Fixation of the Simpliciti stemless humeral component, a radio-steophotogrammatic analysis

Rationale:

Shoulder arthroplasty has traditionally been designed as a stemmed device relying on intramedullary fixation for its stability. Unfortunately drawbacks in stemmed arthroplasty devices are caused by stress-shielding, stress risers, fractures and the need for modularity due to variable anatomy. Therefore, in shoulder arthroplasty short stem devices are developed. It has been proven that the fixation of the humeral component is not compromised due to a shorter stem. However, a reduced area of fixation, like the stemless design, can hypothetically show compromised fixation in the initial or long term. To quantify motion of a stemless design Roentgen Stereometric Analysis (RSA) can be used. In this study, we will identify the fixation and migration patterns of the Simpliciti (Tornier, France) stemless humeral component using RSA.



Objective:

Identifying the fixation and migration patterns of the Simpliciti (Tornier, France) stem less humeral component in vivo, using model based radiostereophotogrammetric (mRSA) analysis.
Evaluating the short and midterm clinical results (NRS for pain, range of motion, Constant score, SF-12, Dash and radiographs).



Study design:

We will perform a prospective cohort study in which 25 patient from Reinier de Graaf Hospital, Delft, The Netherlands, will be enrolled. Patients will be evaluated preoperatively, during hospital stay within the first week postoperatively, at 6 weeks, 6 months, 1 year and after 2 years.



Study population:

The study population will consist of 25 patients aged 45
years and older, with a BMI<35. The subjects will have no clinical relevant disorders of the shoulder and they will undergo a primary shoulder replacement after diagnosis of osteoarthritis, traumatic osteoarthritis, rheumatoid arthritis or avascular necrosis of the humeral head.



Main study parameters/endpoints:

Outcome will be clinically measured using the NRS for pain, Constant score, Oxford shoulderscore,
SF-12 and DASH score, whilst radiographic outcomes will be evaluated through standard radiographic parameters. RSA will be used to measure stem migration.



Nature and extent of the burden and risks associated with participation, benefit and group relatedness: Subjects participating in the study will have the same risks and benefits when not participating in the study. Follow-up times are standard protocol evaluations of the prosthesis. Besides standard follow-up, RSA x-rays will be made to measure the fixation.

The Simpliciti stemless humeral component is a stable implant with minimal translation, rotation and micromotion.

- Preoperative

- During hospital stay

- 6 weeks postoperative

- 6 months postoperative

- 1 year postoperative

- 2 years postoperative

Placement of the Simpliciti stemless humeral component prosthesis, with insertion of tantalum beads for radiosteraophotogrammetric analysis (RSA).