THE HIP

• The hip joint, also known as the coxofemoral joint or acetabulofemoral joint, is formed by the union of the acetabulum of the pelvis and the head of femur, and is a diarthrodial ball-and-socket joint with 3° of freedom.
• The proximal articular surface of the hip joint is the acetabulum, which has a center edge angle and an angle of acetabular anteversion.
• The distal articular surface of the hip joint is the head of femur, which has an angle of inclination, an angle of torsion, and an angle of congruence.
• The hip joint capsule and hip joint ligaments include the iliofemoral ligament, pubofemoral ligament, ischiofemoral ligament, and ligamentum teres.
• The arthrokinematics of the hip joint include movements such as flexion and extension, abduction and adduction, internal/medial and external/lateral rotation.
• The osteokinematics of the hip joint involve the motion of the femur at the hip joint, including anterior and posterior pelvic tilt, lateral pelvic tilt, and pelvic rotation.
• Hip precautions and hip fractures may involve weight-bearing restrictions.
• Transverse Acetabular Ligament is located on the distal articular surface of the femur, covering the head of the femur, with a radius of curvature that is smaller in women than in men.
• The point at which the ligament of the head of femur is attached is known as Fovea/Fovea capitis.
• The femoral neck angulates the head superiorly, anteriorly and medially (SAM).
• The angle of inclination of femur occurs in the frontal plane between the axis of the femoral neck (diagonal line) and the axis of femoral shaft (vertical line), with a normal value of 125° in adults.
• An increase or decrease in the angle of inclination of femur will affect the knee joint, as the hip and the knee have a relationship to one another.
• Coxa Vara is a pathologic increase in medial angulation between the neck and shaft of the femur.
• Coxa Valga is a pathologic decrease in medial angulation between the neck and shaft of the femur.
• The angle of torsion of femur occurs in the transverse plane between the axis of the femoral neck and the axis of the femoral condyles, with a normal angle of torsion (adult) of 15°.
• Anterior torsion of the head and neck of femur is known as anteversion, while retroversion is a pathologic decrease in the angle or reversal of torsion.
• The articular congruence of the hip joint is referred to as the 'frog-leg position', where the head of femur is within the acetabulum.
• Flexion, Abduction, and slight External Rotation (FAbER) is a common position used for positioning or for immobilization of the hip joint when the goal is to improve joint congruence in conditions such as congenital dislocation of the hip and Legg-Calve Perthes Disease.
• A childhood condition that occurs when blood supply to the ball part of the femoral head of the hip joint is temporarily interrupted and the bone begins to die is known as Legg-Calve Perthes Disease.
• Doing the frog-leg position can be used to improve the congruency of the head of femur to the acetabulum because the articular contact is maximized.
• Ligamentum Teres is the movement of the convexity of the femoral head within the concavity of the acetabulum.
• During flexion and extension, the femoral head spins around a coronal axis (sagittal plane).
• In Flexion, the femoral head spins posteriorly.
• In Extension, the femoral head spins anteriorly.
• There is a spinning and gliding motion on the head of femur (gliding of one surface on another opposite, to the motion of the distal end of the femur).
• During hip flexion, where knee is extended, the range of motion is more limited because there is tension in the posterior surface of thigh region.
• During hip flexion, where knee is also flexed, the range of motion is greater.
• During hip extension, where the knee is flexed, the movement is more limited because there is tension or stretch in the quadricep muscle.
• During hip abduction, the Gracile muscle, found in the medial compartment of the thigh, limits the range of motion.
• During hip adduction, the muscles in the lateral surface (ITB and Tensor Fascia Lata) of the thigh limits the range of motion.
• It is important to know the range of motion available so that we know the normal range of motion when measuring the ROM of the client’s hip joint.
• Movement Range of Motion (ROM) in Osteokinematics: Flexion 90 degrees with the knee extended, 120 - 135 degrees with knee flexed; Extension 10 - 30 degrees (Hip extension + knee flexion = limited movement); Abduction 30 - 50 degrees (can be limited by Gracilis muscle); Adduction 10 - 30 degrees (can be limited by ITB and Tensor Fascia Lata muscle); Lateral Rotation 45 - 60 degrees; Medial Rotation 30 - 45 degrees.
• Lateral Pelvic Tilt occurs in the transverse plane around a vertical axis and commonly occurs in single-limb support around the axis of the supporting hip joint.
• Forward Rotation of the Pelvis occurs when the side of the pelvis opposite to the supporting hip joint moves anteriorly, producing medial rotation of the supporting hip joint.
• Backward Rotation of the Pelvis occurs when the side of the pelvis opposite the supporting hip moves posteriorly, producing lateral rotation of the supporting hip joint.
• Normal Range of Motion (ROM) in Gait on Level Ground includes Flexion of 90 degrees, Extension of 10-30 degrees, Abduction/Adduction of 30-50 degrees, Lateral/Medial Rotation of 10-30 degrees.
• Hip Precautions in Hip Replacement Surgery include no hip flexion greater than 90 degrees, no internal rotation, and no adduction (crossing legs or feet).
• Posterolateral Approach in Hip Surgery involves no hip flexion greater than 90 degrees, no internal rotation, and no adduction (crossing legs or feet).
• Anterolateral Approach in Hip Surgery involves no external rotation, no adduction (crossing legs or feet), and no extension.
• Weight-Bearing Restrictions in Hip Fractures include Non-Weight Bearing (NWB), Toe-Touch Weight Bearing (TTWB), Partial Weight Bearing (PWB), Weight Bearing at Tolerance (WBAT), and Full Weight Bearing (FWB).