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Abstract
Background Osteoarthritis (OA) patients encounter progressive pain and functional disabilities, including joint stiffness, due to degeneration of the joint tissues. For knee OA, the most prevalent form, available treatment strategies are limited in number and focus primarily on minimizing the functional disability, inflammation, and pain in a conservative manner since still no unambiguously proven effective disease modifying approaches are available. Progress in the development of joint sparing procedures however, has demonstrated the regenerative capacity of the osteoarthritic knee and with that the delay for conventional last resort therapy such as total knee arthroplasty (TKA). Knee Joint Distraction (KJD) is a joint preserving procedure that can postpone knee arthroplasty in case of knee osteoarthritis for over 5 years [1]. Distraction is applied with an external fixator for 6–8 weeks.
Objectives To reduce the burden on patients during treatment originating from a restriction in joint flexion during KJD, we evaluated an articulating frame. A personalized articulating KJD-device was developed, biomechanically tested, and technical feasibility was evaluated in cadaveric legs. Reproduction of joint specific motion was demonstrated and articulating KJD was concluded to be technically feasible. In this study, clinical feasibility was tested in 3 patients.
Methods Patients received rigid knee joint distraction treatment in general practice. After 2–4 weeks, the frame was removed in the outpatient clinic and the joint was flexed in a continuous passive motion (CPM) device until 30° flexion was reached, or motion became painful. Subsequently, the articulating frame was attached to the bone pins (figure 1), followed by computerized personalization of the hinge from a non-invasive motion measurement. After assembling the custom parts, weight-bearing and non-weight-bearing radiographs were taken at 0, 15, and 30° flexion for joint space width measurements. Finally, the articulating device was replaced by the rigid frame and treatment was continued according to clinical practice.
Results For none of the three patients, the articulating distractor could be personalized. In the first patient, 15° flexion was achieved on the CPM, but pin positions did not allow for positioning of the frame. In the other patients, 8° and 15° flexion was measured, which was too little motion for the custom software to generate personalized hinge parts. Pain at the pin sites during motion was reported by all patients.
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.
References
Woude J-TAD van der, Wiegant K, Roermund PM van, Intema F, Custers RJH, Eckstein F, et al. Five-Year Follow-up of Knee Joint Distraction Clinical Benefit and Cartilaginous Tissue Repair in an Open Uncontrolled Prospective Study. Cartilage. 2016 Aug 26;1947603516665442.
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Disclosure of Interest None declared