Background: Previous work has reported that increased tibial slope is directly correlated with increased anterior tibial translation, possibly predisposing patients to higher rates of anterior cruciate ligament (ACL) tears and causing higher rates of ACL graft failures over the long term. However, the effect of changes in sagittal plane tibial slope on ACL reconstruction (ACLR) graft force has not been well defined. Purpose/Hypothesis: The purpose of this study was to quantify the effect of changes in sagittal plane tibial slope on ACLR graft force at varying knee flexion angles. Our null hypothesis was that changing the sagittal plane tibial slope would not affect force on the ACL graft. Study Design: Controlled laboratory study. Methods: Ten male fresh-frozen cadaveric knees had a posterior tibial osteotomy performed and an external fixator placed for testing and accurate slope adjustment. Following ACLR, specimens were compressed with a 200-N axial load at flexion angles of 0°, 15°, 30°, 45°, and 60°, and the graft loads were recorded through a force transducer clamped to the graft. Tibial slope was varied between −2° and 20° of posterior slope at 2° increments under these test conditions. Results: ACL graft force in the loaded testing state increased linearly as slope increased. This effect was independent of flexion angle. The final model utilized a 2-factor linear mixed-effects regression model and noted a significant, highly positive, and linear relationship between tibial slope and ACL graft force in axially loaded knees at all flexion angles tested (slope coefficient = 0.92, SE = 0.08, P < .001). Significantly higher graft force was also observed at 0° of flexion as compared with all other flexion angles for the loaded condition (all P < .001). Conclusion: The authors found that tibial slope had a strong linear relationship to the amount of graft force experienced by an ACL graft in axially loaded knees. Thus, a flatter tibial slope had significantly less loading of ACL grafts, while steeper slopes increased ACL graft loading. Our biomechanical findings support recent clinical evidence of increased ACL graft failure with steeper tibial slope secondary to increased graft loading. Clinical Relevance: Evaluation of the effect of increasing tibial slope on ACL graft force can guide surgeons when deciding if a slope-decreasing proximal tibial osteotomy should be performed before a revision ACLR. Overall, as slope increases, ACL graft force increases, and in our study, flatter slopes had lower ACL graft forces and were protective of the ACLR graft.

Background: Meniscal ramp lesions have been defined as a tear of the peripheral attachment of the posterior horn of the medial meniscus (PHMM) at the meniscocapsular junction or an injury to the meniscotibial attachment. Precise anatomic descriptions of these structures are limited in the current literature. Purpose: To quantitatively and qualitatively describe the PHMM and posteromedial capsule anatomy pertaining to the location of a meniscal ramp lesion with reference to surgically relevant landmarks. Study Design: Descriptive laboratory study. Methods: Fourteen male nonpaired fresh-frozen cadavers were used. The locations of the posteromedial meniscocapsular and meniscotibial attachments were identified. Measurements to surgically relevant landmarks were performed with a coordinate measuring system. To further analyze the posteromedial meniscocapsular and meniscotibial attachments, hematoxylin and eosin and alcian blue staining were conducted on a separate sample of 10 nonpaired specimens. Results: The posterior meniscocapsular attachment had a mean ± SD length of 20.2 ± 6.0 mm and attached posteroinferiorly to the PHMM at a mean depth of 36.4% of the total posterior meniscal height. The posterior meniscotibial ligament attached on the PHMM 16.5 mm posterior and 7.7 mm medial to the center of the posterior medial meniscal root attachment. The meniscotibial ligament tibial attachment was 5.9 ± 1.3 mm inferior to the articular cartilage margin of the posterior medial tibial plateau. The posterior meniscocapsular attachment converged with the meniscotibial ligament at the most posterior point of the meniscocapsular junction in all specimens. Histological staining of the meniscocapsular and meniscotibial ligament PHMM attachments showed similar structure, cell density, and fiber directionality, with no qualitative difference in the makeup of their collagen matrices across all specimens. Conclusion: The anatomy of the area where a medial meniscal ramp tear occurs revealed that the 2 posterior meniscal attachments merged at a common attachment on the PHMM. Histological analysis validated a shared attachment point of the meniscocapsular and meniscotibial attachments of the PHMM. Clinical Relevance: The findings of this study provide the anatomic foundation for an improved understanding of the meniscocapsular and meniscotibial attachments of the PHMM, which may help provide a more precise definition of a meniscal ramp lesion.

