Download Advanced Biomechanics Final Notes 10-14

Advanced Biomechanics Final Notes
10-14-10
The Shoulder:
Patient History:
 Patient age:
- Cuff degeneration 40-60
- Calcium deposit 20-40
- Frozen shoulder 45-60
 How they support arm:
- Support- AC separation, fracture
- Arm hanging- dislocation, burner/stinger
 Mechanism:
- FOOSH: dislocation, fracture, labral tear, rotator cuff tear
- Fall on tip of shoulder: AC separation
 Movements that cause pain or problems:
- Anterior instability: excessive abduction and lateral rotation leading to dead arm syndrome
in which patient feels sudden paralyzing pain and weakness
- Anterior instability: pain during late cocking and acceleration phases of throwing or
explosive overhead movement
- Rotator cuff tear: night pain resting pain, plus abduction (differentiate from cervical disc by
ROM and Bakody and reverse Bakody presentation)
- Tendinitis: activity related pain
o Muscular related problems graded by muscle strength
o Pain with no weakness indicates tendinitis
o Pain with some weakness is partial thickness tear
o Pain with severe weakness is full thickness tear (sometimes have less pain with full
thickness tear because of loss of stretch receptors)
- AC pain: full abduction or full horizontal abduction localized to the AC joint
Scapulothoracic elevation/depression:
 Scapular elevation occurs as a composite of SC and AC joint rotations
 Downward rotation of the scapula at the AC joint allows the scapula to remain nearly vertical
throughout the elevation
 Additional adjustments at the AC joint help to keep the scapula flush with the thoracics
Scapulothoracic protraction/retraction:
 Due to motion of AC and SC joint (mostly from SC joint)
Scapulothoracic upward/downward rotation:
 Upward rotators:
- Primary: serratus (does the most), lower fibers of trap, upper fibers of trap (at end range)
 Downward rotators:
- Posterior cuff muscles, lat, rhomboids
Internal/external GH rotation:
 With external rotation have activation of posterior cuff and roll and slide motion anteriorly of
GH (rolls posterior but head of humerus translates anterior)
 Inferior GH ligament becomes engaged at 90 degrees or above (thickening in both anterior and
posterior parts termed bands)
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Anterior band is primary passive restraint to anterior humeral movement during external
rotation
- During internal rotation posterior movement is restricted by posterior band
 Coracohumeral ligament and superior glenohumeral ligament (0-45)
 45-60 degrees is middle glenohumeral ligament
GH Abduction:
 Humerus slides inferiorly providing space under acromion preventing impingement
 Roll and slide needed to prevent impingement syndrome
 Without inferior glide takes only 22 degrees of movement before you start to impinge
 Should have 1 cm space
Advanced Biomechanics Final Notes
10-21-10
Shoulder:
Scapulohumeral Rhythm:
 When arm abducts scap should rotate upwards bringing glenoid under humerus
- If this doesn’t happen have eccentric overload leading to cuff tear
Basic Mechanical Characteristics of Normal Function:
 Stiffness (mobility)
 Stability
 Strength
 Smoothness
Postural Stiffness/Muscle Imbalance
 Due to dominant pecs
AC joint OA
 If there is asymmetric bump on 1 side look for a history of trauma which is fairly common
 X-ray: Zanka view (AP with 15 degree cephalad tube tilt)
 O’Brien test: have patient reach across midline and compress the joint
AC Separation:
 The joint space widens with hyperabduction and hyperextension exercises such as in weight
lifting which can lead to destruction
 Position of antalgia- holding arm across belly
 This tends to be chronic condition 3-6 weeks
Coracoacromial Ligament:
 Transcapular 4 view on x-ray allows you to look for impingement
Impingement:
 Secondary or Functional: can x-ray and the joint space will look normal but will still have
changes in function
 Internal impingement (instability)- overhead athlete, will have pain in back of the shoulder
Internal Impingement:
 Apley’s scratch test- quick test for internal rotation; check for anterior instability
Impingement Tests:
 Hawkins- arm at 90 degrees, 15 degrees adducted, internally rotate
 Neer- abduct arm
 Reverse impingement- inferior shear with abduction
 Muscle assistance (Kibler/functional)- patient abducts and they don’t have upward rotation of
the scapula; doctor assists with upward movement of the scapula, if the pain is relieved they
have a functional impingement
Partial Tears:
 Can be more painful than full thickness
Rotator Cuff Tests:
 Abrasion Sign: 90 degrees, passive internal and external rotation
 Lift off test- more for subscapularis
