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Validation of a new model-based tracking technique for measuring three-dimensional, in vivo glenohumeral joint kinematics.

Shoulder motion is complex and significant research efforts have focused on measuring glenohumeral joint motion. Unfortunately, conventional motion measurement techniques are unable to measure glenohumeral joint kinematics during dynamic shoulder motion to clinically significant levels of accuracy. The purpose of this study was to validate the accuracy of a new model-based tracking technique for measuring three-dimensional, in vivo glenohumeral joint kinematics. We have developed a model-based tracking technique for accurately measuring in vivo joint motion from biplane radiographic images that tracks the position of bones based on their three-dimensional shape and texture. To validate this technique, we implanted tantalum beads into the humerus and scapula of both shoulders from three cadaver specimens and then recorded biplane radiographic images of the shoulder while manually moving each specimen's arm. The position of the humerus and scapula were measured using the model-based tracking system and with a previously validated dynamic radiostereometric analysis (RSA) technique. Accuracy was reported in terms of measurement bias, measurement precision, and overall dynamic accuracy by comparing the model-based tracking results to the dynamic RSA results. The model-based tracking technique produced results that were in excellent agreement with the RSA technique. Measurement bias ranged from -0.126 to 0.199 mm for the scapula and ranged from -0.022 to 0.079 mm for the humerus. Dynamic measurement precision was better than 0.130 mm for the scapula and 0.095 mm for the humerus. Overall dynamic accuracy indicated that rms errors in any one direction were less than 0.385 mm for the scapula and less than 0.374 mm for the humerus. These errors correspond to rotational inaccuracies of approximately 0.25 deg for the scapula and 0.47 deg for the humerus. This new model-based tracking approach represents a non-invasive technique for accurately measuring dynamic glenohumeral joint motion under in vivo conditions. The model-based technique achieves accuracy levels that far surpass all previously reported non-invasive techniques for measuring in vivo glenohumeral joint motion. This technique is supported by a rigorous validation study that provides a realistic simulation of in vivo conditions and we fully expect to achieve these levels of accuracy with in vivo human testing. Future research will use this technique to analyze shoulder motion under a variety of testing conditions and to investigate the effects of conservative and surgical treatment of rotator cuff tears on dynamic joint stability.

Aged, 80 and over↗

Azlocillin and cefonicid penetration into bone enhanced by probenecid.

Azlocillin (AZL) and cefonicid (CFD) penetration into rabbit humerus and scapula was evaluated with and without concomitantly administered probenecid. Groups of animals received either 70 mg of AZL intravenously or 20 mg of CFD intramuscularly per kg of body weight; other groups were pretreated with 40 mg of probenecid per kg before the administration of antibiotics. Peak levels of AZL in the sera of animals not receiving probenecid were 76.0 micrograms/ml at 30 min and declined to 7.7 micrograms/ml by 2.0 h. Maximum concentrations in bone were 2.7 micrograms/g in the humerus and 7.1 micrograms/g in the scapula at 1 h. Pretreatment with probenecid significantly elevated levels of AZL in both serum and bone while increasing the half-life in serum from 0.44 to 0.65 h. Maximum drug concentrations in bones of probenecid-pretreated animals were 3.9 and 11.7 micrograms/g in the humerus and scapula, respectively, with detectable levels persisting in bone for up to 4 h. The peak level of CFD alone in serum was 36.7 micrograms/ml at 30 min and declined to 0.86 micrograms/ml at 8 h. Maximum concentrations in bone were 0.66 micrograms/g in the humerus at 1 h and 1.8 micrograms/g in the scapula at 2 h. Pretreatment with probenecid significantly elevated levels of CFD in both serum and bone while increasing the half-life in serum from 1.4 to 2.94 h. Pretreatment with probenecid achieved maximum concentrations of 1.7 and 2.8 micrograms/g in the humerus and scapula, respectively. Detectable levels of CFD persisted in the humerus for up to 4 h and in the scapula for 8 h.

Animals↗

[New operative technique to resect of peripheral bronchogenic carcinoma with chest wall invasion using Kent's retractor].

