Biceps Pulley Lesions: Diagnostic Accuracy of Nonarthrographic Shoulder MRI and the Value of Various Diagnostic Signs

BACKGROUND

There is limited data in the literature regarding the role of nonarthrographic MRI for detecting biceps pulley (BP) lesions.

PURPOSE

To assess the accuracy of nonarthrographic MRI for detecting BP lesions, and to evaluate the diagnostic value of various MRI signs (superior glenohumeral ligament discontinuity/nonvisibility, long head of biceps (LHB) displacement sign or subluxation/dislocation, LHB tendinopathy, and supraspinatus and subscapularis tendon lesions) in detecting such lesions.

STUDY TYPE

Retrospective.

POPULATION

84 patients (32 in BP-lesion group and 52 in BP-intact group-as confirmed by arthroscopy).

FIELD STRENGTH/SEQUENCE

1.5-T, T1-weighted turbo spin echo (TSE), T2-weighted TSE, and proton density-weighted TSE spectral attenuated inversion recovery (SPAIR) sequences.

ASSESSMENT

Three radiologists independently reviewed all MRI data for the presence of BP lesions and various MRI signs. The MRI signs and final MRI diagnoses were tested for accuracy regarding detecting BP lesions using arthroscopy results as the reference standard. Furthermore, the inter-reader agreement (IRA) between radiologists was determined.

STATISTICAL TESTS

Student's t-tests, Chi-squared, and Fisher's exact tests, and 4-fold table test were used. The IRA was calculated using Kappa statistics. A P-value <0.05 was considered statistically significant.

RESULTS

The sensitivity, specificity, and accuracy of nonarthrographic MRI for detecting BP lesions were 65.6%-78.1%, 90.4%-92.3%, and 81%-86.9%, respectively. The highest accuracy was noticed for the LHB displacement sign (84.5%-86.9%), and the highest sensitivity was registered for the LHB tendinopathy sign (87.5%). Furthermore, the highest specificity was observed for the LHB displacement sign and LHB subluxation/dislocation sign (98.1%-100%). The IRA regarding final MRI diagnosis and MRI signs of BP lesions was good to very good (κ = 0.76-0.98).

DATA CONCLUSION

Nonarthrographic shoulder MRI may show good diagnostic accuracy for detecting BP lesions. The LHB displacement sign could serve as the most accurate and specific sign for diagnosis of BP lesions.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY: Stage 2.

Detection and Quantitative Assessment of Arthroscopically Proven Long Biceps Tendon Pathologies Using T2 Mapping

This study evaluates how far T2 mapping can identify arthroscopically confirmed pathologies in the long biceps tendon (LBT) and quantify the T2 values in healthy and pathological tendon substance. This study comprised eighteen patients experiencing serious shoulder discomfort, all of whom underwent magnetic resonance imaging, including T2 mapping sequences, followed by shoulder joint arthroscopy. Regions of interest were meticulously positioned on their respective T2 maps, capturing the sulcal portion of the LBT and allowing for the quantification of the average T2 values. Subsequent analyses included the calculation of diagnostic cut-off values, sensitivities, and specificities for the detection of tendon pathologies, and the calculation of inter-reader correlation coefficients (ICCs) involving two independent radiologists. The average T2 value for healthy subjects was measured at 23.3 ± 4.6 ms, while patients with tendinopathy displayed a markedly higher value, at 47.9 ± 7.8 ms. Of note, the maximum T2 value identified in healthy tendons (29.6 ms) proved to be lower than the minimal value measured in pathological tendons (33.8 ms), resulting in a sensitivity and specificity of 100% (95% confidence interval 63.1-100) across all cut-off values ranging from 29.6 to 33.8 ms. The ICCs were found to range from 0.93 to 0.99. In conclusion, T2 mapping is able to assess and quantify healthy LBTs and can distinguish them from tendon pathology. T2 mapping may provide information on the (ultra-)structural integrity of tendinous tissue, facilitating early diagnosis, prompt therapeutic intervention, and quantitative monitoring after conservative or surgical treatments of LBT.

Are the Pathologic Features of Enthesopathy, Tendinopathy, and Labral and Articular Disc Disease Related to Mucoid Degeneration? A Systematic Review

BACKGROUND

Tendinopathy, enthesopathy, labral degeneration, and pathologic conditions of the articular disc (knee meniscus and ulnocarpal) are sometimes described in terms of inflammation or damage, while the histopathologic findings are often consistent with mucoid degeneration. A systematic review of the histopathology of these structures at diverse locations might reconceptualize these diseases as expected aspects of human aging. The potential benefits of this evolution might include healthier patient and clinician mindsets as well as a reduced likelihood of overdiagnosis and overtreatment resulting from greater awareness of base rates of pathology.

QUESTION/PURPOSE

In this systematic review of studies of surgical specimens, we asked: Are there are any differences in the histopathologic findings of structural soft tissue conditions (mucoid degeneration, inflammation, and vascularity) by anatomic site (foot, elbow, or knee) or structure (tendon body, muscle or tendon origin or insertion [enthesis], labrum, or articular disc)?

