Chopart Amputation (Transverse Tarsal Amputation)

Indication. A Chopart amputation is performed when the forefoot must be sacrificed but the hindfoot (talus and calcaneus) is viable, perfused and free of infection - the aim being to preserve a sensate, weight-bearing stump at the most distal level that will reliably heal. Absolute indications are severe irreparable forefoot trauma with a viable hindfoot; diabetic forefoot gangrene or osteomyelitis with intact hindfoot perfusion; a malignant forefoot tumour requiring negative margins; multiple failed ray amputations leaving a non-functional forefoot remnant; and chronic forefoot osteomyelitis unresponsive to medical and surgical management. Relative indications include severe Charcot forefoot deformity with irreparable midfoot collapse, a congenital forefoot deformity requiring reconstruction, extensive forefoot soft-tissue loss with exposed bone, and peripheral vascular disease where a more distal amputation would be inadequate. Contraindications are the conditions that make the hindfoot stump fail: inadequate perfusion (TcPO2 less than 30mmHg or ABI less than 0.5), active hindfoot infection or osteomyelitis, an ischaemic heel or Achilles region, severe PVD mandating a higher level, a non-ambulatory patient (a transtibial amputation fits a prosthesis better), and a psychiatric or cognitive inability to cooperate with prolonged rehabilitation. The level-selection decision. Once the forefoot is lost and the hindfoot is viable, the real choice is which hindfoot-preserving level gives this patient the best function. Each option trades stump length against prosthetic reliability:

Guidelines, registries and global practice. Across the IWGDF (International Working Group on the Diabetic Foot), AOFAS and BOA/BOAST limb-loss guidance the principle is the same: amputate at the most distal level that will reliably heal while delivering a functional, prosthetically fittable limb. There is no implant registry for amputation; the evidence is case series and systematic reviews. - Perfusion thresholds. Healing is unlikely with TcPO2 under 30mmHg or ABI under 0.5; many vascular units target TcPO2 over 40mmHg or toe pressure over 30mmHg at the proposed level before committing. Restore inflow first if marginal.

• Antibiotic prophylaxis. A first-generation cephalosporin (cefazolin 2g IV, 3g if over 120kg) within 60 minutes of incision is standard; add MRSA cover (vancomycin or teicoplanin) where colonisation or local prevalence is high. For established diabetic foot infection give culture-directed therapeutic antibiotics per IWGDF/IDSA rather than prophylaxis alone.
• Practice variation. In high-resource settings with ready prosthetics and vascular support, a balanced (modified) Chopart or a primary transtibial amputation are both reasonable; in lower-resource settings a heel-bearing midfoot stump or a Pirogoff/Syme stump that allows barefoot household ambulation without a prosthesis may be preferred. The level must match the patient's rehabilitation and prosthetic ecosystem. Consent specifically for wound breakdown or flap necrosis, an insensate stump if the plantar nerves are injured, progressive equinoVARUS deformity, phantom-limb pain, the high likelihood of long-term AFO or prosthesis use, and a 20 to 40 percent chance of revision to a higher level within five years. Setup. Supine with an ipsilateral hip bump (30 degrees internal rotation), thigh tourniquet (inflate to 250 to 300mmHg for the lower extremity), the foot off the end of the table or on a radiolucent support. Prep from tourniquet to toes. Fluoroscopy is helpful to mark the talonavicular and calcaneocuboid joints.

The goal: confirm perfusion, design a long plantar racquet flap, disarticulate cleanly through the talonavicular and calcaneocuboid joints while protecting the dorsalis pedis and the medial and lateral plantar neurovascular bundles, balance the tendons to prevent equinoVARUS, and close a tension-free, sensate flap over smooth bone with the foot splinted in neutral. The exposure - the racquet incision and the step-by-step protection of the plantar bundle - is laid out in full below; it is the heart of the operation.

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Rehabilitation | Phase | Timing | Immobilisation and wound | Milestone | |-------|--------|--------------------------|-----------| | Immediate | 0 to 2 weeks | Bulky padded dressing and posterior splint, foot at neutral, knee at 30 degrees flexion | Hospital 3 to 5 days, strict non-weight-bearing, drain out at 24 to 48 hours, PCA or epidural then oral analgesia, enoxaparin 40mg SC daily, glucose 6 to 10 mmol/L in diabetics | | Early | 2 to 6 weeks | Posterior splint in neutral, changed weekly to watch for equinus | Non-weight-bearing, sutures out at 3 to 4 weeks, serial casting if equinus develops, upper-body and transfer training | | Intermediate | 6 to 12 weeks | Custom AFO | Gradual weight-bearing from 6 to 8 weeks if healed, union check at 10 to 12 weeks if arthrodesis, prosthetic consultation, gait training | | Long-term | 3 months onward | AFO long-term in about 80 percent, plus prosthesis or shoe filler | Review 3-monthly then 6-monthly; monitor for equinus, skin breakdown and ulceration | Most patients return to household ambulation over several months; about 80 percent need a long-term AFO and 20 to 40 percent require revision to a higher level within five years. Red flags requiring urgent review: flap discoloration (dusky, blue or black), wound dehiscence with bone exposure, fever or systemic sepsis, progressive equinus deformity, new pressure ulceration, or uncontrolled pain. Complications

Complication rates from verified series: - Wound complications: failed wound healing about 46 percent after conventional (un-balanced) Chopart versus 28 percent after modified (balanced) Chopart in systematic review; up to 94 percent with any wound complication in a dysvascular diabetic case series.

