AT 359
Chapter 20 - The Knee & Related Structures

Anatomy:
Patella - largest sesamoid bone; it "tracks" through the trochlear groove of the femur
Tibia - weight bearing bone; it articulates with the femur (tibiofemoral joint)
Fibula - non-weight bearing bone; it articulates with the tibia but not the femur
Medial Meniscus - c-shaped fibrocartilage attached to medial tibial facet
Lateral Meniscus - o-shaped fibrocartilage attached to latera tibial facet

Meniscal blood supply - has very poor blood supply especially to inner zone
        -3 zones with the outermost getting more blood supplied to it

Major Ligaments:
-Anterior Cruciate Ligament
        -prevents anterior movement of the tibia on the femur
        -also protects against excessive internal rotation and is secondary stabilizer for varus and valgus stresses
        -works in conjunction with the hamstring muscles to stabilize knee
-Posterior Cruciate Ligament
        -prevents hyperextension of the knee
        -also prevents posterior movement of the tibia on the femur
        -3x as strong as ACL
        -PCL injuries may present themselves as ACL injuries if you are not careful on the special tests
-Medial Collateral Ligament
        -has two bands, superficial and deep
                -the deep layer is attached to the joint capsule and medial meniscus
        -protects against valgus and external rotational forces
-Lateral Collateral Ligament
        -cord-like ligament
        -protects against varus and internal rotational forces

Joint Capsule:
-Structures contained inside joint capsule are the ACL, PCL and meniscii
-Swelling in joint capsule is generalized in nature

Muscles:

Bursae - synovial fluid filled sacs to prevent excess friction between tissues
        -Suprapatellar, Infrapatellar, Prepatellar, gastrocnemial bursas are the most often injured

Fat Pads - serves to protect and cushion the knee
        -Infrapatellar fat pad is the largest; separates the patellar tendon and the joint capsule

Nerve Supply -
        -tibial nerve innervates most of the hamstrings and gastrocnemius muscles
        -femoral nerve innervates the quadriceps and sartorius muscles
        -the common peroneal is vulnerable where it splits around the proximal fibular head

Blood Supply-
        -Popliteal artery stems from the femoral artery to supply the knee
                -it branches into different arteries called genicular arteries

Measuring Leg Alignment:
-patellar malalignment
        -patella baja or alta; squint-eyed or bug-eyed patella
-patellar orientation
        -tilted
-genu valgum
        -knock-kneed
-genu varum
        -bowlegged
-genu recurvatum
        -swayback or "back" knees; also called cheerleader knees

Swelling of the knee:
-Intracapsular - inside the joint
        -hemarthrosis
        -generalized swelling
-Extracapsular - outside the joint
        -localized swelling

Girth Measurement
-it is essential to measure swelling and atrophy after a knee injury
-there are 5 sites that measurements are usually taken:
        1) 8 cm above joint line
        2) 2 cm above joint line
        3) joint line
        4) tibial tuberosity
        5) gastrocnemius belly
-some use the mid patella for measurement

Q angle:
-angle created by lines drawn through the ASIS(line of femur) to mid patella and mid patella to tibial tuberosity
-angles greater than 20 degrees can predispose an athlete to patellar femoral problems
            -normal male angle = 10 degrees
            -normal female angle = 15 degrees

A angle:
-angle created by lines drawn through the patella longitudinally and from the tibial tuberosity to the apex of the inferior pole of the        patella
-angles greater than 35 degrees indicate greater risk for patellofemoral problems

