Patellofemoralinstability: what’s new?

Pr Jacques MenetreyCentre de Médecine du Sport et de l’’Exercice (CMSE)

Hirslanden Clinique la CollineGenève SuisseHUG, Genève

Faculté de médecine, Université de Genève

Outline

Intro Patella height – patella engagement MPFL ? Trochleoplasty

Epidemiology

Incidence of primary patella dislocation:

6 to 112/100’000 persons Depending upon the age of the population

Nietosvaara et al J Pediatr Orthop 1994Fithian et al Am J Sports Med 2004 Sillanpaa et al Med Sci Sports Exerc 2008Colvin J Bone Joint Surg 2008Hsiao et al Am J Sports Med 2010

Mechanism of injury

Knee valgus stress and internal rotation of the femur with the foot fixed on the ground

Risk factors: Tall height and excess weight

Sillanpaa et al Med Sci Sports Exerc 2008Colvin J Bone Joint Surg 2008Nikku et al Acta Orthop 2009

Sillanpaa et al Med Sci Sports Exerc 2008

Challenge

44% to 70% recurrent dislocations Depending upon the patient cohort

Results in a partial or complete MPFL disruption 50-60% of the restraining force against lateral patellar

displacement

Stefancin et al COOR 2007Smith et al KSSTA 2011Hing et al Cochrane Database Syst Rev 2011

Conplan et al J Bone Joint Surg 1993Desio et al Am J Sports Med 1998Hautamaa et al Clin Orthop 1998

Major predisposing factors

1987

Major predisposing

factors

Major predisposing

factors

Trochlea dysplasiaTrochlea dysplasia

TT-TG > 20 mm

TT-TG > 20 mm

Patellar tilt > 20°Patellar tilt > 20°

Patella alta > 1.2Patella

alta > 1.2

Major predisposing

factors

Major predisposing

factors

Trochlea dysplasiaTrochlea dysplasia

TT-TG > 20 mm

TT-TG > 20 mm

Patellar tilt > 20°Patellar tilt > 20°

Patella alta > 1.2Patella

alta > 1.2

2012

Major predisposing factors

2012

Major predisposing

factors

Major predisposing

factors

Trochlea dysplasiaTrochlea dysplasia

TT-TG > 20 mm

TT-TG > 20 mm

Tear of the MPFLTear of

the MPFL

Patella alta > 1.2Patella

alta > 1.2

Major predisposing factors

Patella alta

Measure of patella height

Caton-Deschamps index:

infera AT/AP < 0.6 normal 0.6 ≤ AT/AP ≤ 1.2 alta 1.2 < AT/AP

Sagittal Patellofemoral Engagement (SPE)

SPE index: 2 cuts:

Longest patellar cartilage surface Longest trochlear cartilage

PL/TL: 0.42 normal PL/TL: <0.39 beware

Dejour D OTSR 2013

Sagittal Patellofemoral Engagement (SPE)

Dejour D OTSR 2013

Caton-Deschamps: 1.66SPE index: 0.88

Sagittal Patellofemoral Engagement (SPE)

Dejour D OTSR 2013

Caton-Deschamps: 0.81SPE index: 0.19

Patella alta Distalisation osteotomy of the TT

Objective: index Caton-Deschamps = 1

Always before the MPFL reconstruction !!

Associated tenodesis of the patellar if > 52 mm

Attention: distalisation medializes automatically of 4 mm

Mayer C. et al. AJSM 2012

Servien E. RCO 2004

Surgical ttr

Avulsion du MPFL sur la patellaP0 P1 P2

Only P2 lesions are susceptible to surgical fixation

Sillanpää P. et al. KSSTA 2014

Surgical ttr

Osteochondral fracture of the patella

Surgical ttr Osteochondral fracture of the patella :

fixation by resorbables pins

Surgical ttr Osteochondral fracture of the lateral condyle :

fixation by resorbable pins

Recurrent dislocations - Ttr “à la carte”

