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An experimental study of instability during supination and pronation of the fractured scaphoid
An Experimental Study of Instability During Supination and Pronation of the Fractured Scaphoid PER FALKENBERG From the University of Copenhagen. Rotatory instability of scaphoid fractures was studied by a method not used previously. On two fresh specimens the scaphoid bone was fractured by osteotomy, and the fracture was fixed by a Hoffmann apparatus extending from the distal radius to the lst, 2nd and 3rd metacarpals. This permits free rotation in the forearm. The scaphoid fragments were marked by Kirschner wires. No movement occurred between the fragments when supination/pronation was kept within the normal range of movement.
It is widely accepted that acute fractures of the scaphoid should be placed in a plaster cast with the first metacarpal and the proximal phalanx of the thumb fixed as recommended by Bohler (1935). On the other hand, it is a matter of discussion whether the elbow is to be incorporated in the cast. There have been advocates of both views (Bohler, 1935; Watson-Jones, 1960; Cooney, 1980; Adams, 1972; Verdan, 1960; Grace, 1929; Squire, 1959), as rotation in the forearm is assumed to entail a shift of the fragments. Little has been published concerning instability of these fractures solely due to the rotation of the forearm. Arkless (1960), describing it by cineradiography, found no indication for preventing rotation. Unfortunately, these experiments were performed without fixation. Verdan (1960) has reported small movements in the fracture during. supination and pronation, but without mentioning either the extent of the movement or the method of measurement. In the present study (performed on fresh specimens consisting of the upper arm, forearm, and hand) an attempt was made to record possible movements. The method has not been described previously. As casting immobilization would prevent measurement of such movement, it was decided to obtain the fixation needed by a Hoffmann external fixation apparatus.
fixed point of rotation was moved from the ulna to the radius. However, the normal relative movement between the radius-ulna and the hand remains unchanged. By this means the region to be measured, that is the scaphoid bone, was relatively immobilized, flexion/extension and deviation in the wrist were while rotation of the forearm was abolished, unhindered. Two Kirschner wires were used as markers, one through the distal part of the radius and one through the scaphoid bone. The distance between the wire ends was measured during a complete movement of rotation in the forearm. Osteotomy was then carried out through the waist of the scaphoid bone using an osteotome achieving a transverse fracture, first splitting the capsule of the joint on the dorsal side in the direction of the fibres. Both fragments were marked by Kirschner wires, and a fresh rotation of the forearm was carried out while recording the movement of the wires placed in the scaphoid fragments. On the second specimen only the skin and subcutaneous tissues were removed over the dorsal aspect of the wrist. In other respects the procedure was the same for both specimens.
Method
Each specimen consisted of the upper arm, forearm, and hand. First, the author made sure that movements in the elbow and wrist were normal. The test specimen was dissected free, leaving the ligaments intact. The distal part of the radius was fastened by screws to a fixed point, so that the volar aspect of the distal end of the radius was prone and the arm otherwise horizontal. The hand was fixed in relation to the forearm by a Hoffmann external fixation apparatus, extending from the radial aspect of the radius to the first, second and third metacarpals (Figure 1) in slight dorsiflexion (MacConaill, 1941). Thus, the Received for publication August, 1984. Dr. Per Falkenberg, 18 Edvard Griegsgade,
VOL. 10-B No. 2 JUNE
1985
DK-2100 Copenhagen,
Denmark.
The degree of rotation in the forearm was measured by a goniometer, with the stump of the humerus as the indicator and maximum pronation as zero point. The distance between the wire ends was measured with a slide gauge. The measurings were repeated three times, each time after a full rotation of the forearm. As the length of the wires was known, the movement could be expressed in degrees. Results
There was no movement between the inserted Kirschner wires in either specimen, intact or fractured, when supination was within the normal range of movement, that is O”-130”. Not until supination was forced, up to 211
PERFALKENBERG
Fig. 1
Specimen 1 with Hoffmanns
external fixation apparatus. The fragments of the fractured scaphoid are marked with Kirschner-wires.
