A Closer Look At Beaming The Columns In The Charcot Diabetic Foot
Surgeons currently perform beaming by using large diameter cannulated screws. From a surgical perspective, there are two columns to beam for Charcot. There is the medial column to include the first metatarsal, medial cuneiform, navicular and talus. There is also the lateral column to include the bases of the fourth and fifth metatarsals, the cuboid and calcaneus. From a reconstructive perspective, the two columns act independently.16 Beaming the medial column, however, will improve the function of the lateral column but the reverse is not true. A beamed lateral column is not capable of providing a stable and propulsive medial column.
In many instances, we see a unique biomechanical combination of events with Charcot neuroarthropathy. We see a collapsed medial longitudinal arch and a simultaneous ulcer laterally beneath the cuboid and a varus heel. This represents the reactive forces of weightbearing on a foot with a contracted and inelastic Achilles tendon and weakened midfoot ligaments that fail. The bases of the lesser metatarsals dislocate and sit dorsal to the cuboid, pushing the cuboid through the plantar surface of the foot. The peroneus longus and brevis tendons lose their functional pull with the cuboid altering the tendon balance. An unopposed tibialis posterior pulls the hindfoot into varus, instigating medial column collapses and an inability of the first metatarsal to bear weight, creating a rocker bottom.14 Beaming as a basic construct for reconstruction of both columns represents a surgical solution to a metabolic disease.
A Guide To The Art Of Beaming
In a severe Charcot midfoot collapse, beaming of the columns can act as a simple solution to a complex anatomic dilemma with fracture and/or dislocation at multiple joints. Simply stated, a beam down the medial column can align the first metatarsal, medial cuneiform, navicular and talus in a rectus alignment swiftly and surely as in the radiograph image below. Since the screw is cannulated, one can use a Steinmann pin to directly align all fractures and dislocations. It is the senior author’s experience that it is sometimes easier to remove some of the most dislocated/fractured bones, allowing one to manipulate the foot more easily into a rectus alignment with a Steinmann pin, replacing the dislocated bones just prior to beam placement.
Similarly on the lateral column, removal of a plantar dislocated cuboid from its non-anatomic location, debriding the cuboid on the back table and replacing it in an anatomically correct position can serve to eliminate the causation of the plantar ulcer and restore peroneal tendon function. The beams need to cross multiple joints beyond the joints that were fractured or dislocated.17 This is because the underlying disease is present in all of the joints and can be progressive if load sharing does not happen.
Furthermore, in many instances of Charcot, segments of the midfoot bones are virtually destroyed. Currently, we are investigating substitutes for those bones but until those become available, we frequently simply beam across the void, packing it with bone chips, platelet rich plasma and stem cells. It is understood that the beams will support the load, share the load with the remaining diseased bones and produce a framework for stability and weightbearing.
The question arises as to whether one should lock the medial and lateral columns with fusion of the subtalar joint or with a subtalar implant. The subtalar implant is the senior author’s preference because it limits any subtalar motion that is abnormal without completely eliminating inversion and eversion. Accordingly, there can be some mobile adaptation of the foot to the supporting surface on which it ambulates and, at the same time, the two columns can now serve to support each other.