Cystic changes of the humeral head on MR imaging. Relation to age and cuff-tears

An Injectable Calcium Phosphate Bone Graft Substitute Improves the Pullout Strength of Various Suture Anchor Designs in an Osteoporotic Bone Model

Purpose

To compare various suture anchor designs with and without calcium phosphate (CaP) augmentation in an osteoporotic foam block model and decorticated proximal humerus cadaveric model.

Methods

This was a controlled biomechanical study, consisting of 2 parts: (1) an osteoporotic foam block model (0.12 g/cc; n = 42) and (2) a matched pair cadaveric humeral model (n = 24). Suture anchors selected were an all-suture anchor, PEEK (polyether ether ketone)-threaded anchor, and a biocomposite-threaded anchor. For each study arm, one half the samples were first filled with injectable CaP and the other half were not augmented with CaP. For the cadaveric portion, the PEEK- and biocomposite-threaded anchors were assessed. Biomechanical testing consisted of a stepwise, increasing load protocol for a total of 40 cycles, followed by ramp to failure.

Results

For the foam block model, the average load to failure for anchors with CaP was significantly greater when compared with anchor fixation augmented without CaP; the all-suture anchor was 135.2 ± 20.2 N versus 83.3 ± 10.3 N (P = .0006); PEEK was 131 ± 34.3 N versus 58.5 ± 16.8 N (P = .001); and biocomposite was 182.2 ± 64.2 N versus 80.8 ± 17.4 N (P = .004). For the cadaveric model, the average load to failure for anchors augmented with CaP was again greater than anchor fixation without CaP; PEEK anchors went from 41.1 ± 21.1 N to 193.6 ± 63.9 N (P = .0034) and biocomposite anchors went from 70.9 ± 26.6 N to 143.2 ± 28.9 N (P = .004).

Conclusions

Augmenting various suture anchors with CaP has shown to significantly increase pull-out strength and stiffness in an osteoporotic foam block and time zero cadaveric bone model.

Clinical Relevance

Rotator cuff tears are common in the elderly patients, in whom poor bone quality jeopardizes treatment success. Exploring methods that increase the strength of fixation in osteoporotic bone to improve outcomes in this patient population is important.

Cystic lesions of the humeral head on magnetic resonance imaging: a pictorial review

Cystic lesions of the humeral head are commonly encountered on routine shoulder magnetic resonance imaging (MRI). Differential diagnoses include degenerative lesions, calcific tendinitis with osseous involvement, perianchor cysts, abscesses and less often, tumours. Degenerative lesions, including subcortical and subchondral cysts, are the most commonly encountered. These may be associated with rotator cuff disease and degenerative joint diseases or considered part of ageing depending on the location of the cystic lesions. For instance, cysts of the bare area of the humeral head are considered benign age-related entities, whereas cysts of the greater or lesser tuberosity may herald rotator cuff disease. Infectious lesions, particularly osteomyelitis and intraosseous (Brodie’s) abscesses, are intramedullary in location and should be suspected in the context of clinical features such as fever and radiological features such as the penumbra sign. Perianchor cysts are postoperative lesions associated with the use of suture anchors in surgeries such as rotator cuff tear repairs. They generally self-resolve over 18 to 24 months. On MRI, the distribution, morphology, and signal characteristics can help point towards a specific diagnosis. The patient’s demographic, clinical presentation, and past surgical history can be discriminatory. Knowledge of different cystic lesions in the humeral head and underlying aetiology can be useful in helping the radiologist develop a more thorough search pattern for associated conditions. Determining the underlying cause of cysts can have important implications on management, such as when differentiating perianchor cysts from infection. This pictorial review outlines the differential diagnoses of humeral head cysts on MRI and provides a diagnostic approach for the radiologist.

Cement augmentation of suture anchors in the proximal humerus during rotator cuff repair improves pullout strength: a systematic review

IMPORTANCE

Rotator cuff pathology is a growing concern in the ageing population. If cement augmentation of suture anchors improves pullout strength, its application can potentially be applied in cases of poor bone quality to prevent anchor failure.

OBJECTIVE

To evaluate the biomechanical benefits and fixation strength of cement-augmented versus non-augmented suture anchors in the proximal humerus during rotator cuff repair (RCR).

