1. In ten healthy young men an experimental paralysis of the supraspinatus muscle was induced with the aid of Xylocaine injected in or near the suprascapular nerve.

2. The completeness of the paralysis was checked by electromyography.

3. With the supraspinatus muscle completely eliminated, all subjects could move the arm against gravity through its full range in the shoulder joint, though the force and the power of endurance during abduction were diminished.

4. It is concluded that the role of the supraspinatus muscle is of a quantitative nature only.

The retear of the rotator cuff (RC) repair is a significant problem. Usually it is the effect of poor quality of the tendon. The aim was to evaluate histologically two types of RC reconstruction with scaffold. We have chosen commercially available scaffold polycaprolactone based poly(urethane urea). Rat model of supraspinatus tendon injury was chosen. There were four study groups: RC tear (no repair) (n=10), RC repair (n=10), RC repair augmented with scaffold (n=10) and RC reconstruction with scaffold interposition between tendon and bone (n=10). The repairs were investigated histologically at 6 and 16 weeks. The results in two groups in which scaffold was used had significantly better scores at 6 weeks comparing to non-scaffold groups (16,4±3, 17,3± 2,8 vs. 12,5±4,4, 13,8±1,4 respectively) and 16 weeks (23±1,9, 22,8±1,6 vs. 13,8±3,3, 14,9± 3,8 respectively). Results in two scaffold groups improved between 6 and 16 weeks. Signs of foreign body reaction against scaffold were not observed. Application of scaffold to strengthen the repair site and bridging of the tendon defect improved healing of the RC repair in animal model at 6 and 16 weeks. The quality of reconstructed tendon improved over time. No such effect was observed in groups without repairs and isolated repairs were performed.

Background

To determine if double needle ultrasound-guided hydrodissolution and aspiration of intratendinous calcification is more effective treatment than blind subacromial corticosteroid injection.

To quantify the variation in strain between the deep and superficial layers of the supraspinatus tendon, ten cadaveric shoulders were tested on a purpose built rig. Differential Variable Reluctance Transducers (DVRTs) were inserted into the superficial and deep aspects of the tendon spanning the critical zone. DVRTs accurately measured linear displacement and from this strain was calculated.

The strain was measured for two aspects of supraspinatus action, abduction from 0 to 120 degrees with a tensile load (100 Newtons) and static load increases at zero abduction (20, 50, 100, 150 and 200 Newtons). After preconditioning, ten sets of results were recorded for each load/position.

The hypothesis, there is a statistically significant difference in strain between the superficial/deep supraspinatus tendon during abduction and with static loading, was tested using a one way ANOVA.

During abduction a statistically significant difference in strain was measured between the layers of the supraspinatus tendon at thirty degrees (p=0.000428) and this increased with further abduction.

Tensile loading increased tendon strain more in the deep layer of the tendon. This was statistically significant at loads greater than 150N (p= 0.007).

The variation in properties between the superficial and deep layers of the supraspinatus tendon has been proposed as a cause of differential strain (1). This study confirms statistically different strains between the superficial and deep tendon layers. It is proposed that the resulting shearing effect initiates intratendinous defects and ultimately tears.

1. The end-results of conservative treatment of supraspinatus tears have been studied in a series of 109 patients graded on a clinical basis, and in a further series of twenty-seven patients assessed initially by procaine infiltration.

2. In 87 per cent. of patients with mild lesions, full function was regained in an average period of five and a half weeks. In more than 50 per cent. of patients with apparently severe lesions, there was full functional recovery in eleven to thirteen weeks.

3. Clinical assessment, other than as mild or apparently severe, is unreliable in the early stages.

4. Procaine infiltration of recent tears, by abolishing pain and spasm, allows more accurate assessment of supraspinatus function and gives a more clear indication as to the advisability of conservative or early operative treatment. If such infiltration of the torn segment of tendon fails to restore voluntary abduction power, early operative repair is indicated.

5. Six patients with negative procaine tests, in whom the shoulder cuff was subsequently explored, all showed extensive tears.

Background: It is commonly believed that rotator cuff tears do progress in size over time. Recent reports suggest that tear progression may not be necessarily true. It was the purpose of this study to review non-operatively treated isolated supraspinatus tears especially in terms of tear size progression.

Methods: Inclusion criteria were non-operatively treated isolated full-thickness tears of the supraspinatus, MRI at time of diagnosis available, and patients willing to undergo an additional MRI after more than 2 years after diagnosis. Twenty-four patients (20 men, 4 women) with an average at time diagnosis of 51 years identified and reviewed with MRI and clinically based on the Constant score.

