1. Patellofemoral Instability

2. • Spectrum of disorders
• LPCS –C/c subluxation –Recurrent dislocation

3. C/c Subluxation
“Instabilities rotuliennes potentielles”-Dejour
• Patellar pain when routine views /CT
reveals lateral displacement

4. Recurrent Dislocation
• Second decade
• Female preponderance / Athletic males
• Initial episode of dislocation
• Subsequent episodes of instability
• Frequency decreases with Age(Crosby)

5. Chronic dislocation
• Knees in which patella dislocates laterally
each time knee is flexed and returns to
midline in extension(Habitual dislocation)
• More severe –patella permanently dislocated
–(Permanent dislocation)

6. Causes
• Muscular (dynamic)
– Increased Q angle
– Unbalanced quad contraction(VMO vs VL)
• Static
– Anteversion neck
– Tibial torsion
– Hind foot pronation
– Lateral retinacular tightness
– Medial retinacular laxity-prerequisite
– Dysplasia patella,position,size
– Dysplasia Trochlea
– Gen lig laxity

7. Causes- Runow
• External –trauma
• Internal
– Abnormalities of patellofemoral joint
• High Insall index (>1.3)- C-2% P-41%
• Generalized laxity C-10-11% P56-69%

8. Classification based on 2
independent Variables
• Local ( patella Alta )&Systemic(Generalized laxity )
• Grade 1 Absence of both
• Grade 2 Gen laxity +no Alta
• Grade 3 P Alta + no lig laxity
• Grade 4 Both +

9. • Age of onset decreased from grade 1 to 4
• Bilateral dislocations increased from grade 1 to 4
• Incidence of moderate trauma decreased from 1
to 4

10. Passive soft tissue stabilizers
• Anchored by 4 structures
in cruciform pattern

11. Static stabilizers
• Lateral retinaculum
– Superficial and deep
– Deep –superior ,middle and inferior
• Medial retinaculum
– Medial patellofemoral ligament –53% RF
– Medial patellotibial ligament-22%RF
• Ligamentum Patellae

12. Examination
• Sequentially in Standing ,walking ,sitting
supine and prone
• With feet together
– Angular deformities
– Squinting of patellae
– Hip anteversion
– Bulk of quads and Bulk& attachment VMO
• Position of feet- look for Pronation

13. Sitting
• Bony components
• Position of patella in flexed knee
– Patella alta
– Frog eye patella(Hugston and Walsh)
• Tracking and movement
• Direction of patellar tendon to trans
epicondylar line with knee at 90 deg/tubercle
sulcus angle(> 10 deg Abn.)

14. Supine
• Tenderness and swelling
• Retinacular structures
• Palpation of patellar surfaces
• Compression
• Passive patellar tilt
• Mobility in Extension and 30deg flexion(in
Quadrants)

15. Patellar tilt( Kolowich & Poulos)

16. Q angle
• Values vary-male 14 deg Female 17 deg
> 20 Abn
• How to test –
– extension
– standing
– Supine
– knee flexion30deg or 90 deg

17. Q angle
• In Extension- may be normal as patella is
displaced laterally
• Standing- Fulkerson
• Standing increases Q angle by 0.9-1.2
deg(m/f)(Woodland & Francis)-Clinically not
significant

18. Q angle
• Knee flexion 30 deg-(Fithian) –Patella
entering sulcus
– Control 12 deg, dislocations 19.2 deg
• Knee flexion 90 deg –Patella firmly fixed in
trochlea

19. Tracking
• Sequence of events-patella enters trochlea
from SL position at 10 degree flexion ,and
drawn into trochlea with increasing flexion
• J sign- tracks laterally in early flexion and
then shifts medially with active or passive
flexion(also test in active extension)
• Lateral pull test-Contract quads with knee
in extension-Predominant lateral
movement

21. Apprehension test of Fairbank
• Patella pushed laterally in 20-30 deg of
flexion

22. Tests for medial instability
Always a complication of realignment
• Can medially displace patella and flex
knee,reproducing symptoms as patella moves
into trochlea.
• Gravity subluxation test-inability of vastus
lateralis to reduce patella in lateral position.

