HAND SURGERY
Triggering of the Digits After Carpal Tunnel Surgery Mehmet Ali Acar, MD,* Harun Ku¨tahya, MD,Þ Ali Gu¨lec¸, MD,* Mehmet Elmada?, MD,þ Nazım Karalezli, MD,§ and Tunc Cevat Ogun, MD|| Introduction: Carpal tunnel syndrome (CTS) and trigger finger may be seen simultaneously in the same hand. The development of trigger finger in patients undergoing CTS surgery is not rare, but the relationship between these conditions has not been fully established. The aims of this prospective randomized study were to investigate the incidence of trigger finger in patient groups undergoing transverse carpal ligament releasing (TCL) or TCL together with distal forearm fascia releasing and to identify other factors that may have an effect of these conditions. Materials and Method: This prospective randomized study evaluated 159 hands of 113 patients for whom CTS surgery was planned. The patients were separated into 2 groups: group 1 (79 hands of 57 patients) undergoing TCL releasing only and group 2 (80 hands of 56 patients) undergoing TCL and distal forearm fascia releasing together. The age and gender of the patients, dominant hand, physical examination findings, visual analogue scale (VAS), and electromyography (EMG) results were recorded. Follow-up examinations were made at 1, 3, 6, 12, and 24 months for all patients. We noted development of trigger finger in the surgical groups, and its location and response to treatment. Results: The incidence of trigger finger development was statistically significantly different between group 1 and group 2 (13.9% and 31.3%, respectively). The logistic regression analysis of factors affecting the development of trigger finger posttreatment found that the surgical method and severity of EMG were significant, whereas the effects of the other factors studied were not found to have any statistical significance. Conclusion: There was an increased risk of postoperative trigger finger development in patients undergoing TCL and distal forearm fascia releasing surgery for CTS compared to those undergoing CTL only. There is a need for further studies to support this result and further explain the etiology. Key Words: carpal tunnel syndrome, trigger finger, transverse carpal ligament, forearm facia, carpal tunnel surgery (Ann Plast Surg 2015;75: 393Y397)
C
arpal tunnel syndrome (CTS), which is one of the most important causes of pain, neurological findings, and functional restriction in the hand, is the most frequently encountered entrapment neuropathy with a prevalence of 2.7% in the general population.1 Although conservative treatments exist, the majority of patients require surgical release of the carpal tunnel.2 Trigger finger is a stenosing tenosynovitis that is generally characterized by pain, swelling, restricted finger movement, and painful locking of the finger.3 Just as trigger finger and CTS may be seen simultaneously in the same hand, trigger finger may develop after CTS surgery.4Y14 Received January 2, 2014, and accepted for publication, after revision, March 22, 2014. From the *Department of Orthopedics and Traumatology, Medical School of Selcuk University. Konya; †Department of Orthopedics and Traumatology, Beyhekim State Hospital, Konya; ‡Department of Orthopedics and Traumatology, BezmiAlem Foundation University, Istanbul; §Department of Orthopedics and Traumatology, N.E. University Meram School of Medicine, Konya; and ||Department of Orthopedics and Traumatology, Medicana Konya Hospital. Konya, Turkey. Conflicts of interest and sources of funding: none declared. Reprints: Mehmet Ali Acar, MD, Department of Orthopedics and Traumatology, Medical School of Selcuk University, Konya, Turkey. E-mail: mehmetaliacar@ selcuk.edu.tr. Copyright * 2014 Wolters Kluwer Health, Inc. All rights reserved. ISSN: 0148-7043/15/7504-0393 DOI: 10.1097/SAP.0000000000000233
Annals of Plastic Surgery
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The development of trigger finger after carpal tunnel surgery has been reported by several researchers.9Y11,13,14 Differences in trigger finger development between endoscopic surgery and open surgical methods have also been previously studied. In a study by Harada et al,10 in which endoscopic methods and mini open methods were performed in a total of 875 patients, it was reported that 101 (11.5%) patients required trigger finger release surgery after CTS surgery. Those authors found that the choice of endoscopic or open surgery methods had no effect on the rate of trigger finger development. In both endoscopic and mini open surgery, a release was performed only on the transverse carpal ligament (TCL). In the standard open surgical method, the TCL is released together with the distal forearm fascia. We noted that no study has been conducted to date examining the incidence of trigger finger development in 2 differing techniques of the open carpal tunnel release. The primary aim of the present prospective study was to compare the rates of trigger finger development in patients treated with 2 variations of the open carpal tunnel release surgery, one with and one without forearm antebrachial fascia division.
PATIENTS AND METHODS The study included patients who were recommended for surgery for idiopathic CTS and were followed up at our clinic. Study approval was granted by the Local Ethics Committee, and informed consent was obtained from each patient. The criteria for surgical release of the carpal tunnel included symptoms severe enough to wake the patient at night and impede daily living activities, physical examinations (Phalen and Tinel tests), and electromyography (EMG) results supporting CTS. Patients with etiological factors predisposing them to CTS such as diabetes mellitus, acute trauma, rheumatoid arthritis, pregnancy, hypothyroidism, and hyperthyroidism were not included in the study. Patients who had trigger finger in preoperative physical examination, who had a history of operation and/or injection history because of trigger finger, and who had been detected to have pain or nodularity on A1 pulley were excluded from the study. We planned a follow-up period of at least 24 months, with removal of patients who did not complete the follow-up from the study results. All surgical procedures were performed by the same surgeon. The patients were randomized into 2 groups using a computer-generated randomization table. Patients with bilateral CTS were operated on in different sessions. Group 1 underwent TCL releasing alone, whereas group 2 had both TCL and distal forearm fascia releasing.
Surgical Technique Group 1: With the hand in supination under tourniquet control and the wrist in 15-degree extension, at the junction point of the long axis of the third web and the Kaplan line, a 2-cm incision 2 mm ulnar to the thenar line was made proximally. After passing subcutaneously without damaging the palmar sensory branch of the median nerve, the proximal and distal portions of the TCL were released while protecting the median nerve along the ulnar edge of the TCL (Fig. 1). Primary skin suturing was performed. A compressive bandage was applied; after 15 minutes, it was loosened and re-applied. Group 2: After releasing the TCL, while protecting the median nerve, the proximal portion of the distal forearm fascia was released (1 cm) by advancing scissors under the skin (Fig. 2). www.annalsplasticsurgery.com
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Statistical analysis of the data obtained in the study was made using SPSS 16 software program. Crosstabs W2 and Fisher exact chisquare test were used to evaluate the categorized and ordinal scale parameters and the group comparisons. To determine which parameters had affected the development of trigger finger, logistic regression analysis was used. Descriptive characteristics such as patient age, gender, and dominant side were evaluated with descriptive statistical tests (frequencies, descriptives).
