What are the most common complications after a Below-Knee Amputation (BKA)?

Most Common Complications After Below-Knee Amputation (BKA)

Wound complications are the most prevalent issue after BKA, occurring in approximately 10.4% of cases, followed by infection (31.3% in some series), with unplanned reoperation required in 9.6% of patients within 30 days. 1, 2, 3

Primary Complications by Frequency

Wound-Related Complications (Most Common)

• Wound occurrences affect 10.4% of BKA patients, defined as superficial infection, deep infection, and/or wound disruption 1
• Infection is the single most common wound complication at 31.3%, representing the leading cause of surgical morbidity 3
• Wound dehiscence occurs frequently enough to require debridement/secondary closure in 25.6% of unplanned reoperations 2
• Elevated INR significantly increases wound complications (OR 1.5 for every integral increase), making coagulopathy correction critical pre-operatively 1

Reoperation Requirements

• Unplanned reoperation occurs in 9.63% of BKA patients within 30 days 2
• The most common reasons for reoperation are:
  • Conversion to above-knee amputation (28.7% of reoperations) 2
  • Debridement or secondary closure (25.6% of reoperations) 2
  • Revision leg amputation at the same level (10.3% of reoperations) 2

Hospital Readmission

• Unplanned and procedure-related readmissions occur in 8.75% of patients within 30 days 2

Major vs Minor Complications

• Major complications affect 12.8% of BKA patients 2
• Minor complications affect 8.7% of BKA patients 2

Mortality

• 30-day mortality rate is 5.14% for BKA patients 2
• Medical comorbidities predicting mortality include history of MI (OR 1.8), CHF (OR 1.6), and COPD (OR 1.6) 1

High-Risk Patient Factors

Modifiable Risk Factors

• Current/recent smoking status increases wound complications (OR 1.34 for reoperation, OR 1.8 for wound occurrence in AKA) 1, 2
• Elevated INR is the strongest modifiable predictor for BKA wound complications (OR 1.5 per unit increase) 1
• Bleeding disorders increase reoperation risk (OR 1.30) 2

Non-Modifiable Risk Factors

• Patients transferred from another facility have higher reoperation rates (OR 1.28) 2
• Preoperative ventilator dependence dramatically increases reoperation risk (OR 2.38) 2
• Younger age (50-59 years) paradoxically predicts more wound occurrences compared to older patients (OR 1.9) 1

Delayed Complications

Stump Maturation Issues

• Residual limb edema typically resolves by week 5-6, but delayed healing extends time to prosthetic fitting 4
• Median time to prosthetic referral ranges from 73 days (with aggressive management) to 247 days (standard care) for complicated cases 5

Fall-Related Trauma

• Falls are common and potentially catastrophic, causing lacerations, fractures, and wound dehiscence requiring revision surgery 4
• Lower limb amputees represent the highest-risk hospitalized population for falls (20.6% incidence) 4

Clinical Pitfalls to Avoid

Critical pre-operative optimization: Normalize INR before surgery, as this is the single strongest modifiable predictor of wound complications in BKA patients 1. Patients with coagulopathy should have this corrected aggressively.

Smoking cessation is non-negotiable: Current smokers have 34% increased reoperation risk and should be counseled on immediate cessation 2.

Peripheral arterial disease (PAD) patients require special consideration: All patients progressing to above-knee amputation in one series had PAD, while none without PAD required conversion, suggesting PAD patients may benefit from primary AKA in selected cases 5.

Early aggressive management of stump complications: When major stump complications occur (operative infection or dehiscence), staged operative debridement with negative pressure wound therapy achieves 100% BKA salvage in non-PAD patients, compared to 73.7% with standard care 5.