Mastering Foot & Ankle Amputations: Lisfranc and Chopart Techniques

Welcome, fellows, to the operating theater. Today, we're tackling a complex and critical area of reconstructive orthopaedics: foot and ankle amputations, specifically focusing on the Lisfranc and Chopart levels. These procedures, while challenging, offer patients with extensive forefoot or midfoot pathology, particularly oncologic conditions, a chance at functional limb preservation. Our goal is always to achieve a wide oncologic margin while creating a durable, end-bearing stump that allows for maximal ambulation and prosthetic fit.

Understanding the Surgical Landscape: Anatomy and Biomechanics

Before we make any incision, a deep understanding of the foot's intricate anatomy and biomechanics is paramount.

The Transverse Tarsal (Chopart) Joint

The Chopart joint, also known as the transverse tarsal joint, is a compound articulation consisting of two distinct joints: the talonavicular joint medially and the calcaneocuboid joint laterally.
* Talonavicular Joint: This is a ball-and-socket type joint, crucial for hindfoot motion. The head of the talus articulates with the concavity of the navicular.
* Calcaneocuboid Joint: A saddle-shaped joint, less mobile than the talonavicular, but vital for midfoot stability.
* Ligamentous Support: Key stabilizers include the spring ligament (plantar calcaneonavicular), the bifurcate ligament (connecting calcaneus to navicular and cuboid), and the dorsal talonavicular and calcaneocuboid ligaments.
* Muscular Implications: An amputation at this level preserves the powerful plantarflexors, primarily the Achilles tendon complex, but sacrifices the dorsiflexors (tibialis anterior, extensor hallucis longus, extensor digitorum longus). This imbalance, if not addressed, invariably leads to an equinus contracture, where the foot is fixed in plantarflexion. This is a significant functional disadvantage and a key reason why the Chopart amputation historically had a poor reputation. Our technique today will directly address this.

The Tarsometatarsal (Lisfranc) Joint

The Lisfranc joint complex refers to the articulations between the tarsal bones (cuneiforms and cuboid) and the bases of the five metatarsals.
* Key Articulations: The medial cuneiform articulates with the first metatarsal, the intermediate cuneiform with the second, the lateral cuneiform with the third, and the cuboid with the fourth and fifth metatarsals.
* Stability: This joint is inherently stable due to its bony architecture and strong ligamentous support, particularly the Lisfranc ligament (interosseous ligament connecting the medial cuneiform to the base of the second metatarsal).
* Muscular Implications: A Lisfranc amputation preserves both the dorsiflexors and plantarflexors, making it a highly functional amputation level with minimal biomechanical imbalance.

Neurovascular Considerations

Meticulous attention to neurovascular structures is crucial to ensure flap viability and prevent painful neuromas.
* Dorsal Foot:
* Dorsalis Pedis Artery: A continuation of the anterior tibial artery, it runs over the dorsum of the foot, giving off the arcuate artery and deep plantar artery. Its terminal branch often enters the first dorsal interspace. Preservation of its contribution to the plantar arch is ideal for transmetatarsal amputations. For Lisfranc and Chopart, it will often need to be ligated.
* Deep Peroneal Nerve: Provides sensation to the first web space and motor innervation to the extensor digitorum brevis. Its cutaneous branches will be encountered dorsally.
* Superficial Peroneal Nerve: Supplies sensation to the dorsum of the foot (except the first web space). Its cutaneous branches will be encountered dorsally and laterally.
* Plantar Foot:
* Medial and Lateral Plantar Arteries: Branches of the posterior tibial artery, forming the deep plantar arch. These are vital for the plantar flap viability. Terminal branches will need ligation.
* Medial and Lateral Plantar Nerves: Branches of the tibial nerve, providing sensation and motor innervation to the intrinsic foot muscles. Terminal branches will be encountered.
* Posterior Tibial Tendon: Crucial for hindfoot stability and inversion. Its release is necessary for Chopart disarticulation.
* Flexor Hallucis Longus (FHL) and Flexor Digitorum Longus (FDL): These tendons will be divided during Chopart and Lisfranc amputations.

