Clinical outcomes of medialized single-row repair with fascia lata graft augmentation for large and massive rotator cuff tears.

BACKGROUND: A high postoperative retear rate after arthroscopic rotator cuff repair (ARCR) of large and massive tears remains a problem. This study evaluated rotator cuff integrity after ARCR with fascia lata graft augmentation for large and massive rotator cuff tears and compared clinical outcomes between patients with intact repairs and retears. METHODS: Forty-five patients with rotator cuff tears who could not undergo primary repair due to tendon retraction underwent arthroscopic medialized single-row repair with fascia lata graft augmentation. The patients' minimum follow-up was 2 (2-9) years. Supraspinatus cuff integrity was evaluated postoperatively by magnetic resonance imaging. We compared the clinical outcomes of patients with intact repairs vs. retears based on the University of California-Los Angeles (UCLA), Constant, and Japanese Orthopaedic Association (JOA) scores. We also evaluated their range of motion (ROM) and muscle strength. RESULTS: Retears were observed in 11 of 45 patients. UCLA, Constant, and JOA scores significantly improved postoperatively compared to preoperatively in the intact repair (all P < .001) and retear (all P < .036) groups. The intact repair group had significantly higher Constant (75.6 [mean] ± 9.9 [SD] vs. 69.8 ± 7.9; P = .026) and JOA (94.4 ± 6.9 vs. 89.8 ± 5.9; P = .041) scores than the retear group. Forward elevation, abduction, and the strengths of abduction and external rotation significantly improved in the intact repair group (all P < .003) but not in the retear group (all P > .05). The intact repair group had significantly higher postoperative forward flexion (165° ± 15° vs. 154° ± 23°; P = .036), abduction (164° ± 17° vs. 151° ± 26°; P = .029), and abduction strength (3.5 ± 2.2 kg vs. 2.3 ± 1.2 kg; P = .017) than the retear group. In the intact repair group (n = 34), Sugaya type I:II ratio differed significantly between postoperative 3 months (2:32) and 24 months (24:10) (P < .001). Repaired tendon thickness did not decrease significantly between 3 months (7.1 mm) and 2 years (6.9 mm) (P = .543). CONCLUSIONS: ARCR with fascia lata graft augmentation of large and massive rotator cuff tears showed a 24.4% retear rate but significantly improved the clinical scores, ROMs, and muscle strength with excellent cuff integrity in the intact repair group. However, the differences in the Constant and UCLA scores between the intact repair and retear groups were under the minimal clinically important difference, and their clinical significance is uncertain. Our results confirm that ARCR with fascia lata graft augmentation improves patients' postoperative outcomes if the repair site is maintained postoperatively.

Sequential Changes in Posterior Shoulder Muscle Elasticity After Throwing as Assessed via Ultrasound Shear Wave Elastography.

BACKGROUND: Improvements in ultrasound diagnostic equipment and techniques can enable muscle stiffness to be measured quantitatively as muscle elasticity using ultrasound shear wave elastography (USWE), where high muscle elasticity values represent muscle stiffness. PURPOSE: To use USWE to analyze the sequential changes in muscle elasticity in the posterior shoulder before and after pitching. STUDY DESIGN: Descriptive laboratory study. METHODS: The authors evaluated 14 baseball players who had played in high school or college at an intermediate level. The elasticity of the supraspinatus, infraspinatus (ISP), middle trapezius, lower trapezius (LT), rhomboideus, and serratus anterior muscles of the throwing shoulder was measured using USWE at 3 time points: before, immediately after, and 24 hours after a throwing session of 100 pitches. The authors analyzed the sequential changes in the mean elasticity values of the respective muscles at the 3 time points. RESULTS: The mean elasticity values before, immediately after, and 24 hours after throwing were as follows: supraspinatus: 32.9, 53.4, 43.8 kPa; ISP: 22.7, 44.8, 43.7 kPa; middle trapezius: 45.1, 70.3, 59.9 kPa; LT: 32.8, 45.5, 46.5 kPa; rhomboideus: 29.1, 47.5, 38.8 kPa; and serratus anterior: 19.2, 36.9, 26.5 kPa, respectively. The mean elasticity values for all tested muscles were significantly higher immediately after throwing compared with before throwing (P ≤ .0086 for all), and elasticity values in the ISP and LT remained significantly higher 24 hours after throwing compared with before throwing (P ≤ .019 for both). CONCLUSION: The study results indicated that pitching significantly increased ISP and LT muscle elasticity even after 24 hours.

