Shoulder Flashcards
Position of scapula? (what plane and facing ant vs retro)
Anteverted 30° in frontal plane
Position of glenoid fossa? (what plane and facing ant vs retro)
Tipped superiorly in relation to scapula, retroverted in transverse plane (varies but <7°)
Dominant shoulders tend to have more humeral anteroversion or retroversion?
Retroversion
T/F: total rotation ROM of the GH joint is affected by retroversion of humerus?
False, total range is same. Excessive retroversion = increased ER, decreased IR
What is the balance stability angle?
Angle between the glenoid arc and center of the glenoid
What happens if forces from muscles around the joint are directed outside of the balance stability angle?
Joint can be unstable
Causes of excessive GH retroversion? What ° would be excessive?
Developmental abnormality, OA, secondary post-traumatic arthritis, inflammatory conditions
- >7° retroversion
Concentric wear of the glenoid
Symmetrical or even along glenoid, centration (CENTRAL)
aka “Type A”
Eccentric wear
Uneven wear of POSTERIOR glenoid, causing retroversion and post humeral head subluxation, can cause biconcave glenoid
aka “Type B”
Type C glenoid changes
Retroversion of more than 25°, regardless of erosion or location
What type of GH OA responds less to TSA surgery
eccentric deformities (negative impact with higher failure rate vs concentric)
Glenoid anteversion predisposes the shoulder to what type of instability
Anterior
Glenoid retroversion predisposes the shoulder to what type of instability
posterior, also leads to posterior labral tears
What angle of retroversion is correlated with poor outcomes to restore stability to GH joint?
> 15° retroversion angle
Which causes more instability: humeral retroversion vs glenoid changes?
Glenoid changes
Hill-Sach’s fracture
- Location
- Associated w/ what type of instability/dislocation
- Compression fx of posterior superior humeral head
- Common with anterior/inferior dislocations
What % of bone loss with humeral lesions (i.e. Hill-Sachs) should be addressed surgically?
20-25%
How to calculate true glenoid track width?
84% length - Glenoid defect width = track width
AC joint ligaments provide stability in which directions?
Ant/Post
Coraclavicular ligaments (2)
1) Conoid
2) Trapeziod
Coraclavicular ligaments prevent against which movements at the AC joint?
Sup/Inf
Amount of clavicular rotation with humeral elevation in scapular plane?
5-8° posteriorly
AC joint: Type I strain
AC: strained, partially torn
CC: none
AC joint: Type II strain
AC: Rupture
CC: Stretched but intact
AC joint: Type III strain
AC: Rupture
CC: Rupture
AC joint is what type?
Diarthrodial w/ fibrocartilaginous disc
The (congruency/incongruency) of the AC disc contributes to high rate of early degenerative changes?
Incongruency
SC joint: which direction of dislocation is more common?
Anterior
NOTE: post very dangerous
What structures (3) form a pulley that stabilizes the biceps tendon?
1) Superior GH ligament
2) Coracohumeral ligament
3) distal subscap tendon
Buford complex (GH capsule)
Congenital labrum variant where the anterior/superior labrum is absent from 1-3 “o-clock”
Middle GH ligament contributes the most to stability in what position?
Shoulder abducted to 45° and ER
Superior GH ligament contributes the most to stability in what position? Resists what?
Neutral rotation, 0° abd
Resists inferior
Bankart lesion
Avulsion of anterior band of INF GH lig
Which of the inferior GH ligaments has the highest tensile strength? Which direction does it stabilize?
Anterior band, resists anterior translation when shoulder is 90° abd and ER
What GH ligament is the main stabilizer against inferior GH jt translation
Inferior complex
2 categories of GH joint instability?
1) TUBS
2) AMBRI
What does TUBS stand for?
Traumatic
Unilateral
Bankart lesion
Surgery
What does AMBRI stand for?
Atraumatic
Multidirectional
Bilateral
Rehabilitation
Inferior capsular shift
Multidirectional instability is categorized by instability in how many directions?
At least 2
Posterior band of GH ligament stabilizes the shoulder when in what position?
