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Correct Coding – LIM innovations Infinite Socket™ – Revised

DME MAC Joint Publication

This is a revision to the original article, posted 5/21/2015. This article changes the previously published benefit determination and code assignment.

Infinite Socket™ (LIM innovations) is an open-frame above-knee socket design that has recently become available. This product uses struts that extend from a base to an adjustable brim enclosing an inner shell to form the structure of the socket. It is custom-fabricated from a model of the patient’s residual limb.

The existing HCPCS L-codes used for above-knee lower limb prosthesis sockets describe items which enclose the residual limb to provide the stability, proprioception, and suspension necessary for the effective use of the artificial limb. Although the LIM innovations Infinite Socket™ is different in design from traditional sockets described by the existing L-codes, it has been determined that this product is an effective alternative and that existing HCPCS codes appropriately describe the product. The correct combination of codes to bill Medicare for this item are:

Base Code

If this product is included as part of a complete prosthesis, the base socket is included as part of the prosthesis base code. Chose the appropriate base code depending upon the type provided.

  • L5321 – Socket above knee, molded socket, open end, sach foot, endoskeletal system, single axis knee
  • L5590 – Preparatory, above knee – knee disarticulation ischial level socket, non-alignable system, pylon no cover, sach foot, laminated socket, molded to model

The add-on codes discussed below (L5631, L5649, L5950, and choice of suspension) must be included on the same claim for the complete prosthesis i.e., the claim that includes one of the above codes. Do not use L5321 or L5590 for billing a replacement socket for an existing prosthesis.

If this product is provided as a replacement to an existing socket, in addition to the add-on codes below (L5631, L5649, L5950, and choice of suspension), for the base code, use:

  • L5701 – Replacement, socket, above knee/knee disarticulation, including attachment plate, molded to patient model

Addition codes:

Use on all claims in addition to the base code:

  • L5631 – Addition to lower extremity, above knee or knee disarticulation, acrylic socket
  • L5649 – Addition to lower extremity, ischial containment/narrow m-l socket
  • L5950 – Addition, endoskeletal system, above knee, ultralight material (titanium, carbon fiber or equal).

HCPCS code L5999 (Lower extremity prosthesis, not otherwise specified) must not be used to bill for features or functions included in the socket. The combination of base and addition codes listed above include all the features and functions of the base device. Use of L5999 in this manner is incorrect coding (unbundling).

HCPCS add-on L codes used to describe the type of suspension incorporated into the socket may be added to the claim. Use of more than one type of suspension is considered incorrect billing, (same/similar item).

HCPCS codes describing features that may not be necessary on all sockets may only be used when the feature is provided for the individual beneficiary. Some examples of features that are not automatically included in every socket or for all beneficiaries are (not all-inclusive):

  • L5651 – Addition to lower extremity, above knee, flexible inner socket, external frame
  • L5920 – Addition, endoskeletal system, above knee or hip disarticulation, alignable system

The prosthetic record must include specific, detailed information justifying the need for each additional feature

Test sockets (L5624 – Addition to lower extremity, test socket, above knee) are not necessary for the production of this socket design. Claims for L5624 in conjunction with this socket design are considered incorrect billing.

Refer to the LCD for Lower Limb Prostheses (L33787) and related policy article for additional information on coverage, coding and documentation for artificial limbs.

For questions about correct coding, contact the PDAC contractor Contact Center at 877-735-1326 during the hours of 8:30 a.m. to 4:00 p.m. CT, Monday through Friday, or email the PDAC by completing the DME PDAC Contact Form.

Correct Coding - LIM innovations Infinite Socket™ - Revised
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