EVIDENCE REVIEW

A systematic review of PubMed, Embase and Cochrane Library was performed to identify all published articles reporting on biomechanical analysis of suture anchors in the shoulder in a cadaveric model. Inclusion criteria required fresh-frozen specimens, placement in the footprint of the proximal humerus, and comparative assessment of fixation constructs with or without polymethylmethacrylate (PMMA) or bioabsorbable composite cement augmentation. Biomechanical testing procedure, cement augmentation method and pullout force were assessed.

FINDINGS

After review of 105 abstracts, seven full manuscripts met inclusion criteria. Six of seven studies reported statistically significant differences in mean pullout force between augmented (three PMMAs, three composites, one PMMA vs composite) and non-augmented anchors. Of two studies evaluating cycles to failure, both found a significant increase in the augmented versus non-augmented anchors. Of two studies stratifying by anchor position, both investigations identified significant differences in mean pullout strength between augmented and non-augmented anchors at the posteromedial and anterolateral anchor positions.

CONCLUSIONS AND RELEVANCE

Cement augmentation of suture anchors in cadaveric humeri for RCR improves pullout strength regardless of cement type used or anchor position. Cement augmentation may provide a viable option for future clinical application.

LEVEL OF EVIDENCE

IV, systematic review.

Fibrosis in the rotator interval associated with articular vs. bursal side partial-thickness rotator cuff tears

Background

The pathogenesis of articular- and bursal-sided partial-thickness rotator cuff tears (PTRCTs) is considered to be different, and associated lesions with PTRCTs need to be examined.

Methods

The current study consisted of 76 shoulders of 73 patients (27 men, 46 women, 64.0 ± 8.3 years old) who underwent mini-open repair after conversion to full-thickness tears for either articular side (group A; n = 56) or bursal side (group B; n = 20) PTRCT with at least a 2-year follow-up. Clinical outcomes and their images were compared between the groups. Plain radiographs were used with the arm passively elevated in maximum elevation to assess restriction of glenohumeral motion.

Results

The retear rate was not significantly different between the groups. Both groups showed significant improvement in functional scores at the final follow-up. Patients in group A showed a higher incidence of preoperative fibrosis in the rotator interval (69.6% vs. 35.0%, respectively; P = .006) and a lower incidence of an acromial spur (7.1% vs. 35.0%, respectively; P = .008) compared with group B. Plain radiographs with arm elevation showed restriction of glenohumeral movement in 49 of 76 shoulders (64.5%) preoperatively, including 36 of the 46 shoulders with fibrosis and 13 of the other 30 shoulders.

Conclusion

Both articular- and bursal-sided PTRCTs showed significant functional improvements after surgery. The articular-sided tears had a lower incidence of an acromial spur, but had a higher incidence of fibrosis in the rotator interval, which led to a limitation in glenohumeral motion.

Arthroscopic Transosseous Repair of Rotator Cuff Tear and Greater Tuberosity Cysts

Purpose

To evaluate the short-term outcomes of rotator cuff repair in the presence of a greater tuberosity cyst (GTC) using a transosseous repair technique.

Methods

This study included patients who underwent arthroscopic rotator cuff tear repair with a transosseous technique and were evaluated clinically and by postoperative magnetic resonance imaging (MRI) after 1 year. The inclusion criteria were based on the results of preoperative MRI and were as follows: patients identified as having a repairable full-thickness rotator cuff tear associated with the presence of cystic changes at the tendon insertion site of the greater tuberosity, defined as a GTC involving the footprint area of the torn tendon (supraspinatus and/or infraspinatus tendons).

Results

We evaluated 25 patients. The mean preoperative and postoperative American Shoulder and Elbow Surgeons scores were 39.48 (P = .530) and 84.64 (P = .035), respectively; Constant shoulder scores, 38.96 (P < .005) and 80.28 (P = .425), respectively; and University of California–Los Angeles shoulder rating scale scores, 10.6 (P = .045) and 29.04 (P = .315), respectively. The GTC mapping system was easily adopted in all the MRI examinations independently from the quality of the images. The GTCs were mostly located in the superficial anterolateral section of the humeral head and in both the posterolateral sections (superficial and deep).

Conclusions

Arthroscopic transosseous rotator cuff repair led to significant mid-term improvement and satisfactory subjective outcomes with low complication and failure rates in this study. The GTC mapping system could be useful to evaluate GTCs and to aid surgeons in the choice of the best surgical technique.

