PubMed Health⌕ Search

Biomedical subjects

E Itoi

Publications and source records attributed to E Itoi.

At least 19 recordsLinked to original sources
PubMed2000

The effect of a glenoid defect on anteroinferior stability of the shoulder after Bankart repair: a cadaveric study.

BACKGROUND: An osseous defect of the glenoid rim is sometimes caused by multiple recurrent dislocations of the shoulder. It is generally thought that a large defect should be treated with bone-grafting, but there is a lack of consensus with regard to how large a defect must be in order to necessitate this procedure. Some investigators have proposed that a defect must involve at least one-third of the glenoid surface in order to necessitate bone-grafting. However, it is difficult to determine (1) whether a defect involves one-third of the glenoid surface and (2) whether a defect of this size is critical to the stability of the shoulder after a Bankart repair. The purposes of the present study were (1) to create and quantify various sizes of osseous defects of the glenoid and (2) to determine the effect of such defects on the stability and motion of the shoulder after Bankart repair. METHODS: The glenoids from sixteen dried scapulae were photographed, and the images were scanned into a computer. The average shape of the glenoid was determined on the basis of the scans, and this information was used to design custom templates for the purpose of creating various sizes of osseous defects. Ten fresh-frozen cadaveric shoulders then were obtained from individuals who had been an average of seventy-nine years old at the time of death, and all muscles were removed to expose the joint capsule. With use of a custom multiaxis electromechanical testing machine with a six-degrees-of-freedom load-cell, the humeral head was translated ten millimeters in the anteroinferior direction with the arm in abduction and external rotation as well as in abduction and internal rotation. With a fifty-newton axial force constantly applied to the humerus in order to keep the humeral head centered in the glenoid fossa, the peak force that was needed to translate the humeral head a normalized distance was determined under eleven sequential conditions: (1) with the capsule intact, (2) after the creation of a simulated Bankart lesion, (3) after the capsule was repaired, (4) after the creation of an anteroinferior osseous defect with a width that was 9 percent of the glenoid length (average width, 2.8 millimeters), (5) after the capsule was repaired, (6) after the creation of an osseous defect with a width that was 21 percent of the glenoid length (average width, 6.8 millimeters), (7) after the capsule was repaired, (8) after the creation of an osseous defect with a width that was 34 percent of the glenoid length (average width, 10.8 millimeters), (9) after the capsule was repaired, (10) after the creation of an osseous defect with a width that was 46 percent of the glenoid length (average width, 14.8 millimeters), and (11) after the capsule was repaired. RESULTS: With the arm in abduction and external rotation, the stability of the shoulder after Bankart repair did not change significantly regardless of the size of the osseous defect (p = 0.106). With the arm in abduction and internal rotation, the stability decreased significantly as the size of the osseous defect increased (p<0.0001): the translation force in shoulders in which the width of the osseous defect was at least 21 percent of the glenoid length (average width, 6.8 millimeters) was significantly smaller than the force in shoulders without an osseous defect. The range of external rotation in shoulders in which the width of the osseous defect was at least 21 percent of the glenoid length was significantly less than that in shoulders without a defect (p<0.0001) because of the pretensioning of the capsule caused by closing the gap between the detached capsule and the glenoid rim. The average loss of external rotation was 25 degrees per centimeter of defect. CONCLUSIONS: An osseous defect with a width that is at least 21 percent of the glenoid length may cause instability and limit the range of motion of the shoulder after Bankart repair.

Aged↗
PubMed1999

The static rotator cuff does not affect inferior translation of the humerus at the glenohumeral joint.

BACKGROUND: The static contribution of the rotator cuff to the inferior stability of the shoulder is poorly understood. The purpose of this study was to determine the effect of static rotator cuff muscles on the inferior stability of the glenohumeral joint. METHODS: The humeral head positions relative to the glenoid were obtained in 12 shoulder specimens under the following conditions: with and without a 1.5-kg load; with the humerus adducted and abducted 90 degrees; and in three stages of dissection: (1) before release of any of the rotator cuff muscles, (2) after release of the supraspinatus or the cuff muscles other than the supraspinatus, and (3) after release of all of the cuff muscles. The order of release was changed in two ways: release of the supraspinatus followed by the release of other muscles in one group, and the opposite order in the other group. RESULTS: In both adduction and abduction, there were no significant differences in the positions of the humeral head either among the three stages of release or between the two different orders of release. CONCLUSION: The static contribution of the cuff muscles to the inferior stability of the shoulder is insignificant.

Biomechanical Phenomena↗
PubMed1999

Position of immobilization after dislocation of the shoulder. A cadaveric study.

