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TRANSTHECAL DIGITAL BLOCK AT THE PROXIMAL PHALANX
TRANSTHECAL DIGITAL BLOCK AT THE PROXIMAL PHALANX P. J. TOROK, S. D. FLINN and A. Y. SHIN From the Departments of Orthopedic Surgery and Clinical Investigation, Naval Medical Center San Diego, San Diego, California, USA
This study assessed the efficacy of a modified transthecal digital block. Three-hundred-and-sixty consecutive digits were anaesthetised with this technique for the treatment of fractures, infections and foreign bodies. Complete palmar and dorsal anaesthesia was achieved in 357 of the 360 digits (99%), including 52 of 53 thumbs (98%). The technique was extremely easy to perform and no complications occurred. Journal of Hand Surgery (British and European Volume, 2001) 26B: 1: 69–71 digital crease that required treatment under local anaesthesia were enrolled into a Hand Injury Registry approved by the institutional review board. The anaesthetic technique was used for lacerations, fractures, infections, and foreign bodies. Exclusion criteria included open flexor tendon sheath injuries, infections of the flexor tendon sheath, lesions with an overlying superficial infection at the proposed injection site, known allergy to lidocaine or bupivacaine, haematologic or vasospastic diseases, and a refusal to undergo treatment. All patients provided informed consent prior to their procedure, and then a modified transthecal digital block was administered at the level of the middle of the proximal phalanx. All injections were performed by house staff who were rotating through the Orthopaedic Acute Care Clinic or the Hand Service. House staff were shown the technique by one of the authors, performed one block under direct supervision and then performed subsequent blocks with indirect supervision. A syringe with a 25-gauge (light blue) needle was filled with 2 ml 1% lidocaine (Abbott Laboratories, North Chicago, IL, USA) and 2 ml 0.5% bupivacaine (Abbott Laboratories, North Chicago, IL, USA) at room temperature. Using a sterile technique, 3–4 ml of anaesthetic was injected into the flexor sheath at a point half way between the proximal digital crease and the proximal interphalangeal joint crease (palmar, mid sagittal). Pressure was applied over the A1 pulley while injecting, thereby promoting distal flow of the anaesthetic (Fig 1). As described by Whetzel (1997), the needle was passed through the flexor tendon and down to bone, and was then lifted slightly off the phalanx before the anaesthetic was injected. The thumb was anaesthetised in a similar manner with the needle inserted on its palmar surface, half way between the palmar digital and the interphalangeal creases. A successful anaesthetic block was defined as loss of sensation on both the dorsal and palmar aspects of the digit as far proximally as the level of injection, and the ability to complete the proposed procedure without pain. Failure of the digital block was defined as
INTRODUCTION Chiu (1990) described a technique of digital block that produced complete finger anaesthesia with a single injection into the flexor tendon sheath at the level of the distal palmar crease. When compared to the traditional dorsal digital block, the advantages of his technique are the use of a single injection and the absence of risk of direct trauma to the neurovascular bundles. However, as others found that Chiu’s technique did not always provide satisfactory anaesthesia (Chevaleraud et al., 1993; Low et al., 1997), Whetzel et al. (1997) described a modification that used a different injection site. Their technique involved a transthecal injection through the flexor tendon at the level of the proximal digital crease. The more readily identified landmarks at this level made their technique more reproducible. The efficacy of the transthecal block for thumb anaesthesia has not been adequately addressed. Chiu (1990) reported that three of his four failed anaesthetic attempts were on thumbs, though he did not record the total number of thumbs anaesthetised. Whetzel’s et al.’s (1997) description did not specifically state whether thumbs were included in their series. We have modified the transthecal technique by and injecting at the mid-proximal phalanx level in order to increase reproducibility and improve applicability to the thumb. The purpose of this study is to determine the efficacy of this transthecal digital block in the fingers and thumb. MATERIALS AND METHODS Between January 1998 and March 1999, all patients with dorsal or palmar finger lesions distal to the proximal The Chief, Bureau of Medicine and Surgery, Navy Department, Washington, D.C., Clinical Investigation Program, sponsored this report # S94-140 as required by NSHSBETHINST 6000.41A. The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the Navy, Department of Defense, or the United States Government. 69
70
Fig 1 Injection technique in the thumb.
