Katsuya Nobuhara

Pathologic evidence of degeneration as a primary cause of rotator cuff tear.

Histopathologic, histochemical, and morphometric studies were done on 80 medial stumps of torn rotator cuff tendons to clarify the cause of tears. A high prevalence and diffuse distribution of degenerative changes were observed in the rotator cuff tendons including thinning and disorientation of collagen fibers, myxoid degeneration, hyaline degeneration, chondroid metaplasia, calcification, vascularproliferation, and fatty infiltration. No distinct inflammatory reaction was observed. Thinning and disorientation of collagen fibers, myxoid degeneration, and hyaline degeneration were seen in all cases. All changes except vascular proliferation and fatty infiltration were more pronounced in the middle to deep layers of the tendons than in the superficial layer. The collagen fibers were disoriented in the deep layer of the tendons, shown by microscopic image analysis. The frequency and distribution of thinning and disorientation of collagen fibers, myxoid degeneration, and hyaline degeneration suggest that these are early degenerative processes. Chondroid metaplasia and calcification may be chronic pathologic changes that occur after tearing regardless of the type of tear. Preexisting degenerative change in the middle and deep layers of the tendon in association with microtrauma seems to be the main cause of rotator cuff tears.

Rotator interval lesion.

Arthrography and surgical exploration reveal the pathogenesis of a painful shoulder syndrome characterized by inferior instability in the rotator interval (RI). The RI is the space between the subscapularis and the adjacent supraspinatus interval. Two types of RI lesions can be identified. Type I, a contracted state, is characterized by inflammatory changes in superficial bursal area. In Type II, an unstable condition is associated with extensive inflammation of deeper tissues in the RI. In a series of 101 patients, including 106 shoulders with RI lesions, surgical repair of the RI was performed with the shoulder in an externally rotated position. This position ensured a close fit of the supraspinatus and the subscapularis attachments. Of 78 shoulders evaluated in a follow-up study, 96% were graded good or excellent, and 4% poor. This investigation presents evidence for the importance of diagnosis and treatment of RI lesions in patients with persistent pain in the shoulder.

Surgical procedure and results of repair of massive tears of the rotator cuff.

One hundred eighty-seven patients (189 shoulders) were treated surgically between 1970 and 1992 for massive rotator cuff tears using either a tendon-to-tendon repair or the McLaughlin procedure. The age of the patients ranged from 20 to 86 years; 95% of them were 45 years or older. The average followup was 6 years 9 months. Excellent or good functional results were attained in 93% of patients. Thirty-three percent of those who underwent tendon to tendon repair complained of pain after overuse compared with only 18% who had the McLaughlin Procedure.

Loss of glenohumeral internal rotation in little league pitchers: A biomechanical study

Glenohumeral internal rotation deficit (GIRD) is a significant shoulder problem for throwing athletes. GIRD, however, has not been reported in little league pitchers. The purpose of this study was to investigate GIRD in little leaguers. The range of motion of both shoulders was measured in 25 male little league pitchers. All pitchers underwent motion analyses of their pitching to evaluate shoulder kinematics. GIRD was found in 10 of the 25 pitchers. External rotation in the dominant arm in the GIRD group was not significantly different compared to the contralateral or dominant arm in the non-GIRD group. This biomechanical study showed that the GIRD group had increased external rotation while throwing compared to the non-GIRD group. These findings indicate that GIRD can occur prior to development of the increased external rotation in the dominant arm seen in adult throwers.

Glenoid shape in atraumatic posterior instability of the shoulder

Glenoid shape is related closely to shoulder stability and its abnormality is thought to affect the humeral head position in shoulders with atraumatic instability. However, it is unclear how the glenoid shape in shoulders with atraumatic instability is different from the glenoid shape in normal shoulders. The current authors investigated glenoid shape of 45 healthy individuals (20 males and 25 females; average age, 22 years) and 20 patients with atraumatic posterior instability with multidirectional laxity (six males and 14 females; average age, 19 years) using three-dimensional magnetic resonance imaging. The tilting angles of the glenoid bone were measured in five consecutive planes perpendicular to the long axis of the glenoid and cross sections were divided into three types (concave, flat, convex). In healthy individuals, the average tilting angles from the bottom to the top of the glenoid bone were 3.0° ± 3.6°, 1.0° ± 3.2°, −1.0° ± 2.0°, −2.3° ± 3.9°, and −6.9° ± 3.7° anteriorly, and tilting angles of patients were −6.1° ± 4.0°, −4.0° ± 3.6°, −4.8° ± 3.2°, −5.5° ± 2.7°, and −7.5° ± 3.1°. The type of cross section also was different on the bottom plane where the concave shape accounted for 78% of healthy individuals whereas it accounted for 0% of patients. The loss of tilting angles and concavity of the inferior glenoid would correlate with the direction of the head translation in posterior instability.

