High-resolution ultrasound analysis of subsynovial connective tissue in human cadaver carpal tunnel.

The carpal tunnel contains the median nerve, nine flexor tendons, two synovial bursae, and peritendinous subsynovial connective tissue (SSCT). Fibrosis of the SSCT is the most consistent pathological finding in patients with carpal tunnel syndrome. We investigated the anatomy and gliding characteristics of the flexor digitorum superficialis tendon and its adjacent SSCT with high-resolution ultrasound (15 MHz). Our hypotheses were that tendon and SSCT are distinguishable by ultrasound and that their velocities during tendon excursion are different. Qualitative ultrasound analysis of a flexor tendon and its SSCT was performed on five cadaver wrists and correlated to respective findings after anatomical study of the same cadavers. Quantitative Doppler velocity analysis of eight cadaver wrists was done to assess the sliding movement of the tendon and its SSCT within the carpal tunnel. No significant difference was found between the thickness of SSCT measured by ultrasound and that measured directly after dissection. The SSCT moved slower than its flexor tendon. The SSCT velocities were statistically different from the tendon velocities (t-test, p>0.001). High-resolution ultrasound is a very precise method to display the anatomy of the tendon and SSCT within the carpal tunnel, and their different velocities can be detected with Doppler. Noninvasive assessment of the thickness and velocity of the tenosynovium in carpal tunnel syndrome by high-resolution sonography might be a new diagnostic tool for disorders affecting the SSCT, especially carpal tunnel syndrome.     

腕管综合征内窥镜手术预防正中神经损伤的临床研究

目的 介绍腕管综合征内窥镜手术(endoscopic carpal tunnel release,ECTR)预防正中神经损伤并发症的方法.方法 利用彩色多普勒超声仪(B超)对37例74手患者术前进行检测.结果 71例正中神经走行在桡侧腕屈肌腱与掌长肌腱之间,3例走行在掌长肌腱与尺侧腕屈肌腱之间,并术中确认.结论 正中神经变异走行在掌长肌腱与尺侧腕屈肌腱之间是ECTR的禁忌证,B超能准确定位正中神经与掌长肌腱关系,避免内窥镜手术损伤正中神经,更具有简单、经济、方便可靠等优点.

Abstract：

Objective To introduce a method of preventing median never injury during endoscopic carpal tunnel release (ECTR). Methods Ultrasonography of both wrists was done to 37 patients of carpal tunnel syndrome who were going to undergo open release of the transverse carpal ligament. Structures in the carpal tunnel were visualized to guide surgical decision-making. Results Ultrasonography showed that median never lies between the tendon of flexor carpi radialis and palmaris longus in 71 patients and lies between the tendon of palmaris longus and flexor carpi ulnaris in 3 patients. These findings were confirmed during the surgeries. Conclusion It is a contraindication of ECTR if median never lies between palmaris longus and flexor carpi ulnaris. Ultrasonography can accurately reveal the relative position of median never to the palmaris longus tendon. Pre-operative ultrasonography of the wrist is a simple, inexpensive and convenient method to exclude these contraindications and thus prevent median never injuries in ECTR.     

A potential complication of endoscopic carpal tunnel release.

Complications of carpal tunnel release have been well documented in the literature. Recently, a procedure for endoscopic release of the transverse carpal ligament has been described. This case report demonstrates a potential complication of endoscopic carpal tunnel release, in which the flexor digitorum superficialis tendon to the ring finger was nearly cut when the arthroscopic trocar passed beneath it. The procedure was converted to an open carpal tunnel release when the transverse fibers of the carpal ligament were not seen after several passes of the trocar. This complication was related to the inability to fully extend the wrist and metacarpophalangeal joints because of arthritic contractures. This case underscores the need for accurate identification of endoscopic anatomy prior to release of the carpal tunnel. The surgeon should not hesitate to convert to open technique if it becomes necessary.     

Failed endoscopic carpal tunnel release. Operative findings and results of open revision surgery.

From 1994 to 1997, 22 patients (24 wrists) underwent open revision carpal tunnel release for persistent carpal tunnel syndrome after a primary endoscopic release. The age range was from 21 to 77 years. At the time of revision surgery, 22 wrists had an incomplete release of the flexor retinaculum and two patients had median nerve transection (one partial and one complete). One patient had release of Guyon's canal and not the carpal tunnel. After the open revision carpal tunnel release, 20 patients returned to work with five patients returning to jobs of lighter duty. In addition, these 20 patients had significant improvement in symptoms. The remaining two patients had sustained a median nerve injury and did not return to work. One of these patients developed a painful neuroma in continuity of the median nerve which required vein wrapping with a saphenous vein graft. This study indicates that endoscopic release of the flexor retinaculum holds the same risks and complications as open release. Based on our study we believe that patients with persistent carpal tunnel syndrome after failed endoscopic flexor retinaculum release can be successfully treated with open release.     