incomplete anaesthesia or inability to complete the proposed procedure because of pain. RESULTS During the 15-month period, 350 patients who met the inclusion criteria underwent digital anaesthesia via the modified transthecal approach. Three hundred and sixty digits (307 fingers and 53 thumbs) were anaesthetised in 269 men and 81 women who had a mean age of 32 (range, 7–85) years. The indications included 149 fractures (distal phalanx, middle phalanx, and distal half of the proximal phalanx), 103 lacerations, 70 nailbed injuries, 26 distal infections, and 12 foreign bodies. Overall, the anaesthetic block was successful in 357 digits (99%) including 52 of 53 thumbs (98%). All necessary procedures, including all dorsal procedures, were performed without pain. In the three cases that failed, the examiner had not realised that the flexor tendon sheath had been opened by the injury, allowing the anaesthetic to flow freely out of the finger through the overlying wound. A conventional digital block was subsequently administered to such patients. All house staff reported that the technique was simple to perform and highly reproducible. No complications occurred with respect to infection, nerve or vascular injury, or flexor tendon adhesions. DISCUSSION Chiu (1990) achieved successful palmar and dorsal digital anaesthesia with his intrathecal technique in 416 of 420 patients (99%). Morrison (1993), Morros et al. (1993) and Hill et al. (1995) also obtained high (91– 100%) success rates, but other authors have reported much less satisfactory results with this technique. Chevaleraud et al. (1993) found that transthecal digital blocks failed to provide satisfactory anaesthesia to the
THE JOURNAL OF HAND SURGERY VOL. 26B No. 1 FEBRUARY 2001
dorsum of the finger and only produced satisfactory palmar anesthesia in his 350 patients. Low et al. (1997) confirmed Chevaleraud’s findings, demonstrating complete anaesthesia in only 40% of cases. They also reported that transthecal blocks were difficult to perform. Whetzel et al. (1997) modified the Chiu technique, using an injection at the proximal digital crease, and demonstrated effective and complete digital anaesthesia in all 50 cases. In a comparison of the transthecal technique to a single subcutaneous injection at the level of the A1 pulley, Low et al. (1997) demonstrated no difference with regard to the effectiveness, distribution, onset and duration of the achieved anaesthesia, and recommended the single subcutaneous injection since it was easier to administer and carried no risk of intraarticular injection. However, their success rate for thumb anaesthesia was only 78% with the transthecal technique and 81% with the subcutaneous injection. The mechanism of action of the transthecal block has been examined in a cadaveric study by Sarhadi and Shaw-Dunn (1998), who injected methylene blue and latex into 60 digits. They found that the injected solution escaped from the flexor tendon sheath around the vincular vessels at the base and head of the proximal phalanx, flowed smoothly through the perivascular loose areolar tissue, and then spread alongside the digital nerve and vessels and their palmar and dorsal branches. The injection site used in this study was midway between the proximal and middle digital creases, which we believe is a more comfortable and reproducible injection site. Additionally, since the injection site is located midway between the anatomic locations where the anaesthetic leaves the flexor sheath (Sarhadi and Shaw-Dunn, 1998), the anaethetic has a more direct route compared to the traditional transthecal or subcutaneous techniques. Low et al. (1997) recommended a single subcutaneous injection at the level of the A1 pulley to prevent intraarticular injection. Our modified injection site effectively prevents intraarticular injection, and our results for this modification of the transthecal technique are very favorable, with a 99% success rate. It is unclear from previous reports how successful the transthecal block is for producing thumb anaesthesia. However, we achieved full anaesthesia in 52 of 53 thumbs with a single injection halfway between the proximal and distal thumb creases. There were no instances of incomplete dorsal anaesthesia. These results were achieved by junior residents who reported that the technique was simple, effective and reproducible. The transthecal technique should be avoided in patients with open flexor tendon sheath injuries as the anaesthetic rapidly escapes from the sheath and out of the overlying wound; although, there is a theoretical risk of flexor tendon sheath infection with the transthecal technique, this complication has never been reported. However, we would not recommend the technique if there is an infection overlying the injection site and a
TRANSTHECAL DIGITAL BLOCK
