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Patella

The patella, commonly known as the kneecap, is the largest sesamoid bone in the human body, embedded within the tendon of the quadriceps femoris muscle anterior to the knee joint.^[1] It is a flat, inverted triangular bone with a broad superior base, a pointed inferior apex, and medial and lateral borders, featuring a posterior articular surface divided into seven facets (three medial, three lateral, and one odd facet) that articulate with the patellar groove of the femur to form the patellofemoral joint.^[2]^[1] The patella plays crucial roles in knee biomechanics, primarily by protecting the anterior knee joint from direct trauma and enhancing the efficiency of the quadriceps femoris muscle during knee extension.^[1] It increases the moment arm of the quadriceps tendon, providing up to 60% more torque in the final 15 degrees of extension, while also centralizing the pull of the quadriceps components (rectus femoris and vasti muscles) to improve force transmission to the tibia via the patellar ligament.^[1] Superiorly, it attaches to the quadriceps tendon, and inferiorly to the patellar ligament, which inserts on the tibial tuberosity, facilitating smooth flexion and extension movements essential for locomotion, standing, and weight-bearing activities.^[1]^[2] Developmentally, the patella originates from mesenchymal tissue around the ninth week of gestation, becoming cartilaginous by the fourteenth week and undergoing ossification centers that typically appear between ages 3 and 6, with full maturation by adolescence.^[1] Its blood supply arises from the genicular arteries (superior and inferior lateral and medial, descending genicular, and supreme genicular), forming a robust peripatellar anastomosis to support its metabolic demands, while innervation is provided by branches of several nerves including the femoral, genitofemoral, and obturator nerves.^[2]^[1] Clinically, the patella is susceptible to conditions such as fractures from high-impact trauma, instability or dislocation due to trochlear dysplasia or patella alta (where the patella sits abnormally high, measured by Insall-Salvati ratio >1.2), and chondromalacia patellae, which involves cartilage softening and is more prevalent in females, often requiring conservative management or surgical intervention to restore knee function.^[1]^[3]

Anatomy

Gross Structure

The patella, commonly known as the kneecap, is a triangular sesamoid bone located anterior to the knee joint, embedded within the quadriceps femoris tendon. It exhibits a flattened, triangular shape with its base oriented superiorly and apex directed inferiorly, measuring approximately 4.5 cm in length (range 3.8–5.3 cm), 4.7 cm in width (range 4–5.5 cm), and 2.3 cm in thickness on average in adults. These dimensions vary by sex, with males typically having a thicker patella (average 2.5–3 cm) compared to females, reflecting differences in overall skeletal robusticity.^[4]^[5] The anterior surface of the patella is convex and rough, providing attachment sites for the fibers of the quadriceps tendon, and is covered by a thin layer of periosteum beneath the subcutaneous tissue. In contrast, the posterior surface is primarily smooth and covered by articular cartilage, facilitating articulation with the femur; it features a posterior articular surface divided into seven facets (three medial, three lateral, and one odd facet) separated by a vertical ridge, with the proximal two-thirds to three-quarters participating in the patellofemoral joint while the distal portion remains non-articular and rough for ligamentous connections. The bone's borders include the superior base, which is thick and rounded for quadriceps integration; the inferior apex, from which the patellar ligament extends to the tibial tuberosity; and the medial and lateral margins, which are concave and converge toward the apex.^[6]^[1]^[2] Ossification of the patella begins postnatally with a single primary center appearing between 3 and 6 years of age, though a cartilaginous precursor forms in utero within the quadriceps tendon. This process starts as multiple foci that coalesce rapidly, with girls typically ossifying earlier (by age 4–5 years) than boys (up to age 6 years), contributing to the bone's mature gross structure by adolescence.^[7]^[8]^[9]

Microscopic Structure

The patella is classified as a sesamoid bone, embedded within the quadriceps tendon anterior to the knee joint, and develops through the ossification of fibrocartilage during postnatal growth.^[10] This process begins with cartilaginous precursors that undergo endochondral ossification, transforming fibrocartilaginous tissue into bone while maintaining integration with the surrounding tendon fibers.^[11] Microscopically, the patella features a dense outer layer of cortical bone, which is thicker on the anterior surface to provide enhanced protection against compressive forces from the overlying tendon and skin.^[12] This compact bone consists of lamellar organization with osteons aligned parallel to the surface, contributing to its resistance to bending and impact. The interior comprises cancellous bone, a spongy network of trabeculae that are oriented along principal stress lines, optimizing force transmission from the quadriceps to the patellar tendon during knee extension.^[13] The posterior aspect of the patella is covered by hyaline articular cartilage, a smooth, avascular tissue 2-4 mm in thickness that facilitates low-friction gliding against the femoral trochlea.^[14] This cartilage is stratified into four zones: a superficial tangential zone with flattened chondrocytes and parallel collagen fibers resisting shear; a middle transitional zone with rounded cells and random fiber orientation; a deep radial zone featuring columnar chondrocytes and perpendicular fibers for tensile strength; and a calcified zone that integrates with the subchondral bone plate via tidemarks.^[15] As a sesamoid structure fully embedded in the quadriceps tendon, the patella lacks an independent joint capsule; its posterior surface is instead lined by the synovial membrane of the knee joint, which secretes lubricating fluid into the patellofemoral compartment.^[16] This arrangement allows direct tendon-bone continuity without intervening capsular tissue.

Attachments and Relations

The patella is embedded anteriorly within the quadriceps tendon, which forms the primary superior attachment to the bone. This tendon arises from the quadriceps femoris muscle group, including the rectus femoris originating from the anterior inferior iliac spine and ilium, as well as the vastus medialis, vastus lateralis, and vastus intermedius muscles that arise from the femoral shaft. These components converge to insert onto the superior and anterior surfaces of the patella, creating a layered structure that enhances the mechanical leverage for knee extension. ^[1]^[17] Inferiorly, the patella connects to the tibia via the patellar ligament, a strong fibrous band extending from the apex and rough posterior surface of the patella to the tibial tuberosity. This ligament, essentially the continuation of the quadriceps tendon distal to the patella, transmits the contractile force of the quadriceps during knee extension, stabilizing the patellofemoral joint. The patella lies anterior to the knee joint capsule, with its posterior articular surface facing and articulating with the femoral condyles during flexion and extension movements. Inferior to the patella, the infrapatellar fat pad (Hoffa's fat pad) provides cushioning between the patellar ligament and the joint capsule, reducing friction and absorbing compressive forces. ^[1]^[18]^[19] The blood supply to the patella is derived from an anastomotic peripatellar arterial ring formed by the superior medial and lateral genicular arteries (both branches of the popliteal artery) and the inferior medial and lateral genicular arteries (branches of the popliteal artery), ensuring robust vascularization despite the bone's superficial position. Innervation primarily involves articular branches from the femoral nerve supplying the anterior aspect through the vastus medialis and vastus lateralis muscles, while sensory innervation to the posterior and lateral surfaces comes from the superior and inferior genicular nerves, which are branches of the femoral, common peroneal, and tibial nerves. Lymphatic drainage from the patella and surrounding knee structures flows to the popliteal lymph nodes located in the popliteal fossa, facilitating immune surveillance and fluid return from the lower limb. ^[20]^[21]^[22]^[23]

