Computed tomography (CT) arthrography of shoulder instabilities in athletes

Anterior Shoulder Instability

The anatomy of the glenohumeral joint prioritizes mobility at the expense of stability and thus predisposes it to injury through dislocation. This article discusses the anatomical basis for instability and how it translates into patterns of injury, focusing on anterior instability. We suggest an approach to imaging the unstable shoulder and examine the imaging features seen in the context of anterior instability, along with consideration of postoperative appearances.

Control strategies to re-establish glenohumeral stability after shoulder injury

BACKGROUND

Muscles are important "sensors of the joint instability". The aim of this study was to identify the neuro-motor control strategies adopted by patients with anterior shoulder instability during overhead shoulder elevation in two planes.

METHODS

The onset, time of peak activation, and peak magnitude of seven shoulder muscles (posterior deltoid, bilateral upper trapezius, biceps brachii, infraspinatus, supraspinatus and teres major) were identified using electromyography as 19 pre-operative patients with anterior shoulder instability (mean 27.95 years, SD = 7.796) and 25 age-matched asymptomatic control subjects (mean 23.07 years, SD = 2.952) elevated their arm above 90 degrees in the sagittal and coronal planes.

RESULTS

Temporal characteristics of time of muscle onsets were significantly different between groups expect for teres major in the coronal plane (t = 1.1220, p = 0.2646) Patients recruited the rotator cuff muscles earlier and delayed the onset of ipsilateral upper trapezius compared with subjects (p<0.001) that control subjects. Furthermore, significant alliances existed between the onsets of infraspinatus and supraspinatus (sagittal: r = 0.720; coronal: r = 0.756 at p<0.001) and ipsilateral upper trapezius and infraspinatus (sagittal: r = -0.760, coronal: r = -0.818 at p<0.001). The peak activation of all seven muscles occurred in the mid-range of elevation among patients with anterior shoulder instability whereas subjects spread peak activation of all 7 muscles throughout range. Peak magnitude of patients' infraspinatus muscle was six times higher (sagittal: t = -8.6428, coronal: t = -54.1578 at p<0.001) but magnitude of their supraspinatus was lower (sagittal: t = 36.2507, coronal: t = 35.9350 at p<0.001) that subjects.

CONCLUSIONS

Patients with anterior shoulder instability adopted a "stability before mobility" neuro-motor control strategy to initiate elevation and a "stability at all cost" strategy to ensure concavity compression in the mid-to-150 degrees of elevation in both sagittal and coronal planes.

Posteroinferior labral cleft at direct CT arthrography of the shoulder by using multidetector CT: is this a normal variant?

PURPOSE

To describe a posterior labral cleft at direct computed tomographic (CT) arthrography of the shoulder by using multidetector CT and to compare this finding with a true posterior labral tear.

MATERIALS AND METHODS

Institutional ethics review board approval was obtained, and informed consent was waived. One hundred twenty-seven shoulders in 126 patients were examined with direct CT arthrography by using 16- or 64-section multidetector CT and arthroscopy. Two musculoskeletal radiologists retrospectively reviewed CT arthrographic images for the presence, location, and size of a posterior labral tear, defined as a detectable contrast material-filled focal discontinuity of the labrum on an axial image, proved by using arthroscopy. A posterior labral cleft was defined as a false-positive lesion at CT arthrography that was proved to be a normal finding arthroscopically. Sensitivity, specificity, accuracy, positive and negative predictive values of tears and clefts were determined; incidence according to the patient's age and sex and the laterality (right or left shoulder), location, and size of the lesion were compared.

RESULTS

In 127 shoulders, radiologists 1 and 2 found 12 and 11 posterior labral tears, respectively, seen exclusively in male patients with posterior instability. Radiologist 1 observed 24 (18.9%) clefts, and radiologist 2 observed 20 (15.7%) clefts, seen more commonly in female patients (P = .037 for radiologist 1, P = .026 for radiologist 2) and in the inferior quadrant of the posterior labrum (along 7- to 8-o'clock positions, P < .05 for both radiologists); these clefts were shallower than labral tears (P = .005 for radiologist 1, P = .025 for radiologist 2).

CONCLUSION

At direct CT arthrography, a labral cleft may be a normal variation of the posterior labrum.

