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  1. 1. Patellofemoral Instability
  2. 2. • Spectrum of disorders• LPCS –C/c subluxation –Recurrent dislocation
  3. 3. C/c Subluxation“Instabilities rotuliennes potentielles”-Dejour• Patellar pain when routine views /CTreveals lateral displacement
  4. 4. Recurrent Dislocation• Second decade• Female preponderance / Athletic males• Initial episode of dislocation• Subsequent episodes of instability• Frequency decreases with Age(Crosby)
  5. 5. Chronic dislocation• Knees in which patella dislocates laterallyeach time knee is flexed and returns tomidline in extension(Habitual dislocation)• More severe –patella permanently dislocated–(Permanent dislocation)
  6. 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. 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. 8. Classification based on 2independent 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. 9. • Age of onset decreased from grade 1 to 4• Bilateral dislocations increased from grade 1 to 4• Incidence of moderate trauma decreased from 1to 4
  10. 10. Passive soft tissue stabilizers• Anchored by 4 structuresin cruciform pattern
  11. 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. 12. Examination• Sequentially in Standing ,walking ,sittingsupine 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. 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 transepicondylar line with knee at 90 deg/tuberclesulcus angle(> 10 deg Abn.)
  14. 14. Supine• Tenderness and swelling• Retinacular structures• Palpation of patellar surfaces• Compression• Passive patellar tilt• Mobility in Extension and 30deg flexion(inQuadrants)
  15. 15. Patellar tilt( Kolowich & Poulos)
  16. 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. 17. Q angle• In Extension- may be normal as patella isdisplaced laterally• Standing- Fulkerson• Standing increases Q angle by 0.9-1.2deg(m/f)(Woodland & Francis)-Clinically notsignificant
  18. 18. Q angle• Knee flexion 30 deg-(Fithian) –Patellaentering sulcus– Control 12 deg, dislocations 19.2 deg• Knee flexion 90 deg –Patella firmly fixed introchlea
  19. 19. Tracking• Sequence of events-patella enters trochleafrom SL position at 10 degree flexion ,anddrawn into trochlea with increasing flexion• J sign- tracks laterally in early flexion andthen shifts medially with active or passiveflexion(also test in active extension)• Lateral pull test-Contract quads with kneein extension-Predominant lateralmovement
  20. 20. Apprehension test of Fairbank• Patella pushed laterally in 20-30 deg offlexion
  21. 21. Tests for medial instabilityAlways a complication of realignment• Can medially displace patella and flexknee,reproducing symptoms as patella movesinto trochlea.• Gravity subluxation test-inability of vastuslateralis to reduce patella in lateral position.
  22. 22. Radiology• AP view –for alignment• Lateral view in at least 30 degree flexion– To assess relation ship between patella andpatellar tendon,Height of patella(PA assosc withsublx disloc trochlear dysplasia)– Trochlear depth and Dysplasia• Axial Views
  23. 23. Radiology• Lateral views– Blumansaat’s line• Difficult to obtain true lat view• Often inaccurate• Patella often above line
  24. 24. Radiology- Insall Salvati Ratio• T –Length measured on deepsurface• P-greatest diagonal length ofpatella• Average T/P=1.02 SD 0.13(Insall)1.04SD0.11( Aglietti)>1.2 Patella Alta,<0.8 Patella infera
  25. 25. Other Indices on Lateral viewIf distal reallignement done• Blackburne and Peel ratio• Lyon School-Caton ratio• Norman IndexBlackburneNormanCaton
  26. 26. 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
  27. 27. 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
  28. 28. Merchants View• Congruence angle measures relation ship ofpatella to sulcus• Sulcus angle is bisected• line drawn from apex of sulcus angle tolowest point on articular ridge of patella• Angles lateral to zero line -positive ,medialnegative• Normal N=100,M=F; sulcus angle138(sd6)Congruence angle-6(sd11) RDPgroup CA +23deg(Merchant)• Other studies -SA similar CA sd 4deg
  29. 29. Laurin’s view• Lateral patellofemoral angle is measured• Open laterally in normal knees• Open medially or parallel in recurrentdislocations• Patellofemoral index -Ratio of medial tolateral interspace
  30. 30. CT• Significant advantage– Avoids problems associated with positioning,obesityetc– Avoid image overlap and distortion• Evaluation in early flexion informative(0-30)-levelmid patellar transverse(Fulkerson)• Look for– sulcus angle, tilt ,congruence and subluxation• Reference line tangential to posterior condylesmore accurate• TT-SF distance(N12ext,>20 abn,8.7at 30)-– disav
  31. 31. 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
  32. 32. MRI
  33. 33. Arthroscopy• Patellar tracking• abnormal if ridge does not seat in trochlea by45deg(Grana)• Typical signs of lateral tracking-”emptysulcus”&”Lateral overhang”(Metcalf)• Trans patellar approach marginally betterthan superolateral portal for tracking,and 70deg scope
  34. 34. Arthroscopic assessment oftracking• Normal -ridge of patella reduces intotrochlea 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
  35. 35. • Patellar articular changes• Centralization behavior with quad contraction
  36. 36. Management• Non Operative management• To be attempted in all patients.• Goals –Normal flexibility,Balanced quadricepsstrength,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)
  37. 37. Quadriceps Training• Most essential component• Strengthening of quads esp. VMO• Isometric and progressive resistive ex. with kneein extension• With increase in strength,Short arc exercises inlast 300• Knee braces with patella cut outs and lateralpadding –some relief.
