• Improvement in functional impairment [ Time Frame: 7 days ]
  Improvement in functional impairment as measured on the Roland-Morris Disability Questionnaire (RMQD), ranging from 0 no functional impairment to 24 severe disability
• improvement in pain score [ Time Frame: 1 hour ]
  improvement in pain score as measured on a numeric pain scale (10 point- scale ranging from 0-no pain to 10-greatest pain)
• improvement in pain score [ Time Frame: 1 day ]
  improvement in pain score as measured on a numeric pain scale (10 point- scale ranging from 0-no pain to 10-greatest pain)
• improvement in pain score as [ Time Frame: 7 days ]
  improvement in pain score as measured on a numeric pain scale (10 point- scale ranging from 0-no pain to 10-greatest pain)
• Pain Medicine consumption [ Time Frame: 7 days ]
  Pain Medicine consumption within a week from ED management.
• subsequent physician or other health professional visit related to low back pain [ Time Frame: 7 days ]
  subsequent physician or other health professional visit related to low back pain within a week from ED management.

• Improvement in functional impairment [ Time Frame: 7 days ]
  Improvement in functional impairment as measured on the 24-item RMDQ score
• improvement in pain score [ Time Frame: 1 hour ]
  improvement in pain score as measured on a numeric pain scale (ranging from 0-10)
• improvement in pain score [ Time Frame: 1 day ]
  improvement in pain score as measured on a numeric pain scale
• improvement in pain score as [ Time Frame: 7 days ]
  improvement in pain score as measured on a numeric pain scale
• Pain Medicine consumption [ Time Frame: 7 days ]
  Pain Medicine consumption within a week from ED management.
• subsequent physician or other health professional visit related to low back pain [ Time Frame: 7 days ]
  subsequent physician or other health professional visit related to low back pain within a week from ED management.

Pain relief and functional impairment have been shown to remain poor to moderate over weeks after emergency department discharge, in patients who seek ED management for acute nontraumatic, nonradicular low back pain.

The investigators made the hypothesis that ultrasound-guided interfascial infiltration of local anesthesics and corticoid is efficient and safe in treating patients presenting to the ED with acute non specific low back pain. The investigators aimed to compare early and short term functional impairment and pain relief one day and 1 week after interfacial infiltration, as compared to standard medical treatment

This is a single center observational feasibility study enrolling ED patients presenting with acute unspecific low back pain.

Ultrasound-guided interfascial infiltration is proposed to eligible patients presenting to our ED with low back pain and disability, as part of routine care. Patients receive standard medical treatment if they refuse interfascial infiltration or in case of absence or unavailability of a trained operator.

Patients were followed-up at 1 day and 7-days pots ED discharge by telephone interview conducted by an independent member of our research team not involved in patient's management

• Low Back Pain
• Acute

• Other: Interfascial infiltration

  Injection of L-bupivacaine (50 mg) and dexamethasone (4 mg) in the interfascial space under ultrasound guidance.

  Patients were kept under surveillance for at least one hour before discharge.

  Patients were discharged home with a 7 day supply of acetaminophen 1000 mg orally every 6 h, ketoprofen 100 mg, orally twice a day, and muscle relaxant as needed. Patients were instructed to take tramadol 50 mg, orally every 6h as needed for low back pain, in case of insufficient relief.

  Other Name: Interfascial injection
• Other: Standard medical treatment

  Standard medical treatment include acetaminophen, NSAIDs and muscle relaxant as first line pharmacological treatment and escalation to analgesics level II or morphine if required, as needed for low back pain, in agreement with national guidelines Route of administration (orally or iv) was let at the discretion of the attending emergency physician.

  Patients were kept under surveillance for one hour before discharge. Patients were discharged home with a 7 day supply of acetaminophen 1000 mg orally every 6h, ketoprofen 100 mg, orally twice a day, and muscle relaxant as needed. Patients were instructed to take tramadol 50 mg, orally every 6h as needed for low back pain, in case of insufficient relief.

  Other Name: Analgesic, level I and II, opioid

• Interfascial infiltration
  Injection of L-bupivacaine (50 mg) and dexamethasone (4 mg) in the interfascial space under ultrasound guidance.
  Intervention: Other: Interfascial infiltration
• Standard medical treatment
  Standard medical treatment include acetaminophen, NSAIDs and muscle relaxant as first line pharmacological treatment and escalation to analgesics level II or morphine if required, as needed for low back pain, in agreement with national guidelines Route of administration (orally or iv) was let at the discretion of the attending emergency physician.
  Intervention: Other: Standard medical treatment

Inclusion Criteria:

• adults aged between 18 and 70 years old
• presenting to the ED for low back pain from musculoskeletal origin, with symptoms evolving for less than 6 weeks,
• a score of 3 or more in the numeric pain scale (0-10)
• a score of 5 or greater on the Rolland Morris Disability Questionary (scale 0-24, RMDQ).

Exclusion Criteria:

• Traumatic or radicular pain or low back pain from alternative etiology
• allergy to local anesthetics
• Blood coagulation disorders
• Patients for whom follow-up by telephone interview was not possible
• Patients already enrolled in the study