Lecture 15 - Knee Injuries pt.2 Flashcards
What are the 3 layers of the Medial Support Complex
- superficial
- middle
- deep
what structures are found in the superficial layer of the medial support complex?
- sartorius and fascia
what structures are found in the middle layer of the medial support complex?
- superficial MCL and semimembranosis
what structures are found in the deep layer of the medial support complex?
- deep fibres of the MCL and capsule
What contributes to the stability of the medial support complex?
- MCL (strongest at 20-30 degrees) –> ACL and PCL are secondary vs. valgus
- Muscle help in full extension –> medial hamstrings, medial head of gastrocs and quad muscles
- Bony structure is tertiary support
What is the MCL?
- medial collateral ligament
- a capsular ligament (swells)
Where are the superficial and deep components of the MCL?
- deep = connect directly to the medial meniscus
- superficial = run from medial femoral epicondyle to superomedial surface of tibia
What is the distribution of knee structures resisting at 5 degrees?
- superficial MCL = 57%
- deep MCL = 8%
- posterior oblique = 18%
what is the distribution of knee structures resisting at 25 degrees?
- superficial MCL = 78%
- deep MCL = 4%
- posterior oblique = 4%
Where is the ACL located?
- anterior aspect of tibial plateau to posterior medial aspect of lateral femoral condyle
- “up and around”
what are the two bundles/bands of the ACL?
- anteromedial –> tighter in flexion
- posterolateral –> tighter in extension
What is the main role of the ACL?
- primary restraint to anterior tibial translation
- greatest translation occurs at 20-30 degrees (so test at this range)
What is the stabilizing role of the ACL?
- restrict posterior translation of femur relative to the tibia during weight bearing
- restrict anterior translation of tibia during non-weight bearing
- limits excessive rotation of the tibia
- secondary support for valgus and varus with collateral ligament damage
which of the cruciate ligaments is weaker?
- the ACL
- this is why it is injured so much easier/ more often
where is the PCL located?
- originated on the lateral aspect of the medial femoral condyle and inserts posteriorly to the intercondylar area of the tibia
what are the two bundles/bands of the PCL?
- anterolateral –> tight in flexion
- posteromedial –> tight in extension
- slight sideways translation at extension due to the screw home mechanism
what is the main role of the PCL?
- primary restraint to posterior tibial translation
- greatest translation occurs at 20-30 degrees
Where is the PCL located in relation to the ACL?
- passes medial to the ACL
- located posterior to the ACL
what is the stabilizing role of the PCL?
- restricts anterior translation of the femur relative to the tibia during weight bearing
- restricts posterior translation of the tibia during non-weight bearing
- limits hyper-internal rotation
- secondary support for valgus and varus with collateral ligament damage
what is the role of the meniscus?
- an essential role in maintaining knee function
- stabilize knee by increasing concavity of tibia (more depth so more stability)
- shock absorption (full extension = 45-50% of load, 90 degree flexion = 85% of load)
- compression facilitates distribution of nutrients
compare and contrast the medial and lateral meniscus
Medial
- c-shaped
- large radius of curvature
- tight connection with capsule and MCL
- poor mobility
- many issues/ bad news
Lateral
- O-shape
- small (tighter) radius of curvature
- loose connection with capsule and popliteal tendon
- increased mobility
What is meniscal fixation?
- menisci are fixed in place and prevented from extruding by coronary ligaments and anterior/posterior transverse meniscal ligaments
- deep portion of capsule attached to periphery of meniscus
- medial is thicker/tighter than lateral
Which menisci is injured first and why?
- medial injures first and often (because tighter)
- lateral injuries are more catastrophic due to how mobile it is
What are the three different zones of the Menisci?
- red-red zone
- red-white zone
- white-white zone
what are the characteristics of the red-red zone?
- good blood supply
- outer 1/3
- heals easier (stitches and rehab/recovery)
- will supply
what are the characteristics of the red-white zone?
- minimal blood supply
- middle 1/3
what are the characteristics of the white-white zone?
- no blood supply/ avascular
- inner 1/3
- will not heal on its own, removal/cut out
what is the goal of clinical perspective in knee injuries?
- to assess knee and determine degree of injury
what must you consider in a clinical perspective?
- subjective findings and objective examination findings
what might you look for in subjective findings?
