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Grip strength following carpal tunnel decompression
GRIP
STRENGTH
FOLLOWING DECOMPRESSION
CARPAL
TUNNEL
W. J. LEACH, C. ESLER and T. D. SCOTT From The Royal Cornwall Hospital, Truro, UK
To monitor the effect of open carpal tunnel decompression on grip strength in the hand, a prospective study was made of 25 patients undergoing a total of 31 operations. Hand grip, key pinch and pulp-to-pulp pinch strengths were measured pre-operatively and at regular intervals until 1 year following operation. At that time there was no significant difference in the hand grip and pulp-topulp pinch strengths compared to their pre-operative values, but the key pinch in females showed a marginally significant reduction (P= 0.04) compared to the pre-operative value.
Journal of Hand Surgery (British and European Volume, 1993) 18B: 750-7.52 There have been reports of reduction in grip strength following carpal tunnel decompression. Das and Brown (1976) found 2 cases of persistent weakness of grip after 170 operations. One of these was due to entrapment of the thenar branch of the median nerve in scar tissue and was relieved by decompression and neurolysis. Gartsmann et al (1986), in a retrospective study of 50 cases, claimed to show an average post-operative decrease in grip strength of 12%, associated with a mean widening of the carpal arch of 13.6%. Eversmann (1988) comments that grip strength decreases following division of the flexor retinaculum but recovers to its original value in most patients by about 6 months. Unfortunately the author does not refer to the work upon which he bases his statement. To date, no prospective evaluation of grip strength following carpal tunnel decompression has been reported, although the conclusions drawn by Gartsmann et al (1986) have important clinical, social and medicolegal implications. With this in mind, it was decided to embark upon a prospective study of patients undergoing carpal tunnel decompression.
MATERIAL
Pinch Gauge, PC 5030HPG (Camp Ltd, Winchester, Hants) respectively. The measurement of grip strength was carried out according to a strict protocol. The patients were assessed while comfortably seated, with the shoulder adducted, the elbow flexed to 90” and the forearm in a neutral position. Three successive readings of the maximal grip strength were taken with the dynamometer set on the second notch, and the average of the three used for data analysis. Key pinch was recorded in a seated position as described, with the gauge held between the pad of the thumb and the radial border of the middle phalanx of the index finger. Pulp-to-pulp pinch was recorded with the gauge held between the pulps of the thumb and index finger. The operations were carried out under local or general anaesthesia and with tourniquet control. In all cases the flexor retinaculum was divided under direct vision; epineurotomy was performed if there was marked perineural fibrosis with hour-glass deformity of the nerve. The grip strengths were measured pre-operatively and at 2 weeks, 6 weeks, 3 months, 6 months and 1 year post-operatively.
AND METHODS
RESULTS
25 consecutive
patients undergoing open carpal tunnel decompression at the Royal Cornwall Hospital, Truro, between 1 March and 30 May 1991 were studied. 6 patients had bilateral procedures carried out at one sitting, giving a total of 31 operations. 14 of the patients were female and 11 were male. The mean age was 43 years (range 25-80 years). Each of the patients was interviewed and examined pre-operatively and at regular intervals until 1 year after operation. Pre-operatively, details of age, sex, symptomatology, hand dominance, past medical history and method of diagnosis were made. It was also noted whether the condition was, or had been, bilateral. None of the patients had diseases thought likely to interfere significantly with grip strength, such as rheumatoid arthritis. Hand grip strength, key pinch and pulp-to-pulp pinch strength were measured using the Jamar Hydraulic Dynamometer, model 003051 and the Jamar Hydraulic
24 of the 25 patients were followed until at least 1 year after operation. One man who had a unilateral procedure was lost to follow-up. 2 other cases had insufficient initial data recorded to allow comparison of the subsequent key grip and pulp-to-pulp pinch strength. Statistical analysis was carried out using analysis of variance, as 6 of the patients had readings taken from both hands following bilateral procedures. Symptoms
All patients complained of persisting scar tenderness after the wound had healed, although this resolved in all cases by 12 weeks. There was good relief of pain following all but one of the operations. This 45-year old man presented with left-sided lateral forearm and hand pain. Tinel’s and Phalen’s tests were positive, although 750
GRIP STREKGTH FOLLOWING CT RELEASE
‘-b-i
6
12
26
52
Weeks,post-owration Fig 1
Mean hand decompression.
