Chronic Obstructive Pulmonary Disease (COPD) is a progressive lung condition characterized by persistent respiratory symptoms and airflow limitation, which significantly affects physical functioning and overall quality of life (1). As the global population ages, the prevalence of both COPD and degenerative joint diseases like osteoarthritis is rising. This has led to an increasing number of COPD patients requiring total hip arthroplasty (THA) or total knee arthroplasty (TKA) to restore mobility and relieve joint pain (2). While arthroplasty has proven benefits in improving joint function and reducing pain, the perioperative and postoperative recovery in patients with comorbid COPD presents unique challenges due to impaired pulmonary reserve, increased risk of respiratory complications, and reduced exercise tolerance (3).

Several studies have investigated the impact of comorbidities on outcomes after joint arthroplasty. However, only a limited number have focused specifically on COPD as an independent risk factor. Liao and Lu (2016) reported increased rates of postoperative complications, longer hospital stays, and higher mortality among arthroplasty patients with COPD (4). Similarly, Crisafulli et al. (2023) highlighted that COPD is associated with delayed functional recovery and poorer rehabilitation outcomes following orthopedic surgeries (5). Despite these findings, there remains a paucity of research examining the long-term functional outcomes and quality of recovery in COPD patients undergoing THA or TKA, especially in terms of pulmonary function status and its influence on physical rehabilitation trajectories.

This research gap is important to address because COPD may not only influence perioperative complications but also limit postoperative mobility and engagement in rehabilitation programs, ultimately affecting surgical success and patient independence. While early mobilization and pulmonary rehabilitation have been suggested to improve outcomes in COPD patients undergoing non-pulmonary surgeries (6), their specific role in the context of joint arthroplasty remains underexplored.

The present study aims to evaluate the functional recovery outcomes in COPD patients undergoing hip or knee arthroplasty and to determine how baseline pulmonary function affects postoperative mobility, rehabilitation participation, and overall recovery. It also seeks to identify whether stratifying patients based on their pulmonary status can guide perioperative planning and improve surgical outcomes.

This prospective observational study was conducted jointly by the Departments of Pulmonary Medicine and Orthopaedics at [Name of Institution], over a period of 12 months. The study was approved by the Institutional Ethics Committee, and written informed consent was obtained from all participants prior to enrollment.

Study Population:

A total of 50 patients diagnosed with Chronic Obstructive Pulmonary Disease (COPD), as per GOLD (Global Initiative for Chronic Obstructive Lung Disease) criteria, and scheduled to undergo total hip arthroplasty (THA) or total knee arthroplasty (TKA), were included in the study. Patients were recruited from the inpatient services of the orthopaedics department. COPD diagnosis and classification were confirmed through spirometry (post-bronchodilator FEV₁/FVC < 0.70).

Inclusion Criteria:

• Patients aged 45 years and above
• Confirmed diagnosis of COPD (any GOLD stage)
• Scheduled for elective THA or TKA
• Able to provide informed consent and comply with follow-up protocol

Exclusion Criteria:

• Patients with acute exacerbation of COPD within 6 weeks prior to surgery
• Known neuromuscular disorders affecting mobility
• Cognitive impairment affecting ability to participate in assessments
• Revision arthroplasty or surgery for fracture

Baseline Assessment:

At enrollment, demographic data (age, sex), smoking history, comorbidities, and COPD severity were recorded. Baseline pulmonary function tests were performed using spirometry (recording FEV₁, FVC, and FEV₁/FVC ratios). The Modified Medical Research Council (mMRC) dyspnea scale and COPD Assessment Test (CAT) scores were documented. Preoperative functional status was assessed using the 6-Minute Walk Test (6MWT) and the Barthel Index.

Surgical and Perioperative Care:

All patients underwent standardized perioperative care and rehabilitation protocols under the supervision of orthopaedic and anaesthesia teams. The choice of anaesthesia (regional or general) was based on clinical suitability. Respiratory care included chest physiotherapy, incentive spirometry, and bronchodilator therapy when required.

Postoperative Assessments:

Postoperative outcomes were assessed at discharge and again at 6 weeks and 3 months follow-up. These included:

• Pulmonary complications (e.g., pneumonia, need for ventilatory support)
• Duration of hospital stay
• Time to mobilization (first assisted ambulation)
• Functional recovery using 6MWT and Barthel Index
• Rehabilitation participation and completion rates

Statistical Analysis:

Data were analyzed using SPSS version XX. Continuous variables were expressed as mean ± standard deviation, while categorical variables were expressed as frequencies and percentages. Pearson or Spearman correlation was used to assess relationships between baseline FEV₁ and functional recovery parameters. A p-value <0.05 was considered statistically significant.

Table 1: Demographic and Clinical Profile of COPD Patients Undergoing Hip or Knee Arthroplasty

The study included 50 patients with a mean age of 66.2 ± 7.47 years, indicating that the population largely consisted of older adults commonly affected by both COPD and joint degeneration. The majority were male (64%), and a significant portion had a history of smoking, with a mean pack-year history of 29.5 ± 9.5, reflecting a known risk factor for COPD. Comorbid conditions were prevalent: 38% had hypertension, 30% had diabetes mellitus, and 22% had ischemic heart disease (IHD). These associated comorbidities can potentially influence surgical outcomes and were taken into account during postoperative monitoring and recovery assessments.

