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DOS Kongressen 2016 ·
143
Dynamic radiostereometric analysis for evaluation of
hip joint pathomechanics
Lars Hansen, Sepp de Raedt, Bjarne Mygind-Klavsen, Peter Bo Jørgensen, Kjeld
Søballe, Bart L. Kaptein, Maiken Stilling
Orthopedic Research Unit, Department of Clinical Medicine, Aarhus University Hospital;
Research and development, Nordisk Røntgen Teknik, Hasselager; Department of
Orthopedic Surgery, Aarhus University Hospital; Orthopedic Research Unit, Department
of Clinical Medicine, Aarhus University Hospital; Department of Orthopaedic Surgery,
Orthopedic Research Unit, Aarhus University Hospital; Department of Orthopaedics,
Leiden University Medical Center; Orthopedic Research Unit, Department of Clinical
Medicine, Aarhus University Hospital
Background:
Dynamic RSA (dRSA) can track 3D in-vivo motion and describe hip joint
kinematics. The method can be used to understand the clinical pathomechanics of femo-
roacetabular impingement (FAI) and the biomechanical effects of arthroscopic cheilec-
tomy and –rim trimming (ACH).
Purpose / Aim of Study:
To evaluate the kinematic changes in the hip joint after ACH.
Materials and Methods:
Seven non-FAI affected human cadaveric hips were CT-
scanned and CT-bone models were segmented. Tantalum marker beads were placed in
the femur and pelvis. dRSA recordings of the hip joints were acquired at 5 fr/sec during
flexion to 90°, adduction to stop and internal rotation to stop (FADIR). ACH was per-
formed and dRSA was repeated. dRSA images were analyzed using model-based RSA
(MBM) and compared to marker-based RSA (MM) as gold standard. Hip joint kinematics
before and after ACH were compared pairwise.
Findings / Results:
There was no systematic bias between model-based and mark-
er-based RSA (p>0.05). 95% agreement limits were below ±0.44mm and ±0.9mm
for translations, and below ±0.7° and ±0.58° for rotations in the femur and pelvis re-
spectively. Mean hip internal rotation increased from 19.1° to 21.9° (p=0.04, Δ2.8°,
CI:0.3°;5.3°) after ACH surgery. Mean adduction of 3.9° before and 2.7° after ACH
surgery was unchanged (p=0.48, Δ-1.2° CI:-2.8°;5.2°). Mean flexion angles during
dRSA tests were 82.4° before and 80.8° after ACH surgery which was similar (p=0.18,
Δ-1.6°, CI:-4.1°; 0.9°).
Conclusions:
A small increase in internal rotation, but not in adduction, was observed
after arthroscopic cheilectomy and –rim trimming in cadaver hips. The hip flexion angle
of the FADIR test was nicely reproduced at followup. dRSA kinematic analysis is a new
and clinically applicable method for the hip joint and may have good potential for testing
of FAI pathomechanics and surgical corrections.
No conflicts of interest reported
94.