Rotator cuff tear pain and tear size and scapulohumeral rhythm

Fully automatic algorithm for detecting and tracking anatomical shoulder landmarks on fluoroscopy images with artificial intelligence

OBJECTIVE

Patients with rotator cuff tears present often with glenohumeral joint instability. Assessing anatomic angles and shoulder kinematics from fluoroscopy requires labelling of specific landmarks in each image. This study aimed to develop an artificial intelligence model for automatic landmark detection from fluoroscopic images for motion tracking of the scapula and humeral head.

MATERIALS AND METHODS

Fluoroscopic images were acquired for both shoulders of 25 participants (N = 12 patients with unilateral rotator cuff tear, 6 men, mean (standard deviation) age: 63.7 ± 9.7 years; 13 asymptomatic subjects, 7 men, 58.2 ± 8.9 years) during a 30° arm abduction and adduction movement in the scapular plane with and without handheld weights of 2 and 4 kg. A 3D full-resolution convolutional neural network (nnU-Net) was trained to automatically locate five landmarks (glenohumeral joint centre, humeral shaft, inferior and superior edges of the glenoid and most lateral point of the acromion) and a calibration sphere.

RESULTS

The nnU-Net was trained with ground-truth data from 6021 fluoroscopic images of 40 shoulders and tested with 1925 fluoroscopic images of 10 shoulders. The automatic landmark detection algorithm achieved an accuracy above inter-rater variability and slightly below intra-rater variability. All landmarks and the calibration sphere were located within 1.5 mm, except the humeral landmark within 9.6 mm, but differences in abduction angles were within 1°.

CONCLUSION

The proposed algorithm detects the desired landmarks on fluoroscopic images with sufficient accuracy and can therefore be applied to automatically assess shoulder motion, scapular rotation or glenohumeral translation in the scapular plane.

CLINICAL RELEVANCE STATEMENT

This nnU-net algorithm facilitates efficient and objective identification and tracking of anatomical landmarks on fluoroscopic images necessary for measuring clinically relevant anatomical configuration (e.g. critical shoulder angle) and enables investigation of dynamic glenohumeral joint stability in pathological shoulders.

KEY POINTS

• Anatomical configuration and glenohumeral joint stability are often a concern after rotator cuff tears. • Artificial intelligence applied to fluoroscopic images helps to identify and track anatomical landmarks during dynamic movements. • The developed automatic landmark detection algorithm optimised the labelling procedures and is suitable for clinical application.

Long-lasting decreased pain threshold negatively affects functional recovery after arthroscopic rotator cuff repair

PURPOSE

The relationship between sensitization and postoperative function in patients undergoing arthroscopic rotator cuff repair (ARCR). The purpose of this study was to evaluate the effect of pre-and postoperative reductions in the pressure pain threshold (PPT) on postoperative clinical outcomes in patients with ARCR and investigate changes in PPT and clinical outcomes resulting from postoperative administration of weak opioids activating the central inhibitory system.

METHODS

This retrospective study included patients who underwent primary ARCR, categorized into Group A (excellent/good Constant scores) and B (fair/poor Constant scores). In a complementary study, patients were randomized to the Control or Tramadol groups. Both studies evaluated the PPT, visual analog scale, active range of motion (ROM), Constant score, and retear rates pre-and postoperatively.

RESULTS

In the primary study with 158 patients, those with poor clinical outcomes exhibited significantly lower PPT at the affected shoulder preoperatively at 3 months postoperatively compared to those with good outcomes. The PPT of the affected side was lower than that of the uninvolved side not only at 1 and 3 months but also preoperatively and at 6 months in the poor outcome group. In the secondary study involving 96 patients, weak opioid administration was associated with increased PPT for 3 months, improved ROM at 3 months postoperatively, and reduced postoperative pain 1 year postoperatively.

CONCLUSION

Patients experiencing poor postoperative clinical outcomes exhibited prolonged lowered PPT. Lowered PPT due to sensitization may adversely affect functional recovery and pain perception. Elevating PPT using weak opioids improved clinical outcomes during the acute perioperative period after ARCR.

LEVEL OF EVIDENCE

III.

Changes in blood flow in the dorsal scapular artery and relationship to shoulder joint function in rotator cuff tears

Background

One of the pain-related factors in rotator cuff tears (RCTs) is abnormal scapular motion, which is thought to be related to the levator scapulae muscle activation. Additionally, attention has recently focused on the peak systolic velocity (PSV) as one of the causes of pain, but blood flow outside of the vessels supplying the rotator cuff has not been clarified. This study aimed to determine the difference in PSV in the dorsal scapular artery (DSA), which is the vessel that supplies the levator scapulae muscles, and the association between PSV and pain and shoulder function in patients with RCTs between the tear and nontear sides.

Methods

This study included 31 patients with RCTs with tear and nontear sides. Magnetic resonance imaging and radiographic examinations included Cofield classification, Goutallier classification, thickening of the coracohumeral ligament, and measurement of the acromiohumeral interval. Clinical evaluation included an automatic range of motion (ROM) for flexion, abduction, and external rotation (ER), a visual analog scale, and the Shoulder36. PSV was evaluated using ultrasound pulsed Doppler mode to assess PSV of DSA. The PSV of DSA on the first rib was drawn in the medial aspect of the suprascapular angle in the long axis, and the maximum PSV waveform was measured three times. The average value was used for further analysis.

