What is In nonunion of scaphoid vescularized muscle pedicle graft is taken from. and explain in detail?
C i.e. Pronator quadrates Blood supply of scaphoid enters distally mainly through the dorsal ridge (spiral groove, narrow non aicular region in the waist) and proximal segment is supplied by retrograde intraosseous blood flow from distal to proximal. This unusual pattern of vascularity is responsible for higher probability of nonunion & avascular necrosis of proximal fragment in fractures of scaphoid. Therefore 0-1% of distal third, 20% of middle third, 40% of proximal third and 100% of proximal pole fractures result in AVN and nonunion. Scaphoid Fracture Functional Anatomy & Epidemiology Scaphoid is the most commonly fractured bone in the - carpusQ, in adult as well as children. However unlike in adults and adolescents, the fracture is rare in young children. (d/t cailagenous nature of carpal bones in children) Scaphoid fracture is seen most commonly in males between the ages of 15 and 30. (adolscents & adults)Q - Scaphoid may be divided into proximal, middle and distal thirds. The middle third is termed the waist. The scaphoid tubercle forms the distal volar prominence. Middle third (Waist) fractures are most commonQ accounting for - 70% of scaphoid fractures > proximal pole fracture (20%) > distal pole fracture (10%), in adults & adolescents. Investigation Distal pole avulsion type fracture is most common fracture type in children Q. Anteroposterior, lateral and oblique views are all essential; often a recent fracture shown only in the oblique viewQ. So a routine scaphoid x- ray series must include:- Radial and ulnar deton PA views with the wrist in about 30deg of extension (by asking to make a fist gently) True lateral view Radial oblique (supinated PA) view and ulnar oblique (pronated PA) view. Comparison view of opposite wrist. However it is common for the fracture not to be visible on the initial films. If doubt exists, the scaphoid should be immobilized in plaster and repeat radiograph obtained in 1421 days as the late films are usually positiveQ. Bone scan, trispiral tomography are other investigations ; occult scaphoid fractures can be reliably diagnosed by MRI & nucleotide scan. Vascularity, Nonunion & AVN Blood supply of scaphoid is precarious. It receives most of its blood supply from two major vascular pedicles (dorsal & volar branches) from the radial aery, both entering distallyQ. Volar (palmar) scaphoid branch of radial aery enters the scaphoid tubercle and supplies its distal 20-30%. Dorsal scaphoid branch of radial aery enters through numerous small foramina along the spiral groove & dorsal ridge and account for 80% of its blood supply. There is usually no or rarely a single perforater proximal to the waist of scaphoid. Hence vascularity of proximal fragment is maintained by retrograde intraosseous blood flow from distal to proximal; 7080% of which is provided by dorsal branch. The distal scaphoid has a dense vascular network whereas intraosseous vascular density declines proximally, leaving the proximal pole with sparse blood supply. Because of this unusual retrograde vascular supply to proximal segment, the scaphoid has a high risk of nonunion and AVN after fracture through waist and proximal pole. Because the scaphoid aiculates with four carpal bones & radius, most of its surface is composed of aicular cailage. Therefore, the vascular supply comes through -a narrow non aicular region in the waist. Most of the blood supply to the scaphoid enters distally, so blood supply of scaphoid diminishes proximallyQ. This accounts for the fact that 1% of distal third, 20% of middle third, 40% of proximal third and 100% of proximal pole fractures result in avascular necrosis or non union of the proximal fragment2. -Because it aiculates with distal radius, and with 4 of remaining 7 carpal bones, the scaphoid moves with nearly all carpal motions, especially volar flexion. Any alteration of its aicular surface through fracture, dislocation, or subluxation or any change of its stability by ligamentous rupture can cause severe secondary changes throughout the entire carpus. Management Stable and undisplaced fractures are treated by scaphoid cast immobilization (glass holding dorsal and radial flexion positionQ impacts the scaphoid fragments and minimises the shearing effects), for 4 - 8 weeks in distal third, 6 - 12 weeks in middle third and 12- 20 weeks in proximal third fractures. Scaphoid cast is applied from the upper forearm to just sho of meta carpophalyngeal joints of fingers, but incorporating proximal phalynx of thumb. The wrist is held dorsiflexed and the thumb forwards in "glass holding position" - A displaced fracture, by definition, is one with > 1 mm of step-off or >60degof scapholunate or >15deg of lunato- capitate angulation. The subtle signs of displacement or instability are - opening & obliquity of fracture line, angulation of distal fragment, and fore shoening of scaphoid image. Displaced- unstable fractures are treated by percutaneous screw fixation or OR & IF by k - wires, compression screw or Herbe screw. - Undisplaced ununited (nonunion) fractures may be treated by excavation of the scaphoid & placement of volar inlay coicocancellous bone graft (Matti Russe procedure). In most cases of stable nonunion cancellous bone graft from either the distal radius (for small defects) or the iliac crest (preferable because of its superior osteogenic and mechanical propeies) is packed into the defect. Dorsal cailage is not disturbed. This provides a hinge and facilitates assessment of scaphoid length. If fracture site is angulated or collapsed coico cancellous volar graft is employed to correct the deformity. If the proximal pole is avascular and no significant radiocarpal ahritis is present, revascularization of the scaphoid with a vascularized bone graft from dorsal radius or preferably pronator quadratus graftQ should be performed. Paial radial stylodectomy should be performed in all patients with radiological signs of stage I radioscaphoid ahritis limited to scaphoid and radial styloid. - Once degenerative ahritis is evident at the radio -carpal joint, salvage procedures includes proximal row carpectomy, scaphoid excision and mid carpal ahodesis or total wrist ahrodesis. Clinical Presentation - The patient is usually and adolescent boy or young adult who gives a h/o falling on outstretched hand usually during active spos. Commonly the injury is misinterpreted as "just a sprain". Like colle's it is a supination - dorsiflexion injury. - Fullness & tenderness in anatomical snuff boxQ. Radial side wrist pain; passive dorsiflexion to the radial side is painful, grip is weak and release of grip gives transitory pain, resisted pinch between the thumb and index finger is uncomfoable. Proximal pressure along the axis of the thumb may be painfulQ.