RESULTS
FIGURE 1. Surgical method for carpal tunnel release in group 1 (transverse carpal ligament release only).
Postoperative protocol: After the surgery, all patient groups were applied a large bulky dressing to restrict wrist range of motion in the early postoperative period. The bulky dressings were removed 2 days after the surgery. The patients were instructed in range of motion exercises for finger, wrist, and arm. The sutures were removed 10 to 12 days after surgery. Four weeks after surgery, patients were permitted to return daily life with weight restriction, and 6 to 8 weeks after surgery, they were permitted for full activity. The preoperative demographic data of the patients, pain scores, and CTS severity were recorded. Pain scores were evaluated by Visual Analogue Scale (VAS, 0Y10), and the severity of CTS was classified as mild, moderate, or severe according to the sensory conduction rate in EMG and motor distal latency distance. 1. MildVslow orthodromic sensory conduction rate (G44 m/s) and normal motor distal latency. 2. ModerateVslow sensory conduction rate (G44 m/s) and motor distal latency extending from more than 4.4 ms. 3. SevereVextended or loss of motor distal latency and potential loss of sensory nerve axon.
The demographic data of the patients and the preoperative physical examination results, VAS scores, and EMG values are shown in Table 1.The results of the 24-month postoperative physical examination (Phalen, Tinel), VAS scores, relief of nighttime paresthesia complaints, EMG changes, development of trigger finger, and P values are shown in Table 2. Trigger finger had occurred during follow-up in 34 cases (bilaterally in 2 cases) in total of 113 patients who underwent surgery. Considering the 159 hands operated, 36 had developed trigger finger. Although 25 (31.3%) of the 80 hands in group 2 had developed trigger finger, 11 (13.9%) of the 79 hands in group 1 developed trigger finger postoperatively. Trigger finger development was significantly higher in group 2 than the group 1 (P = 0.007). Although 11 hands demonstrated single trigger finger development, 2 fingers’ involvement were detected in one hand after surgery in group 1. Sixteen hands revealed single trigger finger development and 2 digits involvement were detected in 8 hands postoperatively in group 2. Eventually, a total of 45 fingers in 36 hands developed trigger finger after surgery. The distribution of trigger finger localizations are given in Table 3. In the logistic regression analysis of patients who developed postoperative trigger finger, the parameters thought to affect the development of trigger finger (age, gender, surgical method, EMG results) were examined in the same model. Although the surgical method and EMG results were found to be statistically significant in the model (P G 0.05), age and gender had no statistically significant effect on the development of trigger finger (P 9 0.05). Their relative risks with 95% confidence intervals are listed in Table 4. No significant difference was found between the 2 surgical groups in terms of time to trigger finger development during follow-up and response to treatment. Trigger finger developed in 36 (22.6%) hands of 34 patients at a mean 5.1 months (range, 3Y6 months) after CT
As the number of hands in the mild group was low, these patients were included in the moderate group for further analysis. At the postoperative 1st, 3rd, 6th, 12th, and 24th month, the presence of trigger finger and its location and pain scores were recorded for all patients. Those patients with sensitivity and/or nodules over the metacarpophalangeal joint, restricted finger movements, or finger locking were considered to be positive for trigger finger. The groups were compared according to the physical examination findings at 24-month follow-up with respect to VAS, EMG, and trigger finger development. For patients who developed trigger finger, conservative treatment was used initially, consisting of non-steroidal antiinf lammatory medication, splinting, and steroid injections. In cases in which the patient had no response to conservative treatment, open surgical release of the first annular pulley (A1) was done.6
Statistical Analysis Power analysis was performed and a N of 51 has power of 80% to detect an effect size of operation technique used in group 1 or group 2. PASS 2013 (Power Analysis and Sample Size) statistical software program was used for the sample size determination. 394
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FIGURE 2. Surgical method for carpal tunnel release in group 2 (transverse carpal ligament and forearm fascia release). * 2014 Wolters Kluwer Health, Inc. All rights reserved.
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Annals of Plastic Surgery
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Triggering of Digits After Carpal Tunnel Surgery
TABLE 1. The Demographic Characteristics of 2 Group Patients Parameters
Total
Total hands Age (mean, range) Gender (F/M) Night-time paresthesia (Y/N) Duration, mo DominantYnon-dominant hands Right side/left side/bilateral side Phalen +/j Tinel +/j VAS EMG
159 52.87 T 8.58 (31Y77) 148/11 156/3 30.27 T 25.19 153/6 29/38/92 129/30 48/111 6.83 T 2.49 53/106
Group 2
P
80 52.53 T 10.04 (31Y77) 90%/10% (72/8) 100%/0.00% (80/0) 23.52 T 18.05 98.8%/1.2% (79/1) 11.4%/17.7%/70.9% (9/14/56) 77.5%/22.5% (62/18) 32.5%/67.5% (26/54) 6.52 T 2.70 33.8%/66.2% (27/53)
0.618 0.109 0.120 0.001* 0.180 0.004* 0.165 0.321 0.120 0.522
Group 1 79 53.22 T 7.13 (34Y75) 96.2%/3.8% (76/3) 92.2%/3.8% (76/3) 37.12 T 29.34 94.9%/5.1% (74/5) 25%/30%/45% (20/24/36) 84.8%/15.2% (67/12) 27.8%/72.2% (22/57) 7.13 T 2.23 32.9%/67.1% (26/53)
*P G 0.05 is statistically significant. Gender: femaleYmale; Phalen/Tinel: positiveYnegative; VAS, Visual Analogue Scale; EMG (electromyography): moderateYsevere.
release. In the follow-up of these patients, 9 (25%) hands recovered spontaneously at a mean 2.6 months later, 4 (11.1%) hands recovered at a mean 4.2 months with conservative treatment, and 10 (27.8%) hands completely recovered at a mean 2.1 months after steroid injections (pain and locking was resolved). In 4 (11.1%) hands that were treated conservatively and 3 (8.3%) hands that had received a steroid injection, the pain was relieved and the locking receded to a level that was not uncomfortable. In 6 hands, pain and locking were not resolved despite steroid injection, and trigger finger surgery was performed at a mean 6.1 months later. The rate of trigger finger releasing following CT release was 16.7%.
