What is the posterior tibialis (tibialis posterior muscle)?

Posterior Tibialis: Anatomy and Clinical Significance

The posterior tibialis (tibialis posterior) is an artery and muscle of the lower extremity that plays a crucial role in foot function and stability.

Posterior Tibial Artery

• The posterior tibial artery is a major blood vessel of the foot that supplies the posterior and lateral compartment of the leg 1
• It can be palpated as it passes behind the medial malleolus of the ankle 1
• Assessment of the posterior tibial pulse is an important component of vascular examination in patients with suspected peripheral artery disease 1
• Absence of a palpable posterior tibial pulse may indicate peripheral arterial disease, especially when combined with other clinical findings 1

Posterior Tibialis Muscle and Tendon

• The posterior tibialis is a muscle located in the deep posterior compartment of the calf 2
• It is the largest and anteriormost tendon in the medial ankle 3
• Primary functions include:
  • Plantar flexion and supination of the ankle 3
  • Stabilization of the plantar vault (medial longitudinal arch) 3, 4
  • Acts as the main dynamic stabilizer of the medial arch of the foot 5, 6
  • Initiates both ankle plantar flexion and subtalar inversion during the stance phase of gait 4
  • Creates a rigid midfoot by stabilizing the transverse tarsal joint 4
  • Allows for increased power generation by the gastrocsoleus complex through toe-off 4

Anatomical Attachments

• The posterior tibialis tendon has a complex distal insertion pattern with its main attachment at the navicular bone (100% of specimens) 6
• The navicular footprint measures approximately 12.1 mm × 6.9 mm in length and width 6
• Additional tendon slips anchor into multiple bones of the foot, including:
  • Lateral cuneiform (93% of specimens) 6
  • Medial cuneiform (80%) 6
  • Metatarsal bases (80%) 6
  • Cuboid (46%) 6
  • Intermediate cuneiform (19%) 6
  • Calcaneus (12%) 6
• The muscle also attaches to the medial proximal tibia, contributing to knee joint stabilization 7

Clinical Significance

• Posterior tibialis tendon dysfunction (PTTD) is a common cause of acquired flatfoot deformity 2, 5
• Risk factors for PTTD include:
  • Age-related tendon degeneration 5
  • Inflammatory arthritis 5
  • Hypertension 5
  • Diabetes mellitus 5
  • Obesity 5
  • Peritendinous injections 5
  • Acute traumatic rupture (less common) 5
• When the posterior tibialis tendon fails to function properly, other foot ligaments and joint capsules weaken progressively, leading to flatfoot deformity 5
• Disorders of the posterior tibial tendon include:
  • Chronic tendinopathy with progressive rupture 3
  • Tenosynovitis 3
  • Acute rupture 3
  • Dislocation and instability 3
  • Enthesopathies 3
• The most common lesion is a progressive "chewing gum" lesion that develops in chronic tendinopathy, typically seen in overweight women over 50 years of age with valgus flat feet 3

Diagnostic Evaluation

• Sonographic assessment of the posterior tibialis tendon requires:
  • High-frequency, linear-array transducers 3
  • Transverse retromalleolar scans 3
  • Longitudinal retromalleolar scans 3
  • Distal longitudinal scans 3
  • Dynamic studies 3
• Medial ankle pain should be carefully investigated with dynamic maneuvers (forced inversion or dorsiflexion) to assess for instability 3

Clinical Importance in Lower Extremity Function

• The posterior tibialis muscle, along with other medial muscles (sartorius, gracilis, semitendinosus), contributes to the "natural brace" for the knee joint 7
• These muscles are important active stabilizers of the knee 7
• Weakness of these active stabilizers has been identified as a risk factor for incident symptomatic and progressive knee osteoarthritis 7
• Strengthening these muscles is recommended to optimize lower extremity biomechanics and reduce the risk of knee injuries 7