Preoperative Planning and Patient Positioning

Fellows, remember that surgical success begins long before the first incision. Careful preoperative evaluation is absolutely necessary.

Indications for Amputation

• Lisfranc Amputation: Indicated for extensive tumors involving the metatarsals, particularly those extending into the first and second interspaces or multiple metatarsals, where a transmetatarsal amputation is insufficient. Patients typically present with pain, a localized mass, and difficulty with weight-bearing.

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* FIG 2 A: Synovial sarcoma of the forefoot. Radiograph showing radiodensity surrounding the second metatarsal.
* Chopart Amputation: Considered for tumors extending to the tarsometatarsal joint with significant soft tissue involvement, where preservation of the entire foot is not possible. It preserves the talus and calcaneus, maintaining hindfoot height and allowing for an end-bearing residual limb.
*

Imaging and Staging Studies

• Plain Radiographs: AP, lateral, and oblique views of the foot are standard. If ankle involvement is suspected, AP and mortise views are also obtained. These provide initial bony detail and help identify expansile lesions.
• MRI: This is our gold standard for assessing tumor extent, especially soft tissue involvement and marrow changes within the metatarsals or tarsals. It's crucial for determining the precise level of amputation and ensuring adequate margins.
• CT Scan: Offers superior bony detail compared to MRI, particularly useful for complex osteolytic or sclerotic lesions, or for planning precise bone cuts.

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* FIG 4 C: Radiograph showing the typical expansile appearance of a unilateral calcaneal brace (UCB).
*

Patient Positioning and Setup

• Supine Position: The patient is placed supine on the operating table. Ensure adequate padding at pressure points.
• Thigh Tourniquet: A pneumatic thigh tourniquet is applied over generous padding (e.g., Webril) on the proximal thigh. This allows for a bloodless field, which is critical for identifying delicate neurovascular structures and achieving precise dissection. Tourniquet time must be carefully monitored.
• Hip Bump: A small bump or roll may be placed proximal to the ipsilateral sciatic notch. This subtly limits external rotation of the extremity during the procedure, keeping the foot in a more neutral alignment for easier access and consistent orientation.
• Fluoroscopy: While not always mandatory for every step, a C-arm should be readily available and draped sterilely. For Lisfranc and Chopart disarticulations, it can be invaluable to confirm joint lines and ensure complete resection, especially in cases of distorted anatomy due to tumor.

Intraoperative Execution: The Masterclass

Now, let's scrub in. We'll proceed systematically, focusing on the principles that apply to all these forefoot/midfoot amputations, then detailing the specifics for each.

General Principles for Foot Amputations

1. Tourniquet Inflation: Once prepped and draped, inflate the thigh tourniquet to the appropriate pressure.
2. Incision Planning: The goal is to remove the tumor with adequate margins while creating a well-padded, durable, and functional stump. The quality of the tissue for the flap is more important than its sheer quantity.
   • Long Plantar Flap: This is generally preferred. The plantar skin is thicker, more durable, and contains specialized fat columns designed for weight-bearing. It provides a robust, end-bearing stump. The dorsal incision is typically shorter, and the plantar incision is extended distally to create a longer flap.
   • Fishmouth Configuration: If there is significant plantar extension of the tumor, precluding a long plantar flap, a fishmouth configuration is necessary. This involves creating dorsal and plantar flaps of approximately equal length. The same principles of careful dissection and stump closure apply.
3. Neurovascular Management:
   • Nerves: Identify cutaneous nerve branches. Apply gentle traction distally, then sharply transect the nerve to allow it to retract proximally into healthier, softer tissue. This minimizes the risk of painful neuroma formation at the stump's end. Avoid crushing or cauterizing nerves.
   • Vessels: Identify and ligate major arterial and venous branches cleanly. Use fine ligatures. Excessive use of cautery to obtain hemostasis is discouraged, as it can compromise the vascularity of the plantar flap, leading to dysvascularity or necrosis.
4. Tendon Management:
   • Extensor Tendons: Place on stretch by flexing the forefoot. Sharply divide them at the level of the skin incision, allowing them to retract proximally.
   • Flexor Tendons: Place on stretch by dorsiflexing the forefoot. Sharply divide them, allowing them to retract proximally.
   • No Attempt to Suture Extensor to Flexor Tendons: This is generally not done in these types of amputations.
5. Bone Contouring: The bony edges of the residual stump must be smooth and beveled to prevent pressure points and skin breakdown.
6. Myodesis/Fascial Attachment: The plantar flap, comprising skin, subcutaneous tissue, and sometimes muscle, is brought up and securely attached (myodesed) to the residual bones, periosteum, or capsular structures. This provides critical padding and stability to the end-bearing stump.
7. Hemostasis and Drainage: After tourniquet deflation, meticulous hemostasis is achieved. A small Penrose drain is often placed deep to the flap and brought out through a separate stab incision, either medially or laterally, to prevent hematoma formation.
8. Wound Closure: Skin is closed with interrupted sutures, typically 4-0 nylon.

