Back To Search Results

Wide-Awake Local Anesthesia No Tourniquet (WALANT) Hand Surgery

Editor: H Brent Bamberger Updated: 4/17/2023 4:29:28 PM

Introduction

Wide-awake Local Anesthesia No Tourniquet (WALANT) is a surgical technique that relies on local anesthetic and hemostatic agents to provide conditions suitable for hand surgery without sedation and tourniquet.[1] The exclusion of sedation makes it possible to perform more procedures in an ambulatory setting rather than rely on general anesthesia only in the operating room. The use of WALANT leads to decreased cost and enhanced patient safety.[2][3][4][5]

Canadian plastic hand surgeon Dr. Lalonde first implemented WALANT to decrease wait times for surgery.[2] He formally proposed the concept in 2005 and has since internationalized it.[6][7]

Anatomy and Physiology

Register For Free And Read The Full Article
Get the answers you need instantly with the StatPearls Clinical Decision Support tool. StatPearls spent the last decade developing the largest and most updated Point-of Care resource ever developed. Earn CME/CE by searching and reading articles.
  • Dropdown arrow Search engine and full access to all medical articles
  • Dropdown arrow 10 free questions in your specialty
  • Dropdown arrow Free CME/CE Activities
  • Dropdown arrow Free daily question in your email
  • Dropdown arrow Save favorite articles to your dashboard
  • Dropdown arrow Emails offering discounts

Learn more about a Subscription to StatPearls Point-of-Care

Anatomy and Physiology

Tailor the history and physical exam to the pathology requiring repair, and assess for key anatomic landmarks to make the local injection most effective. For example, inject 5 mm proximal to the wrist crease on the median aspect best targets the median nerve in WALANT carpal tunnel release (see 'Techniques' section).[5]

Amides and esters are the two main groups of local anesthetics. WALANT typically utilizes the amides Lidocaine and Bupivacaine. These amides block voltage-gated sodium channels leading to decreased pain sensation and metabolize through the liver.

Epinephrine is used in combination with the amide to provide hemostasis. It accomplishes this by activating alpha-adrenergic receptors causing vasoconstriction of blood vessels. This vasoconstriction also delays lidocaine's absorption, thereby prolonging analgesia and improving lidocaine's safety profile.[8] There is evidence that epinephrine also causes hemostasis via platelet aggregation.[9][10]

A unique advantage of WALANT is that it decreases the risk of adhesion formation due to earlier active participation by the patient, which begins intraoperatively. Collagen formation begins on postoperative day three. Thus it should be a priority to begin supervised exercises after most hand procedures to prevent stiffness and adhesions. Prolonged immobilization causes tendons and soft tissue to adhere to the fracture callous and tendon sheaths, resulting in permanently stiff joints.[11]

Indications

The majority of commonly performed hand procedures can use WALANT successfully.[5] It is ideal for patients with comorbidities that might otherwise preclude them from surgery under sedation (congestive heart failure, obstructive sleep apnea).[1][2] Contraindication to tourniquet is another reason to choose WALANT (i.e., ESRD with an AV-fistula).[1][2]

Poor access to healthcare is an indication for WALANT. Without the need for an operating room or anesthesia team, ambulatory surgical care is possible in locations that are remote or lacking adequate resources.[12][7] Multiple studies have demonstrated that WALANT is consistently cheaper and more efficient to perform than in an operating room when feasible.[13][7][2][11]

The COVID-19 epidemic has highlighted the need for ambulatory surgery to avoid unnecessary exposure. WALANT decreases unnecessary exposure to patients and staff by avoiding both the operating room and overnight stays in the hospital. Without sedation, there are no intubation exposure risks, and fewer staff members are needed to facilitate room turnover. This helps the hospital free up the operating rooms for urgent cases requiring anesthesia.[4][14]

For complex procedures requiring advanced instrumentation and more support staff, such as tendon transfers and multiple fracture fixations, WALANT can easily be performed in the operating room as well.

