The document discusses the biomechanics of the knee joint, including the tibiofemoral joint and patellofemoral joint. It covers the articulating surfaces, degrees of freedom, ligaments, muscles, alignment and weight bearing forces of the knee. It also discusses normal patellar tracking in the trochlear groove during range of motion and the changing contact areas between the patella and femur through different degrees of flexion.

1. BIOMECHANICS & PATHOMECHANICS OF KNEE
JOINT AND PATELLOFEMORAL JOINT
• By:-
Dr. Taniya verma ( PT)
MPT – Musculoskeletal

2. Content of tibio-femoral joint
• Articulation surfaces
• Axial rotations and varus-valgus movt.
• Menisci
• Stabilizers
• Bursae
• Ligaments and their biomechanics
• Muscles (quads activity on w.b and n.w.b)
• TF alignment and wt. bearing forces
• CKC/OKC – flex/ext on TF joint

3. Knee complex
1.)Tibio-femoral joint
2.)Patello-femoral joint

4. Knee degree of freedom
• Rotations
• Flex/Ext – 15° – 140°
• Varus/Valgus – 6° – 8° in extension
• Int/ext rotation – 25° – 30° in flexion
• Translations
• AP 5 - 10 mm
• Compression/Distraction 2 - 5 mm
• Medial/Lateral 1-2mm

5. Tibio-femoral Joint
• Double condyloid knee joint is also referred to as Medial &
Lateral Compartments of the knee.
• Double condyloid joint with 3° freedom of Angular
(Rotatory) motion.
• Flexion/Extension –
• Plane – Sagittal plane
• Axis – Coronal axis
• Medial/lateral (int/ext) rotation –
• Plane – Transverse plane
• Axis – Longitudinal axis
• Abduction/Adduction –
• Plane – Frontal plane
• Axis – Antero-posterior axis.

6. Femoral articular surface
• Femur is proximal articular surface of the knee joint with
large medial & lateral condyles.
• Because of obliquity of shaft, the femoral condyles do not
lie immediately below the femoral head but are slightly
medial to it.
• The medial condyle extend further distally, so that, despite
the angulation of the femur’s shaft, the
distal end of the femur remains essentially horizontal

8. Tibial articulating surface
• Asymmetrical medial & lateral tibial condyles constitute the
distal articular surface of knee joint.
• Medial tibial plateau is longer in AP direction than lateral
• The lateral tibial articular cartilage is thicker than the medial
side.
• Tibial plateau slopes posteriorly approx. 7° to 10°
• Medial & lateral tibial condyles are separated by two bony
spines called the Intercondylar Tubercles

9. Axial rotation of knee
arthrokinemetic
• Axis – vertical axis
• Plan – transvers plan
• ROM – Maximum range is
available at 90° of knee flexion.
• The magnitude rotation diminishes as the knee approaches
both full extension and full flexion.
• Medial condyle acts as pivot point while the lateral
condyles move through a greater arc of motion, regardless
of direction of rotation.

10. Valgus (Abduction)/Varus
( Adduction )
• Axis – Antero-posterior axis
• Plane – Frontal plane
• ROM –
• 8° at full extension
• 13° with 20° of knee flexion.
• Excessive frontal plane motion could indicate ligamentous
insufficiency

11. Menisci of knee joint
• 2 asymmetrical fibro cartilaginous joint disk called Menisci
are located on tibial plateau.
• The medial meniscus is a semicircle & the lateral is 4/5 of a
ring
• Both menisci are –
• Open towards intercondylar area
• Thick peripherally
• Thin centrally forming cavities for femoral condyle
• Reduce friction, serve as shock absorber
• Innervated
• Menisci removal = increase articular cartilage stress

12. KNEE JOINT
STABLIZERS

13. Bursa associated with knee
• Pre-patellar bursa –located between skin and anterior
surface of patella
• They allows free movement of skin over patella during
knee flexion & extension
• Subcutaneous bursa –Located between patellar ligament &
overlying skin.
• Deep infra-patellar bursa –
• Located between patellar ligament & tibial tuberosity
• Helps in reducing friction between the patellar
ligament & tibial tuberosity

14. • Sub popliteal bursa –located between tendon of the
popliteus muscle and the lateral femoral condyle
• The gastrocnemius bursa - lies between the tendon of
the medial head of the gastrocnemius muscle and the
medial femoral condyle.
• The three bursae that are connected to the synovial
lining of the joint capsule (the suprapatellar bursa, the
sub popliteal bursa, and the gastrocnemius bursa) allow
the lubricating synovial fluid to move from recess to
recess during flexion and extension of the knee.

