[Translated article] In vitro elution of local anaesthetics from PMMA bone cement.

BACKGROUND AND AIM: Currently, we do not have a gold standard for pain management after total knee arthroplasty. We may use one of more drug delivery systems, none of which are ideal. An ideal depot delivery system would provide therapeutic, nontoxic, doses of drug at the surgical side, especially during 72h postoperatively. The bone cement used in arthroplasties has been used as a drug delivery system, especially antibiotics, since 1970. Based on this principle, we developed this study with the aim to characterize the elution profile of two local anaesthetics (lidocaine hydrochloride and bupivacaine hydrochloride) from PMMA (polymethilmethacrylate) bone cement. MATERIAL AND METHODS: Palacos® R+G bone cement and lidocaine hydrochloride or bupivacaine hydrochloride specimens were obtained depending on the study group. These specimens were immersed in PBS (phosphate buffered saline) and removed from the solution at different set times. Subsequently, the concentration of local anaesthetic in the liquid was analyzed by liquid chromatography. RESULTS: The percentage of lidocaine eluted from PMMA bone cement in this study was 9.74% of the total lidocaine content per specimen at 72h and 18.73% at 336h (14 days). In case of bupivacaine, the elution percentage was 2.71% of the total bupivacaine content per specimen at 72h and 2.70% at 336h (14 days). CONCLUSIONS: Local anaesthetics elute in vitro from PMMA bone cement, reaching doses at 72h close to the doses used in anaesthetic blocks.

[Translated article] Study of femoral component malrotation as a cause of pain after total knee arthroplasty.

INTRODUCTION: The total knee arthroplasty (TKA) has been shown to be a successful and cost-benefit procedure in terms of pain improvement in patient with symptomatic knee osteoarthritis. However, almost a 20% of the patients are not satisfied with the result of the surgery. MATERIAL AND METHOD: We have carried out a transversal unicentric cases controls study with clinical cases of the own hospital, obtained by a clinical records revision. A total of 160 patients with a TKA with at least 1 year of follow-up were selected. Demographic variables, functional scales (WOMAC and VAS) and rotation of the femoral component through the analysis of the images obtained by CT scan were collected. RESULTS: The total was 133 patients that was divided in two groups. A control group and pain group. The Control group was made up of 70 patients with a mean age of 69.59 years (23 men and 47 women) and the pain group was made up of 63 patients with a mean age of 69.48 years (13 men and 50 women). We didn't find difference regarding the analysis of the rotation of the femoral component. In addition, we were not found significant differences when applying a stratification by sex. And, the analysis of the malrotation of the femoral component, previously defining limits of value rotation considered as extreme, in any of the case did not show significant differences. CONCLUSION: The results of the study confirm that malrotation of the femoral component had no influence on the presence of pain at a minimum of one year of follow-up after TKA implantation.

[Translated article] In vitro elution of local anaesthetics from PMMA bone cement.

BACKGROUND AND AIM: Currently, we do not have a gold standard for pain management after total knee arthroplasty. We may use one of more drug delivery systems, none of which are ideal. An ideal depot delivery system would provide therapeutic, nontoxic, doses of drug at the surgical side, especially during 72h postoperatively. The bone cement used in arthroplasties has been used as a drug delivery system, especially antibiotics, since 1970. Based on this principle, we developed this study with the aim to characterise the elution profile of two local anaesthetics (lidocaine hydrochloride and bupivacaine hydrochloride) from PMMA (polymethilmethacrylate) bone cement. MATERIAL AND METHODS: Palacos® R+G bone cement and lidocaine hydrochloride or bupivacaine hydrochloride specimens were obtained depending on the study group. These specimens were immersed in PBS (phosphate buffered saline) and removed from the solution at different set times. Subsequently, the concentration of local anaesthetic in the liquid was analysed by liquid chromatography. RESULTS: The percentage of lidocaine eluted from PMMA bone cement in this study was 9.74% of the total lidocaine content per specimen at 72h and 18.73% at 336h (14 days). In case of bupivacaine, the elution percentage was 2.71% of the total bupivacaine content per specimen at 72h and 2.70% at 336h (14 days). CONCLUSIONS: Local anaesthetics elute in vitro from PMMA bone cement, reaching doses at 72h close to the doses used in anaesthetic blocks.

In vitro elution of local anesthetics from PMMA bone cement. / Estudio in vitro de elución de anestésicos locales en cemento óseo de PMMA.

