The goal of this study is to learn about pain after knee replacement surgery. The surgery uses a fast-recovery program called Enhanced Recovery After Surgery (ERAS).

The main questions are:

How many participants still have pain three months after surgery? How severe is the pain? How many participants still use strong pain medication (opioids)? Participants are adults undergoing knee replacement surgery at UZ Gent and following the ERAS program.

Researchers will collect information on pain and recovery before surgery and for up to three months afterward. Participants will answer simple questions about their pain and daily activities.

This study will help researchers understand post-surgical recovery and may help improve pain care in the future.

This prospective observational cohort study evaluates perioperative pain management and recovery outcomes in adult patients undergoing primary knee replacement surgery within an Enhanced Recovery After Surgery (ERAS), or fast-track, pathway at UZ Gent.

Knee arthroplasty is an established surgical intervention for patients with advanced joint disease, with the aim of improving mobility and reducing pain. The ERAS pathway integrates standardized perioperative care elements, including optimized anesthesia, multimodal analgesia, early mobilization, and reduced length of hospital stay. While ERAS protocols have demonstrated benefits regarding recovery and hospital discharge, the effect of these pathways on persistent postoperative pain and opioid use requires further evaluation.

Persistent pain after knee replacement surgery remains an important clinical outcome. A proportion of patients experience ongoing pain or functional limitations despite technically successful surgery.

Patients included in this study will undergo knee replacement surgery according to the institutional ERAS protocol. The protocol includes preoperative assessment, standardized perioperative care, and early postoperative mobilization. Suitability for the ERAS pathway is evaluated during the preoperative anesthesia consultation. Any deviations from the standardized pathway, including changes in perioperative management or rehabilitation, will be documented together with the reason for the deviation.

Patients undergoing knee replacement surgery according to the ERAS pathway will be followed prospectively from the preoperative assessment until three months after surgery. Data collected will include perioperative characteristics, pain scores, functional outcomes, neuropathic pain features, opioid use, and relevant clinical variables.

Clinical data will be collected prospectively from the preoperative period until three months after surgery. Pain outcomes will be assessed at predefined time points using validated pain assessment tools. Information regarding pain intensity, functional recovery, neuropathic pain characteristics, and opioid medication use will be collected. Additional perioperative variables, including patient characteristics, anesthesia technique, surgical technique, and relevant medical history, will be recorded.

The study population consists of approximately 120 patients undergoing primary elective knee arthroplasty over a one-year inclusion period. Patients who are not considered suitable for the standardized ERAS approach because of relevant medical, neurological, physical, cognitive, surgical, or rehabilitation-related factors will not be included.

The collected data will be analyzed to describe the occurrence and characteristics of persistent postoperative pain after knee replacement surgery within an ERAS pathway. Descriptive analyses will summarize patient characteristics, pain outcomes, opioid use, and recovery measures. Exploratory analyses will evaluate potential associations between perioperative factors and persistent postoperative pain.

As ERAS has become the standard of care at the institution, comparison with a conventional-care control group is not planned. Instead, findings from this cohort will be interpreted in relation to previously published data from conventional perioperative care pathways.

This study aims to provide clinical insight into pain recovery after knee arthroplasty within an ERAS program and may contribute to improving postoperative pain management and patient follow-up strategies.

Inclusion Criteria:

• All patients suitable for a standardized approach to the primary elective knee arthroplasty surgery and recovery period.

Exclusion Criteria:

• Significant comorbidities that may cause complications during the operation or the recovery period (e.g., heart and lung diseases, severe kidney disease, severe overweight).
• Severe neurological, physical, mental, and/or cognitive conditions that may complicate rehabilitation (e.g., inability to understand or follow postoperative instructions).
• Active infections or septic arthritis.
• Specific surgical obstacles such as revision surgery, extensive previous joint surgery, severe limitations in movement, severe instability, or marked abnormalities.

All patients for whom a knee replacement is planned by a surgeon at our hospital and who are eligible for the fast-track program.