Hip Joint

Hip joint Joints A joint is where two or more bones meet. Also known as an articulation Joints can be classified either by: the tissue that holds the bones together or the degree of movement they provide Synovial joints Permits free movement Fibrous joints Limited or no movement Cartilaginous joints Fibrous joints are connected by dense connective tissue and have no joint cavity. Cartilaginous joints are connected by cartilage and have no joint cavity. Synovial joints have a synovial, fluid-filled cavity that surrounds the articulating bones. Synarthrosis: Joints that do not provide any movement. Amphiarthrosis: Joints that only provide a small degree of movement. Diarthrosis: Joints that allow free movement FIBROUS JOINTS  In a fibrous joint, the two bones are connected by dense fibrous connective tissue  These joints can be either synarthrotic or amphiarthrotic  There are three different types of fibrous joints: Suture: between the flat bones of the skull Gomphosis: The roots of a tooth and the alveolar sockets in the maxilla or mandible Syndesmosis: interosseous membrane Sutures Sutural ligament These joints are synarthrotic Gomphoses Gomphoses occur only between the teeth and adjacent bone. In these joints, short collagen tissue fibers in the periodontal ligament run between the root of the tooth and the bony socket These joints are synarthrotic Syndesmoses These joints are amphiarthrotic CARTILAGINOUS JOINTS  In a cartilaginous joint, the two bones are connected by cartilage  These joints can be either synarthrotic or amphiarthrotic There are two types of cartilaginous joints: Synchondroses: growth plate Symphyses: intervertebral joints, symphysis pubis Intervertebral joints Symphysis pubis Synovial joints Synovial joints are most commonly found throughout the limbs. In order for the joint to be classified as synovial:  Both adjacent bones participating in the joint must be lined with hyaline cartilage (articular cartilage)  The joint is encompassed in a capsule that encases the joint cavity. The interior of the capsule is lined with a synovial membrane that is responsible for producing and secreting synovial fluid  Synovial fluid lubricates the joint, which aids in reducing the friction between the bones’ ends as they articulate with each other Further reinforcement of the capsule is provided by ligaments, tendons and skeletal muscle Bursae and Tendon sheaths Bursae are fibrous, slightly flattened sacs, lined with synovial membrane and containing a thin film of synovial fluid. These structures are usually found between bone and other tissues, such as skin, tendons, muscles, and ligaments. Bursae function to cushion the movement between these structures as they rub together. Tendon sheath Bursae A tendon sheath is a membrane that wraps around a tendon, which allows the tendon to stretch and prevents it from adhering to the overlying fascia. This sheath also produces a fluid, known as synovial fluid, which keeps the tendon moist and lubricated. Synovial joints Hinge Joint Example: elbow and knee joints Pivot Joint Example: atlantoaxial joint Gliding (plane) Joint Saddle Joint Ball and Socket Joint Example: shoulder and hip joints Ellipsoid Joint: Example: wrist joint Type Ball Socket Synovial Multi-axial Ball-and-socket joint Articular surfaces: Head Acetabulum a-Head of femur b-Lunate surface of acetabulum Lunate surface Acetabular fossa Head of femur The acetabular labrum is a ring of fibrocartilage that surrounds the acetabulum of the hip. The labrum deepens this cavity and effectively increases the surface (and strength) of the hip joint 3-Nerve Supply: Femoral nerve Obturator nerve Sciatic nerve Referred Pain From the Hip Joint The femoral nerve not only supplies the hip joint but, via the intermediate and medial cutaneous nerves of the thigh, also supplies the skin of the front and medial side of the thigh. It is not surprising, therefore, for pain originating in the hip joint to be referred to the front and medial side of the thigh. The obturator nerve supplies both the hip and knee joints. This would explain why hip joint disease sometimes gives rise to pain in the knee joint. Sciatic Posterior Capsule The capsule of the hip is attached Medially: is attached to the margin of the acetabulum Laterally: is attached to the trochanteric line anterioly and just proximal to the intertrochanteric crest posteriorly Anterior Part of the neck posteriorly is extra