Fact-checked by Grok 2 weeks ago

Leg bone

The leg bones form the primary skeletal components of the human lower limb, consisting of the femur, patella, tibia, and fibula, which collectively support body weight, facilitate bipedal locomotion, and provide attachment sites for muscles, tendons, and ligaments.^[1] In strict anatomical terminology, the "leg" refers to the region between the knee and ankle, encompassing only the tibia and fibula, while the broader lower limb includes the thigh region with the femur and patella.^[2] These bones are classified as long bones, characterized by their elongated shafts and expanded ends for articulation, and they work in concert to absorb impact, maintain stability, and enable a wide range of movements such as walking, running, and jumping.^[1] The femur, or thigh bone, is the longest and heaviest bone in the human body, measuring approximately 26% of an individual's height on average, and it extends from the acetabulum of the pelvis at the hip joint to the knee joint.^[1] Its proximal end features a rounded head connected by a neck to the greater and lesser trochanters, which serve as major muscle attachment points for the gluteal and iliopsoas muscles, while the distal end includes medial and lateral condyles that articulate with the tibia and patella to form the knee joint.^[1] The femur's robust diaphysis, reinforced by the linea aspera ridge, transmits weight from the trunk to the lower leg and is prone to fractures in high-impact trauma due to its critical load-bearing role.^[1] The patella, commonly known as the kneecap, is a small, triangular sesamoid bone embedded within the quadriceps tendon, unique as the largest sesamoid in the body and notably developed in humans among primates for enhancing knee extension efficiency.^[1] It articulates posteriorly with the patellar surface of the femur's distal end, protecting the anterior knee joint while increasing the mechanical advantage of the quadriceps femoris muscle during leg extension.^[1] The patella's smooth articular surfaces and its role in the patellofemoral joint make it susceptible to conditions like patellar dislocation or chondromalacia, particularly in active individuals.^[1] The tibia, or shin bone, is the larger and more medial of the two lower leg bones, serving as the primary weight-bearing structure that transmits forces from the knee to the ankle.^[2] Proximally, it features medial and lateral condyles with an intercondylar eminence for ligament attachments, including the anterior and posterior cruciate ligaments, while distally it forms the medial malleolus that contributes to the ankle's mortise joint with the talus.^[2] Notable features include the tibial tuberosity for patellar ligament insertion and the anterior border, which is subcutaneous and palpable as the shin.^[2] The fibula, the slender lateral bone of the lower leg, does not directly bear weight but stabilizes the ankle and provides attachment for muscles of the lateral compartment, such as the peroneus longus and brevis.^[2] Its proximal head articulates with the tibia at the proximal tibiofibular joint, and the distal end expands into the lateral malleolus, which forms the lateral aspect of the ankle joint and helps prevent excessive inversion.^[2] Connected to the tibia via the interosseous membrane, the fibula's primary clinical significance lies in its use for vascularized bone grafts, such as in jaw reconstruction, due to its dense cortical structure and reliable blood supply.^[2]

Anatomy

Femur

The femur is the longest and strongest bone in the human body, measuring approximately 50 cm in length on average in adults, with variations based on sex, stature, and population. Located in the thigh region between the hip and knee, it is the sole bone of the thigh and exhibits a slight medial convergence toward the knees, aligning with the body's weight-bearing axis to facilitate efficient load transmission from the trunk to the lower leg. In adults, the proximal femur remains a primary site for red bone marrow production, supporting hematopoiesis throughout life.^[3]^[4]^[3] Structurally, the femur consists of a proximal end, shaft, and distal end. The proximal end includes a smooth, spherical head oriented medially, superiorly, and slightly anteriorly, which articulates with the acetabulum of the pelvis to form the hip joint; a fovea capitis on the head provides attachment for the ligament of the head of the femur. This head connects to the shaft via a cylindrical neck with a typical inclination angle of about 128 degrees relative to the shaft's long axis, positioning the head optimally for hip mobility. Rising from the junction of the neck and shaft are the greater trochanter laterally and the lesser trochanter medially, both serving as key attachment sites for muscles such as the gluteus medius, gluteus minimus, and iliopsoas.^[3]^[3]^[3] The shaft, or diaphysis, forms the elongated central portion of the femur, characterized by a cylindrical shape with a mild anterior convexity and a posterior concavity; its diameter varies along its length, typically narrowing in the midsection to about 3 cm in adults. On the posterior surface runs the prominent linea aspera, a roughened longitudinal ridge that bifurcates proximally into the gluteal tuberosity and distally into the medial and lateral supracondylar lines, providing robust attachment points for adductor muscles, vastus lateralis, and vastus medialis. The bone's compact cortical layer surrounds a central medullary cavity filled with yellow marrow, while the ends contain cancellous bone for shock absorption.^[3]^[3]^[3] At the distal end, the femur expands into two large, rounded condyles—the medial condyle, which is larger and more weight-bearing, and the lateral condyle—separated by the intercondylar fossa and articulating with the tibia to form the knee joint. Above the condyles lie the medial and lateral epicondyles, serving as attachments for ligaments and muscles, while the smooth patellar surface on the anterior aspect accommodates the patella during knee extension. This configuration ensures stability and mobility at the knee.^[3]^[3]^[3] The femur's blood supply is critical for its metabolic demands and structural integrity. The shaft receives nutrition primarily from the nutrient artery, a branch of the profunda femoris (deep femoral) artery, which enters through a foramen on the medial surface and branches into ascending and descending rami to vascularize the medullary cavity and endosteum. The femoral head's vascularity depends mainly on retinacular vessels, which are ascending and descending branches from the medial and lateral circumflex femoral arteries; these travel along the neck's surface within the joint capsule, with additional minor supply from the artery of the ligamentum teres via the obturator artery entering the fovea. This retinacular system is vulnerable to disruption in certain injuries, underscoring its anatomical significance.^[3]^[3]^[3]

