Arthroscopic evaluation of knee lateral compartment widening after lateral ligamentous injury.

PURPOSE: To evaluate whether diagnostic arthroscopy of the lateral tibiofemoral compartment can determine the presence of a lateral ligamentous knee injury. METHODS: Nine cadaveric knee specimens were used with varus stresses of 12 Nm and the force at which no further lateral opening occurred. Arthroscopic measurements were taken of the lateral compartments with knees at 30°, 45° and 90°. Measurements were recorded in the intact knees and with sequential sectioning of LCL, popliteus, popliteofibular, ACL and PCL. Measurements and opening differences between each ligament state were recorded. RESULTS: No significant difference existed between the two forces compared (p < 0.05). There was a significant difference in opening distance measured at all knee angles with sequential sectioning (p < 0.001). Sequential opening difference between each ligament state was significantly different (p < 0.001) and also when compared across each knee angle (p < 0.001). At 30° for an isolated LCL injury, the average lateral opening was 10.1 mm. For a combined LCL and PLC (popliteus tendon and popliteofibular ligament) injury, the average lateral opening was 12.9 mm. For LCL-, PLC- and ACL-deficient knees, there was average lateral opening of 16.5 mm. CONCLUSIONS: LCL and combined lateral ligamentous injuries can be differentiated during arthroscopy with varus stress. This may be useful when deciding if there is a need for operative repair of any injured lateral ligamentous structures.

Vacuum-assisted wound closure in postoperative spinal wound infection.

Combined with antibiotic therapy, vacuum-assisted wound closure may help reduce the need for serial irrigation and debridement surgery, contributing to a decrease in overall hospital stay.

The effects of screw orientation in severely osteoporotic bone: a comparison with locked plating.

BACKGROUND: Techniques such as varying screw insertion angles and the use of locked plating have been shown to improve the strength of fixation in bone. The effects of these methods is less clearly understood in bone of exceedingly poor quality. METHODS: Forty plate-bone constructs were assembled and divided into four groups of ten. Perpendicularly placed screws were placed in one group, convergently placed crossing screws were placed in a second group, an oblique end screw was placed in a third group, and a fourth group utilized perpendicularly placed locking screws in a locking plate. All test subjects were mounted and loaded in cantilever bending to the point of failure. Stiffness, initial load to failure, and maximal load tolerated were all analyzed. FINDINGS: All four groups demonstrated evidence of failure at similar loads (21.8-26.1N). The locked group was able to tolerate significantly higher loads overall (37.3N, P=.044). All three non-locked groups demonstrated similar failure patterns and load to failure. Locking constructs demonstrated a distinctly different failure pattern. No significant differences were detected with regard to screw orientation and load to failure. The group with an oblique end screw was significantly less stiff than the other three constructs (P=.017). INTERPRETATION: In a severely osteoporotic model, failure in cantilever bending at low forces will take place regardless of fixation methods used. The mechanism of failure is different in locked constructs compared to traditional constructs. The added benefit of oblique screw placement observed in healthy bone is not observed in osteoporotic bone.

Teachability and reliability of a new classification system for lower cervical spinal injuries.

STUDY DESIGN: Reliability and validation study. OBJECTIVE: The objective of this study is to evaluate a new lower cervical spine injury classification system and assess its reliability, teachability, and clinical applications. SUMMARY OF BACKGROUND DATA: The recently proposed Cervical Spine Injury Severity Score (CSISS) morphologically describes lower cervical spine injuries and grades them on a score of 1 to 20 depending on the integrity of the 4 columns that make up the cervical spine. Early data suggests that this classification system is both reliable and reproducible. Reliability data from additional institutions and data exploring teachability of this classification system is not available. METHODS: Fifteen subjects (12 residents and 3 attendings trained in the management of spinal trauma) reviewed radiographs and CT scans of 50 patients and scored them according to the CSISS. Six residents scored the patients 1 month before an instructional lecture given by the senior author and then again immediately following the lecture to assess teachability of the new classification system. All subjects then reviewed the films a final time 1 month later to assess both intraobserver and interobserver reliability. The patients' scores were also analyzed in conjunction with their clinical treatment. RESULTS: Interobserver reliability overall was excellent (0.975) with junior residents performing similarly to those with more extensive training. Intraobserver reliability was also excellent overall (0.983). Teachability scores improved in the ability to score all 4 columns. Furthermore, this classification system was a fair overall predictor of surgical candidates as a score of 7 predicted 19 out of 26 surgical patients (76% sensitivity, 100% specificity). CONCLUSION: The CSISS is a useful new adjunct in the treatment and classification of lower cervical spine injuries. The system is reliable, reproducible, and teachable. It is clinically useful for all levels of orthopedic training and experience.

Radiographic assessment of lumbar facet distance spacing and pediatric spondylolysis.

STUDY DESIGN: Retrospective radiographic review. OBJECTIVE: The purpose of this article was to explore the relationship between interfacet spacing and pediatric spondylolysis. SUMMARY OF BACKGROUND DATA: Recent literature suggests that a potential cause of spondylolytic defects in adults is a narrowed interfacet spacing in the lower lumbar spine. This lack of space places them at increased risk for pars fractures with repetitive lumbar hyperextension. This relationship has not been explored in a pediatric population. METHODS: The anteroposterior lumbar spine radiographs of 41 pediatric patients with spondylolytic defects were compared with 41 unaffected controls. A standard digital caliper was used to measure interfacet distance. Vertebral body width and interpedicular distance were recorded as internal standards to control for varying vertebral size. Statistical analysis exploring the relationships of interfacet distances between the affected and unaffected groups was performed using a Mann-Whitney U test. RESULTS: The absolute increase in interfacet distance between adjacent levels was significantly smaller at the L4/L5 level in spondylolytic individuals (P = 0.023). When interpedicular distance was used to standardize for vertebral body size, a significantly smaller increase in the interpedicular distance was noted at the L4/5 level in spondylolytic individuals (P = 0.026). Similar results were obtained when body width was used to standardize for vertebral body size (P < 0.001). A similar trend was noticed at the L3/4 level when standardizing with interpedicular distance although these results were not significant (P = 0.098). CONCLUSION: A likely explanation for the etiology of lumbar pars defects is insufficient caudal increase in lumbar interfacet spacing. Further prospective studies are necessary to determine if unaffected individuals with a narrowed interfacet spacing are at increased risk of developing spondylolytic defects later in life.