capsular The synovial membrane Lines the capsule as well as any intracapsular bony surfaces not lined with articular cartilage Thus, where the capsule attaches to the femur, the synovial membrane reflects proximally along the femoral neck to the edge of the femoral head. Subsynovial retinacular arteries (branches of the medial and a few from the lateral femoral circumflex artery) supply the head and neck of the femur Subsynovial retinacular arteries Provide one pathway for the blood supply to the femoral head Blood supply of the head of the femur Medial and lateral circumflex femoral arteries The main blood supply is from the retinacular arteries arising as branches from the circumflex femoral arteries (especially the medial circumflex femoral artery). Artery to the head of femur Acetabular branch of obturator artery (patent in approx. 30% ) Do you remember epiphyseal growth plate ???? Acetabular branch of obturator artery Note that blood supply via ligamentum teres is negligible in adult life This fracture cuts off most of the retinacular blood supply to the head Avascular necrosis is common The upper end of the femur is a common site for fracture in the elderly Subsynovial retinacular arteries Important Anatomic knowledge of the blood supply to the femoral head explains why avascular necrosis of the head can occur after fractures of the neck of the femur. In the young, the epiphysis of the head is supplied by a small branch of the obturator artery (acetabular branch), which passes to the head along the ligament of the femoral head. The neck of the femur receives a profuse blood supply from the medial femoral circumflex artery. These branches ascend along the neck deep to the synovial membrane toward the femoral head. As long as the epiphyseal cartilage remains, no communication occurs between the two sources of blood. In the adult, after the epiphyseal cartilage disappears, an anastomosis between the two sources of blood supply is established. Fractures of the femoral neck interfere with or completely interrupt the blood supply from the root of the femoral neck to the femoral head. The scant blood flow along the small artery that accompanies the round ligament may be insufficient to sustain the viability of the femoral head, and ischemic necrosis gradually takes place. 5 ligaments Main ligaments of the hip joint Iliofemoral ligament Pubofemoral ligament Ischiofemoral ligament All three ligaments are oriented in a spiral fashion around the hip joint so that they become taut when the joint is extended This stabilizes the joint and reduces the amount of energy required to maintain a standing position Anterior Iliofemoral ligament Anterior Pubofemoral ligament Posterior Ischiofemoral ligament The ligament of head of femur (ligamentum teres) is weak and of little importance in strengthening the hip joint. Usually, the ligament contains a small artery to the head of the femur Fovea capitis The acetabular notch is bridged by the Transverse acetabular ligament Movements of the hip joint Flexion is performed by the iliopsoas, rectus femoris, and sartorius Extension is performed by the gluteus maximus and the hamstring muscles Abduction is performed by the gluteus medius and minimus, assisted by the sartorius, tensor fasciae latae, and piriformis Adduction is performed by the adductor longus and brevis and the adductor fibers of the adductor magnus. These muscles are assisted by the pectineus and the gracilis Lateral rotation is performed by the short lateral rotator muscles and assisted by the gluteus maximus Medial rotation is performed by the anterior fibers of the gluteus medius and gluteus minimus and the tensor fasciae latae ANGLE OF INCLINATION  It is the angle between the neck and shaft of the femur, typically ranges from 120 ° to 135 ° degrees  Is about 160 ° in the young child and about 125° in the adult Approx. 125º Allows high degree of freedom ( by moving the longitudinal axis of femur away from hip joint More than 135º: coxa valga Less than 120º: coxa vara Dislocation of the hip The hip is usually dislocated backwards and this is produced by a force applied along the femoral shaft with the hip in the flexed position (e.g. the knee striking against the opposite seat or in car accident The sciatic nerve, is in a close posterior relation with the hip joint therefore, it is in a danger of damage in these injuries Iliopsoas bursa Lies between the iliopsoas tendon and the hip joint