Midtarsal Joint Subluxation: Anatomy, Causes, Symptoms, and Treatment

What is a Subluxation of the Midtarsal Joint?

A subluxation of the midtarsal joint refers to a partial dislocation or misalignment within the complex joint system located in the middle of the foot, leading to instability, pain, and compromised foot mechanics.

Introduction to the Midtarsal Joint (Anatomy & Function)

The midtarsal joint, also known as the Chopart's joint, is a critical functional unit in the foot, positioned between the hindfoot (talus and calcaneus) and the forefoot (metatarsals and phalanges). It is comprised of two distinct articulations:

• Talonavicular Joint: Formed by the head of the talus articulating with the navicular bone.
• Calcaneocuboid Joint: Formed by the anterior aspect of the calcaneus articulating with the cuboid bone.

These joints, along with their intricate network of ligaments (e.g., bifurcate ligament, plantar calcaneonavicular ligament, dorsal talonavicular ligament), work synergistically to provide the foot with essential flexibility and adaptability. The midtarsal joint plays a pivotal role in:

• Shock Absorption: Distributing forces during weight-bearing activities.
• Adaptation to Uneven Surfaces: Allowing the foot to conform to varied terrain.
• Gait Mechanics: Contributing to the pronation and supination movements necessary for efficient walking and running.
• Forefoot Stability: Acting as a crucial link that transfers forces from the hindfoot to the forefoot.

Defining Subluxation in General Terms

In medical terminology, a dislocation describes a complete separation of the articulating surfaces of a joint, where the bones are no longer in contact. A subluxation, however, represents a partial or incomplete dislocation. In a subluxation, the joint surfaces lose their normal anatomical alignment but still maintain some degree of contact. This partial displacement can lead to:

• Compromised joint stability.
• Altered biomechanics.
• Pain and inflammation.
• Potential damage to surrounding ligaments, tendons, and cartilage.

Subluxations can occur in various joints throughout the body, often as a result of trauma, repetitive stress, or underlying structural weaknesses.

Subluxation of the Midtarsal Joint Explained

A subluxation of the midtarsal joint, therefore, involves an abnormal, partial displacement of the talonavicular and/or calcaneocuboid joints. This condition can range from subtle instability to a more significant, yet incomplete, separation of the joint surfaces.

• Mechanism of Injury: Midtarsal joint subluxations typically result from forces that exceed the stabilizing capacity of the surrounding ligaments and muscles. Common mechanisms include:

  • Forced Inversion or Eversion: Sudden, forceful twisting of the foot, often seen in ankle sprains where the midfoot also sustains injury.
  • Direct Trauma: A direct impact to the midfoot, such as a fall or crush injury.
  • Repetitive Microtrauma: Chronic overuse or repetitive stress activities that gradually strain the supporting structures.
  • Plantarflexion and Inversion Injuries: Particularly common in sports that involve jumping, landing, and quick changes in direction.

• Common Causes: Several factors can predispose an individual to a midtarsal joint subluxation:

  • Acute Traumatic Events: Falls, sports injuries (e.g., basketball, soccer, running), or motor vehicle accidents.
  • Chronic Overuse: High-impact activities or occupations requiring prolonged standing or walking, especially without proper footwear.
  • Biomechanical Imbalances:
    • Pes Planus (Flat Feet): Can lead to increased stress and instability in the midfoot.
    • Pes Cavus (High Arches): May result in a rigid foot that transmits shock poorly, leading to compensatory movements and stress.
    • Muscle Weakness: Insufficient strength in the intrinsic foot muscles or extrinsic ankle stabilizers.
  • Ligamentous Laxity: Genetic predisposition or conditions that result in overly flexible ligaments.
  • Inappropriate Footwear: Shoes that lack adequate support or cushioning.

• Associated Symptoms: The symptoms of a midtarsal joint subluxation can vary in intensity but commonly include:

  • Pain: Often localized to the dorsal (top), lateral (outer), or medial (inner) aspect of the midfoot. Pain may worsen with activity, weight-bearing, or specific movements.
  • Swelling and Tenderness: Localized inflammation around the affected joint.
  • Instability: A feeling of the foot "giving way" or being unstable, especially on uneven surfaces.
  • Clicking or Popping Sensation: May be felt or heard during movement as the joint surfaces shift.
  • Difficulty with Weight-Bearing: Leading to an altered gait pattern (limping).
  • Reduced Range of Motion: Stiffness or limited movement in the midfoot.
  • Bruising: May be present in acute traumatic cases.