15. Ligament of knee joint
• Collateral ligament
• Medial collateral ligament (MCL)
• Lateral collateral ligament (LCL)
• Cruciate ligament
• Anterior cruciate ligament (ACL)
• Posterior cruciate ligament (PCL)
• Posterior capsular ligament
• Meniscofemoral ligament
• Iliotibial band

16. BIOMECHANICS OF ACL
• Restrains anterior translation of tibia.
• The ACL consist of two separate bands that wrap around
each other.. The anteromedial band (AMB) and the
posterolateral band (PLB)
• With the knee in full extension, the PLB is taut; as knee
flexion increases, the PLB loosens and the AMB becomes
tight
• Most injuries occurs in CKC
• Least stress on ACL between 30°-60° of flexion
• Anteromedial bundle tight in flexion and extension
• Posterior lateral bundle tight only in extension

17. • The muscles surrounding the knee joint are capable of either inducing or minimizing strain in the ACL.
• With the tibiofemoral joint in nearly full extension, a quadriceps muscle contraction is capable of
generating an anterior shear force on the tibia, thereby increasing stress on the ACL.
• Fleming et al. reported that the gastrocnemius muscle similarly has the potential to translate the tibia
anteriorly and strain the ACL because the proximal tendon of the gastrocnemius wraps around the
posterior tibia, effectively pushing the tibia forward when the muscle becomes tense through active
contraction or passive stretch 1.
• The hamstring muscles are capable of inducing a posterior shear force on the tibia throughout the
range of knee flexion, becoming more effective in this role at greater knee flexion angles.
• The hamstrings, therefore, have the potential to relieve the ACL of some of the stress of checking
anterior shear of the tibia on the femur

18. BIOMECHANICS OF PCL
• Two Bundles- Anteromedial taut in flexion; posteromedial taut In extension
• Orientation prevents posterior motion of tibia
• Restraint to varus/valgus force.
• Restrain motion with knee flexed.
• Resists rotation especially int.rotation of tibia on femur.
• The popliteus muscle shares the role of the PCL in resisting posteriorly
directed forces on the tibia and can contribute to knee stability when the PCL
is absent.

19. Muscles of the Knee
Area One-joint Muscle Two-joint Muscle
Anterior
Vastus Lateralis
Rectus Femoris
vastus Medialis
Vastus Intermedialis
Posterior
Biceps Femoris
(Short)
Biceps Femoris (Long)
Semimembranosus
Semitendinosus
Sartorius
Gracilis
Gastrocnemius
Lateral Tensor Fascia Latae

20. Muscles of Posterior Knee
Knee Flexors
Semimembranosus, Semitendinosus, Biceps
Femoris (Long & Short Heads), Sartorius,
Gracilis, Popliteus & Gastrocnemius Muscles
Flex + Tibial Medial
Rotators
Popliteus, Gracilis, Sartorius, Semimembranosus & Semitendinosus
Muscles
Flex + Tibial Lateral
Rotator
Biceps Femoris
Flex + Abductor Biceps Femoris, Lateral Head Gastrocnemius & Popliteus
Flex + Adductor Semimembranosus, Semitendinosus, Medial Head
Gastrocnemius, Sartorius & Gracilis

21. Quadriceps muscle
• Functions –
• Together, the 4 components of quadriceps femoris
muscle function to extend the knee.
• Rectus femoris being a 2 joint muscle, it also involved
in hip flexion along with knee extension.
• Angle of pull of Quadriceps –
• Vastus lateralis – Pull 35° Lateral to long axis of femur
• Vastus Intermedius – Pull Parallel to Shaft of femur, making
purest knee extensor.
• Vastus Medialis – Pull depended on segment of muscle –
resultant pull 40° medially.
• Upper fibers Vastus Medialis Longus (VML) angled 15°
– 18° Medially
• Distal fibers Vastus Medialis Oblique (VMO) angled 50°
– 5° Medially

