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Introduction The loss of bone mass, as a consequence of bone remodelling, in the proximal third of the femur, is a factor that contributes to the failure of hip prostheses in the medium to long term. This periprosthetic remodelling occurs mainly during the first 12 months after the operation. The aim is to evaluate the behaviour at one year of a new anatomical stem, the ANATO® stem (2015-Stryker®), which is a redesign of its predecessor (ABG-II®—Stryker stem) by means of bone densitometry. Method Prospective, controlled study in which the changes in bone mineral density (BMD) observed around the 7 areas of Gruen in a group of 61 patients affected by primary coxarthrosis, in whom an ANATO® stem was implanted, are analysed densitometrically. The healthy hip was taken as the control group. The existence of differences in the remodelling pattern according to sex, age and body mass index (BMI) was compared. The follow-up was during the first year after the intervention. Results After one year of follow-up, decreases of bone mineral density in zone 7 of −5.9% were observed, being this decrease statistically significant. No differences were found in the remodeling pattern according to age, sex and body mass index. Conclusion The ANATO® stem allows an efficient transmission of loads from the stem to the proximal femur. Only in zone 7 significant bone atrophy is observed. Differences in age, BMI and sex do not seem to influence the bone remodelling around this new stem.

Resumen: Introducción: La pérdida de masa ósea, como consecuencia del remodelado óseo, en el tercio proximal del fémur, es un factor que contribuye al fracaso de las prótesis de cadera a medio-largo plazo. Este remodelado periprotésico se desarrolla sobre todo durante los 12 primeros meses tras la intervención.Se pretende evaluar el comportamiento a un año de un nuevo vástago anatómico, el vástago ANATO® (2015-Stryker®), el cual es un rediseño de su predecesor (vástago ABG-ii®--Stryker) mediante densitometría ósea. Material y método: Estudio prospectivo, controlado, en el que se analizan densitométricamente los cambios en la densidad mineral ósea (DMO), observados en torno a las siete áreas de Gruen, en un grupo de 61 pacientes, afectos de coxartrosis primaria, en quienes se implantó un vástago ANATO®. La cadera sana fue tomada como grupo control. Se comparó la existencia de diferencias en el patrón de remodelado según sexo, edad e índice de masa corporal (IMC). El seguimiento fue durante el primer año tras la intervención. Resultados: Al año de seguimiento se aprecian descensos de la densidad mineral ósea en la zona siete, de -5,9%, siendo este descenso estadísticamente significativo. No se encontraron diferencias en el patrón de remodelado según edad, sexo e índice de masa corporal. Conclusión: El vástago ANATO®, permite una transmisión eficiente de cargas desde el vástago al fémur próximal. Únicamente en la zona siete se aprecia atrofia ósea significativa. Las diferencias de edad, IMC y sexo parecen no influir en la remodelación ósea en torno a este nuevo vástago. Abstract: Introduction: The loss of bone mass, as a consequence of bone remodelling, in the proximal third of the femur, is a factor that contributes to the failure of hip prostheses in the medium to long term. This periprosthetic remodelling occurs mainly during the first 12 months after the operation.The aim is to evaluate the behaviour at one year of a new anatomical stem, the ANATO® stem (2015-Stryker®), which is a redesign of its predecessor (ABG-ii®-Stryker stem) by means of bone densitometry. Method: Prospective, controlled study in which the changes in bone mineral density (BMD) observed around the seven areas of Gruen in a group of 61 patients affected by primary coxarthrosis, in whom an ANATO® stem was implanted, are analysed densitometrically. The healthy hip was taken as the control group. The existence of differences in the remodelling pattern according to sex, age and body mass index (BMI) was compared. The follow-up was during the first year after the intervention. Results: After one year of follow-up, decreases of bone mineral density in zone seven of -5.9% were observed, being this decrease statistically significant. No differences were found in the remodelling pattern according to age, sex and body mass index. Conclusion: The ANATO® stem allows an efficient transmission of loads from the stem to the proximal femur. Only in zone seven significant bone atrophy is observed. Differences in age, BMI and sex do not seem to influence the bone remodelling around this new stem.

To establish the pattern of bone remodeling caused by a cementless, anatomic implant, we intend to evaluate the changes in bone mineral density observed after surgery in the Gruen zones. A controlled, prospective study was carried out, in which a group of 37 patients with primary coxarthrosis were densitrometrically analyzed over the 1 year period following the implant of an ANATO stem (Stryker). The patient's healthy hip was taken as the control. Any differences in the remodeling pattern were compared according to age, body mass index, and implant size. Decreases in bone mineral density were observed after 3 months in all of the zones studied. However, this bone mineral density loss was recovered in all zones by the end of the study, except in zone 7 where a decrease of 7.2% in bone mass was observed. In zones 2 and 6, where more loads are transmitted, bone mass preservation, in accordance with Wolff's law, can be seen. No differences were found in the remodeling pattern in relation to age and body mass index. There were also no differences related to stem size except in zones 1 and 7. The ANATO stem achieves an efficient transmission of loads between the stem and the proximal femur, providing enough mechanical loads for bone preservation. It is only in zone 7 where significant bone atrophy can be observed, attributable to the damage that this area suffers during the surgical process and the subsequent stress-shielding caused by the implant design.

giant cell is a tumor that appears in young adults, requirirng surgical treatment due to its metastatic capacity, but recurrence rates makes no consensus about theraperutic management.23 patients were operated between 1996-2012 at Miguel Servet hospital, performing a mean of 8.9 years follow-up.Functional result was satisfactory in all cases, being able to perform normal phisical activity. Six recurrences were detected, which required surgical treatment, showing complete recovery at the end of the follow-up. One patient died by pulmonary metastasis.Surgery is the most appropriate treatment in giant cell tumors, having shown good results both in treatment of primary tumor and recurrences.