Results

The PSV in the DSA was significantly higher (P = .04, 95% confidence interval: 0.2-7.6) on the tear (22.6 ± 7.4 cm/s) than the nontear sides (18.9 ± 6.9 cm/s). In addition, a significant negative correlation (r = -0.46, P = .0087) was found between PSV in DSA and ER on the tear side.

Conclusion

This study revealed a significantly increased PSV in the DSA on the tear side in RCTs and negatively correlated with ER ROM. The results suggest that increased PSV in the DSA may contribute to ER ROM limitation in the glenohumeral joint.

Return of Scapulohumeral Rhythm in Patients After Reverse Shoulder Arthroplasty: A Midterm Stereoradiographic Imaging Analysis

BACKGROUND

Reverse shoulder arthroplasty (RSA) is associated with high rates of midterm complications including scapular notching, implant wear, and mechanical impingement. Scapulo-humeral rhythm (SHR), described by Codman in the 1920's, is defined as the ratio of glenohumeral motion to scapulothoracic motion. SHR is used as an indicator of shoulder dysfunction, as alterations in SHR can have profound implications on shoulder biomechanics. The determination of SHR can be hindered by soft-tissue motion artifacts and high radiation burdens associated with traditional surface marker or fluoroscopic analysis. EOS low dose stereoradiographic imaging analysis utilizing 3D model construction from a 2D X-ray series may offer an alternative modality for characterizing SHR following RSA.

METHODS

Patients (n=10) underwent an EOS imaging analysis to determine SHR at six and twelve months post-RSA. Leveraging 3D models of the implants, 2D/3D image registration methods were used to calculate relative glenohumeral and scapulothoracic positioning at 60, 90 and 120° of shoulder elevation. Subject-specific SHR curves were assessed and midterm changes in post-RSA SHR associated with follow-up time and motion phase were evaluated. Pearson correlations assessed associations between patient-specific factors and post-RSA SHR.

RESULTS

Mean post-RSA SHR was 0.81:1 across subjects during the entire midterm postoperative period. As a cohort, post-RSA SHR was more variable for 60-90° of shoulder motion. SHR for 90-120° of motion decreased (0.43:1) at twelve months post-RSA. Post-RSA SHR could be categorized using three relative motion curve patterns, and was not strongly associated with demographic factors such as BMI. 50% of subjects demonstrated a different SHR relative motion curve shape at twelve months post-RSA, and SHR during the 90120° of motion was found to generally decrease at twelve months.

CONCLUSION

Midterm post-RSA SHR was successfully evaluated using EOS technology, revealing lower SHR values (i.e., greater scapulothoracic motion) compared to normal values reported in the literature. SHR continued to change for some subjects during the midterm post-RSA period, with the greatest change during 90-120° of shoulder motion. Study findings suggest that future post RSA rehabilitation efforts to address elevated scapulothoracic motion may benefit from being patient-specific in nature and targeting scapular stabilization during 90-120° of shoulder motion. Level of Evidence: IV.

Ratio between 3D glenohumeral and scapulothoracic motions in individuals without shoulder pain

This study determined the ratio between glenohumeral and three-dimensional scapular motion during arm elevation and lowering in 91 individuals without shoulder pain. Scapular kinematics were assessed using an electromagnetic tracking device. Individuals performed 3 repetitions of elevation and lowering of the arm in the sagittal plane. Two-way ANOVAs (interval: 30-60°, 60-90°, 90-120° x phase: elevation and lowering) and paired t-tests were used for data analysis. For scapular internal/external rotation, lesser scapular internal rotation contribution was found during the 60-90° interval as compared to the 90-60° interval. Lesser scapular external rotation was identified in the 60-30° interval of arm lowering. The ratio was greater during arm elevation (1.89) compared to lowering (1.74) across the entire motion arc. For scapular upward rotation, greater upward rotation contribution was observed during arm elevation at the 30-60° interval, and less scapular downward rotation contribution in the final range of arm lowering. For scapular tilt, lesser scapular posterior tilt contribution during arm elevation was observed compared to arm lowering. The ratios between glenohumeral elevation/lowering and each individual scapulothoracic motion showed either differences between intervals and/or between elevation and lowering during specific intervals in healthy individuals.

Which Risk Factors Are Associated with Pain and Patient-reported Function in Patients with a Rotator Cuff Tear?

BACKGROUND

Patient-reported measures guide physicians in clinical decision making and therefore it is critical to determine what clinical factors are associated with these scores. Psychological and physical factors are commonly studied separately in patients with rotator cuff tears to determine their influence on outcomes. It is well established that psychological distress and scapular motion change in the presence of a symptomatic rotator cuff tear. However, these factors have not been studied simultaneously in a clinical setting to determine their association with shoulder outcome scores.

QUESTION/PURPOSE

After controlling for relevant confounding variables, what physical and psychological factors are associated with better (1) American Shoulder and Elbow Surgeons (ASES) scores for function, (2) ASES pain scores, and (3) total ASES scores?