165” in the former and 160” in the latter specimen, did incipient excursions appear, increasing until a maximum forced supination of 180” in the intact as well as the fractured scaphoid. TABLE
Radial Staph. I Staph. II Diff. in Mean dff. Angle distance in distance wire wire wire
2.18
intact
Specimen fractured
I,
2.34
0.17 0.17 0.20
0.18
2.1”
2.34
0.15 0.18 0.16
0.16
3.8”
Specimen intact
II,
Specimen fractured
II
6.25
1.51 1.49 1.56
1.52
3.1”
0.80 0.76 0.90
0.82
4.1”
2.30
4.77
4.54
5.28
By considering only the difference in distance between the wire ends, a triangle can be traced with all three sides known, that is the length of the wires and the difference in the distance between their ends. Thereupon, the desired angle can be calculated by the following formula: 212
=
b2 + c2 - a2
2 bc The distances are given in cm and were measured at maximum forced supination of 180”. Discussion
1
Specimen I,
Cosa
The external fixation used at present is rigid, but allows free rotation of the forearm. When a below-elbow plaster for fracture of the scaphoid is applied in the clinic, one obtains approximately the same conditions as those in the experiment. The finding of no movement in the scaphoid fragments during rotation of the forearm within the normal range shows that there is no indication for including the elbow in plaster immobilisation. According to Russe, the transverse fracture through the middle third of the scaphoid, is far more common than the horizontal and vertical oblique ones, which is why this type of fracture was used in the experiment (Russe, 1960). The movement found in the experiment is of no clinical importance, as it did not occur until the limit of normal rotation had been exceeded. In the first experiment on the dissected preparation, an attempt was made to demonstrate possible movement of the scaphoid fragments induced by changes in the tension of the radiocarpal ligament during supination/pronation (Verdan, 1960). In the second specimen the muscular apparatus was preserved THEJOURNAL OF HAND SURGERY
INSTABILITY
Fig. 2
OF SCAPHOID
FRACTURES
By Vicky Steptoe.
in order to demonstrate a instability, if any, of the fracture.
muscle-conditioned
The experimental results indicate that a short plaster cast sufficiently immobilizes scaphoid fractures.
References ADAMS, J. C. Outline of Fractures. Including Joint Injuries. Edinburgh, London and New York, Churchill Livingstone, 1972. ARKLESS, R. (1960). Cineradiography in Normal and Abnormal Wrists. American Journal of Roentgeology 96: 837-844. BOHLER, L. The Treatment of Fractures. 4th edition, William Wood and Co. (1935). Bristol John Wright (1936). COONEY, W. P., DOBYNS, J. H. and LINSCHEID, R. L. (1980). Fractures of the Scaphoid: A Rational Approach to Management. Clinical Orthopaedics and Related Research, 149: 90-97. GOLDMAN, S., LIPSCOMB, P. R. and TAYLOR, W. F. (1969). Immobilisation for Acute Carpal Scaphoid Fractures. Surgery, Gynecology & Obstetrics 129: 281-284.
VOL. 10-B No. 2 JUNE
1985
Acknowledgement
I am grateful to Vicky Steptoe for the drawing.
GRACE, R. V. (1929). Fracture of the Carpal Scaphoid. Annals of Surgery 89: 752.761. MacCONAILL, M. A. (1941). The Mechanical Anatomy of the Carpus and its Bearings on Some Surgical Problems. Journal of Anatomy 75: 166.175. RUSSE, 0. (1960). Fracture of the Carpal Navicular. Diagnosis, Non-operative Treatment, and Operative Treatment. The Journal of Bone and Joint Surgery 42A: 759-768. SQUIRE, M. (1959). Carpal mechanics and trauma. The Journal of Bone and Joint Surgery, 41B: 210. VERDAN, C. (1960). Fractures of the Scaphoid. Surgical Clinics of North America, 40: 461-464. WATSON-JONES, R. Injuries of the Wrist, In: Fractures and Joint Injuries. Vol. II 1960, Baltimore, Williams and Wilkins Co. 1960.
