The present study has been performed to investigate the biochemical characteristics of collagen in the organic constituent tissues of the shoulder joint. 1. Collagen was extracted from human deltoid, major pectoral, supraspinatus, infraspinatus, and minor teres muscles, long head of the biceps, the anterior capsule, membrane tissue of the rotator interval, subacrominal bursa, coracoacrominal and glenohumeral ligaments, and skin in 4 cases of males immediately after their accidental deaths ranging from 25 to 59 years old. 2. Hydroxyproline was determined to estimate the collagen contents in a neutral salt soluble, a citric acid soluble and an insoluble fraction. 3. Insoluble collagen was reduced with tritiated sodium borohydride. Hydrolysis of the reduced materials was carried out with 6N HC1 for 24h at 110°C in vacuo. Hydrolyzed samples were chromatographed in an Aminex A-5 colum. 4. Similar results were obtained from the tendon, capsule and subacrominal bursa, but the membrane tissue of the rotator interval was similar to the ligament. 5. In the biochemical study, the ligament was composed of the most stable collagen fibers, but the long head of the biceps produced relatively immature collagen fibers. 6. These data may approximately reflect the clinical features of each tissue.
The present study was undertaken to investigate the biochemical and histological characterstics of the glenoid labrum in the normal shoulder joint. 1. Collagen was extracted from human g lenoid labrum and acetabular limbus immediately after accidental death (ranging from 25 to 73 years old). 2. Sections were stained with hematoxylin-eosin, Alcian blue, Toluidine blue and Safranin 0. 3. The total collagen contents in the tissue were as follows: the glenoid labrum,20-40 per cent the acetabular limbus, 30-50 per cent of wet weight. 4. The amount of total soluble collagen in the glenoid labrum was 0.40-0.75 per cent and in the acetabular limbus was 0.3-1.0 per cent. 5. All samples consisted of mainly type I collagen and of a small amount of type III collagen. 6. In the glenoid labrum, specific radioactivity and the reducible crosslinks were richer than those in the acetabular limbus. 7. In all tissues, many fibrocyto were observed and they were lined with a connective tissue. 8. Fibro-cartilage cells were seen intervening between the acetabular cartilage and the labrum. 9. With aging, there was marked degeneration of the matrix, particularly in the acetabular limus. These data suggest that collagen in the glenoid labrum has relatively immature cross-links compared with those in the acetabular limbus.
The present study was undertaken to investigate the biochemical changes of collagen in animal joint capsules and muscles on traumatic dislocation and sciatic nerve cutting. 1. Collagen was extracted from a dog M. gluteus medius and M. biceps femoralis on traumatic dislocation. 2. The amounts of soluble collagen in the dislocated joint capsules and M. gluteus medius were richer than those in a normal joint, but there were no changes in the amounts of reducible cross-links in any tissues. 3. These data suggest that traumatic dislocations have no effect on the stability of collagen in the joint capsules and muscles. 4. Collagen was ext r acted from a rabbit M. gluteus medius, M. biceps femoralis and M. gastrocnemius by sciatic nerve cutting. 5. The amounts of total and soluble collagen and reducible cross-links were richer than those of normal muscles put under the sciatic nerve. 6. These data suggest that the collagen of the M. biceps femoralis and M. gastrocnemius produce relatively immature fibers compared with a normal joint. 7. All these data may suggest that the results of collagen in the L-S are inherent.
Ninety-six shoulders of sixty cadavers were examined to determine degenerative changes of the articular cartilage of the glenohumeral joints through the ageing process. Fifty-seven right and thirty-nine left shoulders of sixty males aged from 42 to 93 (mean 71.9), and thirty-six females from 53 to 98 (mean 73.6) were examined. Cadavers whose causes of death were infectious diseases and neoplasmas were excluded from this study. Of sixty-nine shoulders, three were found to have complete cuff 'tears and six incomplete ones. The Indian ink method was applied to clarify the irregularities of the cartilage. The degenerative changes of the articular surface were classified into five grades (grade 1: intact,2: surface flecking,3: mild fibrillation,4: severe fibrillation,5: ulceration). The surfaces of both the heads and the glenoids were divided into five areas (superior, anterior, inferior, posterior and central). The degree of degenerative changes was about the same regardless of age in both heads and glenoids, though changes were slightly more advanced in the former than in the latter. The grade was slightly higher in females than in males of any age, and slightly higher in the supeior area of heads, and the inferior area of glenoids. In shoulders with cuff tears, the degenerative changes were higher than those without tears. The changes were more advanced in the heads with complete tears than those with incomplete ones, althogh there was no difference in the glenoids. From these results we concluded: 1, Ageing has little effect on the degenerative process of the articular cartilage of the glenohumeral joints.2, There is a correlation between the existance of complete cuff tears and the degenerative changes of the glenohumeral joint.
