highly significantP < 0.001
This effect was highly significant (chi-square test, χ 2 (2, n = 156–337) = 21.05–157.36, P < 0.001 for postoperative days 1, 3 and 7 on the ipsilateral side and χ 2 (2, n = 143–330) = 41.99–157.87, P < 0.001 for postoperative days 1, 3 and 7 on the contralateral side) and lasted until the postoperative day 7 on both the operated and unoperated sides.