- Email: [email protected]
Is complete release of all volar carpal canal structures necessary for complete decompression in endoscopic carpal tunnel release?
ARTICLE IN PRESS IS COMPLETE RELEASE OF ALL VOLAR CARPAL CANAL STRUCTURES NECESSARY FOR COMPLETE DECOMPRESSION IN ENDOSCOPIC CARPAL TUNNEL RELEASE? A. YOSHIDA, I. OKUTSU and I. HAMANAKA From the Okutsu Minimally Invasive Orthopaedic Clinic, Minamiazabu, Minato-ku, Tokyo, Japan
This study investigated the need to completely divide the flexor retinaculum to achieve full decompression of the median nerve in the carpal canal, using carpal canal pressure measurements at the mid-point and/or the proximal one-third of the flexor retinaculum to analyse the degree of decompression after release of successive lengths of the flexor retinaculum from the distal holdfast fibres to its proximal margin. Pressure measurements were taken at each operative step in the resting hand position and during active power gripping. The pressure measurements indicated that decompression of the carpal canal was achieved both at rest and on active gripping after complete division of the flexor retinaculum. However, pressure measurements indicated that complete decompression had not been achieved during active power gripping with the proximal one-third of the flexor retinaculum intact. These results demonstrate the need for complete release of the full length of the flexor retinaculum, including the distal holdfast fibres. Journal of Hand Surgery (European Volume, 2007) 32E: 5: 537–542 Keywords: carpal tunnel syndrome, minimally invasive surgery, carpal canal pressure, distal holdfast fibres of the flexor retinaculum
Surgical treatment of carpal tunnel syndrome (CTS) requires release of the volar structures of the carpal canal to decompress the median nerve. The detail of these volar structures is variably described. Cobb et al. (1993) described two parts, viz. a main transverse carpal ligament, or flexor retinaculum, and a distal portion of the flexor retinaculum, which they considered to be connected to each other and not distinct anatomical structures. Okutsu and co-workers described the volar structures of the carpal canal as consisting of the flexor retinaculum and the ‘distal holdfast fibres of the flexor retinaculum’, which are located between the thenar and hypothenar fascia and anatomically distinct, being isolated from the flexor retinaculum by adipose tissue (Okutsu et al., 1996a, b; Tanabe and Okutsu, 1997). The distal holdfast fibres of the flexor retinaculum are located at the distal end of the carpal canal, between the flexor retinaculum and the palmar aponeurosis, on a different anatomical plane from the flexor retinaculum (Tanabe and Okutsu, 1997). In two previous and separate studies, we released the full length of the flexor retinaculum, the distal holdfast fibres of the flexor retinaculum and the forearm fascia, respectively, and took carpal canal pressure measurements pre-operatively and following each surgical step in 257 hands (Okutsu et al., 1996a) and 56 hands (Okutsu et al., 1996b). From those experiences, we concluded that release of the distal holdfast fibres, in addition to the flexor retinaculum, is necessary for complete decompression of the carpal canal in endoscopic carpal tunnel release.
During the last two decades, Jakab, Ganos, and Cook (1991) and Kapandji (1990) have attempted to create a ‘‘plasty’’ of the flexor retinaculum following open surgical procedures to prevent complications such as decrease in grip strength, wrist pain, pillar pain and subluxation of the flexor tendons from the carpal canal. If allowing any part of the volar structures to remain at endoscopic surgery would prevent these complications, the minimum release that would achieve complete decompression of the median nerve needs to be determined. The purpose of this study was to determine how much of the volar structures of the carpal canal need be released, and how much left intact, during endoscopic surgery for CTS to achieve complete decompression.
PATIENTS AND METHODS All patients in this study were informed as to the nature of the operation and gave their full, informed consent. All operations were performed at the Okutsu Minimally Invasive Orthopaedic Clinic. This was done in accordance with the Ethical Guidelines for Clinical Studies, July 30, 2003 (amended December 28, 2004), Japanese Ministry of Health, Labour and Welfare. Group 1: Between March and November 2004, we performed endoscopic carpal canal release surgery using the Universal Subcutaneous Endoscope (USE) system (Okutsu et al., 1987, 1989b), and measured the carpal canal pressure at the mid-point of the flexor retinaculum in 60 hands in 47 patients, including 32 right hands and 537
ARTICLE IN PRESS 538
THE JOURNAL OF HAND SURGERY VOL. 32E No. 5 OCTOBER
2007
