Keisuke Matsuki

Repair Integrity and Functional Outcome After Arthroscopic Double-Row Rotator Cuff Repair A Prospective Outcome Study

BACKGROUND The retear rate following rotator cuff repair is variable. Recent biomechanical studies have demonstrated that double-row tendon-to-bone fixation excels in initial fixation strength and footprint coverage compared with the single-row or transosseous fixation methods. This study was designed to report the repair integrity and clinical outcome following arthroscopic double-row rotator cuff repair. METHODS A consecutive series of 106 patients with full-thickness rotator cuff tears underwent arthroscopic double-row rotator cuff repair with use of suture anchors and were followed prospectively. Twenty patients lacked complete follow-up data or were lost to follow-up. The eighty-six study subjects included fifty-two men and thirty-four women, with an average age of 60.5 years. There were twenty-six small, thirty medium, twenty-two large, and eight massive tears. Clinical outcomes were evaluated at an average of thirty-one months. Repair integrity was estimated with use of magnetic resonance imaging, which was performed, on the average, fourteen months postoperatively, and was classified into five categories, with type I indicating sufficient thickness with homogeneously low intensity; type II, sufficient thickness with partial high intensity; type III, insufficient thickness without discontinuity; type IV, the presence of a minor discontinuity; and type V, the presence of a major discontinuity. RESULTS The average clinical outcome scores all improved significantly at the time of the final follow-up (p < 0.01). At a mean of fourteen months postoperatively, magnetic resonance imaging revealed that thirty-seven shoulders had a type-I repair; twenty-one, a type-II repair; thirteen, a type-III repair; eight, a type-IV repair; and seven, a type-V repair. The overall rate of retears (types IV and V) was 17%. The retear rate was 5% for small-to-medium tears, while it was 40% for large and massive tears. The shoulders with a type-V repair demonstrated significantly inferior functional outcome in terms of overall scores and strength compared with the other types of repairs (p < 0.01). CONCLUSIONS Arthroscopic double-row repair can result in improved repair integrity compared with open or miniopen repair methods. However, the retear rate for shoulders with large and massive tears remains higher than that for smaller tears, and shoulders with large repair defects (type V) demonstrate significantly inferior functional outcomes.

Humeral Insertion of the Supraspinatus and Infraspinatus. New Anatomical Findings Regarding the Footprint of the Rotator Cuff

BACKGROUND It is generally believed that the supraspinatus is the most commonly involved tendon in rotator cuff tears. Clinically, however, atrophy of the infraspinatus muscle is frequently observed in patients with even small to medium-size rotator cuff tears. This fact cannot be fully explained by our current understanding of the anatomical insertions of the supraspinatus and infraspinatus. The purpose of this study was to reinvestigate the humeral insertions of these tendons. METHODS The study included 113 shoulders from sixty-four cadavers. The humeral insertion areas of the supraspinatus and infraspinatus were investigated in ninety-seven specimens. In sixteen specimens, all muscular portions of the supraspinatus and infraspinatus were removed, leaving the tendinous portions intact, in order to define the specific characteristics of the tendinous portion of the muscles. Another twenty-six shoulders were used to obtain precise measurements of the footprints of the supraspinatus and infraspinatus. RESULTS The supraspinatus had a long tendinous portion in the anterior half of the muscle, which always inserted into the anteriormost area of the highest impression on the greater tuberosity and which inserted into the superiormost area of the lesser tuberosity in 21% of the specimens. The footprint of the supraspinatus was triangular in shape, with an average maximum medial-to-lateral length of 6.9 mm and an average maximum anteroposterior width of 12.6 mm. The infraspinatus had a long tendinous portion in the superior half of the muscle, which curved anteriorly and extended to the anterolateral area of the highest impression of the greater tuberosity. The footprint of the infraspinatus was trapezoidal in shape, with an average maximum medial-to-lateral length of 10.2 mm and an average maximum anteroposterior width of 32.7 mm. CONCLUSIONS The footprint of the supraspinatus on the greater tuberosity is much smaller than previously believed, and this area of the greater tuberosity is actually occupied by a substantial amount of the infraspinatus.

