Total Knee Replacement (TKR) is one of the most successful orthopedic procedures for relieving pain, correcting deformity, and restoring function in patients with advanced knee osteoarthritis. With increasing life expectancy, obesity, and sedentary lifestyles, the prevalence of degenerative knee diseases has risen significantly, leading to a growing demand for TKR worldwide. The procedure provides substantial improvements in mobility, quality of life, and functional outcomes in patients suffering from end-stage knee arthritis.^[1]

Despite excellent long-term outcomes, several patient-related factors influence postoperative recovery and implant survival, among which diabetes mellitus is considered one of the most important comorbid conditions. Diabetes mellitus is a chronic metabolic disorder characterized by hyperglycemia resulting from defects in insulin secretion, insulin action, or both. The global burden of diabetes has increased dramatically, particularly in developing countries such as India, where a large proportion of patients undergoing TKR are diabetic. Diabetes has been associated with impaired wound healing, increased susceptibility to infections, delayed rehabilitation, and higher rates of postoperative complications.^[2]

Hyperglycemia adversely affects immune function, microvascular circulation, and collagen synthesis, thereby potentially influencing surgical outcomes following joint replacement procedures. Several studies have reported that diabetic patients undergoing TKR may experience higher rates of surgical site infection, periprosthetic joint infection, prolonged hospital stay, thromboembolic events, and poorer functional recovery compared with non-diabetic patients. However, other studies have demonstrated comparable functional outcomes when diabetes is adequately controlled perioperatively.^[3]

The relationship between diabetes and postoperative outcomes remains controversial due to variations in glycemic control, duration of diabetes, presence of diabetic complications, and differences in study populations. Assessment of clinical outcomes following TKR commonly includes evaluation of pain relief, range of motion, functional scores such as the Knee Society Score (KSS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), postoperative complications, length of hospital stay, and patient satisfaction. Understanding the impact of diabetes on these outcomes is important for risk stratification, preoperative counseling, optimization of glycemic control, and formulation of perioperative management strategies.^[4]

Comparative evaluation of diabetic and non-diabetic patients undergoing TKR can help identify differences in recovery patterns and complication rates, thereby assisting surgeons in improving patient selection and postoperative care. Therefore, the present study was undertaken to compare the clinical outcomes of diabetic and non-diabetic patients undergoing total knee replacement and to evaluate the influence of diabetes on postoperative recovery and complications.^[5]

AIM

To compare the clinical outcomes of diabetic and non-diabetic patients undergoing total knee replacement.

OBJECTIVES

1. To compare postoperative functional outcomes between diabetic and non-diabetic patients undergoing total knee replacement.
2. To assess and compare the incidence of postoperative complications in diabetic and non-diabetic patients undergoing total knee replacement.
3. To evaluate the effect of diabetes mellitus on recovery parameters such as pain relief, range of motion, and duration of hospital stay following total knee replacement.