BACKGROUND AND AIM: Currently, we do not have a gold standard for pain management after total knee arthroplasty. We may use one of more drug delivery systems, none of which are ideal. An ideal depot delivery system would provide therapeutic, nontoxic, doses of drug at the surgical side, especially during 72h postoperatively. The bone cement used in arthroplasties has been used as a drug delivery system, especially antibiotics, since 1970. Based on this principle, we developed this study with the aim to characterize the elution profile of two local anesthetics (lidocaine hydrochloride and bupivacaine hydrochloride) from PMMA (polymethilmethacrylate) bone cement. MATERIAL AND METHODS: Palacos® R+G bone cement and lidocaine hydrochloride or bupivacaine hydrochloride specimens were obtained depending on the study group. These specimens were immersed in PBS (phosphate buffered saline) and removed from the solution at different set times. Subsequently, the concentration of local anesthetic in the liquid was analyzed by liquid chromatography. RESULTS: The percentage of lidocaine eluted from PMMA bone cement in this study was 9.74% of the total lidocaine content per specimen at 72h and 18.73% at 336h (14 days). In case of bupivacaine, the elution percentage was 2.71% of the total bupivacaine content per specimen at 72h and 2.70% at 336h (14 days). CONCLUSIONS: Local anesthetics elute in vitro from PMMA bone cement, reaching doses at 72h close to the doses used in anesthetic blocks.

Study of femoral component malrotation as a cause of pain after total knee arthroplasty. / Estudio de la malrotación del componente femoral como causa de dolor tras la implantación de una artroplastia total de rodilla.

INTRODUCTION: The total knee arthroplasty (TKA) has been shown to be a successful and cost-benefit procedure in terms of pain improvement in patient with symptomatic knee osteoarthritis. However, almost a 20% of the patients are not satisfied with the result of the surgery. MATERIAL AND METHOD: We have carried out a transversal unicentric cases controls study with clinical cases of the own hospital, obtained by a clinical records revision. A total of 160 patients with a TKA with at least 1year of follow-up were selected. Demographic variables, functional scales (WOMAC and VAS) and rotation of the femoral component through the analysis of the images obtained by CT scan were collected. RESULTS: The total was 133 patients that was divided in two groups. A control group and pain group. The control group was made up of 70 patients with a mean age of 69.59years (23 men and 47 women) and the pain group was made up of 63 patients with a mean age of 69.48years (13 men and 50 women). We did not found difference regarding the analysis of the rotation of the femoral component. In addition, we were not found significant differences when applying a stratification by sex. The analysis of the malrotation of the femoral component, previously defining limits of value rotation considered as extreme, in any of the case did not show significant differences. CONCLUSION: The results of the study confirm that malrotation of the femoral component had no influence on the presence of pain at a minimum of one year of follow-up after TKA implantation.

[Translated article] Current situation of robotics in knee prosthetic surgery: A technology that has come to stay?

Robotic surgery is a surgical technique that is on the rise. The goal of robotic-assisted total knee arthroplasty (RA-TKA) is to provide the surgeon with a tool to accurately execute bone cuts according to previous surgical planning to restore knee kinematics and balance of soft tissue, being able to precisely apply the type of alignment that we choose. In addition, RA-TKA is a very useful tool for training. Within the limitations, there is the learning curve, the need for specific equipment, the high cost of the devices, the increase in radiation in some systems and that each robot is linked to a specific type of implant. Current studies show, with RA-TKA, variations in the alignment of the mechanical axis are reduced, postoperative pain is improved and earlier discharge is facilitated. On the other hand, there are no differences in terms of range of motion, alignment, gap balance, complications, surgical time or functional results.

Current situation of robotics in knee prosthetic surgery, a technology that has come to stay? / Situación actual de la robótica en cirugía protésica de rodilla, ¿una tecnología que ha venido para quedarse?

Robotic surgery is a surgical technique that is on the rise. The goal of robotic-assisted total knee arthroplasty (RA-TKA) is to provide the surgeon with a tool to accurately execute bone cuts according to previous surgical planning to restore knee kinematics and balance of soft tissue, being able to precisely apply the type of alignment that we choose. In addition, RA-TKA is a very useful tool for training. Within the limitations, there is the learning curve, the need for specific equipment, the high cost of the devices, the increase in radiation in some systems and that each robot is linked to a specific type of implant. Current studies show, with RA-TKA, variations in the alignment of the mechanical axis are reduced, postoperative pain is improved and earlier discharge is facilitated. On the other hand, there are no differences in terms of range of motion, alignment, gap balance, complications, surgical time or functional results.

[Interlocking femoral nail and total knee Arthroplasty in one stage for a patient with a femoral diaphyseal stress fracture]. / Enclavado femoral y artroplastía total de rodilla en un tiempo en una paciente con fractura diafisaria femoral por estrés.

