Internal and external rotation of the shoulder: effects of plane, end-range determination, and scapular motion

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.

Toughening mechanisms for the attachment of architectured materials: The mechanics of the tendon enthesis

Architectured materials offer tailored mechanical properties but are limited in engineering applications due to challenges in maintaining toughness across their attachments. The enthesis connects tendon and bone, two vastly different architectured materials, and exhibits toughness across a wide range of loadings. Understanding the mechanisms by which this is achieved could inform the development of engineered attachments. Integrating experiments, simulations, and previously unexplored imaging that enabled simultaneous observation of mineralized and unmineralized tissues, we identified putative mechanisms of enthesis toughening in a mouse model and then manipulated these mechanisms via in vivo control of mineralization and architecture. Imaging uncovered a fibrous architecture within the enthesis that controls trade-offs between strength and toughness. In vivo models of pathology revealed architectural adaptations that optimize these trade-offs through cross-scale mechanisms including nanoscale protein denaturation, milliscale load-sharing, and macroscale energy absorption. Results suggest strategies for optimizing architecture for tough bimaterial attachments in medicine and engineering.

Arthroscopic Superior Capsule Reconstruction for Cuff Tear Arthropathy (Hamada Grade 5): A Case Report

CASE

We performed arthroscopic superior capsule reconstruction (ASCR) for cuff tear arthropathy (CTA) with humeral head deformity. A 62-year-old man presented with severely limited shoulder motion and recalcitrant omalgia. He had a history of dental implant removal due to metal allergy, and his Constant score was 21 points. We diagnosed CTA with Hamada classification grade 5 and performed ASCR to avoid allergic reactions. Severe night pain improved within 1 week of ASCR, and his Constant score after 2 years was 74 points.

CONCLUSION

ASCR may be an effective alternative treatment for patients with CTA with humeral head deformity.

Influence of humeral abduction angle on axial rotation and contact area at the glenohumeral joint

BACKGROUND

Although the elevation angle of the arm affects the range of rotation, it has not been evaluated up to the maximal abduction angle. In this study we conducted an evaluation up to maximal abduction and determined the contact patterns at the glenohumeral (GH) joint.

METHODS

Fourteen healthy volunteers (12 men and 2 women; mean age, 26.9 years) with normal shoulders (14 right and 8 left) were instructed to rotate their shoulders at 0°, 90°, 135°, and maximal abduction for each shoulder at a time. Using 2-dimensional and 3-dimensional single-plane image registration, the internal rotation (IR), external rotation (ER), and range of motion (ROM; ie, axial rotations) at the thoracohumeral (TH) and GH joints, and the contribution ratio (%ROM = GH-ROM/TH-ROM) were calculated for each abduction. The glenoid position with respect to the humeral head was also analyzed.

RESULTS

The TH-IR and TH-ER shifted toward an ER with increasing abduction angle, whereas the TH-ROM significantly decreased except at abduction between 0° and 90° (P < .001). The GH-IR and GH-ROM significantly decreased except at abduction between 0° and 90° (P < .001), but the GH-ER remained constant regardless of the abduction. The contribution ratio exceeded 80% for every abduction angle. The glenoid moved on the central and posterior areas of the humeral head at 0° and 90° abduction, respectively, and on the posterosuperior and anterosuperior areas at 135° and maximal abduction, respectively.

CONCLUSION

Our results provide new knowledge about wide axial rotation up to maximal abduction and constant GH-ER at any abduction.