No detailed report has been published on the supra-infraspinatus tendon junction where tendons with different tractive directions compose the rotator cuff despite the fact that mechanical stresses are mainly placed upon this site. During cadaver autopsy we noticed the formation of various spaces in this junction and investigated the characteristics of these intratendinous spaces. 274 joints were taken as specimens from 137 cadavers (84 males and 53 f emales) from 43 to 98years of age with an average of 74 years. After examining the surface of the rotator cuff, an incision was made over the junction of the supraspinatus and the infraspinatus tendon from the greater tuberosity to the muscles interval. The presence of intratendinous space was examined and if an intratendinous space was found, a macroscopic and microscopic examinations were performed. The formation of intratendinous space was observed in 46 joints (24 right joints and 22 left joints)of 33 cases (17 males and 16 females). The majority of spaces were found from the middle to the deep layer. Most of these spaces were located in tendon insertions and few were found in the more proximal portion. In many of the spaces formed in tendon insertions, the internal surface was irregular, whereas that of proximal spaces was smooth. Microscopic examination revealed two types of morphologic changes, in one the torn stump of tendon fibers was on the wall, and in the other it took the from of bursa enveloped with lining cells and areolar tissue. There are two types of intratendinous spaces formed in the junction of the supraspinatus and infraspinatus tendons, one of which is caused by a tendon tear and the other is bursa-like. Both the tendon tear and the formation of bursa indicate that stress is centered upon this site.
A separation between the labrum and the glenoid is often observed clinically. We carried out an anatomical study on the attachment of the labrum to the glenoid in order to investigate whether the separation is a pathological condition or a normal variation. One hundred shoulder joints taken from 50 cadavers, aged between 48 and 98 years, were used in this study. Firstly, the joints were investigated macroscopically. Then, histological sections were made for further detailed investigation with a microscope. Macroscopically, the manner of attachment was classified into two types: Type I; absence of a separation, Type II.; presence of a separation. Separations were frequently observed in the upper part of the glenoid, while scarcely in the lower part. In cases where a separation was found, the labrum covered the glenoid surface and thus a part of the separation was often hidden. Microscopically, Type II was classified into 2 subtypes. Type I: no separation was observed between the glenoid and the labrum, Type II A: a separation was observed but the articular cartilage and the labrum were smoothly connected, Type II B: a separation was observed and the articular cartilage and the labrum were not smoothly connected. When the upper 1/4 of the glenoid was investigated,24 joints were classified as Type I,58 joints as Type II A, and 18 joints as Type II B. No correlation between the types and age or sex was observed. Type I and II A were thought to have no relation to rotator cuff tears, while type II B was. Type I and II A were considered to be normal variations. Type II B was considered to be a pathological condition.
The purpose of this investigation is to document postmortem radiologic and histologic changes of the undersuface of the acromion and to elucidate the pathogenesis of so-called Neer's spur. A part of the acromion with the coracoacromial ligament inserted into the undersurface of the acromion, was obtained from 76 autopsy specimens (mean age 69.3 years). The specimens were radiographed in A-P direction. The insertion of the ligament at the acromion was macro-and microscopically examined. In 18.4% of the specimens a downward beaklike bony projection of the acromion was noted. In 9.2% of the cases an inferior spur at the ligament insertion into the acromion was observed. 4% of the specimens demonstrated localized sclerosis inferiorly. Degenerative changes were staged from grade 1 to grade 4. Hypertrophic change of the fibrocartilaginous layer was a characteristic finding in grades 1 and 2, and wear and tear of the undersurface of the acromion was typical of grades 3 and 4. Neer's spur which was always surrounded by a hypertrophied fibrocartilagionus layer, was found at the anteroinferior corner of the acromion. From this study it is felt, that 1) a bony variant can predispose an impingement syndrome, and 2) the hypertrophied fibrocartilaginous layer plays an important role in the degenerative process of the acromial insertion of the coraco-acromial ligament.