22. • When an erect posture is attained –
• Minimal activity of quadriceps because the LOG passes
just anterior to knee axis results in a gravitational
extension torque that maintains the joint in extension.
• In weight-bearing with the knee slightly flexed –
• The LOG pass posterior to knee joint axis
• As the gravitational torque tend to promote knee
flexion, the activity of quadriceps is necessary to
counterbalance the gravitational torque and maintain
the knee joint in equilibrium.
Quadriceps activities
During weight-bearing

24. Quadriceps activities during non–weight-bearing
• The MA of resistance is minimal when the knee is flexed to 90° but
increases as knee extension progresses.
• Therefore, greater quadriceps force is required as the knee approaches
full extension.
• The opposite happens during weight-bearing activities.

26. TF alignment & weight
bearing force
• The anatomic/ longitudinal axis –
• Femur – Oblique, directed inferiorly &
medially
• Tibia – Directed vertically
• The femoral & tibial longitudinal axis
form an angle medially at the knee
joint of 180° – 185°
• In bilateral static stance – equal weight
distribution on medial & lateral condyle

27. • Deviation in normal force distribution –
• TF angle > 185°– Genu Valgum – compress lateral
condyle; increased tensile force on medial condyle
• TF angle < 175° – Genu Varum – compress medial
condyle; increased tensile force on lateral condyle
• Compressive force in dynamic knee joint
• 2 – 3 time body weight in normal gait
• 5 – 6 time body weight in activities (like –
Running, Stair Climbing etc.)

28. TF CKC Flexion
• Early 0° – 25° knee flexion –
• Posterior rolling of femoral condyles on the tibia.
• As flexion continues –
• Posterior Rolling accompanied by simultaneous
Anterior glide of femur
• Create a pure Spin of femur on the posterior tibia

29. TF CKC extension
• Extension from flexion is a reversal of flexion motion.
• Early extension –
• Anterior rolling of femoral condyles on tibial plateau
• As extension continues –
• Anterior Rolling accompanied by simultaneous
Posterior glide of femur
• Produce a pure Spin of femoral condyles on tibial
plateau
Tf OKC flexion / extension
• When tibia is flexed on a fixed femur –
• The tibia performed Both Posterior Rolling & Gliding on
relatively fixed femoral condyles.
• When tibia is Extended on a fixed femur –
• The tibia performed Both Anterior Rolling &
Gliding on relatively fixed femoral condyles.

30. Contents of PFJ
• Articulating surfaces and functions
• Stabilizers
• PFJ motions and patellar tracking
• Contact area of patella during motion
• PFJ congruence and various patellar positions
• Joint reaction forces
• Radiographic evaluation
• CKC vs OKC and Pt. implications
• PATELLOFEMORAL PAIN : definition, mechanism, examination and
treatment.

31. Articulating surfaces –
Patella = inverted triangle with apex directed inferiorly;
Articulates with trochlea
PFJ function
• It work primarily as an anatomical pulley
• It reduce friction between quadriceps tendon & femoral condyle.
• The ability of patella to perform its function without restricting knee
motion depends on its mobility
PATELLO-FEMORAL JOINT (PFJ)

32. Patellar Influence on Quadriceps Function
• Patella lengthens the MA of quadriceps by increasing the distance
of quadriceps tendon & patellar tendon from the axis of the knee
joint.
• The patella, as an anatomic pulley, deflects the action line of
quadriceps away from the joint centre, increasing the angle of pull
& enhancing extension torque generation.
• Pull of quadriceps also creates anterior translation of tibia on
femur increasing ACL restraint
• Presence of patella allows flexion and extension to occur with a
lesser amount of quadriceps force
• Because the fulcrum (patella) is placed between applied force (
quadriceps) and resistance to be moved (lower leg), patella
function as class 1 lever

33. PFJ articulating surface
• The triangular shape patella is a largest sesamoid bone in
body is a least congruent joint too.
• Posterior surface is divided by a vertical ridge into medial &
lateral patellar facets.
• The ridge is located slightly towards the medial facet making
smaller medial facet
• The medial & lateral facet are flat & slightly convex side to
side & top to bottom.
• At least 30% of patella have 2nd ridge separating medial
facet from the extreme medial edge known as Odd Facet of
Patella.
• https://youtu.be/e9MQwjZeQs8

