The advantages and disadvantages of endoscopic

Endoscopic versus open carpal tunnel release in bilateral carpal tunnel syndrome A PROSPECTIVE, RANDOMISED, BLINDED ASSESSMENT R. D. Ferdinand, J. G. B. MacLean From Perth Royal Infirmary, Scotland The advantages and disadvantages of endoscopic compared with open carpal tunnel release are controversial. We have performed a prospective, randomised, blinded assessment in a district general hospital in order to determine if there was any demonstrable advantage in undertaking either technique. Twenty-five patients with confirmed bilateral idiopathic carpal tunnel syndrome were randomised to undergo endoscopic release by the single portal Agee technique to one hand and open release to the other. Independent preoperative and postoperative assessment was undertaken by a hand therapist who was blinded to the type of treatment. Follow-up was for 12 months. The operating time was two minutes shorter for the open technique (p <.5). At all stages of postoperative assessment, the endoscopic technique had no significant advantages in terms of return of muscle strength and assessment of hand function, grip strength, manual dexterity or sensation. In comparison with open release, single-portal endoscopic carpal tunnel release has a similar incidence of complications and a similar return of hand function, but is a slightly slower technique to undertake. J Bone Joint Surg [Br] 22;84-B:375-9. Received 28 February 21; Accepted after revision 23 August 21 Open release of the flexor retinaculum is the most common operation undertaken for the treatment of carpal tunnel syndrome. The complications after this procedure have been well documented 1,2 and are often a consequence of the palmar scar. Endoscopic release has been proposed as a R. D. Ferdinand, FRCS (Trauma & Orth), Orthopaedic Specialist Registrar J. G. B. MacLean, FRCS Orth, Consultant Orthopaedic Surgeon Perth Royal Infirmary, Jeanfield Road, Perth PH1 1NX, UK. Correspondence should be sent to Mr J. G. B. MacLean. 22 British Editorial Society of Bone and Joint Surgery 31-62X/2/312224 $2. method of decompressing the tunnel through a smaller incision sited away from the middle of the palm. 3-5 Initially, endoscopic release involved a two-portal technique and had a high incidence of complications, 6-8 which were related to the distal portal. 7,8 Agee et al 9 developed a single-portal technique in which visualisation of the structures to be divided was maintained throughout the procedure. The reported incidence of complications for this technique was lower than that for earlier methods. 1 The theoretical advantages of an endoscopic release are reduced tenderness of the scar, an earlier return of grip strength, and an earlier return to work. The perceived disadvantages are an increased risk of nerve damage and questionable efficacy. The technique is also more expensive. We have therefore compared the endoscopic and open techniques in order to determine any differences in outcome. Patients and Methods Between 1996 and 1998, 25 patients with bilateral idiopathic carpal tunnel syndrome, whose symptoms had persisted for more than three months despite the use of a night splint, were included in the study. All had nerve-conduction studies. Those with bilateral conduction delay at the carpal tunnel in the absence of any other abnormality were included. Patients who had had previous surgery to the wrist or hand were excluded. Details of the patients are given in Table I. All were right-handed. The independent preoperative assessment included a detailed history and record of the time taken to carry out activities of daily living in a standardised setting. This was based on the performance of 11 tasks. In each a score of was given if performed independently, 1 if performed with difficulty and 2 if dependent. Examination comparing both hands included the grading of the strength of the thenar muscle (abductor pollicis brevis and opponens pollicis, MRC graded scale to 5), dynamometry of lateral pinch using a B & L pinch gauge (Fabrication Enterprises Inc, New York) and grip strength using a baseline dynamometer (B & L Engineering, Santa Fe, New Mexico). Goniometry of the wrist and finger movement were recorded and functional assessment was according to the method of Jebson et VOL. 84-B, NO. 3, APRIL 22 375

