59 - Kyphoplasty and Vertebroplasty: A Systematic Review of 26 Clinical Studies for Height Restoration in Osteoporotic Vertebral Compression Fractures.

¹Henry Ford Health System, Detroit, MI, USA. ²Wayne State Medical School, Detroit, MI, USA

Purpose
Osteoporotic vertebral compression fractures (OVCF) are a major source of chronic and acute low back pain, with over 700,000 cases reported in the US annually. In addition to the human suffering caused by OVCF, this condition also leads to enormous economic and productivity losses in the US, with an estimated 149 million days of lost work per year and productivity losses of $100-200 billion annually. Occurring mainly in older adults with osteoporosis, OVCF are usually treated with conservative management, such as lumbosacral orthotic compressor brace/belts, calcitonin, physical therapy, bed rest, and short-duration narcotics; however, conservative approaches are ineffective for many patients. Therefore, it is crucial to know which treatments are most successful in relieving pain and restoring function for patients who are refractory to conventional treatment.
Kyphoplasty and vertebroplasty are vertebral augmentation therapies that can restore bone height, which is a major factor in alleviating the morbidity due to OVCF. While both procedures involve injection of a polymer cement into sites of fracture, kyphoplasty involves using an inflatable balloon to first make space for polymer injection. These minimally invasive procedures are recommended for patients who have OVCF but are refractory to conventional therapies. Additionally, 2017 guidelines identify other patients who may benefit from vertebral augmentation, such as those with benign bone tumors or traumatic acute vertebral compression fractures with a local kyphotic angle greater than 15 degrees.
While kyphoplasty and vertebroplasty have both been assessed in clinical trials, there is no comprehensive review comparing the two procedures that takes into consideration all clinical results. Our aim was to perform a thorough systematic review to identify the overall effectiveness of these two methods to better inform the medical community regarding which strategy would best benefit OVCF patients. Because restoration of vertebral height is a key factor associated with pain relief, we chose to assess height restoration as a primary indicator of therapeutic success. Additionally, we used restoration of function and pain relief as secondary outcomes in order to provide a comprehensive picture on how these two procedures compare.
Methods
Our systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) Protocols Statement issued in 2015. A literature search was performed to identify relevant studies using electronic databases, PubMed/MEDLINE (1954 to March 2020), Embase (1974 to March 2020), Web of Science (1954 to March 2020), Cochrane Library (including Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Reviews (1970 to March 2020), ClinicalTrials.gov (2008 to March 2020), and CINAHL (1937 to March 2020) to retrieve randomized controlled trials (RCTs).
Regarding data extraction and quality assessment, only RCTs were included. The Harden model was used to break down studies into different levels of review. Only level II studies were included, which is “One or more well powered randomized, controlled trials.”
For study selection, inclusion criteria included: patient over the age 18, studies written in English, study population of vertebral osteoporotic compression fractures, active comparator (placebo or treatment) and RCTs that had an outcome measure of height restoration with statistical significance. If the study included height restoration, we also included secondary outcomes of pain relief and functionality.
Exclusion criteria included: omitting systematic review, observational studies, case reports, editorials, case series, non-human (animal) studies, cadaver models, non-English studies, inclusion of patients with vertebral compression fractures other than osteoporosis, and studies of kyphoplasty and/or vertebroplasty that did not look at outcome measures of vertebral height restoration.
A total of 1752 articles were identified and duplicates were removed, resulting in 1248 articles. Titles and abstracts were screened, resulting in 48 articles. The full-text of these 48 articles were then assessed for eligibility, and all studies apart from RCTs for osteoporotic vertebral compression fractures without statistical analysis were removed. This resulted in a final number of 26 articles that were included in the study, with 4 of the studies specifically comparing kyphoplasty to vertebroplasty.
Results
A total of 26 RCTs were viewed. Of the 26 studies, 19 reviewed kyphoplasty, 11 reviewed vertebroplasty, and there was overlap within 4 studies that performed head-to-head comparisons of kyphoplasty and vertebroplasty.
Vertebral Height Restoration:A. Of 11 studies that investigated vertebroplasty, 2 showed less height loss after vertebroplasty, 1 showed no improvement after vertebroplasty as measured by Becks index, 4 showed improvements as percent change ratio, and all 4 studies that measured absolute vertebral height gain showed improvements.
B. Of 19 studies that assessed vertebral height restoration with kyphoplasty, none reported vertebral height loss, 10 reported vertebral height restoration, and 9 reported absolute restored vertebral height.
C. Of the few studies that compared kyphoplasty head-to-head with vertebroplasty, 1 study did not show significant anterior height restoration ratio post-operatively at 3 months for either procedure, 1 study showed significantly more vertebral body height restoration from kyphoplasty, and 1 did not find any significant increase in vertebral body height for either procedure.
Wedge, Kyphosis, and Cobbs Angle Restoration:
A. Of the 4 studies that investigated wedge angle after vertebroplasty, all showed significant post-operative improvement. One study that measured kyphoplasty showed improved but not statistically significant post-operative wedge angle.
B. While there were no studies that directly compared kyphoplasty to vertebroplasty regarding kyphosis angle restoration, 1 study reported significant improvement from vertebroplasty, and 7 studies showed improvement from kyphoplasty.
C. For Cobbs angle restoration, there were no reports that assessed with this vertebroplasty, but 7 studies of kyphoplasty showed significantly improved Cobbs angle, some with lasting changes up to 3 years.
Pain Reduction:
A. Of 9 studies that looked at preoperative and postoperative VAS scores for patients who received vertebroplasty, 7 studies reported all patients having had reduced postoperative pain scores.
B. Of 19 studies that measured kyphoplasty, all patients had reduced postoperative pain scores, with long-term follow-up showing sustained reductions in pain at 12 months and 24 months.
C. Of the 4 studies that directly compared kyphoplasty and vertebroplasty, all reported statistically significant sustained reduction in pain, with no difference between the procedures.
Restoration Of Functionality:
A. Functionality was assessed by the Oswestry Disability Index (ODI) in most studies. Of the 5 studies that looked at pre- and post-operative ODI after vertebroplasty, all showed improved functionality. For kyphoplasty, 13 of the 19 studies showed improved functionality. Only 1 study measured functionality as a comparison of both procedures and showed that all patients improved.
Conclusions
Our systematic review found evidence to support both kyphoplasty and vertebroplasty as effective treatments for OVCF. Each therapy was shown to restore some vertebral body height, reduce kyphosis angle, improve Cobbs angle, and improve the wedge angle. Importantly, both treatments also showed similar benefits for pain reduction and improved patient-reported functionality. Although fracture type and age of fracture may be important parameters influencing outcomes from kyphoplasty versus vertebroplasty, there was insufficient evidence available to make any associations between fracture type and height restoration. Also, there is a possibility that the occurrence of cement leakage, which can lead to negative outcomes, may be higher for kyphoplasty. Overall, while clinical studies have revealed multiple benefits from both methods, it was not possible to conclude whether one approach was superior to the other. However, we conclude that our results are extremely encouraging for clinicians, since both kyphoplasty and vertebroplasty are effective, viable options for treating OVCF patients who have not benefited from traditional therapies.