Total knee arthroplasty (TKA) is widely regarded as one of the most successful and cost-effective surgical interventions for relieving pain and restoring function in patients with end-stage knee osteoarthritis.(1) As the global burden of osteoarthritis continues to rise alongside an ageing population, the annual volume of TKA procedures performed worldwide is projected to increase substantially, placing growing emphasis on optimizing postoperative recovery pathways to reduce hospital resource utilization while preserving patient outcomes.(2) Among the modifiable elements of perioperative care, the timing of postoperative mobilization has emerged as a central focus, given its direct influence on pain, functional recovery, and length of hospital stay.

Historically, patients undergoing TKA were kept on bed rest for one to several days postoperatively to allow wound stabilization and pain control before initiating physiotherapy. However, this conventional approach is now recognized to carry its own risks: prolonged immobility predisposes patients to deep vein thrombosis, pulmonary embolism, muscle atrophy, joint stiffness, and delayed functional independence.(3) The introduction of Enhanced Recovery After Surgery (ERAS) protocols across orthopaedic practice has shifted this paradigm, placing early mobilization—commonly defined as ambulation within 24 hours of surgery—at the core of postoperative management, alongside multimodal analgesia, optimized anaesthesia, and blood conservation strategies.(4)

A growing body of evidence supports the benefits of early mobilization after lower-limb arthroplasty. A systematic review and meta-analysis of randomized controlled trials by Guerra and colleagues found that early mobilization following hip or knee arthroplasty reduced hospital length of stay by an average of 1.8 days compared with traditional protocols, without increasing adverse events.(5) Similarly, a large multicentre retrospective cohort study from China involving more than 6,000 TKA patients demonstrated that ambulation within 24 hours was associated with significantly shorter length of stay, lower postoperative pain scores, greater knee flexion range of motion, and a reduced incidence of deep vein thrombosis and pulmonary infection compared with later ambulation.(6) These findings have been echoed in single-institution cohort studies; Yakkanti and colleagues reported that patients mobilized on the day of surgery had significantly shorter length of stay and were more frequently discharged directly home rather than to a rehabilitation facility, compared with those mobilized on postoperative day one.(7)

Beyond length of stay, early mobilization appears to confer measurable functional advantages. Within ERAS frameworks, studies in elderly TKA populations have demonstrated that early-mobilized patients achieve significantly lower visual analogue pain scores and superior Knee Society Scores and range of motion in the immediate postoperative period, without any increase in short-term mortality or major complications.(8) The physiological rationale for these benefits is well established: prolonged bed rest is associated with increased insulin resistance, disuse myopathy, impaired pulmonary function, reduced tissue oxygenation, and heightened thromboembolic risk, all of which can be mitigated through prompt, safe ambulation supported by adequate analgesia.(9).

Despite this accumulating evidence, considerable variability persists in clinical practice regarding the precise timing, intensity, and supervision of early postoperative mobilization, and the proportion of patients who are actually mobilized within the first 24 hours after TKA remains surprisingly low at many centres.(10) Much of the existing literature has also focused predominantly on length of stay as the primary outcome, with comparatively fewer prospective studies directly examining the combined trajectory of pain, range of motion, ambulation capacity, and discharge disposition within a single cohort. The present study was therefore undertaken to prospectively evaluate the impact of early mobilization, relative to standard later mobilization, on postoperative pain, functional recovery, length of stay, discharge disposition, and complication rates following primary unilateral TKA.