The three principal benefits of WALANT are patient safety, greater access to surgical needs, and improved intraoperative diagnosis and assessment.[3][7][13][5]

The preoperative benefits of WALANT are improved access to surgical care and workflow. Multiple studies demonstrate decreased wait times from the first consultation to surgery day.[15] Without sedation concerns, patients drive themselves to the facility and eat breakfast beforehand.[16][2] Remote and impoverished areas can accommodate surgeons despite less infrastructure.[7][11] The preoperative phase is shorter, as patients can delay their arrival until 30 minutes before start time. A preoperative workup is not obligatory for safe outcomes. There are fewer procedure cancellations and delays since an anesthesiologist's preoperative clearance is not required. Patients with significant comorbidities like CHF or COPD have less perioperative risk.[3]

Patients can only tolerate tourniquets for durations of no more than thirteen minutes on average.[17][5] Paralysis with a tourniquet can occur in as little as seven minutes.[18] WALANT eliminates the tourniquet risks and brachial plexus blocks. Upper extremity muscles, neurovascular structures, and skin are less likely to be damaged. The surgery can be performed in the upright position if necessary to avoid acute respiratory compromise in patients with obstructive sleep apnea, COPD, or CHF. Injections and the surgery are performed in separate rooms to speed up room turnover, as the injections can be completed in the preoperative area.[19]

WALANT allows the surgeon to make a diagnosis more accurately. Intraoperative assessments are particularly advantageous with flexor tendon repairs, as it is more challenging to gauge tension without patient participation.[20] Gapping is one of the most common complications of flexor tendon repairs, occurring more than 7% of the time.[20] It is linked to tendon rupture (6% prevalence), adhesions, and worsening tendon strength.[21][22] It is critical to maintain a gap of less than 3 mm to minimize poor outcomes. WALANT provides a more accurate assessment of gapping through active patient participation during the repair. This can save a return trip to the surgeon's office, as tendon "bunching" against suture can result in rupture once the active range of motion begins postoperatively.[20][23]

Patient satisfaction and better allocation of resources are the most significant postoperative benefits of WALANT. Studies by Tan (2020) and Rhee (2017) reported that 94% of patients would choose WALANT again in the future. Patients have decreased pain postoperatively in comparison to sedation with a tourniquet. Tahir in 2020 reported that distal radius fractures using WALANT healed more rapidly.[3] WALANT facilitates better communication between the patient and the surgical team, promoting understanding, compliance, and injury prevention postoperatively.[11][2] Less time is spent in the postoperative phase, decreasing costs for the facility and patient.[1][5][2][12] Patients can safely drive themselves home after the procedure.[16] Postoperative opioid consumption is equivalent or decreased with WALANT.[24]

Contraindications

Absolute

  • Lack of consent
  • Uncooperative (more common with children)[2][3]

Relative[3][7][13][7][3]

  • Anxious
  • Needle-phobia
  • Peripheral vascular disease
  • Hypercoagulable
  • Lidocaine hypersensitivity
  • Ongoing infection
  • Polytrauma
  • Lack of proper staff, training, facilities
  • Language/cultural differences, deaf
  • Liver disease[19]
  • Anticoagulants* (controversial)
  • Preference for general anesthesia
  • Inability to lay supine (history of back pain, OSA, et al.)

Equipment

Procedure rooms should be equipped with adequate lighting and have a headlamp available. Position an ergonomic chair appropriately for the injection to minimize a vasovagal response.[5][2] Pillows are helpful for chronic back and neck pain. Resuscitation equipment should be on hand to perform BLS or ACLS if needed and smelling salts for syncopal events. Sterile equipment includes instrument peel packs, gloves, towels, chlorhexidine/iodine solutions.[2] A smaller needle size (25 to 27 gauge) is ideal for two reasons: it is less painful penetrating the skin and prevents high injection rates of acidic lidocaine uncomfortable for the patient.[1][11]

The most common analgesic-hemostasis mixture is 1% lidocaine with 1:100,000 epinephrine.[2][5][1] Other lidocaine-epinephrine ratios have also shown efficacy in tendon repair of the wrist (1:400,000) and with fracture manipulation (1:1,000,000).[1][20] Optional 8.4% bicarbonate mixed in 1 ml:10 ml fashion with the lidocaine-epinephrine solution functions well as a buffer solution to diminish lidocaine acidity during the injection.[5][25] Bupivacaine can be added to the lidocaine-epinephrine mixture for cases with durations greater than 2.5 hours.[5] Phentolamine reversal should always be available and given as 1 g diluted in 1 to 10 ml of 0.9% normal saline.[13]