Humeral Insertion of the Supraspinatus and Infraspinatus

BACKGROUND It is generally believed that the supraspinatus is the most commonly involved tendon in rotator cuff tears. Clinically, however, atrophy of the infraspinatus muscle is frequently observed in patients with even small to medium-size rotator cuff tears. This fact cannot be fully explained by our current understanding of the anatomical insertions of the supraspinatus and infraspinatus. The purpose of this study was to reinvestigate the humeral insertions of these tendons. METHODS The study included 113 shoulders from sixty-four cadavers. The humeral insertion areas of the supraspinatus and infraspinatus were investigated in ninety-seven specimens. In sixteen specimens, all muscular portions of the supraspinatus and infraspinatus were removed, leaving the tendinous portions intact, in order to define the specific characteristics of the tendinous portion of the muscles. Another twenty-six shoulders were used to obtain precise measurements of the footprints of the supraspinatus and infraspinatus. RESULTS The supraspinatus had a long tendinous portion in the anterior half of the muscle, which always inserted into the anteriormost area of the highest impression on the greater tuberosity and which inserted into the superiormost area of the lesser tuberosity in 21% of the specimens. The footprint of the supraspinatus was triangular in shape, with an average maximum medial-to-lateral length of 6.9 mm and an average maximum anteroposterior width of 12.6 mm. The infraspinatus had a long tendinous portion in the superior half of the muscle, which curved anteriorly and extended to the anterolateral area of the highest impression of the greater tuberosity. The footprint of the infraspinatus was trapezoidal in shape, with an average maximum medial-to-lateral length of 10.2 mm and an average maximum anteroposterior width of 32.7 mm. CONCLUSIONS The footprint of the supraspinatus on the greater tuberosity is much smaller than previously believed, and this area of the greater tuberosity is actually occupied by a substantial amount of the infraspinatus.

In vivo 3-dimensional analysis of scapular kinematics: comparison of dominant and nondominant shoulders

BACKGROUND Alterations in scapular motion frequently are seen in association with various shoulder disorders. It is common clinically to compare the pathological shoulder with the contralateral shoulder, in spite of arm dominance, to characterize the disorder. However, there have been few articles that test the underlying assumption that dominant and nondominant shoulders exhibit comparable dynamic kinematics. The purpose of this study was to compare the 3-dimensional (3-D) scapular kinematics of dominant and nondominant shoulders during dynamic scapular plane elevation using 3-D-2-D (2-dimensional) registration techniques. MATERIALS AND METHODS Twelve healthy males with a mean age of 32 years (range, 27-36) were enrolled in this study. Bilateral fluoroscopic images during scapular plane elevation and lowering were taken, and CT-derived 3-D bone models were matched with the silhouette of the bones in the fluoroscopic images using 3-D-2-D registration techniques. Angular values of the scapula and scapulohumeral rhythm were compared between dominant and nondominant shoulders with statistical analysis. RESULTS There was a significant difference in upward rotation angles between paired shoulders (P < .001), while significant differences were not found in the other angular values and scapulohumeral rhythm. The dominant scapulae were 10° more downwardly rotated at rest and 4° more upwardly rotated during elevation compared to the nondominant scapulae. DISCUSSION/CONCLUSION Scapular motion was not the same between dominant and nondominant arms in healthy subjects. The dominant scapula was rotated further downward at rest and reached greater upward rotation with abduction. These differences should be considered in clinical assessment of shoulder pathology.

Dynamic In Vivo Glenohumeral Kinematics During Scapular Plane Abduction in Healthy Shoulders

STUDY DESIGN Controlled laboratory study. OBJECTIVES To measure superior/inferior translation and external rotation of the humerus relative to the scapula during scapular plane abduction using 3-D/2-D model image registration techniques. BACKGROUND Kinematic changes in the glenohumeral joint, including excessive superior translation of the humeral head and inadequate external rotation of the humerus, are believed to be a possible cause of shoulder impingement. Although many researchers have analyzed glenohumeral kinematics with various methods, few articles have assessed dynamic in vivo glenohumeral motion. METHODS Twelve healthy males with a mean age of 32 years (range, 27-36 years) were enrolled in this study. Fluoroscopic images of the dominant shoulder during scapular plane elevation were taken, and computed tomography-derived 3-D bone models were matched with the silhouette of the bones in the fluoroscopic images using 3-D/2-D model image registration techniques. The kinematics of the humerus relative to the scapula were determined using Euler angles. RESULTS On average, there was 2.1 mm of initial humeral translation in the superior direction from the starting position to 105° of humeral elevation. Subsequently, an average of 0.9 mm of translation in the inferior direction occurred between 105° and maximum arm elevation. The average amount of external rotation of the humerus was 14° from the starting position to 60° of humeral elevation. The humerus then rotated internally an average 9° by the time the shoulder reached maximum elevation. These changes in superior/inferior translation and external/internal rotation were statistically significant (P<.001 and P = .001, respectively), based on 1-way repeated-measures analysis of variance. CONCLUSION The observed glenohumeral translations and rotations characterize healthy shoulder function and serve as a preliminary foundation for quantifying pathomechanics in the presence of glenohumeral joint disorders.