34. Femur patellar surface
• femoral sulcus/intercondylar groove
• Corresponds to vertical ridge on patella
• Concave side to side; convex top to bottom
• The patella is attached to the tibial tuberosity by the
patellar tendon

35. Medial-lateral PFJ stability
• PFJ is under permanent control of 2 restraining mechanism
across each other at right angel.
• Transvers group of stabilizer
• Longitudinal group of stabilizer
• Transvers stabilizer –
• Medial & lateral retinaculum
• Vastus Medialis & Lateralis
• The lateral PF ligament contributes 53% of total force when
in full extension of knee.
Longitudinal stabilization
• Patellar tendon – inferiorly
• Quadriceps tendon – superiorly
PATELLO-FEMORAL JOINT
STABLIZERS

36. SOFT TISSUE STABLIZERS OF PATELLA
Medially=
The medial restraints consist of the
medial retinaculum, the medial
patellofemoral ligament, and the VMO.
Laterally=
The lateral restraints consist of the lateral
retinaculum, the vastus lateralis, and the
iliotibial band.
Inferiorly = the patella tendon Superiorly =
central quadriceps tendon expansion of
the quadriceps muscle

37. PATELLAR MOTONS ( patellar tracking)
• Patellar flexion = patella travels down the intercondylar groove
• Patellar extension = Knee extension brings the patella back to its original
position with the apex of the patella pointing inferiorly
• Medial and lateral patellar tilt
• Medial and lateral patellar rotation

38. NORMAL PATELLAR TRACKING
• Normal tracking of patella inside trochlear groove during knee ROM .
• Balanced forces around patella = normal biomechanics of PFJ
• FULL EXTENDED KNEE
• Patella is tethered in a distal-medial-posterior direction by tight medial
retinacula ( MPFL).
• 0-20’ (trochlear engagement)
• Medial translation
• Lateral tilt 4-5 degrees
• Progressive flexion
• 20-90 degrees
• Lateral translation
• Progressive lateral tilt
• rotation

39. • In full extension- little/no contact b/w femur and patella
• At 10° – 20° of flexion – contact with inferior margin of
medial & lateral facet.
• By 90° of flexion – all portion of patella contact with femur
except the odd facet.
• Beyond 90° of flexion – medial condyle enter the
intercondylar notch & odd facet achieves contact for the
first time.
• At 135° of flexion – contact is on lateral & odd facet with
medial facet completely out of contact.
CONTACT AREA OF PATELLA ON
FEMUR DURING MOTION

41. PFJ congruence
• Fully extended knee= patella lies on femoral sulcus ;
minimal joint congruency
• The vertical position of patella in femoral sulcus is related to
length of patellar tendon, approximately 1:1 is (referred to
as Insall-Salvati index)
• An excessive long tendon produce an abnormally high
position of patella on femoral sulcus known as patella alta,
(Ratio>1.2) which increases the risk for patellar instability
• In neutral or extended knee, the patella has little or no
contact with the femoral sulcus beneath.

42. • Position of patella
• Patella alta- abnormal high position of patella
• Patella baja- abnormally low position of patella
• Squinting of patella- medially facing patella

43. PF joint reaction forces
• The patella is pulled simultaneously by the quadriceps tendon superiorly and by
patella tendon inferiorly
• In normal full extension the patella is suspended between them
• Even a strong compression of quads produce no PF compression
clinical significance-This is the rational for use of straight leg raising exercise
with hip in neutral position as a way of improving quadriceps muscle strength without
creating PF problems
• Minimal quads forces are required during upright and relaxed standing ( COG
almost above directly above knee )
• As knee flexion increases the COG shift posteriorly, increasing flexion moments
required.
• Knee flexion affects angle between patellar tendon force and quadriceps tendon
force
• The total JRF depends on – 1) magnitude of active or passive pull of quads,
• 2) angle of knee flexion

45. Medial & lateral force on patella
• Since the action line of quadriceps & patellar ligament do not
co-inside, patella tend to pulled slightly laterally & increase
compression on lateral patellar facets.
• Larger force on patella may cause it to subluxation or dislocate
off the lateral lip of femur.
• Genu valgum increase the obliquity of femur & oblique the pull
of quadriceps.
• Medial Femoral anteversion & lateral tibial torsion = increased
obliquity in patella predisposing to excessive lateral pressure or
to subluxation or dislocation.
• Excessive tension in lateral retinaculum (or weakness of VMO)
=lateral patellar tilt
• Insufficient height of lateral lips of femoral sulcus may create
patellar subluxation or fully dislocation