DISCUSSION The results of this study showed that, in the patient group that underwent distal forearm fascia with TCL release compared to the group who had TCL release alone, the incidence of development of trigger finger was significantly increased. A common pathogenesis and relationship between CTS and trigger finger has been debated by many authors.4,8Y10,14Y16 In a prospective study by Kumar et al to determine any relationship between idiopathic CTS and trigger finger, patients presenting with both CTS and trigger finger were compared to those presenting with CTS alone. The results showed that of 551 patients, 211 had at least one trigger finger, and of the 211 patients with trigger finger, 91 (43%) had CTS. The data supported a correlation between idiopathic CTS and idiopathic trigger finger and a common pathophysiological factor. Hayashi et al9 reported that trigger finger developed postoperatively in 52 of 64 hands operated on for CTS and that trigger finger also developed in 9 of 101 hands treated conservatively after a 1-year follow-up period.
In a retrospective review by Kim et al13 of 633 hands in 362 patients who underwent carpal tunnel release for idiopathic carpal tunnel syndrome, cervical arthritis was found in 253 patients (70%) with C5 to C6 arthritis as the most common site. Basal joint arthritis of the thumb was observed in 216 (34%) of the 633 hands. Preoperative trigger finger or de Quervain (DQ) disease was observed in 85 of the 633 hands (13%), and these disorders developed in 67 hands (11%) postoperatively. Patient education about cervical arthritis, basal joint arthritis, and trigger digit is very important, as these disorders commonly coexist with idiopathic carpal tunnel syndrome. In a study by King et al, trigger finger was observed at a rate of 6.6% in the hand that had undergone CT release, compared with 3.5% for the untreated contralateral hand. The most common location of trigger finger after CT release was the thumb. The prevalence of trigger finger in the little finger was equal between the groups, and trigger finger in the other digits was observed more often in the untreated hand. The dominant hand was more likely to be affected when trigger finger developed after CT release. The incidence of DQ in the hand that had undergone CT release was 0.5%, compared with 0.8% for the untreated contralateral hand. No significant correlations were found between trigger finger or DQ and other conditions. In a retrospective chart review by Goshtasby et al,14 792 CT release procedures and multiple variables were compared in patients who did and did not develop trigger finger after CT release. The incidence of new-onset trigger finger after CT release was 6.3%. Multivariate regression analysis showed that osteoarthritis and undergoing an endoscopic procedure were the only 2 independent risk factors. Thus, it was recommended that patients should be made aware of the potential sequelae of trigger finger before an endoscopic procedure for CT release. In studies by Hombal, Hayashi, and Harada et al, it was suggested the development of trigger finger after carpal tunnel release
TABLE 2. Characteristics of Patients After the Surgery Parameters Phalen +/j Tinel +/j VAS Night-time paresthesia (Y/N) EMG Trigger finger development (Y/N)
Total
Group 1
Group 2
P
28/131 18/141 1.12 T 2.23 0/159 152/7 36/123
16.5%/83.5% (13/66) 10.1%/89.9% (8/71) 1.00 T 2.09 0%/100% (0/79) 94.9%/5.1% (75/4) 13.9%/86.1% (11/68)
18.8%/81.2% (15/65) 12.5%/87.5% (10/70) 1.26 T 2.38 100%/0.00% (80/0) 96.2%/4.8% (77/3) 31.3%/66.8% (25/55)
0.432 0.413 0.538 0.107 0.458 0.007
Phalen/Tinel: positiveYnegative; VAS, Visual Analogue Scale; EMG (electromyography): moderateYsevere; Trigger finger development: yesYno.
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TABLE 3. Trigger Finger Distribution in Groups After Surgery Thumb Index finger Middle finger Ring finger Little finger Total
Group 1 (n = 79)
Group 2 (n = 80)
0 2 (15.4%) 3 (23.1%) 8 (61.5%) 0 45 (100%)
5 (15.6%) 6 (18.8%) 9 (28.1%) 10 (31.3%) 2 (6.3%)
is not coincidental. In the current study, trigger finger developed in 36 (22.6%) of 156 hands after carpal tunnel surgery. These results are in agreement with those of Hombal, Hayashi, and Harada et al. Hayashi et al showed that carpal tunnel surgery is a significant risk factor for the development of trigger finger and that mild or moderate severity of CTS accelerates the development of trigger finger. It was suggested that slippage of the tendon resulting from edema after surgery can cause changes within the carpal tunnel and the surrounding tissue. In the logistic regression analysis performed in the current study, the risk of trigger finger development in patients with mild and moderate EMG results was found to be significantly higher than that of patients with severe CTS. In a biomechanical study conducted by Robert et al,17 the effects of 5 different surgical techniques on combined tendon excursion have been investigated on cadavers. The combined tendon excursion comparison has been performed with measuring the intact wrist, endoscopic CTS release with single incision, endoscopic CTS release with double incision, conventional open CTS release, and after skin suture, respectively. As a result, 27.8% increase of combined tendon excursion was observed in CTS release with single incision, 29.7% in CTS release with double incision, and 43.4% in conventional open CTS release occurred when compared with measurements made before release. No significant excursion chance occurred after skin suture. In our study, only transverse carpal ligament (TCL) was released with mini-incision in group 1. In addition to mini-incision, distal forearm fascia had been released from 1 cm proximal to wrist f lexor crease in group 2. In our study, patients in group 1 demonstrate similarities with subjects in whom endoscopic methods were used to release cadaver wrist. On the other hand, patients in group 2 demonstrate similarities with subjects in whom standard open technique was used to release cadaver wrist. Robert et al17 reported a significantly increased tendon excursion in cadavers in whom standard open carpal tunnel release was performed. In our study, trigger finger rates were significantly higher in group 2 (in whom forearm fascia release was performed). Biomechanically, after the cutting of the TCL, the f lexor tendons of the wrist change location,17,18 and this change results in ‘‘strangulation’’, with the entrance angle of the f lexor tendon opposite the A1 pulley being increased thus causing an increase in pressure force and friction between the f lexor tendons and the A1 pulley.19,20 This increased force on the tendon-pulley surface causes
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deterioration in the nerve lubrication mechanism leading to trigger finger.21 Hombal reported that cutting the TCL causes a bowstring effect on the f lexor tendons that increases the load on the proximal pulleys; this outcome occurs particularly when the wrist is in f lexion during active movements of the fingers.16 In a cadaver study of TCL release alone and TCL together with distal forearm fascia release by Karalezli et al, it was reported that the additional release of the distal forearm fascia increased the entrance angle to the A1 pulley of the flexor tendons.22 These authors suggested that the increased friction in the A1 pulley of this angular increase may increase triggering. In previous studies, this angular increase has been reported most in the middle finger then in the ring finger, thumb, index finger, and small finger, respectively. In the current study, in the TCL and distal forearm fascia release patient group, the prevalence of the development of trigger finger was evaluated as in the ring finger, middle finger, index finger, thumb, and small finger, respectively. As a result, we believe that the relaxation of forearm fascia, which leads to increase in tendon excursion, is the most important etiologic factor in the development of trigger finger. Limitations of this presented study are the exclusion of patients with co-factor(s) that may take place in the etiology of CTS. During the preparation of this study, we generally focused on surgical procedure effect on the trigger finger development in patients with primary CTS, and patients with etiological factors predisposing them to CTS such as diabetes mellitus, acute trauma, rheumatoid arthritis, pregnancy, hypothyroidism, and hyperthyroidism were not included in the study. If these co-factors were reviewed and seen to predominate in one of the 2 study populations, they may represent the variable responsible for the association or development of the trigger fingers rather than the surgical technique. This data should have been included and dealt with through a multivariate regression. To the best of our knowledge, this is the first study that compared 2 different open surgery techniques; this approach can be considered a limitation, as there is a need for supporting studies. Another limitation is lack of imaging modalities. Imaging studies such as magnetic resonance imaging, which may be useful in explaining the etiology, were not included in this study. Therefore, future prospective biomechanical studies using imaging methods would be useful. In conclusion, open surgery techniques performed for CTS are influential in the development of postoperative trigger finger, and the procedure releasing both the TCL and distal forearm fascia increases this incidence compared to the release of TCL alone. There is a need for further studies to support this result and further explain the etiology.
