Recently, many patients and friends have been asking questions about shoulder disorders. In order to enhance the understanding of shoulder disorders and to achieve early diagnosis and timely treatment, we have written this article for your reference in the hope that it will help people’s health care.
Rotator cuff injury was first discovered and named by Smith in 1834, but did not attract much attention until Codman and Akerson pointed out in 1931 that the disease was an important cause of shoulder pain and made preliminary studies on its diagnosis and treatment, and then many scholars began to conduct a lot of research on the disease. Rotator cuff injury is one of the most common shoulder disorders in middle-aged and elderly people, which can cause shoulder pain and serious shoulder dysfunction, and its incidence accounts for about 17% of shoulder lesions and 41% of Nobuhara in Japan, which seriously affects the quality of life of middle-aged and elderly people. In this paper, we will review the anatomical biomechanics, etiology, diagnosis and treatment of rotator cuff.
I. Anatomical biomechanics: The rotator cuff is composed of muscle fibers of the supraspinatus, infraspinatus, subscapularis and teres minor muscles that originate from the scapula and attach around the humeral head, mixed with the shoulder capsule, forming a cuff-like structure at the anatomical neck of the humeral head, which has a supporting and stabilizing effect on the shoulder-humeral joint. When the shoulder joint is abducted and lifted, the contraction of the rotator cuff muscles keeps the humeral head fixed on the shoulder pelvis and prevents the strong contraction of the deltoid muscle from causing direct impact of the humeral head with the acromion or rostro-capital arch. The supraspinatus acts as an overhead stabilizer for the humeral head, the infraspinatus and the teres minor act as posterior stabilizers and externally rotate the humerus, while the subscapularis has the role of internally rotating the humerus. The supraspinatus is the most important of the rotator cuff muscles and is the most prone to injury. Another role of the rotator cuff is to maintain a so-called confined joint cavity that helps maintain synovial fluid to nourish the articular cartilage and prevent secondary osteoarthritis.
The concept of rotator cuff gap tears was first introduced by Nobuhara, who believed that the main clinical symptom was shoulder pain during shoulder supination and a feeling of instability in the shoulder joint. Anatomically, the rotator cuff gap is the gap between the supraspinatus tendon and the subscapularis tendon, which is a triangle-like structure in the coronal plane. The medial side of the triangle is the root of the rostral process, and its upper and lower sides are formed by the supraspinatus and subscapularis tendons, respectively, ending laterally at the greater and lesser humeral tuberosities and covering the long head of the biceps tendon in the intertubular sulcus. The rotator cuff gap is the structure bridging the supraspinatus tendon and the subscapularis tendon, and is actually part of the entire rotator cuff structure, and is the weakest part of the structure, limiting the inferior displacement of the humeral head and external rotation of the shoulder joint. Once injury occurs, it will lead to a weakening of the combined action of the supraspinatus and subscapularis muscles in the process of upper arm abduction, a decrease in the strength of the humeral head fixed on the shoulder glenoid, resulting in a relaxation of the glenohumeral joint and a decrease in the stability of the shoulder joint [1].
II. Etiology-pathogenesis.
There are many factors that contribute to rotator cuff injury, including trauma, glenohumeral instability, shoulder-thoracic joint dysfunction, congenital or developmental malformations and degenerative changes. Among them, the degeneration theory and the impingement theory are the best known.
(i) Degenerative theory.
