Norimasa Takahashi

Application of shock waves to rat skin decreases calcitonin gene-related peptide immunoreactivity in dorsal root ganglion neurons.

There have been several reports on the use of extracorporeal shock waves in the treatment of pseudarthrosis, calcifying tendinitis, and tendinopathies of the elbow. However, the pathomechanism of pain relief has not been clarified. To investigate the analgesic properties of shock wave application, we analyzed changes in calcitonin gene-related peptide (CGRP)-immunoreactive (ir) dorsal root ganglion (DRG) neurons. In the nontreated group, fluorogold-labeled dorsal root ganglion neurons innervating the most middle foot pad of hind paw were distributed in the L4 and L5 dorsal root ganglia. Of these neurons, 61% were CGRP-ir. However, in the shock wave-treated group, the percentage of FG-labeled CGRP-ir DRG neurons decreased to 18%. These data show that relief of clinical pain after shock wave application may result from reduced CGRP expression in DRG neurons.

Second application of low-energy shock waves has a cumulative effect on free nerve endings.

Some physicians recommend treating tendinopathies with multiple sessions of shock waves. Some evidence, however, suggests shock wave application can induce nerve fiber degeneration. We questioned whether repeated shock wave application provides a cumulative effect on nerve fibers compared with the effect of one application. One thousand shock wave impulses of an energy flux density of 0.08 mJ/mm2 were applied to the foot pad of 32 rats. After 14 days, 16 rats received a second application. The foot pads were resected on Days 7, 14, 28, and 42. Sections were processed immunohistochemically using antibodies for sensory nerve. We compared the number of epidermal nerve fibers in rats that received one application of shock waves with the fibers in rats that received two applications. During the first 4 weeks, there was nearly complete degeneration of epidermal nerve fibers in both groups. By the end of 6 weeks, reinnervation of the epidermis began in the single-treatment group. Reinnervation occurred slower in the repeated-treatment group. These data show that a second application has a cumulative effect on nerve fibers. Our data suggest multiple applications of low-energy shock waves might a provide longer-lasting antinociceptive effect.

Extracorporeal shockwaves induce the expression of ATF3 and GAP-43 in rat dorsal root ganglion neurons.

Although extracorporeal shockwave has been applied in the treatment of various diseases, the biological basis for its analgesic effect remains unclear. Therefore, we investigated the dorsal root ganglion neurons of rats following shockwave exposure to the footpad to elucidate its effect on the peripheral nervous system. We used activating transcription factor 3 (ATF3) and growth-associated phosphoprotein (GAP-43) as markers for nerve injury and axonal regeneration, respectively. The average number of neurons immunoreactive for ATF3 increased significantly in the treated rats at all experimental time points, with 78.3% of those neurons also exhibiting immunoreactivity for GAP-43. Shockwave exposure induced injury of the sensory nerve fibers within the exposed area. This phenomenon may be linked to the desensitization of the exposure area, not the cause of pain, considering clinical research with a particular absence of painful adverse effect. Subsequent active axonal regeneration may account for the reinnervation of exposed area and the amelioration of the desensitization.

Nerve Regeneration After Radiofrequency Application

Background Many patients with chronic tendinosis have experienced early pain relief after application of bipolar radiofrequency treatment. It is hypothesized that the mechanism of action may be the acute degeneration and/or ablation of sensory nerve fibers. Hypothesis After ablation or degeneration by bipolar radiofrequency, nerve fibers will have the ability to regenerate with time. Study Design Controlled laboratory study. Methods Eighteen Sprague-Dawley rats were used in this study. These rats were divided into 3 groups (30, 60, and 90 days after bipolar radiofrequency). These rats were treated with 2 points of bipolar radiofrequency applications to the left hindpaws with the Topaz microdebrider device. Right hindpaws were used as the contralateral control. Tissues were processed for neural class III β-tubulin or calcitonin gene-related peptide immunohistochemistry by using the free-floating avidin biotin complex technique. The numbers of neural class III β-tubulin—immunoreactive and calcitonin gene-related peptide-immunoreactive nerve fibers in the epidermis were counted and compared with those in the contralateral control. Results Although the numbers of nerve fibers demonstrated by both the antibodies of neural class III β-tubulin and calcitonin gene-related peptide were significantly decreased (P < .0001) until 60 days after bipolar radiofrequency treatment, regeneration of the epidermal nerve fibers occurred 90 days after treatment. Conclusion Bipolar radiofrequency treatment induced degeneration of sensory nerve fibers immediately after treatment, but by 90 days posttreatment, there was evidence of complete regeneration. Clinical Relevance Early degeneration followed by later regeneration of nerve fibers after bipolar radiofrequency treatment may explain long-term postoperative pain relief after microtenotomy for tendinosis.

