Patellofemoral Instability
Patellofemoral Instability
• Spectrum of disorders • LPCS –C/c subluxation –Recurrent dislocation
C/c Subluxation “Instabilities rotuliennes potentielles”-Dejour
• Patellar pain when routine views /CT reveals lateral displacement
Recurrent Dislocation
• Second decade • Female preponderance / Athletic males• Initial episode of dislocation• Subsequent episodes of instability • Frequency decreases with Age(Crosby)
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)
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
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%
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 +
• 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
Passive soft tissue stabilizers
• Anchored by 4 structures in cruciform pattern
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
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
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.)
Supine
• Tenderness and swelling • Retinacular structures • Palpation of patellar surfaces • Compression • Passive patellar tilt• Mobility in Extension and 30deg flexion(in
Quadrants)
Patellar tilt( Kolowich & Poulos)
Q angle
• Values vary-male 14 deg Female 17 deg > 20 Abn
• How to test –– extension– standing – Supine– knee flexion30deg or 90 deg
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
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
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
Apprehension test of Fairbank
• Patella pushed laterally in 20-30 deg of flexion
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.
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
Radiology
• Lateral views
– Blumansaat’s line• Difficult to obtain true lat view • Often inaccurate• Patella often above line
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
Other Indices on Lateral viewIf distal reallignement done
• Blackburne and Peel ratio• Lyon School-Caton ratio• Norman Index
Blackburne
Norman
Caton
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
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
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
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
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
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
MRI
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
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
• Patellar articular changes• Centralization behavior with quad contraction
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)
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.
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
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
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
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)
Predictive factorsAglietti n 21
• Poorer results in• Females• >5 dislocations • Persistent lateral tracking clinically• Deficit at 1 leg hop test >15 %
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
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
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
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
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
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
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
ThankYou
Insall
Hauser
Fulkerson
• Elmslie Trillat
• Hughston
• Table 31-1. Repair of patellofemoral instability• Determining factors Procedure
• Lateral pain, lateral tilt, mild lateral Arthroscopic lateral release subluxation, tight lateral structures, Q angleand 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 anglenear 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• Lateral release with distalization and• medialization of tibial tuberosity (Simmons• procedure)• Recurrence with grade 3 to grade 4• chondromalacia• Oblique Fulkerson type osteotomy leaving at least one third of postmedial cortex intact• •
• 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• Open• Highly competitive athlete near end of• season• Proximal extensor• realignment• Subluxation or dislocation• Insall; Madigan et al.• Q angle <20 degrees• Distal extensor• realignment• Recurrent subluxation or dislocation• Roux-Goldthwait;• Galeazzi• Q angle >20 degrees, skeletally• immature (soft tissue realignment)• Q angle >20 degrees, skeletally• mature• Elmslie-Trillat• Proximal and distal• realignment• Recurrent dislocations, skeletally• mature, Q angle approaching 20• degrees• Hughston; modified• Elmslie-Trillat• Patellectomy with• extensor realignment• Skeletally mature, salvage procedure• West and Soto-Hall