The use of outcomes instruments in the assessment of patients with idiopathic scoliosis.

Outcomes research is becoming an increasingly vital aspect of modern medicine. With current cost containment measures, the need for effective and reproducible treatment options is essential. The methodology associated with these outcomes studies is varied. Studies involving radiographic assessment can be effective with respect to instrumentation performance. However, studies that use physical parameters for outcomes do not include the patient's perception of outcome. For surgical outcome to be considered successful, patient satisfaction must be taken into account. The tools and methods used to assess patient satisfaction are complicated, as these outcomes measures must stratify the various aspects of daily living, personal perception, and overall well-being. The interpretation and analysis of these patient-perceived data can prove challenging because the variability within a group can be large based on human factors. Nonetheless, patient satisfaction should be of prime importance and should be addressed in any outcome study. An overview of the parameters and terms associated with outcomes research in the assessment of patients with scoliosis is important in order to improve existing care or aid in the evaluation of new standards of care.

Ultra high molecular weight polyethylene (UHMWPE) model can provide results comparable to cadaveric models.

The in vitro biomechanical models using a cadaveric spine specimen have long been used in understanding normal and abnormal functions of spines as well as for strength and stability testing of the spine specimen or spinal construct. Little effort has been made to describe the similarities or differences between UHMWPE and cadaveric models. Eight cadaveric lumbar spines were harvested generating six FSU and three corpectomy models. Six UHMWPE blocks were fabricated to form FSU and corpectomy models. All were tested intact, with posterior instrumentation, and with anterior instrumentation consisting of Moss-Miami 4.0 mm stainless steel rods, uni-axial stainless steel screws and DePuy Harm's cages. All models were tested in axial compression. The cadaveric model and UHMPWE model yielded axial stiffness values of comparable magnitude with respect to instrumentation applied using the posterior approach (P>0.05). Under an FSU configuration, only in the case of anterior instrumentation without the addition of a Harm's cage did both the cadaveric and UHMPWE models provide comparable axial stiffness results (P>0.05). While in vitro cadaveric models are considered the gold standard for biomechanical testing of the spine, the data suggests that under specific approaches and surgical models UHMWPE can be used to infer mechanical performance of instrumentation in cadaveric material.

Factors involved in the decision to perform a selective versus nonselective fusion of Lenke 1B and 1C (King-Moe II) curves in adolescent idiopathic scoliosis.

STUDY DESIGN: A retrospective evaluation of 203 adolescent idiopathic scoliosis patients with Lenke 1B or 1C (King-Moe II) type curves. OBJECTIVES: To evaluate the incidence of inclusion of the lumbar curve in the treatment of this type of deformity as well as radiographic factors associated with lumbar curve fusion. SUMMARY OF BACKGROUND DATA: In patients with structural thoracic curves and compensatory lumbar curves, many authors have recommended fusing only the thoracic curve (selective thoracic fusion). Studies have shown that correction of the thoracic curve results in spontaneous correction of the unfused lumbar curve; however, in some cases, truncal decompensation develops. Though there have been various attempts to define more accurately what type of curve pattern should undergo selective fusion, controversy continues in this area. METHODS: Measurements were obtained from the preoperative standing posteroanterior and side-bending radiographs of 203 patients with Lenke Type 1B or 1C curves from five sites of the DePuy AcroMed Harms Study Group. Patients were divided into two groups depending on their most distal vertebra instrumented: the "selective thoracic fusion" group included patients who were fused to L1 or above and the "nonselective fusion" group included patients fused to L2 or below. A statistical comparison was conducted to identify variables associated with the choice for a nonselective fusion. RESULTS: The incidence of fusion of the lumbar curve ranged from 6% to 33% at the different patient care sites. Factors associated with nonselective fusion included larger preoperative lumbar curve magnitude (42 +/- 10 degrees vs. 37 +/- 7 degrees, P < 0.01), greater displacement of the lumbar apical vertebra from the central sacral vertical line, (3.1 +/- 1.4 cm vs. 2.2 +/- 0.8 cm, P < 0.01), and a smaller thoracic to lumbar curve magnitude ratio (1.31 +/- 0.29 vs. 1.44 +/- 0.30, P = 0.01). CONCLUSIONS: The characteristics of the compensatory "nonstructural" lumbar curve played a significant role in the surgical decision-making process and varied substantially among members of the study group. Side-bending correction of the lumbar curve to <25 degrees (defining these as Lenke 1, nonstructural lumbar curves) was not sufficientcriteria to perform a selective fusion in some of these cases. The substantial variation in the frequency of fusing the lumbar curve (6% to 33%) confirms that controversy remains about when surgeons feel the lumbar curve can be spared in Lenke 1B and 1C curves. Site-specific analysis revealed that the radiographic features significantly associated with a selective fusion varied according to the site at which the patient was treated. The rate of selective fusion was 92% for the 1B type curves compared to 68% for the 1C curves.

The mechanical effects of suture anchor insertion angle for rotator cuff repair.

Twelve matched pairs of humerii were instrumented with suture anchor at 90 degrees, 75 degrees, 45 degrees, and 30 degrees relative to the cortical border at the junction of the greater tuberosity and articular surface. Two fixtures were inserted into each specimen at different angles and loaded to failure. Suture anchors failed at an average of 171, 219, 169, and 192 N with 90 degrees, 75 degrees, 45 degrees, and 30 degrees insertion angles, respectively. No statistical difference was detected between groups (P=.08). Although previous authors have prescribed angles < or =45 degrees to improve pull-out strength, the current in vitro data does not support these recommendations.

Histologic characterization of acute spinal cord injury treated with intravenous methylprednisolone.