Current concepts and advances: computerized tomography in sports medicine

Computed tomography (CT) is a widely used imaging technique. With the introduction of multidetector row technology, CT has been further refined. Although the focus of this transformation has been body and cardiac imaging, orthopedic imaging has benefited greatly. Specifically, the improvements in CT have made it possible to obtain submillimeter-thick slices that enable the creation of high-resolution multiplanar reformations from a single scan. These images usually are indistinguishable from direct plane acquisitions and provide unparalleled detail. Additionally, the factors responsible for causing CT image artifacts when hardware is present are much better understood and the improvements in CT technique and technology can be exploited to provide better images of patients with orthopedic hardware. The detailed multiplanar visualization of joints facilitates CT arthrography that has undergone a renaissance. CT arthrography is useful in the very large athlete or patient, the claustrophobic, and for those patients who fail a conventional magnetic resonance examination or magnetic resonance arthrogram.

Perianchor radiolucency after knotless anchor repair for shoulder instability: correlation with clinical results of 69 cases

BACKGROUND

Although there would seem to be a logical relationship between radiolucency around the suture anchor and clinical result in Bankart repair, the correlation has not been demonstrated so far.

HYPOTHESIS

Knotless suture anchor is a viable alternative for arthroscopic Bankart repair, but postoperative radiologic findings of radiolucency around anchors are correlated with poor clinical results.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Sixty-nine consecutive patients with Bankart lesions were treated with arthroscopic reconstruction using knotless metal suture anchors. The mean follow-up was 40 months. Clinical and radiologic analysis was performed retrospectively. A new concept of perianchor radiolucency was introduced and, according to this radiologic finding, patients were divided into 2 subgroups: the perianchor radiolucency group and those who did not reveal perianchor radiolucency. The perianchor radiolucency group was further subdivided by shape and location. "Root type" was defined as a radiolucent halo at the root of the anchor, and perianchor radiolucency without any root halo was named "branch type." Location of perianchor radiolucency was described as above or below the equator of the glenoid.

RESULTS

After operation, the mean Rowe score increased to 93.8 from 43.1, and computed tomography arthrogram showed a 97% healing rate. Reoperations were performed due to 1 case of redislocation and 2 cases of anchor arthropathy. All these reoperated cases revealed perianchor radiolucency before reoperation. Other than reoperated cases, 2 patients showed apprehension at final evaluation. The perianchor radiolucency group had a significantly lower Rowe scores than the group that showed no perianchor radiolucency. Some of the patients in the perianchor radiolucency group had peculiar radiologic findings frequently associated with complications. The radiologic findings that consisted of root-type perianchor radiolucency located below the equator of the glenoid was termed the "ominous sign." Osteophytes of the humeral head together with the ominous sign is considered a warning sign of forthcoming progression of anchor arthropathy, and the authors suggest early surgical intervention with these findings.

CONCLUSION

After Bankart repair using knotless suture anchor, the ominous sign might be an important warning sign for possible forthcoming complications including redislocation, anchor arthropathy, and residual instability.

Multidirectional instability of the glenohumeral joint

The concept of multidirectional instability (MDI) was introduced as an important clinical entity in 1980. Previously, it had received little mention in the literature and was not considered to be clinically relevant. MDI is a symptomatic glenohumeral subluxation or dislocation occurring in more than one direction. The basic pathology of this condition is a loose and redundant joint capsule. Most patients with MDI can be treated successfully by conservative methods, such as patient education, a shoulder girdle strengthening program, or modification of the patient's routine activity.

Magnetic resonance arthrography (MRA) in the postoperative shoulder

To evaluate changes in capsular mechanisms and the labroligamentous complex with magnetic resonance arthrography (MRA) after shoulder surgery and to establish possible criteria for the expected post-operative appearance of the shoulder. MRA of the shoulder was performed in 16 patients, before and 6 months after undergoing arthroscopic surgery for recurrent unidirectional dislocation. MR studies were performed after application of a constant amount of contrast solution (2 mmol Gd-DTPA). Axial and coronal oblique T1-weighted images were obtained with and without fat suppression techniques. Anterior (a) and posterior (p) capsular distances were measured, and the p/a ratio was established. Capsule thickness, capsular leaking, estimation of the volume of the axillary recess, appearance of the glenohumeral ligaments, and evidence of labral lesions were compared on pre- and postoperative images. Mean anterior capsular distance (a) decreased from 9.73 +/- 1.03 mm preoperatively to 5.27 +/- 2.49 mm postoperatively, whereas dorsal capsular distance (p) increased from 6.13 +/- 2.36 to 8.93 +/- 2.37. The p/a ratio increased from 0.64 +/- 0.25 to 2.36 +/- 2.54 (p = 0.007). Capsular leaking was suspected preoperatively in seven patients, but was not evident postoperatively. Capsular thickness and the estimated volume in the axillary recess did not change significantly. Contrast extension into pre-existent labral tears (nine patients) decreased or were not evident postoperatively. Changes in the appearance of the glenohumeral ligaments were found in six patients. Changes in capsular distances might be indicative of a decreased capsular laxity and could be a valuable criterion in the evaluation of the postoperative shoulder. Postoperative follow-up of labral tears is demonstrated by a decrease in contrast extension into or under a tear. Reactive capsular thickening or scar tissue formation can be reactive or preexistent. Changes in ligaments might be secondary to surgery. MRA may be helpful in the reevaluation of patients with suspected recurrent instability.

