Implant Removal



Implant Removal


Timothy S. Brown

David G. Lewallen



Key Concepts



  • The importance of efficient and bone-sparing implant removal cannot be overemphasized. Care and efficiency with this part of the procedure sets the reconstructive portion of the procedure up for success. Likewise, problems that develop in this portion of the procedure will echo throughout the procedure, often causing further problems.


  • Successful removal of implants in total hip arthroplasty (THA) requires careful preoperative planning.


  • In all cases, every attempt should be made to obtain the outside hospital records. This is useful for sizing, for determining the need for standard equipment (for example, hexagonal head versus cruciate head screwdrivers), for identifying the need for specialized extraction tools, and for predicting otherwise unsuspected intraoperative difficulties.


  • Preoperative radiographs should be carefully evaluated and can often help predict areas at risk for bone damage or bone loss on both the pelvic and the femoral side of the hip.


Sterile Instruments and Implants



  • Implant-specific removal tools (when the design of existing implant is known)


  • Large bone tamp


  • Drill bit and 50-mm 6.5-mm cancellous bone screw and companion drill bit


  • Curved osteotomes designed for cup extraction


  • Special curved blade cup removal tool (for example, Explant system, Zimmer Biomet, Warsaw, Indiana)


  • Small sagittal saw


  • Gigli saw and handles


  • High-speed burr with standard and pencil tips, metal-cutting burr


  • Universal stem extractor


  • Long-handled hip osteotomes (i.e., Moreland osteotomes, Depuy Synthes, Warsaw, Indiana)


  • Ultrasonic cement removal system (i.e., Oscar, Orthofix Inc., Lewisville, Texas)


  • Trephines


  • Large drill bit from femoral nail set


  • Broken hardware removal set (if broken screws are present)


  • Universal hardware removal set (if implant/screws are of unknown design)


Preoperative Planning



  • A key to successful removal of implants in THA is understanding the specific features of the implants that are coming out (Figure 24.1).



    • Obtain implant records from prior operations if at all possible.


    • Specific implant extraction tools are available for most designs, particularly for femoral components (Figure 24.2).


    • Certain constructs require special planning:



      • Well-fixed cemented femoral components


      • Well-fixed extensively porous coated femoral components







        Figure 24.1 ▪ Variety of femoral implants.






        Figure 24.2 ▪ Threaded area of proximal implant for extraction/insertion.


      • All polyethylene components


      • Monoblock acetabular components


      • Modular dual-mobility cups with metal liners


      • Stems with dual-modular femoral necks (Figure 24.3)


  • By examining the radiographs try to identify areas of bone loss and predict areas where the bone will be weak and at risk for fracture.



    • Pelvis



      • Anteroposterior (AP) pelvis, Judet oblique view, cross-table lateral radiographs. Perform careful evaluation of each zone of the acetabulum for osteolytic lesions (Figure 24.4).






        Figure 24.3 ▪ Dual-modular femoral neck implant that requires specialized extraction tool.






        Figure 24.4 ▪ Total hip arthroplasty with failure due to osteolysis and instability. Osteolysis medially was predicted from the radiograph and bone grafted at the time of revision THA.



    • Femur



      • AP hip, frog leg, or cross-table lateral radiographs of the femur. Careful evaluation of the proximal bone stock, femoral deformity, and stem alignment in both the coronal and sagittal planes are all important.


  • Know the previous operations



    • Get operative reports



      • Surgical approach?


      • Any complications?


Bone, Implant, and Soft Tissue Techniques



  • Any extensile approach to the hip joint can be used: anterolateral, posterolateral, or transtrochanteric, but understand how to perform each extensile approach when needed, including extended trochanteric osteotomy (ETO) (laterally based posterior to anterior, laterally based anterior to posterior, or anteriorly based [Wagner style] lateral to medial).


  • The hip is dislocated, the femoral head disimpacted with a bone tamp and mallet, and the femur retracted to expose the acetabulum if only the acetabulum will be revised.


Acetabulum

Dec 14, 2019 | Posted by in ORTHOPEDIC | Comments Off on Implant Removal
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