Diagnosis and Assessment

Diagnosing a midtarsal joint subluxation requires a thorough clinical evaluation and often imaging studies.

• Clinical Examination:
  • Patient History: Detailed inquiry into the mechanism of injury, onset of symptoms, and aggravating/alleviating factors.
  • Palpation: Identifying areas of tenderness over the midtarsal joint lines and surrounding ligaments.
  • Range of Motion Assessment: Evaluating active and passive movements of the foot and ankle, looking for limitations or pain.
  • Stability Tests: Specific manual tests to assess the integrity of the midtarsal ligaments and joint stability.
  • Gait Analysis: Observing the patient's walking pattern to identify compensatory movements or antalgic gait.
• Imaging Studies:
  • X-rays: Used to rule out fractures and assess gross alignment. Weight-bearing X-rays are crucial for evaluating joint space and alignment under load.
  • MRI (Magnetic Resonance Imaging): Provides detailed images of soft tissues, including ligaments, tendons, and cartilage, which can reveal ligamentous tears or inflammation.
  • CT Scan (Computed Tomography): Offers excellent bony detail, useful for assessing subtle fractures or complex bony misalignments.
  • Dynamic Imaging: In some cases, stress X-rays or fluoroscopy may be used to visualize joint movement and instability under load.

Management and Treatment Approaches

Treatment for a midtarsal joint subluxation aims to reduce pain, restore stability, and improve foot function. The approach depends on the severity of the subluxation, associated injuries, and patient activity levels.

• Conservative Management: This is the initial approach for most midtarsal subluxations.
  • RICE Protocol: Rest, Ice, Compression, and Elevation to manage pain and swelling.
  • NSAIDs: Non-steroidal anti-inflammatory drugs to reduce pain and inflammation.
  • Immobilization: A walking boot or cast may be used for a period to allow healing and protect the joint from further stress.
  • Orthotics: Custom or off-the-shelf orthotic inserts can help support the arch, improve foot mechanics, and redistribute pressure.
• Rehabilitation Principles: Physical therapy is essential for restoring full function.
  • Pain and Swelling Management: Modalities such as ultrasound, electrical stimulation, or manual therapy.
  • Range of Motion Exercises: Gentle movements to restore flexibility without stressing the healing joint.
  • Strengthening Exercises: Targeting intrinsic foot muscles, as well as extrinsic ankle and lower leg muscles (e.g., tibialis posterior, peroneals) to enhance dynamic stability.
  • Proprioceptive Training: Balance exercises (e.g., single-leg stance, wobble board training) to improve the body's awareness of foot position and prevent recurrence.
  • Gait Retraining: Correcting abnormal walking patterns to reduce stress on the midfoot.
  • Gradual Return to Activity: A progressive program to safely reintroduce weight-bearing and sport-specific movements.
• When Surgical Intervention is Considered: Surgery is typically reserved for cases where conservative treatment fails, or for severe, chronic instability, or if there are associated fractures or significant ligamentous ruptures. Surgical options may include:
  • Ligament Repair or Reconstruction: To stabilize the joint.
  • Arthrodesis (Fusion): In severe, chronic cases of instability and pain, fusing the involved joints may be considered to eliminate movement and pain, though it results in a loss of flexibility.

Prevention Strategies

Preventing midtarsal joint subluxations involves addressing risk factors and promoting overall foot health.

• Proper Footwear: Wear supportive shoes appropriate for your activity level and foot type. Avoid worn-out shoes.
• Warm-up and Cool-down: Prepare the feet and ankles for activity with dynamic stretches and gradually cool down afterward.
• Balance and Proprioceptive Training: Incorporate exercises that challenge balance and improve joint position sense.
• Foot and Ankle Strengthening: Regularly perform exercises to strengthen the intrinsic foot muscles and ankle stabilizers.
• Address Biomechanical Issues: Consult with a podiatrist or physical therapist to identify and manage conditions like flat feet or high arches with orthotics or specific exercises.
• Gradual Progression: Increase the intensity and duration of physical activities gradually to allow the body to adapt.
• Listen to Your Body: Pay attention to pain or discomfort and seek professional advice if symptoms persist.

Conclusion

A subluxation of the midtarsal joint is a significant injury that can lead to chronic pain and functional limitations if not properly managed. Understanding its complex anatomy, mechanisms of injury, and the importance of early and comprehensive treatment is crucial for fitness enthusiasts, personal trainers, and healthcare professionals alike. With appropriate diagnosis, a structured rehabilitation program, and adherence to prevention strategies, individuals can often achieve a successful recovery and return to their desired activity levels.