A Step-By-Step Guide to Calcaneonavicular Coalition Resection
- William Fishco DPM FACFAS
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Luckily, most of the pediatric conditions that podiatrists treat are relatively minor and/or self-limiting. Common conditions include gait abnormalities such as in-toeing, toe walking, excessive pronation and genu varum/valgum. Most of these conditions are amenable to “wait and see” and/or use of orthotics.
The most common painful condition that we see in pre-adolescents is calcaneal apophysitis. This is also treatable and never requires surgery. (Fortunately, children rarely need any surgery with the exception of tarsal coalition and severe flexible flat feet that are unresponsive to orthotic therapy.)
This blog is dedicated to the condition that oftentimes needs surgery — the calcaneonavicular coalition. Tarsal coalitions typically appear as calcaneonavicular coalitions in children between the ages of 9 and 11. Older children between the ages of 13 and 15 develop a middle facet coalition of the subtalar joint. These are the two most common coalitions. I have seen other joints such as talonavicular joint coalitions, although these are rare.
When a child presents to the office with a painful flatfoot, the most important element to determine is the flexibility of the foot. Always compare it to the asymptomatic foot. Look for asymmetry. A gait exam is important to assess for excessive abduction of the foot. For a calcaneonavicular coalition, one rarely needs a magnetic resonance imaging (MRI). Typically, X-rays are sufficient to detect the coalition. If the X-ray is normal yet I suspect a coalition, I may get a MRI to check for a fibrous coalition.
Surgery for resection of the coalition is the typical treatment course when there is pain and dysfunction. I will present a case and a step-by-step pictorial of the surgery.
A Closer Look At The Patient Presentation And Treatment
A 9-year-old child presented to the office complaining of pain in the right foot when wearing cleats and while running during football practice. His exam was consistent with a unilateral rigid flatfoot. He was guarding the foot when I attempted range of motion. The foot did not go into peroneal spasm, but he certainly everted the foot when I tried to move it. I took X-rays and noted a calcaneonavicular coalition. I performed surgery to resect the coalition.
The following is a highlight of the important aspects of the surgery. I placed the patient on the operating room table in the supine position and administered general anesthesia. I do not use a tourniquet, but you can use one if you would like. Mark out pertinent landmarks including the anterior process of the calcaneus at the calcaneocuboid joint, the sinus tarsi and the most lateral border of the extensor tendon apparatus. Next, take a fluoroscopic image. Visualize and mark the coalition on the foot. Then administer local anesthesia and begin the surgery.
Make a curvilinear incision from the inferior aspect of the tip of the fibula and carry it medially to the extensor tendon apparatus. The incision will cross the sinus tarsi and aim towards the talonavicular joint. You will always encounter the superficial peroneal nerve on the medial aspect of the incision, which you will need to identify and retract. Once you carry the dissection down to the deep fascia, you will see the extensor digitorum brevis muscle belly. Incise the fascia at the proximal extent of the muscle and detach it from the calcaneus and cuboid that you are retracting distally.
You will then see the calcaneocuboid joint. If you palpate with your finger at that level and move medially, your finger will be over the course of the coalition. As your finger butts up against bone medially, you are at the talonavicular joint. I try to identify that joint so I can protect the talar head when resecting bone. Next, I will take an osteotome and mallet to start my lateral bone cut. I will use fluoroscopy to do a “bull’s eye” view to confirm that I am in good position with care not to get into the calcaneocuboid joint.
Once the location is good, use the mallet and osteotome to complete the osteotomy. I will then do the same maneuver medially and once the position is good, I will perform the osteotomy. I use two osteotomes to manipulate the bone fragment out of the foot. At this point, the most important thing to remember is that in addition to taking enough bone width, make sure you do not leave a ledge of plantar bone. You should be able to use an instrument and palpate soft tissues. If you palpate any bone, then you need to keep working to remove that.
Certainly you want to assess range of motion, which should be somewhat improved but rarely greatly improved. I feel the surgery resolves pain more so than “fixes” a flat foot. Next, use an offset rasp to smooth out the cut bone margins and use bone wax on these margins. Repairing the deep fascia of the muscle, then the subcutaneous tissue closure, followed by skin closure, closes the wound.
There are some controversies regarding what to do after one resects the coalition. The most important aspect of the surgery is not what you put in after the resection, but what you take out. You need to be very generous in the amount of bone you resect. Resect at least 1 cm (enough to stick your finger between the bones). I will use bone wax on the cut margins of bone. I do not use muscle interposition, but I may use a fat allograft if I can harvest it nearby. Tarsal coalitions can return. You can prevent this with aggressive resection of bone. Also, I recommend immediate range of motion exercise. I will have patients walk in a fracture boot immediately following surgery per tolerance.
Hopefully this step-by-step pictorial of the surgery helps you prepare for your next calcaneonavicular coalition resection.