28 left hands in 36 women and 11 men for idiopathic CTS. The mean age (SD) of the patients was 56.2 (11.1) (range 22–81) years. Carpal pressure was measured in the resting hand position and during active power gripping, which involved the patient clenching the fist at full power without grasping an object. Group 2: Between May 2005 and January 2006, the same procedures were performed on 28 hands in 24 patients, including 16 right hands and 12 left hands in 17 women and seven men for idiopathic CTS. In these patients, pressure measurements were taken under the proximal one-third of the flexor retinaculum rather than at the mid-point. The mean age (SD) was 59.6 (11.7) (range 31–79) years. We measured carpal canal pressure for both groups using the continuous infusion technique (Gelberman et al., 1981; Hashizume et al., 1997; Okutsu et al., 1989a). Measurements were taken pre-operatively (first measurement), after release of the distal two-thirds of the flexor retinaculum (second measurement), after release of the distal holdfast fibres of the flexor retinaculum (third measurement) and after release of the remaining proximal one-third of the flexor retinaculum, i.e. after complete release of the volar structures (fourth measurement). The operative procedure and carpal canal pressure measurements were performed under local anaesthesia (10 ml of 1% Lidocaine containing Epinephrine) and without a pneumatic tourniquet. The operative (Okutsu et al., 1987, 1989b) and measurement procedures have been described elsewhere (Okutsu et al., 1989a). The USE system was inserted into the carpal canal from a 1 cm forearm skin incision 1.5 cm proximal to the distal wrist crease. Under endoscopic vision, the entire length of the flexor retinaculum was measured against marked sheath lines. Pre-operative carpal canal pressure measurements (first measurement) were performed using a 14 gauge Angiocath (Becton Deckinson Vascular Access, Sandy, Utah, USA) in the resting position and during active power gripping, 5 minutes after injection of local anaesthetic into the carpal canal and following stabilisation of the canal pressure. In Group 1 (60 hands), the tip of the Angiocath was positioned at the midpoint of the length of the carpal canal. For Group 2 (28 hands), the tip of the Angiocath was positioned deep to the proximal one-third of the flexor retinaculum. Carpal canal pressure was then measured in both groups for 30 seconds and the maximum pressure was recorded (first measurement). The Angiocath tip position was determined by the Angiocath length, flexor retinaculum length, and the length from the skin incision, as measured against marked sheath lines. The catheter was removed following each measurement step as described in our previous study (Okutsu et al., 1989a). Then the distal two-thirds of the flexor retinaculum was measured and released from the distal end of the flexor retinaculum with a hook knife, entirely under
direct vision through the endoscope. The USE system was removed and the second carpal canal pressure measurement was taken in both the resting position and during active power gripping. The second pressure measurements for both groups were performed in the same manner as previously described. Next, the USE system was re-inserted between the distal holdfast fibres of the flexor retinaculum and the superficial palmar arterial arch. The distal holdfast fibres of the flexor retinaculum were released with a hook knife, again entirely under direct vision through the endoscope. A third carpal canal pressure measurement was performed in the same manner as previously described, for both groups. Finally, the proximal one-third of the flexor retinaculum was released and the fourth carpal canal pressure measurement was performed, again as previously described. The flexor retinaculum splits by o2 mm on distal two-thirds release, 42 mm on release of the distal holdfast fibres of the flexor retinaculum, and 48 mm on complete release of the flexor retinaculum. We analysed the data statistically at each step using Wilcoxon’s matched-pairs signed-ranks test. Significant statistical differences were then compared to determine the overall efficacy of each step of the procedure. In respect of the Bonferrroni correction for multiple comparisons, an adjusted significant level of 0.01 was used: po0.01).
RESULTS In Group 1 (60 hands), in whom the carpal canal pressure was measured at the mid-point of the flexor retinaculum, the mean flexor retinaculum length (SD) was 25.7 (4.8) (range 20–40) mm. In the resting position, the pre-operative mean carpal canal pressure (SD) in Group 1 was 60.1 (30.1) (range 4–172) mmHg. The second measurement (SD) was 2.2 (3.5) (range 0–15) mmHg. The third measurement (SD) was 1.1 (2.0) (range 0–7) mmHg. The fourth measurement (SD) was 1.0 (1.8) (range 0–7) mmHg (Fig 1). During active power gripping, the pre-operative mean carpal canal pressure (SD) in Group 1 was 168.4 (56.6) (range 42–291) mmHg. The second measurement (SD) was 37.4 (27.8) (range 4–144) mmHg. The third measurement (SD) was 14.8 (17.6) (range 0–107) mmHg. The fourth measurement (SD) was 10.2 (9.9) (range 0–43) mmHg (Fig 2). There were significant statistical differences between both the pre-operative pressure (first measurement) and the pressure after release of the distal two-thirds of the flexor retinaculum (second measurement) pressure both at rest and during active power gripping, and between the release of the distal two-thirds of the flexor retinaculum (second measurement) and after release of the distal holdfast fibres of the flexor retinaculum (third
ARTICLE IN PRESS 539
COMPLETE RELEASE OF ALL VOLAR CARPAL CANAL STRUCTURES
100 Carpal canal pressure (mmHg)
90 80 70 60 50 40 30 20 10 0 release distal 2/3 FR
preop.
release DHFFR
release remaining proximal 1/3 FR
Surgical process * : p < 0.01 N.S.:not significant FR=flexor retinaculum; DHFFR=distal holdfast fibers of the flexor retinaculum
Fig 1 Relationship between mid-point carpal canal pressure measurements (mean and standard deviation) and step-by-step release of the volar structures of the carpal canal at rest.
Carpal canal pressure (mmHg)
250 200 150 100 50 0 release distal 2/3 FR
preop.
