why iUni? CLINICAL RATIONALE FOR A PATIENT-SPECIFIC UNICOMPARTMENTAL KNEE REPLACEMENT SYSTEM
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CLINICAL RATIONALE FOR A PATIENT-SPECIFIC UNICOMPARTMENTAL KNEE REPLACEMENT SYSTEM

Key elements needed for a successful UKA: The right patient, a highly reproducible procedure, and the right implant. UKA can have favorable results vs. off-the-shelf TKA Better function and ROM 1 UKA patients have better range of motion and function. PKR tibial axial rotation is comparable to native knees, while TKR knees show a signicant difference.2 UKA can require revision Recent results from national registries and other multi-center studies reporting on causes of revision from over 6,500 primary xed bearing UKA. PKR patients have fewer problems bending their knee.3 17% Patients prefer...

The right UKA implant system must maximize the chance of procedural success and must minimize the chance of failure. Key drivers of a successful UKA procedure Preventing failure from implant loosening and subsidence Preventing malpositioned components and malaligned (varus/valgus) tibial resections 24% of loosening is attributed to femoral and tibial component malposition or malaligned tibial resections.14 Maximizing tibial coverage Poor tibial coverage, i.e. underhang, has been attributed to increased risk of tibial component loosening and subsidence.15 Minimizing disease progression and...

Impact of Tibial Overhang Overhang of ≥3mm has been shown to be clinically signicant • A study of 160 Oxford UKR patients demonstrated at 5 years post-surgery that 9% of patients have major overhang (≥3mm) and signicantly worse Oxford knee scores and pain scores.15 • In a study with six cadavers, researchers identied that tibial trays with ≥3mm of anterior overhang result in signicantly higher loads on the MCL.16 iUni G2 solution: Unparalleled tibial t Key design features Implant proles are patientmatched to provide >95% tibial coverage20 Designed to sit within in ≈1mm of cortical rim m...

Impact of Tibial Underhang Multiple publications have associated underhang with tibial loosening and subsidence Off-the-shelf UKA offers limited options • Chau, et al., stated in UKA that “…concern with an under-hanging tray is that the load is transmitted primarily through the relatively weak cancellous rather than the stronger cortical bone. This may increase the risk of tibial component subsidence and loosening.”15 • Swienckowski, et al., stated that in UKA “…cortical support is essential for the tibial components to avoid subsidence.”21 • Fitzpatrick, et al., in a comparison of UKA...

Impact of Femoral Fit on Patient Pain Malaligned femoral components can cause loosening A study of 47 UKA failures during the period of 2000-2008, identied that 16% were attributed to femoral malposition or sizing issues.14 Patella impingement can cause increased pain A study of 99 UKA knees at mean 14 year follow-up identied that 28% had patella impingement and increased pain, typically when on stairs and rising from chairs.17 iUni G2 solution: Unparalleled femoral t femoral malposition or sizing issues14 Key design features Implant set at ~1mm inferior to sulcus terminalis for optimal...

Impact of Femoral Fit on Function Anatomy of the femur varies Femoral condyles have an asymmetrical shape and vary from patient to patient.24 Off-the-shelf systems offer limited options A typical UKA system has the following femoral component conguration. • A single shape • A set range of sizes iUni G2—an opportunity to maintain patients’ anatomy Key design features Green line represents patient’s sagittal J-curve at articulating surface level Femoral component thickness approximates average cartilage thickness on the femur Femoral component follows bone topography of the medial or lateral...

Impact of implant design on long-term Mechanical Axis Alignment Can Impact Disease Progression and Polyethylene Wear Slight ‘undercorrection’ can provide optimal results • Studies have shown ‘slight undercorrection’ (e.g. between 171° to 179° post-operative varus angle in a medial UKA) can provide optimal results.25 Slight undercorrection • A follow-up study of 58 medial uni knees with mean 15 year follow-up, reported that ‘overcorrected’ knees (e.g. post-operative valgus angle in a medial UKA) had 92% more cartilage loss in the opposite condyle.25 provides optimal axis alignment • In the...

Other Factors Impacting Polyethylene Wear Contact stress can impact topside wear Reducing contact stress has been shown to reduce wear on the articulating surface of the poly insert.26 Micro-motion Index Comparison Standard29,30 vs. ConforMIS G2 implants31 Poly/tray micro-motion and undersurface can impact backside wear 50 40 Studies have shown micro-motion can cause wear. In addition, examinations of explanted inserts have identied the poly undersurface as a second source of wear.27, 28 iUni G2 solution: Engineered femoral and tibial components Key design features Femoral component and...

why iUni? FIT • Individualized t that virtually eliminates overhang and sizing compromises • Designed to follow the contour of each patient’s anatomy • Tibial tray designed for maximized cortical rim coverage and proper rotational alignment SHAPE • Individualized medial or lateral femoral J-curves • Wear optimized by matching femur and tibial inserts for maximized surface contact area SIMPLE SURGICAL TECHNIQUE • Reduced number of intra-operative decisions such as implant sizing and rotation • Mechanical and rotational alignment are pre-determined in the individualized iJig instrumentation •...

references 1. Rougraff B, et al.; “A comparison of tricompartmental and unicompartmental arthroplasty for the treatment of gonarthrosis”; Clin Orthop Relat Res; Dec 1991; Vol. 273: pp. 157–164 2. Patil S, et al.; “Can normal knee kinematics be restored with unicompartmental knee replacement?”; J Bone Joint Surg AM; Feb 2005; Vol. 87(2): pp. 332-338 3. Lastad-Lygre S., Pain and function in patients after primary unicompartmental and total knee arthroplasty; J Bone Joint Surg Am; Dec 2010; Vol. 92(18): pp. 2890-2897 4. Dalury D., et al.; “Unicompartmental knee arthroplasty compares favorably...