Development and Variation

Embryological Development

The patella originates from a mesenchymal condensation within the quadriceps tendon expansion, forming as a sesamoid bone through a process involving both endochondral and intramembranous ossification. This condensation first becomes discernible during O'Rahilly stage 19, approximately 6-7 weeks of gestation, as a dense blastema ventral to the femoral condyles. Mesenchymal proliferation occurs primarily between weeks 5 and 6, establishing the foundational precursor in the pre-patellar region. Chondrification of this mesenchymal precursor begins around week 8 (O'Rahilly stage 22-23), transforming the central portion into hyaline cartilage while the periphery undergoes intramembranous ossification. The cartilaginous anlage emerges distinctly by 8-10 weeks, with a fibrous band connecting it to the femur, and becomes fully formed by 12-14 weeks, resembling the adult shape with defined medial and lateral facets—initially equal in size, though the lateral facet enlarges by week 23. Vascular invasion into the cartilage model initiates primary endochondral ossification around month 4 (3-5 months) in utero, forming a single central ossification center, though the bone remains largely cartilaginous at birth.^[24]^[1] Postnatally, the ossification center is not radiographically visible until ages 3-6 years due to its delayed progression compared to other knee bones like the distal femur, which ossifies in utero by 3-6 months. This delay contributes to the patella's susceptibility to multipartite forms, where multiple ossification foci fail to fully fuse. Growth of the patella is influenced by mechanical stress from fetal knee movements and later postnatal activity, with ossification and modeling continuing until late adolescence, driven by tension in the quadriceps tendon.^[6]^[1]

Anatomical Variations

The patella exhibits notable anatomical variations in size, shape, position, and ossification patterns across individuals and populations, influencing its morphology without necessarily impacting function in most cases. These differences arise from genetic and developmental factors, including variations in homeobox (Hox) genes that regulate skeletal patterning during embryogenesis.^[25] Size variations in the patella are influenced by sex and ethnicity. The patella is generally smaller in females compared to males; for example, in a study of Vietnamese adults, average patellar heights were 3.81 cm in females and 4.3 cm in males, reflecting broader dimorphic patterns in knee anatomy. Ethnic differences also contribute.^[26]^[27] Patellar shape is commonly classified using the Wiberg system, which categorizes morphology based on the posterior articular facets. Type I features symmetrical medial and lateral facets that are both concave and of equal size; Type II shows a smaller medial facet that is often flat or slightly convex; and Type III displays a markedly hypoplastic medial facet with a prominent lateral facet, potentially increasing lateral patellar tilt. This classification aids in assessing congruence with the femoral trochlea.^[28] Positional variations include patella alta, characterized by a high-riding patella relative to the femur (often defined by an Insall-Salvati ratio >1.2), which is associated with an increased Q-angle exceeding 20° and may predispose to instability. Conversely, patella baja involves a low-riding patella due to a shortened patellar tendon, frequently occurring as a postoperative complication following procedures like total knee arthroplasty.^[29]^[30] Bipartite patella, a developmental variant resulting from failure of ossification centers to fuse, affects approximately 2% of the population and is more prevalent in males (9:1 ratio), often involving a superolateral accessory fragment connected by fibrocartilage. It is typically asymptomatic but can cause anterior knee pain, particularly under stress.^[31]^[32] Accessory ossicles near the patella, such as the fabella—a sesamoid in the lateral gastrocnemius tendon—occur in 10-30% of individuals and are distinct from patellar variants, serving as a separate stabilizer rather than part of the patella proper.^[33]

Function

Biomechanical Role

The patella serves as a critical sesamoid bone in the knee extensor mechanism, enhancing the lever arm of the quadriceps muscle to improve the efficiency of knee extension. By positioning the quadriceps tendon anterior to the femoral condyles, the patella increases the quadriceps moment arm by approximately 30% during knee flexion angles of 30-60°, with peak enhancement occurring around 45° of flexion. This geometric advantage can be approximated by the formula for the moment arm length:

\text{moment arm} = \text{patella height} \times \sin(\theta)

where \theta is the knee flexion angle, allowing for greater torque generation with less quadriceps force.^[34]^[35] In addition to lever arm enhancement, the patella facilitates force distribution across the patellofemoral joint, reducing the overall joint reaction force by up to 50% during knee extension compared to scenarios without the patella. This reduction occurs because the patella's pulley-like action optimizes force transmission, minimizing the quadriceps effort required for a given extension torque and thereby lowering compressive loads on the joint. The patellofemoral compressive force (PFCF) can be estimated using the approximation:

\text{PFCF} \approx \text{QF} \times \left(1 + \frac{L_q}{L_p}\right)

where QF is the quadriceps force, L_q is the quadriceps lever arm length, and L_p is the patellar tendon lever arm length; this model highlights how the patella balances forces to prevent excessive stress. Studies on patellectomy demonstrate that removal of the patella results in a 40% decrease in knee extension torque, underscoring the bone's role in maintaining mechanical efficiency.^[36]^[34] The patella also contributes to precise knee kinematics through its tracking mechanism, where the medial facet engages the trochlear groove of the femur to prevent lateral subluxation during flexion and extension. This contact ensures central alignment of the patella within the groove, distributing loads evenly and stabilizing the extensor mechanism against lateral deviation forces generated by the quadriceps. In cases of anatomical variations, such as Wiberg Type III patella (characterized by a hypoplastic medial facet), uneven force transmission may occur, potentially increasing the risk of early degenerative changes.^[37]

Protective and Stabilizing Functions

The patella functions as an anterior bony shield that dissipates the force of direct impacts to the knee, thereby protecting the underlying joint structures from trauma. By deflecting external forces, it reduces stress on the femoral condyles and articular cartilage, distributing loads over a larger contact area during weight-bearing activities. This protective role is particularly evident in dynamic scenarios such as falls or collisions, where the patella absorbs shock to prevent deeper injury to the patellofemoral compartment.^[38] In terms of joint stabilization, the patella engages with the femoral trochlear groove, effectively deepening the articulation and providing bony constraint against lateral subluxation as the knee flexes beyond 20-30 degrees. The vastus medialis obliquus (VMO) muscle exerts a medial pull on the patella via its attachments, countering varus and valgus forces to maintain alignment during weight-bearing and gait. This dynamic stabilization, combined with the medial and lateral patellar retinacula, contributes to overall knee stability in extension, with the patella accounting for approximately 30% of the extensor mechanism's torque at full extension; studies following patellectomy demonstrate increased anteroposterior instability, including greater anterior tibial translation.^[38]^[39]^[40] The patella also facilitates lubrication in the patellofemoral compartment by elevating the quadriceps tendon away from the femur, promoting synovial fluid flow and nutrient distribution to the articular surfaces. Additionally, mechanoreceptors within the patellar retinacula contribute to knee proprioception by providing sensory feedback on joint position and movement, though this role is secondary to the primary stabilizing ligaments like the ACL. Recent gait analysis research highlights the patella's contribution to reducing ACL strain during locomotion, with altered patellofemoral mechanics post-injury leading to increased ligament loading in dynamic tasks.^[38]^[41]^[42]