Table 2: Six-Minute Walk Test (6MWT) Recovery over Time

The 6-Minute Walk Test (6MWT) showed consistent improvement across the follow-up period. At discharge, the mean walking distance was 248.33 ± 60.77 meters, which increased to 331.31 ± 51.50 meters at 6 weeks and further improved to 374.13 ± 57.88 meters by 3 months. This trend indicates effective functional recovery in COPD patients after joint arthroplasty, highlighting the benefit of early mobilization and structured rehabilitation even in the presence of underlying respiratory limitations (Table 2).

Table 3: Barthel Index Recovery Over Time

The Barthel Index, which assesses independence in daily living activities, showed marked improvement following arthroplasty in COPD patients. At discharge, the mean score was 74.10 ± 10.58, indicating moderate dependence. This improved significantly to 90.51 ± 9.63 at 6 weeks and reached 96.47 ± 10.02 by 3 months, reflecting near-complete functional independence (Table 3).

Table 4: Comparison of Outcomes across COPD Severity Groups Using Kruskal-Wallis Test

The Kruskal-Wallis test was used to compare postoperative outcomes across different COPD severity groups. None of the variables, including functional recovery measures (6MWT and Barthel Index at various time points) and hospital stay, showed statistically significant differences (p > 0.05). This indicates that despite varying levels of baseline airflow obstruction, the recovery trajectory and hospital metrics did not significantly differ, suggesting effective recovery is achievable with standard postoperative care across all COPD severities (Table 4).

Table 5: Pearson’s Correlation Analysis of Pulmonary Function and Postoperative Outcomes

Pearson’s correlation analysis showed weak and statistically non-significant associations between pulmonary function and postoperative recovery metrics. There was no meaningful correlation between FEV₁% and 6MWT distance (r = –0.03) or Barthel Index (r = 0.08) at 3 months. Similarly, the CAT score showed only a slight, non-significant positive correlation with hospital stay duration (r = 0.11). These results suggest that while COPD is an important comorbidity, baseline pulmonary function alone may not strongly influence short-term functional outcomes following hip or knee arthroplasty (Table 5).

The present study aimed to assess the functional outcomes in COPD patients undergoing hip or knee arthroplasty, with a focus on the influence of baseline pulmonary function on postoperative recovery. The study evaluated various parameters, including pulmonary complications, hospital stay duration, functional recovery through 6-Minute Walk Test (6MWT) and Barthel Index, and participation in rehabilitation over a 3-month follow-up.

In this cohort of 50 patients with confirmed COPD, most belonged to the moderate and severe GOLD stages, with a mean FEV₁% predicted of approximately 51%. Functional recovery improved progressively from discharge to 3 months, as reflected by increasing 6MWT distances and Barthel Index scores over time. However, statistical analysis using the Kruskal-Wallis test revealed no significant differences in functional outcomes across COPD severity groups (p > 0.05). This suggests that while recovery occurred in all groups, baseline severity of airflow limitation did not independently affect short-term functional gains following arthroplasty (7, 8).

Pearson’s correlation analysis showed weak and statistically insignificant relationships between FEV₁% and both 6MWT distance (r = –0.03, p = 0.8223) and Barthel Index (r = 0.08, p = 0.5670) at 3 months. Similarly, CAT score did not show a strong correlation with hospital stay (r = 0.11, p = 0.4407). These findings align with prior reports indicating that COPD may be a general risk factor for postoperative complications, but its impact on functional recovery is likely modulated by other factors such as age, nutritional status, preoperative mobility, and rehabilitation adherence (9,10).

Our findings partially contrast with studies such as Shin et al. (2022), who reported that COPD significantly influenced postoperative complications and length of stay in patients undergoing total joint arthroplasty (11). In their large-scale retrospective analysis, COPD patients experienced higher rates of respiratory failure and prolonged hospitalization. However, those studies did not specifically measure functional recovery metrics like 6MWT or Barthel Index, which are more sensitive to mobility and independence outcomes. Furthermore, Cha et al. (2019) observed delayed recovery and lower independence scores in COPD patients following hip fracture surgery, emphasizing the need for tailored perioperative care in this population (12,13).

Interestingly, a key strength of this study is its focus on structured postoperative follow-up using standardized functional measures, which are often lacking in broader database studies. Despite the lack of statistically significant associations, the overall improvement in functional scores suggests that well-structured rehabilitation can help COPD patients recover post-arthroplasty similarly to non-COPD individuals, provided their condition is stable and well-managed.

In conclusion, this study demonstrates that COPD patients undergoing hip or knee arthroplasty experience functional improvements over time, regardless of the baseline severity of airflow limitation. While no strong correlations were found between FEV₁% and recovery measures, the data shows the importance of individualized rehabilitation protocols and multidisciplinary perioperative management. Future studies with larger samples and longer follow-up periods are warranted to further delineate the role of pulmonary status in long-term outcomes post-arthroplasty.

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