DOS 2017

· DOS Abstracts

Outcome of tibial component valgus subsidence in ce-

mentless Oxford unicompartmental knee replacement

Lasse E. Rasmussen, Thomas Lind-Hansen, Claus Varnum, Per Wagner Kristensen

Orthopedic Dept. , Sygehus Lillebælt, Vejle Hospital; Orthopedic Dept

Background:

We shifted from the cemented to the cementless Oxford uni-

compartmental knee replacement (OUKR) in January 2015 to reduce the risk of

cementing errors and mistaken revision from radiolucent lines. Upon the change

we experienced a number of tibial fractures and tibial component subsidence. In

September 2015 we altered our surgical technique, by gently tapping down the

tibial component and moving the vertical cut as lateral as possible, to ensure the

largest possible component.

Purpose / Aim of Study:

To investigate if the new surgical approach altered

the occurrence of tibial component subsidence and, in the case of subsidence,

to investigate the 1-year outcome.

Materials and Methods:

We performed a prospective intervention study. X-

rays were taken postoperatively at 4 weeks and 1 year for all cementless OUKR

operated in 2015 and 2016. 1 year after surgery, all patients were interviewed

regarding satisfaction. Results were compared before and after the intervention.

Findings / Results:

Subsidence occurred within 4 weeks in 42/187 women

and 28/166 men. Subsidence before September 2015; 28/105 = 27%. After

September 2015; 42/250 = 17%; (p =0,037). The tibial component subsid-

ed within the first 4 weeks; hereafter it remained stabile for the following 11

months in 49 (98%) of the cases. 38 patients (78%) were extremely satisfied,

8 (16%) were satisfied, and 4 (8%) were less satisfied. Two of the less satisfied

patients were due to neuroma formation. The level of satisfaction was similar in

patients before and after the intervention in September 2015.

Conclusions:

Valgus subsidence of the tibial component in cementless OUKR

may depend on the surgical technique. It may occur within the first 4 weeks

postoperatively whereafter the component stabilizes. Valgus subsidence does

not seem to affect patient-reported outcome 1 year postoperatively.

No conflicts of interest reported

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