Clinical Significance

Dislocations and Instability

Patellar dislocations primarily involve the patella shifting laterally out of the femoral trochlea, accounting for approximately 90% of cases, and are most common in adolescents during first-time events often triggered by non-contact twisting injuries.^[43] Medial dislocations are rare, comprising less than 10% of incidents, and typically result from high-energy trauma such as direct lateral blows to the patella.^[44] The causes of patellar instability and dislocation include anatomical factors like shallow trochlear dysplasia, which reduces the groove's depth and containment of the patella; increased quadriceps angle (Q-angle, typically greater than 20°), increasing lateral pull on the patella; and laxity in the medial retinaculum, compromising medial stabilization.^[45]^[46] These predispositions are often exacerbated by acute trauma, such as internal rotation of the femur on a planted foot with knee flexion.^[47] Symptoms of acute patellar dislocation manifest as sudden, severe knee pain, often accompanied by hemarthrosis (bleeding into the joint space) leading to swelling and effusion.^[45] A positive patellar apprehension test, where lateral pressure on the patella during knee extension elicits fear of dislocation and reflexive quadriceps contraction, indicates underlying instability.^[48] Diagnosis begins with clinical evaluation, including assessment of patellar tilt and tracking, alongside a history of the injury mechanism.^[45] Imaging, particularly MRI, is essential to identify associated injuries such as medial patellofemoral ligament (MPFL) tears—present in 90% of lateral dislocations—and osteochondral fragments, which occur in 50-70% of cases and may require intervention to prevent long-term joint damage.^[49] Non-surgical management for first-time dislocations involves closed reduction under sedation, followed by immobilization with a knee brace for 4-6 weeks to allow soft tissue healing, and physical therapy emphasizing vastus medialis obliquus (VMO) strengthening to improve medial stability and patellar tracking.^[44] For recurrent instability, surgical options include MPFL reconstruction, which has shown lower recurrence rates compared to repair; 2024 studies indicate repair yields a 41% redislocation rate at long-term follow-up versus 14% for reconstruction.^[50] In cases of severe trochlear dysplasia, trochleoplasty reshapes the trochlear groove to enhance patellar containment, significantly improving quality of life and reducing redislocation risk.^[51] Overall, recurrence rates after first-time dislocations range from 15-60%, with higher risks in younger patients and those with predisposing anatomical variations.^[45]

Fractures and Trauma

Patellar fractures represent approximately 1% of all skeletal fractures and typically result from high-energy trauma disrupting the bone's integrity and the knee's extensor mechanism. These injuries are classified based on the fracture pattern and articular involvement using the AO/OTA system, which categorizes them as Type A (extra-articular, often involving the superior or inferior pole), Type B (partial articular, such as marginal fractures), and Type C (complete articular, including transverse or comminuted patterns).^[52] The primary mechanisms of patellar fractures include direct trauma, accounting for about 40% of cases, such as a fall onto a flexed knee or a dashboard injury in motor vehicle collisions, which often produces comminuted fractures.^[52] Indirect mechanisms, comprising the remaining cases, arise from sudden quadriceps contraction against a fixed flexed knee, leading to transverse fractures in roughly 50% of instances.^[52] Less commonly, vertical or stellate fractures occur in about 25% of cases, while osteochondral fractures may result secondarily from patellar dislocation.^[52] Patients with patellar fractures commonly present with acute knee pain, significant swelling due to hemarthrosis, inability to actively extend the knee, and a palpable gap or defect at the fracture site.^[53] Acute management prioritizes restoring the extensor mechanism and articular congruence. Nondisplaced fractures, defined as those with less than 2-3 mm of displacement or separation and an intact extensor mechanism, are treated nonoperatively with immobilization in extension for 4-6 weeks followed by progressive rehabilitation.^[52] Displaced or unstable fractures require surgical intervention; transverse fractures are typically fixed with tension band wiring to convert tensile forces into compression, while comminuted fractures may necessitate partial patellectomy with reattachment of the quadriceps and patellar tendons.^[52] Complications include nonunion or delayed union in 2-5% of cases, primarily due to avascular fragments in the watershed region of the patella's blood supply.^[54] Recent advancements as of 2025 include bioabsorbable fixation techniques, such as resorbable screw-augmented suture methods, which have demonstrated favorable radiographic union rates (100% at 12 months) and functional outcomes (mean Lysholm score of 92) with reduced hardware-related symptoms compared to metallic implants.^[55] Additionally, 3D-printed titanium alloy anatomical plates have shown superior biomechanical stability in finite element analyses for various fracture patterns, potentially improving fixation in complex cases, though long-term clinical outcomes remain under evaluation.^[56]

