Stretching Force of Incision Affects Early Clinical Results After Primary Total Knee Arthroplasty: A Retrospective Study

Abstract

Objective: To investigate the impact of different skin incisions on recovery from total knee arthroplasty (TKA).

Methods: This is a retrospective study conducted in a tertiary hospital. A total of 1210 patients accepted primary and unilateral total knee arthroplasty (TKA) at the authors' affiliated institutions between January 2015 and January 2019. Patients who accepted primary and unilateral TKA due to OA under epidural anesthesia were included. Excluded cases included patients who had no completed follow-up; preoperative flexion contracture greater than 15° and preoperative flexion less than 90°; paresthesia in lower limb; scar within the knee area; patella alta or baja. We recorded and analyzed the following data, including each patient's characteristics, incision stretching index (IS index), perioperative information, and follow-up assessments. Patients were grouped by trisecting the range of IS index we observed in the present study. The primary outcome measure was the visual analog scale (VAS) pain score rated on a scale of 0-10 from no pain to severe pain. Secondary outcome measures include knee girth reflecting postoperative swelling, knee range of motion (ROM), sensory testing, and the strength of quadriceps. These measures were completed 2 weeks postoperatively.

Results: A total of 1089 patients undergoing primary and unilateral TKA in our two institutions were screened for final analysis, and 121 ones were excluded. The patients were followed up for an average of 13.3 months postoperatively. The mean length of FL was 28.3 cm (range: 21.0-38.8 cm). The mean IS index was 2.7 cm (range: 0.4-5.1 cm). We found no significant difference in those data among groups (P > 0.05). VAS pain scores among group IS A, IS B, and IS C were significantly different (2.3 ± 0.6 vs 3.4 ± 1.6 vs 3.9 ± 1.5, P = 0.0001). Similar situations were seen in knee circumference, ROM, area of abnormal sensation, and quadriceps strength among groups (all P < 0.05). With the increase in the IS index, VAS pain score, knee circumference, area of abnormal sensation, and incision problems were significantly increased (P < 0.05). At the same time, ROM and the strength of quadriceps decreased (P < 0.05). With the increase in the IS index, the number of patients with incision problems was increased significantly (P < 0.05). Besides, no significant difference in PJI and DVT among groups was observed (P > 0.05).

Conclusions: Proper incision stretching can improve postoperative pain relief, surgical swelling, ROM, sensory disturbance of the knee, and the strength of quadriceps with reduced risk of incision complications.

Keywords: Incision stretching index (IS index); Range of motion; Total knee arthroplasty; Visual analogue scale.