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Peripheral Musculoskeletal Science > Patellofemoral Joint > Flashcards

Patellofemoral Joint Flashcards

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1
Q

describe the patellofemoral joint

A

❖ Diarthrodial plane joint
❖ Patella and trochlear variable and articulation doesn’t fit well
❖ The posterior surface of the patella articulates with the trochlear groove along the anterior surface of the femoral condyles to form the patellofemoral joint
❖ Relies on stability from static and dynamic (contractile)
structures

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2
Q

What is the function of the trochlea sulcus or intercondylar groove

A

❖ Distal femur reverse U-shaped intercondylar groove
❖ Intercondylar groove of femur facilitates/guides tracking of patella during flexion/extension
❖ Concave medial and lateral facets covered in articular cartilage
❖ Any bony abnormalities here may alter tracking
❖ Most angles and forces are inclined to encourage the patella laterally
❖ Patella only engages with pale blue areas

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3
Q

What is the function of the PFJ

A

❖ By displacing the fulcrum of motion of the extensor mechanism anterior to the femur, the patellofemoral articulation produces a mechanical advantage increasing the force of the quadriceps muscle in extending the knee
❖ The patella also centralises the divergent forces of quads and transmit that tension around the femur to patellar tendon

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4
Q

When does the patella contact the femur

A

As knee flexes to about 30 degrees, the patella articular surface begins to engage with the trochlea
➢ Between 30-90o of flexion, first the inferior and then the superior patella cartilage articulates with the trochlea cartilage
➢ Beyond 120 degrees knee flexion, contact decreases lots b/w the patella and trochlea

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5
Q

Why do pts with PFPS complain of pain with sit-to-stand/squat/stairs

A

❖ Greatest compression occurs in loaded flexion
❖ PFJRF is a product of the magnitude of Fq (power of quad contraction) and the angle of the knee
❖ The joint reaction force becomes higher as the
knee flexion angle increases

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6
Q

what is the loading on PFJ in different angles of knee flexion

A

➢ 10-15o flexion (walking)-50% body weight
➢ 60o flexion (ascending stairs)- 300% body weight
➢ 135o or more of flexion (deep squat)- 800% body weight

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7
Q

what is PFJS

A

❖ PFJS= amount of PFJRF per area of articular surface

❖ If contact area is smaller, then the patellar articular stress increases

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8
Q

what are the consequences of higher PFJS

A

❖ increases risk of subchondral bone stress and heightened risk with mal-tracking and/or small patella
❖ Asymmetrical loading of the PFJ becomes a key issue

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9
Q

What are some causes of PFPS

A 
❖ One of the main causes of PFPS is patellar orientation and alignment
➢ Knee hyperextension
➢ Lateral tibial torsion
➢ Genu valgum/varus
➢ Increased Q-angle
➢ Tightness in ITB, hamstrings, gastroc
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10
Q

How does an altered orientation of patella cause PFPS

A

it may glide more to one side of femur, which can result in pain, discomfort or irritation
❖ Muscular imbalances or biomechanical abnormality can cause a patellar deviation
❖ If VMO (vastus medialis oblique) isn’t strong enough, vastus lateralis can exert a higher force and cause a lateral glide, lateral tilt or lateral rotation of patella
❖ ITB or lateral retinaculum imbalance/weakness–>results in patella deviation/ lateral tracking of patella

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11
Q

What is the effect of tight hamis, hip and calf muscles on patella

A

❖ Tight hamstrings musclesIt places more posterior force on the knee, causing pressure between the patella and the femur to increase
❖ Weakness of tightness in the hip muscles–>Dysfunction of the hip external rotators results in compensatory foot pronation.
❖ Tight calf muscles It can lead to compensatory foot pronation and can increase the posterior force on the knee

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12
Q

what are the proximal, distal, lateral and medial passive stabilisers of PFJ

A 
Proximal:
-Rec Fem
-vastus intermedius
-quad tendon
Medial:
-VMO
-medial retinaculum
-Medial patello-femoral ligaments
Distal:
-patella tendon
Lateral:
-ITB
-Lateral PF Ligaments
-lateral retinaculum
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13
Q

What is the major passive stabiliser

A

MPFL-> major passive restraint preventing lateral patella dislocation

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14
Q

what is the Q-angle

A

❖ It is the effective line of pull of the quadriceps
❖ Formed between 2 lines joining:
➢ The anterior superior iliac spine and the centre of patella
➢ A line joining the centre of patella and the tibial tuberosity

