Optimal posterior screw placement configuration in Sanders 2B calcaneal fractures: A biomechanical study / Configuración y localización óptima de los tornillos posteriores en las fracturas de calcáneo Sanders 2B: estudio biomecánico

Background: Calcaneal fractures can be high energy intra-articular injuries associated with joint depression. Challenges to fracture reduction include lateral wall blow out, medial wall overlap, comminution and central bone loss. Secondary deformity such as hindfoot varus alters foot biomechanics. Minimally invasive approaches with indirect reduction of the calcaneal tuberosity to maintain the reduction using posterior screws is routinely being used in the treatment of joint depression fractures. Biomechanically, optimum screw numbers and configuration is not known. Biomechanical studies have evaluated and proposed different screw configurations, however, it is not clear which configuration best controls varus deformity. This study aims to determine the optimum screw configuration to control varus deformity in Sanders 2B calcaneal fractures. Methods: Sawbone models were prepared to replicate Sanders type 2-B fracture, with central bone loss and comminution. 0.5cm medial wedge of the calcaneal tuberosity was removed to create varus instability. After stabilising posterior facet with a single 4mm partial threaded screw, and applied an 8 hole contoured plate to stabilise the angle of Gissane, inserted one or two 7mm cannulated partially threaded Charlotte™ (Wright Medical Technology, Inc. 5677 Airline Road Arlington, TN) Headless Multi-use Compression (under image guidance) extra screws to control varus and subsidence deformity of the fracture. Coronal plane displacement of the dissociated calcaneal tuberosity fragment relative to the body when applying 5N, 10N and 20N force was measured in millimetres (mm). Results: 2 screws inserted (one medial screw into the sustentaculum talus from inferior to superior and, one lateral screw into the long axis anterior process) provides the least displacement (0.88±0.390 at 5N and 1.7±1.251 at 20N) and the most stable construct (p<0.05) when compared to other configurations...(AU)

Introducción: Las fracturas de calcáneo suelen ser lesiones intraarticulares de alta energía asociadas con hundimiento articular. Además, se añade con frecuencia el estallido de la pared lateral, la superposición de la pared medial, la conminución y la pérdida de hueso bajo la carilla articular. La deformidad secundaria, como el varo del retropié, altera la biomecánica del pie. Nuestra comunidad utiliza cada vez más abordajes mínimamente invasivos con reducción indirecta de la tuberosidad del calcáneo para mantener la reducción mediante tornillos posteriores. Hay estudios que proponen diferentes configuraciones de tornillos, tras experimentación biomecánica, pero aún no es bien conocido qué configuración controla mejor la deformidad en varo. Este estudio tiene como objetivo determinar la configuración óptima del tornillo para controlar la deformidad en varo en las fracturas de calcáneo Sanders 2B. Método: Se prepararon modelos en Sawbone para replicar la fractura de Sanders tipo 2B, con pérdida de hueso central y con conminución. Se eliminó una cuña medial de 0,5cm de la tuberosidad calcánea para crear inestabilidad en varo. Tras estabilizar el ángulo de Gissane con un tornillo aislado parcialmente roscado de 4mm y una placa moldeada, se utilizaron tornillos de compresión multiuso Charlotte (Wright Medical Technology, Inc. 5677 Airline Road Arlington, TN) sin cabeza, canulados y parcialmente roscados de 7mm insertados sobre una AK bajo escopia. El desplazamiento del plano sagital del fragmento de tuberosidad fracturado en comparación con el cuerpo al aplicar una fuerza de 5N, 10N y 20N se midió en milímetros (mm). Resultados: Dos tornillos insertados (un tornillo medial en el sustenaculum tali de inferior a superior y un tornillo lateral en el eje largo del astrágalo) proporciona el menor desplazamiento (0,88±0,390 a 5N y 1,7±1,251 a 20N) y resulta la construcción más estable (p<0,05) en comparación con otras configuraciones...(AU)