- area of pain (medial vs. lateral vs. deep)
- MOI (varus or valgus, contact or non-contact)
- sounds (pop or crack)
- locking? (meniscus usually)
- did you see it coming? (last second turning to avoid hit)
- pain and disability at time of injury
- presence and timing
- onset of swelling
- degree of disability (could they continue?, could they stand?)
what might you look for in objective examination findings?
- observation
- STTT
- special tests (could include neuro)
- palpation
What is hemarthrosis?
- bleeding into the joint
- quick swelling (noticeable usually within the first 2 hours)
What percentage of knee assessments result in ACL tear diagnosis in adults?
- > 75%
what is the most common knee injury in young (11-14) patients?
- patellar dislocation
- then fractures and meniscal tears
why is it important to learn the past trauma of patients?
- because when checking for swelling and dislocations, would need to know past injuries in case one side looks/feels different
What are Ottawa Knee Rules?
A knee X-ray is only required if any of the following:
- age 55 or older (bone density)
- isolated tenderness of the patella (and nowhere else in the knee)
- tenderness of the head of the fibula
- cannot flex to 90 degrees
- unable to bear weight immediately and in ER for 4 steps (regardless of limping)
what type of patella dislocation is more common?
- lateral dislocation
what is a patella dislocation?
- when the patella moves out of its groove (usually laterally) onto/over the femoral condyle
What is the MOI of acute patella dislocation?
- forceful knee rotation (tibia ER/femur IR) +/- forceful quadriceps contraction
- knee usually near full extension (out of trochlea)
- +/- laterally directed force
What are the symptoms of a patellar dislocation?
- a possible feeling of “knee shift”, “move” or “pop out”
- pain ++ until reduced (less pain once put back in place)
- fast swelling (hemoarthrosis)
what are the signs of a patellar dislocation?
- loss of knee function (if still dislocated)
- tenderness over the medial border of the patella (bc. torn everything medially for it to shift)
- positive lateral apprehension test
- need to R/O ACL (because would also have swelling and similar subjective findings)
how do you put a dislocated knee back in place?
- relocate at the same position as MOI
- slightly flex the hip
- slowly extend the knee
- should relocate on its own (if it doesn’t do not force it, might be an underlying fracture)
- always send for X-Rays immediately
What are the 3 layers of the lateral support complex?
- superficial
- middle
- deep
- and support from muscles
what are the structures of the superficial layer of the lateral support complex?
- iliotibial band and biceps femoris
what are the structures of the middle layer of the lateral support complex?
- patellofemoral ligaments
- retinaculum
what are the structures of the deep layer of the lateral support complex?
- lateral (tibial) collateral ligament (LCL)
- popliteus tendon
- capsule
- other ligaments
What is the MOI of an LCL injury?
- less common but more complicated
- usually varus loading +/- hyperextension
- most contribution at 20-30 degrees of knee flexion
- may include ITB, lateral hamstrings and/or popliteus (test these too because usually injured with LCL)
What is the MOI of lateral spread?
- usually varus
what is the MOI of medial spread?
- usually valgus
What is the MOI of an MCL injury?
- most frequently injured knee structure (40% involve MCL)
- valgus force with or without rotation
- often occur in isolation (without other structures getting injured)
What are the signs/symptoms of collateral ligament sprains?
- pain over structure
- minimal swelling = LCL
- slow localized swelling = MCL
- stress testing = in same direction of MOI (for either)
- valgus stress = MCL (tested at 0 and 20-30 degrees)
- varus stress = LCL (tested at 20-30 degrees)
- graded 1-3
what are the characteristics of each grade of a sprain?
- grade 1 = pain with no laxity
- grade 2 = pain with laxity, but a distinct end point
- grade 3 = pain variable with gross laxity and no endpoint
What are the common mechanisms of ACL Injuries?
- contact or non-contact mechanism
- usually during cutting or single limb landing
- may occur in isolation or with other injuries
- 2-10x higher rate in females
what other injuries may occur with an ACL injury?
- 75% meniscal injuries
- 80% have bone bruise on lateral joint line (lateral knee pain from bones hitting each other)
What are the four MOIs of ACL tear?
- valgus after MCL - usually with contact
- deceleration/internal rotation - non-contact
- hyper-extension (not straight hyperextension unless everything else is also torn)
- quads active - anterior tibial translation (quads fire more than hamstrings)
what is the quads active mechanism of ACL injury?
- rapid deceleration and untoward landing
- shoe- surface interface friction
- anterior tibial dislocation by quads (hamstrings not on)
- causes bone bruising
what are the symptoms of ACL tears?
