Abstract
We have read the letter to editor regarding our GSJ paper. We highly appreciate that the authors offered their insights regarding our paper and identified certain inadequacies within it.
Their primary concern is our method for evaluating cement leakage may underestimate incidences of it. The rate of occurrence of cement leakage is varied, with reported incidences ranging from 34.0% to 91.3%. When detected using computed tomography (CT) scanning, which is known to be superior to intraoperative fluoroscopy or postoperative radiography for evaluation of cement leakage.1,2 However, the associated health economics and radiation exposure dose are our concerns. As we known, the significance of an asymptomatic cement leakage has been widely debated. Some researchers do not treat asymptomatic leaks to be a complication. Thus, in our clinical practice, we used to apply X-ray films, not a CT scan, to evaluate cement leakage postoperatively. For those with symptomatic cement leakage, CT scan was then considered as an alternative tool.
Second, more surgical details were given as follows. Standard anteroposterior and lateral view images of the target vertebral body were obtained using C-arm fluoroscopy. A 0.5-centimeter incision was made at the skin puncture site. The entry points were located at the 10 o’clock projection on the left pedicle and 2 o’clock projection on the right, and they were confirmed by fluoroscopy. Under the monitoring of the C-arm, the puncture needle was inserted into the pedicle. Adjustments were made according to the C-arm fluoroscopy during the operation. When the needle tip reached the posterior margin of the vertebral body without penetrating the medial wall of the pedicle, the puncture was continued until the needle tip reached the anterior one-third of the vertebral body. PMMA injection was performed under the supervision of the C-arm. The injection was stopped until a satisfactory distribution of the cement or until cement leakage was noted. For T10 or above, we usually adopt unilateral puncture, and the amount of PMMA injected into each vertebral body is generally 2-4 ml. For vertebra below T10, bilateral puncture is commonly used, with the amount of injected PMMA typically ranging from 6-9 ml.
Several researchers have compared the use of unilateral and bilateral puncture techniques during PVA procedures, and their findings indicated that the amount of PMMA injected in unilateral puncture is less than bilateral puncture.3-6 Besides that, unilateral puncture was found to have advantages in decreasing the risk of PMMA leakage into the spinal canal when compared with bilateral puncture.5 6 The amount of PMMA injected in the unilateral and bilateral puncture groups of the present study is similar to that in Zhao et al.'s study. 3 As an retrospective study, we have to admitted that selection bias was hardly to avoid.
Third, in our center, the selection criteria for PKP were: (1) a local kyphotic angle >15° due to fracture, (2) significant fracture of the superior or inferior vertebral endplates, and posterior vertebral wall rupture. Prior to PMMA injection during PKP, a balloon is used to dilate within the vertebral body, creating a cavity that restores vertebral height to a certain extent. It enables PMMA to accumulate in the low-pressure cavity, reducing the risk of leakage through vertebral endplate or posterior wall fractures. In our report, none of the patients who underwent PKP experienced nerve damage. The lower PMMA leakage rate associated with PKP was considered as the main factors, other risk factors may include insufficient sample size of PKP group or selection bias.