[Artículo traducido] Configuración y localización óptima de los tornillos posteriores en las fracturas de calcáneo Sanders 2B: estudio biomecánico / Optimal posterior screw placement configuration in Sanders 2B calcaneal fractures: A biomechanical study

Background: Calcaneal fractures can be high energy intra-articular injuries associated with joint depression. Challenges to fracture reduction include lateral wall blow out, medial wall overlap, comminution and central bone loss. Secondary deformity such as hindfoot varus alters foot biomechanics. Minimally invasive approaches with indirect reduction of the calcaneal tuberosity to maintain the reduction using posterior screws is routinely being used in the treatment of joint depression fractures. Biomechanically, optimum screw numbers and configuration is not known. Biomechanical studies have evaluated and proposed different screw configurations, however, it is not clear which configuration best controls varus deformity. This study aims to determine the optimum screw configuration to control varus deformity in Sanders 2B calcaneal fractures. Methods: Sawbone models were prepared to replicate Sanders type 2-B fracture, with central bone loss and comminution. 0.5cm medial wedge of the calcaneal tuberosity was removed to create varus instability. After stabilising posterior facet with a single 4mm partial threaded screw, and applied an 8 hole contoured plate to stabilise the angle of Gissane, inserted one or two 7mm cannulated partially threaded Charlotte™ (Wright Medical Technology, Inc. 5677 Airline Road Arlington, TN) Headless Multi-use Compression (under image guidance) extra screws to control varus and subsidence deformity of the fracture. Coronal plane displacement of the dissociated calcaneal tuberosity fragment relative to the body when applying 5N, 10N and 20N force was measured in millimetres (mm). Results: 2 screws inserted (one medial screw into the sustentaculum talus from inferior to superior and, one lateral screw into the long axis anterior process) provides the least displacement (0.88±0.390 at 5N and 1.7±1.251 at 20N) and the most stable construct (p<0.05) when compared to other configurations...(AU)

Introducción: Las fracturas de calcáneo suelen ser lesiones intraarticulares de alta energía asociadas con hundimiento articular. Además, se añade con frecuencia el estallido de la pared lateral, la superposición de la pared medial, la conminución y la pérdida de hueso bajo la carilla articular. La deformidad secundaria, como el varo del retropié, altera la biomecánica del pie. Nuestra comunidad utiliza cada vez más abordajes mínimamente invasivos con reducción indirecta de la tuberosidad del calcáneo para mantener la reducción mediante tornillos posteriores. Hay estudios que proponen diferentes configuraciones de tornillos, tras experimentación biomecánica, pero aún no es bien conocido qué configuración controla mejor la deformidad en varo. Este estudio tiene como objetivo determinar la configuración óptima del tornillo para controlar la deformidad en varo en las fracturas de calcáneo Sanders 2B. Método: Se prepararon modelos en Sawbone para replicar la fractura de Sanders tipo 2B, con pérdida de hueso central y con conminución. Se eliminó una cuña medial de 0,5cm de la tuberosidad calcánea para crear inestabilidad en varo. Tras estabilizar el ángulo de Gissane con un tornillo aislado parcialmente roscado de 4mm y una placa moldeada, se utilizaron tornillos de compresión multiuso Charlotte (Wright Medical Technology, Inc. 5677 Airline Road Arlington, TN) sin cabeza, canulados y parcialmente roscados de 7mm insertados sobre una AK bajo escopia. El desplazamiento del plano sagital del fragmento de tuberosidad fracturado en comparación con el cuerpo al aplicar una fuerza de 5N, 10N y 20N se midió en milímetros (mm). Resultados: Dos tornillos insertados (un tornillo medial en el sustenaculum tali de inferior a superior y un tornillo lateral en el eje largo del astrágalo) proporciona el menor desplazamiento (0,88±0,390 a 5N y 1,7±1,251 a 20N) y resulta la construcción más estable (p<0,05) en comparación con otras configuraciones...(AU)

Optimal posterior screw placement configuration in Sanders 2B calcaneal fractures: A biomechanical study.