Study Design and Setting This prospective comparative study was conducted in the Department of Orthopaedics in collaboration with the Department of Physical Medicine and Rehabilitation at a tertiary care teaching hospital over a period of one year. Institutional Ethics Committee approval was obtained prior to commencement, and the study was conducted in accordance with the principles of the Declaration of Helsinki. Written informed consent was obtained from all participants prior to enrolment. Study Population A total of 150 patients undergoing primary unilateral TKA for osteoarthritis were enrolled using consecutive sampling and allocated to either an early mobilization group (n = 75) or a standard mobilization group (n = 75), based on time of surgery, ward admission timing, and physiotherapy resource availability on the day of operation. Inclusion criteria comprised patients aged 45 to 80 years undergoing elective primary unilateral TKA for primary osteoarthritis, with the ability to ambulate independently prior to surgery. Exclusion criteria included revision arthroplasty, bilateral simultaneous TKA, inflammatory arthropathy, significant pre-existing neurological or cardiopulmonary disease limiting mobilization, intraoperative complications requiring deviation from standard protocol, and patients unable to comply with the structured physiotherapy schedule. Intervention Protocols All patients received a standardized surgical technique under spinal or general anaesthesia, with comparable multimodal analgesia comprising periarticular local infiltration, scheduled paracetamol, and supplementary opioids as required. Patients in the early mobilization group were assisted to sit out of bed and ambulate with a walker under physiotherapist supervision within 24 hours of surgery, typically within 6 to 12 hours postoperatively once haemodynamically stable and adequately analgised. Patients in the standard mobilization group commenced ambulation after the first 24 postoperative hours, in keeping with conventional ward protocols. Both groups subsequently followed an identical structured physiotherapy regimen, including quadriceps strengthening, active-assisted range-of-motion exercises, and gait training, progressing according to individual tolerance. Outcome Measures and Statistical Analysis Pain was assessed using the 10-point visual analogue scale (VAS) on postoperative days 1 and 3. Knee flexion range of motion (ROM) was measured using a standard goniometer on postoperative day 3 and at six weeks. Ambulation distance was recorded on postoperative day 2. Length of hospital stay, discharge disposition (home versus inpatient rehabilitation facility), Knee Society Score at six weeks, and postoperative complications (deep vein thrombosis, pulmonary infection, nausea/vomiting, surgical site infection, and 30-day readmission) were recorded for all patients. Continuous variables were expressed as mean ± standard deviation and compared using the independent samples t-test; categorical variables were expressed as frequencies and percentages and compared using the chi-square or Fisher's exact test, as appropriate. A two-tailed p-value of less than 0.05 was considered statistically significant. All analyses were performed using standard statistical software.

A total of 150 patients completed the study protocol and follow-up, with 75 patients in each group. Baseline demographic and clinical characteristics were comparable between the two groups, as summarized in Table 1.

Table 1. Baseline demographic and clinical characteristics of the study population

Values are expressed as mean ± standard deviation or number (percentage). ASA = American Society of Anesthesiologists; OA = osteoarthritis; VAS = visual analogue scale; ROM = range of motion. p-values calculated using independent t-test or chi-square test as appropriate.

There were no statistically significant differences between the early and standard mobilization groups with respect to age, sex distribution, body mass index, ASA grade, preoperative diagnosis, baseline pain scores, or preoperative knee range of motion, confirming that the two groups were well matched at baseline and that subsequent differences in outcome could be attributed to the timing of mobilization rather than confounding patient factors.

Postoperative functional outcomes, including pain, range of motion, ambulation distance, and length of stay, are presented in Table 2.

Table 2. Postoperative functional outcomes by mobilization group

Values are expressed as mean ± standard deviation. POD = postoperative day. p-values calculated using independent samples t-test.

Patients mobilized within 24 hours of surgery began ambulating substantially earlier than those in the standard group and demonstrated significantly lower pain scores at both postoperative day 1 and day 3. Knee flexion range of motion was greater in the early mobilization group at both early (day 3) and intermediate (six-week) time points, and these patients walked considerably further by postoperative day 2. Hospital length of stay was nearly two days shorter in the early mobilization group, and functional outcome at six weeks, as measured by the Knee Society Score, was also significantly higher in this group.

Discharge disposition and postoperative complication rates for both groups are summarized in Table 3.

Table 3. Discharge disposition and postoperative complications by mobilization group

Values are expressed as number (percentage). p-values calculated using chi-square or Fisher's exact test as appropriate.

A significantly higher proportion of patients in the early mobilization group were discharged directly home rather than to an inpatient rehabilitation facility. The incidence of postoperative pulmonary infection was significantly lower in the early mobilization group, and although the rate of deep vein thrombosis was numerically lower in this group, the difference did not reach statistical significance. Rates of postoperative nausea/vomiting, superficial surgical site infection, and 30-day readmission were comparable between groups, indicating that early mobilization did not introduce additional surgical risk.

