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![vastus medialis has 2 types of
fibres
• Longitudinal (vastus
medialis longus [VML]) – 15-
18°
• Oblique (vastus medialis oblique
[VMO]) – 50-55°
• VMO pulls the patella medially
and thus helps in patellar
stabilisation](https://image.slidesharecdn.com/untitledpresentation-250522133544-c8550441/75/Untitled-presentation-pptx-manassilaayo-40-2048.jpg)
Untitled presentation.pptx manassilaayo.
- 1. Biomechanics and appliedanatomy of knee joint and related disorders DR.FARIS BABU .M JUNIOR RESIDENT- 1, DEPT. OF PMR,SMS.
- 2. KNEE COMPLEX- ANATOMY ⮚ Thetibiofemoral joint ⮚ The patellofemoral joint
- 3. ANATOMY OF KNEEJOINT. • A hinge type of joint with some flexion and extension. • Small degree of medial and lateral rotation. • One of the most frequently injured joints because of its : ✔ Anatomical structure. ✔ Exposure to external forces ✔ Functional demands placed on it
- 4. Structures around theknee Can be divided into ▪ Osseous structures ▪ Extra articular structures ✔Extra articular tendinous structures ✔Extra articular ligamentous structures ▪ Intra articular structures.
- 5. Osseous structures • Consistof ✔Distal femoral condyles. ✔Proximal tibial plateaus. ✔The patella.
- 6. Extraarticular structures ✔ Thesynovium ✔ Joint capsule ✔ Collateral ligaments ✔Musculotendinous units-span the joint“Extra articular tendinous structures”.
- 7. MRI IMAGING OFKNEE JOINT
- 8. Extraarticular Tendinous structures Principallythese includes ✔Quadriceps mechanism ✔Gastrocnemius ✔Medial hamstrings ✔Lateral hamstrings ✔Popliteus ✔Iliotibial band
- 9. Extraarticular ligamentous structures Primarily theseincludes ✔The joint capsule ✔Medial collateral ligament ✔Lateral collateral ligament. Intra articular structures ✔Medial meniscus ✔Lateral menicscus ✔Anterior cruciate ligament ✔Posterior cruciate ligament.
- 10. FEMORAL ARTICULAR SURFACE ⮚Distal end of femur – 2 condyles (medial codyle is larger than lateral condyle) ⮚ Lateral condyle projects slightly anterior as compared to medial condyle ⮚ Lateral view: condyles are convex ⮚ Posteriorly: separated by intercondylar notch ⮚ Anteriorly: joined by patellar groove
- 11. TIBIAL ARTICULAR SURFACE •Medial condyle is larger . • Separated by intercondylar tubercle • Condyles are relatively flat, at the centre they are slightly concave. • Inclined posteriorly (7-10 degree)
- 12. MENISCI ❖Fibrocartilage structure ontibial condyle. ❖ medial is semilunar, lateral menisci is larger and forms 4/5th of a circular Functions: ❖ Increase area of articulation, hence increasing joint congruence and stability ❖ Shock absorber by distributing the force laterally and reduce the joint stress.
- 13. ◼ Meniscal Attachments Both Menisciare attached to Intercondylar tubercle of tibia. Tibial condyle via coronary ligament. Patella via patellomeniscal & patellofemoral ligaments Transverse ligament. ACL Med. Men. attached to: MCL. Semitendinosus muscle. Lat. Men. attached to: Ant. & Post. meniscofemoral ligaments. PCL. Popliteus muscle.
- 14. Menisci Nutrition &Innervation ❖ Established at 8 weeks of embryonal age. ❖ 1st year -well vascularised, ❖ Vascularity gradually reduces ,once weight bearing starts. ❖ At age of 50 only periphery is vascularized and central region is completely avascular. ❖ Central region receives nutrition via diffusion from synovial fluid ( Mostly during weight bearing ). ❖ Whole meniscal complex is well innervated by ❖ - Nociceptors ❖ - Mechanoreceptors –Golgi Tendon Organ, Ruffini corpuscles Pacinian corpuscles
- 15. KNEE JOINT CAPSULE -Superficial fibrous layer - Deep synovial layer • Attachments Posteriorly : Proximally to posterior margins of femoral condyles & inter condylar notch, distally to posterior tibial condyle. Medially & Laterally: Proximally above femoral condyle & distally margins of tibial condyle. Collateral ligaments reinforce sides of capsule. Anteriorly : Patella, Quadriceps muscle superiorly and patellar ligament inferiorly.
