Scaphoid Fractures 1

Transcription

1 1 Scaphoid Fractures

2 Scaphoid Fractures Introduction Anatomy Biomechanics History Clinical examination Radiographic evaluation DDx Classification Treatment Complications 2

3 Scaphoid fractures Introduction Scaphoid fractures constitute % of all carpal bone fractures Second only to the distal radius in frequency Due to the importance of scaphoid in wrist mechanics and because of the frequency of the fracture in young adult male, it has an economic as well as physical significance Uncommon in children because the physis of distal radius fails first 3

4 Anatomy Also called Navicular An irregular shaped bone,more resembling a twisted peanut than the boat for which it is named Scaphoid represents floor of the anatomic snuff box 4

5 Anatomy Articular cartilage covers 80 % of the scaphoid surface - only narrow area of its neck, & even smaller distal portion, are accessible to blood vessels Distally, it articulates with the trapezium and trapezoid in a gliding motion, The articulation with the trapezium forms a base for independent movement of the thumb On the ulnar side, it articulates distally with the capitate, and proximally with the lunate in a rotary motion Proximally, its large, biconvex surface allows 5 articulation with the radius

6 6 Anatomy -ligaments

7 Anatomy Blood Supply Major blood supply comes from the scaphoid branches of the radial artery entering the dorsal ridge at or just distal to waist area and supplying % of the bone including the entire proximal pole - in a retrograde fashion Second group of vessels, arise from palmar & superficial palmar branches of radial artery & enter the distal tubercle, it perfuses distal % of bone, including tuberosity 7

8 Blood Supply There are no anastomoses between the dorsal and palmar vessels Vessels enter thru dorsal ridge in 79 %, distal to waist in 14 %, & proximal to waist in 7 % Fractures across scaphoid may destroy blood supply to its proximal part 8

9 Biomechanics Mechanically scaphoid links the proximal and distal rows Scaphoid spans both carpal rows and therefore has less mobility than other carpal bones Scaphoid carries the compressive loads from the hand across the wrist to the distal forearm 9

10 Biomechanics Scaphoid flexes with wrist flexion & extends with wrist extension It also flexes during radial deviation & extends during ulnar deviation These factors make immobilization of scaphoid fractures difficult especially when there is displacement 10

11 Biomechanics Scaphoid is a principal bony block to dorsiflexion of hand & wrist, and is susceptible to frx during fall on outstretched hand With scaphoid fx, distal scaphoid tends to flex, & proximal scaphoid extends with the proximal carpal row,, because of this, angulation occurs at fx site, which gradually leads to a humpback deformity 11

12 Mechanism of injury Two different mechanisms 1. Compression injury : usually results in non displaced fx 2. Hyperextension bending injury : usually results in displaced fx 12

13 Diagnosis A strong index of suspicion is the key to early diagnosis The diagnosis should be based on : History Clinical examination Radiographic evaluation 13

14 History Occurs after a fall on an outstretched hand, athletic injury, or MVA Usually happens in young adult men Pain at the radial side of the wrist Associated injuries 14

15 Clinical Examination Should demonstrate tenderness in the anatomic snuff box Tenderness to palpation over scaphoid tuberosity and/or proximal pole just distal to Lister's tubercle Tenderness with axial compression of thumb toward the snuff box Tenderness as patient supinates forearm against resistance 15

16 Clinical Examination Radial & ulnar deviation results in pain on radial side of wrist Forced dorsiflexion usually elicits significant tenderness There is usually pain at extremes of motion Limitation of wrist motion but not dramatically Swelling usually not present 16

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18 Radiographic Evaluation The best method for determining the presence of a fracture Many different views have been recommended The useful initial views are : PA, lateral, scaphoid view ( PA with ulnar deviation ) 18

19 Radiographic Evaluation Motion views of the wrist ( flexionextension-radial & ulnar deviation ) may demonstrate fracture displacement If a diagnosis still can t be confirmed with confidence on routine films, further oblique views can be taken If certainty still exists after all these maneuvers, the patient should be placed in a cast for 2 to 4 weeks and the clinical & radiographic evaluation repeated 19

20 Radiographic Evaluation If the second radiographic examination is still equivocal, a technetium bone scan, polytomography, CT or MRI of the wrist is recommended The bone scan is the most sensitive but the least specific of these modalities, thus if the bone scan is negative, a scaphoid fx is ruled out 20

21 Radiographic Evaluation If the bone scan is positive, more specific studies ( e.g. polytomography, CT or MRI ) can be helpful 21

22 DDx It is the same DDx of radial sided wrist pain Lunate dislocation or fx Sapholunate instability Radial styloid fx Trapezium fx Rupture of FCR tendon ECRB or ECRL avulsion 22

23 Classifications of scaphoid fx A. Location of the fracture : 5 different fracture sites : Proximal third ( proximal pole ).. 25% Middle third ( waist ) most common 65% Distal third..10% Tuberosity Distal articular surface ( osteochondral fx ) 23

