Patellofemoral Arthroplasty .align the patella!!!! Phil Davidson, - - PowerPoint PPT Presentation

Patellofemoral Arthroplasty ….align the patella!!!!

Phil Davidson, MD Davidson Orthopaedics Park City, Utah Ortho Summit, Las Vegas Dec 7, 2017

Disclosures

none

Outline

• Morphology
• Geometry
• Bio vs Prosthetic
• Prosthetics/Implants
• Realign Procedures
• Combo Procedures

– Realignment – Arthroplasty

The majority of PF DJD in isolation or in “younger patients” are associated with:

• 1. Abnormal Morphology
• 2. Abnormal Geometry

Rotation Height Version

28 year old female

Morphology

• Both patellar and trochlear

morphology need to be identified in considering treatment options

• Abnormal morphology can

create stresses on repairs

• May not make sense to do

inlay resurfacing on abnormal morphologic topography Wiberg Classification

Dejour Classification

Geometry

• Geometric alignment needs

to be considered in 3-D – Patellar position M-L

• Valgus knee

– Patellar “tilt”

• Femoral version

– Patellar height

• Correction targeted at

specific malalignment/rotation

• NEVER do Lateral Release

alone

Limb Rotation – femur and tibia

• Both Femoral

Version AND Tibial Torsion bear on PF forces

• Femoral Anteversion

– NL female 13

• External Tibial

Torsion

– NL female 27

Radiography

Merchant Xray- need dedicated board/ jig > 145 considered “shallow”

Radiography- Patellar Height

• Caton-Deschamps (CD)

Ratio (X/Y)

• NL appx 0.6-1.3
• Very handy to use

digital measuring tools

• Patellar Alta and Baja

– Can be addressed with TTO – Alta possible MPFL

Radiography- TT-TG or TT-PCL Relative Patellar Translation

• TT-TG, useful if distinct

FTG sulcus

– NL <appx 18mm

• TT-PCL, may be more

accurate, needed for abnormal FTG morphology

– NL appx <24

Extensor Realignment

• Medial Plication
• Lateral Release
• Need “normal” tissue to

plicate

– i.e. not markedly lax

• Easily incorporated into

PFA

“Selective” lateral release, preserving underlying synovial layer– part of realignm ent, not alone!

MPFL combo with PFA

• This is indicated when

DJD coexists with recurrent instability and/or laxity

• Need to protect patellar

implant

• Avoid patellar bone

tunnel techniques

TTO with PFA

• Medialization can

correct for increased TT-TG or TT-PCL

• Move proximal to

address patellar baja

• Distalize to address

patellar alta

Biologic or Prosthetic Resurfacing ????

Key decision making point

• Multifactoral decision

– Lesion: focal or diffuse – Patient Factors – Comorbidities – Osteophytes – Bipolar – Resources Available

Inverted patella of 19 yr old male

Radiographic Guide to Bio vs. Prosthetic

Kellgren-Lawrence Grading Scale

Generally Biological Resurfacing…… Grade 0 = Normal Grade 1 = Doubtful narrowing of the joint space and possible osteophytic lipping Grade 2 = Definite osteophytes, definite narrowing of the joint space Generally Prosthetic Resurfacing….. Grade 3 = Moderate multiple osteophytes, definite narrowing of joints space, some sclerosis and possible deformity of bone contour Grade 4 = large osteophytes, marked narrowing of joint space, severe sclerosis and definite deformity of bone contour.

KL 1 KL 4

Biological Options

• Scaffolds
• Cell Therapy
• Osteochondral Grafts

– Autogenous

• Limited use

– Allograft

• Fresh stored
• Cryopreserved
• Cartilage Grafts

– Minced, ground, lamellar – Cryopreserved – Non-viable (scaffold)

Inlay vs Onlay Patella – Biologic

What if biologics will not or cannot work? …Transitioning the algorithm from biologics to prosthetics

Prosthetics - Joint Resurfacing

Onlay vs Inlay Joint Resurfacing - Patella

• Inlay useful for focal

defects and for “normal” morphology

• Onlay needed for

diffuse chondral disease or “abnormal” morphology

• I use Onlay MUCH

more frequently

Onlay vs Inlay Joint Resurfacing for FTG

• Onlay device replaces

anatomy, but may add unwanted volume

• Inlay device based on ambient

anatomy

• Inlay device allows for

concurrent realignment

• Inlay device inherently stable
• Inlay typically more anatomic

Onlay

I nlay

PFA “legacy onlay implants” very negative history

• Non-anatomical
• Overstuffed the joint
• Encroach on TF joint
• Very mixed, negative

results with high revision rates

• Did not allow for

concurrent alignment!!

Patellar-Trochlea alignment

Key step- Patella directly over FTG

Summary

• Must establish alignment
• Want to accommodate

potential revision to TKA

• Cannot have plastic on

cartilage (no poly patella alone)

• Resurfacing must be done

in context of anatomy/deformities

• No Overstuffing

Thank You

phildavidsonmd@gmail.com