METHODS

Fifty-nine patients with a potential symptomatic rotator cuff tear were recruited and agreed to participate in this cross-sectional study. Of those, 85% (50 of 59) met eligibility criteria for a primary diagnosis of an MRI-confirmed symptomatic partial-thickness or full-thickness rotator cuff tear without a history of shoulder surgery. Demographics, rotator cuff tear size, arm flexion, and clinical scapular motion during active arm flexion were evaluated by experienced examiners using standardized procedures. Patients completed the ASES questionnaire and the Optimal Screening for Prediction of Referral and Outcomes-Yellow Flag assessment form, which measures 11 different pain-related psychological distress symptoms. Three separate stepwise multiple linear regression analyses were performed for ASES pain, function, and total scores, with significance set at p < 0.05.

RESULTS

This model found that ASES function scores were associated with four factors: older age, increased arm flexion, increased percentage of scapular external rotation during arm flexion, and increased scores for acceptance of chronic pain (adjusted r2 = 0.67; p = 0.01). Those four factors appear to explain 67% of the observed variance in ASES function scores in patients with rotator cuff tears. Furthermore, increased percentage of scapular external rotation during arm flexion and decreased fear-avoidance beliefs related to physical activity scores (adjusted r2 = 0.36; p < 0.01) were associated with better ASES pain scores. And finally, better ASES total scores were associated with four factors: increased arm flexion, increased percentage of scapular upward rotation, increased scapular external rotation during arm flexion, and decreased fear-avoidance beliefs related to physical activity scores (adjusted r2 = 0.65; p < 0.001).

CONCLUSION

Our results favor adopting a comprehensive biopsychological clinical assessment for patients with rotator cuff tears that specifically includes humeral and scapular motion, fear-avoidance behaviors, and pain coping behaviors along with demographics. These particular physical and psychological variables were found to be associated with the ASES and, therefore, should be clinically examined simultaneously and targeted as part of a tailored treatment plan.

LEVEL OF EVIDENCE

Level II, prognostic study.

Scapular motion in the presence of rotator cuff tears: a systematic review

BACKGROUND

Rotator cuff tears (RCTs) remain a significant source of pain and disability in the shoulder. Although much work has been done in the study of the effects of rotator cuff tears on glenohumeral joint motion, much less has been done in understanding the effect of rotator cuff tearing on scapular motion or activation. It remains unknown whether scapular dyskinesis is causative or adaptive. The purpose of this study was to systematically review the literature to determine the relationship between rotator cuff tear presence and size on scapular motion, and if rotator cuff repair restored normal motion.

METHODS

A systematic review using PRISMA guidelines was accomplished to include all studies with biomechanical or clinical outcomes of scapular motion in the presence of RCTs. Studies were excluded if they involved shoulder arthroplasty, rotator cuff tendinopathy, or shoulder impingement without an RCT. From 530 initial references, 42 manuscripts were selected for full review and cross referenced. All studies were evaluated for inclusion and exclusion criteria.

RESULTS

Sixteen studies including 335 rotator cuff tears were included in the final review. There were several findings of interest in the literature. First, although all studies demonstrated scapular dyskinesis, they did not report a consistent pattern of motion in the presence of an RCT. In general, scapular posterior tilt was decreased, and scapular upward rotation was increased, especially in large tears, but the literature was unclear as to whether this was a result of the RCT or an adaptive attempt to maintain elevation. Larger RCTs resulted in more pronounced scapular dysfunction, but there was significant variability within studies. Further, dyskinesis was confounded by pain with more abnormal movement in symptomatic vs. asymptomatic RCTs, the latter of which were not different from normal healthy controls. Four studies addressed the effect of RCT on scapular mechanics and found that repair consistently improved it compared to the normal side, but the time to normalization varied between 5 months and 2 years.

CONCLUSION

Scapular motion is abnormal in the presence of an RCT, but the literature is inconsistent regarding a universally affected variable or consistent degree of scapular dysfunction in this setting. Furthermore, it remains unknown which changes are adaptive vs. pathologic. Understanding the relationship between rotator cuff tearing and scapular dyskinesis will require better biomechanical models that consider scapular dyskinesis in their design.

Adherence Tracking With Smart Watches for Shoulder Physiotherapy in Rotator Cuff Pathology: Protocol for a Longitudinal Cohort Study

Background

Physiotherapy is essential for the successful rehabilitation of common shoulder injuries and following shoulder surgery. Patients may receive some training and supervision for shoulder physiotherapy through private pay or private insurance, but they are typically responsible for performing most of their physiotherapy independently at home. It is unknown how often patients perform their home exercises and if these exercises are performed correctly without supervision. There are no established tools for measuring this. It is, therefore, unclear if the full benefit of shoulder physiotherapy treatments is being realized.

Objective

The proposed research will (1) validate a smartwatch and machine learning (ML) approach for evaluating adherence to shoulder exercise participation and technique in a clinical patient population with rotator cuff pathology; (2) quantify the rate of home physiotherapy adherence, determine the effects of adherence on recovery, and identify barriers to successful adherence; and (3) develop and pilot test an ethically conscious adherence-driven rehabilitation program that individualizes patient care based on their capacity to effectively participate in their home physiotherapy.