Degenerative and Overuse Conditions

Patellofemoral pain syndrome (PFPS), also known as runner's knee, is a prevalent chronic condition characterized by diffuse anterior knee pain, often resulting from patellar maltracking, abnormal patellofemoral joint loading, or repetitive overuse activities such as running and squatting.^[57] It affects approximately 25% of young adults, with a higher prevalence of 28.9% among adolescents, and is particularly common in runners, where incidence rates range from 20% to 30% due to increased biomechanical stress on the patellofemoral joint.^[58]^[59] MRI may reveal subtle signs of cartilage irritation or trochlear dysplasia and is used to rule out other pathologies.^[60] Chondromalacia patellae refers to the softening and degeneration of the articular cartilage on the posterior surface of the patella, leading to pain and crepitus during knee flexion.^[61] This condition is graded using the Outerbridge classification, which ranges from grade I (superficial fibrillation and softening) to grade IV (full-thickness cartilage loss exposing subchondral bone), allowing clinicians to assess severity and guide management.^[62] It commonly arises from overuse in active individuals, contributing to patellofemoral dysfunction without initial bony changes.^[63] Patellofemoral osteoarthritis involves progressive wear of the cartilage in the patellofemoral compartment, resulting in pain, stiffness, and reduced mobility, often isolated or as part of generalized knee osteoarthritis.^[64] Key risk factors include obesity, which increases mechanical load on the joint (with individuals having a BMI over 30 kg/m² being 6.8 times more likely to develop knee osteoarthritis), and prior trauma that alters joint alignment or initiates degenerative cascades.^[65] This form of osteoarthritis can exacerbate anterior knee pain and is more prevalent in middle-aged adults with repetitive knee-loading occupations or sports.^[66] Osgood-Schlatter disease, an overuse-related apophysitis, affects the tibial tuberosity where the patellar tendon inserts, causing painful swelling and prominence in adolescents during growth spurts.^[67] It typically occurs between ages 10 and 15, more frequently in boys and athletes involved in jumping or running sports, due to repetitive traction forces from quadriceps contraction on the immature apophysis.^[68] Symptoms often resolve with skeletal maturity, but residual tuberosity prominence may persist.^[69] Management of these degenerative and overuse conditions begins with conservative approaches, including nonsteroidal anti-inflammatory drugs (NSAIDs) for pain relief, patellar taping or bracing to improve tracking, and physical therapy focused on quadriceps strengthening and hip stabilization.^[70] For persistent chondromalacia or early osteoarthritis, arthroscopic debridement removes fibrillated cartilage and loose fragments, providing symptomatic relief in up to 80% of selected patients with grade III or IV lesions. In advanced patellofemoral osteoarthritis, total knee arthroplasty resurfaces the joint, offering significant pain reduction and functional improvement, particularly when isolated patellofemoral replacement is not feasible. Recent advancements include biologic therapies such as platelet-rich plasma (PRP) injections, which deliver growth factors to promote cartilage repair and reduce inflammation; systematic reviews from 2023-2024 indicate PRP provides clinically meaningful pain relief and functional gains lasting up to 12 months in PFPS and early osteoarthritis, outperforming hyaluronic acid in some cohorts.^[73]^[74] Gait retraining protocols, emphasizing increased cadence (7.5-10%) and reduced knee valgus, have shown efficacy in alleviating PFPS symptoms in runners, with pain reductions maintained at six-month follow-ups when combined with exercise.^[75]^[76] These interventions prioritize load management and biomechanical correction to prevent progression.^[77]

Comparative and Evolutionary Aspects

Presence in Other Animals

The patella exhibits considerable morphological variation across mammals, reflecting adaptations to diverse locomotor strategies. In primates, including humans, it is a large, distinct sesamoid bone embedded in the quadriceps femoris tendon, enhancing knee extension leverage during bipedal locomotion.^[78] In contrast, carnivores such as dogs possess a reduced patella that is small and embedded deeply within the tendon, providing minimal protrusion while still contributing to stifle joint stability.^[78] The patella is absent as an ossified structure in certain rodents, such as guinea pigs, where a fibrous analog embedded in the tendon serves a comparable supportive role without bony development.^[78] Similarly, most reptiles and non-avian birds lack a true ossified patella; instead, knee extension relies on a robust patellar ligament and fibrous tissues, with independent origins of a bony patella occurring in some squamate lizards and select avian lineages like ostriches.^[79]^[80] In quadrupedal mammals, the patella assumes a less prominent role in weight-bearing compared to bipeds due to differences in posture, yet it facilitates efficient limb extension; for instance, in horses, the patella is elongated and participates in the "locking" mechanism of the stifle joint, aiding cursorial locomotion and prolonged standing without muscular effort.^[81] Elephants feature a standard patella in the knee alongside multiple additional sesamoid bones, including medial and lateral fabellae, which collectively enhance extensor mechanism efficiency and mimic expanded patellar support during weight-bearing. Fossil evidence documents the ossified patella's evolution within crown-group Mammalia, with the earliest confirmed appearances in the early Cretaceous (approximately 125 million years ago) and Paleocene (around 66 million years ago).^[78] Among basal mammals, monotremes such as the platypus possess a small but fully ossified patella, while in marsupials, the structure is typically fibrocartilaginous (a "patelloid") at birth, with ossification occurring postnatally in some species like certain macropods.^[78]^[82]

Evolutionary Origins

The patella, a sesamoid bone embedded in the quadriceps tendon, traces its evolutionary origins to early vertebrate structures, with sesamoid bones appearing in the tendons of fish and amphibians as fibrous or cartilaginous precursors that provided biomechanical support at joints.^[81] These precursors likely facilitated tendon protection and force transmission in ancestral tetrapods, emerging around 350 million years ago during the transition from aquatic to terrestrial locomotion, though direct fossil evidence for a knee-specific sesamoid is sparse in Devonian forms.^[81] Ossification of the patella occurred independently in multiple tetrapod lineages, reflecting homoplasy driven by similar selective pressures for enhanced knee extension efficiency. In the synapsid lineage leading to mammals, the patella remained absent or unossified in non-mammalian forms, with strong fossil evidence indicating no bony patella in pre-mammalian cynodonts from the Triassic and Jurassic periods.^[78] Ossification evolved multiple times within crown-group Mammalia, likely between four and six instances, including in monotremes, multituberculates, and placental lineages, with the earliest confirmed fossil patellae appearing in Paleocene mammals around 66 million years ago.^[81] This transition from fibrous to bony forms in synapsids coincided with adaptations for more efficient terrestrial locomotion, though the precise timing remains inferred from comparative anatomy due to limited Mesozoic mammal fossils. In contrast, the patella is absent in the fossil record of non-avian dinosaurs, despite their bipedal habits, suggesting it was not a prerequisite for upright posture in that clade.^[81] The adaptive significance of the patella's evolution is tied to its role in amplifying the quadriceps' moment arm, which increases leverage for knee extension and reduces tendon stress during locomotion—a key advantage for bipedalism in primates.^[81] In primate evolution, this structure enhanced stability and efficiency in upright postures, emerging independently in strepsirrhines and haplorhines to support extended hindlimb propulsion.^[81] Among archosaurs, the patella evolved separately in birds, originating as a small sesamoid in the femorotibialis externus tendon during the Cretaceous, absent in basal archosaurs and non-avian dinosaurs but present in many modern avian species for flight and perching demands.^[83] Developmentally, the patella arises from Sox9-positive and Scx-positive chondroprogenitors in the tendon, regulated by BMP4 and TGFβ signaling pathways that promote condensation and ossification independently of mechanical load in early stages.^[84] This genetic framework underscores the homoplastic nature of patella evolution across vertebrates, where conserved pathways enabled recurrent ossification in response to locomotor innovations.^[85]