*
release DHFFR
release remaining proximal 1/3 FR
Surgical process * : p < 0.01
FR=flexor retinaculum; DHFFR=distal holdfast fibers of the flexor retinaculum
Fig 2 Relationship between mid-point carpal canal pressure measurements (mean and standard deviation) and step-by-step release of the volar structures of the carpal canal during active power gripping.
measurement) pressure at rest and during active power gripping. There was no significant statistical difference between the pressure after release of the distal holdfast fibres of the flexor retinaculum measurement (third measurement) and the pressure after release of the remaining proximal one-third of the flexor retinaculum measurement (fourth measurement) (Fig 1) in the resting position. However, there was a significant statistical
difference between the pressure after release of the distal holdfast fibres of the flexor retinaculum (third measurement) and after release of the remaining proximal onethird of the flexor retinaculum measurement (fourth measurement) (Fig 2) during active power gripping. In Group 2 (28 hands), in whom pressure measurements were taken under the proximal one-third of the flexor retinaculum, the mean flexor retinaculum length (SD) was 27.1 (3.0) (range 25–33) mm.
ARTICLE IN PRESS 540
THE JOURNAL OF HAND SURGERY VOL. 32E No. 5 OCTOBER
2007
In the resting position, the pre-operative mean carpal canal pressure (SD) was 55.2 (23.0) (range 17–108) mmHg. The second measurement (SD) was 5.9 (8.9) (range 0–32) mmHg. The third measurement (SD) was 4.1 (4.3) (range 0–13) mmHg. The fourth measurement (SD) was 2.1 (2.6) (range 0–9) mmHg (Fig 3). During active power gripping, the pre-operative mean carpal canal pressure (SD) was 157.1 (52.9) (range 25–300) mmHg. The second measurement (SD) was 54.2 (39.3) (range 4–164) mmHg. The third measurement (SD) was 34.5 (26.1) (range 1–100) mmHg. The fourth measurement (SD) was 6.9 (10.1) (range 0–50) mmHg (Fig 4). For Group 2 there were significant statistical differences between the pre-operative pressure (first measurement) and the pressures after release of the distal two-thirds of the flexor retinaculum (second measurement) pressure, both at rest and during active power gripping. There were no significant statistical differences in pressures at rest between release of the distal two-thirds of the flexor retinaculum (second measurement) and release of the distal holdfast fibres of the flexor retinaculum (third measurement), and between release of the distal holdfast fibres of the flexor retinaculum (third measurement) and release of the remaining proximal one-third of the flexor retinaculum (fourth measurement) (Fig 3). There were significant statistical differences during active power gripping between release of the distal twothirds of the flexor retinaculum (second measurement) and release of the distal holdfast fibres of the flexor retinaculum (third measurement), and between release
of the distal holdfast fibres of the flexor retinaculum (third measurement) and release of the remaining proximal one-third of the flexor retinaculum (fourth measurement) (Fig 4). Carpal canal pressure measurement results at rest and during active power gripping were achieved within optimal range following release of the distal holdfast fibres of the flexor retinaculum (third measurement) in Group 1. However, in Group 2, it was only achieved following release of the remaining one-third of the flexor retinaculum (fourth measurement) during active power gripping.
DISCUSSION The purpose of CTS treatment is to achieve complete decompression of the median nerve as it passes through the carpal canal. Using the continuous infusion technique, we have shown a correlation to exist between carpal canal pressure and median nerve pressure both at rest and during active power gripping (Okutsu et al., 2003, 2004). Various authors have identified residual symptoms or recurrent CTS as a result of incomplete release of the distal volar structures (Das and Brown, 1976; Hulsizer et al., 1998; Kern et al., 1993; Louis et al., 1985; Steyers, 2002). Robbins (1963) identified the distal part of the carpal canal as the shallowest part of the canal. Based on previous clinical studies, we have concluded that the optimal postoperative carpal canal pressure is less than 10 mmHg at rest and less than 25 mmHg
100
Carpal canal pressure (mmHg)
90 80 70 60 50 40 30 20 10 0 preop.
release distal 2/3 FR
release DHFFR
release remaining proximal 1/3 FR * : p < 0.01
Surgical process
N.S.:not significant FR=flexor retinaculum; DHFFR=distal holdfast fibers of the flexor retinaculum
Fig 3 Relationship between the proximal one-third carpal canal pressure measurements (mean and standard deviation) and step-by-step release of the volar structures of the carpal canal at rest.
ARTICLE IN PRESS 541
COMPLETE RELEASE OF ALL VOLAR CARPAL CANAL STRUCTURES
Carpal canal pressure (mmHg)
250 200 150 100 50 0 preop.
release distal 2/3 FR
release DHFFR
release remaining proximal 1/3 FR
Surgical process * : p < 0.01 FR=flexor retinaculum; DHFFR=distal holdfast fibers of the flexor retinaculum
Fig 4 Relationship between the proximal one-third carpal canal pressure measurements (mean and standard deviation) and step-by-step release of the volar structures of the carpal canal during active power gripping.
during active power gripping. We defined these pressure levels previously as ‘‘complete decompression’’ (Okutsu et al., 1996a, b). In this study, the most significant decompression occurred after the first surgical manoeuvre in the resting position and during active power gripping. Measurement at the proximal one-third during active power gripping, after release of the distal twothirds of the flexor retinaculum and the distal holdfast fibres, demonstrated a mean carpal canal pressure of 34.5 mmHg and standard deviation of 26.1 mmHg. These results indicate that most patients have not achieved the optimal pressure, so we recommend release of the remaining proximal one-third of the flexor retinaculum to ensure complete decompression in all cases. Recovery from clinical symptoms following ‘complete decompression’ of the carpal canal is faster than recovery after incomplete decompression (Okutsu, 1998). Hashizume et al. (1997) reported that carpal canal pressure is different at different locations within the carpal canal. We, therefore, performed pressure measurements at both the mid-point and in the proximal one-third of the carpal canal in this study in order to obtain more precise data. The significant statistical differences in pressure in the carpal canal between release of the distal holdfast fibres of the flexor retinaculum (third measurement) and release of the remaining proximal one-third of the flexor retinaculum (fourth measurement) during active power gripping shows that preserving the proximal part of the flexor retinaculum during endoscopic carpal canal release may lead to unsatisfactory results. This may be due to dynamic factors, such as variable wrist positions
and/or migration of the flexor muscle belly distally or lumbrical muscles proximally into the carpal canal. Based on our carpal canal pressure measurement results, we conclude that complete release of the whole of the flexor retinaculum, including the distal holdfast fibres, is essential to achieve complete decompression in endoscopic carpal canal release surgery for CTS.
