Juan J. Panisello

Long-Term Remodeling in Proximal Femur Around a Hydroxyapatite-Coated Anatomic Stem: Ten Years Densitometric Follow-Up

Bone remodeling after a hip arthroplasty has been quantified with dual energy x-ray absorptiometry, usually for short-term follow-up. We used this technique to determine the long-term remodeling produced by a hydroxyapatite-coated, anatomic stem. Eighty patients with unilateral hip osteoarthritis were included in the study. The contralateral, healthy hip was taken as control. Bilateral dual energy x-ray absorptiometry scans were done before the surgery, at 15 days, and 1 and 10 years postoperatively. There was a decrease of bone mineral density in zones 1 and 7, which ranged from 12.2% to 27.3% at the end of the first year. There were no changes in zones 1 to 6 from the 1st to the 10th year, but there was a late decrease, up to 42.9%, in zone 7. The changes of bone mineral density promoted by this stem occurred in the first postoperative year. Late loss was seen only in area 7.

Study of bone remodeling of two models of femoral cementless stems by means of DEXA and finite elements

BackgroundA hip replacement with a cemented or cementless femoral stem produces an effect on the bone called adaptive remodelling, attributable to mechanical and biological factors. All of the cementless prostheses designs try to achieve an optimal load transfer in order to avoid stress-shielding, which produces an osteopenia.Long-term densitometric studies taken after implanting ABG-I and ABG-II stems confirm that the changes made to the design and alloy of the ABG-II stem help produce less proximal atrophy of the femur. The simulation with FE allowed us to study the biomechanical behaviour of two stems. The aim of this study was, if possible, to correlate the biological and mechanical findings.MethodsBoth models with prostheses ABG-I and II have been simulated in five different moments of time which coincide with the DEXA measurements: postoperative, 6 months, 1, 3 and 5 years, in addition to the healthy femur as the initial reference. For the complete comparative analysis of both stems, all of the possible combinations of bone mass (group I and group II of pacients in two controlled studies for ABG-I and II stems, respectively), prosthetic geometry (ABG-I and ABG-II) and stem material (Wrought Titanium or TMZF) were simulated.Results and DiscussionIn both groups of bone mass an increase of stress in the area of the cancellous bone is produced, which coincides with the end of the HA coating, as a consequence of the bottleneck effect which is produced in the transmission of loads, and corresponds to Gruen zones 2 and 6, where no osteopenia can be seen in contrast to zones 1 and 7.ConclusionsIn this study it is shown that the ABG-II stem is more effective than the ABG-I given that it generates higher tensional values on the bone, due to which proximal bone atrophy diminishes. This biomechanical behaviour with an improved transmission of loads confirmed by means of FE simulation corresponds to the biological findings obtained with Dual-Energy X-Ray Absorptiometry (DEXA).

Changes in periprosthetic bone remodelling after redesigning an anatomic cementless stem

The aim of this prospective cohort study was to determine the densitometric relevance of minor design modifications of a cementless stem designed to improve proximal load transfer. We used a prospective cohort study with densitometric analysis over a five-year period of two groups of patients with primary osteoarthritis. The first group, 56 hips, received the first version of the ABG stem (ABG-I); the second group, 54 hips, had the ABG-II stem. The results obtained with the ABG-I stem showed a decrease of bone density in proximal areas that ranged from 13% to 37%. However, the new design had a decrease of the same areas that ranged from 9% to 23%. These differences were noted at the end of the first post-operative year and remained stable, except in zone 7, where they were progressive. There is little evidence that the modified stem reduces femoral bone density loss.RésuméNous avons revu de façon rétrospective 68 hanches chez 62 patients présentant une dysplasie acétabulaire et ayant bénéficié d’une ostéotomie péri-acétabulaire. Parmi ces 68 hanches, 33 avaient en préopératoire une rétroversion acétabulaire (groupe rétroversion) et 35 une antéversion (groupe contrôle). Toutes les hanches ont été évaluées selon le score de Harris. L’évaluation radiographique de la rétroversion acétabulaire et du mur postérieur déficient ont été basées sur le signe du croisement et le signe du mur extérieur. Les scores cliniques des deux groupes au suivi final était semblable. Dans le groupe rétroversion, 12 hanches avaient antéversé leur acétabulum en post-opératoire le signe du mur postérieur disparaissant, mais celui-ci restant présent dans 21 hanches avec un acétabulum en rétroversion post-opératoire. Parmi les 21 hanches avec acétabulum rétroversé une coxarthrose postérieure s’est développée à 5 ans post-opératoire. Lorsque l’on réalise une correction par ostéotomie pour une hanche dysplasique avec un acétabulum rétroversé, il est important de corriger cette rétroversion de façon à prévenir une coxarthrose secondaire due à la déficience du mur postérieur.

