Assessment of Inter- and Intraobserver Reliability and Accuracy to Evaluate Apical Vertebral Rotation Using Four Methods: An Experimental Study Using a Saw Bone Model.

STUDY DESIGN: After placing a thoracic three-vertebra segment saw bones model on a standardized turntable, a series of anteroposterior (AP) radiographs were obtained and then set in increments to 90° rotation. Then the specimen was instrumented with 35-mm pedicle screws bilaterally and the rotation process and image acquisition were repeated. OBJECTIVE: Assess reliability and accuracy of spine surgeons evaluating apical vertebral rotation (AVR) through surgeon's visual x-ray estimation, Nash-Moe system, Upasani trigonometric method, and Upasani grading system. BACKGROUND CONTEXT: Accurate assessment of AVR is one measure surgeons can evaluate the success of intervention and potential loss of correction in scoliotic deformities. METHODS: Eighty-four representative images of uninstrumented and instrumented vertebral segments were blinded. AVR was estimated by five experienced spinal deformity surgeons using the four techniques. The surgeons' grading, estimates, and errors compared to actual rotation were calculated. Inter- and intraobserver reliability were calculated using interclass correlation (ICC). RESULTS: Each surgeon's error for simple visual estimation for uninstrumented segments was 8.7° to 17.4° (average error = 12.4°), and for instrumented segments it was 7.7° to 11.3° (average error = 9.5°). Error for the Upasani trigonometric method was -6.7° to 11.6° (average error = 0.9°). There was relatively poor accuracy for Nash-Moe system (38.2%-53.9%) compared with the Upasani grading system (76.74%-80.23%). Interobserver reliability using the Nash-Moe method was good (0.844), with intraobserver reliability from fair to excellent (0.684-0.949). Interobserver reliability for the Upasani grading method was good (0.829), with intraobserver reliability from fair to good (0.751-0.869). We found excellent interobserver reliability for Upasani trigonometric classification (0.935) with fair to excellent intraobserver reliability (0.775-0.991). The interobserver reliability of surgeons' visual estimates was good (0.898) and the intraobserver reliability from good to excellent (0.866-0.99) without pedicle screws, and interobserver reliability was excellent (0.948) and intraobserver reliability also excellent (0.959-0.986) with pedicle screws. CONCLUSIONS: We confirm that both techniques described by Upasani have good reliability and accuracy, appearing more accurate than surgeon's visual estimates or Nash-Moe system. LEVEL OF EVIDENCE: Level III.

Surgeon Reliability for the Assessment of Lumbar Spinal Stenosis on MRI: The Impact of Surgeon Experience.

BACKGROUND: Treating surgeon's visual assessment of axial MRI images to ascertain the degree of stenosis has a critical impact on surgical decision-making. The purpose of this study was to prospectively analyze the impact of surgeon experience on inter-observer and intra-observer reliability of assessing severity of spinal stenosis on MRIs by spine surgeons directly involved in surgical decision-making. METHODS: Seven fellowship trained spine surgeons reviewed MRI studies of 30 symptomatic patients with lumbar stenosis and graded the stenosis in the central canal, the lateral recess and the foramen at T12-L1 to L5-S1 as none, mild, moderate or severe. No specific instructions were provided to what constituted mild, moderate, or severe stenosis. Two surgeons were "senior" (>fifteen years of practice experience); two were "intermediate" (>four years of practice experience), and three "junior" (< one year of practice experience). The concordance correlation coefficient (CCC) was calculated to assess inter-observer reliability. Seven MRI studies were duplicated and randomly re-read to evaluate inter-observer reliability. RESULTS: Surgeon experience was found to be a strong predictor of inter-observer reliability. Senior inter-observer reliability was significantly higher assessing central(p<0.001), foraminal p=0.005 and lateral p=0.001 than "junior" group.Senior group also showed significantly higher inter-observer reliability that intermediate group assessing foraminal stenosis (p=0.036). In intra-observer reliability the results were contrary to that found in inter-observer reliability. CONCLUSION: Inter-observer reliability of assessing stenosis on MRIs increases with surgeon experience. Lower intra-observer reliability values among the senior group, although not clearly explained, may be due to the small number of MRIs evaluated and quality of MRI images.Level of evidence: Level 3.