BACKGROUND: After reduction of a shoulder dislocation, the torn edges of a Bankart lesion need to be approximated for healing during immobilization. The position of immobilization has traditionally been adduction and internal rotation, but there is little direct evidence to support or discredit the use of this position. The purpose of the present study was to determine the relationship between the position of the arm and the coaptation of the edges of a simulated Bankart lesion created in cadaveric shoulders. METHODS: Ten thawed fresh-frozen cadaveric shoulders were used for experimentation. All of the muscles were removed to expose the joint capsule. A simulated Bankart lesion was created by sectioning the anteroinferior aspect of the capsule from the labrum. With linear transducers attached to the anteroinferior and inferior portions of the Bankart lesion, the opening and closing of the lesion were recorded with the arm in 0, 30, 45, and 60 degrees of elevation in the coronal and sagittal planes as well as with the arm in rotation from full internal to full external rotation in 10-degree increments. RESULTS: With the arm in adduction, the edges of the simulated Bankart lesion were coapted in the range from full internal rotation to 30 degrees of external rotation. With the arm in 30 degrees of flexion or abduction, the edges of the lesion were coapted in neutral and internal rotation but were separated in external rotation. At 45 and 60 degrees of flexion or abduction, the edges were separated regardless of rotation. CONCLUSIONS: The present study demonstrated that, in the cadaveric shoulder, there was a so-called coaptation zone in which the edges of a simulated Bankart lesion were kept approximated without the surrounding muscles.

Aged↗
PubMed1998

Humeral attachment of the supraspinatus and infraspinatus tendons: an anatomic study.

We investigated the anatomic relationship of the supraspinatus (SSP) and infraspinatus (ISP) tendons to the three facets of the greater tuberosity. After removing the superficial layer of the cuff to expose the tendon fibers in 10 embalmed shoulders, the cuff tendon attachment to the facets was examined, and the location of attachment was measured in reference to (1) the anterior margin of the greater tuberosity and (2) the superior margin of the sulcus (anatomic neck without cartilage). The SSP tendon attached to the superior facet and the superior half of the middle facet. The ISP tendon attached to the entire middle facet, covering a portion of the SSP tendon. Thus, the anterior half of the superior cuff tendon (12.6 +/- 1.1 mm) was composed of only the SSP tendon, whereas the posterior half (9.8 +/- 3.2 mm) was composed of both the SSP and ISP tendons. The sulcus was located not at the SSP-ISP interval but slightly posterior to the posterior margin of the SSP tendon (4.3 +/- 2.4 mm). We conclude that (1) there is an overlap between the SSP and ISP tendons identifiable by the facets or the distance from the anterior greater tuberosity and (2) the sulcus is located slightly posterior to the posterior margin of the SSP tendon.

Aged↗
PubMed1998

Cystic changes of the humeral head on MR imaging. Relation to age and cuff-tears.

We obtained MR images of 140 painful shoulders in 134 patients to determine the relationship between cystic changes of the humeral head and integrity of the rotator cuff. Cystic changes were observed in 49 shoulders (35%) and the commonest site was in the bare bone area of the anatomical neck, and the second commonest site was at the attachment of the supraspinatus tendon. Cystic changes in the bare bone area were observed equally often in shoulders with or without rotator cuff tears (27% and 18%, respectively) and were more frequently observed in the elderly. Cystic changes at the attachment of the supraspinatus and subscapularis tendons were specific to rotator cuff tears: they were observed in 28% of rotator cuff tears, but in none of those with an intact cuff. We conclude that there are two distinct types of cystic changes: one at the attachment of the supraspinatus and subscapularis tendons, which is closely related to tears of these tendons, and the other in the bare bone area of the anatomical neck, which is related to aging.

Adolescent↗
PubMed1998

Electromyographic activities of the biceps during arm elevation in shoulders with rotator cuff tears.

We investigated electromyographic activities of the biceps in 40 shoulders with full-thickness tears of the rotator cuff and 40 asymptomatic shoulders, with a normal rotator cuff on MRI, to determine the role of the biceps in cuff-deficient shoulders. Using surface electrodes, biceps activities were recorded during arm elevation in the scapular plane with and without a 1-kg load. The percentages of integrated electromyograms to the maximum voluntary contraction (%MVC) were obtained at 30 degrees, 60 degrees, 90 degrees, and 120 degrees of elevation. In the normal shoulders, %MVC of the biceps was always less than 10% through the arc of elevation both with and without load. Among 40 shoulders with rotator cuff tears, 14 showed increased activities of the biceps more than 10% in %MVC (p < 0.0001), whereas the remaining 26 shoulders had activities similar to the normal shoulders. The biceps activities in these 14 shoulders increased with load application and at higher angles of elevation. The muscle strength tended to be weaker in shoulders with increased biceps activities than in those without. Our findings suggest a potential supplemental function of the biceps in shoulders with rotator cuff tears.