METHODS

Studies between 1980 and 2021 investigating the histopathologic findings of specimens from surgery for trigger digit, de Quervain tendinopathy, plantar fasciitis, lateral and medial elbow enthesopathy, rotator cuff tendinopathy, posterior tibial tendinopathy, patellar tendinopathy, Achilles tendinopathy, or disease of the hip labrum, ulnocarpal articular disc, or knee meniscus were searched for in the PubMed, EMBASE, and CINAHL databases. Inclusion criteria were the prespecified anatomic location or structure being analyzed histologically and any findings described with respect to inflammation, vascularity, or mucoid degeneration. Studies were excluded if they were nonhuman studies or review articles. Search terms included "anatomy," "pathology," and "histopathology." These terms were coupled with anatomic structures or disorders and included "trigger finger," "de Quervain," "fasciitis, plantar," "tennis elbow," "rotator cuff tendinopathy," "elbow tendinopathy," "patellar tendonitis," "posterior tibial tendon," and "triangular fibrocartilage." This resulted in 3196 studies. After applying the inclusion criteria, 559 articles were then assessed for eligibility according to our exclusion criteria, with 52 eventually included. We recorded whether the study identified the following histopathologic findings: inflammatory cells or molecular markers, greater than expected vascularity (categorized as quantitative count, with or without controls; molecular markers; or qualitative judgments), and features of mucoid degeneration (disorganized collagen, increased extracellular matrix, or chondroid metaplasia). In the absence of methods for systematically evaluating the pathophysiology of structural (collagenous) soft tissue structures and rating histopathologic study quality, all studies that interpreted histopathology results were included. The original authors' judgment regarding the presence or absence of inflammation, greater than expected vascularity, and elements of mucoid degeneration was recorded along with the type of data used to reach that conclusion.

RESULTS

Regarding differences in the histopathology of surgical specimens of structural soft tissue conditions by anatomic site, there were no differences in inflammation or mucoid degeneration, and the knee meniscus was less often described as having greater than normal vascularity. There were no differences by anatomic structure. Overall, 20% (10 of 51) of the studies that investigated for inflammation reported it (nine inflammatory cells and one inflammatory marker). Eighty-three percent (43 of 52) interpreted increased vascularity: 40% (17 of 43) using quantitative methods (14 with controls and three without) and 60% (26 of 43) using imprecise criteria. Additionally, 100% (all 52 studies) identified at least one element of mucoid degeneration: 69% (36 of 52) reported an increased extracellular matrix, 71% (37 of 52) reported disorganized collagen, and 33% (17 of 52) reported chondroid metaplasia.

CONCLUSION

Our systematic review of the histopathology of diseases of soft tissue structures (enthesopathy, tendinopathy, and labral and articular disc) identified consistent mucoid degeneration, minimal inflammation, and imprecise assessment of relative vascularity; these findings were consistent across anatomic sites and structures, supporting a reconceptualization of these diseases as related to aging (senescence or degeneration) rather than injury or activity.

CLINICAL RELEVANCE

This reconceptualization supports accommodative mindsets known to be associated with greater comfort and capability. In addition, awareness of the notable base rates of structural soft tissue changes as people age might reduce overdiagnosis and overtreatment of incidental, benign, or inconsequential signal changes and pathophysiology.

Imaging of the Long Head of Biceps Tendon and Rotator Interval

This article reviews the imaging and common pathology of the long head of biceps tendon and rotator interval (RI). This area of complex anatomy plays a crucial role in normal shoulder function. Injury or abnormality of the RI may contribute to a range of shoulder pathology, such as biceps instability, tendinopathy, and frozen shoulder. Understanding the normal and pathologic appearances of the RI structures is crucial for a correct diagnosis and directing treatment.

Tendon midsubstance trauma as a means for the development of translatable chronic rotator cuff degeneration in an ovine model

BACKGROUND

Chronic degeneration of rotator cuff tendons is a major contributing factor to the unacceptably high prevalence of rotator cuff repair surgery failures. The etiology of chronic rotator cuff degeneration is not well understood, and current therapies are not effective, necessitating preclinical research to fill this knowledge gap. Unfortunately, current large animal models rely on enthesis disruption as a means of model generation, which is not representative of human patients with chronic rotator cuff degeneration prior to full-thickness tears. Following, the goal of this study was to develop and characterize a translational large-animal model of chronic rotator cuff degeneration without enthesis release.

METHODS

A midsubstance damage model [i.e., "combed fenestration" (CF)] in adult sheep was generated by creating 16 longitudinal cuts within the top third of the infraspinatus tendon thickness. Tendon integrity was characterized through exhaustive non-destructive biomechanical stress relaxation testing [peak stress, peak load, percent relaxation, and cross-sectional area (CSA)], followed by histopathological degeneration scoring and analysis (Bonar score), histomorphological analysis of collagen organization and fatty atrophy (percent adipose area), and gene expression analyses.

RESULTS

The CF model tendons exhibited significantly decreased mechanical properties as evidenced by decreased peak stress (P<0.025) and increased percent relaxation (18-week vs. Control, P<0.035) at multiple strain magnitudes and across all timepoints. At all timepoints, the CF tendons exhibited pathological changes aligned with tendon degeneration, as evidenced by increased Bonar scoring (P<0.001) and decreased collagen organization (6-week vs. Control, P=0.013). Increases in intramuscular adipose content were also documented through histomorphology analysis (6- and 18-week vs. Control, P<0.077). Significant changes in gene expression were noted at all timepoints.

CONCLUSIONS

These data reveal that this new ovine CF model of chronic rotator cuff degeneration results in tendons with decreased mechanical properties, degenerative pathology characteristics, and gene expression profiles that aligned with the degenerative changes that have been noted in humans with tendinopathy. For these reasons, we believe this novel large animal model of chronic rotator cuff degeneration is a translational platform in which to test devices, therapies, and/or technologies aimed at repairing damage to the shoulder.

