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Dynamic splinting following flexor tendon repair
DYNAMIC
SPLINTING FOLLOWING FLEXOR TENDON REPAIR N. D. CITRON and A. FORSTER
From the Royal National Orthopaedic Hospital, London. Electromyographic investigation of subjects wearing dynamic flexor tendon repair (Kleinert) splints shows a wide variability in the amount of contraction in the flexor digitorum profundus muscle during extension of the finger. We suggest there is no advantage in giving extra resistance to the extensor muscles, and that the strength of the rubber bands needs to be only just sufficient to flex the finger passively back to its resting position. Introduction Immediate postoperative mobilisation of repaired flexor tendons has been proposed as a means of reducing adhesion formation near the suture line (Strickland and Glogovac, 1980; Gelberman et al, 1983). This is especially important in tendon injuries in Zone 2 of Verdan (1979). One method advocated has been dynamic splinting as originally described by Young and Harmon (1951), and popularised by Kleinert and his associates (Kleinert et al, 1967; Lister et al, 1977). In this method, a rubber band is attached to the finger nail of the affected finger with the other end of the band near the wrist so as to keep the finger in an attitude of flexion. The patient is instructed actively to extend the finger against the resistance provided by the band and then to relax, so that the tension in the band returns the finger to its previous resting flexed attitude. This provides excursion at the tendon repair site without causing tension at the suture line. The method by which this is achieved is said to be two fold; firstly, the shortening of the rubber band pulls the finger into flexion without any need for contraction of the flexor muscle, and secondly, the extension of the finger against resistance is said to inhibit contraction of the flexor muscle by reinforcing the normal reciprocal agonist-antagonist reflex mechanism. Variants of the traction system have been proposed (Becker and Hardy, 1980; Slattery and McGrouther, 1984; Kleinert, 1986), and the purpose of this study was to determine the optimal resistance needed in the splint to most inhibit the flexor muscle, thus allowing a rational choice to be made between the different alternatives. Materials and Methods Five subjects were used in the experiment: four normal individuals and one patient who had undergone repair of both flexor tendons in zone 2, ten days previously. All were right-handed, and the left hand was used in all five, who had splints made for them out of a thermoplastic material, according to the method described by Lister et al, (1977), and held in place with velcro straps. A standard commercial rubber band, of resting length 9-12 Received for publication 19th March 1986. Mr. N. Citron, Royal Orthopaedic Hospital, 45-51 Bolsover Street, London WlP SAQ.
96
centimetres, was attached to the fingernail of one finger with a dress hook glued in place with ‘superglue’. A pair of surface electrodes was placed over the extensor muscle, and a needle electrode inserted into the muscle belly of flexor digitorum profundus serving that finger, using landmarks as described by Delagi and Perotto (1980). The position of the electrode was verified by getting the subject to flex the terminal joint of his splinted finger. No response could be elicited when the subject flexed the proximal interphalangeal joint of the wrist, thereby confirming placement of the electrode. One subject had an additional needle electrode placed in the third lumbrical muscle. The output from the recording leads was displayed on a Medelec M56 and recorded on light-sensitive paper for later analysis. TABLE
Subject
Age
sex
(Ysl
1 E F F M
: 4 5 * Cut
both
z* 25 35 30
1
Finger Tested Left Left Left Left Left
Ring Middle Middle Ring Ring
F. D. P. and F. D. S. with
Reciprocal Relaxation
Co-contraction
primary
-
+ + * repairs
+ 10 days previously.
Results The most striking feature of the results was the variability between subjects (Table 1). They showed a range of responses; one subject had no profundus activity during extension of the finger both with and without the rubber bands, and even by increasing the tension in the bands by shortening them, it was impossible to induce profundus activity (Figure 1). In contrast to this, two subjects showed simultaneous contraction (synkinesis) of the profundus with any degree of finger extension, even without resistance (Figure 2): the application of resistance through the rubber band served to increase rather than decrease the contraction of profundus (Figure 3). One of these two subjects was the patient with a recent tendon repair. Recording was continued with the wrist and finger joints in different starting positions, but this did not seem to influence the results obtained in any given patient. THE JOURNAL
OF HAND
SURGERY
DYNAMIC
SPLINTING
FDP RING FINGER
--1 Fig.
j 1
Subject
3. Showing
EXTEND complete
lack
EXTEND
I of contraction
of F.D.P.
during
finger
extension
1 in Kleinert
EXTEND
I splint.