Acknowledgements This clinical research was supported by a grant from the Japanese Foundation for Research and Promotion of Endoscopy.
References Cobb TK, Dally BK, Posteraro RH, Lewis RC (1993). Anatomy of the flexor retinaculum. Journal of Hand Surgery, 18A: 91–99. Das SK, Brown HG (1976). In search of complications in carpal tunnel decompression. Hand, 8: 243–249. Gelberman RH, Hergenroeder PT, Hargens AR, Lundborg GN, Akeson WH (1981). The carpal tunnel syndrome: a study of carpal canal pressures. Journal of Bone and Joint Surgery, 63A: 380–383. Hashizume H, Nanba Y, Shigeyama Y, Hirooka T, Yokoi T, Inoue H (1997). Endoscopic carpal tunnel pressure measurement: a reliable technique for complete release. Acta Medica Okayama, 51: 105–110. Hulsizer DL, Staebler MP, Weiss AC, Akelman E (1998). The results of revision carpal tunnel release following previous open versus endoscopic surgery. Journal of Hand Surgery, 23A: 865–869. Jakab E, Ganos D, Cook FW (1991). Transverse carpal ligament reconstruction in surgery for carpal tunnel syndrome: a new technique. Journal of Hand Surgery, 16A: 202–206. Kapandji AI (1990). Plastic surgical enlargement of the anterior annular carpal ligament in the treatment of carpal tunnel syndrome. Annals of Hand and Upper Limb Surgery, 9: 305–314 (in French).
ARTICLE IN PRESS 542
THE JOURNAL OF HAND SURGERY VOL. 32E No. 5 OCTOBER
2007
Kern BC, Brock M, Rudolph KH, Logemann H (1993). The recurrent carpal tunnel syndrome. Zentralblatt fu¨r Neurochirurgie, 54: 80–83. Louis DS, Greene TL, Noellert RC (1985). Complications of carpal tunnel surgery. Journal of Neurosurgery, 62: 352–356. Okutsu, I., 1998. The world’s first endoscopic management of carpal tunnel syndrome: eleven years clinical experience. In: Roth, J.H., Richards, R.S., (Eds), Seventh Congress of the International Federation of Societies for Surgery of the Hand. Bologna, Monduzzi, 123–129. Okutsu I, Ninomiya S, Natsuyama M et al. (1987). Subcutaneous operation and examination under Universal Endoscope. Journal of the Japanese Orthopaedic Association, 61: 491–498 (in Japanese). Okutsu I, Ninomiya S, Hamanaka I, Kuroshima N, Inanammi H (1989a). Measurement of pressure in the carpal canal before and after endoscopic management of carpal tunnel syndrome. Journal of Bone and Joint Surgery, 71A: 679–683. Okutsu I, Ninomiya S, Takatori Y, Ugawa Y (1989b). Endoscopic management of carpal tunnel syndrome. Arthroscopy, 5: 11–18. Okutsu I, Hamanaka I, Tanabe T, Takatori Y, Ninomiya S (1996a). Complete endoscopic carpal tunnel release in longterm haemodialysis patients. Journal of Hand Surgery, 21B: 668–671. Okutsu I, Hamanaka I, Tanabe T, Takatori Y, Ninomiya S (1996b). Complete endoscopic carpal canal decompression. American Journal of Orthopedics, 25: 365–368.