Facet joint orientation difference between cephalad and caudad portions: a possible cause of degenerative spondylolisthesis.

Study Design. A case-control study. Objective. To measure the orientation of the facet joints at both cephalad and caudad portions and to compare them between patients with degenerative spondylolisthesis (DS) and patients with lumbar spinal stenosis (LSS, controls). Summary of Background Data. Several radiologic studies have indicated a correlation between DS and an increased sagittal orientation of the facet joints. However, the orientation of the facet joints have only been measured on 1 axial cut of computed tomography scans and magnetic resonance imaging. Methods. Thirty-two patients with DS only at the L4–L5 level were assigned to group-1, and 28 patients with LSS without DS were assigned to group-2. Two computed tomography scans for the cephalad and caudad portions of the facet joint were made for L3–L4 and L4–L5 levels, respectively. Delta facet angle was defined as facet angle (cephalad)–facet angle (caudad). Results. Facet angles of the cephalad portion were more sagittally oriented (P < 0.001) than those of the caudad portion in group-1. The mean facet angle of the cephalad portion was 72° and that of the caudad portion was 57° at L4–L5. The mean facet angle of the cephalad portion at L4–L5 was greater (P = 0.001) in group-1 (72°) than in group-2 (62°). Delta facet angles were significantly greater in group-1 than in group-2. Mean delta facet angle was 15° in group-1 and 2° in group-2 at L4–L5 (P < 0.001), and 4° and 0°, respectively, at L3–L4 (P = 0.046). Conclusion. In this study, we confirmed that the cephalad portion of the facet joints were more sagittally oriented and that the caudad portion of the facet joints were more coronally oriented in patients with DS. These findings were observed not only at L4–L5 but also at the uninvolved L3–L4 level in patients with DS at the L4–L5 level.

Subsequent vertebral fractures following spinal fusion surgery for degenerative lumbar disease: a mean ten-year follow-up.

Study Design. Case-control study. Objective. To assess the long-term prevalence of vertebral fractures after lumbar spinal fusion with instrumentation. Summary of Background Data. The incidence of the adjacent and the nonadjacent, remote level subsequent vertebral fractures after lumbar spinal fusion is not well described in the literature. Methods. The study is a retrospective analysis of 100 consecutive patients of 55 years of age or older with spinal fusion for degenerative diseases between L1 and S1, and instrumentation for less than 4 segments. Patients with prevalent vertebral fractures defined at the time of surgery, or patients with secondary causes of osteoporosis were excluded. Mean follow-up period was 10.2 years (range, 7–14 years). Acute vertebral fractures were determined by magnetic resonance imaging and lateral spine radiographs. Results. Acute vertebral fractures were determined in 20 vertebrae in 14 (24%) of the 59 female patients, whereas 1 male patient (2%) had 1 vertebral fracture during the follow-up period. Eighteen of the 21 fractures occurred within 2 years of the spinal instrumentation surgery. Regarding time to fracture occurrence after surgery, adjacent level fractures occurred within 8 months, and remote level fractures occurred between 8 and 22 months after surgery. Conclusion. Postmenopausal female patients who underwent lumbar spinal instrumentation surgery were susceptible to develop subsequent vertebral fractures within 2 years after surgery. The greater the number of spinal segments between the fracture and the instrumentation was, the longer the time after surgery.

In vivo 3D kinematics of normal forearms: Analysis of dynamic forearm rotation

BACKGROUND Forearm rotation is an indispensable activity of daily living and comprises complex motions with rotational and translational components. It is thought that changes in these motions with injury or disease may affect diagnostic indices. Several studies have assessed in vivo forearm kinematics with static conditions, but dynamic forearm kinematics have not yet been reported. The purpose of this study was to analyze forearm kinematics during dynamic rotation using radiographic 3D-2D registration methods. METHODS Ten forearms of five healthy males with the mean age of 37 years old were enrolled. Lateral fluoroscopic images were taken during forearm rotation from maximum supination to maximum pronation with their elbows flexed to approximately 45°. Geometric bone models were created from CT scans of the humerus, the radius and the ulna. Three-dimensional kinematics were determined using 3D-2D model registration techniques with the images and models, and the arc of axial rotation of the radius, volar/dorsal translation of the ulna at the distal radioulnar joint and rotation axis of forearm were computed. FINDINGS The radial rotation arc was 157°. The ulna translated 3.9 mm (SD 1.5mm) dorsally during activity. The rotation axis of the forearm passed through the center of the radial head and the ulnar head at the 1.9 mm (SD 0.7 mm) posterior from its geometric centroid. INTERPRETATION The posteriorly deviated rotation axis at the ulnar head may result in the ulnar head translating dorsally during pronation. These data provide a basis for objective assessment of pathological forearm function.

