The transverse tarsal joint, also known as the midtarsal joint or Chopart's joint, is a compound intertarsal synovial joint located in the human foot that connects the hindfoot to the midfoot, consisting of two distinct articulations: the talonavicular joint between the talus and navicular bones, and the calcaneocuboid joint between the calcaneus and cuboid bones.[1] This biaxial, triplanar structure facilitates essential movements such as supination (inversion, adduction, and plantarflexion) and pronation (eversion, abduction, and dorsiflexion), allowing the foot to adapt to uneven surfaces and transition from a flexible shock-absorbing state during weight acceptance to a rigid lever for propulsion during gait.[2]The joint's stability is maintained by a network of ligaments, including the plantar calcaneonavicular (spring) ligament supporting the medial longitudinal arch at the talonavicular articulation, and the bifurcate, long plantar, and short plantar ligaments reinforcing the calcaneocuboid component.[1] Functionally, it coordinates with the subtalar joint to enable approximately 20° of adduction and 10° of abduction, contributing to overall foot biomechanics by distributing forces across the medial and lateral longitudinal arches and enhancing balance during locomotion.[2] The transverse tarsal joint's role in arch support and dynamic foot function underscores its importance in clinical contexts, where injuries such as midtarsal sprains can lead to instability, altered gait, and conditions like flatfoot deformity if ligamentous integrity is compromised.[3]
Anatomy
Bones involved
The transverse tarsal joint, also known as Chopart's joint, is a compound articulation formed by two distinct synovial joints: the talonavicular joint medially and the calcaneocuboid joint laterally. These joints connect the hindfoot to the midfoot, involving four primary tarsal bones: the talus and calcaneus proximally, and the navicular and cuboid distally.[4]The talus contributes to the medial component of the joint through its head, which presents a convex articular surface that articulates with the navicular bone, forming a saddle-type configuration. The talar head is broader anteriorly, enhancing joint congruence and stability during foot positioning.[5][4]The navicular bone reciprocates this articulation with a concave posterior surface, fully covered in articular cartilage, which receives the convex talar head to create a stable, triplanar interface. On its medial aspect, the navicular features a prominent tuberosity that serves as an attachment site for supporting structures, though it does not directly participate in the joint surfaces.[6][4]Laterally, the calcaneus engages the cuboid via its anterior surface, which bears a concave articular facet oriented vertically for the calcaneocuboid joint, often described as saddle-shaped to permit multiplanar contact. This facet aligns with the cuboid's posterior aspect to bridge the hindfoot and midfoot columns.[7][4]The cuboid bone completes the lateral articulation with a transversely oriented convex posterior surface that matches the calcaneus's concavity, forming a reciprocal saddle configuration for efficient load transfer. Inferiorly and laterally, the cuboid includes a prominent groove, known as the peroneal sulcus, which accommodates the peroneus longus tendon without altering the primary joint interfaces.[8][4]
Joint components
The transverse tarsal joint, also known as Chopart's joint or the midtarsal joint, is a functional complex composed of two distinct synovial joints that collectively facilitate the transition between the hindfoot and midfoot. These components are the talonavicular joint and the calcaneocuboid joint, which together form a compound articulation without a shared enclosing structure. This arrangement allows the joint to separate the hindfoot (comprising the talus and calcaneus) from the midfoot (including the navicular and cuboid), enabling adaptive flexibility during locomotion.[4][3]The talonavicular joint is a saddle-type synovial joint formed by the ovoid, convex head of the talus articulating with the concave, oval posterior surface of the navicular. This configuration supports multiplanar motion, including inversion, eversion, abduction, and adduction, contributing to the foot's overall mobility. The joint is lined by a synovial membrane that secretes lubricating fluid into its dedicated bursa, with hyaline cartilage covering the articular surfaces for smooth gliding.[5][4]The calcaneocuboid joint, the lateral component of the complex, is similarly classified as a saddle-type synovial joint, where the quadrilateral, concavo-convex anterior surface of the calcaneus articulates with the reciprocal posterior surface of the cuboid. This joint exhibits greater inherent stability than the talonavicular due to robust ligamentous reinforcement, limiting excessive motion while still permitting gliding during inversion and eversion. Like its medial counterpart, it features a separate synovial bursa and lacks an interosseous membrane, ensuring independent synovial function. Viewed superiorly, the overall transverse tarsal joint line adopts an S-shaped axis, enhancing its biomechanical efficiency.[9][10][11]
