Carpal Tunnel Release Using Ultrasound Guidance: Two-Year Outcomes of a Randomized Controlled Trial Within the Military

Abstract

Purpose

The primary objective was to compare the short-term (1-month) and long-term (2-year) outcomes of carpal tunnel release (CTR) using ultrasound guidance (CTR-US) to mini-open CTR (mOCTR) within the United States military population.

Methods

This single-site, prospective, randomized controlled trial enrolled military beneficiaries with carpal tunnel syndrome (CTS). Participants were randomized to receive either CTR-US in the clinic procedure room setting or mOCTR. Demographics and patient-reported outcome measures (PROs) were collected at baseline and follow-up PROs out to 2-years postprocedure. The primary outcome was the Quick Disabilities of the Arm, Shoulder, and Hand at 1 month. Additional outcomes included the Numeric Pain Rating Scale, Boston Carpal Tunnel Questionnaire – Symptom Severity Scale, Modified 2-item CTS Palmar Pain Scale, and adverse events (2-year window). Complete-case, intention-to-treat, generalized additive models (α = 0.05) were used to compare PROs between groups.

Results

Forty-one participants (58.5% women, 49.5 ± 14.4 years, 41.5% active duty) were randomized and treated (21 CTR-US, 20 mOCTR) with 100% follow-up at 2 years. Both groups demonstrated improved Quick Disabilities of the Arm, Shoulder, and Hand (CTR-US: −8.2 ± 17.1; mOCTR: −8.4 ± 13.6), Boston Carpal Tunnel Questionnaire – Symptom Severity Scale (CTR-US: −0.9 ± 0.8; mOCTR: −1.2 ± 0.7), and Numeric Pain Rating Scale (CTR-US: −1.1 ± 2.7; mOCTR: −1.1 ± 2.1) scores at 1 month with sustained clinically meaningful improvement out to 2 years. The CTR-US group reported less incisional pain and functionally limiting incisional pain during the first 4 and 3 weeks, respectively. One infection was reported in the CTR-US group.

Conclusions

Both groups had clinically meaningful improvements out to 2 years with respect to pain and CTS symptom reduction, as well as improvement in function. Compared to mOCTR, the CTR-US group reported less incisional pain and functionally limiting incisional pain in the early postprocedural period.

Type of study/level of evidence

Therapeutic 1B.

Carpal tunnel syndrome (CTS) is the most common peripheral entrapment neuropathy.^1,2 CTS incidence is between 1.5 and 3.5 per 1,000 person-years³ within the general workforce and 3.98 per 1,000 person-years among military personnel.⁴ Current literature indicates risk factors include female gender, increasing age, forceful repetitive movements, forceful grip, and vibration exposure (low risk evidence), the last three of which are relevant within the United States Military Health System (MHS).3, 4, 5, 6 CTS treatment options include activity modification, bracing, injections, and in severe or refractory cases, carpal tunnel release (CTR).^7,8 CTS can impact readiness and return to duty in the military and general populations, prompting the need to improve treatment options.^4,5 CTR techniques have evolved over time to reduce iatrogenic tissue trauma and postoperative pain, promoting quicker recovery and improved outcomes.9, 10, 11, 12, 13

Newer techniques have incorporated image guidance (eg, endoscope, ultrasound [US]), alternative anesthesia (eg, Wide Awake Local Anesthesia No Tourniquet), and a variety of devices that facilitate transverse carpal ligament (TCL) release via smaller incisions.9, 10, 11, 12, 13, 14, 15, 16 CTR using a mini-open carpal tunnel release (mOCTR) or endoscopic carpal tunnel release approach is the current standard of care in the MHS for management of severe or refractory CTS. These techniques are typically performed via a single, palmar (1−3 cm) and single, forearm (≤1 cm) incision, respectively.17, 18, 19, 20, 21, 22 As the availability of high-resolution US systems has continued to increase, the role of US has expanded into image-guided procedures, including CTR with US guidance (CTR-US). US provides a unique combination of dynamic, high-resolution imaging and a wide field of view of the carpal tunnel region.^8,23, 24, 25, 26, 27 Compared to mOCTR and endoscopic carpal tunnel release, CTR-US involves a single, smaller (<1 cm), non-palmar incision,^10,11 and the use of US can reliably identify potential structures at risk of injury, including the thenar motor branch, and anatomic variations.25, 26, 27

