How To Achieve Improved Results With The Chopart Amputation

Author(s): 
By Gordon Zernich, CP, Tomas Dowell, CPO/LPO, Gary M. Rothenberg, DPM, FACFAS, and Michael M. Cohen, DPM, FACFAS

   Other surgeons have attempted to limit the risk of plantarflexion contractures and skin breakdown by contouring the anterior talus and calcaneus bones, resecting several tendons to the neck of the talus and sustentaculum tali bones, closing the wound with an anterior placement of the plantar flap, and performing lengthening of the Achilles tendon.3 These are just a few examples of how bone fusions, tendon transfers and tenotomies have progressed over the decades to preserve and balance all or part of a complex foot structure consisting of 28 bones (about 13 percent of the bones in the body), 33 joints, more than 100 muscles, ligaments and tendons, and a network of nerves, blood vessels, skin and soft tissue.

   While each patient and circumstance for amputation is unique, the Chopart level amputation also has its advantages over more proximal levels. It has been well documented that cardiac demand is increased in the patient with any level lower extremity amputation. In fact, this is often directly related to increased morbidity and mortality after amputation. Accordingly, we recognize that the more distal level amputation may ultimately increase longevity. Additionally, as with any level foot or leg amputation, the psychological aspect of preserving as much foot as possible cannot be understated. The surgeon will generally know within a few weeks post-op if the surgical wound will heal successfully. However, the long-term success will clearly be dependent upon the postoperative prosthetic department fitting and patient compliance with the device.

Keys To Addressing Post-Op Complications

The difficulties with the longevity of a fully successful, rather than acceptable, outcome of the surgical procedure itself include the progressive development of equinovarus. We have seen that development despite the lengthening of the Achilles and routing the anterior tibial tendon through the talar neck. In an effort to counterbalance the varus pull of the transferred anterior tibial tendon, the podiatry department of the Miami Veterans Affairs Medical Center (VAMC) instructs its providers to transfer the peroneal tendons to the lateral wall of the calcaneus instead of just “letting them fly.”

   When the patient presents at the amputee clinic, the talus and calcaneus remain after the Chopart amputation. The talus receives lateral and medial support from the fibula and tibia bones of the lower leg respectively, and allows dorsiflexion and plantarflexion movement as an ideal outcome. The subtalar joint joins the talus with the calcaneus permitting, ideally, medial and lateral movement of the lower leg over the heel and inversion and eversion moments of the residual foot. In short, the remaining hindfoot affords the amputee multiaxial movement and moments when it is fitted and aligned with a prosthetic, orthotic or hybrid “prosthosis” best suited to the need. That multiaxial movement is what separates the more sophisticated and costly prosthetic feet from those that are more suitable for lower activity level, below or above the knee amputees.

What You Should Know About Above Ankle Prostheses

The most important characteristics of the clinical evaluation are the activity, compliance and motivational level of the patient. It may or may not be related to the surgical outcome but the choice of the prosthetic device depends upon the patient’s ability to bear weight, ambulate and perhaps even to vary cadence. However, there are two basic types of Chopart prostheses: above ankle and below ankle.

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