The Effects of Cryotherapy on Quadriceps Corticomotor Excitability in Patients with Anterior Knee Pain.

摘要

Introduction: Central activation deficits (CAD) are a common occurrence following injury and could have long term implications such as developing early onset osteoarthritis. Individuals with anterior knee pain (AKP) have been seen to have higher magnitudes of CAD when compared to ACL deficient and ACL reconstructed populations. In addition, these deficits have been seen bilaterally suggesting that the activation deficit may be cortical in nature. The purpose of this study is to examine the effects of cryotherapy on quadriceps intracortical excitability in patients with and without anterior knee pain. Research Design: Case-control Methods: Thirteen participants (6 AKP: age 20.17+/-2.64years; height 1.60+/-0.04m; mass 63.67+/-5.86kg and 7 Healthy: age 22.86+/-1.07years; height 1.66+/-0.75m; mass 71.10+/-15.95kg) reported for two sessions, one week apart, during which they received either a cryotherapy intervention or no intervention. The order of condition was randomized and concealed from the tester. Measures of short and long interval intracortical inhibition (SICI and LICI), intracortical facilitation (ICF) and pain were recorded at baseline, and again at 10, 20, 35, and 50 minutes after intervention application (control or cryotherapy). SICI, LICI, and ICF were assessed using transcranial magnetic stimulation, while pain was assessed using a 10cm visual analog scale. Statistical Analysis: Mixed models ANOVAs with repeated measures on time were used to analyze pain, SICI, ICF, and LICI. Paired T-tests were used to determine statistically significant events in the event of a significant interaction. The a priori alpha level was P<0.05. Results: There was significant group by time interaction within LICI in the cryotherapy condition (P=0.025). Post hoc t-tests revealed LICI was significantly lower at 35 minutes compared to baseline during the control session in the healthy participants (Baseline:0.48+/-0.28; 35 minutes:0.33+/-0.17; P=0.042). There was a significant group-main effect for ICF (P=0.050) during the cryotherapy condition, but not the control condition. Post hoc testing revealed that at the 10 minute time interval ICF was significantly higher in the healthy group as compared to the AKP group (AKP: 0.85+/-0.22; Healthy: 1.33+/-0.48; P=0.044). During the control session there was a significant increase in pain over time within the AKP group at each time interval [(Baseline: 1.23+/-2.08cm;10 minutes: 1.96+/-2.13cm P=0.016; 20 minutes: 2.14+/-2.11cm; P=0.008; 35 minutes: 2.68+/-3.2cm; P=0.047; 50 minutes: 2.94+/-3.25cm; P=0.027)]. Additionally, pain was significantly higher in the AKP group at 10 and 20 minutes compared to the healthy group [(10 minutes: AKP: 1.96+/-2.13cm; Healthy: 0.00+/-0.00cm; P=0.047), (20 minutes: AKP: 2.14+/-2.11cm; Healthy: 0.00+/-0.00cm; P=0.032)]. Conclusion: It is difficult to address the changes revealed in ICF and LICI in healthy participants. To begin, LICI significantly decreased in the absence of intervention at 35 minutes. There is no reasonable explanation for this decrease aside of the variation in our collected data. During cryotherapy in the healthy group there was a significant increase in ICF at 10 minutes. This suggests that cryotherapy despite have little affect on our inhibitory measures, may have been able to facilitate. However, neither of these findings continued to trend in their respective directions at subsequent time points. Interestingly, there was a significant increase in pain within the AKP group when no cryotherapy was administered. We did not see this trend during their cryotherapy session, potentially suggesting that cryotherapy has the ability to limit pain from increasing. Despite several interesting findings, due to our limited sample size further research is needed to truly understand the role of cryotherapy as both a pain moderator and disinhibitory modality in patients with AKP.