BACKGROUND: Calcaneal fractures can be high energy intra-articular injuries associated with joint depression. Challenges to fracture reduction include lateral wall blow out, medial wall overlap, comminution and central bone loss. Secondary deformity such as hindfoot varus alters foot biomechanics. Minimally invasive approaches with indirect reduction of the calcaneal tuberosity to maintain the reduction using posterior screws is routinely being used in the treatment of joint depression fractures. Biomechanically, optimum screw numbers and configuration is not known. Biomechanical studies have evaluated and proposed different screw configurations, however, it is not clear which configuration best controls varus deformity. This study aims to determine the optimum screw configuration to control varus deformity in Sanders 2B calcaneal fractures. METHODS: Sawbone models were prepared to replicate Sanders type 2-B fracture, with central bone loss and comminution. 0.5cm medial wedge of the calcaneal tuberosity was removed to create varus instability. After stabilising posterior facet with a single 4mm partial threaded screw, and applied an 8 hole contoured plate to stabilise the angle of Gissane, inserted one or two 7mm cannulated partially threaded Charlotte™ (Wright Medical Technology, Inc. 5677 Airline Road Arlington, TN) Headless Multi-use Compression (under image guidance) extra screws to control varus and subsidence deformity of the fracture. Coronal plane displacement of the dissociated calcaneal tuberosity fragment relative to the body when applying 5N, 10N and 20N force was measured in millimetres (mm). RESULTS: 2 screws inserted (one medial screw into the sustentaculum talus from inferior to superior and, one lateral screw into the long axis anterior process) provides the least displacement (0.88±0.390 at 5N and 1.7±1.251 at 20N) and the most stable construct (p<0.05) when compared to other configurations. A single medial screw into the sustentaculum tali (conf. 3) resulted in the least stable construct and most displacement (4.04±0.971 at 5N and 11.24±7.590 at 20N) (p<0.05). CONCLUSION: This study demonstrates the optimal screw configuration to resist varus in calcaneal fractures using minimally invasive techniques. Optimal stability is achieved using 2 screws; one located along the long axis of the calcaneus (varus control) and the other placed in the short axis directed towards the posterior facet of the calcaneus (control varus and subsidence). Further cadaver research would help evaluate optimal screw placement in simulated fractures to further assess reproducibility.

Optimal posterior screw placement configuration in Sanders 2B calcaneal fractures: A biomechanical study. / [Artículo traducido] Configuración y localización óptima de los tornillos posteriores en las fracturas de calcáneo Sanders 2B: estudio biomecánico.

BACKGROUND: Calcaneal fractures can be high energy intra-articular injuries associated with joint depression. Challenges to fracture reduction include lateral wall blow out, medial wall overlap, comminution and central bone loss. Secondary deformity such as hindfoot varus alters foot biomechanics. Minimally invasive approaches with indirect reduction of the calcaneal tuberosity to maintain the reduction using posterior screws is routinely being used in the treatment of joint depression fractures. Biomechanically, optimum screw numbers and configuration is not known. Biomechanical studies have evaluated and proposed different screw configurations, however, it is not clear which configuration best controls varus deformity. This study aims to determine the optimum screw configuration to control varus deformity in Sanders 2B calcaneal fractures. METHODS: Sawbone models were prepared to replicate Sanders type 2-B fracture, with central bone loss and comminution. 0.5 cm medial wedge of the calcaneal tuberosity was removed to create varus instability. After stabilising posterior facet with a single 4 mm partial threaded screw, and applied an 8 hole contoured plate to stabilise the angle of Gissane, inserted one or two 7 mm cannulated partially threaded CharlotteTM (Wright Medical Technology, Memphis, USA) Headless Multi-use Compression (under image guidance) extra screws to control varus and subsidence deformity of the fracture. Coronal plane displacement of the dissociated calcaneal tuberosity fragment relative to the body when applying 5 N, 10 N and 20 N force was measured in millimetres (mm). RESULTS: 2 screws inserted (one medial screw into the sustentaculum talus from inferior to superior and, one lateral screw into the long axis anterior process) provides the least displacement (0.88 ± 0.390 at 5 N and 1.7 ± 1.251 at 20 N) and the most stable construct (p < 0.05) when compared to other configurations. A single medial screw into the sustentaculum tali (conf. 3) resulted in the least stable construct and most displacement (4.04 ± 0.971 at 5 N and 11.24 ± 7.590 at 20 N) (p < 0.05). CONCLUSION: This study demonstrates the optimal screw configuration to resist varus in calcaneal fractures using minimally invasive techniques. Optimal stability is achieved using 2 screws; one located along the long axis of the calcaneus (varus control) and the other placed in the short axis directed towards the posterior facet of the calcaneus (control varus and subsidence). Further cadaver research would help evaluate optimal screw placement in simulated fractures to further assess reproducibility.