Patella

The patella, also known as the kneecap, is the largest sesamoid bone in the human body and is located anterior to the knee joint, embedded within the tendon of the quadriceps femoris muscle. It functions as a pulley, redirecting the pull of the quadriceps to improve mechanical efficiency at the knee. Unlike typical long bones, the patella develops entirely within tendon tissue and lacks a diaphysis or shaft, consisting instead of a compact structure adapted for articulation and protection.^[5] Structurally, the patella exhibits a triangular shape, with a broad base superiorly and a pointed apex directed inferiorly toward the tibial tuberosity. The anterior surface is rough and convex, facilitating attachment of the quadriceps tendon and subcutaneous fibrous expansions, while also being perforated by nutrient foramina for vascular supply. In contrast, the posterior surface is smooth and concave, forming the articular area divided into medial and lateral facets—specifically, three facets on each side plus an additional odd facet along the medial border—that glide against the femoral trochlea during movement. These facets vary in configuration, classified by the Wiberg system into Type I (symmetric, ~10% prevalence), Type II (most common, flat medial facet, ~65%), and Type III (lateral prominence, ~25%). The apex connects distally to the patellar ligament, which transmits force to the tibia.^[5]^[6] The patella measures approximately 4.3 cm in transverse width, 3.6–4.3 cm in height from base to apex, and 2.2–2.5 cm in thickness on average, though these dimensions show sexual dimorphism and age-related variation, with males typically exhibiting larger sizes. Shape variations include hypoplastic (patella parva) or hyperplastic (patella magna) forms, as well as less common morphologies like hunter's cap or half-moon shapes; notably, bipartite or multipartite patellae, resulting from failure of ossification centers to fuse, occur in 2–6% of the population and are more prevalent in males (up to 9 times higher incidence).^[7]^[8]^[9]^[10] Developmentally, the patella originates from a mesenchymal condensation within the quadriceps femoris tendon, chondrifying around the 14th week of gestation before the knee joint fully forms. Ossification begins from a single primary center between ages 3 and 6 years, though radiographic visibility may appear as early as 2–3 years; secondary centers can contribute to variants like bipartite forms if fusion fails by adolescence. The bone is composed of dense cortical bone overlying trabecular cancellous tissue, without a central medullary cavity typical of long bones, which enhances its resistance to compressive forces. By increasing the quadriceps moment arm, the patella boosts torque efficiency by up to 60% during the terminal 15° of knee extension.^[5]^[6]^[11]

Tibia

The tibia, commonly known as the shin bone, is the larger and more medial of the two long bones in the lower leg, serving as the primary weight-bearing structure between the knee and ankle joints. It is the second longest bone in the human body, after the femur, with an average adult length of approximately 36 to 40 centimeters. The tibia is thicker on its medial side and features a nutrient foramen on its posterior surface, which allows passage of the nutrient artery supplying the bone. As the main bone responsible for lower leg stability, it transmits the majority of the body's weight during locomotion and standing. At its proximal end, the tibia expands to form the medial and lateral condyles, which together create the tibial plateau—a flat, superior articular surface that receives the femoral condyles to form the knee joint. This plateau is covered by the medial and lateral menisci, which enhance shock absorption and stability. Between the condyles lies the intercondylar eminence, a raised area with medial and lateral tubercles that serve as attachment sites for the anterior and posterior cruciate ligaments as well as the menisci. The tibial tuberosity, a prominent ridge on the anterior surface just below the condyles, provides the attachment point for the patellar ligament, facilitating knee extension. The tibial shaft is triangular in cross-section, characterized by three borders: the anterior border forming the sharp anterior crest (the subcutaneous shin surface), the medial border, and the lateral interosseous border. The shaft's surfaces include a broad anterior surface for muscle attachments, a posterior surface marked by the soleal line for soleus muscle origin, and a lateral surface facing the fibula. This robust, prism-like structure supports the tibia's role in weight transmission. The distal end of the tibia features a downward projection known as the medial malleolus, which forms the medial prominence of the ankle and articulates with the talus bone to contribute to the ankle joint. The inferior articular surface of the distal tibia is concave and smooth, directly contacting the superior aspect of the talus for hinge-like movement. Laterally, a fibular notch accommodates the distal fibula, forming the syndesmosis joint. The tibia connects to the fibula along its length via the interosseous membrane, a fibrous sheet that distributes forces between the two bones. Overall, the tibia is significantly larger than the fibula and is essential for the structural integrity of the lower leg.