Progression of long head of the biceps brachii tendon abnormality on magnetic resonance imaging after rotator cuff repair

OBJECTIVES

To correlate the deterioration of preserved long head of biceps tendon (LHB) after rotator cuff repair with preoperative and postoperative MRI factors.

METHODS

Total of 209 shoulder joints (F:M = 145:64; mean age 57.4 years) which underwent rotator cuff repair and at least two postoperative MRI scans over 10 months after surgery were included. LHB integrity was graded with a five point severity scale. LHB deterioration was defined by increased composite score of integrity and extent score between the preoperative and second postoperative MRI. For preoperative and postoperative MRI factors, size and location of superior cuff -supraspinatus and infraspinatus- and subscapularis tears, fatty degeneration of rotator cuff, preoperative LHB status, subluxation of LHB, superior labral tear, acromion type, repaired rotator cuff status, postoperative capsulitis and acromioplasty state were assessed. Logistic regression was used to evaluate the association between LHB deterioration and aforementioned factors. Same analysis was conducted for 62 shoulder joints with a long-term follow-up MRI.

RESULTS

Of the 209 shoulders, 49.3% (n = 103) showed LHB deterioration on short-term follow-up MRI. In long-term follow-up subgroup, 32 LHBs were further deteriorated. In multivariate analysis, fatty degeneration of superior cuff showed significant association with LHB deterioration in both short-term (p = .04, p = .007) and long-term subgroups (p = .004, p = .005) among preoperative and postoperative factors, respectively.

CONCLUSIONS

Degree of fatty degeneration in superior cuff is associated with LHB deterioration on postoperative MRI.

ADVANCES IN KNOWLEDGE

Our results support that tenotomy or tenodesis of LHB should be considered during rotator cuff repair, especially in patients with advanced fatty degeneration of rotator cuff.

[Injuries of the biceps-labrum complex : Principles, pathologies and treatment concepts]

BACKGROUND

The biceps-labrum complex is prone to acute lesions and degenerative changes due to its anatomical structure and the high load it has to endure. Pathological changes of these structures are common pain generators and can significantly impair shoulder function. Anatomically, the biceps-labrum complex can be divided into three zones: inside, junction and bicipital tunnel.

DIAGNOSTIC PROCEDURE

Despite the focused physical examination and advancements in imaging techniques, the exact localization of pathologies remains challenging. Arthroscopy can be used to accurately diagnose inside and junctional pathologies but extra-articular changes in the region of the bicipital tunnel can only be partially visualized.

TREATMENT

In cases of unsuccessful conservative treatment and correct indications, a high level of patient satisfaction can be surgically achieved. In young patients an anatomical reconstruction of inside lesions or tenodesis of the long head of the biceps tendon is performed; however, even tenotomy is a valuable option and can achieve equally satisfactory results. Unaddressed pathological changes of the bicipital tunnel can lead to persistence of pain. In clinical procedures performing tenodesis, both the different techniques and the implants used have been found to show similar results. This article describes the anatomical principles, pathological changes, the focused clinical instrumental diagnostics and discusses the different treatment philosophies as well as the outcome according to the recent literature.

A new significance of an old structure: Aponeurotic expansion of supraspinatus tendon and its relationships with biceps brachii long head and rotator cuff tendons

PURPOSE

To investigate the relationship between aponeurotic expansion of supraspinatus tendon and disorders of biceps brachii long head (LHB), supraspinatus and subscapularis tendons.

METHODS

Images of 3.0 T shoulder magnetic resonance images (MRI) of a total of 154 patients and 157 shoulders (3 cases with bilateral imaging) between the ages of 18-45 were retrospectively evaluated for the presence of aponeurotic expansion. When identified it was further categorized according to its thickness. Tendinopathy and tears of LHB, supraspinatus and subscapularis tendons and LHB subluxations were evaluated individually. Statistical analyses were performed using Chi-square, Fisher's exact, Mann-Whitney U and Kruskall-Wallis tests. Odds ratio and multiple logistic regression analyses were performed when applicable. p < 0.05 was considered as statistically significant.

RESULTS

A total of 82 male and 72 female cases with a mean age of 34 (±8.2) were included. Aponeurotic expansion could be identified in 31 cases (19.8 %). MRI findings for LHB disorders in this group was significantly higher (p = 0.01). The adjusted odds ratio of having LHB tendinopathy in the presence of aponeurotic expansion was 3.25 (% 95 CI:1.29-8.19). No significant correlation was found between presence of aponeurotic expansion and subscapularis or supraspinatus tendon disorders (p = 0.66 and p = 0.792 respectively). Age was a significant variable for disorders of all three tendons (p < 0.001).

CONCLUSION

On 3.0 T MRI, findings of LHB tendon disorders were significantly more common in cases with aponeurotic expansion of supraspinatus tendon. This anatomical variation may have an unrecognized clinical significance.

Diagnostic accuracy of MRI for detection of tears and instability of proximal long head of biceps tendon: an evaluation of 100 shoulders compared with arthroscopy

OBJECTIVE

To evaluate the diagnostic accuracy of magnetic resonance imaging (MRI) for detection of instability and tears of the proximal long head of biceps tendon (LHBT). To assess intraobserver and interobserver agreement.

MATERIALS AND METHODS

We performed a retrospective analysis of prospectively collected data of 100 consecutive shoulders who underwent non-contrast 1.5-T MRI prior to arthroscopic surgery due to rotator cuff injury. Images were independently analyzed by two musculoskeletal radiologists. LHBT was evaluated for presence of tearing (intact, longitudinal split, partial-thickness, or full-thickness) and position (normal, subluxated, and dislocated). Anterosuperior rotator cuff tears were also assessed. The reference standard was arthroscopic surgery. The ramp test was performed in order to evaluate LHBT stability. Diagnostic performance measures were determined and Kappa coefficients assessed agreement.

