| Abstract|| |
Background : Scaphoid, among all carpal bones, is very vulnerable for fracture due to its unique shape and situation with greater articular surface. All scaphoid fractures are being treated with below elbow POP thumb spica casts keeping hand in ball throwing position. A few scaphoid fractures through the waist take longer time to unite, if not end in nonunion. These fractures were found to be displaced unimpacted trans-scaphoid fractures through the waist.
Method : The effect of various positions of hand, wrist and forearm over unimpacted displaced scaphoid fractures through the waist were studied on dissected hand specimens and in patients with skiagrams. It was observed that possible radial deviation of hand over neutrally held wrist and forearm would result in anatomical reduction with impaction between the fragments. Added compression effect at site of fracture, necessary for early fracture healing, is produced by passively abducting the first metacarpal bone.
Results : Of 68 scaphoid fractures under study, 24 and 41 were displaced and undisplaced ones through the waist respectively. All of them united in eight to ten weeks time as any fracture, when immobilised undisturbed with anatomic reduction and added compression between the fragments except one displaced fracture which took eight more weeks of immobilization for union and revascularilization of proximal fragment.
Conclusion : This study showed that all scaphoid fractures in particular those through waist when rigidly immobilized unite as any fracture in eight to ten weeks provided the proximal fragment maintains proper blood supply. Otherwise it would further eight week of immobilization for the proximal fragment to get revascularize following union.
Keywords: Carpal scaphoid; Displaced fractures through waist; Management.
|How to cite this article:|
Chari P R. Fresh fractures of the scaphoid : A rationale method of treatment. Indian J Orthop 2006;40:250-4
| Introduction|| |
The carpal scaphoid is unique among the carpal bones with large articular surface and in its blood supply. Its arterial blood supply is from its dorsum through its non-articular ridge. The transverse branches arising from the dorsal branch of the radial artery anastomose to give rise to branches which enter the scaphoid through its non-articular dorsal ridge from distal to proximal. But in 15% of the scaphoids it is seen that the proximal half derived its blood supply intra-osseously through one extra-osseous arterial branch entering through the dorsal ridge little distal to its mid-region of the scaphoid, the waist.
The shape, large articular surface and its situation has helped the scaphoid to have greater range of movement over other carpal bones. Besides its situation among the carpal bones is such that it forms a link between proximal and distal rows of carpal bones. Thus it becomes very vulnerable to injury resulting in its fracture, commonly through its weak part, the waist
The incidence of fracture of the scaphoid has been on increase in automobile and fast outdoor sport injuries. During such accidents it would be very difficult for the patients to recollect the exact mechanism of injury due to pre-occupied apprehensive state of mind. However, it is still considered to be due to fall on the outstretched hand. Experiments conducted by Verdan and Narakas on upper limbs to produce scaphoid fractures, in particular through its waist, had shown that sudden pronation of the dorsiflexed wrist, with hand in full ulnar deviation and thumb in opposition over supinating forearm or sudden supination of forearm in full pronation following fall over hand in full ulnar deviation, wrist in dorsiflexion with thumb in full abduction, would result in fractures of the scaphoid through its waist. Such a type of violence is a tortional one but not a bending violence.
Some of the scaphoid fractures through the waist do not unite even after three or four months of immobilization with below thumb spica casts keeping forearm, wrist, hand and thumb in conventional position of 'ball throwing' position. Besides below elbow thumb spica cast would allow unrestricted forearm movements which in turn produce torque movement between the scaphoid fragments resulting in non union.
Sixty eight fresh fractures of the scaphoid in the same number of patients attending the Orthopaedic Clinic during a period of 24 years from May 1977 to April 2001 were thoroughly investigated and studied to find out the number of displaced scaphoid fractures. Radiological examination revealed that 65 out of 68 scaphoid fractures were through the waist. Of these 65 scaphoid fractures, 41 were displaced ones [Table - 1].
The present study was based on the effects of various positions of hand, wrist, thumb and forearm on displaced scaphoid fractures through waist in dissected hand specimens and confirmed with those observed with the help of skiagrams in patients with such scaphoid fractures.
| Observations|| |
On observing the effect of ulnar deviation of the hand with wrist and forearm in neutral position, with thumb in abduction, it was seen in AP skiagrams of normal wrists that distal 2/3 rds of the scaphoids was well out of radial articulation and appear to stand vertical on their proximal poles. Dissected hand and wrist specimens with induced displaced scaphoid fractures through waist showed distinct gap between the scaphoid fragments [Figure - 1].
AP skiagrams of the wrist in patients with displaced scaphoid fractures through waist revealed appreciable gap between the fragments by the pull of the distal fragment away from the proximal by the action of abductor pollicis brevis muscle through its origin from the tubercle of the distal fragment. This gap increases when the thumb was abducted against resistance[Figure - 2].Thedisplacedscaphoidfracturescan be recognized and separated from undisplaced ones this way.
On observing effect of full ulnar deviation of hand with wrist in 300 dorsiflexion, thumb in palm opposition and forearm in neutral, it was observed in a AP and lateral skiagrams of normal wrists that the distal 2/3 rds of the scaphoid was out of radial articular surface.
Dissected hand and wrist specimen with induced displaced scaphoid fracture through waist showed volar gap between the fragments. This got appreciably increased by the action of abductor pollicis brevis muscle through its origin from the tubercle of the distal fragment as shown by the distal pull of abductor pollicis with dissection foreceps, to simulate its active action. [Figure - 3]
Skiagrams of the wrist in patients, with displaced scaphoid fractures through waist, showed gap between the fragments
On studying the effect of pronation of forearm over dorsiflexed wrist with hand in full ulnar deviation and thumb in opposition ( 'ball throwing' position of immobolisation of scaphoid fractures in practice with below elbow thumb spica plaster casts), skiagrams of normal wrists revealed torsion of the entire scaphoid with distal 2/3 rds well out of radial articular surface.
