Biomechanics of the Wrist - Lecture 4 PDF

Biomechanics 2 Dr: Amany gomaa atiaa lecturer of Burn & Surgery Faculty of Physical Therapy -Sinai University sinaiuniversity.net  Biomechanics of the wrist joint. Wrist complex. ligaments. muscles. Loose packed position. Close packed position. Angles. Arthokinemati...

Biomechanics 2 Dr: Amany gomaa atiaa lecturer of Burn & Surgery Faculty of Physical Therapy -Sinai University sinaiuniversity.net  Biomechanics of the wrist joint. Wrist complex. ligaments. muscles. Loose packed position. Close packed position. Angles. Arthokinematics Wrist complex and its articulations The wrist joint complex consists of multiple articulations of the eight carpal bones with the distal radius, the structure within the ulnocarpal space, the metacarpals, and each other.  Bony structure **The carpus is divided into the proximal and distal row. **The bones of the distal row from the radial to ulnar side are the trapezium, trapezoid, capitate and hamate. **The distal carpal row forms a relatively immobile transverse unit that articulates with the metacarpals to form the carpometacarpal joint. **The more mobile proximal row consists of the scaphoid, lunate,and triquetrum. This row articulates with the distal radius to form the radiocarpal joint.  The eighth carpal bone, the pisiform is a sesamoid bone that mechanically enhances the wrist’s most powerful motor, the flexor carpi ulnaris, and forms its own small joint with the triquetrum.  Between the proximal and distal rows of carpal bones is the midcarpal joint, and between adjacent bones of these rows are the intercarpal joints.  The wrist consists of three main joints; , distal radioulnar joint (synovial pivot), the radiocarpal joint (condyloid synovial), and the midcarpal joint(synovial gliding). Also, ulnocarpal, carpometacarpal joint (synovial saddle joint), and intercarpal joint participate in formation of wrist complex. Wrist complex WRIST JOINT STRUCTURE OF THE WRIST  TFCC  The triangular fibrocartilage complex (TFCC) is a load-bearing structure between the lunate, triquetrum, and ulnar head. The function of the TFCC is to act as a stabilizer for the ulnar aspect of the wrist. The TFCC is at risk for either acute or chronic degenerative injury.  Goldstandard of diagnosis of TFCC injury is arthroscopy but sometimes MRI can reveal some abnormalities of TFCC.  Angles. Sagittal plane. Frontal plane. 10°. 25°. range of flexion. Range of ulnardeviation Volar (Palmer) tilt Ulnar tilt  Three axes of motion:.  Flexion (65 degree)-extension (55 degree).  Radial (15 degree)-ulnar deviation (35 degree).  Prono (90 degree)-supination (90 degree). MOVEMENTS OF THE WRIST  Arthrokinematics of wrist joint  In open chain movement, the convex surfaces of the scaphoid and lunate move on the concave surfaces of the radius and ulna.  During flexion: scaphoid/lunate roll anteriorly (toward palm) and glide posteriorly(toward dorsum)  During extension: scaphoid/lunate roll posteriorly(toward dorsum) and glide anteriorly(toward palm).  During ulnar deviation: scaphoid/lunate roll toward ulna and glide toward radius.  During radial deviation: scaphoid/lunate roll toward radius and glide toward ulna.. Wrist is the most complex joints of the body due to the numerous joints combined to create one.. Wrist joint is Synovial Ellipsoid (Condyloid).. Wrist stabilization is ensured by the complex of stabilizers, both static (intrinsic and extrinsic ligaments) and dynamic (flexor and extensor of the wrist). Wrist ligaments  The ligaments of the wrist include: **Extrinsic ligaments: -Bridge carpal bones to the radius or metacarpals, they include volar and dorsal ligaments. palmar radiocarpal ligament dorsal radiocarpal ligament radial collateral ligament Ulnar collateral ligament -Three main dorsal extrinsic ligaments have great functional significance—the dorsal intercarpal, dorsal radiotriquetral, and dorsal radioulnar ligaments.. **Intrinsic ligaments: -Originate and insert on carpal bones, the most important intrinsic ligaments are the scapholunate interosseous ligament, lunotriquetral interosseous ligament, and scaphotrapeziotrapezoid ligament. Ligaments Function. Radial and ulnar collateral ligaments – bind the bones of the wrist and provide stability.. Volar radiocarpal ligaments – support the palm side of the wrist.. Dorsal radiocarpal ligaments – support the back of the wrist.. scapholunate ligament –plays an important role in facilitating movement & providing stability to the wrist, particularly when lifting heavy objects.  Kinetics  When evaluating force transmission, in extension the scaphoid transmitted 51% of the force and the lunate transmitted 49%, in neutral position 53% and 47%, and flexion 55% and 45%, respectively. Flexion Extension and Hyperextension 🤔Radial deviators stronger than ulnar deviators !!!  Wrist Ar thokinematics 2 Degree of Freedom Sagittal plane Frontal plane Flexion Extension Ulnardeviation Radial deviation Roll same & Glide opposite  Circumduction Combination of flexion, adduction(ulnar deviation) , extension, and abduction(radial deviation) motions. Closepacked position Extention with a slight degree of (abduction/radial deviation). Loose packed position Neutral wrist with a slight degree of (adduction/ulnar deviation). COMMON INJURIES OF THE WRIST AND HAND  Ligamentous sprain  Two of the common ones are the scapholunate ligament, in the middle of the wrist between the scaphoid and lunate bones, and the TFCC (triangular fibrocartilage complex) on the outside of the wrist. TFCC injury Wrist sprains Fracture of the distal radius Fractures of the scaphoid and lunate  De Quervain Tenosynovitis  With this condition thickening of the tendon sheaths around the abductor pollicis longus and extensor pollicis brevis develops where the tendons pass in through the fibro- osseous tunnel located along the radial styloid at the distal wrist. Pain is exacerbated by thumb movement and radial and ulnar deviation of the wrist.  You may be asked to perform a Finkelstein test, in which you bend your thumb across the palm of your hand and bend your fingers down over your thumb. Then you bend your wrist toward your little finger. If this causes pain on the thumb side of your wrist, you likely have de Quervain tenosynovitis.a Finkelstein test. De Quervains disease Carpal tunnel syndrome  Carpal tunnel syndrome  Themost common entrapment neuropathy of the upper extremity. It occurs in females more than males. The symptoms include pain and/or paresthesia of palmar aspect of lateral 3 and half fingers. For any questions feel free to contact me by mail [email protected] Dr: Amany gomaa atiaa lecturer of Burn & Surgery Faculty of Physical Therapy -Sinai University