Mary Kay Reinhardt

Initial outcome and efficacy of "kyphoplasty" in the treatment of painful osteoporotic vertebral compression fractures.

Study Design. An Institutional Review Board-approved Phase I efficacy study of inflatable bone tamp usage in the treatment of symptomatic osteoporotic compression fractures. Objectives. To evaluate the safety and efficacy of inflatable bone tamp reduction and cement augmentation, “kyphoplasty,” in the treatment of painful osteoporotic vertebral compression fractures. Summary of Background Data. Osteoporotic compression fractures can result in progressive kyphosis and chronic pain. Traditional treatment for these patients includes bed rest, analgesics, and bracing. Augmentation of vertebral compression fractures with polymethylmethacrylate, “vertebroplasty,” has been used to treat pain. This technique, however, makes no attempt to restore the height of the collapsed vertebral body. Kyphoplasty is a new technique that involves the introduction of inflatable bone tamps into the vertebral body. Once inflated, the bone tamps restore the vertebral body back toward its original height while creating a cavity that can be filled with bone cement. Patients and Methods. Seventy consecutive kyphoplasty procedures were performed in 30 patients. The indications included painful primary or secondary osteoporotic vertebral compression fractures. Mean duration of symptoms was 5.9 months. Symptomatic levels were identified by correlating the clinical data with MRI findings. Perioperative variables and bone tamp complications or issues were recorded and analyzed. Preoperative and postoperative radiographs were compared to calculate the percentage height restored. Outcome data were obtained by comparing preoperative and latest postoperative SF-36 data. Results. At the completion of the Phase I study there were no major complications related directly to use of this technique or use of the inflatable bone tamp. In 70% of the vertebral bodies kyphoplasty restored 47% of the lost height. Cement leakage occurred at six levels (8.6 %). SF-36 scores for Bodily Pain 11.6–58.7, (P = 0.0001) and Physical Function 11.7–47.4, (P = 0.002) were among those that showed significant improvement. Conclusions. The inflatable bone tamp was efficacious in the treatment of osteoporotic vertebral compression fractures. Kyphoplasty is associated with early clinical improvement of pain and function as well as restoration of vertebral body height in the treatment of painful osteoporotic compression fractures.

Vertebroplasty and kyphoplasty for osteolytic vertebral collapse.

As many as 70% of patients with cancer and multiple myeloma initially present with osteolytic involvement of the spine. These vertebral fractures are associated with significant morbidity and mortality and represent a tremendous personal and societal burden. Traditional medical and surgical options often are inadequate or too invasive for this population debilitated by cancer. Vertebroplasty involves the injection of polymethylmethaerylate to strengthen a vertebra. This minimally invasive method, which has been adopted by practitioners during the past decade to treat symptomatic osteoporotic compression fractures is reported to provide quick pain relief in 90% of patients, with only infrequent, mostly minor, complications. In patients with osteolytic fractures, vertebroplasty is associated with an increased rate of cement leak and less predictable pain relief. Kyphoplasty is an extension of vertebroplasty that uses an inflatable bone tamp to restore the vertebral body toward its original height while creating a cavity to be filled with bone cement. Preliminary data indicate that kyphoplasty is a safe procedure associated with a lower risk of cement leak, restoration of vertebral body height, and sagittal spinal alignment. In patients with osteolytic fractures secondary to multiple myeloma, kyphoplasty yields quick pain relief, and is associated with a statistically significant improvement in generic health outcome measures.

Bone-mounted miniature robotic guidance for pedicle screw and translaminar facet screw placement: Part I--Technical development and a test case result.

OBJECTIVE:To introduce a new miniature robot (SpineAssist; MAZOR Surgical Technologies, Caesarea, Israel) that has been developed and tested as a surgical assistant for accurate percutaneous placement of pedicle screws and translaminar facet screws. METHODS:Virtual projections in three planes—axial, lateral, and anteroposterior—are reconstructed for each vertebra from a preoperative computed tomographic (CT) scan. On a specially designed graphic user interface with proprietary software, the surgeon plans the trajectory of the screws. Intraoperative fluoroscopic x-rays with targeting devices are then matched with the CT-based virtual images, as well as the surgeons plan. A clamp is attached to the spinous process or a minimally invasive frame (Hover-T frame; MAZOR Surgical Technologies) is mounted to the iliac crest and one spinous process. The miniature robot is then attached to the clamp and/or frame. On the basis of combined CT scan and fluoroscopic data, the robot aligns itself to the desired entry point and trajectory, as dictated by the surgeons preoperative plan. RESULTS:A test case in a cadaver lumbar spine was performed in which four screws and two rods were inserted, using a minimally invasive technique, combining the SpineAssist system and Hover-T frame in conjunction with the PathFinder system (Spinal Concept Inc., Austin, TX). The discrepancy between the planned and actual screw trajectories was measured by means of postprocedural CT scan. Overall, the four screws were implanted with an average deviation of 1.02 ± 0.56 mm (range, 0–1.5 mm) from the surgeons plan. CONCLUSION:These preliminary results confirm the systems accuracy and support its use in minimally invasive spine surgery applications.