Transmetatarsal Amputation (TMA)

While our focus is Lisfranc and Chopart, the TMA is a foundational skill. Let's briefly review it as it shares many principles.

Step-by-Step Execution: Transmetatarsal Amputation

1. Incision: We begin with a transverse dorsal incision, typically at the middle or proximal third of the metatarsals, extending through skin and subcutaneous tissue. From this dorsal incision, we fashion a long plantar flap. This means extending the incision obliquely across the medial and lateral aspects of the foot, then transversely across the plantar skin, just proximal to the planned metatarsal osteotomies.

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* TECH FIG 1 A: Dorsal skin incision for transmetatarsal amputation.
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Lisfranc Amputation

Now, let's move to the Lisfranc amputation, which involves disarticulation at the tarsometatarsal joint level.

Step-by-Step Execution: Lisfranc Amputation

1. Incision: Similar to TMA, we start with a transverse dorsal incision, either at the middle or proximal third of the metatarsals, extending through skin and subcutaneous tissue. A long plantar flap is then fashioned by extending the incision approximately 45 degrees from the transverse dorsal incision obliquely across the medial and lateral foot to the level of the distal metatarsals, then transversely across the plantar aspect.

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* TECH FIG 1 C,D: Surgical technique for Lisfranc amputation. Skin incisions on the dorsal and plantar aspects of the foot. The plantar skin flap is longer. Dissection and removal of the metatarsals. Wound closure with sutures.
2. Neurovascular Management:
* Identify and sharply transect the cutaneous branches of the peroneal nerve dorsally, allowing proximal retraction.
* Ligate and divide the terminal branch of the dorsalis pedis artery as it enters the first dorsal interspace and courses in the plantar fascia.
* On the plantar aspect, identify the sensory nerve to the first ray and the terminal branches of the medial plantar nerve. Apply traction and sharply divide them.
* Ligate and divide the terminal branches of the medial plantar artery.
3. Tendon Management:
* Place the extensor tendons on stretch by flexing the forefoot, then sharply divide them at the incision level, allowing proximal retraction.
* Place the superficial and deep flexor tendons on stretch by dorsiflexing the forefoot through the Lisfranc joint, then sharply divide them, allowing proximal retraction.
4. Disarticulation: The Lisfranc joint is sharply disarticulated. This requires precise identification of the joint lines between the cuneiforms/cuboid and the metatarsal bases. Use a small scalpel to incise the dorsal, plantar, and interosseous ligaments. The Lisfranc ligament, connecting the medial cuneiform to the second metatarsal base, is particularly stout and requires complete division.
* Pearl: Maintain the foot in slight plantarflexion during disarticulation to open the dorsal aspect of the joint and facilitate ligamentous release.
5. Bone Contouring: The cuneiforms, which form the new distal end of the stump, should be contoured to a rounded, smooth end using a rasp or bone file. This prevents sharp edges from creating pressure points.
6. Stump Closure:
* Deflate the tourniquet and achieve meticulous hemostasis.
* Bring the plantar flap up and myodesed to the tarsal bones. Alternatively, the plantar fascia can be sewn into the periosteum overlying the capsular structures in and around the tarsal bones.
* Place a small drain.
* Close the skin with 4-0 nylon sutures.