EXTENSORS
Fig. 2a
Subject
1. Some contraction
of F.D.P.
just
visible
on extension
Recording from the lumbrical showed that it was active during resisted extension (Figure 4), at full extension against the front of the splint with the band at full tension, one subject who had previously had a fairly silent profundus, developed an effort tremor with alarge co-contractions of the profundus (Figure 5). Only one patient showed the classic increased flexor inhibition with the rubber bands described by Lister et al, (1977), and Kleinert (1973, (Figure 6), with no activity in the profundus during extension although some resting profundus activity was present both before and after this.
of fingers
without
resistance.
elicit movement in the distal interphalangeal joint, to ensure that what was being observed was of some significance. It was not possible to measure the actual force of contraction being developed in the profundus tendon in the digital canal, for although the amplitude of concentric needle EMG recordings is considered to be linearly related to force (Fuglsang-Frederikson, 1981), the simultaneous contraction of lumbricals prevents EXTENSORS
Discussion
The significance of the findings described here may not be great in practical terms because rupture of the repair site appears to be a rare problem in clinical practice (Lister et al, 1977), though others have not found it so rare. Much more common is a loss of extension due to inability of the patient to extend his fingers against a rubber band which is too strong, thereby developing a flexion contracture. The magnitude of the electrical activity in the profundus was compared to that needed to VOL.
12-B No. 1 FEBRUARY
1987
FDP RING
;“i/$! 1
FINGER _i;l_iL_ Resisted
Fig.
2b
Subject 1. Showing increased as against out of splint.
extension
profundus
in splint
contraction
in splint
97
N. D. CITRON
AND
A. FORSTER
FDP
MIDDLE
FINGER 1-L
Fig.
3a
Subject
2. Some
contraction
FDP MIDDLE
of F.D.P.
just
EXTEND
I
visible
on extension
of fingers
in splint
but
without
resistance.
FINGER
. .
--r-vp @r
- I
1
‘: Extend
Fig.
3b
Subject
2. Recording
FDP MIDDLE
from
F.D.P.
only.
3c
Subject
contraction
occurs
2. Increasing
the splint
resistance
in splint (doubling
with the rubber
determination of the precise EMG/force relationship here. As the origin of the lumbrical is proximal to the digital canal, its contraction might take some tension off part of the profundus tendon in the digital sheath. Previous studies (Long et al, 1986) have shown that simultaneous contraction of lumbrical and profundus does not occur during normal finger movements, but this does not preclude them occurring in resisted movement in certain individuals (Figure 4). Simultaneous contraction of extrinsic flexors and extensors had been previously noted by Person et al, (1968). They found that during active finger extension, the flexor digitorum superficialis is activated to prevent simultaneous extension of adjacent fingers under the influence of the juncturae tendinae. When the hand is in a dynamic splint as classically described, the metacarpophalangeal joints are kept in some flexion, and the juncturae do not thus really ever come into play. 98
during
resisted
extension
in Kleinert
splint.
FINGER
Extension Fig.
More
in splint
increased bands)
I-
resistance
increases
the co-contraction.
In the original description of the splinting method by Young and Harmon, extension of the finger against the rubber band was done passively by the patient, so the only tension at the repair site was the viscoelastic resistance of the flexor mass. It has been pointed out that the length-tension curve of a rubber band as used in this type of splint shows a rapid increase of tension with stretch, which may be reduced by using a longer initial starting length (Brand, 1985). We suggest that there might be real advantages in this. Kleinert has himself described a modification to the splint in which a special spring device is used to give a more linear resistance (Kleinert, 1986), and Becker and Hardy (1980) have described an ingenious use of a pulley and rubber band to give a similar effect. It would seem that the correct resistance to be applied using these methods would be the minimum needed to return the fingers to their flexed position. Giving an extra resistance to the extensors may not be of benefit in reducing flexor profundus contraction during extension. THE
JOURNAL
OF HAND
SURGERY
DYNAMIC
SPLINTING
3rd LUM
FDP RING
I Resisted Fig.