Clinical Outcome and Glenoid Morphology After Arthroscopic Repair of Chronic Osseous Bankart Lesions: A Five to Eight-Year Follow-up Study.

BACKGROUND Arthroscopic osseous Bankart repair for shoulders with chronic recurrent anterior instability has been reported as an effective procedure with promising short-term outcomes. However, to date, we know of no report describing longer-term outcomes and glenoid morphologic change. The purpose of the present study was to report intermediate to long-term outcomes and glenoid morphologic change after arthroscopic osseous Bankart repair in patients with substantial glenoid bone loss. METHODS A consecutive series of eighty-five patients with traumatic anterior glenohumeral instability associated with a chronic osseous Bankart lesion underwent arthroscopic repair from January 2005 through December 2006. Forty-six patients with bone loss of >15% of the inferior glenoid diameter relative to the assumed inferior circle regardless of the fragment size were selected as candidates for this study. Thirty-eight patients (83%), including thirty-four male and four female patients, with a mean age of 23.4 years (range, fifteen to thirty-six years) at the time of surgery, were available for final follow-up at a mean of 6.2 years (range, 5.0 to 8.1 years) after surgery. RESULTS One patient had a redislocation during a traffic accident five months after surgery before obtaining an osseous union. The mean Rowe score and the mean Western Ontario Shoulder Instability Index improved significantly from 30.7 points preoperatively to 95.4 points postoperatively and from 26.5% to 81.5%, respectively. Although the mean preoperative fragment size was measured as only 4.7%, the mean glenoid bone loss improved from 20.4% preoperatively to -1.1% postoperatively. CONCLUSIONS Arthroscopic osseous Bankart repair is an effective primary treatment for shoulders with substantial glenoid bone loss as it provides successful outcomes without recurrence of instability once osseous union is obtained. Glenoid morphology can be normalized during the intermediate to long-term postoperative period, even in shoulders with a smaller fragment.

Arthroscopic management of selective loss of external rotation after surgical stabilization of traumatic anterior glenohumeral instability: arthroscopic restoration of anterior transverse sliding procedure.

PURPOSE The purpose of this study was to clarify the effectiveness of an arthroscopic procedure for restoration of anterior transverse sliding (RATS) mechanism of the subscapularis tendon in patients with loss of external rotation after surgical stabilization of anterior glenohumeral instability. METHODS Seven patients who underwent an arthroscopic RATS procedure for loss of external rotation after surgical stabilization of anterior glenohumeral instability were retrospectively reviewed. There were 4 male and 3 female patients with a mean age of 30.7 years. The original procedure was arthroscopic Bankart repair and rotator interval closure in 5 patients, open Bankart repair in 1, and an open Bristow procedure in 1. The arthroscopic RATS procedure was performed as follows: (1) removal of the fibrous tissue in the rotator interval; (2) release of the subscapularis tendon from the glenoid neck; and (3) incision of the superior part of the inferior glenohumeral ligament until a sufficient external rotation angle was obtained without causing anterior instability. We evaluated the mean forward flexion and external and internal rotation angles, Constant score, and University of California, Los Angeles score before the arthroscopic RATS procedure and at final follow-up (mean, 24 months). RESULTS The mean forward flexion and external and internal rotation angles improved from 162.1° ± 9.5° to 171.4° ± 3.8° (P < .05), from 2.9° ± 4.9° to 47.9° ± 9.1° (P < .005), and from T10 to T8 (P < .05), respectively. The mean Constant and University of California, Los Angeles scores improved from 81.0 ± 13.6 points to 95.1 ± 4.0 points and from 24.0 ± 3.7 points to 33.9 ± 2.0 points, respectively (P < .005). CONCLUSIONS The arthroscopic RATS mechanism procedure is a useful treatment option with minimum morbidity in patients with loss of external rotation after surgical stabilization of traumatic anterior glenohumeral instability. LEVEL OF EVIDENCE Level IV, therapeutic case series.