RESULTS

Concerning the detection of overall tears, sensitivity ranged from 71 to 73% and specificity was 73%. The specificity for full-thickness tears ranged from 75 to 96%. Overall displacement showed sensitivity ranging from 51 to 58% and specificity ranging from 70 to 86%. The specificity of overall displacement combined with anterosuperior rotator cuff tears ranged from 73 to 91%. Interobserver Kappa values were between 0.59 and 0.69. Intraobserver Kappa values were between 0.74 and 0.82.

CONCLUSIONS

MRI has moderate accuracy and good agreement for detection of LHBT tears and instability. There is a tendency for increased specificity for full-thickness tears and for instability in the coexistence of anterosuperior rotator cuff tears.

MRI, arthroscopic and histopathologic cross correlation in biceps tenodesis specimens with emphasis on the normal appearing proximal tendon

PURPOSE

To correlate the histopathologic appearances of resected long head of the biceps tendon (LHBT) specimens following biceps tenodesis, with pre-operative MRI and arthroscopic findings, with attention to the radiologically normal biceps.

MATERIAL AND METHODS

Retrospective analysis of patients who had undergone preoperative MRI, subsequent arthroscopic subpectoral tenodesis for SLAP tears and histopathologic inspection of the excised sample between 2013 and 16. Those with a normal MRI appearance or mildly increased intrasubstance signal were independently analyzed by 2 blinded radiologists. A blinded orthopedic surgeon and pathologist reviewed all operative imaging and pathologic slides, respectively.

RESULTS

Twenty-three LHBT resected samples were identified on MRI as either normal (Reader 1 n = 15; Reader 2 n = 14) or demonstrating low-grade increased signal (Reader 1 n = 8; Reader 2 n = 9). Of these, 86.9% demonstrated a histopathological abnormality. 50% of samples with histopathological abnormality demonstrated normal appearance on MRI. The most common reported histopathology finding was myxoid degeneration (73.9%) and fibrosis (52.2%). The most common arthroscopic abnormality was fraying (18.2%) and erythema (13.6%). Utilizing histopathology as the gold standard, the two radiologists demonstrated a sensitivity of 35.0% v 42.9%, specificity of 66.7% v 100%, PPV of 87.5% v 100%, and NPV of 13.3% v 14.3%. Corresponding arthroscopic inspection demonstrated a sensitivity of 31.6%, specificity of 66.6%, PPV 85.7% and NPV of 13.3%. There was moderate agreement between the two radiologists, κ = 0.534 (95% CI, 0.177 to 0.891), p = 0.01.

CONCLUSION

Histopathological features of low grade tendinosis including mainly myxoid degeneration and fibrosis are frequently occult on MR imaging.

Effect of patient age on accuracy of primary MRI signs of long head of biceps tearing and instability in the shoulder: an MRI-arthroscopy correlation study

OBJECTIVE

To determine the effect of patient age on the accuracy of primary MRI signs of long head of biceps (LHB) tendon tearing and instability in the shoulder using arthroscopy as a reference standard.

MATERIALS AND METHODS

Subjects with MRI studies and subsequent arthroscopy documenting LHB tendon pathology were identified and organized into three age groups (18-40, 41-60, 61-87). Normal and tendinopathic tendons were labeled grade 0, partial tears grade 1 and full tears grade 2. Two radiologists blinded to arthroscopic data graded MRI studies independently. Prevalence of disease, MRI accuracy for outcomes of interest, and inter-reader agreement were calculated.

RESULTS

Eighty-nine subjects fulfilled inclusion criteria with 36 grade 0, 36 grade 1 and 17 grade 2 tendons found at arthroscopy. MRI sensitivity, regardless of age, ranged between 67-86% for grade 0, 72-94% for grade 1 and 82-94% for grade 2 tendons. Specificity ranged between 83-96% for grade 0, 75-85% for grade 1 and 99-100% for grade 2 tendons. MRI accuracy for detection of each LHB category was calculated for each age group. MRI was found to be least sensitive for grade 0 and 1 LHB tendons in the middle-aged group with sensitivity between 55-85% for grade 0 and 53-88% for grade 1 tendons. Agreement between MRI readers was moderate with an unweighted kappa statistic of 62%.

CONCLUSION

MRI accuracy was moderate to excellent and agreement between MRI readers was moderate. MRI appears to be less accurate in characterizing lower grades of LHB tendon disease in middle-aged subjects.

A high-glucose diet affects Achilles tendon healing in rats

Chronic and acute tendinopathies are difficult to treat and tendon healing is generally a very slow and incomplete process and our general understanding of tendon biology and regeneration lags behind that of muscle or bone. Although still largely unexplored, several studies suggest a positive effect of nutritional interventions on tendon health and repair. With this study, we aim to reveal effects of a high-glucose diet on tendon neoformation in a non-diabetic rat model of Achilles tenotomy. After surgery animals received either a high-glucose diet or a control diet for 2 and 4 weeks, respectively. Compared to the control group, tendon repair tissue thickness and stiffness were increased in the high-glucose group after 2 weeks and gait pattern was altered after 1 and 2 weeks. Cell proliferation was up to 3-fold higher and the expression of the chondrogenic marker genes Sox9, Col2a1, Acan and Comp was significantly increased 2 and 4 weeks post-surgery. Further, a moderate increase in cartilage-like areas within the repair tissue was evident after 4 weeks of a high-glucose diet regimen. In summary, we propose that a high-glucose diet significantly affects tendon healing after injury in non-diabetic rats, potentially driving chondrogenic degeneration.