sterile technique should always be used. The 25-gauge needle does pierce the flexor tendon, but no flexor tendon damage has been reported, and there are theoretical concerns regarding compartment syndrome due to the extravasation of fluid around the proximal phalanx causing compression of the neurovascular bundles. We saw no clinical evidence of this in our series and the swelling around the proximal phalanx usually resolved in less than an hour. No complications have been reported in the more than 1,000 transthecal injections reported in the literature. The limitations of this study are inherent to retrospective studies. There was no control group and no subjective evaluation of the pain experienced by the patients. However all the surgical blocks were tested for adequacy and all the proposed procedures were performed without additional anaesthesia when the block was successful. These limitations notwithstanding, the proximal phalanx transthecal digital block method has several advantages when compared to other techniques. The advantage of a single injection is obvious, especially for patients frightened of needles, and there is no risk of direct trauma to the neurovascular bundles. Furthermore the landmarks are easy to identify and the technique can be easily taught to others with predictable success. It is indicated when dorsal or palmar anaesthesia is needed in any digit including the thumb, but it should not be used when there is a significant open flexor tendon sheath injury. Other contraindications
71
include flexor tenosynovitis and overlying cellulitis at the injection site. References Chevaleraud E, Rogout JM, Brunelle E, Dumontier C, Brunelli F (1993). Local anesthesia of the finger using the flexor tendon sheath. Annals French Anesthesia and Reanimation, 12: 237–240. Chiu DTW (1990). Transthecal digital block: flexor tendon sheath used for anaesthetic infusion. Journal of Hand Surgery, 15A: 471–473. Hill RG, Patterson JW, Parker JC, Bauer J, Wright E, Heller MB (1995). Comparison of transthecal digital block and traditional digital block for anesthesia of the finger. Annals of Emergency Medicine, 25: 604–607. Low CK, Wong HP, Low YP (1997). Comparison between single injection transthecal and subcutaneous digital blocks. Journal of Hand Surgery, 22B: 582–584. Low CK, Vartany A, Engstrom JW, Poncelet A, Diao E (1997). Comparison of transthecal and subcutaneous single injection digital block techniques. Journal of Hand Surgery, 22A: 901–905. Morrison WG (1993). Transthecal digital block. Archives of Emergency Medicine, 10: 35–38. Morros C, Perez D, Raurell A, Rodriguez JE (1993). Digital anesthesia through the flexor tendon sheath at the palmar level. International Orthopaedics, 17: 273–274. Sarhadi NS, Shaw-Dunn J (1998). Transthecal digital nerve block: an anatomic appraisal. Journal of Hand Surgery, 23B: 490–493. Whetzel TP, Mabourakh S, Barkhordar R (1997). Modified transthecal digital block. Journal of Hand Surgery, 22A: 361–363.
Received: 11 July 2000 Accepted after revision: 6 October 2000 Dr Alexander Y. Shin, c/o Clinical Investigations Department, 34800 Bob Wilson Drive, San Diego, CA 92134, USA. # 2001 The British Society for Surgery of the Hand doi: 10.1054/jhsb.2000.0519, available online at http://www.idealibrary.com on
This study assessed the efficacy of a modified transthecal digital block. Three-hundred-and-sixty consecutive digits were anaesthetised with this technique for the treatment of fractures, infections and foreign bodies. Complete palmar and dorsal anaesthesia was achieved in 357 of the 360 digits (99%), including 52 of 53 thumbs (98%). The technique was extremely easy to perform and no complications occurred. Journal of Hand Surgery (British and European Volume, 2001) 26B: 1: 69–71 digital crease that required treatment under local anaesthesia were enrolled into a Hand Injury Registry approved by the institutional review board. The anaesthetic technique was used for lacerations, fractures, infections, and foreign bodies. Exclusion criteria included open flexor tendon sheath injuries, infections of the flexor tendon sheath, lesions with an overlying superficial infection at the proposed injection site, known allergy to lidocaine or bupivacaine, haematologic or vasospastic diseases, and a refusal to undergo treatment. All patients provided informed consent prior to their procedure, and then a modified transthecal digital block was administered at the level of the middle of the proximal phalanx. All injections were performed by house staff who were rotating through the Orthopaedic Acute Care Clinic or the Hand Service. House staff were shown the technique by one of the authors, performed one block under direct supervision and then performed subsequent blocks with indirect supervision. A syringe with a 25-gauge (light blue) needle was filled with 2 ml 1% lidocaine (Abbott Laboratories, North Chicago, IL, USA) and 2 ml 0.5% bupivacaine (Abbott Laboratories, North Chicago, IL, USA) at room temperature. Using a sterile technique, 3–4 ml of anaesthetic was injected into the flexor sheath at a point half way between the proximal digital crease and the proximal interphalangeal joint crease (palmar, mid sagittal). Pressure was applied over the A1 pulley while injecting, thereby promoting distal flow of the anaesthetic (Fig 1). As described by Whetzel (1997), the needle was passed through the flexor tendon and down to bone, and was then lifted slightly off the phalanx before the anaesthetic was injected. The thumb was anaesthetised in a similar manner with the needle inserted on its palmar surface, half way between the palmar digital and the interphalangeal creases. A successful anaesthetic block was defined as loss of sensation on both the dorsal and palmar aspects of the digit as far proximally as the level of injection, and the ability to complete the proposed procedure without pain. Failure of the digital block was defined as