REFERENCES 1. Adroshi I, Gummesson C, Johnsson R, et al. Prevalence of carpal tunnel syndrome in a general population. JAMA. 1999;282:153Y162. 2. Mondelli M, Giannini F, Giacchi M. Carpal tunnel syndrome incidence in a general population. Neurology. 2002;58:289Y294. 3. Ryzewicz M, Wolf JM. Trigger digits: principles, management, and complications. J Hand Surg Am. 2006;31:135Y146. 4. Conklin JE, White WL. Stenosing tenosynovitis and its possible relation to the carpal tunnel syndrome. Surg Clin North Am. 1960;40:531Y541. 5. Kumar P, Chakrabarti I. Idiopathic carpal tunnel syndrome and trigger finger: is there an association? J Hand Surg Eur. 2009;34:58Y59.
TABLE 4. Relative Risk Factors Age Gender EMG Surgical method
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Male Moderate Group 2
Odds Ratio
95% CI
P
0.957 2.705 2.950 3.651
0.910Y1.006 0.592Y12.361 1.105Y7.877 1.352Y9.858
0.086 0.199 0.031 0.011
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6. Assmus H. Carpal tunnel syndrome and stenosing tenosynovitis. Nervenarzt. 2000;71:474Y476. 7. Morita A, Tomita Y, Hirata H, et al. Association between stenosing tenosynovitis and carpal tunnel syndrome. J Jpn Soc Surg Hand. 2001;18:411Y413. 8. Morita A, Tomita Y, Hirata H, et al. Stenosing tenosynovitis in the patient with carpal tunnel syndrome. J Jpn Soc Surg Hand. 2003;20:716Y718. 9. Hayashi M, Uchiyama S, Toriumi H, et al. Carpal tunnel syndrome and development of trigger digit. J Clin Neurosci. 2005;12:39Y41.
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10. Harada K, Nakashima H, Teramoto K, et al. Trigger digits-associated carpal tunnel syndrome: relationship between carpal tunnel release and trigger digits. Hand Surg. 2005;10:205Y208. 11. King BA, Stern PJ, Kiefhaber TR. The incidence of trigger finger or de Quervain’s tendinitis after carpal tunnel release. J Hand Surg Eur. 2013;38:82Y83. 12. Rottgers SA, Lewis D, Wollstein RA. Concomitant presentation of carpal tunnel syndrome and trigger finger. J Brachial Plex Peripher Nerve Inj. 2009;4:13. 13. Kim JH, Gong HS, Lee HJ, et al. Pre- and post-operative comorbidities in idiopathic carpal tunnel syndrome: cervical arthritis, basal joint arthritis of the thumb, and trigger digit. J Hand Surg Eur. 2013;8:50Y56. 14. Goshtasby PH, Wheeler DR, Moy OJ. Risk factors for trigger finger occurrence after carpal tunnel release. Hand Surg. 2010;15:81Y87. 15. Phalen GS. The carpal tunnel syndrome: seventeen years experience in diagnosis and treatment of six hundred fifty-four hands. J Bone Joint Surg. 1966;48A:211Y228. 16. Hombal JWR, Owen R. Carpal tunnel decompression and trigger digits. Hand. 1970;2:192Y196.
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Triggering of Digits After Carpal Tunnel Surgery
17. Robert K, Brown MD, Clayton A, et al. Changes in digital flexor tendon mechanics after endoscopic and open carpal tunnel releases in cadaver wrists. J Hand Surg. 2000;25A:112Y119. 18. Netscher D, Mosharrafa A, Lee M, et al. Transverse carpal ligament: its effect on flexor tendon excursion, morphologic changes of the carpal canal, and on pinch and grip strengths after open carpal tunnel release. Plast Reconstr Surg. 1997;100:636Y642. 19. Doyle JR. Palmar and digital flexor tendon pulleys. Clin Orthop. 2001;383: 84Y96. 20. Uchiyama S, Coert JH, Berglund L, et al. Method for the measurement of friction between tendon and pulley. J Orthop Res. 1995;13:83Y89. 21. Uchiyama S, Amadio PC, Ishikawa J, et al. Boundary lubrication between the tendon and the pulley in the finger. J Bone Joint Surg Am. 1997;79:213Y218. 22. Karalezli N, Ku¨tahya H, Gu¨lec¸ A, et al. Transverse carpal ligament and forearm fascia release for the treatment of carpal tunnel syndrome change the entrance angle of flexor tendons to the A1 pulley: the relationship between carpal tunnel surgery and trigger finger occurrence. ScientificWorldJournal. 2013;630617.
