SHOULDER IMPINGEMENT Dr Maher Assaf Sfhd.med.sa
WHAT IS IT?• Rotator cuff impingement syndrome is a clinical diagnosis that caused by mechanical impingement of the rotator cuff by its surrounding structures.• Patients with impingement syndromes may present with various signs and symptoms on physical examination depending on the degree of pathology and the structures involved.
CLINICAL FEATURESPain nocturnal + + overhead activities unaple to sleep on involved sidePainful arch (70 – 120)Impingement signs neer test hawkins test
Hawkins testHawkins test – “patient reports pain when the arm is flexed at 90° andpassively positioned in internal rotation” Hawkins Test - ThePainSource.com -YouTube.FLV
Neers test pain during passive arm elevation Neers Impingement Test -ThePainSource.com - YouTube.FLV
STATIC FACTORS activity pain haw neerOa of Ac joint Overhead+abd ac j - +Hooked acromion Over h lateral + +Ossificatin of Over h ant lateral + -coracoacromial ligOs acromiale Over h fibrous union + -Coracoid change add+internal anterior - -
DYNAMIC FACTORS act pain haw/neer• Weak muscles over h ant/pos + + ant laxity fatigue• Tight post throw post + - capsule• Glenoid abduction post - - ( internal ext rotation impingment) throwing
SUBACROMIAL IMPINGEMENTNeer proposed that 95% of rotator cuff tears are due to chronicimpingementbetween the humeral head and the coracoacromial arch.
SUBACROMIAL IMPINGEMENTStage 1 disease consists of edema and hemorrhage ofthe tendondue to occupational or athletic overuse, and is reversible underconservative treatment .
SUBACROMIAL IMPINGEMENTStage 2 disease shows progressive inflammatory changes of therotator cuff tendons and the subacromial-subdeltoid bursa, andcan be treated by removing the bursa and dividing thecoracoacromial ligament after failed conservative management.
SUBACROMIAL IMPINGEMENTStage 3 disease manifests as partial or complete tears of therotator cuff and secondary bony changes at the anterior acromion,the greater tuberosity or the acromioclavicular joint.
SUBACROMIAL IMPINGEMENT FACTORS• abnormal acromial shape or position;• subacromial enthesophytes;• os acromiale;• thickened coracoacromial ligament;• acromioclavicular joint undersurface osteophytes.
SUBACROMIAL IMPINGEMENT FACTORS acromial shape Ac joint subacromial osteophytes osteophytes thickened os acromialecoracoacromial lig
• Morrison and Bigliani described three types of• acromion based on dried cadaver specimens and• conventional outlet view radiographs.• Type 1 acromion has a flat undersurface and is• considered the physiologic shape.• Type 2 acromion has a curved undersurface.• Type 3 acromion has a hooked undersurface.
Both type 2 and 3 acromion are considered abnormalvariants that predispose individuals to impingement ofsupraspinatus beneath the acromion, and increase thelikelihood of developing rotator cuff tear.
SUBCORACOID IMPINGEMENTThe coracoid process may cause anterior impingementwhen the coracohumeral distance is decreased. This distance must be large enough to accommodate thearticular cartilage of the humerus, the subscapularistendon, the subscapularis bursa and the rotator intervaltissue, and portions of the insertions of thecoracoacromial ligament and the conjoint tendon.
SUBCORACOID IMPINGEMENTGerber’s study in normal subjects with conventional CT ofthe shoulder demonstrates average distance betweenmedially rotated humeral head (the lesser tuberosity) andthe coracoid tip is 8.6 mm.Forward flexion combined with medial rotation reducedthe coracohumeral distance to an average of 6.7 mm (30).A coracohumeral space of less than 6 mm wasconsidered diagnostic of subcoracoid stenosis.
SUBCORACOID IMPINGEMENT1. Idiopathic – anatomic abnormality of the coracoid process such aslongitudinally or laterally displaced coracoid process, or developmentalenlargement of the coracoid process.2. Iatrogenic – surgical procedures involving the coracoid process, such asbone block procedures for anterior instability ofthe shoulder, posterior glenoid neck osteotomies for posterior instability of theshoulder, and acromionectomies for rotator cuff tears.3. Traumatic – fractures of the lesser tuberosity or the coracoid process, andsubsequent malunion that leads to decreased subcoracoid space.4. space-occupying lesions in the subcoracoid space such as ganglions,calcifications, and amyloid deposits.