Previous publications have demonstrated the safety and effectiveness of CTR-US using various techniques.9, 10, 11, 12, 13^,28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38 Multiple observational studies, case series, and a prospective multicenter trial have demonstrated clinically meaningful symptom reduction and functional improvement as early as 2 weeks postprocedure that are maintained up to 2−6 years.^{10,11,17,18,28,30,}38, 39, 40, 41, 42, 43, 44, 45, 46 Several randomized controlled trials (RCTs) have compared CTR-US to mOCTR.9, 10, 11^,13,31 Results have varied but generally demonstrate equal or superior outcomes following CTR-US, particularly with respect to early recovery.9, 10, 11^,13,31 Notably, the longest RCT duration follow-up was 1 year, only one RCT involved a United States population, and all CTR-US procedures were performed by surgeons. Although CTR-US can be performed by surgeons, non-surgeons with experience performing advanced US-guided procedures and appropriate training can also safely perform this procedure.^28,30,39,43

The primary purpose of this RCT was to compare the outcomes of CTR-US to mOCTR within a United States military population, including longer duration follow-up (2 years) relative to previous RCTs. CTR-US was performed by trained non-surgeons and mOCTR was performed by fellowship-trained hand surgeons. The primary outcome was upper extremity function at 1-month postprocedure. Secondary outcomes included pain, CTS symptoms, medication use, adverse events, and procedural data. This article presents the 1-month and 2-year outcomes for military beneficiaries enrolled in this trial.

Materials and Methods

Study design

This study is a single-site, prospective RCT at Walter Reed National Military Medical Center, approved by the Walter Reed National Military Medical Center Institutional Review Board (WRNMMC-2020-0278). This study was performed in accordance with the ethical standards in the 1964 Declaration of Helsinki and relevant regulations of the United States Health Insurance Portability and Accountability Act (HIPAA). The study was prospectively registered on ClinicalTrials.gov (NCT04504019) on 06/22/2020 (https://clinicaltrials.gov/study/NCT04504019?term=NCT04504019&rank=1) and followed the Consolidated Standards of Reporting Trials (CONSORT) guidelines.

Screening, enrollment, and randomization

Military beneficiaries (18−89 years) with clinical, electrodiagnostic, and US findings consistent with median neuropathy at the wrist were enrolled by the study coordinator from 03/2021 to 03/2023. Electrodiagnostic severity was determined per the Bland criteria.⁴⁷ Exclusion criteria included patients with prior wrist surgery, median nerve (MN) trauma, or US findings precluding safe and effective CTR-US based on performing physicians’ experience.

After written consent, participants underwent standardized US examinations to confirm MN enlargement and determine CTR-US eligibility. Examinations were performed by the principal investigator using a 5−18 or 4−18 MHz broadband linear array transducer (Affiniti 70, Philips, Inc). The principal investigator is a board-certified physical medicine and rehabilitation (PM&R) physician with Registered in Musculoskeletal sonography certification who had 9 years of clinical musculoskeletal US experience at study start.

The MN was surveyed from the distal humerus to the palm and focused on key anatomic structures including MN and its distal branches, ulnar artery, superficial palmar arch, TCL, and any anatomic variations.²⁷ Measurements included MN cross-sectional area (mm²) at the pisiform (and pronator quadratus, if indicated) and the transverse safe zone at the hamate [defined as the distance between the MN and the hook of the hamate or ulnar artery, whichever is closer].^{13,24,27,48,49} Further examination details are provided in Appendix S1 and Figure S1, available online on the Journal’s website at https://www.jhsgo.org. Remaining eligible participants were randomized 1:1 to CTR-US or mOCTR, and the study coordinator relayed allocations to participants and providers.

mOCTR procedures

mOCTR procedures were performed by three fellowship-trained hand surgeons with 1, 9, and 15 years of surgical experience at study start. mOCTR was selected as the comparator because it was the preferred CTR technique at the study site and was already being performed in the outpatient clinic procedure room setting, the planned setting for CTR-US. mOCTR procedures were performed using a small, palmar incision in a clinic procedure room using only local anesthesia via standard procedures or in an operating room (OR) with local anesthesia and moderate sedation due to staffing limitations. Wounds were closed with sutures and dressed with occlusive dressing, gauze, and self-adherent wrap. As per standard site protocol, all mOCTR participants received postprocedure prescriptions for hydrocodone/acetaminophen and ibuprofen, were advised to keep their incisions covered for at least 5 days postprocedure, and returned for suture removal at 2 weeks. Repetitive movements and heavy gripping activities were limited for 1−2 weeks postprocedure and gradually progressed thereafter depending on patient tolerance and healing status.