INTRODUCTION Chiu (1990) described a technique of digital block that produced complete finger anaesthesia with a single injection into the flexor tendon sheath at the level of the distal palmar crease. When compared to the traditional dorsal digital block, the advantages of his technique are the use of a single injection and the absence of risk of direct trauma to the neurovascular bundles. However, as others found that Chiu’s technique did not always provide satisfactory anaesthesia (Chevaleraud et al., 1993; Low et al., 1997), Whetzel et al. (1997) described a modification that used a different injection site. Their technique involved a transthecal injection through the flexor tendon at the level of the proximal digital crease. The more readily identified landmarks at this level made their technique more reproducible. The efficacy of the transthecal block for thumb anaesthesia has not been adequately addressed. Chiu (1990) reported that three of his four failed anaesthetic attempts were on thumbs, though he did not record the total number of thumbs anaesthetised. Whetzel’s et al.’s (1997) description did not specifically state whether thumbs were included in their series. We have modified the transthecal technique by and injecting at the mid-proximal phalanx level in order to increase reproducibility and improve applicability to the thumb. The purpose of this study is to determine the efficacy of this transthecal digital block in the fingers and thumb. MATERIALS AND METHODS Between January 1998 and March 1999, all patients with dorsal or palmar finger lesions distal to the proximal The Chief, Bureau of Medicine and Surgery, Navy Department, Washington, D.C., Clinical Investigation Program, sponsored this report # S94-140 as required by NSHSBETHINST 6000.41A. The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the Navy, Department of Defense, or the United States Government. 69
70
Fig 1 Injection technique in the thumb.
incomplete anaesthesia or inability to complete the proposed procedure because of pain. RESULTS During the 15-month period, 350 patients who met the inclusion criteria underwent digital anaesthesia via the modified transthecal approach. Three hundred and sixty digits (307 fingers and 53 thumbs) were anaesthetised in 269 men and 81 women who had a mean age of 32 (range, 7–85) years. The indications included 149 fractures (distal phalanx, middle phalanx, and distal half of the proximal phalanx), 103 lacerations, 70 nailbed injuries, 26 distal infections, and 12 foreign bodies. Overall, the anaesthetic block was successful in 357 digits (99%) including 52 of 53 thumbs (98%). All necessary procedures, including all dorsal procedures, were performed without pain. In the three cases that failed, the examiner had not realised that the flexor tendon sheath had been opened by the injury, allowing the anaesthetic to flow freely out of the finger through the overlying wound. A conventional digital block was subsequently administered to such patients. All house staff reported that the technique was simple to perform and highly reproducible. No complications occurred with respect to infection, nerve or vascular injury, or flexor tendon adhesions. DISCUSSION Chiu (1990) achieved successful palmar and dorsal digital anaesthesia with his intrathecal technique in 416 of 420 patients (99%). Morrison (1993), Morros et al. (1993) and Hill et al. (1995) also obtained high (91– 100%) success rates, but other authors have reported much less satisfactory results with this technique. Chevaleraud et al. (1993) found that transthecal digital blocks failed to provide satisfactory anaesthesia to the
THE JOURNAL OF HAND SURGERY VOL. 26B No. 1 FEBRUARY 2001
dorsum of the finger and only produced satisfactory palmar anesthesia in his 350 patients. Low et al. (1997) confirmed Chevaleraud’s findings, demonstrating complete anaesthesia in only 40% of cases. They also reported that transthecal blocks were difficult to perform. Whetzel et al. (1997) modified the Chiu technique, using an injection at the proximal digital crease, and demonstrated effective and complete digital anaesthesia in all 50 cases. In a comparison of the transthecal technique to a single subcutaneous injection at the level of the A1 pulley, Low et al. (1997) demonstrated no difference with regard to the effectiveness, distribution, onset and duration of the achieved anaesthesia, and recommended the single subcutaneous injection since it was easier to administer and carried no risk of intraarticular injection. However, their success rate for thumb anaesthesia was only 78% with the transthecal technique and 81% with the subcutaneous injection. The mechanism of action of the transthecal block has been examined in a cadaveric study by Sarhadi and Shaw-Dunn (1998), who injected methylene blue and latex into 60 digits. They found that