Document Type: RESEARCH PAPER
Brigham and Women’s Hospital, Boston, MA, USA
Great Plains Orthopedics, North Platte, NE, USA
Background: Techniques that allow early muscle activation, such as closed kinetic chain (CKC) and open kinetic
chain (OKC) exercises, may play a beneficial role in the early rehabilitation of the reconstructed knee. However,
current rehabilitation regimens have not been shown to reverse post-operative quadriceps activation failure
and weakness. To investigate whether patients who use a continuous active motion (CAM) device that follows
closed kinetic chain principles have better early post-operative functional improvements than patients who use a
continuous passive motion (CPM) device that follows the principles of open kinetic chain principles. A prospective
randomized controlled trial with non-blinded study staff. A tertiary care clinic at a teaching hospital. A total of 110
patients signed the consent form and 83 patients participated in the study.
Methods: Patients were randomly assigned to use either the CPM device for 4 hours daily for 3 weeks (control
group), or a CAM device for 3 sessions of 20 minutes for 3 weeks (intervention group), starting 24 hours after
knee replacement surgery.The primary outcome measure was to identify the superiority, inferiority, or equivalence
of one device at week 4 after knee arthroplasty using various functional outcome measures such as kinesthesia,
quadriceps strength, coordination, general orthopaedic outcome measures and narcotic consumption.
Results: At 4 weeks, all outcome measurements were comparable between the two groups, with the exception
of sit-to-stand test: in the treatment group the time was significantly shorter compared to the control group
(P=0.016). Balance was significantly better in both control (P=0.001) and treatment group (P=0.032) compared
to prior surgery.
Conclusion: Most clinical centers would like to expedite functional recovery of knee arthroplasty patients without
increasing the risk of falls. We observed balance and kinesthesia improvements after surgery using either
device which may be important to benefit fast recovery programs. Further research is warranted to see whether
additional active closed kinetic chain exercised following knee replacement surgery could improve specific
functional outcomes such the observed sit-to-stand test.