Clinical Feasibility of Personalized Articulating Knee Joint Distraction

Introduction: Knee Joint Distraction (KJD) is a joint preserving procedure
that can postpone arthroplasty in case of knee osteoarthritis. Distraction
is applied with an external rigid fixation device for six weeks. To reduce the
burden during treatment due to the absence of joint flexion, we developed a
personalized articulating KJD-device. Its technical feasibility, joint-specific
motion reproduction, was previously pre-clinically demonstrated. In this study,
clinical feasibility of this new device was tested in three patients.

Materials and Methods: Patients received conventional KJD treatment with
a rigid distraction device. After two to four weeks, the device was removed during
a one-day hospital visit and the joint was flexed on a Continuous Passive Motion
(CPM) device until 30 degrees of flexion was reached, or motion became too
painful. Subsequently, the articulating frame was assembled and personalized
with custom hinge parts based on a non-invasive joint motion measurement.
Weight-bearing and non-weight-bearing radiographs were intended to be taken
at 0, 15, and 30 degrees of flexion for joint space width measurements. Finally,
the articulating device was replaced by the rigid distractor and conventional
treatment was continued.

Results: For none of the patients, the articulating distractor could be
personalized adequately. Insufficient joint motion was achieved during CPM due
to intolerable pain at the pin sites.

Conclusions: Despite confirmation of joint-specific articulating distraction
on cadaveric legs, clinical feasibility could not be demonstrated, mainly due to
painful motion of soft tissues along the bone pins. Safe and solid anatomical
location of pins is considered to hamper articulating distraction