47. RADIOGRAPHIC EVALUATION
• Three views of the patella—an AP, a lateral in 30 degrees of knee flexion,
and an axial image—should be obtained.
• AP view = assess for the presence of any fractures, The overall size,
shape, and gross alignment of the patella.
• lateral view = evaluate the patellofemoral joint space and to look for
patella alta or baja, the presence of fragmentation of the tibial tubercle
or inferior patellar pole can be seen.
• Both the AP and the lateral views can also be used to confirm the
presence and location of any loose bodies or osteochondral defects that
may exist.
• An axial image, typically a Merchant (knee flexed 45 degrees and x-ray
beam angled 30 degrees to axis of the femur) or skyline view, may be
the most important. It is used to assess patellar tilt and patellar
subluxation

48. • SULCUS ANGLE
• A line is drawn along the medial and lateral walls of the
trochlea. The angle formed between them is the sulcus angle.
Greater than 150 degrees is abnormal and indicates a shallow
or dysplastic groove
• CONGRUENCE ANGLE
• Measure Patellofemoral subluxation .
• The angle is formed by a line drawn from the apex of the
trochlear groove bisecting the sulcus angle and a line drawn
from the apex of the groove to the apex of the patella. A lateral
position of the patella apex relative to the apex of the trochlea
is considered positive (with greater positive angles suggesting
greater lateral shift)
• A normal congruence angle has been described as −6 degrees
±6 degrees.

49. (A) sulcus angle
(B) congruence angle
(C) Lateral displacement may also be quantified by the distance between the medial patellar facet and the
apex of the medial femoral condyle.
(D) The lateral patellofemoral angle is a measure of patellar tilt and is calculated as the angle between a
horizontal line across the peaks of the 2 femoral condyles and a line along the lateral patellar facet. An
angle opening medially indicates lateral tilt.
(E) The Insall-Salvati index is calculated in the sagittal plane as the ratio of patella length to patellar
tendon length.
(F) The Blackburne-Peel index similarly quantifies patellar height and is the ratio of the distance of the
articular surface of the patella to the distance measured between the inferior patellar articular surface
and the tibial plateau.

50. CLOSED KINETIC CHAIN
• In closed chain mode the joint reaction force
on the patellofemoral joint increases as the knee flexes from 0 to 90°
• The contact area also increases, but the change is less than that of the force. Therefore, the stress in-
creases ; as the knee goes from 0 to 90°.
• From 90 to 120°, the force either Ievels off' or even decreases ;as the quadriceps tendon comes into
contact with the trochlea and begins to account for some of the total joint reaction force and contact area.

51. OPEN KINETIC CHAIN
• In the open chain mode (eg., leg curls and extensions), the forces across the patella are lowest
at 90° of flexion . The joint reaction force is quite low.
• As the knee extends from this flexed position, the quadriceps force increases, the joint reaction
force increases (then decreases past 45°). and the contact area progressively decreases.
• The net result is an increase in contact stress until early flexion (about 25°). Between 5° and 25°,
the situation is quite complex
• At 0 degree, the quadriceps force is high, the joint reaction force is low because the femur and
tibia are nearly parallel and because there is no contact between the two cartilaginous surfaces.
Likewise, contact stress is low.
• In hyperextension, the patellar cartilage stress is low because the patella is actually lifted off the
distal femur and does not overlap with the trochlea.

52. PHYSICAL THERAPY IMPLICATION
• Open chain exercises are most safely carried out from 25° to 90° (60°
to 90° if there are distal lesions).
• From a point of view of cartilage stress, straight leg raises with the
knee at 0° of extension or hyperextension are equally safe.
• Closed chain exercises are safest in the 0 to 45° range, especially if
there are proximal lesions.
• Those with patellofemoral pain avoid deep flexion while doing
weight-bearing extension exercises and avoid the final 30° of
extension during non–weight-bearing knee extension exercises

53. PATELLOFEMORAL PAIN ?
(2016 Patellofemoral pain consensus
statement )
• Diffuse anterior knee pain in activities such as squatting,
running, stairs ascend and descend.
• Patellofemoral pain- synonym for PFP syndrome,
chondromalacia patellae, anterior knee pain, runners knee.
• Pain around or behind the patella increased which is
aggravated by at least one activity that loads the
patellofemoral joint during weight bearing on a flexed knee
(eg, squatting, stair ambulation, jogging/ running,
hopping/jumping).