Bone-mounted miniature robotic guidance for pedicle screw and translaminar facet screw placement: part 2--Evaluation of system accuracy.

OBJECTIVE To evaluate the accuracy of a novel bone-mounted miniature robotic system for percutaneous placement of pedicle and translaminar facet screws. METHODS Thirty-five spinal levels in 10 cadavers were instrumented. Each cadavers entire torso was scanned before the procedure. Surgeons planned optimal entry points and trajectories for screws on reconstructed three-dimensional virtual x-rays of each vertebra. Either a clamp or a minimally invasive external frame was attached to the bony anatomy. Anteroposterior and lateral fluoroscopic images using targeting devices were obtained and automatically registered with the virtual x-rays of each vertebra generated from the computed tomographic scan obtained before the procedure. A miniature robot was mounted onto the clamp and external frame and the system controlled the robots motions to align the cannulated drill guide along the planned trajectory. A drill bit was introduced through the cannulated guide and a hole was drilled through the cortex. Then, K-wires were introduced and advanced through the same cannulated guide and left inside the cadaver. The cadavers were scanned with computed tomography after the procedure and the systems accuracy was evaluated in three planes, comparing K-wire positions with the preoperative plan. A total of fifty-five procedures were evaluated. RESULTS Twenty-nine of 32 K-wires and all four screws were placed with less than 1.5 mm of deviation; average deviation was 0.87 ± 0.63 mm (range, 0–1.7 mm) from the preoperative plan in this group. Sixteen of 19 K-wires were placed with less than 1.5 mm of deviation. There was one broken and one bent K-wire. Another K-wire was misplaced because of collision with the previously placed wire on the contralateral side of the same vertebra because of a mistake in planning, resulting in a 6.5-mm deviation. When this case was excluded, average deviation was 0.82 ± 0.65 mm (range, 0–1.5 mm). CONCLUSION These results verify the systems accuracy and support its use for minimally invasive spine surgery in selected patients.

Functional outcomes of kyphoplasty for the treatment of osteoporotic and osteolytic vertebral compression fractures

IntroductionVertebral body compression fractures secondary to osteoporosis or malignant osteolysis are an increasingly common problem. The primary purpose of our study was to assess functional outcomes of kyphoplasty for the treatment of osteoporotic and osteolytic vertebral compression fractures. Our secondary purpose was to compare such functional outcomes in patients with osteoporosis versus multiple myeloma.MethodsThe 314 consecutive patients prospectively included in our study had progressive and painful compression fractures as a result of osteoporosis or multiple myeloma that were refractory to nonoperative modalities. Of those 314 patients, the 211 (67.2%) patients (155 with osteoporosis and 56 with multiple myeloma) who had complete preoperative and postoperative data formed our final study group. All patients tolerated the kyphoplasty procedure well (that is, there were no adverse events in terms of perioperative patient condition). Follow-up ranged from 1 to 235 weeks (mean 55.0 weeks). Functional outcomes were assessed by the SF-36 and Oswestry Disability Index at baseline and at follow-up examinations. Data were analyzed by Student’s t-test and the level of significance was set at P≤0.05.ResultsThe average Owestry Disability Index score decreased by 12.6 points (P<0.001) in the overall group, by 11.8 points (P<0.001) at short-term follow-up, and by 8.6 points (P<0.001) at long-term follow-up. All SF-36 sub-scores except for general health and role-emotional showed statistically significant improvement from baseline values at the same time points. There was no statistically significant difference with regard to functional outcome in the osteoporosis and multiple myeloma sub-groups.ConclusionsKyphoplasty provided a safe and effective treatment for pain and disability in patients with verterbral compression fractures secondary to osteoporosis and multiple myeloma. In addition, we found no statistically significant difference with regard to functional outcome between patients with osteoporosis and multiple myeloma.

Radiographic and histologic findings of vertebral augmentation using polymethylmethacrylate in the primate spine: percutaneous vertebroplasty versus kyphoplasty.

