Quantitative and qualitative analyses of subacromial impingement by kinematic open MRI

Investigating the reliability and validity of subacromial space measurements using ultrasound and MRI

BACKGROUND

While ultrasound (US) measures of the subacromial space (SAS) have demonstrated excellent reliability, measurements are typically captured by experts with extensive ultrasound experience. Further, the agreement between US measured SAS width and other imaging modalities has not been explored. This research evaluated the agreement between SAS measures captured by novice and expert raters and between US and magnetic resonance imaging (MRI). This study also evaluated the effect of US transducer tilt on measured SAS.

METHODS

Nine men and nine women participated in this study. US images were captured by a novice and expert with the participant in both seated and supine positions. An inclinometer was fixed to the US probe to measure transducer tilt. SAS width was measured in real time from freeze framed images. MRI images were captured, and the humerus and acromion manually segmented. The SAS width was measured using a custom algorithm.

RESULTS

Intraclass correlation coefficients (ICCs) between novice and expert raters were 0.74 and 0.63 for seated and supine positions, respectively. Intra-rater agreement was high for both novice (ICC = 0.83-0.84) and expert (ICC ≥ 0.94) raters. Agreement between US and MRI was poor (ICC = 0.21-0.49) but linearly related.

CONCLUSIONS

Moderate agreement between novice and expert raters was demonstrated, while the agreement between US and MRI was poor. High intra-rater reliability within each rater suggests that US measures of the SAS may be completed by a novice with introductory training.

Comparison of acromiohumeral distance and glenohumeral internal rotation angle between the empty can test and modified empty can test: "thumb pointing down" versus "elbow pointing laterally"

BACKGROUND

During the empty can test, the direction of the thumb (downward) has been widely used as an instruction for producing glenohumeral internal rotation. However, the combination of forearm pronation and thumb motion as a compensatory movement could contribute to the lack of glenohumeral internal rotation during the empty can test. This study aimed to compare the glenohumeral internal rotation angle between the conventional empty can (with thumb direction) and modified empty can tests (with elbow direction), as well as the acromiohumeral distance between the full can, conventional empty can, and modified empty can tests.

METHODS

In this laboratory study, we measured the glenohumeral internal rotation angle using a motion sensor and the acromiohumeral distance using ultrasonography during the following tests: full can test (thumb pointing up), conventional empty can test (thumb pointing down), and modified empty can test (elbow pointing laterally) in 20 healthy subjects.

RESULTS

Compared with the conventional empty can test, the glenohumeral internal rotation angle was significantly greater during the modified empty can test (p < 0.05). Furthermore, the acromiohumeral distance measured in the modified empty can test was significantly less than that in the full can test (p < 0.001) and conventional empty can test (p < 0.001). However, there was no difference in the acromiohumeral distance between the full can test and the conventional empty can test (p > 0.017).

CONCLUSIONS

During the empty can test, the instructions should be given to patients based on the elbow direction (elbow pointing laterally). The modified empty can test can produce full glenohumeral internal rotation, compared with instructions based on the thumb direction (thumb pointing down). Consequently, the modified empty can test can produce a more decreased subacromial space.

Effects of deep friction massage and dry needling therapy on night pain and shoulder internal rotation in subacromial pain syndrome: 1-year follow up of a randomised controlled trial

Background/Aims

Shoulder problems are common in the general population. The aim of this research was to compare the short and long-term effects of trigger point deep friction massage and trigger point dry needling therapy on rest, activity, and the intensity of night shoulder pain and shoulder internal rotation in Subacromial Pain Syndrome.

Methods

Out of 73 outpatients diagnosed with Subacromial Pain Syndrome, 40 were selected according to agreed criteria and were randomly assigned to two groups. A total of 19 patients received trigger point deep friction massage and 21 received trigger point dry needling therapy. The trigger point deep friction massage group received treatment over 3 weeks and the trigger point dry needling therapy group received treatments over 4 weeks. Both groups received six treatment sessions and a programme of post-treatment exercises. The shoulder internal rotation angle was measured using a goniometer, and pain intensities were measured using a visual analogue scale before the first session, after six sessions and after 1 year.

Results

According to both the short- and long-term data, significant improvements were seen in both groups for all parameters. However, when the groups were compared, no significant difference was found between the two interventions, although the trigger point deep friction massage intervention showed earlier improvements as the treatments could be carried out in 3 weeks, rather than the 4 weeks required for the trigger point dry needling therapy sessions.

Conclusions

Both trigger point deep friction massage and trigger point dry needling therapy are effective in improving pain and shoulder internal rotation. Both groups maintained significant clinical improvement throughout the year. Although both interventions produced good results, trigger point deep friction massage treatments were completed in a shorter time and so demonstrated earlier improvements. Therefore, Trigger point deep friction massage may be regarded as the preferred option, particularly as no equipment is needed and is a non-invasive method of treatment.