Source of Data Data were collected from patients undergoing primary total knee replacement surgery in the Department of Orthopaedics of the study institution. Clinical records, preoperative assessments, operative notes, and postoperative follow-up data were reviewed and documented in a structured case record form. Study Design The study was conducted as a hospital-based comparative observational study. Study Location The study was carried out in the Department of Orthopaedics at a tertiary care teaching hospital. Study Duration The study was conducted over a period of 18 months, including patient recruitment, surgery, follow-up, data collection, and statistical analysis. Sample Size A total of 120 patients undergoing total knee replacement were included in the study. • Group A (Diabetic patients): 60 patients • Group B (Non-diabetic patients): 60 patients Inclusion Criteria 1. Patients aged ≥40 years undergoing primary total knee replacement. 2. Patients diagnosed with advanced osteoarthritis of the knee requiring TKR. 3. Patients willing to participate and provide written informed consent. 4. Patients with documented diabetic status (diabetic or non-diabetic). 5. Patients available for postoperative follow-up assessment. Exclusion Criteria 1. Revision total knee replacement surgeries. 2. Patients undergoing TKR for inflammatory arthritis, malignancy, or traumatic indications. 3. Patients with active local or systemic infection. 4. Patients with severe peripheral vascular disease. 5. Patients with chronic immunosuppressive disorders. 6. Patients with incomplete medical records. 7. Patients lost to follow-up during the study period. Procedure and Methodology After obtaining approval from the Institutional Ethics Committee, eligible patients fulfilling the inclusion criteria were enrolled in the study. Written informed consent was obtained from all participants. A detailed clinical history was recorded, including age, sex, body mass index, duration of symptoms, comorbidities, diabetic status, duration of diabetes, medications, and glycemic control parameters. Patients were categorized into two groups: • Group A: Diabetic patients • Group B: Non-diabetic patients Preoperative evaluation included routine hematological investigations, blood sugar profile, HbA1c levels (for diabetic patients), renal function tests, liver function tests, electrocardiography, and radiographic assessment of the affected knee. All patients underwent primary total knee replacement using standard surgical techniques performed by experienced orthopedic surgeons. Perioperative antibiotic prophylaxis, thromboprophylaxis, anesthesia protocols, and rehabilitation regimens were standardized according to institutional guidelines. Postoperative assessments were performed during hospital stay and follow-up visits at 6 weeks, 3 months, and 6 months. Clinical outcomes evaluated included: • Pain assessment using Visual Analogue Scale (VAS) • Knee Society Score (KSS) • Range of motion (ROM) • Duration of hospital stay • Time to ambulation • Wound healing status • Postoperative complications (infection, wound complications, deep vein thrombosis, stiffness, re-admission, and revision surgery) All findings were recorded systematically for analysis. Sample Processing Data obtained from patient interviews, clinical examinations, laboratory investigations, operative records, and follow-up visits were entered into a predesigned data collection proforma. The collected data were checked for completeness, accuracy, consistency, and subsequently coded for computerized statistical analysis. Statistical Methods Data were analyzed using Statistical Package for Social Sciences (SPSS) version 25.0. • Continuous variables were expressed as Mean ± Standard Deviation (SD). • Categorical variables were expressed as frequencies and percentages. • Independent Student's t-test was used for comparison of quantitative variables between diabetic and non-diabetic groups. • Chi-square test or Fisher's exact test was applied for categorical variables. • Repeated outcome measures were compared using appropriate parametric or non-parametric tests. • Odds ratios with 95% confidence intervals were calculated where applicable. • A p-value <0.05 was considered statistically significant. Data Collection Data were collected using a structured Case Record Form (CRF) that included: Demographic Variables • Age • Gender • Body Mass Index (BMI) Clinical Variables • Duration of knee symptoms • Side affected • Comorbidities • Diabetic status • Duration of diabetes • HbA1c levels Operative Variables • Type of prosthesis used • Duration of surgery • Intraoperative complications • Blood loss Postoperative Outcome Variables • Visual Analogue Scale (VAS) score • Knee Society Score (KSS) • Range of Motion (ROM) • Duration of hospital stay • Time to ambulation • Wound healing status • Postoperative complications • Requirement of revision surgery • Overall functional outcome at follow-up All collected information was maintained confidentially and utilized solely for research purposes.

Table 1: Baseline characteristics of diabetic and non-diabetic patients undergoing total knee replacement

Table 1 compares the baseline characteristics of diabetic and non-diabetic patients undergoing total knee replacement. The mean age of the study population was 62.3 ± 7.9 years, with no significant difference between diabetic (62.7 ± 7.8 years) and non-diabetic patients (61.9 ± 8.1 years) (p=0.583). Similarly, the mean BMI was comparable between the two groups (28.6 ± 3.7 kg/m² vs. 27.9 ± 3.4 kg/m²; p=0.283). Females constituted the majority of participants (60.0%), and gender distribution did not differ significantly between groups (p=0.709). Bilateral knee involvement was observed in 55.8% of patients and was similarly distributed among diabetic and non-diabetic patients (p=0.852). Hypertension was significantly more prevalent among diabetic patients (60.0%) compared to non-diabetic patients (41.7%) (χ²=4.04, p=0.044), indicating a higher burden of comorbidities in the diabetic group. The duration of symptoms before surgery was slightly longer in diabetic patients (7.9 ± 5.1 years) than in non-diabetic patients (6.8 ± 4.6 years), although this difference was not statistically significant (p=0.217).

Table 2: Comparison of postoperative functional outcomes between diabetic and non-diabetic patients

Table 2 presents the comparison of postoperative functional outcomes between diabetic and non-diabetic patients. Preoperative Knee Society Scores (KSS) were similar in both groups (43.1 ± 8.9 vs. 44.6 ± 8.3; p=0.344), indicating comparable preoperative functional status. At six months after surgery, both groups demonstrated substantial improvement; however, non-diabetic patients achieved significantly higher KSS scores compared to diabetic patients (85.6 ± 8.3 vs. 79.8 ± 9.6; p=0.001). Likewise, preoperative WOMAC scores were comparable between groups (p=0.447), whereas six-month WOMAC scores were significantly lower among non-diabetic patients (26.8 ± 7.6) compared to diabetic patients (32.1 ± 9.1), reflecting better functional recovery and symptom improvement in the non-diabetic group (p=0.001). Excellent functional outcomes were observed more frequently in non-diabetic patients (46.7%) than diabetic patients (31.7%), although the difference did not reach statistical significance (p=0.093). The proportion of patients with good outcomes was similar between groups (p=0.852). Notably, fair or poor functional outcomes were significantly more common among diabetic patients (23.3%) compared to non-diabetic patients (10.0%) (p=0.049). These findings suggest that diabetes adversely affects postoperative functional recovery following total knee replacement.