Lindblom and Palmer studied the rotator cuff by microangiography and found that there is an obvious lack of vascular zone about 1 cm from the stop of the supraspinatus muscle, which is called the “critical zone” by Codman and Moseley. This zone is the junction of the branches of the suprascapular and infrascapular arteries from the muscle belly and the branches of the anterior rotator humeral artery from the greater tuberosity. Before the degeneration of the supraspinatus tendon, there is a significant ischemia in the lack of vascularity. This lack of blood supply causes local ischemia in the tendon and is an intrinsic factor in rotator cuff degeneration and tearing. Since then, some scholars have concluded that the degeneration of the supraspinatus hypovascular zone increases with age, and the myofibrillar tissue becomes necrotic and ruptures, and can be significantly ruptured by minor trauma, which is the degenerative trauma theory. It has been found that the dominant hand side is prone to rotator cuff tears, indicating that excessive wear and tear is a major factor causing rotator cuff injury. Although trauma is an external factor causing rotator cuff tears, for non-degenerative rotator cuffs, however, trauma generally causes acute massive tears or large nodal avulsion fractures, and only for degenerative rotator cuffs can trauma cause partial or complete rotator cuff fractures.
(ii) The impingement theory.
The impingement theory was proposed by Neer in 1972. The rotator cuff tendon between the rostral arch and the greater tuberosity of the humeral head is prone to congestion, edema, degeneration, and even rupture due to collision with the rostral arch when the shoulder is abducted and lifted due to hypertrophy of the rotator cuff tendon, subacromial and acromioclavicular joint degeneration or osteophyte formation, low acromion, and hook deformity below the anterior acromion. Kim [2] examined 376 patients with rotator cuff injuries and found that 74% of them had impingement of the acromion, further confirming Neer’s impingement theory. In these specimens, 73% of the rotator cuff injuries were hook-shaped, which led to the conclusion that the shape of the rotator cuff was closely related to the shoulder impingement sign. This autopsy finding was also supported by the X-ray examination of 200 cases of the shoulder joint.
Ozaki et al. found that many rotator crest lesions such as trabecular disorders, osteosclerosis, osteochondral atrophy and cystic changes occurred in the bursal surface of the rotator cuff. This was not the case for partial rotator cuff tears below the rotator cuff, i.e., on the articular side. Therefore, it is speculated that the subacromial bony changes are secondary to rotator cuff injury, rather than due to subacromial bony degeneration causing rotator cuff injury. Other authors have correlated impingement syndrome and rotator cuff tears and found that rotator cuff tears increased with age, whereas subacromial osteochondral changes did not correlate with age. Thus, it was hypothesized that impingement syndrome is not the main cause of rotator cuff tears, and Harvie [3] et al. recently proposed that genetic factors play an important role in total rotator cuff tears through a controlled study of twin siblings versus the general population.
It is now believed that rotator cuff tears are actually the result of a combination of intrinsic and extrinsic factors, with intrinsic factors including the lack of vascular zone of the rotator cuff tendon and the specific location and function of the supraspinatus muscle, and extrinsic factors including repeated use of the shoulder joint, subacromial impingement and different degrees of shoulder trauma.
III. Clinical manifestations and signs.
1. Shoulder joint pain is an early symptom of rotator cuff rupture: the most typical pain is nocturnal pain in the neck and shoulder area and pain from “over-the-top” activities (when the affected limb is raised above the top of one’s head). In the presence of chronic subacromial bursitis, the pain is persistent and intractable. Sometimes there is radiating pain to the neck and upper extremities, and the pain is aggravated by lying on the affected side, which seriously affects sleep and is very painful for the patient. Pain becomes the main reason for patients to visit the clinic and an important parameter to evaluate the effectiveness of treatment.
2. Weakness of the shoulder joint, atrophy of the supraspinatus, infraspinatus and deltoid muscles. Depending on the site of rotator cuff injury, shoulder joint weakness can be manifested as weakness in abduction, weakness in supination or weakness in posterior extension, respectively. Due to the pain and weakness, the active activities of the shoulder joint are limited and the shoulder joint cannot be lifted and abducted, which affects the function of the shoulder joint, but the passive range of motion of the shoulder joint is usually not significantly limited.
3. Pressure pain in the gap between the anterior lower part of the acromion and the greater tuberosity. When the arm is lifted or rotated, a popping sound may be felt or a gravelly sound may be palpated. The distinctive gravelly sound is usually seen in the third stage of impingement sign, especially in complete rotator cuff tears.