History and Terminology

Historical Descriptions

The earliest known descriptions of the patella appear in ancient Greek medical texts, where Hippocrates around 400 BCE referred to it as the "kneecap" and noted its propensity for dislocations, describing such injuries as easily reducible through manual manipulation.^[86] In the Roman era, Aulus Cornelius Celsus in the 1st century CE introduced the term "patella," likening the bone's shape to a small dish or pan, marking its first anatomical nomenclature in Latin literature.^[87] Galen, in the 2nd century CE, expanded on these observations by classifying it among sesamoid bones that enhance tendon leverage across joints. Non-Western traditions also contributed early insights into knee anatomy, as evidenced in the Sushruta Samhita, an ancient Indian surgical text from around the 6th century BCE, which describes the knee joint's structure and its vulnerability to trauma from falls or overuse.^[88] During the Renaissance, Andreas Vesalius advanced anatomical understanding in his seminal 1543 work De Humani Corporis Fabrica, providing detailed illustrations of the patella as the body's largest sesamoid bone, highlighting its role in protecting the knee and facilitating quadriceps force transmission.^[89] In the 18th century, Scottish surgeon John Hunter contributed significantly to the study of patellar pathology through pathological specimens, including a fractured patella from a policeman's knee injury, which he used to demonstrate the bone's vulnerability to trauma and the resulting degenerative changes in the joint.^[90] Surgical interventions began to evolve, with Belgian surgeon Thirion performing the first recorded patellectomy in 1829 for patella osteomyelitis, removing the bone to address infection despite concerns over quadriceps weakness.^[91] The 20th century saw further refinements in diagnosis and treatment. The discovery of X-rays by Wilhelm Röntgen in 1895 revolutionized patellar fracture assessment, enabling precise visualization of displacement and fragmentation that was previously reliant on palpation alone.^[92] For instability, the Roux-Goldthwait procedure, initially described in the late 19th century but modified in the 1910s, addressed recurrent dislocations by rerouting the patellar tendon to enhance medial stability, serving as an early non-bracing surgical option.^[93] By the 1950s, Friedrich Pauwels introduced tension band wiring for transverse patellar fractures, a technique that converts tensile forces into compressive stability across the fracture site, markedly improving outcomes over prior wiring methods.^[94] In the 2020s, advancements in imaging have incorporated artificial intelligence to automate patellofemoral measurements, such as patellar height and sulcus angle from radiographs, CT, and MRI, achieving high accuracy comparable to radiologists and aiding early detection of instability or malalignment.^[95]

Etymology

The term patella, denoting the kneecap, derives from Latin patella, a diminutive form of patina, meaning "small pan," "shallow dish," or "plate," reflecting the bone's flattened, dish-like shape.^[96]^[97] This anatomical usage was introduced by the Roman encyclopedist Aulus Cornelius Celsus in the early 1st century CE, marking its transition from a general descriptor to a specific medical term in classical literature.^[98]^[99] In ancient Greek, the kneecap was referred to as epigonatis (ἐπιγόνατις), literally "upon the knee," emphasizing its position over the knee joint. Aristotle, in his History of Animals (ca. 350 BCE), described it as mylē (μύλη), or "millstone," alluding to its role within the tendon while noting its bony nature in the knee's sliding mechanism.^[100] Across other languages, descriptive terms highlight the bone's form or function. In English, "kneecap" emerged in the mid-17th century as a compound of "knee" and "cap," initially denoting a protective covering before shifting to the bone itself by the late 19th century.^[101] The French rotule (kneecap) stems from Medieval Latin rotula, meaning "small wheel," evoking its rounded, pivoting articulation.^[102] In Sanskrit, it is known as jānukapālikā (कnee-protector) or jānuphalaka (कnee-pan), terms used in ancient Ayurvedic texts to describe its shielding role.^[103] Medieval Arabic medical writings, such as those in the tradition of Ibn Sina, employed ar-raḍfa (الرضفة), meaning "the small plate" or "lid," paralleling the Latin etymology.^[104] The nomenclature evolved from these shape-based descriptors in antiquity to a standardized anatomical term by the 18th century, as seen in European texts like Albrecht von Haller's Elementa Physiologiae (1757–1766), where patella became the conventional Latin label in systematic anatomy.^[105] Additionally, the patella is classified as a sesamoid bone, a term derived from Greek sēsamoeidēs ("sesame-like"), coined in the late 17th century to describe small, seed-shaped bones embedded in tendons; its application to the patella solidified in 19th-century comparative anatomy.^[106]