Diagnostic accuracy of 3T conventional shoulder MRI in the detection of the long head of the biceps tendon tears associated with rotator cuff tendon tears

OBJECTIVE

To evaluate the diagnostic performance (DP) of 3T (3 Tesla field strength) conventional shoulder magnetic resonance imaging (MRI) in detecting the long head of the biceps tendon (LHBT) tears in association with rotator cuff tendon tears.

MATERIALS AND METHODS

This study included 80 consecutive patients who underwent arthroscopic surgery for rotator cuff tendon tears. Two radiologists independently evaluated the preoperative 3T shoulder MRI for the presence of LHBT tears. The DP of MRI was evaluated using the results of arthroscopy as the reference standard. We also evaluated the DP of several MR signs of LHBT in detection of partial LHBT tears.

RESULTS

Arthroscopic examination revealed 35 partial and 5 complete tears. According to the results of evaluation by reviewers 1 and 2, shoulder MRI exhibited sensitivities of 77.14 and 80 % and specificities of 71.11 and 73.33 % in detection of partial LHBT tears and sensitivities of 80 and 100 % and a specificity of 100% (both) in detection of complete LHBT tears. In detecting partial LHBT tears, increased T2 signal intensity of the LHBT exhibited high sensitivities (reviewers 1 and 2; 82.85 and 80 %, respectively) and the presence of intratendinous defects or C-signs exhibited the highest specificities (reviewers 1 and 2; 95.55 and 93.33 %, respectively), followed by abnormalities in shape and outer margins of the LHBT (reviewers 1 and 2; 91.11 and 82 %; 91.11 and 86.66 %, respectively).

CONCLUSION

Non-contrast-enhanced 3T shoulder MRI is potentially highly accurate in detection of complete LHBT tears, but moderately accurate in detection of partial LHBT tears.

Detour sign in the diagnosis of subluxation of the long head of the biceps tendon with arthroscopic correlation

OBJECTIVE

To determine whether detection of the detour sign via MRI indicates subluxation of the long head of the biceps tendon (SLBT) in the shoulder joint and to investigate the association of SLBT with the degeneration of the long head of the biceps tendon (LBT) and rotator cuff tears.

METHODS

This retrospective study included 65 patients with shoulder pain who underwent shoulder MRI and arthroscopic surgery. When axial images revealed that the LBT was displaced over the inner rim of the bicipital groove with some remaining contact with the groove (Criterion 1), or demonstrated a "detour sign" of the biceps tendon (Criterion 2), the lesion was diagnosed as an SLBT. Shoulder arthroscopy was used as the reference standard.

RESULTS

Arthroscopy identified SLBT in 18 patients. When the MRI diagnosis was based on Criterion 1 alone, SLBT was diagnosed with a sensitivity of 44.4-55.6% and 75.4-80% accuracy. However, when the MRI diagnosis was based on Criteria 1 plus 2, SLBT was diagnosed with a sensitivity of 83.3-94.4% and 78.5-81.5% accuracy. There was a significant difference (p < 0.05) in the diagnostic sensitivity of Criteria 1 and 2.

CONCLUSION

The detour sign based on axial MRI may be regarded an additional useful anatomical feature that improves the diagnostic performance of MRI in the identification of SLBT lesions. Advances in knowledge: Recognition of the detour sign may enhance the diagnostic performance of the conventional MRI protocol over the MR arthrography protocol for SLBT.

Creating an Animal Model of Tendinopathy by Inducing Chondrogenic Differentiation with Kartogenin

Previous animal studies have shown that long term rat treadmill running induces over-use tendinopathy, which manifests as proteoglycan accumulation and chondrocytes-like cells within the affected tendons. Creating this animal model of tendinopathy by long term treadmill running is however time-consuming, costly and may vary among animals. In this study, we used a new approach to develop an animal model of tendinopathy using kartogenin (KGN), a bio-compound that can stimulate endogenous stem/progenitor cells to differentiate into chondrocytes. KGN-beads were fabricated and implanted into rat Achilles tendons. Five weeks after implantation, chondrocytes and proteoglycan accumulation were found at the KGN implanted site. Vascularity as well as disorganization in collagen fibers were also present in the same site along with increased expression of the chondrocyte specific marker, collagen type II (Col. II). In vitro studies confirmed that KGN was released continuously from KGN-alginate in vivo beads and induced chondrogenic differentiation of tendon stem/progenitor cells (TSCs) suggesting that chondrogenesis after KGN-bead implantation into the rat tendons is likely due to the aberrant differentiation of TSCs into chondrocytes. Taken together, our results showed that KGN-alginate beads can be used to create a rat model of tendinopathy, which, at least in part, reproduces the features of over-use tendinopathy model created by long term treadmill running. This model is mechanistic (stem cell differentiation), highly reproducible and precise in creating localized tendinopathic lesions. It is expected that this model will be useful to evaluate the effects of various topical treatments such as NSAIDs and platelet-rich plasma (PRP) for the treatment of tendinopathy.

The extensor carpi ulnaris pseudolesion: evaluation with microCT, histology, and MRI

OBJECTIVE

To determine if magic angle plays a role in apparent central increased signal intensity of the distal extensor carpi ulnaris tendon (ECU) on MRI, to see if histologic findings of tendon degeneration are associated with increased T1 or T2 tendon signal on MR imaging, and to determine the prevalence of the ECU "pseudolesion".

