lecture 31 parekh amputations
TRANSCRIPT
Amputations of the Foot & Ankle
Selene G. Parekh, MD, MBAAssociate Professor of Surgery
Partner, North Carolina Orthopaedic ClinicDepartment of Orthopaedic Surgery
Adjunct Faculty Fuqua Business SchoolDuke University
Durham, NC919.471.9622
http://seleneparekhmd.comTwitter: @seleneparekhmd
Overview
• Introduction/General considerations• Distal Syme’s amputation• Great toe amputation• Lesser toe amputation• Ray resection/partial foot amputation• Transmetatarsal amputation• Chopart’s amputation• Syme’s amputation• Below knee amputation
Amputation
• Admission of failure• Surgical defeat
Amputation
• Positive procedure• First step on road to rehabilitation
Amputation
• Save a marginally viable foot• “Win the battle. Lose the war”
Amputation
• Challenges• Selection of proper level• Maximize function• Surgical technique• Post-operative management• Footwear modifications & prostheses
Causes
1. Diabetes
2. PVD
3. Trauma
4. Chronic infection
5. Tumors
6. Congenital abnormalities
Limb Salvage
• Change in paradigm• Complete amputation• Partial amputation
General Considerations
• Plantigrade painless foot w/ stable healing wounds
General Considerations
• Preservation of greater portion of limb • Must be able to heal w/ stable soft tissue envelope
• More proximal amputation better if it yields more functional result
Wound Closure
• Balance between length of preserved bone & available soft tissue
• Immediate or delayed primary closure• Minimize trauma to wound edges• Palpate stump through flap (no rough edges)• Leave sutures in longer• Drain
Vascular Reconstruction
• Consultation• Bypass• Angioplasty
Determination of Level
• Arterial doppler ultrasound• Best initial screen• Toe pressures
• Most reliable for predicting healing• Normal >40 mmHg
• Transcutaneous oxygen measurements• Cumbersome, time consuming
Nutritional Status
• Predictive of wound healing• Total lymphocyte count > 1500/ul• Serum albumin > 3.5 g/dl• Total protein > 6.2 g/dl• Hgb > 11 g/dl
Specific Amputation Levels
Terminal Syme Amputation
• Terminal amputation of toe & nail
• Indications• Nail deformity• Infection
• Remove enough bone to close s/ tension (1/3-1/2 distal phalanx)
• Remove nail plate
• Include all proximal eponychial fold
Terminal Syme Amputation
• Terminal amputation of toe & nail
• Indications• Nail deformity• Infection
• Remove enough bone to close s/ tension (1/3-1/2 distal phalanx)
• Remove nail plate
• Include all proximal eponychial fold
Great Toe Amputation
• Save base of proximal phalanx (1cm)• Preserve PF & FHB• Preserve WB function of 1st ray• Minimize transfer lesion
• Avoid sesamoid resection, if possible• Complications
• Dehiscence• Varus/claw deformity 2nd toe
Great Toe Amputation
Great Toe Amputation
• Custom molded filler in shoe• Prevents sliding of
foot inside shoe
• MTP disarticulation• Partial amputation
• Residual partial toe maintains space• Blocks migration of adjacent toes
Lesser Toe Amputation
• Do not leave 1 or 2 remaining toes• Develop ulceration• Transmetatarsal amputation
Lesser Toe Amputation
Lesser Toe Amputation
• Toe separators to avoid drift• Complications
• Dehiscence• Toe drift• DF of the stump
Ray & Partial Foot Amputations
• More common• Durable • Easy to fit in shoes w/ minor modifications• Narrowing of foot
• Increased forefoot pressure• Treat w/ molded insole
• Preservation of foot length
Border Ray Resection
• 1st & 5th easiest
• Straight incisions• Loop around digit
• Longer plantar flap
Border Ray Resection
• 1st ray resection• Controversial
• Transmet???
