The metatarsosesamoid joint: An in vitro 3D quantitative assessment

•Our goal was to quantitatively define the excursion of the sesamoids.•Tibial sesamoid has greater longitudinal excursion.•The fibular sesamoid has greater lateral excursion.•Hallucal sesamoids appear to have differential tracking.•Of interest to those involved in design of hallux arthroplasty.

BackgroundThe anatomy of the first metatarsophalangeal (MTP) joint, particularly the metatarsosesamoid articulation, remains poorly understood. Our goal was to quantitatively define the excursion of the sesamoids.MethodsSeven cadavers were dissected to assess the articulating surfaces throughout a normal range of motion. The dissections were digitally reconstructed in various positions using a MicroScribe.ResultFor first MTP joint, excursion averaged 14.7 mm for the tibial sesamoid in the sagittal plane and 7.5 mm for the fibular sesamoid. The sesamoids also moved medially to laterally when the joint was dorsiflexed. For the maximally dorsiflexed joint, excursion averaged 2.8 mm for the tibial sesamoid and 3.5 mm for the fibular sesamoid.ConclusionHallucal sesamoids appear to have differential tracking: the tibial sesamoid has greater longitudinal excursion; the fibular sesamoid has greater lateral excursion. The anatomical data will interest those involved with the design of an effective hallux arthroplasty.