Custom Triflange Implants



Custom Triflange Implants


Matthew W. Tetreault

Michael J. Taunton



Key Concepts



  • Custom triflange acetabular components provide a unique solution for bridging large acetabular defects that exceed the limits of defect-matching techniques.


  • These implants possess the strength to provide long-term stability without underlying support, the potential for biologic fixation, and the ability to address specific bony defects and pelvic anatomy.


  • Collaboration between the surgeon and implant design team is paramount during preoperative planning because intraoperative flexibility is limited.


  • A minimum of several weeks is required for implant design and fabrication.


Sterile Instruments and Implants


Instruments



  • Routine hip retractors


  • A full set of revision total hip arthroplasty (THA) instruments, including:



    • Cup explant system


    • Femoral component explant system


    • High-speed burrs (short and long pencil-tip burrs, 6.5-mm round burr)


    • Osteotomes (straight, curved, flexible)


    • Cement removal set/instruments to clean out intramedullary canal


    • Curettes


    • Cobb elevators


    • Drill, drill bits, threaded drill guides, depth gauge


  • In the event of a trochanteric osteotomy:



    • Cabling device/wire passers (also for prophylactic use during femoral component revision)


    • Oscillating saw


  • Sterilized models of the hemipelvis and triflange implant


Implants



  • Custom triflange acetabular component and liner


  • Custom triflange screws


  • Femoral heads (with trial heads)


  • Revision femoral components (with trial stems)


  • Cerclage cables and wires


  • Allograft bone chips


Positioning



  • Lateral decubitus with hip positioners


  • The operative limb should be draped out and sterilely prepared from the iliac crest to the distal thigh.



Surgical Approach



  • The authors typically prefer an extensile posterolateral approach, although an extensile anterolateral or transtrochanteric approach may be used.


  • A trochanteric osteotomy can facilitate femoral component removal and/or relieve tension when exposure for the iliac flange would risk traction injury to the superior gluteal nerve.


Preoperative Planning


Record Review



  • Obtaining the outside operative report and implant stickers is essential.


Laboratory Workup



  • Assess for infection preoperatively with inflammatory markers and fluoroscopically guided hip aspiration as indicated.


Imaging



  • Preoperative imaging is imperative and includes the following:



    • Anteroposterior (AP) pelvic radiograph


    • AP hip radiograph


    • Cross-table lateral hip radiograph


    • Judet radiographs (obturator and iliac oblique views)


    • Thin-slice computed tomography (CT) scan with 3-dimensional (3D) reconstruction


  • The above-mentioned imaging should be used to determine the extent of acetabular bone loss, including the presence and stability of a pelvic discontinuity (separation of the ilium from the ischiopubic segment), as well as the quantity and location of remaining host bone. This imaging also allows for the precise identification of in situ hardware.


  • If severe protrusion of the acetabular implant is present, CT angiography may be ordered to assess existing implant proximity to intrapelvic vessels. If vascular structures are at risk, preoperative evaluation by a vascular surgeon (who can be on standby at the time of surgery in the event of vascular compromise) is warranted. Very rarely, a retroperitoneal exposure is indicated to free the intrapelvic structures before implant removal.



Component Design

Dec 14, 2019 | Posted by in ORTHOPEDIC | Comments Off on Custom Triflange Implants

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