Okutsu I, Hamanaka I, Kitajima I, Yoshida A, Ninomiya S (2003). Median nerve pressure vs carpal canal pressure in carpal tunnel syndrome patients. Journal of Japanese Society for Surgery of the Hand, 20: 65–68 (in Japanese). Okutsu I, Ninomiya S, Yoshida A, Hamanaka I, Kitajima I (2004). Measurement of carpal canal and median nerve pressure in patients with carpal tunnel syndrome. Techniques in Hand and Upper Extremity Surgery, 8: 124–128. Robbins H (1963). Anatomical study of the median nerve in the carpal tunnel and etiologies of the carpal-tunnel syndrome. Journal of Bone and Joint Surgery, 45A: 953–966. Steyers CM (2002). Recurrent carpal tunnel syndrome. Hand Clinics, 18: 339–345. Tanabe T, Okutsu I (1997). An anatomical study of the palmar ligamentous structures of the carpal canal. Journal of Hand Surgery, 22B: 754–757. Received: 31 March 2006 Accepted after revision: 2 April 2007 Dr Aya Yoshida, MD, Okutsu Minimally Invasive Orthopaedic Clinic, 3rd Floor, Dai-ni Sano Building, 5-10–24, Minamiazabu, Minato-ku, Tokyo 106-0047, Japan. Tel.: +81 3 5420 0920; fax: +81 3 6408 0923. E-mail: [email protected]
r 2007 The British Society for Surgery of the Hand. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhse.2007.04.002 available online at http://www.sciencedirect.com
This study investigated the need to completely divide the flexor retinaculum to achieve full decompression of the median nerve in the carpal canal, using carpal canal pressure measurements at the mid-point and/or the proximal one-third of the flexor retinaculum to analyse the degree of decompression after release of successive lengths of the flexor retinaculum from the distal holdfast fibres to its proximal margin. Pressure measurements were taken at each operative step in the resting hand position and during active power gripping. The pressure measurements indicated that decompression of the carpal canal was achieved both at rest and on active gripping after complete division of the flexor retinaculum. However, pressure measurements indicated that complete decompression had not been achieved during active power gripping with the proximal one-third of the flexor retinaculum intact. These results demonstrate the need for complete release of the full length of the flexor retinaculum, including the distal holdfast fibres. Journal of Hand Surgery (European Volume, 2007) 32E: 5: 537–542 Keywords: carpal tunnel syndrome, minimally invasive surgery, carpal canal pressure, distal holdfast fibres of the flexor retinaculum
Surgical treatment of carpal tunnel syndrome (CTS) requires release of the volar structures of the carpal canal to decompress the median nerve. The detail of these volar structures is variably described. Cobb et al. (1993) described two parts, viz. a main transverse carpal ligament, or flexor retinaculum, and a distal portion of the flexor retinaculum, which they considered to be connected to each other and not distinct anatomical structures. Okutsu and co-workers described the volar structures of the carpal canal as consisting of the flexor retinaculum and the ‘distal holdfast fibres of the flexor retinaculum’, which are located between the thenar and hypothenar fascia and anatomically distinct, being isolated from the flexor retinaculum by adipose tissue (Okutsu et al., 1996a, b; Tanabe and Okutsu, 1997). The distal holdfast fibres of the flexor retinaculum are located at the distal end of the carpal canal, between the flexor retinaculum and the palmar aponeurosis, on a different anatomical plane from the flexor retinaculum (Tanabe and Okutsu, 1997). In two previous and separate studies, we released the full length of the flexor retinaculum, the distal holdfast fibres of the flexor retinaculum and the forearm fascia, respectively, and took carpal canal pressure measurements pre-operatively and following each surgical step in 257 hands (Okutsu et al., 1996a) and 56 hands (Okutsu et al., 1996b). From those experiences, we concluded that release of the distal holdfast fibres, in addition to the flexor retinaculum, is necessary for complete decompression of the carpal canal in endoscopic carpal tunnel release.
During the last two decades, Jakab, Ganos, and Cook (1991) and Kapandji (1990) have attempted to create a ‘‘plasty’’ of the flexor retinaculum following open surgical procedures to prevent complications such as decrease in grip strength, wrist pain, pillar pain and subluxation of the flexor tendons from the carpal canal. If allowing any part of the volar structures to remain at endoscopic surgery would prevent these complications, the minimum release that would achieve complete decompression of the median nerve needs to be determined. The purpose of this study was to determine how much of the volar structures of the carpal canal need be released, and how much left intact, during endoscopic surgery for CTS to achieve complete decompression.
PATIENTS AND METHODS All patients in this study were informed as to the nature of the operation and gave their full, informed consent. All operations were performed at the Okutsu Minimally Invasive Orthopaedic Clinic. This was done in accordance with the Ethical Guidelines for Clinical Studies, July 30, 2003 (amended December 28, 2004), Japanese Ministry of Health, Labour and Welfare. Group 1: Between March and November 2004, we performed endoscopic carpal canal release surgery using the Universal Subcutaneous Endoscope (USE) system (Okutsu et al., 1987, 1989b), and measured the carpal canal pressure at the mid-point of the flexor retinaculum in 60 hands in 47 patients, including 32 right hands and 537
ARTICLE IN PRESS 538
THE JOURNAL OF HAND SURGERY VOL. 32E No. 5 OCTOBER
2007
