Early postoperative transverse pelvic fracture: a new complication related to revision arthroplasty with an uncemented cup.
BACKGROUND
Uncemented hemispherical cups are commonly used to revise failed acetabular total hip components, even in the presence of marked acetabular bone loss. The purpose of the present study was to report a new complication of acetabular component revision with an uncemented hemispherical cup.


METHODS
We retrospectively reviewed the records of seven patients (seven hips) in whom an early postoperative transverse acetabular fracture had developed following the implantation of an uncemented trabecular metal cup for the revision of a failed acetabular component. All patients were female. The average age was 63.6 years. The reason for acetabular revision was aseptic loosening of the original cup in five patients and reimplantation after a previous resection arthroplasty in the remaining two. The average cup size used for revision was 58 mm. In two hips, additional modular acetabular metal augments were used to restore the acetabular rim.


RESULTS
The average postoperative time to diagnosis of a transverse acetabular fracture was eight months. Five of the seven patients presented with a marked acute increase in pain and a new displaced transverse acetabular fracture (pelvic discontinuity) that was visible on plain radiographs. Two patients were asymptomatic but had a nondisplaced transverse acetabular fracture. In all seven patients, the trabecular metal socket appeared radiographically to be well fixed to part of the pelvis. The five patients with a displaced fracture were managed with additional surgery to stabilize the fracture.


CONCLUSIONS
To our knowledge, early postoperative transverse pelvic fractures following revision of the acetabular component have not been reported previously. The most likely causes of this complication are further weakening of the remaining pelvic bone stock as a result of the reaming required to obtain a secure fit of a large-diameter hemispherical socket and the cyclic stresses on the weakened bone with resumption of walking. It is unlikely that the fractures occurred intraoperatively because in each case the socket remained well fixed to one of the pelvic fragments.
Springer
Bryan D
BD
OrthoCarolina Hip and Knee Center, 1915 Randolph Road, Charlotte, NC 28209. bryan.springer@orthocarolina.com.
Berry
Daniel J
DJ
Department of Orthopaedic Surgery, Mayo Clinic, 200 First Street S.W., Rochester, MN 55905.
Cabanela
Miguel E
ME
Department of Orthopaedic Surgery, Mayo Clinic, 200 First Street S.W., Rochester, MN 55905.
Hanssen
Arlen D
AD
Department of Orthopaedic Surgery, Mayo Clinic, 200 First Street S.W., Rochester, MN 55905.
Lewallen
David G
DG
Department of Orthopaedic Surgery, Mayo Clinic, 200 First Street S.W., Rochester, MN 55905.
D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D001843:Bone Cements; D005260:Female; D050723:Fractures, Bone / Q000209:etiology*; D006622:Hip Prosthesis / Q000009:adverse effects; D006801:Humans; D008875:Middle Aged; D010384:Pelvic Bones / Q000293:injuries*; D011475:Prosthesis Failure; D012086:Reoperation; D012189:Retrospective Studies
D001843:Bone Cements