Range of Motion Adaptations in Powerlifters

Gadomski, SJ, Ratamess, NA, and Cutrufello, PT. Range of motion adaptations in powerlifters. J Strength Cond Res 32(11): 3020-3028, 2018-The aim of this study was to investigate range of motion (ROM) and training patterns in powerlifters. Upper- and lower-extremity passive ROMs were assessed through goniometry in 15 male powerlifters (35.3 ± 13.7 years) and 15 age-matched controls (34.9 ± 14.6 years). The Apley scratch test and modified Thomas test were used to assess ROM across multiple joints. Training frequency, stretching frequency, and exercise selection were recorded using questionnaires. Passive glenohumeral (GH) extension, internal rotation, and external rotation ROM were significantly decreased in powerlifters (p < 0.050). Powerlifters displayed decreased ROM in the Apley scratch test in both dominant (p = 0.015) and nondominant (p = 0.025) arms. However, knee extension angle was markedly improved in powerlifters (20.3 ± 7.3°) compared with controls (29.9 ± 6.2°; p < 0.001). Bench press and bench press variations accounted for 74.8% of all upper-body exercises, whereas back squat and deadlift accounted for 79.7% of all lower-body exercises in powerlifters' training programs. To determine whether existing ROM adaptations were seen in elite powerlifters, the powerlifting cohort was split into 3 groups based on Wilks score: <400 (low), 400-500 (intermediate), and >500 (high). GH ROM limitations were more pronounced in elite powerlifters (Wilks >500), who had more powerlifting experience (p = 0.048) and greater lean body mass (p = 0.040). Overall, powerlifters displayed decreased GH ROM, but increased hamstring ROM, after training programs that were heavily focused on the bench press, back squat, and deadlift.

Assessment of the glenohumeral joint's active and passive axial rotational range

BACKGROUND

Assessment of the range of axial rotation of the glenohumeral joint will improve understanding of shoulder function, with applications in shoulder rehabilitation and sports medicine. However, there is currently no complete description of motion of the joint. The study aimed to develop a reliable protocol to quantify the internal and external axial rotations of the glenohumeral joint during active and passive motion at multiple humeral positions.

METHODS

Optical motion tracking was used to collect kinematic data from 20 healthy subjects. The humerus was positioned at 60°, 90°, and 120° of humerothoracic elevation in the coronal, scapular, and sagittal planes. Internal and external rotations were measured at each position for active and passive motion, where intrasubject standard deviations were used to assess variations in internal-external rotations.

RESULTS

The protocol showed intrasubject variability in the axial rotational range of <5° for active and passive rotations at all humeral positions. Maximum internal rotation was shown to be dependent on humeral position, where a reduced range was measured in the sagittal plane (P < .001) and at 120° elevations (P < .001). Conversely, maximum external rotations were not affected by humeral position.

CONCLUSION

The results describe normal ranges of internal-external rotation of the glenohumeral joint at multiple humeral positions. The protocol's low variability means that it could be used to test whether shoulder pathologic conditions lead to changes in axial rotational range at specific humeral positions.

Kinematic comparison and description of the 3-dimensional shoulder kinematics of 2 shoulder rotation tests

OBJECTIVES

The purpose of this study was to compare shoulder external rotation range of motion (ROM) during the hand-behind-neck (HBN) test and a standard shoulder external rotation test and to describe the 3-dimensional scapular motion during the HBN test.

METHODS

An electromagnetic tracking device was used to assess the dominant shoulder of 14 healthy participants while performing active full ROM in a standard shoulder external rotation test in an elevated position (EREP) and in the HBN test. The humeral and scapular 3-dimensional positions at the end of EREP and HBN were compared using a paired-sample t test. A correlation analysis was performed between humeral and scapular angles to assess the contribution of scapular motion to the full shoulder ROM during the HBN test.

RESULTS

No significant differences were found between the HBN test and the EREP at the end-range of the glenohumeral external rotation (HBN: 15.6° ± 6.3° vs EREP: 23.4° ± 4.7°; P = .08) and on scapular internal-external rotation (HBN test: 21.2° ± 6.3° vs EREP: 15.6° ± 1.8°; P = .23). Significant differences were found in scapular upward rotation (HBN: 21.2° ± 6.3° vs EREP: 15.6° ± 1.8°; P < .01) and scapular spinal tilt (HBN: -0.4° ± 2.3° vs EREP: 8.1° ± 2.1°; P < .01). There was a positive correlation between the humeral angles and scapular internal and posterior spinal tilt angles with the HBN test.