Personnel

Well-trained personnel must facilitate all three perioperative phases of WALANT surgery to maximize workflow and patient outcomes.[2] The interdisciplinary team includes the surgeon, a "distractive anesthesia" team member to minimize patient anxiety, scrub tech, first assist, circulating nurse, and hand therapist.[3][2][11]

Preparation

Patients should arrive at least thirty minutes before the procedure start time. Assume patients are unfamiliar with medical terminology and anxious about being awake. Therefore all communication should be through simple language.[2] Given the COVID epidemic, minimize exposures through PPE at all times, avoid overlap of patients in waiting rooms and staff only as necessary.[4]

Administer lidocaine-epinephrine approximately thirty minutes before incision time.[2][13][19] Move the patient into the procedure room fifteen minutes beforehand.[2] Have 1 g phentolamine in 10 ml of 0.9% normal saline available if epinephrine reversal is needed.[13] Utilize bicarbonate buffer for procedures requiring more local anesthetic.[11] Cefazolin is the standard perioperative antibiotic prophylaxis.[1] Keep extra 1% lidocaine with epinephrine available if pain control or hemostasis is initially inadequate.[3] Research has found a high safety profile in measuring vital signs, EBL, and VAS scores in 10-minute intervals throughout the procedure. Surgeons instruct patients on intraoperative testing as well as education on post-op care.[3] Hand therapists can often assist with splint placement at the end of the procedure.[2]

Vital signs should be taken every thirty minutes for the first few hours postoperatively.[3] A typical discharge pain regimen includes PO tramadol 37.5/325mg acetaminophen BID combination for ten days and calcium supplements.[3][1] In general, most post-operative rehabilitation involves early protective movement, and patients should avoid doing anything painful without a hand therapist present.[11]

Technique or Treatment

The three main principles of WALANT are pain control with lidocaine, bleeding control with epinephrine, and anxiety control with technique and ambiance (Ilyas, FORE lecture 2018).

Inject the patient while they sit upright to avoid a potential vasovagal response.[5] Keep the needle as still as possible, and inject at an angle perpendicular to the skin.[11] Move the extremity towards the needle instead of pushing the needle into the skin to decrease discomfort. Inject up to 10 ml just beneath the skin and antegrade, maintaining at least one centimeter of local wheel ahead of the advancing needle tip at all times. Reinsert the needle into areas already numbed for repeat injections. When done correctly, patients should only feel pain with the initial injection.[11]

  • Carpal tunnel release - 10 ml injection 5 mm proximal to wrist crease and 5 mm ulnar to the median nerve, and an additional 10 ml injected deep to the incision site
  • Trigger finger - 4 ml injection into subcutaneous tissue just deep to the incision site. Avoid injection into the sheath.
  • Finger sensory block - 2 ml injection into the dorsal or volar aspect of proximal phalanx distal to finger-palm crease[5]
  • Metacarpal fractures - 40 ml circumferentially around metacarpal
  • Dupuytren's contracture - 10 ml injection into palm, 2 ml into proximal phalanx, 2 ml middle phalanx[5]
  • ORIF distal radius - 5 ml injection into distal radius fracture. 10 ml into volar or dorsal distal radius. Use a more concentrated 1:40,000 1% lidocaine-epinephrine as it is a procedure that requires more hemostasis. For volar plating, inject 5 l into the pronator quadratus. For dorsal plating, inject 5 ml beneath the extensor retinaculum[1]

Complications

The most common adverse reaction associated with WALANT is fainting secondary to a vasovagal response.[5] Another common reaction is increased anxiety in patients who fear being awake for the procedure. "Jitters" also can infrequently occur with lidocaine.[2] Otherwise, few adverse effects exist for WALANT.

A common myth associated with WALANT is that there is a high risk of digital ischemia with epinephrine use. This concern originated from a study using procaine-epinephrine instead of lidocaine for analgesia. Procaine has a higher incidence of digital ischemia due to its significantly lower pH than lidocaine or bupivacaine.[20] Multiple studies have reported that lidocaine-epinephrine in controlled doses is safe to use in the fingers.[20][26][27][12][25]

Epinephrine-induced cardiac ischemia is a rare complication of WALANT.[28] Lidocaine seldom causes significant adverse effects. However, seizures and altered mentation have been reported with intravascular administration.[29][5] Intravascularly administered bupivacaine-induced cardiotoxicity and death are also exceedingly rare. Unlike lidocaine, the analgesic effects of bupivacaine wear off before the paresthesia.[5]