Level of Evidence

Level IV, therapeutic case series.

Evaluation of arthroscopic rotator cuff repair results in patients with anterior greater tubercle cysts

PURPOSE

The purpose of this study was to investigate the clinical results of arthroscopic rotator cuff repair in patients with anterior greater tubercle cyst in magnetic resonance imaging (MRI).

METHODS

The cyst-present group comprised 38 patients with anterior greater tubercle cyst in MRI, and age- and sex-matched 30 patients without cyst in humeral head were included in the control group. The cystic group was divided into two groups, smaller than 5 mm (21 patients) and larger than 5 mm (17 patients), according to the cyst size. A total of three groups were created. In the evaluation of clinical outcomes, modified University of California at Los Angeles (UCLA) and the Western Ontario Rotator Cuff Index (WORC) were used. The visual analog scale (VAS) was used to assess pain. One-way analysis of variance was used to compare VAS, UCLA, and WORC scores among the groups.

RESULTS

There was a statistically significant difference in the clinical results of VAS, UCLA, and WORC among the cystic and noncystic groups in the anterior greater tubercle ( p < 0.05). There was also a statistically significant difference in the clinical results of UCLA, WORC, and VAS scores according to the cyst sizes in the anterior greater tubercle cyst group ( p < 0.05).

CONCLUSION

Anterior greater tubercle cysts have negative effects on rotator cuff repair results. If the anterior greater tubercle cyst size is greater than 5 mm, the negative effects of rotator cuff repair results are more pronounced. An understanding of anterior greater tubercle cysts has a critical importance for rotator cuff surgery planning.

Association between the location of tuberosity cysts and rotator cuff tears: A comparative study using radiograph and MRI

BACKGROUND

The association between tuberosity cysts and rotator cuff tears (RCTs) and the nature of the major contributing factors to tuberosity cyst formation continue to be controversial. The purpose of our study was to evaluate the strength of associations of RCT and various factors involved in the chronicity of RCT with tuberosity cysts, using magnetic resonance imaging (MRI) and radiographs.

METHODS

We reviewed consecutive patients with various disease entities between August 2004 and July 2013. After excluding unsuitable patients, this study involved 1007 shoulders of 906 consecutive patients. Each tuberosity cyst was categorized as an anterior greater tuberosity (GT), posterior GT, lesser tuberosity, and bare-area cyst. The odds ratios (ORs) and 95% confidence intervals (CIs) between the tuberosity cysts and various factors were evaluated by logistic regression analyses; p-value was set below 0.05.

RESULTS

Anterior GT cysts and posterior GT cysts on MRI or anterior GT cysts on radiographs were significantly associated with supraspinatus tendon (SST) tears ( p ≤ 0.019) and infraspinatus tendon (IST) tears ( p ≤ 0.004). Among the shoulder pathologies, RCTs only significantly associated with cyst formation (OR 4.23, 95% CI 3.17-5.65; p < 0.001). The retraction grade of Patte was significantly associated with anterior GT cyst (OR 3.65, 95% CI 2.42-5.48; p < 0.001).

CONCLUSION

Detecting an anterior GT cyst in a radiograph, even a low prevalence, in a patient with symptomatic shoulder indicates a need to consider RCT, especially of the SST, IST, and a high possibility of a retracted tear.

The value of radiographic markers in the diagnostic work-up of rotator cuff tears, an arthroscopic correlated study

OBJECTIVE

To evaluate the value of radiographs during the diagnostic work-up of rotator cuff tears, using arthroscopy as reference standard.

MATERIALS AND METHODS

This retrospective study included 236 shoulders of 236 patients. All radiographs were evaluated for inferior cortical acromial sclerosis, lateral acromial spur, superior migration of the humeral head, greater tubercle cysts, and subacromial space calcifications. Predictive value of these radiographic signs in predicting rotator cuff tears was determined with arthroscopy as reference standard.

RESULTS

According to arthroscopy, 131 shoulders were diagnosed with rotator cuff tears. Seventy-two out of 131 shoulders (55%) had inferior cortical acromial sclerosis, 37 (28%) lateral acromial spur, 21 (16%) superior migration of the humeral head, 7 (5%) greater tubercle cysts and 15 subacromial space calcifications (11%). Inferior cortical acromial sclerosis (P = 0.001), lateral spur (P = 0.001), superior migration (P = 0.002), and cysts (P = 0.03) were significantly and independently associated with rotator cuff tears, whereas subacromial calcifications (p = 0.21) was not. Inferior cortical acromial sclerosis, superior migration, lateral acromial spur, and cysts combined have a positive predictive value of 78%.