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Triggering of the Digits After Carpal Tunnel Surgery Mehmet Ali Acar, MD,* Harun Ku¨tahya, MD,Þ Ali Gu¨lec¸, MD,* Mehmet Elmada?, MD,þ Nazım Karalezli, MD,§ and Tunc Cevat Ogun, MD|| Introduction: Carpal tunnel syndrome (CTS) and trigger finger may be seen simultaneously in the same hand. The development of trigger finger in patients undergoing CTS surgery is not rare, but the relationship between these conditions has not been fully established. The aims of this prospective randomized study were to investigate the incidence of trigger finger in patient groups undergoing transverse carpal ligament releasing (TCL) or TCL together with distal forearm fascia releasing and to identify other factors that may have an effect of these conditions. Materials and Method: This prospective randomized study evaluated 159 hands of 113 patients for whom CTS surgery was planned. The patients were separated into 2 groups: group 1 (79 hands of 57 patients) undergoing TCL releasing only and group 2 (80 hands of 56 patients) undergoing TCL and distal forearm fascia releasing together. The age and gender of the patients, dominant hand, physical examination findings, visual analogue scale (VAS), and electromyography (EMG) results were recorded. Follow-up examinations were made at 1, 3, 6, 12, and 24 months for all patients. We noted development of trigger finger in the surgical groups, and its location and response to treatment. Results: The incidence of trigger finger development was statistically significantly different between group 1 and group 2 (13.9% and 31.3%, respectively). The logistic regression analysis of factors affecting the development of trigger finger posttreatment found that the surgical method and severity of EMG were significant, whereas the effects of the other factors studied were not found to have any statistical significance. Conclusion: There was an increased risk of postoperative trigger finger development in patients undergoing TCL and distal forearm fascia releasing surgery for CTS compared to those undergoing CTL only. There is a need for further studies to support this result and further explain the etiology. Key Words: carpal tunnel syndrome, trigger finger, transverse carpal ligament, forearm facia, carpal tunnel surgery (Ann Plast Surg 2015;75: 393Y397)
C
arpal tunnel syndrome (CTS), which is one of the most important causes of pain, neurological findings, and functional restriction in the hand, is the most frequently encountered entrapment neuropathy with a prevalence of 2.7% in the general population.1 Although conservative treatments exist, the majority of patients require surgical release of the carpal tunnel.2 Trigger finger is a stenosing tenosynovitis that is generally characterized by pain, swelling, restricted finger movement, and painful locking of the finger.3 Just as trigger finger and CTS may be seen simultaneously in the same hand, trigger finger may develop after CTS surgery.4Y14 Received January 2, 2014, and accepted for publication, after revision, March 22, 2014. From the *Department of Orthopedics and Traumatology, Medical School of Selcuk University. Konya; †Department of Orthopedics and Traumatology, Beyhekim State Hospital, Konya; ‡Department of Orthopedics and Traumatology, BezmiAlem Foundation University, Istanbul; §Department of Orthopedics and Traumatology, N.E. University Meram School of Medicine, Konya; and ||Department of Orthopedics and Traumatology, Medicana Konya Hospital. Konya, Turkey. Conflicts of interest and sources of funding: none declared. Reprints: Mehmet Ali Acar, MD, Department of Orthopedics and Traumatology, Medical School of Selcuk University, Konya, Turkey. E-mail: mehmetaliacar@ selcuk.edu.tr. Copyright * 2014 Wolters Kluwer Health, Inc. All rights reserved. ISSN: 0148-7043/15/7504-0393 DOI: 10.1097/SAP.0000000000000233
Annals of Plastic Surgery
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The development of trigger finger after carpal tunnel surgery has been reported by several researchers.9Y11,13,14 Differences in trigger finger development between endoscopic surgery and open surgical methods have also been previously studied. In a study by Harada et al,10 in which endoscopic methods and mini open methods were performed in a total of 875 patients, it was reported that 101 (11.5%) patients required trigger finger release surgery after CTS surgery. Those authors found that the choice of endoscopic or open surgery methods had no effect on the rate of trigger finger development. In both endoscopic and mini open surgery, a release was performed only on the transverse carpal ligament (TCL). In the standard open surgical method, the TCL is released together with the distal forearm fascia. We noted that no study has been conducted to date examining the incidence of trigger finger development in 2 differing techniques of the open carpal tunnel release. The primary aim of the present prospective study was to compare the rates of trigger finger development in patients treated with 2 variations of the open carpal tunnel release surgery, one with and one without forearm antebrachial fascia division.
PATIENTS AND METHODS The study included patients who were recommended for surgery for idiopathic CTS and were followed up at our clinic. Study approval was granted by the Local Ethics Committee, and informed consent was obtained from each patient. The criteria for surgical release of the carpal tunnel included symptoms severe enough to wake the patient at night and impede daily living activities, physical examinations (Phalen and Tinel tests), and electromyography (EMG) results supporting CTS. Patients with etiological factors predisposing them to CTS such as diabetes mellitus, acute trauma, rheumatoid arthritis, pregnancy, hypothyroidism, and hyperthyroidism were not included in the study. Patients who had trigger finger in preoperative physical examination, who had a history of operation and/or injection history because of trigger finger, and who had been detected to have pain or nodularity on A1 pulley were excluded from the study. We planned a follow-up period of at least 24 months, with removal of patients who did not complete the follow-up from the study results. All surgical procedures were performed by the same surgeon. The patients were randomized into 2 groups using a computer-generated randomization table. Patients with bilateral CTS were operated on in different sessions. Group 1 underwent TCL releasing alone, whereas group 2 had both TCL and distal forearm fascia releasing.
Surgical Technique Group 1: With the hand in supination under tourniquet control and the wrist in 15-degree extension, at the junction point of the long axis of the third web and the Kaplan line, a 2-cm incision 2 mm ulnar to the thenar line was made proximally. After passing subcutaneously without damaging the palmar sensory branch of the median nerve, the proximal and distal portions of the TCL were released while protecting the median nerve along the ulnar edge of the TCL (Fig. 1). Primary skin suturing was performed. A compressive bandage was applied; after 15 minutes, it was loosened and re-applied. Group 2: After releasing the TCL, while protecting the median nerve, the proximal portion of the distal forearm fascia was released (1 cm) by advancing scissors under the skin (Fig. 2). www.annalsplasticsurgery.com
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Statistical analysis of the data obtained in the study was made using SPSS 16 software program. Crosstabs W2 and Fisher exact chisquare test were used to evaluate the categorized and ordinal scale parameters and the group comparisons. To determine which parameters had affected the development of trigger finger, logistic regression analysis was used. Descriptive characteristics such as patient age, gender, and dominant side were evaluated with descriptive statistical tests (frequencies, descriptives).
