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Case Discussion: First Metatarsophalangeal Joint Replacement Conversion to a Fusion

Mrs W is a 77 year old lady who presented with a two year history of left great toe pain. She had undergone a left first metatarsophalangeal joint replacement seventeen years prior, and initially had a good outcome from this procedure. However, she had developed increasing pain in her great toe and had difficulty walking and playing golf. She had tried a Hoka runner and other stiff soled shoe but continued to struggle with pain. There were no symptoms or signs of infection around the prosthesis.

On examination, Mrs W had some mild shortening, but no deviation, of her left great toe. There was no evidence of infection and she has a well healed scar from her previous surgery. The first metatarsophalangeal joint was quite tender to palpation, particularly at the plantar aspect. Mobilising her left first metatarsophalangeal joint was moderately tender, but there is no crepitus and the joint itself is quite mobile. She has no metatarsalgia and no clawing of the lesser toes.

An x-ray and CT scan demonstrated loosening of the first metatarsophalangeal joint implant and a possible pathological fracture at the plantar aspect of the first metatarsal shaft (see below):

X-ray image of the foot

CT scan of the foot

Mrs W was struggling with pain, and given the loose implant and risk of further bone loss we decided to proceed with surgery. This involved removal of the implant, debridement of the bone and conversion to a fusion. Given the first toe was very short relative to the second toe secondary to bone loss from the replacement, further shortening of the toe may have resulted in significant metatarsalgia underneath the second metatarsal head.

We therefore used tricortical structural bone graft, harvested from the iliac crest of the ipsilateral pelvis, to lengthen the first metatarsal at the time of the fusion and prevent further shortening (see intra-operative x-rays below). There was no evidence of infection intra-operatively, but multiple samples were taken and sent for microscopy and culture, and no pathogen was grown.

Mrs W was non weight bearing for two weeks, then comfortably started heel weight bearing in a post-operative shoe until six weeks post-operatively. She had no complications from her iliac crest bone graft harvest site.

An x-ray was performed six weeks following her procedure that confirmed successful radiological and clinical fusion. She had some residual shortening of her first metatarsal, but no metatarsalgia and no pain. Ten months following her surgery she is pain free, returned to golf and, and apart from avoiding shoes with a heel, has no limitations to her footwear choices.

X-ray image of the foot

X-ray image of the foot

Key Learning Points:

  • First metatarsophalangeal joint replacements were a surgical treatment for arthritis of the first metatarsophalangeal joint. However, they have a high revision rate due to implant loosening and many orthopaedic surgeons would consider a fusion procedure to treat severe first metatarsophalangeal joint arthritis instead.

  • There is a risk of infection with any prosthesis, so patients presenting with pain and an implant in situ should undergo careful screening for infection including inflammatory markers if appropriate. Intra-operative samples should also be taken to exclude infection.

  • Residual shortening of the hallux can be a consequence of revision forefoot surgery, and can be addressed by utilising tricortical bone graft, commonly harvested from the iliac crest, distal femur or proximal tibia.

All cases and clinical photographs have been shared following discussion and written permission from the patient and/or guardian.


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