Biceps Labral Complex:
 Bankart- inferior anterior dislocation, pulling off of labrum
SLAP tear:
 Bicep and labrum tear
 Won’t be tested on the 7 different varieties
Atraumatic Instability:
 More generalized pain, not easy to localize, dully ache
MDI Diagnosis:
 Sulcus sign greater than 1 cm is significant
Instability Testing:
 Should have greater movement with posterior shear of the joint compared to anterior
 Relocation test: push head of humerus posterior; from the position of posterior apprehension
test and ask patient if it feels better
SLAP tests:
 Andrews supine SLAP- significantly reliable test for SLAP injury
Advanced Biomechanics Final Notes
11-4-10
Shoulder/scapula:
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Because pec minor inserts into coracoid when its tight it pulls the scapula forward resulting in
inferior border winging
 Throwers with shoulder problems at risk for ulnar collateral ligament injury
 Depressed scapula- trap is eccentrically lengthened; common in recreational weight lifter;
prominent AC joint
 Overloading of bicep mechanism leads to SLAP tears (common in recreational weight lifter doing
rows that does not engage the back muscles)
 Error with Bruegger posture is that they extend with the lumbar spine instead of holding the rib
cage down and then uprighting and putting extension in the T/S (diaphragm keeps the rib cage
down)
Serratus Anterior screens:
 4 point rock, T4 extension, posterior capsule stretch
Hip Mechanics:
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Patient can still walk with a hip fracture
Gluts are most important stabilizer for hips
Deconditioning can be blamed for hip fractures later in life
Treat the patient in their 30s and 40s with weak gluts and tight iliopsoas
Coxa vara- high risk for shear forces and fracture at the neck
Coxa valga- high risk for degeneration at the hip
Advanced Biomechanics Final Notes
11-18-10
Knee:
 Ortho tests: Lachmans, anterior drawer, pivot shift (see http://sportsdoc.umn.edu)
- Lachmans most sensitive
 Partial ligament disruption will have a soft end feel upon joint play
 ACL- 40-50% of knee injuries
 Not every person with an ACL tear will be positive on pivot shift test
- Poor sensitivity
- However every patient who has a positive pivot shift test will have an ACL tear
 Anterior drawer- disadvantage is that if you don’t test during the first 48 hours the hamstring
will become hypertonic and block some of the anterior translation
 When there is evidence of meniscal tear this is highly linked to OA of the knee
 Older patients who are less active do better with conservative non-operative treatment
 Hamstring will tighten to compensate for ACL injury- do not try to stretch or lengthen hamstring
if patient is ACL deficient (this is body’s natural compensation pattern to provide stability to the
knee)
 Operative treatment: in an effort to maintain range of motion and decrease swelling try to have
patient weight bearing even before the operation
- Need to strengthen quads- perform terminal extension strengthening injuries
 Females at higher risk of ACL injury:
- Females ACL is half the diameter of the male, femoral notch is narrower (cuts through the
ACL), hormonal factors, shorter and broader pelvis creates larger valgus Q angle,
functionally women are generally quad dominant (lack of balance between quad strength
and hamstring strength), generally when women land from a jump they have poor form (too
much knee extension or land in valgus position)
 Sportsmetric program- has shown decrease in ACL injury
 PCL injury- far less common (only about 3% of knee injuries)
- This is a far more difficult reconstruction surgery
- Trauma related (dashboard injury) vs. ACL injury which is more often sports related
- Isolated PCL injury may not require surgery
- If damage additional structures and lateral ligaments need surgery
- Can occur with hyperflexion
 Posterior drawer is good for PCL
 Quad active test- when the quads engage they cause anterior translation (in a stable knee there
should not be anterior translation)
 Varus or valgus at 0 degrees you will be testing more of the cruciates than the collaterals
 Perform varus at 30 degrees to check for posterolateral corner injuries (favor external rotation)
and put finger in the joint line to monitor the amount of gapping
 Dial test- 5 degree difference is clinically significant (compare involved side to uninvolved side)
 Medial collateral ligament- most commonly torn when knee is in flexion
- Middle 1/3 is the first thing to tear
- Goes hand in hand with medial meniscus tear and ACL
- 1st structure to fail with abduction load
- If all that is injured is the MCL then it is probably better not to get surgery