Isolated Musculocutaneous Nerve Injury in a Professional Baseball Player: A Case Report.

INTRODUCTION: Musculocutaneous nerve lesion in a throwing athlete is a rare condition. We report the case of a professional baseball pitcher with an isolated musculocutaneous nerve lesion that occurred during a pitching motion. CASE PRESENTATION: The patient had radiating pain in the upper arm and weakness of elbow flexion. Physical examination revealed flaccid paralysis of the biceps brachii muscle and paresthesia in the right lateral forearm. Musculocutaneous nerve injury was suspected. Because some signs of recovery were observed within a few days, the patient received non-operative management. Nerve conduction studies at 2 weeks after the injury showed low-amplitude compound muscle action potential of the right biceps brachii muscle by stimulation of the musculocutaneous nerve. Needle electromyography showed markedly reduced motor unit potential recruitment in the biceps brachii muscle. He was diagnosed as having isolated musculocutaneous nerve injury. At 2 months after the injury, the muscle contraction and strength of the biceps brachii muscle improved. At 7 months after the injury, muscle weakness was fully recovered. His pitching ability returned to that of a competitive player. CONCLUSION: Because the neuroparalysis was incomplete and began to recover within a few days, we considered the pathology of this injury to be incomplete axonotmesis, which was successfully treated conservatively.

Relationship between glenohumeral internal rotation deficit and shoulder conditions in professional baseball pitchers.

BACKGROUND: Previous studies have reported that glenohumeral internal rotation deficit (GIRD) may increase the risk of throwing-shoulder injuries. The purpose of this study was to analyze the conditions of the throwing shoulder in professional baseball pitchers with GIRD by comparing with those in pitchers without GIRD. METHODS: In total, 26 male professional baseball pitchers participated in this study. We evaluated passive range of motion (ROM) and isometric muscle strength at internal rotation (IR) and external rotation (ER) at 90° of abduction, as well as the muscle thickness of the supraspinatus (SSP) and infraspinatus (ISP) by ultrasound. The pitchers were divided into 2 groups: those who exhibited a loss of IR of ≥20° in the throwing shoulder (GIRD group) and those who did not (non-GIRD group). RESULTS: In the GIRD group, the total ROM deficit (throwing side - non-throwing side) (P < .001), the muscle thickness ratio (throwing to non-throwing) of the SSP and ISP (P = .017 and P = .014, respectively), and the muscle strength ratio (throwing to non-throwing) of ER (P = .028) were significantly lower than those in the non-GIRD group. In contrast, the muscle strength ratio (throwing to non-throwing) of IR was significantly higher in the GIRD group than in the non-GIRD group (P = .0064). CONCLUSIONS: We have shown that GIRD has significant correlations with several conditions, such as atrophy of the SSP and ISP, weakness of ER strength, enhancement of IR strength, limitation of total ROM, and throwing side, all of which could be important factors for throwing-shoulder injuries.

Muscle Strains in the Lower Extremity of Japanese Professional Baseball Players.