4, Positive pain arc sign, the affected extremity is raised 600-1200 when the rotator cuff is subjected to the maximum stress and obvious pain in front of the shoulder.
5. Positive hanging arm test. Some patients cannot lift actively or cannot hold the upper limb after lifting due to pain. 6. Impact test: pain occurs when the humeral tuberosity impacts with the acromion.
IV. Imaging diagnosis
(a) X-ray examination has no direct diagnostic value for rotator cuff injury, especially for acute tears or early lesions, but it has reference value for the diagnosis of subacromial impingement when the following X-ray signs are present.
(1) A hooked or curved subacromial peak.
(2) Dense or bony subacromial and greater humeral tuberosity formation.
(3) Decalcification, erosion, resorption or osteomalacia of the anterior acromion or acromioclavicular joint or greater tuberosity of the humerus.
(4) rounding of the greater tuberosity of the humerus, loss of the boundary between the articular surface of the humeral head and the greater tuberosity, and deformation of the humeral head.
(5) The distance between the acromion and the humeral head is reduced.
The normal acromion-humeral head distance ranges from 1 to 1.5 cm, less than 1.0 cm is considered narrow, and less than 0.5 cm suggests an extensive rotator cuff tear. Conventional radiographs show humeral head displacement and humeral tuberosity deformity in rotator cuff injury, with a positive rate of 78% and a specificity of 98%, so it is important to measure the acromion-humeral head distance.
(b) Arthrography has been used since the 1930s and is the traditional imaging method to diagnose rotator cuff tears. Arthrographic methods include single contrast contrast imaging and double contrast imaging, which is the principle of using the humeral mons arthrographic cavity contrast agent to spill into the subacromial bursa or fill the biceps tendon sheath through the ruptured rotator cuff for diagnosis, and can make diagnosis of full-thickness tears, partial tears of the rotator cuff articular surface, rotator cuff gap splitting and frozen shoulder, especially for the diagnosis of full-layer tears with high accuracy. Different authors have reported an accuracy rate of 90-100%. However, shoulder arthrography is an invasive test that requires fluoroscopic X-ray guidance for puncture into the joint cavity, which is not only radiologically harmful but also prone to misdiagnosis due to technical factors of the puncturer. Kelloran et al. have shown that uneven distribution of contrast in the joint cavity, projection of the biceps tendon sheath to the lateral aspect of the greater tuberosity in external rotation, and injection of contrast into the subacromial bursa can all lead to misdiagnosis. In patients with partial rotator cuff tears, the accuracy of shoulder arthrography is poor.
(c) Ultrasound diagnosis of rotator cuff tears has been used in clinical practice since the early 1980s. It has the advantages of non-invasive, dynamic observation, repeatability, high accuracy, ability to detect tears of rotator cuff tendons other than supraspinatus; convenient operation, time saving, low cost; ability to make diagnosis of biceps longus tendon disorders at the same time; unique value for postoperative follow-up of rotator cuff tears, etc., and high accuracy of diagnosis, as reported abroad The accuracy rate is 90%, and the sensitivity of ultrasound diagnosis of rotator cuff tears is 75% and the specificity is 92.3%. Therefore, it is valued by clinical workers, and many scholars are now happy to accept it, especially in epidemiological investigation and postoperative follow-up observation, which has unique value. However, when applying ultrasound to diagnose rotator cuff injury, the operator must be fully familiar with the pathological and anatomical basis of the rotator cuff in order to make a reasonable description of the images, the diagnostic criteria are not easy to grasp, and the diagnostic accuracy is highly dependent on individual operating techniques and experience. According to Brandt, there are 7 ultrasound diagnostic criteria for rotator cuff tears: 1 interrupted echogenicity in the rotator cuff; 2 central strong echogenic zone; 3 no rotator cuff echo; 4 strong echogenic points in the rotator cuff; 5 thinning of the local echogenic area; 6 flat laminar echo; 7 thin hypoechoic shadow.