In vivo 3-dimensional analysis of scapular and glenohumeral kinematics: comparison of symptomatic or asymptomatic shoulders with rotator cuff tears and healthy shoulders.

BACKGROUND Alteration in shoulder kinematics has been suggested as one cause of symptoms in shoulders with rotator cuff tears (RCTs). However, only a few studies comparing symptomatic and asymptomatic RCTs using kinematic analysis have been performed. The purpose of this study was to compare 3-dimensional (3D) scapular and glenohumeral kinematics during scapular-plane abduction among symptomatic RCTs, asymptomatic RCTs, and healthy shoulders. METHODS This study included 7 healthy shoulders in subjects with a mean age of 62 years, 5 symptomatic RCTs in subjects with a mean age of 70 years, and 7 asymptomatic RCTs in subjects with a mean age of 67 years. All shoulders with RCTs had medium-sized tears (1-3 cm in the coronal plane) that were confirmed with magnetic resonance imaging. Biplane fluoroscopic images during scapular-plane abduction were recorded, and computed tomography-derived 3D bone models were matched with the silhouettes of the bones on the fluoroscopic images using 3D/2-dimensional model-image registration techniques. Angular values of the scapula and glenohumeral kinematics were compared among the 3 groups. RESULTS Posterior tilt of the scapula was significantly smaller in the symptomatic RCTs (3.1° ± 1.8°) than in healthy shoulders (10.4° ± 0.8°) (P = .049). The humerus of the symptomatic shoulders was less externally rotated relative to the scapula throughout the activity than the healthy shoulders and asymptomatic RCTs (P = .006 and P = .028 respectively). However, there were no kinematic differences between the asymptomatic RCTs and healthy shoulders. CONCLUSION Kinematic changes in symptomatic RCTs might be associated with development of symptoms. Improvement of these kinematic changes may be a key to successful conservative treatment for symptomatic RCTs.

Short-segment fixation without fusion for thoracolumbar burst fractures with neurological deficit can preserve thoracolumbar motion without resulting in post-traumatic disc degeneration: a 10-year follow-up study.

Study Design. Prospective consecutive series. Objective. To evaluate the post-traumatic disc degeneration and range of motion 10 years after short-segment fixation without fusion for thoracolumbar burst fractures with neurological deficit. Summary of Background Data. Early clinical results of short-segment fixation without fusion for thoracolumbar burst fractures were satisfactory. However, the long-term results have not been reported, and post-traumatic disc degeneration and preservation of thoracolumbar motion have not been elucidated. Methods. Twelve patients who had thoracolumbar burst fractures and associated incomplete neurological deficit, operatively treated within 4 days of admission and had their implants removed within 1 year, were prospectively followed for at least 10 years. Following indirect reduction and pedicle screw fixation, transpedicular intracorporeal hydroxyapatite grafting to the fractured vertebrae was performed. Results. Sagittal alignment was improved from a mean preoperative kyphosis of 17° to −2° (lordosis) by operation, but was found to have slightly deteriorated to 2° at the final follow-up observation. With respect to back pain, 8 patients did not report back pain. Three reported occasional minimal pain, and 1 reported moderate pain. None reported severe pain or needed daily dosages of analgesics. Regarding disc degeneration, the shape of the disc adjacent to the fractured vertebra had not changed from the preoperative to the 10-year postoperative magnetic resonance image (MRI). Although signal intensity of the disc had decreased by 1 grade from the preoperative to the 2-year postoperative MRI, the intensity had not changed from the 2-year postoperative MRI to the 10-year postoperative MRI. At the 10-year follow-up, flexion-extension radiographs revealed that a mean range of motion at the disc adjacent to the fractured vertebra was 12º (range; 5–19). Conclusion. This unprecedented 10-year follow-up study demonstrated that posterior indirect reduction, transpedicular hydroxyapatite grafting, and pedicle screw fixation does not require fusion to a segment, thereby preserves thoracolumbar motion without resulting in post-traumatic disc degeneration. Level of Evidence: 4