Adult↗
PubMed1998

Superior-inferior stability of the shoulder: role of the coracohumeral ligament and the rotator interval capsule.

OBJECTIVE: To study the superior-inferior stabilizing functions of the coracohumeral ligament (CHL) and the rotator interval capsule (RIC) with use of a material testing machine. MATERIAL AND METHODS: The axial translations of the humerus with the superior-inferior translation force of 30 N applied were recorded under the following joint capsule conditions: (1) intact, (2) vented, (3) the CHL sectioned, and (4) the RIC incised in six cadaver shoulders. The order of sectioning was changed for conditions 3 and 4 in six other cadaver shoulders. RESULTS: With the arm in internal and neutral rotations, venting the capsule significantly increased the superior-inferior translation, which was unaffected by further sectioning of the CHL and the RIC. With the arm in external rotation, only the CHL contributed significantly to inferior stability, whereas both this ligament and the RIC contributed to superior stability to a lesser degree. CONCLUSION: The CHL is a stabilizer in superior inferior directions with the arm in external rotation, and the intra-articular pressure that is maintained by the intact RIC is a stabilizer in superior-inferior directions with the arm in internal and neutral rotations. These findings may provide a scientific background to support closure of the interval space to stabilize the shoulder and may explain part of the superior instability observed in shoulders with rotator cuff tears.

Aged↗
PubMed1997

Intramuscular malignant granular cell tumor.

We describe a malignant granular cell tumor in the semimembranosus muscle of a 61-year-old woman. Magnetic resonance images disclosed a tumor with intermediate and low signal intensity on both T1- and T2-weighted images, measuring about 7 x 4 x 4 cm in size. The patient showed an uneventful clinical course during a 30-month follow-up period after the wide excision. The pertinent findings in making the diagnosis of malignant granular cell tumor are large size, intramuscular location, and mitosis including an atypical mitosis.

Biopsy↗
PubMed1997

Isokinetic strength after tears of the supraspinatus tendon.

We measured the isokinetic strength of abduction, adduction, internal rotation, and external rotation in ten patients with full-thickness tears of the supraspinatus and ten with partial-thickness tears. The measurements were repeated after intra-articular or intrabursal injection of local anaesthetic. Pain blocks produced significant increases in strength in both full and partial-thickness tears. After the block, the strength in full-thickness tears compared with the opposite side was 67% to 81% in abduction and 67% to 78% in external rotation, both significantly smaller than those on the uninvolved side (p = 0.0064, p = 0.0170). In partial-thickness tears the strength after the block ranged from 82% to 111%, with no significant differences between the involved and uninvolved sides. The decreases in strength of 19% to 33% in abduction and 22% to 33% in external rotation after full-thickness tears appear to represent the contribution of supraspinatus to the strength of the shoulder.

Adult↗
PubMed1995

Tensile properties of the supraspinatus tendon.

The tensile properties of the supraspinatus tendon were investigated in 11 shoulders from fresh cadavers. The tendon was divided into three longitudinal strips: anterior, middle, and posterior. Each specimen was mounted on a materials testing machine, with four fluorescent markers placed on both surfaces of the tendon strip. The positions of these markers were recorded during the test by two synchronized video cameras. Load-deformation and strain curves were determined, and the stress-strain curve, strength, and modulus of elasticity were calculated. The posterior strip was thinner in cross section than the others (p = 0.0355). The ultimate load and ultimate stress were significantly greater in the anterior strip (16.5 +/- 7.1 MPa) than in the middle (6.0 +/- 2.6 MPa) and posterior (4.1 +/- 1.3 MPa) strips (p < 0.0001). The modulus of elasticity also was significantly greater in the anterior strip (p < 0.0001), but there was no significant difference between the superficial and deep surfaces. It is concluded that the anterior portion of the supraspinatus tendon is mechanically stronger than the other portions, and it seems to perform the main functional role of the tendon.

Aged↗
PubMed1995

Morphology of the torn rotator cuff.

