Webspace Approach for Morton's Neuroma (Dorsal and Plantar)

What the approach exposes. The webspace approach gives direct surgical access to the common digital nerve and its bifurcation in an intermetatarsal space, for excision or decompression of a Morton's neuroma. The dorsal longitudinal webspace incision is the international workhorse; the plantar transverse web-sulcus incision is reserved for when direct or more proximal access is preferred. No other exposure gives equivalent access to the common digital nerve and its bifurcation into the proper digital nerves. Why operate through the webspace. Morton's neuroma is a region of degenerative perineural fibrosis of the common digital nerve as it passes in the intermetatarsal space, deep to (plantar to) the deep transverse intermetatarsal ligament. The pathological nerve is accessed most directly through the webspace it occupies, from either surface. Entrapment of the thickened nerve beneath the unyielding ligament, against the metatarsal heads, is central to the prevailing pathomechanics. Why the third webspace. The third webspace common digital nerve receives contributions from both the medial plantar nerve (the third common plantar digital branch) and the lateral plantar nerve. This makes it the thickest of the common digital nerves and the least mobile, and therefore the most vulnerable to compression - the anatomical explanation for the third webspace being the most frequently affected. Morton's neuroma shows a strong female predominance and typically presents in middle age. ### Indications Primary indication: Recalcitrant interdigital (Morton's) neuroma that has failed an adequate trial of non-operative management (typically three to six months), with a confirmed diagnosis and excluded differentials. Non-operative regimen that must be exhausted first: - Wide, deep toe-box footwear with a stiff or rocker sole

• Metatarsal dome or pad placed proximal to the tender webspace to splay the metatarsal heads
• Activity modification and weight optimisation
• Ultrasound-guided corticosteroid injection (repeat once if partially successful)
• Consider alcohol (sclerosing) injection in selected patients Contraindications: - Failure to exclude a differential diagnosis - the most important contraindication. Never operate on an unconfirmed diagnosis
• Active local infection or a compromised soft-tissue envelope
• Severe peripheral vascular disease or digital ischaemia
• Untreated peripheral neuropathy or complex regional pain syndrome
• Significant forefoot deformity (for example severe hallux valgus or hammer toes) that should be addressed first, as it may be the true driver of symptoms Differential diagnosis that must be excluded before offering surgery: - Metatarsal stress fracture (and metatarsal neck stress fracture)
• Freiberg's infraction (avascular necrosis of the metatarsal head)
• Metatarsophalangeal joint synovitis, including inflammatory arthritis, gout and rheumatoid disease
• Intermetatarsal bursitis (a close imaging mimic)
• Tarsal tunnel syndrome
• Lumbar radiculopathy
• Peripheral neuropathy or peripheral vascular disease

Approach Variants

Webspace distribution of disease: - Third webspace: most commonly affected (combined medial and lateral plantar nerve contribution)

• Second webspace: second most common
• Fourth and first webspaces: uncommon
• Multiple webspaces or bilateral: possible; operate one at a time, planned separately

Alternative procedures: - Decompression or neurolysis (Gauthier technique) - division of the deep transverse intermetatarsal ligament with the nerve preserved, suitable for early or moderate disease

• Alcohol sclerosing injection - a non-surgical option for patients unfit for or declining surgery
• Cryotherapy or radiofrequency ablation - emerging minimally-invasive options in selected centres

Work down through the dorsal webspace in layers, splitting the intermetatarsal interval bluntly down to the deep transverse intermetatarsal ligament, dividing that ligament to deliver the plantar nerve, then resecting the nerve as far proximally as the exposure allows. A bloodless field under tourniquet is essential throughout.

Position, Landmarks and Incision Planning

Position. Supine with a sandbag or bump under the ipsilateral buttock to control external rotation and bring the forefoot into a neutral position, the foot at the distal edge of the table so the assistant can reach the plantar surface. Exsanguinate the limb and inflate a thigh or calf tourniquet for a bloodless field - critical for identifying the small nerve and vessels. For the plantar approach, supine with the knee well flexed and the hip externally rotated, or a lateral position, exposes the plantar webspace. Palpable landmarks. The relevant pair of metatarsal heads (most commonly the third and fourth), the tender webspace sulcus between them, the distal web crease, and the weight-bearing plantar skin that a dorsal incision must avoid. Confirm the marked side and webspace with the patient awake, and document toe capillary refill before exsanguination. Clinical examination landmark - Mulder's sign. One hand squeezes the metatarsal heads medially-to-laterally while a thumb of the other hand presses the webspace dorsally-to-plantarly; a palpable or audible click with reproduction of symptoms is supportive but not pathognomonic. Dorsal incision. A longitudinal incision in the affected webspace, centred between the two metatarsal heads, starting just proximal to the web crease and extending proximally for approximately three centimetres, lying entirely on non-weight-bearing dorsal skin. Plantar incision. A transverse incision in the web sulcus or web crease (the non-weight-bearing skin between the metatarsal heads) - the key to avoiding a painful weight-bearing scar - about two to three centimetres long and parallel to the web crease.

Neurovascular Anatomy of the Webspace

Structures at Risk

Managing an intra-operative vascular injury. If the common digital artery is divided, coagulate or ligate selectively, reassess toe capillary refill after tourniquet release, and document the finding. Concerning ischaemia is rare from a single digital artery but must be recognised. ### Extensile Options - Proximal extension - the dorsal incision can be extended proximally along the line of the metatarsal to resect the nerve more proximally; this is the most useful extension, because a more proximal resection lowers the risk of a stump neuroma. For the plantar approach, the transverse web-sulcus incision can be converted to a short longitudinal plantar extension if more proximal access is needed.