Table l-Hand
strength
Fig 2 following
carpal
tunnel
grip strength before and after carpal tunnel decompression
Mean pulp-to-pulp decompression.
1 year post-operation
DifSerence
All
24.8 (SD 11.9)
25.1 (SD 12.9)
NS
Men Women
31.3 (SD 12.8) 21.0 (SD 9.56)
33.3 (SD 14.0) 20.3 (SD 9.54)
NS NS
Difference between men and women
P
P
pinch strength before and after carpal tunnel decompression
pinch
strength
following
carpal
tunnel
(kg/F)
Pre-operation
Table 2-Key :,I
grip
(kg/F)
DifSerence
‘,’
Pre-operation
I year post-operation
All
6.85 (SD 2.30)
6.26 (SD 2.45)
NS
Men Women
8.11 (SD 2.30) 6.16 (SD 2.09)
8.12 (SD 2.45) 5.23 (SD 1.93)
NS
Difference between men and women
P
P
nerve conduction studies were equivocal for median nerve compression at the wrist. His symptoms have worsened since operation and he has also developed increasing neck pain, with X-ray evidence of degenerative changes at the U-6 level of his cervical spine. Hand grip strength Men had a significantly higher initial grip strength than females (Table 1). Figure 1 shows the grip strength is seen to decrease after operation, but gradually recovers to its pre-operative value by about 6 months. At 1 year, for both sexes, the mean grip strength is not significantly altered compared to the initial value but the significant difference between the sexes is maintained.
Key pinch strength Again, men had a significantly higher pre-operative mean strength of pinch grip than women (Table 2). In both sexes the key pinch strength decreases after operation, but recovers gradually (Fig 2). The values for male patients returned to the pre-operative level at 1 year, but were still reduced in women. This reduction was marginally significant. The difference between the sexes continued to be highly significant.
Pulp-to-pulp pinch strength Men had a significantly higher women (Table 3). After an initial
initial strength than decrease immediately
152
THE JOURNAL
Table 3-Pulp-to-pulp
OF HAND
SURGERY
VOL. 18B No. 5 OCTOBER
1993
pinch strength after carpal tunnel decompression (kg/F) Difference Pre-operation
I year post-operation
All
4.42 (SD 1.98)
4.71 (SD 2.09)
NS
Men Women
5.36 (SD 2.40) 3.9 (SD 1.47)
5.63 (SD 2.34) 4.21 (SD 1.74)
NS NS
Difference between men and women
P
P
_
after operation, the strengths for both male and female patients returned to their normal values by 6 months, and were increased at 1 year (Fig 3). This increase was not statistically significant, although the significant difference between the sexes was maintained.
not a feature of the available normative data (Mathiowetz et al 1985; 1986). From our study it appears that return of pre-operative strength can be expected 1 year after operation, but we found a marginally significant reduction in key pinch strength in the female group.
6
Acknowledgements The authors wish to thank Mrs Caroline Meikle of the Department of Occuoational Theraov for her helo and co-ooeration. and Mrs Janet Freeman. Director of the Department of Medical Aidit, fo; her help with statistical analysis.