Dissected specimen with induced displaced scaphoid fracture through waist revealed not only volar gap between the fragments but also pronation twist of the distal fragment over steadied proximal fragment [Figure - 4]a,b.
Skiagrams of the wrist in patients with displaced scaphoid fractures through the waist showed distinct tortional mal-alignment of fragments due to pronation twist of the distal fragment over the proximal with volar gap in between [Figure - 5].
On observing the effect of full radial deviation of the hand with wrist and forearm in neutral position, it was seen in skiagrams of normal wrists that the entire scaphoid slides ulnar wards to lie horizontal on the entire radial articular surface, hitching against the lunate bone with its proximal pole and snugly surrounded in position by lateral three distal row carpal bones.
Dissected hand and wrist specimen with induced displaced scaphoid fracture through waist showed anatomical reduction with impaction between fragments [Figure - 6].
Skiagrams of the wrist in patients with displaced scaphoid fractures through waist, showed anatomical reduction of fragment with impaction while lying entirely on distal radial articular surface, snuggly surrounded by distal lateral three carpal bones [Figure - 7]a,b.
In such a position of forearm, wrist and hand, passive abduction of the first metacarpal bone [Figure - 8]a forces the proximal fragment indirectly through Os trapezium, against the steadied distal fragment, producing compression effect over anatomically reduced scaphoid fragments with impaction. In that position, if the limb is immobilised with well moulded above elbow thumb spica cast [Figure - 8]b all displaced scaphoid fractures healed, in eight to ten weeks time [Figure - 7]c provided the proximal fragment maintains its blood supply [Table - 2].
In the present study of 68 fresh fractures of the scaphoid in equal number of patients, all being males, the incidence on right was twice that of the left side. Sixty five of 68 scaphoid fractures were with fractures through waist. Of these scaphoid fractures, radiological examination revealed 41 of them to be displaced ones [Table - 1].
Twenty nine scaphoid fractures through waist (20 displaced and 9 undisplaced) were treated with above elbow thumb spica cast of six weeks and then with below elbow thumb spica for four more weeks. The rest 36 of the transscaphoid fractures (21 displaced and 15 undisplaced) were treated with above elbow thumb spica undisturbed for eight weeks. All scaphoid fractures through waist, both displaced and undisplaced, thus treated have united except one displaced fracture in which the proximal scaphoid fragment resulted in avascular necrosis. This fracture took eight weeks to unite and for full revascularization of proximal fragment [Figure - 9]a,b. Three more scaphoid fractures other than fractures through waist have also united following immobilization as others in six week time.
| Discussion|| |
Carpal scaphoid has unique shape and larger articular surface. Thus, it has greater range of movement than any other carpal bone. Due to its greater range of movement and its situation in linking the proximal with the distal row of carpal bones, it has become highly vulnerable to injury resulting in its fracture, usually through its mid weak region, the waist.
Review of the literature revealed that conservative management of the scaphoid fractures is still controversial. However, all scaphoid fractures, both undisplaced and displaced, are being treated in 'ball throwing' or glass holding position with below elbow thumb spica casts,,,,,. But displaced scaphoid fractures through waist would remain un-united even after three or four months of immobilization. This is due to mal-alignment of fragments with anterior gap between the fragments. This was clearly demonstrated in "ball throwing" position of fresh dissected hand and wrist specimen with induced displaced fracture through waist [Figure - 4]. Displaced scaphoid fractures in particular or recognized from undisplaced with significant gap between fragments in skiagrams of wrist in patients taken after full ulnar deviation of hand and active abduction of thumb preferably against resistance [Figure - 2].
Berlin was the first to prove with help of skiagrams of the wrists of patients with displaced scaphoid fractures through waist, that radial deviation of the hand with wrist in slight dorsiflexion would result in anatomic reduction of the fracture. Verdan and Narakas showed with the help of dissected wrist and hands in cadavers with induced scaphoid fractures through waist, that when hand and forearm were kept in neutral with wrist in functional position about 30 0 dorsiflexion, scaphoid fractures through waist would get anatomic reduction with impaction. But Cooney et al stated that there would be good impaction between anatomically reduced scaphoid fragments when the volar carpal ligament would become lax by slight volar flexion of wrist, keeping hand and forearm in neutral position.
The present study on dissected wrist and hand with induced scaphoid fractures through waist in fresh amputated specimen through arm and of the skiagrams of patients with such displaced scaphoid fractures, revealed that passive radial abduction of the first metacarpal bone and radial deviation of the hand with wrist and forearm in neutral, would result not only in anatomical eduction with impaction but also with added compression between the fragments. The compression effect between the fragments in any fracture is essential for early healing of the fracture. All displaced scaphoid fractures, in particular those through waist, if rigidly immobilised in above elbow thumb spica with anatomical reduction and added compression between the fragments would unite, as any fracture in six to eight weeks time [Figure - 10]a,b. Even though the proximal fragment becomes avascular undisturbed rigid immobilization would not only heal the fracture but also fully revascularise the proximal fragment [Figure - 9]a,b. Thus, it proves to show that avascular necrosis of bone is no bar for union of a fracture
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P Ranga Chari
‘Prashanth Towers’. Musheerabad, Hyderabad 500 020
Source of Support: None, Conflict of Interest: None
[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6], [Figure - 7], [Figure - 8], [Figure - 9], [Figure - 10]
[Table - 1], [Table - 2]