Clinical Significance

WALANT hand surgery enhances patient safety by eliminating the risks associated with sedation and tourniquet. Its minimalistic approach makes it ideal in an ambulatory setting, minimizing healthcare disparities through better healthcare access. Patients living far from the hospital or in a healthcare-poor region can have access to surgical care. Other benefits include decreased patient cost, less time spent out of work, and less time waiting to schedule surgery.[2][11][3][7][12]

In times of the COVID-19 epidemic, WALANT provides an opportunity for patients to receive surgical care without taking up valuable OR time for emergent cases. Additionally, it decreases exposure between patients, hospital, and staff as it can be performed outside the operating room.[4][14] Regarding the opioid epidemic, WALANT has shown to have at least equivalent results in opioid consumption postoperatively compared with general sedation in an operating room.[1][24]

Enhancing Healthcare Team Outcomes

WALANT is most effective when set protocols are in place, and a multi-disciplinary approach is utilized. Staff well versed in guiding patients through the preoperative, operative, and recovery phases of surgery day in an unfamiliar ambulatory setting will maximize work efficiency and minimize anxiety.[2] Intraoperatively, a staff member in charge of providing "distracting anesthesia" improves patient satisfaction and workflow.[3] Hand therapists further promote a team atmosphere and assure the patient that they are supported.[11]

Nursing, Allied Health, and Interprofessional Team Interventions

Wide-awake Local Anesthesia No Tourniquet (WALANT) is an alternative to general anesthesia and tourniquet for undergoing surgery. General anesthesia is where the anesthesiologist sedates the patient (induces sleep) before the surgery starts in the operating room to reduce pain sensation. A tourniquet is a device that squeezes the arm to control bleeding. Instead, WALANT uses only tiny doses of lidocaine to decrease pain and epinephrine to minimize bleeding. Typically the injections take place thirty minutes before surgery starts.

The patient remains awake throughout the procedure. The surgeon asks the patient for feedback and to perform specific movements that help improve the repair. This technique is especially beneficial for patients with tendon injuries. Often a hand therapist will be present to assist with range-of-motion exercises and discuss future rehabilitation plans. Since the patient is awake, there are more opportunities to ask the surgeon questions and learn about the procedure.

WALANT can easily be performed in a surgery center or even in the surgeon's office. On the day of surgery, patients can have breakfast and drive themselves to their procedure. For patients that have severe medical conditions like congestive heart failure, WALANT may be a better alternative. Other benefits include more flexible scheduling and affordability. WALANT effectively treats many conditions affecting the hand, such as carpal tunnel syndrome, trigger finger, and wrist fractures.

References


[1]

Huang YC, Hsu CJ, Renn JH, Lin KC, Yang SW, Tarng YW, Chang WN, Chen CY. WALANT for distal radius fracture: open reduction with plating fixation via wide-awake local anesthesia with no tourniquet. Journal of orthopaedic surgery and research. 2018 Aug 6:13(1):195. doi: 10.1186/s13018-018-0903-1. Epub 2018 Aug 6     [PubMed PMID: 30081923]


[2]

Tan E, Bamberger HB, Saucedo J. Incorporating Office-Based Surgery Into Your Practice With WALANT. The Journal of hand surgery. 2020 Oct:45(10):977-981. doi: 10.1016/j.jhsa.2020.07.003. Epub 2020 Aug 21     [PubMed PMID: 32839051]


[3]

Tahir M, Chaudhry EA, Zaffar Z, Anwar K, Mamoon MAH, Ahmad M, Jamali AR, Mehboob G. Fixation of distal radius fractures using wide-awake local anaesthesia with no tourniquet (WALANT) technique: A randomized control trial of a cost-effective and resource-friendly procedure. Bone & joint research. 2020 Jul:9(7):429-439. doi: 10.1302/2046-3758.97.BJR-2019-0315.R1. Epub 2020 Jul 1     [PubMed PMID: 32905335]

Level 1 (high-level) evidence

[4]