References
24 II
2
6
12
26
DAS, S. K. and BROWN, H. G. (1976). In search of complications of carpal tunnel decompression. The Hand, 8: 3: 243-249. EVERSMANN, W. Entrapment and Compression Neuropathies. In: Green, D. P. (Ed.): Operative Hand Surgery, 2nd Edn. New York, Churchill Livingstone, 1988: 1437-1438. GARTSMAN, G. M., KOVACH, J. C., CROUCH, C. C., NOBLE, P. C. and BENNETT, J. B. (1986). Carpal arch alterations after carpal tunnel release. Journal of Hand Surgery, 11A: 3: 372-374. MATHIOWETZ, V., KASHMAN, N., VOLLAND, G., WEBER, K., DOWE, M. and ROGERS, S. (1985). Grip and pinch strength: Normative data for adults. Archives of Physical Medicine and Rehabilitation, 66:
52
Weeks, post-oaeration
Fig 3
Mean key decompression.
grip
strength
following
carpal
tunnel
DISCUSSION
The operation of carpal tunnel decompression is commonly performed in a wide variety of age groups in both sexes. Grip strengths may be affected in several ways after carpal tunnel decompression. The discomfort of the surgical scar will reduce the strength of the hand by inhibition, and disuse for several weeks may lead to muscle weakness. There are also the theoretical changes to the carpal anatomy after division of the flexor retinaculum. Conversely, assuming that operation is successful, an improved innervation of the thenar muscles and sensation in the hand might be expected to lead to an increase in pinch and grip strength, with gradual improvement until full recovery is achieved. Gartsmann et al (1986) showed widening of the carpal arch after operation in association with a reduction in grip strength. This study was retrospective, using the other hand as a control, and compensating for presumed relative weakness in the non-dominant hand, which was
69-74. MATHIOWETZ, V., WIEMER, D. M. and FEDERMAN, S. M. (1986). Grip and pinch strength: Norms for 6.to 19.year olds. American Journal of Occupational Therapy, 40: 705-711.
Accepted: I June 1993 W. J. Leach FRCS Ed, Senior Registrar. Hospital,
0
Glasgow
1993 The British
GSI 4TF, Society
Department
UK. for Surgery
of the Hand
of Orthopaedics,
Southern
General
STRENGTH
FOLLOWING DECOMPRESSION
CARPAL
TUNNEL
W. J. LEACH, C. ESLER and T. D. SCOTT From The Royal Cornwall Hospital, Truro, UK
To monitor the effect of open carpal tunnel decompression on grip strength in the hand, a prospective study was made of 25 patients undergoing a total of 31 operations. Hand grip, key pinch and pulp-to-pulp pinch strengths were measured pre-operatively and at regular intervals until 1 year following operation. At that time there was no significant difference in the hand grip and pulp-topulp pinch strengths compared to their pre-operative values, but the key pinch in females showed a marginally significant reduction (P= 0.04) compared to the pre-operative value.
Journal of Hand Surgery (British and European Volume, 1993) 18B: 750-7.52 There have been reports of reduction in grip strength following carpal tunnel decompression. Das and Brown (1976) found 2 cases of persistent weakness of grip after 170 operations. One of these was due to entrapment of the thenar branch of the median nerve in scar tissue and was relieved by decompression and neurolysis. Gartsmann et al (1986), in a retrospective study of 50 cases, claimed to show an average post-operative decrease in grip strength of 12%, associated with a mean widening of the carpal arch of 13.6%. Eversmann (1988) comments that grip strength decreases following division of the flexor retinaculum but recovers to its original value in most patients by about 6 months. Unfortunately the author does not refer to the work upon which he bases his statement. To date, no prospective evaluation of grip strength following carpal tunnel decompression has been reported, although the conclusions drawn by Gartsmann et al (1986) have important clinical, social and medicolegal implications. With this in mind, it was decided to embark upon a prospective study of patients undergoing carpal tunnel decompression.