OBJECTIVE: Many substances have been investigated for attenuation of spinal cord injury after acute trauma; however, pharmacologically only steroid administration has shown clinical benefits. This study attempts to characterize local spinal cord histologic response to human dose equivalent (HDE) intravenous methylprednisolone (MP) administration in a rodent model of acute spinal cord injury. DESIGN: Forty-eight Sprague-Dawley rats were divided equally into control and experimental groups. Each group was subdivided into eight sets of three animals each, according to postinjury intervals. Paraplegia after lower thoracic laminectomy was achieved using a standardized weight drop technique. INTERVENTION: Within one hour, experimental animals were treated with HDE MP followed by 23-hour continuous infusion of HDE MP. Spinal cords were harvested at variable intervals postinjury and prepared for histologic/immunohistochemistry examination. MAIN OUTCOME MEASUREMENTS: Edema, necrosis, and glial fibrillary acidic protein (GFAP) positivity in the specimens from treated/control groups were graded by microscopy and immunohistochemistry staining and compared in a blinded manner by a qualified neuropathologist and senior authors. RESULTS: Minimal differences were observed between control and MP-treated animals at zero and four hours. At eight hours, increased white matter and medullary edema was evident in control versus MP-treated rats. This trend continued through twelve, sixteen, twenty-four, forty-eight, and seventy-two hours. No difference was observed in the astrocytic response to injury by GFAP immunohistochemistry between the groups. CONCLUSIONS: Histologically, MP reduces the development of severe edema and preserves spinal cord architecture adjacent to the site of injury. In contrast, MP does not alter the development of spinal cord necrosis or astrocytic response at the zone of injury.

A multicenter study of the outcomes of the surgical treatment of adolescent idiopathic scoliosis using the Scoliosis Research Society (SRS) outcome instrument.

STUDY DESIGN: A multicenter study of the outcomes of the surgical treatment of adolescent idiopathic scoliosis using the Scoliosis Research Society Questionnaire (SRS 24). OBJECTIVE: To evaluate the patient based outcome of the surgical treatment of adolescent idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: A paucity of information exists with respect to patient measures of outcome regarding the surgical treatment of adolescent idiopathic scoliosis. To our knowledge, no prospective outcome study on this topic thus far exists. METHODS: Using the SRS 24 questionnaire, seven scoliosis centers agreed to prospectively assess outcome for surgically treated patients with adolescent idiopathic scoliosis. Data were collected before surgery and at 24 months after surgery. Data were analyzed using paired and independent samples t test for all seven SRS 24 questionnaire domains (Pain, General Self-Image, Postoperative Self-Image, Postoperative Function, Function From Back Condition, General Level of Activity, and Satisfaction) using Statistical Package for Social Science. The domains were analyzed with respect to the total cohort, gender, curve magnitude, and type of surgery using independent-samples t tests. RESULTS: A total of 242 patients were included in our analysis. A baseline preoperative pain level of 3.68 of 5 was found. This improved to 4.63 after surgery, representing an improvement of 0.95 points. Surgical intervention was associated with improving outcome when compared with preoperative status. Pain, General Self-Image, Function From Back Condition, and Level of Activity all demonstrated statistically significant improvement as compared with preoperative status (P < 0. 001). Overall, patients were highly satisfied with the results of surgery. CONCLUSION: Preoperative pain exists in our adolescent scoliosis population. Pain scores were improved in our study population at the 2-year postsurgical follow-up. Statistically significant improvements were likewise seen in the General Self-Image, Function From Back Condition, and Level of Activity domains. The present study demonstrates the ability of surgery to improve the outcome of patients afflicted with adolescent idiopathic scoliosis.

Anatomic consideration for standard and modified techniques of cervical lateral mass screw placement.

BACKGROUND CONTEXT: Posterior screw placement techniques have been previously described. Each technique differs with respect to starting point, lateral angulation and sagittal orientation. PURPOSE: To examine the potential for injury to critical anatomic structures, such as nerve roots and vertebral arteries, during posterior cervical screw placement and to determine safe screw placement. STUDY DESIGN/SETTING: An anatomic study was conducted to determine the optimal screw angulation for posterior cervical lateral mass screws. SPECIMEN SAMPLE: Ten fresh-frozen human cadaveric cervical spine specimens were used, consisting of four females and six males, ranging in age from 32 to 68 years. OUTCOME MEASURES: Angular measurements and distance from nerve root and vertebral arteries were measured with a single caliper and recorded. One millimeter of proximity to a vital structure was considered a violation of that structure. METHODS: Ten fresh-frozen human cadaveric cervical spine specimens were instrumented from C2 to C7 by a single surgeon. Kirschner wires (2.0 mm) were used to reproduce the Roy-Camille, Anderson and Magerl screw trajectories. The wire was drilled through each lateral mass, simulating overdrill error. Each technique was instrumented according to the original description and with additional modifications. The modification consisted of varying the angle of screw placement in the axial plane of the original description from 0 to 30 degrees. Distances to the closest neurovascular structures were averaged for all assays. RESULTS: The Magerl technique is safe at the standard position and modified positions of 20 degrees and 30 degrees from C3-C6. The Roy-Camille technique frequently violates neurovascular structures below C3, especially the nerve root with more lateral screw angulation. The standard technique is noted to have good bone purchase only at C2 and C3. The Anderson technique is safe at 20 degrees and 30 degrees modified positions from C3-C7. Posterior screw placement at the C7 vertebral level was safe only with a modified Anderson technique of 20 degrees and 30 degrees of lateral screw angulation. CONCLUSIONS: The present study indicates that there are significant differences of potential neurovascular injury, which is dependent on the technique used for screw entry, the level instrumented and the angle of screw trajectory in the parasagittal plane.