation of the osteotomy occurs with a large headed screw. However, this technique has been associated with high rates of complications due to posterior irritation from the screw head, subsequently leading to its removal.3 Fixation methods for osteotomies have advanced throughout the years and include the use of headless screws as well as non-locking and locking plates. Some have advocated fixed angle, locking step-off plates for the medial slide calcaneal osteotomy. These plates have an incorporated translational distance with a step-off to allow for the desired medial shift (6 to 10 mm) of the calcaneal tuberosity.
A Step-By-Step Guide To Surgical Technique
Ensure that the patient is in a supine position on the operating table. Utilize a thigh tourniquet unless it is contraindicated. Start the incision at the superior lateral aspect of the calcaneal tuberosity and extend it distally and inferiorly at a 45 degree angle to the weightbearing surface, parallel to the peroneal tendons. Take care to avoid injury to the sural nerve by utilizing blunt dissection until you locate and retract the nerve. Then perform sharp dissection to the periosteal layer along the lateral aspect of the calcaneus.
Make an osteotomy parallel to the incision, ensuring that it extends anterior to the plantar calcaneal tubercle. Use a sagittal saw first to score the lateral cortex and then advance the saw just prior to the medial cortex. Take care not to over-penetrate through the medial cortex in order to avoid injury to vital neurovascular structures such as the posterior tibial artery and nerve as well as the lateral plantar nerve.4
Then use a large osteotome to complete the osteotomy across the medial cortex. Slight distraction of the osteotomy with osteotomes or a lamina spreader can facilitate the translation. Translate the posterior tuberosity medially, usually between 6 and 10 mm. We utilize one fingerbreadth as an appropriate amount of translation. During the translation of the tuberosity, it is important to avoid superior migration. One can achieve this by flexing the knee to relax the gastrocnemius muscle.5
Surgeons can temporarily stabilize the osteotomy by inserting a Steinmann pin percutaneously, starting posterior to anterior, and angling it slightly lateral due to the medial shift of the osteotomy. Intraoperative fluoroscopy, especially a calcaneal axial view, can confirm the corrected position of the tuberosity. After confirming the desired position, position the lateral step-off plate with the desired translation over the osteotomy. Secure the plate with the use of four locking screws, two in the main body of the calcaneus and two into the displaced tuberosity.
Following successful translation and fixation, use a bone rasp or a small rotary burr to smooth any sharp step-off on the lateral side of the osteotomy. Rounding the lateral shelf helps in preventing irritation to the adjacent peroneal tendons and the sural nerve. Carry out other concomitant procedures for correcting the flatfoot deformity at this time.
What You Should Know About Potential Complications
Previous studies have shown complications with single screw fixation of the medial slide calcaneal osteotomy. These complications include hardware becoming painful for patients when weightbearing due to a prominent screw head and painful scar formation at the posterior heel, leading to a second surgery. Screw removal rates are reportedly as high as 53 percent.3,6
In a recent study, Abbasian and colleagues compared three different fixation methods for calcaneal osteotomies. These fixation methods included a lateral locking plate, a headless screw or a headed screw.3 The rate of hardware removal due to symptoms was 47 percent in the headed screw group, 11 percent with headless screws and 6 percent with lateral plates. This suggests that the use of lateral plates for fixation of calcaneal osteotomies is associated with less hardware irritation and subsequent removal.
In a cadaveric study, Konan and coworkers compared the mechanical stability of locking step-off plates to that of single 7 mm compression screws.7 The load to failure rate was significantly higher in the step-off plate group than the single compression screw group. The authors concluded that this may suggest greater stability with locking plate fixation and possibly earlier weightbearing.
In Conclusion
Although compression across the osteotomy site does not occur with step-off plate fixation, it is our experience that non-unions are rare due to the cancellous nature of the calcaneus. Locking plate fixation for the medial slide calcaneal osteotomy is advantageous in that it is associated with less hardware irritation and subsequent hardware removal.
In addition, the medial slide calcaneal osteotomy utilizes the same incision as the osteotomy, decreasing the need to make a separate incision for screw fixation at the posterior heel. Although further prospective randomized clinical trials are needed, early weightbearing may be possible with the use of locking plate fixation for medial slide calcaneal osteotomies.
Dr. Cook is the Director of Podiatric Medical Education at University Hospital at the University of Medicine and Dentistry of New Jersey in Newark, N.J. He is a Fellow of the American College of Foot and Ankle Surgeons.
Dr. Labib is the Chief Resident within the Podiatric Residency Program at University Hospital at the University of Medicine and Dentistry of New Jersey in Newark, N.J.
References
1. Koutsogiannis E. Treatment of mobile flat foot by displacement osteotomy of the calcaneus. J Bone Joint Surg Br. 1971; 53(1):96-100.
2. Mann R, Thompson F. Rupture of the posterior tibial tendon causing flat foot. J Bone Joint Surg. 1985; 67(4):556-561.
3. Abbasian A, Zaidi R, Guha A, Goldber A, Cullen N, Singh D. Comparison of three different fixation methods of calcaneal osteotomies. Foot Ankle Int. 2013; 34(3):420-5.
4. Greene D, Thompson M, Gesink D, Graves S. Anatomic study of the medial neurovascular structures in relation to calcaneal osteotomy. Foot Ankle Int. 2001; 22(7):569-571.
5. Haddad S, Mann R. Flatfoot deformity in adults. In Coughlin M, Mann R, Saltzman C (eds). Surgery of the Foot and Ankle. Eighth edition. Mosby Elsevier, Philadelphia, 2007, pp. 2158-2180.
6. Bolt P, Coy S, Toolan B. A comparison of lateral column lengthening and medial translational osteotomy of the calcaneus for the reconstruction of adult acquired flatfoot. Foot Ankle Int. 2007; 28(11):1115-1123.
7. Konan S, Meswania J, Blunn G, Madhav R, Oddy M. Mechanical stability of a locked step-plate versus single compression screw fixation for medial displacement calcaneal osteotomy. Foot Ankle Int. 2012; 33(8):669-674.