MATERIAL
Pinch Gauge, PC 5030HPG (Camp Ltd, Winchester, Hants) respectively. The measurement of grip strength was carried out according to a strict protocol. The patients were assessed while comfortably seated, with the shoulder adducted, the elbow flexed to 90” and the forearm in a neutral position. Three successive readings of the maximal grip strength were taken with the dynamometer set on the second notch, and the average of the three used for data analysis. Key pinch was recorded in a seated position as described, with the gauge held between the pad of the thumb and the radial border of the middle phalanx of the index finger. Pulp-to-pulp pinch was recorded with the gauge held between the pulps of the thumb and index finger. The operations were carried out under local or general anaesthesia and with tourniquet control. In all cases the flexor retinaculum was divided under direct vision; epineurotomy was performed if there was marked perineural fibrosis with hour-glass deformity of the nerve. The grip strengths were measured pre-operatively and at 2 weeks, 6 weeks, 3 months, 6 months and 1 year post-operatively.
AND METHODS
RESULTS
25 consecutive
patients undergoing open carpal tunnel decompression at the Royal Cornwall Hospital, Truro, between 1 March and 30 May 1991 were studied. 6 patients had bilateral procedures carried out at one sitting, giving a total of 31 operations. 14 of the patients were female and 11 were male. The mean age was 43 years (range 25-80 years). Each of the patients was interviewed and examined pre-operatively and at regular intervals until 1 year after operation. Pre-operatively, details of age, sex, symptomatology, hand dominance, past medical history and method of diagnosis were made. It was also noted whether the condition was, or had been, bilateral. None of the patients had diseases thought likely to interfere significantly with grip strength, such as rheumatoid arthritis. Hand grip strength, key pinch and pulp-to-pulp pinch strength were measured using the Jamar Hydraulic Dynamometer, model 003051 and the Jamar Hydraulic
24 of the 25 patients were followed until at least 1 year after operation. One man who had a unilateral procedure was lost to follow-up. 2 other cases had insufficient initial data recorded to allow comparison of the subsequent key grip and pulp-to-pulp pinch strength. Statistical analysis was carried out using analysis of variance, as 6 of the patients had readings taken from both hands following bilateral procedures. Symptoms
All patients complained of persisting scar tenderness after the wound had healed, although this resolved in all cases by 12 weeks. There was good relief of pain following all but one of the operations. This 45-year old man presented with left-sided lateral forearm and hand pain. Tinel’s and Phalen’s tests were positive, although 750
GRIP STREKGTH FOLLOWING CT RELEASE
‘-b-i
6
12
26
52
Weeks,post-owration Fig 1
Mean hand decompression.
Table l-Hand
strength
Fig 2 following
carpal
tunnel
grip strength before and after carpal tunnel decompression
Mean pulp-to-pulp decompression.
1 year post-operation
DifSerence
All
24.8 (SD 11.9)
25.1 (SD 12.9)
NS
Men Women
31.3 (SD 12.8) 21.0 (SD 9.56)
33.3 (SD 14.0) 20.3 (SD 9.54)
NS NS
Difference between men and women
P
P
pinch strength before and after carpal tunnel decompression
pinch
strength
following
carpal
tunnel
(kg/F)
Pre-operation
Table 2-Key :,I
grip
(kg/F)
DifSerence
‘,’
Pre-operation
I year post-operation
All
6.85 (SD 2.30)
6.26 (SD 2.45)
NS
Men Women
8.11 (SD 2.30) 6.16 (SD 2.09)
8.12 (SD 2.45) 5.23 (SD 1.93)
NS
Difference between men and women
P
P
nerve conduction studies were equivocal for median nerve compression at the wrist. His symptoms have worsened since operation and he has also developed increasing neck pain, with X-ray evidence of degenerative changes at the U-6 level of his cervical spine. Hand grip strength Men had a significantly higher initial grip strength than females (Table 1). Figure 1 shows the grip strength is seen to decrease after operation, but gradually recovers to its pre-operative value by about 6 months. At 1 year, for both sexes, the mean grip strength is not significantly altered compared to the initial value but the significant difference between the sexes is maintained.
