Patellofemoral arthroplasty with onlay prosthesis leads to higher rates of osteoarthritis progression than inlay design implants: a systematic review

Abstract

Purpose The aim of this study was to report the clinical and functional outcomes, complication rates, implant survivorship and the progression of tibiofemoral osteoarthritis (OA), after new inlay or onlay patellofemoral arthroplasty (PFA), for isolated patellofemoral OA. Comparison of different implant types and models, where it was possible, also represented one of the objectives. Methods A systematic literature search following PRISMA guidelines was conducted on PubMed, Scopus, Embase and Cochrane databases, to identify possible relevant studies, published from the inception of these databases until 11.11.2022. Randomized control trials (RCTs), case series, case control studies and cohort studies, written in English or German, and published in peer-reviewed journals after 2010, were included. Not original studies, case reports, simulation studies, systematic reviews, or studies that included patients who underwent TKA or unicompartmental arthroplasty (UKA) of the medial or lateral compartment of the knee, were excluded. Additionally, only articles that assessed functional and/or clinical outcomes, patient-reported outcomes (PROMs), radiographic progression of OA, complication rates, implant survival rates, pain, as well as conversion to TKA rates in patients treated with PFA, using inlay or onlay trochlea designs, were included. For quality assessment, the Methodological Index for Non-Randomized Studies (MINORS) for non-comparative and comparative clinical intervention studies was used. Results The literature search identified 404 articles. 29 of them met all the inclusion criteria following the selection process. Median MINORS for non-comparative studies value was 12.5 (range 11–14), and for comparative studies 20.1 (range 17–24). In terms of clinical and functional outcomes, no difference between onlay and inlay PFA has been described. Both designs yielded satisfactory results at short, medium and long-term follow-ups. Both designs improved pain postoperatively and no difference between them in terms of postoperative VAS has been noted, although the onlay groups presented a higher preoperative VAS. When comparing the inlay to onlay trochlea designs, the inlay group displayed a lower progression of OA rate. Conclusion There is no difference in functional or clinical outcomes after PFA between the new inlay and the onlay designs, with both presenting an improvement in most of the scores that were used. A higher rate of OA progression was observed in the onlay design group. Level of evidence III.

Almost 79% survival rate at 10‐year follow‐up for the patellofemoral joint arthroplasty: An Italian prosthetic registry study

“…Clinically, this study showed how PFJ can be equated with TKA in survival outcomes and subjective clinical scores and highlighted that PFJ remains a procedure with less blood loss, shorter hospital stay [7], preservation of bone stock and ligaments [23] and better functional outcomes and stair-climbing abilities [17].…”

Robotic-assisted patellofemoral arthroplasty provides excellent implant survivorship and high patient satisfaction at mid-term follow-up

“…This advancement mitigates trochlear internal rotation risk and effectively manages any degree of dysplasia demonstrating a tangible impact on reducing failure rates [ 16 , 38 , 39 ]. However, these implants can’t effectively substitute the native trochlea, accelerating the progression of OA, which persist as great cause of failure [ 40 – 42 ]. Moreover, 2nd generation PFAs often result in an increased thickness of the trochlea, causing overstuffing of the patellofemoral joint and, consequently, pain due to increased tension exerted on the retinacular fibers [ 43 ].…”

Standard Versus Dysplastic Inlay Implant for Patellofemoral Arthroplasty: Surgical Technique and Decision-Making

“… 9 The new inlay design better maintains the natural biomechanics of the joint and allows personalized and anatomic trochlear resurfacing, reducing complications, improving stability, preserving soft tissue tension, and minimizing overstuffing. 9 , 10 , 11 , 12 , 13 , 14 …”