Torsional loads in the early postoperative period following total hip replacement

Abstract

Torques generated in one subject during the early postoperative period were measured with a telemeterized total hip component. The patient was examined during gait, stair ascent, rising from a chair, and single-limb stance. The torques were plotted against both the resultant joint contact force and the force component directed along the stem axis. During gait, the maximum torque was 35 Nm, recorded at a walking velocity of 1.7 m/sec. The peak torques during stair ascent and during rising from a seated position were found to be 23 and 15 Nm, respectively. The maximum value for torque measured in this study was 37 Nm during one attempt at single-limb stance. Comparison of plots for torque versus stem-axis component for the four activities shows that the torque increased more rapidly for chair exits than for gait up to resultant contact force values of as much as 1,000 N. For stair ascent, the same was true to values of 1,400 N. Within any given activity, the relationship between stem torque and resultant or stem-axis force showed considerable variability. These results indicate that experiments evaluating the stability of femoral components in total hip arthroplasty should incorporate a component directed along the stem axis, as well as a component normal to the plane of the prosthesis. The results also suggest that theoretical stress analysis models should consider the broad variability in the orientation of the joint force at the hip.

The John Charnley Award: The Functional Outcome of Hip Resurfacing and Large-head THA Is the Same

“…The timed up and go test is the only functional test in which the control group surpassed the prostheses groups at all followups. One explanation could be the extremely high axial and rotational loads on the hip generated by the action of standing from a sitting position [8,26,27].…”

“…The operated patients may have had more difficulties in rising quickly from the chair, making the 180°turn at fast speed, or sitting on the chair. Extremely high axial and rotational loads on the hip are generated by this action [8,26,27].…”

An implantable telemetry device to measure intra-articular tibial forces

“…However, there are obvious disadvantages to such a system. Subsequently, in vivo forces have been successfully measured in orthopedics in the hip using telemetry links (Graichen et al, 1999;Bergmann et al, 1988Bergmann et al, , 1993Bassey et al, 1997;Kotzar et al, 1991Kotzar et al, , 1995Brand et al, 1994;Graichen and Bergmann, 1991;Davy et al, 1988;Hodge et al, 1989), spine (Calisse et al, 1999;Wilke et al, 1999;Rohlmann et al, 1995) and femur (Lu et al, 1998). Lu et al, 1997) The first report of a telemetered hip prosthesis came from English and Kilvington, who reported hip forces of 2.7 times the body weight during the stance phase of level walking without support (English and Kilvington, 1979).…”

“…Tibial prostheses have been instrumented with force transducers to measure tibial forces in vitro (Kaufman et al, 1996); however, direct measurement of tibial forces in vivo has not been reported. Telemetry has been shown to be a safe and accurate means of obtaining force data from implanted transducers and has been used to measure in vivo forces in the hip, spine, and femur (Graichen et al, 1999;Bergmann et al, 1988Bergmann et al, , 1993Bassey et al, 1997;Kotzar et al, 1991Kotzar et al, , 1995Brand et al, 1994;Graichen and Bergmann, 1991;Davy et al, 1988;Hodge et al, 1989;Calisse et al, 1999;Wilke et al, 1999;Rohlmann et al, 1995;Lu et al, 1997Lu et al, , 1998Taylor et al, 1997Taylor et al, , 1998. Hip forces measured through telemetry have typically been lower than those predicted mathematically.…”

Nested Metamaterials for Wireless Strain Sensing

“…However, to date, many of the technologies that seek to exploit this bone-implant loadsharing phenomena have been considered too large in dimension or involve implantation of an associated power supply. Previous investigations have been successful in determining forces in the hip [7]- [9], spine [10]- [12], and femur [13], [14]. However, due to the relatively large size of the sensors and associated hardware (signal conditioning, modulation, etc.…”