Comparison of Surgeon Rating of Severity of Stenosis Using Magnetic Resonance Imaging, Dural Cross-Sectional Area, and Functional Outcome Scores.

OBJECTIVE: To determine the relationship between the severity of stenosis graded using both surgeons' visual assessment of spinal stenosis as well as measurement of dural cross-sectional area on magnetic resonance imaging (MRI), with the patient's disability. METHODS: Seven fellowship-trained spine surgeons reviewed MRI studies retrospectively of 30 symptomatic consecutive patients with lumbar stenosis and graded stenosis in the central canal, the lateral recess, and the foramen at T12-L1 to L5-S1 as none, mild, moderate, or severe. Dural cross-sectional area was measured at each level from T12-L1 to L5-S1. All patients completed the questionnaires for Oswestry Disability Index (ODI), Short Form 36 (SF-36), and recorded Visual Analog Scale scores for leg and back pain, and symptom severity scale of the Zurich claudication questionnaire. RESULTS: There was positive correlation between the right leg pain Visual Analog Scale score and the mean surgeon grades for central and lateral recess stenosis at L4-L5 and lateral recess stenosis at L5-S1. Except for a positive correlation between role physical score and surgeon grade for lateral recess stenosis at L5-S1, we found no correlation between the surgeons' grading of stenosis at any level with the ODI or SF-36. We found no correlation between the dural cross-sectional area with the ODI or SF-36. We did not find any correlation between the Zurich symptom severity scale and surgeons' grading of stenosis at any level. CONCLUSIONS: Although surgeons rely on visual assessment of the severity of stenosis while making surgical decisions, we found that objective and subjective imaging parameters to grade severity of stenosis did not consistently indicate the patient's disability level.

Changes in neuroforaminal height with 2 level axial presacral lumbar interbody fusion at L4-S1.

BACKGROUND: The objective was to examine the changes in neuroforaminal height at L4-L5 and L5-S1 after insertion and graduated foraminal distraction using the 2 level transsacral implant in a cadaveric model. METHODS: Discectomy and transsacral instrumentation was performed in six fresh human cadavers at L4-S1. The neuroforaminal height was measured at L4-L5 and L5-S1 before and after insertion of the implant and then at each stage of manual distraction. RESULTS: Mean L4-5 neuroforaminal height increased from 18.2 ± 3.1mm to 20.3± 2.9mm (11%) on the left and from 18.8±2.8mm to 20.6± 2.3mm (12%) on the right (P<0.05). Mean L5-S1 neuroforaminal height increased from 15.7±3.0mm to 18.4 ±2.8mm (17%) on the left and from 15.6 ±2.1mm to 18.3 ±1.8mm (17%) on the right (P<0.05). When the neuroforaminal height was plotted against amount of rotation of the screw driver it was found that the neuroforaminal height at L5-S1 increased by 1mm on average for every complete revolution of the screw driver. At least 2 full rotations of the screw driver were achieved in all cadavers. CONCLUSIONS: The transsacral screw construct distracted the disc space and neuroforaminal height in a cadaveric spine model without soft tissue envelope. During the initial process, manual control of disc space distraction predictably correlated with the increase in the neuroforaminal height to a maximum. However, further research is needed to look at variables affecting disc space pliability, implant subsidence, in vivo application, and clinical benefit of this procedure.

Paraspinal muscle impingement causing acute Brown-Sequard syndrome after posterior cervical decompression.

