Patellofemoral Arthroplasty
Patellofemoral arthroplasty is a type of partial knee replacement in which surgical option for isolated patellofemoral arthritis.
Two different designs include;
• İnlay-style designed (previous generation)
o Positioning Inset flush with native trochlea
o Rotation Determine by native trochlea
o Narrower
o No further proximal extension than native trochlear surface
• Onlay-style designed (newer generation)
o Replaces entire trochlea, perpendicular to AP axis
o Set by surgeon, perpendicular to AP axis
o Wider
o Extends further proximal than native trochlea
CLINICAL PRESENTATION
· Anterior knee pain arise from patellofemoral joint
o aggravated by activities such as squatting, ascending or especially descending stairs , getting up from a chair
· Patellar crepitus and reproduce pain during retro-patellar palpation
RADIOLOGIC ASSESMENT
· Standing AP/lateral knee radiographs
· Rosenberg view
· Patellar skyline (axial or merchant) view
· Standing full-leg radiographs
o To evaluate;
- Femorotibial compartments
- Femorotibial malalignment
- Stage of PF-OA (Iwano classification)
- Trochlear dysplasia
- Patellar height
- Patellar subluxation
· MRI
- Meniscal pathology, ligament injury
· CT
- To evaluate rotational malalignment
INDICATIONS
· Indications
o Isolated symptomatic PF
o PF-OA Iwano stage 3–4
o Posttraumatic PF-OA
o Trochlear dysplasia with or without instability
o Failed prior conservative procedure
o Good patellar tracking
o Age>40 years
· Absolute contraindications
o Systemic inflammatory arthropathy
o Tibiofemoral OA
o Severe uncorrected tibiofemoral malalignment (Valgus deformity > 8 degrees or varus deformity > 5 degrees)
o Uncorrected patellofemoral instability or maltracking
o Stiffness
o Ligamentous tibiofemoral instability
o Acute infection or CRPS
· Relative contraindications
o Quadriceps atrophy
o Patella baja
o BMI > 30
COMPLICATIONS
Showing that the 5-year cumulative revision rate was greater than 20% for inlay prostheses and less than 10% for onlay designs
Early complications
· Patellar instability
· Maltracking (inlay-style implants %17-36, onlay-style implants less than %1)
· Arthrofibrosis
· Persistant pain
· Extensor mechanism failure
Late complications
· Progression of tibiofemoral arthritis (most common reason for long-term failure, ̴25% of the revision at 15 years of follow-up)
· Aseptic loosening (more frequent in cementless PFA)
REFERENCES
· Batailler C, Libert T, Oussedik S, Zaffagnini S, Lustig S. Patello-femoral arthroplasty- indications and contraindications. J ISAKOS. 2024 Aug;9(4):822-828. doi: 10.1016/j.jisako.2024.01.003. Epub 2024 Jan 5. PMID: 38185247.
· Lonner JH, Bloomfield MR. The clinical outcome of patellofemoral arthroplasty. Orthop Clin North Am. 2013 Jul;44(3):271-80, vii. doi: 10.1016/j.ocl.2013.03.002. Epub 2013 May 4. PMID: 23827831.
Pisanu G, Rosso F, Bertolo C, Dettoni F, Blonna D, Bonasia DE, Rossi R. Patellofemoral Arthroplasty: Current Concepts and Review of the Literature. Joints. 2017 Oct 4;5(4):237-245. doi: 10.1055/s-0037-1606618. PMID: 29270562; PMCID