We report the new operative technique for resection of peripheral bronchogenic carcinoma with chest wall invasion using Kent's retractor and hook suspender. Standard muscle sparing thoracotomy cannot obtain the adequate operative field in the posterior chest wall under the scapula because of sparing the latissimus dorsi muscle. To obtain a sufficient operative field at the operation for en bloc chest wall resection, especially with the area of the posterior chest wall under the scapula, resection of the trapezius muscle, rhomboideus major muscle, and latissimus dorsi muscle has been added to muscle-sparing thoracotomy. Through our new technique using Kent's retractor and hook suspender that has been used in the abdominal surgery, assistant surgeon can be eliminated in favor of hanging up the scapula, which is able to be performed much easier to obtain a good operative field. To use the Kent's retractor and hook suspender, the scapula is lifted upward and cranially. With these procedures, the proximal portion of the first, second and third ribs in the posterior chest wall covering by the scapula is able to resect from vertebrocostal junction with muscle-sparing thoracotomy. We examined the apparatus for a case of the right upper lung carcinoma with invasion to the posterior chest wall. We performed right upper lobectomy with chest wall in the area of the second, third and forth ribs with suspending the scapula by Kent's retractor after muscle-sparing thoracotomy.

Adenocarcinoma↗

Three-dimensional scapulothoracic motion during active and passive arm elevation.

BACKGROUND: Scapulothoracic muscle activity is believed to be important for normal scapulothoracic motion. In particular, the trapezius and serratus anterior muscles are believed to play an important role in the production and control of scapulothoracic motion. The aim of this study was to determine the effects of different levels of muscle activity (active versus passive arm elevation) on three-dimensional scapulothoracic motion. METHODS: Twenty subjects without a history of shoulder pathology participated in this study. Three-dimensional scapulothoracic motion was determined from electromagnetic sensors attached to the scapula, thorax and humerus during active and passive arm elevation. Muscle activity was recorded from surface electrodes over the upper and lower trapezius, serratus anterior, anterior and posterior deltoid, and infraspinatus muscles. Differences in scapulothoracic motion were calculated between active and passive arm elevation conditions. FINDINGS: Scapular motion was observed during the trials of passive arm elevation; however, there was more upward rotation of the scapula, external rotation of the scapula, clavicular retraction, and clavicular elevation under the condition of active arm elevation. This was most pronounced for scapular upward rotation through the mid-range (90-120 degrees) of arm elevation. INTERPRETATION: The upper and lower trapezius and serratus anterior muscles have an important role in producing upward rotation of the scapula especially throughout the mid-range of arm elevation. Additionally, it appears that capsuloligamentous and passive muscle tension contribute to scapulothoracic motion during arm elevation. Assessment of the upper and lower trapezius and serratus anterior muscles and upward rotation of the scapula should be part of any shoulder examination.

Adolescent↗

The scapulo-humeral rhythm: effects of 2-D roentgen projection.

OBJECTIVE: The objective of this study is to illustrate the low accuracy of two-dimensional (2-D) X-ray projection methods for the quantification of the three-dimensional (3-D) shoulder motions. BACKGROUND: The traditional method for the quantification of the gleno-humeral motion is by means of 2-D X-ray recording. The motion was characterized by the scapulo-humeral rhythm: the ratio of the nett humeral elevation over nett scapular rotation. The method was based on the quantification of the planar projection of the spatial positions of X-ray dense structures of the scapula. The deformations introduced by the central projection method, a feature of X-ray projection, cannot be compensated for by calibration: the position of the scapula with respect to the camera setting is unknown, and skeletal landmarks of the scapula cannot uniquely be identified. The transformation from 3-D orientations to 2-D angles will, therefore, be inaccurate. METHODS: A 2-D X-ray projection of the scapula during a typical arm abduction was simulated. The 3-D motion was obtained by means of palpation and subsequent digitization of skeletal landmarks of the scapula. The 3-D positions of the recorded landmarks were projected on a plane by a simulation based on the parameters of the X-ray equipment. The scapulo-humeral rhythm was calculated for the different scapular landmarks, and for the orientation of the subject with respect to the projection axis. The results were compared with previous published scapulo-humeral rhythms. RESULTS: The scapulo-humeral rhythm depends both on the choice of the skeletal landmarks, used to quantify the scapular rotations, and on the orientation of the subject in the X-ray setting. The full range of results obtained from earlier published experiments could be obtained from a simulation based on a single 3-D arm abduction. CONCLUSIONS: The 2-D scapulo-humeral rhythm, obtained from planar X-ray projection, is an inaccurate parameter to define the scapular motions. RELEVANCE: The 2-D scapulo-humeral rhythm is an insensitive parameter to identify clinical disorders in the gleno-humeral motions, 3-D motion recording should be applied. Only when stringent precautions are taken with respect to repeatability of positioning of the subjects, can the method be used to study intra-individual effects, e.g., the follow-up of patients during treatment.