28 left hands in 36 women and 11 men for idiopathic CTS. The mean age (SD) of the patients was 56.2 (11.1) (range 22–81) years. Carpal pressure was measured in the resting hand position and during active power gripping, which involved the patient clenching the fist at full power without grasping an object. Group 2: Between May 2005 and January 2006, the same procedures were performed on 28 hands in 24 patients, including 16 right hands and 12 left hands in 17 women and seven men for idiopathic CTS. In these patients, pressure measurements were taken under the proximal one-third of the flexor retinaculum rather than at the mid-point. The mean age (SD) was 59.6 (11.7) (range 31–79) years. We measured carpal canal pressure for both groups using the continuous infusion technique (Gelberman et al., 1981; Hashizume et al., 1997; Okutsu et al., 1989a). Measurements were taken pre-operatively (first measurement), after release of the distal two-thirds of the flexor retinaculum (second measurement), after release of the distal holdfast fibres of the flexor retinaculum (third measurement) and after release of the remaining proximal one-third of the flexor retinaculum, i.e. after complete release of the volar structures (fourth measurement). The operative procedure and carpal canal pressure measurements were performed under local anaesthesia (10 ml of 1% Lidocaine containing Epinephrine) and without a pneumatic tourniquet. The operative (Okutsu et al., 1987, 1989b) and measurement procedures have been described elsewhere (Okutsu et al., 1989a). The USE system was inserted into the carpal canal from a 1 cm forearm skin incision 1.5 cm proximal to the distal wrist crease. Under endoscopic vision, the entire length of the flexor retinaculum was measured against marked sheath lines. Pre-operative carpal canal pressure measurements (first measurement) were performed using a 14 gauge Angiocath (Becton Deckinson Vascular Access, Sandy, Utah, USA) in the resting position and during active power gripping, 5 minutes after injection of local anaesthetic into the carpal canal and following stabilisation of the canal pressure. In Group 1 (60 hands), the tip of the Angiocath was positioned at the midpoint of the length of the carpal canal. For Group 2 (28 hands), the tip of the Angiocath was positioned deep to the proximal one-third of the flexor retinaculum. Carpal canal pressure was then measured in both groups for 30 seconds and the maximum pressure was recorded (first measurement). The Angiocath tip position was determined by the Angiocath length, flexor retinaculum length, and the length from the skin incision, as measured against marked sheath lines. The catheter was removed following each measurement step as described in our previous study (Okutsu et al., 1989a). Then the distal two-thirds of the flexor retinaculum was measured and released from the distal end of the flexor retinaculum with a hook knife, entirely under
direct vision through the endoscope. The USE system was removed and the second carpal canal pressure measurement was taken in both the resting position and during active power gripping. The second pressure measurements for both groups were performed in the same manner as previously described. Next, the USE system was re-inserted between the distal holdfast fibres of the flexor retinaculum and the superficial palmar arterial arch. The distal holdfast fibres of the flexor retinaculum were released with a hook knife, again entirely under direct vision through the endoscope. A third carpal canal pressure measurement was performed in the same manner as previously described, for both groups. Finally, the proximal one-third of the flexor retinaculum was released and the fourth carpal canal pressure measurement was performed, again as previously described. The flexor retinaculum splits by o2 mm on distal two-thirds release, 42 mm on release of the distal holdfast fibres of the flexor retinaculum, and 48 mm on complete release of the flexor retinaculum. We analysed the data statistically at each step using Wilcoxon’s matched-pairs signed-ranks test. Significant statistical differences were then compared to determine the overall efficacy of each step of the procedure. In respect of the Bonferrroni correction for multiple comparisons, an adjusted significant level of 0.01 was used: po0.01).
RESULTS In Group 1 (60 hands), in whom the carpal canal pressure was measured at the mid-point of the flexor retinaculum, the mean flexor retinaculum length (SD) was 25.7 (4.8) (range 20–40) mm. In the resting position, the pre-operative mean carpal canal pressure (SD) in Group 1 was 60.1 (30.1) (range 4–172) mmHg. The second measurement (SD) was 2.2 (3.5) (range 0–15) mmHg. The third measurement (SD) was 1.1 (2.0) (range 0–7) mmHg. The fourth measurement (SD) was 1.0 (1.8) (range 0–7) mmHg (Fig 1). During active power gripping, the pre-operative mean carpal canal pressure (SD) in Group 1 was 168.4 (56.6) (range 42–291) mmHg. The second measurement (SD) was 37.4 (27.8) (range 4–144) mmHg. The third measurement (SD) was 14.8 (17.6) (range 0–107) mmHg. The fourth measurement (SD) was 10.2 (9.9) (range 0–43) mmHg (Fig 2). There were significant statistical differences between both the pre-operative pressure (first measurement) and the pressure after release of the distal two-thirds of the flexor retinaculum (second measurement) pressure both at rest and during active power gripping, and between the release of the distal two-thirds of the flexor retinaculum (second measurement) and after release of the distal holdfast fibres of the flexor retinaculum (third
ARTICLE IN PRESS 539
COMPLETE RELEASE OF ALL VOLAR CARPAL CANAL STRUCTURES
100 Carpal canal pressure (mmHg)
90 80 70 60 50 40 30 20 10 0 release distal 2/3 FR
preop.
release DHFFR
release remaining proximal 1/3 FR
Surgical process * : p < 0.01 N.S.:not significant FR=flexor retinaculum; DHFFR=distal holdfast fibers of the flexor retinaculum
Fig 1 Relationship between mid-point carpal canal pressure measurements (mean and standard deviation) and step-by-step release of the volar structures of the carpal canal at rest.
Carpal canal pressure (mmHg)
250 200 150 100 50 0 release distal 2/3 FR
preop.
*
release DHFFR
release remaining proximal 1/3 FR
Surgical process * : p < 0.01
FR=flexor retinaculum; DHFFR=distal holdfast fibers of the flexor retinaculum
Fig 2 Relationship between mid-point carpal canal pressure measurements (mean and standard deviation) and step-by-step release of the volar structures of the carpal canal during active power gripping.
measurement) pressure at rest and during active power gripping. There was no significant statistical difference between the pressure after release of the distal holdfast fibres of the flexor retinaculum measurement (third measurement) and the pressure after release of the remaining proximal one-third of the flexor retinaculum measurement (fourth measurement) (Fig 1) in the resting position. However, there was a significant statistical
difference between the pressure after release of the distal holdfast fibres of the flexor retinaculum (third measurement) and after release of the remaining proximal onethird of the flexor retinaculum measurement (fourth measurement) (Fig 2) during active power gripping. In Group 2 (28 hands), in whom pressure measurements were taken under the proximal one-third of the flexor retinaculum, the mean flexor retinaculum length (SD) was 27.1 (3.0) (range 25–33) mm.
