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