Results: The average follow-up was 46 (27–87) months. The Constant score (not available at time of diagnosis) at follow-up averaged 75 points (relative Constant score 86%). Overall the average tear size did not change significantly over time (366mm2 at follow-up versus 393mm2 at time of diagnosis, p > 0.05). In 2 patients the tear was not detectable any longer on MRI suggesting that it was healed, in 7 patients the tear was smaller, in 10 patients it did not change over time and only in 5 patients it progressed.

Discussion and Conclusion: Non-operatively treated isolated supraspinatus tears were unchanged, smaller or even healed in 79% of the patients after a follow-up period of more than 4 years. This suggests that supra-spinatus tears do not necessarily progress over time and even have a potential to heal.

1. The supraspinatus group of lesions constitutes one of the two common causes of the painful shoulder.

2. Most, but not all, of these lesions resolve either spontaneously or after conservative treatment.

3. When conservative treatment fails symptoms can be relieved by excision of the acromion process, provided that sufficient bone is removed to relieve all pressure on the tendon throughout a full range of shoulder movement.

4. Excision of the acromion is contra-indicated if there is doubt as to the diagnosis or if there is true limitation of shoulder movement.

1. The explosive type of painful shoulder due to rupture of a calcified deposit into the sub-deltoid bursa is described.

2. A brief report of six cases is presented.

3. No treatment other than rest and sedation is needed.

Purpose

Full-thickness tendon tears of the supraspinatus (SP) are common and can have a significant impact on shoulder function. To optimally treat supraspinatus tendon tears an accurate understanding of its musculotendinous architecture is needed. We have previously shown that the architecture of supraspinatus is complex. It has architecturally distinct regions: anterior and posterior, each of which is further subdivided into superficial, middle and deep parts (Kim et al., 2007). Data of FBL and PA of the torn supraspinatus could enhance clinical decision making and guide rehabilitative treatments (Ward et al., 2006). Currently, however, in vivo US quantification of the fiber bundle architecture of the distinct regions of supraspinatus in subjects with full-thickness tendon tears has not been investigated.

PURPOSE: To quantify architectural parameters within the distinct regions of supraspinatus in subjects with a full-thickness tendon tear using the US protocol that we previously developed (Kim et al., 2010), and to compare findings with age and gender matched normal controls.

Summary Statement

Tendon-bone interface becomes matured with the perforating fiber and the cells striding over the bone area. We suggest that both “perforating fiber” and “cell stride” could play a crucial role in regeneration after rotator cuff repair.

We measured the isokinetic strength of abduction, adduction, internal rotation, and external rotation in ten patients with full-thickness tears of the supraspinatus and ten with partial-thickness tears. The measurements were repeated after intra-articular or intrabursal injection of local anaesthetic.

Pain blocks produced significant increases in strength in both full and partial-thickness tears. After the block, the strength in full-thickness tears compared with the opposite side was 67% to 81% in abduction and 67% to 78% in external rotation, both significantly smaller than those on the uninvolved side (p = 0.0064, p = 0.0170). In partial-thickness tears the strength after the block ranged from 82% to 111%, with no significant differences between the involved and uninvolved sides.

The decreases in strength of 19% to 33% in abduction and 22% to 33% in external rotation after full-thickness tears appear to represent the contribution of supraspinatus to the strength of the shoulder.

Excessive apoptosis has been found in torn supraspinatus tendon1 and mechanically loaded tendon cells2. Following oxidative and other forms of stress, one family of proteins that is often unregulated are Heat Shock Proteins (HSPs). The purpose of this study was to determine if HSPs were unregulated in human and rat models of tendinopathy and to determine if this was associated with increased expression of regulators of apoptosis (cFLIP, Caspases 3& 8).

A running rat supraspinatus tendinopathy overuse model 3 was used with custom microarrays consisting of 5760 rat oligonucleotides in duplicate. Seventeen torn supraspinatus tendon and matched intact subscapularis tendon samples were collected from patients undergoing arthroscopic shoulder surgery. Control samples of subscapularis tendon were collected from ten patients undergoing arthroscopic stabilisation surgery and evaluated using semiquantative RT-PCR and immunohistochemistry.

