Patellofemoral Instability: Perfecting the Distal Realignment and - - PowerPoint PPT Presentation

Patellofemoral Instability: Perfecting the Distal Realignment and Outcomes Jason L. Koh, M.D.

Board of Directors Endowed Chairman North Shore University Health System Clinical Professor University of Chicago Board Member, Patellofemoral Foundation

Thoughts

• Bone trumps soft tissue
• Significant bony malalignment = bony procedure
• Repairs of weak tissue are…weak
• Primary repair increased failures with dysplasia
• Fixing pathoanatomy may require several parts

Who needs a tibial tubercle

• steotomy?
• Instability – patients with significant bony

abnormality / alta

• Unloading chondral lesions
• Can be combined with cartilage procedures

Anterior Tibial tubercle – Trochlear groove (ATT-TG) Distance

• Objective, reliable
• > 15 mm abnormal
• > 20 mm “Objective

patella instability (OPI)”

• I would consider distal

realignment

• Can be done w/MRI
• (Dejour)

Patella height

• ALL RATIOS 1:1 + 0.2
• Blackburn-Peel (most

reliable) A:Y

• Caton A:X
• Insall-Salvati B:Z
• Consider distalization if

>1.4

Tubercle realignment for instability

• No need for significant anteriorization
• Relatively flat shingle
• Consider distalization by up to 1 cm if

necessary (usually not)

• Goal is about 1.2:1 ratio

Patella alta – goal 1.2

Unloading procedures (tibial tubercle)

• Fulkerson oblique
• steotomy
• Anterior –

medialization of tubercle

• Very reliable for

appropriate lesion

Biomechanics of Fulkerson osteotomy

• Anteriorize – shifts load proximal
• Medialize – shift load medial

Results (Pidoriano and Fulkerson)

• results depending on location of defect
• distal , lateral facet of patella or lateral trochlea
• NOT for CENTRAL, DIFFUSE, or PROXIMAL

Technique: Workup

• MRI if lesion appropriate
• Distal, lateral patella; lateral trochlea

Assess articular cartilage arthroscopically

• Evaluate for other articular cartilage lesions

Lateral cartilage lesion

Skin incision centered on tubercle

• For smaller degrees of correction, can use

shorter shingle (5cm)

• For significant anteriorization, consider longer

shingle (7cm)

Define medial and lateral borders of tubercle and patella tendon

• Open anterolateral fascia and elevate musculature
• Avoid going deep to septum
• Note small perforators at proximal edge
• Determine obliquity of shingle
• Taper shingle to distal tip, leave 2-3 mm distally

unless distalizing

• Osteotomy angled medial to lateral and proximal to distal
• use small oscillating saw (ACL type saw) and irrigate
• Soft tissue protected with retractors

Oscillating saw

Finish proximal portion with curved

• steotomes

Osteotomes

Note oblique osteotomy

Osteotomy anteromedially translated

• Measure distance translated
• Provisionally fixed with k wire

Measurement

Assess patellofemoral tracking arthroscopically to see if lesion is unloaded

Scope

Fix tubercle with lag technique

• I use 2 4.0 headless variable pitch screws or 3.5

screws

• Can use 4.5 screw – but will have to remove many
• Knee is flexed to 90 degrees and posterior

neurovascular tissues allowed to fall away

Fixation

Stabilize shingle

Assess tubercle radiographically in AP

And lateral; grab posterior cortex with screw

Closure and Rehab

• Leave fascia open
• Allow ROM
• Patella mobilization
• Progress to full weightbearing at 6 – 8 wks
• Early WB runs a risk of later stress fracture of

the tibia at proximal osteotomy site (Fulkerson, SCOI experience)

• CPT code distal realignment 27418

Caveats

• Avoid over medialization
• Watch patella tracking after provisional fixation
• I try for slight lateral initial touch of patella
• Neurovascular structures are close posteriorly

(Kline et al)

• Avoid early weightbearing (Fulkerson, Stetson)
• Risk of nonunion of tuberosity relatively small

Results

• Allow progression of activity
• Typically will take 4-6 months for sport
• Extensor lag may persist for 6-8 months
• May have progression of patellofemoral

arthritis requiring further surgery; however, in most cases, results are durable

• Combined results with cartilage procedures

may be better

Results

• Roux-Goldthwaite: 14% redislocation, 25%

arthritis (Sillanpaa CORR 2008)

• AMZ: 31 patients, 4.4 yrs: 1 redislocation, 1 tip

fx, 2 hardware removal (Ding Injury 2015)

• Fulkerson 93% good-excellent at 5 years
• Jim Bradley – AJSM 2010 – 41 Fulkersons in

34 athletes – avg age 20; mean fu 46 months

• 97% return to sport w/o recurrence

Complications

• Nonunion – may have delayed union
• Preservation of tip attachment may decrease
• Shingle fracture – 1 case reported by Cosgarea
• Proximal tibia fracture – associated with early

WB (SCOI, Fulkerson)

• (I had one associated with a fall down the

stairs)

Overmedialization

Tubercle realignment: TTTG >20 mm

• r patella alta ratio >1.4
• Avoid over medialization
• Goal distalize 1.2; medialize to

TTTG 10-15 mm

Over distalization

Revision

Thank you!