This study is intended to pursue the role of the long head of the biceps (hereafter referred to as long head) in the abduction of the upper extremities, and to review the technique of reconstructing the rupture of the long tendon by understanding the significance of the long head in shoulder movements. The subjects were patients with a rupture of the long head in 6 shoulders and musculocutaneous nerve palsy in one shoulder. The subjects were exercised for abduction of the upper extremities with a scapular plane, then, the locus was taken for the movement of the glenoid fossa and the head of the humerus. This technique was performed before and after reconstruction of the tendon in the above mentioned cases, and the results were reviewed comparatively in due course. Comparisons were made of the locus of the glenoid fossa and the head of the humerus in motion, time of abduction with the scapular plane in each stage in the afore mentioned cases, and the following results were obtained. 1. Rupture of the long head resulted in disorder of the locus of the glenoid fossa and the head of the humerus. 2. After a long time, only suturing the ruptured long head into the bicipital groove without end-to-end sutures resulted in the head of the humerus and glenoid fossa being in the same locus as the controls.
Since 1983; we have performed free vascularized scapular bone graft for such conditions as severe osteomyelitis, pseudoarthrosis, or large segmental bone defects. However, the effects of the removal of the lateral part scapula have not been published. This investigation attempted to assess the function of the donor site of the shoulder. In this study, twenty-seven patients who had undergone the surgical procedure more than a year previously, were investigated as to pain and disabilities by the questionnaire method and were evaluated according to the JOA shoulder scale. Isokinetic strength of the shoulder was measured in fourteen patients by Cybex II dynamometer. The strength of the shoulder that had been operated on was compared with that of the contralateral side. In the questionnaire study, eighteen of the twenty-seven patients had no pain, seven had tenderness, one had slight pain in daily work, and the remaining one had frequent night pain. In the isokinetic evaluation of the muscle strength, the peak values were expressed as percentage against the normal shoulder. For the entire study population, the decrease of strength was significant (p<0.05) in external rotation (80.9±27.4%) and in extension (85.1±18.0%). No statistically significant difference was found between the dominant and nondominant shoulders. We grouped the patients according to whether the grafted bone size was large (>5 cm) or small (<5 cm). The donor side strength of the large graft group was statistically significantly reduced (75.6±21.5%) in internal rotation at slow torque arm speed.
It is commonly known that elevation of the arm is combined with rotation. However it is very difficult to measure the rotational angle physiologically. We made a video-computer system for this and measured the angles during elevation in both the frontal and the scapular planes. A special bar (30g) was put on the elbow joint of twenty men and fifteen women. An X-Y plotter was used to get the positions of the tip a nd the middle point of the bar. Then a personal computer was used to calculate the rotational angle and to analyse the transposition of the instant center of the shoulder joint. From this study we conclude that the rotational angle in the frontal plane that (102.6°) is larger than thar in the scapular plane (65.0°) and that thar of the right shoulder is larger than the left shoulder one. Furthermore, we found that there are two different patterns in the rotational angle.
In the Impingement syndrome, the degenerative changes on the under surface are marked in the anterior 1/3 of the acromion. We considered the spatial position of this anterolateral portion an important causative factor. We have already reported that in the impingement group, the anterolateral point of the acromion is located more anteroinferially than in the normal group. In this report, we wish to verify our previous report by using a 2-dimensional finite element method. Materials were 6 cases,6 joints in the impingement group and 6 cases, 6 joints in the normal group. Using a 2-dimensional finite element method, we investigated the stress which the anterolateral portion of the acromion received. The model was made from a lateral radiograph and a second joint was set up to receive the upward force from the humeral head. The force on the anterolateral portion of the acromion changed with the position of the acromion. Especially, when the acromion was placed anteroinferially, the stress was inclined to increase. When Young's modulus of the supraspinatus tendon increased, the stress tended to concentrate in the hard region. When the stress on the anterolateral portion of the acromion increases, the mechanical stress on that portion will increase. Such stress is likely to cause subacromial impingement. The results of this report suggest that the spatial position of the acromion and the physical character of the rotator cuff may be causes of subacromial impingement.