Common injury in which sport/position
Flexion and IR
Football linemen (blocking)
Difference between Bankart vs bony bankart
Bankart: just ligament
Bony bankart: both lig and anterior glenoid
Reverse bankart
Lesion of post labrum and post INF GH ligament, can be bony
Depth of the glenoid is increased by what % due to labrum?
50%
What part of the labrum is more loosely attached (superior/anterior/posterior/inferior)
Superior
T/F: Dynamic stability of the labrum is controlled by the attachment of the long-head of the biceps tendon?
True
SLAP stands for?
Superior
Labrum
Anterior to Posterior
What population is at high risk for SLAP lesions?
Overhead throwing athletes (eccentric biceps activity)
Vascularization of the GH labrum
Historically poor, but found to be more dense in periphery (best in anterosuperior)
Does the GH labrum have nerve endings?
Yes, causing injuries to be painful, can contribute to proprioception
Rotator cuff interval
Located between supraspinatus and subscapularis, triangle shaped in anterior shoulder
Rotator cable
Semicircular thickening of the GH joint capsule. It travels between tubercles of the humerus and interweaves with the supra- and infraspinatus muscle tendons. The rotator cable anchors these tendons to the tubercles, playing the role of a suspension bridge
What part of the supraspinatus is the stiffest?
Bursal side and higher ant vs post
Rotator cresent
Located between rotator cable and insertions on the greater tuberosity
Vascularization of rotator crescent?
Avascular, but noted to be greater on bursal side of the tendon
Which is stronger - rotator cable vs crescent?
Cable is 2.59 thicker
NOTE: cable is better to stress shield with age
Cable vs crescent dominant in young and old?
Young: crescent dominant
Old: cable dominant
What is a force couple?
2 forces directed in opposite directions that cause rotation in a specific direction
Subscapularis is in a force couple with which muscle on the scapula?
Infraspinatus
Rotator cuff (collectively) is in a force couple with which muscle around the GH jt?
Deltoids and pecs
What position of the shoulder does the long-head of the bicep provide stability in?
Abd and ER
What are intrinsic factors of rotator cuff pathology?
Alterations in biology, hypercholesterolemia, family hx of RTC tears
Neer proposed that what % of RTC tears were caused by impingment?
95%
Which has better outcomes: surgical subacromial impingement decompression vs non-operative tx?
Neither, they have the same outcomes
T/F: Combined removal of the acromion and bursectomy was more beneficial vs bursectomy alone?
False, no difference
What angle of elevation/flexion does the smallest distance between the acromion and supraspinatus occur?
30-70° elevation
Neers sign may be indicative of which type of impingement?
Internal
Painful Arc test is in which ° range?
60°-120° of abduction
Posterior internal impingement is commonly found in what population?
Throwing athletes (late cocking phase)
What is the primary intrinsic factor for RTC pathoanatomy?
Age (vascularity is significantly decreased after age 40)
What 2 systemic conditions put a person a higher risk for developing tendinopathy?
Hypercholesteremia and diabetes
Does smoking affect tendon healing? If so, how?
Yes, it inhibits delivery of O2
Do genetics contribute to risk for RTC pathology?
Yes, small role
What is the most common partial thickness tear of the rotator cuff? (intra-tendinous, bursal-sided, articular-sided)
Intra-tendinous
Degenerative tears in the RTC tend to initially occur where?
Within the RTC crescent and the juction between the supra and infraspinatus
What happens to shoulder function with tears inside the crescent?
Well maintained as long as there is no disruption in the rotator cable
T/F: rotator cuff atrophy has no impact in outcomes post-repair?
False, RTC atrophy has been correlated to higher post-op re-tear rates
How soon after RTC tear (not operated on yet) can you see cartilage damage?
12 weeks
6 Muscles responsible for stabilization of the scapulothoracic joint
1) Trapezius
2) Romboid major
3) Romboid minor
4) SA
5) LS
6) Pectoralis minor
Scapulohumeral rhythm is defined as what ratio?
2:1 ratio - 60° scap upward rotation and 120° GH jt movement
What shoulder force couple is responsible for posterior scapula tilting?
Lower trap and SA
What muscle is the primary upward rotator and protractor of the shoulder girdle?
Serratus Anterior
What muscle is the primary stabilizer of the scapula?
Trapezius
Scapular muscle imbalance/altered motor control is believed to contribute to dyskinesis in what 2 ways?