A practical approach to imaging of the shoulder with emphasis on MR imaging

Our understanding of shoulder disorders has changed considerably as a result of improved diagnostic tools, such as arthroscopy and multiplanar imaging modalities. The diagnosis of the cause of shoulder pain can be difficult because a spectrum of disorders, including cervical spine disease, acromioclavicular arthritis, and shoulder instability. Impingement and denervation syndromes can present with similar clinical findings. Accurate depiction of anatomic abnormalities is important for treatment planning. The purpose of this article is to report on the application of available imaging modalities, with emphasis on MR imaging. A strategy for the appropriate use of these studies and their variations of technique is also provided.

A prospective evaluation of a new physical examination in predicting glenoid labral tears

We studied 62 patients (40 men and 22 women) with an average age of 28 years over a 28-month period who presented with shoulder pain that was refractory to 3 months of conservative management. Patients with a prior glenohumeral dislocation or a rotator cuff tear were excluded. The "crank" test was performed with the arm elevated to 160 degrees in the scapular plane of the body, loaded axially along the humerus, and with maximal internal and external rotation. Although similar tests have been described, the crank test is a new examination previously unreported. Half of the patients (31) had a positive crank test. Arthroscopy performed on all 62 patients revealed glenoid labral tears in 32 patients. Two patients who had positive crank tests did not have labral tears but had partial-thickness, articular-side rotator cuff tears. The sensitivity of the crank test was 91%, the specificity was 93%, the positive predictive value was 94%, and the negative predictive value was 90%. With these data, the crank test fulfills the criteria as a single physical examination test that is highly accurate for the preoperative diagnosis of glenoid labral tears. Accordingly, expensive imaging modalities currently used in this patient population may be employed less in the future.

Bony changes of the glenoid as a consequence of shoulder instability

Among 500 skeletons of mature individuals, 27 showed signs of shoulder instability as indicated by the presence of a glenoid rim avulsion fracture, a bony Bankart lesion, with an anterior or posterior Hill-Sachs defect. Twenty-two of these glenoid lesions were anterior, and five were posterior. This is a higher prevalence than reported in clinical studies. With few exceptions the pathologic changes in the bony glenoid were well circumscribed and not found in conjunction with diffuse arthritic changes. These findings do not support prophylactic shoulder stabilization to avoid the development of arthritic changes of a generalized and major degree.

Diagnosis of glenoid labral tears. A comparison between magnetic resonance imaging and clinical examinations

We studied 54 patients with shoulder pain secondary to anterior instability or glenoid labral tears refractory to 6 months of conservative management with no evidence of rotator cuff lesions. All patients had sufficient preoperative clinical data, magnetic resonance imaging, and shoulder arthroscopy results for analysis. The ability to predict the presence of a glenoid labral tear by physical examination was compared with that of magnetic resonance imaging (conventional and arthrogram) and confirmed with arthroscopy. There were 37 men and 17 women (average age, 34 years) in the study group. Of this group, 64% were throwing athletes and 61% recalled specific traumatic events. Clinical assessment included history with specific attention to pain with overhead activities, clicking, and instances of shoulder instability. Physical examination included the apprehension, relocation, load and shift, inferior sulcus sign, and crank tests. Shoulder arthroscopy confirmed labral tears in 41 patients (76%). Magnetic resonance imaging produced a sensitivity of 59% and a specificity of 85%. Physical examination yielded a sensitivity of 90% and a specificity of 85%. Physical examination is more accurate in predicting glenoid labral tears than magnetic resonance imaging. In this era of cost containment, completing the diagnostic workup in the clinic without expensive ancillary studies allows the patient's care to proceed in the most timely and economic fashion. Glenoid labral tears have been associated with overhead throwing activities, trauma, and shoulder instability. Assessment of an athlete with shoulder pain should take into account a careful history of clicking sounds or catching, symptoms with overhead activities, reports of instability, or previous trauma. On physical examination, patients with labral tears often demonstrate objective instability with or without clicking or catching during glenohumeral rotation. Plain radiographs have not been helpful, and radiologists have relied on techniques from arthrogram to arthrotomogram, CT arthrogram, magnetic resonance imaging (MRI), and MR arthrogram to assist in the diagnosis. Various sensitivities and specificities have been reported for these tests. However, a large degree of intra- and interobserver variability has been demonstrated, and the degree to which these studies are helpful in preoperative planning has been questioned. No previous study to our knowledge has involved MRI in a direct comparison of other diagnostic modalities. Therefore, the purpose of this study is to investigate the accuracy of MRI and physical examination in the diagnosis of glenoid labral tears.