The Floating Metatarsal: First Metatarsophalangeal Joint Dislocation With Associated Lisfranc Dislocation

The authors report a case of an irreducible dorsal dislocation of the first metatarsophalangeal joint, with concomitant Lisfranc dislocation and fractures of the second, third, and fourth metatarsals. This combination has been reported only once in the literature. This extremely rare combined injury results in a floating metatarsal. Open reduction of the metatarsophalangeal joint dislocation and fixation of Lisfranc joint and metatarsal fractures with Kirschner wires was performed. One year after surgery, the patient is active and the first metatarsophalangeal joint is asymptomatic, but there is mild pain in the Lisfranc joint.

Long-Term Outcomes of a New Model of Anatomical Hydroxyapatite-Coated Hip Prosthesis

This prospective study was designed to evaluate 196 Anatomique Benoist Giraud (ABG II) total hip arthroplasties which were implanted between September 1999 and December 2000. A minimum 11 years follow up was completed in 183 cases. The bearing surfaces were polyethylene-zirconia in 84 cases, polyethylene-metal in 42 and ceramic-ceramic in 57. Changes in the femoral stem design, in relation to the previous ABG I model, have led to a significant improvement in stress-shielding. Polyethylene wear rate was lower by more than 50% compared with non-crosslinked polyethylene. Excellent and good results were obtained in 90.32% of cases, and implant survival was 98.39% at the end of follow-up.

Extensive osteolysis caused by polyethylene particle migration in an anatomical hydroxyapatite-coated hip prosthesis: 10 years' follow-up.

We report our 10-year follow-up results of 630 consecutive Anatomique Benoist Giraud I hip prostheses implanted between June 1990 and December 1995. At this time, 520 were satisfactory and 25 had been revised. Although the majority of patients remained asymptomatic at the end of follow-up, the real survivorship of the implant was less than 91% (33 patients who were in the waiting list for revision due to osteolysis at that time were revised by December 2007). On the other hand, radiographic outcomes were of concern: around 90% of patients showed progressive stress shielding and large granulomatous lesions in the proximal femur, and more than 82% of patients exhibited polyethylene wear in excess of 1 mm (mean=1.69 mm).

Changes in the morphology of hip fractures within a 10-year period

Abstract. The objective of this study was to find out whether the morphology of various types of hip fractures and the mean ages of the patients had changed in a recent 10-year period. All patients aged 65 years or more with acute hip fracture admitted to Miguel Servet University Hospital in 1989–1990 (n = 457) and in 1999–2000 (n = 518) were studied. The results showed a significant increase in the incidence of displaced cervical fractures (P < 0.001) and a decrease in the incidence of nondisplaced cervical fractures (P < 0.001) in women. The incidence of different types of trochanteric fractures did not vary. No change was observed in the mean age of patients with cervical fractures, but the mean age of women with A12 trochanteric fractures was significantly higher in 1999–2000 than in 1989–1990 (P < 0.05).

