What are the risks and benefits of bilateral above knee (BAK) amputations?

Risks and Benefits of Bilateral Above Knee Amputations

Bilateral above knee amputations (BAK) should be considered only when limb preservation is not feasible, as they are associated with significantly poorer functional outcomes and higher mortality rates compared to more distal amputation levels.

Decision-Making Process

• Amputation decisions should be made by a multidisciplinary care team that assesses the most distal level of amputation that can facilitate healing and provide maximal functional ability 1
• Primary amputation is indicated when life over limb is the prevailing consideration and the threatened limb is causing patient instability (e.g., ischemia, metabolic derangement, advanced infection) 1
• Patient-centered approach using objective classification of limb threat, patient risk, anatomic disease pattern, and patient/family goals should guide decision-making 1

Benefits of Bilateral Above Knee Amputations

• Definitive treatment for life-threatening conditions when limb preservation is not possible 1
• May be necessary when primary amputation is indicated due to:
  • Extensive tissue loss making skin coverage impossible 1
  • Proven section of critical nerves 1
  • Multiple fractures with bone loss or ischemic vascular lesions 1
  • Life-threatening sepsis due to foot infection 1

Risks and Complications

Mortality

• Extremely high mortality rates compared to more distal amputations 2
• Two-year mortality rate for above-knee amputations can reach 28.3% compared to 3.8% for knee arthrodesis in cases of periprosthetic joint infection 3
• Risk factors for mortality include:
  • Dementia (HR 2.769) 2
  • Non-ambulatory status preoperatively (HR 2.281) 2
  • Heart failure (HR 2.013) 2
  • Renal failure (HR 1.87) 2
  • Advanced age 3

Functional Outcomes

• Extremely poor rehabilitation potential for bilateral above-knee amputees, especially those with vascular disease 4
• Historical data shows that of 38 bilateral above-knee amputees, only 2 with traumatic amputation achieved prosthetic rehabilitation, while none of the 35 with dysvascular amputation were successfully rehabilitated 4
• Most dysvascular bilateral above-knee amputees become wheelchair-dependent (58%) or bedridden (34%) 4

Quality of Life Factors

• Factors associated with lower quality of life after amputation include:
  • Age >65 years 1
  • Presence of diabetes 1
  • Being homebound/isolation 1
• Factors associated with higher quality of life include:
  • Walking with prosthesis (rarely achieved with bilateral above-knee amputations) 1
  • Female sex (especially if age <60 years) 1
  • Living at home 1

Other Complications

• Higher reoperation rates (37.0%) compared to more conservative procedures like knee arthrodesis (11.5%) 3
• Resistant bacterial infections are associated with high rates of reoperation (HR 3.083) 2
• Neuropathic pain is common (reported in approximately 40% of patients after above-knee amputation) 3
• Long-term loss of mobility can lead to:
  • Negative psychological health impacts 1
  • Deterioration of physical health 1
  • Socio-economic challenges due to social isolation and loss of work 1
  • Negative effects on glucose control and cardiovascular risk factors 1

Importance of Knee Preservation

• Preserving even a single knee joint dramatically improves rehabilitation outcomes 4
• Success rates for prosthetic rehabilitation by amputation level:
  • Bilateral above-knee: near 0% for vascular patients, limited success for traumatic amputees 4
  • Combined above-knee and below-knee: approximately 24% rehabilitation rate 4
  • Bilateral below-knee: approximately 80% rehabilitation rate 4

Key Considerations for Clinical Practice

• When amputation is necessary, always aim for the most distal level possible that will heal 1
• The significance of preserving the knee joint, even a single knee, cannot be overemphasized 4
• For dysvascular bilateral above-knee amputees, wheelchair ambulation should be the expected outcome rather than prosthetic rehabilitation 4
• Professional-controlled factors that influence outcomes include:
  • Timing of amputation 1
  • Informed decision-making 1
  • Post-amputation support 1

Pitfalls to Avoid

• Performing bilateral above-knee amputations when more distal amputations might be feasible 4
• Failing to involve a multidisciplinary team in the decision-making process 1
• Setting unrealistic expectations for prosthetic rehabilitation in dysvascular bilateral above-knee amputees 4
• Underestimating the mortality risk, especially in older patients with comorbidities 2, 3