The Glenoid Labrum: Basic Science and Clinical Correlation

Rehabilitation of the shoulder offers many challenges. Arthroscopic and advanced imaging techniques have facilitated significant changes in our perception and management of glenoid labral pathology. Despite this progress, controversies involving the glenoid labrum continue to exist. This paper presents an overview of glenoid labral histology, morphology, and vascularity. Labral injuries are investigated and categorized. The management of glenoid labral pathology is discussed along with ramifications for shoulder rehabilitation.

Three-dimensional MRI of the glenoid labrum

The objective of this study was to assess the accuracy of three-dimensional (3D) magnetic resonance imaging (MRI) reformation in the evaluation of tears of the glenoid labrum complex (GLC). Fifty-five shoulders were evaluated by MRI using standard spin-echo sequences. Gradient-refocused-echo axial projections were used to assess the GLC on the two-dimensional (2D) studies. Three-dimensional Fourier transform multiplanar gradient-recalled imaging with a resolution of 0.7 mm was also performed in all patients. Independent analyses of the anterior and posterior labra were performed in a blinded manner for both the 2D and 3D studies by three experienced musculoskeletal radiologists. Observations of the imaging studies were compared with the videoarthroscopic findings. The appearance of the GLC was rated on a scale of 0 to 4 (0-2 = normal, 3, 4 = abnormal or torn). The diagnostic confidence was averaged from the three reader's scores. Anterior labral tears were effectively detected with sensitivities of 89% and 96% and specificities of 96% and 100% (P < 0.0001) for the 2D and 3D studies, respectively. For posterior labral tears, the sensitivity and specificity of the 2D method were 47% and 98%, respectively. The sensitivity and specificity of the 3D volume sequence were 53% and 98%, respectively. The lower sensitivity of both imaging methods for detecting posterior labral tears may be influenced by the smaller number (n = 5) of arthroscopically confirmed cases in our study and reflects the difficulty of visualizing the posteroinferior borders of the GLC with present MRI techniques.

Magnetic resonance imaging of the glenoid labrum in anterior shoulder instability

Detachment of the anterior inferior labrum and inferior glenohumeral ligament complex from the glenoid is a common lesion encountered in anterior shoulder instability while other types of labral lesions are associated with symptoms that mimic instability. Accurate delineation of labral lesion is, therefore, key in managing shoulder problems. In a prospective double-blinded fashion, we compared the magnetic resonance imaging findings with those noted at surgery in 33 patients with possible anterior shoulder instability. Of 28 surgically confirmed labral lesions, 21 were detected by imaging. Sensitivity was 75%, specificity 100%, while positive and negative predictive values were 100% and 41%, respectively. Overall accuracy was 79%. Based on a literature review and our clinical experience, we developed a classification of glenoid labra according to the type and severity of the lesions. Method of treatment correlated with clinical outcome, using this system, to a statistically significant level. Unfortunately, this system enabled accurate classification with magnetic resonance imaging in only 7 of 33 (21%) labra, with the precision necessary to affect surgical planning in our series. We conclude that magnetic resonance imaging is not useful in the surgical planning for most patients with obvious anterior shoulder instability.

[Limbus diagnosis by computerized tomography after initial traumatologic dislocation of the shoulder]

This paper shows a retrospective analysis of 98 shoulder joint CT scans after traumatic primary anterior dislocation in the period of 1988 till December 1991. The intraoperative findings and the X-ray characteristics beside arthrographic and MRI examinations led us to a classification of four types by pathomorphologic aspects, the type of the tear correlated to the degree of instability. For anterior limbus tear and lesions, a CT scan gives a diagnostic sensitivity of more than 90% (own rate 94.6%). Concerning our patients, the total lesions rate of 77.6% following first traumatic dislocation justifies a progressive examination and evaluation of the joint structures, that enhance further dislocations. Hereby, inspite of its invasivity, joint CT scan have, in comparison to other diagnostic procedures, proved to be routinely useful.

