Background: We have recently developed a subcutaneous anterior pelvic fixation technique (INFIX). This internal fixator permits patients to sit, roll over in bed and lie on their sides without the cumbersome external appliances or their complications. The purpose of this study was to evaluate the biomechanical stability of this novel supraacetabular pedicle screw internal fixation construct (INFIX) and compare it to standard internal fixation and external fixation techniques in a single stance pelvic fracture model. Methods: Nine synthetic pelves with a simulated anterior posterior compression type III injury were placed into three groups (External Fixator, INFIX and Internal Fixation). Displacement, total axial stiffness, and the stiffness at the pubic symphysis and SI joint were calculated. Displacement and stiffness were compared by ANOVA with a Bonferroni adjustment for multiple comparisons Results: The mean displacement at the pubic symphysis was 20, 9 and 0.8 mm for external fixation, INFIX and internal fixation, respectively. Plate fixation was significantly stiffer than the INFIX and external Fixator (P = 0.01) at the symphysis pubis. The INFIX device was significantly stiffer than external fixation (P = 0.017) at the symphysis pubis. There was no significant difference in SI joint displacement between any of the groups. Conclusions: Anterior plate fixation is stiffer than both the INFIX and external fixation in single stance pelvic fracture model. The INFIX was stiffer than external fixation for both overall axial stiffness, and stiffness at the pubic symphysis. Combined with the presumed benefit of minimizing the complications associated with external fixation, the INFIX may be a more preferable option for temporary anterior pelvic fixation in situations where external fixation may have otherwise been used.

Noncontact anterior cruciate ligament (ACL) injury after valgus landing has been reported and studied biomechanically. However, the role of the medial collateral ligament (MCL) in dissipating these forces has not been fully elucidated. The purpose of this study was to investigate the role that the MCL plays in ACL strain during simulated landing. The hypothesis was that ACL strain would increase significantly in MCL-incompetent knees compared with the native knee and that reconstructing the MCL would return the values to those of the intact knee. Controlled laboratory study. Eight fresh-frozen human cadaveric knees were used in this study. A materials testing machine applied a force of 2× body weight over 60 milliseconds to simulate landing after a jump. The knees were tested in 12 loading conditions, consisting of full extension or 15° of flexion combined with 7° of valgus or neutral alignment while the tibia was in external rotation, neutral rotation, or internal rotation. This test procedure was repeated on each specimen with the MCL transected and reconstructed. The superficial and deep MCL was transected along with the posterior oblique ligament, which was thought to simulate a worst case scenario. The MCL was reconstructed by use of semitendinosus and gracilis tendon grafts. During internal rotation at 0° of flexion and 0° of valgus, both the intact (P = .005) and the reconstructed (P = .004) MCL states placed significantly lower strain on the ACL than did the transected MCL. The reconstructed MCL state at 0° of flexion and 7° of valgus (P = .049) along with 15° of flexion and 0° of valgus (P = .020) also placed significantly lower strain on the ACL than did the transected MCL. For external rotation testing at 0° of flexion and 7° of valgus, the reconstructed MCL state placed significantly lower strain on the ACL than did the transected MCL (P = .039). Finally, during neutral rotation, the ACL strain at 0° of valgus and 0° of flexion, and at 7° of valgus and 0° of flexion was significantly lower for the MCL-intact groups (P < .028) and MCL-reconstructed groups (P < .016) than the MCL-transected groups. The current findings demonstrate that during valgus landing, a knee with an incompetent MCL puts the ACL under increased strain. These values are highest in full extension with the tibia in internal and neutral rotation. This increased strain can be reduced to baseline levels with reconstruction. A knee with an incompetent MCL puts the ACL under increased strain. Once the MCL has healed in an elongated manner, MCL reconstruction should be considered.