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15
Q

what are some static/structural influences on Q-angle

A 
❖ Excessive femoral anteversion
❖ Structural genu valgus
❖ Structural genu varum
❖ Patella alta
❖ Patella baja
❖ Patella hypoplasia
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16
Q

what are some dynamic influences on Q-angle

A

❖ Local issues
➢ Poor quads function Vastus medialis oblique (VMO)
➢ Reduced extensibility ITB/lateral retinaculum/VL–>results in reduced patella mobility= medial glide/tilt
➢ Lax medial retinaculum/ MPFL
❖ Non-local issues
➢ Proximal issues poor frontal and transverse plane control at the stance hip = excessive dynamic valgus= patella lateralisation
➢ Distal issues:
• Foot/ankle motor control impairment prolonged/excessive foot eversion and abduction
• Loss of ankle dorsiflexion short gastrocnemius/soleus and stiff ankle joint

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17
Q

How do glute muscles affect Q-angle

A

❖ Gluteal muscles poor femoral-pelvic motor control and weakness of the gluteal muscle can result in excessive dynamic valgus
➢ Glutes function to maintain a level and stable pelvis during SL WB’ing activities
➢ If performing optimally, glute group opposes excessive dynamic valgus
➢ Dynamic valgus a position in which the stance hip moves in adduction and IR, and the contralateral pelvis drops inferiorly
➢ Excessive dynamic valgus is the issue of concern clinically

18
Q

What are the subgroups of PFPS

A 
➢ Sedentary adolescent/you-adult
➢ Active adolescent more common
➢ PFPS secondary to TFJ trauma/surgery
➢ Patella laxity/instability
➢ Direct trauma to PFJ
➢ Degenerative knee (OA)
19
Q

What are causes pf PFPS

A

❖ Sub-chondral bone stress reaction and/or peripatellar synovitis
➢ Usually secondary to repetitive sub-maximal mechanical loading of the PFJ and its soft tissue inclusions synovium and infra-patella fat pad
➢ Or direct trauma
❖ Hip kinematics can also influence the knee and provoke PFPS
➢ Weaker hip abductor muscles = increased hip abduction during running
➢ This affects Q-angle= increased stress on PFJ

20
Q

What are the neurological mechanisms for PFPS

A

❖rich free nerve endings within the retinacula, fat pad and SC bone leads to decreased pain thresholds
➢ Also SC bone and infrapatellar fat pad are felt to be the key pain generators in most forms of anterior knee pain

21
Q

what are the core criteria for PFPS diagnosis

A

❖ Pain that is described as behind/around the patella which is aggravated by at least 1 known PFJ loading activity during WB’ing
❖ Additional criteria
➢ Crepitus/ grinding during knee flexion
➢ TOP patella facets
➢ Small effusion
➢ Pain on sitting, STS or straightening the knee after prolonged sitting

22
Q

what are subjective features of PFPS

A

❖ Body chart
➢ Pain typically anterior and diffuse (peri-patella/retro-patella)
➢ Crepitus
❖ Mechanisms
➢ Typically secondary to repetitive/cyclic loading with a gradual onset on a background of TL error
➢ Adolescent sedentary population and sudden change in activity
➢ Primary onset due to trauma product of acute injury such as direct trauma to PFJ or recent knee surgery
❖ Aggravating factors activities involving repetitive loaded knee flexion-extension (stairs, cycling, squatting)
❖ Often provoked by prolonged knee flexion when PFJ is already sensitised (driving for extended periods)

23
Q

what are objective features of PFPS

A 
❖ Observation
➢ Mild, local swelling
➢ Biomechanical issues are common
❖ Functional critical test
❖ Symptoms provoked with WB’ing activities are eased/cleared when performed with:
➢ Correct loading strategy
➢ Medial/lateral patella glides
❖ ROM unloaded knee joint AROM and PROM usually WNL
❖ Palpation TOP at the PFJ margins
24
Q

what are the clinical features of patellofemoral chondral injury

A

❖ Injuries where the articular cartilage of knee joint is affected
❖ Articular cartilage is not very well perfused hence repair is harder
❖ Injury may occur due to trauma or overuse
❖ Patella joint effusion
❖ Decreased ROM
❖ Pain behind kneecap often on palpation, during knee movements against resistance
❖ Pain at rest, during and especially after prolonged sitting
❖ Accentuated pain during squatting/ walking downhill/ down stairs
❖ Radiological imaging helps in diagnosing

25
Q

Management of patellofemoral chondral injury

A

❖ Rest knee joints, stabilising knee joint
❖ Strength training and stretching exercises to strengthen extensor muscles
❖ Pain relieve medications
❖ Surgical interventions

26
Q

how does PFOA affect patella pain

A

❖ PFOA and PFPS present similar in terms of pain presentation
❖ Individuals with OA walk with bent knee resulting in increased stress
on patella-femoral joint as they are constantly loaded