Background: Although posterior medial meniscal root (PMMR) repairs are often successful, postoperative meniscal extrusion after a root repair has been identified as a potential clinical problem. Purpose/Hypothesis: The purpose was to quantitatively evaluate the tibiofemoral contact mechanics and extent of meniscal extrusion after a PMMR repair. It was hypothesized that the addition of a centralization suture (into the posterior medial tibial plateau) would help restore normal joint load-bearing characteristics and restore the native amount of meniscal extrusion after a root tear. Furthermore, we hypothesized that the amount of meniscal extrusion would be greatest in loaded and flexed knees when measured at the posterior border of the medial collateral ligament (MCL). Study Design: Controlled laboratory study. Methods: Meniscal extrusion and tibiofemoral contact mechanics were measured using 3-dimensional digitization and pressure sensors in 10 nonpaired, human cadaveric knees. The PMMR of each knee was tested under 6 states: (1) intact; (2) type 2A PMMR tear; (3) anatomic transtibial pull-out root repair; (4) anatomic transtibial pull-out repair with centralization; (5) nonanatomic transtibial pull-out repair; and (6) nonanatomic transtibial pull-out repair with centralization, with randomization of the order of conditions 3 and 4, and 5 and 6. The testing protocol loaded knees with a 1000-N axial compressive force at 4 flexion angles (0°, 30°, 60°, 90°) in each state. Meniscal extrusion was measured with a 3-dimensional coordinate digitizer at 0° and 90° in both the loaded and unloaded states and calculated from the difference from the articular margin of the tibia to the periphery of the meniscus. Peak contact pressure, contact area, and total contact pressure were also recorded for all states at all flexion angles. Statistical analysis investigated the independent effects of flexion, state, and loading using 3 distinct 2-factor models. Results: Differences in the contact mechanics between repair techniques were most notable at higher flexion angles, demonstrating significantly higher average and peak contact pressures for nonanatomic repair states when compared with anatomic repairs with and without centralization (all P < .05). In unloaded knees at full extension, the magnitude of medial meniscal extrusion was significantly higher at the posterior border of the MCL compared with the posterior medial tibia ( P < .001) and adjacent to the root attachment on the tibia locations ( P < .001). Both anatomic repair states had no significant difference in the degree of extrusion when compared with the intact state. Conclusion: The anatomic transtibial pull-out root repair and the anatomic transtibial pull-out root repair with centralization techniques best restored contact mechanics of the knee and meniscal extrusion when compared with root tear and nonanatomic repair states at time zero. There were no significant differences in contact pressure or magnitude of extrusion between the anatomic repair state and the anatomic repair with centralization state. We found that extrusion is best measured in the coronal plane at the posterior border of the MCL for unloaded knees. However, the degree of extrusion increased as the knee was loaded and flexed to 90°. Clinical Relevance: When there are concerns about meniscal extrusion with a medial meniscal root repair, the addition of a centralization suture may be beneficial for patients in reducing pathologic meniscal extrusion and restoring joint contact mechanics.