The purpose of this study is to evaluate the capabilities of MRI on the normal rotator cuff. Four normal shoulders from four volunteers (25-31 y. o., mean 27 y. o. ) were used for imaging. In addition, images from twelve patients (19-80 y. o., mean 43.0 y. o. ) who had no apparent rotator cuff tear were reviewed retrospectively. For anatomical study, these images were compared with corresponding sections of four cadaveric shoulders. Our previous study has shown that FE image is the best for observing of the normal shoulder, in comparison with other spin echo MR images, such as the Ti weighted, the T2 weighted and the proton density weighted ones. In this study, FE images were taken under Shimadzu 1.0 Tesla superconductive MRI system, using a local flexible coil. They were taken in the oblique coronal (scapular) plane and in the plane transverse to the axis of the supraspinatus muscle (TASS plane). Two kinds of signal intensities were observed within the normal rotator cuff. Similar findings were observed in all the patients with the exception of an 80 y. o. woman. Their age including the normal volunteers ranged from 19 y. o. to 77 y. o. with a mean age of 38.7 y. o. Comparisons between these images and the cadaveric rotator cuffs showed the good correlation of the images with the anatomical structures. The area of low signal intensity represents the original tendon layer in the rotator cuff, while the comparatively high signal intensity region corresponds to the roughly distributed connective tissue within the rotator cuff. These findings on the images should not be regarded as abnormal. These results demonstrate that MRI is useful for the observation of the normal rotator cuff.
Magnetic resonance (MR) imaging has been known as a useful tool for imaging the musculoskeletal system, especially spinal lesions, avascular necrosis, and the tumors of the bone and the soft tissues. However, there are only a few reports on MR imaging around the shoulder joint. We reported on the technique of MRI for the shoulder and typical MR imaging of the shoulder disorders at the society'is meeting last year. The "so called 50 kata" is a Japanese traditional term for periarthritis scapulohumerale in English. We have examined 19 shoulders in patients with "so-called 50 kata" using MR imaging since February in 1988 and compared the MR images of the disorder with those of other diseases. The typical MR appearance of "so-called 50 kata" is relatively high intensity of the supraspinatus tendon with the T1-weighted and/or T2-rweighted sequence, which resembles that of subacromial impingement syndrome.
In the diagnosis of rotator cuff tears, arthrography is now established as a fully reliable method for a complete tear. However, arthrography is a little invasive, or often cannot demonstrate incomplete tears, and the site of tears. MR studies are less invasive, and have the possibility to demonstrate them. We performed MR studies of 45 patients, who had clinical signs suggesting rotator cuff tears, and compared the MR findings with arthrograms and those of MRI with intraarticular injection of Gd-DTPA. Scans were performed with a Siemence 1.5-T superconductive system. A body coil or a surface coil was used for all scans. Ti, proton density, and T2-weighted images were obtained of all patients in the oblique plane along the supraspinatus muscle.39 of the 45patients underwent arthrography.13 patients had findings of rotator cuff tearson both MR imaging and arthrography.19 had no findings of tears in either study.3 had findings of tears on MR imaging but had no findings of tears on arthrography. We think this discrepancy was caused by incomplete tears or degenerative changes.4 had no findings on MR imaging but had findings of tears on arthrography. In all of these cases, MR imaging was performed with using a body coil. We believe MR imaging with a body coil hasn't enough resolution to demonstrate small tears., MR imaging with intraarticular Gd-DTPA clearly demonstrated the size and site of tears. This method seems useful to demonstrate small tears which are not visible on usual MR imaging. In the diagnosis of rotator cuff tears, MR imaging has comparable abilities to arthrography. With the progress of MR imaging technic, MR imaging should be the better modality.