Trend in Spain in the use of total ankle arthroplasty versus arthrodesis in the period 1997-2017. / Tendencia en España en el uso de artroplastia total de tobillo frente a artrodesis en el periodo 1997-2017.

OBJECTIVE: The main objective of this study is to compare proportionally the incidence of total ankle arthroplasty (TAA) versus ankle arthrodesis and to determine the variables that may have influenced its indication. The secondary objective is to analyse the trend in the use of TAA using a population-based analysis and to compare our results with those reported by national registries in other countries. MATERIAL AND METHOD: A retrospective review of the Minimum Basic Data Set from 1997-2017 was performed. Subjects were categorised according to surgical procedure. Their temporal evolution was analysed and hospital variables associated with the indication (age, sex, hospital complexity) were identified. In order to compare the trend in Spain with respect to other countries, the information was standardised as number of procedures per 100,000 inhabitants/year and a projection was made for the five-year period 2020-2025. RESULTS: In the period 1997-2017, 11,669 ankle arthrodesis and 1,049 TAAs were performed. The trend was increasing and significant for both procedures, however, in the last 10 years analysed the proportional trend of TAA decreased significantly. Being female (OR 1.32), being 65 years or older (OR 1.50) and being operated in a complex hospital (OR 1.31) were associated with the indication for a TAA. Compared to other countries, Spain has much lower rates of TAA utilisation, with minimal growth estimated for the year 2025. CONCLUSION: Although the use of TAA has increased, its growth has been lower than that of ankle arthrodesis and its current trend is proportionally decreasing, with female sex, age≥65 years and the patient being operated in a medium/high complexity hospital being associated with the indication for TAA. Compared with other countries, Spain has much lower rates of use and its projection over the next five years, although increasing, is expected to be minimal.

Matrix-induced autologous chondrocyte implantation grafting in osteochondral lesions of the talus: Evaluation of cartilage repair using T2 mapping.

Osteochondral lesions of the talus may be treated with different autologous biological approaches. These include platelet-rich plasma, stem cells or MACI and ACI. MACI implants are used to cover cartilage lining defects in the ankle. A total of 18 patients were treated with MACI implants. NMR images were taken before and after the procedure. T2 mapping was used to quantify the changes in cartilage collagen after a 6 12-month postoperative period. Increase in collagen was recorded on all patients. Both open and arthroscopic procedures were performed depending on the technical difficulties encountered during the repair.