- 16. ●Extensor retinaculum: anteriorportion of capsule containing Quadriceps tendon, patella, patellar tendon and medial & lateral patellar retinaculum. • Transverse fibres connecting patella and condyles are known as medial and lateral patellofemoral ligaments. • Lateral & medial Patellomeniscal ligaments • Lateral & medial Patellotibial ligaments
- 17. Synovial Layer • Functions: -provides nutrition to avascular part of menisci - lubrication of joint • Anteriorly synovium adheres to anterior aspect and sides of ACL & PCL • Posteriorly, the synovium breaks away from the inner wall of the fibrous joint capsule • Laterally, lateral femoral condyle and Popliteus muscle • Medially, medial femoral condyle, semimembranosus and Gastrocnemius muscle.
- 18. KNEE JOINT LIGAMENTS •Ligament provides stability to incongruent knee joint. • prevents: 1.Excessive knee extension 2. Varus and valgus stresses at the knee. 3. Anterior or posterior displacement of the tibia. 4. Medial or lateral rotation of the tibia beneath the femur 5. Combinations of anteroposterior displacements and rotations of the tibia, together known as rotary stabilization of the tibia
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- 20. ANTERIOR CRUCIATE LIGAMENT •Origin : Posteromedial aspect of lateral femoral condyle • Insertion : medial tibial intercondylar tubercle • Directions: inferiorly, medially and anteriorly • 2 bundles :Anteromedial bundle (AMB), active during flexion Posterolateral bundle (PLB), active during extension • Function : -restricts anterior translation of tibia on femur -prevents hyperextension -Med. & Lat. rotation stability -valgus & varus stability -assist valgus stability of MCL • Least stress on ACL between 30-60 degrees of flexion • MOI- Hyperextension,rotational force , varus/ valgus force.
- 21. POSTERIOR CRUCIATE LIGAMENT •Origin : Anterolateral aspect of medial femoral condyle • Insertion : tibial plateau , between post. horns of both menisci • Direction: inferiorly and posteriorly • 2 bundles : Anterolateral bundle (ALB) – active in flexion Posteromedial bundle (PMB) – active in extension • Function : • Restricts posterior translation of tibia • Provides valgus/ varus stability • Rotational stability, • Hamstrings increase the load on PCL & relieve ACL • Quadriceps decrease the load on PCL • MOI- Dashboard injuries, Hyperflexion / Hyperextension, valgus/ varus force with foot planted.
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- 23. MEDIAL COLLATERAL LIGAMENT •Origin: medial femoral epicondyle just below adductor tubercle • Divided into superficial & deep fibres • Insertion : superficial part into medial border of shaft of tibia just distal to insertion of pes anserinus deep part into proximal tibia above groove of semimembranosus muscle • Function : -Restricts valgus stress -Restricts anterior translation of tibia -Prevents excessive lateral rotation of tibia • Most common injured ligament in knee
- 24. LATERAL COLLATERAL LIGAMENT •Origin : lateral femoral epicondyle • Insertion : fibular head • Function: -Restricts varus stress &lateral rotation. - Prevent hyperextension. -Efficiency of LCL is maximum in 30° flexion
- 26. BIOMECHANICS OF KNEEJOINT
- 27. Medial Tibio Femoralangle ●Anatomical (longitudinal) axis of femur is oblique directed medially & inferiorly from proximal to distal end ●Anatomical axis of tibia is almost vertical ●Mechanical axis passes from the head of femur to centre of knee joint to centre of calcaneum represents weight bearing axis ●Medial tibiofemoral angle = 185°, creating physiological valgus angle at knee joint.