Methods

This research will be conducted in 2 phases. The first phase is a prospective longitudinal cohort study, involving 120 patients undergoing physiotherapy for rotator cuff pathology. Patients will be issued a smartwatch that will record 9-axis inertial sensor data while they perform physiotherapy exercises both in the clinic and in the home setting. The data collected in the clinic under supervision will be used to train and validate our ML algorithms that classify shoulder physiotherapy exercise. The validated algorithms will then be used to assess home physiotherapy adherence from the inertial data collected at home. Validated outcome measures, including the Disabilities of the Arm, Shoulder, and Hand questionnaire; Numeric Pain Rating Scale; range of motion; shoulder strength; and work status, will be collected pretreatment, monthly through treatment, and at a final follow-up of 12 months. We will then relate improvement in patient outcomes to measured physiotherapy adherence and patient baseline variables in univariate and multivariate analyses. The second phase of this research will involve the evaluation of a novel rehabilitation program in a cohort of 20 patients. The program will promote patient physiotherapy engagement via the developed technology and support adherence-driven care decisions.

Results

As of December 2019, 71 patients were screened for enrollment in the noninterventional validation phase of this study; 65 patients met the inclusion and exclusion criteria. Of these, 46 patients consented and 19 declined to participate in the study. Only 2 patients de-enrolled from the study and data collection is ongoing for the remaining 44.

Conclusions

This study will provide new and important insights into shoulder physiotherapy adherence, the relationship between adherence and recovery, barriers to better adherence, and methods for addressing them.

International Registered Report Identifier (IRRID)

DERR1-10.2196/17841

Three-dimensional in vivo comparative analysis of the kinematics of normal shoulders and shoulders with massive rotator cuff tears with successful conservative treatment

BACKGROUND

This study used in vivo three-dimensional to two-dimensional image registration techniques to compare the glenohumeral kinematics of shoulders with massive rotator cuff tears that were successfully treated conservatively and those of normal shoulders.

METHODS

Ten patients (age, 67.4 ± 3.63 years) with massive rotator cuff tears on one side and without contralateral tears were enrolled. We performed computed tomography and fluoroscopy on both shoulder joints and created three-dimensional bone models of the humerus and scapula using image registration techniques. We measured the humeral superoinferior translation, angle of humeral external rotation, scapular upward rotation, scapular anteroposterior tilt, and scapular external rotation of the torn shoulders with good range of motion after effective conservative treatment and compared these measurements to those of the contralateral normal shoulders.

FINDINGS

There was a significant difference in the initial position of the humeral head relative to the glenoid in the tear group; it was 2.0 mm higher than that in the normal group (p < .05). This difference disappeared in the range from 40° to full elevation. The scapular motion of the tear group was significantly more upwardly rotated than that of the normal group: by 9.9° at rest (p < .05) and by 11.6° at terminal elevation (p < .05). No significant differences were detected for humeral head external rotation, scapular anteroposterior tilt, and scapular external rotation between the two groups.

INTERPRETATION

Kinematics of shoulders with massive cuff tears could not be recovered completely even though the patients had no significant symptoms after successful conservative treatment.

The Influence of Glenohumeral Joint Posterior Capsule Tightness and Impingement Symptoms on Shoulder Impairments and Kinematics

BACKGROUND

Posterior capsule tightness (PCT) and shoulder impingement syndrome (SIS) symptoms are both associated with altered shoulder biomechanics and impairments. However, their combined effect on kinematics, pain, range of motion (ROM), strength, and function remain unknown.

OBJECTIVE

The purpose of this study was to determine if the combination of PCT and SIS affects scapular and humeral kinematics, glenohumeral joint ROM, glenohumeral joint external rotation strength, pain, and function differently than does either factor (PCT or SIS) alone.

DESIGN

The design was a cross-sectional group comparison.

METHODS

Participants were placed into 1 of 4 groups based on the presence or absence of SIS and PCT: control group (n = 28), PCT group (n = 27), SIS group (n = 25), and SIS + PCT group (n = 25). Scapular kinematics and humeral translations were quantified with an electromagnetic motion capture system. Shoulder internal rotation and external rotation ROM, external rotation strength, and pain and Shoulder Pain and Disabilities Index scores were compared between groups with ANOVA.

RESULTS

The SIS group had greater scapular internal rotation (mean difference = 5.13°; 95% confidence interval [CI] = 1.53°-8.9°) and less humeral anterior translation (1.71 mm; 95% CI = 0.53-2.9 mm) than the other groups. Groups without PCT had greater internal rotation ROM (16.05°; 95% CI = 5.09°-28.28°). The SIS + PCT group had lower pain thresholds at the levator scapulae muscle (108.02 kPa; 95% CI = 30.15-185.88 kPa) and the highest Shoulder Pain and Disabilities Index score (∼ 44.52; 95% CI = 33.41-55.63).

LIMITATIONS

These results may be limited to individuals with impingement symptoms and cannot be generalized to other shoulder conditions.