Ligaments and capsule
The transverse tarsal joint, comprising the talonavicular and calcaneocuboid articulations, is stabilized by several key ligaments that connect the calcaneus, navicular, and cuboid bones, preventing excessive motion while supporting the foot's arches.[1][12]The bifurcate ligament is a Y-shaped structure originating from the anterolateral aspect of the calcaneus, dividing into two parts: the calcaneonavicular ligament, which extends to the dorsolateral surface of the navicular, and the calcaneocuboid ligament, which attaches to the dorsomedial surface of the cuboid. This ligament reinforces the lateral aspect of the talonavicular and calcaneocuboid joints, acting as a key stabilizer against inversion forces.[1][12][13]The plantar calcaneonavicular ligament, also known as the spring ligament, is a thick, elastic band that supports the head of the talus and the medial longitudinal arch of the foot; it consists of a talonavicular part passing beneath the talar head to the navicular and a superomedial calcaneonavicular part arising from the sustentaculum tali of the calcaneus to the navicular's medial margin.[1][14][15]The plantar calcaneocuboid ligament, or short plantar ligament, is a short, thick fibrous band extending from the anterior tubercle and plantar surface of the calcaneus to the plantar aspect of the cuboid, just posterior to its tuberosity, where it reinforces the inferior capsule of the calcaneocuboid joint and helps maintain the lateral longitudinal arch.[1][12][16]The long plantar ligament arises from the plantar surface of the calcaneal tubercle and extends distally to the bases of the second through fifth metatarsals, passing over the cuboid and peroneus longus tendon, thereby providing strong reinforcement to the plantar aspect of the lateral midfoot and preserving the longitudinal arch during weight-bearing.[1][11][12]The dorsal calcaneocuboid ligament is a thin, broad band connecting the dorsal surface of the calcaneus to the dorsomedial aspect of the cuboid, offering weaker reinforcement to the dorsal side of the calcaneocuboid joint compared to its plantar counterparts.[1][12]The joint capsule of the transverse tarsal joint is thin and loose, allowing for the required range of motion, with the talonavicular component sharing a capsule with the anterior subtalar joint and the calcaneocuboid having an independent capsule; both are reinforced by medial and lateral collateral ligaments but lack a common enclosing capsule.[1][11][12]
Function
Movements
The transverse tarsal joint, also known as Chopart's joint, facilitates biaxial, triplanar motion primarily through supination and pronation, occurring around two distinct axes: a longitudinal axis inclined approximately 15° superiorly to the transverse plane and 9° medially to the sagittal plane, and an oblique axis inclined 52° superiorly and 57° medially.[1] These axes enable coupled movements including inversion and eversion in the frontal plane, abduction and adduction in the transverse plane, and minor contributions to dorsiflexion and plantarflexion in the sagittal plane.[1] Supination involves inversion, adduction, and plantarflexion, while pronation encompasses eversion, abduction, and dorsiflexion, allowing the joint to adapt the midfoot to varying terrain. The joint also enables approximately 20° of adduction and 10° of abduction in coordination with the subtalar joint.[1][2]The primary range of motion is in inversion, measuring 8° to 10°, with eversion limited to 2° to 3°; these values reflect the joint's greater capacity for supinatory movements to enhance stability during propulsion.[1] Dorsiflexion and plantarflexion at the joint provide minor contributions, accounting for up to 12% of the first 30° of total foot plantarflexion, equivalent to approximately 3.6°.[1] The close-packed position occurs in full supination, maximizing joint congruence and stability, whereas the open-packed position is midway between extremes, permitting greater mobility.[1][17]In cases of capsular restriction, the joint exhibits a characteristic pattern of limitation: dorsiflexion greater than plantarflexion, followed by adduction and medial rotation, which guides clinical assessment of joint integrity.[1] Motion coupling between the component articulations—the talonavicular and calcaneocuboid joints—shows greater excursion at the talonavicular joint compared to the calcaneocuboid, enabling differential adaptation of the forefoot to hindfoot alignment while maintaining overall midfoot flexibility.[18] This differential motion supports the joint's role in distributing loads across the foot without excessive rigidity.[19]
