This prospective observational cohort study aims to evaluate the association between perioperative dexamethasone administration and early postoperative recovery following primary total knee arthroplasty. In routine clinical practice, dexamethasone may be administered orally, intravenously, or not administered, depending on the surgeon's established perioperative protocol.

The primary objective is to assess early postoperative recovery in terms of pain intensity, functional mobility, and knee joint range of motion. Secondary objectives include evaluation of inflammatory response, postoperative metabolic changes, opioid requirement, and the severity of postoperative nausea and vomiting (PONV).

Group allocation is non-randomized and determined solely by the standard perioperative management approach routinely applied by the surgeon selected by the patient. No additional interventions are introduced for research purposes. All outcomes are assessed prospectively during the early postoperative period.

Total knee arthroplasty (TKA) is an effective treatment for advanced knee osteoarthritis; however, early postoperative recovery may be influenced by pain severity, limited functional mobility, systemic inflammatory response, metabolic alterations, and postoperative nausea and vomiting. Optimization of perioperative medical management is therefore a key component of enhanced recovery pathways.

Dexamethasone is frequently incorporated into perioperative care due to its anti-inflammatory, analgesic, antiemetic, and metabolic effects. Despite widespread use, variability persists in routine clinical practice regarding route of administration and dosing strategies. Comparative real-world data evaluating oral and intravenous administration within standardized care pathways remain limited.

This study is designed as a single-center, prospective observational cohort investigation evaluating early postoperative recovery parameters associated with routine perioperative dexamethasone strategies. The study does not introduce experimental interventions, randomization, or alterations to established treatment protocols.

Participants are assigned to cohorts according to the routine perioperative management approach of the operating surgeon selected by the patient. Each participating surgeon follows a predefined dexamethasone protocol that was implemented prior to initiation of this study. Treatment allocation is therefore independent of the research process and reflects real-world clinical practice.

The exposure of interest is perioperative dexamethasone administration as part of routine clinical care. Exposure status is defined according to the route of administration applied within the surgeon's established perioperative protocol: intravenous dexamethasone, oral dexamethasone, or no dexamethasone.

The standard institutional regimens consist of 8 mg administered preoperatively and 4 mg administered on postoperative day one, delivered either intravenously or orally depending on routine practice. Patients receiving no dexamethasone serve as the comparison cohort. Exposure classification is determined prior to postoperative outcome assessment.

All surgical procedures are performed using standardized institutional techniques for primary total knee arthroplasty. Postoperative management follows a multimodal analgesic protocol consistent across cohorts. Rescue opioid administration is provided when clinically indicated, and cumulative tramadol dose is recorded. Laboratory monitoring and clinical assessments are performed according to routine perioperative care standards.

Outcome data are collected prospectively using standardized and validated measurement tools during the early postoperative period. Baseline demographic and clinical variables are documented to account for potential confounding factors. Statistical analyses will include appropriate parametric or non-parametric tests depending on distributional assumptions. Repeated measurements will be evaluated using repeated-measures analysis or mixed-effects modeling, with multivariable adjustment to account for baseline differences between cohorts. Statistical significance is defined as p < 0.05.

The study is conducted in accordance with the Declaration of Helsinki and has received institutional ethics committee approval. All participants provide written informed consent prior to enrollment. Participation does not alter standard clinical management.

Inclusion Criteria:

• Age between 50 and 80 years
• Diagnosis of primary knee osteoarthritis (primary gonarthrosis)
• Scheduled for elective primary total knee arthroplasty
• ASA physical status I or II
• Ability to ambulate independently (with or without assistive devices) preoperatively
• Ability to understand study procedures and complete pain and functional assessments
• Provision of written informed consent

Exclusion Criteria:

• Revision total knee arthroplasty
• History of knee joint infection
• Inflammatory arthritis (e.g., rheumatoid arthritis)
• Chronic systemic corticosteroid use
• Uncontrolled diabetes mellitus
• Known endocrine disorders affecting glucose metabolism
• Active infection at any site
• Known hypersensitivity to corticosteroids
• Severe hepatic, renal, or cardiac disease
• Neurological or musculoskeletal disorders affecting gait or balance
• Inability or unwillingness to comply with study procedures

The study population consists of adult patients aged 50 to 80 years with a diagnosis of primary knee osteoarthritis who are scheduled to undergo elective primary total knee arthroplasty at Istanbul Sultangazi Haseki Training and Research Hospital. Eligible participants have an ASA physical status of I or II and are able to ambulate independently prior to surgery. All participants are capable of understanding the study procedures and providing written informed consent.

Patients are managed according to the routine perioperative dexamethasone protocols of the surgeon selected by the patient. Group allocation is based on the standard clinical practice of the chosen surgeon and not assigned by the investigators. Participants are followed prospectively to evaluate postoperative pain, inflammatory response, functional mobility, postoperative nausea and vomiting, and analgesic requirements during the early postoperative period.

Individual participant data will not be shared due to institutional policies, patient privacy considerations, and the observational nature of this single-center study. The collected data are intended solely for the purposes of this research and related academic publications.