Slide track analysis of the relative motion between femoral head and acetabular cup in walking and in hip simulators

Saikko, Vesa; Calonius, Olof

doi:10.1016/s0021-9290(01)00224-x

Cited by 94 publications

(103 citation statements)

References 16 publications

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“…The 50% lower wear rate of the TKR inserts compared with the THR liners for regular wear (no delamination) may be a result of the lower degree of multidirectional motion in the knee [18,31]. This comparison entailed adjusting the wear rates to a patient age of 70 years to account for age dependence, and included only active patients.…”

Section: Discussionmentioning

confidence: 99%

How Does Wear Rate Compare in Well-functioning Total Hip and Knee Replacements? A Postmortem Polyethylene Liner Study

Pourzal

Knowlton

Hall

et al. 2016

Clinical Orthopaedics &Amp; Related Research

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Background The longevity of total hip (THR) and knee replacements (TKR) that used historical bearing materials of gamma-in-air sterilized UHMWPE was affected more by osteolysis in THRs than in TKRs, although osteolysis remains a concern in TKRs. Therefore, the study of polyethylene wear is still of interest for the knee, particularly because few studies have investigated volumetric material loss in tibial knee inserts. For this study, a unique collection of autopsy-retrieved TKR and THR components that were well-functioning at the time of retrieval was used to compare volumetric wear differences between hip and knee polyethylene components made from identical material. Questions/purposes The following questions were addressed: (1) How much did the hip liners wear and what wear patterns did they exhibit? (2) How much did the knee inserts wear and what wear patterns did they exhibit? (3) What is the ratio between TKR and THR wear after controlling for implantation time and patient age? Methods We compared 23 THR components (HarrisGalante [HG] and HG II) and 20 TKR components (MillerGalante [MG II]) that were retrieved postmortem. The components were made from the same polyethylene formulation and with similar manufacturing and sterilization (gamma-in-air) processes. Twenty-one patients (12 males, nine females) had THRs and 16 (four males, 12 females) had TKRs. Patients who had TKRs had an older (p = 0.001) average age than patients who had THRs (age, 75 years; SD, 10, versus 66 years; SD, 12, respectively). Only wellfunctioning components were included in this study. Therefore, implants retrieved postmortem from physically active patients and implanted for at least 2 years were considered. In addition, only normally wearing TKR components were considered, ie, those with fatigue wear (delamination) were excluded. The wear volume of each component was measured using metrology. For the tibial inserts an autonomous mathematic reconstruction method was used for quantification. Results The acetabular liners of the THR group had a wear rate of 38 mm 3 per year (95% CI, 29-47 mm 3 /year). Excluding patients with low-activity, the wear rate was 47 mm 3 per year (95% CI, 37-56 mm 3 /year). The wear rate of normally wearing tibial inserts was 17 mm 3 per year (95% CI, À6 to 40 mm 3 /year). After controlling for the relevant confounding variable of age, we found a TKR/THR wear rate ratio of 0.5 (95% CI, 0.29-0.77) at 70 years of age with a slightly increasing difference with increasing age. Conclusions Excluding delamination, TKRs exhibited lower articular wear rates than THRs for historical polyethylene in these two unique cohorts of postmortem retrievals.

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Section: Discussionmentioning

confidence: 99%

How Does Wear Rate Compare in Well-functioning Total Hip and Knee Replacements? A Postmortem Polyethylene Liner Study

Pourzal

Knowlton

Hall

et al. 2016

Clinical Orthopaedics &Amp; Related Research

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“…In actual prosthetic joints, not only the contact pressure but also the size and shape of the slide track varies considerably on the contact surfaces [Saikko and Calonius, 2002b]. It may not be possible to determine a characteristic wear factor for every type of slide track.…”

Section: Discussionmentioning

confidence: 99%

In vitro wear simulation on the RandomPOD wear testing system as a screening method for bearing materials intended for total knee arthroplasty