BACKGROUND: Predicting when athletes can return to play after muscle strains is not always simple because of difficulties in evaluating the severity of such injuries. PURPOSE/HYPOTHESIS: The purpose of this study was to evaluate the use of magnetic resonance imaging (MRI) to classify lower extremity muscle strains in Japanese professional baseball players. The hypothesis was that MRI grading can be used to diagnose the severity of muscle strains in the lower extremity and predict return to play in athletes. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: A total of 55 muscle strains occurred in the lower extremity of players on a professional baseball team between the 2006 and 2015 seasons; all players had undergone MRI examination. Age, player position, location of injury, cause of injury, and duration until return to play (in days) were extracted from the medical records. MRI scans were classified using the following system: grade 0, no abnormal findings; grade 1a, T2-weighted high intensity only between muscles; grade 1b, T2-weighted high intensity between muscles and in muscle belly; grade 2, injury of musculotendinous junction; and grade 3, rupture of tendon insertion. RESULTS: The sites of injuries were distributed as follows: hamstrings (n = 33), quadriceps (n = 6), hip adductors (n = 6), and calves (n = 10). MRI findings revealed 9 muscle strains (16%), 19 grade 1a (34%), 19 grade 1b (34%), and 8 grade 2 muscle strains (16%). The length of time until return to training and competition, respectively, was 15 and 26 days for grade 1a injuries, 19 and 36 days for grade 1b injuries, and 55 and 69 days for grade 2 injuries. CONCLUSION: Players with grade 1 injuries took 4 to 5 weeks to return to play, whereas players with grade 2 injuries took 10 weeks to return. MRI can be useful for diagnosing lower extremity muscle strains and predicting the time to return to play.

Bilateral Collateral Ligament Reconstruction for Chronic Elbow Dislocation.

We report the case of a 37-year-old male with autism spectrum disorder who was hospitalized for chronic elbow dislocation. He had suffered a posterior elbow dislocation 5 months ago. His elbow dislocation was easily reduced, but the reduction position could not be maintained. Severe varus and valgus instabilities were observed in his right elbow. He was diagnosed with chronic elbow dislocation due to bilateral collateral ligament dysfunction and was surgically treated. Bilateral ligament reconstruction using the bilateral palmaris longus (PL) tendon combined with a temporary ulnohumeral joint fixation was performed. Cast immobilization was applied for 6 weeks. One year after surgery, his range of motion was -15° in extension, 140° in flexion, 80° in pronation, and 90° in supination. He did not face any problems in daily activities.

Treatment of Locking of the Metacarpophalangeal Joint of the Thumb.

Locking of the thumb metacarpophalangeal joint is a relatively rare condition. We report successful treatment in 11 cases of locking of the thumb. Ten patients were diagnosed at an average of 3.2 days (range: 0-21 days) from the injury onset, whereas one patient was diagnosed at 4 months from the injury. Seven of 11 cases underwent successful manual reduction, whereas the other four cases required surgical treatment. Among the surgically treated cases, all cases had a sharp prominent of the radial condyle of the metacarpal head. Therefore, this case series showed 1 chronic case and 4 of 10 cases with a nonround shape of metacarpal heads requiring open reduction.

Osteochondritis Dissecans of the Humeral Trochlea Treated with Mosaic-type Osteochondral Autologous Transplantation.

INTRODUCTION: The majority of osteochondritis dissecans (OCD) of the elbow occurs in the humeral capitellum in adolescence while OCD in the humeral trochlea is relatively rare. We report a rare case of OCD in the humeral trochlea, which underwent mosaic-type osteochondral autologous transplantation. CASE REPORT: A 24-year-old man, who was a gymnastic athlete, complained of severe right elbow pain for 9 years. Image findings revealed a trochlear osteochondral defect with intra-articular loose body. Due to the large defect and duration of the disease, autologous osteochondral transplantation form femoral condyle was performed. Two years after surgery, the range of elbow motion was 0° in extension and 120° in flexion. He had no pain on his elbow. CONCLUSION: OCD in the humeral trochlea was treated with mosaic-type osteochondral autologous transplantation form femoral condyle. Despite the large trochlear defect, osteochondral transplantation yielded a satisfactory result and this treatment might be an option for treatment of trochlear OCD.

Assessment of posterior shoulder muscle stiffness related to posterior shoulder tightness in college baseball players using shear wave elastography.

