| Unispacer — Bailie et al. (2008) | Prospective 18‑patient series: 44% required revision within 2 years | High early revision rate; UniSpacer considered investigational/not established; supports non‑coverage |
| Bi‑UKR vs computer‑assisted TKR — Confalonieri/Framed 48‑month matched study | No difference in Knee Society scores; Bi‑UKR had better WOMAC Function/Stiffness and shorter hospital stay for Bi‑UKR | Some short‑term functional benefit in selected series but insufficient long‑term evidence; bicompartmental approaches remain experimental |
| Parratte long‑term bicompartmental series (Parratte et al.) | At mean 12‑17 years: prosthesis survivorship 78% for bicompartmental UKA vs 54% for medial UKA/PFA; higher revision vs TKA noted | Long‑term survivorship variable with higher revision rates in some series; argues caution and limited coverage until better evidence |
| Odgaard RCT (PFA vs TKA, 2018) | PFA: faster early recovery and better AUC for several PROs up to 2 years; no difference in complications over 2 years | PFA may be reasonable in appropriately selected isolated patellofemoral disease; supports conditional coverage for PFA in selected patients |
| Bunyoz systematic review (PFA vs TKA) | Second‑generation PFA and TKA have similar PROMs; PFA revision rate higher (8.4% vs 1.3%) | Short‑term PRO parity but higher revision risk for PFA — selection and counseling important; not broadly preferred over TKA |
| Journey‑Deuce bicompartmental implant — Dudhniwala et al. (2016) | Cohort (n=15): early aseptic loosening and 60% revision at minimum 54 months; implantation ceased at institution | Device‑specific high early failure supports classification as experimental/investigational and non‑coverage for that implant |
| PSI / Navigation meta‑analyses (Huijbregts 2016b; Thienpont 2017; Bouche network meta‑analysis) | PSI yields small radiographic differences, mixed tibial outlier effects, minimal clinical benefit; navigation reduces HKA outliers vs PSI/standard (~10% fewer) but no consistent PRO improvement | Robotic/navigation/PSI improve some radiographic accuracy but lack consistent clinically meaningful benefit — considered experimental/investigational or integral (not separately reimbursed) |
| CIM observational / single‑center cohorts (Culler 2017; Schwarzkopf 2015; Shroeder 2019) | Reports of lower transfusion/adverse events, reduced LOS, high early survivorship in small series; limited generalizability | Promising perioperative/efficiency signals but insufficient high‑quality long‑term comparative evidence — coverage limited to FDA‑approved devices and selection criteria; CIM remains conditional |
| Economic analyses / simulation (O'Connor 2019; Namin 2019) | Medicare episodes: customized cohort lower average episode spending ($18,585 vs $20,280); simulation projects potential large savings with broad CIM adoption but relies on assumptions | Economic models suggest potential savings but do not replace clinical effectiveness evidence; payers may require stronger clinical data before broad coverage expansion |
| Femoral overhang — Mahoney & Kinsey (2010) | ≥3 mm femoral overhang in ≥1 zone occurred in 40% men, 68% women; associated OR 1.9 for increased knee pain at 2 years | Implant fit matters; supports interest in patient‑specific or better sizing but does not by itself mandate coverage of CIM/PSI |
| Robotic arm / MAKO and long‑term RCT (Kim et al. long‑term RCT) and systematic reviews | Robotic assistance reduces alignment variance and outliers but long‑term RCT (13‑yr) showed no difference in function, survivorship, or complications; systematic reviews find better radiographic accuracy but no meaningful clinical benefit | Robotic techniques improve precision yet lack demonstrated long‑term clinical/survivorship benefit — considered integral/experimental and not separately reimbursed |
| Meta‑analyses of PSI trials (Rudran 2022; Hinloopen 2023; Russell 2014) | Mostly no clinical differences in PROs; occasional small statistically significant changes below MCID at 2 years; mixed alignment outcomes | PSI/PSCG/CCB not shown to provide clinically meaningful advantages to justify routine separate reimbursement; considered experimental/adjuvant |
| Tammachote RCT (CCB vs conventional, 2018) | No improvement in alignment or functional outcomes; operative time reduced by 11 mins | CCB may reduce OR time but lacks evidence of clinical benefit — experimental adjunct |
| ConforMIS / CIM cohort and kinematics (Zeller 2017; Shroeder 2019) | CIM associated with more normal kinematics, high satisfaction, 100% survivorship at ~1.9 yrs in small cohort; MUA rates comparable to literature | Short‑term favorable signals exist but long‑term comparative data limited; selective use may be considered where criteria met; broader coverage contingent on evidence |
| Ceramic femoral prosthesis long‑term (Nakamura 2017) | 507 TKAs: 15‑year survivorship 94% (revision/radiographic failure) and 96.2% (revision any component) | Long‑term data support certain alternative materials/devices when FDA‑approved; coverage aligned with device approval and selection criteria |
| MAKO/robotic observational UKA series (Deese 2018) and systematic reviews (Ruangsomboo 2023) | Robotic‑assisted UKA shows good early PROMs and accuracy; meta‑analysis: improved radiologic accuracy but little/no difference in PROs or survivorship at long‑term | Robotics may improve technical accuracy but lacks proven clinically meaningful long‑term outcome advantages — treated as integral/experimental adjunct not separately reimbursed |
| Callahan meta‑analysis (1995) & registry/cohort summaries (Wilson 2019) comparing UKA vs TKA | UKA and TKA have similar pain/function in many studies; UKA often shorter LOS and faster recovery but higher revision rates at 5–10 years | Supports coverage of UKA in appropriately selected patients per criteria; tradeoffs between faster recovery and higher revision risk must be considered |
| Parratte et al. (2010) & long‑term bicompartmental review | Bicompartmental arthroplasty gives short‑term improvement but long‑term durability not well documented; some implant designs had early failures and withdrawal | Evidence insufficient to support routine coverage of bicompartmental/bi‑UKA; considered experimental/investigational |
| Network/meta‑analysis (Bouche 2020) comparing navigation, PSI, robotics, standard guides | Navigation reduced HKA outliers vs PSI/standard (~10% fewer), but no differences in KSS/WOMAC at 6 months; other technologies showed mixed radiographic benefits without PRO improvement | Radiographic improvements alone are insufficient to justify routine separate reimbursement of navigation/PSI/robotics; considered experimental/integral adjuncts |