- Bracing may be helpful for athlete that wants to stay active
 Lateral collateral ligament- associated with PCL tear, not injured as often
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- Occurs with varus loading
Meniscal injuries:
- Incidence of acute meniscal tears is 60-70 per 100,000
- More common in men (2.5-4:1)
- Vertical bucket handle tears of periphery more frequently
- Patients older than 30 , degenerative tears more common
- 76% of asymptomatic patients with an average age of 65 years were noted to have tears of
either the medial or lateral meniscus by MRI
- Squat can tell you a lot of information
o Pain during ascent or descent is usually retropatellar or patellofemoral pain
o Pain at the bottom of the squat is usually indicative of meniscal injury
o Posterior horn injury is aggravated by flexion
o Extension load injury is anterior horn
- Most sensitive physical exam test is joint line palpation
- McMurrays is most specific test
- Steinmann’s- pt supine, palpate area that hurts, flex knee bring towards chest and then
extend- ask patient if pain is changing or moving (if pain stays the same regardless of
position then it is probably collateral or capsular injury, if pain changes or moves then it is
probably meniscus)
- Varus and valgus can be more sensitive in discriminating between medial meniscus and
medial collateral ligament
- Meniscus doesn’t like compression
- Collateral ligament doesn’t like tension
- Apleys compression- heel points toward meniscus that is being challenged
- External rotation- challenges medial meniscus
- Internal rotation- challenges lateral meniscus
- Heel to buttock test- if there is asymmetry from right to left that is obvious sign of
mechanical failure (very often a meniscal injury)
- Bucket handle tear more common in under 30
- Make sure you know McMurray test (see slides); you will be tested on this
- Most people heal without surgery
- Soft tissue work is helpful
Chondral injury
- Increased obesity increases risk
- Acute level- direct blow, can have hemarthrosis
- Intermittent swelling is most common symptom
- Degenerated knee will have genu varus
- Will see joint enlargement
- Glucosamine sulfate attracts water molecules, shows benefits in treatment of OA
One of the most failed knee surgeries is a lateral release surgery for ITB or patellofemoral issues
Anterior knee variants:
- Chondromalacia patella
- Osgood Schlatter- avulsion fracture because bone is growing too fast for length of muscles
and tendons
o More prevalent in males
o Knee squatters
o Poor functioning glutes
- Patellar tendon rupture
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- Patellofemoral tracking
- Screen out the rectus femoris- absolutely crucial, often short in athletes
Tri-Planar Glute- activates the glutes and is joint sparing
- Also a good way to get at stretch in the groin
Good way to work pelvic floor muscles is deep squatting
Single leg squat (assessment)
- 1 inch squat
- Shows G med insufficiency
Knee adjustment will very rarely hurt the patient however have to ask yourself if it will really
help
Orthotics- pronation is a good thing for the knee
- Don’t just randomly throw orthotics in shoes, might fix one problem but cause another
- Another issue is that the orthotics are too hard
- Don’t want them too flimsy either
Glut med controls valgosity of the knee
Gait eval- want the knee to travel in a sagittal plane, patella should point straight towards you
- Inward movement of the knee cap driven by structural position of the hip, antiverted hip
position
End stage OA presents with severe genu varus position on one side
Wear out our joints through internal forces (improper usage of muscles around the joint and
joint subluxations or fixations)
Genu valgum common in middle aged females, have to have some valgosity to walk
Tightness in anterior sagittal plane of the hip causes excessive movement in the coronal plane
(tight psoas or hip flexors)
- Watch the butt crack to see how it moves or wiggles
Should be able to get 80 degrees of hip flexion with an SLR
ART and Graston should be done when you find adhesions in the muscles, not just when patient
is in pain
External rotation of the tibia accompanies hip antiversion
Advanced Biomechanics Final Notes
12-2-10
Foot:
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2nd digit is longer than great toe, designed for toe off
Our foot was not designed for manmade surfaces and shoes
- Foot is designed to be walking on the terrain
- 3rd world countries have fewer complaints of foot problems
Orthotics- when patient comes in with orthotics, take them out of the shoe and have the patient
