Ikuko Wakabayashi

Immobilization in external rotation after shoulder dislocation reduces the risk of recurrence. A randomized controlled trial.

BACKGROUND An initial anterior dislocation of the shoulder becomes recurrent in 66% to 94% of young patients after immobilization of the shoulder in internal rotation. Magnetic resonance imaging and studies of cadavera have shown that coaptation of the Bankart lesion is better with the arm in external rotation than it is with the arm in internal rotation. Our aim was to determine the benefit of immobilization in external rotation in a randomized controlled trial. METHODS One hundred and ninety-eight patients with an initial anterior dislocation of the shoulder were randomly assigned to be treated with immobilization in either internal rotation (ninety-four shoulders) or external rotation (104 shoulders) for three weeks. The primary outcome measure was a recurrent dislocation or subluxation. The minimum follow-up period was two years. RESULTS The follow-up rate was seventy-four (79%) of ninety-four in the internal rotation group and eighty-five (82%) of 104 in the external rotation group. The compliance rate was thirty-nine (53%) of seventy-four in the internal rotation group and sixty-one (72%) of eighty-five in the external rotation group (p = 0.013). The intention-to-treat analysis revealed that the recurrence rate in the external rotation group (twenty-two of eighty-five; 26%) was significantly lower than that in the internal rotation group (thirty-one of seventy-four; 42%) (p = 0.033) with a relative risk reduction of 38.2%. In the subgroup of patients who were thirty years of age or younger, the relative risk reduction was 46.1%. CONCLUSIONS Immobilization in external rotation after an initial shoulder dislocation reduces the risk of recurrence compared with that associated with the conventional method of immobilization in internal rotation. This treatment method appears to be particularly beneficial for patients who are thirty years of age or younger.

Position of immobilization after dislocation of the glenohumeral joint. A study with use of magnetic resonance imaging

Background: Glenohumeral dislocations often recur, probably because a Bankart lesion does not heal sufficiently during the period of immobilization. Using magnetic resonance imaging, we assessed the position of the Bankart lesion, with the arm in internal and external rotation, in shoulders that had had a dislocation. Methods: Coaptation of a Bankart lesion was examined with use of magnetic resonance imaging, with the arm held at the side of the trunk and positioned first in internal rotation (mean, 29°) and then in external rotation (mean, 35°), in nineteen shoulders. Six shoulders (six patients) had had an initial anterior dislocation, and thirteen shoulders (twelve patients) had had recurrent anterior dislocation. Fast-spin-echo T2-weighted axial images were made when the dislocation had occurred less than two weeks earlier, and spin-echo T1-weighted axial images after intra-articular injection of gadolinium-diethylenetriamine pentaacetic acid were made when the dislocation had occurred more than two weeks earlier. Separation and displacement of the anteroinferior portion of the labrum from the glenoid rim were measured on the axial images, and coaptation of the anterior part of the capsule to the glenoid neck was assessed by measurement of the detached area, opening angle, and detached length. Results: Separation and displacement of the labrum were both significantly less (p = 0.0047 and p = 0.0017, respectively) when the arm was in external rotation than when it was in internal rotation. The detached area and the opening angle of the anteroinferior portion of the capsule were both significantly smaller (p = 0.0003 and p < 0.0001, respectively), and the detached length was significantly shorter (p < 0.0001) with the arm in external rotation. Conclusion: Immobilization of the arm in external rotation better approximates the Bankart lesion to the glenoid neck than does the conventional position of internal rotation.

A new method of immobilization after traumatic anterior dislocation of the shoulder: a preliminary study

This preliminary prospective study was conducted to determine whether immobilization with the arm in external rotation would decrease the rate of recurrence after initial traumatic anterior dislocation of the shoulder. Forty patients with initial shoulder dislocations were assigned to (1) conventional immobilization in internal rotation (IR group, n = 20) or (2) a new method of immobilization in external rotation (ER group, n = 20). The recurrence rate was 30% in the IR group and 0% in the ER group at a mean 15.5 months. The difference in recurrence rate was even greater among those who were aged less than 30 years (45% in the IR group and 0% in the ER group). Immobilization with the arm in external rotation is effective in reducing the rate of recurrence after initial dislocation of the shoulder.

