Neuropathy in surgical-related locations has received concerns after total hip arthroplasty (THA), while the contralateral intercostal nerve (ICN) injury has not been reported. A 25-year-old female patient with a body mass index (BMI) of 17.9 kg/m2 visited the orthopedic outpatient clinic with complaints of progressive left hip pain for 20 days. She was diagnosed with left end-stage hip osteoarthritis and developmental dysplasia of the bilateral hips after radiographs and a detailed history-taking. After painstaking consideration, a cementless THA with the standard posterolateral approach was performed under general anesthesia. The procedure was difficult but successful. Unexpectedly, the numbness and slight tingling in the skin of the right breast, lateral chest wall, and axilla cropped up on the first postoperative day. Following the clinical features and the conclusion of the multidisciplinary discussion, we assume that ICN neuropathy is the diagnosis in this case due to compression of the lateral decubitus position during the operation. Her symptoms completely disappeared after using mecobalamin injection (0.5 mg, intramuscular injection, every other day) for 11 days. The Harris left hip score improved from 39 to 94, and the visual analogue scale from 7 was reduced to 2 on the day of discharge. There were no other complications within the first year after the operation. For THA, we should pay attention to some unexpected complications by virtue of the special position, especially in thin and low-BMI people, which suggested that further comprehensive perioperative nursing measures and the beneficial surgical position and anesthesia type were called for.