Biomechanical Phenomena↗

The measurement of three dimensional scapulohumeral kinematics--a study of reliability.

OBJECTIVE: To validate a system, using electromagnetic movement sensors, for the simultaneous measurement of scapular and humeral positions. DESIGN: The study was designed to analyse the repeatability and to quantify the inherent measurement errors, using two observers to measure the movements of five normal subjects. BACKGROUND: Following an earlier study of a system to measure three dimensional scapula motion, the method has been developed to incorporate simultaneous measurement of humeral and scapular position using a new design of scapula locator and a two-channel measurement system. METHODS: The system was used to measure the scapula movements accompanying abduction of the shoulder. The scapula locator was applied at 10 degrees intervals of abduction. This was measured initially using a fluid filled goniometer, but, in a second part of the study, using an additional motion sensor. RESULTS: In the single channel study, the 95% confidence intervals were less than 4 degrees and 10 mm. When simultaneous measurement of arm position was performed the confidence intervals were little changed. CONCLUSIONS: A new system for the measurement of scapulohumeral relationships has been shown to have good inter-and intraobserver reliability. This study opens the way for a full investigation of the scapula motion accompanying three dimensional shoulder motion in both normal subjects and in patients having shoulder pathology.

Analysis of Variance↗

The Sprengel deformity. Morphometric analysis using 3D-CT and its clinical relevance.

We evaluated scapular dysplasia and malposition in 15 patients with the Sprengel deformity using three-dimensional CT (3D-CT). The shape, height-to-width ratio, the areas of both scapulae, the anterior curvature of the supraspinous portion and glenoid version were assessed on scapular posterior, medial and inferior views. The degree of rotation and superior displacement were measured on the trunk posterior view. The omovertebral connection was also assessed and correlated with the operative findings. Most of the affected scapulae had a characteristic shape with a decrease in the height-to-width ratio and were larger than the contralateral scapulae. There was an inverse relationship between scapular rotation and superior displacement. The typical curve of the supraspinous portion of the scapula was seen in only three cases. There was no significant difference in glenoid version. The point of tethering of the omovertebral connection may determine the shape, rotation and superior displacement of the scapula. 3D-CT was helpful in delineating the deformity in detail, and in planning scapuloplasty.

Child↗

Sprengel deformity.

Eighteen cases of Sprengel deformity in sixteen patients were treated by the same surgeon. The operation was a modification of Green's procedure; all muscular attachments to the scapula are freed, the omovertebral band is cut, and the scapula is sutured into a pocket in the latissimus dorsi after the scapula has been rotated and moved caudad to a more normal position. No spring or wire traction is employed. The ages of the patients at operation ranged from twenty months to five years and ten months. The duration of follow-up ranged from three years to fourteen years and three months. In eleven of the fifteen patients who were available for follow-up, there was a moderate or dramatic improvement in appearance postoperatively. Preoperatively, the total abduction of the shoulder averaged 91 degrees (range, 60 to 120 degrees), and postoperatively, the abduction averaged 148 degrees. A radiographic geometric method was devised to quantitate lowering and derotation of the scapula. The lowering did not change appreciably with time. The original malrotation of the scapula was corrected initially but usually recurred after two years; however, this did not compromise the large increase in abduction postoperatively.

