DEPARTMENT OF TECHNIQUE Tenosynovial injection for carpal tunnel syndrome Although local steroid injection into the tenosynovium syndrome,
is a frequent treatment for carpal tunnel
it involves some risk and is not always effective. We simulated injection on 16 fresh
cadaver forearms, instilling 1 ml (group 1) or 2 ml (group 2) of methylene blue at 1 cm or 3 cm proximal to the most distal wrist crease. Passive flexion and extension were simulated 2 minutes after injection by application
of traction to the appropriate
digital tendons. Specimens
dissected under loupe magnification from midpalm to midforearm, and photographed,
dye diffusion was quantified
sections of the carpal tunnel and contents were graded for presence of dye,
and average values were determined
for each of the four groups. Diffusion of dye was best in
group 2B in which 2 ml was injected 3 cm proximal to the distal wrist flexion crease. (J HAND
SURG1992;17A:178-81.) Yoshitaka Minamikawa, MD, Osuku, Japan, Clayton A. Peimer, MD, Buflulo, N. Y., Kenichi Kambe, MD, Osaka, Japan, Dale R. Wheeler, MD, and Frances S. Sherwin, MA, BufSalo, N. Y.
ocal steroid injection into the inflamed or reactive tenosynovium is an accepted nonoperative treatment for carpal tunnel syndrome. Although we know that locally administered steroids are pharmacologically effective,‘-” the procedure carries significant risk of injection into the median nerve.‘*-I4 Further, therapeutic injection is not always successful.‘. Is.I6Using a cadaver model, we compared two injection techniques to determine which was the best route and
From the Division of Hand Surgery, Department of Orthopaedic Surgery, State University of New York at Buffalo School of Medicine and Biomedical Sciences, Buffalo, N.Y., and the Department of Otthopaedic Surgery, Kansai Medical University, Osaka, Japan. Received for publication Jan. 17, 1991; accepted in revised form July 16, 1991. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Reprint requests: Clayton A. Peimer, MD, Hand Center of Western New York, Millard Fillmore Hospital, 3 Gates Circle, Buffalo, NY 14209. J/l132568
which also minimized risk of intraneural in-
jection . Materials
Sixteen frozen, unpreserved cadaver forearms were thawed and subdivided into four groups. We simulated traditional carpal tunnel injection* with use of a 1% inch, 22-gauge needle to instill 1 ml (group 1) or 2 ml (group 2) of methylene blue into the carpal canal with fingers in flexor cascade. For groups 1A and 2A, we injected 1 cm proximal to the most distal wrist crease between the palmaris longus and the flexor carpi radialis tendon (in line with the second web), penetrating to a depth of about half the needle and aiming about 30 degrees distally and dorsally (Fig. 1). We then simulated 10 repetitions of active flexion and passive extension 2 minutes after injection by applying traction on the appropriate tendons. Tenosynovial injection was done by the same method (group 1B = 1 ml; group 2B = 2 ml) but from a portal 3 cm proximal to the crease and ulnar to the palmaris longus (when present), in line with the third web, to the same depth and angle. The fingers were again extended and flexed by tendon traction for 10 repetitions 2 minutes later. Each specimen was then dissected under loupe magnification from
Vol. 17A. No January 1992
injection ,for carpal tunnel swdrome
Fig. 1. Injection sites: 1 cm proximal to the distal wrist (Aexion) crease (A) in line with the second web, and 3 cm proximal to this line (B) but in line with the third web. The needle was directed about 30 degrees distally and dorsally, at a depth of about % inch (half the needle length) for both sites.
to midforearm. The presence and extent of dye diffusion were quantified and photographed. We divided the carpal tunnel and contents into 16 sections and graded each area for presence of dye as + +(intense). + (mild), k (equivocal), and - (none). Average values for presence of dye were determined for each of the four groups. midpalm
Results In groups IA and 2A, dye extended distally from the injection site, primarily along the radial half of the carpal canal. The injection in one cadaver (in group 1A) was entirely dorsal to the carpal canal and was excluded from the quantified evaluation. No injections in either group were into the median nerve. In groups
The Journal of HAND SURGERY
GROUP 1A (1 cc)
GROUP 18 (1 cc)
GROUP 2A (2 cc)
GROUP 28 (2 cc)
Fig. 2. Assessment of dye presence and diffusion into carpal tunnel structures after injection of
methylene blue. Diffusion of dye in the carpal canal is illustrated in this cross section by graded shadings. MN, Median nerve; FPL, flexor pollicis longus; Roman numerals refer to finger rays; S, superficialis; P, profundus.
1B and 2B, dye not only stained most of the flexor tenosynovium, but the canal floor was also well stained both radially and ulnarly (Fig. 2).