stand on them to determine if they are actually doing anything
- Patient must be in a neutral shoe if you are going to put in an orthotic
- Nike Pegasus or Vomero are examples of neutral shoes
- Men’s dress shoes- Merill, Clark, Echo
- Female’s dress shoes- Clark, avoid stiletto
Normal bend in the tibia should be 1-2 degrees
- Tibia varum- can be due to genetics; patient looks bow-legged but on closer examination
tibia is banana shaped; stiff mid foot, hyper-mobile talus; orthotics for the mid-foot
Tibia will follow the talus
- No muscles insert into the talus
- When have over pronated mid foot and rear foot it is more difficult to get them better
Static evaluation:
- Callus formation
- Hallux abducto-valgus/bunion
o Bunionectomy is most failed orthopedic surgery
- Haglunds deformity
- Hammer/claw toes- center of gravity is too far forward
- Tibia should be relatively straight (+ or – 2 deg)
- Legs should be approximately same length (<3-5mm)
o Structural or functional
o Do a scanogram to determine if it is structural
- Take a peek at shoe and look for big asymmetric findings
- Autonomic overload? (cold, sweaty)
Joints of the Rearfoot:
- Talo-Crural/Ankle Mortise
- Sub-Talar Joint
Talar Dome fracture:
- Only gets picked up with MRI
- If patient sprains ankle and isn’t getting better send out for MRI to see if have talar dome
fracture
Calcaneal eversion allows talar movement which drives internal tibial rotation which drives
femoral internal rotation activating the glutes
- Lack of calcaneal eversion and restricted talar movement can lead to meniscal grinding as a
compensation
Sub-talar joint
- Located between the talus and calcaneus
- 1-2 separate articulations
- Shock absorption
- Torque converter
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Big issue: determine if there is a lack of eversion
Person with too much eversion- won’t be able to adjust inversion into that foot, treat by
building the muscles
Mid-tarsal joint (little ankle):
- Between the cuboid and calcaneus & cuboid and navicular
Peroneus longus-creates plantar flexion of the first metatarsal (this is the key function that the
overly pronated foot can’t do)
- Peroneus longs is sloppy and loose in overly pronated foot (have overactive peronei
muscles)
- Have to have plantar flexion in order to get dorsiflexion
- Great toe dorisflexion/1st metatarsal plantar flexion
- Functional hallucis limitus- Orthotic to treat restricted plantar flexion is Morton’s extension
or rocker bottom shoes
1st Ray mobilization- 1st metatarsal PF/hallux DF
Pronation and supination- memorize charts
Pronated foot- difficulty with toe off during the gait cycle
Supinated foot
- Thudding noise during gait
- Decreased fat pad
Four Phases of Gait
- Heel strike
- Mid-stance (transformation)
- Toe-off (propulsion)
- Swing phase
Heel Strike
- Hip is flexed to 30 deg
- Knee is almost fully extended
- Ankle slightly dorsiflexed
- Subtalar joint slightly supinated
- Calcaneus is inverted a couple deg
Gait shock absorbers
- Three distinct actions of the bipedal allow for shock absorption:
o Pronation/DF
o Knee flexion
o SIJ movement
- All movements can occur excessively (too much of a good thing)
No muscle provides calcaneal eversion (done by gravity)
If unable to pronate enough compensation must occur elsewhere (transverse tarsal joint, knee,
hip)
Can’t unlock mid-foot after heel-strike so loose bag of bones doesn’t occur for terrain adaption
Tibialis posterior- biggest function is to control eversion
Eversion:
- Controlled valgosity of the front knee is a necessary loading mechanism
- This is a natural loading mechanism, as you see the forefoot abduction to drive
pronation/eversion/loading
3 ways to assess eversion:
- Gait
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- Functional testing (step downs)
- Motion palpation
Metatarsal bump- used to treat Morton’s neuroma
Criteria for orthotic:
- Uncontrolled pronation
o Can control internal tibia rotation
- FHL
- Tibial torsions and varums
o Often produce cavus looking feet and inverted calcaneus, but hypermobile sub-talar
joint, very stiff mid-foot
- Forefoot varus
- There are no carved in stone rules but this is a foundation
Tibial Structural Issues
- Tibial varum:
o How much bending there is in the frontal plane
o Steeper approach which requires the foot to pronate through an excessive ROM
o Cavus foot- but often hypermobile sub-talar
- Tibial torsions
o How much twist is in the tibia as we develop
o This is an ongoing process as we grow, which means huge sight for compensation
o Measure transmalleolar angle or passively flex and extend the knee keeping the
knee in sag plane and look for foot deviation