  38. 38. MC Connell’s Rehab• Based on appreciation of alterations in entirelimb• Muscle tightness in all groups identified andcorrected• IT and lateral retinaculum band stretched bymedial patellar glide and tilt• If pronation foot present,Supination ex/orthosis• VMO training after lateral retinacular stretch• Taping of patella
  39. 39. Who benefits from Mc Connel’sprogramme?• Isometric quad in 120,90,60,30deg;holdcontraction 10 secs• If pain relieved by repeating with patellapushed medially
  40. 40. Surgical treatment• Once a specific malaligment problem hasbeen identified a surgical option can beselected• Almost all techniques include Lateralrelease.• Procedures to decrease laterally directedvector may be proximal distal or combinedrealignment
  41. 41. Lateral release• Arthroscopic and open• Most Authors advice release to include VLO andpatellotibial ligament for optimal results• Patella should be tiltable by 70-90 degree at end ofprocedure• Results varied(100%-30%) ,good results in shortterm(metcalf,Simpson),poorer in long term(Christensen)
  42. 42. Predictive factorsAglietti n 21• Poorer results in• Females• >5 dislocations• Persistent lateral tracking clinically• Deficit at 1 leg hop test >15 %
  43. 43. Lateral release /Medialimbrication• Alters line of pull of quadriceps• Does not alter Q angle or length of patellartendon• 2 components –Lateral release + lateral anddistal advancement of medial structures in line ofVMO• Insall,Scuderi• Results 91-62%• Best results if patella centered at end ofsurgery
  44. 44. Arthroscopic lateral releasemedial plication• Produces shortening of medial patellofemoralligament which is primary restraint to lateralsubluxation• Distal extension to tibialtuberosity(Patellomeniscal & Patellotibialligaments) additional support
  45. 45. Distal realignment• Theoratically reduces Q angle and thus the laterallydirected moment• Medialization is often associated withposteriorization and increased PF stresses(Hauser,Hughston,)• Maltracking controlled but pain & OA in long term• Avoided by Oblique Osteotomy (AM of Fulkerson)or Withgraft (Roux-Elmslie -Trelatt )procedures• Unsuitable in open Physes• Elevation of tibial tubercle reduces stress ,increaseslever arm(Macquet,Bandi)• Long patellar tendon –distallization• VMO function improves myographically-Caruso
  46. 46. Distal soft tissue realignment• ?in Skeletally immature patients• Roux Goldthwaite-lateral patellar tilt• Galeazzi -semimembranosus tenodesis topull patella medially and distally• Results variable• Allinclude lateral release and medalimbrication• ?is it really required
  47. 47. 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 angularmalallignment• Medialization with lateral release• Tilt subluxation +articular change– Include anteriorization also• Subluxation -• medialization primary goal• Children-• LR+medialimbricatio,rarely Galeazzi
  48. 48. Aglietti&Insalls recommendation• Isolated lateral release-40%redislocation,40%+congruence• Realignment surgeries –effective in preventingdislocation ,but anatomy not restored-lateral tracking +in 57%interminal extn.• Congruence best corrected with proximal followed bycombined and least by distal.• Medial soft tissue with proximal realignmentmajor role in centralizing and congruence
  49. 49. Suggested procedure• Pre and intra op planning– Patellar height by Insall and Caton(aim1) If high,distaltransposition req,amount calculated– Medial transposition calculated by TT-SFdistance(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 checktracking 0-90deg, tighten
  50. 50. ThankYou
  51. 51. Insall
  52. 52. HauserFulkerson
  53. 53. • Elmslie Trillat• Hughston
  54. 54. • Table 31-1. Repair of patellofemoral instability• Determining factors Procedure• Lateral pain, lateral tilt, mild lateral Arthroscopic lateral releasesubluxation, tight lateral structures, Q angleand Insall index WNL• Acute dislocation with associated• osteochondral fragment or high-level• athlete at end of season Arthroscopeand repair ofmedial patellofemoral ligament and medial retinaculumModified Elmslie-Trillat lateral release andRecurrence with Insall index <1.2 and Q anglenear 20 degrees•medial tuberosity transfer may just perform• arthroscopic evaluation and medial tuberosity transfer if there is no evidenceof lateral tightness• Recurrence with Insall index >1.2
  55. 55. • 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