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The patella initially ossifies at between three and five years, commencing as multiple foci that rapidly coalesce. As the patellar ossification center ...
[8]
The age of patella ossification - EPOS™
The overall range of patella ossification age is 2-6 years however, there is a clear gender difference with all girls having ossified patellae before their 5th ...Purpose · Methods And Materials · Results
[9]
U.K. team determines age of patella ossification | AuntMinnieEurope
The ranges for patella ossification were between 2 and 6 years for boys and 2 to 4 years for girls. Also, 96% of the female patellae were ossified before the ...<|control11|><|separator|>
[10]
Computational model for the patella onset | PLOS One
Dec 11, 2018 · ... ossification of the cartilage to form the patella. According to the ... fibrocartilage, or even bone show up in the previous site of the patella.
[11]
Bipartite Patella - Pediatrics - Orthobullets
Oct 12, 2022 · ossification. males at 4-5 years old. females at 3 years old. accessory ossification center appears between 8-12 years. separate fragment ...
[12]
Sesamoid bones also show functional adaptation in their ...
Aug 16, 2021 · The patella is the largest sesamoid bone of the skeleton. It is strongly involved in the knee, improving output force and velocity of the knee extensors.
[13]
Regional variations in human patellar trabecular architecture and ...
The gross anatomy of the attachment of the quadriceps and patellar tendons to the patella is shown in Fig. 1. Note that the oblique fibres of vastus medialis ...
[14]
The Basic Science of Articular Cartilage - NIH
Articular cartilage is hyaline cartilage and is 2 to 4 mm thick. Unlike most tissues, articular cartilage does not have blood vessels, nerves, or lymphatics. It ...
[15]
Articular Cartilage - Basic Science - Orthobullets
Normal articular cartilage is composed of three zones and the tidemark zones based on the shape of the chondrocytes and the orientation of the type II collagen.
[16]
Anatomy, Sesamoid Bones - StatPearls - NCBI Bookshelf
Apr 4, 2023 · The patella is an anomaly among sesamoid bones due to its consistent presence, size, and significance in humans.
[17]
https://www.ncbi.nlm.nih.gov/books/NBK513334/
[18]
Anatomy, Bony Pelvis and Lower Limb: Thigh Quadriceps Muscle
The most superficial fibers of the tendon continue and cover the patella, inserting on the tibial tuberosity called the patellar ligament.<|control11|><|separator|>
[19]
Patellar tendon | Radiology Reference Article - Radiopaedia.org
Aug 14, 2025 · ... patella itself is a sesamoid bone embedded in the quadriceps tendon 1,2. ... superior and inferior lateral genicular arteries, branches of ...
[20]
UPDATING OF THE ANATOMY OF THE EXTENSOR MECHANISM ...
The medial and lateral inferior genicular arteries issue branches to feed the patella, Hoffa's fat pad and the patellar tendon. These two arteries each divide ...
[21]
Vascular supply at risk during lateral release of the patella ... - NIH
Nov 24, 2017 · The patella is vascularized by a highly anastomotic ring that is supplied by five genicular arteries (inferior medial, inferior lateral, ...
[22]
The Patellar Arterial Supply via the Infrapatellar Fat Pad (of Hoffa)
Mar 21, 2012 · The two superior genicular arteries run along the superior pole of the patella forming an anastomosis together with the descending genicular ...
[23]
Denervation of the Patella During Knee Arthroplasty - PubMed Central
Nov 18, 2024 · Specifically, the patella is innervated by the lateral and medial superior genicular nerves, which are principal contributors to postoperative ...
[24]
Anatomy, Bony Pelvis and Lower Limb, Knee - StatPearls - NCBI - NIH
Nov 5, 2023 · The quadriceps tendon attaches the quadriceps to the patella. Knee extensors are the main muscular stabilizers of the knee joint and include ...
[25]
https://pmc.ncbi.nlm.nih.gov/articles/PMC6461774/
[26]
Genetics of the patella - PMC - PubMed Central - NIH
Jan 21, 2019 · Developmentally, the patella is not yet ossified at birth in humans and in other organisms that have been studied (mouse, rabbit, chick). In ...
[27]
Three-dimensional Morphology of the Knee Reveals Ethnic ...
Males had larger knees, with a mean 5-mm-larger anteroposterior dimension than females in all ethnicities. African American females had a 7.4-mm-deeper patellar ...
[28]
Morphologic Evaluation of the Patella: The Impact of Gender and Age
Feb 14, 2024 · The mean patellar joint angle was 128.3 ± 8.20 degrees. The average patellar height was 4.07 ± 0.35 cm.
[29]
Wiberg classification of patella shape | Radiology Reference Article
Aug 21, 2025 · Wiberg classification is a system used to describe the shape of the patella based mainly on the asymmetry between the patellar medial and lateral facets.
[30]
Patella alta | Radiology Reference Article | Radiopaedia.org
Mar 9, 2025 · Patella alta, or a high-riding patella, describes a situation where the position of the patella is considered high. It may be idiopathic or ...Insall-Salvati ratio · Medial patellofemoral ligament... · Question 1840
[31]
Patella Baja - Physiopedia
Patella baja is defined by an abnormally low position of the patella in relation to the femoral trochlea, typically resulting from a shortened patellar tendon ...
[32]
Bipartite patella | Radiology Reference Article | Radiopaedia.org
May 17, 2025 · Bipartite patella occurs in approximately 2% of the population, and occurs bilaterally in about 43% of cases. It is 9 times more common in males ...
[33]
Bipartite Patella in an Elite Football Player – A Rare Cause of ... - NIH
Bipartite patella is usually an asymptomatic anatomical variant estimated to have a prevalence of 0.2–6% in an adult population. A 28-year-old league-level ...Missing: 2020-2025 | Show results with:2020-2025
[34]
Fabella | Radiology Reference Article | Radiopaedia.org
It occurs in ~20% (range 10-30%) of the population 1. The fabella can also be fibrocartilaginous in nature and is occasionally found in the medial head of the ...Missing: prevalence | Show results with:prevalence
[35]
Biomechanics of the Patello-Femoral Joint
The patella increases the mechanical advantage of extensor muscles, transmits tensile forces, and increases the lever arm of knee extension, with contribution ...Missing: 30-50% 30-60°
[36]
Moment arm of the patellar tendon in the human knee - PubMed
Peak values of the patellar tendon moment arm ranged from 4-6 cm for the six knees tested; the moment arm was maximum near 45 degrees of knee flexion.Missing: height × sin( θ)
[37]
A study of quadriceps excursion, torque, and the effect of ... - PubMed
Patellectomy decreased excursion of the quadriceps to 51.3 +/- 1.30 millimeters from zero to 90 degrees of knee flexion. Torque was decreased by roughly 40 per ...
[38]
Patellar maltracking: an update on the diagnosis and treatment ...
Jun 14, 2019 · Patellar maltracking occurs as a result of an imbalance in the dynamic relationship between the patella and trochlea.
[39]
A finite element analysis of patellofemoral joint biomechanics
Aug 29, 2024 · This study aimed to elucidate the mechanism of anterior knee pain after UKA by examining the biomechanical characteristics of the patellofemoral joint.Missing: wiberg classification
[40]
BIOMECHANICS AND PATHOMECHANICS OF THE ... - NIH
During open chain knee motion, the patella follows the path of the tibia due to the distal insertion of the patellar tendon to the tibial tubercle. The patella ...
[41]
VMO Part I: The True Key to Patella Stabilization?
For many years, it has been believed that the primary role of the VMO is to not only contribute to knee extension torque but also to provide medial patella ...
[42]
Patellar reconstruction following previous patellectomy - RCSEng
Mar 2, 2017 · Kwong and Desai reported an 85% complication rate in their series of seven arthroplasties with simultaneous trabecular metal patellar implants.