We adopted The Reverse West-Point View (hereinafter called RWP View) under which patients lay supine. We evaluated bony Bankart lesions and capsular detachments on recurrent shoulder dislocation and subluxation by means of a RWP View and others by comparing them with our operative findings. We used a double contrast arthrogram. 20 patients (20 shoulders) were taken up for evaluation.15 patients,15 shoulders suffered from recurrent shoulder dislocation and 5 patients,5 shoulders from recurrent subluxation. We classified the cases of bony Bankart lesions and capsular detachmen t into 3 grades by means of a pre-operative arthrogram and these were compared with our operative findings for closer examination. In 87.5 % of the cases, the degree of damage proved to be the same as the operative findings.
In this paper, we will discuss the anterior capsular mechanism from an arthrographic view point. In recurrent dislocations of the shoulder joint, we often see an abnormal shadow known as the ballooning. This is the theme of this paper. We want to study this phenomenon arthrographically. (Materials and Method) We performed double contrast arthrography on 6 2 shoulders with recurrent dislocation. In the internal rotation position we found four categories of medial aspect shadows shown arthrographycally. A is the superior aspect. B is the middle aspect. C is the inferior aspect. I (A. B. C. Three convex aspects) II (A, B combined, C distinguishable)III (A distinguishable, B, C combined) IV (A, B, C combined) (Result) When studying the 62 recurrent disloca i t on cases, we supposed we would find examples of types I, II, III and IV. Instead, all 62 shoulders were either type III or type IV. We found no examples of type I and type II. Finally, we think the caus e of inflamed B and C is disruption of the inferior glenohumeral ligament. In order to understand the extent of the injured inferior glenohumeral ligament, we took arthrograms with the X-ray beam at 30° medially and 40° cranially on supine. The relief in the inferior glenohumeral ligament was described in normal cases, but it was distinguished in recurrent dislocation cases. The irregular relief was described in dead arm syndrome cases too.
From April 1985 to September 1989,22 shoulders in 18 cases of positional instability of the shoulder joint were treated in Matsudo Orthopaedic Hospital. Among them 10 shoulders in 10 cases were treated operatively. Nobuhara's glenoid osteotomy was performed in the first 3 cases; but recuruence was recognized in 2 cases. For positional instability of the shoulder joint, one-directional reinforcement is not enough. Two-directional reinforcement is necessary. Since November 1987, in 7 cases we performed a two-directional glenoplasty in which downward and anterior or posterior reinforcements of the shoulder joint can be performed at the same time. The graft is made up of a wedge part that is inserted into the osteotomized bed of the scapular neck and raises up the glenoid and a bone block that extends the glenoid. The results of 5 cases which were followed-up over 11months after surgery were excellent and no recurrences were recognized. Among these 22 shoulders of the positional instability,2 sho u lders developed from loose shoulder syndrome,5 shoulders from voluntary dislocation and 2 shoulders from loose shoulder syndrome to voluntary dislocation then to positional instasbility (One of them returned to loose shoulder syndrome). Spontaneous recovery was noticed in a male patient. We consider that the positional instability of the shoulder is included in a large category of shoulder instabilities like the loose shoulder syndrome and voluntary dislocation. The morbidity of these disorders changes into one of the other two according to the alteration of grade of the shoulder instability.
We have measured the intra-articular pressure simultaneously with arthrography of the shoulder. In this study, changes in the intra-articular pressure were examined in unstable shoudlers associated with loose shoulder, rotator interval lesion, and traumatic recurrent anterior dislocaiton. Of the 731 shoulders (731 patients) in which intra-articular pressure was me a sured from 1981, the measurement was possible in 254 shoulders (254 patients). A total of 91 shoulders, consisting of 20shoulders with traumatic recurrent anterior dislocation,40 loose shoulders, and 31 shoulders with rotator interval lesion, were evaluated. Physiologic saline was in f used into the joint, and canges in the intra-articular pressure were recorded as electric signals through a transducer. The arm was moved up and down passively, and the pressure was measured at intervals of 10. In loose shoulder and rotator interval l e sion, the intra-articular pressure decreased as the arm was lifted higher, but the decreases were smaller than in normal shoulders. In these groups, there was a smaller pressure increase to the position of maximum uplift with a smaller peak value and within a narrower range than in the normal group. These findings were more notable in the shoulders with an FSH angle of 81' or greater. These results suggest that the intra-articular pressure reflects the joint capacity. In traumatic recurrent anterior dislocation, however, the decrease in the pressure in an early stage of arm lifting was the greatest among all groups including the normal group, and the pressure increase with arm lifting was gentler in shoulders with an FSH of 80 °or less, unlike in the other two groups. The changes in the intra-articular pressure in shoulders with traumatic recurrent anterior dislocation may be explained by disruption of the anterior capsular mechanism and muscle contraction due to anxiety over the possibility of dislocaiton during arm lifting as well as the looseness of the articular capsule.