CTR-US procedures

CTR-US procedures were performed by two PM&R physicians with 7 and 8 years of post-training experience in US-guided and interventional pain procedures at study start. Although both had completed a formal, cadaver-based training program in CTR-US, the study procedures represented their first clinical CTR-US procedures. Training and additional procedural details are included in Appendix S1, available online on the Journal’s website at https://www.jhsgo.org. All CTR-US procedures were performed under continuous US guidance with a 4−18 MHz broadband linear array transducer (Affiniti 70, Philips, Inc) in the clinic procedure room using only local anesthesia. The PM&R clinic is located in close proximity to the Orthopedic Surgery clinic, which was conducive for procedural consults as needed. CTR-US procedures were performed using a small (4−6 mm), distal forearm incision using only local anesthesia. After injecting local anesthetic and blunt dissection, the CTR-US device (UltraGuideCTR, Sonex Health, Inc) was then inserted and appropriately positioned in the carpal tunnel under real-time US guidance (Fig. 1A, B).^10,11,30,39 Once positioned, the two inflatable balloons were activated to create space within the carpal tunnel (Fig. 1A) and following reconfirmation of accurate placement, the TCL was released by a retractable blade in a retrograde manner. Wounds were closed with 2−4 sterile adhesive strips in a star pattern to the incision site (preceded by topical skin adhesive per provider discretion). Similar to mOCTR, gauze and self-adherent wrap were applied over the distal forearm, wrist and hand. Opioid prescriptions were provided upon participant request. Participants were advised to keep incisions covered for at least 5 days postprocedure, and they removed their sterile adhesive strips (if still present) at 1 week. Postprocedure activity guidelines were similar to mOCTR.

Figure 1.

Ultrasound views of device used to perform CTR-US. Ultrasound guidance is used during the entirety of the procedure to visualize the key neurovascular and muscular structures and the device used to perform the CTR-US procedure (see main text and Appendix S1, available online on the Journal’s website at https://www.jhsgo.org). A is a transverse view of the carpal tunnel showing a SAX view of the device with balloons inflated (black arrows with blue border) and B depicts a longitudinal view of the carpal tunnel and LAX view of the device deep to the TCL prior to deployment of the retractable, retrograde blade for TCL transection. CTR-US, carpal tunnel release using ultrasound guidance; LAX, long axis; MN, median nerve; SAX, short axis; TCL, transverse carpal ligament; UA, ulnar artery.

Demographics and patient-reported outcome measures (PROs)

Demographics and PROs were collected prior to the procedure by the study coordinator. Follow-up PROs were collected at 1-, 2-, 3-, 4-, and 6-weeks, 3-, 6-, and 12-months, and 2-years postprocedure by the study coordinator. In-person follow-ups occurred at 1-, 2-, and 6-weeks, 3- and 12-months. The primary outcome was the change in Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH)⁵⁰ at 1 month. Our sample size estimate based on 1-month change in QuickDASH score targeted 83 patients for 90% power to detect an effect size of −10. Enrollment ended prior to reaching the target because of recruitment challenges within the funding period (ie, COVID-19 pandemic).

Additional PROs included Boston Carpal Tunnel Questionnaire – Symptom Severity Scale (BCTQ-SSS),⁵¹ Numeric Pain Rating Scale (NPRS),⁵² Global Assessment of Satisfaction, Global Rating of Change (GROC),^53,54 Modified 2-item CTS Palmar Pain Scale,⁵⁵ medication usage (type and frequency of use), and adverse events. The Global Assessment of Satisfaction is a 7-point Likert scale from Completely Dissatisfied (1) to Completely Satisfied (7) where scores ≥ 5/7 indicate satisfaction. The GROC is a 15-point Likert scale from a great deal worse (−7) to a great deal better (7) where scores ≥ 5/7 indicate overall improvement.^53,54 The Modified 2-item CTS Palmar Pain Scale allows participants to report on their palmar (including pillar pain) and incisional pain and their impact on function separately, with higher scores indicating more pain and functional interference.⁵⁵

Objective measures

Intra-operative data including procedure time, incision length, and method of closure were documented. Grip and pinch strength were measured (average of three trials) with a Jamar Hydraulic Handheld Dynamometer and B&L Engineering Pinch Gauge (JLW Instruments) at baseline, and 3 and 12 months.