CONCLUSIONS

The results of the present study showed that, in young asymptomatic participants with no known shoulder pathology, the end-range of shoulder rotation was similar in the HBN test and in a standard shoulder rotation test. During the HBN test, the scapula assumed a more internal and anterior spinal tilted position at the end-range of active shoulder external rotation. These results suggest that the HBN test may be used to assess the end-range of glenohumeral external rotation.

Assessment of shoulder external rotation range-of-motion on throwing athletes: the effects of testing end-range determination (active versus passive)

The purpose of this study was to compare the effects of active or passive end-range determination (supine position) for external rotation range of motion (ROM) in overhead throwing athletes and verify if athletes' ROM is similar to non-athletes. Kinematic data from the dominant shoulder of 24 healthy male subjects, divided into two groups (12 athletes and 12 non-athletes) were recorded at end-range external rotation, thoracohumeral and glenohumeral external rotation angles were compared and a 2-way repeated-measures ANOVA was used to calculate the effects of end-range determination (passive versus active) across groups (athlete and non-athlete). A significant main effect (p < 0.001) on both thoracohumeral and glenohumeral external end-range angles was observed while the highest end-range determination values were associated with passive motion. No differences were observed between the athletic or non-athletic groups for either thoracohumeral (p = 0.784) or glenohumeral (p = 0.364) motion.

Gender effect on the scapular 3D posture and kinematic in healthy subjects

Populations considered for shoulder analysis are often composed of various ratios of men and women. It is consequently hypothesized that gender has no significant effect on the joint kinematic. However, the literature reports, for the shoulder, differences in the range of motion between genders. The specific influence of gender on the scapulo-thoracic kinematics has not been studied yet. The dominant shoulder of two populations of men and women composed of 11 subjects each were evaluated in three dimensions for three distinct motions: flexion in the sagittal plane, abduction in the frontal plane and gleno-humeral internal/external rotation with the arm abducted at 90°. Posture, kinematics and range of motion were studied separately. For flexion and abduction and with regard to the scapular kinematic, external rotation was significantly larger for women than men. The differences were of at least 5° at 120° of humeral elevation. Upward rotations were identical. Women also showed larger average active humero-thoracic range of motion. The mean differences were of 13°, 7°, 12° and 5° for abduction, flexion, internal rotation and external rotation, respectively. No difference was observed between the scapular resting positions of both populations. The observed differences concerning both the scapular and humeral patterns would indicate that the shoulder behaviour of men and women should not be expected to be similar.

Measuring shoulder external and internal rotation strength and range of motion: comprehensive intra-rater and inter-rater reliability study of several testing protocols

BACKGROUND

Shoulder range of motion (ROM) and strength measurements are imperative in the clinical assessment of the patient's status and progression over time. The method and type of assessment varies among clinicians and institutions. No comprehensive study to date has examined the reliability of a variety of procedures based on different testing equipment and specific patient or shoulder position. The purpose of this study was to establish absolute and relative reliability for several procedures measuring the rotational shoulder ROM and strength into internal (IR) and external (ER) rotation strength.

METHODS

Thirty healthy individuals (15 male, 15 female), with a mean age of 22.1 ± 1.4 years, were examined by 2 examiners who measured ROM with a goniometer and inclinometer and isometric strength with a hand-held dynamometer (HHD) in different patient and shoulder positions. Relative reliability was determined by intraclass correlation coefficients (ICC). Absolute reliability was quantified by standard error of measurement (SEM) and minimal detectable change (MDC). Systematic differences across trials or between testers, as well as differences among similar measurements under different testing circumstances, were analyzed with dependent t tests or repeated-measures analysis of variance in case of 2 or more than 2 conditions, respectively.

