Metatarsals: Understanding Their Movements, Functions, and Common Issues

What are the movements of the metatarsals?

The metatarsals, five long bones in the midfoot, primarily exhibit limited gliding movements at their proximal tarsometatarsal and intermetatarsal joints, contributing to overall foot rigidity and flexibility, while their distal metatarsophalangeal joints allow for significant flexion, extension, abduction, and adduction of the toes, crucial for propulsion and balance.

Understanding the Metatarsals

The metatarsals are a group of five long bones located in the midfoot, positioned between the tarsal bones (ankle/hindfoot) and the phalanges (toes). Numbered I to V, starting from the medial (big toe) side, each metatarsal features a base (proximal end), a shaft (body), and a head (distal end). They form the essential framework of the forefoot, contributing significantly to the foot's arched structure and its ability to bear weight, absorb shock, and facilitate locomotion. While often perceived as a rigid structure, the foot's complex architecture allows for intricate, albeit sometimes subtle, movements at various joints involving the metatarsals.

The Joints of the Metatarsals

The movements attributed to the metatarsals occur at their articulations with adjacent bones. Understanding these specific joint complexes is key to comprehending metatarsal kinematics.

Tarsometatarsal (TMT) Joints (Lisfranc's Joint)

These are the articulations between the bases of the metatarsals and the distal row of tarsal bones (medial, intermediate, and lateral cuneiforms, and the cuboid). Functionally, the TMT joints are crucial for the foot's ability to adapt to uneven surfaces and transition between a flexible shock absorber and a rigid lever for propulsion.

• Movement Type: Primarily gliding and sliding movements.
• Degrees of Movement: The first TMT joint (medial cuneiform and 1st metatarsal) is the most mobile, allowing for a greater range of motion, particularly in dorsiflexion/plantarflexion and some abduction/adduction. This mobility is essential for maintaining ground contact and adapting to various terrains.
• The second through fifth TMT joints are progressively less mobile, with the second TMT joint being the most rigid, often described as the keystone of the transverse arch. Their movements are minimal, contributing to the overall pronation and supination of the midfoot as a functional unit rather than isolated metatarsal movements. These subtle movements help to lock and unlock the midfoot, providing stability when needed and flexibility for adaptation.

Intermetatarsal Joints

These are the articulations between the bases of adjacent metatarsals (e.g., between the 1st and 2nd metatarsal bases).

• Movement Type: Very limited gliding movements.
• Degrees of Movement: These joints primarily allow for slight relative motion between the metatarsal shafts, which helps in adjusting the transverse arch of the foot during weight-bearing and propulsion. This minimal movement aids in distributing load evenly across the forefoot.

Metatarsophalangeal (MTP) Joints

These are the articulations between the heads of the metatarsals and the bases of the proximal phalanges of the toes. These joints are the primary sites of significant movement involving the distal ends of the metatarsals.

• Flexion: Bending the toes downwards towards the sole of the foot.
• Extension: Lifting the toes upwards towards the shin. This is a critical movement, particularly for the first MTP joint, as it is essential for the push-off phase of gait.
• Abduction: Spreading the toes away from the midline of the foot (or second toe).
• Adduction: Bringing the toes closer together towards the midline of the foot (or second toe).

Functional Significance of Metatarsal Movements

The combined, intricate movements of the metatarsals are fundamental to the foot's multifaceted functions:

• Weight Bearing and Load Distribution: The subtle gliding at the TMT and intermetatarsal joints, along with the resilient arches, allows the foot to distribute body weight efficiently across the forefoot during standing and dynamic activities.
• Shock Absorption: The controlled flexibility at the TMT joints, particularly during initial ground contact, contributes to the foot's ability to absorb impact forces, protecting higher joints like the knee, hip, and spine.
• Propulsion (Push-off): Extension at the MTP joints, especially the great toe's (first MTP) extension, is crucial for generating forward momentum during walking, running, and jumping. The metatarsals act as a rigid lever during this phase.
• Adaptation to Uneven Surfaces: The slight movements at the TMT joints enable the midfoot to conform to irregular ground, maintaining stability and balance.
• Maintaining Foot Arches: The structural integrity and subtle movements of the metatarsals contribute to the dynamic maintenance of both the longitudinal and transverse arches of the foot, which are vital for both stability and flexibility.

Clinical Relevance and Common Issues

Dysfunction or injury affecting metatarsal movement can lead to various foot conditions, highlighting the importance of their proper function.

• Metatarsalgia: Pain in the ball of the foot, often due to excessive pressure or poor mechanics leading to inflammation around the metatarsal heads or MTP joints. Altered metatarsal movement patterns can exacerbate this.
• Lisfranc Injuries: Sprains, fractures, or dislocations of the TMT joints. These injuries are significant due to the critical role of these joints in midfoot stability and can severely impair foot function.
• Bunion Formation (Hallux Valgus): A deformity of the first MTP joint where the great toe deviates laterally (towards the other toes), and the first metatarsal head deviates medially. This alters the biomechanics of push-off and can cause pain and further deformities.
• Stress Fractures: Repetitive stress, often from high-impact activities or sudden increases in training volume, can lead to stress fractures of the metatarsal shafts, particularly the second and third metatarsals.
• Morton's Neuroma: Thickening of the tissue around the nerve leading to the toes, often between the third and fourth metatarsal heads, caused by compression and irritation. Impaired intermetatarsal mobility can contribute to nerve impingement.

Optimizing Metatarsal Health and Function

Maintaining healthy metatarsal movement is crucial for overall foot function and preventing injuries.

• Foot Strengthening Exercises: Incorporating exercises that target the intrinsic foot muscles can improve stability and control over metatarsal movements. Examples include toe spreads, toe curls, and short foot exercises.
• Proper Footwear Selection: Wearing shoes with adequate toe box space to allow for natural toe spread and MTP joint movement, appropriate arch support, and cushioning can significantly support metatarsal function.
• Mobility Drills: Gentle foot and ankle mobility exercises can help maintain the subtle gliding movements at the TMT and intermetatarsal joints, improving the foot's adaptability.
• Biomechanical Assessment: For individuals experiencing persistent foot pain or those involved in high-impact sports, a professional biomechanical assessment can identify specific movement dysfunctions or structural issues affecting the metatarsals, guiding targeted interventions.
• Gradual Training Progression: When engaging in activities that place significant stress on the feet, such as running or jumping, gradually increasing intensity and volume allows the metatarsals and surrounding tissues to adapt, reducing the risk of stress injuries.