The effect of displacement on the mechanical properties of human cadaver subsynovial connective tissue

The subsynovial connective tissue (SSCT) in the carpal tunnel may participate in the origin of carpal tunnel syndrome (CTS), yet material properties of the SSCT have not been well‐characterized. We investigated the response of the SSCT to repeated ramp stretch tests. Eight human cadaver wrists were used. The physiological excursion of the flexor digitorum superficialis of the third digit (FDS 3) was measured, starting from a neutral position to maximal flexion of the metacarpophalangeal and proximal interphalangeal joints. The FDS 3 tendon was pulled to 40%, 60%, 90%, and 120% of the physiological excursion. Two “ramp stretch” cycles were performed at every excursion level, except for 120% of excursion, where three cycles were performed. The ratio of energy absorbed between the second (E2) and first (E1) ramp stretch was 0.94 (SD = 0.07) for 60%, 0.84 (SD = 0.11) for 90%, and 0.68 (SD = 0.11) for 120% of the physiological excursion. A significant decrease occurred in energy absorbed after the first ramp stretch cycle at 90% and 120% of the physiological excursion, which was not seen at 60%. Our data are consistent with a stepwise damage occurring in the SSCT. Furthermore, the damage seems to initiate within the physiological range of tendon excursion. This finding may be important in understanding the pathophysiology of conditions that are associated with SSCT pathology, such as carpal tunnel syndrome. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1732–1737, 2012     

The role of flexor tenosynovectomy in the operative treatment of carpal tunnel syndrome

BACKGROUND: We conducted a prospective, randomized study to evaluate the effect of flexor tenosynovectomy as an adjunct to open carpal tunnel release for the treatment of idiopathic carpal tunnel syndrome and reviewed the histological characteristics of the flexor tenosynovium to identify possible correlations between histopathology and symptoms. METHODS: Eighty-eight wrists in eighty-seven patients with idiopathic carpal tunnel syndrome were randomized to open carpal tunnel release with or without flexor tenosynovectomy. A validated self-administered questionnaire for the assessment of symptom severity and functional status was completed both before and after the operation to assess patient outcome. The study group included fifteen men and seventy-two women with a mean age of fifty-eight years. All patients were followed for a minimum of twelve months after the operation. Intraoperatively, the tenosynovium of all patients was graded on the basis of its gross appearance. Half of the wrists were then treated with a flexor tenosynovectomy through the operative incision, and the tenosynovium was graded histologically. Correlations were sought between the gross appearance of the tenosynovium and the preoperative and postoperative symptoms and functional status, between the histologic appearance of the tenosynovium and the preoperative and postoperative symptoms and functional status, and between the gross and the histologic findings. RESULTS: After the operation, both groups improved significantly with respect to symptom severity and functional status (paired t test), with no significant difference between the groups (unpaired t test). No significant correlation was found between the gross appearance of the tenosynovium and the preoperative or postoperative symptoms and functional status, between the histologic appearance of the tenosynovium and the preoperative or postoperative symptoms and functional status, or between the gross and the histologic findings. CONCLUSIONS: We observed neither an added benefit nor an increased rate of morbidity in association with the performance of a flexor tenosynovectomy at the time of carpal tunnel release. We identified no clinical correlations that might predict which individuals would benefit from flexor tenosynovectomy on the basis of either the gross (intraoperative) or histologic evaluation of the flexor tenosynovium. Our findings suggest that routine flexor tenosynovectomy offers no benefit compared with sectioning of the transverse carpal ligament alone for the treatment of idiopathic carpal tunnel syndrome.     

Snapping wrist after surgery for carpal tunnel syndrome and trigger digit: a case report

We present a case of snapping dislocation of the flexor digitorum superficialis tendon to the small finger over the hook of the hamate that was noted after carpal tunnel release and trigger digit release.     