27
Q

Management of PFPS

A
  • exercise== decreased pain, and increased function in medium/long term
  • combine hip, knee exercises to decrease pain in short/med/long term
28
Q

treatment options for PFPS

A

PFJ taping and orthotics
❖ Foot orthoses–> give short-term relief
❖ PFJ taping
➢ As an add-on treatment
➢ First-line treatment
➢ Varies significantly
❖ Changes in fear avoidance behaviours are an important predictor of outcome success

29
Q

what is os-good schlatter’s disease

A

❖ Juvenile equivalent of patella tendinopathy
❖ Involves the tibial tubercle and the immature ossification centre beneath
❖ Growth spurts
❖ It is a non-inflammatory degenerative pathology not Apophysitis
❖ Osteochondrosis is a more appropriate term pathology of the immature growth plate which tendon is attaching to
➢ Derangement of the normal processes of bone growth localised tissue necrosis usually followed by full regeneration of healthy bone tissue
➢ Occurs within the underlying epiphyses

30
Q

what are physical features of os-goos schlatters disease

A

❖ Observation localised deformity over the TT
❖ Pain location = anterior-well localised
❖ Palpation-TOP TT
❖ Muscle tests-contraction of extensors can be painful and possible muscle tightness
❖ Medical investigation- radiography

31
Q

what are management options of os-good schlatter’s disease

A

❖ Education
❖ Self limiting can be protracted
❖ When skeletally mature, symptoms usually resolve
❖ Participation in sports guided by severity of symptoms alternating activities/modifications of symptoms
❖ Address any co-existing factors

32
Q

what is sinding-larsen-johansson disease

A

❖ Involves a vulnerable growth area
❖ Distal pole of patella
❖ Usually affects children/adolescents who are active in sport

33
Q

physical features of sinding-larsen-johansson disease

A

❖ Observation localised deformity over the TT
❖ Pain location = anterior well localised
❖ Palpation TOP TT
❖ Muscle tests contraction of extensors can be painful and possible muscle tightness
❖ Medical investigation radiography

34
Q

what is infra-patella fat-pad impingement

A 
❖ Once fat-pad has become irritates, things involving terminal extension often drive the pain going into mid-range flexion
❖ Causative factors:
➢ Local trauma
➢ Post surgery
➢ Genu recurvatum
➢ Inferior pole tilt
❖ May accompany PFJ syndrome
35
Q

what are physical clinical features of infra-patella fat-pad impingement

A

❖ Observation thickening over fat pad
❖ Aggravating activities prolonged standing, stairs and EOR extension activities (active and passive)
❖ Passive TOP deep to patella tendon/behind inferior pole

36
Q

management of infra-patella fat-pad impingement

A

❖ Bracing/taping
❖ Motor relearning and posture correction
❖ Posterior pelvic tilt, abdominal control, neutral position of knee
❖ Increase DF range if limited

37
Q

what is ilio-tibial band friction syndrome

A

❖ Lateral knee pain
❖ It descends distally to attach to lateral border of patella and lateral patellar retinaculum, and Gerdy’s tubercle of tibia
❖ Sends fibres to the lateral aspect of patella
➢ Friction between the lateral femoral condyle and tract causing inflammation of tract/bursa
➢ Any high levels f compression at the distal end of the ITB can very quickly cause them to become irritated
➢ Compression of the highly innervated layer of fat and connective tissue that separates the ITB from the epicondyle

38
Q

what is ITB function

A

❖ Controlled adduction assists TFL and controls and decelerates adduction and extension of thigh
❖ Knee joint stabiliser acts as an anterolateral stabiliser of knee joint
❖ Assists knee extension TFL with ITB assists with knee extension

39
Q

What is the aetiology of ITBFS

A

Any biomechanical situation which allows compression of the ITB on the lateral epicondyle
➢ Sub-optimal hip control excessive dynamic valgus, tight/overactive TFL
➢ Tight ITB

40
Q

what are sujective clinical features of ITBFS

A

❖ Pain over lateral aspect of knee pain usually well localised and lateral but may diffuse soreness along lateral thigh
❖ Aggravating activities
➢ Running, stairs typically during 20-30 degrees of flexion/extension
➢ Tends to deteriorate lots if subject continues to pursue aggravating activities
❖ Injury progression not unlike that of a tendinopathy
➢ Primary pain only after exercise
➢ Secondary pain during and after exercise
➢ Tertiary pain affecting ADL’s
❖ Symptoms become progressively more disabling as the injury progresses

41
Q

what are objective clinical features of ITBFS

A

❖ Observation localised swelling over the lateral epicondyle
❖ No restriction of ROM of hip/knee full ROM typically within 20-30o of ext; a decreased in ROM is most likely due to apprehension
❖ Palpation exquisite tenderness over lateral epicondyle/IT bursa
➢ Enhanced if palpate in Ober’s position
➢ Crepitus

Peripheral Musculoskeletal Science (3 decks)

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