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Biomedical subjects

D Palanca

Publications and source records attributed to D Palanca.

11 recordsLinked to original sources
PubMed2006

Influence of the tunnel angle in ACL reconstructions on the biomechanics of the knee joint.

BACKGROUND: A high tension in anterior cruciate ligament grafts affects both graft and knee functional performance. Clinical observations suggest that impingement of the graft against the posterior cruciate ligament might cause high graft tensions. Also, meniscal injury has been well documented in association with damage in the anterior cruciate ligament. METHODS: In this paper, we present the results obtained in a three-dimensional finite element model of the human knee, corresponding to different aspects of anterior cruciate ligament reconstruction with bone-patellar tendon-bone grafts. This model was used to investigate the effect of the angle in the coronal plane of femoral and tibial tunnels. Firstly, graft tension was computed in a knee moved from 0 degrees to 60 degrees of flexion and the results were compared with experimental ones obtained by other authors. Secondly, the resulting kinematics under an anterior load of 134 N was compared to that of the intact knee. FINDINGS: The obtained results showed that the closest anterior tibial translation to that of the intact knee was obtained with femoral and tibial tunnels with angles of 60 degrees. In this same case, a lower graft tension was also obtained. The results demonstrated noticeable increases in the meniscal stresses after anterior cruciate ligament reconstruction. INTERPRETATION: Our results showed that impingement only depends on the femoral tunnel angle. On the contrary, laxity principally depends on the tibial tunnel angle. The angle of the femoral tunnel affects the graft tension while the tibial tunnel affects laxity, meniscal stresses and strains.

Anterior Cruciate Ligament↗
PubMed2005

A finite element simulation of the effect of graft stiffness and graft tensioning in ACL reconstruction.

BACKGROUND: The anterior cruciate is the most frequent knee ligament to be totally disrupted. Surgical reconstruction of the anterior cruciate ligament is a common practice to treat the disability or chronical instability of knees due to anterior cruciate ligament insufficiency. Some of the factors that influence the success or failure of the anterior cruciate ligament reconstruction are the integrity of secondary restraints, the preoperative laxity of the knee, the status of the articular and meniscal cartilages, the selection of the graft material, the surgical technique, the graft tension and the postoperative rehabilitation. METHODS: In this paper we present and discuss the results obtained with a three-dimensional finite element model of the human knee joint corresponding to different aspects of human anterior cruciate ligament reconstruction. In particular, this model was used to investigate the effect of graft stiffness and graft tensioning on the knee joint biomechanics. The initial graft tension was set to 0, 20, 40 or 60 N with the knee at 0 degrees , 30 degrees and 60 degrees of flexion. Three different stiffnesses corresponding to those of patellar tendon, gracilis and quadrupled semitendinosus grafts were analyzed. FINDINGS: The resulting kinematics in each of these cases under an anterior load of 134 N was compared to that of the intact knee. The obtained results showed that, after reconstruction, the closest anterior tibial translation to that of the intact knee is obtained with a bone-patellar tendon-bone graft with a pretension of 60 N. INTERPRETATION: However, this initial tension produces an important additional stress in the graft during the knee movement. This may cause problems in revascularization and remodelling during the postoperative healing process. A lower pretension of about 40 N should therefore be recommended in the present conditions.

Anterior Cruciate Ligament Injuries↗
PubMed2005

Finite element analysis of the effect of meniscal tears and meniscectomies on human knee biomechanics.

BACKGROUND: Many authors have suggested that the high levels of shear and tensile stresses that appear in the articular cartilage after meniscectomy are partly responsible for cartilage pathologies, such as osteoarthrosis. METHODS: In this paper, we investigate the effect of meniscal tears and meniscectomies on the human knee joint. Solid models of the tibia, femur, menisci and cartilage were generated from MRI images. A three-dimensional finite element model was developed that included the femur, tibia, cartilage layers, menisci and ligaments. The femur and tibia were considered to be rigid, the articular cartilage and menisci to be linearly elastic, isotropic and homogeneous and the ligaments were modelled as hyperelastic. Three different situations were compared: a healthy tibio-femoral joint, a tibio-femoral joint with tears in one meniscus and a tibio-femoral joint after meniscectomy. FINDINGS: The minimal principal stresses corresponding to a compressive load at 0 degrees flexion were obtained for the posterior zone of the medial meniscus and the corresponding region of the articular cartilage. Under an axial femoral compressive load, the maximal contact stress in the articular cartilage after meniscectomy was about twice that of a healthy joint. INTERPRETATION: This fact could partially explain the cartilage damage and degeneration that have been observed after meniscectomy.

Adult↗
PubMed2004

A comparative analysis of different treatments for distal femur fractures using the finite element method.

