Edward Rainier G. Santos

Surgical treatment for the painful motion segment: matching technology with the indications: posterior lumbar fusion.

Study Design. A convenience literature-based review of the different techniques of posterior lumbar fusion. Objective. To describe the history, specific techniques, and outcomes of different methods of posterior lumbar fusion. The specific methods that were described include 1) uninstrumented posterior, posterolateral, and facet fusion, and 2) instrumented fusion using pedicle screws or facet screws. Summary of Background Data. There are various posterior fusion techniques available for the treatment of degenerative lumbar spine conditions. Each individual technique has specific technical demands, indications, advantages, and disadvantages which should be taken into consideration when performing these procedures. Methods. The published scientific literature on the different methods of posterior lumbar fusion was reviewed. The history, indications, advantages, disadvantages, and clinical and radiographic outcomes were described based on the literature search. Results/Conclusions. Posterior fusion techniques have been and will continue to be among the most commonly performed procedures in lumbar spine surgery. The different methods of fusion are well defined, as are the possible complications and outcomes. They are effective techniques when performed on appropriately selected patients by a surgeon knowledgeable in the techniques and indications. Further studies are needed regarding promising but relatively unproven developments such as minimally invasive surgery and the use of osteoinductive agents.

Magnetic resonance imaging 20 years after anterior lumbar interbody fusion.

Study Design. A 20-year magnetic resonance imaging (MRI) and functional outcome follow-up study was performed on patients who had undergone anterior lumbar interbody fusion. Objectives. The objectives of the present study are to determine whether or not degeneration is related to adjacent level fusion and the clinical significance of this degeneration. Summary of Background Data. There are concerns that lumbar fusion leads to increase stress at the adjacent levels. However, the clinical significance of this remains unclear. Methods. Thirty-nine patients who underwent lower lumbar anterior lumbar interbody fusion and who had normal preoperative discograms at the level adjacent level were evaluated with a minimum of a 20-year follow-up. MRI scans were performed and independently evaluated for any evidence of degeneration. Functional status was assessed using the Low Back Outcome Scale. Results. Twenty-nine (74.3%) patients had some evidence of degeneration in their lumbar spine and advanced degeneration was identified in 12 (30.7%) patients. Nine (23.1%) patients had advanced degeneration isolated to the adjacent level and 7 (17.9%) patients had evidence of advanced degeneration with preservation at the level adjacent to the fusion. There was no association between function and radiographic degeneration. Only 3 patients required additional surgery as a result of adjacent level degeneration. Conclusion. The prevalence of degenerative changes is similar to other studies involving normal asymptomatic subjects. Furthermore, the majority of degenerative changes seen occurred over multiple levels or at levels not adjacent to the fusion, suggesting that changes seen may be more likely related to constitutional factors as opposed to the increased stresses arising from the original fusion.

Mobile and fixed-bearing (all-polyethylene tibial component) total knee arthroplasty designs. A prospective randomized trial.

BACKGROUND Proponents of mobile-bearing total knee arthroplasty believe that it has potential advantages over a fixed-bearing design in terms of diminished wear and improved motion and/or function, but these advantages have not been demonstrated in a randomized clinical comparison to our knowledge. We conducted a patient-blinded, prospective, randomized clinical trial to compare mobile-bearing and fixed-bearing cruciate-substituting total knee arthroplasties of the same design. METHODS Patients between the ages of sixty and eighty-five years were prospectively randomized to receive a cruciate-substituting rotating-platform design or a fixed-bearing design with an all-polyethylene tibial component. There were no significant differences in the demographic characteristics (mean age, 72.2 years; mean American Society of Anesthesiologists score, 2.7; mean body mass index, 31.8 kg/m(2)) or preoperative clinical or radiographic measures between the groups. Routine clinical and radiographic follow-up measures included the Knee Society score (KSS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Short Form-36 (SF-36) outcome measures. RESULTS The results of 312 arthroplasties (136 with an all-polyethylene tibial component and 176 rotating-platform designs) in 273 patients were analyzed at a minimum of two years (mean, forty-two months) postoperatively. Although there was significant improvement in both groups, there was no significant difference between the groups with regard to the mean postoperative range of motion (110.9 degrees and 109.1 degrees, respectively; p = 0.21), the mean KSS clinical score (90.4 and 88.2 points; p = 0.168), or the mean KSS pain score (44.9 and 43.1 points; p = 0.108) at this follow-up point. There were ten revisions: seven because of infection, one because of patellar fracture, one because of instability, and one because of aseptic loosening. CONCLUSIONS The two designs functioned equivalently at the time of early follow-up in this low-to-moderate-demand patient group. The rotating-platform design had no significant clinical advantage over the design with the all-polyethylene tibial component.