The measurement of the glenoid tilting angle (G. T. A. ) and of the ratio between the diameter of the glenoid and the humeral head (G/H ratio) has been done at Nobuhara Hospital since 1970. The results were reported at the 10th annual meeting of the Japan Shoulder Society. As a result, it was thought that the cause was retrotilt and/or a short diameter of the glenoid in loose shoulder. On the other hand, in the cases of recurrent anterior dislocation, many cases having antetilt and/or a short diameter of the glenoid. However, some cases with normal values in G. T. A. and G/H ratio were also found. In this report, all cases are divided into the following 4 groups by mean values and the standard deviation of the normal group. Group L: The G. T. A. is higher. Group B: The G. T. A. is normal but the G/H ratio is lower. Group N The G. T. A. is normal and the G/H ratio is normal or higher. Group D: The G. T. A. is lower. In loose shoulder, group s L and B are 61.6%, group N is 17.9% and group D is 20.5%. In recurrent anterior dislocation, groups D and B are 60.2%, group N is 15.1% and group L is 24.5%. Hypoplasia which was thought to be retrotilt and/or a shortening of the gleno i d was the main cause of loose shoulder, but cases with antetilt of the glenoid or a normal bony construction were also as unstable as if they had loose shoulder. It is believed that the cause of instability in cases with antetilt was increased slackness of the capsule and the cause in the normal group was a soft tissue abnormality. Recurrent anterior dislocations mainly occured in cases with antetilt and/or a shortening of the glenoid. However, they also occured in cases with retrotilt. In short, prolonged instability caused such difficult conditions that recurrent anterior dislocation was combined with loose shoulder.
Loose shoulder shows abnormal instability and various symptoms, but it's mechanism is not analyzed clearly. In this study, we measured the ball roll(B) and gliding(G) in loose shoulders and compared them with those in healthy subjects. Using an image analyzing system, B and G values during active elevation on the scapular plane were measured, and the B+G values and | G | /B ratios were calculated in 28 loose shoulders (LS) and 60 normal subjects (N). In addition, evaluation was made in 4 phases of motion, setting phase, hanging joint phase, transitional zone phase and phase of joint needing support. The results were as follows: 1) As the arm was elevated, in group LS, the B values gradually decreased, but the G values varied widely. 2) Glenohumeral movement in group N could be divided into 3 phases according to the B+G values and the | G | /B ratios, but in group LS no regularity was observed. 3) The slipping phenomenon in group LS was found at the transitional zone phase and the phase of joint needing support. 4) Motion range of the center of the humeral heatl was 8% of the long axis of the glenoid in group N, but in group LS it was 16%. 5) In group LS, glenohumeral movement, especially gliding mechanism was failed.
There have been few reports about shoulder instability in cases of progressive muscular dystrophy. We examined shoulder instability in Duchenne's dystrophy (DMD) and limbgirdle type dystrophy (L-G) cases. Materials used in this study were sixteen cases of DMD (all cases were male, aged 11 to 21 years old with a mean age of 16 years old) and thirteen cases of L-G (11 males and 2 females, aged 28 to 50 years old with a mean age of 41 years old). We examined the range of motion of the shoulder and did manual muscle testing. We also measured shoulder instability using X-ray photos from several angles. The shoulder was frequently flail in progressive muscular d y strophy. The incidence of descent of the humeral head was 10 % or more in 19 of 32 shoulders (59 %) with DMD and 10 of 26 (38 %) with L-G. The value of the transverse glenohumeral index (Saha) in the DMD cases was smaller than that of both the L-G cases and Saha index. There was a high incidence o f abnormal shoulder instability in both DMD and L-G cases. We feel weakness of muscles, such as the rotator cuff, was one of the main causes of shoulder instability in these cases. In most of the DMD cases, the glenoid was too small in relation to the humeral head suggested from measurements on X-ray photos and this probably was one of the causes of shoulder instability.