376 R. D. FERDINAND, J. G. B. MACLEAN Table I. Details of the 25 patients with bilateral carpal tunnel syndrome, and of the outcome at 6, 12, 26 and 52 weeks after endoscopic and open carpal tunnel release Return to Age Worst Days off full activity Activities of daily living score Case Gender (yrs) Employment (R = retired) side work (wks) Preop 6 12 26 52 Improvement 1 F 85 Private home help (R) L N/A 2 6 3 2 1 6 2 F 51 Restaurant cleaner R 4 12 9 3 2 1 9 3 M 45 Aircraft engineer R 25 6 4 2 4 4 M 57 Building engineer-unempl R N/A 2 3 1 1 5 F 62 Woollen shop L 11 6 2 2 2 6 M 31 Caring profession R 41 12 4 2 1 1 4 7 F 59 District nurse (R) L N/A 12 5 4 4 2 1 4 8 F 53 Typist-unempl R 3 12 3 2 1 1 1 2 9 F 42 Cook (R) R N/A 2 8 6 6 2 2 6 1 F 74 R R N/A 26 8 6 6 2 7 11 F 42 Ice rink (R) R N/A 12 5 1 1 1 5 12 F 49 School cook L 7 12 8 1 1 1 8 13 M 65 Consultant engineer L 14 6 1 1 14 F 42 Childminder L 28 6 8 3 1 8 15 F 62 Nurse (R) R N/A 12 7 4 1 7 16 F 5 Housewife (disabled) R N/A 12 14 17 1 9 4 1 17 F 75 R L N/A 2 5 2 1 5 18 M 47 Manager R 2 16 1 3 11 5 2 8 19 F 59 Cook L 14 12 7 7 5 3 1 6 2 F 78 R R N/A 6 8 4 3 1 8 21 F 47 Social worker R 56 12 8 11 6 2 8 22 F 49 Shop assistant R 19 12 5 5 1 5 23 F 48 Receptionist R 21 12 4 2 4 24 F 48 Housewife R N/A 52 1 6 5 1 25 F 52 Cook R 42 12 5 4 5 al 11 which is based on the sum of the time taken to perform seven specific manual tasks. Sensory impairment was assessed by static two-point discrimination over the middle and distal phalanges of the index, middle and ring fingers. Static testing was done since moving two-point discrimination has been shown to confer no advantage. 12 On the thumb, two-point discrimination over the proximal and distal phalanges was recorded. In the assessment of strength, movement and sensation, three recordings were made and the mean of these taken as the true measure. Finally, a nine-peg test for manual dexterity was timed. The same surgeon (JGBM) carried out all the operations. Randomisation was by standard computerised methods to determine which side underwent endoscopy. The contralateral release was by the open method. Figures 1a and 1b show the anatomical landmarks used to determine the position of the incisions. In Figure 1b x marks the site of the pisiform. Carpal tunnel release was undertaken sequentially under the same anaesthetic. The use of exsanguination and a tourniquet on the upper arm was standard procedure. If a clear endoscopic view of the tunnel could not be achieved, endoscopy was abandoned in favour of an open procedure. Open release was under loupe magnification. The wounds were closed with interrupted monofilament sutures and the tourniquet was not released before bandaging. The operating time was recorded from the point at which the tourniquet was inflated to that of completion of suturing. The postoperative management was identical for both groups with removal of sutures at two weeks, when the wounds were covered with an adherent dressing. This concealed from the therapist and the patient which type of release had been performed. The first postoperative assessment was undertaken at this stage. Postoperative assessment recorded the degree of resolution of the presenting symptoms with regard to numbness, pain and paraesthesiae. Pain in the scar and tenderness in the palm were assessed on a visual analogue scale of 1 to 1. Subsequent assessments were made at 6, 12, 26 and 52 weeks after operation. The patient concealed the wounds with adherent dressings before each assessment to ensure that the assessor continued to be blinded to the type of release which had been performed. At these sessions all the objective preoperative assessments were repeated, and both the time of return to work and the time to full activity were recorded. In order to assess the subjective outcome, patient satisfaction with each wrist was recorded on a percentage scale (% complete dissatisfaction, 1% complete satisfaction). The mean scores of each group were analysed by Student s t-test to determine the significance of any identified differences. Results Table I gives details of the patients, the changing level of activities of daily living, the time of return to full activity and the time off work, where appropriate. Both groups were similar. THE JOURNAL OF BONE AND JOINT SURGERY

