Tarsometatarsal Joints, Anatomical Structure, Kinematic Considerations, Biomechanical Coupling and Functional Adaptation

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Tarsometatarsal Joints

The tarsometatarsal joints hold historical significance, particularly due to the work of Jacques Lisfranc, a renowned surgeon in Napoleon's army who extensively described amputation procedures involving this region. As a result, these joints are commonly referred to as Lisfranc's joints. Anatomically, this complex is a crucial structure forming the boundary between the midfoot and forefoot, consisting of five distinct joints.

Anatomical Structure

The tarsometatarsal joints create precise articulations between the bases of the metatarsal bones and the tarsal bones, specifically the three cuneiforms and the cuboid. Each metatarsal bone pairs with a specific tarsal bone as follows:

  • The first metatarsal articulates with the medial cuneiform.
  • The second metatarsal articulates with the intermediate cuneiform.
  • The third metatarsal articulates with the lateral cuneiform.
  • The fourth and fifth metatarsals articulate with the distal surface of the cuboid.

The joint surfaces exhibit distinctive characteristics—most are flat, but the medial two joint surfaces show slight irregular curvature. The stability of this intricate joint system is reinforced by three primary ligamentous structures:

  1. Dorsal ligaments
  2. Plantar ligaments
  3. Interosseous ligaments

A notable feature is that only the first tarsometatarsal joint possesses a fully developed joint capsule.

Kinematic Considerations

The tarsometatarsal joints function as base joints for the forefoot, playing a vital biomechanical role. One of their most significant structural aspects is the interlocking wedge-like configuration of the second metatarsal base between the medial and lateral cuneiforms, which severely restricts mobility at the second and third tarsometatarsal joints. This rigid structural arrangement resembles the second and third finger joints of the hand, allowing the second and third metatarsal rays to provide longitudinal stability to the entire foot. Such structural stability is particularly crucial in the late stance phase of gait, preparing the forefoot for push-off.

In terms of mobility, the first, fourth, and fifth tarsometatarsal joints exhibit the greatest range of motion, with the first joint displaying the most pronounced mobility. Movements of the first metatarsal joint occur primarily in the sagittal plane, with approximately 10° of motion. Other planes of motion are relatively restricted.

During early to mid-stance, the first tarsometatarsal joint dorsiflexes by about 5°, influenced by two opposing forces:

  1. A downward force from body weight compressing the cuneiform region
  2. An upward ground reaction force acting on the distal end of the first metatarsal

This controlled dorsiflexion of the first metatarsal is closely linked to the gradual flattening of the medial transverse arch, which helps distribute and absorb loading stress effectively.

During the late stance (push-off) phase, the first tarsometatarsal joint rapidly plantarflexes by approximately 5°, primarily controlled by the contraction of the fibularis longus muscle. This plantarflexion of the first metatarsal ray subtly shortens the medial column, promoting elevation of the medial longitudinal arch. This stabilization mechanism is crucial for accommodating the increased loads experienced by the midfoot and forefoot during the later stages of the gait cycle.

Biomechanical Coupling and Functional Adaptation

Although research on the first tarsometatarsal joint remains ongoing, numerous studies have described kinematic coupling phenomena between different planes of movement. One particularly significant observation is that plantarflexion of the joint is often accompanied by slight eversion, whereas dorsiflexion is accompanied by slight inversion. These movement patterns are readily observed in non-weight-bearing conditions but do not align perfectly with traditional definitions of pronation and supination, leading some to categorize them as atypical movements.

Despite this classification, these unique movement patterns offer functional advantages. For example, the combined motion of plantarflexion and eversion allows the medial foot column to adapt more effectively to uneven terrain. This pattern resembles the thumb’s movement when gripping a large spherical object, highlighting its biomechanical significance.

Despite advances in research, the precise functional integration of these movement patterns within overall foot kinematics during gait remains incompletely understood. Further studies are needed to clarify their role in dynamic foot stability and propulsion.