Rat Microarray: Upregulation of HSP 27 (×3.4) & 70 (×2.5) and cFLIP (×2.2) receptor was noted in degenerative rat supraspinatus tendon subjected to daily treadmill running for 14 days compared to tendons of animals subject to cage activity only. Histological analysis: All torn human supraspinatus tendons exhibited changes consistent with marked tendinopathy. Matched subscapularis tendon showed appearances of moderate-advanced degenerative change. Apoptosis mRNA expression: The expression levels of caspase 3 & 8 and HSPs 27 & 70 were significantly higher in the torn edges of supraspinatus when compared to matched subscapularis tendon and control tendon (p< 0.01). cFLIP showed significantly greater (p< 0.001) expression in matched subscapularis compared to supraspinatus and control tendon. Immunohistochemical analysis: cFLIP, Caspase 3 & 8 and HSP 27 and 70 was confirmed in all samples of torn supraspinatus tendon. Significantly increased immunoactivity of Caspase 3& 8 and HSP 27 & 70 were found in torn supraspinatus (p< 0.001) compared to matched and normal subscapularis. The proteins were localized to tendon cells.

The finding of significantly increased levels of Heat Shock Proteins in human and rat models of tendinopathy with the co-expression of other regulators of apoptosis suggests that Heat Shock Proteins play a role in the cascade of stress activated-programmed cell death and degeneration in tendinopathy.

Purpose of this study is to create an experimental model of electrophysologic evaluation of the supraspinatus muscle on rats, after traumatic rupture of its tendon.

The population of this study consisted of 10 male Sprague Dawley rats weighting 300–400g. Under general anaesthesia we proceeded with traumatic rupture of the supraspinatus tendon and exposure of the muscle. The scapula was immobilized, and the supraspinatus tendon was attached to a force transducer using a 3–0 silk thread. A dissection was performed in order to identify the suprascapular nerve, which was then stimulated with a silver electrode. Stimulations were produced by a stimulator (Digitimer Stimulator DS9A) and were controlled by a programmer (Digitimer D4030). Fiber length was adjusted until a single stimulus pulse elicited maximum force during a twitch under isometric conditions. Rectangular pulses of 0.5 ms duration were applied to elicit twitch contractions. During the recordings, muscles were rinsed with Krebs solution of approximately 37 8C (pH 7.2–7.4) and aerated with a mixture of 95% O2 and 5% CO2. The output from the transducer was amplified and recorded on a digital interface (CED).

The following parameters were measured at room temperature (20–21 8C): single twitch tension; time to peak; half relaxation time; tetanic tensions at 10, 20, 40, 80 and 100 Hz; and fatigue index, which was evaluated using a protocol of low frequency (40 Hz) tetanic contraction, during 250 ms in a cycle of 1 s, for a total time of 180 s. The fatigue index value was then calculated by the formula [fatigue index=(initial tetanic tension − end tetanic tension) ∗ 100/(initial tetanic tension)]. In the end, the transducer was calibrated with standard weights and tensions were converted to grams.

The mean single twitch was 8.2, the time to peak 0.034 msec and the half relaxation time 0.028 msec. The strength of titanic muscle contractures was 5.7 msec at 10Hz and 17.7 at 100Hz. Finally, the fatigue index was calculated at 48.4.

We believe that electrophysiologic evaluation of the supraspinatus muscle in rats will help us understanding the pathology of muscle atrophy after rotator cuff tears and possibly the functional restoration after cuff repair

Purpose of the study: Fatty infiltration and atrophy of rotator cuff muscles is an important prognostic factor for anatomic healing and function after repair. The purpose of this study was to analyse factors influencing the development and progression of the supraspinatus muscle and to search for correlation between infiltration and atrophy.

Material and method: Preoperative arthroscans and MRI series for 1688 patients with rotator cuff tears were reviewed. We searched for correlations between fatty infiltration of the supraspinatus muscle and gender, age at imaging, size of the tear, onset (trauma or not), and time from symptom onset to imaging. Fatty infiltration was noted according to the Goutallier classification and on the MRI using the classification adapted by Fuchs. For the statistical analysis, fatty infiltration was considered minor for grades 0 and 1, moderate for grade 2 and severe for grades 3 and 4. Muscle atrophy was assessed using the tangent sign.

Results: Fatty infiltration of the supraspinatus increased significantly with the size of the tendon tear (p< 0.0005), time from symptom onset to imaging (lp< 0.0005) and patient age (p< 0.0005). Atrophy increased with number of torn tendons, positive tangent sign was correlated with the grade of fatty infiltration of the supraspinatus (p< 0.0005) and the infraspinatus (p< 0.0005). Moderate and severe fatty infiltration developed a mean 3 and 5 years, respectively, after symptom onset.

Discussion: Surgical treatment should be undertaken before the appearance of moderate (grade 2) fatty infiltration and atrophy (positive tangent sign).

Conclusion: Moderate fatty infiltration of the supraspinatus develops on average three years after onset of symptoms.

