Clinical notes - Minor shoulder instabilities

Chronic m inorshould er instabilities are com m only found w ith high-velocity acti­ vities such as throw ing and the tennis serve, and in sw im m ing. It refers to chronic m icro-trau m a involv ing the stabilising m echanism s of the g lenohum eral joint, leading to subluxa tion of the hum eral head during sporting activity. It has also been described as occult instability , occult re­ curring glenohum eral subluxa tion or func­ tional instability. Signs and sym ptom s are often vague and p resent w ith an im pingem ent-like condition w hich seem s to be resistant to therapy. Diagnosis and the treatm ent of this condition therefore offers a great chal­ lenge to the therapist! This condition m ay result from • Disorder o f the passive stabilisers o f the joint, eg hyper-elasticity of the capsule, labral tears. • Loss of functional stability of the joint, due to w eakness, loss of endurance or lack o f coordination o f the m uscles of the shoulder girdle. To appreciate the presentation and ap­ proach to treatm ent o f this condition, the biom echanics and m uscle firing pattern of throw ing m ust be understood, in order that the principles can be applied to other sporting activities, such as the tennis serve and sw im m ing. Throw ing can be divided into four stages: 1. W ind-up, w hich consists o f shoulder flexion; 2. Cocking, w ith abduction, follow ed by horizontal extension and full lateral ro­ tation; 3. A cceleration until the ball leaves the hand; 4. Follow -through w ith forw ard flexion and m edial rotation o f the shoulder. W ind-up: The rotator cuff contracts to stabilise the head in the glenoid. Supraspinatus is m ost active betw een 80 and 110° of ab d u ctio n , w h erea s in fra sp in a tu s and teres m inor activity increase steadily to­ w ards full elevation. It is this contraction that is m ost im portant for centralisation of the h ead . T o e le v a te an d a b d u ct the shoulder, the scapula m ust rotate laterally and elevate. Scapular rotation requires a "fo rce cou p le" com posed of the upper trapezius, low er trapezius, levator scapu­ lae and serratus anterior. W ithout this sta­ bilisation about the ST joint, the glenoid w ill lose its optim al upw ard directed posi­ tion, p red isp o sin g to su b acro m ial im ­ pingem ent. The effective w eight o f the upper limb w ill increase, placing abnorm al stresses on the rotator cuff. This w ill lead to w eakness and fatigue of the supraspinatus, w ith further loss of stabilisation. Full trunk extension/rotation and pelvic rotation contribute to the stage of wind-up. C ocking consisting of horizontal exten­ sion (30°) and lateral rotation (160-180°). Throughout this stage the rotator cuff cen­ tralises the head. Full external rotation is achieved by the posterior deltoid and the lateral rotators, w hile the m iddle trapezius and the rhom boids adduct the scapula. Serratus anterior stabilises the scapula against the thoracic wall. Eccentric con­ tractions of the subscapularis decelerates the m o v em en t, w h ile teres m ajor, latissim us dorsi, and pectoralis m ajor con­ trol the last degrees of lateral rotation and prevent excessive anterior translation of the hum erus in the glenoid. Coordination and correct activation o f these m uscles therefore is im portant to m inim ise over­ strain on the anterior part o f the joint. A cceleration : Pectoralis m ajor, subsca­ pularis, latissim us dorsi and teres m ajor a c t c o n ce n tr ic a lly as m ed ia l ro ta to rs . Low er and upper trapezius and serratus anterior contract concentrically to hold the scapula rotated and to m ove it laterally. Follow -through co n sis ts of. forw ard flexion and m edial rotation of the shoulder jo int. Eccentric activity in posterior deltoid, su p rasp in atu s, in frasp in atu s and teres m inor control the m edial rotation. Eccen­ tric contractions o f the middle trapezius, rh o m b o id s , p e c to ra lis m a jo r an d la-1 tissim us dorsi provide the decelerating force. W ith instability there appears to be a com pensatory