Adolescent↗

Shoulder joint kinematics during elevation measured by ultrasound-based measuring system.

In order to analyze shoulder joint movements, the authors use a ZEBRIS CMS-HS ultrasound-based movement analysis system. In essence, the measurement involves the determination of the spatial position of the 16 anatomical points, which are specified on the basis of the coordinates of ultrasound-based triplets positioned on the upper limb, the scapula, and the thorax; their spatial position is measured in the course of motion. Kinematic characteristics of 74 shoulder joints of 50 healthy persons were identified during elevation in the plane of the scapula. Kinematic characteristics of motion were identified by scapulothoracic, glenohumeral, and humeral elevation angles; range of angles; scapulothoracis and glenohumeral rhythm; scapulothoracic, glenohumeral, and scapuloglenoid ratios; and the relative displacement between the rotation centers of the humerus and the scapula. Motion of the humerus and the scapula relative to each other was characterized by their rotation as well as the relative displacement between the rotation centers of scapula and humerus. The biomechanical model of the shoulder joint during elevation can be described by analyzing the results of the measurements performed.

Adult↗

Manual scapular stabilization: its effect on shoulder rotational range of motion.

OBJECTIVES: To study the effect of a recently described method of measuring shoulder rotational range of motion in which the scapula is manually stabilized, and to determine the reliability of that technique compared with measurements taken with the scapula unstabilized. DESIGN: Fifty high school athletes underwent measurement of shoulder rotational range of motion with and without the scapula manually stabilized. Measurements were performed by two groups of physical therapists blinded to the movement results, with repeat measurements performed 5 days later. RESULTS: Rotational motion measured with the scapula stabilized was significantly less than when it was measured with the scapula unstabilized. Reliability was comparable for the two techniques when measuring external rotation, but the new technique was more reliable for measuring internal rotation. CONCLUSION: Scapular stabilization should be used when measuring internal rotation of the shoulder to obtain more accurate measurement of pure glenohumeral rotation. The technique described is promising, but warrants further refinement before it can be recommended for widespread clinical use. With practice, in experienced clinicians' hands, this technique may be the most reliable method for measuring outcome in clinical trials and for following clinically significant rotational motion deficits.

Adolescent↗

Constraints on the morphological evolution of marsupial shoulder girdles.

Throughout their evolutionary histories, marsupial mammals have been taxonomically and morphologically less diverse than their sister taxa the placentals. Because of this, it has been proposed that the evolution of marsupials has been constrained by the functional requirements of their mode of reproduction. Marsupials give birth after short gestation times to immature neonates that immediately crawl, under the power of their precociously developed shoulder girdles, to the teat where they attach and complete their early development. Using a novel approach incorporating adult and embryological morphological data, this study is the first to both: (1) statistically support adult patterns of morphological divergence consistent with the constraint hypothesis, and (2) identify ontogenetic patterns of morphological change that demonstrate that the constraint was responsible, at least in part, for their formation. As predicted by the marsupial constraint, the shoulder girdles of adult marsupials are less diverse than those of adult placentals, and adult marsupial scapulae are less morphologically diverse than adult marsupial pelves. Furthermore, marsupials that complete an extensive crawl to the teat are restricted to a common pattern of ontogenetic scapular shape change, strongly supporting the hypothesis that the morphological development of the marsupial scapula has been limited evolutionarily by its obligate role in the crawl to the teat. Because this study establishes that ontogenetic and evolutionary morphological change is correlated within mammalian scapulae, it is probable that the marsupial constraint also restricted the morphological divergence of the scapula over evolutionary time by limiting ontogenetic change in the scapula. These findings, coupled with the importance of the shoulder girdle in mammalian locomotor specialization, support the conclusion that the low morphological diversity of marsupial forms over evolutionary time could be directly due to the constraint on marsupial morphological evolution caused by the functional requirements of the crawl to the teat.

Animals↗

[Age-related characteristics of the human acromioclavicular joint].