The morphological characteristics of shoulders with torn rotator cuffs were determined using 41 embalmed specimens. The following parameters were measured in the supraspinatus (SSP), infraspinatus (ISP) and subscapularis (SSC) muscles: the length, thickness and width of the extramuscular tendon; the length of the intramuscular tendon; the length and width of a tear, if present, muscle fibre length; and muscle volume. The cross-sectional area (CSA) of the tendon was measured on the photographic image of slices of the tendon using an image analysis system, and the CSA of the muscle was calculated by dividing the muscle volume by muscle fibre length. The rotator cuff was intact in 11 shoulders. A partial-thickness tear of the cuff was present in 12 shoulders, a full-thickness tear of the SSP in 11 shoulders, and a full-thickness tear of more than 2 tendons in 7. Overall incidence of full-thickness tears of the rotator cuff was 44%, and that of partial-thickness tears 29%. With increase of tear size, the functional tendon length (extramuscular tendon length plus tear length) increased by a statistically significant amount in the SSP, ISP and SSC, whereas muscle fibre length decreased in SSP and ISP. It is concluded that the increased functional tendon length and decreased muscle fibre length are the main morphological changes that make the rotator cuff a physiologically abnormal unit. Surgical repair of the torn cuff would be expected to improve these anatomical changes and restore the kinetics of the glenohumeral joint.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Malrotation of the humeral component of the capitellocondylar total elbow replacement is not the sole cause of dislocation.

Malrotation of the humeral component of the capitellocondylar total elbow replacement is thought but not proved to be one of the major causes of postoperative dislocation. The purpose of this study was to quantitate the effect of malrotation of the humeral component on the kinematics and laxity of the capitellocondylar total elbow prosthesis. Eleven fresh previously frozen elbows were used. With the humeral component in optimal position, external rotation, or internal rotation, movements of the elbow with neutral, valgus, and varus loading were monitored with an electromagnetic tracking device. When the humeral component was positioned in external rotation, the ulna was more valgus and supinated than when the component was in optimal position, and when the component was in internal rotation the ulna was more valgus in extension and more supinated in flexion. Malrotation in external rotation decreased valgus-varus laxity, and malrotation in internal rotation increased rotational laxity. Only one elbow became dislocated, despite constant severe maltracking between the components in all of the specimens. We concluded that although malrotation of the humeral component influences the laxity and causes maltracking, it is not the primary cause of postoperative dislocation. The contribution of other factors should be investigated.

Aged↗
PubMed1994

Effect of back-strengthening exercise on posture in healthy women 49 to 65 years of age.

OBJECTIVE: To evaluate the effect of back-strengthening exercise on posture in 60 healthy estrogen-deficient women. DESIGN: The 60 study subjects were randomly assigned to either an exercise or a control group, and various factors were assessed at time of enrollment in the study and at 2-year follow-up. MATERIAL AND METHODS: The 32 women in the exercise group were instructed in progressive back-strengthening exercises, whereas the 28 women in the control group had no exercise prescription and were asked to continue their usual physical and dietary activities. At baseline and 2-year follow-up examinations, back extensor strength was measured with a strain-gauge dynamometer, and lateral roentgenograms of the thoracic and lumbar areas of the spine were obtained to measure the angles of thoracic kyphosis, lumbar lordosis, and sacral inclination. The changes in radiographic measurements and back extensor strength were analyzed statistically. RESULTS: Back extensor strength increased significantly in both the exercise and the control groups, but no radiographic measurements were significantly different between these groups. The significant increase in back extensor strength in both groups of healthy women suggested that the original grouping did not accurately reflect the amount of exercise. Thus, the 60 subjects were reclassified for comparison on the basis of increase in back extensor strength--27 with more than or equal to the mean increase of 21.1 kg and 33 with less than 21.1 kg. Furthermore, each of these groups of subjects was subdivided on the basis of degree of thoracic kyphosis. Among the subjects with substantial thoracic kyphosis, those with a significant increase in back extensor strength had a significant decrease in thoracic kyphosis (-2.8 +/- 4.2 degrees; P = 0.041), whereas those with a small increase in strength had a nonsignificant increase in thoracic kyphosis (1.8 +/- 5.3 degrees). The increase in back extensor strength did not seem to affect mild degrees of kyphosis. CONCLUSION: Increasing the back extensor strength in healthy estrogen-deficient women helps decrease thoracic kyphosis.

Aged↗
PubMed1994

Motion and laxity of the capitellocondylar total elbow prosthesis.