Pediatric Pedicle Screw Placement Using Intraoperative Computed Tomography and 3-Dimensional Image-Guided Navigation

Study Design. A retrospective cohort study reporting the use of intraoperative computed tomography (CT) and image-guided navigation system for the placement of pedicle screws in pediatric compared with adult patients. Objective. To evaluate the accuracy of open pedicle screw placement in pediatric patients using intraoperative CT and 3-dimensional (3D) image-guided navigation. Summary of Background Data. Pedicle screws are widely used in children for the correction of spinal deformity. Navigation systems and intraoperative CT are now available as an adjunct to fluoroscopy and anatomic techniques for placing pedicle screws and verifying screw position. Methods. From 2007 to 2010, 984 pedicle screws were placed in a consecutive series cohort of 50 pediatric patients for spinal deformity correction with the use of intraoperative CT (O-arm, Medtronic, Inc, Louisville, CO) and a computerized navigation system (Stealth, Medtronic, Inc, Louisville, CO). The primary outcome measure for this study is redirection or removal of screw on the basis of the intraoperative CT imaging. During the study period, 1511 screws were placed in adult patients using the same image guidance system. Results. A total of 984 pedicle screws were implanted using real-time navigation, with a mean of 20 screws per patient (range: 2–34). On the basis of intraoperative CT, 35 screws (3.6%) were revised (27 redirected and 8 removed), representing a 96.4% accuracy rate. No patients returned to the operating room because of screw malposition. Of the 1511 screws placed in adult patients, 28 (1.8%) were revised intraoperatively for malposition on CT imaging, for an overall 98.2% accuracy rate. Screw revision thus was more common in the pediatric population (P = 0.008). However, the pediatric screw accuracy rate is significantly higher than the findings from a recent meta-analysis of predominantly nonnavigated screws in children, reporting a 94.9% accuracy rate (P = 0.03). Conclusion. We report 96.4% accuracy in pediatric pedicle screw placement using intraoperative CT and a 3D navigation system. This is similar to other reports and has better accuracy than a recent meta-analysis of nonnavigated screws in children.

All-polyethylene and metal-backed tibias have similar outcomes at 10 years: A randomized level II evidence study

The advantages of a monoblock design and lower cost have generated renewed interest in all-polyethylene tibial components for total knee arthroplasty (TKA). We hypothesized an all-polyethylene design would function equivalently to a metal-backed modular design at lower cost and at long-term followup. We report the 8- to 12-year followup of our earlier reported prospective randomized comparison of a modern congruent all-polyethylene tibial component with a modular metal-backed tibial component of the same design. The mean age of the patients was 69 years and 92% were diagnosed with osteoarthritis. Of 290 patients (316 total knee arthroplasties) enrolled, 120 patients died, 22 had revision surgery, and one was lost to followup. We followed the remaining 147 patients (167 TKAs: 97 all-polyethylene/70 metal-backed) clinically and radiographically. There were no differences in knee function (Knee Society clinical score, range of motion, stability) or radiographic parameters between the groups. Of the 22 revisions, only three were performed for tibial aseptic loosening (three metal-backed). Ten-year survivorship of the all-polyethylene tibial component was 91.6% with revision for any reason and 100% for aseptic loosening. The metal-backed tibial component survivorship was 88.9% with revision for any reason and 94.3% for aseptic loosening. The contemporary all-polyethylene tibial component functioned equivalently to its monoblock counterpart and was less costly.Level of Evidence: Level I, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

The accuracy of intraoperative O-arm images for the assessment of pedicle screw postion

