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Below Knee Amputation

- See:
      - BKA Prosthesis 
      - Amputations in the Diabetic Patient
      - Pediatric BKA:

- Discussion:
    - length considerations:
         - ideal bone length is between 12 to 17 cm as measured from the medial joint line;
         - in stumps less than 9 cm, consider removing the entire fibula along w/ some muscle bulk;
         - when stump measures less than less than 5 cm, function is comprimised, therefore consider amputation at next higher level (knee disarticulation or AKA);
    - gait and energy adaptions:
         - average BK amputee expends about 40% more kcal/min than non amputees to maintain a normal gait;
         - since the average BK amputee walks 36% slower, the average rate of oxygen consumption may remain unchanged;
         - note, however, the net oxygen demand will increase since the total amount of work to walk a given distance will increase;
         - references:
                - Below knee amputation and rehabilitation of amputees.
                - Gait kinematics in below-knee child amputees: a force plate analysis.
    - vascular considerations: (anastomoses of lower limb arteries)
         - dominant supply of the skin at this level is provided by the arteries that run w/ the saphenous nerve and the sural nerve (ie sural artery);
         - references:
                - Fasciocutaneous blood supply in below-knee amputation.
                - Anatomical aspects of the blood supply to the skin of the posterior calf: technique of below-knee amputation.
                - The blood supply to the skin of the leg: a post-mortem investigation.
                - Segmental transcutaneous measurements of PO2 in patients requiring below-the-knee amputation for peripheral vascular insufficiency.
                - Cutaneous blood flow and its relation to healing of below knee amputation.
                - Muscle blood flow after amputation. Increased flow with medullary plugging.
                - The below-the-knee amputation for vascular disease.
                - Functional outcome of below-knee amputation in peripheral vascular insufficiency. A multicenter review.
                - Noninvasive determination of healing of major lower extremity amputation: the continued role of clinical judgment.
                - An index of healing in below-knee amputation: leg blood pressure by Doppler ultrasound

    - Diabetic Foot - Treatment Considerations 
           - 5-7 year mortality rate after BKA is greater than 50%;
    - indications for BKA w/ chronic foot and ankle pain:
         - in the report by Honkamp et al, the authors assessed the outcome of below-the-knee amputations performed to relieve intractable foot and ankle pain;
         - patients with diabetes mellitus, peripheral vascular occlusive disease, or peripheral neuropathy were excluded;
         - 20 patients met the inclusion criteria, and 18 completed the study;
         - when asked whether they would have the BKA done again under similar circumstances, 16 patients said yes, one was unsure, and one said no;
         - same distribution was observed when patients were asked if they were satisfied with the outcome: - 16 said yes, one was unsure, and one said no;
         - after the amputation, the patients reported a decrease in both pain frequency and pain intensity;
         - 10 patients discontinued the use of narcotics, and seven decreased the level and/or dosage;
         - 3 patients worked before the amputation, and eight worked after the amputation;
         - average walking distance increased from 0.3 to 0.8 mile (p = 0.0034).
         - ref: Retrospective Review of Eighteen Patients Who Underwent Transtibial Amputation for Intractable Pain
    - considerations with gangrene and infection: (debridment of muscle)
         - references:
                   - Lower extremity amputation: open versus closed.
                   - One-stage versus two-stage amputation for wet gangrene of the lower extremity: a randomized study.
                   - Simplified two-stage below-knee amputation for unsalvageable diabetic foot infections.
                   - Staged below-knee amputations for septic peripheral lesions due to ischaemia.
                   - Guillotine amputation in the treatment of nonsalvageable lower-extremity infections.
                   - Primary closure of below-knee amputation stumps: a prospective study of sixty-two cases.
                   - Below knee amputation in war surgery: a review of 111 amputations with delayed primary closure.
                   - Below-knee amputation for ischaemic gangrene. Prospective, randomized comparison of a transverse and a sagittal operative technique

 - Technical Considerations:
    - posterior flap technique: 
    - osteomyoplastic technique:
           - Osteomyoplastic and Traditional Transtibial Amputations in the Trauma Patient: Perioperative Comparisons and Outcomes    
    - skew flap:
           - level of bone section about 10-15 cm below the tibial plateau
           - shortest level that can be accepted allows 3 cm of stump below the flexor tendons when the knee is 90 deg flexed
           - point is drawn on the skin 2.5 cm lateral to the subcutaneous crest of tibia & this is point of anterior insection of two flaps;
           - use a measuring tape to mark the posterior flap;
           - long and short saphenous veins are identified and ligated;
           - saphenous nerve and sural nerve are carefully separated, pulled down & divided under tension so that they will not be incorporated into ligatures securing the veins;
           - references:
                  - Long posterior flap versus equal sagittal flaps in below-knee amputation for ischaemia.
                  - Skewflap versus long posterior flap in below-knee amputations: multicenter trial.
                  - Experience with the 'skew flap' below-knee amputation.
                  - A rationale for skew flaps in below-knee amputation surgery.
                  - Sagittal flaps in below-knee amputations in Chinese patients.
                  - Below-knee amputation using the sagittal technique: a comparison with the coronal amputation

Operative Complications of Combat-Related Transtibial Amputations: A Comparison of the Modified Burgess and Modified Ertl Tibiofibular Synostosis Techniques

Below-knee amputation: a modern approach

A prospective study of lower limb amputations.

Doppler-determined segmental pressures and wound-healing in amputations for vascular disease.

Improved results with diabetic below-knee amputations.

Lower extremity amputation: the control series.

Iatrogenic tibial pseudoaneurysm following below-knee amputation.

Myodermal flap closure of below the knee amputation.

Wedge resection of amputation stumps. A valuable salvage procedure.