Vertebral compression fractures are the most common and serious complication in patients with osteoporosis, causing pain that is an important cause of loss of independent living in many older adults. In recent years, with the development of minimally invasive spine techniques, such as percutaneous vertebroplasty (PVP) [1] and percutancous kyphoplasty (PKP), rapid pain relief and stabilization of the spine can be achieved; at the same time, PKP can also enable PKP can also partially reposition vertebral compression fractures and correct kyphoplasty deformities. From November 2007 to January 2009, a total of 45 PKP cases with 99 vertebrae were performed in our department. The clinical results are satisfactory and are reported below.
1. Data and Methods
1.1 Clinical data
The patients in this group, 14 males and 31 females, aged 55-94 years, average 74.5 years. The medical history ranged from 1 week to 1 year. The main symptoms were pain in the lumbar back, which was aggravated when turning and sitting, and alleviated when resting flat, requiring family care in life; percussion pain of the affected spine was obvious on physical examination, and 18 patients had obvious posterior convexity deformity, and none of them had signs of spinal nerve damage. The symptoms were not significantly relieved by bed rest and oral painkillers. Preoperative X-ray and MRI examinations were taken, combined with physical examination to determine the responsible vertebrae, iodine allergy tests were done, and there were no obvious contraindications to surgery in laboratory and systemic examinations. The specific lesioned vertebrae were as follows: T5 3, T6 5, T7 5, T8 2, T9 4, T10 8, T11 13, T12 17, Ll 15, L2 11, L3 8, L4 5, L5 3.
1.2 Methods
1.2.1 Surgical method and postoperative management
Under local anesthesia or general anesthesia with tracheal intubation, the patient was placed in prone position with padding of the upper chest and pelvis, and the abdomen was suspended. The percutaneous balloon-expanded vertebral body retrobulbar orthopedic instrumentation produced by Shandong Guanlong Company was used. Puncture was performed via the pedicle (lumbar spine) or the paravertebral arch (thoracic spine) with unilateral or bilateral access. The tip of the puncture needle is placed percutaneously under 3D-C-arm X-ray machine fluoroscopy at the outer superior edge of the vertebral arch, at the 9 or 10 o’clock position on the left side and at the 2 or 3 o’clock position on the right side. The angle and direction of needle insertion are adjusted according to the results of the frontal and lateral fluoroscopy.
The correct marker for needle insertion is the tip of the needle at the posterior edge of the vertebral body in lateral fluoroscopy and the tip of the needle at the medial edge of the pedicle in orthogonal fluoroscopy. The puncture needle is gradually advanced to the anterior middle of the vertebral body, the core is withdrawn, the guide needle is inserted, the puncture needle is withdrawn, the working cannula is placed, the fine drill is inserted through the cannula, a bone tunnel is drilled in the vertebral body under fluoroscopy, and the fine drill is removed. The balloon is placed into the bone tunnel, and lateral fluoroscopy shows its ideal location in the anterior 3/4 of the vertebral body.
Under C-arm X-ray, iodophoresis is injected into the balloon (approximately 3-4 ml at <300 psi) to expand the balloon, elevate the vertebral endplate, partially restore the vertebral body height, correct the kyphosis, and create a cavity within the vertebral body for cement filling. Iodophoranol is withdrawn and the balloon is extracted. The bone cement was mixed, and when it was cured in the shape of "toothpaste", it was slowly injected into the vertebral body at low pressure under the close supervision of a C-arm X-ray machine, and the cement was injected into each vertebral body: about 4.0 ml in the thoracic spine and about 6.0 ml in the lumbar spine. Postoperative antibiotics were administered intravenously for 3 days to prevent infection and anti-osteoporosis treatment was continued. The shortest follow-up was 3 months and the longest follow-up was 12 months, with an average of 7.6 months.
1.3 Assessment indexes
1.3.1 Visual analogue score
The visual analog scale (VAS) is a 10-cm long straight line with the left end representing no pain (0 points) and the right end representing severe pain (10 points).
1.3.2 Mobility score
1 point, no obvious difficulty in movement; 2 points, difficulty in walking; 3 points, need to use wheelchair or can only sit and stand; 4 points, forced to be bedridden.
1.3.3 Use of pain medication score
0 points no use of pain medication; 1 point use of non-steroidal anti-inflammatory pain medication; 2 points no regular use of narcotic pain medication; 3 points regular use of narcotic pain medication; 4 points intravenous or intramuscular injection of narcotic pain medication.
1.3.4 Cobb angle measurement
On the lateral X-ray film, draw a line parallel to the end plate of the vertebral body at the superior edge of the affected vertebral body and the inferior edge of the inferior vertebral body, and draw a perpendicular line with each of these two lines, and the angle Cobb angle number of the two perpendicular lines.
1.4 Statistical processing
Data were expressed as ±s, SPSS 11.0 statistical software processing, preoperative and postoperative results were performed paired t-test, and P<0.05 was judged as statistically significant difference.