Table 3: Incidence of postoperative complications among diabetic and non-diabetic patients

Table 3 shows the incidence of postoperative complications in diabetic and non-diabetic patients. Superficial wound infection occurred significantly more frequently in diabetic patients (16.7%) than in non-diabetic patients (5.0%) (p=0.040). Delayed wound healing was also more common among diabetic patients (20.0% vs. 8.3%), although the difference did not achieve statistical significance (p=0.067). Deep infection and deep vein thrombosis were observed more often in diabetic patients; however, these differences were not statistically significant (p=0.171 and p=0.240, respectively). Knee stiffness developed in 18.3% of diabetic patients compared with 6.7% of non-diabetic patients, representing a significant difference (p=0.047). Readmission rates were higher among diabetic patients (11.7% vs. 3.3%), though statistical significance was not reached (p=0.083). Importantly, the overall incidence of any postoperative complication was significantly greater in diabetic patients (38.3%) than in non-diabetic patients (15.0%) (χ²=8.40, p=0.004). These results indicate that diabetes is associated with an increased risk of postoperative complications following total knee replacement.

Table 4: Effect of diabetes on recovery parameters after total knee replacement

Significant at p<0.05. KSS: Knee Society Score; WOMAC: Western Ontario and McMaster Universities Osteoarthritis Index; VAS: Visual Analogue Scale.

Table 4 evaluates the effect of diabetes on postoperative recovery parameters. Preoperative VAS pain scores were comparable between diabetic and non-diabetic patients (8.2 ± 1.1 vs. 8.0 ± 1.3; p=0.365), indicating similar baseline pain severity. At six months postoperatively, non-diabetic patients reported significantly lower pain scores than diabetic patients (2.3 ± 1.1 vs. 3.2 ± 1.4; p<0.001), suggesting superior pain relief. Similarly, the mean range of motion at six months was significantly greater among non-diabetic patients (113.6 ± 11.5°) compared with diabetic patients (105.8 ± 14.1°) (p=0.001). Recovery milestones were also achieved earlier in non-diabetic patients, who ambulated sooner (2.6 ± 1.0 vs. 3.3 ± 1.3 days; p=0.001) and had shorter hospital stays (7.6 ± 2.2 vs. 9.3 ± 2.9 days; p<0.001). Satisfactory pain relief was achieved by a significantly higher proportion of non-diabetic patients (86.7%) compared to diabetic patients (68.3%) (p=0.015). Furthermore, delayed rehabilitation was significantly more common among diabetic patients (28.3%) than non-diabetic patients (11.7%) (p=0.022).

