RESUMEN
Subchondral bone is thought to play a significant role in the initiation and progression of the post-traumatic osteoarthritis. The goal of this study was to document changes in tibial and femoral subchondral bone that occur as a result of two lapine models of anterior cruciate ligament injury, a modified ACL transection model and a closed-joint traumatic compressive impact model. Twelve weeks post-injury bones were scanned via micro-computed tomography. The subchondral bone of injured limbs from both models showed decreases in bone volume and bone mineral density. Surgical transection animals showed significant bone changes primarily in the medial hemijoint of femurs and tibias, while significant changes were noted in both the medial and lateral hemijoints of both bones for traumatic impact animals. It is believed that subchondral bone changes in the medial hemijoint were likely caused by compromised soft tissue structures seen in both models. Subchondral bone changes in the lateral hemijoint of traumatic impact animals are thought to be due to transmission of the compressive impact force through the joint. The joint-wide bone changes shown in the traumatic impact model were similar to clinical findings from studies investigating the progression of osteoarthritis in humans.
Asunto(s)
Huesos/diagnóstico por imagen , Osteoartritis/diagnóstico por imagen , Animales , Ligamento Cruzado Anterior/cirugía , Densidad Ósea , Cartílago Articular/diagnóstico por imagen , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Femenino , Fémur/diagnóstico por imagen , Fémur/patología , Miembro Posterior/patología , Imagen por Resonancia Magnética , Masculino , Meniscos Tibiales/cirugía , Conejos , Tibia/diagnóstico por imagen , Tibia/patología , Microtomografía por Rayos XRESUMEN
Traumatic injury to the knee leads to the development of post-traumatic osteoarthritis. The objective of this study was to characterize the effects of a single intra-articular injection of a non-ionic surfactant, Poloxamer 188 (P188), in preservation of meniscal tissue following trauma through maintenance of meniscal glycosaminoglycan (GAG) content and mechanical properties. Flemish Giant rabbits were subjected to a closed knee joint, traumatic compressive impact with the joint constrained to prevent anterior tibial translation. The contralateral limb served as an un-impacted control. Six animals (treated) received an injection of P188 in phosphate buffered saline (PBS) post trauma, and another six animals (sham) received a single injection of PBS to the impacted limb. Histological analyses for GAG was determined 6 weeks post trauma, and functional outcomes were assessed using stress relaxation micro-indentation. The impacted limbs of the sham group demonstrated a significant decrease in meniscal GAG coverage compared to non-impacted limbs (p<0.05). GAG coverage of the impacted P188 treated limbs was not significantly different than contralateral non-impacted limbs in all regions except the medial anterior (p<0.05). No significant changes were documented in mechanics for either the sham or treated groups compared to their respective control limbs. This suggests that a single intra-articular injection of P188 shows promise in prevention of trauma induced GAG loss.
Asunto(s)
Meniscos Tibiales/efectos de los fármacos , Poloxámero/farmacología , Tensoactivos/farmacología , Lesiones de Menisco Tibial , Heridas no Penetrantes/metabolismo , Heridas no Penetrantes/patología , Animales , Fenómenos Biomecánicos/efectos de los fármacos , Fémur/efectos de los fármacos , Fémur/lesiones , Glicosaminoglicanos/metabolismo , Inyecciones , Meniscos Tibiales/metabolismo , Meniscos Tibiales/patología , Poloxámero/administración & dosificación , Conejos , Tensoactivos/administración & dosificaciónRESUMEN
The objective of this study was to induce anterior cruciate ligament (ACL) and meniscal damage, via a single tibiofemoral compressive impact, in order to document articular cartilage and meniscal changes post-impact. Tibiofemoral joints of Flemish Giant rabbits were subjected to a single blunt impact that ruptured the ACL and produced acute meniscal damage. Animals were allowed unrestricted cage activity for 12 weeks before euthanasia. India ink analysis of the articular cartilage revealed higher degrees of surface damage on the impacted tibias (p=0.018) and femurs (p<0.0001) compared to controls. Chronic meniscal damage was most prevalent in the medial central and medial posterior regions. Mechanical tests revealed an overall 19.4% increase in tibial plateau cartilage thickness (p=0.026), 34.8% increase in tibial plateau permeability (p=0.054), 40.8% increase in femoral condyle permeability (p=0.029), and 20.1% decrease in femoral condyle matrix modulus (p=0.012) in impacted joints compared to controls. Both instantaneous and equilibrium moduli of the lateral and medial menisci were decreased compared to control (p<0.02). Histological analyses revealed significantly increased presence of fissures in the medial femur (p=0.036). In both meniscus and cartilage there was a significant decrease in GAG coverage for the impacted limbs. Based on these results it is clear that an unattended combined meniscal and ACL injury results in significant changes to the soft tissues in this experimental joint 12 weeks post-injury. Such changes are consistent with a clinical description of mid to late stage PTOA of the knee.