MATERIALS AND METHODS

A standard 3 Tesla protocol was utilized to scan ten cadaveric wrists. A 40 mm length of 10 ECU and four extensor carpi radialis brevis (ECRB) tendons were immersion fixed before microCT scanning. Staining with Alcian blue, Masson's trichrome and Safranin O was performed before light microscopy. Fifty clinical wrist MRIs were also reviewed for the presence of increased T1 and/or T2 signal.

RESULTS

Central increased T1 and/or T2 signal was observed in 9 of 10 cadaveric ECU tendons, but not in ECRB tendons. MicroCT and histology showed inter-tendinous matrix between the two distal heads of the ECU. Increased mucoid degeneration correlated with increased MRI signal intensity. The tendon fibers were at a maximum of 8.39° to the longitudinal axis on microCT. Clinical MRIs showed increased T1 signal in 6%, increased T2 signal in 8%, increased T1 and T2 signal in 80%, and 6% showing no increased signal.

CONCLUSION

Central increased T1 and/or T2 signal in the ECU tendon indicates the presence of normal inter-tendinous ground substance, with increased proteoglycan content (mucoid degeneration) responsible for increased signal intensity. None of the fibers were shown on microCT to approach the magic angle.

Long head of the biceps brachii tendon: unenhanced MRI versus direct MR arthrography

OBJECTIVE

We sought to determine the diagnostic accuracy of unenhanced MRI and direct MR arthrography (MRA) for evaluation of the intra-articular long head of the biceps brachii tendon (LHBT) using arthroscopy as the gold standard.

MATERIALS AND METHODS

A retrospective review of patients who underwent shoulder MRI (n = 132) and MRA (n = 67) within 12 months prior to arthroscopy was performed. MR images were independently reviewed by two blinded musculoskeletal radiologists. Routinely recorded arthroscopic photos/videos were reviewed by an orthopedic surgeon. The LHBT was graded as normal, tendinosis, partial thickness tear less or greater than 50%, and complete tear. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy for tendinosis and tear detection were calculated.

RESULTS

MRI correctly diagnosed fewer normal LHBTs compared to MRA (39-54% versus 74-84%, respectively; p < 0.005). MRI and MRA did not differ significantly in the diagnosis of tendinosis (18-36% and 15-38%, respectively; p > 0.05) and tears (75-83% and 64-73%, respectively; p > 0.05). For tendinosis, MRI versus MRA showed 18-36% and 15-38% sensitivity, 69-79% and 83-91% specificity, 22-28% and 18-50% PPV, 74-76% and 80-86% NPV, and 61-64% and 70-81% accuracy; respectively. For tears, MRI versus MRA showed 75-83% and 64-73% sensitivity, 73-75% and 82-91% specificity, 66-69% and 41-62% PPV, 82-87% and 92-94% NPV, and 74-78% and 79-88% accuracy; respectively.

CONCLUSIONS

No significant difference was found between unenhanced MRI and direct MRA for the detection of tendinosis and tears of LHBTs.

The aponeurotic expansion of the supraspinatus tendon: anatomy and prevalence in a series of 150 shoulder MRIs

OBJECTIVE

To describe the aponeurotic expansion of the supraspinatus tendon with anatomic correlations and determine its prevalence in a series of patients imaged with MRI.

MATERIALS AND METHODS

In the first part of this HIPAA-compliant and IRB-approved study, we retrospectively reviewed 150 consecutive MRI studies of the shoulder obtained on a 1.5-T system. The aponeurotic expansion at the level of the bicipital groove was classified as: not visualized (type 0), flat-shaped (type 1), oval-shaped and less than 50% the size of the adjacent long head of the biceps section (type 2A), or oval-shaped and more than 50% the size of the adjacent long head of the biceps section (type 2B). In the second part of this study, we examined both shoulders of 25 cadavers with ultrasound. When aponeurotic expansion was seen at US, a dissection was performed to characterize its origin and termination.

RESULTS

An aponeurotic expansion of the supraspinatus located anterior and lateral to the long head of the biceps in its groove was clearly demonstrated in 49% of the shoulders with MRI. According to our classification, its shape was type 1 in 35%, type 2A in 10 % and type 2B in 4%. This structure was also identified in 28 of 50 cadaveric shoulders with ultrasound and confirmed at dissection in 10 cadavers (20 shoulders). This structure originated from the most anterior and superficial aspect of the supraspinatus tendon and inserted distally on the pectoralis major tendon.

CONCLUSION

The aponeurotic expansion of the supraspinatus tendon can be identified with MRI or ultrasound in about half of the shoulders. It courses anteriorly and laterally to the long head of the biceps tendon, outside its synovial sheath.