Special Tests:
-Valgus
        -tests MCL stability
        -should be done at 0 and 30 degrees
        -worse if loose at 0 degrees
        -positive indicator is laxity
-Varus
        -tests LCL stability
        -should be done at 0 and 30 degrees
        -positive indicator is laxity
-Anterior Drawer
        -tests ACL stability
        -should be done in 90 degrees of knee flexion
        -a torn PCL can give a false positive sign
        -positive indicator is laxity
-Lachman's
        -can be done several ways
        -knee is always in 30 degrees flexion
        -tests ACL integrity
        -positive indicator is laxity
-Posterior Sag
        -patient is supine with knees in 90 degrees flexion
        -a torn PCL will cause the tibia to drop in its resting position
                    -the tibial tuberosity will not be as visible
-Posterior Drawer
        -patient is supine with knees in 90 degrees of flexion
        -same as anterior, but opposite direction
        -tests PCL integrity
        -positive indicator is laxity
-McMurray's
        -tests for meniscal tears
        -as the knee is extended, a valgus force is applied to the knee with the lower leg externally rotated
        -do the same thing again, but witha a varus force and the lower leg internally rotated
                -whichever way the knee is being pushed, turn the foot the opposite direction
        -positive indicator is pain and clicking
-Apley's Compression & Distraction
        -patient is prone
        -tests for meniscal tears
        -pressure is placed downward on foot as the examiner rotates the lower leg both directions
        -the examiner distracts the lower leg by pulling up with the thigh stabilized and rotates again
        -a positive indicator is when there is pain on compression but not on distraction

Patellar Tests:
-Patellar Grind
        -indicates presence of degenerative condition, usually chondromalacia
        -can be very painful if not done right
        -use light pressure when performing test
-Patellar Apprehension
        -tests for patellar instability
        -patient will become apprehensive when patella is pushed laterally
        -positive is apprehension w/ or w/o pain
-Patellar Ballotment
        -used to determine if there is significant intra-articular swelling
        -with a hemoarthrosis, the blood and synovial fluid push the patella up like a boat in the water
        -positive indicator is a clicking feeling when pushing the patella directly down towards the trochlear
                groove of the femur

Prophylactic Braces:
        -braces can be custom-fitted or off-the-shelf
        -main factor is severity of injury and/or costs
        -ACL reconstructions usually require a brace for one year after surgery
        -a lateral knee hinge can be used prophylactively to reduce the amount of MCL injuries

INJURIES:
-MCL Sprains
        -typical MOI is a direct blow to the lateral knee
        -as with any ligament exam, immediate examination will give you the most accurate results
                    -if you wait too long, swelling will hinder the examination process
        -Grades 1-3, with 3 being the worst - total tearing of ligament
        -Grade 3 tears will sometimes present themselves with little or no pain a few minutes after initial injury
                    -this has to do with the extent of nerve damage
        -Grade 3 will also have some opening during valgus stress testing in 0 degrees
        -generally take longer to heal because of stresses placed upon them and poor blood supply
       
-LCL Sprains
        -not as common as MCL sprains
        -typical MOI is varus force with internal rotation of lower leg
        -when laxity is noted, always suspect avulsion fx of the fibular head
        -if laxity is noted in 0 degrees varus stress test, other structures are likely injured as well (ACL, PCL)
        -injury to the common peroneal nerve can result from injury to this structure
                   
-ACL Sprains
        -very common injury in sports
        -typical MOI is valgus stress w/external rotation of lower leg
        -usually results from non-contact rather than contact
        -injury can also occur in hyperextension
        -women are 3x more likely to tear their ACL
                    -factors include: wider hips, intercondylar notch size, ACL laxity, menstrual cycle hormones, to name a few
        -will usually hear an audible "pop"; sometimes people in a close proximity can also hear it
        -will develop hemarthrosis within a few hours
        -surgical reconstruction is required for continued participation in competitive sports

-PCL Sprains
        -3x as strong as ACL
        -not injured as often as ACL
        -most vulnerable in 90 degrees of knee flexion
                    -i.e. falling on knee, especially while wearing a knee brace
                    -very common injury in car wrecks because knees hit dashboard in bent position
        -will not always require surgery

