RESUMEN
Some patients have been less than satisfied with flexion after total knee arthroplasty (TKA). As early designs provided limited flexion, companies have developed high-flexion designs. We conducted a study to compare flexion between 2 standard and 3 high-flexion designs and to compare clinical and radiographic postoperative flexion. Clinical and radiographic measurements were obtained by 3 independent orthopedists. Clinical flexion, with the patient maximally bending his or her knee as far as possible, was measured with a goniometer, recorded, and compared with measurements from lateral radiographs of the knee in the same position. A total of 144 knees (108 patients) were included in the study. Mean preoperative flexion was 110° for both groups, and mean postoperative flexion was 111° clinically and 109° radiographically for the standard designs, and 114° clinically and 117° radiographically for the high-flexion designs (P<.05). The groups had similar preoperative and postoperative Knee Society knee and function scores. Measurements obtained by the 3 independent examiners were highly correlated. Compared with the standard designs, the highflexion designs demonstrated statistically significantly more flexion, though the clinical increase in flexion was relatively small (3º).
Asunto(s)
Artroplastia de Reemplazo de Rodilla/métodos , Articulación de la Rodilla/fisiopatología , Prótesis de la Rodilla , Osteoartritis de la Rodilla/fisiopatología , Diseño de Prótesis , Rango del Movimiento Articular/fisiología , Anciano , Femenino , Humanos , Articulación de la Rodilla/diagnóstico por imagen , Articulación de la Rodilla/cirugía , Masculino , Persona de Mediana Edad , Osteoartritis de la Rodilla/diagnóstico por imagen , Osteoartritis de la Rodilla/cirugía , Periodo Posoperatorio , Radiografía , Resultado del TratamientoRESUMEN
Postoperative flexion is an important factor in the outcome of total knee arthroplasty. Although normal activities of daily living require a minimum of 105° to 110° of flexion, patients from non-Western cultures often engage in activities such as kneeling and squatting that require higher flexion. The desire to achieve greater flexion serves as the driving force for prosthetic modifications, including high-flexion designs. Techniques used to measure knee flexion and knee position during measurement are not often described or are different depending on the examiner. The purpose of this study was to compare active (self) and passive (assisted) flexion after successful total knee arthroplasty for 5 prostheses (2 standard and 3 high-flexion) using clinical (goniometer) and radiographic (true lateral radiograph) measurement techniques by different independent examiners.At a mean follow-up of 2.7 years (range, 1-5.6 years), a total of 108 patients (144 total knee arthroplasties) had completed the study. Mean postoperative active flexion was 111° clinically and 109° radiographically for the standard designs and 114° clinically and 117° radiographically for the high-flexion designs. Adding passive flexion increased flexion to 115° clinically and 117° radiographically for the standard designs and 119° clinically and 124° radiographically for the high-flexion designs. Flexion differences between the 2 measurement techniques (active vs passive and clinically vs radiographically) were statistically significant (P<.05). These findings demonstrate the importance of describing how flexion is measured in studies and understanding how the method of measurement can affect the findings.
Asunto(s)
Artrografía/métodos , Artrometría Articular/métodos , Artroplastia de Reemplazo de Rodilla/métodos , Inestabilidad de la Articulación/diagnóstico , Inestabilidad de la Articulación/cirugía , Anciano , Femenino , Humanos , Inestabilidad de la Articulación/fisiopatología , Masculino , Rango del Movimiento Articular , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Resultado del TratamientoRESUMEN
Cementless femoral fixation by means of bone ingrowth has been successful in total hip arthroplasty in patients with sufficient bone quality. Consistent bone ingrowth and resultant long-term success involve many factors, including surgical technique, initial mechanical stability achieved at time of implantation, stem design and material, and implant surface. One potential method for achieving faster, more consistent initial bone ingrowth is use of the osteoconductive ceramic hydroxyapatite. In addition, more stable initial fixation most likely improves long-term outcome. In this article, we review the criteria for successful cementless femoral fixation and the long-term results reported in the literature.
Asunto(s)
Artroplastia de Reemplazo de Cadera/métodos , Fémur/cirugía , Fijación de Fractura/métodos , Artroplastia de Reemplazo de Cadera/instrumentación , Cementos para Huesos , Fijación de Fractura/instrumentación , Humanos , Diseño de PrótesisRESUMEN
The effects of damaged femoral heads on long-term wear in total hip arthroplasties are not well known. In the study reported here, we compared the surface roughness of dislocated femoral heads, retrieved at time of revision, with that of heads revised for reasons other than dislocation. The dislocated heads, including 6 cobalt-chrome (Co-Cr), 2 oxidized zirconium, and 2 alumina (ceramic) heads, were compared with nondislocated Co-Cr and ceramic heads. Scratch marks on the dislocated Co-Cr and alumina heads were considerably smaller and shallow than those on the dislocated oxidized zirconium heads. Mean surface roughness of the dislocated heads was 368 nm (Co-Cr), 376 nm (alumina), and 2137 nm (oxidized zirconium). On the contrary, the mean surface roughness for nondislocated Co-Cr and alumina heads was 307.44 nm (outlier excluded) and 138.8 nm, respectively. Our data suggest that increased surface damage and roughness can occur after dislocation.
Asunto(s)
Artroplastia de Reemplazo de Cadera , Cabeza Femoral , Prótesis de Cadera , Falla de Prótesis , Óxido de Aluminio , Artroplastia de Reemplazo de Cadera/efectos adversos , Aleaciones de Cromo , Humanos , Oxidación-Reducción , Reoperación , Propiedades de Superficie , CirconioRESUMEN
Wear debris from metal-on-polyethylene articulation in conventional total hip arthroplasty can limit the implant's longevity. Modern ceramic material with high wear resistance and low fracture risk has the potential to extend the lifetime of total hip arthroplasty, which makes the procedure potentially more suitable for young, active patients. Concerns with brittle ceramic material include fracture risk, the "squeak" phenomenon, and potentially a higher dislocation rate secondary to limited neck lengths and liner options. We therefore determined the early dislocation rate in modern ceramic-on-ceramic total hip arthroplasty. In 1635 total hip arthroplasties performed over the 9-year period (1996-2005), we observed three anterior and 15 posterior dislocations (1.1%). All were treated successfully, one with a revision and 17 with closed reduction under general anesthesia. Ceramic-on-ceramic total hip arthroplasty can be a good alternative bearing surface with a low dislocation rate.