CONCLUSIONS

The combination of inferior cortical acromial sclerosis, lateral acromial spur, superior migration of the humeral head, and greater tubercle cysts has a high positive predictive value for the presence of full-thickness rotator cuff tears. In patients with a high suspicion for having a rotator cuff tear based on radiographic findings, MRI can be performed directly without the delay and costs caused by an additional ultrasound exam.

Osteolysis is observed around both bioabsorbable and nonabsorbable anchors on serial magnetic resonance images of patients undergoing arthroscopic rotator cuff repair

Objectives

The objective of this study was to evaluate the incidence of osteolysis around the bioabsorbable and nonabsorbable anchors using serial magnetic resonance imaging (MRI) and to determine the relationship between osteolysis and the retear rate after arthroscopic rotator cuff repair.

Methods

From July 2012 to July 2014, 50 patients [28 men and 22 women; mean age, 56.4 (range: 45–56) years] underwent arthroscopic rotator cuff repair for a medium-to large-size tear with double-row suture-bridge technique. The bioabsorbable anchors used in the medial row comprised hydroxyapatite-polylactic acid enantiomer, and the nonabsorbable anchors in the lateral row were polyetheretherketone (PEEK)-type anchors. All patients underwent MRI evaluation at 3, 6, and 12 months postoperatively to determine osteolysis and identify any retear.

Results

The incidences of osteolysis at 3, 6, and 12 months postoperatively were 1%, 4%, and 6% with nonabsorbable anchors and 13%, 29%, and 39% with bioabsorbable anchors, respectively. The incidences of osteolysis were significantly higher with the bioabsorbable anchors than with the nonabsorbable anchors (P < 0.005 for all three follow-ups). There was no significant difference between osteolysis and non-osteolysis groups regarding the retear rate or retear size (P = 0.189 and 0.069, respectively).

Conclusions

Osteolysis was common around bioabsorbable anchors used for arthroscopic rotator cuff repair, and it also occurred around the PEEK-type nonabsorbable anchors. The incidence of osteolysis of nonabsorbable anchors was significantly lower than that of bioabsorbable anchors. Osteolysis did not significantly affect rotator cuff retear after arthroscopic repair with either bioabsorbable or nonabsorbable anchors.

Level of evidence

Level III, Therapeutic Study.

Lesser tuberosity cysts and their relationship with subscapularis tears and subcoracoid impingement

BACKGROUND

We aimed to evaluate cysts in the lesser tuberosity of humeral head seen on magnetic resonance imaging (MRI) and their relationship with subcoracoid impingement and subscapularis tears evident on arthroscopic surgery videos. Our hypothesis was that the cysts would be more frequent with subscapularis tears and in the case of subcoracoid impingement.

METHODS

Patients who underwent shoulder arthroscopy between January 2010 and January 2016 were retrieved to evaluate subscapularis tears on surgery videos and lesser tuberosity cysts (LTC), coracohumeral distances (CHD) on both sagittal oblique and transverse sections of MRI retrospectively. There were 137 patients meeting the study criteria with subscapularis tear evident on surgery video and having preoperatively studied magnetic resonance images. All the tears were classified according to the Lafosse's system. The control group was constituted with 121 patients who underwent shoulder arthroscopy and were diagnosed with no subscapularis tear. Then, any statistically significant relationship between these parameters was investigated by the use of statistics software.

RESULTS

The mean age (57), gender distribution (female for 67.1%), and involved shoulder (right for 62.8%) rate of the groups were statistically similar. The existence rate of LTC was 55.5% and 19% for the study and control groups, respectively (P = .000). The study group was then evaluated in two groups regarding the existence of a cyst in the lesser tuberosity. There was no statistical difference between these two groups in terms of coracohumeral distances and tear type (P > .05). The study group was also divided into two depending on the transverse section CHD whether it was under 7 mm or not. There was still no statistical difference between these subgroups in terms of a cyst existence (P > .05). The supraspinatus tear rate and age distribution was also not differing in patients with and without LTC.