Cambios en el remodelado óseo periprotésico tras el rediseño del vástago ABG: estudio densitométrico

Objetivo Determinar la variacion de masa osea en dos versiones del mismo modelo de vastago femoral no cementado con objeto de cuantificar las diferencias atribuibles a un rediseno del implante con anclaje eminentemente metafisario. Material y metodo Estudio prospectivo, controlado, en el que se analizan densitometricamente, durante un ano, dos grupos de 36 pacientes afectos de coxartrosis primaria, con caracteristicas biologicas semejantes, distribuidos segun el equipo quirurgico que llevo a cabo la intervencion. Cada equipo utilizo uno de los implantes. Resultados Las modificaciones introducidas en el vastago ABG-II consiguieron un patron de remodelado oseo con mayor conservacion del capital oseo en todas las zonas estudiadas. Las cifras de perdida osea son semejantes a las obtenidas con implantes hechos a medida. Conclusiones El vastago ABG-II, de anclaje estrictamente metafisario, consigue un adecuado anclaje capaz de transmitir cargas al femur proximal y minimizar la perdida osea por puenteo de fuerzas (stress shielding).

Densitometric and finite-element analysis of bone remodeling further to implantation of an uncemented anatomical femoral stem

Abstract Introduction Implantation of a femoral stem changes the load transmission dynamics in the hip and gives rise to the so-called adaptive remodeling. The goal pursued by all stems, whether cemented or not, is to achieve a perfect load transmission mechanism in order to avoid the phenomenon of stress-shielding, which may cause proximal bone devitalization. Materials and methods In order to quantify bone mass variations in the 7 Gruen zones, a serial DEXA analysis was carried out in 80 patients, with preoperative measurements as well as postoperative measurements at 6 months and 1, 3, 5, 7 and 10 years post implantation. Results and conclusions Finite-element (FE) simulations make it possible to characterize the biomechanical changes that occur in the femur further to implantation of a prosthetic stem, as well as the stems long-term performance. The purpose of our study is to determine whether the results of the simulation can explain the biomechanical changes that may lie behind the evolution of bone density observed through DEXA scanning after implantation of an uncemented anatomical stem. The results of the FE simulation show an excellent match between the bone loss observed on DEXA scans and the evolution of stress patterns observed in each of the Gruen zones, which confirms that even if the stem implanted was metaphyseal, stress shielding was manifest in the proximal femoral area, giving rise to the devitalization of bone in Gruen zones 1 and 7.

Estudio densitométrico y con elementos finitos de la remodelación ósea tras la implantación de un vástago femoral anatómico no cementado

Introduccion La implantacion de un vastago femoral cambia las condiciones de transmision de carga de la cadera, produciendo el denominado remodelamiento adaptativo. El objetivo de todos los vastagos (cementados y no cementados) ha sido conseguir una perfecta transmision de cargas que evite los fenomenos de puenteo de fuerzas o stressshielding, que a su vez producen una desvitalizacion osea proximal. Material y metodo Para cuantificar las variaciones de la masa osea en las 7 zonas de Gruen se ha realizado un estudio seriado a 10 anos con DEXA en 80 pacientes, con mediciones en el pre y posoperatorio, 6 meses posperatorio, y a 1, 3, 5, 7 y 10 anos tras la implantacion de la protesis. Resultados y Conclusiones La simulacion con elementos finitos (EF) permite caracterizar los cambios biomecanicos que se producen en el femur tras la implantacion de un vastago protesico, asi como su comportamiento a largo plazo. El objetivo de nuestro estudio es comprobar si los resultados de la simulacion explican los cambios biomecanicos que justifiquen la evolucion de la densidad osea obtenida mediante el estudio con DEXA, tras la implantacion de un vastago anatomico no cementado. Los resultados de la simulacion con EF presentan un perfecto paralelismo entre las perdidas de masa osea detectadas con la DEXA y la evolucion tensional en cada zona de Gruen, lo que confirma que aunque el diseno de la protesis es de apoyo metafisario, se produce un claro fenomeno de puenteo de fuerzas en la zona proximal del femur, todo lo cual produce una desvitalizacion osea en las zonas 1 y 7 de Gruen.