We present the case of an 81-year-old woman who was followed up by the Rheumatology Service for osteoporosis and treated with bisphosphonates for more than five years. She reported a fracture of the distal third of the contralateral femur by a low energy mechanism, treated with retrograde intramedullary nailing the previous year. She presented a clinic of cruralgia and left gonalgia, without previous trauma. A scintigraphy and radiographs were performed to support the diagnosis of stress fracture of the distal third of the left femur and osteonecrosis of the left internal femoral condyle. Thinking about the possible complications of performing two interventions in an elderly patient, we decided to complete the treatment in a single time and by the same surgical approach, trying to resolve the osteonecrosis and the fracture at the same time, with the objective of an early rehabilitation and lower morbidity. A femoral retrograde prophylactic nailing was performed to stabilize the stress fracture and a retentive primary knee prosthesis was implanted for the posterior cruciate ligament by the same surgical approach. There were no incidents in the immediate postoperative period, with ambulation beginning with help 48 hours after the intervention. The fracture consolidated and the patient presented a good functional result of the knee, both in the immediate postoperative period and at three years of follow-up.

Presentamos el caso de una mujer de 81 años de edad, en seguimiento por el Servicio de Reumatología por osteoporosis y tratada con bifosfonatos durante más de cinco años. Refirió una fractura del tercio distal del fémur contralateral por mecanismo de baja energía, tratada con enclavado intramedular retrógrado el año anterior. Presentó una clínica de cruralgia y gonalgia izquierda, sin traumatismo previo. Se le realizó una gammagrafía y radiografías que apoyaron el diagnóstico de fractura de estrés del tercio distal del fémur izquierdo y osteonecrosis del cóndilo femoral interno izquierdo. Pensando en las posibles complicaciones de llevar a cabo dos intervenciones en una paciente de avanzada edad, se decidió efectuar el tratamiento en un tiempo y por el mismo abordaje quirúrgico, tratando de resolver la osteonecrosis y la fractura a la vez, con el objetivo de una rehabilitación precoz y menor morbilidad. Se realizó un enclavado profiláctico retrógrado femoral para estabilizar la fractura de estrés y se implantó una prótesis de rodilla primaria retentiva para el ligamento cruzado posterior por el mismo abordaje quirúrgico. No hubo incidencias en el postoperatorio inmediato; se inició deambulación con ayuda a las 48 horas de la intervención. La fractura consolidó y la paciente presentó un buen resultado funcional de la rodilla, tanto en el postoperatorio inmediato como a los tres años de seguimiento.

Enclavado femoral y artroplastía total de rodilla en un tiempo en una paciente con fractura diafisaria femoral por estrés / Interlocking femoral nail and total knee Arthroplasty in one stage for a patient with a femoral diaphyseal stress fracture

Resumen: Presentamos el caso de una mujer de 81 años de edad, en seguimiento por el Servicio de Reumatología por osteoporosis y tratada con bifosfonatos durante más de cinco años. Refirió una fractura del tercio distal del fémur contralateral por mecanismo de baja energía, tratada con enclavado intramedular retrógrado el año anterior. Presentó una clínica de cruralgia y gonalgia izquierda, sin traumatismo previo. Se le realizó una gammagrafía y radiografías que apoyaron el diagnóstico de fractura de estrés del tercio distal del fémur izquierdo y osteonecrosis del cóndilo femoral interno izquierdo. Pensando en las posibles complicaciones de llevar a cabo dos intervenciones en una paciente de avanzada edad, se decidió efectuar el tratamiento en un tiempo y por el mismo abordaje quirúrgico, tratando de resolver la osteonecrosis y la fractura a la vez, con el objetivo de una rehabilitación precoz y menor morbilidad. Se realizó un enclavado profiláctico retrógrado femoral para estabilizar la fractura de estrés y se implantó una prótesis de rodilla primaria retentiva para el ligamento cruzado posterior por el mismo abordaje quirúrgico. No hubo incidencias en el postoperatorio inmediato; se inició deambulación con ayuda a las 48 horas de la intervención. La fractura consolidó y la paciente presentó un buen resultado funcional de la rodilla, tanto en el postoperatorio inmediato como a los tres años de seguimiento.

Abstract: We present the case of an 81-year-old woman who was followed up by the Rheumatology Service for osteoporosis and treated with bisphosphonates for more than five years. She reported a fracture of the distal third of the contralateral femur by a low energy mechanism, treated with retrograde intramedullary nailing the previous year. She presented a clinic of cruralgia and left gonalgia, without previous trauma. A scintigraphy and radiographs were performed to support the diagnosis of stress fracture of the distal third of the left femur and osteonecrosis of the left internal femoral condyle. Thinking about the possible complications of performing two interventions in an elderly patient, we decided to complete the treatment in a single time and by the same surgical approach, trying to resolve the osteonecrosis and the fracture at the same time, with the objective of an early rehabilitation and lower morbidity. A femoral retrograde prophylactic nailing was performed to stabilize the stress fracture and a retentive primary knee prosthesis was implanted for the posterior cruciate ligament by the same surgical approach. There were no incidents in the immediate postoperative period, with ambulation beginning with help 48 hours after the intervention. The fracture consolidated and the patient presented a good functional result of the knee, both in the immediate postoperative period and at three years of follow-up.