Isador H. Lieberman

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.

Musculoskeletal allograft risks and recalls in the United States.

&NA; There have been several improvements to the US tissue banking industry over the past decade. Tissue banks had limited active government regulation until 1993, at which time the US Food and Drug Administration began regulatory oversight because of reports of disease transmission from allograft tissues. Reports in recent years of disease transmission associated with the use of allografts have further raised concerns about the safety of such implants. A retrospective review of allograft recall data was performed to analyze allograft recall by tissue type, reason, and year during the period from January 1994 to June 30, 2007. During the study period, more than 96.5% of all allograft tissues recalled were musculoskeletal. The reasons underlying recent musculoskeletal tissue recalls include insufficient or improper donor evaluation, contamination, recipient infection, and positive serologic tests. Infectious disease transmission following allograft implantation may occur if potential donors are not adequately evaluated or screened serologically during the prerecovery phase and if the implant is not sterilized before implantation.

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.

Radiation Exposure to the Surgeon and the Patient During Kyphoplasty

Study Design Prospective study of patients who underwent single or multilevel kyphoplasty for vertebral fractures. Objective To quantify the radiation exposure to the surgeon and to the patient during kyphoplasty, and also to provide a procedural algorithm that effectively minimizes the radiation exposure to the surgeon during any fluoroscopic-guided procedure. Summary of Background Data Spine surgeons who perform minimally invasive procedures often employ fluoroscopy for intraoperative navigation. Methods Twenty-seven patients were enrolled. Two fluoroscopes (1 anterior/posterior and 1 lateral) were used for localization, navigation, and monitoring cement flow. All surgeons wore thyroid shields and lead aprons. The dose of radiation exposure was measured by dosimeter badges. One badge was attached to each patient. The surgeons wore 3 badges: under the thyroid shield (protected), under the lead apron over the left chest (protected), and outside the lead apron over the left chest (unprotected). A thermoluminescent ring dosimeter was worn on the right hand for 18 cases, and on the left hand for 9 cases. Results The exposure time was 5.7±2.0 minutes/vertebra for a single level (n=10), 3.9±0.8 minutes/vertebra for a 2 level (n=9), 2.9±1.2 minutes/vertebra for a 3 level kypholasty (n=8). The exposure time of single level kyphoplasy was significantly different from that of multilevel kyphoplasy (2 level, P=0.040; 3 level, P=0.002). Surgeon exposure as measured by the protected dosimeter was less than the minimum reportable dose (<0.010 mSv). Exposure as measured by the unprotected dosimeter, which is equivalent to deep whole body exposure was 0.248±0.170 mSv/vertebra. The eye exposure was 0.271±0.200 mSv/vertebra, and the shallow exposure (hand/skin) was 0.273±0.200 mSv/vertebra. The hand exposure was 1.744±1.173 mSv/vertebra. Conclusions Without eye or hand protection, the total radiation exposure dose to these areas would exceed the occupational exposure limit after 300 cases per year. Surgeons should wear lead lined glasses and keep their hands out of the radiation beam.

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.

Lumbar intervertebral body fusion cages: Histological evaluation of clinically failed cages retrieved from humans

BACKGROUND Although interbody cages are widely used, there is little histological documentation of the tissue within cages in the human spine. The purpose of this study was to describe the contents of retrieved, clinically failed, interbody cages from human patients, with special reference to the influence of graft type on the viability of bone in the cages. METHODS Seventy-eight cages that had been retrieved from forty-eight patients were analyzed. There were eight carbon-fiber cages and seventy threaded metal cages. Of the sixty-seven cages for which information about grafting was available, fifty-six had been packed with autograft only, six had local autograft mixed with demineralized bone matrix, four had allograft, and one had demineralized bone matrix only. The indications for cage retrieval included a failed fusion, malposition or migration of the cage, trauma (a compression fracture at the fusion site), low-back pain, progressive spondylosis, nerve-root impingement, and/or infection. The cages had been in situ for an average of twenty-two months. Undecalcified sections through the center of each plastic embedded cage were reviewed, and the approximate areas occupied by viable bone, necrotic bone, fibrocartilage, hyaline cartilage, fibrous tissue, and graft substitute were visually estimated. Debris particles were estimated by a semiquantitative scoring system. RESULTS Seventy-one of the seventy-eight cages showed evidence of vascular ingrowth and areas of histologically viable bone, representing incorporating bone graft. The average area occupied by viable bone was 44% (range, 0% to 80%). In some cages, relatively large fragments of cortical bone graft were associated with only minimal new-bone formation. Fibrocartilage occupied up to 50% of the available area in these failed cages. Some cages also contained small fibrocartilage seams connecting segments of bone in a pattern that suggested motion in vivo. In thirty-one of the seventy-eight cages, > or = 5% of the available area was occupied by hyaline cartilage, probably from vertebral end plates or facet joints. CONCLUSIONS While this study was not designed to test the efficacy of cages or of bone graft, the prevalence of hyaline and fibrocartilage in these failed cages illustrates the importance of graft and graft-site preparation to maximize bone-graft incorporation. LEVEL OF EVIDENCE Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence.