Estudio prospectivo aleatorizado sobre la influencia del bloqueo distal del clavo Gamma 3 en el tratamiento de las fracturas pertrocantéreas de fémur / Randomized prospective study on the influence distal block and Gamma 3 nail on the treatment of intertrochanteric fractures of femur

Objetivo. El propósito de este estudio es valorar la necesidad de bloquear distalmente los clavos Gamma 3 (Stryker. Mahwah, New Jersey. USA) en fracturas pertrocantéreas de fémur 31-A1 y 31-A2 de la AO. Material y métodos. Desde junio de 2011 hasta enero de 2013 se recoge una muestra formada por 177 pacientes con fractura pertrocantérea de fémur tratados en nuestro centro mediante osteosíntesis con clavo Gamma 3 estándar. Es un estudio prospectivo y aleatorizado según el año de nacimiento de cada paciente, par con bloqueo o impar sin bloqueo distal del clavo, formando dos grupos de 90 y 87 fracturas respectivamente. Resultados. En los pacientes intervenidos mediante clavo con bloqueo distal se observó una mayor incidencia de complicaciones médicas, una menor incidencia de complicaciones biomecánicas y un aumento en el colapso del foco de fractura en comparación con el grupo control, siendo estas diferencias estadísticamente significativas (p < 0,05). También se observa en el grupo con bloqueo distal un mayor requerimiento transfusional y una mayor tasa de éxitus presentando diferencias estadísticamente significativas (p < 0,05), sin embargo esta significación desaparece al ajustar los resultados por otras características relacionadas con los pacientes. Conclusiones. Basándonos en los resultados hallados en este trabajo, el uso del tornillo de bloqueo distal en los clavos Gamma 3 debe restringirse a fracturas pertrocantéreas inestables tras reducción donde se requiera una estabilidad adicional al clavo intramedular, pudiendo así disminuir el riesgo de complicaciones derivadas de su uso (AU)

Objective. The purpose of this study is to assess the need to lock the Gamma 3 nail (Stryker, Mahwah New Jersey USA) distally for intertrochanteric fractures of femur 31-A1 and 31-A2 of the AO. Material and methods. Details were recorded on a sample of 177 patients with intertrochanteric femoral fractures treated in our hospital by a standard Gamma nail between June 2011 and January 2013. A prospective study was conducted by randomizing patients by year of birth, even numbers with, or odd number without, distal locking, forming two groups of 90 and 87 fractures, respectively. Results. The patients treated with a distal locking nail had an increased incidence of medical complications, a lower incidence of biomechanical complications, and an increase in the fracture collapse compared with the control group, with statistical significance (p < 0 .05). It is also observed in the group with distal locking increased transfusion requirement and a higher death rate, with statistically significant differences (p < 0 .05), but this significance disappears when adjusting for other patient-related characteristics. Conclusions. Based on the results found in this work, the use of distal locking screw in the Gamma 3 nails should be restricted to unstable trochanteric fractures after reduction where additional stability to the intramedullary nail is required, and may decrease the risk of complications from use (AU)

[Randomized prospective study on the influence distal block and Gamma 3 nail on the treatment of intertrochanteric fractures of femur]. / Estudio prospectivo aleatorizado sobre la influencia del bloqueo distal del clavo Gamma 3 en el tratamiento de las fracturas pertrocantéreas de fémur.

OBJECTIVE: The purpose of this study is to assess the need to lock the Gamma 3 nail (Stryker, Mahwah New Jersey USA) distally for intertrochanteric fractures of femur 31-A1 and 31-A2 of the AO. MATERIAL AND METHODS: Details were recorded on a sample of 177 patients with intertrochanteric femoral fractures treated in our hospital by a standard Gamma nail between June 2011 and January 2013. A prospective study was conducted by randomizing patients by year of birth, even numbers with, or odd number without, distal locking, forming two groups of 90 and 87 fractures, respectively. RESULTS: The patients treated with a distal locking nail had an increased incidence of medical complications, a lower incidence of biomechanical complications, and an increase in the fracture collapse compared with the control group, with statistical significance (p < 0.05). It is also observed in the group with distal locking increased transfusion requirement and a higher death rate, with statistically significant differences (p < 0.05), but this significance disappears when adjusting for other patient-related characteristics. CONCLUSIONS: Based on the results found in this work, the use of distal locking screw in the Gamma 3 nails should be restricted to unstable trochanteric fractures after reduction where additional stability to the intramedullary nail is required, and may decrease the risk of complications from use.