Structure, ontogeny and evolution of the patellar tendon in emus (Dromaius novaehollandiae) and other palaeognath birds

The patella (kneecap) exhibits multiple evolutionary origins in birds, mammals, and lizards, and is thought to increase the mechanical advantage of the knee extensor muscles. Despite appreciable interest in the specialized anatomy and locomotion of palaeognathous birds (ratites and relatives), the structure, ontogeny and evolution of the patella in these species remains poorly characterized. Within Palaeognathae, the patella has been reported to be either present, absent, or fused with other bones, but it is unclear how much of this variation is real, erroneous or ontogenetic. Clarification of the patella’s form in palaeognaths would provide insight into the early evolution of the patella in birds, in addition to the specialized locomotion of these species. Findings would also provide new character data of use in resolving the controversial evolutionary relationships of palaeognaths. In this study, we examined the gross and histological anatomy of the emu patellar tendon across several age groups from five weeks to 18 months. We combined these results with our observations and those of others regarding the patella in palaeognaths and their outgroups (both extant and extinct), to reconstruct the evolution of the patella in birds. We found no evidence of an ossified patella in emus, but noted its tendon to have a highly unusual morphology comprising large volumes of adipose tissue contained within a collagenous meshwork. The emu patellar tendon also included increasing amounts of a cartilage-like tissue throughout ontogeny. We speculate that the unusual morphology of the patellar tendon in emus results from assimilation of a peri-articular fat pad, and metaplastic formation of cartilage, both potentially as adaptations to increasing tendon load. We corroborate previous observations of a ‘double patella’ in ostriches, but in contrast to some assertions, we find independent (i.e., unfused) ossified patellae in kiwis and tinamous. Our reconstructions suggest a single evolutionary origin of the patella in birds and that the ancestral patella is likely to have been a composite structure comprising a small ossified portion, lost by some species (e.g., emus, moa) but expanded in others (e.g., ostriches).

First metatarsophalangeal joint- MRI findings in asymptomatic volunteers

OBJECTIVES

To evaluate the spectrum and frequency of MR findings of the first metatarsophalangeal joint (MTPJ) in asymptomatic volunteers.

METHODS

MR imaging of 30 asymptomatic forefeet was performed with a dedicated extremity 1.5-Tesla system. Participants were between 20 and 49 years of age (mean ± SD: 35.5 ± 8.4 years). Two radiologists assessed cartilage, bone, capsuloligamentous structures, and tendons of first MTPJs on MR images.

RESULTS

Cartilage defects were observed in 27 % (n = 8) of first MTPJs, most frequently located at the base of the proximal phalanx (23 %, n = 7), whereas cartilage defects of the metatarsal head (13 %, n = 4) and the metatarsosesamoid compartment were rare (0 %-3 %, n = 0-1). Bone marrow oedema-like signal changes were present in 37 % (n = 11) and subchondral cysts in 20 % (n = 6) of first MTPJs. Hyperintense areas on intermediate-weighted sequences (range: 30-43 %, n = 9-13) and on fluid-sensitive sequences with fat suppression (range: 33-60 %, n = 10-18) within the medial and lateral collateral ligament complex were common. Plantar recesses (77 %, n = 23) and distal dorsal recesses (87 %, n = 26) were frequently observed.

CONCLUSIONS

Cartilage defects, bone marrow oedema-like signal changes, subchondral cysts, plantar recesses, and distal dorsal recesses were common findings on MRI of first MTPJs in asymptomatic volunteers. The collateral ligaments were often heterogeneous in structure and showed increased signal intensity.

KEY POINTS

• Cartilage defects of asymptomatic first metatarsophalangeal joints were common on MRI. • The collateral ligaments were often heterogeneous in structure and showed increased signal intensity. • Areas of increased signal intensity within the flexor and extensor tendons were rare. • These observations need to be considered in MR examinations of symptomatic cases.

Shoulder arthroscopy remains superior to direct MR arthrography for diagnosis of subtle rotator interval lesions

PURPOSE

To assess the sensitivity, specificity and accuracy of MR arthrography, as opposed to shoulder arthroscopy, in diagnosing individual rotator interval (RI) structures lesions at different levels of severity.

MATERIALS AND METHODS

Seventy-five patients were enrolled in a prospective study. All the patients were diagnosed with full-thickness rotator cuff tendon tears on unenhanced MRI and had complimentary MR arthrography to search for obscure RI lesions. All the patients then underwent shoulder arthroscopy. The arthroscopist was blinded about the MR arthrography results.

RESULTS

At arthroscopy, 42 patients (56 %) were found to have RI lesion(s) and represented the study group. The remaining 33 patients represented the control group. The sensitivity, specificity and accuracy of MR arthrography for detecting individual RI lesions varied widely depending on the location and severity of the lesions. MR arthrography showed intermediate sensitivity of 67-80 %, specificity of 83-89 % and accuracy of 89-92 % for diagnosing subtle RI lesions; and perfect (100 %) sensitivity, specificity and accuracy for diagnosing biceps long head tendon dislocation. For the rest of RI lesions, MR arthrography showed high sensitivity, specificity and accuracy. Inter-observer agreement was found to be almost perfect (K = 0.81-1.0).

CONCLUSION

Shoulder arthroscopy remains the gold standard for diagnosing subtle RI lesions. Although MR arthrography has proved to be a valuable tool for diagnosing established RI lesions, it is of intermediate sensitivity for diagnosing subtle RI lesions resulting in early insufficiency of the biceps pulley system.

The effect of biceps procedure on the outcome of rotator cuff reconstruction

Purpose. Biceps long head pathology is often associated with rotator cuff tears. The aim of this study was to determine the effect of possible associated biceps procedure on the treatment outcome in rotator cuff repair. Methods. 148 consecutive shoulders operated for isolated full-thickness supraspinatus tendon tear were included. A biceps tenotomy or tenodesis was performed in cases of irritated/frayed and/or unstable biceps tendon. The patients were grouped into three groups according to the biceps procedure (no procedure, tenotomy, and tenodesis). The age-adjusted Constant score was used as an outcome measure. Results. 145 shoulders (98%) were available for final followup. Preoperatively, there was no statistically significant difference in Constant scores. At three months, there was a statistically significant positive change in Constant scores compared with preoperative status in the tenotomy group in women. At one year there was a statistically significant positive change in Constant scores in all groups in both genders. However, there was no statistically significant difference between the groups at one year in either gender. Conclusion. Biceps procedure does not affect the final clinical treatment outcome after rotator cuff repair. Recovery from operative treatment may be faster in tenotomized female patients in cases of encountered biceps pathology.

