Abstract
The pathophysiology of partial-thickness rotator cuff tears is variable. A majority are articular-sided tears, but bursal and intrinsic tears also commonly occur. Because partial-thickness tears are an intermediate condition between impingement and full-thickness tears, the clinical presentation can mimic that of either condition. Initial management is conservative. Surgical intervention involves débridement, in situ repair, or completion of the tear with repair. The surgical intervention is highly dependent on patient presentation and the surgeon’s clinical assessment as well as arthroscopic assessment.
Keywords
partial thickness, rotator cuff tear, débridement
Partial-thickness rotator cuff tears constitute an interesting and difficult group of shoulder lesions. In large part, the difficulty stems from terminology: we use the phrase partial-thickness rotator cuff tear to describe the anatomic end result of several different pathophysiologic pathways. If we consider rotator cuff disease to be an intrinsic tendinopathy and part of the natural aging process, partial-thickness rotator cuff tears represent a transition from tendinosis to tendon rupture. If we view rotator cuff changes as lesions caused by extrinsic compression forces, partial-thickness rotator cuff tears are the result of more compression than that which results in tendinosis and less compression than that which results in full-thickness tears. If we accept the hypothesis that partial-thickness rotator cuff tears are the result of compression between the humeral head and the acromion, do these compression forces cause partial-thickness tears in patients with internal impingement? Perhaps the rotator cuff tears we see in younger patients are due to excessive eccentric muscular contraction. Because it appears that the same anatomic lesion (partial-thickness rotator cuff tear) can be caused by different mechanisms, the surgeon must determine the cause and treat the tear accordingly.
Literature Review
In a group of throwing athletes (average age 22 years) treated with arthroscopic débridement without decompression, Andrews reported 85% good or excellent results. Snyder found 47 partial tears in a group of 600 patients undergoing shoulder arthroscopy, and advocated débridement without decompression if the tear was confined to the articular surface; arthroscopic subacromial decompression was added if the tear extended to both the articular and the bursal surfaces. In our series of partial-thickness rotator cuff tears, we reported that outlet impingement tears of less than 50% of the tendon thickness respond well to arthroscopic subacromial decompression, whereas tears greater than 50% require repair. Partial-thickness rotator cuff tears in patients with glenohumeral instability require instability correction and then rotator cuff repair or arthroscopic subacromial decompression, depending on the extent of the individual lesions.
Diagnosis
Patients with partial-thickness rotator cuff tears may present with signs and symptoms typical of rotator cuff disease. When the shoulder is elevated through the painful arc during activities of daily living, pain is localized deep to the lateral deltoid muscle (subdeltoid pain). Night pain may also occur. Examination demonstrates normal active and passive range of motion with positive impingement signs. Subacromial anesthetic injection relieves the pain for bursal-sided tears. A critical feature of the examination is the amount of pain and weakness observed when resisted manual muscle testing is performed. Significant pain and weakness with resisted external rotation or elevation are relative indications for early operative intervention. Plain radiographs appear similar to those of patients with impingement syndrome or full-thickness tears. Most commonly, the diagnosis is made with magnetic resonance imaging (MRI). The use of intra-articular gadolinium increases the sensitivity of MRI (MRA) in patients with partial-thickness rotator cuff tears, particularly in those who must have open MRI. Diagnostic ultrasonography has also been very helpful, especially in cases of intrasubstance partial-thickness rotator cuff tears ( Figs. 11.1–11.3 ). Often, a partial-thickness tear is found at the time of arthroscopic examination of the glenohumeral joint.
Nonoperative Treatment
In the absence of significant subacromial space compromise from a type 3 acromion, nonoperative treatment is indicated and is identical to that prescribed for patients with impingement syndrome. Patients are instructed to avoid painful positions and activities. Nonsteroidal anti-inflammatory medication may relieve pain at night. If there is a loss of passive motion, appropriate stretching exercises are indicated. Home exercises to strengthen the scapular-stabilizing muscles may help.
Operative Technique
Operative Findings
The findings in patients with partial-thickness rotator cuff tears are related to both the severity of the tear and the presence of other lesions within the joint. Most tears are located on the articular surface; approximately 75% of these are in the supraspinatus tendon, 20% are in the infraspinatus tendon, and 5% are in the teres minor tendon. The depth or severity of the tendon tear is grade 1 (less than one-fourth of the tendon thickness) in 45% of cases, grade 2 (less than one-half the tendon thickness) in 40%, and grade 3 (more than one-half the tendon thickness) in 15% ( Figs. 11.4–11.7 ).
Chondral defects on the articular surface of the humeral head or the glenoid, or the presence of labral tears, is suggestive of glenohumeral instability and should prompt the surgeon to consider whether the partial-thickness rotator cuff tear coexists with other clinical diagnoses.