213
It is widely accepted that acute fractures of the scaphoid should be placed in a plaster cast with the first metacarpal and the proximal phalanx of the thumb fixed as recommended by Bohler (1935). On the other hand, it is a matter of discussion whether the elbow is to be incorporated in the cast. There have been advocates of both views (Bohler, 1935; Watson-Jones, 1960; Cooney, 1980; Adams, 1972; Verdan, 1960; Grace, 1929; Squire, 1959), as rotation in the forearm is assumed to entail a shift of the fragments. Little has been published concerning instability of these fractures solely due to the rotation of the forearm. Arkless (1960), describing it by cineradiography, found no indication for preventing rotation. Unfortunately, these experiments were performed without fixation. Verdan (1960) has reported small movements in the fracture during. supination and pronation, but without mentioning either the extent of the movement or the method of measurement. In the present study (performed on fresh specimens consisting of the upper arm, forearm, and hand) an attempt was made to record possible movements. The method has not been described previously. As casting immobilization would prevent measurement of such movement, it was decided to obtain the fixation needed by a Hoffmann external fixation apparatus.
fixed point of rotation was moved from the ulna to the radius. However, the normal relative movement between the radius-ulna and the hand remains unchanged. By this means the region to be measured, that is the scaphoid bone, was relatively immobilized, flexion/extension and deviation in the wrist were while rotation of the forearm was abolished, unhindered. Two Kirschner wires were used as markers, one through the distal part of the radius and one through the scaphoid bone. The distance between the wire ends was measured during a complete movement of rotation in the forearm. Osteotomy was then carried out through the waist of the scaphoid bone using an osteotome achieving a transverse fracture, first splitting the capsule of the joint on the dorsal side in the direction of the fibres. Both fragments were marked by Kirschner wires, and a fresh rotation of the forearm was carried out while recording the movement of the wires placed in the scaphoid fragments. On the second specimen only the skin and subcutaneous tissues were removed over the dorsal aspect of the wrist. In other respects the procedure was the same for both specimens.
Method
Each specimen consisted of the upper arm, forearm, and hand. First, the author made sure that movements in the elbow and wrist were normal. The test specimen was dissected free, leaving the ligaments intact. The distal part of the radius was fastened by screws to a fixed point, so that the volar aspect of the distal end of the radius was prone and the arm otherwise horizontal. The hand was fixed in relation to the forearm by a Hoffmann external fixation apparatus, extending from the radial aspect of the radius to the first, second and third metacarpals (Figure 1) in slight dorsiflexion (MacConaill, 1941). Thus, the Received for publication August, 1984. Dr. Per Falkenberg, 18 Edvard Griegsgade,
VOL. 10-B No. 2 JUNE
1985
DK-2100 Copenhagen,
Denmark.
The degree of rotation in the forearm was measured by a goniometer, with the stump of the humerus as the indicator and maximum pronation as zero point. The distance between the wire ends was measured with a slide gauge. The measurings were repeated three times, each time after a full rotation of the forearm. As the length of the wires was known, the movement could be expressed in degrees. Results
There was no movement between the inserted Kirschner wires in either specimen, intact or fractured, when supination was within the normal range of movement, that is O”-130”. Not until supination was forced, up to 211
PERFALKENBERG
Fig. 1
Specimen 1 with Hoffmanns
external fixation apparatus. The fragments of the fractured scaphoid are marked with Kirschner-wires.