CONCLUSIONS

The LTCs were significantly associated with subscapularis tears, and could be used as an indicator in the interpretation of MRI scans. However, there was no relationship between the subcoracoid impingement and LTCs.

Dislocation of the Shoulder Joint - Radiographic Analysis of Osseous Abnormalities

Radiography remains pivotal to the workup of instability lesions of the shoulder, both in the acute as well as the chronic settings. The goal of radiography is to detect osseous abnormalities and locate them in order to determine the direction of instability. In antero-inferior instability, Hill-Sachs lesions are often visible at radiography and should not be confused with various differential diagnoses, which are usually more laterally located. Bankart lesions are more difficult to detect on conventional radiography, but there are less false positives than for Hill-Sachs lesions. The Garth view represents an excellent radiographic view to detect antero-inferior instability impaction fractures at both the humeral and glenoid sides. Accurate quantification of bony abnormalities and detection of lesions to the soft-tissue stabilizers of the shoulder however require advanced cross-sectional imaging techniques.

Locations of lesser tuberosity cysts and their association with subscapularis, supraspinatus, and long head of the biceps tendon disorders

BACKGROUND

Humeral head cysts are not uncommon in individuals with rotator cuff disorders. The cysts are usually considered an indicator of rotator cuff pathologies; however, they may have different meanings in different regions.

PURPOSE

To determine the frequency of cysts within and adjacent to the lesser tuberosity and the relationship between these cysts and subscapularis, supraspinatus, and long head of the biceps tendon (LHBT) disorders.

MATERIAL AND METHODS

We retrospectively reviewed 760 consecutive shoulder magnetic resonance imaging (MRI) examinations. Among these MRIs, we selected a group of patients with cysts located around the lesser tuberosity. The study population was also divided into two subgroups, patients with cysts within the lesser tuberosity and those with cysts adjacent to the lesser tuberosity. In addition to the number and size of cysts, the MRI appearance of the tendons was evaluated.

RESULTS

Eighty-one (10.7%) patients had cysts within and/or adjacent to the lesser tuberosity, 34 (42%) patients had cysts within the lesser tuberosity, and 47 (58%) patients had cysts adjacent to it. LHBT and subscapularis tendon disorders were significantly related to more than one cyst. In a univariate analysis, cysts within the lesser tuberosity were significantly associated with LHBT and subscapularis tendon disorders; however, multivariate analyses showed that only LHBT disorders were significantly associated with cysts within the lesser tuberosity.

CONCLUSION

Cysts within the lesser tuberosity were less common than cysts adjacent to it. LHBT and subscapularis tendon disorders were more frequently found in patients with more than one cyst within and/or adjacent to the lesser tuberosity. In addition, cysts within the lesser tuberosity were associated with LHBT disorders.

Intratendinous supraspinatus cyst as a cause of shoulder impingement

We report the case of a 29-year-old gentleman with shoulder impingement. An articular-sided intratendinous supraspinatus cyst was identified as the cause of his symptoms. Arthroscopic cyst debridement resulted in a good outcome at 1-year follow-up. Cysts around the shoulder are a well described pathological entity. They consist of different categories, including intraosseus cysts of the humeral head and glenoid, paralabral cysts and cysts associated with the acromioclavicular joint. Although paralabral cysts that lie intramuscularly or between the muscle bellies have frequently been reported, this is the first report of an intratendinous supraspinatus cyst with an intact rotator cuff. We describe the case, its management and the postsurgical outcome.

Posterior horn medial meniscal root tear: the prequel

OBJECTIVE

To determine whether subarticular marrow changes deep to the posterior horn medial meniscal root anchor might predict subsequent medial meniscal root tear.

MATERIALS AND METHODS

Fifteen patients with MR-diagnosed posterior horn medial meniscal root (PHMMR) tear and a knee MRI antecedent to the tear were identified at three imaging centers over a 7-year period. The pre- and post-tear MR images were evaluated for marrow signal changes deep to the root anchor, meniscal root signal intensity, medial compartment articular cartilage thinning, and meniscal body extrusion. Images of 29 age- and gender-matched individuals with two MRIs of the same knee were reviewed as a control group.