4
Subject
4. Showing
co-contraction
of lumbrical
with
extension its component
1 in splint
of the flexor
digitorum
profundus.
EXTENSORS
FDP RING Fig. 5
Subject
5. Showing
FDP RING
effort
tremor
with
co-contraction
of flexors
VOL.
6
Subject
4. Showing
12-B No. 1 FEBRUARY
when
band
tension
near maximum
in splint.
FINGER Extend
Fig.
and extensors
FINGER
the classical
1987
reciprocal
relaxation
against
of flexors
resistance
and extensors
in splint
in splint. 99
N. D. CITRON
Acknowledgments We would like to thank Dr. C. Wynn-Parry for his help and advice, and Ms D. Cavers of the occupational therapy department at the Edgware General Hospital, for making the splints used in this study. I would also like to thank MS V. Aurens of the R.N.O.H. for her help with the illustrations.
References BECKER, H and HARDY, M. (1980). A Constant Tension Dynamic Splint. Plastic and Reconstructive Surgery, 66: 1: 148-150. BRAND, P. W. (1985). In: ClinicalBiomechanics of the Hand ppllO-112. C. V. Mosby. St. Louis. (1985). DELAGI, E. F. and PEROTTO, A. (1980). Anatomic Guide for the Electromyographer - The Limbs (2nd Edition). C. Thomas, Springfield, Illinois. FUGLSANG-FREDERIKSEN, A. Electrical Activity and Force During Voluntary Contraction of Normal and Diseased Muscle. Acta Neurologica Scandinavica. Munksgaard Copenhagen (1981), Vol. 63: Supplement 83. GELBERMAN, R. H., BERG, J. S. V., LUNDBORG, G. N. and AKESON, W. H. (1983). Flexor Tendon Healing and Restoration of the Gliding Surface. An Ultrastructural Study in Dogs. The Journal of Bone and Joint Surgery, 65A: 1: 70-80. KLEINERT, H. E., KUTZ, J. E., ASHBELL, T. S. and MARTINEZ, E. (1967). Primary Repair of Lacerated Flexor Tendons in “No Man’s Land”. The Journal of Bone and Joint Surgery, 49A: 3: 577.
100
AND
A. FORSTER KLEINERT, H. E., KUTZ, J. E. and COHEN, M. J. Primary repair of zone 2 flexor tendon lacerations. In AAOS Symposium on Tendon Surgery in the Hand. St. Louis, C. V. Mosby. (1975) pp91-104. KLEINERT, H. E. (1986). Lecture, British Orthopaedic Association lnstructional Course, London. LISTER, G. D., KLEINERT, H. E., KUTZ, J. E. and ATASOY, E. (1977). Primary flexor tendon repair followed by immediate controlled mobilization. The Journal of Hand Surgery, 2: 6: 441.451. LONG, C. (1986). Intrinsic-Extrinsic .Muscle Control of the Fingers. Journal of Bone and Joint Surgery, 50A: 5: 973-984. PERSON, R. S., ROSHCHINA, N. A. (1958). Electromyographic Investigation on Co-ordination of Antagonistic Muscular Activity in Movements of the Fingers. Journal of Physiology U.S.S.R., 94: 419.426. SLATTERY, P. G. and McGROUTHER, D. A. (1984). A Modified Kleinert Controlled Mobilization Splint Following Flexor Tendon Repair. The Journal of Hand Surgery, 9B: 2: 217-218. STRICKLAND, .I. W. and GLOGOVAC, S. V. (1980). Digital function following flexor tendon repair in Zone 2: A comparison of immobilisation and controlled passive motion techniques. The Journal of Hand Surgery, 5: 6: 531.543. VERDAN, C. and MICHON, J. (1986). Le traitment des plaies des tendons fltchisseurs des doigts. Revue de Chirurgie Orthopkdique et Reparatrice de I’Appareil Moteur, 47: 3: 285-425. YOUNG, R. E. S. and HARMON, J. M. (1951). Repair of Tendon Injuries of the Hand. Annals of Surgery, 15 I: 4: 562-566.