165” in the former and 160” in the latter specimen, did incipient excursions appear, increasing until a maximum forced supination of 180” in the intact as well as the fractured scaphoid. TABLE
Radial Staph. I Staph. II Diff. in Mean dff. Angle distance in distance wire wire wire
2.18
intact
Specimen fractured
I,
2.34
0.17 0.17 0.20
0.18
2.1”
2.34
0.15 0.18 0.16
0.16
3.8”
Specimen intact
II,
Specimen fractured
II
6.25
1.51 1.49 1.56
1.52
3.1”
0.80 0.76 0.90
0.82
4.1”
2.30
4.77
4.54
5.28
By considering only the difference in distance between the wire ends, a triangle can be traced with all three sides known, that is the length of the wires and the difference in the distance between their ends. Thereupon, the desired angle can be calculated by the following formula: 212
=
b2 + c2 - a2
2 bc The distances are given in cm and were measured at maximum forced supination of 180”. Discussion
1
Specimen I,
Cosa
The external fixation used at present is rigid, but allows free rotation of the forearm. When a below-elbow plaster for fracture of the scaphoid is applied in the clinic, one obtains approximately the same conditions as those in the experiment. The finding of no movement in the scaphoid fragments during rotation of the forearm within the normal range shows that there is no indication for including the elbow in plaster immobilisation. According to Russe, the transverse fracture through the middle third of the scaphoid, is far more common than the horizontal and vertical oblique ones, which is why this type of fracture was used in the experiment (Russe, 1960). The movement found in the experiment is of no clinical importance, as it did not occur until the limit of normal rotation had been exceeded. In the first experiment on the dissected preparation, an attempt was made to demonstrate possible movement of the scaphoid fragments induced by changes in the tension of the radiocarpal ligament during supination/pronation (Verdan, 1960). In the second specimen the muscular apparatus was preserved THEJOURNAL OF HAND SURGERY
INSTABILITY
Fig. 2
OF SCAPHOID
FRACTURES
By Vicky Steptoe.
in order to demonstrate a instability, if any, of the fracture.
muscle-conditioned
The experimental results indicate that a short plaster cast sufficiently immobilizes scaphoid fractures.
References ADAMS, J. C. Outline of Fractures. Including Joint Injuries. Edinburgh, London and New York, Churchill Livingstone, 1972. ARKLESS, R. (1960). Cineradiography in Normal and Abnormal Wrists. American Journal of Roentgeology 96: 837-844. BOHLER, L. The Treatment of Fractures. 4th edition, William Wood and Co. (1935). Bristol John Wright (1936). COONEY, W. P., DOBYNS, J. H. and LINSCHEID, R. L. (1980). Fractures of the Scaphoid: A Rational Approach to Management. Clinical Orthopaedics and Related Research, 149: 90-97. GOLDMAN, S., LIPSCOMB, P. R. and TAYLOR, W. F. (1969). Immobilisation for Acute Carpal Scaphoid Fractures. Surgery, Gynecology & Obstetrics 129: 281-284.
VOL. 10-B No. 2 JUNE
1985
Acknowledgement
I am grateful to Vicky Steptoe for the drawing.
GRACE, R. V. (1929). Fracture of the Carpal Scaphoid. Annals of Surgery 89: 752.761. MacCONAILL, M. A. (1941). The Mechanical Anatomy of the Carpus and its Bearings on Some Surgical Problems. Journal of Anatomy 75: 166.175. RUSSE, 0. (1960). Fracture of the Carpal Navicular. Diagnosis, Non-operative Treatment, and Operative Treatment. The Journal of Bone and Joint Surgery 42A: 759-768. SQUIRE, M. (1959). Carpal mechanics and trauma. The Journal of Bone and Joint Surgery, 41B: 210. VERDAN, C. (1960). Fractures of the Scaphoid. Surgical Clinics of North America, 40: 461-464. WATSON-JONES, R. Injuries of the Wrist, In: Fractures and Joint Injuries. Vol. II 1960, Baltimore, Williams and Wilkins Co. 1960.
213