Participation in sports has risen in the United States over the last few years, increasing the risk of injuries such as tears to the anterior cruciate ligament (ACL) in the knee. Previous studies have shown a correlation between knee kinematics when landing from a jump and this injury. The purpose of this study was to validate the ability of a commercially available inertial measurement units (IMUs) to accurately measure knee joint angles during a dynamic movement. Eight healthy subjects participated in the study. Validation was performed by comparing the angles measured by the wearable device to those obtained through the gold standard motion capture system when landing from a jump. Root mean square, linear regression analysis, and Bland–Altman plots were performed/constructed. The mean difference between the wearable device and the motion capture data was 8.4° (flexion/extension), 4.9° (ab/adduction), and 3.9° (rotation). In addition, the device was more accurate at smaller knee angles. In our study, a commercially available wearable IMU was able to perform fairly well under certain conditions and was less accurate in other conditions.

The purpose of this study was to describe the effect of anterior horn of the lateral meniscus (AHLM) tears on tibiofemoral contact pressures and the ability to restore normal parameters with repair. Eight fresh-frozen cadaveric knees were used. The specimens were subjected to a load of 1,000 N at 0 and 30 degrees of flexion and peak pressure, force and contact area were recorded. The test was repeated for four different instances. Peak force in the lateral compartment was significantly increased at 0 degrees of knee flexion from 37 N intact to 47 N after the tear and 56 N postmeniscectomy. At 0 degrees of knee flexion, the peak pressure of the lateral meniscus was significantly increased from 1.1 MPa in the intact state to 1.9 MPa after meniscectomy. The peak pressure in the nontraumatized medial compartment was significantly increased after partial lateral meniscectomy (p < 0.05). This cadaveric study demonstrated a significant increase in tibiofemoral peak forces in both the medial and lateral compartments with a tear of the AHLM. It also showed an increase in peak contact pressure after meniscectomy. With repair, the preinjury condition peak forces were restored to normal, suggesting the importance of repairing tears of the AHLM.

Background: An increase in soccer-related injuries occurred in the United States between 2000 and 2012; however, most studies of soccer-related injuries have only examined the pediatric population and not adults. Hypothesis: The number of soccer injuries is increasing in both the pediatric and adult populations. There are differences in injury types and counts when comparing male and female players within various age groups. Study Design: Descriptive epidemiology study. Level of Evidence: Level 4. Methods: This retrospective analysis surveyed the US Consumer Product Safety Commission’s National Electronic Injury Surveillance System (NEISS) database from 2000 to 2012 for soccer-related injuries in children and adults aged 5 to 49 years. Results: From 2000 to 2012, there were an estimated 2,472,066 soccer-related injuries among 5- to 49-year-olds; 629,994 (25.5%) in adults (aged 20-49 years). The overall estimated pediatric injury count increased significantly over the time period ( R² = 0.764, P < 0.001). In the 20- to 49-year age range, there was also a significant increase in the estimated number of injuries over the 13-year period, from 41,292 injuries in 2000 to 55,743 in 2012 ( R² = 0.719, P < 0.001). The estimated injury counts for male players were significantly higher than female players in any given year for all age groups ( P < 0.001). Girls aged 5 to 19 years were more likely to have lower extremity injuries than boys (odds ratio [OR], 1.256; 95% CI, 1.214-1.299; P < 0.001). The most common injuries reported were strain/sprains (33.3%), fractures (23.7%), and contusions and abrasions (17.4%) within the 5- to 49-year age category. In both sexes, strains and sprains were significantly lower among 5- to 19-year-olds in comparison with 20- to 49-year-olds (OR, 0.740; 95% CI, 0.714-0.766; P < 0.001). Conclusion: There are age- and sex-related differences in estimated injury count, body part injured, type of injury, and hospital admissions for soccer. Also, estimated injury count increased over the 2000 to 2012 time period. Clinical Relevance: This study demonstrates that there are differences between pediatric and adult injuries, based on sex, body part, type of injury, and hospital admissions.