THE
JOURNAL
OF HAND
SURGERY
SPLINTING FOLLOWING FLEXOR TENDON REPAIR N. D. CITRON and A. FORSTER
From the Royal National Orthopaedic Hospital, London. Electromyographic investigation of subjects wearing dynamic flexor tendon repair (Kleinert) splints shows a wide variability in the amount of contraction in the flexor digitorum profundus muscle during extension of the finger. We suggest there is no advantage in giving extra resistance to the extensor muscles, and that the strength of the rubber bands needs to be only just sufficient to flex the finger passively back to its resting position. Introduction Immediate postoperative mobilisation of repaired flexor tendons has been proposed as a means of reducing adhesion formation near the suture line (Strickland and Glogovac, 1980; Gelberman et al, 1983). This is especially important in tendon injuries in Zone 2 of Verdan (1979). One method advocated has been dynamic splinting as originally described by Young and Harmon (1951), and popularised by Kleinert and his associates (Kleinert et al, 1967; Lister et al, 1977). In this method, a rubber band is attached to the finger nail of the affected finger with the other end of the band near the wrist so as to keep the finger in an attitude of flexion. The patient is instructed actively to extend the finger against the resistance provided by the band and then to relax, so that the tension in the band returns the finger to its previous resting flexed attitude. This provides excursion at the tendon repair site without causing tension at the suture line. The method by which this is achieved is said to be two fold; firstly, the shortening of the rubber band pulls the finger into flexion without any need for contraction of the flexor muscle, and secondly, the extension of the finger against resistance is said to inhibit contraction of the flexor muscle by reinforcing the normal reciprocal agonist-antagonist reflex mechanism. Variants of the traction system have been proposed (Becker and Hardy, 1980; Slattery and McGrouther, 1984; Kleinert, 1986), and the purpose of this study was to determine the optimal resistance needed in the splint to most inhibit the flexor muscle, thus allowing a rational choice to be made between the different alternatives. Materials and Methods Five subjects were used in the experiment: four normal individuals and one patient who had undergone repair of both flexor tendons in zone 2, ten days previously. All were right-handed, and the left hand was used in all five, who had splints made for them out of a thermoplastic material, according to the method described by Lister et al, (1977), and held in place with velcro straps. A standard commercial rubber band, of resting length 9-12 Received for publication 19th March 1986. Mr. N. Citron, Royal Orthopaedic Hospital, 45-51 Bolsover Street, London WlP SAQ.
96
centimetres, was attached to the fingernail of one finger with a dress hook glued in place with ‘superglue’. A pair of surface electrodes was placed over the extensor muscle, and a needle electrode inserted into the muscle belly of flexor digitorum profundus serving that finger, using landmarks as described by Delagi and Perotto (1980). The position of the electrode was verified by getting the subject to flex the terminal joint of his splinted finger. No response could be elicited when the subject flexed the proximal interphalangeal joint of the wrist, thereby confirming placement of the electrode. One subject had an additional needle electrode placed in the third lumbrical muscle. The output from the recording leads was displayed on a Medelec M56 and recorded on light-sensitive paper for later analysis. TABLE
Subject
Age
sex
(Ysl
1 E F F M
: 4 5 * Cut
both
z* 25 35 30
1
Finger Tested Left Left Left Left Left
Ring Middle Middle Ring Ring
F. D. P. and F. D. S. with
Reciprocal Relaxation
Co-contraction
primary
-
+ + * repairs
+ 10 days previously.
Results The most striking feature of the results was the variability between subjects (Table 1). They showed a range of responses; one subject had no profundus activity during extension of the finger both with and without the rubber bands, and even by increasing the tension in the bands by shortening them, it was impossible to induce profundus activity (Figure 1). In contrast to this, two subjects showed simultaneous contraction (synkinesis) of the profundus with any degree of finger extension, even without resistance (Figure 2): the application of resistance through the rubber band served to increase rather than decrease the contraction of profundus (Figure 3). One of these two subjects was the patient with a recent tendon repair. Recording was continued with the wrist and finger joints in different starting positions, but this did not seem to influence the results obtained in any given patient. THE JOURNAL
OF HAND
SURGERY
DYNAMIC
SPLINTING
FDP RING FINGER
--1 Fig.
j 1
Subject
3. Showing
EXTEND complete
lack
EXTEND
I of contraction
of F.D.P.
during
finger
extension
1 in Kleinert
EXTEND
I splint.