Gliding resistance of flexor tendon associated with carpal tunnel pressure: A biomechanical cadaver study

The purpose of this study was to investigate the effect of carpal tunnel pressure on the gliding characteristics of flexor tendons within the carpal tunnel. Eight fresh human cadaver wrists and hands were used. A balloon was inserted into the carpal tunnel to elevate the pressure. The mean gliding resistance of the middle finger flexor digitorum superficialis tendon was measured with the following six conditions: (1) as a baseline, before balloon insertion; (2) balloon with 0 mmHg pressure; (3) 30 mmHg; (4) 60 mmHg; (5) 90 mmHg; (6) 120 mmHg. The gliding resistance of flexor tendon gradually increased as the carpal tunnel pressure was elevated. At pressures above 60 mmHg, the increase in gliding resistance became significant compared to the baseline condition. This study helps us to understand the relationship between carpal tunnel pressure, which is elevated in the patient with carpal tunnel syndrome (CTS) and tendon gliding resistance, which is a component of the work of flexion. These findings suggest that patients with CTS may have to expend more energy to accomplish specific motions, which may in turn affect symptoms of hand pain, weakness and fatigue, seen commonly in such patients. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:58–61, 2011     

The effect of tendon excursion velocity on longitudinal median nerve displacement: Differences between carpal tunnel syndrome patients and controls

The subsynovial connective tissue (SSCT) is a viscoelastic structure connecting the median nerve (MN) and the flexor tendons in the carpal tunnel. Increased strain rates increases stiffness in viscoelastic tissues, and thereby its capacity to transfer shear load. Therefore, tendon excursion velocity may impact the MN displacement. In carpal tunnel syndrome (CTS) the SSCT is fibrotic and may be ruptured, and this may affect MN motion. In this study, ultrasonography was performed on 14 wrists of healthy controls and 25 wrists of CTS patients during controlled finger motions performed at three different velocities. Longitudinal MN and tendon excursion were assessed using a custom speckle tracking algorithm and compared across the three different velocities. CTS patients exhibited significantly less MN motion than controls (p ≤ 0.002). While in general, MN displacement increased with increasing tendon excursion velocity (p ≤ 0.031). These findings are consistent with current knowledge of SSCT mechanics in CTS, in which in some patients the fibrotic SSCT appears to have ruptured from the tendon surface. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:483–487, 2015.     

内镜在腕管综合征治疗中的应用选择

目的探讨内镜治疗腕管综合征（carpal tunnel syndrome,CTS）的病例选择。方法2004年7月～2007年9月,用内镜技术治疗21例（24腕）CTS。手术在局麻下进行,距腕横纹近侧3cm处掌长肌腱尺侧横切口1cm,前臂筋膜深层分离将专用外套管置入腕管,在内镜监视下用专用钩刀切断腕横韧带。术后1、2、3、5个月随访。结果术后5个月时按Kelly法疗效评级：优11例;良6例;一般2例（3腕）;差2例。其中疗效差1例于内镜术后7个月行传统开放手术神经干束间松解而缓解,1例存在明显的手指皮肤痛觉过敏并皮肤干燥等交感神经症状而继续保守治疗。结论按如下原则选择内镜处理或开放手术治疗CTS：①特发性病例内镜处理;继发性病例开放手术,如类风湿关节炎所致的滑膜增生肿胀,腕内骨折后畸形,腕管内肿瘤、囊肿、炎症、痛风,神经干自身病变等。②拇指对掌功能有障碍及晚期CTS选择开放手术。③老年患者（〉60岁）优先考虑开放手术;年轻、有较高职业和外观要求的患者可以优先考虑内镜治疗。     

Relationship of carpal canal contents volume to carpal canal pressure in carpal tunnel syndrome patients

Forty patients long-term haemodialysis with a second recurrence of carpal tunnel syndrome and concomitant loss of flexor tendon function due to flexor adhesions were treated by excision of the flexor digitorum superficialis tendons. During the procedure the carpal canal pressure was measured using a continuous infusion technique. The preoperative mean carpal canal pressure was 81 (SD, 53)mmHg. After removal of all the flexor digitorum superficialis tendons, the carpal canal pressure decreased to 10 (SD, 8)mmHg. The clinical symptoms of carpal tunnel syndrome were relieved and hand strength and finger motion were improved in all patients.     

Flexor superficialis abductor transfer with carpal tunnel release for thenar palsy