- 28. GENU VALGUM Medial Tibiofemoralangle > 185° Increased compressive forces in lateral compartment Lateral compartment arthritis Ligaments on lateral side are lax Medial Tibiofemoral angle < 175° Increased compressive forces in medial compartment Medial compartment arthritis Ligaments on medial side are lax GENU VARUM
- 29. ● ●FLEX- roll anteriorly+ glide posteriorly EXT- Roll posteriorly+glideanteriorly KNEE JOINT DURING WEIGHT BEARING / TIBIA IS FIXED
- 30. Flexion : 0-25° -rolling posteriorly >25° - rolling posteriorly + glide anteriorly
- 31. ARTHROKINEMATICS – Roleof cruciate ligaments in Flexion/ extension ▪ Anterior glide is due to ⮚ -Tension of ACL ⮚ -The menisci ▪ Posterior glide is due to ⮚ -Tension of PCL ⮚ -The menisci
- 32. When Femur isfixed/ Non weight bearing Flexion : post. roll + post. glide Extension : ant. roll + ant. glide
- 33. Locking and unlockingmechanism of knee joint • Locking- ⮚ by closed kinematic chain extension from 30*flexion. ⮚ Larger medial femoral condyle continue rolling and gliding posteriorly when smaller lateral side is stopped. ⮚ medial rotation of femur-in last 5 degrees of extension. ⮚ by contraction of quadriceps and ligaments of knee joint • Unlocking -lateral rotation of
- 34. 3. LOCKING ANDUNLOCKING Non- weight bearing KNEE EXTENSION ⮚ The tibia glides anteriorly on the femur. ⮚ During the last 30 degrees of knee extension, anterior tibial glide persists on the tibia's medial condyle because its articular surface is longer . ⮚ Prolonged anterior glide on the medial side produces external tibial rotation, known as locking or "screw- home" mechanism.
- 35. UNLOCKING KNEE FLEXION ⮚ Whenthe knee begins to flex from a position of full extension, posterior tibial glide begins first on the longer medial condyle. ⮚ Between 0 -20 deg. of flexion, posterior glide on the medial side produces relative tibial internal rotation, a reversal of the screw- home mechanism. popliteus ‘unlocks’ the knee at the beginning of flexion of the fully extended knee. (popliteus provides an external rotation torque to the femur that mechanically unlocks the knee. )
- 36. • In weightbearing condition: - tibia is fixed ⮚ - the knee is mechanically locked by a combo of extension and slight IR of the femur on a fixed tibia ⮚ -unlocking the knee requires that the femur ER on the fixed tibia.
- 37. ▪ ROTATION • ROM:Med. Rotation- 0-15° Lat. Rotation – 0-20° (maximum in 90° flexion) • Medial condyle act as pivot point while the lateral condyle move through a greater arc of motion. • Lateral rotation of tibia: lat. Condyle moves posteriorly and med. condyle moves slight anteriorly. • Med. Rotation: lat. Condyle moves anteriorly and med. condyle moves slight posteriorly.
- 38. ABDUCTION AND ADDUCTION Occursin frontal plane around AP axis ROM: 13-20° (maximum in flexion) Abduction : 0-15° Adduction : 0-5°
- 39. KNEE EXTENSORS Vastus lateralis- laterally oriented 35° from midline Vastus intermedius – in line with long axis of femur. It is purest knee extensor Vastus medialis - medially oriented 40° from midline
- 40. vastus medialis has2 types of fibres • Longitudinal (vastus medialis longus [VML]) – 15- 18° • Oblique (vastus medialis oblique [VMO]) – 50-55° • VMO pulls the patella medially and thus helps in patellar stabilisation
- 41. ROLE OF PATELLAIN QUADRICEPS ⮚ Increase the moment arm of quadriceps ⮚ Increase the angle of pull of quadriceps ⮚ At 50° flexion , maximum torque is generated in quadriceps
- 42. QUADRICEPS LAG ⮚ Ifthere is substantial quadriceps weakness or if the patella has been removed because of trauma, the quadriceps may not be able to produce adequate torque to complete the last 15° of nonweightbearing knee extension.