Fibula

The fibula is the slender lateral bone of the lower leg, positioned parallel to the tibia and forming part of the ankle joint. It consists of a proximal head, a long shaft, and a distal end that expands into the lateral malleolus. The proximal head is slightly enlarged and features a flat, circular facet that articulates with the lateral condyle of the tibia, connected by a small neck region. The shaft exhibits a triangular cross-section proximally that becomes more irregular distally, with an interosseous border on the medial surface that anchors the interosseous membrane linking it to the tibia. The distal end forms the prominent lateral malleolus, which includes a malleolar fossa for ligament attachment and articulates inferiorly with the talus.^[12]^[13]^[14] In adults, the fibula measures approximately 32 to 38 cm in length, making it thinner and shorter than the adjacent tibia, which contributes to its accessory role in the lower leg. Unlike the tibia, the fibula does not bear significant weight, transmitting less than 10% of the body's load during neutral ankle positioning, primarily serving to stabilize the ankle and provide leverage for muscle action. Its articulations include the proximal tibiofibular joint with the tibia, a syndesmotic connection via the interosseous membrane along the shaft, and the distal tibiofibular joint, where the lateral malleolus engages the talus to form the ankle mortise. These synovial and fibrous joints allow limited movement while maintaining structural integrity.^[15]^[16]^[17] The fibula primarily functions as an attachment site for muscles of the lateral and posterior leg compartments, including the fibularis (peroneus) longus and brevis on the lateral surface, which facilitate foot eversion and plantarflexion. Other key attachments include the extensor digitorum longus and extensor hallucis longus on the anterior surface for toe extension, as well as the soleus and flexor hallucis longus posteriorly. Due to its low mechanical load and robust vascular supply from the fibular artery, the fibula is frequently harvested for autologous bone grafts in reconstructive procedures, such as mandibular reconstruction, where segments of the shaft provide suitable length and minimal donor site morbidity.^[12]^[14]^[18]

Function

Weight-Bearing and Support

The leg bones form a robust structural chain that transmits body weight from the hip to the foot, with the femur serving as the primary conduit for load transfer. The distal femur's medial and lateral condyles articulate with the proximal tibial plateau, distributing compressive forces across the knee joint during weight-bearing activities.^[19] The tibia bears approximately 85-90% of the total load transmitted through the lower leg, functioning as the main weight-supporting element due to its larger cross-sectional area and alignment with the body's mechanical axis.^[20] In contrast, the fibula contributes to stability by resisting torsional and lateral forces, while sharing 5-19% of the axial load (depending on ankle position), thereby preventing excessive tibial deformation.^[21] The patella augments this system by increasing the quadriceps moment arm, which reduces the force required for knee extension and optimizes patellofemoral joint load distribution during upright posture.^[22] Biomechanically, the femur exhibits exceptional compressive strength, capable of withstanding loads up to several times body weight before failure, with ultimate compressive stress values around 205 MPa in healthy adults.^[23] Trabecular bone within the epiphyseal regions of the femur and tibia plays a critical role in stress distribution, with its spongy architecture aligning along principal stress trajectories to efficiently dissipate forces and minimize peak strains.^[24] Optimal alignment is maintained via the Mikulicz line, a mechanical axis extending from the center of the femoral head through the intercondylar notch to the center of the talar dome, ensuring even load sharing across the joint surfaces.^[25] During dynamic activities like running, the leg bones endure peak ground reaction forces equivalent to 3-4 times body weight, highlighting their capacity for repeated high-impact loading.^[26] In athletes engaging in weight-bearing sports, such as running or jumping, bone adaptations include increased cortical thickness and mineral density in the femur and tibia, enhancing resistance to compressive fatigue.^[27] Evolutionarily, the transition to bipedalism in hominins drove thickening of the femoral shaft and robustification of the tibial diaphysis, allowing efficient vertical load transmission while freeing the upper limbs.^[28] Proper alignment is quantified by the femorotibial angle, which measures approximately 174° in neutral knees (equivalent to 6° valgus), balancing medial and lateral compartment pressures.^[29] Deviations, such as varus (increased angle beyond 180°) or valgus (decreased below 174°), shift load unevenly, potentially overloading the medial or lateral tibial plateau and compromising long-term support.^[30]

Facilitation of Movement

The leg bones play a crucial role in locomotion by forming articulations that allow for controlled motion at the knee and ankle. The knee joint, primarily a hinge articulation between the femur, tibia, and patella, permits flexion and extension with a limited degree of rotation, enabling efficient forward propulsion during walking and running. This hinge-like structure facilitates a normal range of knee flexion from 0° to approximately 140°.^[31]^[32] The patella enhances this by gliding within the femoral trochlea, stabilizing the joint during extension. The proximal and distal tibiofibular joints, along with the syndesmotic articulation, provide rotational stability to the ankle, allowing subtle movements that support overall leg swing without compromising alignment.^[33]^[34] Muscle attachments on the leg bones further facilitate movement by providing leverage points for key locomotor muscles. On the femur, the greater trochanter serves as the insertion site for the gluteus medius and minimus muscles, which abduct and stabilize the hip during the swing phase of gait, while the lesser trochanter anchors the iliopsoas for hip flexion. The tibial tuberosity receives the patellar ligament, transmitting quadriceps force for knee extension. The fibula head attaches the peroneus (fibularis) longus and brevis muscles, aiding in foot eversion and inversion to adjust terrain during locomotion. Additionally, the superior aspect of the patella connects to the vastus intermedius muscle, contributing to the quadriceps mechanism that drives knee extension.^[35]^[36]^[37]^[38]^[12]^[5] Biomechanically, these features optimize movement efficiency in the gait cycle, where the swing phase relies on coordinated hip flexion, knee extension, and ankle dorsiflexion propelled by the leg bones. The patella increases the effective moment arm of the quadriceps tendon, enhancing knee extension torque by redirecting force away from the joint axis. The fibula contributes to ankle stability, bearing 5-19% of axial load and supporting eversion and inversion to maintain balance during dynamic activities.^[21] In jumping, the trochanters of the femur provide leverage for gluteal muscles, amplifying hip extension power to generate upward propulsion.^[39]