CONCLUSIONS

Decreased ROM and lower pain thresholds were found in individuals with both impingement symptoms and PCT. However, the combination of factors did not influence scapular and humeral kinematics.

Comparison of scapular upward rotation during arm elevation in the scapular plane in healthy volunteers and patients with rotator cuff tears pre- and post-surgery

BACKGROUND

Function loss caused by rotator cuff tears alters the scapular orientation, however, few prior studies have reported on scapular movements after rotator cuff repair. The purpose was to determine the scapular orientations before and after rotator cuff repair.

METHODS

We recruited 14 healthy controls, 10 small and six massive rotator cuff tear in patients. The scapular upward rotation during arm elevation was analyzed using fluoroscopic imaging.

FINDINGS

Before surgery, both rotator cuff groups demonstrated greater scapular upward rotation compared to healthy controls. Two months postoperation, the analyses showed significant differences between the patients with small rotator cuff tears and healthy controls at arm elevations of 90°, and between patients with both rotator cuff tear groups and healthy controls at arm elevations of 120°. At five months post-operation, significant differences still existed between the healthy controls and both rotator cuff groups. In regard to the temporal effects in the patients with small rotator cuff tears, the scapular upward rotation decreased significantly over time (2-5 months postoperation) at arm elevations of 120°. We did not identify a main effect owing to time in the patients with massive rotator cuff tears.

INTERPRETATION

In patients with small rotator cuff tears, scapular upward rotation was reduced over the period of 2-5 months postoperation, however, the patients with massive rotator cuff tears showed greater scapular upward rotation throughout the experimental period. The results suggested that the execution of the rehabilitation program should consider that the tear size could affect scapular motion.

Computational optimization of graft tension in simulated superior capsule reconstructions

Superior capsular reconstruction has received increased attention as a surgical technique to address massive "irreparable" rotator cuff tears; however, the functional limitations and surgical techniques associated with this repair have yet to be sufficiently explored. The goal of this study was to utilize a multidisciplinary approach to characterize the biomechanics of this repair by: (i) identifying activities of daily living that may overburden the graft; and (ii) optimizing surgical techniques used during implantation. This experiment was completed in three phases. First, graft failure mechanics were characterized by performing an in vitro experiment. Second, in vivo shoulder kinematics associated with various activities were recorded with 3-D motion capture techniques. Finally, an in silico model was used to assess graft strains. Results show that motions involving posterior shoulder rotation, such as back washing, lead to graft strains that may cause failure. Output from the optimization suggests that orienting the humerus in approximately 25° abduction, and 20° internal rotation during implantation will result in optimal graft performance. Clinical Significance: The novel paradigm used in this study demonstrates the utility of coupling in vitro, in vivo, and in silico modeling techniques in one cohesive experiment. This paradigm presents an additional tool, aside from clinical studies and cadaveric experimentation, to better predict and understand the strengths and limitations of superior capsular reconstruction. This approach has potential to be translated to other soft tissue repairs and may provide valuable information to clinicians and rehabilitative specialists to manage patient expectations and guide rehabilitation. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2789-2796, 2018.

Dynamic thoracohumeral kinematics are dependent upon the etiology of the shoulder injury

Obtaining kinematic patterns that depend on the shoulder injury may be important when planning rehabilitation. The main goal of this study is to explore whether the kinematic patterns of continuous and repetitive shoulder elevation motions are different according to the type of shoulder injury in question, specifically tendinopathy or rotator cuff tear, and to analyze the influence of the load handled during its assessment. For this purpose, 19 individuals with tendinopathy and 9 with rotator cuff tear performed a repetitive scaption movement that was assessed with stereophotogrammetry. Furthermore, static range of motion (ROM) and isometric strength were evaluated with a goniometer and a dynamometer, respectively. Dynamic measurements of maximum elevation (Emax), variablility of the maximum angle (VMA), maximum angular velocity (Velmax), and time to maximum velocity (tmaxvel) were found to be significantly different between the tendinopathy group (TG) and the rotator cuff tear group (RTCG). No differences were found in the ROM assessed with goniometry and the isometric strength. The effect of increasing the load placed in the hand during the scaption movement led to significant differences in Emax, VMA, tmaxvel and repeatability. Therefore, only the dynamic variables showed sufficient capability of detecting differences in functional performance associated with structural shoulder injury. The differences observed in the kinematic variables between patients with tendinopathy and rotator cuff tear seem to be related to alterations in thoracohumeral rhythm and neuromuscular control. Kinematic analysis may contribute to a better understanding of the functional impact of shoulder injuries, which would help in the assessment and treatment of shoulder pain.

The presence and influence of posterior capsule tightness on different shoulder problems

BACKGROUND

In the literature it has been shown that posterior capsule flexibility is a precursor to shoulder problems. However, no study thus far has shown the influence of the flexibility of posterior capsule in different shoulder pathologies.

OBJECTIVE

This study set about to compare the role of posterior capsule tightness in different shoulder problems.

