Guides / L1833
L1833 Knee orthosis, adjustable joints, rigid support — off-the-shelf (L1832: custom fitted)Medicare Knee Orthosis Documentation Requirements (L1833, L1832)
Citations verified against the CMS Medicare Coverage Database · Reviewed September 2026
Prefabricated double-upright knee orthoses are among the most reviewed items the DME MACs see, and the reason is consistent: the record says "pain" or "instability" without the exam that proves it. LCD L33318 (Knee Orthoses) and Policy Article A52465 are specific about what counts.
L1833, the off-the-shelf version, was removed from CMS's Required Prior Authorization List in August 2024 and returns to it on October 28, 2026 — along with the face-to-face and written-order-prior-to-delivery requirements. L1832, the custom-fitted twin, has required prior authorization since 2022. The requirement set below is what AffirmDME checks on both.
The requirements, with citations
Every item below is a check AffirmDME runs automatically — this list mirrors the production rules engine, not a paraphrase of the regulations.
Recent knee injury or surgery, or objective knee instability
The record must show one of the LCD's coverage pathways: a recent injury to or surgical procedure on the knee, or an ambulatory beneficiary with knee instability supported by a Group 2 or Group 4 diagnosis from the policy article.
LCD L33318 — knee orthosis coverage criteriaInstability pathway: ambulatory status and the joint laxity exam
When coverage rests on instability rather than injury or surgery, the LCD requires an ambulatory beneficiary, and the policy article requires the record to name the laxity test(s) performed (varus/valgus stress, anterior/posterior drawer) and describe the findings. Pain or a subjective description of instability does not meet the criterion.
LCD L33318 criterion 2 / Policy Article A52465 — joint laxity documentationDiagnosis codes from the policy article's groups
The claim's ICD-10 codes must come from the Group 2 (injury/surgery) or Group 4 (instability) lists in A52465.
Policy Article A52465 — Group 2 / Group 4 ICD-10 codesFace-to-face encounter documented (required from October 28, 2026)
L1833 joins CMS's Required Face-to-Face Encounter and Written Order Prior to Delivery List on October 28, 2026. From that date the chart notes must document an in-person (or permitted telehealth) evaluation for the item, and the completed order must reach you before delivery.
42 CFR 410.38(d)(2) — F2F/WOPD list, effective 10/28/2026Face-to-face within 6 months of the order
The qualifying encounter must have occurred within the 6 months before the order date.
42 CFR 410.38(d)(2)Standard Written Order (SWO) on file
A complete written order must exist before the claim is submitted — patient name, item description, quantity, ordering practitioner, and signature.
42 CFR 410.38(d)Order date and practitioner signature
The SWO must be dated and signed by the treating practitioner. Undated or unsigned orders are treated as no order at all.
42 CFR 410.38(d)Practitioner NPI on the order
The ordering practitioner's NPI must appear on the order and match PECOS enrollment.
42 CFR 410.38(d)Medical necessity in the clinical record
The medical record — not just the order — must support why the item is medically necessary for this patient.
CMS PA Documentation ChecklistLength of need documented for rental items
Since the 2020 SWO rule, length of need is no longer a required element of the order itself — but the DME MAC PA portals ask for it, and the record must support the expected duration of use. AffirmDME requires an estimated length of need (1–99 months; 99 = lifetime) on every capped-rental item so the packet never stalls on it.
42 CFR 410.38(d) — SWO elements (2020 rule); DME MAC PA request fieldsWhat usually sinks these claims
- The record documents pain but no injury, surgery, or objective laxity exam — Noridian's 2025 knee orthosis review found this in the largest share of errors
- A same-or-similar orthosis (L1810–L1860) is on file within the last five years and no ABN was obtained
- The item was billed as custom fitted (L1832) when only straps were adjusted at delivery — that is the off-the-shelf code
- Replacement claims with no documentation that the original was lost, stolen, or irreparably damaged in a specific incident
- Proof of delivery missing or not matching the billed date of service
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Check a case freeFAQ
Does Medicare require prior authorization for L1833?
From October 28, 2026, yes — for dates of delivery on or after that day, nationwide. L1833 was on the list from 2022, came off in August 2024, and was re-added by the July 2026 Federal Register notice. L1832 has required prior authorization since 2022.
What is the difference between L1832 and L1833?
The same device, distinguished by fitting at delivery. L1833 is off-the-shelf: only minimal self-adjustment (straps, closures, simple trimming) that the beneficiary or supplier can do. L1832 is custom fitted: more than minimal adjustment by a certified orthotist or someone with equivalent training. Bill the code that matches what actually happened.
What counts as documentation of knee instability?
A physical examination that names the laxity test performed and describes objective findings — for example varus/valgus instability or a positive anterior drawer. The MACs' joint Dear Physician letter is explicit that pain or a subjective complaint of instability is not enough.
Does the PA decision cover the diagnosis criteria?
The reviewer checks the same LCD criteria you see above. An affirmed decision means the documentation supported coverage at the time of review; it is not a guarantee of payment if the claim later fails a technical check such as same-or-similar or proof of delivery.
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This guide summarizes Medicare requirements as implemented in AffirmDME's compliance engine, with citations to the governing sources. It is not legal or billing advice; LCDs and CMS policy change — always confirm against the current policy text linked above.
Also drawn on: Noridian JD — knee orthoses TPE review results (Oct–Dec 2025) · CGS — prior authorization for orthoses (request acceptance dates) .
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- Medicare DME Documentation Requirements: the checklist every claim needs
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- The Medicare DMEPOS Required Prior Authorization List, explained (2026)
- Probationary Prior Authorization for newly enrolled DMEPOS suppliers (Oct 15, 2026)
- The DMEPOS prior authorization exemption: how it works and how to keep it
- Which DME MAC handles your claim: Jurisdictions A, B, C, and D
- Standard Written Order (SWO) requirements for Medicare DME
- Medicare DME face-to-face encounter requirements
- Prior authorization vs ADR vs prepayment review vs TPE: what each means for a DME claim
- After a non-affirmed prior authorization: resubmit, deliver with an ABN, or wait
- Medicare DME proof of delivery requirements
- Preparing and submitting a DMEPOS prior authorization request
Unfamiliar term? The glossary defines ADR, SWO, UTN, PTAN and the rest; the PA List lookup checks any HCPCS code.