Today, I'd like to discuss a topic that has no association with the adult film industry.
Inlay and onlay; these two concepts keep coming up during my research and I can't get a grasp on the specifics of either. Specifically, the Arthrosurface patellofemoral implant that is marketed as an "inlay" device. Maybe I'm getting caught up in the nomenclature but it sounds like an inlay partial replacement is set within the cartiledge and an onlay is laid over the damaged bone? Let's do some research!
So here's the low-down; after reading through a lot of different literature, it boils down to this:
Inlay-onlay terminology is generally used in patellofemoral arthroplasty where there's either focal or diffuse areas of disease. It can also apply to tibio-femoral disease where there is hardware that addresses focal articular cartiledge defects, but generally a full onlay prosthesis is used since the nature of articular wear in this compartment is typically diffuse.
Inlay implants are inserted into a carved, flat pocket of the diseased region of the
bone. The implant is surrounded by a rim of cortical bone and supported by hardened,
sclerotic bone. Onlay implants are not placed into any furrows and do not require hardened bone for support, but instead rely on the direct support of a rim of cortical bone, as they are placed on top of a flat tibial osteotomy (ie cut-surfaced bone).
Translation: inlays are recessed flush with the the articulating cartilage, while onlay's encompass the whole area and provide the entire gliding surface.
Here's a good pic I found of an example of inlay/onlay on the tibial plateau:
Inlay and onlay; these two concepts keep coming up during my research and I can't get a grasp on the specifics of either. Specifically, the Arthrosurface patellofemoral implant that is marketed as an "inlay" device. Maybe I'm getting caught up in the nomenclature but it sounds like an inlay partial replacement is set within the cartiledge and an onlay is laid over the damaged bone? Let's do some research!
So here's the low-down; after reading through a lot of different literature, it boils down to this:
Inlay-onlay terminology is generally used in patellofemoral arthroplasty where there's either focal or diffuse areas of disease. It can also apply to tibio-femoral disease where there is hardware that addresses focal articular cartiledge defects, but generally a full onlay prosthesis is used since the nature of articular wear in this compartment is typically diffuse.
Inlay implants are inserted into a carved, flat pocket of the diseased region of the
bone. The implant is surrounded by a rim of cortical bone and supported by hardened,
sclerotic bone. Onlay implants are not placed into any furrows and do not require hardened bone for support, but instead rely on the direct support of a rim of cortical bone, as they are placed on top of a flat tibial osteotomy (ie cut-surfaced bone).
Translation: inlays are recessed flush with the the articulating cartilage, while onlay's encompass the whole area and provide the entire gliding surface.
Here's a good pic I found of an example of inlay/onlay on the tibial plateau:
Again, inlays have little application for the tibial-femoral joint since joint degeneration in this compartment is typically diffuse.
Why should I care about inlay and onlay? Inlay replacements provide the most conservative approach for resurfacing the patellofemoral area. By conserving the native bone, this allows for more joint restoration options in the future. My injury happens to be a focal point of cartilage damage. Why resurface the whole area when the use of an inlay would focus on the diseased area while preserving the rest of the joint.
And I'm sorry to disappoint my fan base looking for "ortho-erotica".
Why should I care about inlay and onlay? Inlay replacements provide the most conservative approach for resurfacing the patellofemoral area. By conserving the native bone, this allows for more joint restoration options in the future. My injury happens to be a focal point of cartilage damage. Why resurface the whole area when the use of an inlay would focus on the diseased area while preserving the rest of the joint.
And I'm sorry to disappoint my fan base looking for "ortho-erotica".