Abstract
Introduction
Knee osteoarthritis is a leading cause of disability around the world. Traditionally, total knee arthroplasty (TKA) is the gold standard treatment; however, unicompartmental knee arthroplasty (UKA) has emerged as a less-invasive alternative to TKA. Patients with UKAs participate earlier with physical therapy (PT), have decreased complications, and faster discharges (1, 2). As UKA has evolved, so has computer navigation and robotic technology. The Robotic Assisted UKA combines the less invasive approach of the UKA with accurate and reproducible alignment offered by a robotic interface (3)(Figure1).
A key part of a patient's satisfaction is perioperative pain control. Femoral nerve blocks (FNB) are commonly performed to provide analgesia, though they cause quadriceps weakness which limits PT (4). An alternative is the adductor canal block (ACB) which provides analgesia while limiting quadriceps weakness (4). The adductor canal is an aponeurotic structure in the middle third of the thigh containing the femoral artery and vein, and several nerves innervating the knee joint including the saphenous nerve, nerve to the vastus medialis, medial femoral cutaneous nerve, posterior branch and occasionally the anterior branch of the obturator nerve (5).
In a multi-modal approach with Orthopedic Surgery, Regional Anesthesia, and PT departments, an early goal directed plan of care was developed to study ACB in UKA with a focus on analgesia effectiveness and PT compliance rates.
Methods
Following IRB approval, we performed a case series including 29 patients who received a single shot ACB.
Primary outcomes were distance walked with PT on postoperative day (POD) 0 and 1 and discharge day. Our secondary outcomes included Visual Analog Scale (VAS) scores in the post-anesthesia care unit (PACU), 8 and 24 hours postoperatively and oral morphine equivalents required for breakthrough pain.
Results
All patients received PT prior to discharge. With respect to distance walked, the median distance on POD 0 was 26 feet (IQR 9–66), and on POD 1 was 128 feet (IQR of 80–200), and the median day of discharge was POD 1 (IQR 0–2). In this study, the patients’ median age was 64 (IQR 59–69) and the median BMI was 31 kg/m2 (IQR 22–41). The median VAS score in the PACU was 1 (IQR 0–7). The VAS scores for 8 and 24 hours were 5 (IQR 2–7) and 5 (IQR 2.7–7). Median oral morphine equivalents required for breakthrough pain were 99.5 mg (IQR 67.5–150.5 mg) (Figure 3).
Conclusion
This case series supports that a single shot ACB facilitates early PT and hospital discharge in patients post UKA.