23. Radiology
• AP view –for alignment
• Lateral view in at least 30 degree flexion
– To assess relation ship between patella and
patellar tendon,Height of patella(PA assosc with
sublx disloc trochlear dysplasia)
– Trochlear depth and Dysplasia
• Axial Views

24. Radiology
• Lateral views
– Blumansaat’s line
• Difficult to obtain true lat view
• Often inaccurate
• Patella often above line

25. Radiology- Insall Salvati Ratio
• T –Length measured on deep
surface
• P-greatest diagonal length of
patella
• Average T/P=1.02 SD 0.13(Insall)
1.04SD0.11( Aglietti)
>1.2 Patella Alta,<0.8 Patella infera

26. Other Indices on Lateral view
If distal reallignement done
• Blackburne and Peel ratio
• Lyon School-Caton ratio
• Norman Index
Blackburne
Norman
Caton

27. Trochlear morphology
• Trochlear Depth
– Control av7.8mm,instability av 2.3,
<4mm pathol
• Trochlear Bump
– Normal 0.8mm,
Instability+3.2mm,threshold 3mm
• crossing sign
– 3types of dysplasia
– 2 Normal variants

29. Axial views
• Various Methods-often inaccurate ,irreproducible
• Jaroschy,Hughston & Walsh,
• Ficat&Hungerford 30, 60, 90 deg
• Merchant-2 angles measured-Sulcus ,congruence
• Laurins views
• Malghem &Maldague-Knee 30deg Tibia ER

30. Merchants View
• Congruence angle measures relation ship of
patella to sulcus
• Sulcus angle is bisected
• line drawn from apex of sulcus angle to
lowest point on articular ridge of patella
• Angles lateral to zero line -positive ,medial
negative
• Normal N=100,M=F; sulcus angle
138(sd6)Congruence angle-6(sd11) RDP
group CA +23deg(Merchant)
• Other studies -SA similar CA sd 4deg

32. Laurin’s view
• Lateral patellofemoral angle is measured
• Open laterally in normal knees
• Open medially or parallel in recurrent
dislocations
• Patellofemoral index -Ratio of medial to
lateral interspace

34. CT
• Significant advantage
– Avoids problems associated with positioning,obesity
etc
– Avoid image overlap and distortion
• Evaluation in early flexion informative(0-30)-level
mid patellar transverse(Fulkerson)
• Look for
– sulcus angle, tilt ,congruence and subluxation
• Reference line tangential to posterior condyles
more accurate
• TT-SF distance(N12ext,>20 abn,8.7at 30)-
– disav

35. CT classification of mal alignment
• Type 1 -Subluxed with out tilt
• Type 2-Subluxed with tilt
• Type 3 tilt with out Sublux
• Type4 normal alignment

36. MRI

37. Arthroscopy
• Patellar tracking
• abnormal if ridge does not seat in trochlea by
45deg(Grana)
• Typical signs of lateral tracking-”empty
sulcus”&”Lateral overhang”(Metcalf)
• Trans patellar approach marginally better
than superolateral portal for tracking,and 70
deg scope

38. Arthroscopic assessment of
tracking
• Normal -ridge of patella reduces into
trochlea by 10 deg flexion
– deg 1 subluxation-reduction bet 10-30 deg
– deg 2-reduction beyond 30deg(Lindberg)
• Other investigators-
– N upto 30
– Borderline 30-50
– Abnormal >50deg

39. • Patellar articular changes
• Centralization behavior with quad contraction

40. Management
• Non Operative management
• To be attempted in all patients.
• Goals –Normal flexibility,Balanced quadriceps
strength,Stretching of tight lateral structures
• Entire extremity included in rehabilitation
• Most important component –Quadriceps training
• Evaluation of Non operative treatment-
Satisfactory result-50%, Recurrence 46%(Garth)

41. Quadriceps Training
• Most essential component
• Strengthening of quads esp. VMO
• Isometric and progressive resistive ex. with knee
in extension
• With increase in strength,Short arc exercises in
last 300
• Knee braces with patella cut outs and lateral
padding –some relief.

42. MC Connell’s Rehab
• Based on appreciation of alterations in entire
limb
• Muscle tightness in all groups identified and
corrected
• IT and lateral retinaculum band stretched by
medial patellar glide and tilt
• If pronation foot present,Supination ex/
orthosis
• VMO training after lateral retinacular stretch
• Taping of patella

43. Who benefits from Mc Connel’s
programme?
• Isometric quad in 120,90,60,30deg;hold
contraction 10 secs
• If pain relieved by repeating with patella
pushed medially

44. Surgical treatment
• Once a specific malaligment problem has
been identified a surgical option can be
selected
• Almost all techniques include Lateral
release.
• Procedures to decrease laterally directed
vector may be proximal distal or combined
realignment

45. Lateral release
• Arthroscopic and open
• Most Authors advice release to include VLO and
patellotibial ligament for optimal results
• Patella should be tiltable by 70-90 degree at end of
procedure
• Results varied(100%-30%) ,good results in short
term(metcalf,Simpson),poorer in long term(Christensen)