- 43. KNEE FLEXORS • semimembranosus,semitendinosus, biceps femoris (long and short heads) (HAMSTRINGS) • sartorius • gracilis • popliteus • Gastrocnemius • except the short head of the biceps femoris and the popliteus, all of the knee flexors are two-joint muscles.
- 44. HAMSTRINGS ●the hamstring musclescross both the hip (as extensors) and the knee ●Actions: hip extension, knee flexion, medial and lateral rotation ●Provide valgus and varus stability ●Helps ACL muscle in anterior stability ●Five of the flexors (the popliteus, gracilis, sartorius, semimembranosus, and semitendinosus muscles) have the potential to medially rotate the tibia on a fixed femur ●biceps femoris laterally rotate the tibia ●The lateral muscles (biceps femoris, lateral head of the gastrocnemius, and the popliteus) are capable of producing valgus moments at the knee ●the medial side of the joint (semimembranosus, semitendinosus, medial head of the gastrocnemius, sartorius, and gracilis) can generate varus moments ●Semimembranosus: cause posterior distortion of medial menisci during knee flexion
- 45. GASTROCNEMIUS • Crosses boththe knee joint and the ankle joint. • Actions: knee flexion and ankle planter flexion • produces the greatest knee flexion when the knee is in full extension. As the knee is flexed, the ability of the gastrocnemius muscle to produce a knee flexion is significantly diminished. SARTORIUS • Knee flexion • Medial rotation of Tibia • Active only in swing phase
- 46. GRACILIS • Hip flexionand adduction • Knee flexion • Slight med. rotation of Tibia POPLITEUS • Small, single joint muscle • Medial rotation of tibia (unlocking of knee) • Attaches to lateral menisci, causes its deformation during knee flexion
- 47. GLUTEUS MAXIMUS &SOLEUS • Do not cross knee joint • cause knee joint extension in weight bearing
- 48. Stability of kneejoint ●Include: 1. Passive forces: capsuloligamentous structure 2. Active forces: various muscles
- 50.
- 51. ROLE OF PATELLA ⮚Anatomical pully – increase the moment arm of quadriceps ms. thereby increasing the pull of muscle ⮚ Decreases friction between quadriceps tendon and femoral condyles.
- 52. PATELLOFEMORAL JOINT CONGRUENCE ⮚ Extension– patella lies in patellar sulcus. ⮚ Flexion – lies in intercondylar notch. ⮚ Stabilized by med. & lat. Patellar retinaculum , med. & lat. Patellofemoral ligaments and various muscular connections. ⮚ Patellar alta – high riding patella due to increase length of patellar tendon. ⮚ Patellar baja – low riding patella due to length of patellar tendon. ⮚ Insall salvati index = length of patellar tendon & = 1:1 diagonal length of patella
- 53. PATELLA IN KNEE FLEXION/EXTENSION Thecontact between the patella and the femur changes throughout the knee ROM • full extension : inferior pole of patella. • Flexion=20° : inferior margin of med. & lat. Facet • Flexion=60° : complete patella except sup. Pole • Flexion=90° : complete patella • By full flexion, only the odd facets are making contact with the femur.