Data analysis

Descriptive analyses reported central tendencies in terms of location (eg, mean, proportion) and scale (eg, SD) for all study variables. Demographics were reported as mean ± SD and percentages, procedural data as mean measurements (± SD), and PROs as mean change (± SD) or percentage at 1-month or 2-years postprocedure, compared to baseline. Inferential analyses included two-sample Welch’s t tests (α = 0.01) for procedural data and complete-case, intention-to-treat, generalized additive models (α = 0.05) incorporating multi-level structures through patient-level random effects for all other outcomes. Trial protocol and statistical analysis plan can be reviewed on ClinicalTrials.gov. Data can be made available upon request.

Results

The study CONSORT flow diagram is shown in Figure 2. Forty-one randomized participants (58.5% women, 49.5 ± 14.4 years, 41.5% active duty; 21 CTR-US, 20 mOCTR) were treated between 06/2021 and 07/2023. There were no significant differences in group demographics (Table 1). All 21 CTR-US and 15 mOCTR procedures were completed in clinic procedure rooms, whereas five mOCTR procedures were performed in OR with moderate sedation. Two-year follow-up was available for 100% of participants.

Figure 2.

CONSORT flow diagram. See additional screening information within Appendix S1, available online on the Journal’s website at https://www.jhsgo.org. CONSORT, Consolidated Standards of Reporting Trials.

Table 1.

Demographics and Baseline Data

Demographic/Baseline Variable	Variable Category	CTR-US Group (N = 21)	mOCTR Group (N = 20)	P
Age (y) (mean ± SD)		48.6 ± 13.3	50.4 ± 16.3	.6800
Sex (N [%])	M F	8 (38.1) 13 (61.9)	9 (45.0) 11 (55.0)	.6537
Marital status (N [%])	Divorced Legally separated Married Never married Widow or widower	1 (4.8) 0 (0) 17 (80.9) 1 (4.8) 2 (9.5)	2 (10.0) 1 (5.0) 16 (80.0) 1 (5.0) 0 (0)	.7977
Ethnicity (N [%])	Asian or Pacific Islander Black or African American (not Hispanic) Hispanic White (not Hispanic)	3 (14.3) 3 (14.3) 3 (14.3) 12 (57.1)	4 (20.0) 6 (30.0) 2 (10.0) 8 (40.0)	.6204
Military status (N [%])	Active duty Dependent Retired	8 (38.1) 7 (33.3) 6 (28.6)	9 (45.0) 4 (20.0) 7 (35.0)	.6281
Rank (N [%])	Enlisted (Senior) Officer (Junior) Officer (Senior) Warrant officer	6 (42.9) 2 (14.2) 6 (42.9) 0 (0)	6 (37.5) 2 (12.5) 7 (43.7) 1 (6.3)	1.000
Military service (N [%])	Air Force Army Marines Navy	1 (7.1) 6 (42.9) 2 (14.3) 5 (35.7)	4 (25.0) 8 (50.0) 0 (0) 4 (25.0)	.3227
Handedness (N [%])	L R	2 (9.5) 19 (90.5)	5 (25.0) 15 (75.0)	.2379
Procedures on dominant hand (N [%])		14 (66.7)	15 (75.0)	--------
CTS severity (N [%])	Mild Moderate Severe	1 (4.8) 11 (52.4) 9 (42.9)	2 (10.0) 6 (30.0) 12 (60.0)	.3856
MN CSA (mm2) (mean ± SD)		14.5 ± 4.3	15.1 ± 4.7	.6109
TSZ (mm) (mean ± SD)		6.1 ± 1.9	6.6 ± 1.8	--------
QuickDASH score (mean ± SD) (0−100)		29.8 ± 17.7	37.4 ± 16.6	.1642
BCTQ-SSS score (mean ± SD) (1−5)		2.7 ± 0.8	3.1 ± 0.8	.1610
NPRS Score (mean ± SD) (0−10)		3.5 ± 2.5	3.5 ± 2.2	.9930
Opioid use frequency∗ (mean ± SD) (0−5; 0: no use;5: multiple times per day)		0.2 ± 0.7	0.3 ± 0.9	--------

BCTQ-SSS, Boston Carpal Tunnel Questionnaire – Symptom Severity Scale; CSA, cross-sectional area; CTR-US, carpal tunnel release using ultrasound guidance; CTS, carpal tunnel syndrome; MN, median nerve; mOCTR, mini-open carpal tunnel release; NPRS, Numeric Pain Rating Scale; QuickDASH, Quick Disabilities of the Arm, Shoulder, and Hand; SD, standard deviation; TSZ, transverse safe zone.

