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Case Discussion #19: 33 year old physiotherapist with a coalition and chronic ankle instability

Mr W is a 33 year old gentleman, who works full time as a musculoskeletal physiotherapist. He had an eight-year history of left foot pain following a plantarflexion injury. He had severe pain in the dorsolateral border of his foot at the time which partially resolved, but felt his foot had never quite been right. Mr W also had a history of recurrent ankle sprains since adolescence, but prior to the plantarflexion injury was able to control his ankle instability with non-operative measures. Post the injury, his ankle instability worsened and was more difficult to control. He also had ongoing pain when trying to run, and his foot was sore in the evenings after standing all day. He was able to play social basketball with his foot heavily strapped but really struggled to get through a game.


Mr W had tried non-operative measures for his foot pain including a steroid injection, orthotics, bracing, taping, strengthening and proprioception work.


Clinically, Mr W had a mild subtle cavovarus foot type bilaterally, which is unusual given the diagnosis of a coalition. He had some moderate calf wasting on the left side. He was able to perform a bilateral heel raise, and his hindfoot was mobile to standing heel raise, but was unable to perform a single leg heel raise due to pain. His ankle was non-tender to palpation of the talar domes, but his foot was very tender to direct palpation of the navicular tuberosity and the sinus tarsi. He had a full, symmetrical range of motion of his ankle. Interestingly, his subtalar joint was mobile (the subtalar joint is normally stiff if a coalition is present) however this may have been a reflection of his ankle instability rather that a mobile subtalar joint. There was no evidence of a coalition in his contralateral foot and his neurological examination was normal.


In addition to a complete rupture of the anterior talofibular ligament and the calcaneofibular ligament, an MRI scan demonstrated a fibrous calcaneonavicular coalition with florid bone oedema in the lateral navicular (see below).

A CT scan demonstrated a small amount of cystic change in the lateral navicular, consistent with a chronic stress reaction (see below).

Mr W had an unusual combination of chronic ankle instability and a fibrous calcaneonavicular coalition. It was difficult to work out what was driving his pain, as both a coalition and ankle instability can result in sinus tarsi pain.


The decision was therefore made to proceed with an excision of the coalition, combined with intra-operative clinical and radiological assessment under anaesthesia to assess for ankle instability and proceed with an ankle reconstruction if required.


The excision of coalition, including fat graft interposition, was performed successfully. He was then screened intra-operatively for ankle instability, which demonstrated radiological signs of instability with an increased talar tilt (see below) and clinically he had a markedly positive anterior drawer. A lateral ligament reconstruction was subsequently performed.



Mr W was non weight bearing for two weeks post-operatively to allow for wound healing, then commenced weight bearing in an ankle brace and started his rehabilitation as per our standard ankle reconstruction (our protocol is available here)


Three months following surgery, Mr W is progressing well. His foot pain has completely resolved and he is working on building the strength back in his ankle. He is progressing with his rehabilitation and will start open chain exercises and gradual return to sport drills in the coming weeks.


DISCUSSION

This is an interesting case in a young patient who had quite disabling pre-operative pain. It was difficult to determine whether the pain was coming from his coalition or ankle instability, and we were both concerned that simply excising the coalition with a concomitant ankle reconstruction may result in worsening of ankle instability due to increased subtalar mobility and/or ongoing pain. The decision to proceed with both coalition excision and ankle stabilisation simultaneously was complex due to the risk of over-operating and post-operative stiffness. Whilst the long-term results of his surgery is unknown at this stage, he is currently doing very well.

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