Essential Insights On The Medial Slide Calcaneal Osteotomy
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.
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.