RESULTS

MRI in 11 of 15 (73%) cases with subsequent PHMMR tear demonstrated linear subcortical marrow edema deep to the meniscal root anchor on the antecedent MRI compared to only 1 of 29 (3%) non-tear controls (p < 0.0001). The abnormal signal resolved on post-tear MRI in all but two patients. Cyst-like changes deep to the PHMMR were present on initial MRI in three of 15 (23%) cases and three of 29 (10%) controls, persisting in all but one case on follow-up imaging. The PHMMR was gray on the initial MRI in seven of 15 (47%) of cases that developed tears compared to four of 29 (14%) controls (p < 0.0001). There was medial meniscal extrusion (MME) prior to tear in two of 15 (13%) patients and in ten of 15 (67%) patients after PHMMR failure. In the control group, MME was present in one (3%) and three (10%) of 29 subjects on the initial and follow-up MRIs, respectively. Articular cartilage loss was noted in two of 15 (15%) cases before tear and nine of 15 (69%) on follow-up imaging, as compared to one (3%) and four (14%) of 29 subjects in the control group.

CONCLUSIONS

Subcortical marrow edema deep to the PHMMR may result from abnormal stresses and thus be a harbinger of meniscal root failure. This hypothesis is supported by resolution of these marrow signal changes after root tear. Following tear, extrusion of the meniscal body results in increased stress on the medial weight-bearing surfaces often leading to articular cartilage loss; we observed this sequence in six of our 15 patients with PHMMR tears.

Cysts within and adjacent to the lesser tuberosity: correlation with shoulder arthroscopy

OBJECTIVE

The purpose of our study was to determine if cysts in and adjacent to the lesser tuberosity are associated with rotator cuff pathology found at arthroscopy.

MATERIALS AND METHODS

A retrospective review was undertaken of the magnetic resonance (MR) imaging of 286 consecutive arthroscopic procedures performed by a single orthopedic shoulder surgeon from February 2001 to June 2009. Images of the shoulders were reviewed by an experienced fellowship-trained musculoskeletal radiologist, reader 1, and a musculoskeletal fellow, reader 2, for the presence and location of lesser tuberosity cysts. Cysts were grouped by their location into those within the lesser tuberosity and those adjacent to the lesser tuberosity. Interreader agreement was calculated using kappa values.

RESULTS

A total of 26 patients (17 men, 9 women; age range 14–84 years; mean of 61 years) had cysts in or adjacent to the lesser tuberosity. For reader 1, patients with cysts located in the lesser tuberosity were found to be significantly older(p=00.03) and more likely to have subscapularis tendon tears(p=00.02) than patients with cysts located adjacent to the tuberosity. No significant difference in any category between patients with a cyst located in the lesser tuberosity and those adjacent to the tuberosity was identified for reader 2. Interreader agreement of imaging findings ranged from fair to near perfect agreement.

CONCLUSION

Cysts located in the lesser tuberosity at the insertion of the subscapularis tendon are suggestive of subscapularis tendon pathology and may occur in older individuals.

Cystic Changes at Supraspinatus and Infraspinatus Tendon Insertion Sites: Association with Age and Rotator Cuff Disorders in 238 Patients

PURPOSE

To retrospectively determine the frequency of posterior and anterior cystic abnormalities at rotator cuff insertion site on the greater tuberosity and to determine their relationship to patient age and rotator cuff disorders.

MATERIALS AND METHODS

Institutional review board approval was given; informed consent was waived. The study was HIPAA compliant. In 238 patients with rotator cuff diagnoses at surgery, preoperative magnetic resonance (MR) imaging studies were reviewed to localize osseous cystic changes as anterior (supraspinatus insertion site) or posterior (infraspinatus insertion site) on the greater tuberosity. If rotator cuff tear was present, tendon retraction and location of partial tear (articular or bursal surface) were recorded. Two radiologists reached conclusions by consensus. Locations of cysts were correlated to surgical cuff diagnoses: no tear, tendinopathy, partial-thickness tear, and complete tear. Prospective interpretations from original MR reports were compared with surgical results. Statistical analyses included one-way analysis of variance, chi(2), Fisher exact, and Student t tests, as well as logistic regression and receiver operating characteristic curve comparison.

RESULTS

There were 238 consecutive patients (150 men, 88 women; mean age, 43 years). Cysts were located at or near footprint of cuff tendon and demonstrated fluid or soft-tissue signal intensities. Posterior cysts occurred in 56.7% of shoulders and showed no statistical correlation to age or cuff diagnosis. Anterior cysts occurred in 22.7% of shoulders and were strongly associated with cuff disorders (P<.001). Controlling for cuff disorders, there was no relationship between anterior cysts and age (P>.50). Anterior cysts were more common in partial-thickness articular (48%) than in bursal (13%) tears (P<.001).