Study Design. Human cadaveric study. Objective. The objective of the study was to determine the accuracy of intraoperative O-arm images in determining pedicle screw position using open dissection as the gold standard. Summary of Background Data. Pedicle screws are widely used in the treatment of various spinal disorders. Postoperative computed tomographic scans are the imaging gold standard to detect pedicle screw malposition. However, a second procedure is necessary if such malpositioned screws have to be revised. The O-arm is an intraoperative scanner that allows revision of a screw without having to return the patient to the operating room for a separate procedure. No previous studies have looked at the accuracy of intraoperative O-arm images in determining pedicle screw position. Methods. This factorial validation study utilized 9 cadavers in a comparison of intraoperative O-arm images and the dissection gold standard. Four hundred sixteen screws were inserted using 3-dimensional image (O-arm) guidance from C2 to S1. The screw positions were randomized into 3 groups: “IN” (fully contained within the pedicle), “OUT-lateral,” or “OUT-medial.” After screw insertion, O-arm images were obtained and reviewed in a blinded fashion by 3 independent observers. Dissection identified the true position of the screws. Specificity, sensitivity, positive predictive value (PPV), and negative predictive value (NPV) were calculated using dissection results as the gold standard. The interobserver reliability was also determined. Results. The overall accuracy, specificity, sensitivity, PPV, and NPV of O-arm images for the thoracic and lumbar spine were 73%, 76%, 71%, 74%, and 72%, respectively. Accuracy of surgeon perception in the cervical spine was significantly less than in the thoracic and lumbosacral spine. There was substantial interobserver agreement between the 3 readers. Conclusion. Intraoperative O-arm images accurately detect significant pedicle screw violations in the thoracic and lumbosacral spine but are less accurate for the cervical spine.

The accuracy of navigation and 3D image-guided placement for the placement of pedicle screws in congenital spine deformity.

Background: Treatment of congenital spine deformity has high surgical risk due to abnormal anatomy and dysmorphic pedicles. We hypothesized that an image-guided navigation system would result in a low rate of screw revision due to malposition. Methods: From 2007 to 2010, 142 screws were placed in 14 consecutive patients with congenital spine deformity using an intraoperative computer tomography (CT) (O-arm) and image-guided navigation system (Stealth). Mean age was 8.8 years (range, 1 to 18 y). Deformities included scoliosis (12), kyphosis (1), and spinal dysgenesis (1). Screws were placed from T2 to S1. An intraoperative CT verified screw position. Need for intraoperative screw revision is the primary outcome measure. Results: Of the 142 screws placed, 1 required revision intraoperatively due to malposition (99.3% screw accuracy rate). The screw was at L3 and was successfully redirected. There were no complications due to screw malposition. This navigated congenital screw accuracy rate (99.3%) is higher than the 94.9% accuracy rate reported for non-navigated screws in all children undergoing pedicle screw fixation in a recent systematic literature review and higher than the reported 96.4% accuracy rate for navigated pedicle screws in children. Kosmopoulos and colleagues found a lower accuracy rate (86.6%) in adult non-navigated screws (P<0.0001) and adult navigated screws (93.7%). Of note, 9 pedicles were noted on navigation to be absent. Despite the goal of bilateral screw placement at each fusion level, 31 of 173 pedicles were left unfilled due to technical impossibility based on intraoperative CT imaging. This represents an 18% screw dropout rate. Conclusions: CT-guided navigation resulted in the successful placement of 142 pedicle screws in patients with congenital deformity and altered anatomy, which represents a 99.3% screw accuracy rate. This is comparable with the screw accuracy rate of 93.7% reported for adult navigated pedicle screws. Further, navigation prevented attempts of screw placement at levels with absent or impassable pedicles. Image-guided navigation and intraoperative CT are valuable tools for the safe placement of pedicle screws in patients with significant congenital spine deformity and altered anatomy. Level of Evidence: IV, Case Series.

Comparison of Cranial Facet Joint Violation Rates Between Open and Percutaneous Pedicle Screw Placement Using Intraoperative 3-D CT (O-arm) Computer Navigation