Biomechanical role
The transverse tarsal joint, comprising the talonavicular and calcaneocuboid articulations, provides essential flexibility during the early stance phase of gait by unlocking in pronation, which aligns its joint axes to allow shock absorption and adaptation to ground impact.[20] In contrast, it locks during supination in late stance, diverging the axes to create a rigid lever for efficient propulsion at toe-off.[21] This dynamic mechanism enhances overall foot function by transitioning from a mobile structure for energy dissipation to a stable platform for force generation.[22]The joint supports the medial longitudinal arch primarily through the talonavicular component and the spring ligament complex, which acts as a stabilizing sling for the talar head, aiding balance on uneven terrain.[23] As the key transition between hindfoot and midfoot, it permits pronation and supination movements in coordination with the subtalar joint, facilitating the dispersion of ground reaction forces across the foot.[21] The transverse tarsal joint transmits loads from the tibia via the talus to the forefoot, contributing substantially to foot flexibility; its associated transverse arch accounts for more than 40% of overall foot stiffness, which modulates flexibility in unlocked configurations.[24]In terms of motion, the joint supports inversion and eversion ranges of approximately 10°–13° total, enabling adaptive pronation and supination during weight-bearing.[1] Pathomechanically, hypermobility can result in excessive pronation and foot instability, while hypomobility, often due to conditions like tarsal coalition, leads to a rigid flatfoot with reduced adaptability.[21][25]
Blood supply and innervation
Vascular supply
The transverse tarsal joint, comprising the talonavicular and calcaneocuboid articulations, receives its primary arterial supply from the lateral tarsal artery, which arises from the dorsalis pedis artery as it crosses the midfoot dorsally.[1] This vessel provides blood to the dorsolateral aspects of the joint capsule, ligaments, and adjacent tarsal bones, including the navicular and cuboid.[26]Additional arterial contributions include the medial tarsal arteries, which originate from the dorsalis pedis and supply the medial midfoot structures, as well as branches from the arcuate artery that traverse the dorsal midfoot to nourish the intertarsal regions.[27] These arteries form anastomotic networks with branches of the posterior tibial artery (via the medial and lateral plantar arteries) and the peroneal artery near the ankle, ensuring collateral circulation to the hindfoot-midfoot transition.[28]Venous drainage of the joint occurs primarily through the dorsal and plantar venous plexuses, which collect blood from the midfoot and empty into the deep tibial veins accompanying the posterior and anterior tibial arteries.[29]Clinically, the transverse tarsal joint represents a watershed area with relatively tenuous vascularity, predisposing it to avascular necrosis of the navicular or talar head following dislocations or fracture-dislocations.[30]
Nerve supply
The transverse tarsal joint, comprising the talonavicular and calcaneocuboid articulations, receives primarily sensory innervation without direct motor supply to the joint structures themselves.[31]The talonavicular joint is innervated dorsally by the deep fibular nerve and plantarly by the medial plantar nerve.[1][32] The calcaneocuboid joint receives dorsal innervation from the deep fibular nerve and sural nerve, with plantar supply from the lateral plantar nerve.[1][10][32]Overall, the joint's sensory innervation arises from branches of the tibial nerve (via its medial and lateral plantar divisions) and common fibular nerve (primarily the deep fibular branch), providing comprehensive coverage of the dorsal, plantar, and lateral aspects.[31] Although lacking direct motor innervation, joint function is indirectly influenced by muscles such as the fibularis (peroneal) group, innervated by the superficial fibular nerve, and the tibialis anterior and posterior, supplied by the deep fibular and tibial nerves, respectively, which act across the joint to facilitate inversion, eversion, and other movements.[14] Branches from these nerves also extend to the supporting ligaments of the joint capsule.[31]This innervation supports proprioception through mechanoreceptors in the joint capsule and ligaments, which are crucial for sensing foot position, balance, and adaptive gait adjustments during weight-bearing activities.[33]