METHODS

One-hundred-twenty-five patients diagnosed with shoulder subacromial impingement syndrome (n= 52), partial rotator cuff tear (n= 31) or frozen shoulder (n= 42) and 30 asymptomatic peers participated in the study. Horizontal adduction was assessed in side-lying position for posterior capsule tightness. Pain was measured via the visual analogue scale and shoulder range of motion and active total elevation was assessed with goniometer. Hand behind the back (HBB) test was assessed the active internal rotation by measuring the distance between T5 and the thumb.

RESULTS

It was found that the affected side of the posterior capsules of the patients with subacromial impingement syndrome (p< 0.001), partial rotator cuff tear (p< 0.001) and frozen shoulder (p< 0.001) was stiffer than their healthy side. There were significant differences among groups in the level of tightness in the posterior capsule between the affected and the healthy sides (p< 0.001). All range of motion of the shoulder including HBB test and the posterior capsule tightness of the affected side are found to be correlated (p< 0.05).

CONCLUSIONS

This study emphasized that the posterior capsule's susceptibility to tightness is most evident in frozen shoulder among different shoulder problems.

Three-dimensional Scapular Kinematics During Arm Elevation in Massive Rotator Cuff Tear Patients

Objective

Rotator cuff tears can influence shoulder kinematics and severely impair function. However, there have been no studies on three-dimensional (3D) shoulder kinematics in massive rotator cuff tear (MRCT) patients. Hypothesizing that MRCT patients could demonstrate significantly changed scapular kinematics during arm elevation in the scapular plane, we compared 3D scapular kinematics in the scapular plane between MRCT patients and healthy elderly subjects.

Methods

We assessed 15 shoulders of 11 MRCT patients and 16 shoulders of 16 healthy subjects. With the subjects seated, we used an electromagnetic tracking system to calculate the upward rotation, posterior tilt, and internal rotation of the scapula at 10° increments from 30° to 120° with respect to the thorax. We performed two-way analysis of covariance with the initial position of the scapular motion as the covariate and performed multiple comparisons using the Bonferroni method.

Results

MRCT patients exhibited significantly higher scapular upward rotation than did the healthy subjects (P < 0.05). There were no significant differences between groups with regard to posterior tilt and internal rotation.

Conclusions

This study indicated that when MRCT patients elevated their arms, they exhibited a significantly higher scapular upward rotation at low- to mid-range elevations compared with that of healthy subjects. This difference may have resulted from a compensatory effect in response to the decreased elevation torque caused by the loss of rotator cuff function. These results may assist rehabilitation strategies to improve active arm elevation in MRCT patients.

Scapulohumeral rhythm relative to active range of motion in patients with symptomatic rotator cuff tears

BACKGROUND

Some patients with rotator cuff tears feel pain without functional limitation, whereas others show a decrease in range of motion. To investigate this distinction, the scapulohumeral rhythm was used to conduct a functional evaluation of shoulder joints' coordination. The objective was to characterize patients according to their active range of motion without pain and their scapulohumeral rhythm compared with healthy individuals.

MATERIALS AND METHODS

Fourteen patients with rotator cuff tears and 14 healthy individuals were set up with 35 reflective markers on the trunk and upper limb tracked by an optoelectronic system to measure the scapulohumeral rhythm. Five scapular plane maximal arm elevations were executed without pain. Patients were separated by maximal arm elevation of 85° (category A) and 40° (category B). Three-way mixed-design analysis of variance with factors of group (patients and healthy), arm elevation, and motion direction was applied to the scapulohumeral rhythm.

RESULTS

A main effect of group (P = .032) was observed in patients in category A, who showed inferior scapulohumeral rhythm. An interaction between group and arm elevation (P = .044) was observed for patients in category B, where their scapulohumeral rhythm increased more during arm elevation than in the healthy individuals.

CONCLUSIONS

Patients who reached at least 85° compensated for the loss of glenohumeral motion by increased scapulothoracic contribution, suggesting that structural damage interferes with motion mechanics. In contrast, patients who reached less range of motion underused the scapulothoracic joint, which is likely to create subacromial impingement at low arm elevation. A patient's maximal range of motion without pain may indicate a pattern of scapulohumeral rhythm alteration.

Collecting shoulder kinematics with electromagnetic tracking systems and digital inclinometers: A review

The shoulder complex presents unique challenges for measuring motion as the scapula, unlike any other bony segment in the body, glides and rotates underneath layers of soft tissue and skin. The ability for clinicians and researchers to collect meaningful kinematic data is dependent on the reliability and validity of the instrumentation utilized. The aim of this study was to review the relevant literature pertaining to the reliability and validity of electromagnetic tracking systems (ETS) and digital inclinometers for assessing shoulder complex motion. Advances in technology have led to the development of biomechanical instrumentation, like ETS, that allow for the collection of three-dimensional kinematic data. The existing evidence has demonstrated that ETS are reliable and valid instruments for collecting static and dynamic kinematic data of the shoulder complex. Similarly, digital inclinometers have become increasingly popular among clinicians due to their cost effectiveness and practical use in the clinical setting. The existing evidence supports the use of digital inclinometers for the collection of shoulder complex kinematics as these instruments have been demonstrated to yield acceptable reliability and validity. While digital inclinometers pose a disadvantage to ETS regarding accuracy, precision, and are limited to two-dimensional and static measurements, this instrument provides clinically meaningful data that allow clinicians and researchers the ability to measure, monitor, and compare shoulder complex kinematics.