Most patients complain of pain and tenderness in the anterior aspect of theshoulder, which is exacerbated by various degrees of flexion, adduction, androtation.The pain is thought to be caused by impingement of the subscapularis tendonbetween the lesser tuberosity and coracoid process.MR axial and oblique sagittal images are used to evaluate the coracohumeralspace and subcoracoid impingement.Subscapularis tendon partial or full thickness tear and biceps tendon instabilityhas been reported in patients with clinical diagnosis of subcoracoidimpingement.
SECONDARY EXTRINSIC IMPINGMENTIn these patients the coracoacromial outlet is usually normal. Overhead-throwing athletes can develop glenohumeral joint instabilitysecondary to fatigue and overloading of the rotator cuff muscles caused bychronic microtrauma and weakening of the anterior capsule. This instability will cause abnormal superior translation of the humeral head andlead to dynamic narrowing of the coracoacromial outlet.Instability can also occur in the scapulothoracic joint, and cause abnormalscapular motion and result in dynaminc narrowing of the coracoacromial outlet.
MR images will showundersurface degenerationand partial tears of the rotatorcuff tendons.Labral abnormality is alsodescribed in patientswith secondary extrinsicimpingement.
POSTEROSUPERIOR GLENOID IMPINGEMENTPosterosuperior glenoid impingement syndrome was firstdescribed by Walch et al in athletes who participate inrecurrent overhead activities, such as throwing, tennisplaying, and swimming.During the late cocking phase of throwing motion, the armis maximally abducted and maximally externally rotated.This extreme ABER position will cause contact betweenthe undersurface fibers on the supraspinatus andinfraspinatus and posterosuperior glenoid rim.
This contact is commonly seen in asymptomaticindividuals and non-throwers during ABER;Repetitive impaction of these structures in competitiveathletes can lead to degeneration and tearing of thearticular surface fibers at the infraspinatus andsupraspinatus tendon junction with associateddegeneration and tearing of the posterosuperior glenoidlabrum.
The diagnosis of internal impingement can be made onphysical examination when abduction and externalrotation of the shoulder elicits posterosuperiorglenohumeral joint pain. Relocation test of Jobe can be done to further confirmthis diagnosis, when a posteriorly directed force to thehumeral head while shoulder in ABER position relievesthe pain.
MR image findings include partial-thickness undersurfacetearing of the posterior fibers of the supraspinatus and anteriorfibers of the infraspinatus tendons;Fraying and tearing of the posterosuperior glenoid labrum;Paralabral cyst formation;Cystic changes in the greater tuberosity of the humeral head
Some of these findings may simply represent normaladaptive changes from the repetitive motion, howeverthey are considered pathologic in symptomatic patients.MR imaging can also demonstrate the contact betweenthe rotator cuff tendons, the greater tuberosity, and theposterosuperior glenoid labrum when arm is placed inABER position.
ANTEROSUPERIOR GLENOID IMPINGEMENTImpingement of theundersurface of thereflective pulley system andof the subscapularis tendonagainst the anterosuperiorglenoid rim, when the arm isanteriorly elevated,horizontally adducted, andinternally rotated.
The shoulder pulley system iscomposed of coracohumeral ligament(CHL), the superior glenohumeralligament (SGHL ), and fibers of thespupraspinatus and subscapularistendon. the function of the pulley system is toprotect the long head of the bicepstendon against anterior shearingstress, and stabilize this tendon in itsintraarticular position.
Gerber and Sebesta proposed that in patients withanterosuperior impingement syndrome, repetitive andforceful anterior elevation, horizontal adduction andinternal rotation of the arm will cause impingement of thereflective pulley between the subscpularis tendon and theanterosuperior glenoid rim, and leads to frictionaldamages in these structures.
A torn reflective pulley, either secondary to trauma or degenerativeprocess, can cause instability of the long head of the biceps (LHB)in its intraarticular course, results in medial subluxation of LHB.
The medially subluxed LHB will lead to anterior translation andsuperior migration of the humeral head, which will causeanterosuperior impingement.
The combination of a partial articular-side subscapularisand supraspinatus tendon tear in addition to the pulleylesion increases the risk of the incidence of ASI; and gender are not influencing factors forAgethe development of the ASI.