1) Excessive UT activation
2) Decreased/delayed activation of lower/middle traps and SA
Innervation of SA muscle?
Long thoracic nerve
Innervation of the traps and SCM?
Spinal accessory nerve XI
Common presentation of damage to the spinal accessory nerve (CN XI)
Asymmetric neckline (depressed), a drooping shoulder, protraction and winging of the scapula, and weakness of forward elevation
Cervical lymph node removal or radical dis’c dissection due to cancerous tumors can cause damage to which nerve responsible for scapular motion?
Spinal accessory nerve (CN XI)
What are the factors of pain behavior?
- Aggravating/alleviating factors
- 24hr pattern
- Pain severity and irritability
- Chronicity
Hypothesized pathoanatomic diagnosis:
- Persistent pain in ant/lat shoulder
- Inability to sleep d/t pain
- Gradual loss of ROM
- Female
- Age 40-65 y/o
- Presence of diabetes or hypothyroidism
Adhesive capsulitis - primary
Hypothesized pathoanatomic diagnosis:
- Gradual onset pain
- Decreased ROM
- Age 60+
- Crepitus/catching w/ end ranges
- AM stiffness
GH OA
Hypothesized pathoanatomic diagnosis:
- Ant/lat shoulder pain
- Pain w/ overhead activity
- Painful arc
- Pain at night
Subacromial pain syndrome
Hypothesized pathoanatomic diagnosis:
- Ant/lat shoulder pain
- Loss of strength
- Pain worst at night
- Age 40+
RTC tear
Hypothesized pathoanatomic diagnosis:
- Anterior shoulder pain
- apprehension
- pain in end-range abd/ER
- Hx ant/inf trauama
- Recurrent sublux/dislocaations
- Jt clicking/clunking
- Jt locking
- “dead arm syndrome”
Anterior instability/labral tear
Hypothesized pathoanatomic diagnosis:
- Instability
- Apprehension
- Pain in flex/horiz add w/ post force through humerus
- Hx of trauma w/ or w/o dislocation
Posterior instability
Hypothesized pathoanatomic diagnosis:
- Deep anterior pain
- Clicking/clunking/jt locking
- Pain w/ throwing or bicep loading
SLAP lesion
Hypothesized pathoanatomic diagnosis:
- Post pain during abd/ER (especially w/ hyperabduction)
- Overhead athletes
Posterior internal impingement
Hypothesized pathoanatomic diagnosis:
- Anterior pain
- Bicipital groove w/ shoulder flex and supination
Long head of the biceps tendinopathy
Hypothesized pathoanatomic diagnosis:
- Superior pain increases w/ end-range elevation and/or horiz add
- Hx heavy weightlifting
- Hx trauma (especially inf force through shoulder girdle)
AC joint arthropathy/injury
What is SINSS model?
Severity, Irritability, Nature, Stage and Stability (SINSS) model for pain
Characteristics of HIGH pain irritability:
- ≥7/10 pain
- Constant night or rest pain
- High disability level
- Pain limits ROM (AROM > PROM)
Characteristics of MODERATE pain irritability:
- 4-6/10 pain
- Intermittent at night and rest
- Moderate disability
- Little discrepancy between PROM and AROM
- Pain primarily @ end-range
Characteristics of MILD pain irritability:
- ≤3/10 pain
- No resting or night pain
- Minimal pain @end-range
- AROM = PROM
Polymyalgia Rheumatica
An inflammatory disorder causing muscle pain and stiffness around the shoulders and hips & almost flu-like symptoms
- Common in 60+ y/o
Parsonage-Turner syndrome (PTS)
- Neuro disorder characterized by rapid onset of severe pain in the shoulder and arm. - This acute phase may last for a few hours to a few weeks and is followed by wasting and weakness of the muscles (amyotrophy) in the affected areas.
Validated standardized screening tool to identify medical red flags
OSPRO-Review of systems tool
T/F: Delayed surgical repair in the presence of an acute rotator cuff tear negatively impacts patient outcomes
True
How can chronicity of RTC tear be determined?
MRI
- Muscle atrophy
- Fat infiltration
What is the first choice imaging for shoulder pain (traumatic)?
XR/radiographs
- 2-3 views