Shoulder Coordination During Full-Can and Empty-Can Rehabilitation Exercises

CONTEXT

Supraspinatus tear is a common rotator cuff injury. During rehabilitation, debate persists regarding the most appropriate exercises. Whereas shoulder coordination is part of normal arm function, it has been infrequently considered in the context of exercise selection.

OBJECTIVE

To assess shoulder-motion coordination during 2 common supraspinatus rehabilitation exercises and to characterize load and motion-direction influences on shoulder coordination.

DESIGN

Descriptive laboratory study.

SETTING

Motion-analysis laboratory. Patient or Other Participants :  Fifteen asymptomatic right-hand-dominant men (age = 26 ± 4 years, height = 1.77 ± 0.06 m, mass = 74.3 ± 7.7 kg).

INTERVENTION(S)

Full-can and empty-can exercises with and without a 2.27-kg load.

MAIN OUTCOME MEASURE(S)

We recorded motion with an optoelectronic system. Scapulohumeral rhythm and complete shoulder joint kinematics were calculated to quantify shoulder coordination. The effects of exercise type, load, motion direction, and humerothoracic-elevation angle on the scapulohumeral rhythm and shoulder-joint angles were assessed.

RESULTS

We observed multivariate interactions between exercise type and humerothoracic elevation and between load and humerothoracic elevation. Scapulohumeral rhythm increased by a mean ratio of 0.44 ± 0.22 during the full-can exercise, whereas the addition of load increased mean glenohumeral elevation by 4° ± 1°.

CONCLUSIONS

The full-can exercise increased the glenohumeral contribution, as hypothesized, and showed normal shoulder coordination. During the empty-can exercise, the increased scapulothoracic contribution was associated with a compensatory pattern that limits the glenohumeral contribution. Using loads during shoulder rehabilitation seems justified because the scapulohumeral rhythm is similar to that of unloaded arm elevation. Finally, motion direction showed a limited effect during the exercises in healthy individuals.

Computational reverse shoulder prosthesis model: Experimental data and verification

The reverse shoulder prosthesis aims to restore the stability and function of pathological shoulders, but the biomechanical aspects of the geometrical changes induced by the implant are yet to be fully understood. Considering a large-scale musculoskeletal model of the upper limb, the aim of this study is to evaluate how the Delta reverse shoulder prosthesis influences the biomechanical behavior of the shoulder joint. In this study, the kinematic data of an unloaded abduction in the frontal plane and an unloaded forward flexion in the sagittal plane were experimentally acquired through video-imaging for a control group, composed of 10 healthy shoulders, and a reverse shoulder group, composed of 3 reverse shoulders. Synchronously, the EMG data of 7 superficial muscles were also collected. The muscle force sharing problem was solved through the minimization of the metabolic energy consumption. The evaluation of the shoulder kinematics shows an increase in the lateral rotation of the scapula in the reverse shoulder group, and an increase in the contribution of the scapulothoracic joint to the shoulder joint. Regarding the muscle force sharing problem, the musculoskeletal model estimates an increased activity of the deltoid, teres minor, clavicular fibers of the pectoralis major, and coracobrachialis muscles in the reverse shoulder group. The comparison between the muscle forces predicted and the EMG data acquired revealed a good correlation, which provides further confidence in the model. Overall, the shoulder joint reaction force was lower in the reverse shoulder group than in the control group.

Wrist rhythm during wrist joint motion evaluated by dynamic radiography

We hypothesized that wrist joint motion involves a "wrist rhythm" similar to the scapulohumeral rhythm. Therefore, we used a flat-panel detector to evaluate the ratio of radiolunate and capitolunate joint motions during wrist joint motion by dynamic radiography. The subjects were 20 healthy men. Dynamic imaging of the wrist joint was performed during active exercise for a total of ten seconds. In this study, we defined the radiocarpal (RL angle) and midcarpal joint angle (CL angle) as the wrist joint angle in the obtained images and measured the variation of these angles. The average curve was plotted and regression lines calculated from the average curve. The ratio was calculated from the slopes of the regression lines of the RL CL angles. These findings indicated that the ratio of the RL and CL angle motions was approximately 1:4 during palmar flexion and approximately 2:1 during dorsiflexion.

Study of the scapular muscle latency and deactivation time in people with and without shoulder impingement

Changes in muscle activities are commonly associated with shoulder impingement and theoretically caused by changes in motor program strategies. The purpose of this study was to assess for differences in latencies and deactivation times of scapular muscles between subjects with and without shoulder impingement. Twenty-five healthy subjects and 24 subjects with impingement symptoms were recruited. Glenohumeral kinematic data and myoelectric activities using surface electrodes from upper trapezius (UT), lower trapezius (LT), serratus anterior (SA) and anterior fibers of deltoid were collected as subjects raised and lowered their arm in response to a visual cue. Data were collected during unloaded, loaded and after repetitive arm raising motion conditions. The variables were analyzed using 2 or 3 way mixed model ANOVAs. Subjects with impingement demonstrated significantly earlier contraction of UT while raising in the unloaded condition and an earlier deactivation of SA across all conditions during lowering of the arm. All subjects exhibited an earlier activation and delayed deactivation of LT and SA in conditions with a weight held in hand. The subjects with impingement showed some significant differences to indicate possible differences in motor control strategies. Rehabilitation measures should consider appropriate training measures to improve movement patterns and muscle control.