Dynamic study is important to evaluate the condition of loose shoulder. We reported at the 14th Japan Shoulder Society meeting that the muscle contraction curve produced a different pattern in those with instability, and we thought this muscular imbalance might cause functional disorder of the loose shoulder. This time we have analyzed more materials and post medical treatment cases, using a Cybex II isokinetic dynamometer. Twenty-nine patients, with forty-nine shoulder joints were investigated. Their shoulders were significantly unstable, and this was checked by arthrography. The control group consisted of forty-one normal individuals, with eighty-one shoulder joints. Results. It was found that muscle contraction power was lower in abduction, adduction, extension and flexion in the patients group compared with the control group. The correlation between these four directions could be seen in the control group, but in the patients group, the correlation between abducition and adduction, and also between flexion and extension could not. The muscle contraction curve showed a different pattern, with an abnormal wave in twentyseven patients (89%). But this abnormal wave improved after surgical or conservative treatment. Discussion Our results show that the lower and ill-balanced muscle strength and dynamic instability might cause a functional disorder of the loose shoulder. The isokinetic study was useful in evaluating the dynamic instability of loose shoulder and the effects of its treatment.
There are various kinds of operations for multidirectional instability. Although a somewhat constant level of success has been achieved, they are not always effective in all cases. We have performed the extended Bankart operation to tighten the capsule because we noted that the common finding in all cases is the enlargement and relaxation of the capsule. In the present study, clinical cases were analysed to study the usefulness of this procedure. Seventeen shoulders in 17 cases (9 males and 8 fe m ales) who were operated on during the period from September 1987 to December 1988 were examined. Of all the cases with bilateral instability,8were operated on the right side and 9 on the left. The age ranged from 13 to 43 years. Trauma was the clue to onset in 12, and 5 had on history of trauma.2 cases had a long history of voluntary disl. with a psychological component. Past history of involuntary disl. or sublux. was present in 15. The instability was three-directional in 13 cases, and two-derectional (A-P) in 4. General joint laxity was present in 2. As for the surgical procedure, the capsule ranging from the anterosuperior to the postero-inferior was separated, and was sutured (6-8 sutures) again to the glenoid rim while the capsule was raised anterosuperiorly. Postoperatively, physical therapy was performed after oneweek fixation at a neutral position with a sling. No one has complained of instability or objectively shown a recurrence. This operation was considered effective in so far as the results of short-term follow-up studies were concerned. The tightening of the capsule is suspected to limit instability not only through physical actions, but also through physiological actions.
Based on the data presented in 1986, we tried to make a clinical application for measuring the slope of the acromion. First, we took a correct lateral view X-ray film of scapula through a fluoroscope by using macerated scapulae and named it as supraspinatus outlet view. This lateral view of the scapula must show a clear shape of supraspinatus fossa and spine of scapula. Then we measured the slope of the acromion (α-angle) with the procedure presented in 1986, and we confirmed the accuracy of the data obtained by this method. Next by using this procedure, we took 228supraspinatus outlet views of both 71 healthy males and 43 females, their age ranged from 18 to 33. Then we measured the slope of the acromion. The a-angle of healthy male was 33.6+4.3 degrees and that of healthy female was 35.0 ±4.3 degrees, ranged from 23 to 45 degrees. There was an apparent difference in a-angle between healthy males and females (p<0.02). Finally, we measured the a-angle of both 56 shoulders in 28 males and 16 shoulders in 8 females who had stage II subacromial impingement lesion without spur on the undersurface of the acromion. Their age ranged from 15 to 48. The a-angle was 30.5±3.4 degrees in males and 31.9±2.8 degrees in females, ranged from 23 to 39 degrees. The a-angle of the patient with impingement lesion was singnificantly less than that of healthy adult (p<0.001). The following results were obtained; Supraspinatus outlet view was clinically useful in measuring the slope of the acromion. The less or flat slope of the acromion may be an important factor in the pathogenesis of subacromial impingement.