BACKGROUND: Limitations of shoulder range of motion (ROM) have been reported to be at high risk for shoulder disorders in baseball players. In this study, we assessed posterior shoulder muscle stiffness using shear wave elastography in baseball players with and without posterior shoulder tightness. MATERIALS AND METHODS: In total, 21 college baseball players volunteered to participate in this study. Passive ROMs for shoulder abduction and horizontal adduction were measured using a goniometer. Subsequently, we divided all participants into 2 groups based on the differences between bilateral shoulder ROMs: STIFF+ and STIFF- groups. Thickness and elasticity of the posterior and inferior shoulder muscles were assessed using ultrasound. RESULTS: Shoulder abduction ROM on the throwing side was 114.5° ± 5.3° and 131.3° ± 5.7° in the STIFF+ and STIFF- groups, respectively, which was significantly different between the 2 groups (P = .023). Horizontal adduction ROM on the throwing side was 96.6° ± 4.9° and 110.9° ± 4.8° in the STIFF+ and STIFF- groups, respectively, which was also significantly different between the 2 groups (P = .014). The elasticity of infraspinatus and lower trapezius in the STIFF+ group was significantly greater than that in the STIFF- group (P = .018 and .033, respectively). DISCUSSION: In this study, we found that the elasticity of infraspinatus and lower trapezius in stiff shoulders was significantly greater than that in nonstiff shoulders, which indicated that the infraspinatus and lower trapezius could be the key muscles in posterior shoulder tightness.

Influence of advanced glycation end products on rotator cuff.

BACKGROUND: Most rotator cuff tears are the result of age-related degenerative changes, but the mechanisms underlying these changes have not been reported. Recently, advanced glycation end products (AGEs) have been regarded as an important factor in senescence. Therefore, we hypothesized that AGEs would have detrimental effects on rotator cuff-derived cells. In this study, we investigated the influence of AGEs on rotator cuff-derived cells in vitro and ex vivo. METHODS: Rotator cuff-derived cells were obtained from human supraspinatus tendons. The cells were cultured in the following media: (1) regular medium with 500 µg/mL AGEs (High-AGEs), (2) regular medium with 100 µg/mL AGEs (Low-AGEs), and (3) regular medium alone (Control). Cell viability, secretion of vascular endothelial growth factor, and the expressions of hypoxia-inducible factor-1α, reactive oxygen species, and apoptosis were assessed after cultivation. An ex vivo tissue culture with AGEs was also performed to measure the tensile strength. RESULTS: Cell viability in the High-AGEs group was significantly suppressed relative to that in the Controls. The amount of vascular endothelial growth factor secretion was significantly greater in the High- and Low-AGEs groups than in the Controls. Immunofluorescence stain demonstrated enhancement of hypoxia-inducible factor-1α and reactive oxygen species expressions and cell apoptosis in the High- and Low-AGEs groups relative to that in the Controls. In ex vivo mechanical testing, tensile strength was significantly higher in the Control group than in the AGEs groups. DISCUSSION: These results indicated that AGEs caused age-related degenerative rotator cuff changes. The reduction of AGEs might prevent rotator cuff senescence-related degeneration.

Molecular changes to tendons after collagenase-induced acute tendon injury in a senescence-accelerated mouse model.