PURPOSE: In patients with advanced chronic carpal tunnel syndrome (CTS) the ability of the thumb to abduct and perform functional opposition is impaired greatly, primarily because of denervation and paralysis of the abductor pollicis brevis muscle. The purpose of this study was to evaluate the results of transfer of the flexor digitorum superficialis to the abductor pollicis brevis for restoration of thumb abduction in thenar paralysis caused by advanced chronic CTS. METHODS: Fifty patients (51 hands) with advanced CTS and loss of thumb abduction had a flexor digitorum superficialis transfer (37 small, 10 ring, 4 middle finger donors) to the abductor pollicis brevis with simultaneous carpal tunnel release (49 of 51 endoscopic). Thirty patients (60%) were women with an average age of 70 years (range, 35-90 y). Forty-three patients (84%) were in their sixth through eighth decades. We analyzed retrospectively preoperative and postoperative abduction, abduction strength, thenar muscle recovery and function, and patient satisfaction and complications. RESULTS: All patients reported improved thumb and hand function. Thumb abduction increased almost 20 degrees and 3 British Medical Research Council strength grades. Abduction was improved by the transfer in all patients, with some thenar recovery found in 35 of 40 cases followed-up longer than 12 months. Harvest of the flexor digitorum superficialis from the ring and middle fingers was associated with donor finger proximal interphalangeal joint contracture, although harvest from the small finger was not. CONCLUSIONS: Carpal tunnel release with simultaneous flexor digitorum superficialis-to-abductor pollicis brevis transfer provides satisfactory results for patients with profound CTS and thenar paralysis. The use of the small finger superficialis as the donor motor has minor morbidity compared with other methods and has predictable improvement and patient satisfaction. This transfer method is combined easily with endoscopic carpal tunnel release (as in 49 of our 51 cases), 2-portal, or open method releases.     

Gliding characteristics between flexor tendons and surrounding tissues in the carpal tunnel: a biomechanical cadaver study.

The purpose of this study was to investigate the gliding characteristics of flexor tendons within the carpal tunnel with varied wrist positions and tendon motion styles, which may help us to understand the relationship between carpal tunnel syndrome (CTS) and repetitive hand motion. Eight fresh human cadaveric wrists and hands were used. The peak (PGR) and mean (MGR) gliding resistance of the middle finger flexor digitorum superficialis tendon were measured with the wrist in 0, 30, and 60 degrees of flexion and extension. While moving all three fingers together, the PGR at 60 degrees flexion was significantly higher than that at 0, 30, or 60 degrees extension. While moving the middle finger alone, the PGR at 60 and 30 degrees flexion was significantly higher than the PGR at 60 degrees extension. The PGR moving the middle finger FDS alone was significantly greater than that for all three digits moving together in 0, 30, and 60 degrees flexion. Differential finger motion with wrist flexion elevated the tendon gliding resistance in the carpal tunnel, which may be relevant in considering the possible role of wrist position and activity in the etiology of CTS.     

Complete division of the flexor pollicis longus tendon as a rare complication in open carpal tunnel release: a case report

A rare case of complete division of the flexor pollicis longus tendon as a complication of open carpal tunnel using a short-incision is reported. The tendon was cut directly beneath the proximal edge of the transverse carpal ligament. Furthermore, the transverse carpal ligament was split incompletely. A few days after surgery, the patient noted that she was unable to flex the thumb interphalangeal joint. A re-operation completely releasing the transverse carpal ligament and suturing the lacerated tendon was performed 2 weeks later.     

Endoscopic carpal tunnel release in selected rheumatoid patients

Twenty endoscopic carpal tunnel releases were performed in 15 patients with quiescent seropositive rheumatoid arthritis using the Agee technique. Patients were not considered for endoscopic carpal tunnel release if there was florid synovitis with crepitus or loss of active finger flexion, if there was evidence of flexor tendon rupture or if they had previously undergone surgery in the region. Access to the tunnel was significantly easier than normal and visualization of the flexor retinaculum was satisfactory in all cases. There were no complications. We conclude that endoscopic carpal tunnel release can be safely performed in selected patients with rheumatoid arthritis. The absence of a palmar scar can be a great advantage to these disabled patients.     

Velocity‐dependent changes in the relative motion of the subsynovial connective tissue in the human carpal tunnel

The purpose of this study was to measure the rate‐dependent changes in the relative motion of subsynovial connective tissue (SSCT) and median nerve in the human carpal tunnel. Using fluoroscopy, we measured the relative motion of middle finger flexor digitorum superficialis tendon, SSCT, and median nerve in eight human cadavers during simulated active finger flexion motions at 2.0, 5.0, 7.5, and 10.0 mm/s. The shear index was defined as the difference in motion between tendon and SSCT or tendon and nerve, expressed as a percentage of tendon excursion. The motion patterns of the SSCT and median nerve relative to tendon excursion were measured at each 10% increment (decile) of maximum tendon excursion. The tendon–SSCT shear index was significantly higher at 10.0 mm/s than at 2.0 mm/s in the single‐digit motion. There were corresponding significant decreases in SSCT and median nerve motion for the 10.0 mm/s velocity compared to the 2.0 mm/s velocity. This study demonstrates that the relative motion of the tissues in the carpal tunnel appears to be dependent on tendon velocity, specifically with less nerve and SSCT motion at higher velocity tendon motion. This suggests that SSCT may be predisposed to shear injury from high‐velocity tendon motion. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:62–66, 2011     

Trigger digits-associated carpal tunnel syndrome: relationship between carpal tunnel release and trigger digits.