The main objective of this work is the evaluation, by means of the finite element method (FEM) of the mechanical stability and long-term microstructural modifications in bone induced to three different kinds of fractures of the distal femur by three types of implants: the Condyle Plate, the less invasive stabilization system plate (LISS) and the distal femur nail (DFN). The displacement and the stress distributions both in bone and implants and the internal bone remodelling process after fracture and fixation are obtained and analysed by computational simulation. The main conclusions of this work are that distal femoral fractures can be treated correctly with the Condyle Plate, the LISS plate and the DFN. The stresses both in LISS and DFN implant are high especially around the screws. When respect to remodelling, the LISS produces an important resorption in the fractured region, while the other two implants do not strongly modify bone tissue microstructure.

Aged↗
PubMed2000

Three-dimensional finite element analysis of several internal and external pelvis fixations.

The Finite Element Method (FEM) can be used to analyze very complex geometries, such as the pelvis, and complicated constitutive behaviors, such as the heterogeneous, nonlinear, and anisotropic behavior of bone tissue or the noncompression, nonbending character of ligaments. Here, FEM was used to simulate the mechanical ability of several external and internal fixations that stabilize pelvic ring disruptions. A customized pelvic fracture analysis was performed by computer simulation to determine the best fixation method for each individual treatment. The stability of open-book fractures with external fixations at either the iliac crests or the pelvic equator was similar, and increased greatly when they were used in combination. However, external fixations did not effectively stabilize rotationally and vertically unstable fractures. Adequate stabilization was only achieved using an internal pubis fixation with two sacroiliac screws.

Aged↗
PubMed1996

Complications and technical problems with the gamma nail.

A retrospective review of complications with the gamma nail has been carried out in 152 patients with stable and unstable pertrochanteric fractures. Operative complications occurred in 10 patients. Screws penetrated the femoral neck in 3, immediate varus was associated with a short screw in 2, diaphyseal fractures occurred at the site of the distal screws in 3 and comminuted femoral fractures in 2. Fifteen patients (10.5%) died in hospital. At follow up, pseudarthrosis was present in 2 cases and fractures of the femoral shaft in 4. The incidence of complications could be reduced by using of shorter nails, less valgus angulation and by not introducing distal screws unless essential.

Aged↗
PubMedDate not supplied

Results of the surgical treatment of Lisfranc fracture-dislocations.

The authors present a series of 25 patients with Lisfranc fracture-dislocation who were treated by reduction (open or closed) and stabilization with Kirschner wiring. Minimum follow-up was two years. The dislocations were divided based on the Quenu and Kuss classification system. Nonsurgical reduction was possible in 17 patients. Neither the type of dislocation nor the type of reduction influenced the results in progression in our series. Nonetheless, long-term functional results were better when the quality of the reduction was excellent.

Adolescent↗
PubMedDate not supplied

Late recurrence and endocranial metastasis caused by giant cell tumor.

A case of giant cell tumor localized in the proximal end of the right tibia, initially treated by simple curettage is described. After 11 years there was local recurrence, confirmed anatomopathologically, observed during wide resection and reconstruction by arthroplasty plus homoplastic grafting. After a few months there were metastatic lesions in the left parietooccipital and right retroorbitary area. Biopsy of the parietooccipital lesion showed giant cells in a sarcomatous stroma. The patient died after several attempts at chemotherapy. Even if only sporadic cases have been described of late recurrences and of extrapulmonary metastases for giant cell tumors, the case presented here is exceptionally rare. The factors that influence recurrence of these tumors and their ability to metastasize is discussed.

Adult↗
PubMedDate not supplied

Baker's pseudocyst in the prosthetic knee affected with aggressive granulomatosis caused by polyethylene wear.

It is our belief that this is the first histologically documented case of popliteal cyst secondary to early failure of a cementless knee prosthesis, that occurred after 4 years. The walls of the cyst presented with granulomatous reaction to polyethylene particles. In prosthetic reimplantation successive to excision of the cyst we observed a recurrence of cysts and osteointegration of the prosthetic components, that made reimplantation difficult. Histological assessment of the synovial tissue, periprosthetic tissue and underlying bone showed granulomatous reaction to polyethylene debris. A "tumor" in a patient that has a knee prosthesis can be caused by implant failure. In cases of early failure wear forms large particles and their migration at the bone-prosthesis interface may be obstructed and thus cause a different biological response. If reimplantation is necessary osteointegration of the implants may make surgery difficult.

Female↗
PubMedDate not supplied

The treatment of giant cell tumors by curettage and filling with acrylic cement. Long-term functional results.

Curettage and filling with acrylic cement in the treatment of para-articular giant cell tumor (GCT) has multiple advantages as compared to other methods; nonetheless, the possibility of progression in arthrosis is still a drawback. The literature does not report long-term functional results when this method was used. Four cases are presented with a mean long-term follow-up of 13.5 years (minimum 11, maximum 18). Clinical results, evaluated by the Enneking system (18), were excellent, and there were no radiological modifications, so that we believe that this is the method to choose for Campanacci stage I and II GCT (1), and in some stage III cases, as joint function is not compromised in time.

Acrylates↗