By birth in the acromioclavicular joint the acromial end of the clavicle is osseous, and the acromion of the scapula is cartilaginous. The most intensive formation of the relief and configuration of the articular surfaces of the joint occurs from 1 to 3 years of age. In mature persons the form of the articular surface of the acromial end of the clavicle is often oval and that of the acromion of the scapula--ellipsoid. In newborns the areas of the articular surfaces are nearly equal. The area of the articular surface of the acromial end of the clavicle is significantly more than that of the acromion of the scapula during the periods from 1 to 3, from 13 to 17 and from 21 to 30 years of age. The articular cleft is revealed in the roentgenograms by 17 years of age, when synostosis process of the acromion of the scapula is completed. The thickness of the articular cartilage at different poles of the articular surfaces from birth up to 70 years of age is not equal and therefore it is possible to judge about nonequivalent functional loading on different areas of the articular cartilage. The articular cartilage of the acromial end of the clavicle from birth to 16 years of age is hyaline, after 17 years of age, they acquire the structure of the fibrous cartilage. In the articular cartilage of the acromion of the scapula, this rearrangement is realized more slowly: its fibrous structure is revealed after 23-24 years of age. Involutional changes in the joint are revealed during the fourth decade.(ABSTRACT TRUNCATED AT 250 WORDS)

Acromioclavicular Joint↗

The spinoglenoid ligament: an anatomic study.

The spinoglenoid ligament and its anatomic variations are described in 27 shoulders from 15 cadavers. In each shoulder one or two distinct spinoglenoid ligaments originated from the base of the spine of the scapula; they inserted on the neck of the scapula or the shoulder joint capsule. In the 19 shoulders in which only one spinoglenoid ligament was present, it inserted into the neck of the scapula in 14 cases and into the shoulder joint capsule in five instances. In the eight shoulders in which there were two ligaments, one inserted into the neck of the scapula and the other into the shoulder joint capsule. We did not observe any hypertrophic spinoglenoid ligaments that may have compressed the suprascapular nerve.

Cadaver↗

In vivo estimation of the glenohumeral joint rotation center from scapular bony landmarks by linear regression.

In this paper, a method is described for in vivo prediction of the glenohumeral joint rotation center (GH-r), necessary for the construction of a humerus local coordinate system in shoulder kinematic studies. The three-dimensional positions of five scapula bony landmarks as well as a large number of data points on the surface of the glenoid and humeral head were collected at 36 sets of cadaver scapulae and adjacent humeri. The position of GH-r in each scapula was estimated by mathematically fitting spheres to the glenoid and humeral head. GH-r prediction from scapula geometry parameters by linear regression resulted in a RMSE between measured and predicted GH-r of 2.32 mm for the x-coordinate, 2.69 mm for the y-coordinate and 3.04 mm for the z-coordinate. Application in vivo revealed a random humerus orientation error due to measurement inaccuracies of 1.35, 0.29 and 1.26 degrees standard deviation per rotation angle. The estimated total humerus orientation error including the offset error due to the regression model inaccuracy was 2.86, 0.84 and 2.69 degrees standard deviation. As these errors were about 15 and 20% of, respectively, the intra- and inter-subject variability of the humerus orientations measured, it is concluded that the method described in this paper allows for an adequate construction of a humerus local coordinate system.

Cadaver↗

Periarticular fiber system of the shoulder joint.

The structure and attachment of the glenoid labrum were examined from the functional point of view in 42 shoulder-joint cavities using a combination of macroscopic and microscopic techniques. The labrum continues the long tendon of the biceps as far as the ventral glenoid notch and is supplemented by a connecting band between the superior and inferior glenohumeral ligaments. In the upper quadrants, the periarticular fibers are broadly attached to the neck of the scapula and separated by a gap from the articular cartilage. In the lower quadrants, they are attached to both the neck of the scapula and the joint surface. The periarticular structures consist of bundles of parallel collagen fibers that run round the entire circumference of the cavity. The labrum, glenohumeral ligaments, and inserting tendons form a basket of fibers around the neck of the scapula, which constitutes a functional unit: the periarticular fiber system (PAFS). This acts as a tension-brace for the joint cavity and takes part in the local transmission of pressure through the cavity. Detachment of the labrum, or the labral-biceps anchor, should only be diagnosed when it can be shown that the tissue between the PAFS and the upper part of the neck of the scapula has been torn, and that the extent of the gap formation reaches laterally and caudally beyond the peripheral edge of the cartilage.

