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