STUDY DESIGN: A case report. OBJECTIVE: To present a previously unreported cause of neurologic compromise after cervical spine surgery. SUMMARY OF BACKGROUND DATA: Several different causes of postoperative neurologic deficit have been reported in the literature. The authors present a case of acute postoperative paralysis after posterior cervical decompression by a mechanism that has not yet been reported in the literature. METHODS: A 54-year-old muscular, short-statured man underwent posterior cervical laminectomy from C3-C5 without instrumentation and left C5 foraminotomy. Within hours of leaving the operating room, he began to develop postoperative neurologic deficits in his extremities, which progressed to a classic Brown-Sequard syndrome. Magnetic resonance imaging revealed regional kyphosis and large swollen paraspinal muscles impinging on the spinal cord without epidural hematoma. Emergent operative re-exploration confirmed these findings; large, swollen paraspinal muscles, a functioning drain, and no hematoma were found. RESULTS: The patient was treated with immediate corticosteroids at the time of initial diagnosis, and emergent re-exploration and debulking of the paraspinal muscles. The patient had complete recovery of neurologic function to his preoperative baseline after the second procedure but required a third procedure in which anterior discectomy and fusion at C4-C5 was performed, which led to improvement of his preoperative symptoms. CONCLUSION: When performing posterior cervical decompression, surgeons must be aware of the potential for loss of normal lordosis and anterior displacement of paraspinal muscles against the spinal cord, especially in muscular patients.

National trends in anterior cervical fusion procedures.

STUDY DESIGN: Population-based database analysis. OBJECTIVE: To analyze trends in patient- and healthcare-system-related characteristics, utilization and outcomes associated with anterior cervical spine fusions. SUMMARY OF BACKGROUND DATA: Anterior cervical decompression and spine fusion (ACDF) is one of the most commonly performed surgical procedures of the spine. However, few data analyzing trends in patient- and healthcare-system-related characteristics, utilization and outcomes exist. METHODS: Data from 1990 to 2004 collected in the National Hospital Discharge Survey were accessed. ACDF procedures were identified. Five-year periods of interest (POI) were created for temporal analysis and changes in the prevalence and utilization of this procedure as well as in patient- and healthcare-system-related variables were examined. The changes in the occurrence of procedure-related complications were evaluated. RESULTS: An estimated total of 771,932 discharges after ACDF were identified. Temporally, an almost 8-fold increase in total prevalence was accompanied by a similar increase in utilization (23/100.000 civilians/POI to 157/100.000/civilians/POI). The highest increase in utilization was observed in those > or =65 years (28-fold). Average age increased from 47.2 years to 50.5 years over time. Length of hospital stay decreased from 5.17 days to 2.38 days. Overall procedure-related complication rates decreased from 4.6% to 3.03%. The prevalence of hypertension, diabetes mellitus, hypercholesterolemia, obesity, pulmonary, and coronary artery increased over time among patients undergoing ACDF. CONCLUSION: Despite limitations inherent to secondary analysis of large databases, we identified a number of significant changes in the utilization, demographics, and outcomes associated with ACDF, which can be used to assess the effect of changes in medical care, direct health care resources, and future research. The effect of the increased prevalence of comorbidities on medical practice remains to be evaluated. Further studies are necessary to evaluate causal relationships.

Distal femoral rotational axes in Indian knees.

PURPOSE: To measure the angular relationships of distal femoral rotational axes in 100 normal Indian knees. METHODS: 42 men and 8 women aged 26 to 40 (mean, 31) years, with 100 normal non-arthritic knees were recruited. Anatomic landmarks were measured using computed tomography. They included the posterior condylar axis, the transepicondylar axis, the anteroposterior axis (Whiteside's line), the posterior condylar angle (PCA), the Whiteside-epicondylar angle (W-EP), and the Whiteside-posterior condylar angle (W-PC). RESULTS: The mean PCA, W-EP, and W-PC were 5, 90.8, and 95.8 degrees, respectively. The mean femorotibial alignment was 179.6 degrees. The differences between the left and right sides were significant only for the WEP and W-PC. Only the PCA and W-EP were weakly correlated (r=0.338, p=0.001). CONCLUSION: There are differences in distal femoral rotational axes among Indian, Caucasian, and Japanese knees. Our data can be used to evaluate changes in those axes in ageing or arthritic patients.

Quantification of effect of sequential posteromedial release on flexion and extension gaps: a computer-assisted study in cadaveric knees.