Chopart Amputation

This is where we address the historical challenge of equinus contracture. The Chopart amputation is a transtarsal amputation that preserves the talus and calcaneus, maintaining hindfoot height.

Step-by-Step Execution: Chopart Amputation

1. Incision: The Chopart amputation is performed through a transverse incision that is dorsally based at or just distal to the talonavicular joint. A long plantar flap is critical here for a sturdy, end-bearing stump. The plantar incision extends distally to create this flap, similar to the Lisfranc technique.

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* TECH FIG 1 E: Surgical technique for Chopart amputation. Skin incisions with dorsal and plantar flaps.
2. Neurovascular Management:
* Identify the dorsalis pedis artery and its accompanying deep peroneal nerve. The dorsalis pedis artery is ligated and divided. The sensory nerve is placed on stretch and transected sharply, allowing it to retract proximally.
* On the plantar aspect, identify and manage the terminal branches of the medial and lateral plantar nerves and arteries as described previously.
3. Tendon Management:
* The extensor hallucis longus (EHL) and extensor digitorum longus (EDL) tendons are placed on stretch and sharply divided, allowing them to retract proximally.
* The posterior tibial tendon, flexor hallucis longus (FHL), and flexor digitorum longus (FDL) tendons are also divided and allowed to retract proximally. The posterior tibial tendon is often tagged for potential use in augmenting the dorsiflexion, though the tibialis anterior is the primary choice.
4. Disarticulation: The capsules of the talonavicular and calcaneocuboid joints are circumferentially divided. This requires careful dissection to ensure complete release of the midfoot from the hindfoot. The bifurcate ligament is a key structure that needs to be divided to fully disarticulate the calcaneocuboid joint.
5. Bone Contouring: The talus and calcaneus should be cut and contoured to fit a prosthesis. Use a rasp or bone file to smooth any sharp edges on the talar head and calcaneal anterior process.
6. The Critical Step: Tibialis Anterior Transfer to Prevent Equinus Contracture
* This is the most crucial step in a Chopart amputation to achieve a functional outcome. Without it, unopposed Achilles action will lead to equinus.
* Tendon Detachment: The tibialis anterior tendon is detached from its insertion on the medial cuneiform and base of the first metatarsal. Ensure you take a cuff of soft tissue, preferably periosteum, with the tendon to provide a robust attachment point.
* Talus Tunnel Creation: A drill hole is made through the neck and head of the talus. This tunnel should be drilled in an oblique fashion, typically from dorsolateral to plantar-medial. Start with a small pilot hole, then enlarge it with a cannulated drill or sequential reamers to accommodate the tendon.
* Warning: Drill under constant fluoroscopic guidance to prevent inadvertent damage to the talar dome articular cartilage or the subtalar joint. Ensure the tunnel is wide enough to pass the tendon without fraying.
* Tendon Routing: The tibialis anterior tendon is then routed through this bone tunnel.
* Tendon Fixation: The tendon is then secured as it exits through the tunnel. This can be achieved by:
* Sewing the tendon to itself (creating a loop).
* Suturing it to surrounding soft tissue or periosteum.
* Augmenting the repair with bone anchors placed near the dorsal opening of the tunnel. These anchors provide strong, immediate fixation.
* Crucial Positioning: During this repair, the residual foot (talus and calcaneus) must be maintained in maximal dorsiflexion. This pre-tensions the tibialis anterior, ensuring it effectively counteracts the plantarflexion pull of the Achilles.
*

REFERENCES

and the plantar surface is reduced significantly in a Chopart amputation.

1. Berke GM. Lower limb prosthetics. In: Coughlin MJ, Mann RA, Saltzman CL, eds. Surgery of the Foot and Ankle, 8th ed. Philadelphia: Mosby, 2007:1399–1422.

2. Chang BB, Bock DE, Jacobs RL, et al. Increased limb salvage by the use of unconventional foot amputations. J Vasc Surg 1994;19:341–349.

