After undergoing knee reconstruction, therapy with a machine that puts the joint through continuous passive motion leads to improved flexion when added to conventional physical therapy, according to a review by Canadian researchers.

It used to be that immobilization was the standard after orthopedic surgery, but nowadays early mobilization is the preferred approach.

Continuous passive motion (CPM) “is an external motorized procedure that enables a joint to move passively through a predetermined range of motion,” explain Dr. Lucie Brosseau and associates at the University of Ottawa in the Journal of Rheumatology.

However, individual studies of CPM have produced conflicting results, and there is no agreement on how effective it is in the long term.

To get a handle on the pros and cons, the team pooled the results of 14 trials that followed 952 patients who underwent physical therapy with or without CPM after having total knee replacement because of degenerative joint disease.

Two weeks after surgery, CPM was associated with a statistically significant increase in active knee flexion. Those treated with CPM also achieved 90 degrees of knee flexion an average of 4.7 days faster than the comparison group.

Patients were discharged an average of 0.69 days earlier when CPM was used.

On the downside, CPM can be costly, the researchers point out. “Potential benefits will need to be carefully weighed against the inconvenience and expense of CMP.”

However, Dr. Robert B. Salter of the Hospital for Sick Children, Toronto, in an accompanying editorial, contends that CMP is far more convenient than “frequent trips to the physical therapy unit.” He also quotes estimates that using this approach can save thousands of dollars per patient.

SOURCE: Journal of Rheumatology, November 2004.