Influence of bone density on the cement fixation of femoral hip resurfacing components

Abstract

ABSTRACT:In clinical outcome studies, small component sizes, female gender, femoral shape, focal bone defects, bad bone quality, and biomechanics have been associated with failures of resurfacing arthroplasties. We used a well-established experimental setup and human bone specimens to analyze the effects of bone density on cement fixation of femoral hip resurfacing components. Thirty-one fresh frozen femora were prepared for resurfacing using the original instruments. ASR TM resurfacing prostheses were implanted after dual-energy X-ray densitometer scans. Real-time measurements of pressure and temperature during implantation, analyses of cement penetration, and measurements of micro motions under torque application were performed. The associations of bone density and measurement data were examined calculating regression lines and multiple correlation coefficients; acceptability was tested with ANOVA. We found significant relations between bone density and micro motion, cement penetration, cement mantle thickness, cement pressure, and interface temperature. Mean bone density of the femora was 0.82 AE 0.13 g/cm 2 , t-score was À0.7 AE 1.0, and mean micro motion between bone and femoral resurfacing component was 17.5 AE 9.1 mm/Nm. The regression line between bone density and micro motion was equal to À56.7 Â bone density þ 63.8, R ¼ 0.815 (p < 0.001). Bone density scans are most helpful for patient selection in hip resurfacing, and a better bone quality leads to higher initial component stability. A sophisticated cementing technique is recommended to avoid vigorous impaction and incomplete seating, since increasing bone density also results in higher cement pressures, lower cement penetration, lower interface temperatures, and thicker cement mantles. Clinical studies of hip resurfacing arthroplasties identified risk factors for failure, including presence of femoral head cysts, small fixation area, small component size, female sex, and varus positioning of the femoral component. [1][2][3][4] Initial fixation and stability is critical to minimize membrane formation and prevent micro motions of more than 100-150 mm, which can lead to loosening. [5][6][7] The young patients that usually receive hip resurfacing arthroplasties need the best bone preparation and circumferential cement fixation. They should avoid impact activities to minimize the risk for loosening and femoral neck fractures. 8 Surgical technique modifications like increased numbers of femoral head drill holes and the area in which these holes are drilled or cementation of the metaphyseal stem (initially designed for component alignment purposes) were introduced to increase the area of bone-cement interface and enhance initial component stability. 9 Patient selection to avoid low bone density, focal defects, suboptimal shape, and poor hip biomechanics has been emphasized. 4 Our aim was to assess the usefulness of dual-energy X-ray densitometer (DEXA) bone density data for patient selection and prognosis of a sufficient initial stability. We used a well-es...

Cementation and interface analysis of early failure cases after hip-resurfacing arthroplasty

“…Reasons for high penetration depths include the use of jet lavage, especially at a high pressure in osteopenic bone, which itself is another influencing parameter [31]. Cement viscosity has also been regarded as a very important factor [32,33].…”

The influence of cementing technique in hip resurfacing arthroplasty on the initial stability of the femoral component

“…The axial rotational micro movements between the femoral components and the femoral neck were studied using an earlier described torque apparatus [3,15]. This torque apparatus used two counterbalanced weights to produce axial torques (Fig.…”

“…There have been several investigations into the utilization of cement for hip resurfacing [1][2][3][4][5][6][7][8]. A number of factors can affect the cement-bone interface, including lavage, haemostasis, bone density, cement mixing, cement viscosity, timing, temperature, cementing technique and component design.…”

“…The cement applicator was compared with a conventional cementing technique using an earlier described laboratory cementing model to analyse the associated variables [3]. Real-time measurements of pressure and temperature during implantation, and analyses of cement penetration and distribution were performed.…”

Fünf- bis Zehn-Jahresergebnisse für den Oberflächenersatz des Hüftgelenks

“…Es wird behauptet, dass speziell bei Patienten mit hohem Bewegungsanspruch dem kopferhaltenden Oberflächenersatz der Hüfte eine besondere Bedeutung zukommt. Postulierte Vorteile sind geringe Luxationsraten aufgrund großer Implantatköpfe, verbesserte Beweglichkeit, ein geringer Abrieb sowie einfachere Revisionsoperationen [5,13,14,18,29,32,39,44]. Der Vorteil einer knochensparenden Implantation wird auch unter dem Gesichtspunkt einer steigenden Lebenserwartung und dem damit höheren Risiko für Revisionsoperationen betont [28].…”