the injected solution escaped from the flexor tendon sheath around the vincular vessels at the base and head of the proximal phalanx, flowed smoothly through the perivascular loose areolar tissue, and then spread alongside the digital nerve and vessels and their palmar and dorsal branches. The injection site used in this study was midway between the proximal and middle digital creases, which we believe is a more comfortable and reproducible injection site. Additionally, since the injection site is located midway between the anatomic locations where the anaesthetic leaves the flexor sheath (Sarhadi and Shaw-Dunn, 1998), the anaethetic has a more direct route compared to the traditional transthecal or subcutaneous techniques. Low et al. (1997) recommended a single subcutaneous injection at the level of the A1 pulley to prevent intraarticular injection. Our modified injection site effectively prevents intraarticular injection, and our results for this modification of the transthecal technique are very favorable, with a 99% success rate. It is unclear from previous reports how successful the transthecal block is for producing thumb anaesthesia. However, we achieved full anaesthesia in 52 of 53 thumbs with a single injection halfway between the proximal and distal thumb creases. There were no instances of incomplete dorsal anaesthesia. These results were achieved by junior residents who reported that the technique was simple, effective and reproducible. The transthecal technique should be avoided in patients with open flexor tendon sheath injuries as the anaesthetic rapidly escapes from the sheath and out of the overlying wound; although, there is a theoretical risk of flexor tendon sheath infection with the transthecal technique, this complication has never been reported. However, we would not recommend the technique if there is an infection overlying the injection site and a
TRANSTHECAL DIGITAL BLOCK
sterile technique should always be used. The 25-gauge needle does pierce the flexor tendon, but no flexor tendon damage has been reported, and there are theoretical concerns regarding compartment syndrome due to the extravasation of fluid around the proximal phalanx causing compression of the neurovascular bundles. We saw no clinical evidence of this in our series and the swelling around the proximal phalanx usually resolved in less than an hour. No complications have been reported in the more than 1,000 transthecal injections reported in the literature. The limitations of this study are inherent to retrospective studies. There was no control group and no subjective evaluation of the pain experienced by the patients. However all the surgical blocks were tested for adequacy and all the proposed procedures were performed without additional anaesthesia when the block was successful. These limitations notwithstanding, the proximal phalanx transthecal digital block method has several advantages when compared to other techniques. The advantage of a single injection is obvious, especially for patients frightened of needles, and there is no risk of direct trauma to the neurovascular bundles. Furthermore the landmarks are easy to identify and the technique can be easily taught to others with predictable success. It is indicated when dorsal or palmar anaesthesia is needed in any digit including the thumb, but it should not be used when there is a significant open flexor tendon sheath injury. Other contraindications
71
include flexor tenosynovitis and overlying cellulitis at the injection site. References Chevaleraud E, Rogout JM, Brunelle E, Dumontier C, Brunelli F (1993). Local anesthesia of the finger using the flexor tendon sheath. Annals French Anesthesia and Reanimation, 12: 237–240. Chiu DTW (1990). Transthecal digital block: flexor tendon sheath used for anaesthetic infusion. Journal of Hand Surgery, 15A: 471–473. Hill RG, Patterson JW, Parker JC, Bauer J, Wright E, Heller MB (1995). Comparison of transthecal digital block and traditional digital block for anesthesia of the finger. Annals of Emergency Medicine, 25: 604–607. Low CK, Wong HP, Low YP (1997). Comparison between single injection transthecal and subcutaneous digital blocks. Journal of Hand Surgery, 22B: 582–584. Low CK, Vartany A, Engstrom JW, Poncelet A, Diao E (1997). Comparison of transthecal and subcutaneous single injection digital block techniques. Journal of Hand Surgery, 22A: 901–905. Morrison WG (1993). Transthecal digital block. Archives of Emergency Medicine, 10: 35–38. Morros C, Perez D, Raurell A, Rodriguez JE (1993). Digital anesthesia through the flexor tendon sheath at the palmar level. International Orthopaedics, 17: 273–274. Sarhadi NS, Shaw-Dunn J (1998). Transthecal digital nerve block: an anatomic appraisal. Journal of Hand Surgery, 23B: 490–493. Whetzel TP, Mabourakh S, Barkhordar R (1997). Modified transthecal digital block. Journal of Hand Surgery, 22A: 361–363.
Received: 11 July 2000 Accepted after revision: 6 October 2000 Dr Alexander Y. Shin, c/o Clinical Investigations Department, 34800 Bob Wilson Drive, San Diego, CA 92134, USA. # 2001 The British Society for Surgery of the Hand doi: 10.1054/jhsb.2000.0519, available online at http://www.idealibrary.com on