RESULTS
FIGURE 1. Surgical method for carpal tunnel release in group 1 (transverse carpal ligament release only).
Postoperative protocol: After the surgery, all patient groups were applied a large bulky dressing to restrict wrist range of motion in the early postoperative period. The bulky dressings were removed 2 days after the surgery. The patients were instructed in range of motion exercises for finger, wrist, and arm. The sutures were removed 10 to 12 days after surgery. Four weeks after surgery, patients were permitted to return daily life with weight restriction, and 6 to 8 weeks after surgery, they were permitted for full activity. The preoperative demographic data of the patients, pain scores, and CTS severity were recorded. Pain scores were evaluated by Visual Analogue Scale (VAS, 0Y10), and the severity of CTS was classified as mild, moderate, or severe according to the sensory conduction rate in EMG and motor distal latency distance. 1. MildVslow orthodromic sensory conduction rate (G44 m/s) and normal motor distal latency. 2. ModerateVslow sensory conduction rate (G44 m/s) and motor distal latency extending from more than 4.4 ms. 3. SevereVextended or loss of motor distal latency and potential loss of sensory nerve axon.
The demographic data of the patients and the preoperative physical examination results, VAS scores, and EMG values are shown in Table 1.The results of the 24-month postoperative physical examination (Phalen, Tinel), VAS scores, relief of nighttime paresthesia complaints, EMG changes, development of trigger finger, and P values are shown in Table 2. Trigger finger had occurred during follow-up in 34 cases (bilaterally in 2 cases) in total of 113 patients who underwent surgery. Considering the 159 hands operated, 36 had developed trigger finger. Although 25 (31.3%) of the 80 hands in group 2 had developed trigger finger, 11 (13.9%) of the 79 hands in group 1 developed trigger finger postoperatively. Trigger finger development was significantly higher in group 2 than the group 1 (P = 0.007). Although 11 hands demonstrated single trigger finger development, 2 fingers’ involvement were detected in one hand after surgery in group 1. Sixteen hands revealed single trigger finger development and 2 digits involvement were detected in 8 hands postoperatively in group 2. Eventually, a total of 45 fingers in 36 hands developed trigger finger after surgery. The distribution of trigger finger localizations are given in Table 3. In the logistic regression analysis of patients who developed postoperative trigger finger, the parameters thought to affect the development of trigger finger (age, gender, surgical method, EMG results) were examined in the same model. Although the surgical method and EMG results were found to be statistically significant in the model (P G 0.05), age and gender had no statistically significant effect on the development of trigger finger (P 9 0.05). Their relative risks with 95% confidence intervals are listed in Table 4. No significant difference was found between the 2 surgical groups in terms of time to trigger finger development during follow-up and response to treatment. Trigger finger developed in 36 (22.6%) hands of 34 patients at a mean 5.1 months (range, 3Y6 months) after CT
As the number of hands in the mild group was low, these patients were included in the moderate group for further analysis. At the postoperative 1st, 3rd, 6th, 12th, and 24th month, the presence of trigger finger and its location and pain scores were recorded for all patients. Those patients with sensitivity and/or nodules over the metacarpophalangeal joint, restricted finger movements, or finger locking were considered to be positive for trigger finger. The groups were compared according to the physical examination findings at 24-month follow-up with respect to VAS, EMG, and trigger finger development. For patients who developed trigger finger, conservative treatment was used initially, consisting of non-steroidal antiinf lammatory medication, splinting, and steroid injections. In cases in which the patient had no response to conservative treatment, open surgical release of the first annular pulley (A1) was done.6
Statistical Analysis Power analysis was performed and a N of 51 has power of 80% to detect an effect size of operation technique used in group 1 or group 2. PASS 2013 (Power Analysis and Sample Size) statistical software program was used for the sample size determination. 394
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FIGURE 2. Surgical method for carpal tunnel release in group 2 (transverse carpal ligament and forearm fascia release). * 2014 Wolters Kluwer Health, Inc. All rights reserved.
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Triggering of Digits After Carpal Tunnel Surgery
TABLE 1. The Demographic Characteristics of 2 Group Patients Parameters
Total
Total hands Age (mean, range) Gender (F/M) Night-time paresthesia (Y/N) Duration, mo DominantYnon-dominant hands Right side/left side/bilateral side Phalen +/j Tinel +/j VAS EMG
159 52.87 T 8.58 (31Y77) 148/11 156/3 30.27 T 25.19 153/6 29/38/92 129/30 48/111 6.83 T 2.49 53/106
Group 2
P
80 52.53 T 10.04 (31Y77) 90%/10% (72/8) 100%/0.00% (80/0) 23.52 T 18.05 98.8%/1.2% (79/1) 11.4%/17.7%/70.9% (9/14/56) 77.5%/22.5% (62/18) 32.5%/67.5% (26/54) 6.52 T 2.70 33.8%/66.2% (27/53)
0.618 0.109 0.120 0.001* 0.180 0.004* 0.165 0.321 0.120 0.522
Group 1 79 53.22 T 7.13 (34Y75) 96.2%/3.8% (76/3) 92.2%/3.8% (76/3) 37.12 T 29.34 94.9%/5.1% (74/5) 25%/30%/45% (20/24/36) 84.8%/15.2% (67/12) 27.8%/72.2% (22/57) 7.13 T 2.23 32.9%/67.1% (26/53)
*P G 0.05 is statistically significant. Gender: femaleYmale; Phalen/Tinel: positiveYnegative; VAS, Visual Analogue Scale; EMG (electromyography): moderateYsevere.
release. In the follow-up of these patients, 9 (25%) hands recovered spontaneously at a mean 2.6 months later, 4 (11.1%) hands recovered at a mean 4.2 months with conservative treatment, and 10 (27.8%) hands completely recovered at a mean 2.1 months after steroid injections (pain and locking was resolved). In 4 (11.1%) hands that were treated conservatively and 3 (8.3%) hands that had received a steroid injection, the pain was relieved and the locking receded to a level that was not uncomfortable. In 6 hands, pain and locking were not resolved despite steroid injection, and trigger finger surgery was performed at a mean 6.1 months later. The rate of trigger finger releasing following CT release was 16.7%.