Asunto(s)
Cartílago Articular/patología , Traumatismos de la Rodilla/patología , Fenómenos Mecánicos , Meniscos Tibiales/patología , Animales , Ligamento Cruzado Anterior/patología , Lesiones del Ligamento Cruzado Anterior , Fenómenos Biomecánicos , Cartílago Articular/lesiones , Fuerza Compresiva , Fémur/lesiones , Fémur/patología , Conejos , Rotura/patología , Tibia/lesiones , Tibia/patología , Lesiones de Menisco Tibial , Factores de TiempoRESUMEN
BACKGROUND: Prior studies have suggested that anatomic double-bundle (DB) posterior cruciate ligament reconstruction (PCLR) reduces residual laxity compared with the intact state better than single-bundle PCLR. Although the anterolateral bundle (ALB) and posteromedial bundle (PMB) reportedly act codominantly, few studies have compared commonly used graft fixation angles and the influence that graft fixation angles have on overall graft forces and knee laxity. HYPOTHESIS: Graft fixation angle combinations of 0°/75° (PMB/ALB), 0°/90°, 0°/105°, 15°/75°, 15°/90°, and 15°/105° would significantly reduce knee laxity from the sectioned PCL state while preventing in vitro graft forces from being overloaded between any of the graft fixation angles. STUDY DESIGN: Controlled laboratory study. METHODS: Nine cadaveric knees were evaluated for the kinematics of the intact, PCL-sectioned, and DB PCLR techniques. The DB technique was varied by fixing the PMB and ALB grafts at the following 6 randomly ordered fixation angle combinations: 0°/75° (PMB/ALB), 0°/90°, 0°/105°, 15°/75°, 15°/90°, and 15°/105°. A 6 degrees of freedom robotic testing system subjected each specimen to an applied 134-N posterior tibial load at 0° to 120° of flexion and 5-N·m external, 5-N·m internal, and 10-N·m valgus rotation torques applied at 60°, 75°, 90°, 105°, and 120° of flexion. The ALB and PMB grafts were fixed to load cells that concurrently measured graft forces throughout kinematic testing. t tests compared the kinematics between groups, and 2-factor models assessed the contribution of ALB and PMB grafts after DB PCLR (P < .05). RESULTS: Consistently, DB PCLR significantly reduced posterior translation compared with the sectioned PCL and was comparable with the intact state during applied posterior tibial loads at flexion angles of greater than 90°; a mean residual laxity of 1.5 mm remained compared with the intact state during applied posterior tibial loads. Additionally, fixing the PMB graft at 15° resulted in significantly larger PMB graft forces compared with fixation at 0° during applied posterior loading, internal rotation, external rotation, and valgus rotation. Similarly, fixing the ALB graft at 75° resulted in significantly larger ALB graft forces compared with fixation of the ALB graft at 90° or 105° during all loading conditions. CONCLUSION: Fixation of the PMB graft at 0° to 15° and the ALB graft at 75° to 105° during DB PCLR were successful in significantly reducing knee laxity from the sectioned state. However, fixation of the PMB graft at 15° versus 0° resulted in significantly increased loads through the PMB graft, and fixation of the ALB graft at 75° versus 90° or 105° resulted in significantly increased loads through the ALB graft. CLINICAL RELEVANCE: This study found that all 6 fixation angle combinations significantly improved knee kinematics compared with the sectioned state at time zero; however, it is recommended that fixation of the PMB graft be performed at 0° because of the significant increases in PMB graft loading that occur with fixation at 15° and that fixation of the ALB graft be performed at 90° or 105° rather than 75° to minimize ALB graft forces, which could lead to graft attenuation or failure over time.
Asunto(s)
Articulación de la Rodilla/fisiopatología , Procedimientos Ortopédicos/métodos , Ligamento Cruzado Posterior/cirugía , Rotación , Tendones/trasplante , Soporte de Peso/fisiología , Adulto , Aloinjertos , Cadáver , Calcáneo/trasplante , Femenino , Humanos , Inestabilidad de la Articulación/fisiopatología , Inestabilidad de la Articulación/cirugía , Articulación de la Rodilla/cirugía , Masculino , Persona de Mediana Edad , Modelos Biológicos , Rango del Movimiento Articular/fisiología , Robótica , Estrés Mecánico , Suturas , TorqueRESUMEN
BACKGROUND: Currently, no consensus exists for the optimal graft fixation angle for anatomic single-bundle (SB) posterior cruciate ligament reconstructions (PCLRs). Additionally, direct graft forces have not been measured. Alternative graft fixation angles and the resultant graft forces should be investigated to optimize the stability of SB PCLRs without overconstraining the knee. HYPOTHESIS: Graft fixation angles of 75°, 90°, and 105° for SB PCLR were hypothesized to improve knee stability compared with the sectioned posterior cruciate ligament state with no evidence of knee overconstraint. STUDY DESIGN: Controlled laboratory study. METHODS: Nine fresh-frozen human cadaveric knees were biomechanically evaluated for the intact, sectioned, and SB PCLR states with the anterolateral bundle graft fixed at 75°, 90°, and 105°. A 6 degrees of freedom robotic system assessed knee laxity with a 134-N posterior load applied at 0° to 120° and 5-N·m external, 5-N·m internal, and 10-N·m valgus rotation torques applied at 60° to 120°. By securing the graft to an external load cell, graft forces were measured throughout kinematic testing. RESULTS: No significant kinematic differences were found among the 3 fixation angles. Each fixation angle resulted in significantly less posterior translation than in the sectioned state at all flexion angles (P < .05), with 4.1 mm of average residual laxity during an applied posterior loading. For all graft fixation angles, internal rotation was significantly increased between 60° and 120° of flexion, and external rotation was significantly increased at 90°, 105°, and 120° of flexion compared with the intact state. Graft forces were not significantly different among the 3 fixation angles and remained below reported loads observed during activities of daily living. CONCLUSION: All tested SB PCLR graft fixation angles restored knee laxity to similar levels; however, persistent laxity resulted in significant increases in knee laxity compared with the intact state during posterior tibial loading at all flexion angles, internal rotation at flexion angles ≥60°, and external rotation at ≥75° of flexion. CLINICAL RELEVANCE: The results of this study suggest that SB PCL graft fixation angles of 75°, 90°, and 105° were comparable in restoring knee kinematics and exposed the graft to similar time-zero loads. However, SB PCLRs did not fully reduce knee laxity to the intact state.
