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Femoral Component

- See: Total Hip Replacement Menu

- Discussion:
    - design considerations 
    - femoral stem collar
    - cemented femoral stems (radiology of cemented femoral stems
    - press fit femoral stems 
    - femoral component offset 
           - modular neck:
                   - Managing Length and Stability: The Role of the Modular Neck
    - rotational position of femoral component:
           - see: femoral component anteversionadult femoral and acetabular anteversion:
           - if component is placed in anteversion with respect to axis of knee, femur is placed posteriorly with respect to pelvis;
           - this is a stable situation, because excessive internal rotation is needed before the hip dislocates posteriorly and abductors do
                    not allow enough external rotation for hip to dislocate anteriorly;
           - excessive anteversion of femoral component of THR does not lead to dislocation problem, but it does limit external rotation;
           - excessive retroversion tends to produce posterior dislocation;
           - femoral components with inherent anteversion should be placed in neutral with respect to the plane of flexion of the knee; 
           - ref: Patterns of stress distribution at proximal femur after implantation of modular neck prosthesis. A biomechanical study.
    - stiffness of femoral stem:
           - high modulus (stiffer material such as cobalt chrome) will increase stresses in the stem and decrease stresses in the cement;
           - transfer of the stress into the distal stem might stress shield the proximal femur and lead to disuse bone resorption;
           - lower modulus (more flexible material such as titanium) can increase stress on the proximal bone but might also increase
                    stress on, and thus fatigue, the proximal cement increasing incidence of loosening;
    - trunion:
           - risk factors for trunionosis:
                   - thinner neck (larger head): reduced flexural rigidity
                   - shorter trunion: reduced contact area
                   - high offset implants
           - references:
                  - Trunnion corrosion: what surgeons need to know in 2018.
                  - What do we know about taper corrosion in total hip arthroplasty?
                  - Trunnionosis: A pain in the neck
                  - Effect of Taper Design on Trunnionosis in Metal on Polyethylene Total Hip Arthroplasty
                  - Trunnion-Head Stresses in THA: Are Big Heads Trouble?
                  - Taperosis: Does head length affect fretting and corrosion in total hip arthroplasty?
                  - Comparison of Whole-Blood Metal Ion Levels Among Four Types of Large-Head, Metal-on-Metal Total Hip Arthroplasty Implants: A Concise Follow-up, at Five Years, of a Previous Report.
                  - Adverse local tissue reactions in metal-on-polyethylene total hip arthroplasty due to trunnion corrosion: risk of misdx.
                  - Taperosis: Does head length affect fretting and corrosion in total hip arthroplasty?
                  - Ceramic Heads Decrease Metal Release Caused by Head-taper Fretting and Corrosion.
                  - Modern trunnions are more flexible: a mechanical analysis of THA taper designs
                  - What is the trouble with trunnions?
                  - Taper design affects failure of large-head metal-on-metal total hip replacements
                  - Tribocorrosion: Ceramic and Oxidized Zirconium vs Cobalt-Chromium Heads in Total Hip Arthroplasty
                  - A Survey of the Prevalence of and Techniques to Prevent Trunnionosis

    - femoral head size:  (see psoas tendonitis)
    - Calcar Collar:
           - A calcar collar is protective against early periprosthetic femoral frx around cementless femoral components in primary THA

- Femoral Revision:
       - removal of press fit stems 
       - removal of cemented femoral stems 
       - femoral press fit revision
       - cemented femoral revision 
       - bone grafting for femoral defects 
       - total femoral replacement

- Complications:
       - femur fractures following THR 
       - femoral stem failure 
       - types of loosening 
       - bending cantilever
       - cemented femoral component loosening 
       - thigh pain:
               - Thigh Pain After Total Hip Replacement: A Pathophysiological Review and a Comprehensive Classification

Histologic analysis of a retrieved microporous-coated femoral prosthesis. A seven-year case report
Hydroxyapatite-Coated Femoral Stems.  Histological Analysis of Components Retrieved at Autopsy.
Loosening of the femoral component after use of the medullary-plug cementing technique. Follow-up note with a minimum five-year follow-up
Histomorphological studies of the long-term skeletal responses to well fixed cemented femoral components
The survival of the cemented femoral component of a total hip replacement
Bone lysis in well-fixed cemented femoral components 
Improved cementing techniques and femoral component loosening in young patients with hip arthroplasty. A 12-year radiographic review.