ENDOSCOPIC VERSUS OPEN CARPAL TUNNEL RELEASE IN BILATERAL CARPAL TUNNEL SYNDROME 377 Fig. 1a Fig. 1b The anatomical landmarks used to determine the position of the incision for a) the open and b) the endoscopic methods. In three patients undergoing endoscopic decompression an inadequate view was obtained and an open release was done. The mean operating time was 1 ± 2 minutes for the open procedure and 13 ± 4 minutes for the endoscopic release. This difference was significant at p <.5. Figure 2 gives the objective outcomes recorded during the first postoperative year. These include the results of the hand function test of Jebson et al, 11 grip strength and sensation. There was no statistical difference in these when both techniques were compared. As regards the subjective outcome, measurement of the resolution of symptoms and patient satisfaction showed no statistical difference between the two techniques at any time during the first year (Fig. 3). Table II is a record of the complications observed. The injury to the superficial palmar branch was re-explored at six weeks. The branch was found to be intact, but tethered in scar tissue. The persisting pain in the wound which was identified in two patients was localised to the scar and did not extend into the territory of the superficial palmar branch. The tenderness experienced over the endoscopic incision was particularly troublesome since it was exacerbated by contact with clothing and watch straps. Desensitisation provided some benefit in each patient, but did not completely relieve the tenderness. Discussion Division of the flexor retinaculum under direct vision is widely practised and is a safe procedure with a predictable outcome and a relatively low incidence of complications. Single-portal endoscopic release has been developed to address the shortcomings of open release, most of which relate to the size and siting of the scar. It has been suggested that, by reducing the size of the incision and removing it from the middle of the palm, tenderness and VOL. 84-B, NO. 3, APRIL 22

378 R. D. FERDINAND, J. G. B. MACLEAN Percentage satisfaction 8 7 6 5 4 3 2 1 1 9 8 7 6 5 4 3 2 1 2 6 Endoscopic Jebson score (secs) Open Jebson score (secs) Endoscopic grip strength (lbs) Open grip strength (lbs) Endoscopic sensation (mm of 2-point discrimination) Open sensation (mm of 2-point discrimination) 12 26 Weeks after operation Fig. 2 Objective outcomes after open and endoscopic release. 52 Endoscopic Open 6 12 26 52 Weeks after operation Fig. 3 Patient satisfaction, as a percentage, after open and endoscopic release for carpal tunnel syndrome. Table II. Complications after either open or endoscopic carpal tunnel release Complication Open Endoscopic Persistent symptoms and signs 1 of carpal tunnel syndrome Superficial sensory nerve injury 1 Motor branch injury Vascular injury Persisting wound pain 1 1 scar sensitivity may be avoided. In addition, by retaining the superficial fascia overlying the retinaculum and preserving some of the insertion of the thenar and hypothenar muscles, grip strength may be preserved, recovery time reduced and an earlier return to work anticipated. Scepticism persists as to the place of endoscopic carpal tunnel release within the National Health Service. To alter current practice endoscopic release would have to be shown to be at least as effective as open release, at no greater risk to the patient and no greater expense to the service. In our study we set out to identify whether endoscopic release fulfilled these aims. While it is appreciated that studies in which the patient is also used as the control are not ideal, we have attempted to address this problem in as scientific and unbiased a manner as possible. In order to reduce the bias associated with learning a new technique, the surgeon did not undertake the study until he was familiar with it. He attended a cadaver course on endoscopic release and carried out 15 procedures by the method of Agee et al 9 before embarking on the study. As with any new surgical technique there is a learning curve which we suggest, in agreement with