- 54. MOTIONS OF PATELLA •Flexion & extension : inferior glide + downward rotation in patellar flexion • Superior glide + upward rotation in • patellar extension • Medial & lateral tilt : direction toward which the anterior surface of the patella is tipping. • Medial & lateral shift : patella is moving toward the medial and lateral femoral condyles, respectively. • Medial & lateral rotation : with
- 55. PATELLOFEMORAL JOINT STRESS ⮚The patella is pulled simultaneously by the quadriceps tendon superiorly and by the patella tendon inferiorly. ⮚ The total joint reaction force depends on: • Magnitude of active or passive pull of quadriceps • Angle of knee flexion • 20 deg flexion: stress increase 25% to 50% of BW • During running, patellofemoral compressive forces reach between five and six times BW ⮚ In full extension: ⮚ - line of gravity is anterior - quadriceps pull is less
- 56. ⮚ In flexion:, -The center of gravity shifts posteriorly -increasing flexion movement is balanced by quadriceps muscle ⮚ - quadriceps pull is more ⮚ - stress is more
- 57. MECHANISM TO DECREASEPF JOINT STRESS Several mechanisms help minimize or dissipate the patellofemoral joint stress on the patella • Articular surface area: area increases, stress decreases • Hyaline cartilage • Quadriceps: patella acting as anatomical pulley increases quadriceps momentum and decrease quadriceps force • Condyles of femur – deflects the line of force of quadriceps reducing friction and hence decreasing stress
- 58. Stabilizers of patella ●Longitudinal -quadriceps - patellar tendon - longitudinal patellotibial ligaments ●Transverse - medial patellofemoral ligament - lateral patellofemoral ligament
- 59. Q- Angle ● Malestypically have Q- angles between 10 to 14° ● Females between 15-17° ● Q- angle of more than 20° or more is considered to be abnormal creating excessive lateral forces on the patella ● Factors increasing Q- angle - imbalance between the vastus lateralis and vastus medialis - genu valgum - medial femoral torsion -lateral tibial torsion there is an increased ⮚ .
- 60. ●When medial femoraltorsion and lateral tibial torsion coexist, the Q-angle will increase substantially, resulting in a substantial lateral force on the patella
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- 62. Common symptoms(History) • Pain •Swelling • Stiffness • Mechanical disorders-locking,giving way,click etc. • Limp
- 63. Inspection ✔ Gait- observept while entering clinic. • Stiff knee-swing outwards • Other conditions-lurching on sound side. ✔ Attitude- • moderate flexion(optimum positionof knee jt) in first stage tuberculous/acute arthritis • Triple displacement-flexion,post.subluxation &lat.rotation of tibia d/t hamstrings contraction –s/o cruciate &collateral ligaments destruction. • Abnormal abduction/adduction/hyperextension. • Locking –knee in flexed position with limping. • Anterior surface and position of patella noted
- 64. Inspection contd. ✔ Anyobvious deformity ✔ Observe the patient in standing,seated,supine and prone on couch ✔ Observe the patient from front,side and back. ✔ Look for any evidence of shortening ✔ Any compensatory mechanism ✔ Gross shortening ✔ Muscle wasting ✔ Any swelling ✔ Any scar • Active sinus • Healed sinus • Scars of old surgery
- 65. Palpation • Temperature • Tenderness •Swelling • Deformity • Anterior knee palpation • Posterior knee palpation • Medial knee palpation • Lateral knee palpation
- 66. Swelling • Inspectory findingsconfirmed by palpation. • Fluctuation test-pressing supra patellar pouch and feeling impulse with other thumb &fingers. • Patellar tap-pathognomonic of knee joint effusion but for moderate fluid. • For small amount fluid-sides of ligamentum patellae hollow space will be refilled slowly after pressing it. • Thickened synovial membrane-spongy and boggy feel with Absent patellar tap. • Enlarged semimembranosus bursa appears on extension of knee and disappears on its flexion.
- 67. Range of motion •Evaluation of active ROM. • If movement limited by pain, weakness or tightness, assist passively • Bilateral evaluation for comparison.
- 68. Special Tests • Patella-Patellar Grind Test (compression test) • ACL- (Ant. Drawer test, Lachman test) • PCL -(Post. Drawer test, Posterior sag sign) • MCL- Valgus stress test • LCL- Varus stress test • MENISCUS- Apley’s grinding, Mc.murray’s test
- 69. Patellar Grind Test •Patient-supine • Knee extended • The examiner places web space of thumb on superior border of patella • Ask the patient to contract the quadriceps • Examiner applies downward and inferior pressure on patella • Pain is indicative of patellofemoral dysfunction
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- 71. Anterior drawer test •Patient-supine • Hip flexed 45*, knee flexed 90* • Examiner sits on patient’s foot • Hands behind the proximal tibia and thumbs on tibial plateau • Anterior force is applied • Hamstring tendons are palpated with index fingers to ensure relaxation • Increased tibial displacement is indicative of ACL tear.