The present study compared clinical outcomes between diabetic and non-diabetic patients undergoing total knee replacement (TKR). Baseline characteristics such as age, BMI, gender distribution, bilateral knee involvement, and duration of symptoms were comparable between the two groups, indicating that the observed postoperative differences were less likely to be influenced by demographic variations. However, hypertension was significantly more common among diabetic patients (60.0% vs. 41.7%, p=0.044), which is consistent with the findings of Loh et al. (2025)[1], who reported that diabetic patients undergoing TKR frequently present with multiple metabolic and cardiovascular comorbidities that may adversely affect surgical recovery and postoperative outcomes. In the present study, preoperative KSS and WOMAC scores were similar in both groups, suggesting comparable baseline functional impairment. However, at six months postoperatively, non-diabetic patients demonstrated significantly better functional outcomes, with higher KSS scores and lower WOMAC scores than diabetic patients. Similar observations were reported by Vaishya et al. (2025)[2], who concluded in a meta-analysis that diabetes negatively affects functional recovery and overall outcomes following TKA. Haddad et al. (2025)[3] also demonstrated that although TKA substantially improves functional status in all patients, individuals with metabolic comorbidities often experience slower recovery and relatively lower postoperative functional gains. The proportion of patients achieving excellent functional outcomes was higher among non-diabetic patients, whereas fair or poor outcomes were significantly more frequent in diabetic patients. These findings support the observations of Hong et al. (2024)[4], who reported that diabetes mellitus adversely influences postoperative rehabilitation and patient-reported outcome measures after TKA. Anneberg et al. (2025)[5] similarly emphasized that diabetic patients have a more complex clinical risk profile that may contribute to inferior functional outcomes and increased postoperative morbidity. With regard to postoperative complications, diabetic patients in the present study experienced significantly higher rates of superficial wound infection, knee stiffness, and overall complications. These findings are in agreement with Shohat et al. (2018)[6], who demonstrated that inadequate glycemic control is strongly associated with increased surgical site infection and periprosthetic joint infection after total joint arthroplasty. The meta-analysis by Vaishya et al. (2025)[2] further reported a substantially increased risk of periprosthetic joint infection, deep vein thrombosis, and hospital readmission among diabetic patients undergoing TKA. Although deep infection and deep vein thrombosis were numerically higher among diabetic patients in the current study, statistical significance was not achieved, possibly due to the relatively small sample size. Nevertheless, similar trends have been reported by Hong et al. (2024)[4], who found that diabetes increased the risk of periprosthetic joint infection, systemic complications, revision procedures, and short-term mortality following TKA. Berkovich et al. (2025)[7] also reported higher infection rates and healthcare utilization among diabetic patients undergoing knee arthroplasty. Recovery parameters in the present study revealed that diabetic patients had significantly higher postoperative pain scores, reduced range of motion, delayed ambulation, longer hospital stay, lower rates of satisfactory pain relief, and delayed rehabilitation. These findings support those of Khan et al. (2026)[8], who highlighted the importance of perioperative glycemic optimization, reporting a steep increase in postoperative complications and delayed recovery when HbA1c levels exceed recommended thresholds. Similarly, Brown et al. (2024)[9] emphasized that meticulous glycemic management is critical for minimizing postoperative complications and enhancing rehabilitation outcomes in diabetic patients undergoing arthroplasty. The prolonged hospital stay observed among diabetic patients in our study is comparable to the findings of Loh et al. (2025)[1], who reported increased readmission rates and postoperative resource utilization in diabetic individuals. Ye et al. (2020)[10] further suggested that fluctuations in perioperative blood glucose levels are associated with poorer postoperative recovery and prolonged hospitalization following orthopedic procedures. Another important aspect highlighted in recent literature is the role of diabetic complications themselves. Kotzur et al. (2025)[11] demonstrated that diabetic neuropathy independently increases the risk of infection, revision surgery, and poor functional outcomes after TKA. Similarly, Palmer et al. (2025)[12] emphasized that poorly controlled diabetes remains an important predictor of adverse outcomes, although HbA1c alone may not completely reflect perioperative risk. Overall, the findings of the present study are consistent with contemporary literature published between 2015 and 2025, demonstrating that diabetes mellitus is associated with inferior functional recovery, increased postoperative complications, delayed rehabilitation, and prolonged hospitalization following total knee replacement. These observations underline the importance of comprehensive preoperative assessment, optimization of glycemic control, and multidisciplinary perioperative management to improve outcomes in diabetic patients undergoing TKR.

Diabetic and non-diabetic patients undergoing total knee replacement had comparable baseline demographic and clinical characteristics except for a higher prevalence of hypertension among diabetic patients. Although both groups demonstrated significant postoperative improvement, non-diabetic patients achieved superior functional outcomes, as evidenced by higher Knee Society Scores, lower WOMAC scores, better pain relief, greater range of motion, and faster rehabilitation. Diabetic patients experienced a significantly higher incidence of postoperative complications, particularly superficial wound infections, knee stiffness, and overall postoperative adverse events. They also required a longer duration of hospitalization and showed delayed recovery milestones. The findings suggest that diabetes mellitus adversely influences postoperative functional recovery and complication rates following total knee replacement. Therefore, meticulous preoperative assessment, optimization of glycemic control, and comprehensive perioperative management are essential to improve surgical outcomes in diabetic patients undergoing total knee replacement.

LIMITATIONS OF THE STUDY

1. The study was conducted at a single tertiary care center, which may limit the generalizability of the findings to other populations.
2. The sample size was relatively modest and may not have been sufficient to detect differences in less common complications.
3. The follow-up period was limited to six months and did not evaluate long-term implant survival or functional outcomes.
4. Variations in the duration of diabetes, glycemic control, and diabetic complications were not analyzed separately.
5. Potential confounding factors such as physical activity level, nutritional status, and socioeconomic factors were not assessed.
6. The observational study design limits the ability to establish a causal relationship between diabetes and postoperative outcomes.
7. Patient-reported outcome measures beyond KSS and WOMAC were not included in the analysis.

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