EXTENSORS
Fig. 2a
Subject
1. Some contraction
of F.D.P.
just
visible
on extension
Recording from the lumbrical showed that it was active during resisted extension (Figure 4), at full extension against the front of the splint with the band at full tension, one subject who had previously had a fairly silent profundus, developed an effort tremor with alarge co-contractions of the profundus (Figure 5). Only one patient showed the classic increased flexor inhibition with the rubber bands described by Lister et al, (1977), and Kleinert (1973, (Figure 6), with no activity in the profundus during extension although some resting profundus activity was present both before and after this.
of fingers
without
resistance.
elicit movement in the distal interphalangeal joint, to ensure that what was being observed was of some significance. It was not possible to measure the actual force of contraction being developed in the profundus tendon in the digital canal, for although the amplitude of concentric needle EMG recordings is considered to be linearly related to force (Fuglsang-Frederikson, 1981), the simultaneous contraction of lumbricals prevents EXTENSORS
Discussion
The significance of the findings described here may not be great in practical terms because rupture of the repair site appears to be a rare problem in clinical practice (Lister et al, 1977), though others have not found it so rare. Much more common is a loss of extension due to inability of the patient to extend his fingers against a rubber band which is too strong, thereby developing a flexion contracture. The magnitude of the electrical activity in the profundus was compared to that needed to VOL.
12-B No. 1 FEBRUARY
1987
FDP RING
;“i/$! 1
FINGER _i;l_iL_ Resisted
Fig.
2b
Subject 1. Showing increased as against out of splint.
extension
profundus
in splint
contraction
in splint
97
N. D. CITRON
AND
A. FORSTER
FDP
MIDDLE
FINGER 1-L
Fig.
3a
Subject
2. Some
contraction
FDP MIDDLE
of F.D.P.
just
EXTEND
I
visible
on extension
of fingers
in splint
but
without
resistance.
FINGER
. .
--r-vp @r
- I
1
‘: Extend
Fig.
3b
Subject
2. Recording
FDP MIDDLE
from
F.D.P.
only.
3c
Subject
contraction
occurs
2. Increasing
the splint
resistance
in splint (doubling
with the rubber
determination of the precise EMG/force relationship here. As the origin of the lumbrical is proximal to the digital canal, its contraction might take some tension off part of the profundus tendon in the digital sheath. Previous studies (Long et al, 1986) have shown that simultaneous contraction of lumbrical and profundus does not occur during normal finger movements, but this does not preclude them occurring in resisted movement in certain individuals (Figure 4). Simultaneous contraction of extrinsic flexors and extensors had been previously noted by Person et al, (1968). They found that during active finger extension, the flexor digitorum superficialis is activated to prevent simultaneous extension of adjacent fingers under the influence of the juncturae tendinae. When the hand is in a dynamic splint as classically described, the metacarpophalangeal joints are kept in some flexion, and the juncturae do not thus really ever come into play. 98
during
resisted
extension
in Kleinert
splint.
FINGER
Extension Fig.
More
in splint
increased bands)
I-
resistance
increases
the co-contraction.
In the original description of the splinting method by Young and Harmon, extension of the finger against the rubber band was done passively by the patient, so the only tension at the repair site was the viscoelastic resistance of the flexor mass. It has been pointed out that the length-tension curve of a rubber band as used in this type of splint shows a rapid increase of tension with stretch, which may be reduced by using a longer initial starting length (Brand, 1985). We suggest that there might be real advantages in this. Kleinert has himself described a modification to the splint in which a special spring device is used to give a more linear resistance (Kleinert, 1986), and Becker and Hardy (1980) have described an ingenious use of a pulley and rubber band to give a similar effect. It would seem that the correct resistance to be applied using these methods would be the minimum needed to return the fingers to their flexed position. Giving an extra resistance to the extensors may not be of benefit in reducing flexor profundus contraction during extension. THE
JOURNAL
OF HAND
SURGERY
DYNAMIC
SPLINTING
3rd LUM
FDP RING
I Resisted Fig.
