Joints of Lower limb

• The hip joint is an articulation between the head of the femur and the acetabulum of the hip bone.
• The acetabulum of the hip bone is deepened by a fibrocartilaginous rim called the acetabular labrum.
• The articular surfaces of the hip joint are covered with hyaline cartilage.
• The hip joint is a synovial ball-and-socket joint.
• The capsule of the hip joint is dense and strong and is attached medially to the margins of the acetabulum and acetabular labrum, and laterally to the intertrochanteric line of the femur anteriorly and the neck of the femur posteriorly.
• The obturator artery, passing through the obturator canal, is an opening in the obturator foramen, supplies the hip joint.
• The ligaments of the hip joint include the iliofemoral ligament, the strongest ligament in the human body that prevents hyperextension during standing, with a tensile strength of over 350 kg.
• The pubofemoral ligament prevents hyperextension and hyperabduction.
• The ischiofemoral ligament prevents hyperextension.
• The ligament of the head of the femur, also known as the ligamentum teres, is attached to the fovea capitis.
• The synovial membrane lines the capsule and is attached to the margins of the articular surfaces.
• The femoral, obturator, sciatic nerves and nerve to the quadratus femoris supply the hip joint.
• The lateral and medial circumflex femoral arteries travel in capsular retinacula, reflections of the capsule, towards the head, and retinacular arteries may be injured in fractures of the neck of the femur.
• The femoral head also receives supply from the obturator artery via the ligament of the head of femur.
• The hip joint has a wide range of movement, including flexion, extension, abduction, adduction, medial rotation and lateral rotation.
• The muscles that move the hip joint include the abductor muscles, adductor muscles, flexor muscles, extensor muscles, and the biceps femoris, semimembranosus, semitendinosus, and hamstring muscles.
• The knee joint is the largest and most complicated joint in the body, consisting of two joints: a condylar joint between the medial and lateral condyles of femur and corresponding condyles of tibia, and a gliding joint between the patella and patellar surface of the femur.
• The joint between the femur and tibia is a hinge joint, while the joint between the patella and femur is a plane joint.
• The knee joint capsule is attached to the margins of the articular surfaces and surrounds the sides and posterior aspect of the joint.
• The synovial membrane lines the capsule and is attached to the margins of the articular surfaces.
• Extracapsular ligaments include the ligamentum patellae, lateral (fibular) collateral ligament, medial (tibial) collateral ligament, oblique popliteal ligament, and arcuate popliteal ligament.
• Intracapsular ligaments include the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL).
• Menisci are C-shaped sheets of fibrocartilage that lie between femoral condyles and tibial condyles, serving as cushions between the two bones that act as shock absorbers.
• Anterior bursae related to the knee joint include the suprapatellar bursa, prepatellar bursa, superficial infrapatellar bursa, and deep infrapatellar bursa.
• Posterior bursae related to the knee joint include the popliteal bursa and semimembranosus bursa.
• Movements of the knee joint include flexion, extension, medial rotation, and lateral rotation.
• The ankle joint, or talocrural joint, is an articulation between the lower end of the tibia, the two malleoli, and body of the talus.
• The ankle is a synovial hinge joint, with a capsule that encloses the joint and is attached to the margins of the articular surfaces.
• The medial, or deltoid, ligament is attached by its apex to the medial malleolus, below it is attached to the talus; the sustentaculum tali, and navicular bone.
• The lateral ligament is weaker than the medial ligament and consists of three bands: the anterior talofibular ligament, calcaneofibular ligament, and posterior talofibular ligament.
• Movements of the ankle joint include dorsiflexion and plantar flexion.