Efficacy of Peripheral Cutaneous Nerve (PCN) on postoperative pain and functional outcome after total knee arthroplasty: a single-blind, randomized controlled clinical trial"

Abstract

Background: Postoperative pain is an important complication that impedes the functional recovery of the total knee arthroplasty (TKA). A variety of analgesic methods including the popliteal artery and capsule of the posterior knee block (IPACK), local infiltration analgesia (LIA) and peripheral cutaneous nerve (PCN) block have been applied via intraoperative or postoperative local injection for alleviating pain after TKA. The purpose of this study was to compare the analgesic effect and function outcome of two local anesthetic methods for reducing postoperative pain after TKA.

Methods: We demonstrated the effect of these two methods on postoperative pain, need for additional analgesics, functional recovery, and pain-related secreted proteins.

Results: One hundred twenty patients aged 50-75 years who underwent TKA for osteoarthritis between December 2021 to June 2024 were included in the study and divided into two groups as follows: Group A was given local anesthetic drug by IPACK combined with LIA; Group B was given the same local anesthetic drug formulation by IPACK combined with a novel PCN block. The visual analog scale (VAS) values, the need for additional analgesics and the expression of pain-related proteins in the Group B were lower than in the Group A on postoperative 6 h, 1, 2 and 3 days (P < 0.05). However, the joint ROM and early ambulation in the Group B were significantly higher than in the Group A on postoperative 1, 2 and 3 days (P < 0.05).

Conclusions: Based on the present evidence, patients treated with IPACK combined with new PCN block method can effectively reduce pain after TKA compared to IPACK combined with LIA. Furthermore, this approach not only mitigates postoperative pain but also decreases the need for postoperative analgesics and enhances patient's functional recovery.

Trial registration: NCT05202730, Date: 05/12/2021.

Keywords: Cutaneous nerve block; Functional recovery; Local anesthesia; Postoperative pain; Total knee arthroplasty.

Fig. 1

Flow diagram of patients' selection and exclusion

Fig. 2

The media, front and lateral view of anatomy of peripheral cutaneous nerves (PCN) around the knee joint (A) and injection point of LIA in group A (B, C) and PCN blocking in group B (D, E). (Arrow: femoral intermediate cutaneous nerve; Arrow head: medial femoral cutaneous nerve; Triangle: lateral femoral cutaneous nerve; Star: infrapatellar plexus)

Fig. 3

The levels of CFB, FN1, SFN, CXCL9, IGF-2 and TNF-α were higher in the group A than in the group B (p<0.05); in group A, the six proteins had statistically significant changes before and after operation (p<0.05); in group B, only TNF-α had higher levels at the first postoperative day than that before operation (p<0.05)

Fig. 4

HE staining×200. A is with a total knee arthroplasty patient with severe synovial inflammation, and pathological images show a large number of lymphocyte infiltrates. B is with a unicondylar arthroplasty patient, with a mild synovial inflammation and a mild lymphocyte infiltration in the pathological image