4
Subject
4. Showing
co-contraction
of lumbrical
with
extension its component
1 in splint
of the flexor
digitorum
profundus.
EXTENSORS
FDP RING Fig. 5
Subject
5. Showing
FDP RING
effort
tremor
with
co-contraction
of flexors
VOL.
6
Subject
4. Showing
12-B No. 1 FEBRUARY
when
band
tension
near maximum
in splint.
FINGER Extend
Fig.
and extensors
FINGER
the classical
1987
reciprocal
relaxation
against
of flexors
resistance
and extensors
in splint
in splint. 99
N. D. CITRON
Acknowledgments We would like to thank Dr. C. Wynn-Parry for his help and advice, and Ms D. Cavers of the occupational therapy department at the Edgware General Hospital, for making the splints used in this study. I would also like to thank MS V. Aurens of the R.N.O.H. for her help with the illustrations.
References BECKER, H and HARDY, M. (1980). A Constant Tension Dynamic Splint. Plastic and Reconstructive Surgery, 66: 1: 148-150. BRAND, P. W. (1985). In: ClinicalBiomechanics of the Hand ppllO-112. C. V. Mosby. St. Louis. (1985). DELAGI, E. F. and PEROTTO, A. (1980). Anatomic Guide for the Electromyographer - The Limbs (2nd Edition). C. Thomas, Springfield, Illinois. FUGLSANG-FREDERIKSEN, A. Electrical Activity and Force During Voluntary Contraction of Normal and Diseased Muscle. Acta Neurologica Scandinavica. Munksgaard Copenhagen (1981), Vol. 63: Supplement 83. GELBERMAN, R. H., BERG, J. S. V., LUNDBORG, G. N. and AKESON, W. H. (1983). Flexor Tendon Healing and Restoration of the Gliding Surface. An Ultrastructural Study in Dogs. The Journal of Bone and Joint Surgery, 65A: 1: 70-80. KLEINERT, H. E., KUTZ, J. E., ASHBELL, T. S. and MARTINEZ, E. (1967). Primary Repair of Lacerated Flexor Tendons in “No Man’s Land”. The Journal of Bone and Joint Surgery, 49A: 3: 577.
100
AND
A. FORSTER KLEINERT, H. E., KUTZ, J. E. and COHEN, M. J. Primary repair of zone 2 flexor tendon lacerations. In AAOS Symposium on Tendon Surgery in the Hand. St. Louis, C. V. Mosby. (1975) pp91-104. KLEINERT, H. E. (1986). Lecture, British Orthopaedic Association lnstructional Course, London. LISTER, G. D., KLEINERT, H. E., KUTZ, J. E. and ATASOY, E. (1977). Primary flexor tendon repair followed by immediate controlled mobilization. The Journal of Hand Surgery, 2: 6: 441.451. LONG, C. (1986). Intrinsic-Extrinsic .Muscle Control of the Fingers. Journal of Bone and Joint Surgery, 50A: 5: 973-984. PERSON, R. S., ROSHCHINA, N. A. (1958). Electromyographic Investigation on Co-ordination of Antagonistic Muscular Activity in Movements of the Fingers. Journal of Physiology U.S.S.R., 94: 419.426. SLATTERY, P. G. and McGROUTHER, D. A. (1984). A Modified Kleinert Controlled Mobilization Splint Following Flexor Tendon Repair. The Journal of Hand Surgery, 9B: 2: 217-218. STRICKLAND, .I. W. and GLOGOVAC, S. V. (1980). Digital function following flexor tendon repair in Zone 2: A comparison of immobilisation and controlled passive motion techniques. The Journal of Hand Surgery, 5: 6: 531.543. VERDAN, C. and MICHON, J. (1986). Le traitment des plaies des tendons fltchisseurs des doigts. Revue de Chirurgie Orthopkdique et Reparatrice de I’Appareil Moteur, 47: 3: 285-425. YOUNG, R. E. S. and HARMON, J. M. (1951). Repair of Tendon Injuries of the Hand. Annals of Surgery, 15 I: 4: 562-566.
THE
JOURNAL
OF HAND
SURGERY