Increased T2 signal intensity in the distal clavicle does not justify acromioclavicular resection arthroplasty during rotator cuff repair

INTRODUCTION

Acromioclavicular (AC) arthropathy can contribute to shoulder pain; it can be treated surgically by distal clavicle resection (DCR). The aim of this study was to determine whether increased T2 signal intensity in the clavicle on MRI is an argument in favour of AC resection arthroplasty by DCR during rotator cuff repair.

METHODS

The MRI images from 107 shoulders in 107 patients were analysed. We looked for statistical relationships and correlations between shoulders with T2 hyperintensity (HI+) and those without (HI-) before surgery and then in shoulders with T2 hyperintensity (HI+) that underwent AC resection arthroplasty (AC+) and those who did not (AC-).

RESULTS

On MRI, T2 hyperintensity in the AC joint was correlated with sex (more often found in men) and radiological signs of AC arthropathy. There was no statistical correlation before surgery, particularly with AC pain, or after surgery, with outcomes in shoulders undergoing DCR.

CONCLUSION

When repairing rotator cuff tears, the presence of T2 hyperintensity on MRI in the distal clavicle is not a predictor of better clinical outcomes after AC resection arthroplasty is done. The AC pain may be related to the rotator cuff tear instead.

LEVEL OF EVIDENCE

II, prospective randomised study.

Effectiveness of new nerve blocks method on the articular branches of the suprascapular and subscapular nerves to treat shoulder pain

To evaluate the effectiveness and safety of performing nerve blocks on the articular branches of the suprascapular and subscapular nerves for the treatment of shoulder pain caused by various pathologies.Fifty-two patients with shoulder pain were included in this study. Suprascapular and subscapular nerve blocks were performed with 2.5 mL anesthetic solution (2 mL of 0.5% bupivacaine and 0.5 mL of 2 mg/mL dexamethasone). The subjects were evaluated before the procedure and 1, 3, and 6 months afterward by means of the numeric rating scale and the shoulder pain and disability index. A post-injection pain reduction of >50% and <50% was considered a positive and negative response to the blocks, respectively.After nerve blocks, the mean numeric rating scale and shoulder pain and disability index scores were significantly reduced from pre-injection values, and this effect persisted for 6 months after injection. The positive and negative response groups consisted of 31 (60%) and 21 (40%) patients, respectively. The positive response group showed significantly better outcomes on the numeric rating scale and shoulder pain and disability index compared with the negative response group. No patients reported adverse effects either during or after the procedure.Performing nerve blocks on the articular branches of the suprascapular and subscapular nerves resulted in positive outcomes for shoulder pain patients. Regardless of shoulder pathology, this new injection method can be safely used in shoulder pain patients.

Dynamic MRI for articulating joint evaluation on 1.5 T and 3.0 T scanners: setup, protocols, and real-time sequences

Dynamic magnetic resonance imaging (MRI) is a non-invasive method that can be used to increase the understanding of the pathomechanics of joints. Various types of real-time gradient echo sequences used for dynamic MRI acquisition of joints include balanced steady-state free precession sequence, radiofrequency-spoiled sequence, and ultra-fast gradient echo sequence. Due to their short repetition time and echo time, these sequences provide high temporal resolution, a good signal-to-noise ratio and spatial resolution, and soft tissue contrast. The prerequisites of the evaluation of joints with dynamic MRI include suitable patient installation and optimal positioning of the joint in the coil to allow joint movement, sometimes with dedicated coil support. There are currently few recommendations in the literature regarding appropriate protocol, sequence standardizations, and diagnostic criteria for the use of real-time dynamic MRI to evaluate joints. This article summarizes the technical parameters of these sequences from various manufacturers on 1.5 T and 3.0 T MRI scanners. We have reviewed pertinent details of the patient and coil positioning for dynamic MRI of various joints. The indications and limitations of dynamic MRI of joints are discussed.

Shoulder kinematics impact subacromial proximities: a review of the literature

BACKGROUND

Alterations in glenohumeral and scapulothoracic kinematics have been theorized to contribute to rotator cuff pathology by impacting the magnitude of the subacromial space.

OBJECTIVE

The purpose of this review is to summarize what is currently known about the relationship between shoulder kinematics and subacromial proximities.

CONCLUSIONS

A variety of methods have been used to quantify subacromial proximities including photographs, MR imaging, ultrasonography, and single- and bi-plane radiographs. Changes in glenohumeral and scapulothoracic kinematics are associated with changes in subacromial proximities. However, the magnitude and direction of a particular motion's impact on subacromial proximities often vary between studies, which likely reflects different methodologies and subject populations. Glenohumeral elevation angle has been consistently found to impact subacromial proximities. Plane of humeral elevation also impacts subacromial proximities but to a lesser degree than the elevation angle. The impact of decreased scapulothoracic upward rotation on subacromial proximities is not absolute, but instead depends on the angle of humerothoracic elevation. The effects of scapular dyskinesis and humeral and scapular axial rotations on subacromial proximities are less clear. Future research is needed to further investigate the relationship between kinematics and subacromial proximities using more homogenous groups, determine the extent to which compression and other factors contribute to rotator cuff pathology, and develop accurate and reliable clinical measures of shoulder motion.