54. PATELLOFEMORAL PAIN –MECHANISM (Christopher
M.Powers)
• Diminished contact area
• Quadriceps contraction activity ( stair ascent/descent) Inc.. JRF decreased
contact area Inc.. PFJ stress
• Braces reduce symptoms by increasing contact areas.
• High cartilage and bone stress
• Loading elevated hydrostatic and shear stress in articular cartilage
thinner cartilage reduces deformational behavior.
• Cartilage stress transfer to sub chondral bone ( innervated- primary source of
retropatellar pain ) high bone stress.
• Patella malalignment/abnormal tracking
• Trochlear dysplasia /patellar alta excessive lateral patellar tilt lateral
displacement decreased contact area increased PFJ stress

55. • PROXIMAL FACTORS = Hip related;
• Excessive knee valgus resulting from hip adduction increased Q angle
frontal plane malalignment.
• Controlled hip adduction reduce laterally directed force on PFJ hence reduced
Q angle.
• Impaired hip strength (extensors, abductors and ER) altered hip mechanics
• Improved strength controlled hip rotation improved patellar tracking
improve contact area.
• DISTAL FACTORS= related to foot and ankle;
Foot pronation and tibial rotation
• Abnormal foot pronation Inc.. tibial rotation decreased Q angle
• Foot orthosis- provide short term relief ( 6-8 weeks)

56. • Quadriceps; hamstring; gastro soleus flexibility
• Decreased quadriceps flexibility leads to = Inc. PFJ stress; anterior
pelvic tilt; limits gluteal activation
• Hamstring tightness= Inc. knee flexion; Inc. PFJ stress; limits knee
extension and quads activity ( Inc. PF JRF);posterior pelvic tilt
• Gastro soleus tightness= limited ankle DF mobility; toe out/pronated
foot; Inc. tibial IR; Inc. compensatory knee valgus

57. SUBCHONDRAL BONE
OVERLOAD THEORY
Inc. PFJ stress
Inc. cartilage stress
Inc. bone stress
Inc. patella water content
Inc. intra-osmotic pressure
PF pain
Farrokhi et al.2011
Ho. et al 2014

58. CLINICAL EXAMINATION OF PFP
• The best available test is anterior knee pain elicited during a
squatting manoeuvre: PFP is evident in 80% of people who are
positive on this test.
• Additional tests (limited evidence): Tenderness on palpation of the
patellar edges (PFP is evident in 71–75% of people with this finding.
• Tests with limited diagnostic usefulness
▸ Patellar grinding and apprehension tests (eg, Clarke’s test) have
low sensitivity and limited diagnostic accuracy for PFP.
▸ Knee range of motion and effusion

59. Brief physical examination for patellofemoral pain

60. TREATMENT OF PF pain
• Hip Strengthening as a Treatment for Patellofemoral Pain
Nakagawa et al. ClinRehab, 2009 Fukadaet al. JOSPT, 2010
• The combined use of hip and quadriceps strengthening was better th
an quadriceps strengthening alone.

61. Syme, G., Rowe, P., Martin, D., & Daly, G. (2009). Disability in patients with chronic
patellofemoral pain syndrome: A randomised controlled trial of VMO selective
training versus general quadriceps strengthening.
• prospective single blind RCT to compare the effects of rehabilitation with VMO VS general
strengthening of the quadriceps femoris muscles on pain, function and Quality of Life in
patients with PFPS
• Patients with PFPS were recruited from a hospital orthopaedic clinic and randomised into
three groups: (1) physiotherapy with emphasis on selectively retraining the VMO
(Selective); (2) physiotherapy with emphasis on general strengthening of the quadriceps
femoris muscles (General ); and (3) a no-treatment control group (Control ).
• The Selective and General groups demonstrated statistically significant and ‘moderate’ to
‘large’ effect size reductions in pain when compared to the Control group. Both the
Selective and General groups displayed statistically significant and ‘moderate’ and ‘large’
effect size improvements in subjective function and Quality of Life compared to the
Control group

62. ROLE OF VMO : TIME TO RETIRE THE QUADRICEPS IMBALANCE THEORY?
• Isolated recruitment of the (VMO), has not been proven to occur with exercises
commonly prescribed for patellofemoral pain.
• The concept of VMO strengthening is prefaced on the belief that the VMO can
be selectively recruited, independent of the vastus lateralis (VL), through
various exercises. A thorough review of the existing literature has revealed that
isolated contraction of the VMO independent of the VL has never been
documented.
• Thus, isolated recruitment of the VMO does not occur with commonly
prescribed exercises, and that selective strengthening is unlikely.