(d) MRI examination is a more commonly used clinical method to diagnose rotator cuff injury. It is completely non-invasive, has high soft tissue resolution, and can be multi-planar imaging, which can more intuitively observe the rotator cuff tendon and its injury, so its application prospect is significantly better than shoulder arthrography. In particular, conventional MRI is superior to shoulder arthrography for the diagnosis of partial rotator cuff tears because the presence of partial tears in the bursal side and tendon can be determined by changes in rotator cuff morphology and signal. The accuracy of conventional MRI in diagnosing rotator cuff tears has been inconsistently reported. o Evancho et al. reported that the sensitivity of conventional MRI for the diagnosis of total rotator cuff tears was 80%, whereas Singson et al. reported 100%. o Iannotti et al. classified rotator cuff injuries according to their MRI pathological changes as.
(1) Tendonitis: increased homogeneity of tendon signal intensity without morphologic changes and intact subacromial and subdeltoid bursa fatty layer.
(2) Incomplete rupture: limited increase in tendon signal intensity with morphologic changes, showing discontinuity of the subacromial and subdeltoid bursal fat layers.
(3) Complete rupture: Significant increase in tendon signal intensity and significant morphological abnormalities, such as interruption of tendon continuity, retraction of the tendon muscle belly junction, or significant muscle atrophy, increased signal intensity of the muscle, and interruption or loss of the subacromial deltoid subacromial bursa fatty layer continuity.
(e) MRI shoulder arthrography is a new imaging method to diagnose rotator cuff injury in recent years. A comparative study of imaging methods for the diagnosis of rotator cuff injury concluded that MRI rotator cavity imaging has high sensitivity, specificity and accuracy for the diagnosis of rotator cuff tears or total rotator cuff tears, and can be the preferred method for the diagnosis of rotator cuff lesions. Combining the features of shoulder arthrography and conventional MRI scans, MRI shoulder arthrography can both visualize the morphology and signal of rotator cuff tendons and evaluate rotator cuff injury more accurately. According to the literature, the accuracy of MRI shoulder arthrography in diagnosing rotator cuff tears can reach 100%.
V. Treatment
(A) Non-surgical treatment
Non-surgical treatment of rotator cuff injury includes rest, non-hormonal anti-inflammatory drug application, physical therapy, local closure, aspiration of calcified sediment, various exercises to restore muscle strength and comprehensive rehabilitation methods. Most scholars believe that non-surgical treatment is appropriate for patients with short duration of disease (within 3 months), small tears, Neer stage I or older patients with low functional requirements of the shoulder. Due to the wide variation in case selection, evaluation criteria and quality of non-operative treatment application, the excellent rates of non-operative treatment reported in the literature range from 33% to 82%. Goldberg [5] reported on the conservative treatment of 46 patients with full-thickness rotator cuff injuries in which 59% of the patients showed improvement in their symptoms.Bokor et al. performed comprehensive nonoperative treatment in 53 cases of full-thickness rotator cuff tears and achieved a pain relief rate of 77%, which increased with time, with 67% of patients experiencing pain relief at 6 years, while at 9-year follow-up Bartolozzi et al. conducted a multifactorial analysis of the follow-up data of 136 patients with rotator cuff injuries treated conservatively and came to a similar conclusion: the effect of non-surgical treatment was closely related to the length of follow-up, with the longer the time, the better the effect, and found that poor outcome was associated with three factors: rotator cuff tear >1 cm, persistence of symptoms >1 year before treatment, and significant functional decline were closely related.