increase in activity o f the b icep s and the sup rasp inatu s m uscles. D im inished activity o f serratus anterior oc.curs, w hich dim inishes protraction o f the shoulder, therefore placing m ore stress on the anterior restraints. D im inished levels o f activity of pectoralis m ajor, subscapu­ laris, latissim us dorsi and o f infraspinatus has also b een found. T h is im b alan ce, w hether it is part of the prim ary pathologi­ cal process or secondary to it, adds to the anterior instability and m ust be addressed specifically during rehabilitation. Clinical presentation: • Pain w ith overhead activ ities, either d u rin g la te cock in g / acceleratio n or during follow -through. They are often vague and difficult to localise to any specific position of the joint. • Com plaint o f w eakness, especially in the position of late cocking. D ifference betw een m inor instability and im pinge­ m en t sy n d ro m e are th ere fo re v ery subtle. • A pprehension associated w ith certain m ovem ent, but frequently unable to tell w hether this is true apprehension or anticipation of pain. • Painful catches, painful intra-articular clicking or "d ead arm " syndrom e may be present in the late cocking phase. • The history seldom reveals a specific injury, but m oving pain sites in various seasons of play, w hich have been resis­ tant to therapy. On examination: • The patient m ay present w ith full or excessive range of physiological m ove­ m ents, w ith pain at lim it, particularly abduction and lateral rotation or hori­ zontal flexion and m edial rotation. Lat­ eral rotation m ay be lim ited by spasm , especially in abduction, or m ay be ex­ cessive. • Endfeel is often loose, less of a ligam en­ tous tightening. • R esisted co n tra ctio n o f ro ta to r cu ff m uscles are painfree. • Stability tests m ay be negative. • D ifferentiation betw een lesions of the subacrom ial stru ctu res and o f insta­ b ility can be d eterm ined b y adding com pression or d istraction to full elev­ ation, as described by M aitland. • Loss of proprioception, as w ith any in­ jury of a joint. • M uscle strength: A com m on m istake is to test strength only. M uscle control and endurance are functionally m ore im ­ portant. On assessm en t of m uscular c o n tro l a n o rm a l s c a p u lo h u m e r a l rhythm m ay be evident on active elev­ ation and abduction. H ow ever, after repetition o f m ovem ent, or elevation under a load, uncontrolled scapular patterns m ay be revealed. This m ay be m ore evident during low ering w hen the scapular stabilisers function eccentri­ cally. Careful repetition and analysis of the sporting activity m ay be necessary to reproduce the sym p tom s and m uscu­ lar control should be assessed in various functional positions. Rehabilitation: The goal o f rehabilitation is to return the individual to pre-in jury status, nam ely full m ovem ent, strength, endurance, coordina­ tion and speed. Principles of treatment: • Inflam m ation and pain m ust be treated locally. • Re-educate synchrony of m ovem ent. It is im portant not to start strengthening exercises until synchrony of m otion of the shoulder girdle com plex through a norm al range have been achieved! The first aim is to im prove the static stability o f the scapula, for exam ples during co­ contraction exercises o f the rotator cuff, PN F patterns of the scapula, and seated pushup. M iddle fibres of trapezius are exercised in the prone position, initially w ith lim ited lateral rotation. Streng­ thening for the serratus anterior is very im portant for reasons m entioned ear-

C h ronic m in o rsh o u ld e r instabilities are com m o n ly found w ith h igh -velocity acti v ities su ch as th ro w in g and the tennis serve, and in sw im m ing. It refers to chronic m ic ro -tra u m a in v o lv in g the sta b ilisin g m ech an ism s o f the g len o h u m eral jo in t, leading to subluxa tion o f the hu m eral head d uring sp ortin g activity. It has also been described as o ccu lt instability , o ccu lt re curring glen o h u m eral subluxa tion o r fun c tional instability.