Purpose: We hypothesised that the rate of tendon healing after arthroscopic repair of full-thickness tears of the supraspinatus is equivalent to that obtained with open techniques reported in the literature.

Material and methods: We studied prospectively a cohort of 65 patients with arthroscopically repaired full-thickness tears of the supraspinatus. The patients were reviewed a mean 19 months (12–43) after repair. At arthroscopy, patients were aged 59.5 years on average (28–79). Bone-tendon sutures were performed with resorbable thread and self-locking anchors positioned on the lateral aspect of the humerus. Repair was protected with an abduction brace for six weeks. Forty-one patients (63%) accepted an arthroscan performed six months to two years after arthroscopy to assess tendon healing.

Results: Ninety-four percent of the patients were satisfied with the outcome. The mean Constant score was 51.6±10.6 points preoperatively and 80.2±13.2 at last follow-up (p< 0.001). The arthroscan showed that the rotator cuff had healed in 70% of the cases (29/41). The supra-spinatus had not healed on the trochiter in eight cases (25%) and was partially healed in two (5%). The size of the residual tendon defect was less than the initial tear in all cases except one. The rate of patient satisfaction and function was not significantly different if the tendon had healed (Constant score 81.3/100, satisfaction 93%) or if there was a residual tendon defect (Constant score 77.5/100, satisfaction 92%). Shoulder force in patients with a healed tendon (6±1.9 kg) was better than in those with a tendon defect (4.5±2.8 kg), but the difference was not significant. Factors affecting tendon healing were age > 65 years (43% healing, p< 0.02), and wide tears.

Conclusion: Arthroscopic repair of isolated supraspinatus tears enables tendon healing in 70% of cases as demonstrated by arthroscan. This rate was equivalent to those reported in historical series of open repair. Patients aged over 65 years had significantly less satisfactory healing. The absence of tendon healing does not compromise functional and subjective outcome despite reduced force.

The rotator cuff is sited on the anatomical neck of the humerus and is formed by the insertion of the supraspinatus (SP), infraspinatus (IS), teres minor (TM) and subscapularis. All play a vital role in the movement of the glenohumeral joint, and the anatomy is of critical importance in arthroscopic rotator cuff repair. We undertook an osteological and gross anatomical dissection study of the insertion mechanism of these tendons, in particular the SP .

The SP inserts by a triple or quadruple mechanism. The ‘heel’ (medial) and capsule fuse, inserting into the anatomical neck proximal to the anterior facet of the greater humeral tubercle. The ‘foot arch’ inserts as a strong, flat, fibrous tendon into the facet. This area is cuboidal, rectangular, or ellipsoid, and measures 36 mm² to 64 mm². In about 5%, the insertion is fleshy (pitted), rendering it weaker than a tendinous attachment. The ‘toe’ lips over the edge of the facet laterally and fuses with the periosteum, fibres of the inter-transverse ligament and the IS. A proximal ‘hood’ of about 4 mm stretches down inferiorly and fuses with the periosteum of the humeral shaft. The subacromial or subdeltoid synovial bursa are sited laterally.

The IS and TM insert into the middle and posterior facets (225 mm and 36 mm²) at respective angles of 80° and 115°. The inferior portion of the TM facet is not fused with the shoulder capsule. The subscapularis inserts broadly into the lesser tubercle, and the superior fibres fuse with the shoulder capsule and intertransverse ligament. The insertion of the subscapularis does not contribute directly to the formation of the ‘hood’, which belongs exclusively to the SP, IP and TM.

This study confirms the complexity of the SP insertion and suggests that an unfavourable attachment or biomechanical anatomical malalignment may lead to eventual tendon/cuff degeneration.

The supraspinatus tendon (SP) often ruptures. Gray established that the tendinous insertion always attaches to the highest facet of the greater tubercle of the humerus. Our osteological study of 124 shoulders in men and women between the ages of 35 and 94 years refocuses on the humeral insertion of the SP in relation to infraspinatus (IS) and teres minor (TM).

We found type-I SFs (cubic) in 53 shoulders (43%) and type-II SFs (rectangular or oblong) in 21 (17%). Type-III (ellipsoid) SFs were present in 20 shoulders (16%) and type-IV (angulated or sloping) in 11 (9%). SFs were type V (with tuberosity) in 12 shoulders (10%) and type VI (pitted) in three (2%). The facet area of the SP, IP and TM varied from 49 mm, 225 mm and 36mm2. Of the three muscles, the IS facet was consistently the largest (p < 0.05) and shaped rectangularly.

