PTH is a bone forming agent that significantly reduces the risk of osteoporotic vertebral fracture and treats it effectively, especially in multiple level fractures [6, 15, 16]. While previous studies reported that conversion to anti-resorptive agents is necessary after 2 years of PTH administration for the treatment of osteoporosis, there is no standard duration of PTH administration established for acute osteoporotic vertebral fractures [17-19]. This study compared the conservative treatment group (Group C) and the intervention treatment group (Group I). Group C was administered PTH weekly until VAS scores reached ≤3 and radiological parameters had stabilized, followed by administration of anti-resorptive agents, whereas Group I was administered oral anti-resorptive agents after percutaneous VP. Group C required an average of 9.25 ± 5.08 weeks (range, 4–22 weeks) to achieve VAS scores ≤3 and 16.44 ± 7.37 to 24.65 ± 8.75 weeks for the stabilization of radiological parameters.
Although percutaneous VP is commonly used to treat osteoporotic vertebral fractures, studies have reported that patients still experience difficulty in returning to a daily routine after this procedure [20, 21]. Although percutaneous VP is effective in relieving acute pain, it has certain limitations. Percutaneous VP showed no significant difference in symptom relief when compared to conservative treatment at 12 months after the onset of a fracture and no evident symptom relief when compared to a sham procedure [22-25]. There have been reports of interruption of bony union at the fracture site by the injected bone cement and occurrence of re-fracture at the site of cement injection [26]. The leakage of the cement injected into a fractured vertebra can cause unexpectedly severe complications [27]. In a study that compared the findings from a 3-month follow-up of patients undergoing PTH treatment or percutaneous VP, the latter significantly relieved pain in the first week and increased the height of the fractured vertebra at 3 months after the onset of the fracture. However, it did not show a significant difference in the pain level and the ability to perform daily activities after 3 months when compared to PTH treatment. Moreover, there were lower medical expenditures reported in the PTH group as compared to the percutaneous VP group [10].
Previous studies on PTH examined patients with osteoporotic vertebral fractures without dividing them according to the severity of osteoporosis, and these studies only included patients with fractures of a single vertebral body. In such cases, a sample population may predominantly consist of patients with mild to moderate osteoporotic vertebral fractures. Hence, it may appear as if the patients responded well to conservative palliative treatments, such as simple bed rest, thus limiting an accurate assessment of the effects of different treatments. In the present study, a treatment plan was selected after considering patients’ general conditions, BMD and number of fractured vertebral bodies. The current retrospective study setting included treatment groups resembling real-world patients more closely. Group C had a higher mean number of fractured vertebral bodies as compared to Group I (1.58 vs. 1.15), although the difference was not statistically significant. Including severe patients with the lowest BMD (T-score: −5.8) in Group C also emphasized the close setting to the real world.
It took an average of 9.25 weeks for the pain to reduce to a level that did not interfere with daily activities. However, it took 4–6 months (16.44–24.65 weeks) until the radiological parameters stabilized. A study that used plain radiographs and computed tomography to assess the continuity of cancellous bone showed that bony union took an average of 2.8 months to reach bony union through the weekly administration of PTH [13]. In our study, the local kyphotic angle, height of fractured vertebra, and compression rate were used instead of cancellous bone continuity to assess bony union, and the time to achieve bony union differed from that reported in previous studies. The results of this study suggest that it is advisable to continue the use of PTH in patients with osteoporotic vertebral fractures even after their VAS scores improve. Based on previous reports, it may be necessary to maintain PTH administration for 3–6 months after the initial administration. While percutaneous VP is an effective treatment option for acute osteoporotic vertebral fractures, its use is limited in patients with multiple vertebral fractures or underlying diseases, elderly patients, and cases where patients or their legal guardians do not consent to the operation. Percutaneous VP poses a severe risk of cement embolisms in patients with cardiovascular diseases.
Therefore, cement leakage and the resulting complications have been considered severe problems with percutaneous VP. Cement leakage may be asymptomatic, or it may cause complications such as pulmonary thromboembolism, nerve root and cord compression, and neurologic deficits [27, 28]. These complications were observed in this study as well. In most cases of cement leakage, patients experience no symptoms or only mild and transient symptoms. However, as observed in previous studies and this study, cement leakage can also cause lethal complications such as pulmonary thromboembolism and cement migration to the heart. These complications would most likely require additional procedures or operations, which not only places a physical burden on elderly patients, but also increases the duration of hospital stay and medical expenses. Although several protocols have been proposed to prevent cement leakage, extra caution is required when injecting cement in patients with severe osteoporotic vertebral fractures, as they are at a significant risk of cement leakage [29-31]. A previous study reported that the group receiving PTH for 3 months had significantly lower medical expenditures than the group undergoing percutaneous VP. This suggested that PTH is a good treatment option in elderly patients with severe osteoporotic vertebral fractures [10]. In this study, two cases of dizziness and two of nausea or vomiting were reported in the group that was administered PTH. However, these symptoms were not severe enough to cease treatment and were relieved through conservative treatment. The two most commonly reported side effects of PTH are dizziness and lower leg cramps. Other common side effects include nausea, arthralgia, fatigue, headache, and hypertension [32, 33]. A previous study reported that these side effects usually start in the early treatment period and rarely occur after 3 months of treatment [17]. This report is consistent with the results of the present study in which side effects occurred in the early treatment period and were relieved with conservative treatment. Hence, it is necessary to inform patients before starting the treatment that the aforementioned symptoms, albeit mild, may occur in the early treatment period in order to form a therapeutic relationship and ensure high compliance of the patients.
The limitations of this study include the single-center retrospective design, small sample size and relatively short follow-up period. A prospective randomized controlled trial for patients with severe osteoporotic vertebral fractures is warranted to understand the differences between PTH and conventional procedures, and to establish a more precise standard for PTH administration.