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· DOS Abstracts
ELBOW BIOMECHANINCS, RADIOCAPITELLAR JOINT
PRESSURE, AND INTEROSSOUS MEMBRANE STRAIN BE-
FORE AND AFTER RADIAL HEAD ARTHROPLASTY
Chalotte Krabbe Hemmingsen, Theis Muncholm Thillemann, Brian Elmengaard, Sepp de
Raedt, Emil Toft Nielsen, Sebastian Breddam Mosegaard, Kasper Stent-Olesen, Maiken
Stilling
Department of Clinical Medicine, Aarhus University Hospital, Denmark; Department of
Orthopedic Surgery, Shoulder and Elbow Section, Aarhus University Hospital, Denmark;
Department of Orthopedic Surgery, Shoulder and Elbow Section, Aarhus University
Hospital, Denmark; Nordisk Røntgen Teknik, Aarhus Denmark; Department of Clinical
Medicine, Aarhus University Hospital, Denmark; University Clinic for Hand, Hip and Knee
Surgery, Hospital Unit West, Denmark; Nordisk Røntgen Teknik, Aarhus Denmark; De-
partment of Clinical Medicine, Aarhus University Hospital, Denmark
Background:
Complex radial head fractures with associated elbow instability may be
treated with a radial head implant (RHA).
Purpose / Aim of Study:
To compare the elbow kinematics before and after anatomic
RHA in an experimental study.
Materials and Methods:
8 human native elbows (mean age 82 years, range 61-89)
were examined with dynamic radiostereometric analysis (dRSA) during forearm flexion
with neutral rotation, and further in supination and pronation with/without a 10N var-
us-valgus stress. Results were compared with dRSA after insertion of an anatomic RHA
(Acumed). Translations of the radial head in the x-, y- and z-directions relative to the
humerus and to the ulna were measured. The radiocapitellar joint (RCJ) contact pressure
and the tension within the interosseous membrane (IOM) was measured using a pressure
sensor and a custom-made strain gauge.
Findings / Results:
After RHA the radial head was displaced approximately 1.8mm me-
dially and 1.4mm distally compared with the native radial head. During unloaded flexion
motion the mean difference in translation between the native radial head and the RHA
was <1mm (CI95 +/- 0.5mm) (p=0.00), and with varus- valgus loading the difference
was <1.5mm (CI95% +/- 1.5mm) (p=0.00). The mean difference in RCJ contact pres-
sure was <0.30 MPa (CI95% 0.40 MPa) during unloaded flexion motion (p=0.00). The
tension in the IOM in supinated (p=0.03) and pronated (p=0.00) forearm position was
higher for the RHA compared with native elbows. Varus-valgus stress in supinated and
pronated forearm position decreased the IOM tension in the RHA elbows (p=0.00).
Conclusions:
There were only submillimeter kinematic changes and small changes in RCJ
joint pressure and IOM tension after insertion of an anatomical RHA in an experimental
setting.
No conflicts of interest reported
30.