Development

Embryonic Formation

The embryonic formation of leg bones originates from the lateral plate mesoderm during early human development. Around the fourth week of gestation, the lower limb buds emerge as outgrowths from the body wall, consisting of proliferating mesenchymal cells covered by ectoderm. These buds establish the foundational structure for the femur, tibia, fibula, and patella through coordinated signaling mechanisms that define the proximodistal, dorsoventral, and anteroposterior axes.^[40]^[41] The apical ectodermal ridge (AER), a thickened ectodermal structure at the distal tip of the limb bud, plays a critical role in directing proximodistal outgrowth by secreting fibroblast growth factors (FGFs), particularly FGF8 and FGF4, which promote mesenchymal proliferation. In contrast, the zone of polarizing activity (ZPA), located at the posterior margin of the limb bud, secretes sonic hedgehog (Shh) to establish anteroposterior asymmetry and patterning. By the sixth week, mesenchymal cells within the limb buds condense to form precartilage models of hyaline cartilage, initially outlining the future femur, tibia, and fibula; the patella begins as a cartilaginous process arising from mesenchymal cells associated with the developing quadriceps tendon and distal femur. Hox genes, such as HoxD13, contribute to segmental patterning of these condensations, influencing the specification of skeletal elements in the hindlimb, as evidenced by studies showing HoxD13 misexpression leads to alterations in long bone lengths like the femur and tibia.^[42]^[43]^[44]^[45]^[46]^[47] During the seventh week, the lower limb undergoes a 90-degree medial rotation along its longitudinal axis, positioning the knee anteriorly and aligning the extensor muscles on the anterior surface, which refines the orientation of the emerging skeletal elements. This rotation, combined with the earlier patterning signals, ensures proper anatomical alignment of the leg bones prior to subsequent ossification processes.^[48]

Ossification and Growth

The ossification of leg bones occurs primarily through endochondral ossification, where hyaline cartilage models are gradually replaced by bone tissue starting in the fetal period. In the femur, the primary ossification center forms in the diaphysis during the seventh week of gestation, while the secondary ossification center for the distal epiphysis appears around the time of birth.^[49] For the tibia, the diaphyseal center emerges around the seventh week of gestation, with the proximal epiphyseal center also appearing at birth.^[50] The fibula follows a similar pattern to the tibia, with its diaphyseal ossification center developing between the seventh and eighth weeks of gestation.^[2] In contrast, the patella, a sesamoid bone, undergoes secondary ossification later, with its primary center appearing between ages 3 and 6 years. Longitudinal growth of these bones is driven by endochondral ossification at the epiphyseal plates (growth plates), where chondrocytes proliferate, hypertrophy, and are replaced by bone, elongating the bone from both ends.^[2] Appositional growth occurs on the periosteal surface, increasing bone diameter through the addition of new bone layers.^[51] Nutrient arteries play a crucial role during this elongation, entering the diaphysis and branching to supply the metaphyseal regions where active ossification takes place.^[2] Overall, the leg bones undergo substantial longitudinal growth from fetal stages to adulthood.^[52] Epiphyseal plate closure marks the end of longitudinal growth; for the femur, the distal plate typically fuses between 14 and 16 years in females and 16 to 18 years in males,^[53] while the proximal plate closes later, around 16 to 18 years in females and 18 to 20 years in males. The proximal tibial and fibular plates fuse around 15 to 17 years in females and 17 to 19 years in males, with distal closures following shortly after.^[54] Hormonal factors tightly regulate this process, with growth hormone (GH) and insulin-like growth factor-I (IGF-I) promoting chondrocyte proliferation and matrix production at the growth plates to drive elongation.^[55] Thyroid hormones support overall cartilage maturation, while sex steroids—estrogen in females and testosterone in males—initially accelerate growth during puberty but ultimately induce plate closure by promoting chondrocyte senescence and ossification of the remaining cartilage.^[56] Females generally experience earlier closure (1-2 years ahead of males) due to higher estrogen levels during puberty, resulting in shorter overall leg bone length compared to males.^[57]