Anestesia subaracnoidea de urgencia en posición de decúbito prono / No disponible

No disponible

Técnicas regionales en traumatología del miembro inferior en cirugía mayor ambulatoria / Regional anesthesia in traumatology ambulatory surgery for lower limb

Objetivo: Revisar las diferentes técnicas de anestesia loco regionales utilizadas en cirugía traumatológica y ortopédica mayor ambulatoria, analizando las ventajas, los inconvenientes así como las complicaciones y la forma redisminuir su incidencia. Las técnicas regionales especialmente los bloqueos periféricos y la anestesia local de rodilla son una excelente opción en CMA. De las neuroaxiales la epidural tiene unos resultados muy similares a la anestesia general y la intradural deberá realizarse con dosis bajas de anestésico. El control en la perfusión de líquidos perioperatorios es un factor de relevancia en la incidencia de la retención urinaria (AU)

Objetive: To review the different locoregional anesthetic techniques used in ambulatory major traumatologic and orthopedic surgery, analyzing the advantages, inconveniences and complications, with a view to reducing their incidence. Regional techniques, particularly peripheral blocks and local anesthesia of the knee, are an excellent option in ambulatory major surgery. Among the neuroaxial techniques, epidural anesthesia offers results very similar to those of general anesthesia, and the intradural technique must be performed with low anesthetic doses. Control of perioperative fluid perfusion is a relevant factor in terms of the incidence of urinary retention (AU)

Biomecánica de las prótesis de rodilla / Biomechanics of the knee prosthesis

Las prótesis totales de rodilla constituyen uno de los implantesmás colocados en el ámbito de la ortopedia. El númerode modelos existentes en el mercado es muy elevadoy todos tienen sus características. A pesar de ello podemosagrupar las artroplastias de rodilla por estas caracterísricas,siendo las prótesis de platillo móvil el grupo más novedoso.Revisamos la bibliogrfía más reciente sobre la biomecánicade las prótesis totales de rodilla, englobando aspectos comolos materiales, el polietileno, la fijación, la geometría ola presencia del ligamento cruzado posterior para entenderen profundidad el funcionemiento de una PTR

Total knee prostheses (TKAs) are one of the most frequentimplants we use like orthpaedists. There are a largenumber of models and all of them have their characteristics.Despite of it we can group TKAs in avery few ones inwhich mobile-bearing arthroplasty in the newness. We reviewthe literature about biomechanics of TKAs includingmaterials, UHMWPE, fixation of the prostheses, geometryor presence of the cruciate posterior ligament to really understandarthroplasty working

Biomecánica de la rodilla / Biomechanics of the knee

La biomecánica de la rodilla todavía no se conoce exactamente.Diversos patrones se han establecido, pero ningunoha alcanzado el funcionamiento real de la articulación.Revisamos la bibliografía y presentamos la evolucióndel entendimiento del movimiento de la rodilla hasta llegaral modelo de seis grados de libertad en la zona patelofemoraly en la tibiofemoral. Este modelo parece ser el másaproximado a la realidad en cuanto a la cinemática de larodilla

Knee´s biomechanics is not well known yet. A largenumber of patterns has been stablished, but neither ofthem has reached the right articular movement. We reviewthe literature and present the understanding about kneemovement until six grades of freedom model in patello-femoraland tibio-femoral zones. This model seems to be themost approximate to reality in knee kinematics

[Combined sciatic and inguinal paravascular nerve block: a valid alternative for arthroscopic knee surgery]. / Bloqueo ciático y paravascular inguinal para cirugía artroscópica de rodilla, una alternativa válida.