The findings of this study demonstrate that early mobilization within 24 hours of primary TKA confers measurable advantages across multiple domains of postoperative recovery, including reduced pain, improved range of motion, greater ambulation capacity, shorter hospital stay, and a higher likelihood of direct discharge home, without increasing the risk of surgical or thromboembolic complications. These results are consistent with a substantial body of existing literature supporting early mobilization as a core component of enhanced recovery pathways following lower-limb arthroplasty.

The reduction in length of stay observed in our early mobilization group (approximately 1.9 days) closely mirrors the pooled estimate of 1.8 days reported in the meta-analysis of randomized controlled trials by Guerra and colleagues, which examined early mobilization protocols across both hip and knee arthroplasty.(5) Similarly, our finding that early-mobilized patients achieved significantly lower pain scores and greater knee flexion range of motion is in keeping with the large multicentre retrospective study from China, which reported that patients ambulating within 24 hours had significantly lower visual analogue pain scores at 72 hours and superior range-of-motion gains compared with those mobilized later.(6) Our complication data similarly align with this evidence: the lower incidence of pulmonary infection in the early mobilization group reflects a now well-recognized physiological mechanism, whereby early ambulation improves pulmonary ventilation and reduces atelectasis risk relative to prolonged bed rest.(9)

The improvement in discharge disposition observed in our study—with a markedly higher proportion of early-mobilized patients discharged directly home—is consistent with the findings of Yakkanti and colleagues, who reported that patients mobilized on the day of surgery were significantly more likely to be discharged home rather than to a rehabilitation facility compared with those mobilized on postoperative day one.(7) This outcome carries substantial practical and economic significance, as discharge to an inpatient rehabilitation facility is associated with considerably higher downstream healthcare costs and resource utilization than discharge directly home.(11) Our observation that the early mobilization group also achieved a significantly higher six-week Knee Society Score lends further support to the hypothesis that early ambulation may accelerate not only short-term recovery but also intermediate-term functional outcomes, a pattern similarly described in ERAS cohorts of elderly TKA patients, where early-mobilized patients demonstrated superior Knee Society Scores and range of motion without an increase in short-term mortality.(8)

Importantly, our results did not show a significant increase in deep vein thrombosis, surgical site infection, or 30-day readmission in the early mobilization group, reinforcing the safety profile of accelerated postoperative protocols. This finding is consistent with prior reports that early ambulation, by countering the adverse physiological effects of prolonged immobility such as venous stasis and impaired tissue oxygenation, may in fact lower rather than raise thromboembolic risk, although our study was not adequately powered to demonstrate statistical significance for this specific complication.(6,9) It is worth noting, however, that not all studies report uniformly favourable safety differences; some ERAS cohorts have found no significant difference in deep vein thrombosis or pulmonary embolism rates between early and standard mobilization groups despite differences in other outcomes, suggesting that the magnitude of complication-related benefit may vary according to institutional thromboprophylaxis protocols and patient risk profiles.(12).

This study has several limitations. Group allocation was based on ward scheduling and resource availability rather than formal randomization, introducing a potential risk of selection bias despite comparable baseline characteristics between groups. The single-centre design and relatively modest sample size may limit generalizability and statistical power for detecting differences in less common complications such as deep vein thrombosis. Additionally, follow-up was limited to six weeks, precluding assessment of longer-term functional outcomes, patient satisfaction, or implant survivorship. Future multicentre randomized controlled trials with extended follow-up are warranted to confirm these findings and to better define the optimal intensity and supervision requirements of early mobilization protocols across diverse patient populations.

Early mobilization within 24 hours of primary total knee arthroplasty is associated with significantly reduced postoperative pain, improved early and intermediate-term knee range of motion, greater ambulation capacity, shorter hospital length of stay, and a higher rate of direct discharge to home, without a corresponding increase in surgical or thromboembolic complications. These findings support the routine incorporation of early mobilization protocols into standard postoperative care pathways following TKA, as part of a broader enhanced recovery framework, to optimize both patient outcomes and the efficient use of hospital resources.

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