Clinical Significance

Injuries and Fractures

Leg bone injuries, particularly fractures, arise primarily from traumatic mechanisms and pose immediate risks to mobility and vascular integrity. Femoral neck fractures frequently occur in the elderly due to low-energy falls, such as slips or trips, which disrupt the bone's precarious blood supply and elevate the risk of avascular necrosis, a condition where the femoral head loses viability and may collapse.^[58] These injuries contribute to a 10-15% mortality rate within the first 30 days in older patients, often due to associated comorbidities and surgical delays.^[59] In contrast, femoral shaft fractures typically result from high-energy trauma, including motor vehicle collisions or falls from height, with 10-20% presenting as open fractures that expose bone to contamination and necessitate immediate irrigation and debridement.^[60] The standard treatment for femoral shaft fractures involves intramedullary nailing, a minimally invasive technique that provides stable fixation and promotes early mobilization while minimizing soft tissue disruption.^[61] Tibial and fibular fractures account for the majority of lower leg injuries, with the tibia involved in over 80% of cases due to its primary weight-bearing role. Tibial plateau fractures commonly stem from axial loading during falls onto the extended knee, often leading to concomitant meniscus damage in up to 50% of instances, which compromises articular stability and increases the likelihood of early osteoarthritis.^[62] Tibial shaft fractures may develop as stress injuries in runners from repetitive microtrauma during prolonged training, with approximately 75-85% also involving the fibula, complicating alignment and healing.^[63] High-energy tibial pilon fractures, affecting the distal articular surface, arise from direct axial loads like those in motorcycle accidents, resulting in severe comminution and soft tissue compromise. Following any tibial fracture, acute compartment syndrome poses a critical risk, occurring in 1-10% of cases due to swelling and increased intracompartmental pressure that can lead to muscle and nerve necrosis if not promptly addressed via fasciotomy.^[64] Patellar injuries often involve direct trauma to the anterior knee. Transverse patellar fractures typically result from a forceful blow, such as a fall onto the knee or impact from a dashboard in vehicular accidents, disrupting the extensor mechanism and causing hemarthrosis.^[65] Patellar dislocations are usually traumatic, triggered by sudden twisting or valgus forces during sports, with a recurrence rate of 15-60% in young patients; however, generalized patellar instability accounts for about 3% of all such cases and may require surgical stabilization to prevent repeated episodes.^[66]

Diseases and Disorders

Osteoporosis is a metabolic bone disease characterized by reduced bone mineral density and deterioration of bone microarchitecture, particularly affecting the femur and tibia, which leads to increased fragility and fracture risk. This condition is prevalent in postmenopausal women due to accelerated bone loss following estrogen decline, with approximately 50% of Caucasian women over 50 years experiencing an osteoporotic fracture in their lifetime.^[67] The proximal femur and distal tibia are common sites of involvement, where low bone density heightens susceptibility to insufficiency fractures under normal loading.^[68] Osteomyelitis represents an infectious pathology of the bone, most frequently involving the tibia in children through hematogenous spread. Acute hematogenous osteomyelitis is predominantly caused by Staphylococcus aureus, accounting for up to 95% of cases in pediatric populations, resulting in inflammation of the medullary cavity and potential sequestrum formation.^[69] Tuberculous osteomyelitis, a chronic form also known as Pott's disease when affecting the spine, can involve long bones like the tibia and arises from Mycobacterium tuberculosis infection and manifests with granulomatous lesions, bone destruction, and adjacent soft tissue abscesses.^[70] Bone tumors encompass neoplastic disorders of the leg bones, with osteosarcoma being the most common primary malignant tumor, comprising about 20% of all primary bone sarcomas and typically originating in the metaphysis of the proximal tibia or distal femur. It peaks in incidence around age 15 during adolescent growth spurts, presenting with aggressive bone production and soft tissue extension.^[71] Ewing's sarcoma, another high-grade malignancy, preferentially affects the diaphysis of long bones such as the tibia and femur, often in children and young adults, characterized by small round blue cells and permeative bone destruction.^[72] Blount's disease is a developmental disorder causing progressive tibia vara, or varus deformity of the proximal tibia, primarily in children due to abnormal medial physeal growth inhibition from excessive compressive forces. It typically manifests in toddlers or adolescents with bow-legged appearance and lateral knee deviation. Osgood-Schlatter disease involves traction apophysitis at the tibial tuberosity, where repetitive stress from the patellar tendon during growth spurts leads to inflammation, swelling, and pain in adolescents aged 10-15. Paget's disease of bone, a degenerative condition, can cause anterior bowing of the femur through excessive osteoclast-mediated resorption followed by disorganized bone formation, often in older adults and leading to enlarged, weakened long bones.^[73] Leg length discrepancy arises from growth plate (physeal) disturbances in the femur or tibia, such as premature closure or overgrowth, affecting approximately 1 in 1,000 children with differences exceeding 2 cm at skeletal maturity. Treatment for moderate discrepancies (2-5 cm) often involves epiphysiodesis, a procedure that arrests growth on the longer side by percutaneous drilling or plating to equalize limb lengths over time.^[74]^[75]

