First metatarsophalangeal joint implant arthroplasty reduces the first intermetatarsal angle similar to first metatarsophalangeal joint arthrodesis in short-term follow up

In the presence of hallux limitus/rigidus and an elevated 1–2 intermetatarsal angle (IMA), first metatarsophalangeal joint (MTPJ) arthrodesis (FUSION) is often chosen to simultaneously correct both issues; however, this procedure obliterates the first MTPJ function and can often shorten the first ray. Alternatively, the first MTPJ implant arthroplasty (IMPLANT) has the ability to preserve some motion at the joint and does not result in shortening. Despite its surgical utility in clinical restoration, there is a paucity of understanding surrounding the first MTPJ arthroplasty's effect on the IMA. To this end, we performed a retrospective cohort study comparing the changes in IMA in patients that received either a first MTPJ IMPLANT or first MTPJ FUSION at our institution between January 1, 2017 through December 31, 2021. Weightbearing AP films preoperatively and during the immediate (i.e., 4–8 weeks) postoperative period were used to evaluate changes in IMA. We identified 49 patients (20 IMPLANT, 29 FUSION). The IMA was reduced in patients that received FUSION (P < 0.0001) or IMPLANT (P < 0.0001). Surprisingly, we found that the amount of IMA reduction was similar in both groups. Therefore, we conclude that IMPLANT procedures reduce the IMA comparable to FUSION procedures during the immediate postoperative period. Moreover, the results of our work challenges the previous notions of adductor hallucis tendon involvement in IMA reduction in FUSION procedures.

Level of Clinical Evidence: IV, retrospective case series