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25 Classifications of scaphoid fx B. Direction of the fracture : Horizontal Oblique, Transverse, and Vertical Oblique (Russe s Classification ) 25

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27 Classifications of scaphoid fx C. Time since injury : Acute fracture - less than 3 weeks old Delayed union - 4 to 6 months old Nonunion - more than 6 months old 27

28 Classifications of scaphoid fx D. Amount of fracture displacement ( stability ) : Undisplaced ---- stable Displaced ---- unstable 28

29 The unstable fracture (displaced) is defined as : - presence of a fracture gap > 1 mm on any radiographic projection - scapholunate angle > 60 - radiolunate angle > 15 - or intrascaphoid angle > 20 29

30 30 Herbert s Classification

31 Prognosis Negative prognostic factors are : late diagnosis proximal location displacement angulation obliquity of the fracture line smoking carpal instability 31

32 Treatment Is determined by: Location Degree of displacement Fresh vs old fracture 32

33 Treatment Undisplaced ( stable) fracture : Nonoperative ( cast immobilization )--- there have been three main areas of disagreement in non-operative treatment of acute non displaced fractures of scaphoid : 1- the position of the wrist in the cast 2- the need to include joints other than the wrist in the cast 3- the duration of the immobilization 33

34 Treatment Many types of cast immobilization have been described in the literature No evidence exists to prove greater efficacy for one casting position over another. Although above elbow casts may have a slightly shorter time to union, the final rate of union is the same for below or above elbow casts. The key factor in treatment of scaphoid fractures is the duration of immobilization rather than the specific position 34

35 The current recommendation is to use a short arm thumb spica with the thumb interphalangeal joint free. The wrist is placed in radial deviation Long arm cast is recommended for nondisplaced proximal pole fx 35

36 Consider changing the cast every days for the first 6 weeks so that it remains firm around forearm muscles and the wrist Time to healing by location : Distal third fx heals in 6-8 weeks Middle third fx 8-12 weeks Proximal third fx weeks A 95 % union rate can be expected with this management 36

37 Removal of the cast should not occur until union has been documented on CT or tomography Prognosis is excellent in undisplaced, stable fractures if diagnosed and immobilized early (95 % with x-ray evidence of beginning consolidation at 6 weeks ) 37

38 Initial delay in treatment does not preclude casting If treatment is instituted within four weeks no effect on healing time or rate of union has been shown Delay beyond six months invariably requires operative treatment The difficulty lies in fractures between six weeks and six months. If no evidence of bony resorption exists, casting may result in union. If bony resorption or displacement greater than 1 mm exists, operative reduction and bone grafting will be needed 38

39 Treatment Cast immobilization and electrical stimulation : the M/A isn t fully understood It is worthwhile to try electrical stimulation (esp.when there is nonunion ), though there is a lack of reliable double-blind study which compares between series of patients treated with immobilization alone and those treated with immobilization and ES, 39

40 If the patient will not tolerate prolonged cast immobilization (e.g. professional athletes and manual laborers ) early internal fixation should be performed Internal fixation for fresh nondisplaced proximal pole fractures has been recommended by some authors 40

41 Treatment Displaced fractures : Primary internal fixation is treatment of choice for unstable scaphoid frxs Fractures treated by primary internal fixation, average time for return to work is 3.7 weeks with union rate 97 % 41

42 Indications of Surgery in Scaphoid fractures Displaced acute fracture Delayed union or nonunion when bone grafting is insufficient to provide adequate internal fixation S.Fx associated with a perilunate fx or dislocation Ligamentous injury Non displaced fx of proximal pole Non displaced fx if the pt will not tolerate prolonged cast immobilization (e.g. professional athletes and manual laborers ) 42

43 The choice of the surgical procedure will vary with the surgeon s preference and experience, the type of the fracture, the patient s age, and the presence of periscaphoid arthrosis The most important aspect of the treatment is meticulous technique and not the device or equipment selected Reduction of the fracture should be anatomic 43

44 ORIF of scaphoid fractures can be done by many ways : K-wires ( easy insertion ) Herbert screws ( headless, multipitched,difficult insertion ) AO screws Herbert-whipple screw Ender s plate Staples 44

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47 The surgical approaches : Volar approach -- is most of the time the preferred approach to limit the injury to the blood supply of the scaphoid Dorsal approach will be used to address the fractures of the proximal approach 47

48 Volar approach: between FCR and the radial artery 48

49 Treatment of middle third fxs They are the commonest (65%) If fresh stable: short-arm thumb spica cast If fresh undisplaced but potentially unstable (e.g. vertical oblique) and stable fx older than 3 wks : long-arm thumb spica cast If fresh displaced : ORIF (k-wires or screws) 49

50 Proximal Pole Fractures challenging Often difficult to heal Prolonged immobilization- snug, well molded long arm cast- (sometimes exceeds 9 mos) has been necessary with conventional casting Early incorporation of PES has been recommended 50