Clinical significance
Injuries
The transverse tarsal joint, also known as the Chopart joint, is susceptible to a range of traumatic and degenerative injuries due to its role in load transmission and foot stability. These injuries are relatively rare, with an incidence of Chopart joint disruptions estimated at 2.2 per 100,000 individuals per year. They predominantly affect young, active males, with a male-to-female ratio of about 2:1 and a mean age of 36.8 years.[34]Sprains of the transverse tarsal joint typically involve partial or complete tears of supporting ligaments, such as the bifurcate ligament, which stabilizes the calcaneocuboid and talonavicular articulations. These injuries are graded I-III based on severity, with grade I representing mild stretching, grade II partial tears, and grade III complete ruptures; they often result from inversion trauma during sports or falls, leading to lateral ligamentous distraction. The bifurcate ligament, a Y-shaped structure connecting the calcaneus to the navicular and cuboid, is particularly vulnerable in such mechanisms.[35][12]Chopart dislocations represent more severe disruptions, classified by Main and Jowett into medial (navicular displacement with intact calcaneocuboid joint), lateral (cuboid subluxation with intact talonavicular joint), or complete (both joints affected). Pure dislocations without fractures are uncommon, comprising only 3.7% of cases in a series of 128 injuries, while fracture-dislocations—often involving the navicular or cuboid—are more frequent at 55%. These typically arise from high-energy mechanisms like motor vehicle accidents or falls from height, and may be associated with concurrent calcaneus or navicular fractures; up to 20-40% are initially missed on imaging.[34]Degenerative injuries, primarily osteoarthritis, develop from repetitive microtrauma or prior instability, leading to cartilage erosion in the talonavicular and calcaneocuboid joints. This is a notable risk in athletes subjected to chronic axial loading, with post-traumatic arthritis occurring in up to 67% of fracture-dislocation cases at long-term follow-up. Symptomatic midfoot osteoarthritis, encompassing the transverse tarsal region, affects about 12% of adults over 50 years, though isolated transverse tarsal involvement is less common.[34][36]
Diagnosis and treatment
Diagnosis of transverse tarsal joint injuries, also known as Chopart joint injuries, begins with a thorough clinical examination. Patients often present with midfoot pain, swelling, and point tenderness over the calcaneocuboid or talonavicular joints, corresponding to the Chopart line.[37]Weight-bearing instability may be assessed by observing gait abnormalities or performing stress tests to evaluate midfoot alignment and ligament integrity, with extensions of the Ottawa ankle rules applied to rule out associated fractures.[38]Imaging plays a crucial role in confirming the diagnosis and assessing injury extent. Weight-bearing X-rays in anteroposterior, lateral, and oblique views are initial studies to identify dislocations, subluxations, or fractures, though they may miss up to 41% of subtle injuries.[34]Computed tomography (CT) is recommended for detailed evaluation of fractures and joint congruency, particularly in preoperative planning.[34]Magnetic resonance imaging (MRI) is optimal for detecting ligament tears, such as those in the spring ligament complex, and associated soft tissue damage.[35]Treatment strategies depend on injury severity and stability. Conservative management for sprains and stable injuries involves the RICE protocol (rest, ice, compression, elevation) followed by immobilization in a rigid cast or boot for 4-6 weeks, with non-weight-bearing to allow ligament healing.[38] Surgical intervention is indicated for dislocations or unstable fractures, typically consisting of open reduction and internal fixation (ORIF) to restore anatomic alignment, often combined with ligament repair; arthrodesis is reserved for chronic instability or failed conservative attempts.[34][39]Outcomes following early intervention are generally favorable, with 70-80% of patients achieving good functional recovery based on American Orthopaedic Foot and Ankle Society (AOFAS) scores ranging from 70 to 79 points, particularly with prompt ORIF for dislocations.[34] Complications include avascular necrosis of the navicular bone, posttraumatic osteoarthritis, and chronic pain, occurring in up to 29% of cases due to disrupted blood supply or incomplete reduction.[40]Rehabilitation focuses on progressive recovery to restore function. Initial non-weight-bearing is followed by gradual weight-bearing advancement over 6-8 weeks, incorporating strengthening exercises and proprioceptive training such as balance board activities to improve stability and prevent reinjury.[38]