Background: Postoperative determination of tunnel position after anterior cruciate ligament (ACL) reconstruction can be challenging.
Hypothesis: The femoral tunnel angle and inclination angle are reliable methods for evaluating tunnel position after ACL reconstruction while aiding in determining whether an ACL reconstruction falls outside an anatomic range as defined on 3-dimensional (3D) computed tomography (CT).
Study Design: Cohort study (diagnosis); Level of evidence, 3.
Methods: Fifty patients were included who received single-bundle ACL reconstructions with postoperative flexion weightbearing radiographs, magnetic resonance imaging (MRI), and CT scans. Femoral tunnel angles were determined from posterior-to-anterior postoperative radiographs, and inclination angles were determined from sagittal MRI. The ACL reconstructions were grouped by surgical technique, transtibial (TT) or tibial tunnel independent (TTI), and as either falling inside or outside an anatomic range on 3D CT.
Results: Patients with tunnel positions within an anatomic range, as previously defined, had a larger femoral tunnel angle (39.3° ± 4.2°) and smaller inclination angle (49.5° ± 2.7°) than patients who fell outside an anatomic range (17.2° ± 12.5° and 62.3° ± 7.8°, respectively) (P < .001). Patients in the TTI group had a larger femoral tunnel angle (37.6° ± 9.30°) and smaller inclination angle (51.8° ± 6.5°) than those in the TT group (14.2° ± 9.3° and 63.5° ± 7.2°, respectively) (P < .001). Posterior-to-anterior femoral tunnel position was negatively correlated with femoral tunnel angle (P < .001, r = .78) and positively correlated with inclination angle (P < .001, r = .74). Based on a receiver operating characteristic (ROC) curve, a femoral tunnel angle of 32.7° (100% sensitivity and 85% specificity) and inclination angle of 55° (100% sensitivity and 87.5% specificity) were determined to distinguish ACL reconstructions that fell either within or outside an anatomic range on 3D CT.
Conclusion: Femoral tunnel angle and inclination angle can be reliably determined from both posterior-to-anterior radiographs and sagittal MRI and provide a useful metric for characterizing femoral tunnel position.
Background
Anterior cruciate ligament reconstruction with a double-bundle technique requires exact tunnel positioning. Reference values for the anatomic insertions are necessary for radiographic intra- and postoperative control and fluoroscopy-based navigation.
Hypothesis
The femoral and tibial insertions of the anteromedial bundle (AMB) and posterolateral bundle (PLB) of the anterior cruciate ligament can be described using standardized computed tomography scans.
Study Design
Descriptive laboratory study.
Methods
The insertion sites of the AMB and PLB were macroscopically identified and tagged by copper wire in 12 specimens. Computed tomography scans with predefined reconstructions were performed. Femorally, the geometric center of the insertions were determined in the sagittal view and described in a deep-high 10 x 10 grid. Tibially, the insertions were described as the ratio between the geometric center of the insertion sites with respect to the mediolateral and sagittal diameter of the tibia in frontal and sagittal reconstruction, respectively. The tibial insertions were described using a 10 x 10 grid in axial orientation.
Results
The geometric midpoints of the insertion areas at the femur of the AMB and PLB were located on the reticule at x = 21% ± 3% and y = 22% ± 2% for the AMB and x = 27% ± 3% and y = 45% ± 3% for the PLB. In the sagittal plane, the center of the tibial insertion was located at 41% ± 3% and 52% ± 3% of the tibial diameter from the anterior border for the AMB and PLB, respectively. The geometric centers of the tibial insertions in axial view were x = 52% ± 2% and y = 37% ± 3% for the AMB and x = 50% ± 2% and y = 48% ± 3% for the PLB.
Conclusion
The insertion site characteristics of the AMB and PLB can be evaluated by predefined reconstructions of computed tomography scans.
Clinical relevance
These results can serve as orientation landmarks for intra- and postoperative radiographic control and fluoroscopic-based navigation.
Background: Increased knee pain at the time of anterior cruciate ligament reconstruction may potentially predict more difficult rehabilitation, prolonged recovery, and/or be predictive of increased knee pain at 2 years.
Hypothesis: A bone bruise and/or other preoperative factors are associated with more knee pain/symptoms at the time of index anterior cruciate ligament reconstruction, and the presence of a bone bruise would be associated with specific demographic and injury-related factors.
Study Design: Cohort study (prevalence); Level of evidence, 2.
Methods: In 2007, the Multicenter Orthopaedic Outcomes Network (MOON) database began to prospectively collect surgeon-reported magnetic resonance imaging bone bruise status. A multivariable analysis was performed to (1) determine if a bone bruise, among other preoperative factors, is associated with more knee symptoms/pain and (2) examine the association of factors related to bone bruise. To evaluate the association of a bone bruise with knee pain/symptoms, linear multiple regression models were fit using the continuous scores of the Knee injury and Osteoarthritis Outcome Score (KOOS) symptoms and pain subscales and the Short Form 36 (SF-36) bodily pain subscale as dependent variables. To examine the association between a bone bruise and risk factors, a logistic regression model was used, in which the dependent variable was the presence or absence of a bone bruise.
Results: Baseline data for 525 patients were used for analysis, and a bone bruise was present in 419 (80%). The cohort comprises 58% male patients, with a median age of 23 years. The median Marx activity level was 13. Factors associated with more pain were higher body mass index (P < .0001), female sex (P = .001), lateral collateral ligament injury (P = .012), and older age (P = .038). Factors associated with more symptoms were a concomitant lateral collateral ligament injury (P = .014), higher body mass index (P < .0001), and female sex (P < .0001). Bone bruise is not associated with symptoms/pain at the time of index anterior cruciate ligament reconstruction. None of the factors included in the SF-36 bodily pain model were found to be significant. After controlling for other baseline factors, the following factors were associated with a bone bruise: younger age (P = .034) and not jumping at the time of injury (P = .006).
Conclusion: After anterior cruciate ligament injury, risk factors associated with a bone bruise are younger age and not jumping at the time of injury. Bone bruise is not associated with symptoms/pain at the time of index anterior cruciate ligament reconstruction.