• Revision to a higher level: about 28 percent in a large diabetic series (annual incidence 13 percent); up to 56 percent in high-risk diabetic cohorts.
• Successful prosthetic ambulation: about 44 percent in a dysvascular diabetic series; higher in selected ambulatory, balanced, well-perfused patients.
• Background mortality is high in the diabetic-dysvascular population (about 46 percent over about 3 years in one series) and is driven by comorbidity, not by the operation itself. Why a conventional Chopart has fallen out of favour. Many surgeons now prefer a balanced (modified) Chopart, a Pirogoff or Syme stump, or a primary transtibial amputation over an un-balanced Chopart because of the high equinoVARUS rate, the high wound-failure rate (up to about 46 percent conventional, halved by balancing), difficulty with prosthetic fitting and a short lever arm, frequent revision to a higher level, and patient-reported function that does not improve and stays below population norms. A Chopart is still indicated when the patient specifically refuses a higher amputation, when there are religious or cultural requirements for tissue preservation, or when the surgeon is highly experienced with the technique and its deformity-prevention strategies.

Five danger structures - know the location and the protection strategy for each:

Surgical anatomy. The transverse tarsal (Chopart) joint is formed by the talonavicular joint medially - a ball-and-socket joint that allows inversion and eversion - and the calcaneocuboid joint laterally - a modified saddle joint with more restricted motion. The two function together as the midtarsal joint complex; a Chopart amputation disarticulates through both while preserving an intact talus and calcaneus. The vascular supply to the flap comes from the medial and lateral plantar arteries (terminal branches of the posterior tibial), with the dorsalis pedis (the continuation of the anterior tibial, running between EHL and EDL) supplying the dorsal skin. The nerves that matter are the medial plantar nerve (sensation to the medial plantar weight-bearing skin - critical to preserve), the lateral plantar nerve (lateral plantar sensation and motor to the intrinsics, with calcaneal branches to the heel), the deep peroneal nerve (first web space sensation, motor to EDB) and the sural nerve (lateral border sensation). The central problem is muscle imbalance. With the forefoot gone, the insertions of the dorsiflexors and evertors are lost while the plantarflexors and invertors remain:

Key evidence. The systematic review by van der Wal (2023) showed that failed wound healing runs at about 46 percent after a conventional (un-balanced) Chopart but falls to about 28 percent after a modified (balanced) Chopart, with re-amputation to a higher level most frequent after the conventional procedure - and that modified Chopart allowed unprosthetised short-distance ambulation in 74 percent versus only 26 percent household ambulation after a conventional one. This is the quantitative basis for treating tendon balancing as integral to the operation, not optional. Brodell (2020), in a single-centre diabetic series, found that even with tendon transfers 94 percent developed a wound complication and 56 percent required revision, with only 44 percent ever ambulating with a prosthesis - a sobering reminder that in the dysvascular diabetic foot a primary transtibial amputation is often the better answer. The original rationale for balancing (Reyzelman and Armstrong, 1999) emphasised that the residual deformity is equinoVARUS, not pure equinus, and that eliminating the cuboid can paradoxically reduce varus. Faglia (2015) and Schade (2010) underline that in the dysvascular diabetic population the operation is a last-chance limb-salvage step with a high revision rate and very high background mortality, and that no single balancing or arthrodesis technique is proven superior - so the choice is individualised to soft-tissue quality and surgeon experience.

Further reading: 1. Berger LE, Spoer DL, Huffman SS, et al. A comparative analysis of functional and patient-reported outcomes following Lisfranc and Chopart amputations in high-risk limb salvage patients. J Foot Ankle Surg. 2023;62(6):933-938. doi:10.1053/j.jfas.2023.04.014 (PMID 37160203) 2. Chiu YC, Chung TC, Wu CH, et al. Chopart amputation with tibiotalocalcaneal arthrodesis and free flap reconstruction for severe foot crush injury. Bone Joint J. 2018;100-B(10):1359-1363. doi:10.1302/0301-620X.100B10.BJJ-2018-0118.R1 (PMID 30295529) 3. DeGere MW, Grady JF. A modification of Chopart's amputation with ankle and subtalar arthrodesis by using an intramedullary nail. J Foot Ankle Surg. 2005;44(4):281-286. doi:10.1053/j.jfas.2005.04.014 (PMID 16012435) 4. Pinzur MS, Stuck RM, Sage R, Hunt N, Rabinovich Z. Syme ankle disarticulation in patients with diabetes. J Bone Joint Surg Am. 2003;85(9):1667-1672. doi:10.2106/00004623-200309000-00002 5. Sanders LJ, Dunlap G. Transmetatarsal amputation. A successful approach to limb salvage. J Am Podiatr Med Assoc. 1992;82(3):129-135. doi:10.7547/87507315-82-3-129 6. Dillon MP, Fatone S. Deliberations about the functional benefits and complications of partial foot amputation: do we know the full story? Med Hypotheses. 2013;81(4):754-761. doi:10.1016/j.mehy.2013.07.037 7. Early JS, Hansen ST. Surgical reconstruction of the diabetic foot: a salvage approach for midfoot collapse. Foot Ankle Int. 1996;17(6):325-330. doi:10.1177/107110079601700604 8. Harris WR. The classic: Syme's amputation: the technical details essential for success by Austen Harris. Clin Orthop Relat Res. 2012;470(4):947-950. doi:10.1007/s11999-011-2195-6