RESUMEN
OBJECTIVE: Adjacent segment degeneration (ASD) is a common phenomenon after lumbar fusion. Lateral lumbar interbody fusion (LLIF) may provide an alternative treatment method for ASD. This study used finite element analysis to evaluate the biomechanical effects of LLIF with various fixation options and identify an optimal surgical strategy for ASD. METHODS: A validated L1-S1 finite element model was modified for simulation. Six finite element models of the lumbar spine were created and were divided into group 1 (L4-5 posterior lumbar interbody fusion [PLIF] + L3-4 LLIF) and group 2 (L5-S1 PLIF + L4-5 LLIF). Each group consisted of 1) cage-alone, 2) cage + lateral screw fixation (LSF), and 3) cage + bilateral pedicle screw fixation (BPSF) models. The range of motion, intradiscal pressure, and facet loads of adjacent segments as well as interbody cage stress were analyzed. RESULTS: The stress on the LLIF cage-superior endplate interface was highest in the cage-alone model followed by the cage + LSF model and cage + BPSF model. The increase in range of motion, intradiscal pressure, and facet loads at the adjacent segment was highest in the cage + BPSF model followed by the cage + LSF model and cage-alone model. However, the biomechanical effect on the adjacent segment seemed similar in the cage-alone and cage + LSF models. CONCLUSIONS: LLIF with BPSF is recommended when performing LLIF surgery for ASD after L4-5 and L5-S1 PLIF. Considering cage subsidence and biomechanical effects on the adjacent segment, LLIF with LSF may be a suboptimal option for ASD surgery.
Asunto(s)
Tornillos Pediculares , Fusión Vertebral , Humanos , Análisis de Elementos Finitos , Fenómenos Biomecánicos , Rango del Movimiento Articular , Fusión Vertebral/métodos , Vértebras Lumbares/diagnóstico por imagen , Vértebras Lumbares/cirugíaRESUMEN
Tendon rupture induces an inflammatory response characterized by release of pro-inflammatory cytokines and impaired tendon performance. This study sought to investigate the therapeutic effects of simvastatin-loaded porous microspheres (SIM/PMSs) on inflamed tenocytes in vitro and collagenase-induced Achilles tendinitis in vivo. The treatment of SIM/PMSs in lipopolysaccharide (LPS)-treated tenocytes reduced the mRNA expressions of pro-inflammatory cytokines (Matrix metalloproteinase-3 (MMP-3), cyclooxygenase-2 (COX-2), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α)). In addition, the local injection of SIM/PMSs into the tendons of collagenase-induced Achilles tendinitis rat models suppressed pro-inflammatory cytokines (MMP-3, COX-2, IL-6, TNF-α, and MMP-13). This local treatment also upregulated anti-inflammatory cytokines (IL-4, IL-10, and IL-13). Furthermore, treatment with SIM/PMSs also improved the alignment of collagen fibrils and effectively prevented collagen disruption in a dose-dependent manner. Therefore, SIM/PMSs treatment resulted in an incremental increase in the collagen content, stiffness, and tensile strength in tendons. This study suggests that SIM/PMSs have great potential for tendon healing and restoration in Achilles tendinitis.
Asunto(s)
Antiinflamatorios/farmacología , Microesferas , Simvastatina/farmacología , Tendinopatía/tratamiento farmacológico , Tenocitos/efectos de los fármacos , Tendón Calcáneo/patología , Animales , Antiinflamatorios/administración & dosificación , Células Cultivadas , Colágeno/genética , Colágeno/metabolismo , Colagenasas/toxicidad , Ciclooxigenasa 2/genética , Ciclooxigenasa 2/metabolismo , Interleucinas/genética , Interleucinas/metabolismo , Lipopolisacáridos/toxicidad , Metaloproteinasas de la Matriz/genética , Metaloproteinasas de la Matriz/metabolismo , Ratas , Ratas Sprague-Dawley , Simvastatina/administración & dosificación , Tendinopatía/etiología , Tenocitos/metabolismo , Factor de Necrosis Tumoral alfa/genética , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
BACKGROUND: A new instrument system has been introduced to improve the accuracy and reproducibility of implant positioning in Oxford® unicompartmental knee arthroplasty (UKA). This study aimed to determine if the new instrumentation could improve postoperative implant positioning and limb alignment, and reduce the occurrence of outliers in Oxford® UKA. METHODS: A total of 77 cases of Oxford® UKA with the new instrumentation were included. Individual matching for the conventional instrument group was performed according to age, sex, and body mass index. Postoperative radiological variables, including the hip-knee-ankle angle and the varus/valgus and flexion/extension angles of the femoral and tibial implants, were measured and compared between the new instrumentation group and the conventional group. The outliers in implant positions and postoperative complications were also compared. RESULTS: No significant between-group differences were observed in terms of lower limb alignment and tibial implant alignment. However, statistically significant differences were identified in the varus/valgus and flexion/extension angles of the femoral implant (P=0.01 and P<0.001, respectively). More outliers were observed in the flexion/extension angles of the femoral and tibial implants in the new instrumentation group. Eight meniscal bearing dislocations and three lateral compartmental degenerative changes were found in the conventional group, while there were two meniscal bearing dislocations in the new instrumentation group during the study period. CONCLUSION: The present study did not confirm any benefit of the new instrument system in terms of postoperative limb alignment, positioning of the implant, or reducing outliers beyond the use of the conventional instruments.
Asunto(s)
Artroplastia de Reemplazo de Rodilla/instrumentación , Articulación de la Rodilla/diagnóstico por imagen , Prótesis de la Rodilla , Anciano , Femenino , Humanos , Articulación de la Rodilla/cirugía , Masculino , Osteoartritis de la Rodilla/cirugía , Estudios RetrospectivosRESUMEN
A3 intertrochanteric fracture has a higher incidence of intraoperative re-displacement than A1 and 2. The authors have also experienced difficulty with maintenance of reduction in A3 intertrochanteric fractures, as the technique depends on manual effort and can fail easily during the procedure. It induced us to develop this surgical technique to ease the surgical procedure and improve clinical outcomes. This paper introduces a modified provisional guide pin fixation technique applicable to even AO/OTA A3 intertrochanteric fractures, and presents preliminary results of 11 patients who were treated by provisional pin fixation-assisted nailing in A3 intertrochanteric fractures. Using this technique, we have reduced the chances of intraoperative reduction loss and achieved favorable clinical outcomes.