This before-after cohort study was approved by our institutional review board (KMUH-IRB-F(I)-20170129). Informed consent was obtained from each patient before examinations were performed. From February 2018 through May 2019, outpatients visiting the first author’s clinic for LBP with or without leg pain were recruited. The inclusion criteria were as follows: patients with LBP lasting more than six months and diagnosed with low grades (grade I and grade II, based on Meyerding classification ) of lumbar spondylolisthesis by standard lumbar anteroposterior and lateral radiographs. The exclusion criteria were as follows: age <20 years or >70 years; history of spine surgery or congenital deformity; current neurological disorder; allergy to non-steroidal anti-inflammatory drugs (NSAIDs); pregnancy; or moderate-to-severe kidney failure (³stage 3) . Demographic data were recorded, including sex, age, height, and body weight (Table 1). The presenting chief complaint for all patients was mechanical LBP, defined as worsening symptoms with standing and sitting for prolonged periods of time, or upon standing from seated position and bending forward, with/without radicular symptoms.
Analgesia drug injection
Intramuscular (IM) (deltoid muscle) injection with ketorolac 30 mg (30 mg/1 Amp) was adopted for the treatment of back pain. Vital signs, including blood pressure, heart rate, temperature, and respiration rate, were recorded within 30 minutes after the injections. Patients with abnormal vital signs were excluded from the study. Injection side effects were recorded, such as nausea/vomiting, headache, or dizziness.
Flexion extension radiography
Standing flexion-extension radiographs before and after ketorolac injections were obtained. Images were acquired on 10/17 inch digital X-ray cassettes with a film focus distance of 100 cm and at 90 KV. During the radiographic procedure, patients were asked to flex and extend their backs as much as possible with knee extension.
To evaluate the effect of IM ketorolac to relieve low back pain in studied patients, the visual analog scale (VAS) scoring system was recorded before and after analgesia.
The digital images were evaluated on the Picture Archiving and Communication System (PACS) system. We recorded and analysed the target motion segments (TS), forward or backward displacement of one vertebra over a lower vertebra, which were detected by prior standard lumbar X-rays. The radiographic measurement parameters (Fig. 1) were evaluated as follows: (1) vertebral body width (mm; “W” in Fig. 1), (2) lumbar lordosis angle (LA) (º), (3) segmental angulation (SA) (º), and (4) sagittal translation (ST) (mm). The dynamic radiographic changes before and after IM ketorolac injection included (5) dynamic lumbar lordosis (DL) (º), (6) dynamic segmental angulation (DA) (º), (7) dynamic segmental translation (DT) (mm), and (8) slip percentage (DT divided with vertebral body width; SP) (%). Except for the previously identified TS, newly recognized motion segments with listhesis after analgesia were diagnosed using different segment instability criteria as below. Segmental instability was defined as DT >4.5 mm or SP >15% in all lumbar motion segments or DA > 15º at L1/L2, L2/L3, L3/L4, or DA >20º at L4/L5, or DA >25º at L5/S1 . Radiographic parameters from the flexion-extension radiographs were measured by two observers and the mean measurement values between the two observers were adopted for analysis. The two observers were completely blinded to all information, including age, name of patients, and time of image (before or after injection).
All analyses were performed with SPSS version 19.0 (SPSS Inc., Chicago, IL, USA). Continuous variables were presented as mean ± standard deviation. A paired-t test was used to assess the difference between pre- and post-injection. P < 0.05 was considered significant. To validate the assessed data, interobserver reliability was assessed by intraclass correlation coefficient (ICC) analysis.