Anterior cruciate ligament changes in the human knee joint in aging and osteoarthritis

OBJECTIVE

The development and patterns of spontaneous age-related changes in the anterior cruciate ligament (ACL) and their relationship to articular cartilage degeneration are not well characterized. This study was undertaken to investigate the types and temporal sequence of age-related ACL changes and to determine their correlation with cartilage lesion patterns at all stages of osteoarthritis (OA) development in human knee joints without prior joint trauma.

METHODS

Human knee joints (n = 120 from 65 donors ages 23-92) were obtained at autopsy, and ACLs and cartilage were graded macroscopically and histologically. Inflammation surrounding the ACL was assessed separately.

RESULTS

Histologic ACL substance scores and ligament sheath inflammation scores increased with age. Collagen fiber disorganization was the earliest and most prevalent change. The severity of mucoid degeneration and chondroid metaplasia in the ACL increased with the development of cartilage lesions. A correlation between ACL degeneration and cartilage degeneration was observed, especially in the medial compartment of the knee joint.

CONCLUSION

Our findings indicate that ACL degeneration is highly prevalent in knees with cartilage defects and may even precede cartilage changes. Hence, ACL deficiencies may not only be important in posttraumatic OA, but may also be a feature associated with knee OA pathogenesis in general.

Lesions of the biceps pulley: diagnostic accuracy of MR arthrography of the shoulder and evaluation of previously described and new diagnostic signs

PURPOSE

To retrospectively determine the diagnostic accuracy of magnetic resonance (MR) arthrography of the shoulder in the evaluation of lesions of the biceps pulley and to evaluate previously described and new diagnostic signs.

MATERIALS AND METHODS

Institutional review board approval was obtained; the requirement for informed consent was waived. MR arthrograms of 80 consecutive patients (mean age, 34.2 years; 53 male, 27 female) with arthroscopically proved intact or torn pulley systems were assessed for the presence of a pulley lesion by three radiologists who were blinded to arthroscopic results. Criteria evaluated were displacement of the long head of the biceps tendon (LHBT) relative to the subscapularis tendon on oblique sagittal images (displacement sign), medial subluxation of the LHBT on transverse images, nonvisibility or discontinuity of the superior glenohumeral ligament (SGHL), presence of biceps tendinopathy, and rotator cuff tears adjacent to the rotator interval.

RESULTS

There were 28 pulley lesions noted at arthroscopy. For observers 1, 2, and 3, respectively: MR arthrography showed a sensitivity of 89%, 86%, and 82% and a specificity of 96%, 98%, and 87% in the detection of pulley lesions. Nonvisibility or discontinuity of the SGHL was sensitive (79%, 89%, and 79%) and specific (83%, 79%, and 75%). With the displacement sign, sensitivity was 86%, 82%, and 75% and specificity was 96%, 98%, 90%. Tendinopathy of the LHBT on oblique sagittal images showed a sensitivity of 93%, 82%, 64%; specificity was 81%, 96%, and 85%. Subluxation of the LHBT was insensitive (36%, 50%, and 64%) but specific (100%, 98%, and 96%).

CONCLUSION

MR arthrography is accurate in the detection of pulley lesions; the displacement sign, nonvisibility or discontinuity of the SGHL, and tendinopathy of the LHBT on oblique sagittal images are the most accurate criteria for the detection of pulley lesions.

Biceps pulley: normal anatomy and associated lesions at MR arthrography

The biceps pulley or "sling" is a capsuloligamentous complex that acts to stabilize the long head of the biceps tendon in the bicipital groove. The pulley complex is composed of the superior glenohumeral ligament, the coracohumeral ligament, and the distal attachment of the subscapularis tendon, and is located within the rotator interval between the anterior edge of the supraspinatus tendon and the superior edge of the subscapularis tendon. Because of its superior depiction of the capsular components, direct magnetic resonance arthrography is the imaging modality of choice for demonstrating both the normal anatomy and associated lesions of the biceps pulley. Oblique sagittal images and axial images obtained with a high image matrix are valuable for identifying individual components of the pulley system. Various pathologic processes occur in the biceps pulley as well as the rotator interval. These processes can be traumatic, degenerative, congenital, or secondary to injuries to the surrounding structures. The term hidden lesion refers to an injury of the biceps pulley mechanism and is derived from the difficulty in making clinical and arthroscopic identification. Pathologic conditions associated with pulley lesions include anterosuperior impingement, instability of the biceps tendon, biceps tendinopathy or tendinosis, superior labrum anterior and posterior lesions, and adhesive capsulitis. It is important to be familiar with the normal appearance of the biceps pulley so that abnormalities can be correctly assessed and effectively managed.

[Arthroscopic treatment strategies for the long head of the biceps tendon]

Shoulder pain is a common issue in orthopedic clinics and the advancement and progress in shoulder arthroscopy has brought new knowledge into the anatomy, pathology and treatment. Affection of the long head of the biceps tendon (LHBT) may be the cause of these disorders. Pathologies of the LHBT are comorbidities of rotator cuff tears or shoulder instability. The following article gives an overview of diseases of the LHBT as well as arthroscopic treatment options.