ARTICLE IN PRESS 540
THE JOURNAL OF HAND SURGERY VOL. 32E No. 5 OCTOBER
2007
In the resting position, the pre-operative mean carpal canal pressure (SD) was 55.2 (23.0) (range 17–108) mmHg. The second measurement (SD) was 5.9 (8.9) (range 0–32) mmHg. The third measurement (SD) was 4.1 (4.3) (range 0–13) mmHg. The fourth measurement (SD) was 2.1 (2.6) (range 0–9) mmHg (Fig 3). During active power gripping, the pre-operative mean carpal canal pressure (SD) was 157.1 (52.9) (range 25–300) mmHg. The second measurement (SD) was 54.2 (39.3) (range 4–164) mmHg. The third measurement (SD) was 34.5 (26.1) (range 1–100) mmHg. The fourth measurement (SD) was 6.9 (10.1) (range 0–50) mmHg (Fig 4). For Group 2 there were significant statistical differences between the pre-operative pressure (first measurement) and the pressures after release of the distal two-thirds of the flexor retinaculum (second measurement) pressure, both at rest and during active power gripping. There were no significant statistical differences in pressures at rest between release of the distal two-thirds of the flexor retinaculum (second measurement) and release of the distal holdfast fibres of the flexor retinaculum (third measurement), and between release of the distal holdfast fibres of the flexor retinaculum (third measurement) and release of the remaining proximal one-third of the flexor retinaculum (fourth measurement) (Fig 3). There were significant statistical differences during active power gripping between release of the distal twothirds of the flexor retinaculum (second measurement) and release of the distal holdfast fibres of the flexor retinaculum (third measurement), and between release
of the distal holdfast fibres of the flexor retinaculum (third measurement) and release of the remaining proximal one-third of the flexor retinaculum (fourth measurement) (Fig 4). Carpal canal pressure measurement results at rest and during active power gripping were achieved within optimal range following release of the distal holdfast fibres of the flexor retinaculum (third measurement) in Group 1. However, in Group 2, it was only achieved following release of the remaining one-third of the flexor retinaculum (fourth measurement) during active power gripping.
DISCUSSION The purpose of CTS treatment is to achieve complete decompression of the median nerve as it passes through the carpal canal. Using the continuous infusion technique, we have shown a correlation to exist between carpal canal pressure and median nerve pressure both at rest and during active power gripping (Okutsu et al., 2003, 2004). Various authors have identified residual symptoms or recurrent CTS as a result of incomplete release of the distal volar structures (Das and Brown, 1976; Hulsizer et al., 1998; Kern et al., 1993; Louis et al., 1985; Steyers, 2002). Robbins (1963) identified the distal part of the carpal canal as the shallowest part of the canal. Based on previous clinical studies, we have concluded that the optimal postoperative carpal canal pressure is less than 10 mmHg at rest and less than 25 mmHg
100
Carpal canal pressure (mmHg)
90 80 70 60 50 40 30 20 10 0 preop.
release distal 2/3 FR
release DHFFR
release remaining proximal 1/3 FR * : p < 0.01
Surgical process
N.S.:not significant FR=flexor retinaculum; DHFFR=distal holdfast fibers of the flexor retinaculum
Fig 3 Relationship between the proximal one-third carpal canal pressure measurements (mean and standard deviation) and step-by-step release of the volar structures of the carpal canal at rest.
ARTICLE IN PRESS 541
COMPLETE RELEASE OF ALL VOLAR CARPAL CANAL STRUCTURES
Carpal canal pressure (mmHg)
250 200 150 100 50 0 preop.
release distal 2/3 FR
release DHFFR
release remaining proximal 1/3 FR
Surgical process * : p < 0.01 FR=flexor retinaculum; DHFFR=distal holdfast fibers of the flexor retinaculum
Fig 4 Relationship between the proximal one-third carpal canal pressure measurements (mean and standard deviation) and step-by-step release of the volar structures of the carpal canal during active power gripping.
during active power gripping. We defined these pressure levels previously as ‘‘complete decompression’’ (Okutsu et al., 1996a, b). In this study, the most significant decompression occurred after the first surgical manoeuvre in the resting position and during active power gripping. Measurement at the proximal one-third during active power gripping, after release of the distal twothirds of the flexor retinaculum and the distal holdfast fibres, demonstrated a mean carpal canal pressure of 34.5 mmHg and standard deviation of 26.1 mmHg. These results indicate that most patients have not achieved the optimal pressure, so we recommend release of the remaining proximal one-third of the flexor retinaculum to ensure complete decompression in all cases. Recovery from clinical symptoms following ‘complete decompression’ of the carpal canal is faster than recovery after incomplete decompression (Okutsu, 1998). Hashizume et al. (1997) reported that carpal canal pressure is different at different locations within the carpal canal. We, therefore, performed pressure measurements at both the mid-point and in the proximal one-third of the carpal canal in this study in order to obtain more precise data. The significant statistical differences in pressure in the carpal canal between release of the distal holdfast fibres of the flexor retinaculum (third measurement) and release of the remaining proximal one-third of the flexor retinaculum (fourth measurement) during active power gripping shows that preserving the proximal part of the flexor retinaculum during endoscopic carpal canal release may lead to unsatisfactory results. This may be due to dynamic factors, such as variable wrist positions
and/or migration of the flexor muscle belly distally or lumbrical muscles proximally into the carpal canal. Based on our carpal canal pressure measurement results, we conclude that complete release of the whole of the flexor retinaculum, including the distal holdfast fibres, is essential to achieve complete decompression in endoscopic carpal canal release surgery for CTS.
