Background Postoperative pain is one of the main factors that delays recovery after prosthetic knee surgery. The use of sufentanil sublingual tablet systems (SSTS) can effectively relieve postoperative pain, but their value in facilitating early mobilization has been little studied so far. Our aim here was to assess whether their use could facilitate recovery after knee arthroplasty in an enhanced recovery program. Case presentation In a prospective observational single-center study, thirty patients operated on for primary knee arthroplasty in the enhanced recovery pathway were included. Patients who received the SSTS (n=15) were compared with those who received an intravenous morphine patient-controlled analgesia (PCA) (n=15). Our recovery program included in particular the use of an adductor canal block, periarticular infiltration of local anesthetic by the surgeon, removal of the venous cannula from the recovery room if possible, the use of an SSTS when available or an IV morphine PCA otherwise, and early physiotherapy. Recovery parameters including the Timed-Up and Go test, pain scores at rest and on exertion, knee flexions, complications, and lengths of hospital stay were not significantly different between the two groups. However, the postoperative opioid consumption in morphine equivalents was significantly greater in the SL-sufentanil group and these patients had their venous cannula removed earlier than in IV-morphine group. Conclusion In our center, the use of a SSTS was suitable for treating postoperative pain after knee arthroplasty, but it did not improve early recovery in comparison with a morphine PCA.