- ~80% describe an audible pop/crack
- range from very painful to minimal pain
- usually unable to continue activity
- hemarthrosis (> 75% 1-6 hours)
- instability/ giving way
what are the signs of ACL tears?
- restricted movement (especially extension)
- lateral joint tenderness (mistaken for LCL) - 80% have a lateral bone bruise or segond fracture
- positive anterior drawer and Lachman’s tests (which is better than anterior drawer because of hamstrings being inactivated)
- graded like other ligaments (pain, endpoint, laxity)
what are the common characteristics of posterior cruciate ligament injuries?
- strongest of the knee ligaments
- 1/10 are PCL tears (9/10 are ACL)
- ~60% include injuries to other structures (usually meniscal tears)
- usually sports injuries but also common in MVA (motor vehicle accidents)
What are the common MOIs of PCL injuries?
- direct blow to the upper portion of the tibia (fall on flexed knee or MVA dashboard trauma)
- hyper-flexion (increased tension in anterior segment and impingement)
- hyperextension
what are the symptoms of PCL injuries?
- feeling of a pop in the posterior knee
- poorly defined pain in the back of the knee
- minimal swelling at time of injury
what are the signs of PCL injuries?
- minimal swelling
- posterior drawer test (tibia will fall back)
- sag test will be positive (shin sags in leg up crunch position if PCL is gone)
- need to assess medial and lateral structures as well
what is patellofemoral pain?
- pain in the peripatellar/retropatellar area that is aggravated by at least one activity that loads the patellofemoral joint during weight bearing on a flexed knee
what are examples of flexed knee activities that may trigger pain with PFP?
- pain walking down the stairs
- pain with squatting
- pain following sitting for long periods
- running, jumping, hopping
what are the statistics of patellofemoral pain?
- 10-25% of all PT visits are for patellofemoral pain syndrome
- conflicting evidence
- evaluating overuse injuries to identify factors that may contribute to the condition
what are the possible causes of PFP?
- uneven pressure distribution across the back of the patella
- medial hypo-pressure = cartilage degeneration from inside-out
- lateral hyper-pressure = cartilage rub and fibrillation
what are the 5 proposed intrinsic factors of PFP?
- lower chain alignment
- excessive pronation
- poor multi-plane lumbo-pelvis/pelvo femoral control (core and glutes)
- shortened muscles (it band, hamstrings, calves, and rectus femoris)
- pull of quads
How does lower chain alignment cause PFP?
- valgus Q angle
- greater Q angle = greater lateral pull
- q angle > 20 increases risk of instability of PF joint
- can cause PFP syndrome, OA and ITB friction syndrome
How does excessive pronation cause PFP?
- over-pronation at the subtalar joint causes internal rotation of the tibia and delayed re-supination
- affects screw-home mechanism (tibia can’t externally rotate)
- femur is forced to internally rotate more to get to extension
- causes lateral pull on the patella
what is medial collapse mechanism?
- hip adduction, femoral knee rotation and knee valgus
- change femur under patella (decreased joint contact area and increases joint stress)
- pull on IT band to more patella
how does shortened muscles cause PFP?
- quads = increased compression of PF joint
- hamstrings = require increase in quads force production to overcome length issue
- IT band = increases pressure over the lateral surface of the trochlear groove, moves over femoral condyle at 25-30 degree flexion
- gastrocs and soleus = limit dorsiflexion, compensated with excessive rotation of lower leg and altered Q angle
what is vastus medialis dysfunction?
- sum of all 4 quads and tibial tendon are offset into valgus
- weak oblique VM will not be able to maintain alignment (slow, weak, altered line of pull)
- will cause abnormal pull on the patella (will pull sideways or at 45, want it to pull straight up)
what are PFP pain treatments?
- identify and correct the intrinsic and extrinsic issues
- difficult to manage
- different for each individual
what are the pain treatments for the 3 phases?
- initial phase = police/peace and love, relative rest, palliate pain, decrease swelling and identify issues
- repair phase = correct biomechanical issues (muscle length, muscle strength and function)
- remodeling phase = slowly increase FIIT
what are the evidence-based practice tips for PFP rehab?
- daily exercise of 2-4 sets of >10 (20-30) reps for 6 weeks (for running/jumping athletes)
- patellar taping and knee bracing (if it works, if not, don’t do it)