Key pinch strength Again, men had a significantly higher pre-operative mean strength of pinch grip than women (Table 2). In both sexes the key pinch strength decreases after operation, but recovers gradually (Fig 2). The values for male patients returned to the pre-operative level at 1 year, but were still reduced in women. This reduction was marginally significant. The difference between the sexes continued to be highly significant.
Pulp-to-pulp pinch strength Men had a significantly higher women (Table 3). After an initial
initial strength than decrease immediately
152
THE JOURNAL
Table 3-Pulp-to-pulp
OF HAND
SURGERY
VOL. 18B No. 5 OCTOBER
1993
pinch strength after carpal tunnel decompression (kg/F) Difference Pre-operation
I year post-operation
All
4.42 (SD 1.98)
4.71 (SD 2.09)
NS
Men Women
5.36 (SD 2.40) 3.9 (SD 1.47)
5.63 (SD 2.34) 4.21 (SD 1.74)
NS NS
Difference between men and women
P
P
_
after operation, the strengths for both male and female patients returned to their normal values by 6 months, and were increased at 1 year (Fig 3). This increase was not statistically significant, although the significant difference between the sexes was maintained.
not a feature of the available normative data (Mathiowetz et al 1985; 1986). From our study it appears that return of pre-operative strength can be expected 1 year after operation, but we found a marginally significant reduction in key pinch strength in the female group.
6
Acknowledgements The authors wish to thank Mrs Caroline Meikle of the Department of Occuoational Theraov for her helo and co-ooeration. and Mrs Janet Freeman. Director of the Department of Medical Aidit, fo; her help with statistical analysis.
References
24 II
2
6
12
26
DAS, S. K. and BROWN, H. G. (1976). In search of complications of carpal tunnel decompression. The Hand, 8: 3: 243-249. EVERSMANN, W. Entrapment and Compression Neuropathies. In: Green, D. P. (Ed.): Operative Hand Surgery, 2nd Edn. New York, Churchill Livingstone, 1988: 1437-1438. GARTSMAN, G. M., KOVACH, J. C., CROUCH, C. C., NOBLE, P. C. and BENNETT, J. B. (1986). Carpal arch alterations after carpal tunnel release. Journal of Hand Surgery, 11A: 3: 372-374. MATHIOWETZ, V., KASHMAN, N., VOLLAND, G., WEBER, K., DOWE, M. and ROGERS, S. (1985). Grip and pinch strength: Normative data for adults. Archives of Physical Medicine and Rehabilitation, 66:
52
Weeks, post-oaeration
Fig 3
Mean key decompression.
grip
strength
following
carpal
tunnel
DISCUSSION
The operation of carpal tunnel decompression is commonly performed in a wide variety of age groups in both sexes. Grip strengths may be affected in several ways after carpal tunnel decompression. The discomfort of the surgical scar will reduce the strength of the hand by inhibition, and disuse for several weeks may lead to muscle weakness. There are also the theoretical changes to the carpal anatomy after division of the flexor retinaculum. Conversely, assuming that operation is successful, an improved innervation of the thenar muscles and sensation in the hand might be expected to lead to an increase in pinch and grip strength, with gradual improvement until full recovery is achieved. Gartsmann et al (1986) showed widening of the carpal arch after operation in association with a reduction in grip strength. This study was retrospective, using the other hand as a control, and compensating for presumed relative weakness in the non-dominant hand, which was
69-74. MATHIOWETZ, V., WIEMER, D. M. and FEDERMAN, S. M. (1986). Grip and pinch strength: Norms for 6.to 19.year olds. American Journal of Occupational Therapy, 40: 705-711.
Accepted: I June 1993 W. J. Leach FRCS Ed, Senior Registrar. Hospital,
0
Glasgow
1993 The British
GSI 4TF, Society
Department
UK. for Surgery
of the Hand
of Orthopaedics,
Southern
General