The motion and laxity of the capitellocondylar unconstrained total elbow prosthesis were assessed, with use of an electromagnetic tracking device and stimulated muscle-loading, after implantation in seventeen cadaveric elbows. The axis of motion of the elbows with the capitellocondylar implants averaged 2.1 +/- 2.3 degrees more varus angulation than that of the intact elbows. This difference may be attributed to the design of the implant, as the 5-degree-valgus humeral component used in this study has a smaller valgus inclination than the articular surface of the distal aspect of the humerus. Although the maximum valgus-varus laxity of the capitellocondylar elbow prostheses was, on the average, 4.3 +/- 2.4 degrees greater than normal (with simulated muscle-loading), the data must be interpreted in light of the fact that this in vitro study did not allow for soft-tissue healing. The prosthetic components tracked well, and there were no dislocations or malarticulations provided that appropriate soft-tissue tensioning and positioning of the components had been achieved at the time of implantation. Sectioning of either the medial or the lateral collateral ligament resulted in gross instability of the joint after capitellocondylar arthroplasty. The ulnar attachment of the medial collateral ligament was found to be vulnerable to injury during the positioning of the ulnar component of this implant.

Aged↗
PubMed1994

Dynamic anterior stabilisers of the shoulder with the arm in abduction.

The stabilising effects on the glenohumeral joint of each of the rotator-cuff muscles and of the biceps were studied with the arm in abduction and external rotation in 13 cadaver shoulders. The muscles were loaded one at a time with forces proportional to their cross-sectional areas. We recorded the positions of the humeral head before and after the application to the humerus of an anterior force of 1.5 kg. When the capsule was intact, the anterior displacement with the subscapularis loaded was significantly larger than with the other muscles loaded (p = 0.0009). With the capsule vented, the displacement with the biceps loaded was significantly smaller than that with the subscapularis loaded (p = 0.0052). After creating an imitation Bankart lesion, the displacement with the biceps loaded was significantly less than with any of the rotator-cuff muscles loaded (p = 0.0132). We conclude that in the intact shoulder, the subscapularis is the least important anterior stabiliser, and that the biceps becomes more important than the rotator-cuff muscles as stability from the capsuloligamentous structure decreases. Strengthening of the biceps as well as the rotator-cuff muscles should be part of the rehabilitation programme for anterior shoulder instability.

Adult↗
PubMed1993

Intraarticular pressure of the shoulder.

Nine fresh frozen cadaveric shoulders were used to examine the changes in intraarticular pressure (IAP) of the shoulder joint and the position of the humeral head under various loads to determine the relationship between these parameters. All the soft tissues superficial to the rotator cuff were removed. The position of the humerus relative to the scapula was monitored using an electromagnetic tracking system before and after venting the capsule with 0, 0.5, and 1.0 kg of load applied to the humerus inferiorly in addition to the weight of the arm. Simultaneously, the IAP was monitored using a pressure transducer before venting the capsule. Venting had a significant effect on the position of the humeral head: the positions of the head after venting were significantly lowered in all loading conditions. The average IAP was -76 cm H2O without load, and the value decreased in a linear fashion with increased load; the correlations were significant in four of six shoulders without dislocation. The correlations were less significant between the pressure and the position, and there were no significant correlations between the load and the position. IAP, which is determined primarily by the load applied, is important to stabilize the shoulder inferiorly. Because IAP is intimately related to the external load and the response is specific to individuals, examination of IAP response to external load may be helpful in characterizing various instabilities of the shoulder.

Cadaver↗
PubMed1993

Stabilising function of the biceps in stable and unstable shoulders.

We studied the contributions of the long and short heads of the biceps (LHB, SHB) to anterior stability in 13 cadaver shoulders. The LHB and SHB were replaced by spring devices and translation tests at 90 degrees abduction of the arm were performed by applying a 1.5 kg anterior force. The position of the humeral head was monitored by an electromagnetic tracking device with or without an anterior translational force; with 0 kg, 1.5 kg or 3 kg loads applied on either LHB or SHB tendons in 60 degrees, 90 degrees or 120 degrees of external rotation; and with the capsule intact, vented, or damaged by a Bankart lesion. The anterior displacement of the humeral head under 1.5 kg force was significantly decreased by both the LHB and SHB loading in all capsular conditions when the arm was in 60 degrees or 90 degrees of external rotation. At 120 degrees of external rotation, anterior displacement was significantly decreased by LHB and SHB loading only when there was a Bankart lesion. We conclude that LHB and SHB have similar functions as anterior stabilizers of the glenohumeral joint with the arm in abduction and external rotation, and that their role increases as shoulder stability decreases. Both heads of the biceps have been shown to have a stabilising function in resisting anterior head displacement, and consideration should therefore be given to strengthening the biceps during rehabilitation programmes for chronic anterior instability of the shoulder.

Analysis of Variance↗