Background Low-level laser therapy (LLLT) has been proven to be effective in pain control and tissue repair after surgery. LLLT can be used as a physical modality for post-operative joint arthroplasty due to its safety for the patients with metallic implants with or without bone cement. However, there has never been any study using LLLT as a physical modality in patients after total knee arthroplasty (TKA) surgery.

Objectives The aim of this study was to evaluate the therapeutic effects of LLLT on clinical outcomes after TKA.

Methods Sixty-two patients were enrolled in this study. All the patients were diagnosed as primary knee osteoarthritis. They underwent primary unilateral minimally invasive surgery-total knee arthroplasty (MIS-TKA) performed by the same orthopedic surgeon who was specialized in minimally invasive arthroplasty surgery. They were randomized into two groups. Group I received 810 nm GaAlAs LLLT at a power output of 500 mW and a dosage of 80 J per session over the surgical site from post-operative day 2 for 3 days combined with standard rehabilitation program for post-operative TKA patients. Group II received placebo laser and the same program as in Group I. The following clinical parameters were recorded and analyzed (1) Visual analogue scale for pain (VAS) both at rest and at fully active knee flexion, (2) Active knee range of motion (ROM), and (3) Knee Society Score (KSS) which is composed of Knee Score plus Function Score.

All of the clinical parameters were collected at pre-operative day and postoperative day 2, 3, 4 and at 2 weeks & 6 weeks postoperatively except for KSS. We assessed KSS at pre-operative day and 6 weeks after surgery.

Results Fifty-four patients completed the study. Groups were comparable for age, body mass index (BMI), operation duration, intraoperative blood loss and length of stay. Resting VAS pain scores decreased significantly in the laser group, compared with the placebo group, from pre-operative day to post-operative day 4, and from post-operative day 4 to 2 weeks after surgery. VAS at full knee flexion decreased significantly in the laser group, between post-operative day 4 and 2-week postoperative scores.

Active knee ROM in flexion differed between two groups on post-operative day 2. Active knee extension at sixth week in laser group was significantly superior to placebo group whereas pre-operative knee extension lag was more in laser group. Overall KSS in laser group were significantly better than placebo group at sixth-week follow-up while there was no difference between groups before surgery. Moreover, Knee Scores in laser group at 6 weeks after surgery improved significantly from baseline scores while there was no significant improvement in placebo group. No side effect was reported from laser therapy.

Conclusions Post-operative low-level laser therapy improved early post-operative pain, post-operative ROM both in active knee flexion and extension. It showed beneficially therapeutic effects in terms of pain control and knee function after total knee arthroplasty, without side effects.

References

1. Enwemeka CS, Parker JC, Dowdy DS, Harkness EE, Sanford LE, Woodruff LD. The efficacy of low-power lasers in tissue repair and pain control: a meta-analysis study. Photomed Laser Surg 2004:22(4):323-9.

Disclosure of Interest : None declared

DOI 10.1136/annrheumdis-2014-eular.2642