-Meniscal Injuries
        -medial meniscus has higher rate of injury because of attachment to joint capsule
                    -the LCL is more mobile during movement, so it can "give" a little better
        -typical MOI is a twisting, rotational force while weight bearing
        -more injuries occur to the medial meniscus during knee flexion combined with internal rotation
        -swelling develops gradually over a couple of days as opposed to ACL
        -a meniscal tear will present with some of theses clinical s/s:
                    -popping, catching, locking, giving way episodes, pain on deep squatting, etc.
        -according to zones where injury occurs, tissue may be saved and eventually heal on its own
                    -damage in the innermost zone is bad because no blood supply is present and it will not heal on its own
                                -surgical removal will be required
        -the goal in surgery is to remove as little meniscus tissue as possible as this can lead to early degeneration

Hypertrophied Plica
        -plica is leftover folds from birth; they fail to be absorbed by the body; occurs naturally in small percentage of people
        -is often mistaken for meniscal injury
        -medial patellar plica is the most commonly symptomatic
        -s/s range from locking of the knee to catching feeling
                    -main difference between meniscal injury s/s is that there is little to no swelling as compared to meniscal swelling
        -popping is very common with this condition
        -if condition does not resolve, surgey is indicated - MRI will show size of plica

Osteochondral Knee Fx's
        -any injury to ligaments and meniscus can also shear off a piece of bone attached to cartilage
        -immediate swelling with significant pain
        -may show up on MRI, scope is usually done to see extent of damage
        -area must be somewhat repaired as best as possible
        -arthritic area will take longer to heal than other injuries
       
Osteochondritis Dissecans
        -can be from direct or indirect trauma
        -pieces of cartilage and subchondral bone separate from bone
        -occurs more frequently in medial femoral condyle
        -affects both youth and adults
        -common s/s are: chronic swelling and aching in joint after activity especially
        -"joint mice"

Joint Contusions
        -the knee is not well padded
        -bruise will affect joint capsule which hurts in any movement
        -will usually cause patient to limp
        -treat like other bruises

Peroneal Nerve Contusions
        -MOI is blow to lateral aspect of knee
        -numbness, paresthesia, tingling, radiating pain are all common s/s after injury
        -area should be protected by padding upon return to sport
        -return to play when asymptomatic

Bursitis
        -can be acute or chronic or recurrent
        -prepatellar bursitis usually results from a lot of kneeling
        -infrapatellar bursitis usually results from a lot of running
        -management consists of ice, compression, NSAID's
        -surgery may be indicated if steroid injection does not work

Patellar Fx
        -can be from direct or indirect forces
        -about 3% of population has a condition called, "bipartite patella," where the patella is in two halves
                            -this condition is normal and is often misdiagnosed as a patellar fx
       
Acute Patellar Dislocation/Subluxation
        -patella dislocates to the lateral side
        -predisposing factors include:
                -anything that increases the Q-angle including wide hips, genu valgum, etc.
                -weak VMO
                -tight lateral knee structures including the lateral retinaculum
        -patella is reduced by extending the knee and if needed, applying a medial force to patella
        -knee should be immobilized for about 4 weeks
        -strengthening the VMO is critical
       
Injury to Infrapatellar and Suprapatellar Fat Pad
        -caused by chronic or repetitive pressure or compression
        -infrapatellar is most commonly injured in sports
        -if irritation continues, the fat pad can become scarred and develop calcium deposits
        -the fat pad can become lodged between the patella and tibia

Chondromalacia
        -degeneration of articular cartilage on the undersurface of the patella
        -can be caused by abnormal patellar tracking, normal wear and tear, or significant trauma
        -s/s include: grating sensation when flexing/extending the knee
        -cut out deep knee bending or other stressful activities on the knee

Patellofemoral Stress Syndrome
        -occurs because of lateral deviation while tracking through trochlear groove
        -same factors as patellar dislocations/subluxations
        -s/s include: tenderness over lateral patella and lateral femoral condylar ridge, swelling, and a positive
                    patellar apprehension test with lateral force
        -affects females more than males; i.e., look at women's soccer and cross-country
        -McConnell tape job may be beneficial
        -strengthening of VMO is essential

Osgood-Schlatter's Disease
        -apophysitis condition where patellar tendon pulls away from insertion on tibial tuberosity in adolescents
        -causes excessive calcification at injury site (exostoses)
        -will have episodes where it will flare up for a a few days to a week and then subside