Intraoperative Decision Making
Three options are available for the arthroscopic treatment of partial-thickness rotator cuff tears: (1) débridement of the partial-thickness tear alone, (2) débridement of the tear with subacromial decompression, and (3) arthroscopic repair of the partial-thickness tear combined with subacromial decompression. This last option can include in situ repair of the tear or completion of the tear followed by repair.
Four factors are considered when treating patients with partial-thickness rotator cuff tears: (1) tear size and depth, (2) the patient’s desired activity level, (3) bone structure, and (4) the cause of the tear. No one factor by itself determines treatment; the clinician must analyze the effects of all these factors to decide on the appropriate management. The following guidelines can be helpful in the treatment of these troublesome lesions.
The most critical decision is whether the tear can be treated by arthroscopic decompression alone or whether this must be accompanied by tendon repair. There is no general agreement on how the tear’s dimensions (length and width) should influence surgical decision making. Most authors recommend surgical repair if the tear extends to a depth of 50% or more of the tendon substance. If, while viewing from within the glenohumeral joint, the synovial tendon surface inserts at the level of the articular cartilage, but there is a partial tear more proximally, the area of injury can be débrided until normal tendon fibers are identified. The known dimensions of the shaver can be used to estimate the depth of the lesion. The normal tendon thickness proximal to the insertion can be assumed to be 6 to 8 mm to estimate the tear depth. This applies to either the supraspinatus or the infraspinatus. If the supraspinatus tendon does not insert at the level of articular cartilage and there is exposed bone, Nottage’s guidelines can be used to estimate a 10% tear for every millimeter of exposed bone. For example, 5 mm or more of exposed bone means a tear greater than 50%, in which the lesion is repaired. This method works only for the supraspinatus because the infraspinatus does not insert at the level of the articular cartilage, and an area of exposed bone between the tendon insertion and the hyaline cartilage of the humeral head is normal.
Sedentary patients with partial tears are more likely to do well with decompression alone; active patients are more likely to benefit from tendon repair. Patients with structural bone abnormalities (e.g., hooked acromion, inferior acromioclavicular joint osteophytes, anterior acromial spurs) are more likely to benefit from decompression. Patients with glenohumeral instability require correction of the lesions responsible for excessive translation. These factors are then considered in light of patient preference. Some patients prefer tendon repair if it can more reliably lead to a cure; others may choose débridement or decompression because that approach involves fewer lifestyle inconveniences. At each end of the decision-making spectrum, treatment is less controversial: active individuals with normal bone shape and tears involving more than 50% of the tendon thickness are best treated with surgical repair, whereas sedentary patients with acromial spurring and tears involving less than 50% of the tendon thickness can be treated successfully with arthroscopic decompression alone. For those in the middle, treatment is less well defined. Surgeon experience and patient preference, rather than scientific data, appear to dictate the treatment approach.
The vast majority of partial-thickness tears appear on the articular surface of the rotator cuff tendon and are not visible during the inspection of the bursal surface that occurs during an open procedure. Therefore, it seems that the incidence of partial-thickness tears has been underestimated in the literature dealing with open shoulder surgery. Inspection of the cuff’s articular surface is better performed arthroscopically because the entire cuff can be easily evaluated and the location, size, and depth of the tear can be appreciated. The tear can be marked with a suture so that the surgeon can locate the lesion during subsequent subacromial inspection.
Management of Partial-Thickness Tears ( )
When an articular surface partial-thickness rotator cuff tear is noted during the diagnostic examination, the surgeon should establish an anterior portal and introduce a motorized shaver. Remember that the synovial lining, not the tendon, is visualized during this initial inspection. Using the shaver, perform a limited débridement to clearly establish the length, width, and depth of the tear. Some surgeons believe that a partial-thickness rotator cuff tear is always an intrinsic tendinopathy and that débridement stimulates a healing response. If, based on the criteria discussed earlier, a repair is felt to be necessary, the shaver may be used to complete the tear until the shaver enters the subacromial space. Alternatively, and more commonly, a débridement is done, and, while viewing from the glenohumeral joint, a spinal needle is percutaneously inserted into the area of the partial tear. Generally, the needle is inserted near the anterolateral corner of the acromion because most articular surface partial-thickness rotator cuff tears are located in the anterior portion of the supraspinatus. If the tear is more posterior, the needle insertion point must be more posterior. A mental note is made of how far the tear extends anteriorly, posteriorly, medially, and laterally from the needle. Either the needle can be left in or an absorbable monofilament suture can be left in place to mark the site of the tear ( Figs. 11.8–11.11 ).