References

[1]
Bones of the Lower Limb – Anatomy & Physiology - UH Pressbooks
The lower limb contains 30 bones. These are the femur, patella, tibia, fibula, tarsal bones, metatarsal bones, and phalanges.
[2]
Anatomy, Bony Pelvis and Lower Limb: Leg Bones - StatPearls - NCBI
The leg is the region of the lower limb between the knee and the foot. It comprises two bones: the tibia and the fibula.
[3]
Anatomy, Bony Pelvis and Lower Limb: Femur - StatPearls - NCBI
The femur is the longest, heaviest, and strongest human bone. At the proximal end, the pyramid-shaped neck attaches the spherical head at the apex and the ...Missing: dimensions | Show results with:dimensions
[4]
Femur (Thighbone): Anatomy, Function & Common Conditions
Linea aspera; Gluteal tuberosity; Pectineal line; Popliteal fossa. Femur distal aspect. The lower (distal) end of your femur forms the top of your knee joint.<|control11|><|separator|>
[5]
Anatomy, Bony Pelvis and Lower Limb, Knee Patella - NCBI - NIH
Oct 27, 2023 · The patella is the largest sesamoid bone in the human body, located anterior to the knee joint within the tendon of the quadriceps femoris muscle.Introduction · Structure and Function · Embryology · Physiologic VariantsMissing: dimensions | Show results with:dimensions
[6]
Patella | Radiology Reference Article | Radiopaedia.org
Jul 20, 2024 · The ossification centers of the patella appear between 3-6 years. ... Which of the following statements is TRUE? bipartite patella at this age is ...Multipartite patella · Bipartite patella · Patella alta · Dorsal defect of the patella
[7]
Morphologic Evaluation of the Patella: The Impact of Gender and Age
Feb 14, 2024 · The patellar height was greatest in the age group ≤20 years old and smallest in the 41–60 age group (p values < 0.05; ANOVA and Kruskal–Wallis ...
[8]
Anatomic dimensions of the patella measured during total knee ...
The articular surface of the patella was found to have an oval shape with a width-to-height ratio (46 x 36 mm) of 1.30. The dome was 4.8 mm high and displaced ...Missing: bone | Show results with:bone
[9]
Bipartite patella | Radiology Reference Article | Radiopaedia.org
May 17, 2025 · The superolateral accessory ossification center of the patella is usually present by 12 years of age and may persist into adult life. Bipartite ...
[10]
Painful bipartite patella following injury: a case report - PMC
Dec 28, 2021 · Bipartite patella is a rare phenomenon, with a reported incidence ranging from 0.2% to 6%. It occurs more often in males [5] and is bilateral ...
[11]
Patella: Anatomy, function and clinical aspects | Kenhub
The attachment of the quadriceps muscle if found on the superior surface extends distally onto the anterior surface. The rough marking found at the lateral and ...
[12]
Anatomy, Bony Pelvis and Lower Limb: Fibula - StatPearls - NCBI
Unlike the tibia, the fibula is not a weight-bearing bone. Its main function is to combine with the tibia and provide stability to the ankle joint. The distal ...Missing: dimensions | Show results with:dimensions
[13]
The Fibula - Surfaces - Articulations - Fractures - TeachMeAnatomy
### Summary of the Fibula Anatomy
[14]
Fibula - Physiopedia
Proximal: The proximal part of the fibula features an enlarged pointed head and a small neck. · Shaft: The shaft of the fibula is twisted and triangular in cross ...Missing: dimensions | Show results with:dimensions
[15]
Fibula (Calf Bone): Anatomy, Function & Common Conditions
Fibula (Calf Bone). The fibula is the third longest bone in your body. It isn't weight-bearing, but it supports muscles, tendons and ligaments.Missing: dimensions articulations
[16]
Role of the fibula in weight-bearing - PubMed
With the ankle joint in neutral position, the weight distribution to the fibula amounted to 6.4%. With dorsiflexion of the ankle joint, the weight on the fibula ...
[17]
Fibula | Radiology Reference Article - Radiopaedia.org
Jun 25, 2025 · The fibula (plural: fibulae) is the smaller of the two bones of the leg. It is not directly involved in the transmission of weight but is important for ankle ...Os subfibulare · Proximal tibiofibular joint · Pediatric tibia fibula (lateral view)Missing: bearing | Show results with:bearing
[18]
https://pubmed.ncbi.nlm.nih.gov/30256883
[19]
Morphologic Features of the Distal Femur and Proximal Tibia
Jan 25, 2021 · The distal end of the femur is widely expanded as a bearing surface for transmission of weight to the tibia. The medial and lateral condyles are ...
[20]
Tibia – Knowledge and References - Taylor & Francis
The tibia is the primary weight-bearing bone of the leg and accounts for 85% to 90% of weight transfer depending on the position of the foot and ankle (Moore et ...
[21]
(PDF) The Biomechanical Role of the Fibula in Lower Limbs
The fibula plays a crucial role in load distribution within the lower limb, reducing the load on the tibia and femur. 5 Removal of the fibula requires other ...
[22]
Update on Patellofemoral Anatomy and Biomechanics - ScienceDirect
The patella does so by decreasing the quadriceps force required to facilitate knee extension.10 Additionally, the patella integrates the divergent forces of the ...
[23]
7.1: Strength of Human Bones - Physics LibreTexts
Mar 12, 2024 · The femur can support 30x body weight, roughly 6,000 lbs. Its ultimate compressive strength is 205 MPa, and tensile strength is 135 MPa.
[24]
Biomechanics and Mechanobiology of Trabecular Bone: A Review
Trabecular bone is a highly porous, heterogeneous, and anisotropic material which can be found at the epiphyses of long bones and in the vertebral bodies.
[25]
Lower Limb Alignment | Radiology Key
Jun 21, 2020 · Mechanical Axis of the Lower Limb (Mikulicz Line) The axis passes through the center point of the hip joint (center of the femoral head) and ...
[26]