RESULTS

Reliability was good to excellent for IR and ER ROM and isometric strength measurements, regardless of patient or shoulder position or equipment used (ICC, 0.85-0.99). For some of the measurements, systematic differences were found across trials or between testers. The patient's position and the equipment used resulted in different outcome measures.

CONCLUSIONS

All procedures examined showed acceptable reliability for clinical use. However, patient position and equipment might influence the results.

Dominance effect on scapula 3-dimensional posture and kinematics in healthy male and female populations

BACKGROUND

The contralateral shoulder is often used as a reference when evaluating a pathologic shoulder. However, the literature provides contradictory results regarding the symmetry of the scapular pattern in a healthy population. We assume that several factors including gender and type of motion may influence the bilateral symmetry of the scapulae.

MATERIALS AND METHODS

The dominant and nondominant shoulders of 2 populations of men and women comprising 11 subjects each were evaluated for 3 distinct motions: flexion in the sagittal plane, abduction in the frontal plane, and glenohumeral internal/external rotation with the arm abducted at 90°. Posture, kinematics, and range of motion were studied separately.

RESULTS

Asymmetries are observed for motions performed in the frontal and sagittal plane but not for internal/external rotation with the arm abducted at 90°. For both male and female populations, multiplanar asymmetries are observed and the dominant scapula has a larger upward rotation. The asymmetries mainly originate in the scapula's kinematics and not in its original posture.

CONCLUSION

Small but significant asymmetries exist between the dominant and nondominant shoulders in terms of kinematics. One should be aware of these differences when using the contralateral shoulder as a reference.

LEVEL OF EVIDENCE

Basic science study, kinematics

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.

Local versus global optimal sports techniques in a group of athletes

Various optimization algorithms have been used to achieve optimal control of sports movements. Nevertheless, no local or global optimization algorithm could be the most effective for solving all optimal control problems. This study aims at comparing local and global optimal solutions in a multistart gradient-based optimization by considering actual repetitive performances of a group of athletes performing a transition move on the uneven bars. Twenty-four trials by eight national-level female gymnasts were recorded using a motion capture system, and then multistart sequential quadratic programming optimizations were performed to obtain global optimal, local optimal and suboptimal solutions. The multistart approach combined with a gradient-based algorithm did not often find the local solution to be the best and proposed several other solutions including global optimal and suboptimal techniques. The qualitative change between actual and optimal techniques provided three directions for training: to increase hip flexion-abduction, to transfer leg and arm angular momentum to the trunk and to straighten hand path to the bar.

Effects of attachment position and shoulder orientation during calibration on the accuracy of the acromial tracker

The acromial tracker is used to measure scapular rotations during dynamic movements. The method has low accuracy in high elevations and is sensitive to its attachment location on the acromion. The aim of this study was to investigate the effect of the attachment position and shoulder orientation during calibration on the tracker accuracy. The tracker was attached to one of three positions: near the anterior edge of the acromion process, just above the acromial angle and the meeting point between the acromion and the scapular spine. The scapula locator was used to track the scapula during bilateral abduction simultaneously. The locator was used to calibrate the tracker at: no abduction, 30°, 60°, 90° and 120° humerothoracic abduction. ANOVA tests compared RMS errors for different attachment positions and calibration angles. The results showed that attaching the device at the meeting point between the acromion and the scapular spine gave the smallest errors and it was best to calibrate the device at 60° for elevations ≤90°, at 120° for elevations >90° and at 90°or 120° for the full range of abduction. The accuracy of the tracker is significantly improved if attached appropriately and calibrated for the range of movement being measured.