(ii) Surgical treatment
It has been 100 years since Muller (1898) first reported the use of surgery to repair rotator cuff tears. With the continuous improvement of technology and the introduction of arthroscopic techniques, there are now a wide range of invasive treatments for rotator cuff injuries. Anatomically speaking, the rotator cuff plays a role in the three-dimensional movement of the shoulder joint. In the coronal plane, the deltoid and the lower part of the rotator cuff (infraspinatus, teres minor, subacromialis) are a force couple; in the horizontal plane, there is another force couple between the anterior part of the rotator cuff (subacromialis) and the posterior part (infraspinatus, teres minor). The purpose of rotator cuff tear repair is to rebalance these two force couples and restore stability to the shoulder joint, not just to repair the tear. However, due to the variety of pathological changes in rotator cuff injuries, the overall efficiency reported ranges from 70% to 95% depending on the case selected, the surgical approach and the evaluation criteria. Surgical treatment of rotator cuff injuries can be divided into open surgery and arthroscopic surgery.
Open surgical treatment.
McLuohling repair method This method involves fixing the tendon to the bone at the anatomic neck anteriorly above the greater humeral tuberosity or burying the proximal rotator cuff stump into the bone groove at the anatomic neck and fixing it, and is suitable for patients with very few distal stumps or in whom a direct anastomosis is no longer possible. Neer (1972) concluded that rotator cuff injuries are closely related to impingement of the rotator cuff and therefore acromioplasty should be performed at the same time as rotator cuff repair. The acromioplasty consists of excision of the rostral shoulder ligament, thickening of the subacromial bursa, and wedge excision of the anterior inferior part of the acromion until the arm is free of impingement during supination and abduction. Fokter [6] used open surgery to treat 51 patients with total rotator cuff injuries with a mean follow-up of 4 years and a satisfaction rate of 88.2%. The treatment outcome was considered to be significantly related to the size of the tear and the length of surgical treatment after the injury, independent of the modality of surgery, the mode of postoperative rehabilitation and age. The combined application of subacromial decompression and rotator cuff repair acromioplasty in open surgery is the most commonly used method to treat rotator cuff injuries. For patients with huge tears that cannot be repaired by conventional methods, many scholars have applied muscle transposition to obtain better results. karas et al. applied subscapularis transposition posteriorly and superiorly in 20 cases of huge tears (> 5 cm) to treat large supraspinatus tears with muscle atrophy. 85% of the patients were satisfied with the results, but two cases had loss of shoulder elevation and nine cases felt weakness and discomfort during prolonged, repetitive overhead The results indicated that subscapularis transposition is effective in the treatment of large rotator cuff defects, but caution should be exercised in patients requiring excessive supraspinatus horizontal motion. In addition, a procedure like Debeyre’s supraspinatus nudge is performed to repair the defect by peeling off part of the attachment point of its supraspinatus fossa and nudging the muscle outward while preserving the blood supply of the supraspinatus. It is mainly used in patients with large supraspinatus tendon defects.
(iii) Advances in arthroscopic techniques have provided new treatment methods for rotator cuff injuries. Under arthroscopic surveillance, the type of tear can be diagnosed and evaluated, and the injury can also be treated. The structures involved can be clearly seen, making the procedure appear safer than ever before and avoiding the potentially dangerous complications associated with open surgery, especially for triceps injuries. Since the early 1990s, many scholars have performed arthroscopic treatment of rotator cuff injuries, with reported excellent rates of 80%-92% [7]. There are three approaches to arthroscopic surgery for rotator cuff injuries, namely subacromial decompression plication and rotator cuff repair; rotator cuff repair with debridement of the shoulder lesion and small incision assistance; and arthroscopic debridement of the shoulder alone.