A novel sequence of posteromedial release consistent with surgical technique of total knee arthroplasty was performed in 15 cadaveric knees. Medial and lateral flexion and extension gaps were measured after each step of the release using a computed tomography-free computer navigation system. A spring-loaded distractor and a manual distractor were used to distract the joint. Posterior cruciate ligament release increased flexion more than extension gap; deep medial collateral ligament release had a negligible effect; semimembranosus release increased the flexion gap medially; reduction osteotomy increased medial flexion and extension gaps; superficial medial collateral ligament release increased medial joint gap more in flexion and caused severe instability. This sequence of release led to incremental and differential effects on flexion-extension gaps and has implications in correcting varus deformity.

A comparison of coronal plane axial femoral relationships in Asian patients with varus osteoarthritic knees and healthy knees.

Standing full-length radiographs were measured to compare coronal femoral axes between 250 limbs in patients with varus osteoarthritis with 50 healthy controls. Mean distal femoral axis-mechanical axis angle was 7.3 degrees +/- 1.6 degrees , and mean femoral bow was 3.6 degrees +/- 2.5 degrees in patients compared to 5.5 degrees +/- 0.8 degrees and 0.4 degrees +/- 1.2 degrees , respectively, in controls. Femoral condylar-mechanical axis angle was significantly lower in osteoarthritic limbs (89.9 degrees + 2.8 degrees ) as compared to controls (93.1 degrees + 1.6 degrees ). Varus deformity correlated significantly with femoral bowing (P < .05; correlation coefficient, 0.4). Osteoarthritic limbs (18.8%) showed a distal femoral axis-mechanical axis angle more than 9 degrees . These findings have implications in deciding the optimum valgus angle at which to perform distal femoral resection in total knee arthroplasty.

Computerized tomographic morphometric analysis of subaxial cervical spine pedicles in young asymptomatic volunteers.

BACKGROUND: Although cervical spine pedicle screws have been shown to provide excellent fixation, widespread acceptance of their use is limited because of the risk of injury to the spinal cord, nerve roots, and vertebral arteries. The risks of pedicle screw insertion in the cervical spine can be mitigated by a three-dimensional appreciation of pedicle anatomy. Normative data on three-dimensional subaxial pedicle geometry from a large, young, and asymptomatic North American population are lacking. The purpose of the present study was to determine three-dimensional subaxial pedicle geometry in a large group of young volunteers and to determine level and sex-specific morphologic differences. METHODS: Helical computerized tomography scans were made from the third cervical to the seventh cervical vertebra in ninety-eight volunteers (sixty-three men and thirty-five women) with an average age of twenty-five years. Pedicle width, height, length, and transverse and sagittal angulations were measured bilaterally. Pedicle screw insertion positions were quantified in terms of mediolateral and superoinferior offsets relative to readily identifiable landmarks. RESULTS: The mean pedicle width and height at all subaxial levels were sufficient to accommodate 3.5-mm screws in 98% of the volunteers. Pedicle width and height dimensions of <4.0 mm were rare (observed in association with only 1.7% of the pedicles), with 82% occurring in women and 72% occurring unilaterally. Screw insertion positions generally moved medially and superiorly at caudal levels. Transverse angulation was approximately 45 degrees at the third to fifth cervical levels and was less at more caudal levels. Sagittal angulation changed from a cranial orientation at superior levels to a caudal orientation at inferior levels. Mediolateral and superoinferior insertion positions and sagittal angulations were significantly dependent (p < 0.05) on sex and spinal level. Transverse angulation was significantly dependent (p < 0.05) on spinal level. CONCLUSIONS: Pedicle screw insertion points and orientation are significantly different (p < 0.05) at most subaxial cervical levels and between men and women. Preoperative imaging studies should be carefully templated for pedicle size in all patients on a level-specific basis. Although the prevalence was low, women were more likely to have pedicle width and height dimensions of <4.0 mm.

Cruciate ligaments in arthritic knees: a histologic study with radiologic correlation.

Anterior cruciate ligaments (ACLs) and posterior cruciate ligaments (PCLs) from 45 osteoarthritic knees were histologically examined to evaluate the frequency and grade the severity of degenerative changes, which were correlated with radiologic grade of arthritis and severity of deformity at the knee. Immunohistochemical staining was used to identify neurofilaments in 10 knees. A histologic score was generated for both cruciates based on changes found on light microscopy. The ACL was severely degenerated, absent, or disrupted in knees with radiologic arthritis higher than grade 3 and varus deformity exceeding 15 degrees . The PCL was moderately degenerated in most knees irrespective of the grade of arthritis and severity of deformity. Neurofilaments were present in all 10 PCLs and absent in 4 ACLs.

