Study design and selection of participants
We retrospectively analyzed data of patients with non-specific LBP lasting for more than 3 months treated in our spine surgery clinic between January 2017 and December 2018. Detailed medical history was obtained from each patient followed by a thorough physical examination by one of two spine consultants (G.G and E.B). Plain radiographs of the lumbar spine were performed in all cases. The inclusion criteria were: (1) non-specific LBP lasting for more than 3-month duration; (2) normal neurological examination with no findings of motor or sensory deficit; (3) no radicular symptoms or physical findings; (4) no “red flag” signs that may suggest a serious spine pathology (e.g., history of trauma, malignancy, fever, weight loss, neurological deficit, bladder or bowel dysfunction) ; (5) anterior-posterior and lateral lumbar spine radiographs with no pathological findings; (6) no medication prescribed; (7) an age of 18 to 65 years. Exclusion criteria were defined as: (1) radicular signs or neurological deficit; (2) previous spine injury or surgery; (4) systemic conditions which may induce pain (e.g., fibromyalgia, rheumatoid arthritis, malignancy, infection); (6) psychiatric disorders; (7) osteoporosis; (8) pregnancy; (9) incomplete medical record with missing clinical or outcome measure data. The study was approved by our Institutional Ethics Committee, the requirement for informed consent was waived.
After a diagnosis of non-specific LBP without neurological involvement was made, all patients were referred to conservative physical therapy, focusing on stretching and active core muscles strengthening. The exercise program was supervised by trained physiotherapists experienced in treating patients with musculoskeletal disorders. The physical therapy exercise program included instructional and training sessions of 45 minutes twice a week for 4-6 weeks, in which the patients were instructed how to perform core muscles stretching and strengthening exercises independently at home on a daily basis. Thereafter, all patients attended a weekly check-up exercise session for additional 4-6 weeks. A follow-up visit in our outpatient spine clinic was scheduled for 3-month time. No medication was prescribed for the study cohort.
Patients who were initially seen in our outpatient clinic by E.B, in addition to the aforementioned treatment plan, were also referred to MTrPs compression therapy. The manual therapy was performed by an expert in alternative medicine, experienced in treating patients with musculoskeletal disorders (G.P). The patients were instructed to lie down in the supine or prone position. Several MTrPs were identified over the lumbar erector spinae muscles and over the common main muscles associated with LBP (e.g., gluteus maximus, piriformis, hamstrings, quadratus lumborum, iliopsoas, tensor fascia lata) according to previously described diagnostic criteria including: (1) presence of a palpable hypersensitive taut band in the low back and associated muscles; (2) induction of pain similar to the patient's usual symptoms by compression at the MTrPs; (3) induction of pain by stretching the muscle including the MTrPs [Takamoto et al. 2015; Gerwin et al. 1997]. Manual constant pressure was applied to each MTrP for a period of 1-2 minutes at controlled intensity aiming to produce pain response ranging between comfortable pain (approximately 4/10 on a 0-10 numerical scale) to maximally tolerable pain (approximately 7/10 on a 0-10 numerical scale) [10-12]. The sequence of MTrPs compression was repeated for several times during a treatment session of 45 minutes, which was carried out once a week for 6 consecutive weeks.
Clinical outcome was assessed based on patients’ self-reported: (1) back pain during daily activity using a 0 to 10 numerical scale, where 0 indicates no pain and 10 indicates severe pain; (2) back related disability using the Oswestry Disability Index (ODI) on a 0 to 100% scale, where a higher score indicates more disability and poorer function ; and (3) SF-12 life quality questionnaire on a 0 to 100% satisfaction scale, where a higher score indicates more satisfaction and better life quality . Data was collected from the patients' medical record at the first outpatient clinic before initiating treatment and at 3-month follow-up visit (approximately 1-month after the final MTrPs compression therapy session in the MTrPs group).
Continuous parameters are presented as means ± standard deviation and categorical parameters are presented as proportions. Comparisons between the MTrPs group and the control group were performed using unpaired two-tailed t-test for continuous data and the Fisher's exact test for categorical data. Comparisons within each group between outcome measures before and after treatment were performed using paired two-tailed t-test. Data analysis was performed with the use of MedCalc Statistical Software version 19.2.6 (MedCalc Software bvba, Ostend, Belgium). A probability of less than 0.05 was considered statistically significant.