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Surgical site infection and transfusion rates are higher in underweight total knee arthroplasty patients
Jorge Manrique1, Antonia F Chen1, Miguel M Gomez1
1Rothman Institute at Thomas Jefferson University, Philadelphia, PA, USA.
Insights
Underweight total knee arthroplasty (TKA) patients face higher risks of surgical site infections (SSIs) and require more blood transfusions. Further research is recommended to explore preventative strategies for this vulnerable patient group.
Area of Science:
- Orthopedic Surgery
- Arthroplasty Research
- Patient Outcomes
Background:
- Underweight (UW) patients undergoing total hip arthroplasty report increased complications like infection and transfusion.
- Limited data exists on UW patients undergoing total knee arthroplasty (TKA).
- This study investigates complication risks, specifically infection and transfusion, in UW TKA patients.
Purpose of the Study:
- To determine if underweight TKA patients have a higher risk of complications.
- To compare infection and transfusion rates between UW and normal weight TKA patients.
- To identify potential factors contributing to increased complications in UW TKA patients.
Main Methods:
- A case-control study utilized a prospectively collected institutional database.
- Twenty-seven UW TKA patients (BMI < 18.5 kg/m²) were matched with 81 normal weight TKA patients (BMI 18.5-24 kg/m²).
- Demographic variables and various complications including surgical site infection (SSI) and transfusion requirements were compared.
Main Results:
- UW TKA patients had a significantly higher incidence of SSIs (11.1% vs 0.0%).
- UW TKA patients were more likely to require blood transfusions (OR = 3.4).
- The average BMI for UW patients was 17.1 kg/m² compared to 23.0 kg/m² for normal weight patients.
Conclusions:
- Underweight TKA patients demonstrate an increased likelihood of developing SSIs and requiring transfusions.
- Potential contributing factors include impaired wound healing and low preoperative hemoglobin levels.
- Prospective studies investigating tissue coverage and hematologic status are recommended to mitigate SSI risk in UW TKA patients.
Background:
Underweight (UW) patients undergoing total hip arthroplasty have exhibited higher complication rates, including infection and transfusion. No study to our knowledge has evaluated UW total knee arthroplasty (TKA) patients. We, therefore, conducted a study to investigate if these patients are at increased risk for complications, including infection and transfusion.
Methods:
A case-control study was conducted using a prospectively collected institutional database. Twenty-seven TKA patients were identified as UW (body mass index [BMI] < 18.5 kg/m2) from 2000-2012 and were matched for age, gender, date of surgery, age-adjusted Charlson comorbidity index, rheumatoid arthritis, and diabetes. These patients were compared to 81 normal weight patients (BMI 18.5-24 kg/m2). Demographic variables were compared, along with wound complications, surgical site infection (SSI), blistering, deep vein thrombosis, pulmonary embolism, transfusion, revision, flexion contracture, hematoma formation, and patellar clunk.
Results:
The average BMI was 17.1 kg/m2 (range 12.8-18.4) for UW and 23.0 kg/m2 (range 19.0-25.0) for normal weight patients (P < .001). UW TKA patients were more likely to develop SSIs (3/27, 11.1% vs 0/81, 0.0%, P = .01) and were more likely to require transfusions (odds ratio = 3.4, confidence interval 1.3-9.1; P = .02).
Conclusions:
Our study demonstrates that UW TKA patients have a higher likelihood of developing SSI and requiring blood transfusions. The specific reasons are unclear, but we conjecture that it may be related to decreased wound healing capabilities and low preoperative hemoglobin. Investigation of local tissue coverage and hematologic status may be beneficial in this patient population to prevent SSI. Based on the results of this study, a prospective evaluation of these factors should be undertaken.