• Vol. 42 No. 8, 388–394
  • 15 August 2013

Clinical Outcomes of Below Knee Amputations in Diabetic Foot Patients



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Introduction: This study aims to evaluate the predictive factors affecting the clinical outcome of Below Knee Amputations (BKA) performed in diabetic foot patients admitted to National University Hospital (NUH) Multi-Disciplinary Diabetic Foot Team.

Materials and Methods: This is a prospective cohort study of 151 patients admitted to the Department of Orthopaedic Surgery, NUH, for Diabetic Foot Problems (DFP) from January 2006 to January 2010. All had undergone BKA performed by NUH Multi-Disciplinary Diabetic Foot Team. Statistical analyses (univariate and multivariate analysis with logistic regression) were carried out using SPSS version 18.0, for factors such as demographic data, diabetic duration and control, clinical findings and investigations, indications for surgery, preoperative investigations and evaluation, microbiological cultures, and these were compared to the clinical outcome of the patient. A good clinical outcome is defined as one not requiring proximal re-amputation and whose stump healed well within 6 months. The ability to ambulate with successful use of a prosthesis after 1 year was documented. Statistical significance was set at P <0.050.

Results: Mean age of study population was 55.2 years with a male to female ratio of about 3:2. Mean follow up duration was 36 months. Of BKAs, 73.5% gave a good outcome. Univariate analysis showed that smoking, previous limb surgery secondary to diabetes, high Total White Count (TW), Erythrocyte Sedimentation Rate (ESR), C-Reactive Protein (CRP), Urea, Creatinine (Cr), Neutrophils, absence of posterior tibial and popliteal pulses, low Ankle Brachial Index (ABI) and Toe Brachial Index (TBI) were associated with poor clinical outcome. Multivariate analysis showed that high CRP, ESR, Neutrophils, absence of popliteal pulse and low ABI were associated with poor clinical outcome. Of patients, 50.3% attained mobility with prosthesis after 1 year. Mortality rate was 21.2% within 6 months of operation, with sepsis being the most significant cause of death.

Conclusion: Success rate of BKA was 73.5%, with mortality rate being 21.2% within 6 months. In this cohort, 50.3% were able to attain eventual mobility with prosthesis after 1 year. Sepsis was the most significant cause of death. Markers of infection such as high CRP, ESR, neutrophils; and indicators of poor vascularity such as absence of popliteal pulse and low ABI were significantly associated with poor clinical outcome.

Diabetes currently affects 366 million people worldwide or 8.3% of the world’s adult population. This figure is expected to increase to 9.9% by 2030, owing to environmental factors such as sedentary lifestyles and changing dietary patterns. Every year, more than 1 million people undergo a lower-limb amputation as a consequence of diabetes, which calculates to a limb lost to diabetes in the world every 30 seconds. Singapore has one of the highest prevalence of diabetes in the developed world, with 11.3% of residents aged between 18 and 69 years old living with diabetes in 2010. It is one of the top 10 causes of death locally. Diabetic foot complications accounts for almost 700 amputations annually in Singapore.

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