The study protocol was approved by the Institutional Review Board and the Ethics Committee of Luohe Medical College.
Patients
We undertook a retrospective analysis of patients with thoracic and lumbar compression fracture treated with unilateral pedicle puncture PVP from our institution over a two month period (June & July 2015). 78 patients were included according to the standard. Inclusion criteria includes: ①Age from 60 to 99 years; ②Bone attenuation (T score < − 2.5) on bone densitometry; ③Collapse more than 15% of the vertebral height; ④Severe back pain related to a single-level AOVF refractory to analgesic medication; ⑤Using magnetic resonance (MR) imaging, the affected vertebral body showed a hypointense signal on T1-weighted images and hyperintense signal on T2-weighted images. The exclusion criteria included: ①Secondary osteoporosis (Corticosteroids, endocrine disorders and an inflammatory process); ②Failure to acquire informed consent; ③Uncorrected coagulopathy; ④Systemic or local spine infection; ⑤Painless AOVF; ⑥Spinal metastatic cancer; ⑦Severe comorbidities of the cardiorespiratory, hepatic, renal or neurological symptoms. Patients were divided into two groups according to surgical procedure: a flexible cement injecion group (36 cases) using a flexible-tipped bone cement injection and 3-point cement injection technique; a rigidbone cement injection group (42 cases) using a straight bone cement injection technique.
Surgical Instruments
Flexible bone cement injection equipment (Ningbo Branch Huakerun Biotechnology Co., Ltd). with angled bone cement injector. Rigid bone cement injection equipment (Shandong Guanlong Medical Products Co., Ltd).
Procedures
All the PVP procedures were performed in the operating theatre. Patients were placed prone, supported by two transverse bolsters under thorax and pelvis. Gentle distraction and extension was applied to reduce the vertebral fracture. During the procedure, a unilateral transverse process-pedicle approach was adopted with application of local anesthesia. The entry point in the vertebra was identified by fluoroscopy at the junction of the lateral edge of the pedicle s and vertebral plate. The trocar penetrated cortical bone at the lateral edge margin of the vertebral arch, and was advanced medially and inferiorly. Fluoroscopy was used to confirm that the needle tip reached the posterior wall of the vertebral body, No further advance was made beyond about 4 mm anterior to the posterior surface of the vertebral body. During the procedure all patients were observed closely with frequent fluoroscopy and the cement injection was stopped immediately if bone cement leakage occured.
When using the rigid cement injector, an 11-13G core needle was advanced from a posterolateral entry point through the involved vertebral pedicle to the junction of anterior and middle thirds of the vertebral body. The inner core was retracted and 3–4 ml PMMA was injected guided by continuous fluoroscopy. When bone cement began to fill the posterior third of the vertebral body, the injection was terminated In contrast, the flexible bone cement injection method is more involved; detailed descriptions of the process, can be found in the legend of Figs. 1 and 2.
After injection of bone cement, all injection components were withdrawn and pressure was applied to the wound for haemostasis. All the patients were observes supine for 6 hours. Next-day rehabilitation included sitting and standing as tolerated.. Bisphosphonates were generally used to treat osteoporosis after surgery.
Outcome Measures
The operation time, radiation exposure time, the amount of bone cement injection and the leakage of bone cement were recorded for each patient in two groups. Clinical assessments were evaluated before surgery, one week after surgery and 12 months after surgery. Radiographs and computed tomography (CT) scans were performed to assess the cement leakage in the vertebral body and other possible local complications, and all the complications and adverse events were recorded.
On pain measurement, VAS scores were used which ranged from 0 (no pain) to 10 (worst pain ever).Quality-adjusted life years (QALYs) and the Quality of Life Questionnaire of the European Foundation for Osteoporosis (QUALEFFO) were investigated in all patients, which comprises a 41 item questionnaire organized into5 domains (Pain, Physical Function, Social Function, General Health Perception, and Mental Function). Each domain’s score and QUALEFFO total scores are recorded on a 100- point scale, lower scores corresponding to better health-related quality of life.
Anteroposterior and lateral standing radiographs were observed to measure vertebral height and kyphotic angle of the vertebral body of all patients in three periods (preoperatively, one week after surgery, and 12 months after surgery). In the X-ray radiographs, the anterior height of the affected vertebral body and adjacent normal vertebrae were measured, and the relative anterior height (RAH) of the fractured vertebra was calculate according to the equation:.
RAH = fractured vertebral anterior height༏[(Superior vertebral anterior height + inferior vertebral anterior height)༏2] × 100%.
The kyphotic angle was based on the Phillips method, the angle between the superior endplate at one level above the fractured vertebrae and inferior endplate at one level below the fractured vertebrae were measured (Fig. 3).
Statistical Analysis
All statistical analyses were performed with the use of SPSS software, version 12 (SPSS Inc., Chicago, IL). The results were expressed as average ± SD. One-way analysis of variance (ANOVA) was used to compare the VAS scores, quality of life, RAH, and the kyphotic angle between the 2 groups. Difference in cement leakage rate of 2 groups was assessed using χ2 test. P < 0.05 was considered to have statistical significance.