Inverse relation between osteoporosis and spondylosis in postmenopausal women as evaluated by bone mineral density and semiquantitative scoring of spinal degeneration

Study Design. The relation between bone mineral density and severity of spondylosis was evaluated in postmenopausal women. Objective. To examine the possible inverse relation between osteoporosis and spondylosis by evaluating the association between bone mineral density and osteophyte formation or intervertebral disc narrowing using a semiquantitative scoring system. Summary of Background Data. The literature contains studies demonstrating an inverse relation between osteoporosis and spondylosis as well as those documenting insufficient support for such a relation. However, in these studies, only limited-range grading systems (e.g., Grades 1–4) were used to evaluate the severity of spondylosis. Methods. In this study, 104 postmenopausal women older than 60 years underwent bone mineral density measurement of the lumbar spine (anteroposterior, lateral, and midlateral) and proximal femur (femoral neck, trochanter, and Ward’s triangle) using dual-energy x-ray absorptiometry. Raw data representing the semiquantitative osteophyte score and disc score as well as the number of vertebral fractures were obtained using spinal radiograph. Correlations between bone mineral density and the radiographic variable were then analyzed. Results. Significant negative correlations were found between all bone mineral density data and the number of vertebral fractures (−0.524 ≤r ≤ −0.347;P < 0.05). Marginal/moderate positive correlations were observed between the osteophyte score and the bone mineral density data (0.263 ≤ r ≤ 0.580, P < 0.05), and between the disc score and the bone mineral density data (0.233 ≤ r ≤ 0.570, P < 0.05). Conclusions. On the basis of the finding that spondylotic changes in postmenopausal women exhibit positive correlations not only with the lumbar bone mineral density, but also with the remote-site bone mineral density, this study supports the view that osteoporosis has an inverse relation with spondylosis.

Mechanical environment of the supraspinatus tendon: A two-dimensional finite element model analysis

We performed 2-dimensional finite element model analysis to estimate the mechanical environment of the supraspinatus tendon. The geometric shape of the finite element model was determined by magnetic resonance imaging of a normal human shoulder obtained at 0 degrees, 30 degrees, and 60 degrees of abduction, whereas the histologic location of noncalcified and calcified fibrocartilage was determined from a cadaveric specimen. The supraspinatus tendon was pulled proximally with the force of 10 N at 0 degrees, 53 N at 30 degrees, and 115 N at 60 degrees of abduction. The area of high principal stress maximum was observed on the articular side of the supraspinatus tendon, which shifted toward the insertion as the arm was abducted. High stress concentration on the articular side of the supraspinatus tendon near its insertion during arm elevation may explain the frequent occurrence of rotator cuff tears at this site.

Stress Distribution in the Supraspinatus Tendon After Tendon Repair Suture Anchors Versus Transosseous Suture Fixation

Background The stress concentration at the site of supraspinatus tendon repair, either by suture anchor fixation or by transosseous suture fixation, has not been fully clarified. Hypothesis Suture anchor fixation showed higher stress concentrations in the tendon than did transosseous suture fixation. Study Design Controlled laboratory study. Methods Three finite element models were developed based on a previously published model of normal supraspinatus tendon (0° abduction). Single-row fixation, double-row fixation, and transosseous suture fixation were simulated. A tensile force was applied to the proximal end of the supraspinatus tendon to simulate its contraction force. Results In the single-row model, the stress appeared from the site of the anchor and extended into the proximal tendon. The highest stress concentration was observed on the bursal surface of the tendon. The double-row model showed a similar pattern to the single-row model except that the stress concentration was observed only around the medial anchor. In the transosseous model, the stress appeared from the attachment site to a bony trough, which extended proximally into the tendon substance. No significant stress concentration was observed inside the tendon. Conclusion Both single-row and double-row fixations showed higher stress concentration inside the tendon than did transosseous suture fixation. Clinical Relevance A high stress concentration might be a cause of the rerupture often observed after arthroscopic cuff repair using suture anchors.

