Recurrent subchondral cyst in medial malleolus

Osteochondral Defects

Description of patient (type of occupation, indication of age, intensity of sport):

35 year old patient, male, normal weight, no extraordinary sporting activities.

History and previous treatment:

Right ankle pain started 2017 without any trauma. Patient has deep ankle pain.
An intraocceal cyst was found in the right medial malleolus (1,3 cm) with reactive oedema. The CT showed a connection to the joint.
Beginning of 2018: operative abrasion of the cyst + autograft bone transplantion from Gerdy’s tubercle
Fall 2018: the pain renewed slightly and the CT shows a partly ossified cyst with a connection to the joint.
Beginning 2019: the MRI shows a renewed cyst with oedema, pain grows worse.
Spring 2019: anterior arthroscopy, debridement of synovial hypertrophy and microfracture of the suspected canal to the cyst (visualisation of the exact location of the canal was unsure).

Current complaints:

Pain during prolonged gait anteromedially of the ankle. The patient is able to work but pain grows worse during the day. He cannot run due to the pain.
The patient can fully weight bear and walks without crutches. The ankle is a bit stiffer then the left foot, dorsiflexion slightly decreased, plantarflexion is symmetric. "Deep" ankle pain during passive motion. No signs of infection.

The 2018 CT shows a renewed, partly ossified cyst with a connection to the joint (see picture)
The 2019 MRI shows a cyst, which has renewed to prior dimensions (see picture)

Physical examination:

No specific findings. No recognizable pain on palpation

Images:

Other remarks:

The patient is prone to getting neuropathic pain after surgery. This pain has worn off each time but is in risk to renew if surgery is repeated.

Case summary:

Recurrent OCL + cyst of medial malleolus with worsening of deep ankle pain. Conservative treatment with physiotherapy has been tried with little effect. The physiotherapist called me and told me the pain lessens after a physiotherapy session but then recurs after prolonged gait.

Question(s) to this case:

Is a reoperation with abrasion of the cyst and new bone transplantion feasable? Any other treatment options?

Expert:

This is a typical case of cystic lesion arising from the area between medial malleolus and tibial plafond. This cyst always has a connection with the anklejoint and the opening with channel to the cyst is always present. First line treatment is retrograde drilling under arthroscopic control and filling the cyst after curretting and destroying the channel (to prevent recurrence).
This is not always succesfull and the cyst might return (which is the case in your patient). In case of recurrence my advice is to perform a medial malleolar osteotomy straight through the cyst. (Preop planning is important). Curretage and destroy the walls and microfracture the walls. Fill with cancellous bone and fix the osteotomy with the predrilled screws. This in my experience is the most safe and reliable solution.

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