Study Design. Animal study. Objectives. To investigate the gross behavior and the histologic effect(s) of polymethylmethacrylate (PMMA) in primate vertebral bodies after percutaneous vertebroplasty and kyphoplasty. Summary of Background Data. PMMA is known to induce thermal osteonecrosis in exposed bone during tumor surgery and total joint arthroplasty, and barium sulfate as well as PMMA are known to induce a foreign body reaction, but the effects of PMMA on vertebral cancellous bone have not been well documented. Furthermore, little is known about the mechanisms of cement extravasation that occasionally occur during these procedures. Lastly, it is not known if differences exist between vertebroplasty and kyphoplasty with regards to the above occurrences. Methods. Six living, elderly, female baboons were used in this study. Seven vertebrae from T12 to L6 were investigated in each animal. Two levels underwent vertebroplasty, two underwent kyphoplasty, and one underwent cavity creation only without cement augmentation in each animal. Three animals were killed at 24 hours and three at 26 weeks after surgery. The specimens were examined macroscopically for cement migration, and histologically for evidence of thermal necrosis, foreign body reaction, cement migration, and intravascular extravasation. Results. Small zones of osteonecrosis were observed histologically at the bone-cement interface in only two kyphoplasty (2 of 6) and two vertebroplasty specimens (2 of 5) at 26 weeks after surgery. All of these necrotic segments of bone were associated with new bone formation. Foreign body reactions were observed in all specimens at 26 weeks after surgery, yet none of them was associated with bone resorption. The incidence of cement leak into the spinal canal and adjacent soft tissues was 6 of 11 and 4 of 11 in vertebroplasty specimens and 5 of 12 and 3 of 12 in kyphoplasty specimens, respectively. There was no statistical difference in the incidence of cement leakage into the spinal canal (P = 0.54) and adjacent soft tissues (P = 0.55) between vertebroplasty and kyphoplasty specimens. The incidence of intravascular cement was significantly greater in vertebroplasty (11 of 12, 91%) than in kyphoplasty (5 of 12, 42%) (P = 0.013). Conclusions. PMMA caused relatively little necrotic exothermal effect. The presence of PMMA with barium sulfate induces a mild foreign body reaction. The use of a balloon tamp creates a void by displacing pieces of bone, which may result in a lower incidence of intravascular cement leak.

Histological evaluation of biopsies obtained from vertebral compression fractures: unsuspected myeloma and osteomalacia.

Study Design. A histological evaluation of biopsies obtained from presumed osteoporotic vertebral compression fractures (VCF) to confirm possible osteomalacia after tetracycline labeling. Objective. To describe the results of a series of biopsies obtained at the time of vertebral augmentation in presumed osteoporotic VCF, with special reference to the presence of unmineralized bone (osteomalacia) and occult or unconfirmed plasma cell dyscrasia. Summary of Background Data. Vertebral augmentation is now widely performed as a method to treat osteoporotic or osteolytic VCF. However, the influence of underlying pathology on the effect of treatment is unclear. Methods. As of October 2003, 178 biopsies were obtained from 142 patients with VCF during 246 kyphoplasty procedures. There were 110 one-level, 28 two-level, and 4 three-level biopsies. Patients included 41 men and 101 women, with an average age of 72 years (range 40–90). The patients consented to this procedure, and 25 received tetracycline (1g/day, in 2 doses separated by 6 days). Vertebral body biopsies were taken using a trephine just before the kyphoplasty procedure. The biopsies were fixed, embedded, and stained with toluidine blue and hematoxylin eosin, and were viewed with transmitted light. Unstained sections were viewed under fluorescent light to detect tetracycline labels. Results. The 178 biopsy levels included: T4 (3), T5 (1), T6 (4), T7 (13), T8 (12), T9 (8), T10 (11), T11 (17), T12 (28), L1 (25), L2 (14), L3 (13), L4 (17), and L5 (12). All specimens showed fragmented bone with variable amounts of unmineralized bone (osteoid), suggesting bone remodeling and/or fracture healing. Woven bone and cartilaginous tissue were often present, representing fracture callus formation. The biopsies obtained from 30 patients (21%), including 4 who received tetracycline, showed significantly increased osteoid, suggesting either increased bone remodeling activity or mineralization defect (osteomalacia). One sample from these 4 patients who received tetracycline showed no tetracycline labels, essentially diagnostic of osteomalacia. The biopsies also provided de-finitive diagnoses for one case of unsuspected and 3 cases of unconfirmed plasma cell dyscrasia. Conclusions. The majority of biopsies from this series of patients revealed findings consistent with various stages of fracture healing. Osteoid seams were increased in 30 patients, representing either increased bone remodeling or osteomalacia. More cases with tetracycline labeling will help elucidate the true incidence of osteomalacia in this population. As we confirmed 4 cases of plasma cell dyscrasia, we advocate a biopsy during each first-time vertebral augmentation procedure.

Kyphoplasty and vertebroplasty for the treatment of spinal metastases.

Advances in the detection and treatment of many cancers have led to prolonged life and improved quality of life for patients with localized and metastatic cancer; however, the improved survival of patients with osseous lesions, coupled with the destructive nature of metastatic disease and the medications to treat these lesions, has increased the likelihood of vertebral body collapse. Conventional surgical techniques are often poorly tolerated by this patient population, whereas nonoperative management can lead to continued pain and diminished function in the terminal years of life. Vertebroplasty and kyphoplasty are minimally invasive vertebral augmentation techniques used to treat pain in such patients while maintaining a positive safety profile. Vertebroplasty and kyphoplasty are tools in a spectrum of treatments for vertebral compression fractures secondary to osteoporosis and metastatic disease and are not mutually exclusive. Additional research in this area in large cohorts of patients is needed to establish these techniques as safe and clinically cost-effective methods of treating patients with vertebral compression fractures secondary to spinal metastases.