Parameterization of proximal humerus locking plate impingement with in vitro, in silico, and in vivo techniques

BACKGROUND

Locked plating of displaced proximal humeral fractures is common, but rates of subacromial impingement remain high. This study used a multidisciplinary approach to elucidate the relationships between common surgical parameters, anatomic variability, and the likelihood of plate impingement.

METHODS

The experiment was completed in 3 phases. First, a controlled in vitro experiment was conducted to simulate impingement. Second, a dynamic in silico musculoskeletal model modeled changes to implant geometry, surgical techniques, and acromial anatomy, where a collision detection algorithm was used to simulate impingement. Finally, in vivo shoulder kinematics were recorded for 9 activities of daily living. Motions that created a high likelihood of impingement were identified.

RESULTS

Of simulated impingement events, 73.9% occurred when the plate was moved proximally, and 84% occurred when acromial tilt was 20° or 25°. Simulations of impingement occurred at cross-body adduction angles between 10° and 50°. Impingement occurred at an average of 162.0° ± 14.8° abduction with 10 mm distal plate placement, whereas the average was 72.1° ± 11.4° with 10 mm proximal placement. A patient may encounter these shoulder angles when performing activities such as combing one's hair, lifting an object overhead, and reaching behind one's head.

DISCUSSION AND CONCLUSION

Proximal implant placement and decreases in acromial tilt play major roles in the likelihood of impingement, whereas plate thickness and humeral head center of rotation should also be considered. Careful preoperative planning that includes these factors could help guide operative decision making and improve clinical outcomes.

Multimodality imaging of subacromial impingement syndrome

Subacromial impingement syndrome results from irritation of the tendons of the rotator cuff muscles in the subacromial space and may manifest as a range of pathologies. However, subacromial impingement is a dynamic condition for which imaging reveals predisposing factors but no pathognomonic indicators. Also, the usual imaging features of subacromial impingement may be seen in symptomatic and asymptomatic patients. Therefore, imaging is able to detect tears and describe the risk factors of impingement but cannot confirm subacromial impingement. Radiographs allow assessment of the morphology of the acromion and its lateral extension by means of the acromial index and the critical shoulder angle, which may increase in cases of subacromial impingement. Ultrasound is necessary to evaluate a tendon tear and is the only tool that provides dynamic information, which is essential to assessing dynamic conditions. Magnetic resonance imaging (MRI) allows the assessment of associated intraarticular abnormalities, joint effusion, and bone marrow edema. The objective of this article is to provide an overview of the pathophysiology and clinical manifestations of subacromial impingement and discuss recent advances in the imaging of subacromial impingement and the role of radiography, ultrasound, and MRI in differentiating normal from pathologic findings.

Ultrasound evaluation of the subacromial space in healthy subjects performing three different positions of shoulder abduction in both loaded and unloaded conditions

BACKGROUND

Subacromial space (SS) narrowing may result in unsafe contact of rotator cuff tendons and bursa with the acromion, possibly promoting rotator cuff pathologies and pain. We measured SS in asymptomatic subjects after three movements employed for shoulder muscles' training.

PARTICIPANTS AND MAIN OUTCOME MEASURES

Twenty-five males (age 24±5years; stature 175±8 cm; body mass 74±12 kg) underwent SS ultrasound evaluation while executing with (WL) and without (NL) 4-kg load: 90° shoulder abduction (SA) without humerus rotation (90°_neutral); 90° SA maximal humeral external rotation (90°_er); maximum SA (above 90°) during upright row (UR). For inter-operator reliability analysis, a subset of 12 subjects was assessed by two operators.

RESULTS

Intra/inter-operator reliability coefficients were high (ICC>0.87; standard error of measurement range: 0.23-0.51 mm; minimum detectable change range: 0.61-1.79 mm). ANOVA revealed significant differences between loads (p = 0.003, η² = 0.37) and angles (p < 0.001, η² = 0.72), and interaction (p = 0.004, η² = 0.45). Normalized SS values WL were higher at 90°_er vs. 90°_neutral and UR (p < 0.001 for both). Differences in NL were found between 90°_neutral and both 90°_er (p = 0.002) and UR (p = 0.009).

CONCLUSIONS

When holding a 4-kg load, SS is larger at 90°_er than at 90°_neutral and UR shoulder abduction positions. In unloaded condition, SS at 90°_neutral is reduced compared to 90°_er and UR.