DISCUSSION The results of this study showed that, in the patient group that underwent distal forearm fascia with TCL release compared to the group who had TCL release alone, the incidence of development of trigger finger was significantly increased. A common pathogenesis and relationship between CTS and trigger finger has been debated by many authors.4,8Y10,14Y16 In a prospective study by Kumar et al to determine any relationship between idiopathic CTS and trigger finger, patients presenting with both CTS and trigger finger were compared to those presenting with CTS alone. The results showed that of 551 patients, 211 had at least one trigger finger, and of the 211 patients with trigger finger, 91 (43%) had CTS. The data supported a correlation between idiopathic CTS and idiopathic trigger finger and a common pathophysiological factor. Hayashi et al9 reported that trigger finger developed postoperatively in 52 of 64 hands operated on for CTS and that trigger finger also developed in 9 of 101 hands treated conservatively after a 1-year follow-up period.
In a retrospective review by Kim et al13 of 633 hands in 362 patients who underwent carpal tunnel release for idiopathic carpal tunnel syndrome, cervical arthritis was found in 253 patients (70%) with C5 to C6 arthritis as the most common site. Basal joint arthritis of the thumb was observed in 216 (34%) of the 633 hands. Preoperative trigger finger or de Quervain (DQ) disease was observed in 85 of the 633 hands (13%), and these disorders developed in 67 hands (11%) postoperatively. Patient education about cervical arthritis, basal joint arthritis, and trigger digit is very important, as these disorders commonly coexist with idiopathic carpal tunnel syndrome. In a study by King et al, trigger finger was observed at a rate of 6.6% in the hand that had undergone CT release, compared with 3.5% for the untreated contralateral hand. The most common location of trigger finger after CT release was the thumb. The prevalence of trigger finger in the little finger was equal between the groups, and trigger finger in the other digits was observed more often in the untreated hand. The dominant hand was more likely to be affected when trigger finger developed after CT release. The incidence of DQ in the hand that had undergone CT release was 0.5%, compared with 0.8% for the untreated contralateral hand. No significant correlations were found between trigger finger or DQ and other conditions. In a retrospective chart review by Goshtasby et al,14 792 CT release procedures and multiple variables were compared in patients who did and did not develop trigger finger after CT release. The incidence of new-onset trigger finger after CT release was 6.3%. Multivariate regression analysis showed that osteoarthritis and undergoing an endoscopic procedure were the only 2 independent risk factors. Thus, it was recommended that patients should be made aware of the potential sequelae of trigger finger before an endoscopic procedure for CT release. In studies by Hombal, Hayashi, and Harada et al, it was suggested the development of trigger finger after carpal tunnel release
TABLE 2. Characteristics of Patients After the Surgery Parameters Phalen +/j Tinel +/j VAS Night-time paresthesia (Y/N) EMG Trigger finger development (Y/N)
Total
Group 1
Group 2
P
28/131 18/141 1.12 T 2.23 0/159 152/7 36/123
16.5%/83.5% (13/66) 10.1%/89.9% (8/71) 1.00 T 2.09 0%/100% (0/79) 94.9%/5.1% (75/4) 13.9%/86.1% (11/68)
18.8%/81.2% (15/65) 12.5%/87.5% (10/70) 1.26 T 2.38 100%/0.00% (80/0) 96.2%/4.8% (77/3) 31.3%/66.8% (25/55)
0.432 0.413 0.538 0.107 0.458 0.007
Phalen/Tinel: positiveYnegative; VAS, Visual Analogue Scale; EMG (electromyography): moderateYsevere; Trigger finger development: yesYno.
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TABLE 3. Trigger Finger Distribution in Groups After Surgery Thumb Index finger Middle finger Ring finger Little finger Total
Group 1 (n = 79)
Group 2 (n = 80)
0 2 (15.4%) 3 (23.1%) 8 (61.5%) 0 45 (100%)
5 (15.6%) 6 (18.8%) 9 (28.1%) 10 (31.3%) 2 (6.3%)
is not coincidental. In the current study, trigger finger developed in 36 (22.6%) of 156 hands after carpal tunnel surgery. These results are in agreement with those of Hombal, Hayashi, and Harada et al. Hayashi et al showed that carpal tunnel surgery is a significant risk factor for the development of trigger finger and that mild or moderate severity of CTS accelerates the development of trigger finger. It was suggested that slippage of the tendon resulting from edema after surgery can cause changes within the carpal tunnel and the surrounding tissue. In the logistic regression analysis performed in the current study, the risk of trigger finger development in patients with mild and moderate EMG results was found to be significantly higher than that of patients with severe CTS. In a biomechanical study conducted by Robert et al,17 the effects of 5 different surgical techniques on combined tendon excursion have been investigated on cadavers. The combined tendon excursion comparison has been performed with measuring the intact wrist, endoscopic CTS release with single incision, endoscopic CTS release with double incision, conventional open CTS release, and after skin suture, respectively. As a result, 27.8% increase of combined tendon excursion was observed in CTS release with single incision, 29.7% in CTS release with double incision, and 43.4% in conventional open CTS release occurred when compared with measurements made before release. No significant excursion chance occurred after skin suture. In our study, only transverse carpal ligament (TCL) was released with mini-incision in group 1. In addition to mini-incision, distal forearm fascia had been released from 1 cm proximal to wrist f lexor crease in group 2. In our study, patients in group 1 demonstrate similarities with subjects in whom endoscopic methods were used to release cadaver wrist. On the other hand, patients in group 2 demonstrate similarities with subjects in whom standard open technique was used to release cadaver wrist. Robert et al17 reported a significantly increased tendon excursion in cadavers in whom standard open carpal tunnel release was performed. In our study, trigger finger rates were significantly higher in group 2 (in whom forearm fascia release was performed). Biomechanically, after the cutting of the TCL, the f lexor tendons of the wrist change location,17,18 and this change results in ‘‘strangulation’’, with the entrance angle of the f lexor tendon opposite the A1 pulley being increased thus causing an increase in pressure force and friction between the f lexor tendons and the A1 pulley.19,20 This increased force on the tendon-pulley surface causes
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deterioration in the nerve lubrication mechanism leading to trigger finger.21 Hombal reported that cutting the TCL causes a bowstring effect on the f lexor tendons that increases the load on the proximal pulleys; this outcome occurs particularly when the wrist is in f lexion during active movements of the fingers.16 In a cadaver study of TCL release alone and TCL together with distal forearm fascia release by Karalezli et al, it was reported that the additional release of the distal forearm fascia increased the entrance angle to the A1 pulley of the flexor tendons.22 These authors suggested that the increased friction in the A1 pulley of this angular increase may increase triggering. In previous studies, this angular increase has been reported most in the middle finger then in the ring finger, thumb, index finger, and small finger, respectively. In the current study, in the TCL and distal forearm fascia release patient group, the prevalence of the development of trigger finger was evaluated as in the ring finger, middle finger, index finger, thumb, and small finger, respectively. As a result, we believe that the relaxation of forearm fascia, which leads to increase in tendon excursion, is the most important etiologic factor in the development of trigger finger. Limitations of this presented study are the exclusion of patients with co-factor(s) that may take place in the etiology of CTS. During the preparation of this study, we generally focused on surgical procedure effect on the trigger finger development in patients with primary CTS, and patients with etiological factors predisposing them to CTS such as diabetes mellitus, acute trauma, rheumatoid arthritis, pregnancy, hypothyroidism, and hyperthyroidism were not included in the study. If these co-factors were reviewed and seen to predominate in one of the 2 study populations, they may represent the variable responsible for the association or development of the trigger fingers rather than the surgical technique. This data should have been included and dealt with through a multivariate regression. To the best of our knowledge, this is the first study that compared 2 different open surgery techniques; this approach can be considered a limitation, as there is a need for supporting studies. Another limitation is lack of imaging modalities. Imaging studies such as magnetic resonance imaging, which may be useful in explaining the etiology, were not included in this study. Therefore, future prospective biomechanical studies using imaging methods would be useful. In conclusion, open surgery techniques performed for CTS are influential in the development of postoperative trigger finger, and the procedure releasing both the TCL and distal forearm fascia increases this incidence compared to the release of TCL alone. There is a need for further studies to support this result and further explain the etiology.
