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Removal of Cementless Stems

- Pre Op Planning:
     - exam for THR loosening:
     - radiology of press fit stems
           - note degree of porous coating around the stem;
           - note any migration or subsidence of component which may indicate presence of fibrous membrane and poor osseous fixation;
           - as noted by Glassman and Engh 1992, radiographically stable stems are usually resistant to attempts at extraction;
           - in contrast, when cementless stems are painful and appear unstable on x-rays, they will often be easily removed;
                   - note however, stable fibrous ingrowth can make extraction difficult;
           - finally, cementless stems that were initially stable, do not usually become unstable in the presence of infection;
     - attempt to plan ahead of time as to whether trochanteric osteotomy is required;

- Removal of Cementless Stems: 
    - products for component removal;
           - if stem collar is not present, then there must be a variety of sturdy vice grip pliers, which can be applied to the trunion, and impacted with heavy maul;
    - if there is extreme difficulty in dislocating the hip, attempt to perform a wide capsulotomy or perform a trochanteric osteotomy;
    - it is essential to avoid a proximal femoral frx while extracting the stem;
    - before attempting prosthesis removal, remove granulation tissue and capsule around the neck of the prosthesis;
    - direct extraction of a femoral stem can be blocked by excessive cement or proximal bony overgrowth medial to the greater trochanter;
    - if the femoral head is modular w/ Morris taper, then remove it;
    - usually an ingrowth implant requires cutting of the ingrowth sites on all sides of the prosthesis;
    - area of ingrowth, whether fibrous or bone is first cut as far distally as possible by flexible osteotomes or a small power burr;
             - although power burr necessarily sacrifices some bone, this loss is better than fracturing proximal femur becuase bond was not broken adequately;
     - if the porous coating is only proximal, the femoral component can be extracted after the interface has been adequately cut;
     - remove all soft tissue and fibrous tissue from the bone stem interface, anteriorly, posteriorly, and laterally;
     - access to proximal fixation points anteriorly and posteriorly is easy;
             - access to posterior edge can be achieved w/ curved flexible osteotomes;
             - always direct the osteotome slight toward the prosthesis inorder to avoid cutting bone;
             - thin burr or thin flexible osteotomes will allow bone & fibrous tissue to be divided;
     - as long as flexible osteotomes are used in the proximal femur (where metaphyseal bone is present), the risk of fracture is minimal;
     - it is also important to clear the medial trochanter;
             - if large collar is present and there is an ingrowth area on the medial side of implant, this collar may have to be removed with a metal cutting burr;
             - curved thin osteotomes can then be slid down along the interface;
     - consider extended lateral trochanteric osteotomy:
             - one option is to create only one longitudinal limb of the osteotomy at a time;
                      - by using an osteotome to created a single longitudinal split down the femur, enough osseous disruption may occur to allow the prosthesis to be removed;
                      - if the prosthesis cannot be removed the other limb of the osteotomy is created; 
     - use of curved microsaggital saw blade
             - Removal of a well-fixed cementless femoral stem using a microsagittal saw.

- Distal Porous Coating:
     - if the porous coating extends well distally or if the prosthesis has a roughened surface distally esp titanium alloy stems,  interface between
             prosthesis and bone must be cut throughout most of or all of the stem length before the stem can be removed;
     - note that there is a significant chance of femoral fracture, when flexible osteotomes are used in areas where cortical bone has ingrown into  prosthesis;
             - this is especially the case w/ oversized femoral stems;
             - it may be safer in these areas to use a high speed burr;
             - it is also important to not only divide the ingrowth material, but remove it in order to allow further room for the burr to advance;
     - even small area of well ingrown porous coating may prevent removal;
             - safest method is to create an anterior cortical window about 1 cm wide throughout entire length of stem, saving  removed cortical bone for later repair;
                     - the interface around the rest of stem circumference is cut with flexible osteotomes;
                     - during reconstruction, the window is replaced and fixed with cerclage wires

The Removal of Porous Coated Femoral Hip Stems 

A technique of extensile exposure for total hip arthroplasty

Removal of cementless hip implants. Rubash HE et al. Instructional Course Lectures. 1991;40:171-176.

Technical Notes. Removal of a well-fixed cementless femoral stem using a microsagittal saw.

The removal of porous-coated femoral hip stems.

Posterior Longitudinal Split Osteotomy for Femoral Component Extraction in Revision Total Hip Arthroplasty

Cold Saline Lavage for Removal of Incarcerated Porous Ingrowth Stems