High-intensity mechanical therapy for loss of knee extension for worker's compensation and non-compensation patients

Knee flexion contractures have been associated with increased pain and a reduced ability to perform activities of daily living. Contractures can be treated either surgically or conservatively, but these treatment options may not be as successful with worker's compensation patients. The purposes of retrospective review were to 1) determine the efficacy of using adjunctive high-intensity stretch (HIS) mechanical therapy to treat flexion contractures, and 2) compare the results between groups of worker's compensation and non-compensation patients.

Fifty-six patients (19 women, 37 men, age = 51.5 ± 17.0 years) with flexion contractures were treated with HIS mechanical therapy as an adjunct to outpatient physical therapy. Mechanical therapy was only prescribed for those patients whose motion had reached a plateau when treated with physical therapy alone. Patients were asked to perform six, 10-minute bouts of end-range stretching per day with the ERMI Knee Extensionater(r) (ERMI, Inc., Atlanta, GA). Passive knee extension was recorded during the postoperative visit that mechanical therapy was prescribed, 3 months after beginning mechanical therapy, and at the most recent follow-up. We used a mixed-model 2 × 3 ANOVA (group × time) to evaluate the change in passive knee extension between groups over time.

Regardless of group, the use of adjunctive HIS mechanical therapy resulted in passive knee extension deficits that significantly improved from 10.5° ± 5.2° at the initial visit to 2.6° ± 3.5° at the 3 month visit (p < 0.001). The degree of extension was maintained at the most recent follow-up (2.0° ± 2.9°), which was significantly greater than the initial visit (p < 0.001), but did not differ from the 3 month visit (p = 0.23). The gains in knee extension did not differ between worker's compensation and non-compensation patients (p = 0.56).

We conclude that the adjunctive use of HIS mechanical therapy is an effective treatment option for patients with knee flexion contractures, regardless of whether the patient is being treated as part of a worker's compensation claim or not.