Percutaneous Distal Metatarsal Osteotomy for Morton Neuroma

Alirio J. deMeireles

Ettore Vulcano

♦ INTRODUCTION

Morton neuroma is a compression neuropathy of an interdigital nerve, entrapped by the deep transverse intermetatarsal ligament at roughly the level of the metatarsal heads. The disease frequently affects the third web space and is most commonly found in middle-aged females, where it presents as pain at the plantar surface of the affected web space and is worse with weight bearing or palpation.¹,²,³,⁴

Initially, Morton neuroma is treated conservatively with a combination of wide toe box shoes, orthoses, and/or nonsteroidal anti-inflammatory drugs, although these methods are rarely curative. Efficacy and longevity of these noninvasive methods are varied—with temporary improvement of symptoms in 28% to 80% of patients.⁵,⁶,⁷,⁸ Corticosteroid injections are also utilized as a nonoperative treatment option though the authors do not frequently recommend these to the patients due to concern regarding inconvenient side effects such as fat pad atrophy, skin necrosis, long-lasting injection site pain, ligament tear, etc.

♦ SURGICAL TREATMENTS

If symptoms persist after exhaustion of nonoperative modalities, more invasive methods, including chemical neurolysis and the surgical neurectomy, are considered.⁹,¹⁰ While satisfactory results have been reported, both of these approaches have demonstrated several limitations. Current literature regarding percutaneous chemical neurolysis has demonstrated a wide range of efficacy, with complete resolution of symptoms in 21% to 84% of cases.⁷,¹¹,¹² In contrast, neurectomy successfully treats the symptoms in 70% to 90% of cases but has a higher complication rate as compared to the relatively low morbidity of neurolysis.¹³,¹⁴,¹⁵ The most common complications of neurectomy include impaired wound healing, sensory deficits, and traumatic amputation of the neuroma.¹⁰ Thus, given the varied efficacy of chemical neurolysis and the potential morbidity of neurectomy, the development of an effective, minimally invasive procedure to treat Morton neuroma with an equal or lower complication rate would be clinically impactful.

Distal Metatarsal Osteotomy

de Prado et al. described a percutaneous distal metatarsal extraarticular osteotomy of lesser metatarsals (DMMO) for the treatment of Morton neuroma.¹⁶,¹⁷ The premise of this technique is to spare the nerve by dorsalizing and shortening the third and fourth metatarsal heads.¹⁶,¹⁷ The authors have developed a modification of the de Prado technique, which relies on release of the deep transverse intermetatarsal ligament coupled with a DMMO of the fourth metatarsal, leading to widening of the third web space with decompression of the interdigital nerve.

The objective of this chapter is to describe the basic indications, recommended workup, and in-depth surgical technique for the novel operative intervention for the treatment of Morton neuroma.

♦ INDICATIONS AND CONTRAINDICATIONS

Any patient with a diagnosis of a third web space neuroma who has failed 3 months of nonoperative treatment is a candidate for the procedure. Nonoperative treatments consist of metatarsal pads and wide toe box shoes as described in the Introduction section. Injections of any sort, with the exception of diagnostic lidocaine injections, are not recommended by the authors as they are unlikely to treat the condition and might have inconvenient side effects such as fat pad atrophy, skin necrosis, long-lasting injection site pain, ligament tear, etc.

Contraindications include stump neuromas resulting from a previous neurectomy, active forefoot infections, neuropathy, chronic regional pain syndrome, and recent injections (<3 months) in the affected area.

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