Patellofemoral Joint

Question 1

describe the patellofemoral joint

Answer 1

❖ 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

Question 2

What is the function of the trochlea sulcus or intercondylar groove

Answer 2

❖ 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

Question 3

What is the function of the PFJ

Answer 3

❖ 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

Question 4

When does the patella contact the femur

Answer 4

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

Question 5

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

Answer 5

❖ 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

Question 6

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

Answer 6

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

Question 7

what is PFJS

Answer 7

❖ PFJS= amount of PFJRF per area of articular surface

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

Question 8

what are the consequences of higher PFJS

Answer 8

❖ 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

Question 9

What are some causes of PFPS

Answer 9

❖ 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

Question 10

How does an altered orientation of patella cause PFPS

Answer 10

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

Question 11

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

Answer 11

❖ 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

Question 12

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

Answer 12

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

Question 13

What is the major passive stabiliser

Answer 13

MPFL-> major passive restraint preventing lateral patella dislocation

Question 14

what is the Q-angle

Answer 14

❖ 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

Question 15

what are some static/structural influences on Q-angle

Answer 15

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

Question 16

what are some dynamic influences on Q-angle

Answer 16

❖ 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

Question 17

How do glute muscles affect Q-angle

Answer 17

❖ 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

Question 18

What are the subgroups of PFPS

Answer 18

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

Question 19

What are causes pf PFPS

Answer 19

❖ 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

Question 20

What are the neurological mechanisms for PFPS

Answer 20

❖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

Question 21

what are the core criteria for PFPS diagnosis

Answer 21

❖ 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

Question 22

what are subjective features of PFPS

Answer 22

❖ 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)

Question 23

what are objective features of PFPS

Answer 23

❖ 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

Question 24

what are the clinical features of patellofemoral chondral injury

Answer 24

❖ 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

Question 25

Management of patellofemoral chondral injury

Answer 25

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

Question 26

how does PFOA affect patella pain

Answer 26

❖ 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

Question 27

Management of PFPS

Answer 27

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

Question 28

treatment options for PFPS

Answer 28

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

Question 29

what is os-good schlatter's disease

Answer 29

❖ 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

Question 30

what are physical features of os-goos schlatters disease

Answer 30

❖ 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

Question 31

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

Answer 31

❖ 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

Question 32

what is sinding-larsen-johansson disease

Answer 32

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

Question 33

physical features of sinding-larsen-johansson disease

Answer 33

❖ 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

Question 34

what is infra-patella fat-pad impingement

Answer 34

``` ❖ 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 ```

Question 35

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

Answer 35

❖ 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

Question 36

management of infra-patella fat-pad impingement

Answer 36

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

Question 37

what is ilio-tibial band friction syndrome

Answer 37

❖ 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

Question 38

what is ITB function

Answer 38

❖ 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

Question 39

What is the aetiology of ITBFS

Answer 39

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

Question 40

what are sujective clinical features of ITBFS

Answer 40

❖ 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

Question 41

what are objective clinical features of ITBFS

Answer 41

❖ 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