Transcript Knee Evaluation knee_evaluation
KNEE EVALUATIONS
Quick Facts
Patellofemoral Joint (PFJ) Variations in PFJ loading during OKC and CKC activities PFJ loading increases: – with increased flexion in CKC – with increased extension in OKC PFJ Loading Walking – 0.3 x body weight Ascending Stairs – 2.5 x body weight Descending Stairs – 3.5 x body weight Squatting – 7 x body weight
History
MOI – Position of lower extremity at time of injury (?foot planted, knee extended) Previous history Pain (levels, types, descriptors) Unusual sounds/sensations “pop, clicking, snapping” Chronic vs. acute Location of pain “inside the knee” Surface Shoes Type of activity at time of injury Painful to walk up/down stairs; any clicking, catching Did it swell immediately, slowly?
Is the swelling located in the knee or in a pocket?
Observation
Bilateral comparison Gait (limp, walking on toes, do they not want to extend knee, do they keep the knee stiff) Swelling (girth measurements) Discoloration Deformity (squinting patellae, “Frog-eyed” patellae, Patella alta, Patella baja) Genu valgum, genu varum, recurvatum Musculature – defined/mushy
Q-angle
The quadriceps angle (Q-angle) is the angle formed between a line drawn through the tibial tuberosity and the center of the patella and another line drawn from the anterior superior iliac spine (ASIS) of the pelvis through the center of the patella.
Q-angle
Knee in extension – Normal males: 13 degrees – Normal females: 18 degrees Knee in 90 degrees flexion – Both genders: 8 degrees
Structural Alignment
Genu Varum (Bowlegged) Genu Valgum (knock kneed)
Boney Palpation
Tibia – Tibial tuberosity – Tibial Condyles (medial + lateral) Fibula – Head Medial joint line Medial collateral ligament Lateral joint line Lateral Collateral Ligament “Windows” Medial & Lateral Femoral Epicondyles Pes Anserine Hamstrings – Semitendinosus tendon – Semimebranosus – Biceps femoris tendon Quadriceps muscle group – Rectus Femoris – Vastus Lateralis – Vastus Intermedius – Vastus Medialis Oblique Biceps femoris tendon Iliotibial band Popliteal fossa Gastrocnemius heads Patella Patellar tendon
Boney Palpation
Tibia – Tibial tuberosity – Tibial Condyles (medial + lateral) Fibula – Head Medial & Lateral Femoral Epicondyles Patella
Surface Anatomy
Patella (A) Femur (B) Tibia (C,E – tuberosity) Joint Line (D) Fibula (F)
Boney Anatomy
Bony Anatomy – Lower Leg Tibia – Bears most of the weight Fibula – Attachment place for muscles & ligaments – Upper Leg Femur – Patella
Patella
Sesamoid bone Imbedded in quadriceps & patella tendon Serves similar to a pulley for improving angle of pull (results in greater mechanical advantage in knee extension)
Tendons + Ligaments
Medial joint line Medial collateral ligament Lateral joint line Lateral Collateral Ligament “Windows” Pes Anserine – Semitendinosus tendon – Gracilis tendon – Sartorius tendon Semimebranosus tendon Biceps femoris tendon Quadriceps Tendon Biceps femoris tendon Iliotibial band Patellar tendon
Internal Knee Anatomy
Internal Knee Anatomy
Medial Meniscus Lateral Meniscus Anterior Cruciate Ligament Posterior Cruciate Ligament Articular Cartilage
Menisci
Bursae & Fat Pad of the Knee
Cruciate Ligament Movement
Anatomy – Soft Tissue
Quadriceps – – Rectus femoris – Vastus lateralis – Vastus intermedius – Vastus medialis oblique Hamstrings – – Biceps femoris – Semitendinosus – Semimembranosus Popliteus – Popliteal fossa Gastrocnemius + Soleus Tibialis Anterior
Muscles
Quick Facts
Tibiofemoral Joint (TFJ) Normal ROM – Flexion 135-140 degrees – Extension 0 degrees Closed Pack Position – Full extension with ER Loose Packed Position – 25 degrees of flexion
Knee Movements
Screw Home Mechanism
Locking mechanism as the knee nears its final extension degrees – Automatic rotation of the tibia externally (approx. 10 degrees) during the last 20 degrees of knee extension Femoral condyles are a different size – Medial has larger surface area The tibia glides anteriorly on the femur. As knee extends, the lateral femoral condyle expends its articular distance. The medial articulation continues to glide, resulting in external rotation of the tibia utilizing the lateral meniscus as the pivot
point.