[PDF] Running involves a high level of repetitive force
To ensure that the body is able to attenuate these forces it is absolutely critical there is proper mobility at the lower extremity joints, and adequate ...
[27]
Exercise and Bone Health - OrthoInfo - AAOS
Exercise helps build and maintain bone strength, making bones denser. Inactivity causes bone loss. Exercise also improves balance and coordination.Weightbearing Exercise · Strength-Training Exercise · Age And Bone Health Fitness
[28]
Why do humans walk on two legs? - Animals | HowStuffWorks
Jul 24, 2007 · Fossils show that some ancient humans developed longer legs, different hip structures or thicker leg bones, consistent with modern-day humans.<|control11|><|separator|>
[29]
Normal Range and Treatment for Abnormal Tibiofemoral Angle
Jul 8, 2025 · The normal tibiofemoral angle in adults is approximately 5-7 degrees of valgus alignment, with stabilization typically occurring around 3-8 degrees of valgus ...
[30]
Open Wedge High Tibial Osteotomy Principles and Techniques
May 8, 2023 · To define the malalignment, a Mikulicz line must be drawn, i.e., from the center of the femoral head to the center of the ankle. If that line ...
[31]
Anatomy, Bony Pelvis and Lower Limb, Knee - StatPearls - NCBI - NIH
Nov 5, 2023 · The bones articulating at the knee are large and complex. The femur has a slight medial slant, while the tibia is nearly vertical.
[32]
[PDF] Joints (Shoulder, Elbow, Wrist, Hip, Knee, and Ankle) Examination
Knee range of motion: a. Normal range of motion, using the anatomical position as zero degrees. Flexion = 0 to 140 degrees. Extension - zero degrees ...
[33]
Distal Tibiofibular Syndesmosis: Anatomy, Biomechanics, Injury and ...
A stable and precise articulation of the distal tibiofibular syndesmosis is essential for normal motion of the ankle joint.
[34]
[PDF] Normal Anatomy and Biomechanics of the Knee
The tibiofemoral joint allows transmission of body weight from the femur to the tibia while providing hinge-like, sagittal plane joint rotation along with a ...
[35]
Anatomy, Bony Pelvis and Lower Limb, Gluteus Minimus Muscle
The gluteus minimus is fan-shaped and is attached distally to the femur at the anterior border of the greater trochanter.[1]. The gluteus minimus is ...
[36]
Muscles of the Lower Limb | UAMS Department of Neuroscience
gluteus medius, external surface of the ilium between the posterior and anterior gluteal lines, greater trochanter of the femur ; gluteus minimus, external ...
[37]
Anatomy, Bony Pelvis and Lower Limb: Psoas Major - NCBI - NIH
The common tendon attaches on the lesser trochanter of the femur: the muscle during contraction of the fibers lead to external rotation and abduction of the ...Introduction · Structure and Function · Embryology · Muscles
[38]
https://anatomy.med.utah.edu/diganat/anatomy_tutorials/digital_dissector/index.php?selectsize=Large&textsize=Large&lab=35&menu=35%20TibiaFibula&add=/tibia_fibula
[39]
Biomechanics and muscle function during gait - PMC - NIH
Sep 15, 2013 · The next important phase is pre-swing, when the leg is accelerated as a biarticular pendulum that folds and extends passively during swing. This ...
[40]
Patellar Injury and Dislocation - Medscape Reference
Feb 27, 2024 · One study demonstrated that the patella most significantly increases the moment arm of the quadriceps at 20° of knee flexion. After patellectomy ...
[41]
Fibula and its ligaments in load transmission and ankle joint stability
On axial loading of the lower limb, the fibula was found to take an average of 17% of a 1500 N axial load.
[42]
https://www.sciencedirect.com/topics/medicine-and-dentistry/limb-development
[43]
Formation of the Limb Bud - Developmental Biology - NCBI Bookshelf
Limb development begins when mesenchyme cells proliferate from the somatic layer of the limb field lateral plate mesoderm (limb skeletal precursors) and from ...
[44]
Limb Development - an overview | ScienceDirect Topics
The AER, which is located at the tip of the limb buds, maintains outgrowth of the limb bud by expressing fibroblast growth factor 8 and 4 (Fgf8, Fgf4), which in ...
[45]
The roles of FGFs in the early development of vertebrate limbs
The purpose of this review is to discuss the functions performed by members of the FGF family in one of the best-studied vertebrate developmental systems—limb ...Fgf Ligand And Receptor... · Fgf Function In The... · Fgf Function In Limb Bud...Missing: patella | Show results with:patella
[46]
Embryology - Basic Science - Orthobullets
Jul 22, 2022 · Steps of limb development: Shh regulates limb bud formation, chondrification occurs where mesenchyme differentiates into chondrocytes.
[47]
6.10: Embryonic Development of the Skeleton - Medicine LibreTexts
Sep 25, 2024 · Also during the sixth week of development, mesenchyme within the limb buds begins to differentiate into hyaline cartilage that will form models ...
[48]
On the development of the patella - Company of Biologists journals
May 15, 2015 · Collectively, these results indicate that the patella starts to develop as part of the femur before the maturation of the quadriceps tendon and ...INTRODUCTION · RESULTS · DISCUSSION · MATERIALS AND METHODS
[49]
Analysis of Hoxd-13 and Hoxd-11 misexpression in chick limb buds ...
Hoxd-13 misexpression in the hindlimb results in a shortening of the long bones, including the femur, the tibia, the fibula and the tarsometatarsals.Missing: patterning | Show results with:patterning
[50]
Development of Limbs | Obgyn Key
Mar 31, 2020 · The lower limbs rotate medially through almost 90 degrees; therefore, the future knees come to face ventrally, and the extensor muscles lie on ...<|separator|>
[51]
Development of the Appendicular Skeleton – Anatomy & Physiology
Thus, ossification of the femur begins at the end of the seventh week with the appearance of the primary ossification center in the diaphysis, which rapidly ...