The SP inserted in a cubic or rectangular facet format in 75% of people. SP facet-size may relate to tendon strength, degeneration and rupture. This information may contribute to the understanding of tears of the rotator cuff.

Introduction and Objectives: Damage of the supraspinatus tendon (SST) is frequent in persons over 50 years of age. The aim of our study is to assess the degree of satisfaction and shoulder functionality after suture of the SST during open surgery by means of a 11–13 year follow-up.

Materials and Methods: Between 1995 and 1997 in our center, by means of open surgery, 45 SST sutures were performed (< 4 cm) with associated acromioplasty. At a minimum of 11 years follow-up we assessed the degree of patient satisfaction and performed the Constant test and the Jobe test.

Results: We studied 36 shoulders belonging to 33 patients (6 were lost to follow-up and 3 died). There were 21 women (63.6%) and 12 men (36.4%) in the series. Mean age was 52.3 years (31–64) and the affected shoulder was on the dominant side in 82% of cases (3 were bilateral). Of the 33 patients (36 shoulders) we obtained 21 very good scores (58.3%), 11 good (30.5%), 3 regular (8.3%) and 1 poor (2.7%). Using Constat’s test we obtained a mean score of 74.7 at the end of the process (pain 12.6, activity 18.1, mobility 36.9 and strength 7). We also used the Jobe supraspinatus test to assess patients and obtained negative results in 22 cases (61.1%), positive results in 8 cases (30.5%) and no results in 3 cases (8.3%).

Discussion and Conclusions: We were able to see both clinical improvement (subjective and Constant test) and strength in the supraspinatus tendon (Jobe) in 91.7% of cases at 11–13 years of follow-up.

INTRODUCTION

Rotator cuff tears are common injuries which often require surgical repair. Unfortunately, repairs often fail [1] and improved repair strength is essential. P2 Porous titanium (DJO Surgical, Austin TX) has been shown to promote osseointegration [2,3] and subdermal integration [4]. However, the ability of P2Porous titanium to aid in supraspinatus tendon-to-bone repair has not been evaluated. Therefore, the purpose of this study was to investigate P2 implants used to augment supraspinatus tendon-to-bone repair in a rat model [5]. We hypothesized that supraspinatus tendon-to-bone repairs with P2 implants would allow for ingrowth and increased repair strength when compared to standard repair alone.

Aim: The purpose of this study was to evaluate the cytokine molecules present in a rat tendinopathy model and in the torn edge of human rotator cuff tendon in an attempt to understand their role in tendon degeneration.

Methods: A rat tendon overuse model was used with custom microarrays consisting of 5760 rat oligonucleotide features in duplicate. Seventeen torn supraspinatus tendon and matched intact subscapularis tendon samples were collected from patients undergoing arthroscopic shoulder surgery.Control samples of subscapularis tendon were collected from ten patients undergoing arthroscopic stabilisation surgery.Specimens were analysed for the presence of interleukins 18, 15, 12, 11, 6, 2, macrophage inhibitory factor (MIF), and tumour necrosis factor Ą by semiquantitative RT-PCR and immunohistochemistry. Tendinopathy was assessed on a basic histological scale.

Results: Rat Microarray analysis: Upregulation of IL-6, IL-11 and IL18 receptor was noted in the degenerated rat supraspinatus tendon. Downregulation of IL-2 was noted. No other cytokine signal was expressed. Histological analysis: All torn human supraspinatus tendons changes consistent with marked tendinopathy. Matched subscapularis tendon showed appearances of moderate-advanced degenerative change. Cytokine mRNA expression: TNF-£\ mRNA expression was found to be significantly elevated (p< 0.01) in subscapularis tendon compared to torn supraspinatus samples. The expression levels of IL-18, IL-15, IL-6 and MIF was significantly higher in the torn edges of supraspinatus when compared to matched subscapularis tendon and normal control tendon (p< 0.001).

Immunohistochemical analysis: Presence of IL-18, IL-15, Il-6, MIF and TNF-£\ was confirmed in all samples of torn supraspinatus tendon. Significantly increased levels of IL-18, IL-15, IL-6 and MIF were found in torn supraspinatus. (p< 0.01) compared to matched and normal subscapularis.

Conclusions: Cytokines have been shown to promote the intensive production of reactive O2 metabolites ¹ and are potent agonists of protein kinases ². Our finding of significantly increased cytokine levels may suggest that these molecules when expressed during the degenerate and healing phases of tendon injury result in the subsequent production of reactive O2 species and protein kinases³ causing tendon damage or failure of the normal reparative process. Our finding of marked tendinopathy in matched subscapularis tendon may also provide a useful human tendinopathy model.