Primary rotational stability of cylindrical and conical revision hip stems as a function of femoral bone defects: An in vitro comparison

Jakubowitz, Eike; Bitsch, Rudi G.; Heisel, Christian; Lee, Christoph I.; Kretzer, Jan Philippe; Thomsen, M.

doi:10.1016/j.jbiomech.2008.06.002

Cited by 33 publications

(43 citation statements)

References 24 publications

(35 reference statements)

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“…Measurements of initial rotational stability of cemented femoral resurfacing components were carried out using an previously described torque apparatus. 12,13 …”

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confidence: 99%

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

Bitsch

Jäger

Lürssen

et al. 2010

Journal Orthopaedic Research

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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...

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“…Measurements of initial rotational stability of cemented femoral resurfacing components were carried out using an previously described torque apparatus. 12,13 …”

mentioning

confidence: 99%

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

Bitsch

Jäger

Lürssen

et al. 2010

Journal Orthopaedic Research

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“…To allow for standardized implantations in the light of an enhanced comparability to previous investigations [19,20], we decided to use second generation composite femora (#3106, Pacific Research Laboratories, Inc., Vashon, USA). Both strut grafts applied were taken out of a femur which was not to be further used and therefore had standardized dimensions of 16×155 mm and 16×175 mm for all measurements.…”

Section: Experimental Study Protocolmentioning

confidence: 99%

“…The cylindrical shaped S-ROM® stem (DePuy Orthopaedics Inc., Warsaw, USA) with a porous coated proximal sleeve ( Fig. 1) represented a more metaphyseal load transfer [19]. It was intentionally included to compromise its primary stability due to its mainly proximal fixation being directly surrounded by the femoral defect defined later.…”

Section: Experimental Study Protocolmentioning

confidence: 99%

“…templated stem sizes, performed a standardized neck resection [19] and identically prepared the femoral cavity with implant specific instruments. We followed an established protocol [19,20] to achieve a standardized alignment and pressfit fixation for stems comparable to hip surgery [21] and to loads occurring during walking [22]. Therefore, the stems were loaded with 25 cycles of 2 kN and 4 kN using a materials testing machine (Type 81816/B, Karl Frank GmbH, Weinheim, Germany).…”

Section: Experimental Study Protocolmentioning

confidence: 99%

“…The aim of this study was to analyse the influence of strut grafts on the primary stability of revision stems in femora with proximal defects. Two commonly used revision stems [5,[15][16][17][18] with different fixation philosophies [19] were included to assess this influence for different load transfers from stem to femur.…”

Section: Introductionmentioning

confidence: 99%

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Strut grafts in revision hip arthroplasty faced with femoral bone defects: an experimental analysis

Kinkel

Thomsen

Nadorf

et al. 2014

International Orthopaedics (SICOT)

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Purpose In total hip arthroplasty fixation of revision stems can be demanding due to femoral bone loss. Strut grafts are often used for bone augmentation and stabilization of the newly inserted prosthesis. The aim of this study was to assess the effect of strut grafts on primary stability under various stem fixation conditions. Methods Two different revision stems (cylindrical and conical shape) were implanted into synthetic femora. Following a semicircular transfemoral osteotomy, three deficient femoral bearings were simulated (bony lid reattached with cable wires; weakened lid reattached with cable wires; strut grafts placed to the weakened lid with cable wires). Relative micromovements were measured between prostheses and bones due to an axial moment applied to the stems. Results Relative movements correlated to the stem shape. The cylindrical stem showed higher movements increasing significantly with a weakened bony lid and portrayed a slight decrease of movements with strut graft application. No unequivocal influence of the weakened lid could be detected for the conical implant. Strut graft application did not show an additional stabilizing effect. Conclusions The primary stability of the cylindrical fixation concept decreases with impaired fixation conditions of the femur. A clear restabilizing effect with strut grafts could not be proven. A decrease of primary stability due to the impaired bone could not be observed for the conical stem shape. Additionally, strut grafts do not enhance fixation for this stem shape. We conclude that surgeons should not rely on a stabilizing effect of strut grafts in revision hip surgery.

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Humeral cementless surface replacement arthroplasties of the shoulder: An experimental investigation on their initial fixation

Jakubowitz

Neubrech

Raiss

et al. 2011

Journal Orthopaedic Research

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Cementless surface replacement arthroplasties are increasingly being used to treat arthritic humeral heads. These implants are designed to provide narrow bone resection, making a later revision easier. However, no clear evidence exists as to whether their initial fixation is sufficient for bony ingrowth. The aim of our in vitro study was to characterize the relative micromotion of two resurfacing implants with essentially different bone-facing geometries. Both systems were implanted into 10 human humeral specimens and micromotion was measured under a cyclic torque application of up to AE1.75 Nm. The mean relative rotary motion resulted in a significant difference (p ¼ 0.036), which was attributed to design differences of central stabilizers featuring both implants. A conversion of rotary motions into relative micromotions, using recently measured moments acting on these implants during daily activities of living, nullified this difference (p ¼ 0.088). However, depending on the shoulder load case considered, a clear difference appeared (p ¼ 0.031-0.045). In conclusion, both resurfacing implants are capable of achieving sufficient initial fixation on the humeral head and perform relative micromotions in a range considered safe for bony ingrowth. Patient-related parameters do not appear to influence the initial fixation of these implants. Keywords: arthroplasty; shoulder; cementless resurfacing; initial fixation; osseointegrationIn the 1950s, Neer 1 established modern shoulder arthroplasty and revolutionized its design with his perception of ''as near as possible to the anatomy.'' Since then designs have undergone many developments, as use of shoulder replacements has increased over the past 40 years. 2 The latest development is towards cementless surface replacement arthroplasties (CSRAs). Their positioning is independent of the humeral cavity and therefore easy to handle in the treatment of patients who have extra-articular deformities that make the placement of a conventional stemmed prosthesis difficult or impossible. 3,4 The design of CSRAs provides a primary press-fit, and in the majority of cases HA coatings should allow for accelerated biological fixation. 5 The benefit is minimal bone loss that facilitates later revision with a conventional total shoulder arthroplasty. 6,7 However, as promising as the implantation of a CSRA seems to be, a recent clinical study showed a high revision rate, 22% after 13 mos due to pain that may be caused by overstuffing of the joint, not resurfacing the glenoid, or loosening of the humeral component. 8 The complication rates in previous studies seem comparable and vary between 3% and 20%. 5,9-11 A further challenge is recognizing aseptic loosening in standard radiographs, since the bony bearing is always occulted by the metal concavity.As we have learned from total hip arthroplasty, initial fixation is the prerequisite for a good long-term success of cementless implants. This largely depends on how tightly the implant is fixed to the bone. 12 Relative micromotions ...

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Primary rotational stability of cylindrical and conical revision hip stems as a function of femoral bone defects: An in vitro comparison

Cited by 33 publications

References 24 publications

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

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

Strut grafts in revision hip arthroplasty faced with femoral bone defects: an experimental analysis

Humeral cementless surface replacement arthroplasties of the shoulder: An experimental investigation on their initial fixation

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