Rotator Cuff Lesions in Patients with Stiff Shoulders: A Prospective Analysis of 379 Shoulders.

BACKGROUND Idiopathic adhesive capsulitis is defined as a frozen shoulder with severe and global range-of-motion loss of unknown etiology. The purpose of our study was to clarify the prevalence of rotator cuff lesions according to patterns and severity of range-of-motion loss in a large cohort of patients with stiff shoulders. METHODS Rotator cuff pathology was prospectively investigated with use of magnetic resonance imaging (MRI) or ultrasonography in a series of 379 stiff shoulders; patients with traumatic etiology, diabetes, or radiographic abnormalities were excluded. Eighty-nine shoulders demonstrated severe and global loss of passive motion (≤100° of forward flexion, ≤10° of external rotation with the arm at the side, and internal rotation not more cephalad than the L5 level) and were classified as having severe and global loss of motion (Group 1). The remaining 290 shoulders were divided into two groups: those with severe but not global loss (Group 2; 111 shoulders) and mild to moderate limitation (Group 3; 179 shoulders). RESULTS Among all shoulders, imaging demonstrated an intact rotator cuff in 51%, a full-thickness tear in 35%, and a partial-thickness tear in 15%. In Group 1, 91% had an intact rotator cuff and 9% had a partial-thickness rotator cuff tear. No patient in this group demonstrated a full-thickness tear. In Group 2 and Group 3, respectively, 44% and 35% of the shoulders were intact, 17% and 16% had a partial-thickness tear, and 39% and 50% had a full-thickness tear. CONCLUSIONS Shoulder stiffness with severe and global loss of passive range of motion is not associated with full-thickness rotator cuff tears, although some patients may have a partial-thickness tear. Shoulders with severe and global loss of range of motion at a first visit are likely to be cases of idiopathic adhesive capsulitis and may not require further imaging studies.

Osteochondritis Dissecans of the Humeral Capitellum in Young Athletes: Comparison Between Baseball Players and Gymnasts

Background: Osteochondritis dissecans (OCD) lesions are often observed in the humeral capitellum both in young baseball players and gymnasts. It is generally believed that capitellar OCD in baseball players can be seen on an anteroposterior (AP) radiograph with the elbow in 45° of flexion. However, the mechanism of injury seems to be different in baseball players and gymnasts. Repetitive valgus overload with the elbow in flexion is believed to be the cause of capitellar OCD lesions in baseball players, whereas weightbearing with the elbow in extension may be the cause of OCD in gymnasts. Purpose: To determine the difference in capitellar OCD location between baseball players and gymnasts and to propose the optimal AP radiographic angle of the elbow for visualization of early-stage OCD lesions in adolescent gymnasts. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Subjects consisted of 95 baseball players (95 elbows) and 21 gymnasts (24 elbows) with a mean age of 13.7 years (range, 11-18 years). To localize the lesion, inclination of the affected area in the humeral capitellum against the humeral axis was investigated using sagittal computed tomography images of the elbow. The inclination angle was defined as the angle between the long axis of the humerus and the line perpendicular to a line that connected the anterior and posterior margin of the lesion. The inclination angle in each group was compared and statistically analyzed. Results: The mean inclination angle was 57.6° ± 10.7° in baseball players and 28.0° ± 10.7° in gymnasts. Capitellar OCD lesions were located more anterior in baseball players when compared with gymnasts (P < .01). Conclusion: Due to differences in applied stress, capitellar OCD lesions in baseball players were located more anteriorly compared with those seen in gymnasts. Therefore, although AP radiographs with the elbow in 45° of flexion are optimal for detecting OCD lesions in baseball players, radiographs with less elbow flexion or full extension are more useful in gymnasts, especially in early-stage OCD.