BACKGROUND: Aging impairs tendon healing and is a potential risk factor for chronic tendinitis. During normal aging, tendons undergo structural and biomechanical degenerative changes, accompanied by a reduction in the number of tenocytes and changes to their properties. However, molecular changes in aged tendons under inflammatory conditions are not well understood. The present study analyzed the molecular changes in collagenase induced acute tendon injury using a senescence-accelerated mouse (SAM) model. METHODS: SAMP6 mice were used as an aging animal model and SAMR1 mice were used as a control to represent a senescence-resistant inbred strain. All the mice used in the study were 40 weeks old. Collagenase I from Clostridium histolyticum (20 µL) was injected percutaneously to the tendon-bone junction of the Achilles tendon. Two weeks after treatment, the Achilles tendons were harvested and stained using Picrosirius Red to determine collagen expression. Real-time PCR was performed to analyze gene expression of IL-6, tenomodulin, type I and type II collagen, MMP-9, TIMP-1, and TIMP-2. RESULTS: Collagenase injection resulted in significantly higher gene expression of IL-6 but significantly lower tenomodulin expression compared with the control in SAMP6 and SAMR1 mice. In SAMP6 mice, gene expression of type III collagen and MMP-9 was significantly higher in the collagenase-injected group compared with the control group. SAMP6 mice also showed lower expression of type I collagen, TIMP-1, and TIMP-2 in the collagenase-injected group compared with the control group. Picrosirius Red staining showed the highest expression of type III collagen in the collagenase-injected SAMP6 group compared with the other groups. CONCLUSIONS: The collagenase-injected SAMP6 group showed higher expression of IL-6, MMP-9, and type III collagen and lower expression of type I collagen, TIMP-1, and TIMP-2, which are known to suppress metalloproteinases. The results indicate that aging may lead to dysfunction of the tendon healing process after acute tendon injury.

Treatment of Chronic Bony Mallet Fingers by Dorsal Extension Block Pinning with Percutaneous Curettage.

Dorsal extension block pinning is a commonly performed surgical technique for acute bony mallet fingers. However, the treatment of chronic bony mallet finger remains controversial. We investigated the use of dorsal extension block pinning with percutaneous curettage for chronic bony mallet fingers. Seven patients with chronic bony mallet fingers were treated by dorsal extension block pinning with percutaneous curettage. The average age was 17 (range, 12-23) years, and the average time from injury to surgery was 20 (range, 7-49) weeks. Bone union was achieved in all patients. None of the patients experienced pain after bone union. The average loss of distal interphalangeal joint extension was 6 (range, 5-20) degrees, and the average flexion was 59 (range, 40-80) degrees. The Crawford functional score was excellent in three patients, good in two, and fair in two. Dorsal extension block pinning with percutaneous curettage could be a useful treatment for chronic bony mallet fingers.

Rotator cuff tear healing process with graft augmentation of fascia lata in a rabbit model.

BACKGROUND: Fascia lata augmentation of massive rotator cuff tears has shown good clinical results. However, its biological effect during the early healing process is not clearly understood. The purpose of the study was to evaluate the biological efficacy of fascia lata augmentation during the early healing process of rotator cuff tears using a rabbit rotator cuff defect model. METHODS: The infraspinatus tendon was resected from the greater tuberosity of a rabbit to create a rotator cuff tear. The tendon edge was directly sutured to the humeral head. The rotator cuff repaired site was augmented with a fascia lata autograft (augmentation group, group A). The rotator cuff defect in the contralateral shoulder was repaired without augmentation (reattachment group, group R). A group with intact rotator cuff was set as the control group. Histological examinations and mechanical analysis were conducted 4 and 8 weeks postoperatively. RESULTS: In the HE staining, the tendon maturing score of group A was higher than that of group R at 4 weeks postoperatively. In the safranin O staining, proteoglycan staining at the repaired enthesis in group A at 4 weeks postoperatively was stronger than that in group R. Picrosirius red staining showed that type III and type I collagen in group A was more strongly expressed than that in group R at 4 weeks postoperatively. The ultimate failure load of the infraspinatus tendon-humeral head complex in group A was statistically higher than that in group R at 4 weeks postoperatively. The ultimate failure load of group A was similar to that of the control group. CONCLUSION: The biological and mechanical contribution of fascia lata augmentation for massive rotator cuff tears was analyzed in this study. Type III collagen was reported to be expressed during the tendon healing process. Although the biological action similar to natural ligament healing occurred around the fascia lata grafts, type III collagen was gradually replaced by type I collagen as the tissue matured. Our results suggest that fascia lata augmentation could stimulate biological healing and provide initial fixation strength of the repaired rotator cuff.

Association of advanced glycation end products in Dupuytren disease.