2. Results
All 45 patients completed the surgery successfully, and no spinal cord, nerve, or vascular injury occurred intraoperatively, and the operating time for each vertebral body was approximately 30 minutes. There were 10 vertebral bodies with bone cement leakage, with a leakage rate of 10.1%, including 3 cases of cement leakage into the intervertebral disc, 1 case on the anterior side of the vertebral body, 2 cases on the lateral side of the vertebral body, 2 cases on the posterior side of the vertebral body, and 2 cases along the puncture channel. No clinical symptoms were observed in any of the above patients.
Postoperatively and at follow-up, VAS scores, mobility scores and scores with pain medication were significantly improved compared with preoperative scores, and pain relief and functional improvement were significant (Table 1). The difference in vertebral body height before and after surgery was statistically significant, and the Cobb angle was significantly corrected with no significant loss of angle by the time of follow-up (Table 2, Figures 1, 2, 3).
3, Discussion
Due to severe low back pain and dysfunction, patients with osteoporotic vertebral compression fractures need bed rest, wear braces, take painkillers, and have difficulty taking care of themselves, which seriously affects the survival and quality of life of patients and brings burden to society and families. PVP and PKP are effective methods for treating osteoporotic vertebral compression fractures, with a pain relief rate of more than 90% [4].
We performed PKP in 45 patients with osteoporotic vertebral compression fractures and evaluated them at clinical follow-up. Postoperatively and at follow-up, VAS scores, mobility scores, and pain medication use scores were significantly improved compared with preoperative scores, the kyphosis angle was significantly corrected compared with preoperative scores, and the spinal biologic force line was partially restored. The pain relief was satisfactory, and the patient was able to move to the floor the day after surgery, preventing bedridden complications and reducing further calcium loss, which greatly improved the patient’s quality of life.
PKP is a minimally invasive technique of the spine developed in the early 1990s on the basis of PVP. It is a percutaneous puncture through a working cannula to place an expandable balloon in the vertebral body and inject low-viscosity polymethylmethacrylate bone cement into the diseased vertebrae to achieve pain relief. The balloon is inflated by injecting a contrast agent to reset the compression fracture and restore the height of the vertebral body; and a cavity is formed in the vertebral body, which allows low-pressure injection of bone cement, reducing cement leakage and improving the safety of the procedure. Its pain relief mechanism is still not fully elucidated, and is mostly believed to be related to the following aspects.
(1) The cured bone cement increases the strength and stiffness of the vertebral body and stabilizes the vertebral body of the compression fracture;
(2) The release of heat during the polymerization of the bone cement damages the nociceptive nerve endings;
(3) Bone cement monomer is cytotoxic and damages nociceptive nerve endings;
(4) The bone cement assumed part of the axial stress, which reduced the stimulation of nerves in the vertebral body;
(5) It restores the height of the vertebral body and improves the biological force line of the spine;
(6) Correcting the kyphosis deformity and relieving the tension of the low back muscles.
The most common complications of PKP are bone cement pulmonary embolism and bone cement leakage (including intra-disc, anterior side of vertebral body, both sides of vertebral body, intra-vertebral canal and peripheral veins). There was no case of pulmonary embolism in this group; 10 vertebrae had bone cement leakage, with a leakage rate of 10.1%, among which 2 cases leaked to the posterior side of the vertebral body, both without clinical symptoms. Bone cement leakage was mainly related to the integrity of the vertebral cortex, operating technique, bone cement viscosity and filling volume.
Incomplete vertebral cortex increases the risk of cement leakage, especially in the posterior aspect of the vertebral body, which is a relative contraindication. Balloon placement should be in the anterior middle of the vertebral body to reduce damage to the posterior wall of the vertebral body. If the balloon wall is found to be close to the upper and lower endplates or the lateral wall of the vertebral body when expanding the balloon, the expansion should be stopped. Correctly grasp the timing of bone cement injection, too early injection of bone cement, because of the strong liquidity of the bone cement, easy to leak or pulmonary embolism, should be injected when the bone cement curing is “toothpaste” shape. When injecting bone cement, it should be done under the supervision of C-arm X-ray machine and injected slowly and under pressure. Once leakage of bone cement is found, the direction of injection should be changed or the injection should be stopped; when the pushing pressure is too large, the injection should be stopped.
The amount of bone cement injected should not be too much, but should be decided according to the fracture compression, balloon expansion and the feeling of injection, generally 4.0 ml for thoracic vertebrae and 6.0 ml for lumbar vertebrae. local anesthesia is used as much as possible, which not only causes little damage to the patient, but also allows timely understanding of the patient’s self-perception and observation of the sensation and movement of the patient’s lower limbs during puncture and bone cement injection.
The operating time of each vertebral body in this group of patients was about 30 minutes. The average bleeding from a single vertebral body was about 3.5 mL. The short operative time and low bleeding made this minimally invasive procedure acceptable even for frail patients. Thus, PKP is an effective treatment for osteoporotic vertebral compression fractures with minimal trauma, good safety, effective pain relief, and correction of posterior convexity deformity.