CONCLUSION

Posterior cysts were more common than anterior cysts and showed nearly random distribution among patients, regardless of age and cuff diagnosis. Anterior cysts were closely associated with cuff disorders.

Humeral head cysts and rotator cuff tears: an MR arthrographic study

OBJECTIVE

Humeral tuberosity cysts are a common finding, with previous reports suggesting they are related to rotator cuff tear or aging. The aim of this study was to investigate the characteristics of cysts in the tuberosities of the humeral head and their relationship with rotator cuff tear and age.

DESIGN AND PATIENTS

Shoulder MR arthrograms were reviewed in 120 consecutive patients-83 males (mean age 38.0, range 19-59 years) and 37 females (mean age 41.2, range 15-59 years). Patients were referred for investigation of a variety of conditions, and instability was suspected in only a minority of cases. MR was performed before and after direct arthrography with 0.01% solution of gadolinium. Cysts were defined as well-demarcated circular/ovoid foci in two planes that demonstrated high signal on pre-arthrographic T2W sequences. Location, size and numbers of cysts and post-arthrographic enhancement were documented, along with the location of rotator cuff tears, if present.

RESULTS

Cysts in the tuberosities of the humerus were identified in 84 patients (70%), and were seen seven times more frequently in the posterior aspect of the greater tuberosity than anteriorly. Most cysts (94%) demonstrated communication with the joint post-arthrogram. Rotator cuff tears were present in 36 patients, and 79% of all tears occurred in supraspinatus tendon. There was no significant difference in the occurrence of cysts between patients older or younger than age 40 or between genders, but rotator cuff tears were seen significantly more often in the older age group (p<0.01). Tuberosity cysts and rotator cuff tears did not appear to be related (p=0.55). However, whilst this lack of association was quite obvious posteriorly (p=0.84), the trend in the anterior aspect of the greater tuberosity is not as clear (p=0.14).

CONCLUSIONS

Humeral cysts are most often located in the posterior aspect of the greater tuberosity, communicate with the joint space and, in this location, are not related to aging or rotator cuff tear.

Cystic Lesions in the Posterosuperior Portion of the Humeral Head on MR Arthrography: Correlations with Gross and Histologic Findings in Cadavers

OBJECTIVE

The purpose of this study was to describe the appearance of cysts in the posterosuperior portion of the humeral head on MR arthrography and to correlate the MRI findings with the gross and histologic findings in cadavers.

CONCLUSION

Cysts in the posterosuperior portion of the humeral head (the bare area) were located in the lateral humeral head just posterior to the greater tuberosity. These cysts were lined with collagen connective tissue and were connected to the joint spaces. We suggest that these pseudocysts in the posterosuperior portion of the humeral head may be a normal variant rather than being an abnormal change or vascular channel.

Rheumatoid arthritis of the shoulder joint: Comparison of conventional radiography, ultrasound, and dynamic contrast-enhanced magnetic resonance imaging

OBJECTIVE

To determine the role of ultrasound and magnetic resonance imaging (MRI) compared with conventional radiography in the detection of chronic and acute inflammatory manifestations of rheumatoid arthritis (RA) of the shoulder joint.

METHODS

Forty-three consecutive patients with known RA prospectively underwent clinical examination, radiography, ultrasound, and MRI of the shoulder joints. Each patient was assigned a clinical/laboratory score consisting of 7 parameters, including measurements of shoulder mobility, the erythrocyte sedimentation rate, and C-reactive protein level. Conventional radiography was standardized and performed in 2 planes. Ultrasound was performed in 10 predefined planes using a 7.5-MHz linear transducer. MRI at 1.5T comprised transverse and oblique coronal T1- and T2*-weighted fast spin-echo, gradient-echo (GRE), and inversion-recovery sequences with a matrix size of up to 512 pixels. A dynamic T1-weighted GRE sequence was acquired with intravenous administration of contrast medium. Erosions were assessed using all 3 imaging techniques on a 4-point scale. Soft-tissue involvement was evaluated according to the presence of synovitis, tenosynovitis, and bursitis on ultrasound and MRI. The results in the study group were compared with those obtained in a control group of 10 patients with shoulder pain.