Hobday D, Welman T, O'Neill N, Pahal GS. A protocol for wide awake local anaesthetic no tourniquet (WALANT) hand surgery in the context of the coronavirus disease 2019 (COVID-19) pandemic. The surgeon : journal of the Royal Colleges of Surgeons of Edinburgh and Ireland. 2020 Dec:18(6):e67-e71. doi: 10.1016/j.surge.2020.06.015. Epub 2020 Jun 30     [PubMed PMID: 32631702]


[5]

Lalonde DH, Wong A. Dosage of local anesthesia in wide awake hand surgery. The Journal of hand surgery. 2013 Oct:38(10):2025-8. doi: 10.1016/j.jhsa.2013.07.017. Epub 2013 Sep 8     [PubMed PMID: 24021739]


[6]

Maliha SG, Cohen O, Jacoby A, Sharma S. A Cost and Efficiency Analysis of the WALANT Technique for the Management of Trigger Finger in a Procedure Room of a Major City Hospital. Plastic and reconstructive surgery. Global open. 2019 Nov:7(11):e2509. doi: 10.1097/GOX.0000000000002509. Epub 2019 Nov 20     [PubMed PMID: 31942301]


[7]

Far-Riera AM, Pérez-Uribarri C, Sánchez Jiménez M, Esteras Serrano MJ, Rapariz González JM, Ruiz Hernández IM. Prospective study on the application of a WALANT circuit for surgery of tunnel carpal syndrome and trigger finger. Revista espanola de cirugia ortopedica y traumatologia (English ed.). 2019 Nov-Dec:63(6):400-407. doi: 10.1016/j.recot.2019.06.006. Epub 2019 Aug 28     [PubMed PMID: 31471242]


[8]

Garmon EH, Huecker MR. Topical, Local, and Regional Anesthesia and Anesthetics. StatPearls. 2023 Jan:():     [PubMed PMID: 28613644]


[9]

Lanza F, Beretz A, Stierlé A, Hanau D, Kubina M, Cazenave JP. Epinephrine potentiates human platelet activation but is not an aggregating agent. The American journal of physiology. 1988 Dec:255(6 Pt 2):H1276-88     [PubMed PMID: 3202191]


[10]

Spalding A, Vaitkevicius H, Dill S, MacKenzie S, Schmaier A, Lockette W. Mechanism of epinephrine-induced platelet aggregation. Hypertension (Dallas, Tex. : 1979). 1998 Feb:31(2):603-7     [PubMed PMID: 9461228]


[11]

Lalonde DH. Latest Advances in Wide Awake Hand Surgery. Hand clinics. 2019 Feb:35(1):1-6. doi: 10.1016/j.hcl.2018.08.002. Epub     [PubMed PMID: 30470325]

Level 3 (low-level) evidence

[12]

Pires Neto PJ, Ribak S, Sardenberg T. Wide Awake Hand Surgery Under Local Anesthesia No Tourniquet in South America. Hand clinics. 2019 Feb:35(1):51-58. doi: 10.1016/j.hcl.2018.08.005. Epub     [PubMed PMID: 30470331]


[13]

Rhee PC, Fischer MM, Rhee LS, McMillan H, Johnson AE. Cost Savings and Patient Experiences of a Clinic-Based, Wide-Awake Hand Surgery Program at a Military Medical Center: A Critical Analysis of the First 100 Procedures. The Journal of hand surgery. 2017 Mar:42(3):e139-e147. doi: 10.1016/j.jhsa.2016.11.019. Epub 2016 Dec 20     [PubMed PMID: 28011033]


[14]

Thakkar M, Bednarz B. Should WALANT surgery be included in the training curriculum? Journal of plastic, reconstructive & aesthetic surgery : JPRAS. 2020 Aug:73(8):1575-1592. doi: 10.1016/j.bjps.2020.05.072. Epub 2020 May 26     [PubMed PMID: 32507703]


[15]

Duquette S, Nosrati N, Cohen A, Munshi I, Tholpady S. Decreased wait times after institution of office-based hand surgery in a Veterans Administration setting. JAMA surgery. 2015 Feb:150(2):182-3. doi: 10.1001/jamasurg.2014.1239. Epub     [PubMed PMID: 25536462]


[16]

Thompson Orfield NJ, Badger AE, Tegge AN, Davoodi M, Perez MA, Apel PJ. Modeled Wide-Awake, Local-Anesthetic, No-Tourniquet Surgical Procedures Do Not Impair Driving Fitness: An Experimental On-Road Noninferiority Study. The Journal of bone and joint surgery. American volume. 2020 Sep 16:102(18):1616-1622. doi: 10.2106/JBJS.19.01281. Epub     [PubMed PMID: 32544121]