Adolescent↗

Scapular position: the validity of skin surface palpation.

The assessment of the resting position of the scapula forms part of the examination of upper quadrant posture. The purpose of this study was to determine if surface palpation is a valid indicator of actual scapular position. Twelve embalmed shoulders were examined and the actual location of three bony scapular landmarks and three bony thoracic landmarks were compared with surface palpation of these locations. The results, based on the upper value for a distance (with 95% confidence), suggested that the difference between the surface location of the root of the spine of the scapula, the acromial angle and the inferior angle would be less than 0.67 cm, 0.98 cm and 0.46 cm respectively from the centre of the bony locations. The difference between the twelfth thoracic spinous process (SP), the SP corresponding with the root of the spine of the scapula, and the SP corresponding with the inferior angle and the surface points would be 1.46 cm, 1.09 cm and 1.01 cm respectively. The results of this study suggest that surface palpation of scapular location is a valid method for determining the actual location of the scapula. The findings also suggest that surface palpation can determine the location of thoracic landmarks, which may serve as reference points for scapular position.

Aged↗

[MR-based 3D-analysis of the pathomechanics of traumatic and atraumatic shoulder instability].

AIM: Until now it is unknown to what extent malpositioning of the scapula is a relevant factor in shoulder instability that should be considered in therapy. The objective was to analyse 3D-scapular kinematics and humeral head (de-)centering in patients with atraumatic and/or traumatic shoulder instability and to investigate the correlation between the two factors. METHOD: The shoulders of 28 healthy volunteers and of 14 patients each with atraumatic or traumatic instability were examined in various arm positions - with and without muscle activity - using open MR imaging. After 3D reconstruction, analyses of scapular kinematics and glenohumeral translation were performed. RESULTS: In atraumatic unstable shoulders, the scapular position [30 degrees of abduction: scapulo-humeral rhythm: 3.5 +/- 2.6 : 1 vs. healthy 2.4 +/- 1.3 : 1; internal rotation: 59 +/- 9 degrees vs. healthy 49 +/- 3 degrees (p < 0.05)] and humeral head position was significantly decentered in both planes (p < 0.05). While the correlation between the two factors was high during passive elevation (r = 0.60-0.87), it was low during muscular activity (r = 0.25-0.62). In patients with traumatic instability no alterations of the scapula kinematics were observed. Significant humeral head decentering (p < 0.05) occurred only during abduction and external rotation. CONCLUSIONS: Patients with atraumatic instability demonstrated significant alterations of scapular kinematics and decentering of the humeral head. In traumatic instability a decentering occurred only in specific arm positions with no changes in scapula position. Because of the high correlation between the two factors, physiotherapeutic strategies for the scapula-stabilising muscles should be adapted to the direction of instability.

Adolescent↗

[Congenital upward displacement of the shoulder blade].

Congenital upward displacement of the scapula is typified by changes in the shape, position, and attitude of the scapula; in a high percentage of cases it is associated with other malformations of the axial skeleton and the internal organs. As a result of the malposition of the scapula and its insufficient mobility in the scapulocostal joint the ability to raise the upper arm is limited. The need for treatment of this condition derives on the one hand from cosmetic considerations and on the other from the limitation of the mobility of the upper arm. However, in addition to this, the diagnosis of Sprengel's deformity must also lead one to look for accompanying malformations which may have much more serious consequences than the simple upward displacement of the scapula. Surgery represents the only effective form of treatment for Sprengel's deformity. The indication for surgery is based on a classification by degrees, taking both the functional loss as well as the conspicuousness into consideration. The choice of surgical procedure will depend on the severity of the malformation and the age of the patient.

Abnormalities, Multiple↗