Of 875 idiopathic carpal tunnel syndrome (CTS) cases, 101 (11.5%) required trigger digit release operations within three years before and/or after carpal tunnel release (CTR); these 101 cases were investigated, retrospectively. Trigger digit release (TDR) was performed most often after the CTR, especially within three months. Next most common was at the same time as the CTR. The TDR performance rate after CTR was 5.9%. The nerve conduction study (NCS) comparison between trigger digits-associated CTS and isolated CTS showed that pre-operative distal motor latency was significantly more delayed in trigger digits-associated CTS, while there was no evidence of any difference due to age or gender. The difference of operative method (open or endoscopic procedure) did not influence the incidence rate of trigger digits after the CTR. This study suggested that trigger digits-associated CTS has a previously developed wide-ranging narrowing of the flexor tendon sheath.     

Biomechanical influence of the vincula tendinum on digital motion after isolated flexor tendon injury: a cadaveric study

PURPOSE: The vincula are specialized mesotendinous structures attaching to the flexor tendons of the hand. In addition to providing vascular supply to the tendons, the vincula can be mechanically important. The purpose of this study was to quantify the influence of intact vincula on digital flexion after flexor tendon laceration and to assess the ultimate strength and stiffness of the vincula. METHODS: The index, middle, and ring fingers of 12 fresh-frozen cadaveric fingers were dissected free at the level of the metacarpophalangeal joint, preserving at least 10 cm of the flexor and extensor tendons. A 9.8-N load was applied to each flexor tendon, and using digital photography and image analysis software, the degree of flexion at the proximal and distal interphalangeal joints and excursion of tendons proximal to the metacarpophalangeal joint was recorded before and after division of the flexor digitorum profundus and flexor digitorum superficialis tendons at their insertions. Load to failure and stiffness of the vincula were measured via a uniaxial material testing apparatus. Analysis of means was performed with a paired t-test. RESULTS: After division of the flexor digitorum superficialis tendon, proximal interphalangeal joint flexion secondary to the influence of the intact vincula was 93% of that compared with the uninjured digit. Distal interphalangeal joint flexion after flexor digitorum profundus transection was 69% of normal. The increased excursion of transected tendons compared with testing before division was 4 mm for flexor digitorum superficialis and 2 mm for flexor digitorum profundus. Load to failure was 27 N, and stiffness was 6 N/mm. CONCLUSIONS: The vincula breve can facilitate digital flexion after distal tendon transection, allowing tendons to act indirectly across the interphalangeal joints. The intact vincula breve can facilitate an almost normal range of motion across the interphalangeal joints, making the diagnosis of a flexor tendon injury difficult. In the immediate postinjury period, the vincula breve can hold a divided tendon within a few millimeters of its insertion. Testing against resistance is important to avoid missing the diagnosis of a tendon injury.     

经手掌近侧小切口的腕管切开松解减压术

目的 报告使用手掌近侧小切口的腕管切开松解减压术的疗效。方法 自大、小鱼际纹交界处向远侧腕横纹做纵行切口，长2～2．5cm，直视下切开屈肌支持带，解除正中神经卡压。术后随访并与同期采用传统长切口的病例比较，观察小切口的疗效。结果 随访病例19例30腕，其中小切口6例11腕，长切口13例19腕，它们在手指麻木、腕痛、握力及两点辨别觉改善等方面无明显差异，在切口长度、手术时间、恢复正常生活与工作时间以及术后瘢痕触痛、墩柱部疼痛等方面，前者优于后者。结论 经手掌近侧小切口实施腕管切开松解减压术，较传统方法有更多优点，是一种安全、有效的治疗方法。     

内窥镜Chow法治疗腕管综合征

目的探讨内窥镜镜视下Chow法行钩刀或推刀切断腕横韧带,解除正中神经压迫的手术方法和疗效。方法2004年5月-2009年8月,对76例（85侧）腕管综合征患者采用Chow法在内窥镜镜视下行腕横韧带切开术。结果经2～18月随访,伤口均一期愈合,无血管神经损伤,无手掌部疼痛,无伤口感染,多数患者术后夜麻即消失,术后4周桡侧三个半指感觉恢复正常,麻木、疼痛症状明显缓解,10周左右拇对掌功能恢复。Kelly分级评定：优（症状完全消失）58侧,良（明显缓解）21侧,一般（症状轻度减轻）5侧,差（症状不变或加重）1侧,优良率92．94％。结论Chow法内窥镜镜视下切开腕横韧带治疗腕管综合征是安全有效的微创手术。