This study aimed to determine the differences in shoulder pain, functional recovery, and tendon healing according to physical activity level in the early healing phase, when the overall physical activity is reduced due to shoulder joint immobilization, after arthroscopic rotator cuff repair (ARCR).
A total of 38 patients were included in this study as per the inclusion criteria. According to the classification criteria of the International Physical Activity Questionnaire (IPAQ) measured up to 6 weeks after the ARCR, the patients were classified into high (HPA, n=19) and low (LPA, n=19) physical activity groups. To examine the physical activity level-based differences between the groups, analyses results of shoulder pain, range of motion, functional score, grip strength, and isokinetic strength before and 6, 12, and 24 weeks after the surgery were compared. The tendon healing was analyzed by classifying the type according to the Sugaya classification using MRI results performed 6 months after the ARCR.
For shoulder pain, a significant interaction effect was observed between the time and groups; pain significantly reduced at all time-points in all the groups. In the difference between groups by time point, there was no difference according to sex at 6 weeks after surgery, and there was a significant difference only between physical activity levels (p<0.05). However, compared with the male and female HPA groups 12 weeks after surgery, there was no significant difference in the male LPA group, whereas the female LPA group showed significantly higher pain.
In shoulder range of motion, flexion, external rotation, and abduction showed significant interaction effect between time and groups. In both the groups, the joint range of motion significantly decreased 6 weeks after surgery (p<0.05). However, the HPA group recovered to the preoperative level at 12 weeks, whereas the LPA group showed a significantly decreased recovery (p<0.05). In addition, the joint range of motion of the HPA group was significantly greater at 6 and 12 weeks (p<0.05). No significant sex related differences were observed.
The American Shoulder and Elbow Surgeons score (ASES) represented a significant interaction effect between the time and groups. In the HPA group(p<0.05), the ASES score increased significantly at 6, 12, and 24 weeks after surgery (p<0.05), whereas in the LPA group, there was no significant difference at 6 weeks and the ASES score increased significantly at 12 weeks after surgery (p<0.05). In an analysis comparing the ASES score differences between the groups at each time-point after surgery, the HPA group showed significantly higher ASES scores than the LPA group at 6 and 12 weeks (p<0.05). No significant differences were observed between sexes.
In grip strength, there was a significant interaction effect between time and group (p<0.05). the HPA and the LPA groups showed a significant increase and decrease in grip strength after 6 weeks, respectively. Further, the grip strength of the HPA group was significantly higher at 6 and 12 weeks (p<0.05). There were no significant sex-based differences.
For isokinetic muscle strength, there was a significant interaction effect between time and groups in flexion and external rotation strength (p<0.05), but none between the extension and internal rotation strength. Muscle strength significantly increased in both the groups at 12 and 24 weeks (p<0.05); however, the HPA group showed significantly stronger muscle strength than the LPA group at 12 weeks (p<0.05). No significant differences were observed between sexes.
Tendon healing was not significantly different between males and females with the same physical activity levels. However, within the same sex, only females showed a significant difference between the high and low physical activity levels (p<0.05) and high level of physical activity significantly increased the tendon healing rate (p<0.05).
In conclusion, higher physical activity levels in the early healing phase after ARCR were found to result in faster pain relief and restoration of shoulder function. In particular, it was associated with higher tendon healing and lower retear rates in females. Therefore, physical activities using the lower extremities, such as walking, stair climbing, and stationary bicycle riding, should be emphasized in the early healing phase, when the overall physical activity level rapidly decrease due to shoulder joint immobilization, after the ARCR.