Wednesday, 14 November 2007

Morton's Neuroma (Interdigital Neuroma) and Ankle Instability

My ex-colleague referred a housewife in her forties with complaints of left forefoot pain since 4 months duration. The excruciating pain is worse while taking the first few steps after sitting or lying down. She got herself a pair of soft Japanese slippers at home to help her walk at home. Hence, she places her weight on her right lower limb and just drags the left lower limb (painful gait). Her back started to hurt when she needed to walk a while longer. She told me she had seen multiple surgeons (received 2 Corticosteroid injections with pain-relief lasting for 2 months), traditional medicine practitioners, massage therapists and general practitioners but the pain relief was inadequate and short-lived.

After probing a little more, she told me that it first started when she twisted her left ankle 4 months ago. She then visited a traditional chinese medicine practitioner who massaged her foot and ankle. Apparently her foot started hurting after the treatment.

Upon examination of her posture and gait, I found that she had overpronation and unstable ankle. Her anterotalofibular ligament was torn and she had poor muscle tone in her left lower limb due to disuse atrophy. She had tenderness between the 4th and 5th metatarsal heads (uncommon for Morton's Neuroma) and a positive squeeze test. She would probably need an Ultrasound scan (more economical than MRI) for definitive diagnoses.

Taping her medial longitudinal arch seem to reduce her pain. A further double ankle lock and lateral stirrups seemed to complete eliminate the pain. I was concerned that she had lost muscle power and tone since she was placing her weight on the opposite side. I left her with some NSAIDS and athletic tape after teaching her the technique but she would need at least 4 - 8 weeks rehabilitation to return her normal function.
We will look into getting her a suitable orthoses for her feet. She may not require Corticosteroid or Alcohol injections if symptoms subside with the use of corrective insoles. If conservative treatment fails after 3-6 months, surgical excision could be done.

Articles of interest:
Morton's Neuroma
Alcohol Injections under Ultrasound guidance
Investigations for Morton's Neuroma
Interventions for the treatment of Morton's neuroma (Cochrane Review)

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