Precisión diagnóstica de la radiografía para la medición de túneles óseos en reconstrucción de ligamento cruzado anterior / X ray diagnostic accuracy for bone tunnel measurements in anterior cruciate ligament reconstruction

OBJETIVO: Determinar la precisión diagnóstica de las radiografías de rodilla para la medición de los diámetros de los túneles tibiales y femorales en reconstrucción de ligamento cruzado anterior (RLCA). MATERIALES Y PACIENTES: Estudio retrospectivo de precisión diagnóstica en pacientes con antecedentes de RLCA. Inclusión: RLCA realizada en el mismo centro, con el mismo equipo quirúrgico, entre 2011 y 2015; uso de cualquier tipo de injerto y de fijación; estudiados con radiografía (Rx) y tomografía computada (TC) durante postop en el mismo centro. Exclusión: desfase Rx-TC > 6 meses; cirugía entre estudios radiológicos. Análisis de túneles por 3 especialistas (OsiriX). La precisión diagnóstica consideró la TC como gold standard. Se midieron las diferencias inter e intra-observador, y las variables que interfirieron en las mediciones. RESULTADOS: 22 pacientes cumplieron los criterios de selección, determinando 528 mediciones en total (Rx y TC, fémur y tibia, 3 observadores, 2 tiempos). No hubo diferencias estadísticamente significativas en la medición de los túneles femorales (p » 0.8986), pero sí en cuanto a los diámetros tibiales (p » 0.0001). El análisis de precisión diagnóstica determinó una sobrevaloración de los diámetros óseos al usar la radiografía (10,5% en fémur, 10% en tibia). Hubo diferencias estadísticamente significativas inter-observador tanto en Rx como en TC (observador más joven con el resto); sin diferencias intra-observador. CONCLUSIÓN: La Rx como método diagnóstico del diámetro de túneles óseos luego de una RLCA sobreestima los valores reales, lo que empeora cuando el observador tiene menor experiencia.

OBJECTIVE: To determine the diagnostic accuracy of knee radiographs for the measurement of tibial and femoral tunnels diameters after an anterior cruciate ligament reconstruction (ACLR). MATERIALS AND PATIENTS: A retrospective study of the diagnostic accuracy in patients with a history of ACLR. Inclusion: surgery performed in the same center, same surgical team, between 2011 to 2015; any graft and fixation; studied with radiography (X-Ray) and computed tomography (CT) during postop in the same center. Exclusion: X-Ray-CT lag > 6 months; surgery between radiological studies. Tunnel analysis by 3 specialists (OsiriX). Diagnostic accuracy considered CT as a gold standard. The inter and intraobserver differences, and the variables that interfered in the measurements, were measured. RESULTS: 22 patients achieved the selection criteria, determining 528 measurements in total (X-Ray and CT, femur and tibia, 3 observers, 2 times). There were no statistically significant differences in the measurement of the femoral tunnels (p » 0.8986), but there were differences in the tibial diameters (p » 0.0001). Analysis of diagnostic accuracy determined an overestimation of the bone diameters when using the radiography (10.5% in the femur, 10% in the tibia). There were statistically significant inter-observer differences in both X-Ray and CT (younger observer with the rest); there were no intra-observer differences. CONCLUSION: X-Ray as a diagnostic method of the diameter of bone tunnels after an ACLR overestimates the real values, which worsens when the observer has less experience.

A novel radiographic index for the diagnosis of posterior acromioclavicular joint dislocations.

BACKGROUND: Posterior acromioclavicular (AC) joint dislocations are frequently misclassified because posterior translation of the clavicle is difficult to evaluate in Zanca radiograph views. A novel radiographic index was used in this study to accurately diagnose posterior dislocations of the AC joint. HYPOTHESIS: This novel index has a high degree of accuracy for the diagnosis of posterior AC joint dislocations. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 2. METHODS: This was an analytic, descriptive study of 150 patients with different grades of AC injuries according to the Rockwood classification (30 patients for each grade of injury: I, II, III, IV, and V). The diagnosis of an AC injury was made both clinically and radiographically by using comparative Zanca and axillary views. Two measurements were performed in Zanca views: the coracoclavicular distance and the AC width distance. A width index was calculated for each patient. The Student t test, Bonferroni test, logistic regression, linear regression, and receiver operating characteristic (ROC) curves were used for statistical analysis. Forty cases were impartially selected to obtain a κ concordance value. RESULTS: The average value of the AC width index per group (according to the Rockwood classification) was as follows: type I, 2.1% (range, -12% to 25%); type II, 4.2% (range, -19% to 29%); type III, 19.1% (range, -59% to 91%); type IV, 110.3% (range, 47% to 181%); and type V, -3.8% (range, -71% to 62%). There was a significant difference between the average width index in the patients with type IV injuries and those in the remaining groups (P < .05). The ROC curve showed that a width index of 60% has a sensitivity of 95.7% and specificity of 97.5%, with a positive predictive value of 96.7% and negative predictive value of 95.6% to predict a type IV injury. Intraobserver reliability was rated as substantial agreement for each of 3 observers; the interobserver reliability of the 3 independent raters was almost perfect. CONCLUSION: An AC width index of ≥60% is highly accurate for the diagnosis of a posterior AC joint dislocation, with high intraobserver and interobserver concordance.