Degenerative cervical spondylosis: clinical syndromes, pathogenesis, and management.

Degenerative changes in the cervical spinal column are ubiquitous in the adult population, but infrequently symptomatic. The evaluation of patients with symptoms is facilitated by classifying the resulting clinical syndromes into axial neck pain, cervical radiculopathy, cervical myelopathy, or a combination of these conditions. Although most patients with axial neck pain, cervical radiculopathy, or mild cervical myelopathy respond well to initial nonsurgical treatment, those who continue to have symptoms or patients with clinically evident myelopathy are candidates for surgical intervention.

Quantitative anatomy of subaxial cervical lateral mass: an analysis of safe screw lengths for Roy-Camille and magerl techniques.

STUDY DESIGN: Determination of lateral mass screw lengths with Roy-Camille and Magerl techniques of screw insertion using computerized tomography in 98 young, asymptomatic North American volunteers. OBJECTIVE: To provide reliable and normative data on safe screw lengths using the Roy-Camille and Magerl techniques of lateral mass fixation in the subaxial cervical spine. SUMMARY OF BACKGROUND DATA: Lateral mass screw lengths have been studied in the past using differing subject and measurement characteristics and small sample sizes. Results demonstrated considerable variation in screw length and influencing factors. Inappropriate screw lengths can result in neurovascular injury during screw insertion, facet joint damage, or inadequate fixation. METHODS: Bicortical screw lengths were bilaterally measured at each spinal level from C3-C7 in 98 young volunteers using computed tomography reconstructions through the lateral masses obtained in the plane of the screw in Roy-Camille and Magerl techniques. RESULTS: With both techniques, trajectories were longest at C4-C6, shorter at C3, and shortest at C7. Screw lengths were greater in males when compared with females at all levels. Average Magerl screw lengths were approximately 2.6 mm longer at C3-C6 levels, and approximately 1.3 mm longer at the C7 level when compared with Roy-Camille technique. There was minimal correlation between screw lengths and anthropometric measurements including stature, body weight, and neck length. CONCLUSION: Significant variations exist at each subaxial level with either technique. We recommend the surgeon determine screw lengths for fixation at each level using preoperative sagittal oblique computed tomography scans, which provide the most accurate technique of preoperative templating for screw length.

Tibial articular cartilage wear in varus osteoarthritic knees: correlation with anterior cruciate ligament integrity and severity of deformity.

Tibial articular cartilage wear was assessed intraoperatively in 100 consecutive patients with varus osteoarthritis undergoing total knee arthroplasty. Severity of deformity on radiographs, integrity of the anterior cruciate ligament (ACL) at surgery, and body mass index were recorded. Posterior half of the medial tibial plateau was more commonly involved in knees with ACL deficiency; there was predominantly anteromedial involvement with an intact ACL. Varus deformity was significantly greater in knees with a deficient ACL than with an intact ACL. Severity of deformity did not alter the wear pattern, irrespective of the ACL integrity. The functional status of ACL in an osteoarthritic knee can be corroborated with the wear pattern on the tibial plateau articular cartilage.

Tibial torsion in non-arthritic Indian adults: a computer tomography study of 100 limbs.

BACKGROUND: Knowledge of normal tibial torsion is mandatory during total knee replacement (TKR), deformity correction and fracture management of tibia. Different values of tibial torsion have been found in different races due to biological and mechanical factors. Value of normal tibial torsion in Indian limbs is not known, hence this study to determine the norm of tibial torsional value in normal Indian population. MATERIALS AND METHODS: Computer tomography (CT) scans were performed in 100 non-arthritic limbs of 50 Indian adults (42 males, eight females; age 26-40 years). Value of tibial torsion was measured using dorsal tangent to tibial condyles proximally and bimalleolar axis distally. RESULTS: Normal tibial torsion was found to be 21.6 +/- 7.6 (range 4.8 to 39.5) with none of the values in internal rotation. Right tibia was externally rotated by 2 degrees as compared to the left side (P 0.029). No significant difference was found in male and female subjects. Value of tibial torsion was less than in Caucasian limbs, but was comparable to Japanese limbs when studies using similar measurement technique were compared. CONCLUSIONS: Indian limbs have less tibial torsion than Caucasian limbs but the value of tibial torsion is comparable to Japanese limbs.

