The amputee K-levels ranking system is the common practice in the US for classifying amputees into 5 classes. On 2001, the US Health Care Financing Administration’s (HCFA) published a common procedure coding system using code modiﬁers (K0, K1, K2, K3, K4) as a 5-level functional classiﬁcation system related to the functional abilities of lower-limb amputees. In simple words, the lower the activity potential of the amputee, the lower is his/her amputee K-level and vice versa.
Why do we care about our amputee K-level at all? For one, health insurance plans rely on the K-level when approving a prosthetic leg and its components. Once an amputee is assigned a K-level, this dictates the class of the prosthetics the amputee can purchase.
- K0 – No Mobility. This base level is assigned to amputees who do not have the ability or potential to ambulate or transfer safely with or without assistance. A prosthesis does not enhance the quality of life or mobility of the amputee.
- K1 – Very Limited Mobility. The amputee has the ability or potential to use a prosthesis for transfers or ambulation in level surfaces at a ﬁxed walking pace. Walking at various speeds, bypassing obstacles of any kind are out of the K1 class.
- K2 – Limited Mobility – The amputee has the ability or potential to use a prosthesis for ambulation and the ability to adjust for low-level environmental barriers such as curbs, stairs, or uneven surfaces. K2 level amputees may walk for limited periods of time however, without significantly varying their speed.
- K3 - Basic to Normal Mobility. The amputee has the ability or potential to use a prosthesis for basic ambulation and the ability to adjust for most environmental barriers. The amputee has the ability to walk at varying speeds.
- K4 – High Activity. The amputee exceeds basic mobility and applies high impact and stress to the prosthetic leg. Typical of the prosthetic demands of the child, active adult, or athlete.
Amputee K-levels are determined by the treating physician and/or the prosthetist. To evaluate the amputee condition, they consider previous activity of the amputee, residual limb condition, other medical problems, the amputee desire for activity, etc. Naturally, such factors change with time hence, the amputee K-level is dynamic and may change with time. A motivated amputee would most probably go up K-levels. It is important for an active amputee to be classified in his/her appropriate K-Level so that components that are designed for higher activity levels would be covered for payment under the Medicare policy. If your functional ability increases over time, your rating can be changed to a higher level.