Central Ray Resection
• Flaps not as mobile; gap may not close• Preserve soft tissue• Avoid disarticulation @ base of MT
• Midfoot instability• Further breakdown
Partial Forefoot Amputation
• 2 (or 3) medial or lateral ray resection
• ≥3 rays transmet• Lateral ray resection
tolerated better• Creative flaps often
necessary
Partial Forefoot Amputation
• Aftercare• Extra depth shoes
• Accommodates remaining posture & deformities• E.g. claw toes
• Accommodates molded insoles• Shoe filler
• Prevents windshield wiper motion• Rocker-bottom sole
Partial Forefoot Amputation
• Complications• Delayed/poor wound healing• Unstable foot
• Charcot• Ulceration
Transmetatarsal Amputation
• Technically easy• Tibialis anterior preserved
• Active DF• Counteracts equinus contracture
• Rule out equinus deformity• TAL may be necessary
Transmetatarsal Amputation
• Incision based on viable margins• Full thickness flap dorsally• Long plantar flap• Tendons cut under tension• Cascade metatarsals
• Each successive MT ≥2mm shorter
Transmetatarsal Amputation
• Bevel metatarsals• 15-20° dorsal distal to plantar proximal• 5th beveled in 2 planes (plantar & lateral)• Prevents sharp plantar edge & ulceration
Transmetatarsal Amputation
• Preserve length, if possible• Shorter healed stump better than longer,
incompletely healed• Preserve MT bases
Transmetatarsal Amputation
• Toe-filler, lace-up shoe• Rigid & rocker-bottom sole• +/- MAFO
Transmetatarsal Amputation
• Complications• Recurrent/recalcitrant ulceration
• Most often equinus contracture• TAL
• Prominent bone• Resect
Chopart’s Amputation
• Through transverse tarsal (TN & CC) joint or “Chopart’s joint”
Chopart’s Amputation
• Advantages• Easier than Syme’s• Allows use of a shoe w/ AFO rather than prosthesis• Less limb shortening• Preserves tough weight bearing skin of heel
• Poor choice for an active person
Chopart’s Amputation
• Dorsal and plantar flaps
• Leave sufficient soft tissue to accommodate for width of foot
• Extensor tendons resected
• Tibialis anterior & peroneal brevis tendons preserved
Chopart’s Amputation
• TT joint released• Achilles tenectomy
• Simple TAL leads to recurrent equinus
• TA transferred to neck of talus• PB transferred to anterior process
of calcaneus
Prosthetic Considerations
• Since minimal distance from floor, leaves little/no room for prosthesis• Poor amputation level for active patients
Prosthetic Considerations
• AFO w/ built-in molded insole• Plastizote lining to protect & cushion the limb
• Rigid prosthesis extending to tibial tubercle • Carbon fiber plate• Posterior opening door
James Syme, 1799-1870
• Clinical professor @ U. of Edinburgh• Never earned MD• Joseph Lister
• Son-in-law• Invented modern raincoat• 1843
• Ankle disarticulation in 16 yo boy w/ TB talus & calcaneus
Syme’s Amputation
• Ankle disarticulation• Advantages
• Longer limb • Specialized skin & pad of heel• Room available for self-
suspending prosthesis w/ artificial foot
Syme’s Amputation
• Contraindicated if patient lacks viable heel pad
Syme’s Amputation
• Incisions connect points 1.5cm anterior/inferior to malleoli• Plantar incision down to calcaneus• Dorsal incision to dome of talus
• Anterior tendons resected• Anterior tibial artery ligated
Syme’s Amputation
• Release ligamentous attachments to talus• Preserve medial neurovascular bundle
• Common cause for wound breakdown
Syme’s Amputation
• Protect subcutaneous attachment of Achilles• Subperiosteal dissection calcaneus
• Technically difficult• Avoid penetrating skin @ this level
Syme’s Amputation
• Cut malleoli flush w/ plafond• Preserve medial & lateral aspects
• Important to aid in prosthesis suspension• Heel pad sutured to bone
• Otherwise becomes hypermobile & problematic
Syme’s Amputation
• Plantar fascia sutured to deep fascia on anterior aspect of leg• Do not resect dog ears (can lead to failure)• Can be done in 2 stages for infection
Syme’s Amputation
• Advantages over BKA• Full lower leg segment allows for greater quad
leverage• Minimal prosthetic training• Lower energy cost • Higher velocity• Greater stride length
Syme’s Amputation
• Success rate 50-90%• Early failure
• Dysvascular heel pad most common• Late failure
• Progressive PVD • Distal bony prominences
• Hypermobility of stump• Neuroma formation• Heel pain
Prosthetic Considerations
• Door or window allows donning & doffing prosthesis in presence of bulbous distal stump
Pirogoff’s Amputation
• Variation of Syme’s • Portion of calcaneus preserved &
internally fixed• Advantages
• Longer soft tissue flaps • Less shortening
• Disadvantages• Symptomatic non-union
Boyd’s Amputation
• Neither Pirogoff’s nor Boyd’s amputations performed very often• Increased surgical time• Few advantages• Should only be performed if patient is
low demand & will not use prosthesis
BKA
• Necessary when foot salvage fails• Tibial resection 9-12cm below joint line• Fibular resection 1cm proximal to tibia• Long posterior flap
• 12-15cm
Energy ExpenditureAmputation
LevelEnergy, Above
Baseline (%)
Speed (m/min) Oxygen Cost (mL/kg/m)
Long BKA 10 70 0.17
BKA 25 60 0.20
Bilat BKA 40 50 0.20
AKA 65 40 0.20
Wheelchair 0-8 70 0.16
RE ECT
the ankle
the foot