REFERENCES 1. Adroshi I, Gummesson C, Johnsson R, et al. Prevalence of carpal tunnel syndrome in a general population. JAMA. 1999;282:153Y162. 2. Mondelli M, Giannini F, Giacchi M. Carpal tunnel syndrome incidence in a general population. Neurology. 2002;58:289Y294. 3. Ryzewicz M, Wolf JM. Trigger digits: principles, management, and complications. J Hand Surg Am. 2006;31:135Y146. 4. Conklin JE, White WL. Stenosing tenosynovitis and its possible relation to the carpal tunnel syndrome. Surg Clin North Am. 1960;40:531Y541. 5. Kumar P, Chakrabarti I. Idiopathic carpal tunnel syndrome and trigger finger: is there an association? J Hand Surg Eur. 2009;34:58Y59.
TABLE 4. Relative Risk Factors Age Gender EMG Surgical method
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Male Moderate Group 2
Odds Ratio
95% CI
P
0.957 2.705 2.950 3.651
0.910Y1.006 0.592Y12.361 1.105Y7.877 1.352Y9.858
0.086 0.199 0.031 0.011
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6. Assmus H. Carpal tunnel syndrome and stenosing tenosynovitis. Nervenarzt. 2000;71:474Y476. 7. Morita A, Tomita Y, Hirata H, et al. Association between stenosing tenosynovitis and carpal tunnel syndrome. J Jpn Soc Surg Hand. 2001;18:411Y413. 8. Morita A, Tomita Y, Hirata H, et al. Stenosing tenosynovitis in the patient with carpal tunnel syndrome. J Jpn Soc Surg Hand. 2003;20:716Y718. 9. Hayashi M, Uchiyama S, Toriumi H, et al. Carpal tunnel syndrome and development of trigger digit. J Clin Neurosci. 2005;12:39Y41.
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10. Harada K, Nakashima H, Teramoto K, et al. Trigger digits-associated carpal tunnel syndrome: relationship between carpal tunnel release and trigger digits. Hand Surg. 2005;10:205Y208. 11. King BA, Stern PJ, Kiefhaber TR. The incidence of trigger finger or de Quervain’s tendinitis after carpal tunnel release. J Hand Surg Eur. 2013;38:82Y83. 12. Rottgers SA, Lewis D, Wollstein RA. Concomitant presentation of carpal tunnel syndrome and trigger finger. J Brachial Plex Peripher Nerve Inj. 2009;4:13. 13. Kim JH, Gong HS, Lee HJ, et al. Pre- and post-operative comorbidities in idiopathic carpal tunnel syndrome: cervical arthritis, basal joint arthritis of the thumb, and trigger digit. J Hand Surg Eur. 2013;8:50Y56. 14. Goshtasby PH, Wheeler DR, Moy OJ. Risk factors for trigger finger occurrence after carpal tunnel release. Hand Surg. 2010;15:81Y87. 15. Phalen GS. The carpal tunnel syndrome: seventeen years experience in diagnosis and treatment of six hundred fifty-four hands. J Bone Joint Surg. 1966;48A:211Y228. 16. Hombal JWR, Owen R. Carpal tunnel decompression and trigger digits. Hand. 1970;2:192Y196.
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Triggering of Digits After Carpal Tunnel Surgery
17. Robert K, Brown MD, Clayton A, et al. Changes in digital flexor tendon mechanics after endoscopic and open carpal tunnel releases in cadaver wrists. J Hand Surg. 2000;25A:112Y119. 18. Netscher D, Mosharrafa A, Lee M, et al. Transverse carpal ligament: its effect on flexor tendon excursion, morphologic changes of the carpal canal, and on pinch and grip strengths after open carpal tunnel release. Plast Reconstr Surg. 1997;100:636Y642. 19. Doyle JR. Palmar and digital flexor tendon pulleys. Clin Orthop. 2001;383: 84Y96. 20. Uchiyama S, Coert JH, Berglund L, et al. Method for the measurement of friction between tendon and pulley. J Orthop Res. 1995;13:83Y89. 21. Uchiyama S, Amadio PC, Ishikawa J, et al. Boundary lubrication between the tendon and the pulley in the finger. J Bone Joint Surg Am. 1997;79:213Y218. 22. Karalezli N, Ku¨tahya H, Gu¨lec¸ A, et al. Transverse carpal ligament and forearm fascia release for the treatment of carpal tunnel syndrome change the entrance angle of flexor tendons to the A1 pulley: the relationship between carpal tunnel surgery and trigger finger occurrence. ScientificWorldJournal. 2013;630617.
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