^∗Refer to Figure 8 legend for additional details.

Both groups demonstrated improved QuickDASH scores (Fig. 3) at 1 month (primary outcome; CTR-US: −8.2 ± 17.1; mOCTR: −8.4 ± 13.6; P = .510) and 2 years (CTR-US: −16.3 ± 22.9; mOCTR: −26.5 ± 20.1; P = .652) postprocedure, with similar trends for BCTQ-SSS (Fig. 4) and NPRS (Fig. 5). Both groups exceeded the minimal clinically important difference values of 10,⁵⁰ 1.1,⁵¹ and 2,⁵² for the QuickDASH, BCTQ-SSS, and NPRS, respectively, by 1 year, indicating clinically meaningful improvement, which was sustained out to 2 years. There were no significant differences between groups for the aforementioned PROs at 1 month or 2 years (P > .05). However, the wider confidence intervals likely due to the underpowered sample must be considered. At 2 years, 85.7% of CTR-US and 100.0% of mOCTR reported being satisfied with their procedures, and 81.0% of CTR-US and 90.0% of mOCTR reported a GROC score of ≥ 5/7.^53,54 There were no significant differences between groups in grip and pinch strength (Table 2) at 3 months or 1 year (P > .05).

Figure 3.

Mean QuickDASH scores following CTR-US and mOCTR groups over 2 years postprocedure. QuickDASH is scored on scale of 0−100 points, where higher scores indicate more functional limitations. Both groups demonstrated improved QuickDASH scores at 1 month (CTR-US: −8.2 ± 17.1; mOCTR: −8.4 ± 13.6), which was the primary outcome, and 2 years (CTR-US: −16.3 ± 22.9; mOCTR: −26.5 ± 20.1) postprocedure. Both groups experienced reductions in QuickDASH scores that exceeded the MCID of 10 out to 2 years. There were no statistically significant differences in QuickDASH scores between groups at 1 month (P = .510) or 2 years (P = .652). Note the increase in QuickDASH scores at 1 week in both groups, at which time the mean (± SD) QuickDASH score increased from 37.4 ± 16.6 to 58.6 ± 23.5 in the mOCTR group and from 29.8 ± 17.7 to 40.3 ± 22.3 in the CTR-US group. CTR-US, carpal tunnel release using ultrasound guidance; MCID, minimal clinically important difference; mOCTR, mini-open carpal tunnel release; QuickDASH, Quick Disabilities of the Arm, Shoulder, and Hand; SD, standard deviation.

Figure 4.

Mean BCTQ-SSS scores following CTR-US and mOCTR groups over 2 years postprocedure. BCTQ-SSS is scored on scale of 1−5 points, where higher scores indicate more symptoms. BCTQ-SSS scores improved in both groups at 1 month (CTR-US: −0.9 ± 0.8; mOCTR: −1.2 ± 0.7) and 2 years (CTR-US: −1.1 ± 0.8; mOCTR: −1.6 ± 0.9). Both groups experienced reductions in BCTQ-SSS scores that met or exceeded the MCID of 1.1 out to 2 years. There were no statistically significant differences in BCTQ-SSS scores between groups at 1 month (P = .362) or 2 years (P = .214). BCTQ-SSS, Boston Carpal Tunnel Questionnaire – Symptom Severity Scale; CTR-US, carpal tunnel release using ultrasound guidance; MCID, minimal clinically important difference; mOCTR, mini-open carpal tunnel release.

Figure 5.

Mean NPRS scores following CTR-US and mOCTR groups over 2 years postprocedure. Both groups demonstrated reduced NPRS scores (hand/wrist/lower arm) at 1 month (CTR-US: −1.1 ± 2.7; mOCTR: −1.1 ± 2.1) and 2 years (CTR-US: −2.5 ± 2.3; mOCTR: −2.5 ± 2.5) postprocedure. Both groups experienced reductions in NPRS scores that exceeded the MCID of 2.0 at 2 years. There were no statistically significant differences in NPRS scores between groups at 1 month (P = .359) or 2 years (P = .517). CTR-US, carpal tunnel release using ultrasound guidance; MCID, minimal clinically important difference; mOCTR, mini-open carpal tunnel release; NPRS, Numeric Pain Rating Scale.