other authors, 13 exceeds that associated with open surgery. This factor is relevant to the time taken to undertake the procedure. In our study open release took less time and while the difference was statistically significant, the magnitude of the difference is not regarded as being of practical significance. Had the study been undertaken without previous experience of the endoscopic technique the difference would have been greater. The incidence of complications was also no greater for endoscopic release; the only nerve injury was that of a superficial palmar branch which occurred after an open procedure. In those patients who had tenderness of the scar after endoscopic release it appeared to be more persistent and intense, although at one year there was no difference between the two groups. Subjective satisfaction was similarly high for both groups at all stages of postoperative assessment. Objective assessment of grip strength, sensation and hand function were similar for both groups. A steady improvement in all parameters occurred up to one year. The exception was sensory deficit, which improved during the first three months and then remained static. Since the patients underwent bilateral surgery it was not possible to comment on the relative merits of the different types of surgery in relation to return to full activity and work. With no statistical difference in the results of the objective tests between the two techniques, it is reasonable to assume that return to full activity and work is similar in both procedures. The cost of endoscopic carpal tunnel release includes the cost of hiring or purchasing the Agee handle and endoscope and renders the procedure more expensive than an open release. THE JOURNAL OF BONE AND JOINT SURGERY

ENDOSCOPIC VERSUS OPEN CARPAL TUNNEL RELEASE IN BILATERAL CARPAL TUNNEL SYNDROME 379 Our findings show therefore that, in patients with idiopathic carpal tunnel syndrome, decompression of the carpal tunnel by endoscopy confers no advantage over standard open release. The authors gratefully acknowledge the help of Mrs E. Campbell and Mrs K. Stewart of the Department of Occupational Therapy, Perth Royal Infirmary, in the running of this trial. 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. References 1. Kulick MI, Gordillo G, Javidi T, et al. Long-term analysis of patients having surgical treatment for carpal tunnel syndrome. J Hand Surg [Am] 1986;11:59-66. 2. Nancollas MP, Peimer CA, Wheeler DR, Sherwin FS. Long-term results of carpal tunnel release. J Hand Surg [Br] 1995;2:47-4. 3. Boeckstyns ME, Sørensen AI. Does endoscopic carpal tunnel release have a higher rate of complications than open carpal tunnel release?: an analysis of published series. J Hand Surg [Br] 1999;24:9-15. 4. Palmer AK, Toivonen DA. Complications of endoscopic and open carpal tunnel release. J Hand Surg [Am] 1999;24:561-5. 5. Mackenzie DJ, Hainer R, Wheatley MJ. Early recovery after endoscopic vs short incision open carpal tunnel release. Ann Plast Surg 2;44:61-4. 6. Nath RK, Mackinnon SE, Weeks PM. Ulnar nerve transection as a complication of two-portal endoscopic carpal tunnel release: a case report. J Hand Surg [Am] 1993;18:896-8. 7. Murphy RX, Jennings JF, Wukich DK. Major neurovascular complications of endoscopic carpal tunnel release. J Hand Surg [Am] 1994;19:114-8. 8. Scoggin JF, Whipple TL. A potential complication of endoscopic carpal tunnel release. Arthroscopy 1992;8:363-5. 9. Agee JM, McCarroll HR, Tortosa RD, et al. Endoscopic release of the carpal tunnel: a randomised prospective multicentre study. J Hand Surg [Am] 1992;17:987-95. 1. Erhard L, Ozalp T, Citron N, Foucher G. Carpal tunnel release by the Agee endoscopic technique: results at 4 year follow-up. J Hand Surg [Br] 1999;24:583-5. 11. Jebsen RH, Taylor N, Trieschmann RB, Trotter MJ, Howard LA. An objective and standardised test of hand function. Arch Phys Med Rehabil 1969;5:311-9. 12. Szabo RM, Gelberman RH, Dimick MP. Sensibility testing in patients with carpal tunnel syndrome. J Bone Joint Surg [Am] 1984;66:6-4. 13. Cobb TK, Knudson GA, Cooney WP. The use of topographical landmarks to improve the outcome of Agee endoscopic carpal tunnel release. Arthroscopy 1995;11:165-72. VOL. 84-B, NO. 3, APRIL 22