RESULTS

In the study group, erosions of the humeroscapular joint were detected by conventional radiography in 26 patients, by ultrasound in 30 patients, and by MRI in 39 patients; the differences were statistically significant for the comparisons of conventional radiography with MRI and for ultrasound versus MRI (P < 0.0001). Conventional radiography detected 12 erosions of the scapula and MRI detected 15. Synovitis was demonstrated in 12 patients by ultrasound and in 27 patients by MRI (P = 0.0003). Tenosynovitis was observed in 15 patients by ultrasound and in 28 patients by MRI (P = 0.0064). Bursitis was detected in 13 patients by ultrasound and in 18 patients by MRI. The findings on dynamic contrast-enhanced MRI correlated significantly with the detection of synovitis by ultrasound and erosions by static MRI (P < 0.05).

CONCLUSION

Ultrasound and MRI supplement conventional radiography in assessing the shoulder joint. Although conventional radiography can be used as the sole method of following up known joint destruction in RA, ultrasound and, preferably, MRI are recommended as additional techniques in the initial diagnostic evaluation when radiography yields negative results.

Mechanical environment of the supraspinatus tendon: a two-dimensional finite element model analysis

We performed 2-dimensional finite element model analysis to estimate the mechanical environment of the supraspinatus tendon. The geometric shape of the finite element model was determined by magnetic resonance imaging of a normal human shoulder obtained at 0 degrees, 30 degrees, and 60 degrees of abduction, whereas the histologic location of noncalcified and calcified fibrocartilage was determined from a cadaveric specimen. The supraspinatus tendon was pulled proximally with the force of 10 N at 0 degrees, 53 N at 30 degrees, and 115 N at 60 degrees of abduction. The area of high principal stress maximum was observed on the articular side of the supraspinatus tendon, which shifted toward the insertion as the arm was abducted. High stress concentration on the articular side of the supraspinatus tendon near its insertion during arm elevation may explain the frequent occurrence of rotator cuff tears at this site.

Shoulder MRI refinements: differentiation of rotator cuff tear from artifacts and tendonosis, and reassessment of normal findings

One of the difficulties with rotator cuff imaging lies in the normal variability of the tendon's signal. There may be intermediate signal present within the tendon because of magic-angle phenomenon, muscle and tendon fiber interdigitation, or tendinopathy related to degenerative changes or overuse injury. Partial and complete rotator cuff tears should be distinguishable from these causes of intermediate signal if water signal is reliably identified. This article reviews the important issue of distinguishing between rotator cuff tear and other causes of high signal in the rotator cuff, including artifacts and tendonosis. We include a review of the literature and a brief report of a study we conducted on 20 shoulders of 14 asymptomatic, young volunteers. In this study, the rotator cuff tendons were evaluated for abnormal signal at different TE values to determine at what TE the interpreters were able to confidently distinguish the high-signal intensity of a tear (water) from the intermediate signal intensity associated with artifact and tendinopathy. Readers were able to distinguish water and tendon signal in 70% to 100% of fast-spin echo (FSE) fat-saturated images with TE of 66, but there was interobserver variability at this TE, suggesting that it is less reliable than 88 ms in the identification of rotator cuff tears. By using FSE fat-saturated sequences with TE of 88 and fast spin echo inversion recovery (FSEIR) sequences, readers at all levels of experience were able to differentiate water signal intensity from tendon signal intensity in 100% of cases. Therefore, we suggest that either FSEIR images or FSE fat-saturated images with TE greater than 66 be used to facilitate the differentiation of fluid signal from intermediate increased signal intensity in rotator cuff imaging. Additionally, this article reviews the normal findings of shoulder magnetic resonance imaging (MRI) as revealed by the asymptomatic subjects included in our study, and assesses these findings in respect to previous publications. The normal features reviewed include the subacromion-subdeltoid (SA/SD) bursa, the biceps tendon sheath, the acromioclavicular (AC) joint, and the greater tuberosity of the humerus. A small amount of fluid was commonly seen in the SA/SD bursa, as well as the biceps tendon sheath. Subjective down-sloping of the acromion in the coronal plane, mild degenerative change of the AC joint, and undersurface spurring of the AC joint were uncommon in our normal subjects. Cystic change limited to the posterior aspect of the greater tuberosity was identified in 15% to 45% of shoulders.