Acromioclavicular joint pain in patients with adhesive capsulitis: a prospective outcome study

Diagnosis of adhesive capsulitis is a clinical diagnosis based on history and physical examination. Afflicted patients exhibit active and passive loss of motion in all planes and a positive capsular stretch sign. The effect of adhesive capsulitis on acromioclavicular biomechanics leading to tenderness has not been documented in the literature. This study reports on the incidence of acromioclavicular tenderness in the presence of adhesive capsulitis. Furthermore, we note the natural history of such acromioclavicular joint pain in relation to that of adhesive capsulitis. Over a 2-year period (2005-2007), 84 patients undergoing initial evaluation for adhesive capsulitis were prospectively examined with the use of validated outcome measures and physical examination. Acromioclavicular joint tenderness results were compared and analyzed on initial evaluation and final follow-up of at least 1 year. Forty-eight patients (57%) with adhesive capsulitis had acromioclavicular joint pain on examination. At final follow-up, as range of motion improved, a significant increase in American Shoulder and Elbow Surgeons/Penn shoulder score and decrease in number of patients with acromioclavicular pain was noted with only 6 patients with residual pain (P<.05). In the presence of adhesive capsulitis, there is not only compensatory scapulothoracic motion but also acromioclavicular motion. This often results in transient symptoms at the acromioclavicular joint, which abate as the frozen shoulder resolves and glenohumeral motion improves. This is important to recognize to avoid unnecessary invasive treatment of the acromioclavicular joint when the patient presents with adhesive capsulitis.

Positional stretching of the coracohumeral ligament on a patient with adhesive capsulitis: a case report

Idiopathic frozen shoulder is a common medical diagnosis for patients seeking physical therapy. Radiographic and surgical evidence exists that describes the coracohumeral ligament (CHL) as a major contributor to lack of external rotation in patients diagnosed with frozen shoulder. No stretching techniques targeting the anatomical fiber orientation of the CHL have been reported in the literature. This single-patient case-report describes the use of a positional stretching technique of the CHL on a 51-year-old female diagnosed with phase I frozen shoulder. The patient completed 8 in-office visits and 17 home exercise program sessions of positional CHL stretching combined with a simple volitional rotator cuff exercise program in a 4-week period. The patient's Disabilities of the Arm Shoulder and hand (DASH) scores improved from 65 to 36 and Shoulder Pain and Disability Index (SPADI) scores improved from 72 to 8 and passive external rotation from 20 degrees to 71 degrees . While a cause-and-effect relationship cannot be inferred from a single case, this report may foster further investigation regarding the role of the CHL in patients with stage-I and stage-II frozen shoulder as well as therapeutic strategies to help reduce loss of mobility and function.

Analyzing glenohumeral torque-rotation response in vivo

BACKGROUND

Because the human shoulder has many degrees of freedom that allow redundant means of producing the same net humerothoracic motion, there are many impediments to objective, repeatable assessment of shoulder function in vivo. Devices designed to date have suffered from poor reliability. In this study we introduce a new device and methods to evaluate human shoulder kinematics and evaluate its reproducibility from subject to subject and from day to day.

METHODS

This was a controlled laboratory study. Using electromagnetic motion sensors to record the position and orientation of the thorax, scapula, and humerus, we quantified the kinematic response of twenty four normal shoulders in response to known internal-external torque application. A four-parameter logistic function was selected to characterize the strident features of the torque-rotation relationship.

FINDINGS

Our analysis in conjunction with the measurement technique described herein, allowed the passive glenohumeral internal-external range of motion to be differentiated from other motion components and was determined to within 9.6% of full scale over three repeated trials. Range of motion was the most reliable biomechanical outcome, more so than computed indices of glenohumeral flexibility and hysteresis. The exact profile of the torque-rotation response, and therefore the repeatability of the calculated outcomes, was unique from shoulder to shoulder.

INTERPRETATION

The development of the capacity for precise, non-invasive measurement of shoulder biomechanics over time is a requisite step towards optimizing treatment of shoulder injury and disease. Our current methods are superior to previous attempts at trying to non-invasively evaluate the biomechanics of the glenohumeral joint.

