What are the steps and instruments used for a great toe disarticulation?

Great Toe Disarticulation Surgery: Surgical Steps and Instrumentation

Great toe disarticulation involves surgical separation at the metatarsophalangeal (MTP) joint through systematic soft tissue release, joint exposure, capsular incision, and complete removal of the proximal phalanx while preserving the metatarsal head. This procedure is considered when non-surgical offloading treatment fails for neuropathic hallux ulcers, particularly in diabetic patients 1.

Preoperative Assessment

Critical vascular evaluation must be performed before proceeding, as inadequate perfusion will compromise healing and increase amputation risk 1:

• Palpate dorsalis pedis and posterior tibial pulses - if both are palpable, arterial supply is generally adequate 1
• Measure ankle-brachial index (ABI) - values <0.5 or ankle pressure <50 mmHg require urgent vascular imaging and revascularization consideration before surgery 1
• Assess toe pressure - should be >30 mmHg; if lower, revascularization should be considered 1
• Evaluate for infection severity - moderate to severe infections require urgent surgical intervention 1

Surgical Steps

1. Incision and Exposure

Make a dorsal longitudinal incision centered over the first MTP joint, extending from the metatarsal neck to the base of the proximal phalanx 2. This provides superior exposure compared to alternative approaches, though scar contracture is a potential complication 3.

2. Soft Tissue Dissection

• Perform a transverse extensor hallucis longus tenotomy to expose the joint capsule 4, 3
• Incise the joint capsule transversely at the level of the MTP joint 4
• Carefully protect neurovascular bundles during dissection - these run along the medial and lateral aspects of the toe 1, 4

3. Collateral Ligament Release

Release the medial and collateral ligaments from their attachments to allow complete joint exposure and mobilization 4, 3. This step is critical for adequate visualization and prevents inadvertent neurovascular injury.

4. Joint Disarticulation

• Disarticulate the MTP joint by separating the base of the proximal phalanx from the metatarsal head 1
• Remove the entire proximal phalanx including all phalangeal bones of the great toe 1
• Preserve the metatarsal head - do not resect unless there is osteomyelitis with progressive bone destruction or bone protruding through the ulcer 1

5. Debridement and Specimen Collection

Debride all necrotic tissue, infected bone, and surrounding callus using sharp dissection 1. This is essential for:

• Reducing bacterial load and removing colonizing organisms 1
• Obtaining tissue specimens for culture and histopathology 1
• Examining for deep tissue involvement and assessing extent of infection 1

Obtain bone specimens at the time of surgery for culture and histopathology analysis - if margins are culture-negative, antibiotic duration can be reduced from weeks to days 1.

6. Wound Assessment and Closure

• Use a sterile, blunt metal probe to assess for residual deep infection, abscess cavities, or communication with other compartments 1, 5
• Measure and document wound dimensions (length, width, depth) to establish baseline for healing assessment 1, 5
• Close the wound primarily if there is no infection and adequate soft tissue coverage 1
• Leave the wound open for delayed closure if there is moderate to severe infection or inadequate soft tissue 1

Surgical Instruments Required

Essential Instruments

• #15 or #10 scalpel blade - for skin incision and soft tissue dissection 1
• Small bone rongeur - for bone resection if needed 4, 3
• Sterile, blunt metal probe - for wound depth assessment and detection of bone involvement 1, 5
• Small periosteal elevator - for soft tissue dissection and capsular elevation
• Curved Mayo scissors - for capsular incision and soft tissue release
• Small bone-cutting forceps - for removing small bone fragments
• Adson forceps with teeth - for tissue handling
• Needle holder - for wound closure if indicated

Optional Advanced Instruments

• Sagittal saw or osteotomes - if metatarsal head resection is required for osteomyelitis 1, 3
• High-resolution ultrasound - for detecting deep soft tissue abscesses preoperatively 1

Postoperative Management

Combine surgical intervention with appropriate offloading devices to promote and sustain healing 1. The IWGDF recommends:

• Non-removable knee-high offloading device as first-line treatment for postoperative wound healing 1
• Removable offloading device if non-removable is contraindicated or if there is moderate infection/ischemia 1
• Appropriate antibiotic therapy - adjust based on culture results and clinical response 1

Critical Pitfalls to Avoid

Vascular compromise is the most serious complication - always ensure adequate perfusion before proceeding 1, 3. If ABI <0.5 or severe ischemia is present, address vascular insufficiency first through revascularization 1.

Inadequate debridement leads to treatment failure - remove all necrotic tissue and infected bone, even if this enlarges the wound 1. Patients should be forewarned that bleeding is likely and the wound will be larger after debridement 1.

Failure to obtain proper specimens compromises antibiotic selection - always obtain tissue samples rather than superficial swabs, as these provide more accurate culture results 1.

Neurovascular injury during dissection - meticulously protect the neurovascular bundles that run along the medial and lateral aspects of the toe 1, 4, 3.