- 72. Lachman Test • Patient-supine •Knee held b/w full extension and 15*flexion • Femur is stabilised with one hand • Firm pressure is applied on posterior aspect of proximal tibia in attempt to translate it anteriorly.
- 73. Pivot Shift Test •Patient -supine • Leg is picked up at ankle • Knee is flexed by placing heel of the hand behind the fibula • As the knee is extended, tibia is supported on lateral side with slight valgus strain. • A strong valgus force is placed on knee by upper hand • At approx 30*flexion the displaced tibia will suddenly reduce indicating positive test.(ACL TEAR)
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- 75. Posterior Drawer Test •Patient-supine • Hip flexed 45*, knee flexed 90* • Examiner sits on patient’s foot • Hands behind the proximal tibia and thumbs on tibial plateau • Posterior force is applied • Hamstring tendons are palpated with index fingers to ensure relaxation • Increased tibial displacement is indicative of PCL tear.
- 76. Posterior Sag Sign •Patient-supine • Hip flexed 45*, knee flexed 90* • Tibia ‘rocks back’ or ‘sags back’ if PCL is torn. • Normally medial tibial plateau extends 1cm anterior beyond femoral condyle (knee 90* flexion).
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- 78. Valgus stress test •Patient-supine • Examiner grasps the distal leg and provide a valgus force to the knee. • Tests the medial collateral ligament. • The test should be completed with the knee in 20-30* of flexion and also with the knee in full extension to test medial capsular integrity.
- 79. Varus stress test •Patient-supine • Examiner grasps the distal leg and provide a varus force to the knee. • Tests the lateral collateral ligament.
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- 81. Joint Line Tenderness •MKJL is easier to palpate with tibial internal rotation. • Alternatively external rotation allows improved palpation of the lateral meniscus.
- 82. Mc.murray’s Test • Patientsupine • Knee is first fully flexed • The foot is held by grasping the heel • The leg is rotated on the thigh knee still in full flexion. • The leg is brought from actute flexion to right angle while the foot is retained first in full IR And then in full ER. • Click indicates meniscal tear
- 83. Apley’s Grind Test •Patient- prone • Patient flexes affected knee to 90* • Examiner’s one hand grasps patient,s heel and ankle while the other hand stabilises the leg. • Examiner compresses the flexed knee joint and menisci by pushing the patients foot and tibia down the table by internal and external rotation of tibia • Pain on the medial/lateral aspect indicates a medial/lateral meniscal injury
- 84. Complaints ✔ Pain ✔ limp ✔Locking ✔ Swelling ✔ Stiffness ✔ Deformity ✔ Weakness ✔ Instability ✔ Parasthetia ✔ Loss of function
- 85. Differential Diagnosis InKnee • Trauma ✔ Patella fracture ✔ Knee dislocation ✔ Tibial plateau fracture • Arthritis ✔ Osteoarthritis ✔ Rheumatoid arthritis ✔ Traumatic arthritis • Tumor • Infectios •Knee lesions ✔ Articular cartilage defects of knee ✔ Osteonecrosis of knee ✔ Spontaneous osteonecrosis of knee ✔ Plicae •Paediatric conditions ✔Osteochondritis dissecans ✔Osgood schlatter’s disease
- 86. Differential Diagnosis inKnee • Sports conditions ✔ Ligament injury – ACL tear – PCL injury – MCL Injuries – LCL INJURIES – Posterolateral corner injury – Proximal tibiofibular dislocation ✔ Meniscal injuries – Medial meniscal tear – Lateral meniscal tear ✔ Knee overuse injuries – Patellar tendinitis – Quadriceps tendinitis – Semimembranosus tendinitis – Prepatellar bursitis(housemaid’s knee) – Illiotibial band friction syndrome ✔ Knee extensor mechanism • Patellofemoral joint • Patellar instability • Lateral patellar compression syndrome • Idiopathic chondromalacia patellae • Quadriceps tendon rupture • Patella tendon rupture
- 87. REFERENCES ●Joint structure andfunction. Pamela k Levangie, Cynthia C Norkin, 5th edition. ●Kinesiology, The Mechanics and Pathomechanics of Human Movement. Carol Oatis
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