[52]
Anatomy, Bony Pelvis and Lower Limb: Tibia - StatPearls - NCBI - NIH
The tibia is one of two bones that comprise the leg.[1] As the weight-bearing bone, it is significantly larger and stronger than its counterpart, the fibula.<|control11|><|separator|>
[53]
Bone Development & Growth - SEER Training Modules
Bone growth is under the influence of growth hormone from the anterior pituitary gland and sex hormones from the ovaries and testes. Illustration showing how a ...
[54]
[PDF] Femur morphology in healthy infants and young children
Jan 4, 2022 · Abstract. The objective of this study was to characterize femur morphology in healthy infants and young children.<|control11|><|separator|>
[55]
Anatomy of the distal femur - AO Surgery Reference
It closes between 14 and 17 in females and between 15 and 19 in males with a wide variability in age.Missing: human | Show results with:human<|control11|><|separator|>
[56]
Bone Age Determination of Epiphyseal Fusion at Knee Joint and Its ...
May 8, 2024 · Embryologically, it develops at the age of six weeks, with condensation of cells and ossification centers present by the end of the twelfth week ...Missing: timeline patella
[57]
Endocrine regulation of longitudinal bone growth - PubMed
Aug 22, 2011 · Longitudinal growth is primarily influenced by the GH-IGF-I axis, which is a mixed endocrine-paracrine-autocrine system.
[58]
Pubertal growth and epiphyseal fusion - PMC - PubMed Central - NIH
Growth hormone (GH) and insulin-like growth factor-I (IGF-I) are the main stimulators of longitudinal bone growth. They are also important for the acquisition ...
[59]
Hormonal regulation of longitudinal bone growth - PubMed
Hormones that have an established role in the regulation include growth hormone (GH), thyroid hormone and sex steroids. GH promotes mainly the growth of the ...
[60]
Femoral Neck Fractures - StatPearls - NCBI Bookshelf
May 8, 2023 · Femoral neck fractures are associated with low energy falls in the elderly. ... Avascular necrosis increased risk factor with increased initial ...
[61]
Hip Fracture in the Elderly: Time to Act - PMC - PubMed Central
The general mortality rate following procedures of this kind is 10–15% within the first 30 days and 25–30% at 6 months. The excess mortality due to hip ...
[62]
Incidence of complications and functional outcomes following ... - NIH
Aug 16, 2024 · Femoral shaft fractures have an annual incidence ranging from 10 to 21 per 100,000 patients and are usually sustained either after high energy ...
[63]
Initial surgical management of injuries to the lower extremities in ...
Locked intramedullary nailing should be the surgical procedure of choice for the definitive treatment of femoral shaft fractures in polytrauma patients.
[64]
Tibial Plateau Fractures - StatPearls - NCBI Bookshelf - NIH
Tibial plateau fractures may be associated with injury to nearby structures including vasculature, nerves, ligaments, menisci, and adjacent compartments.
[65]
Acute Compartment Syndrome - StatPearls - NCBI Bookshelf - NIH
Tibial shaft fracture is the most common cause of acute compartment syndrome, is associated with a 1 to 10 percent incidence of acute compartment syndrome.Epidemiology · History and Physical · Evaluation · Treatment / Management
[66]
Patellar Fractures (Broken Kneecap) - OrthoInfo - AAOS
Fall directly onto your knee; Take a hard blow to the kneecap, such as during a football tackle where the tackler's helmet hits your knee, or when a baseball or ...
[67]
Patella Dislocation - StatPearls - NCBI Bookshelf - NIH
Jul 4, 2023 · The recurrence rate following a first-time dislocation is around 15-60%.[1] Generalized patellar instability is thought to represent up to 3% of ...
[68]
The clinician's guide to prevention and treatment of osteoporosis
Among Caucasian adults in the USA aged 50 years and older, about 50% of women and 20% of men will experience an osteoporotic fracture in their remaining ...
[69]
A comprehensive overview on osteoporosis and its risk factors - PMC
Bone mass starts decreasing among men and women in their 40s, leading to increased risk of fragility fractures. However, women lose bone more rapidly, ...
[70]
Childhood osteomyelitis: imaging characteristics - PMC
Aug 10, 2012 · The most common organism causing acute haematogenic osteomyelitis is Staphylococcus aureus (up to 95 %), followed by β-haemolytic Streptococcus ...
[71]
Bone and joint infections in children - Oxford Academic
Tuberculous osteomyelitis is infection of a long bone, or spine with Mycobacterium tuberculosis. There is caseation and granuloma formation. This infection ...
[72]
Osteosarcoma (Osteogenic Sarcoma) - StatPearls - NCBI Bookshelf
Dec 11, 2024 · Osteosarcoma, or osteogenic sarcoma, is the most common primary malignant bone tumor, accounting for approximately 20% of all cases.Missing: peak | Show results with:peak
[73]
[PDF] Bone tumors: osteosarcoma and Ewing's sarcoma
The most common malignant bone tumor in childhood and adolescence is osteosarcoma. It represents 15% of all primary bone tumors and 0.2% of all malignant tumors ...
[74]
Paget's Disease of Bone - Endotext - NCBI Bookshelf - NIH
Jan 4, 2020 · It is much easier to detect in the extremities, particularly when bowing of the femur and/or tibia is present (Figure 2).
[75]
Current concepts of leg lengthening - Carol C. Hasler, Andreas H ...
Introduction. Leg length discrepancies are frequent: about one-third of the population shows 0.5–1.5-cm disparities, 5 % more than 1.5 cm and about 1/1,000 ...
[76]
Updates in the Management of Leg Length Discrepancy - NIH
Closing the growth plate by the technique of epiphysiodesis is thought to be the best course of action for kids whose LLDs are expected to be between 2 and 5 cm ...