Key Pearls Of Calcaneal Osteotomies

Author(s): 
By Kieran T. Mahan, DPM

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.

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