Discussion Canal injection is frequently performed because carpal tunnel syndrome is such a common problem. We usually assume that we have successfully injected into the carpal tunnel despite the fact that some patients fail to benefit from this injection. In 1960 the classic article by Foster’ demonstrated the method of carpal tunnel injection medial (ulnar) to the palmaris longus to avoid the median nerve. In 1980 Wood” found that even a skillful hand surgeon failed to inject within the canal in 10% of the cases. In one cadaver in this series (6%), we missed the carpal tunnel entirely when injecting by the classic method. In 1982 Mackinnon et al.‘* described the problems of inadvertent steroid injection into the median nerve. Surprisingly, there have been many different approaches to tunnel injection, some along the ulnar bor-
der of the palmaris longus ‘25.‘. I’, r4.I7 and others at the radial side.‘, ‘* To minimize risk of nerve damage, both injection parallel to the flexor surface’9 and firm compression proximal to the edge of the carpal tunnel to prevent proximal migration of injection solution (4 ml) have been advocated. However, proximal compression and injection of up to 4 ml of solution might well be uncomfortable for the patient, raising the question of why distal compression would not also need to be applied. Our cadaver study revealed that solution injected into the canal tended to move longitudinally away from the needle, just as one would expect in a living patient. Green’s method’ of injection includes palpation of distal bulging from the lidocaine initially instilled to confirm needle position, followed by careful change of the syringe to the steroid solution. Even if his method were ideal, it is significantly more time-consuming. This dissection study demonstrates that reproducible delivery of medication requires 2 ml of solution (injection volume). The portal 3 cm proximal to the carpal
Vol. 17A, No. 1 January 1992
canal also offers more (theoretical) protection for the median nerve; however, in this study we never hit the nerve. Although we do not know that injection of methylene blue dye into thawed, unpreserved cadavers mimics exactly injection into live patients, the anatomic model is the closest we have. For purposes of this study, we assumed that dye performs similarly to other injectable solutions. In clinical practice, if an equal mixture of anesthetic and steroid solutions is injected, the 2 ml volume is easily achieved. The findings of the study justify consideration of this route, dose, and technique. REFERENCES 1. Foster JB. Hydrocortisone and the carpal tunnel syndrome. Lancet 1960; 1:454-6. 2. Gelberman RH, Avconson D. Weisman MH. Carpal tunnel syndrome: results of a prospective trial of steroid injection and splinting. J Bone Joint Surg 1980; 62A:ll81-4. 3. Gelberman RH, Rydevik BL, Pess GM, Szabo RM, Lundborg G. Carpal tunnel syndrome: a scientific basis for clinical care. Orthop Clin North Am 1988;19:11524. 4. Goodwill CJ. The carpal tunnel syndrome: long-term follow-up showing relation of latency measurements to response to treatment. Ann Phys Med 1965;8:12-21. 5. Green DP. Diagnostic and therapeutic value of carpal tunnel injection. J HAND SURG 1984;9A:850-4. 6. Gray RG, Tenenbaum J, Gottlieb NL. Local corticosteroid injection treatment in rheumatic disorders. Semin Arthritis Rheum 1981;10:231-54. 7. Phalen GS. The carpal tunnel syndrome: seventeen years
Tenosynovial injection for carpal tunnel syndrome
experience in diagnosis and treatment of six hundred fifty-four hands. J Bone Joint Surg 1966;48A:21 l-28. 8. Phalen GS. The carpal tunnel syndrome: clinical evaluation of 598 hands. Clin Orthop 1972;83:29-40. 9. Myles AB, Casemore VA, Coulthard M, Gilliam G, Schiller LF. Management of the carpal tunnel syndrome with local corticosteroid injections. Rheumatol Rehabil 1973;12:205-8. 10. Ozdogan H, Yazici H. The efficacy of local steroid injections in idiopathic carpal tunnel syndrome: a double blind study. Br J Rheumatol 1984;23:272-5. 11. Schuchmann JA, Melvin JL, Duran RJ, Coleman CR. Evaluation of local steroid injection for carpal tunnel syndrome. Arch Phys Med Rehabil 197 1;52:253-55. 12. Mackinnon SE, Hudson AR, Gentili F, Kline DG, Hunter D. Peripheral nerve injection injury with steroid agents. Plast Reconstr Surg 1982;69:482-9. 13. McConnell JR, Bush D. Intraneural steroid injection as a complication of carpal tunnel syndrome: a report of three cases. Clin Orthop 1990;250: 18 l-4. 14. Linskey ME, Segal R. Median nerve injury from local steroid in carpal tunnel syndrome. Neurosurgery 1990;26:512-5. 15. McGrath MH. Local steroid therapy in the hand. J HAND SURG 1984;9A:915-21. 16. Otto N. Wehbe M. Steroid injections for tenosynovitis in the hand. Orthop Rev 1986;15:290-3. 17. Wood MR. Hydrocortisone injections for carpal tunnel syndrome. Hand 1980;12:62-4. 18. Dieppe PA, Bacon PA, Bamji AN, Watt I. Atlas of clinical rheumatology. Philadelphia: Lea & Febiger, 1986. 19. Cyriax J, Russell G. Textbook of orthopaedic medicine. London: Bailliere Tindall, 1980:220- 1.