D.Bruni, MD; L.Bragonzoni, PhD; M.Gagliardi, MD; M.Bontempi, PhD; Akkawi I, MD; G.Raspugli,MD, Tedi...

ROENTGEN STEREOPHOTOGRAMMETRIC ANALYSIS:

AN EFFECTIVE TOOL TO PREDICT IMPLANT SURVIVAL AFTER AN ALL-POLY

UNICOMPARTMENTAL KNEE REPLACEMENT.

A 10 YEARS FOLLOW-UP STUDY

D.Bruni, MD; L.Bragonzoni, PhD; M.Gagliardi, MD; M.Bontempi, PhD; Akkawi I, MD; G.Raspugli,MD, Tedi M, MD; S.Patella, MD; Prof. M.Marcacci, MD.

Rizzoli Orthopaedic Institute – Bologna, Italy

The RSA system - background

What is RSA?

Roentgen Stereophotogrammetric Analysis

What it is used for?

The RSA system - background

how it works?

The RSA system - background

Materials and Methods

15 patients treated with UKA- allpoly tibial component, marked with tantalum beads.

Average age at surgery: 71 years

Average Follow Up: 10 years (range 4-15)

Evaluation mode:

1. Clinical evaluation:Knee Society Score (KSS) system [1]

2. Radiographic evaluation: RSA acquisition and software processing of data

Materials and Methods

Maximum Total Point Motion (MTPM)

 [1] Insall JN, Dorr LD, Scott RD, Scott WN. Rationale of the Knee Society clinical rating system. Clin Orthop Relat Res. 1989 Nov;(248):13-4.

Results: RSA evaluation

Results: RSA evaluation

Absolute values within 1° year: MTPM > 2mm in 3/4 revised patients MTPM < 2mm in 11/11 non revised

patients

MTPM differences between 1°-2° year: >0,2 mm in 4/4 revised patients <0,2mm in 11/11 non revised patients

Clinical results

Results: Clinical-radiographic correlation

Conclusions– Take Home Message

1. Even in the long-term static RSA is an efficient tool for the predictive evaluation of the state of fixation of an all-poly UKA

2. MTPM can be used as an early indicator of aseptic loosening:

Absolute values > 2mm within 1°year

MPTM differences between 1°-2° year > 0,2mm

High risk of

Aseptic loosening

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