Impaction morcellized allografting and cement
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IMPACTION MORCELLIZED ALLOGRAFTING AND CEMENT. AAOS Instructional Course Lectures, Vol 48 Tom J. J. H. Slooff, MD B. Willem Schreurs, MD Pieter Buma Jean W. M. Gardeniers, MD. INTRODUCTION. Most Total Hip Arthroplasties (THA), cemented and cementless, fail because of aseptic loosening

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IMPACTION MORCELLIZED ALLOGRAFTING AND CEMENT

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Impaction morcellized allografting and cement

IMPACTION MORCELLIZED ALLOGRAFTING AND CEMENT

  • AAOS Instructional Course Lectures, Vol 48

  • Tom J. J. H. Slooff, MD

  • B. Willem Schreurs, MD

  • Pieter Buma

  • Jean W. M. Gardeniers, MD


Introduction

INTRODUCTION

  • Most Total Hip Arthroplasties (THA), cemented and cementless, fail because of aseptic loosening

  • Key problems in revision surgery:

    • Management of periprosthetic bone loss

    • Achieving long-lasting stability

    • Restoring hip biomechanics


Introduction1

INTRODUCTION

  • The authors of this lecture prefer the use of impaction allografting with cement for reconstruction of failed THA acetabular components


General issues

GENERAL ISSUES

  • Graft material:

    • Autograft - Bone that is transplanted from one location to another within the same individual

    • Allograft - Bone from another individual, but the same species

    • Xenograft - Bone from another species


General issues1

GENERAL ISSUES

  • The graft material goes through a series of processes in which the donor bone and host become closely interconnected.

    • Host supplies the blood vessels and viable bone cells

    • Graft stimulates the host’s cellular activity, ultimately leading to new bone formation in and around the graft


General issues2

GENERAL ISSUES

  • Factors that influence the success of incorporation of the graft material:

    • Firm fixation of the bone graft to the bone bed of the host

    • Extent of surface area between the graft and host bone

    • Vascularity of the surrounding host tissue

    • Load pattern of the graft


General issues3

GENERAL ISSUES

  • Structural vs morcellized allografts

    • Compact structural bone grafts are very dense, which strongly compromises the ingrowth of blood vessels

    • In the early stages, only the contact surface of the graft undergoes breakdown to create space for revascularization

    • Subsequently, the inner part of the graft remains dead bone and weakens due to fatigue fractures and graft resorption


General issues4

GENERAL ISSUES

  • Structural vs morcellized allografts

    • Morcellized allografts are incorporated more uniformly and completely

    • Blood vessels can easily penetrate, which means rapid bone apposition of dead trabeculae without any loss of mechanical strength


General issues5

GENERAL ISSUES

  • Since 1984, the authors (Slooff and assoc) have advocated their technique of dealing with acetabular segmental defects.

  • Acetabular segmental defects were closed with corticocancellous slices or with flexible metal wire meshes.

  • The contained acetabulum was tightly packed with allograft chips

  • The cup was inserted after pressurizing the cement directly onto the graft


General issues6

GENERAL ISSUES

  • The previous treatment sought to accomplish the following

    • Repair hip mechanics by positioning the cup at the level of the anatomic acetabulum (teardrop)

    • Close segmental defects with metal wire mesh to achieve containment

    • Replace the periprosthetic bone loss by augmenting the cavitary defect with morcellized allograft

    • Restore stability by impacting the chips and using bone cement


Surgical technique

SURGICAL TECHNIQUE

  • Posterolateral approach is used

  • Fluid and tissue are always sent to the lab to rule out infection as the cause of the loosening

  • All components and cement are removed

  • The transverse acetabular ligament is identified, and the socket is reconstructed from this level up

  • Cultures are also taken from this deep tissue as well


Surgical technique1

SURGICAL TECHNIQUE

  • The acetabular floor and walls are examined closely for any hidden medial and/or peripheral segmental defects

  • A flexible stainless steel mesh is trimmed and adapted to fit any of the defects and is rigidly fixed to the iliac wall with at least 3 screws

  • Defects are filled by tightly packing allograft chips into the areas

  • A 5mm layer of graft is placed circumferentialy in the area of the new cup


Surgical technique2

SURGICAL TECHNIQUE

  • Cement is pressurized and placed over the allograft, then the cup is held in position until the cement has hardened


Scientific studies

SCIENTIFIC STUDIES

  • Histologic analysis was performed to evaluate graft incorporation

    • At 1 month postrevision, no signs of graft incorporation were found

    • At 4 months, a front of new bone was found penetrating the avascular graft

    • At 8 months, various amounts of graft remnants were embedded in a new trabecular structure

    • At 15 months, bone closely resembled normal trabecular bone


Clinical results

CLINICAL RESULTS

  • Short term results:

    • 1984 study

    • 40 patients with 43 acetabular reconstructions

    • 21 primary, 22 revisions

    • After 2 years (0.5 to 5.5 years), there were no revisions, but 5 cases demonstrated radiolucent lines


Clinical results1

CLINICAL RESULTS

  • Midterm results:

    • 1993 study

    • 80 patients with 88 acetabular revisions

    • 5.7 year follow-up (2 to 11 years)

    • 42 cases for cavitary, 38 combined segmental/cavitary

    • 4 acetabular re-revisions (2 for infection)

    • Post op Harris Hip Score went from 44 to 87


Clinical results2

CLINICAL RESULTS

  • Long-term results:

    • The most reliable criterion in long-term follow-up of primary and revision THA’s is the survival rate of the prosthesis

    • 60 hips

    • 37 defects cavitary, 23 combined

    • 11.8 year f/u (10 -15 years)

    • 5 re-revisions were performed (2 infections)

    • Overall survival rate 90%


Conclusions

CONCLUSIONS

  • Experimental and clinical studies have shown that impacted morcellized allografts lead to a predictable result, with complete and rapid incorporation of the graft without impairing strength during the process

  • In contrast to structural allografts, which incorporate incompletely with unpredictable results

  • The use of wire meshes can be used in conjunction with allograft to fill segmental defects


Conclusions1

CONCLUSIONS

  • Impaction of the morcellized graft results in a stable and rough surface that improves the mechanical cement-bone interlock

  • Rigid impaction reduces gap formation between the host and graft, promoting the union process


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