iPACK Block for Chronic Knee Osteoarthritis: Pain Relief and Functional Outcomes.

Knee osteoarthritis (KOA) causes chronic pain, which impairs mobility. Access to total knee replacement surgery is limited in lower- and middle-income countries, with waiting times often extending to many years. Prolonged immobility is associated with increased perioperative complications. Reducing patients’ chronic knee pain whilst awaiting surgery may therefore improve their mobility and surgical outcomes. This study investigated if pain and physical function were improved in patients with KOA, awaiting knee arthroplasty, using an iPACK (infiltration between the Popliteal Artery and the posterior Capsule of the Knee) block.

Nineteen patients with KOA attending a specialist Pain Unit in South Africa were included in the study. Baseline measurements of pain and physical function were performed using the numerical rating scale (NRS) and Knee Injury and Osteoarthritis Outcome Score short form (KOOS-PS). An ultrasound-guided iPACK block was performed, using 20ml 0.25% bupivacaine and 80mg methylprednisolone. Repeat NRS and KOOS-PS measurements were obtained telephonically after one and two months, and in-person at three months.

Pain scores were significantly reduced at one month (NRS -2, p=0.044) and two months (NRS -2, p=0.021) but not month three. Similarly, physical function was significantly improved at month one (KOOS-PS -7.6, p=0.016), and month two (KOOS-PS -10.2, p=0.026) but not month three. Most participants (78.9%) reported satisfaction with the block.

An iPACK block reduces chronic pain and improves physical function in patients awaiting knee arthroplasty, for about two months. Larger studies are required to confirm these findings and if these translate to reduced perioperative complications.