Larsen-Johansson Disease
        -apophysitis condition where patellar tendon pulls away from insertion on inferior pole of patella in adolescents
        -treated with anti-inflammatories, ice and rest, just like osgood-schlatter's
       
Patellar Tendonitis (Jumper's Knee or Runner's Knee - slang terms)
        -overuse injury where excessive forces are placed upon patellar tendon repeatedly
        -tendon will feel "mushy"
        -more susceptible to rupture
        -treated with ice, ultrasound, deep tendon friction massage, patellar strap & anti-inflammatories

Patellar Tendon Rupture
        -sudden contractions, explosive movements are typical MOI
        -tendonitis is usually present in tendon when it ruptures, this weakens the tendon
        -will not be able to extend knee at all
        -pain will be great at first with the pain usually subsiding
        -palpable mass in the distal thigh (patella)

Runner's Knee
        -catch all term given to some knee conditions that are prevalent amongst runners
        -also sometimes referred to as cyclist's knee
                -Iliotibial Band Friction Syndrome
                            -overuse condition affecting runners with genu varum and pronated feet
                            -this creates friction over lateral femoral condyle where the IT Band will become inflamed
                            -Ober's test will be positive for pain
                            -usually present with popping or snapping when they bend knee
                            -treated with anti-inflammatories, stretching lateral structures and wearing a thigh sleeve to help
                                     reduce pressure on IT Band
                -Pes Anserinius Tendonitis/Bursitis
                            -pes anserine refers to the point on the tibia where the sartorius, gracilis, and semitendinosus    
                                    muscles attach
                            -can result from excessive genu valgus and weak VMO
                            -can develop from running on a slope with one leg higher than the other (i.e., road, street)
                            -treatment consists of ice massage, anti-inflammatories, stretching, rest & orthotics

The Collapsing Knee
            -usually results from one of the following:
                        -weak quadriceps muscle
                        -ACL or PCL instabilities
                        -torn meniscus
                        -osteochondritis dissecans
                        -chondromalacia
                        -subluxating patella

Weight Bearing
        -should be attempted as early as possible
        -trend nowadays is to have early mobilization
       
Joint Mobilizations
        -early joint mobs are key to fast recovery
        -posterior femoral, posterior tibial and patellar glides are performed

Rehabilitation
        -Flexibility
                -gain most flexibility first before trying to incorporate strength training
                -stretch quads, hams, calves, hip flexors
        -Muscular Strength
                -help reduce the effects of atrophy by doing SLR's (straight-leg raises)
                -try to use more closed chain exercises rather than open chain (less stressful on knee)
                -closed chain examples:
                            -mini-squats, TKE's (terminal knee extensions), step-ups, wall slides
        -Neuromuscular Control
                -loss of neuromuscular control results from swelling and pain
                -use proprioceptive exercises such as:
                            -balance boards, BAPS board, slide board, trampoline
        -Bracing
                -depends on what is damaged and how bad...did it require surgery?
                -ACL reconstruction patients are usually fitted with a DonJoy Defiance knee brace (custom)

Functional Testing/Return to Play
-when they can perform specific sport skills with little or no pain, full ROM, and good strength as compared to unaffected leg
-i.e. - if WR in football, have him run his routes; also go through zig-zags, shuffling, fig. 8's, sprinting, hopping, etc.

Web Sites for further study/learning:
www.sportsdoc.umn.edu/Clinical_Folder/Knee_Folder/Knee_Exam/suprapatellar%20plica.htm

www.knee1.com/gotoindex.cfm - knee resource

www.sover.net/~sstryker/itbs.html - IT Band syndrome site

www.healthlink.mcw.edu/article/926052680/html - chondromalacia article

www.worldortho.com

www.medmedia.com/med.htm

www.ncl.ac.uk/~nccc/tutorials/knee - knee anatomy

www.arthroscopy.com/sp05000.htm - knee surgery info