Predisposing factors Normal Surgical ttr

MPFL disrupted MPFL competent Reconstruction of MPFL

TT-TG > 20 mm TT-TG = 12 mm ± 4 mm Medialisation osteotomy of the TT

Patella alta-Index C-D > 1.2

- patellar tendon > 52 mm

Index de C-D = 0.8 – 1Patellar tendon = 42 mm

Distalisation osteotomy of the TT ± tenodesis of the patellar

tendon

Trochlea dysplasia type B or D Normal trochlea Deepening trochleoplasty

MPFL Medial PatelloFemoral Ligament (MPFL) 50-60% of the restraining force against lateral patellar

displacement (Primary stabiliser) Passive restrainer

MPFL

Types of graft: - Gracilis or semi-tendinosus tendon - Quad tendon - Patellar tendon- Fascia lata

Reconstruction of the MPFL

Graft tensioning Objective: to restore native MPFL tension

- Tensioning at 30-60° of flexion

- Graft tensioning in extension with a proximal traction in the patella

Fithian DC. et al. Tech Knee Surg 2006

Christiansen SE et al. Arthroscopy 2008Deie M. et al. JBJS 2003Nomura E et al. AJSM 2007

Reconstruction of the MPFL

Medialisation osteotomy of the TT Objective : 10 < TT-TG < 15

Always before the MPFL reconstruction !!

2

1

Reconstruction of the MPFL

And the solid science…

Stephen et al Am J Sports Med 2012

And the solid science…

The 40/50/60% rule

Stephen et al Am J Sports Med 2012

Radiological landmarks

Palpation

Isometry

Surgical orientation for femoral tunnel positioning in MPFL reconstruction

Radiological landmarks

Schöttle et al. Study on 8 cadaveric knees

Relatively uniform femoral insertion site of the MPFL

Schöttle et al Am J Sports Med 2007

Radiological landmarks – the downside 1 Redfern et al seeking to confirm Schöttle’s point Found difference of 5mm in the A-P and 7 mm proximal to distal

Redfern et al Am J Sports Med 2010

« Bony architecture varies as a consequence of weight bearing activity undertaken by the patients. Therefore, the posterior femoral cortex may not represent a consistent anatomic landmark for use in determination of the femoral tunnel »

Stephen et al Am J Sports Med 2012

Radiological landmarks -the downside 2

Barnett et al. Study on 10 cadaveric knees

Relatively uniform femoral insertion site of the MPFL

Barnett et al KSSTA 2012

Radiological landmarks - the downside 2

Barnett et al.Study on 10 cadaveric knees

In accordance with Schoettle pointMalrotation of 5-10° may lead to tunnel malplacement

Ziegler et alStudy on 10 cadaveric knees

4mm difference to Schoettle point5° of malrotation causes 7-9mm points displacement

Barnett et al KSSTA 2012Ziegler et al Am J Sports Med 2016

Surgical anatomy

The MPFL and its relation to: VMO

Quadriceps tendon

Posteromedial capsule

MCL prox insertion

Adductor tubercle

Nomura et al KSSTA 2005

Post-operative results

No recurrence of instability in 3-10%

25% of complications Up to 30% tunnel malpositioning

Up to 30% with medial knee pain

12-30% loose 10° or more of flexion

Steensen et al Am J Sports Med 2004Servien et al Am J Sports med 2012Shah et al Am J Sports Med 2012Enderlein et al KSSTA 2015

Post-operative results

Gobbi et al KSSTA 2016

Mr C. 20 y. old, football player3 years post-MPFL reconstruction. No recurrence of dislocation or even instability. But painful !

Trochleoplasty ?

Trochlea dysplasia 4 types

Reproducible and reliable classificationLippacher S. et al AJSM 2012Rémy F. et al. JBJS 2002

Trochlea dysplasia

Lateral facet-elevating trochleoplasty by Albee

Thin osteochondral flap byBereiter

Trochlea dysplasia

Sulcus-deepening trochleoplasty for type B and D dysplasia

Ntagiopoulos et al AJSM 2013, Ntagiopoulos et al KSSTA 2014

Take home message Management of primary acute patella dislocation can be

challenging as well as chronic patello-femoral instability Radiographs + MRI + Ct (?) Characterization of the MPFL lesion Characterization of the bony morphology

(patellofemorometry) Ttr « à la carte »

Principle

Patellofemoral stability

Static structural stabilizer

(ligaments)

Static structural stabilizer

(ligaments)

Dynamic structural stabilisers(muscles)

Dynamic structural stabilisers(muscles)

Osteo-articular

conformation

Osteo-articular

conformation