Guidelines for standardization of radiostereometry (RSA) of implants

Valstar, Edward R.; Gill, H. S.; Ryd, Leif; Flivik, Gunnar; Börlin, Niclas; Kärrholm, Johan

doi:10.1080/17453670510041574

Cited by 481 publications

(657 citation statements)

References 31 publications

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“…Digital calibrated stereo radiographs (Bucky Diagnostic; Philips, the Netherlands) were taken using one fixed and one mobile Roentgen source. We followed the published guidelines for radiostereometric analysis (Valstar et al 2005). Mean error of body fitting < 0.3 mm and condition number < 120 were set as cut-off limits to be included in the RSA analysis.…”

Section: Methodsmentioning

confidence: 99%

Lower periprosthetic bone loss and good fixation of an ultra-short stem compared to a conventional stem in uncemented total hip arthroplasty

Salemyr¹,

Muren²,

Ahl³

et al. 2015

Acta Orthopaedica

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Background and purpose — We hypothesized that an ultra-short stem would load the proximal femur in a more physiological way and could therefore reduce the adaptive periprosthetic bone loss known as stress shielding.Patients and methods — 51 patients with primary hip osteoarthritis were randomized to total hip arthroplasty (THA) with either an ultra-short stem or a conventional tapered stem. The primary endpoint was change in periprosthetic bone mineral density (BMD), measured with dual-energy x-ray absorptiometry (DXA), in Gruen zones 1 and 7, two years after surgery. Secondary endpoints were change in periprosthetic BMD in the entire periprosthetic region, i.e. Gruen zones 1 through 7, stem migration measured with radiostereometric analysis (RSA), and function measured with self-administered functional scores.Results — The periprosthetic decrease in BMD was statistically significantly lower with the ultra-short stem. In Gruen zone 1, the mean difference was 18% (95% CI: −27% to −10%). In zone 7, the difference was 5% (CI: −12% to −3%) and for Gruen zones 1–7 the difference was also 5% (CI: −9% to −2%). During the first 6 weeks postoperatively, the ultra-short stems migrated 0.77 mm more on average than the conventional stems. 3 months after surgery, no further migration was seen. The functional scores improved during the study and were similar in the 2 groups.Interpretation — Up to 2 years after total hip arthroplasty, compared to the conventional tapered stem the ultra-short uncemented anatomical stem induced lower periprosthetic bone loss and had equally excellent stem fixation and clinical outcome.

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Section: Methodsmentioning

confidence: 99%

Lower periprosthetic bone loss and good fixation of an ultra-short stem compared to a conventional stem in uncemented total hip arthroplasty

Salemyr¹,

Muren²,

Ahl³

et al. 2015

Acta Orthopaedica

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“…We accepted a maximum mean rigid body error of 0.35 mm and a maximum condition number (RSA rigid body elongation) of 130 for stem rotation [25]. For subsidence measurements, at least two stem markers with a constant distance between them throughout the followup period should be available, one at the tip of the stem and one at the proximal part of the stem including the femoral head center.…”

Section: Methodsmentioning

confidence: 99%

Early Subsidence Predicts Failure of a Cemented Femoral Stem With Minor Design Changes

