Background: To our knowledge, the medium to
long-term outcome after revision knee arthroplasty with structural
allograft augmentation for reconstruction of uncontained defects
has not been determined. The purpose of the present study was to
assess the outcome for patients managed with such a procedure.
Methods: We prospectively followed fifty patients
who had fifty-two revision knee replacements with sixty-six structural
grafts performed at three institutions. Twenty-nine knees (twenty-seven
patients) were independently evaluated at a mean of 96.9 months (range,
sixty to 189 months) by an investigator who had not been involved
in the index procedure. Twelve knees (23%) had a repeat
revision at a mean of 70.7 months (range, twenty-six to 157 months). The
allograft was retained in two of these patients. Eleven patients
died at a mean of ninety-three months (range, sixty-one to 128 months)
after the procedure; the structural allograft and implants were
intact, and the patients were not awaiting revision at the time
Results: Clinical evaluation revealed that the mean
modified Hospital for Special Surgery knee score had improved from
32.5 points preoperatively to 75.6 points at the time of the review
and the mean range of motion had increased from 60.5° preoperatively to
88.6°. Failure was defined as an increase of less than 20 points
in the modified Hospital for Special Surgery knee score at the time
of the review or the need for an additional operation related to
the allograft. Thirteen knee replacements failed, yielding a 75% success
rate. Five knees had graft resorption, resulting in implant loosening.
Four knee replacements failed because of infection, and two knees
had nonunion between the host bone and the allograft. Two knees
(one patient) did not have a 20-point improvement in the knee score.
The survival rate of the allografts was 72% (95% confidence
interval, 69% to 75%) at ten years. On radiographic
analysis, none of the surviving grafts had severe resorption, one
had moderate resorption, and two had mild resorption. One knee had
a loose tibial component, and three knees had nonprogressive tibial
radiolucent lines. All four knees were asymptomatic.
Conclusions: Our results demonstrate that allografts
used in revision knee replacement in patients with the difficult problem
of massive bone loss have an encouraging medium-term rate of survival.