BACKGROUND: Advanced glycation end products are associated with aging, hyperglycemia, and oxidative stress. Accumulation of advanced glycation end products can cause various pathological conditions; however, the association of Dupuytren's disease with advanced glycation end products has not been demonstrated yet. The aim of this study is to investigate the association of Dupuytren's disease with advanced glycation end products. METHODS: Normal palmar fascia from five patients with carpal tunnel syndrome (control group) and Dupuytren's cords from five patients (Dupuytren's disease group) were harvested. The tissues were stained using an anti-advanced glycation end products antibody, anti-receptor for advanced glycation end products antibody, and an anti-reactive oxygen species modulator 1 antibody. The expression of nicotinamide adenine dinucleotide phosphate oxidase-1 and nicotinamide adenine dinucleotide phosphate oxidase-4 genes was also assessed using real-time PCR. For in vitro analysis, the cells harvested from the control and Dupuytren's disease groups were used. After 3 days of exposure to four types of media (control group, control + advanced glycation end products group, Dupuytren's disease group, Dupuytren's disease + advanced glycation end products group), superoxide detection reagent was detected using a total reactive oxygen species/superoxide detection kit. RESULTS: Immunostaining of the palmar fasciae of the Dupuytren's disease group showed higher expressions of advanced glycation end products and receptor for advanced glycation end products than that in the control group. The expression of nicotinamide adenine dinucleotide phosphate oxidase oxidase-1 and nicotinamide adenine dinucleotide phosphate oxidase-4 as well as reactive oxygen species modulator 1, an oxidatively damaged protein, was also higher in the Dupuytren's disease group than in the control group. In an in vitro cell culture, the addition of advanced glycation end products to the Dupuytren's disease-derived cells produced more superoxide free radicals. CONCLUSIONS: These data suggest that the advanced glycation end products receptor for advanced glycation end products interaction produced free radicals via nicotinamide adenine dinucleotide phosphate oxidase activation in Dupuytren's disease patients. Further studies are required to confirm these results.

Transcutaneous carbon dioxide application with hydrogel prevents muscle atrophy in a rat sciatic nerve crush model.

The acceleration of nerve regeneration remains a clinical challenge. We previously demonstrated that transcutaneous CO2 application using a novel hydrogel increases the oxygen concentration in local tissue via an "artificial Bohr effect" with the potential to prevent muscle atrophy. In this study, we investigated the effect of transcutaneous CO2 administration on limb function after peripheral nerve injury in a rat sciatic nerve injury model. In total, 73 Sprague-Dawley rats were divided into a sham group, a control group (crush injury to sciatic nerve and no treatment) or a CO2 group (crush injury with transcutaneous CO2 application). CO2 was administered percutaneously for 20 min five times per week. Scores for the sciatic function index and pinprick test were significantly higher in the CO2 group than control group. The muscle wet weight ratios of the tibialis anterior and soleus muscles were higher in the CO2 group than control group. Electrophysiological examination showed that the CO2 group had higher compound motor action potential amplitudes and shorter distal motor latency than the control group. Histological examination of the soleus muscle sections at postoperative week 2 showed shorter fiber diameter in the control group than in the CO2 group. The mRNA expression of Atrogin-1 and MuRF-1 was lower, mRNA expression of VEGF and myogenin and MyoD was higher in CO2 group at postoperative week 2 compared to the control group. CLINICAL SIGNIFICANCE: Transcutaneous CO2 application has the therapeutic potential to accelerate the recovery of muscle atrophy in peripheral nerve injury. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1653-1658, 2018.

Olecranon Apophyseal Nonunion in Adolescent Judo Players: A Report of Two Cases.

Olecranon apophyseal nonunion is an elbow injury from overuse that affects adolescent athletes such as baseball pitchers who participate in overhead throwing sports. However, such injury is rare in collision sports. Here, we report two patients with this condition who are Judo athletes. The purpose of this report was to describe three elbows with olecranon apophyseal nonunion in two adolescent patients participating in Judo. This is a case series; the level of evidence is 4. Two 15-year-old patients were evaluated. One suffered from unilateral and the other from bilateral chronic posterior elbow pain. They were diagnosed with olecranon apophyseal nonunion, which was treated using internal fixation and bone grafting. Radiographic evidence of the apophyseal union was observed four months postsurgery. Two elbows were treated with tension band wiring, then they underwent hardware removal six months postsurgery. Both patients returned to their previous levels of activities six months postsurgery. Internal fixation using autologous bone grafting was a useful treatment for these Judo athletes with olecranon apophyseal nonunion.