Signs and sym p tom s are often vagu e and p re se n t w ith an im p in g em e n t-lik e con d ition w h ich seem s to be resistant to therapy. D iagnosis and the treatm en t of this con d ition therefore o ffers a great ch al lenge to the therapist! To ap preciate the p resen tation and ap proach to treatm en t o f this con d ition, the biom ech an ics and m u scle firing pattern of throw ing m u st be u n d erstood , in ord er that the p rinciples can b e ap p lied to other sportin g activities, such as the tennis serve and sw im m ing. T h row in g can be divided into four stages: 1. W ind -up, w h ich con sists o f shoulder flexion; 2. C o cking , w ith abd u ction , follow ed by horizontal exten sion and full lateral ro tation; 3. A cceleratio n until the ball leaves the han d; 4. F o llow -th rou g h w ith forw ard flexion and m ed ial rotation o f the shoulder. W in d -u p : The rotator cu ff con tracts to stabilise the h ead in the glenoid. Supraspinatu s is m ost activ e b etw een 80 and 110° of a b d u c tio n , w h e r e a s in fra s p in a tu s and teres m in or activ ity increase stead ily to w ard s full elev ation. It is this con traction that is m ost im p o rtan t for cen tralisation of th e h e a d . T o e le v a te a n d a b d u c t the shoulder, the scapu la m u st rotate laterally and elevate. Scap u lar rotation requ ires a "fo rc e c o u p le " com p o sed of the u p p er trapezius, low er trapezius, levator scap u lae and serratu s anterior. W ith o u t this sta bilisation abou t the ST jo in t, the glenoid w ill lose its op tim al up w ard directed posi tion , p re d isp o s in g to s u b a c ro m ia l im p in g em en t. T he effectiv e w e ig h t o f the upper lim b w ill increase, p lacing abnorm al stresses on the rotator cuff. This w ill lead to w eakn ess and fatigu e o f the supraspi-natus, w ith further loss of stabilisation. Full trunk exten sion / ro tatio n and pelvic rotation con tribu te to the stage o f w ind-up.
C o c k in g con sisting o f horizontal exten sion (30°) and lateral rotation (160-180°). T hro u gh ou t this stage the rotator cu ff cen tralises the head. Full extern al rotation is achieved b y the p osterior deltoid and the lateral rotators, w hile the m id dle trapezius and the rhom boid s ad d u ct the scapula. S e rratu s a n terio r sta b ilise s the scap u la again st the thoracic w all. Eccentric co n tractions o f the su bscap u laris d ecelerates the m o v e m e n t, w h ile te re s m a jo r, latissim us dorsi, and p ectoralis m ajor co n trol the last d egrees o f lateral rotation and p rev ent excessiv e anterior translation of the hu m eru s in the glenoid. C oord ination and correct activ ation o f these m u scles therefore is im p o rtan t to m inim ise o v er strain on the anterior part o f the joint.
A cce le ratio n : P ectoralis m ajor, su b sca pu laris, latissim u s d orsi and teres m ajor a c t c o n c e n tr ic a lly as m e d ia l r o ta to rs . L ow er and upper trapezius and serratus anterior con tract con cen trically to hold the scapu la rotated and to m ove it laterally. W ith instability there appears to be a com p ensato ry increase in activ ity o f the b ice p s and the su p ra sp in a tu s m u scles. D im inish ed activ ity o f serratus anterior oc-.curs, w hich d im in ishes p rotraction o f the shoulder, therefore placing m ore stress on the anterior restraints. D im inish ed levels o f activity o f pectoralis m ajor, su bscap u laris, latissim u s dorsi and o f infraspinatus h a s a lso b e e n fo u n d . T h is im b a la n c e , w hether it is p art o f the p rim ary patholo gi cal process o r second ary to it, adds to the anterior instability and m u st be addressed sp ecifically d uring rehabilitation.

Clinical presentation:
• P ain w ith ov erhead activ ities, either d u rin g la te c o c k in g / a cc e le ra tio n or d uring follow -throu gh. T h ey are often v agu e and d ifficu lt to localise to any specific p osition o f the joint.