ACL & PCL are rotary guides
Special Tests
Myotomes and Dermatomes Valgus Stress test Varus Stress Test Tinel Test Apley McMurray Anterior Drawer Lachmans Posterior Drawer Godfrey’s 90/90 Posterior Sag Patellar Apprehension Test Clark’s Sign
Stress/Special Tests
Check for swelling Check ROM Check integrity of ligaments & joint stability – Valgus, Varus, Lachman’s, Anterior/Posterior Drawer, Godfrey’s 90-90 Test/Posterior Sag Test, Check integrity of meniscus – McMurray’s, Apley’s Compression/Distraction, Duck Walk, Check integrity of patella – Patellar Apprehension, Q Angle, Clarke’s Sign,
Special Tests
Anatomy of the ACL
3 strands Anterior medial tibia to posterior lateral femur Prevent anterior tibial displacement on femur Secondarily, prevents hyperextension, varus & valgus stresses
Biomechanics of the ACL
Most injuries occur in Closed Kinetic Chain Least stress on ACL between 30-60 degrees of flexion Anteromedial bundle tight in flexion & extension Posterior lateral bundle tight only in extension
ACL Tears
Most common mechanisms – Contact:
CKC with foot ER w/ valgus stress Hyperextension direct hit on the posterior tibia
– Non-Contact:
Most common Due to sudden deceleration Sudden landing, cutting, or pivoting
Patient will c/o “buckling” or “giving away”, typically will hear and/or feel a “pop”
Diagnostic Imaging
Why perform an MRI after ACL injury?
Anterior Lachmans
Position: – Supine – Knee flexed to 20 – 30 degrees – Proximal hand on Femur above the patella, distal hand on Tibia just below Tibial Tuberosity Action: – Apply anterior force to the tibia with the distal hand while stabilizing the femur with the proxmial hand Positive Findings: – Anterior Cruciate Ligament Sprain Joint opening up
Anterior Drawer
Position: – Hip flexed to 45 o ; knee flexed @ 90 o – Foot on table in neutral – Examiner sits on foot w/ B hands behind the subject’s proximal tibia and thumbs on the tibial plateau Action: – Apply anterior force to the proximal tibia, feeling the hamstrings for tightness Positive Findings – Anterior Tibial Displacement – Anterior Cruciate Ligament Sprain
PCL Biomechanics
Functions: – Primary stabilizer of the knee against posterior movement of the tibia on the femur – Prevents flexion, extension, and hyperextension Taut at 30 degrees of flexion – posterior lateral fibers loose in early flexion
Posterior Cruciate Ligament
Two bundles – Anterolateral, taut in flexion – Posteromedial, taut in extension Orientation prevents posterior motion of tibia PCL larger & stronger than ACL – CSA 120-150% larger – CSA AL 2x PM Consider associated role of posterolateral complex when discussing PCL – LCL – Popliteus Complex – Arcuate Ligament – Posterior Lateral Capsule
PCL Injuries
Very rare in athletics, usually due to MVA – Due to hyperextension, hyper flexion, or the tibia being forced posteriorly on the femur – Only 33% related to sports Isolated PCL Injuries unusual – Assess other ligaments Avulsion Injuries Mid-Substance Tears
Posterior Drawer Test
Position: – Hip flexed to 45 o ; knee flexed @ 90 o – Foot on table in neutral – Examiner sits on foot w/ B hands behind the subject’s proximal tibia and thumbs on the tibial plateau Action: – Apply posterior force to the proximal tibia Positive Findings – Posterior Tibial Displacement – Posterior Cruciate Ligament Sprain
Godfrey’s 90/90Test
Position: – Hip flexed to 90 o ; knee flexed @ 90 o – Examiner holds onto both heels Action: – Look for posterior translation of the tibia Positive Findings – Displacement of the Tibia – Posterior Cruciate Ligament Sprain
Posterior Sag Test
Position: – Lie on table Knee flexed to 90 o ; Hip flexion 45 o Action: – Subject actively flexes Quads while hip remains in 45 Femur o – Look for a posterior translation of the Tibia in relation to the Positive findings: – Posterior Cruciate Ligament Sprain
MCL Biomechanics
Primary role is to prevent against a valgus force and external rotation of the tibia Throughout Full Range of Motion: – Both fibers are taut in full extension – Anterior fibers are taut in flexion – Posterior fibers are taut in mid range