Table 2.

Grip and Pinch Strength

Measurement Type	Timepoint	CTR-US Group (N = 21)	mOCTR Group (N = 20)	Adjusted Mean Between-Group Difference in Change from Baseline to 3-Mo and Baseline to 12-Mo (95% CI)∗	P
Grip strength (kg) (mean ± SD)	Baseline	28.6 ± 14.0	24.7 ± 12.9	--------
	3-Mo	27.3 ± 13.2	24.3 ± 10.5†	−0.87 (−6.51 to 4.77)	.7442
	12-Mo	30.3 ± 14.4‡	31.7 ± 10.4§	−3.56 (−9.00 to 1.88)	.1797
Tip pinch strength (kg) (mean ± SD)	Baseline	5.5 ± 1.5	4.8 ± 1.9	--------
	3-Mo	6.1 ± 2.1	4.9 ± 1.3†	0.37 (−0.60 to 1.34)	.4271
	12-Mo	6.2 ± 1.9‡	5.9 ± 1.3§	−0.05 (−0.94 to 0.84)	.9067
Palmar pinch strength (kg) (mean ± SD)	Baseline	6.6 ± 1.7	5.8 ± 2.0	--------
	3-Mo	7.0 ± 2.2	6.1 ± 1.5†	0.10 (−0.71 to 0.90)	.7999
	12-Mo	7.2 ± 2.3‡	6.7 ± 1.5§	0.22 (−0.97 to 1.40)	.6969
Key pinch strength (kg) (mean ± SD)	Baseline	8.0 ± 2.2	7.5 ± 2.1	--------
	3-Mo	8.2 ± 2.3	7.4 ± 1.6†	0.20 (−0.59 to 1.00)	.5891
	12-Mo	8.1 ± 2.5‡	8.6 ± 1.7§	−0.72 (−1.76 to 0.32)	.1577

CTR-US, carpal tunnel release using ultrasound guidance; kg, kilograms; mOCTR: mini-open carpal tunnel release; SD, standard deviation

^∗The adjusted mean differences are derived from generalized additive models incorporating random effects, predicting each change from baseline.

^†Measurements only available for 19 mOCTR participants at 3-month follow-up.

^‡Measurements only available for 20 CTR-US participants at 12-month follow-up.

^§Measurements only available for 17 mOCTR participants at 12-month follow-up.

Mean CTR-US distal forearm incision length was shorter than mean mOCTR proximal palmar incision length (CTR-US: 5.4 ± 0.8 mm; mOCTR: 28.0 ± 4.2 mm; P < .01; Fig. 6A, B). Mean immediate postprocedure pain scores (participants treated with local anesthesia only; n (CTR-US) = 21, n (mOCTR) = 15) were 0.3 ± 1.0 and 0.8 ± 1.7 for CTR-US and mOCTR, respectively, with no significant between-group differences (P = .287). CTR-US group reported less incisional pain (Fig. 7A) and impact of incisional pain on function (Fig. 7B) during the first 4 (P = .0000126) and 3 (P = .0000016) weeks, respectively, in comparison to mOCTR group. Although opioid use was uncommon in both groups, there was a greater frequency of opioid use in the immediate postprocedure period for mOCTR compared to CTR-US (P = .000593) (Fig. 8). There were no significant differences in frequency of other pain medication use (P = .136).

Figure 6.

CTR-US and mOCTR scores at 6-weeks postprocedure. A depicts a CTR-US participant’s scar at 6-weeks postprocedure. The mean incision size (± SD) for the CTR-US group (N = 21) was 5.4 ± 0.8 mm. B depicts a mOCTR participant’s scar at 6-weeks postprocedure. The mean incision size (± SD) for the mOCTR group (N = 20) was 28.0 ± 4.2 mm. The CTR-US mean incision was statistically significantly shorter compared to mOCTR (P < .01). A mean of 3.25 ± 1.65 sutures was used for mOCTR, whereas sterile adhesive strips were used for CTR-US. CTR-US, carpal tunnel release using ultrasound guidance; mOCTR, mini-open carpal tunnel release; SD, standard deviation.

Figure 7.