Saikko

2014

Journal of Biomechanics

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The 16-station RandomPOD wear test system, previously validated for prosthetic hip wear, was used in the simulation of knee wear mechanisms with a ball-on-flat test configuration.This consisted of a CoCr pin with a ground and polished spherical bearing surface (radius 28 mm) against a conventional, gamma-sterilized UHMWPE disk in serum lubrication. The biaxial motion, consisting of x and y translations, and the load were non-cyclic. Relative to the disk, the center of contact wandered within a circle of 10 mm diameter, and the average sliding velocity was 15.5 mm/s (range 0 to 31 mm/s). The load varied non-cyclically between 0 and 142 N (average 73 N). In the 60-day test with 16 similar wear couples, moderate adhesive wear, the principal wear mechanism of a well-functioning prosthetic knee, dominated. This showed as a burnished, circular wear mark (diameter 13.2 mm, area 137 mm 2 ). The wear factor was 2.04 ± 0.03 × 10 -6 mm 3 /Nm (mean ± 95 per cent confidence limit). For the first time a truly multidirectional, realistic and uniform, large capacity pin-ondisk simulation of knee wear mechanisms was implemented.

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“…15,21 Analysis of the wear paths produced by different simulators has shown a wide variation, ranging from simple linear paths with infinite aspect ratios to open circular paths with low aspect ratios. 22 The potential importance of variations in individual THA patient's wear paths on wear rates has recently been recognized, with altered gait cycle inputs used to predict wear rate in a finite element model.…”

Section: Discussionmentioning

confidence: 99%

“…Three-dimensional wear paths were determined for a sample of 20 points on the acetabulum and two-dimensional projected plots of the wear paths were produced. [14][15][16] The aspect ratios of the 2D wear paths was used to determine the degree of linear or multidirectional motion experienced at the hip. Larger aspect ratios indicated more longitudinal paths, while smaller ratios indicated more wide or open paths.…”

Section: Methodsmentioning

confidence: 99%

The influence of wear paths produced by hip replacement patients during normal walking on wear rates

Bennett¹,

Humphreys²,

O’Brien³

et al. 2008

Journal Orthopaedic Research

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Variation in wear paths is known to greatly affect wear rates in vitro, with multidirectional paths producing much greater wear than unidirectional paths. This study investigated the relationship between multidirectional motion at the hip joint, as measured by aspect ratio, sliding distance, and wear rate for 164 hip replacements. Kinematic input from three-dimensional gait analysis was used to determine the wear paths. Activity cycles were determined for a subgroup of 100 patients using a pedometer study, and the relationship between annual sliding distance and wear rate was analyzed. Poor correlations were found between both aspect ratio and sliding distance and wear rate for the larger group and between annual sliding distance and wear rate for the subgroup. However, patients who experienced a wear rate <0.08 mm/year showed a strong positive correlation between the combination of sliding distance, activity levels, and aspect ratio and wear rate (adjusted r 2 ¼ 55.4%). This group may represent those patients who experience conditions that most closely match those that prevail in simulator and laboratory tests. Although the shape of wear paths, their sliding distance, and the number of articulation cycles at the hip joint affect wear rates in simulator studies, this relationship was not seen in this clinical study. Other factors such as lubrication, loading conditions and roughness of the femoral head may influence the wear rate. ß

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Slide track analysis of the relative motion between femoral head and acetabular cup in walking and in hip simulators

Cited by 94 publications

References 16 publications

How Does Wear Rate Compare in Well-functioning Total Hip and Knee Replacements? A Postmortem Polyethylene Liner Study

How Does Wear Rate Compare in Well-functioning Total Hip and Knee Replacements? A Postmortem Polyethylene Liner Study

In vitro wear simulation on the RandomPOD wear testing system as a screening method for bearing materials intended for total knee arthroplasty

The influence of wear paths produced by hip replacement patients during normal walking on wear rates

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