Rehabilitation:
The goal o f re h ab ilitation is to retu rn the ind ividu al to p re-in ju ry statu s, nam ely full m ov em ent, strength , en d u ran ce, coo rd in a tion and speed. lier. Exam ples are pushups, initially against the wall, progressing towards the floo r, m oving past the norm al movement into protraction of the sca pula. ' • Im prove dynam ic control about the shoulder joint. Exercises are initiated in a neutral position where control of the movement is retained. Short lever exer cises are used, for exam ple bilateral shoulder flexion, with the elbows in 90° flexion. These are progressed towards the position of instability, and towards the movement of the sporting activity. As control improves, the rotator cuff m u sclesare exercised con cen trically and eccentrically against resistance, for e x a m p le w ith s u r g ic a l tu b in g or weights. Strengthening only the lateral rotators for posterior instability and the medial rotators for anterior .instability fails to recognise the entire function of the cuff. • Increase muscle strength and endur ance. Only when full control of move ment is achieved, can resistance be in creased. W eight training is included using low weights at high repetitions to emphasise endurance. Isokinetic exer cises, concentrating on the rotators, are' instituted initially in the neutral posi tion. High speed, 180-240° are used, again to emphasise the control and en durance. From the neutral position these exercises are progressed towards 90° of abduction. • Re-educate proprioception. By improv ing muscular control, joint and muscle afferents are stimulated, thereby elicit ing reflex activity and improving mus cular control, joint and muscle afferents are stimulated, thereby eliciting reflex activity and improving proprioception. A d d itio n a l e x e rcise s, w ith w o bb le board and ball are included. • Improve flexibility. Optimal control re q u ires a p ro p er b alan ce of m u scle length between agonists and antagon ists to prevent further stress on gleno humeral and subacromial structures. • Introduce the sporting activity. The spe cific movements are included into the rehabilitation program within limits of pain. Initially emphasis is on fluidity and control of movement. Start with s m a ll ra n g e m o v em en ts fo r sh o rt periods gradually progressing range and time, concentrating on accuracy and control. Progression of exercise is always deter m in ed by the c o n tro l o f m o v e m e n t, presence of pain or related symptoms, and never by time! If the patient can throw at previous perform ance levels without dis comfort, he/she may return to competi tion. Never forget to include lower ex tremity and trunk strength work into the training program.

Principles of treatment:
Rehabilitation of the minor shoulder in stability can be very com plex. However, with careful analysis of the muscle firing pattern, and correction thereof starting proximally with the scapula control, good results can be achieved. It must be kept in mind, that conservative treatm ent is not sufficient if disorders of the passive sta bilisers are present. Post-operatively the same principles of treatm ent are followed, with close liaison betw een the patient, sur geon and therapist.
This paper was presented at the Congress of the South African Sports Medicine Association, Cape Town, March 1993.

IN MEMORIAM -KATHLEEN OLIVE SWEET Nee HARRIS, MCSP
Died suddenly in Fish Hoek on 30 August 1993.
She trained at Manchester Royal Infirmary, qualifying as a Chartered Physiotherapist in 1952. Shortly afterwards she came to South Africa and settled in the Cape.
She joined the Cape Provincial Administration in 1961 and worked her way through the ranks, becoming a grade 1 physiotherapist in 1967, and a principal in 1974. From 1969 she was based at the South Peninsula Group of Hospitals, and was eventually responsible for physiotherapy services within the group, until she retired.
It was through her efforts that the Neuro Rehabilitation Centre, now based at the Lady Michaelis Hospital, was established.
As a person she was quiet, charming, and courteous, and her staff and colleagues found her ever helpful, caring, ready to listen, and dependable. Although generally self-effacing she was always able to offer sound, construc tive advice, and what she said was worth listening to. She was noted for her steady persistence in the face of (sometimes strong) opposition until she had achieved her objectives. She held her profession in high esteem and served on many committees aimed at enhancing patient care.
She had an incredible zest for life, and her interests were wide ranging. She was a member of International Training for Communication (ITC), and was very involved with Community Projects, particularly those aimed at young people. At the time of her death she was actively involved in teaching English to underprivileged children. She loved the outdoors, and the Western Cape mountains were very special to her. She enjoyed hiking, and following adventure trails. Two of her latter exploits were: Rafting down the Orange River with her two grandchildren, and exploring Bushmanland on a Camel! She was an avid reader, good with her hands, and an active member of the Historic Club of Simonstown. She was a devoted wife, mother and grand mother.
Her sudden and untimely death has come as a great shock to those of us who were privileged to know her, and we extend our heartfelt condolences to Leonard, Alison and Hennie, grandchildren Hannes and Nicky, and to all members of her wider family circle.