Elbow Biomechanics PDF

ELBOW BIOMECHANICS Prof. Olga Hoyos López MSc PT 2 3  INTRODUCTION. The elbow complex: Function Elbow -Shortening and lengthening of the arm for positioning of the hand -Provides stability for use of wrist and hand -Very stable joint, between two very movables joints...

ELBOW BIOMECHANICS Prof. Olga Hoyos López MSc PT 2 3  INTRODUCTION. The elbow complex: Function Elbow -Shortening and lengthening of the arm for positioning of the hand -Provides stability for use of wrist and hand -Very stable joint, between two very movables joints Forearm -Proximal radio-ulnar -Distal radio-ulnar -Both joints work together to achieve pronation/supination to assist in positioning of the hand 4  The elbow complex: Structure Uniaxial, diarthrodial = synovial hinge joint Three bones: humerus, radius, ulna 1dg of freedom of motion (sagittal plane) Articulations of the ELBOW -Humeroulnar -Humeroradial (no contact until elbow flexion >90dg) Shared - Proximal radio-ulnar Synovial Capsule! 5  The elbow complex: Structure COMPOSITE JOINT (more than one joint) Articulations of the ELBOW -Humeroulnar -Humeroradial (no contact until elbow flexion >90dg) - Proximal radio-ulnar Hinge joint: Only allows movement in one plane flexion/extension 6  1. Humero-ulnar joint Between Modified hinge joint with 1dg of freedom: flexion/extension. “Modified” because ulna experiences slight amount of axial rotation and side-to-side motion 7 2.Humero-radial joint “Mortar and pestle” 8 2. Humero-radial joint However, even though the humeroradial joint has the surface of a “Ball and socket” type of joint, due to the presence of the annular ligament, that anchors radius to ulna, it behaves more like a “pivot” joint. Radial head “pivoting” around the humeral capitulum 9  3. Proximal radioulnar joint Not part of the hinge joint. Involved in PRONATION and SUPINATION of the forearm It’s a Pivot joint (rotation around an axis) 10 11  The elbow complex: Structure Muscles -Anterior: Biceps Brachii, brachioradialis, brachialis (flexors) -Posterior: Triceps, anconeus (extensors) 12 The elbow complex: Structure 14  The elbow complex: Structure Ligaments -MCL or -LCL or Ulnar collateral ligament Radial collateral ligament Valgus instability test Varus instability test 15 16 17 18 OPEN & CLOSED KINEMATIC CHAINS 19  OPEN KINEMATIC CHAIN Distal segment is FREE to move on the proximal segment ULNA and RADIUS move on top of the HUMERUS Concave on the Convex movement: roll and glide SAME DIRECTION 20 OPEN KINEMATIC CHAIN 21  CLOSED KINEMATIC CHAIN Distal segment is fixed and the proximal segment performs the movement Radius and ulna are fixed, only way to execute movement is to move the humerus. Convex on concave movement = roll and glide OPPOSITE DIRECTION 22 EXTENSION KINEMATICS 23 EXTENSION KINEMATICS 24 HUMERO-RADIAL JOINT OPEN KINEMATIC CHAIN HUMERO-ULNAR JOINT OPEN KINEMATIC CHAIN SUMMARY Osteokinematics Glide/slide Roll (Open Kinematic Chain) 25 HUMERO-RADIAL JOINT CLOSED KINEMATIC CHAIN HUMERO-ULNAR JOINT CLOSED KINEMATIC CHAIN SUMMARY Osteokinematics Glide/slide Roll (Open Kinematic Chain) Flexion Posterior Anterior Extension Posterior Anterior 26 Lateral view elbow – articular capsule  ARTHROKINEMATICS OF PRONATION AND SUPINATION While flexion and extension are the only movements that can occur at the elbow joint itself, movement is also afforded at the proximal radioulnar joint, which contributes to the elbow joint. Movements at this joint are called pronation and supination. These are rotational movements that occur when: Distal end of the RADIUS moves over the distal end end of the ULNA by rotating the radius in the pivot joint formed by the circular head of the radius, the radial groove of the ulna and the annular ligament. 28 ARTHROKINEMATICS OF PRONATION AND SUPINATION Longitudinal axis Centre of radial head to center of ulnar head 29  OSTEO KINEMATICS OF PRONATION AND SUPINATION Pronation and supination are easily visualised when the elbow is flexed at 90°. Supination is where the palm of the hand is facing upwards; pronation is rotation of the forearm so that the palm is facing downwards. In the anatomical position, the forearm is in the supine position. Pronation in the anatomical position is movement of the forearm so that the palm is facing posteriorly. 30  KINETICS: Pronation/Supination muscles Muscles -Supination: Supinator, Biceps Brachii -Pronation: Pronator teres, Pronator Quadratus 31 32 OSTEO KINEMATICS OF PRONATION AND SUPINATION 33 OSTEO KINEMATICS OF PRONATION AND SUPINATION 34 OSTEO KINEMATICS OF PRONATION AND SUPINATION 35  OSTEO KINEMATICS OF PRONATION AND SUPINATION Limits to Pronation Tension of the supinators Tension of the posterior fibers of the triangular ligament Tension of the annular ligament 36 37 38 39 40 41 42  Elbow joint – The carrying angle Angle formed between the long axis of the humerus and the long axis of the forearm when the arm is in the anatomical position  Elbow joint – The carrying angle Average carrying angle: -males: 5 to 10 degrees -females: 10 to 15 degrees. Why is it important? -Helps to keep the hand away from the body, providing clearance during activities such as walking or carrying objects. -Contributes to the efficient positioning of the hand for various tasks.