Johanson

Antonsson

Shareghi

et al. 2016

Clinical Orthopaedics &Amp; Related Research

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Background Radiostereometry (RSA) measurements of early micromotion can predict later failure in hip and knee prostheses. In hip implants, RSA has been particularly helpful in the evaluation of composite-beam stem designs. The Spectron EF Primary stem (Smith & Nephew, London, UK) has shown inferior performance compared with its predecessors in both clinical studies and registry reports. Early RSA studies have shown somewhat greater subsidence for the Spectron EF Primary stem compared with the earlier Spectron EF, but still within boundaries considered to be safe.Questions/purposes Our primary research question was whether stem subsidence and rotation for this stem design measured with RSA at 2 years can predict later stem failure. A secondary question was whether high femoral stem offset and small stem sizes, both features specific to the Spectron EF Primary stem compared with its predecessors, are associated with stem failure rate. Methods Two hundred forty-seven hips (209 patients with median age 63 years [range, 29-80 years], 65% female, and 77% primary osteoarthritis) with a valid RSA examination at 2 years were selected from four different RSA studies (totaling 279 hips in 236 patients) in our department. The studies were primarily aimed at evaluating cup fixation, bone cement, and polyethylene types. All study patients received a cemented Spectron EF Primary stem. The selected hips had complete followup until stem failure, death, or the end of the followup period. Stem failure was defined as revision of a loose femoral stem or radiological failure with significant osteolysis in Gruen zones 2 to 6. Cox regression analyses were performed to evaluate if stem subsidence and rotation after 2 years, adjusted for age, sex, stem size, standard/high stem offset, and conventional/highly crosslinked polyethylene, could predict later clinical aseptic failure of the stem. We identified 32 stem failures (27 revisions, five radiological failures) at 14 years median followup (range, 3-18 years). Ten-year stem survival was 94% (95% confidence interval [CI], 90%-96%).Results Stem subsidence at 2 years (adjusted hazard ratio [HR], 6.0; 95% CI, 2.5-15; p \ 0.001) and retrotorsion of the stem (adjusted HR, 1.7; 95% CI, 1.1-2.5; p = 0.018) were associated with later stem failure. Further risk factors were male sex (subsidence analysis HR, 6.9; p [ 0.001), use of the two smallest stem sizes (HR size 1 , 8.0; p[0.001,

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“…The UmRSA system has been validated in a standardized manner and a phantom was examined to confirm the accuracy of our system. A standard protocol was used for the RSA investigation [30]. The stability of the tantalum markers in a rigid body will influence the accuracy of any measured movement.…”

Section: Methodsmentioning

confidence: 99%

“…This is the mean difference between the relative distances of markers in a rigid body in one examination compared with that in another examination. Valstar et al [30] proposed the upper limit for the mean error of rigid body fitting should be 0.35 mm, which is the figure we used.…”

Section: Methodsmentioning

confidence: 99%

“…Conversely, the lower the condition number, the better the distribution of the ball in the rigid body. Valstar et al suggested condition numbers less than 110 are reliable and sufficient for determination of prosthetic migration and recommended against using condition numbers in excess of 130 [30]. To ensure accuracy, we used 115 as the upper limit of acceptability.…”

Section: Methodsmentioning

confidence: 99%

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The Influence of a Suction Device on Fixation of a Cemented Cup using RSA

Timperley

Whitehouse

Hourigan

2009

Clinical Orthopaedics &Amp; Related Research

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The quality of technique used at the time of socket cementation is crucial in ensuring a durable longterm result of the implant. We asked whether a new instrument, an aspirator retractor introduced into the wing of the ilium before socket preparation and cementation, would enhance cement fixation as defined by RSA and radiographic examination. We randomized 38 patients into two groups. The surgical technique was identical between the groups with the exception of the use of the aspirator retractor. Patients were followed clinically and with radiostereometry at a minimum of 2 years. We compared gross radiographic appearances, including the depth of penetration of cement and the incidence of postoperative and 2-year radiolucent lines. There was no difference in proximal migration between the two groups. No improvement of fixation was proven from the measured translations and rotations of the socket in the suction group. We found no difference in the number or extent of radiolucent lines or the depth of cement penetration when the iliac suction device was used in conjunction with contemporary cementing techniques. Although the data suggest no shortterm advantage in this small study, we will continue to follow these patients presuming there will be improved outcomes in the longer term and since the device provides an easier method of obtaining adequate fixation, especially if technical difficulties are encountered during the pressurization procedure.

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Guidelines for standardization of radiostereometry (RSA) of implants

Cited by 481 publications

References 31 publications

Lower periprosthetic bone loss and good fixation of an ultra-short stem compared to a conventional stem in uncemented total hip arthroplasty

Lower periprosthetic bone loss and good fixation of an ultra-short stem compared to a conventional stem in uncemented total hip arthroplasty

Early Subsidence Predicts Failure of a Cemented Femoral Stem With Minor Design Changes

The Influence of a Suction Device on Fixation of a Cemented Cup using RSA

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