[43]
The Effects of Patellar Taping on Knee Joint Proprioception - PMC
Some studies have shown that patellar taping helps to decrease pain in patients with PFPS 2 and in patellofemoral osteoarthritis.
[44]
Patellofemoral contact forces and knee gait mechanics 3 months ...
It could be that the thicker patellar cartilage, compared to trochlear, may provide the patella with more protection from post-surgical biomechanical and ...
[45]
Management of Patellar Dislocations | POGO Physio Gold Coast
Jun 13, 2022 · It is estimated that 90% of lateral patellar dislocations occur during a non-contact twisting injury, such as a sudden lateral cut. The most ...
[46]
Patella Dislocation - StatPearls - NCBI Bookshelf - NIH
Jul 4, 2023 · Acute patellar dislocations typically occur as a result of trauma, usually a non-contact twisting injury to the knee, or from a direct blow to the medial ...Continuing Education Activity · Evaluation · Treatment / Management · Prognosis
[47]
Patellar Instability - Knee & Sports - Orthobullets
Jul 13, 2025 · Patellar-femoral bony structures account for stability in deeper knee flexion.trochlear groove morphology, patella height, patellar tracking.
[48]
Patellar Instability - StatPearls - NCBI Bookshelf - NIH
Lateral patellar tracking will eventually flatten the trochlear groove leading to patellar instability. Regardless of the cause, trochlear dysplasia results in ...
[49]
Lateral patellar dislocation | Radiology Reference Article
Mar 25, 2025 · Patellar dislocation most commonly results from a twisting motion, with the knee in flexion and the femur rotating internally on a fixed foot ( ...Trochlear dysplasia · Tibial tuberosity to trochlear... · Sliver sign (patella)
[50]
Patellar Apprehension Sign - Physiopedia
When a patient expresses apprehension or try to move their affected knee away from the pressure, this indicate a positive sign. This is a sound test to find out ...
[51]
Patellar Dislocation (Acute)
Osteochondral injury as a result of patellar dislocation ranges from 5% to 50%, although Seeley reported an incidence as high as 73% (Seeley, 2013). Treatment:.Patellar Dislocation (acute) · Imaging Studies · Treatment
[52]
Comparison of Failure Rates at Long-term Follow-up Between MPFL ...
Jan 8, 2024 · MPFL repair resulted in a nearly 3-fold higher rate of recurrent patellar dislocation (41% vs 14%) at the long-term follow-up compared with MPFL reconstruction.
[53]
Trochleoplasty for severe trochlear dysplasia significantly improves ...
Trochleoplasty is an effective surgical technique which improves the QoL in patients suffering from patellar instability secondary to severe trochlear ...
[54]
Patella Fracture - Trauma - Orthobullets
Jul 7, 2025 · Patella Fractures are traumatic knee injuries caused by direct trauma or rapid contracture of the quadriceps with a flexed knee that can lead to ...
[55]
Patella Fractures - StatPearls - NCBI Bookshelf - NIH
Jul 31, 2023 · At the time of diagnosis, forty-four percent of patients with atraumatic periprosthetic patellar fractures complained of minimal or no symptoms.
[56]
The management of nonunion and delayed union of patella fractures
The incidence of nonunion or delayed union of patella fractures is rare and ranges from 2.7–12.5% [1] (Table 1). The treatment of this complication is fraught ...
[57]
Radiographic and Functional Outcomes Following Resorbable ... - NIH
Oct 6, 2024 · Results · Figure 4. Radiograph of a mid-pole transverse patellar fracture fixed with a resorbable screw-augmented suture technique. · Table 1.
[58]
Biomechanical comparison of using traditional and 3D-printed ...
Sep 24, 2024 · FE analysis showed that the AATBP biomechanical performance was better than the ASP fixation for different patella fractures. The 3D-printed ...2. Materials & Methods · 3. Results · 4. Discussion<|control11|><|separator|>
[59]
Patellofemoral Syndrome - StatPearls - NCBI Bookshelf - NIH
Patellofemoral syndrome (PFS) is one of the most common causes of anterior knee pain. It is commonly known as runner's knee, patellofemoral pain syndrome, ...
[60]
Incidence and prevalence of patellofemoral pain: A systematic ... - NIH
Annual prevalence for patellofemoral pain in the general population was reported as 22.7%, and adolescents as 28.9%.
[61]
PREVALENCE OF ANTERIOR KNEE PAIN IN 18–35 YEAR-OLD ...
A prevalence rate of 25% has been commonly cited in the literature. However, this rate may be more anecdotal than empirical.<|control11|><|separator|>
[62]
Knee Pain due to Patellofemoral Disorders & Treatments - HSS
Patients who have a tracking problem in the patellofemoral joint – the patella does not stay in the groove on the femur – are vulnerable to a spectrum of ...Introduction · Patellofemoral Pain Syndrome · Surgery For Kneecap...
[63]
Chondromalacia Patella - StatPearls - NCBI Bookshelf - NIH
... (Outerbridge grade II, III, and IV chondromalacia patellofemoral joint).[24] ... Staging. Outerbridge classification of chondromalacia patellae (5 grades from 0 to ...Etiology · Evaluation · Treatment / Management · Staging
[64]
Classifications in Brief: Outerbridge Classification of Chondral Lesions
Grade I chondral lesions are characterized by softening and swelling, which often require tactile feedback with a probe or other instrument to assess. A Grade ...
[65]
Chondromalacia patellae: current options and emerging cell therapies
Jul 18, 2021 · Chondromalacia patellae (CMP), also known as runner's knee, typically occurs in young patients, which is characterized by anterior knee pain ...
[66]
Knee osteoarthritis prevalence, risk factors, pathogenesis and features
Age, weight, trauma to joint due to repetiting movements in particular squatting and kneeling are common risk factors of knee OA. Several factors including ...
[67]
Obesity & osteoarthritis - PMC - PubMed Central - NIH
Obesity is the greatest modifiable risk factor for OA4,5,6. Coggon et al7 reported that subjects with a BMI>30 kg/m2 were 6.8 times more likely to develop knee ...Missing: Patellofemoral | Show results with:Patellofemoral
[68]
Mechanical and constitutional risk factors for symptomatic knee ...
Results: Independent risk factors for knee OA included obesity (odds ratio [OR] 3.3; 95% confidence intervals [95% CI] 1.6-6.9), previous knee injury (OR 3.4; ...Missing: trauma | Show results with:trauma
[69]
Osgood-Schlatter Disease - StatPearls - NCBI Bookshelf - NIH
Osgood Schlatter disease, also known as osteochondrosis or traction apophysitis of the tibial tubercle, is a common cause of anterior knee pain in the ...Continuing Education Activity · Introduction · Etiology · Treatment / Management
[70]
Pathogenic Factors Associated With Osgood-Schlatter Disease in ...
Aug 28, 2018 · OSD is traction apophysitis resulting from the repeated contraction of the quadriceps femoris muscle on the tibial tuberosity. The onset of OSD ...
[71]
Osgood-Schlatter disease: a 2020 update of a common knee ...
OSD is a mostly self-limiting apophysitis of the tibial tubercle and the adjacent patella tendon in young active patients with open physis.Missing: tuberosity | Show results with:tuberosity
[72]
Patellofemoral Pain Syndrome - AAFP
Jan 15, 2019 · The patella acts as a lever within the leg, decreasing the ... force and is therefore of particular importance in stabilizing the patella.
[73]
Arthroscopic debridement for grade III and IV chondromalacia of the ...
This study evaluates the success of arthroscopic debridement in elderly patients with grade III and IV chondromalacia of the knee as measured by patient ...
[74]
Total knee replacement for patients with patellofemoral arthritis
Total knee replacement resulted in better outcomes for older patients with patellofemoral arthritis as compared with patellofemoral replacement, debridement ...
[75]
The Role of Platelet-Rich Plasma (PRP) in the Treatment of ...
Sep 16, 2025 · All five included studies demonstrated that PRP treatment led to clinically meaningful improvements in pain and/or function in symptomatic ...