Radiation Exposure to the Surgeon During Open Lumbar Microdiscectomy and Minimally Invasive Microdiscectomy : A Prospective, Controlled Trial

Study Design. This is a prospective in vivo study comparing radiation exposure to the surgeon during 10 minimally invasive lumbar microdiscectomy cases with 10 traditional open discectomy cases as a control. Objective. Radiation exposure to the eye, chest, and hand of the operating surgeon during minimally invasive surgery (MIS) and open lumbar microdiscectomy were measured. The Occupational Exposure Guidelines were used to calculate the allowable number of cases per year from the mean values at each of the 3 sites. Summary of Background Data. Fluoroscopy is a source of ionizing radiation and as such, is a potential health hazard with continued exposure during surgery. Presently, radiation exposure to the surgeon during MIS lumbar microdiscectomy is unknown. Methods. Radiation exposure to the surgeon (millirads [mR]) per case was measured by digital dosimeters placed at the level of the thyroid/eye, chest, and dominant forearm. Other data collected included operative side and level, side of the surgeon, side of the x-ray source, total fluoroscopy time, and energy output. Results. The average radiation exposure to the surgeon during open cases was thyroid/eye 0.16 ± 0.22 mR, chest 0.21 ± 0.23 mR, and hand 0.20 ± 0.14 mR. During minimally invasive cases exposure to the thyroid/eye was 1.72 ± 1.52 mR, the chest was 3.08 ± 2.93 mR, and the hand was 4.45 ± 3.75 mR. The difference between thyroid/ eye, chest, and hand exposure during open and minimally invasive cases was statistically significant (P = 0.010, P = 0.013, and P = 0.006, respectively). Surgeons standing in an adjacent substerile room during open cases were exposed to 0.2 mR per case. Conclusion. MIS lumbar microdiscectomy cases expose the surgeon to significantly more radiation than open microdiscectomy. One would need to perform 1623 MIS microdiscectomies to exceed the exposure limit for whole-body radiation, 8720 cases for the lens of the eye, and 11,235 cases for the hand. Standing in a substerile room during x-ray localization in open cases is not fully protective.

Radiation exposure to the surgeon during percutaneous pedicle screw placement.

Study Design In-vitro radiation exposure study. Objective To determine the radiation exposure to the eyes, extremities, and deep tissue during percutaneous pedicle screw placement. Summary of Background Data Image-guided minimally invasive spinal surgery is typically performed with the use of fluoroscopy, exposing the surgeon and patient to ionizing radiation. The radiation dose to the surgeon has not been reported and risk to the surgeon performing this procedure over the long term is uncertain. Methods Percutaneous pedicle screws were placed in a cadaveric specimen from L2-S1 bilaterally using a cannulated pedicle screw system. Two fluoroscopes were used in the anteroposterior and lateral planes. The surgeon wore a thermolucent dosimeter ring on the right hand and badge over the left chest beneath the lead apron. Complete surgical time was recorded and a computed tomography scan was performed to assess screw placement. Radiation exposure was measured for total time of fluoroscopy use; average exposure per screw, surgical level, and dose to the eyes was calculated. This data was used to define the safety of percutaneous pedicle screw placement. Results Total fluoroscope time for placement of 10 percutaneous pedicle screws was 4 minutes 56 seconds (29 s per screw). The protected dosimeter recorded less than the reportable dose. The ring dosimeter recorded 103 mREM, or 10.3 mREM per screw placed. All screws were within the bone confines with acceptable trajectory. Exposure to the eyes was 2.35 mREM per screw. Conclusions On the basis of this data, percutaneous pedicle screw placement seems to be safe. A surgeon would exceed occupational exposure limit for the eyes and extremities by placing 4854 and 6396 screws percutaneously, respectively. Lead protected against radiation exposure during screw placement. The “hands-off” technique used in this study is recommended to minimize radiation exposure. Lead aprons, thyroid shields, and leaded glasses are recommended for this procedure.