2015 ISAKOS Biennial Congress ePoster #1919

Prospective Clinical and Radiological Two-Year Results After Inlay and Onlay Patellofemoral Arthroplasty

Matthias Cotic, MSc, Munich, Bavaria GERMANY
Matthias Feucht, MD, Munich GERMANY
Gebhart Meidinger, MD, Munich GERMANY
Philip B. Schoettle, MD, PhD, Assoc. Prof., Munich GERMANY
Knut Beitzel, Prof., Cologne GERMANY
Andreas B. Imhoff, MD, Prof., Munich, Bavaria GERMANY

Department of Orthopaedic Sports Medicine / Klinikum Rechts der Isar / Technische Universit√§t M√ľnchen, Munich, GERMANY

FDA Status Not Applicable

Summary: Patellofemoral inlay and onlay resurfacing arthroplasty demonstrate significant improvements in pain and function in isolated procedures.




Patellofemoral arthroplasty has a history of more than 30 years, however patient selection and implant choice continue to create a challenging clinical picture for optimized outcomes. Conceptual design differences can be classified into two concepts to address and improve the native anatomy. The purpose of this study therefore was to assess the clinical and radiographic differences of isolated inlay and onlay patellofemoral arthroplasty with prospective two year results.

Material And Methods

From 2006 to 2010 a total of 28 patients were treated with an isolated patellofemoral arthroplasty. Fourteen patients (Group I, 3 female, 11 males, mean age 50±8 years) underwent implantation of an Onlay prosthesis (Journey PFJ® Smith&Nephew, Andover, MA, USA). The other 14 patients (Group II, 4 female, 10 male, mean age 45±12 years) received an Inlay prosthesis HemiCAP® Wave, Arthrosurface, Franklin, MA, USA). All patients demonstrated significant baseline symptoms refractory to conservative care (n = 28) and prior surgical interventions (Group I, n=11; Group II, n= 13). Clinical outcomes were based on Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores, Pain Visual Analog Scale (VAS); progression of radiographic tibiofemoral arthritis was assessed using Kellgren-Lawrence Scores (KL).


The average follow-up was 2 years in both groups. The following medians were assesed: Group I showed a significant VAS Pain improvement from 8 to 5 (Delta 3, p=0.006); similar in Group II, the VAS pain significantly improved from 6 to 3 at last follow-up (Delta 3, p=0.002). The WOMAC score also improved significantly in both Groups: Group I changed from 52 to 80 (Delta 28, p=0.001), Group II changed from 53 to 88 (Delta 35, p=0.046). Radiographic comparison in Group I showed a significant worsening of the preoperative tibiofemoral Arthritis Grade (KL medial, delta 0, p = 0.034; KL lateral, delta 1, p = 0.034), whereas Group II did not show any progression of tibiofemoral arthritis (KL medial, delta 0, p = 0.317; KL lateral, delta 0, p = 0.317).


Both prosthetic design concepts demonstrated significant improvements in pain and function. When compared to onlay patellofemoral arthroplasty, implantation of inlay prostheses showed better preservation of the tibiofemoral joint and did not result in a progression of the baseline stage.