Wolf applied arthroscopic treatment of rotator cuff injuries followed up for 4-10 years with a satisfaction rate of 94%.Severud [9] compared the efficacy of arthroscopic treatment of rotator cuff injuries with that of small incisions and found that there was no significant difference in the long-term efficacy of the two and that the surgical efficacy was independent of the surgical method and more dependent on the type of injury, whereas the arthroscopic group had a significant difference in There was a lower incidence of shoulder stiffness at 6-12 weeks and better range of motion was achieved. Hata [10] compared the use of a small incision with conventional open surgery for rotator cuff injuries; the small incision approach did not lead to postoperative deltoid atrophy, and at 3-month postoperative follow-up, the shoulder scores were significantly higher than in the conventional open group, allowing for earlier recovery. Massoud [11] performed arthroscopic acromioplasty and debridement for 114 chronic small and medium rotator cuff injuries with a satisfactory outcome in 74.6% of patients, with a significant difference of 59.3% and 87.5% in patients under 60 years of age and over 60 years of age, respectively.
Early arthroscopic rotator cuff repair mostly used single-row rivet suture fixation, which gradually revealed some defects over time.Apreleva [12] et al. recently showed that the attachment of the rotator cuff at the humerus is a complex three-dimensional structure, and the single-row reconstruction technique is not able to completely reconstruct the normal rotator cuff because the rivet fixation is point contact. The single-row rivet suture reconstruction of rotator cuff injuries can reconstruct only 67% of the area, whereas the conventional open penetrating suture closure of the rotator cuff can reconstruct 85% of the area of the rotator cuff stop, thus suggesting that the increased reconstructed area can promote healing and enhance the strength of the repaired tendon.Ian[13] proposed a double-row reconstruction technique for rotator cuff repair. The double-row reconstruction technique fixes the rotator cuff stump in two rows, the inner row is fixed to the humeral head near the outer edge of the articular surface, and the outer row is fixed to the outer side of the bone bed at the inner edge of the trap of the greater tuberosity. Double-row reconstruction has increased fixation points due to the addition of a second row of fixation, which increases the initial strength of the reconstructed tissue, reduces the load carried by each rivet, and improves the mechanical strength and function of the repaired rotator cuff, allowing it to heal better at the anatomic point. De Beer [14] et al. treated 58 patients with rotator cuff injuries using a modified double-row reconstruction method with an average follow-up of 15 months and an excellent rate of 90%, and more importantly, ultrasound showed that 89% of patients had an intact rotator cuff at postoperative follow-up. This may indicate that the double-row reconstruction technique can reduce postoperative rotator cuff retears and improve postoperative outcomes. This method consists of two suture rivets fixed independently of each other, and then the two rivets are connected by a suture loop so that the load is distributed over the two rivets, which reduces the failure rate of fixation. It has similar strength and fewer sutures through the rotator cuff compared to other double-row fixation methods and is simple.
The treatment of massive rotator cuff tears has been controversial since and the management of this condition has included conservative treatment, arthroscopic debridement and or biceps tendon resection, partial repair and tendon transposition. It was previously thought that rotator cuff injuries of 10-30 mm could be operated on arthroscopically, and large and massive rotator cuff tears should be repaired openly due to supraspinatus tendon retraction, adhesions, and bursal fatigue, with open surgery being preferable to arthroscopic surgery for large and massive tears. However, with the development of arthroscopic techniques, these views have changed, and Lo and Burkhart [17] initially reported the use of arthroscopy for repair of massive rotator cuff injuries. The procedure consisted of an anterior dissection of the rostro-humeral ligament and a posterior dissection of the supraspinatus muscle to release the supraspinatus tendon. Significant improvement in pain scores was found at 18 months of follow-up. Bennett [18] reported an arthroscopic repair of a giant rotator cuff injury using the “marginal convergence method” and “gap shift method” with a 95% patient satisfaction rate. Jones and Savoie [19] used the same method to repair a giant rotator cuff injury and achieved a satisfaction rate of 88%. With the maturation of arthroscopic techniques, it is foreseeable that it will be the future direction of rotator cuff injury treatment, as it not only has a wide field of view and can clarify the etiology comprehensively, but also has a small trauma and fast postoperative recovery.