63. BIOFEEDBACK FOR PFJ PAIN6
• Dursun et al2 investigated the relationship between biofeedback, exercise,
and quadriceps function in patients with PFPS.
• Sixty subjects participated in the study and were assigned to 1 of the following groups:
biofeedback
and exercise or exercise only.
• All subjects performed a traditional exercise program 5 days a week for 4 weeks and then 3 days a
week for another 8 weeks. The exercise program consisted of isometric strengthening, as well
as Fexibility, proprioceptive, and endurance training.
• The researchers measured changes in visual-analog-scale (VAS) scores, Functional Index
Questionnaire (FIQ) scores, and mean quadriceps contraction at the end of each month.
• VAS and FIQ scores improved significantly for both groups at each measurement interval
• Based on these improvements, the authors concluded that biofeedback did not result in clinical
improvement beyond that of traditional exercise alone

64. McConnell-Based Patella Taping
• McConnell3 has advocated the use of patella taping to promote pain-free exercise for patients with
PFPS, reporting that patella taping places the patella in a more medial position and decreases
compressive forces caused by excessive lateralization. McConnel has reported success rates as high as
96% in patients with PFPS who performed exercise in combination with this taping technique
• Eburne and Bannister4 compared the McConnell regimen with an isometric quadriceps-exercise
program in patients with PFPS. One group of subjects performed quadriceps isometric and SLR
exercises; subjects in the other group performed VMO-strengthening exercises with McConnell
taping.
• At the end of the 3-month period, subjects in both groups demonstrated improvements in these
parameters, and statistical analyses did not reveal any between-group differences. Overall, the
showed that both exercise programs benefited all patients by 50%, far less than the 96% success rate
reported by McConnell.

65. • Clark et al5 conducted a randomized controlled trial that examined the effect of exercise, patient
education, and taping on strength, pain, and function in patients diagnosed with PFPS. The
researchers assigned participants to 1 of the following intervention groups: exercise, taping, and
education; exercise and education; taping and education; and education regarding the etiology and
prevention of further knee irritation (shoe wear, ice, stress relaxation, and diet/weight advice)
• The researchers measured pain, perceived function, and strength before the intervention and at 3
and 12 months after the beginning of the study. All subjects demonstrated improvements in all
parameters at the 3-month retesting period. In addition, those in the exercise and education groups
achieved greater strength gains than did subjects who only did taping.

66. PROXIMAL EXERCISES ARE EFFECTIVE IN TREATING PATELLOFEMORAL PAIN SYNDROME:
A SYSTEMATIC REVIEW
Jeroen S.J. Peters, PT1 and Natalie L. Tyson, PT2
• The aim of this systematic review was to investigate the effectiveness of proximal
exercises, compared with knee exercises, for patients with patellofemoral pain, in
improving pain and function.
• A computer‐based search (population: patients with patellofemoral pain, intervention:
proximal [hip or lumbo‐pelvic] exercises, comparator: knee exercises, outcome:
self‐reported pain and/or functional questionnaire) was undertaken. Data was
extracted for the exercise prescription and applicable outcome measures, and a
descriptive analysis undertaken.
• Eight studies (three randomized controlled trials, one clinical controlled trial, three
cohort studies and one case series) of moderate to high methodological quality met
the inclusion criteria. Proximal exercise programs showed a consistent reduction of
pain and function in the treatment of patellofemoral pain.
• All of the proximal exercise programs improved pain and function, while 80% of the
knee interventions reduced pain, and 75% improved function.

67. REFERENCES :-
• Norkins Joint Structure and Function: A Comprehensive Analysis Fourth Edition
• The Biomechanics of the Patellofemoral joint' -Ronald P. Grelsamer, MD" john R. Klein, MD -'
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