This document discusses patellofemoral disorders, including their anatomy, biomechanics, pathology, and treatment. It describes the anatomy of the patella and trochlea, as well as medial and lateral stabilizers. Biomechanics discussed include joint reaction forces, contact areas and pressures. Pathologies include traumatic injuries, atraumatic causes like chondromalacia and malalignment syndromes. Treatment depends on factors like age, cartilage damage, and underlying causes; it ranges from conservative options to various surgical procedures. The take home message is that patellofemoral disorders require careful evaluation of the whole limb and conservative treatment first before considering surgery.

1. What we should know about:
Patellofemoral disorders
AKRAM ALDAWOUDY, Mch.orth., FRCS

2. Patellofemoral disorders
•Anatomy
•Biomechanics
•Pathology
•Common clinical entities

3. Anatomy
The patella
•Patella is the largest sesamoid bone
•Thickest articular cartilage in the body
•Up to 5mm at central ridge
•Articular surface is divided into the lateral
facet and the medial facet
•Four different anatomical shapes probably
the result of the stress imposed on it.

5. Anatomy
The trochlea
•Asymmetric medial and lateral facets, with
the lateral facet little more prominent and
more proximal
•The greater height of the lateral facet of the
trochlea and the congruence between the
sulcus and the ridge are important for stability
and constitutes a structural bony stabilizer.

7. Anatomy
Medial Stabilizers
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Medial retinaculum
Including medial patellofemoral ligament
MPFL runs from medial border of patella to
adductor tubercle
75% restraining medial force
Vastus Medialis obliquus
Pulls at 55 to 70 degrees

8. Anatomy
Lateral Stabilizers
•Lateral retinaculum
•Superficial attaches to ITB
•Deep, 3 bands
•Connects to IT band, tibia, & lateral epicondyle
•IT band moves posteriorly in flexion
•Contributes to tilt and subluxation
•Vastus lateralis
•Main muscle inserts proximally at angle of 31 deg
•Vastus lateralis obliquus
•Distinct distal portion from lateral intermuscular septum

10. Biomechanics
•The patalla pushes away the patellar tendon
from the femorotibial contact point, increasing
the patellar tendon moment arm (pulley
action)
•Centralization of the divergent forces and
transmit them in a frictionless way to the tibial
tubercle
•Thichest articular cartilage, highiest
compressive forces

11. Biomechanics
•Joint reaction forces, the result of the tension
developing in the quadriceps and patellar
tendons (multiples of body weight)
•0.5 level walking
•3.3 stair climbing
•7.8 squats
•Patellofemoral contact areas, moves
proximally and broadens with increasing
flexion.

13. Biomechanics
•Patellofemoral contact pressure, ratio of
patellofemoral reaction ferce to patellofemoral
contact areas, most important
•Patellofemoral contact pressure increases
with patellar malpositioning, as patellofemoral
contact areas decrease

14. Angle of pull of the
quadriceps (Q-angle)
Line drawn from ASIS
to Mid-patella and
Line drawn from
mid-patella to tibial
tubercle
Normal Q angle= 15

15. Pathology
•Traumatic:
bony
chondral
ligamentous
Merchant’s
classification, sophisticated, though
comprehensive
•Atraumatic, Insall classification

16. Insall Classification
•Presence of cartilage damage
chondromalacia
Osteoarthritis
osteochondritis dissicans
•Variable cartilage damage
malalignement syndromes
synovial plicae
•Usually, normal cartilage
peripatellar causes: bursitis, tendinitis
Overuse syndromes
Reflex sympathetic dystrophy
Patellar abnormalities

17. Pathology
•Primary OA
•Pat fem maltraching

18. Chondral Pathology
•Diagnosis
•history: pain on getting to stairs and on
kneeling, clicking, age, trauma
• Clin. exam: patellar squeeze, tender
undersurface, tend lat.retinaculum
•Imaging: plain probably enough, MRI ?!!!
ALWAYS LOOK FOR AN
UNDERLYING FACTOR

20. Chondral Pathology
•Treatment:
still a problem, especially in young pts.
Depends on:
•Age of the pt., age of the knee
•Generalized or localized lesions
•Underlying factor, Maltraching
•Stage of the disease

21. Chondral Pathology
•Conservative management
should be always tried first
Rest
Reduction of wt.
Restriction of activities
Quadriceps training
NSAIDS
PT

22. Chondral Pathology
•Treatment:
•Operative,
DECECION CATIOUSLY TAKEN
•Correction of the underlying
maltraching
•Lateral retinacular release, may lead to
worse results ??!!
•Articular cartilage management, from
cell to metal

23. Chondral Pathology
•Arthroscopic debridement/chondroplasty
•Microfracture
•Chondral grafts
•ACI
•Generally less successful than for condylar
lesions
•Anterior Displacing Osteotomies
•Fulkerson
•angled for less medialization
•Maquet
•avoid huge grafts

24. Chondral Pathology
•Patellectomy
Mainly of historical interest
•Patellofemoral arthroplasty
Generally for older, lower demand patients
Not as well proven as TKA
•TKA
Gold standard if coexistent femoral-tibial
arthritis
Reasonable in older, low demand patients with
severe PF and some other compartment
disease

25. Maltraching
A- Acute dislocation:
•Usually presents to A&E after an injury!!
Easy reduction
•Often hemarthrosis
•If aspiration returns fat then suspect fracture
•40% risk of osteochondral injury
•Many missed on Xray
•MRI better
•Most often medial patellar facet and lateral
femur
•Most often underlying alignment issues

28. Maltraching
•Treatment of acute form:
•Extend knee to reduce
•If x ray changes, fat in joint, or crepitus
consider scope
•Physical therapy
•Primary repair of MPFL only in selected pts.
•50% will probably need eventual surgery
•Early interveniton may increase chronic pain
and arthrofibrosis

29. Maltraching
B-The chronic form:
•May present with pain and/or mechanical
symptoms
•Medial and lateral patellar translation
Compare medial to lateral and side to side
Apprehension test

30. Careful planning

31. Maltraching
Consider:
•Overall limb alignment, valgus knee, valgus
heel, femoral anteversion…
•Trochlear geometry
•Patellar tilt
•Quadriceps function
•Age, style of life …
•Beware of hyperlaxity, bilaterality
•Rotational alignment of the whole limb
•Degree of sublaxation
•Only dynamic instability !!!
•Degree of articular cartilage pathology
• J-sign, pat height

32. Q
Q

34. Maltraching
•Radiology
•Good quality x rays
•Whole leg standing films
•Tangential views
•CT
•MRI ??!!!

35. Maltraching
Conservative treatment
•Rest, Ice, NSAIDS
•Physical therapy
•Should be tried for several months before
more aggressive measures
•Avoid aggressive quad strengthening if pain
important
•Patellar tracking braces
•Avoidance of offending activities

36. Maltraching
Surgical treatment:
tailored for every pt. indiviually
•Lateral release: Probably to be done with
lateral patellar compression syndrome
•Distal realignment:
Transfer, anterior, anteromedial, posterome
dial (not done)
Osteotomies, valgus knees

38. Maltraching
•Proximal realignment:
Trochleoplasty, Good results in well
selected cases, open and recently !!!
arthroscopic
MPFL reconstruction
“advancement”, commonly done
now, different techniques, isolated gracilis
graft or a strip of patellar tendon

40. Take home message
•Patellofemoral joint disorders one of the very
complex issues
•Look at the limb as a whole
•Conservative measures always come first
•Surgery may be devastating if not carefully
planned for
•Lateral release over done ??!!
•MPFL reconstruction coming to be a
standard procedure