• Multiple neuromas - use a separate incision for each affected webspace and preserve an adequate skin bridge between incisions to avoid necrosis. Staged assessment of which webspace is truly symptomatic is wise before operating on two webspaces in one foot.
• Revision surgery for stump neuroma - prefer a plantar approach for revision, as it gives direct access and allows a more proximal resection of the stump; identify the cut nerve end, resect back to healthy nerve and bury the stump in soft tissue or muscle.
• Decompression (Gauthier) variant - instead of resecting the nerve, divide the deep transverse intermetatarsal ligament and leave the nerve intact (neurolysis); suited to early disease and patients who wish to avoid permanent numbness, accepting a higher recurrence rate. ### Complications

Outcomes

Good prognostic factors: a confirmed clinical diagnosis with excluded differentials; a single, clearly symptomatic webspace; a clear transient response to a diagnostic injection; an adequate proximal nerve resection; and appropriate patient expectations (numbness accepted). Poor prognostic factors: diagnostic uncertainty or coexisting forefoot pathology; multiple webspaces or bilateral symptoms; inadequate proximal resection (stump neuroma); a compensation or litigation context; and unrealistic expectations or marked psychological overlay. Recurrent or persistent pain - reassess first: re-evaluate the diagnosis (wrong diagnosis is the commonest reason for persistent symptoms); image to look for a stump neuroma, intermetatarsal bursitis or a missed second neuroma; and use a diagnostic injection to clarify whether the webspace is the true source. Revision surgery is reserved for a confirmed stump neuroma with a positive Tinel, through a plantar approach for more proximal access, with the stump buried in soft tissue - counsel that revision outcomes are less predictable than primary surgery.

• Morton's neuroma excision (neurectomy) - excision of the neuroma with proximal and distal nerve resection (the standard operation).
• Neurolysis or decompression (Gauthier) - division of the deep transverse intermetatarsal ligament with the nerve preserved.
• Stump neuroma revision - resection of a recurrent neuroma, usually via a plantar approach for more proximal access, with burial of the stump.
• Nerve biopsy - rare, when histological confirmation of an atypical lesion is required. ### Post-operative Care Immediate: - Bulky compression dressing and a stiff-soled postoperative shoe.
• Elevation for the first 48 hours.
• Neurovascular observation of the toes (capillary refill, sensation).
• Analgesia and DVT prophylaxis as appropriate. Weight-bearing and wound care: - Dorsal approach: weight-bearing as tolerated in a postoperative shoe from the outset.
• Plantar approach: non-weight-bearing or heel-walking for two to three weeks to protect the scar.
• Suture removal at 10 to 14 days.
• Gradual return to normal footwear over four to six weeks. Rehabilitation: - Gentle toe and ankle range-of-motion as comfort allows.
• Return to wider, accommodative footwear.
• Activity guided by symptoms; full recovery typically six to eight weeks.

At a Glance The

webspace approach exposes the common digital nerve for excision or decompression of a Morton's neuroma. Morton's neuroma is degenerative perineural fibrosis, not a tumour, most often in the third webspace because the common digital nerve there receives branches from both the medial and lateral plantar nerves, making it the thickest and least mobile. Surgery follows an adequate non-operative trial and exclusion of mimics. The dorsal longitudinal webspace incision is the workhorse: its scar is off the weight-bearing skin and recovery is quick, but dissection is deeper and the deep transverse intermetatarsal ligament must be divided to deliver the nerve, which lies plantar to it. The plantar transverse web-sulcus incision gives direct access and a more proximal resection, at the cost of a plantar scar. The defining technical principle is to resect the nerve as far proximally as possible, because an inadequate proximal resection is the commonest cause of a painful stump or recurrent neuroma. The common digital artery travels with the nerve and must be protected. ### Core Examination Questions

Mnemonics

Guidelines, Registries and Global Practice

Morton's neuroma is managed worldwide with broadly convergent principles across examination systems. Non-operative management (accommodative footwear, metatarsal pad, corticosteroid injection) is first line everywhere; surgical excision is reserved for recalcitrant, confirmed cases. The dorsal webspace approach is the international default, with the plantar approach reserved for selected cases and revision. Side-by-side principles (where guidance converges): | Body | Position on Morton's neuroma | |------|------------------------------| | AAOS and orthopaedic foot-and-ankle consensus | Confirm clinically, support with ultrasound or MRI, exhaust non-operative care, then offer excision through a dorsal or plantar webspace approach; exclude mimics | | BOA, BOAST and EFORT | Stepwise non-operative to operative management; careful patient selection; inform patients that some symptoms may persist | | International foot-and-ankle societies | The deep transverse intermetatarsal ligament is divided in the dorsal approach; adequate proximal resection is emphasised to avoid stump neuroma | Population evidence: - Morton's neuroma shows a strong female predominance and typically presents in middle age.

• The third webspace is the most commonly affected, consistent with the dual medial and lateral plantar nerve contribution to that interdigital nerve. Global practice variation: In high-resource settings, ultrasound-guided injection and MRI are routine adjuncts and both dorsal and plantar approaches are widely taught. In resource-limited settings, the diagnosis remains primarily clinical and the dorsal excision is the standard, lowest-morbidity operation. Alcohol sclerosing injections and decompression (neurolysis) are used variably by preference and resource availability. Consent (globally applicable): discuss expected webspace numbness (the nerve is sacrificed), recurrence or stump neuroma, persistent symptoms if the diagnosis is incorrect, infection, painful plantar scar (plantar approach), and the small risk to the common digital artery and digit perfusion.