Asunto(s)
Tendón Calcáneo/trasplante , Articulación de la Rodilla/fisiopatología , Procedimientos Ortopédicos/métodos , Ligamento Cruzado Posterior/cirugía , Rotación , Soporte de Peso/fisiología , Adulto , Cadáver , Calcáneo/trasplante , Femenino , Humanos , Inestabilidad de la Articulación/fisiopatología , Inestabilidad de la Articulación/cirugía , Articulación de la Rodilla/cirugía , Masculino , Persona de Mediana Edad , Modelos Biológicos , Rango del Movimiento Articular/fisiología , Robótica , Estrés Mecánico , Suturas , TorqueRESUMEN
BACKGROUND: Single- and double-row arthroscopic reconstruction techniques for acute bony Bankart lesions have been described in the literature. HYPOTHESIS: The double-row fixation technique would provide superior reduction and stability of a simulated bony Bankart lesion at time zero in a cadaveric model compared with the single-row technique. STUDY DESIGN: Controlled laboratory study. METHODS: Testing was performed on 14 matched pairs of glenoids with simulated bony Bankart fractures with a defect width of 25% of the glenoid diameter. Half of the fractures were repaired with a double-row technique, while the contralateral glenoids were repaired with a single-row technique. The quality of fracture reduction was measured with a coordinate measuring machine. To determine the biomechanical stability of the repairs, specimens were preconditioned with 10 sinusoidal cycles between 5 and 25 N at 0.1 Hz and then pulled to failure in the anteromedial direction at a rate of 5 mm/min. Loads at 1 mm and 2 mm of fracture displacement were determined. RESULTS: The double-row technique required significantly higher forces to achieve fracture displacements of 1 mm (mean, 60.6 N; range, 39.0-93.3 N; P = .001) and 2 mm (mean, 94.4 N; range, 43.4-151.2 N; P = .004) than the single-row technique (1 mm: mean, 30.2 N; range, 14.0-54.1 N and 2 mm: mean, 63.7 N; range, 26.6-118.8 N). Significantly reduced fracture displacement was seen after double-row repair for both the unloaded condition (mean, 1.1 mm; range, 0.3-2.4 mm; P = .005) and in response to a 10-N anterior force applied to the defect (mean, 1.6 mm; range, 0.5-2.7 mm; P = .001) compared with single-row repair (unloaded: mean, 2.1 mm; range, 1.3-3.4 mm and loaded: mean, 3.4 mm; range, 1.9-4.7 mm). CONCLUSION: The double-row fixation technique resulted in improved fracture reduction and superior stability at time zero in this cadaveric model. CLINICAL RELEVANCE: This information may influence the surgical technique used to treat large osseous Bankart fractures and the postoperative rehabilitation protocols implemented when such repair techniques are used.
Asunto(s)
Artroscopía/métodos , Fracturas Óseas/fisiopatología , Fracturas Óseas/cirugía , Escápula/lesiones , Escápula/cirugía , Adulto , Fenómenos Biomecánicos , Cadáver , Femenino , Humanos , Masculino , Persona de Mediana Edad , Escápula/fisiopatologíaRESUMEN
Post-traumatic osteoarthritis (PTOA) develops as a result of traumatic loading that causes tears of the soft tissues in the knee. A modified transection model, where the anterior cruciate ligament (ACL) and both menisci were transected, was used on skeletally mature Flemish Giant rabbits. Gross morphological assessments, elastic moduli, and glycosaminoglycan (GAG) coverage of the menisci were determined to quantify the amount of tissue damage 12 weeks post injury. This study is one of the first to monitor meniscal changes after inducing combined meniscal and ACL transections. A decrease in elastic moduli as well as a decrease in GAG coverage was seen.