Primary total hip arthroplasty in protrusio acetabuli using impacted morsellized bone grafting and cementless cups: a medium-term radiographic review.

Thirty primary total hip arthroplasties were performed for protrusio acetabuli in 23 patients (mean age, 46 years) using impacted autologous bone grafting and a cementless porous-coated hemispheric cup without the use of metal cages or rings. At 2 to 10 years' follow-up (mean, 4.2 years), there was satisfactory radiographic evidence of consolidation of the graft in all cases. All acetabular components were considered to be stable with no instance of graft resorption. Clinical results were considered as excellent in 14 hips, good in 13 hips, fair in 2 hips, and poor in 1 hip. For younger patients with protrusio acetabuli, use of an uncemented porous-coated hemispheric cup with peripheral press-fit fixation and restoration of bone stock with impacted autologous bone grafting reflect a technically straightforward procedure that appears to give satisfactory medium-term results.

Comparison of limb and component alignment using computer-assisted navigation versus image intensifier-guided conventional total knee arthroplasty: a prospective, randomized, single-surgeon study of 467 knees.

Total knee arthroplasty was performed in 282 knees with image-free navigation (group A) and in 185 with optimized conventional technique (group B). Mean postoperative mechanical axis of the limb was 179.7 degrees in group A and 179.1 degrees in group B (P < .002). There was a higher percentage of knees in group A that had restoration of mechanical axis to +/-1 degrees, +/-2 degrees, and +/-3 degrees of neutral (P < .0001). There were 9.2% outliers (+/-3 degrees) in group A and 21.6% outliers in group B (P < .0001). For knees exceeding 20 degrees varus, there was no significant difference between the mean mechanical axes in the 2 groups. Both components were aligned within 3 degrees of neutral in 90.8% of the knees in group A and 76.2% of the knees in group B (P < .0001).

Unicompartmental knee arthroplasty: functional recovery and radiographic results with a minimally invasive technique.

We prospectively evaluated 100 consecutive unicompartmental knee arthroplasties, performed in minimally invasive quadriceps-sparing fashion, for medial compartment osteoarthritis in patients aged 46 to 79 years, with anteromedial tibial wear, less than 10 degrees of flexion contracture, correctable varus not exceeding 15 degrees , and an intact anterior cruciate ligament. We aimed to determine (1) early functional outcome and (2) radiographic limb alignment and component placement. Mean incision length was 7.2 cm, hospital stay 2.1 days, and blood loss 240 ml. Flexion at 3 months was between 120 degrees and 155 degrees (mean, 139 degrees ). Among the patients, 80% could flex beyond 130 degrees , and 91% could sit cross-legged, kneel, and get up easily from the floor. The mean hip-knee-ankle axis was 177 degrees . Ninety-five percent of femoral components were centered on the tibial component. Tibial component slope was restored in 91%.

Correcting varus deformity.

We report our technique and the results of treating severe intra- and extra-articular varus deformity using posterior stabilized fixed-bearing implants. We used a technique of selective posteromedial release and reduction osteotomy of posteromedial tibial flare in 173 knees in 117 patients. Proximal tibial osteotomy was used to correct severe extra-articular deformity. Mean tibiofemoral varus of 22 degrees preoperatively was corrected to 5.3 degrees valgus postoperatively. A total of 86% knees were in 4 degrees to 10 degrees valgus postoperatively. Mean Knee Society score improved from 22.8 to 91.1, and function score from 22.8 to 72.1 at 2 to 9 years. Of 30 bone grafts for tibial defects, 28 were successfully incorporated. No patient reported significant instability. Three knees showed tibial component loosening. Our technique restored alignment and stability without the need for constrained implants.