Retired - Correct Coding – LIM Innovation Below Knee Socket

Infinite Socket™ (LIM innovations) is an open-frame below-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 Healthcare Common Procedure Coding System (HCPCS) L-codes used for below-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 the socket design has critical design elements to meet the coding requirements for the following HCPCS codes. The correct combination of HCPCS codes to bill Medicare for this item are described below:

1. Base code for complete prosthesis (choose one)

• L5301 BELOW KNEE, MOLDED SOCKET, SHIN, SACH FOOT, ENDOSKELETAL SYSTEM
• L5540 PREPARATORY, BELOW KNEE 'PTB' TYPE SOCKET, NON-ALIGNABLE SYSTEM, PYLON, NO COVER, SACH FOOT, LAMINATED SOCKET, MOLDED TO MODE

2. Base code for socket replacement

• L5700 REPLACEMENT, SOCKET, BELOW KNEE, MOLDED TO PATIENT MODEL

3. Addition codes to always bill with one of the above base codes

• L5629 ADDITION TO LOWER EXTREMITY, BELOW KNEE, ACRYLIC SOCKET
• L5637 ADDITION TO LOWER EXTREMITY, BELOW KNEE, TOTAL CONTACT
• L5940 ADDITION, ENDOSKELETAL SYSTEM, BELOW KNEE, ULTRA-LIGHT MATERIAL (TITANIUM, CARBON FIBER OR EQUAL)

4.  Addition codes that are not to be billed

• L5620 ADDITION TO LOWER EXTREMITY, TEST SOCKET, BELOW KNEE
• L5646 ADDITION TO LOWER EXTREMITY, BELOW KNEE, AIR, FLUID, GEL OR EQUAL, CUSHION SOCKET
• L5668 ADDITION TO LOWER EXTREMITY, BELOW KNEE, MOLDED DISTAL CUSHION

The add-on codes L5629, L5637, L5940, and the HCPCS codes describing the choice of suspension must be included on the same claim for the complete prosthesis or socket replacement, i.e., the claim that includes one of the above base codes.

Do not use L5301 or L5540 for billing a replacement socket for an existing prosthesis.

HCPCS code L5999 (LOWER EXTREMITY PROSTHESIS, NOT OTHERWISE SPECIFIED) must not be used to bill for any features or functions included in the socket. The combinations of base and addition codes listed above include all the features and functions of the design. Use of L5999 is incorrect coding (unbundling).

HCPCS codes used to describe the type of suspension incorporated into the socket must be added to the claim. Use of more than one type of suspension per limb is considered incorrect billing (same/similar item).

HCPCS codes describing features that may not be necessary on all sockets or prostheses 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):

• L5645 ADDITION TO LOWER EXTREMITY, BELOW KNEE, FLEXIBLE INNER SOCKET, EXTERNAL FRAME
• L5910 ADDITION, ENDOSKELETAL SYSTEM, BELOW KNEE, ALIGNABLE SYSTEM

Do not bill L5910 when providing a replacement socket as this addition was previously reimbursed with the provision of the complete prosthesis. Claims for L5910 in conjunction with any replacement socket are considered incorrect billing.

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

Refer to the Lower Limb Prosthesis Local Coverage Determination and related Policy Article for additional information on coverage, coding and documentation for artificial limbs.

For questions about correct coding, contact the Pricing, Data Analysis and Coding (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 e-mail the PDAC by completing the DME PDAC Contact Form.