[76]
Platelet-Rich Plasma for Knee and Hip Osteoarthritis Pain - NIH
Jul 13, 2024 · The main finding of this study was that PRP therapy improved pain and function irrespective of knee OA stage, compared to control group ...
[77]
Gait Retraining Programs: Pain, Function, Kinematics
Jan 10, 2024 · Gait retraining programs that increased cadence by 7.5–10% reduced pain levels post-training [13–17], and results were maintained six-months [17] ...
[78]
A Systematic Review With Network Meta-analysis - jospt
Nov 17, 2023 · Techniques including gait retraining and dynamic knee valgus corrections, are frequently applied during PFP rehabilitation. This is a reasonable ...
[79]
Running Retraining Technique and Neuromuscular Exercises ... - NIH
Aug 1, 2025 · When treating runners with patellofemoral pain (PFP), clinicians aim to reduce patients' symptoms, such as pain and discomfort.
[80]
Evolution of the patellar sesamoid bone in mammals - PMC - NIH
Mar 21, 2017 · In maturity, the patella is composed of an outer lamellar cortex enclosing an inner cancellous bone structure with marrow spaces, and has an ...
[81]
Anatomy, morphology and evolution of the patella in squamate ...
The patella (kneecap) is the largest and best‐known of the sesamoid bones, postulated to confer biomechanical advantages including increasing joint leverage.Missing: patagium | Show results with:patagium
[82]
Structure, ontogeny and evolution of the patellar tendon in emus ...
Dec 23, 2014 · The patella (kneecap) exhibits multiple evolutionary origins in birds, mammals, and lizards, and is thought to increase the mechanical ...
[83]
Evolution of the patellar sesamoid bone in mammals - PeerJ
Mar 21, 2017 · A bony patella is absent in extinct early Tetrapoda and crown ... fossil evidence (absence or equivocality of a patella in all outgroups).
[84]
Evolution of the patella and patelloid in marsupial mammals - PMC
Aug 19, 2020 · We found novel evidence of an ossified patella in one specimen of Macropus rufogriseus (Bennett's wallaby), with hints of similar variation in other species.
[85]
(PDF) Structure, ontogeny and evolution of the patellar tendon in ...
Aug 10, 2025 · Our reconstructions suggest a single evolutionary origin of the patella in birds and that the ancestral patella is likely to have been a ...
[86]
On the development of the patella - Company of Biologists journals
May 15, 2015 · The patella increases the distance between the quadriceps muscle and the knee and thereby increases the moment arm of the muscle, enhancing ...
[87]
Common cellular origin and diverging developmental programs for ...
Highlighted Article: Sesamoid bones originate from pools of Sox9+/Scx+ chondroprogenitors, and a combination of genetic and mechanical regulatory programs.<|control11|><|separator|>
[88]
Hippocrates: A Pioneer in Orthopaedics and Traumatology
Nov 18, 2023 · He referred also to patellar dislocation, as an easily reduced injury. Wrist Dislocation. Four directions of wrist dislocation were described ...
[89]
(DOC) Some Fascinating Anatomical Etymologies - Academia.edu
The term was introduced in its anatomical sense by Aurelius Celsus in the first century A.D.4 Fig.-11: A Roman patella. From the Fig.-12: An 18th century Arab ...
[90]
Sesamoid bones of the hand: A multicenter study - PMC - NIH
Sesamoid bones (SBs) are the skeletal variations of the hand and foot that were first described by Galen.[1] They are mostly located on the hands and feet ...Missing: attachments | Show results with:attachments
[91]
Critical review of Anatomy of Knee joint and its Clinical aspects in ...
Dec 31, 2019 · The knee joint is the largest and complex joint of the body. In Sandhigata Vata the vitiated Vata consequences in Asthi Ksaya. Osteoarthritis is ...
[92]
andreas vesalius of brussels - jstor
Vesalius [Fabrica. (1543), I: xxvi: 120] recognises that there is much to ... digital bones, not forgetting the sesamoid ossicles. These are wrapped in.
[93]
John Hunter and the origins of modern orthopaedic research<link ...
Preserved in the Hunterian Museum is the patella of a policeman who had earlier injured his knee in a fall (Fig. 3). It shows the damage caused by the trauma, ...
[94]
Early history of operative treatment of patellar fractures - PubMed
The presented overview shows that the first efforts to address patellar fractures by operative treatment, although sporadic, emerged in the pre-antiseptic era.
[95]
Early history of operative treatment of fractures - ResearchGate
Aug 7, 2025 · Development of operative treatment of fractures was influenced by three major inventions: anaesthesia (1846), antisepsis (1865) and X-rays (1895).
[96]
Treatment of Recurrent Patellar Instability with a Modification of the ...
Aug 5, 2025 · The Roux-Goldthwait procedure, first described by both Roux 162 and Goldthwait 163 in 1888 and 1895 respectively, was later modified in 1985 to ...Missing: Hey 1829
[97]
Evolution in the Management of Patella Fractures - PMC - NIH
Feb 29, 2024 · Non-union or delayed union in closed, operatively treated patella fractures is rare, with one series reporting a rate of less than 1% [67].
[98]
Performance of artificial intelligence in automated measurement of ...
Sep 26, 2025 · This systematic review therefore aims to evaluate the performance of AI models in automatically measuring patellofemoral joint parameters. We ...Missing: 2020s | Show results with:2020s
[99]
Patella - Etymology, Origin & Meaning
Originating from Latin patella, meaning "small pan or dish," knee cap refers to the small movable bone in front of the knee joint, named for its shape.
[100]
patella - Wiktionary, the free dictionary
Etymology 1 From Latin patella (“a small pan or dish, a plate; the kneepan, patella”), diminutive of patina (“a broad shallow dish, pan”). Doublet of paella.English · Etymology 1 · Italian · Latin
[101]
10/3/07 - Anatomy Words
Oct 3, 2007 · The term was introduced in its anatomical sense by Aurelius Celsus in the first century A.D.. True to its roots, an archaic name for the ...
[102]
The Word Patella Is The Latin Form of Patina | PDF - Scribd
Related to this term is the Italian word for frying pan which is padella. The term was introduced into medicine by Celsus. You might also like. Skeletal ...
[103]
Aristotle's Physiology of Animal Motion: On Neura and Muscles
Aristotle posits neura as key structures in animal motion, excluding muscles from this role. Neura operate similarly to modern muscles, pulling bones for limb ...<|control11|><|separator|>
[104]
Kneecap - Etymology, Origin & Meaning
1650s, "a covering or protection for the knee," from knee (n.) + cap (n.). Meaning "bone in front of the knee joint" is from 1869.Missing: patella | Show results with:patella
[105]
rotule - Wiktionary, the free dictionary
See also: rotulé. French. Etymology. Borrowed from Medieval Latin rotula. Pronunciation. IPA: /ʁɔ.tyl/. Audio: Duration: 2 seconds.0:02, (file). Noun.
[106]
Janukapalika, Jānukapālikā: 1 definition
May 7, 2021 · Jānukapālikā (जानुकपालिका):—Patella-knee cap. A lens shaped sesamoid bone situated in front the knee in the tendon of the quadriceps femoris muscle.
[107]
patella - Translation and Meaning in Almaany English Arabic ...
patella - Translation and Meaning in All English Arabic Terms Dictionary ; patella cubiti · رَضَفَةُ المِرْفَق ; patella partita · رَضَفَةٌ مُجَزَّأَة ; slipping patella · رَضَفَةٌ ...
[108]
https://www.dictionary.com/browse/patella
[109]
SESAMOID Definition & Meaning - Merriam-Webster
Etymology. Greek sēsamoeidēs, literally, resembling sesame seed, from sēsamon ; First Known Use. circa 1696, in the meaning defined above ; Time Traveler. The ...Missing: Theophrastus | Show results with:Theophrastus
[110]
Sesamoid bone - Wikipedia
Often, these bones form in response to strain, or can be present as a normal variant. The patella is the largest sesamoid bone in the body.