Study Design. Retrospective study comparing cranial facet joint violation rates of open and percutaneous pedicle screws inserted using 3-dimensional image-guidance. Objective. To determine the rate of cranial facet joint violation in intraoperative computed tomography (CT) image-guided lumbar pedicle screw instrumentation and compare facet joint violation rates between CT image-guided open and percutaneous techniques. Summary of Background Data. Facet joint violation by pedicle screws can potentially result in a higher rate of adjacent segment degeneration. Reported cranial facet joint violation rates range from 7% to 100%. Intraoperative image-guidance, which has enhanced pedicle screw placement accuracy, may aid in avoiding impingement of the cranial facet joints. Methods. We reviewed 188 cases of 3-dimensional image-guided lumbar pedicle screw instrumentation from November 2006 to December 2011. The cranial screws of each construct were graded by 3 reviewers according to the Seo classification (0 = no impingement; 1 = screw head in contact/suspected to be in contact with joint; 2 = screw clearly invaded the joint) on intraoperative axial CT images. If there was a difference in evaluation, a consensus was reached to arrive at a single grade. The &khgr;2 test was used to determine significance between the open and percutaneous group (&agr; = 0.05). Results. A total of 370 screws (245 open, 125 percutaneous) were graded. Overall facet joint violation rate was 18.9% (grade 1 = 16.2%, grade 2 = 2.7%). Open technique (grade 1 = 22.4%, grade 2 = 4.1%) had a significantly higher violation rate than percutaneous technique (grade 1 = 4%, grade 2 = 0%) (P < 0.0001). There is a trend of an increasing likelihood of facet joint violation from L1 to L5. Conclusion. The use of intraoperative CT image-guidance in lumbar pedicle screw placement resulted in a facet joint violation rate at the lower end of the reported range in literature. The percutaneous technique has a significantly lower facet violation rate than the open technique. Level of Evidence: 4

Total Knee Arthroplasty in Juvenile Rheumatoid Arthritis

BACKGROUND There is a paucity of reports regarding the long-term results of total knee arthroplasty in patients with juvenile rheumatoid arthritis. The purpose of this study was to evaluate the outcome of total knee arthroplasty in patients with juvenile rheumatoid arthritis who had been followed for a minimum of twelve years. METHODS Eight consecutive patients (fifteen knees) with juvenile rheumatoid arthritis underwent total knee arthroplasty at an average age of 16.8 years. Clinical evaluation of pain status, range of motion, and the ability to walk and radiographic evaluation of the alignment of the knees and component loosening were performed preoperatively and at a mean of 15.5 years postoperatively. RESULTS All patients had substantial pain and functional limitation before the surgery, and seven of the eight patients used a wheelchair. At the time of the latest follow-up, which was after revision surgery in three patients, all of the knees were pain-free and six patients were able to walk about the community. The mean arc of motion had increased from 36 degrees to 79 degrees . The final radiographic evaluation showed that thirteen of the fifteen knees were in neutral alignment and two were in valgus. Failure, defined as revision of any of the components or definite loosening as seen radiographically, occurred in three knees. CONCLUSIONS Good results, in terms of pain relief and restoration of function, were seen at a minimum of twelve years following total knee arthroplasty in our series of patients with juvenile rheumatoid arthritis. This procedure is a reasonable option when nonoperative therapy has been inadequate for patients with severe disability and pain in this relatively young population.

New generation intraoperative three-dimensional imaging (O-arm) in 100 spine surgeries: Does it change the surgical procedure?

The O-arm (Medtronic Sofamor Danek, Inc., Memphis, TN, USA), an intraoperative CT scan imaging system, may provide high-quality imaging information to the surgeon. To our knowledge, its impact on spine surgery has not been studied. We reviewed 100 consecutive spine surgical procedures which utilized the new generation mobile intraoperative CT imaging system (O-arm). The most common diagnoses were degenerative conditions (disk disease, spondylolisthesis, stenosis and acquired kyphosis), seen in 49 patients. The most common indication for imaging was spinal instrumentation in 81 patients (74 utilized pedicle screws). In 52 (70%) of these, the O-arm was used to assess screw position after placement; in 22 (30%), it was coupled with Stealth navigation (Medtronic Sofamor Danek, Inc.) to guide screw placement. Another indication was to assess adequacy of spinal decompression in 38 patients; in 19 (50%) of these, intrathecal contrast material was used to obtain an intraoperative CT myelogram. In 20 patients O-arm findings led to direct surgeon intervention in the form of screw removal/repositioning (n=13), further decompression (n=6), interbody spacer repositioning (n=1), and removal of kyphoplasty trocar (n=1). In 20% of spine surgeries, the procedure was changed based on O-arm imaging findings. We found the O-arm to be useful for assessment of instrumentation position, adequacy of spinal decompression, and confirmation of balloon containment and cement filling in kyphoplasty. When used with navigation for image-guided surgery, it obviated the need for registration.