3. Chou LB, Malawer MM. Analysis of surgical treatment of 33 foot and ankle tumors. Foot Ankle Int 1994;15:175–181.

4. Dillon MP, Barker TM. Can partial foot prostheses effectively restore foot length? Prosthet Orthot Int 2006;30:17–23.

5. Garbalosa JC, Cavanagh PR, Wu G, et al. Foot function in diabetic patients after partial amputation. Foot Ankle Int 1996;17:43–48.

6. Greene WB, Cary JM. Partial foot amputations in children: a comparison of the several types with the Syme amputation. J Bone Joint Surg Am 1982;64A:438–443.

7. Hattrup SJ, Amadio PC, Sim FH, et al. Metastatic tumors of the foot and ankle.Foot Ankle 1988;8:243–247.

8. Heim M. A new orthotic device for Chopart amputees. Orthop Rev 1994;23:249–252.

9. Hirsch G, McBride ME, Murray DD, et al. Chopart prosthesis and semirigid foot orthosis in traumatic forefoot amputation: comparative gait analysis. Am J Phys Med Rehabil 1996;75:283–291.

10. Kirby EJ, Shereff MJ, Lewis MM. Soft-tissue tumors and tumor-like lesions of the foot: an analysis of eighty-three cases. J Bone Joint Surg Am 1989;71A:621–626.

11. Millstein SG, McCowan SA, Hunter GA. Traumatic partial foot amputations in adults: a long-term review. J Bone Joint Surg Br 1988; 70B:251–254.

12. Murari TM, Callaghan JJ, Berrey BH Jr, et al. Primary benign and malignant osseous neoplasms of the foot. Foot Ankle 1989;10:68–80.

13. Philbin TM, Leyes M, Sferra JJ, et al. Orthotic and prosthetic devices in partial foot amputations. Foot Ankle Clin 2001;6:215–228.

14. Roach JJ, Deutsch A, McFarlane DS. Resurrection of the amputations of Lisfranc and Chopart for diabetic gangrene. Arch Surg 1987; 122:931–934.

15. Seale KS, Lange TA, Monson D, et al. Soft tissue tumors of the foot and ankle. Foot Ankle 1988;9:19–27.

16. Sundberg SB, Carlson WO, Johnson KA. Metastatic lesions of the foot and ankle.Foot Ankle 1982;3:167–169.

17. Wetzel LH, Levine E. Soft-tissue tumors of the foot: value of MR imaging for specific diagnosis. AJR Am J Roentgenol 1990;155:1025–1030.

18. The Chopart procedure provides an excellent level of amputation for a patient with limited activities and goals. 1 The main advantage to this level is that little is lost between the distal end of the residual limb and the floor. This allows ease of ambulation without the need for a prosthetic device. 13

19. For persons requiring short trips to the bathroom in the middle of the night or stability for transfers, the Chopart level is perfect. Unfortunately, the lack of anatomic structure and minimal distance from the plantar surface to the floor makes the Chopart amputation a poor choice for the active amputee.

20. Ambulation is achieved with a foot spacer. For the Chopart stump, a clamshell type of prosthesis allows good weightbearing function and restores the effective foot length. 4

21. Generally, patients are able to ambulate 3 months after amputation using a simple shoe prosthesis. 14

22. Gait analysis shows that abnormality and asymmetry of ground-reaction forces were less with a greater preserved stump length. 9

COMPLICATIONS
- Wound healing complications are treated with local wound care, elevation, and non-weight bearing. Oral antibiotics may be indicated. If there is skin flap necrosis, débridement with a skin graft may be necessary. 2

• Superficial infection is often resolved with a short course of oral antibiotics.

• Deep infection may require immediate operative débridement of devitalized tissue. Parenteral antibiotics are important to treat this limb-threatening problem. At the time of the débridement, a bone culture should be ordered to help determine the appropriate antibiotic.

• Equinus contracture is most easily treated by prevention. However, stretching with a therapist may be helpful. Serial casting may be required to correct the deformity.