Background:Metal screws are traditionally used to fix the coracoid process to the glenoid. Despite stable fixation, metal screws have been associated with hardware complications. Therefore, some studies have advocated for suture button fixation during the Latarjet procedure to reduce the complications associated with screw fixation.Purpose:To biomechanically evaluate the ultimate failure load of a cortical button and self-tensioning suture versus metal screws for coracoid graft fixation during the Latarjet procedure.Study Design:Controlled laboratory study.Methods:Eight matched pairs of fresh-frozen, male cadaveric shoulders (N = 16) underwent the Latarjet procedure. The shoulders of each pair were randomly assigned to 1 of 2 groups: fixation using two 3.75-mm cannulated, fully threaded metal screws or fixation using a double suture button construct. Specimens were secured in a dynamic testing machine and cyclically preconditioned from 2 to 10 N at 0.1 Hz for 10 cycles. After preconditioning, specimens were pulled to failure at a normalized displacement rate of 400% of the measured gauge length per minute. The ultimate failure load and mechanism of failure were recorded for each specimen.Results:The mean ultimate load to failure for screw fixation (226 ± 114 N; 95% CI, 147-305 N) was not significantly different from that for suture button fixation (266 ± 73 N; 95% CI, 216-317 N) (P = .257). The mean strain at failure for screw fixation (63% ± 21%; 95% CI, 48%-77%) was not significantly different from that for suture button fixation (86% ± 26%; 95% CI, 69%-104%) (P = .060). The most common mechanism of failure for the screw fixation method was at the bone block drill holes, while an intramuscular rupture at the clamp-muscle interface occurred for the suture button construct.Conclusion:The screw and suture button fixation techniques exhibited comparable biomechanical strength for coracoid bone block fixation of the Latarjet procedure.Clinical Relevance:Metal screws have been reported to be a large contributor to intraoperative and postoperative complications. Therefore, given the results of the current study, a suture button construct may be an alternative to metal screw fixation during the Latarjet procedure. However, further clinical studies are warranted.

Background: Surgical treatment of lateral meniscal tears can be challenging due to the greater mobility of the lateral meniscus, thin capsule, and management of the popliteal hiatus. There has been a lack of quantitative assessments of the structural attachments to the posterior horn of the lateral meniscus (PHLM) to guide repairs. Purpose: To qualitatively and quantitatively describe the anatomy of the PHLM, popliteomeniscal fascicles, and the posterolateral capsule. Study Design: Descriptive laboratory study. Methods: Fourteen male, nonpaired, fresh-frozen cadaveric knees were used. The attachments of the posterolateral capsule, popliteomeniscal fascicles, and meniscofemoral ligaments to the lateral meniscus and the attachment of the meniscotibial ligament to the tibia were identified. A 3-dimensional coordinate measuring system was used to measure the relationships of these attachments to surgically relevant landmarks and their structural relationship with the lateral meniscus. Results: The posterolateral capsule attachment had a confluent attachment at the superior margin of the PHLM, quantitatively attaching to the proximal 11% of the total height of the PHLM. On average, the length of the posterolateral capsule attachment to the superior surface of the PHLM was 16.7 ± 2.7 mm. The average length of the meniscotibial attachment to the posteroinferior aspect of the meniscus was 12.8 ± 3.9 mm. There was a lack of ligamentous attachments to the lateral meniscus between the lateral aspect of the meniscotibial ligament and the anterior aspect of the anterosuperior popliteomeniscal fascicle, where only popliteomeniscal fascicle and capsular attachments to the posterior meniscus were present. Conclusion: This anatomic study provides quantitative guidelines for the complex attachments to the PHLM. Knowledge of the quantitative descriptions of these attachments may aid in an improved intraoperative diagnosis of PHLM tears that extend to the popliteal hiatus, and further studies related to the surgical repair of the intricate attachments to the PHLM are recommended. Clinical Relevance: The findings of this study provide the anatomic foundation for an improved understanding of the role of the meniscocapsular, meniscotibial, and popliteomeniscal fascicle attachments of the posterolateral meniscus. Understanding the differences between the lengths of the superior and inferior aspects of the popliteal hiatus will help to further refine characterization of tears extending into the popliteal hiatus and to avoid potential overconstraint of the more mobile lateral meniscus during a repair by anatomically reproducing its native structural attachments.