Why You Wake Up With
Less Pain After Knee Replacement

One of the most common fears patients have before knee replacement is not the surgery itself — it is the pain afterward. This is understandable, and it is something I take seriously. The good news is that how we manage pain after knee replacement has improved significantly, and the approach we now use makes a meaningful difference in the early recovery experience.

The Problem: Knee Pain Comes From Two Directions

The knee receives pain signals from both the front and the back. Traditional nerve blocks targeted only one side, which meant patients often had reasonable pain control at the front of the knee but still experienced significant pain behind it — especially when bending or straightening the leg after surgery.

For knee replacement to be truly successful, both directions need to be addressed.

Two Blocks, One Goal

Adductor Canal Block (ACB)

The adductor canal is a tunnel on the inner thigh through which the saphenous nerve runs — a sensory nerve responsible for pain signals from the front and inner side of the knee. An ultrasound-guided injection of local anesthetic into this canal quiets the front of the knee without affecting the muscles you need to walk.

This is a key advantage over older techniques such as the femoral nerve block, which numbed the thigh muscles and made walking difficult and unsafe in the early postoperative period.

iPACK Block

iPACK stands for Infiltration between the Popliteal Artery and Capsule of the Knee. This is an ultrasound-guided injection into a small space behind the knee, targeting the sensory nerves of the posterior knee capsule — the source of the deep, aching pain patients feel when trying to bend the knee after surgery.

Critically, the iPACK block is purely sensory. It does not affect the muscles behind the knee, so walking and bending are preserved from the outset.

What the Evidence Shows

This combination has been studied extensively. A 2022 systematic review and meta-analysis in the Journal of Orthopaedic Surgery and Research found that adding iPACK to the adductor canal block resulted in significantly shorter hospital stays compared to the adductor canal block alone. A 2025 scoping review covering 130 randomized controlled trials confirmed that all four meta-analyses examining the ACB + iPACK combination found superior postoperative pain control and reduced need for rescue pain medication compared to ACB alone. A 2024 propensity-matched study further showed that the ACB + iPACK combination provided superior pain control and earlier ambulation compared to the traditional femoral + sciatic nerve block combination, with less motor impairment.

What This Means for You

In practical terms, patients who receive both blocks typically experience the following compared to those who do not:

How We Perform These Blocks

Both injections are performed under real-time ultrasound guidance after general anesthesia has been induced, before the surgery begins. Because you are already fully asleep under general anesthesia at this point, you will not feel discomfort during either injection. The entire process takes approximately 10–15 minutes.

The local anesthetic typically lasts 12–18 hours. This overlapping period, combined with scheduled oral anti-inflammatory medication, creates a smooth transition as the block wears off.

Frequently Asked Questions

A Note on Our Approach

We introduced the ACB + iPACK protocol in April 2026 as a standard part of our knee replacement pathway. We track patient outcomes — including pain scores on the first postoperative day and early range of motion — as part of our ongoing clinical registry. Our aim is to continuously refine what we offer based on real-world data from our own patients.

If you have questions about pain management before your surgery, please bring them to your consultation. Understanding what to expect is one of the most effective ways to reduce anxiety and prepare for a smooth recovery.