46. Predictive factors
Aglietti n 21
• Poorer results in
• Females
• >5 dislocations
• Persistent lateral tracking clinically
• Deficit at 1 leg hop test >15 %

47. Lateral release /Medial
imbrication
• Alters line of pull of quadriceps
• Does not alter Q angle or length of patellar
tendon
• 2 components –Lateral release + lateral and
distal advancement of medial structures in line of
VMO
• Insall,Scuderi
• Results 91-62%
• Best results if patella centered at end of
surgery

48. Arthroscopic lateral release
medial plication
• Produces shortening of medial patellofemoral
ligament which is primary restraint to lateral
subluxation
• Distal extension to tibial
tuberosity(Patellomeniscal & Patellotibial
ligaments) additional support

49. Distal realignment
• Theoratically reduces Q angle and thus the laterally
directed moment
• Medialization is often associated with
posteriorization and increased PF stresses(Hauser
,Hughston,)
• Maltracking controlled but pain & OA in long term
• Avoided by Oblique Osteotomy (AM of Fulkerson)or With
graft (Roux-Elmslie -Trelatt )procedures
• Unsuitable in open Physes
• Elevation of tibial tubercle reduces stress ,increases
lever arm(Macquet,Bandi)
• Long patellar tendon –distallization
• VMO function improves myographically-Caruso

50. Distal soft tissue realignment
• ?in Skeletally immature patients
• Roux Goldthwaite-lateral patellar tilt
• Galeazzi -semimembranosus tenodesis to
pull patella medially and distally
• Results variable
• Allinclude lateral release and medal
imbrication
• ?is it really required

51. What to Do?-Post &Fulkerson
• Tilt-Recognized clinically radiology/CT
– Can cause soft tissue pain-
• Neuromatous degen tight lat/medial stretch.
• Non Operative
• Lateral release
• Tilt + Subluxn
– Lateral release alone does not improve coronal and angular
malallignment
• Medialization with lateral release
• Tilt subluxation +articular change
– Include anteriorization also
• Subluxation -
• medialization primary goal
• Children-
• LR+medialimbricatio,rarely Galeazzi

52. Aglietti&Insalls recommendation
• Isolated lateral release-40%redislocation,40%
+congruence
• Realignment surgeries –effective in preventing
dislocation ,but anatomy not restored-lateral tracking +in 57%in
terminal extn.
• Congruence best corrected with proximal followed by
combined and least by distal.
• Medial soft tissue with proximal realignment
major role in centralizing and congruence

53. Suggested procedure
• Pre and intra op planning
– Patellar height by Insall and Caton(aim1) If high,distal
transposition req,amount calculated
– Medial transposition calculated by TT-SF
distance(disadvantages)
• Intra op SST angle(N@16degAN@25)
Adv-Limb positioning, Intra op assessment,not on patient size
• Lateral retinacular release VLO to TT
• Wide medial arthrotomy
• Tibial tubercle osteotomy- horizontal /oblique
– Medial and distal advancement,fix after checking Q angle
• Medial plication at correct tension,at 30deg check
tracking 0-90deg, tighten

54. ThankYou

55. Insall

56. Hauser
Fulkerson

57. • Elmslie Trillat
• Hughston

58. • Table 31-1. Repair of patellofemoral instability
• Determining factors Procedure
• Lateral pain, lateral tilt, mild lateral Arthroscopic lateral release
subluxation, tight lateral structures, Q angle
and Insall index WNL
• Acute dislocation with associated
• osteochondral fragment or high-level
• athlete at end of season Arthroscopeand repair of
medial patellofemoral ligament and medial retinaculumModified Elmslie-
Trillat lateral release and
Recurrence with Insall index <1.2 and Q angle
near 20 degrees
•
medial tuberosity transfer may just perform
• arthroscopic evaluation and medial tuberosity transfer if there is no evidence
of lateral tightness
• Recurrence with Insall index >1.2

59. • Table 31-2. Operative treatment of recurrent subluxation or dislocation of patella
• Operative procedure
• Indications
• Techniques
• Lateral retinacular
• release
• Recurrent subluxation
• Open
• Relatively normal Q angle
• Arthroscopic
• Tight lateral structures
• Lateral tilt with minimal lateral
• subluxation on roentgenogram in
• combination with realign-ment
• procedure
• Repair of medial
• patellofemoral ligament
• and VM
• Acute or subacute dislocation in
• association with osteochondral
• fracture