OBJECTIVE: To assess the effectiveness of a combined transgluteal sciatic and inguinal paravascular nerve block for arthroscopic knee surgery. MATERIAL AND METHODS: Prospective descriptive study of 88 patients scheduled for arthroscopic knee surgery. Using a nerve stimulator and a transgluteal approach, we infiltrated the sciatic nerve with 20 mL of 1.5% mepivacaine. Then, with the patient in supine position, we located the femoral nerve and inserted a plastic catheter into the descending inguinal canal, applying pressure near the tip, to inject 20 mL of 1% mepivacaine. We evaluated a) anesthetic effectiveness, b) tolerance of the pressure cuff, c) time in the intensive care recovery unit, and d) time until reversal of the block. RESULTS: Anesthesia was efficacious for 89.77% of the patients: excellent for 54 patients (61.36%), good for 25 (28.41%), and insufficient for 9 (10.23%). The pressure cuff was well tolerated by 70 patients (79.54%) and caused discomfort for 18 (20.45%). Mean postoperative stay in the intensive care recovery unit was 19.05 (SD 8.11) minutes. Reversal took place at a mean 204.09 (SD 22.59) minutes for the sensory nerve block and at 223.45 (SD 20) minutes for the motor block. CONCLUSIONS: The combined sciatic and inguinal paravascular block is effective for arthroscopic knee surgery and offers an alternative when other anesthetic techniques cannot be used. Use of a pressure cuff may require complementary sedation.

[Continuous parascalene block for shoulder surgery]. / Bloqueo paraescalénico continuo en la cirugía del hombro.

OBJECTIVE: To evaluate the efficacy and incidence of side effects of parascalene brachial plexus block for shoulder surgery and for postoperative analgesia. PATIENTS AND METHODS: This prospective descriptive study enrolled 186 patients scheduled for conventional (open) and arthroscopic shoulder operations. The parascalene approach to the brachial plexus was used, with an 18-G x 4.5 cm cannula (30 degrees bevel), applying the technique of detecting perforation of the prevertebral fascia. Mepivacaine 1.5% was administered for anesthesia, beginning with a test dose of 5 ml followed by doses of 25 ml. Bupivacaine 0.125% with 1/400,000 adrenaline was given for postoperative analgesia. Two groups were established according to type of surgery. In group A were patients undergoing open surgery and those with articular stiffness undergoing arthroscopic surgery; analgesics were delivered in continuous perfusion of 5 to 8 ml/h. Group B patients, who underwent arthroscopic surgery, received the analgesic in boluses of 10 to 14 ml every 4 to 6 hours. We assessed perception of perforation of the fascia, provocation of paresthesia, number of puncture attempts, anesthetic efficacy, postsurgical analgesia (visual analogue scale from 0 to 10) and complications. RESULTS: Blockade was effective for 155 of the 186 patients (83.33%). In 118 (63.44%) the perception of perforation of the prevertebral fascia was ostensible, in 52 (27.95%) it was slight and in 16 (8.6%) it was undetectable. Paresthesia was triggered by the cannula in 18 cases (9.13%) and by the test dose in 181 cases (97.31%). The mean number of puncture attempts was 1.2 +/- 0.09 per patient. During the early postoperative period analgesia was adequate for 92 (84.40%) of the 109 patients in group A. In group B, 45 patients (97.82%) required 1 to 2 analgesic doses (mean 1.4 +/- 2 doses) and one patient (2.17%) needed 6 doses within the first 24 hours. Catheters remained inserted as long as 36 hours to 10 days (mean 3.5 days) in group A. In group B they had been removed by 24 hours. Complications were transitory and slight. No cases of pneumothorax, no intra- or epidural anesthesia was required and no instances of vascular puncture occurred. CONCLUSIONS: The parascalene approach is easy to use and entails few risks while providing excellent anesthetic conditions for open and arthroscopic shoulder operations. It is useful for ambulatory analgesia to facilitate early rehabilitation after surgery.