51 Proximal Pole Fractures There is increasing favor to proceed to ORIF A dorsal approach allow s direct visualization of the fracture If it is a fresh fx, can be fixed by 2-3 k-wires The k-wires are extracted in a retrograde fashion in 6-8 weeks Alternatively,one may use a Herbert screw which may be inserted retrograde while the fragment is stabilized in a k-wire 51

52 Proximal Pole Fractures Determination of bony union is not easy Tomography or CT is needed Multiple follow up films should be obtained for several months after the assumed healing 52

53 Distal Pole Fractures These are often avulsion injuries of the tuberosity and can be expected to heal promptly with cast treatment Fresh and undisplaced should heal in 4-8 wks in a cast Displaced fx needs ORIF 53

54 After treatment care After achieving a rigid fixation, there is a big controversy about the need for immobilization Some authors recommend a long arm cast after k-wire or compression screw fixation for 2-3 weeks New literature is in favor of early mobilization 54

55 Complications of Scaphoid Fx Delayed union or Nonunion Malunion (Humpback deformity) SLAC wrist Osteonecrosis 55

56 Nonunion The incidence of scaphoid nonunion for undisplaced fx is 5-10% The incidence increases up to 90% in displaced proximal pole fxs Risk factors : Proximal pole fx Displacement Late diagnosis Inadequate immobilization Associated ligamentous injuries 56

57 Nonunion Failure to heal after 6 months establishes the Dx of nonunion Recent studies indicated that virtually that all unstable nonunions lead to carpal collapse and posttraumatic arthritis,, for this reason treatment is recommended for all scaphoid nonunions even if asymptomatic Thin cut CT scan show more details than conventional tomograms Sagittal views are helpful in determining the degree of carpal collapse and humpback deformity 57

58 Treatment of Nonunion A) Bone grafting : 2 types of bone grafting are indicated for tx of nonunion: 58 Russe bone graft (inlay): used for stable nonunions.the initial procedure used a single corticocancellous strut across the fracture line;a later modification involved two corticocancellous struts inserted into the scaphoid excavation with their cancellous sides facing each other,the remainder of the cavity is filled with cancellous chips. Usually k-wires are added to secure the construct.

59 59 Inlay graft

60 Con t Russe bone graft The time to union with this procedure is relatively long,generally requiring cast immobilization for 6-4 months Healing rates of % have been reported Satisfactory relief of symptoms has been reported ; 78 % of painful wrist became free of symptoms and 88 % of patients were satisfied with the results 60

61 Con t Bone Grafting Fernandez bone graft (interpositional graft): angulated nonunions with a dorsal humpback deformity require interpositional grafting. Fernandez has described the use of a trapezoidal iliac graft to correct the angulation and carpal collapse pattern.fixation is achieved with screws or k-wires In both types of bone grafting,a volar approach is used, and care must be taken to preserve the vascularity of the fragments 61

62 62 Interpositional graft

63 Treatment of Nonunion B) Electrical stimulation: Pulsed Electromagnetic Field ( PEMF ) stimulation has been investigated as a noninvasive treatment for scaphoid nonunion.although controversial, there appears to be some benefit (shorter healing time)when electric stimulation is combined with bone grafting procedures 63

64 Treatment of Nonunion C) Proximal pole excision: when a small proximal fragment is not amenable to bone grafting,proximal pole excision and fascial hemiarthroplasty are recommended 64

65 Treatment of Nonunion D) Salvage procedures : 65 Are indicated when nonunion has lead to carpal collapse and secondary degenerative changes Proximal row carpectomy,intercarpal arthrodesis, or radiocarpal arthrodesis is recommended in patients with chronic wrist pain and stiffness Radial styloidectomy and scaphoid interposition arthroplasty may be combined with other procedures or performed independently in the younger patient with less severe symptoms Silicone implants have been used in the past but are now avoided because of silicone synovitis

66 Malunion Malunion of the scaphoid may occur when a displaced or angulated fracture is allowed to heal without anatomic reduction In most of cases, there is a dorsal angulation resulting in a fixed humpback deformity DISI pattern ensues,resulting in pain,loss of motion, and decreased grip strength Treatment in a young patient includes osteotomy,volar wedge bone graft,and internal fixation Once degenerative arthritis has begun,treatment is limited to a salvage procedure such as proximal row carpectomy,intercarpal arthrodesis,or complete wrist fusion 66

67 67 Osteonecrosis

68 SLAC scapholunate advanced collapse (SLAC) refers to a specific pattern of osteoarthritis and subluxation which results from untreated chronic scapholunate dissociation or from chronic scaphoid nonunion 68

69 Case # 1 J.D. 24 y.o male. Fell on his out stretched hand while snowboarding on March 7/2000 C/0 pain Lt wrist, no other injuries. O/E : Lt wrist tenderness, neurovascular intact X-rays : 69

70 70 ER x-ray

71 71 Lateral view

72 72 Post -reduction

73 73 ORIF March7/2000

74 74 May1/ wks post ORIF

75 75 May1/ wks post ORIF

76 May 29/ wks 76

77 77 May 29/2000