Saline magnetic resonance arthrography in the evaluation of glenohumeral instability

Sixty-five patients underwent magnetic resonance (MR) shoulder arthrography. Forty-eight of these patients underwent examination under anesthesia (EUA). MR images were retrospectively evaluated for signs felt to be imaging indicators of shoulder instability, including evaluation of various capsular measurements and the presence of glenoid labral tears, as well as Hill-Sachs fractures. Statistical analysis of the results showed that no correlation between capsular indicators with EUA-documented instability was found. However, there was a statistically significant correlation between the presence of a Bankart cartilaginous deformity (p = 0.000) and Hill-Sachs fractures (p = 0.022) with EUA-documented instability. Sensitivity to labral tears was 89% and specificity was 98%, whereas Hill-Sachs fracture detection was 69% and 87%, respectively. We believe that MR saline arthrography is of benefit in the evaluation of the anterior labrum when unenhanced MR imaging is inconclusive, and we speculate on the role of MR arthrography as a primary investigative tool.

Arthroscopic treatment of glenoid labral tears

We reviewed 52 consecutive patients who had undergone arthroscopic labral debridement. The average age was 29 and there were 35 men and 17 women. At operation, 27 patients had superior labrum anterior and posterior (SLAP) lesions, 20 patients had anteroinferior labral lesions, and 5 patients had posterior labral lesions. Despite the fact that, preoperatively, none of these patients had a history of dislocations or clinically evident instability, 70% of the patients with superior labral lesions, and all of those with anteroinferior and posterior lesions had instability on examination under anesthesia. The average followup was 36 months. At 1 year after arthroscopy, 78% of the patients with superior lesions had excellent relief compared with 30% of the patients in the anteroinferior group. At 2 years followup, these results decreased to 63% and 25%, respectively, and only 45% of the patients with superior labral lesions and 25% of those with anteroinferior lesions had returned to their previous athletic performance level. Four patients required a reoperation: 2 for instability and 2 for impingement. We conclude that occult instability is frequently present in patients with glenoid labral tears. The overall results are not encouraging, but this procedure may have an indication for short-term goals in competitive athletes or those who are willing to accept some compromise in function.

A prospective comparison of computerized arthrotomography and magnetic resonance imaging of the glenohumeral joint

Twenty-five patients with shoulder instability or shoulder pain of undetermined etiology were prospectively evaluated with magnetic resonance imaging and computerized arthrotomography. Actual lesions were determined by arthroscopy or at the time of open surgical repair. The images obtained were interpreted independently by three radiologists blinded to both surgical results and the results of previous diagnostic tests. Sensitivity, specificity, and accuracy were determined for each imaging technique for a variety of pathologic entities, including anterior and posterior labral abnormalities, capsular redundancy, biceps-labral complex abnormalities, humeral head (Hill-Sachs) impression lesions, and glenohumeral loose bodies. Analysis of imaging techniques also included construction of receiver operator curves for labral abnormalities. Magnetic resonance imaging showed better diagnostic results in the evaluation of glenoid labral and humeral head impression lesions (P < 0.05). Both imaging techniques were equally successful in identifying biceps-labral lesions and intraarticular loose bodies within the glenohumeral joint. Neither imaging technique was consistent in the evaluation of capsular redundancy. Receiver operator curve analysis confirmed that magnetic resonance imaging was the more accurate imaging study in evaluating anterior and posterior glenoid labral abnormalities.

Magnetic resonance imaging of the glenoid labrum

Shoulder complaints are common in the athletic population. Successful treatment is dependent upon the ability to correctly identify the pathologic changes associated with a specific disorder and arrive at an accurate diagnosis. Labral abnormalities are traditionally associated with glenohumeral instability. Isolated labral tears or degenerative changes may also cause shoulder dysfunction. A reliable clinical tool to assess the status of the labrum would be useful for diagnosis and management of shoulder disorders. The magnetic resonance images of 48 shoulders that had subsequent surgical examination of their labra were reviewed with respect to labral appearance. Labra appearing as abnormal were further classified as torn, degenerative, or eroded. Surgical examination was used as the reference standard. Magnetic resonance imaging demonstrated high levels of sensitivity, specificity, positive and negative predictive values, and accuracy for evaluation of the glenoid labrum. Magnetic resonance imaging is a reliable and accurate method for depicting the status of the glenoid labrum. Magnetic resonance imaging appearance of the labrum may assist the clinician in distinguishing the varying forms of shoulder dysfunction and facilitate diagnosis and effective treatment.