Acknowledgements This clinical research was supported by a grant from the Japanese Foundation for Research and Promotion of Endoscopy.
References Cobb TK, Dally BK, Posteraro RH, Lewis RC (1993). Anatomy of the flexor retinaculum. Journal of Hand Surgery, 18A: 91–99. Das SK, Brown HG (1976). In search of complications in carpal tunnel decompression. Hand, 8: 243–249. Gelberman RH, Hergenroeder PT, Hargens AR, Lundborg GN, Akeson WH (1981). The carpal tunnel syndrome: a study of carpal canal pressures. Journal of Bone and Joint Surgery, 63A: 380–383. Hashizume H, Nanba Y, Shigeyama Y, Hirooka T, Yokoi T, Inoue H (1997). Endoscopic carpal tunnel pressure measurement: a reliable technique for complete release. Acta Medica Okayama, 51: 105–110. Hulsizer DL, Staebler MP, Weiss AC, Akelman E (1998). The results of revision carpal tunnel release following previous open versus endoscopic surgery. Journal of Hand Surgery, 23A: 865–869. Jakab E, Ganos D, Cook FW (1991). Transverse carpal ligament reconstruction in surgery for carpal tunnel syndrome: a new technique. Journal of Hand Surgery, 16A: 202–206. Kapandji AI (1990). Plastic surgical enlargement of the anterior annular carpal ligament in the treatment of carpal tunnel syndrome. Annals of Hand and Upper Limb Surgery, 9: 305–314 (in French).
ARTICLE IN PRESS 542
THE JOURNAL OF HAND SURGERY VOL. 32E No. 5 OCTOBER
2007
Kern BC, Brock M, Rudolph KH, Logemann H (1993). The recurrent carpal tunnel syndrome. Zentralblatt fu¨r Neurochirurgie, 54: 80–83. Louis DS, Greene TL, Noellert RC (1985). Complications of carpal tunnel surgery. Journal of Neurosurgery, 62: 352–356. Okutsu, I., 1998. The world’s first endoscopic management of carpal tunnel syndrome: eleven years clinical experience. In: Roth, J.H., Richards, R.S., (Eds), Seventh Congress of the International Federation of Societies for Surgery of the Hand. Bologna, Monduzzi, 123–129. Okutsu I, Ninomiya S, Natsuyama M et al. (1987). Subcutaneous operation and examination under Universal Endoscope. Journal of the Japanese Orthopaedic Association, 61: 491–498 (in Japanese). Okutsu I, Ninomiya S, Hamanaka I, Kuroshima N, Inanammi H (1989a). Measurement of pressure in the carpal canal before and after endoscopic management of carpal tunnel syndrome. Journal of Bone and Joint Surgery, 71A: 679–683. Okutsu I, Ninomiya S, Takatori Y, Ugawa Y (1989b). Endoscopic management of carpal tunnel syndrome. Arthroscopy, 5: 11–18. Okutsu I, Hamanaka I, Tanabe T, Takatori Y, Ninomiya S (1996a). Complete endoscopic carpal tunnel release in longterm haemodialysis patients. Journal of Hand Surgery, 21B: 668–671. Okutsu I, Hamanaka I, Tanabe T, Takatori Y, Ninomiya S (1996b). Complete endoscopic carpal canal decompression. American Journal of Orthopedics, 25: 365–368.
Okutsu I, Hamanaka I, Kitajima I, Yoshida A, Ninomiya S (2003). Median nerve pressure vs carpal canal pressure in carpal tunnel syndrome patients. Journal of Japanese Society for Surgery of the Hand, 20: 65–68 (in Japanese). Okutsu I, Ninomiya S, Yoshida A, Hamanaka I, Kitajima I (2004). Measurement of carpal canal and median nerve pressure in patients with carpal tunnel syndrome. Techniques in Hand and Upper Extremity Surgery, 8: 124–128. Robbins H (1963). Anatomical study of the median nerve in the carpal tunnel and etiologies of the carpal-tunnel syndrome. Journal of Bone and Joint Surgery, 45A: 953–966. Steyers CM (2002). Recurrent carpal tunnel syndrome. Hand Clinics, 18: 339–345. Tanabe T, Okutsu I (1997). An anatomical study of the palmar ligamentous structures of the carpal canal. Journal of Hand Surgery, 22B: 754–757. Received: 31 March 2006 Accepted after revision: 2 April 2007 Dr Aya Yoshida, MD, Okutsu Minimally Invasive Orthopaedic Clinic, 3rd Floor, Dai-ni Sano Building, 5-10–24, Minamiazabu, Minato-ku, Tokyo 106-0047, Japan. Tel.: +81 3 5420 0920; fax: +81 3 6408 0923. E-mail: [email protected]
r 2007 The British Society for Surgery of the Hand. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhse.2007.04.002 available online at http://www.sciencedirect.com