Glenohumeral, scapular, and thoracic angles at maximum shoulder external rotation in throwing

BACKGROUND

Because a majority of throwing injuries occur near the maximum external rotation (MER) of the throwing shoulder, sports medicine practitioners and researchers have paid special attention to the shoulder kinematics at the MER in throwing. However, little is known about the individual kinematics of the glenohumeral, scapulothoracic, and thoracic joints at the MER. Purpose To demonstrate the glenohumeral, scapulothoracic, and thoracic joint movements and their contribution to the MER in throwing for baseball players.

STUDY DESIGN

Descriptive laboratory study.

METHODS

We collected throwing motion data for 20 collegiate baseball players by using 3 high-speed cameras and established 3-dimensional coordinates of each landmark with a direct linear translation method. We then obtained the MER of the shoulder complex, the external rotation angle of the glenohumeral joint, the posterior tipping angle of the scapula, and the thoracic extension angles at the MER in throwing.

RESULTS

The mean (+/- standard deviation) value of the MER was 144.2 degrees +/- 11.0 degrees . The mean (+/- standard deviation) values of the glenohumeral external rotation, the scapular posterior tipping, and the thoracic extension angles at the MER were 105.7 degrees +/- 15.5 degrees , 23.5 degrees +/- 13.9 degrees , and 8.9 degrees +/- 7.3 degrees , respectively.

CONCLUSION

Our results indicate that not only the glenohumeral joint movement but also the scapular and thoracic movements make major contributions to the MER angle.

CLINICAL RELEVANCE

To better understand the pathomechanics of the shoulder complex in throwing, we need to take into account the individual contributions of the glenohumeral, scapulothoracic, and thoracic extension movements to the MER.

Anatomy and mechanics of the shoulder: review of current concepts

This narrative review is intended to provide hand and upper extremity therapists, who occasionally treat patients with shoulder diagnoses, with several current concepts related to normal shoulder anatomy and function. It is hoped that this review will be useful for 1) appreciating patho-anatomy and pathophysiology, 2) planning treatment approaches, and 3) stimulating research aimed at improved understanding of the shoulder.

Natural history of complex fractures of the proximal humerus using a three-dimensional classification system

We studied the nonoperative treatment of proximal humeral fractures in severe injuries usually treated surgically. The natural history of 63 patients was followed prospectively for 2 to 9 years (mean, 42 months) with a nonrandomized protocol. A 3-dimensional classification system based on computed tomography scans was used to categorize the fractures. Assessment was made for range of motion, function via a validated testing instrument (Simple Shoulder Test), analog pain score, avascular necrosis (AVN), and fracture union. Magnetic resonance imaging for early signs of AVN was done in 16 cases. After conservative treatment of complex fractures of the shoulder, motion is considerably compromised but pain is minimal and functional status is acceptable to most individuals in this predominantly older patient population. Status comparable to a successful surgical shoulder fusion is achieved in most cases-Nature's fusion. Contrary to common belief, AVN, even in severely displaced injuries, is rare. Future randomized studies based on a 3-dimensional classification need to be done to compare these natural history results with various types of surgical interventions.

Prevalence of symptoms and signs of shoulder problems in people with diabetes mellitus

Diabetes mellitus is a known risk factor for frozen shoulder. This study was performed to quantify this association and test any relationship with other risk factors for diabetic complications. Patients attending diabetic (n = 865) and general medical (n = 202) clinics were interviewed and examined. External rotation was measured in both shoulders. Glycated hemoglobin A(1c) was measured in all diabetic patients. Frozen shoulder was defined as pain for more than 3 months and external rotation of less than 50% of the unaffected shoulder. Bilateral frozen shoulder was defined as external rotation of less than 30 degrees in both shoulders. Shoulder pain was present in 25.7% of diabetic patients compared with 5.0% of general medical patients. The criteria for frozen shoulder were fulfilled in 4.3% of diabetic patients and in 0.5% of the general medical patients. Only duration of diabetes had a positive association. The prevalence of painful or stiff shoulder was greater in diabetic patients than general medical patients. The prevalence of frozen shoulder is less than previously reported but still greater in diabetic patients.