RESUMEN
Introduction: Total hip arthroplasty (THA) requires forceful maneuvers that can cause the pelvis to shift from its original position. Various methods for stabilizing the pelvis in the lateral decubitus position exist, but there is limited data quantifying the relative stability of each hip positioner. We sought to quantify the pelvic movement that occurred in four commercially available hip positioners during surgeon induced motion of the hip. Methods: An infrared marker was attached to the ilium of a cadaver secured in the lateral decubitus position. Four commercially available hip positioners were used for positioning: Beanbag, Pegboard, Stulberg, and ExactFit. Rotation and translation was captured using an infrared marker and camera system while the hip was moved through six motions (Flexion, Extension, Internal Rotation, External Rotation, Push, and Pull). Results: The Beanbag had the greatest amount of rotation and translation of the pelvis, with maximum hip rotation of 41.5°. The Stulberg and Pegboard positioners showed intermediate stability, with a maximum rotation of 7.8° and 17.1°, respectively. The ExactFit hip positioner resulted in the least amount of motion of the pelvis, with a maximum rotation of the pelvis of up to 3.2°. Of the simulated motions performed, internal rotation and flexion of the hip led to the greatest changes in pelvic rotation and translation. Conclusion: The ExactFit positioner was associated with the smallest amount of pelvic motion during simulated motions of hip arthroplasty, followed by the Stulberg, Pegboard, and Beanbag positioners. Further studies are required to correlate this information with clinical outcomes following total hip arthroplasty.
RESUMEN
Recurrent dislocation secondary to posterior soft tissue deficiency is a challenging complication of total hip arthroplasty. We describe the use of an Achilles allograft sling to improve hip stability. Eight patients treated with the sling were followed an average of 5 years. Seven patients had no recurrent instability and good postoperative range of motion. One graft failed in a patient with a neuropathic hip. Cadaveric biomechanical testing was also performed to investigate the stiffness and torque to failure of the sling in 6 specimens. Allograft slings can be used to improve hip stability. The technique is relatively easy to perform and does not limit postoperative range of motion. The graft decreases joint stiffness and has a greater torque to failure than the intact capsule.
Asunto(s)
Tendón Calcáneo/trasplante , Artroplastia de Reemplazo de Cadera , Luxación de la Cadera/prevención & control , Luxación de la Cadera/cirugía , Inestabilidad de la Articulación/prevención & control , Inestabilidad de la Articulación/cirugía , Complicaciones Posoperatorias , Adulto , Anciano , Anciano de 80 o más Años , Fenómenos Biomecánicos , Cadáver , Femenino , Estudios de Seguimiento , Luxación de la Cadera/epidemiología , Articulación de la Cadera/fisiología , Articulación de la Cadera/cirugía , Humanos , Inestabilidad de la Articulación/epidemiología , Masculino , Persona de Mediana Edad , Rango del Movimiento Articular/fisiología , Reoperación , Estudios Retrospectivos , Prevención Secundaria , Trasplante Homólogo , Resultado del TratamientoRESUMEN
Femur fractures occur during broaching and impaction of the implant during hip arthroplasty. Prophylactic cerclage of the proximal femur with braided cable and steel wire has been shown to decrease hoop stresses and has been posited as a way to decrease the incidence of intraoperative fracture. In this biomechanical study, the authors investigated the strain across the proximal femur during broaching after the application of stainless steel wire, comparing it with that for braided polyblend suture. Nine femur models were prepared, and strain gauges were applied to each of 3 groups. The control group received no cerclage, the second group received a double loop of suture, and the third group received a single loop of steel wire. A broach was firmly seated in each femur and sequentially increasing axial loads were applied at 1000 N, 2000 N, 3000 N, 4000 N, 5000 N, and 6000 N and to failure. Strain at all loads was lower in both cerclage groups than in the control group. Strain was 28.6%±12.4% lower in the suture group than in the control group (P=.0003). Strain was 30.8%±10.7% lower in the steel wire group than in the control group (P=.0011). There was no statistically significant difference between suture cerclage and steel wire cerclage (P=.7367). When used for prophylactic cerclage of the proximal femur, braided polyblend suture increases hoop stress resistance, decreases strain, and may play a clinically useful role in decreasing intraoperative proximal femur fractures during hip arthroplasty. [Orthopedics. 2016; 39(6):e1183-e1187.].