Mirror Therapy for Total Knee Arthroplasty: A Pilot Study

Background: One in five patients experience persistent pain and disability after total knee arthroplasty (TKA), often driven by increased sensitization of the nervous system and pain. Pain and a sensitized nervous system are major barriers to postoperative rehabilitation impeding improved movement, and function. Objective: To determine if mirror therapy following TKA yields any positive shifts in self-reported pain, active range of motion (ROM) and nerve sensitivity (pressure pain thresholds - PPT). Design: Case series with pre- and immediate post-intervention measurements. Methods: A convenience sample of patients who just underwent TKA was recruited for the study. Prior to mirror therapy, self-reported pain, active knee flexion ROM and PPTs were measured. In hook lying, a mirror was placed between the legs, separating the surgical and non-surgical legs. Patients performed 3 sets of 10 supine heel slides with the non-surgical leg while watching the leg in the mirror, mimicking active knee flexion of the surgical leg. Results: Eighteen patients (9 female), with a mean age of 65.94 years and mean time since TKA of 7.83 days participated in the study. Immediately following mirror therapy, mean active knee flexion improved by 3.84 degrees (p = 0.001), with 10 patients exceeding minimal detectable change. Self-reported pain (p = 0.08), PPT of the surgical knee (p = 0.95), PPT of the non-surgical knee (p = 0.21) and PPT of the upper trapezius (p = 0.23) failed to show any significant improvement after mirror therapy. Conclusion: The results of this study show that mirror therapy immediately following TKA may have some benefit in improving ROM, but not pain or sensitivity of the nervous system. This is the first study exploring the immediate effects of mirror therapy in postoperative TKA.