Atrophy of the rotator cuff muscles and site of cuff tears.

We determined the relationship between the site of rotator cuff tears and atrophy of the cuff muscles. 28 shoulders (28 patients) had rotator cuff tears: 19 isolated tears of the supraspinatus tendon (isolatedtear group) and 9 combined tears of the supraspinatus and infraspinatus tendons (combined-tear group). The cross-sectional area of the subscapularis, supraspinatus, the infraspinatus and teres minor muscles in the coronal oblique MR images were measured before and after surgery. Although we found no difference in tear size, the cross-sectional areas of the muscles were smaller in the combined-tear group than in the isolated-tear group. We conclude that atrophy of the supraspinatus and infraspinatus muscles also depends on the site of the tear.

Mechanical environment of the supraspinatus tendon: three-dimensional finite element model analysis

BackgroundWe analyzed the mechanical environment of the supraspinatus tendon using a three-dimensional finite element model with the software programs MENTAT and MARC.MethodsThe supraspinatus tendon that attaches to the superior facet was extracted and modeled. The geometric shape of the humeral head was determined from computed tomography images, and the shape of the supraspinatus tendon was determined from magnetic resonance images of the shoulder at 0° of abduction in a healthy 27-year-old man. The distal portion of the humeral head was fixed, and 10 N of tensile force was applied to the proximal end of the tendon. The tensile stress was calculated.ResultsThe tensile stress was 1.8 MPa for the bursal side and 15.0 MPa for the articular side of the anterior portion of the supraspinatus tendon. The intensity was 0 MPa for the bursal side and 4.5 MPa for the articular side of the middle portion of the tendon. The intensity was 0.1 MPa for the bursal side and 5.2 MPa for the posterior edge of the tendon.ConclusionsBased on the three-dimensional finite element method, the maximal tensile stress was observed on the articular side of the anterior edge of the supraspinatus tendon. Our result may explain the frequent occurrence of rotator cuff tears at this site.

Range of Motion after Bankart Repair Vertical Compared with Horizontal Capsulotomy

We studied the range of shoulder motion of patients who underwent vertical as compared with horizontal capsulotomies during open Bankart repair for recurrent anterior dislocations of the shoulder. A vertical capsulotomy was used in 10 shoulders and a horizontal capsulotomy was used in 14 shoulders. Except for the method of capsulotomy, the surgical procedure and postoperative rehabilitation were the same. The range of motion was measured at 1.5, 2, 3, 4, 5, 6, 9, and 12 months after the surgery, and at the final follow-up (average, 49 months for the vertical and 26 months for the horizontal group). No dislocations recurred, and the anterior apprehension test was negative in all of the patients in both groups. External rotation in abduction was greater in the horizontal group than in the vertical group; the differences were significantly greater at 9 months and 12 months after surgery and at the final follow-up. External rotation in adduction, flexion, and internal rotation were not significantly different between the groups. We conclude that Bankart repair through a horizontal capsulotomy preserves a better range of external rotation in abduction than does a vertical approach.

Intraosseous ganglion of the metatarsal bone.

We describe a rare case of intraosseous ganglion arising in the metatarsal bone. Radiographs revealed an osteolytic lesion with a fracture in the third metatarsal bone. A biopsied specimen exhibited hyaline fibrous tissue with marked myxoid change. Gadolinium-enhanced MRI, which revealed the network-like enhancement of the rim of the lesion and polycystic lesions adjacent to the joint, was helpful in making a diagnosis of intraosseous ganglion.