Pelvic Allografts in
Revision Hip Surgery
Allan E. Gross, M.D.,
F.R.C.S.(C) Head, Division of
Orthopaedic Surgery Mount Sinai Hospital Professor of Surgery,
Department of Surgery University of Toronto Toronto, Ontario Contained Defect: A central or supero-medial protrusio may be
associated with a loose acetabular prosthesis. The bone stock is restored by using impacted morsellized
cancellous allograft bone. Some of
these defects are so large that 2 or 3 femoral heads may be necessary to
obtain enough bone for morsellization.
For morsellized bone female femoral heads should be used. There are several choices of acetabular
implants that can be used, both uncemented or cemented. For younger higher demand patients we
recommend impacted morsellized bone with a fixed metal-backed large diameter
cup. Contact with at least 50% host
bone must be made. It is necessary to
have rim contact between the cup and the host. If contact cannot be made with 50% host bone, then we recommend
a roof reinforcement ring and a cemented cup. The ring must make rim contact with the host superiorly,
posteriorly and inferomedially, and is fixed with at least 3 screws directed
into the acetabular dome. If a
contained defect is global involving all quadrants of the acetabulum, then a
reconstruction ring that goes from ilium to ischium must be used. Uncontained
Defects: a) Minor Column (Shelf): In some acetabular revisions, it is difficult
to obtain good coverage of the new cup because of supero-lateral bone loss due
to loosening or failure of having obtained good coverage during the primary
procedure due to lack of bone grafting.
In this situation intact male femoral head segments or true acetabular
allografts, can be used to provide good coverage of the acetabular
implant. These shelf grafts are fixed
with 45 mm cancellous screws placed in an oblique to vertical direction. The junction of the shelf allograft and
the pelvic wall is autografted with cancellous bone (flying buttress
graft). Cemented or uncemented
acetabular implants can be used in combination with the shelf graft. There is contact with greater than 50% of
host bone and therefore an uncemented cup can be used but it is technically
easier to use a cemented cup . b) Major Column: Major column defects are best restored with true acetabular
allografts. These are fixed to the
host with cancellous screws and are protected by reconstruction rings that
bridge the defect from host bone to host bone. In this situation, the cup must be cemented because there is no
contact with host bone. The
reconstruction ring spans and protects the graft and also fixes a
discontinuity if it exists. The ring
goes from ilium to ischium. The ring
is fixed by at least 3 cancellous screws inserted into the ilium, and 2
cancellous screws inserted into the ischium.
If good screw fixation cannot be achieved into the ischium, then the
inferior flange can be slotted into or buttressed against the ischium. Suggested Reading: 1. Garbuz D, Morsi E, Gross
AE: Revision of the acetabular component of a total hip arthroplasty with a
massive structural allograft. Study
with a minimum five-year follow-up.
J. Bone Joint Surg;78-A:693-97, May 1996. 2. Garbuz D, Morsi E,
Mohamed N, Gross AE: Classification
and reconstruction in revision acetabular arthroplasty with bone stock
deficiency. Clin
Orthop;324:98-107, 1996. 3. Morsi E, Garbuz D, Gross
AE: Revision total hip arthroplasty with shelf bulk allografts. A long-term follow-up study. J. Arthroplasty;11:86-90, 1996. 4. Gross AE, Duncan CP,
Garbuz D, et al: Revision arthroplasty of the acetabulum in association with
loss of bone stock. An Instructional
Course Lecture, The American Academy of Orthopaedic Surgeons. J. Bone Joint
Surg;80-A:440-51, March 1998. 5. Villar RN, Gross AE, McMinn D: Revision hip arthroplasty: A practical approach to bone stock (Villar RN, Gross Ae, McMinn D, eds). Butterworth-Heinemann, Linacre House Jordan Hill, Oxford, England 0X28DP, 1997.  Previous Lecture
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