Evaluation of three-dimensional glenoid structure using MRI

The tilting angle and the shape of the glenoid cavity are considered to relate closely to shoulder stability. They are also important when planning arthroplasty and developing new designs. This study examines the glenoid cavity using 3‐dimensional MRI. Forty volunteers (20 men, 20 women; average age 21.4; range 18–35 y) were enrolled in the study. The tilting angles of the glenoid bone were measured in 5 consecutive axial planes perpendicular to the glenoidal long axis. Cross sections were divided into 3 types (concave, flat, convex) according to the shape on each plane.

Dynamic analysis of intraarticular pressure in the glenohumeral joint

Dynamic analysis of intraarticular pressure was performed in 180 glenohumeral joints. The intraarticular pressure demonstrated characteristic changes during shoulder movement. In the healthy group minimum pressure was measured at 40 degrees of elevation in the scapular plane. In patients with contractures the pressure increased in the early phase of elevation and persisted. Pressure changes of the group with incomplete tears of the rotator cuff resembled those of the healthy group, whereas those in the massive tear group showed only slight pressure changes. When patients with rotator cuff tears had no limitation of arm elevation, pressure changes close to the normal pattern were found. However, when active elevation was markedly limited, no significant pressure changes were noted in some cases. In unstable shoulders the rate of pressure increase was slower, and the range of pressure changes was more limited than that in the healthy group. It is speculated that changes in intraarticular pressure reflect the intraarticular volume. Measurement of the intraarticular pressure may be clinically useful in functional assessment.

Use of Virtual, Interactive, Musculoskeletal System (VIMS) in Modeling and Analysis of Shoulder Throwing Activity

Our purpose in this study was to apply the virtual, interactive, musculoskeletal system (VIMS) software for modeling and biomechanical analysis of the glenohumeral joint during a baseball pitching activity. The skeletal model was from VIMS library and muscle fiber attachment sites were derived from the visible human dataset. The muscular moment arms and function changes are mainly due to the large humeral motion involved during baseball pitching. The graphic animation of the anatomic system using VIMS software is an effective tool to model and visualize the complex anatomical structure of the shoulder for biomechanical analysis.

External rotation during elevation of the arm

Background Knowledge about the pattern of rotation during arm elevation is necessary for a full understanding of shoulder function, and it is also useful for planning of rehabilitation protocols to restore range of motion in shoulders in disorder. However, there are insufficient in vivo data available. Methods We investigated dynamic arm rotation during elevation in different planes using 30 shoulders in 15 healthy men (age range 21–33 years). Both arms were moved from neutral dependent position to maximum elevated position in 4 planes from laterally to anteriorly, and each dynamic course of motion was traced using a 3-dimensional motion capture system. Results Patterns of rotation were categorized as being one of 2 types, depending on whether or not external rotation peaked before the arm reached the maximum elevated position. External rotation peaked at 122˚ (SD14) of abduction, then decreased according to the arm movement in the lateral planes, but increased gradually to maximum elevated position in the anterior planes. Mean maximal angles of external rotation (in degrees) during elevation were 27 (SD11), 13 (SD13), 3 (SD9), and 3 (SD5), from laterally to anteriorly. Interpretation There were differences in rotational patterns, and more external rotation was needed to reach maximum elevation in lateral planes than in anterior planes.

Effects of joint distention in shoulder diseases.

From 1982 to 1992 arthrography was performed in 3707 patients with painful shoulders to determine the role of the subscapular bursal obliteration in the pathogenesis of painful, stiff shoulders and to evaluate the effects of distention on the subscapular bursa. Three hundred thirty-nine patients were excluded from the study because of incomplete data, leaving 3368. There were 2391 male and 977 female patients; their average age was 39.2 years (range, 8-86 years). Obliteration was noted in 1156 patients (34.3%), and filling of the bursa was seen in 2212 patients (67.7%). Function was regained in 178 patients (5%) by fluid distention alone, and in 308 (8%) patients by additional forced motion. Thus, 486 shoulders (14%) underwent distention and mobilization successfully. The most effective motion was forced abduction and internal rotation. Four hundred fifteen subjects were evaluated clinically; immediate pain relief after distention and/or bursting of the subscapular bursa was noted in all. There was also a remarkable improvement in the range of motion in all subjects who underwent distention alone, or in combination with forced mobilization.