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· DOS Abstracts
Is the learning curve in cementless unicompartmental
knee replacements related to periprostetic fractures
and subscidence?
Lasse E. Rasmussen, Bjørn Gotlieb Jensen, Claus Varnum
Orthopedic dept. , Sygehus Lillebælt, Vejle; Orthopedic dept. , Sygehus Lillebælt,
Vejle; Orthopedic dept., Sygehus Lillebælt, Vejle
Background:
Clinical and radiological data from a design centre of unicompart-
mental knee replacement (UKR) show as good as, or even better outcome of
the cementless compared to the cemented UKR. Our institution (a high volume
hospital with UKR surgeons performing on average 40 UKRs per year) changed
from cemented to cementless UKR in 2015 with a concomitant occurrence of
fractures and subscidence of the tibial implant, not previously observed in the
cemented UKR.
Purpose / Aim of Study:
To elucidate whether or not a learning curve relates
to early failures in cementless UKR.
Materials and Methods:
Since January 2015, we investigated clinical and x-
ray outcome after 4 weeks and 1 year in all patients, receiving a cementless UKR
at our institution
Findings / Results:
From Jan, 2015 to March 2016, 216 cementless UKR were
implanted by 5 knee surgeons. All the surgeons had patients with early peripros-
thetic fracture or subscidence. Within 6 months of primary UKR, 4.2% (9 of
216) underwent revision due to either fracture or instability from subscidence.
Periprostetic fractures 4/216 = 1,9%, (3 revised, 1 not revised), Subscidence
with the occurrence of instability and concomitant revision: 6 / 216 = 2,8%.
Radiological subscidence (not revised) 11/216 = 5 % In September 2015 we
altered the surgical technique, taking extreme care in tapping down the tibial
component, and the company provided coating on the lateral wall of the tibial
implant. Hereafter: Revision due to fractures = 0 %. 1 patient was revised due
to subscidence and instability.
Conclusions:
Even in high volume hospitals with experienced UKR surgeons,
shifting from cemented to cementless UKR may increase failure rate as a part
of a learning curve. Whether the implant design influenced the early failures
remains to be elucidated.
No conflicts of interest reported
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