[17]

Hutchinson DT, McClinton MA. Upper extremity tourniquet tolerance. The Journal of hand surgery. 1993 Mar:18(2):206-10     [PubMed PMID: 8463580]


[18]

Ki Lee S, Gul Kim S, Sik Choy W. A randomized controlled trial of minor hand surgeries comparing wide awake local anesthesia no tourniquet and local anesthesia with tourniquet. Orthopaedics & traumatology, surgery & research : OTSR. 2020 Dec:106(8):1645-1651. doi: 10.1016/j.otsr.2020.03.013. Epub 2020 Jul 4     [PubMed PMID: 32631713]

Level 1 (high-level) evidence

[19]

Leblanc MR, Lalonde J, Lalonde DH. A detailed cost and efficiency analysis of performing carpal tunnel surgery in the main operating room versus the ambulatory setting in Canada. Hand (New York, N.Y.). 2007 Dec:2(4):173-8. doi: 10.1007/s11552-007-9043-5. Epub 2007 May 30     [PubMed PMID: 18780048]


[20]

Nodwell T, Lalonde D. How long does it take phentolamine to reverse adrenaline-induced vasoconstriction in the finger and hand? A prospective, randomized, blinded study: The Dalhousie project experimental phase. The Canadian journal of plastic surgery = Journal canadien de chirurgie plastique. 2003 Winter:11(4):187-90     [PubMed PMID: 24009436]

Level 1 (high-level) evidence

[21]

Zhao C, Amadio PC, Tanaka T, Kutsumi K, Tsubone T, Zobitz ME, An KN. Effect of gap size on gliding resistance after flexor tendon repair. The Journal of bone and joint surgery. American volume. 2004 Nov:86(11):2482-8     [PubMed PMID: 15523022]


[22]

Chauhan A, Palmer BA, Merrell GA. Flexor tendon repairs: techniques, eponyms, and evidence. The Journal of hand surgery. 2014 Sep:39(9):1846-53. doi: 10.1016/j.jhsa.2014.06.025. Epub     [PubMed PMID: 25154573]


[23]

Lalonde DH, Kozin S. Tendon disorders of the hand. Plastic and reconstructive surgery. 2011 Jul:128(1):1e-14e. doi: 10.1097/PRS.0b013e3182174593. Epub     [PubMed PMID: 21701291]


[24]

Miller A, Kim N, Ilyas AM. Prospective Evaluation of Opioid Consumption Following Hand Surgery Performed Wide Awake Versus With Sedation. Hand (New York, N.Y.). 2017 Nov:12(6):606-609. doi: 10.1177/1558944716677536. Epub 2016 Nov 28     [PubMed PMID: 29091490]


[25]

Frank SG, Lalonde DH. How acidic is the lidocaine we are injecting, and how much bicarbonate should we add? The Canadian journal of plastic surgery = Journal canadien de chirurgie plastique. 2012 Summer:20(2):71-3     [PubMed PMID: 23730153]


[26]

Denkler K. A comprehensive review of epinephrine in the finger: to do or not to do. Plastic and reconstructive surgery. 2001 Jul:108(1):114-24     [PubMed PMID: 11420511]


[27]

Thomson CJ, Lalonde DH, Denkler KA, Feicht AJ. A critical look at the evidence for and against elective epinephrine use in the finger. Plastic and reconstructive surgery. 2007 Jan:119(1):260-266. doi: 10.1097/01.prs.0000237039.71227.11. Epub     [PubMed PMID: 17255681]


[28]

Cunnington C, McDonald JE, Singh RK. Epinephrine-induced myocardial infarction in severe anaphylaxis: is nonselective β-blockade a contributory factor? The American journal of emergency medicine. 2013 Apr:31(4):759.e1-2. doi: 10.1016/j.ajem.2012.11.022. Epub 2013 Feb 4     [PubMed PMID: 23380109]

Level 3 (low-level) evidence

[29]

DeToledo JC. Lidocaine and seizures. Therapeutic drug monitoring. 2000 Jun:22(3):320-2     [PubMed PMID: 10850400]

Level 3 (low-level) evidence