Mean incisional pain and incisional pain impact on function scores following CTR-US and mOCTR groups over 1-month postprocedure. Incisional pain and impact on function were measured by a Modified 2-Item CTS Palmar Pain Scale with higher scores reflecting more pain and functional limitation. A depicts mean incisional pain scores (0−5) in the CTR-US and mOCTR groups over 1-month postprocedure. The mean incisional pain score at 4 weeks was 1.0 ± 1.2 and 2.1 ± 0.9 for the CTR-US and mOCTR groups, respectively. CTR-US participants reported significantly less incisional pain during the first 4 weeks compared to mOCTR participants (P = .0000126). B depicts mean incisional pain impact on function scores (0−5) in the CTR-US and mOCTR groups over 1-month postprocedure. The mean incisional pain impact on function score at 3 weeks for the CTR-US and mOCTR groups was 0.7 ± 1.0 and 1.8 ± 0.9, respectively. CTR-US participants reported significantly less functionally limiting incisional pain during the first 3 weeks compared to mOCTR participants (P = .0000016). Solid line is the predicted line for each treatment group, while the shaded areas represent the 95% confidence interval. No overlap of the 95% confidence intervals indicates statistical significance (^∗). CTR-US, carpal tunnel release using ultrasound guidance; CTS, carpal tunnel syndrome; mOCTR, mini-open carpal tunnel release.

Figure 8.

Mean opioid use frequency in the CTR-US and mOCTR groups over 1-month postprocedure. At 1-week postprocedure, there was a significantly higher frequency of opioid use in the mOCTR group (2.0 ± 2.2) compared to the CTR-US group (0.1 ± 0.5) (P = .000593). Opioid use frequency was self-reported on a scale from 0 to 5. The following frequency of use options are as follows: 0 = no use, 1 = less than once a week, 2 = once a week, 3 = several times a week, 4 = daily, 5 = multiple times per day. Solid line is the predicted line for each treatment group, while the shaded areas represent the 95% confidence interval. No overlap of the 95% confidence intervals indicates statistical significance (^∗). CTR-US, carpal tunnel release using ultrasound guidance; mOCTR, mini-open carpal tunnel release.

Mean CTR-US procedure time (incision to closure) was significantly greater than that for mOCTR (CTR-US: 32.2 ± 14.7 min; mOCTR: 16.2 ± 4.2 min; P < .01). No procedural consults were required. One CTR-US participant, included in all the above analyses, was diagnosed with an incision site methicillin-resistant Staphylococcus aureus infection (serious adverse event) 9 days postprocedure after presenting to emergency room with heightened pain, erythema, and discharge at incision site. The participant reported applying ointment to the incision site, without physician guidance, 6 days postprocedure. Treatment entailed antibiotics, multiple incision and drainage procedures, and hand therapy to facilitate recovery.

Discussion

The primary finding of this RCT is that CTR-US and mOCTR can both yield clinically meaningful improvements in pain, CTS symptoms, and function out to 2 years in a military population. As the target sample size was not met, the comparative statistical analyses demonstrating no significant between-group differences should be interpreted with appropriate caution. Nevertheless, the improving trends across the PROs in both groups are comparable to previous studies examining long-term outcomes of CTR-US and expand upon results of previous RCTs by including a military population, longer follow-up (2-year), and CTR-US procedures performed by non-surgeons in a clinic procedure room.9, 10, 11^{,13,17,18,28,30,31,39,40,43,46}

TUTOR RCT also reported mean change in BCTQ-SSS (CTR-US: −1.8, mOCTR: −1.8; P = .96) and numeric pain scale (0−10) (CTR-US: −3.9; mOCTR: −3.8; P = .74) but at 1 year postprocedure.¹⁰ Although the 1-year PRO improvements in TUTOR RCT were greater than the mean change in BCTQ-SSS (CTR-US: −1.3 ± 1.0; mOCTR: −1.5 ± 0.9) and NPRS (CTR-US: −2.4 ± 2.8; mOCTR: −2.5 ± 2.8) in the current study, the between-group differences were similar. In terms of function and treatment satisfaction, the CTR-US group’s mean QuickDASH score (10.4 ± 16.3) and satisfaction rate (85.7%) at 1 year in our study are comparable to the study of Cano et al³⁰ on prospective CTR-US cohort, where the mean QuickDASH score and satisfaction rate were reported as 11.7 ± 18.2 and 87.0% at 1 year, respectively.