Mechanical analysis of cuff tear arthropathy during multiplanar elevation with the AnyBody shoulder model

BACKGROUND

This numerical study analysed the mechanics of cuff tear arthropathy with the AnyBody shoulder model.

METHODS

The model simulated three frequent characteristics of cuff tear arthropathy: A supero-posterior massive rotator cuff tear, a proximal and static migration of the humeral head, and a contact between the humeral head and the scapula (glenoid & acromion) with friction. The mechanics of the cuff tear arthropathy with and without friction were studied by analysing: the mechanics of the deltoid (i.e. length & strength), the gleno-humeral and acromio-humeral contact forces, the friction moment, and the maximum elevation angle. Elevations in the frontal, scapular and sagittal planes were simulated.

FINDINGS

Compared to an intact condition, the cuff tear arthropathy model without friction estimated a deltoid strength of -18% (frontal=-13%, scapular=-17%, sagittal=-25%), a gleno-humeral contact force of -34% (frontal=-60%, scapular=-46%, sagittal=+5%), estimated an acromio-humeral contact force of 240 N (frontal=213 N, scapular=184 N, sagittal=324 N) and a maximum elevation angle of 77° (frontal=80°, scapular=87°, sagittal=65°). Contact friction enhanced this behaviour, decreasing even more the gleno-humeral contact force and the maximum elevation angle, while increasing the acromio-humeral contact force.

INTERPRETATION

This novel cuff tear arthropathy model suggests that friction and plane of elevation greatly influence the mechanics of the shoulder with cuff tear arthropathy. It also shows that the AnyBody simulation tool may be useful to study musculoskeletal pathologies and not only normal conditions.

Assessment of scapulohumeral rhythm for scapular plane shoulder elevation using a modified digital inclinometer

AIM: To develop a better understanding of scapulohumeral rhythm during scapular plane shoulder elevation.

METHODS: Thirteen healthy, college-aged subjects participated in this study. Subjects were free from any upper extremity, neck or back pathology. A modified digital inclinometer was utilized to measure scapular upward rotation of the subject’s dominant shoulder. Upward rotation was measured statically as subjects performed clinically relevant amounts of shoulder elevation in the scapular plane. Testing order was randomized by arm position. Scapular upward rotation was assessed over the entire arc of motion and over a series of increments. The percent contributions to shoulder elevation for the scapula and glenohumeral joint were calculated. Scapulohumeral rhythm was assessed and represented the ratio of glenohumeral motion to scapulothoracic motion (glenohumeral elevation: scapular upward rotation). A one-way ANOVA was used to compare scapular upward rotation between elevation increments.

RESULTS: Scapulohumeral rhythm for the entire arc of shoulder elevation was equal to a ratio of 2.34 :1 and ranged from 40.01:1 to 0.90:1 when assessed across the different increments of humeral elevation. Total scapular motion increased over the arc of shoulder elevation. The scapula contributed 2.53% of total motion for the first 30 degrees of shoulder elevation, between 20.87% and 37.53% for 30^o-90^o of shoulder elevation, and 52.73% for 90^o-120^o of shoulder elevation. Statistically significant differences in scapular upward rotation were identified across the shoulder elevation increments [F_(3,48) = 12.63, P = 0.0001].

CONCLUSION: Clinically, we must recognize the usefulness of the inclinometer in documenting the variable nature of scapulohumeral rhythm in healthy and injured shoulders.

IMPACT OF PAIN ON SHOULDER ELEVATION VELOCITY IN PATIENTS WITH ROTATOR CUFF TEARS

Pain is routinely implicated as a factor when considering impaired movement in injured populations. Movement velocity is often considered during the rehabilitation process; unfortunately our understanding of pain's impact on shoulder movement velocity in rotator cuff tear patients is less understood. Therefore, the purpose of this study was to test the hypothesis that there would be an increase in peak and mean shoulder elevation velocities following the decrease of shoulder pain in rotator cuff tear patients, regardless of tear size. Fifteen subjects with full-thickness rotator cuff tears (RCT) performed humeral elevation and lowering in three planes before and after receiving a lidocaine injection to relieve pain. Pain was assessed using a visual analog scale. Humeral elevation velocity data were collected using an electromagnetic tracking system. A significant reduction in pain (pre-injection 3.53 ± 1.99; post-injection 1.23 ± 1.43) resulted in significant increases in maximum and mean humeral elevation velocities. Mean shoulder elevation and lowering velocities increased 15.10 ± 2.45% while maximum shoulder movement velocities increased 12.77 ± 3.93%. Furthermore, no significant relationships were noted between tear size and movement velocity. These significant increases in movement velocity provide evidence to further support the notion that human motion can be inhibited by injury-associated pain, and that by reducing that pain through clinical interventions, human movement can be impacted in a positive fashion.