MCL Sprains
Typically due to valgus forces in CKC – Foot typically in neutral or externally rotated Most frequently injured ligament in the knee Usually no joint effusion unless deep portion affected since primarily located outside the joint capsule
Valgus Stress Test
Position: – Knee @ 0 o and knee @ 30 o – Proximal hand on Lateral joint line – Distal hand on the lower leg Action: – Apply medial force to lateral joint line; and lateral force to distal tibia Positive Findings – Medial Collateral Ligament Sprain
LCL Biomechanics
Primary role is to protect from varus forces and external rotation of the tibia, assists in 2 ° restraint for anterior and posterior tibial translation Throughout Range of motion: – Is taut during extension – Loose during flexion Especially after 30 ° of flexion
LCL Sprains
Typically due to varus forces, especially in CKC position with leg adducted and tibia internally rotated Usually occur during contact sports Typically has limited joint effusion since it is located outside of the joint capsule
Varus Stress Test
Position: – Knee @ 0 line o and knee @ 30 o – Medial hand on Medial joint Action: – Apply lateral force to medial joint line; and medial force to distal tibia Positive Findings – Lateral Collateral Ligament Sprain
Meniscal Functions
Deepens the articulation and fills the gaps that normally occur during the knee’s articulation Primary Functions – Load distribution – Joint Stability – Shock Absorption Secondary Functions – Joint Lubrication – Articular Cartilage Nutrition – Proprioceptive Feedback
Mechanism of Injury
Trauma – Compression – Rotational Force – Valgus Force – Usually Combination of Forces Degenerative Changes – Greater than 30 years old – No PMHX required – Often due to MOI that “seemed harmless” at time
Noyes, 2002 states 60% of meniscal injuries associated with ACL injury
Apley
Compression – Position: Prone Knee flexed to 90 o dorsiflexed – Action: ; foot Stabilize the femur with examiner’s knee Push down on ankle/lower leg and rotate – Positive findings: Pain = Meniscus No Pain = Ligament involvement Distraction – Position: Prone Knee flexed to 90 o dorsiflexed – Action: ; foot Stabilize the femur with examiner’s knee Pull up on ankle/lower leg and rotate – Positive findings: No pain = Meniscus Pain = Ligament involvement
McMurray
Position: – Supine – Examiner’s standing with distal hand grasping the subject’s heel; proximal hand on subject’s knee with fingers palpating the medial and lateral joint lines Action: – Knee fully flexed, externally rotate the tibia and introduce a valgus force and extend the knee Medial Meniscus – Repeat with internal rotation of the tibia and Varus force.
Lateral Meniscus Positive Findings: – “Clicking” indicates a Meniscal Tear Medial side = medial meniscus Lateral side = lateral meniscus
Unhappy Triad
MCL, ACL, Medial Meniscus Typically due to a valgus force with the foot planted
PFJ Biomechanics
During extension, patella glides cranially During flexion, patella glides caudally Patellar compression – OKC greatest at end range (final 30 degrees) – increases in CKC after 30 degrees of flexion
Patellofemoral Pain Syndrome
General term to describe anterior knee pain Caused by a variety of factors:
Signs & Symptoms: – Poorly localized Pain – Little to no swelling – Pt. Tenderness under lateral patella – Insidious onset
Clark’s Sign (Patellar Grind Test)
Position: – Patient is lying supine w/ knee extended – Examiner places the web space of the thumb on the superior border of the patella Action: – Subject contracts the Quads while the examiner applies downward and inferior pressure to the patella Positive Finding: – Pain with movement of patella or inability to complete test – Chondromalacia patella or patellar femoral syndrome
Patellar Apprehensive Test
Position: – Patient is supine and relaxed Action: – Examiner grabs patella and pushes it in all 4 ways Superior / Inferior Lateral / Medial Positive Findings: – Patient Apprehension – Excessive Movement in one direction – Dislocating Patella