Stem curvature and load angle influence the initial relative bone‐implant motion of cementless femoral stems

Berzins, Aivars; Sumner, Dale R.; Andriacchi, Thomas P.; Galante, Jorge O.

doi:10.1002/jor.1100110518

Cited by 55 publications

(37 citation statements)

References 22 publications

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“…If this applies to humans, the micromotions that occurred with our prosthesis seem to be within the critical level, regardless of immediate or late loading. The geometry and surface morphology of the implant are important factors in stability (Berzins et al 1993) and ingrowth (Overgaard et al 1999). An HA-coated implant seems to stimulate ingrowth more than an uncoated implant under loaded conditions.…”

Section: Discussionmentioning

confidence: 99%

No adverse effects of early weight bearing after uncemented total hip arthroplastyA randomized study of 20 patients

Bodén

Adolphson

2004

Acta Orthopaedica Scandinavica

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Background Few guidelines are available whether early weight-bearing after an uncemented total hip arthroplasty (THA) can be recommended or not. Stability and ingrowth may be jeopardized by immediate loading of the implant while functional recovery may be promoted and periprosthetic demineralization reduced.Patients and methods We did a prospective study of 20 patients who were operated on with a hydroxyapatite-coated (HA), uncemented total hip arthroplasty with a tapered stem because of unilateral arthrosis, and randomized the patients to the immediate (I) or late (L) weight-bearing (after 3 months) group. The shoe on the operated side was equipped with an auditory device signaling when the patient placed a load on the extremity. The clinical assessment was done with the Harris hip score at the time of the operation and after 12 and 24 months. Radiographs and dual-energy x-ray absorptiometry (DEXA) were evaluated for migration, femoral remodeling and bone mineral density (BMD) after 3, 6, 12 and 24 months. Tc-scintigraphy was done after 6, 12 and 24 months.Results Postoperatively, the Harris hip score showed no group difference. After 3 months, we noted a large reduction in BMD around the stem prosthesis. This was most marked in the proximal regions and the bone loss was significantly larger in zone 1, 4 and 5 in the L group. Distally, the BMD normalized with time, but the loss of bone persisted in the proximal zones after 24 months. An initial increase in the scintigraphic uptake ratio in all zones in both groups declined with time, but it was still increased on the operated side after 24 months. Several radiographic signs of bone remodeling were seen, but the patterns were similar in both groups.

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Section: Discussionmentioning

confidence: 99%

No adverse effects of early weight bearing after uncemented total hip arthroplastyA randomized study of 20 patients

Bodén

Adolphson

2004

Acta Orthopaedica Scandinavica

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“…In vitro experimental comparison studies between a curved anatomical stem and a straight stem [28][29][30] found that at low angles of flexion, the curved and straight stems demonstrated similar patterns of interface micromotion. However, at high torsional moments such as the one observed during stair climbing, the curved stem was found to be more stable than the straight stem.…”

Section: Discussionmentioning

confidence: 99%

Interface Micromotion of Cementless Hip Stems in Simulated Hip Arthroplasty

Kadir¹,

Kamsah²

2009

American J. of Applied Sciences

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Problem statement:The design of hip prostheses has evolved over time due to various complications found after hip replacement surgery. The currently commercially available cementless femoral stems can be categorized into one of three major types, straight cylindrical, tapered rectangular and anatomical. Each type proposes a unique concept to achieve primary stability-a major requirement for bone healing process. Virtual analyses have been made on individual implants, but comparison between the three major types is required to determine the strength and weaknesses of the design concepts. Approach: Three types of implants were modeled in three dimensions-the straight cylindrical, rectangular taper and anatomical. The size of the three implants was carefully designed to fit and fill the canal of a femur reconstructed from a computed tomography image dataset. Hip arthroplasty was simulated virtually by inserting the hip stem into the femoral canal. Finite element method was used in conjunction with a specialized sub-routine to measure micromotion at the boneimplant interface under loads simulating physiological walking and stair-climbing. Another subroutine was used to assign bone properties based on the grayscale values of the CT image. Results: All the three types of cementless hip stems were found to be stable under both walking and stair climbing activities. Large micromotion values concentrated around the proximal and distal part of the stems. Conclusion/Recommendations: The three major types of hip stems were compared in this study and all of them were found to be stable after simulated physiological activities.

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“…It has been thought that unprotected weight-bearing soon after cementless THA might increase the micromotion of the components and result in fibrous fixation at the implant-bone interface [1,2,19,20,24]. More recently, Jasty has reported that bone ingrowth was detected in a dog femur even though micromotion exceeded 50 µm [13].…”

Section: Discussionmentioning

confidence: 99%

“…It was thought that early weight-bearing might increase micromotion and result in fibrous ingrowth at the implant-bone interface [2,12,24]. Several reports have indicated, however, that early weight-bearing after cementless THA showed no negative influence on clinical results or implant stability [21,22].…”

Section: Introductionmentioning

confidence: 99%