Limb Difference is the partial or complete absence of or malformation of limbs [2], which can result from Amputation, the removal of a limb such as a finger, toe, hand, foot, arm or leg [1].
Amputation can be congenital (present from birth), traumatic (due to an accident or injury) or surgical (due to any of multiple causes such as blood vessel disease, cancer, infection, excessive tissue damage, dysfunction, pain, etc.) [1].
Limb difference can be caused by a previous fracture, trauma to a growth plate or a previous infection. Genetic conditions or syndromes can also result in one limb being longer than the other [2].
Disarticulations are amputations of two bones at their joint [1].
Amputations are categorized based on where the amputation occurs on the body [1].
Lower Limb Amputations:
Below Ankle
- Toe Amputation - Removal of the phalanges (toe bones).
- Transphalangeal Amputation / Toe Disarticulation - Removal of the toe at the metatarsophalangeal (forefoot) joint.
- Transmetatarsal Amputation - Removal of the foot through the metatarsal shafts (long foot bones).
- Lisfranc Amputation - Removal of the foot at the tarsometatarsal (midfoot) joint and disarticulation of all five metatarsals (long foot bones).
- Chopart Amputation - Removal the foot at the talonavicular (ball and socket joint in foot) and calcaneocuboid joints (allows smooth movements of heel and foot bones) and disarticulation through the midtarsal joint (articulation between the midfoot and the hindfoot) leaving only the calcaneus (heel) and talus (bone at base of ankle).
- Syme Amputation / Ankle Disarticulation - Removal of the foot at the ankle joint with preservation of the heel pad.
- Boyd’s Amputation - Removal of the ankle with preservation of the heel pad that retains the calcaneus (heel) and fuses it with the distal tibia (lower end of shin) at the ankle mortise (connection of the lower ends of the shin and calf bones and the bone at base of ankle.
Above Ankle
- Below Knee / Transtibial Amputation - Removal of the lower limb below the knee joint.
- Through Knee / Knee Disarticulation - Removal of the lower limb at the knee joint and not through lower limb bones.
- Above Knee / Transfemoral Amputation - Removal of the lower limb above the knee joint.
- Rotationplasty - Removal of the lower limb above the knee to remove tumors near the knee joint with the foot reattached backwards and the ankle joint acting as a new knee.
- Hip Disarticulation - Removal of the lower limb through the hip joint and not through lower limb bones.
- Hemipelvectomy - Removal of the lower limb through half of the pelvis.
Lower limb amputations are also categorized based on the United States’ Medicare Functional Classification Level (MFCL), also known as the K-Level, which is a 0 to 4 point scale of functional level [3].
- K0 - Does not have the ability or potential to ambulate or transfer safely with or without assistance and a prosthesis does not enhance their quality of life or mobility.
- K1 - Has the ability or potential to use a prosthesis for transfers or ambulation on level surfaces at fixed cadence. Typical of the limited and unlimited household ambulator.
- K2 - Has the ability or potential for ambulation with the ability to traverse low level environmental barriers such as curbs, stairs, or uneven surfaces. Typical of the limited community ambulator.
- K3 - Has the ability or potential for ambulation with variable cadence. Typical of the community ambulator who has the ability to traverse most environmental barriers and may have vocational, therapeutic, or exercise activity that demands prosthetic utilization beyond simple locomotion.
- K4 - Has the ability or potential for prosthetic ambulation that exceeds basic ambulation skills, exhibiting high impact, stress, or energy levels. Typical of the prosthetic demands of the child, active adult, or athlete.
Upper Limb Amputations:
Below Elbow
- Transphalangeal - Removal of the phalanges (finger bones).
- Transmetacarpal - Removal of the fingers below the metacarpal (bones in middle of hand).
- Transcarpal - Removal of the hand below the wrist joint.
- Wrist Disarticulation - Removal of the hand at the wrist joint and not through upper limb bones.
- Transradial Amputation - Removal of the upper limb below the elbow joint
Above Elbow
- Elbow Disarticulation - Removal of the upper limb at the elbow joint and not through upper limb bones.
- Transhumeral Amputation - Removal of the upper limb above the elbow joint.
- Shoulder Disarticulation - Removal of the upper limb at the shoulder joint and not through upper limb bones.
- Forequarter Amputation - Removal of the upper limb with its shoulder girdle.
[1] “Amputation.” Johns Hopkins Medicine. Link
[2] “Limb Length Inequality.” Johns Hopkins Medicine. Link
[3] “Table 1, Lower Limb Extremity Prosthesis Medicare Functional Classification Levels (K Levels)." U.S. National Library of Medicine. Link