Comparative evaluation of an innovative deflectable percutaneous kyphoplasty versus conventional bilateral percutaneous kyphoplasty for osteoporotic vertebral compression fractures: a prospective, randomized and controlled trial

Osteoporotic vertebral compression fractures (OVCFs) can be treated with percutaneous kyphoplasty (PKP). In contrast to conventional PKP, the novel deflectable percutaneous kyphoplasty (DPKP), is a unilateral transpedicular approach procedure allowing a similar bilateral puncture effect, which owes to the deflectable curved bone expander creating a transcentral line cavity to achieve uniform distribution of cement and biomechanical balance while reducing operative time and radiation exposure.The purpose of this study was to prospectively compare and evaluate an innovative surgical procedure, DPKP, versus conventional bilateral percutaneous kyphoplasty (BPKP).This is a prospective randomized controlled trial (RCT).The totality of the participants (n=90) suffering from OVCFs between May 2019 and October 2020, were randomized by SAS 9.3 to generate a block randomization sequence, which was utilized to randomize the groups in a 1:1 ratio, assigned to the DPKP group (n=45) and the BPKP group (n=45) to undergo accordingly procedures.The primary outcome was the total operative time. The secondary outcomes included: comparative assessment of visual analog scale (VAS) scores, Oswestry disability index (ODI), kyphosis angle (KA), anterior border height (AH) of the injured vertebra, frequency of intraoperative X-ray fluoroscopy, the injection volume, distribution pattern and leakage rate of bone cement.All subjects underwent assessment by at least one senior orthopedist and radiologist for the VAS scores, ODI, KA, AH of the injured vertebra, total operative time, the injection volume, distribution pattern, leakage rate of bone cement at preoperative and 24 hours, 6 months, and 1 year postoperatively. Inclusion criteria for subjects in this prospective study were as follows: (1) 60 < age < 80 years old; (2) preoperative spinal X-ray, CT, and MRI confirmed as single-segment, fresh thoracolumbar OVCFs (T5-L5, 15% < collapse < 80%); MRI shows low signal on T1-WI and high signal on T2-WI, especially with STIR high signal characterized by vertebral edema; (3) painful OVCFs refractory to medical treatment, 2 weeks < Symptom duration < 3 months;(4) With significant physical signs of local tenderness; (5) T score of bone mineral density (BMD) < -2.5.The total operative time was significantly reduced in the DPKP group (43.3±19.58 minutes, 95% CI: 37.23-49.37) compared to the BPKP group (55.16±11.56 minutes, 95% CI: 51.78-58.54) (p<.001). Compared to the BPKP group (frequency of intraoperative X-ray fluoroscopy: 43.42±8.64, 95% CI: 40.90-45.95; the volume of bone cement injected: 5.56±0.85 mL, 95% CI: 5.31-5.81), the frequency of intraoperative X-ray fluoroscopy (30.05±17.41, 95% CI: 24.66-35.45) and volume of bone cement injected (5.08±0.97 mL, 95% CI: 4.78-5.38) significantly reduced in the DPKP group compared to the (p<.001). In addition, compared to the preoperative period, both groups showed significant improvements in the postoperative VAS scores, ODI, KA, and AH (p<.001), but there was no statistical difference between the DPKP and BPKP groups (p>.05) at any time-point. Interestingly, although without statistical differences, a tendency towards a lower rate of bone cement leakage was observed in the DPKP group.Our study results indicate that the innovative DPKP is as safe and effective as BPKP in relieving pain, improving the patient's quality of life, and reconstructing vertebral body height. Particularly, DPKP did reduce operative time and radiation exposure compared to BPKP, which correlated with unilateral and bilateral exposure procedures. Moreover, the final cement distribution was less predictable in DPKP, and further studies are warranted to clarify the advantages of DPKP versus conventional unilateral percutaneous kyphoplasty (UPKP) and BPKP.