TKA is the most common and effective surgical procedure for the treatment of OA, leading to satisfactory functional recovery in patients. However, it can be associated with moderate or severe post-operative pain and an intense inflammatory reaction. Pain stems from the onset of loco-regional inflammation, and the presence of pro-inflammatory cytokines (interleukin-1beta: IL-1β, IL-6), tumor necrosis factor-α, histamine, bradykinin, prostaglandin, serotonin, substance P and acetylcholine, which stimulate nociceptors and induce hyperalgesia and allodynia [16
]. It has been demonstrated that the increase in SF-36 score is slow in the 1st
post-operative month and then accelerates at six and 12 months, when local inflammation and pain have been resolved [19
]. Inflammation and pain at the joint after TKA can limit rehabilitation and delay functional recovery [18
Innovative therapeutic strategies are required to locally control the inflammatory reaction following TKA.
It has been demonstrated that PEMFs have an agonist effect on A2A
adenosine receptors, and this explains the anti-inflammatory effects observed in experimental [8
] and clinical [10
] studies. Knees in sheep undergoing osteochondral grafts exposed to PEMFs show a reduced concentration in the synovial fluid of pro-inflammatory cytokines (IL-1β, tumor necrosis factor alpha: TNF-α) [22
]. In vitro
, PEMFs exposure prevents the release of PGE2
by synoviocytes cultured in the presence of pro-inflammatory cytokines (lipopolysaccharide, TNF-α) [23
These results support the rational basis for the use of PEMFs to control the inflammatory reaction that follows surgical procedures. Two randomized, prospective and double-blind studies have been conducted in patients undergoing arthroscopic procedure on the knee. The first study included patients with cartilage lesions undergoing microfractures, while the second concerned patients undergoing anterior cruciate ligament reconstruction. In both studies, early functional recovery of the joint and diminished consumption of NSAIDs were reported [10
In patients undergoing hip revision surgery, PEMFs treatment resulted in early pain control and enhanced functional recovery [15
]. Straburzynska-Lupa et al., in a clinical study of 25 patients treated with PEMFs combined with local cryotherapy following TKA, describe reduced pain, reabsorption of the edema and improved functional recovery [24
On the basis of the above evidence, this prospective, randomized and controlled trial was conducted to verify whether the treatment with I-ONE therapy, in addition to standard rehabilitation, could control pain, reduce swelling and improve functional recovery in patients undergoing TKA.
The Knee Score, based on objective examination of joint, was significantly better for the I-ONE group at two and six months after TKA, indicating that the positive effect is maintained even after the end of the treatment. Furthermore, the values of the Knee Score in the control group at 12 months were comparable with those observed in the experimental group two months post TKA.
The Functional Score, which measures the subjective evaluation of functional recovery, does not demonstrate statistically significant differences between the treated and control groups. These results are in agreement with those reported by other authors concerning the lack of correlation between the parameters of the subjective evaluation scales and those of the clinical-functional scales [11
SF-36 Health Survey score demonstrates that patients treated with I-ONE therapy after TKA had significantly higher values than the control group until month twelve. Furthermore, at 12 months the SF-36 value of the control group equated with that of the I-ONE group at one month.
The values observed for the control group were compared with information available in the literature for Knee Score, Functional Score and SF-36 Health Survey. Breugem et al. [26
] reported a change in Knee Score of 30 points over 12 months, which compares favorably with the 26 points change in this study. The major difference was observed for Functional Score, where the changes were 24 points versus 34 in the present study. In the control group, the SF-36 value doubled at 12 months follow-up and similar findings have been reported by Brandes et al. [27
]. In this study, the score values in the control group were comparable to those in other studies and the differences observed can be ascribed to the populations investigated, and surgical and rehabilitation procedures [28
Pain, monitored on the VAS scale, at all follow-ups was significantly lower in treated group with respect to control one. Swelling was resolved earlier in the treated group; no significant difference between groups was observed at 6 and 12 months. Other authors have reported that limitation due to swelling was important during the acute period (one month after TKA) and the improvement continued until 12 months after surgery [14
]. At one month after TKA, only 33% of patients in the experimental group, versus 93% in the control one, required NSAIDs (p
0.0017). The above observations are in agreement with previous reports concerning patients undergoing knee arthroscopic surgery [10
]. At six months, the number of patients using NSAIDs was still high (46%) in the control group (p
0.05 vs experimental group); however, it further diminished and at 12 months there was no difference between groups. It is accepted that recovery after TKA is longer than after total hip prosthesis. Jones et al., using a large series of patients (#256) undergoing TKA, reported pre-operatively average pain score of 43, increasing to 75 six months after surgery (100 indicating no pain); the study did not report the use of NSAIDs [31
]. Baker et al. reported that 19% of patients still suffered persistent pain one year after TKA [32
The lack of a placebo group is a limitation of this study, but it must be acknowledged that all clinical evaluations were carried out by physicians unaware whether the patient belonged to the control or experimental group. The small population size did not allow to reliably apply the group x time interaction effect test in the analysis of the results. Furthermore, the limited number of patients may explain the difference in Functional Scores observed at the baseline between the two groups. Patients’ compliance was a concern, as the use of I-ONE for four hours per day for 60 days requires significant commitment. However, the treatment was well accepted, and patient compliance was high (3.9 hours per day average use) as the device is portable, battery operated and can be worn while walking or at rest.