Progression of degenerative changes of the biceps tendon after successful rotator cuff repair

BACKGROUND This study investigated the morphologic changes in the biceps tendon using ultrasonography before and after successful arthroscopic posterosuperior rotator cuff repair. METHODS Forty-four patients (44 shoulders) underwent arthroscopic posterosuperior rotator cuff repair with 1-year postoperative magnetic resonance imaging (MRI) follow-up. The patients comprised 22 men and 22 women with an average age of 61 years. The cross-sectional area (CSA) of the biceps tendon in the bicipital groove was measured, and the vascularity in the bicipital groove was graded as 0 to 3, based on the signal density of the anterior circumflex artery, using power Doppler ultrasonography. The preoperative and postoperative CSA and vascularity grades were compared. The pain score on the University of California, Los Angeles Shoulder Rating Scale was used to analyze the correlation between vascularity and postoperative pain. RESULTS The average preoperative and postoperative CSA of the biceps tendon was 15.4 ± 6.5 and 17.9 ± 7.5 mm2, respectively. The postoperative CSA was significantly larger than the preoperative CSA (P < .01). Although no significant difference in the vascularity of the bicipital groove was observed between preoperative and postoperative grading, a negative correlation was observed between the vascularity and postoperative pain score on the University of California, Los Angeles scale (r = -0.369). CONCLUSIONS The biceps tendon in the bicipital groove becomes thicker over time, even after successful posterosuperior rotator cuff repair. In addition, an increase in the vascularity around the biceps tendon in the groove is correlated with pain symptoms after successful repair.

Mid to Long Term Outcome after Arthroscopic Fragment Resection for Capitellar Osteochondritis Dissecans in Adolescent Athlete

Objectives: Capitellar osteochondritis dissecans (OCD) in skeletally immature athletes were often seen in baseball players and gymnasts, and surgeries are indicated for unstable lesions. From 2002 to 2010, we had performed arthroscopic (AS) fragment resection for all inviable lesions regardless of lesion size, though osteochondral grafting have been added for larger lesions since 2010. Several studies have reported short-term outcomes after AS resection for capitellar OCD in adolescent athletes; however, long-term outcomes have not been reported. The purpose of this retrospective study was to investigate functional outcomes and arthritic change in a mid to long-term postoperative period after AS resection for capitellar OCD with small to large lesions in adolescent athletes. Methods: Between 2002 and 2010, 77 elbows in 76 consecutive patients with skeletally immature elbows, which had open epiphyseal lines in the contralateral elbow, underwent AS resection for capitellar OCD. Forty-three elbows in 43 patients (38 males and 5 females with a mean age of 14 years (13-15) who were followed up for at least 5 years (average 8 years; 5-12) were included in this study. Thirty-two patients were engaged in baseball, 7 in gymnastics, and 4 in other sports. The size of OCD lesions was determined with preoperative radiographs. Elbows with a lesion which width did not exceed 1/2 of radial head diameter were assigned to group S (19 elbows), and elbows with a larger lesion to group L (24 elbows). Sports return, DASH score, patient satisfaction, and range of motion (ROM) were reviewed. Radiographs at final follow-up were obtained from 17 and 21 elbows in groups S and L, respectively, and pre- and postoperative osteoarthritis (OA) grade were evaluated. Mann-Whitney’s U test (for sports return and OA progression), paired t test (for pre- and postoperative ROM) and Welch’s T test (for satisfaction, DASH score, and ROM) were used for comparison between the two groups. Results: All patients returned to sports activity, and there was no significant difference in sports return rates between the groups with 17 (89%) and 21 (88%) full-return patients in groups S and L, respectively. DASH score at final follow-up had also no difference. Patient satisfaction (0 to 100 scale) was 91 (70-100) in Group S, and 78 (50-100) in Group L, and the difference was significant (p< 0.01). Flexion ROM at final follow-up did not show significant improvement in both groups compared to preoperative values: Group S, 135 (115-150) to 141 (125-150) degrees; group L, 131 (110-145) to 133 (120-145) degrees. There was a significant difference in flexion ROM at final follow-up between the groups (P=0.001). Extension ROM showed significant improvement in both groups: group S, -8 (-25-5) to 3 (-10-13) degrees (P<0.001); group L -17 (-50-0) to -1 (-15-20) degrees (P<0.001). Group S tended to have better extension than group L, but the differences was not significant (P=0.05). There were no severe OA elbows in both groups. OA change progressed in 2 elbows (12%) in Group S and 4 elbows (19%) in Group L, and the difference was not significant. Conclusion: Both functional outcomes and radiological findings after AS fragment resection were excellent in elbows with a small lesion. Although, in elbows with larger lesions, overall outcomes were acceptable, ROM and patient satisfaction were inferior to those with small lesions. AS resection can be an effective treatment for elbows with a small OCD lesion as well as for those with a large lesion.