Despite similar trends in 1-month and 2-year outcomes, the CTR-US group had smaller incisions and reported less functionally limiting incisional pain, and lower frequency of postprocedural opioid use in the early postprocedural period. The specific reason(s) for increased opioid use frequency in the mOCTR group is beyond the scope of the current study but may in part reflect differences in opioid prescription practices. Both groups reported minimal to no pain immediately postprocedure with no significant differences between groups, which is also consistent with previous RCTs comparing CTR-US and mOCTR, indicating high patient tolerance for both procedures.^10,11,13 The increased CTR-US procedure time is likely due to the notable differences between procedures, particularly the use of US imaging guidance.⁵⁶ Specifically, CTR-US required additional time to sonographically identify key anatomic structures and confirm accurate device placement throughout the procedure. Despite the longer procedural duration, a prior study has already demonstrated that clinic-based hand surgeries require significantly less time (P < .05) spent at the treatment facility in comparison to OR procedures, improving treatment efficiency.⁵⁷

Although the CTR-US procedures were performed by experienced PM&R physicians, there exists an opportunity to expand the current skillset of military surgeons to include musculoskeletal US, including advanced US-guided procedures. For example, a recent American Society for Surgery of the Hand survey reported an increase in US use (68%) among members, with 68% of respondents reporting some US use in their practices.^58,59 In addition, favorable outcomes have already been reported for hand surgeons with minimal to no prior US experience and no prior CTR-US experience prior to training and implementing CTR-US, demonstrating the feasibility of integrating this technique into clinical practice.^{10,11,28,38,41} Last, implementing clinic-based procedures has already been demonstrated to decrease costs and increase access to care within civilian and military clinical settings, targeting relevant CTS treatment barriers within the MHS.^16,57,60,61

Study strengths included the prospective, RCT design, electrodiagnostic confirmation of median neuropathy at the wrist for all participants, and 100% follow-up out to 2 years. In addition, all CTR-US procedures were performed by non-surgeons in a military clinic procedure room setting. However, there are several limitations that should also be considered when interpreting study results. First, it was not feasible to blind the participants or the investigators. Second, the study was underpowered considering the small sample size, which increases the risk of type II error. Therefore, the comparative statistical analyses must be interpreted with appropriate caution. Although the power analysis suggested an enrollment target of 83 patients, study recruitment was discontinued because of recruitment challenges (ie, COVID-19 pandemic) within the funding period. Third, although not planned, 5 mOCTR procedures were performed in the OR versus clinic procedure room, secondary to staffing limitations.

Fourth, although the PM&R physicians were experienced in US-guided procedures and trained in CTR-US, the hand surgeons were notably more experienced performing mOCTR than PM&R physicians performing CTR-US. We acknowledge that multiple patients were excluded based on US examination. These US findings were not necessarily contraindications to the CTR-US procedure but are reflective of an appropriate level of caution, given these were the first clinical procedures performed by the PM&R providers. While the differing levels of experience with the respective procedures can be viewed as both a strength and a limitation, we believe that the current results support the generalizability of the CTR-US technique with appropriate experience and training.^28,30,39,46 Finally, all CTR-US patients were treated with a specific US-guided technique and results may not be generalizable to other techniques.

In summary, the current study demonstrates that CTR-US and mOCTR both result in clinically meaningful improvements with respect to pain, CTS symptom reduction, and functional improvement out to 2 years in a military population. Compared to mOCTR, the CTR-US group reported less functionally limiting incisional pain within the early postprocedural period. These results have important implications for addressing current barriers to CTS treatment within the MHS and civilian sector, including limited access to surgical subspecialty care and limited resources (eg, OR availability, procedural costs, staffing requirements) and improving overall return to activity and return to duty.

Ethical Review Committee Statement

This study was reviewed and approved by the Walter Reed National Military Medical Center Institutional Review Board (WRNMMC-2020-0278). This study was performed in accordance with the ethical standards in the 1964 Declaration of Helsinki and relevant regulations of the US Health Insurance Portability and Accountability Act (HIPAA). The study was registered on ClinicalTrials.gov (NCT04504019) on 06/22/2020 (https://clinicaltrials.gov/study/NCT04504019?term=NCT04504019&rank=1).

Conflicts of Interest

The views expressed in this abstract are those of the author(s) and do not necessarily reflect the official policy of the Department of War or the US Government. The opinions and assertions expressed herein are those of the author(s) and do not necessarily reflect the official policy or position of the Uniformed Services University or the Department of War. Mention of trade names, commercial products or organizations does not imply endorsement by the U.S. Government.

Disclaimers

Each author certifies that there are no funding or commercial associations related to the author or any immediate family members that might pose a conflict of interest in connection with the submitted article.

Supplementary Data

Supplementary Figure 1.