Case Series of Comminuted Olecranon Fracture Treated by Plate Fixation; Do We Have to Remove the Plate?

Comminuted olecranon fracture requires surgical intervention. Plate fixation has been performed on the majority of cases. We reviewed the cases of comminuted olecranon fracture in young and middle age treated by plate osteosynthesis and analyzed the functional outcome, complications and ratio and timing of hardware removal. Fifteen cases of comminuted olecranon fractures treated by plate fixation were reviewed. Bone union was achieved in all cases, the average range of motion at the final follow up was -11° in extension, 133° in flexion, 89° in pronation and 88° in supination. Hardware removal performed in 12 cases in average 8.3 months postoperatively, in 2 cases elbow joint contracture release was performed during the hardware removal. In the co-payment (+) group, 4 cases (67%) removed the plate at average six months postoperatively. On the other hand, no co-payment group (workman's compensation insurance or automobile liability insurance) underwent hardware removal surgery in 8 cases (89%) at 9.6 months postoperatively. There was no statistical difference between the timing or prevalence of hardware removal between the groups. The present study showed high removal rate of hardware despite the excellent clinical result. The surgeons should be aware that plate fixation of the olecranon fracture requires the removal of a plate in the majority of cases.

Effect of platelet-rich plasma on degeneration change of rotator cuff muscles: In vitro and in vivo evaluations.

Atrophy with fatty degeneration is often seen in rotator cuff muscles with torn tendons. PRP has been reported to enhance tissue repair processes after tendon ruptures. However, the effect of PRP on atrophy and fatty degeneration of the muscle is not yet known. The aim of this study is to examine the effect of PRP on degeneration change of rotator cuff muscles in vitro and in vivo. A murine myogenic cell line and a rat rotator cuff tear model were used in this study and PRP was administrated into subacromial space which is widely used in clinical practice. In in vitro study, administration of PRP to C2C12 cells stimulated cell proliferation while inhibited both myogenic and adipogenic differentiation. In in vivo study, administration of PRP suppressed Oil Red-O positive lipid droplet formation. The expression of adipogenic genes was also decreased by PRP administration. In conclusion, PRP promoted proliferation of myoblast cells, while inhibiting adipogenic differentiation of myoblast cells and suppressing fatty degeneration change in rat torn rotator cuff muscles. Further investigations are needed to determine the clinical applicability of the PRP. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1806-1815, 2017.

Rotator cuff repair using cell sheets derived from human rotator cuff in a rat model.

To achieve biological regeneration of tendon-bone junctions, cell sheets of human rotator-cuff derived cells were used in a rat rotator cuff injury model. Human rotator-cuff derived cells were isolated, and cell sheets were made using temperature-responsive culture plates. Infraspinatus tendons in immunodeficient rats were resected bilaterally at the enthesis. In right shoulders, infraspinatus tendons were repaired by the transosseous method and covered with the cell sheet (sheet group), whereas the left infraspinatus tendons were repaired in the same way without the cell sheet (control group). Histological examinations (safranin-O and fast green staining, isolectin B4, type II collagen, and human-specific CD31) and mRNA expression (vascular endothelial growth factor; VEGF, type II collagen; Col2, and tenomodulin; TeM) were analyzed 4 weeks after surgery. Biomechanical tests were performed at 8 weeks. In the sheet group, proteoglycan at the enthesis with more type II collagen and isolectin B4 positive cells were seen compared with in the control group. Human specific CD31-positive cells were detected only in the sheet group. VEGF and Col2 gene expressions were higher and TeM gene expression was lower in the sheet group than in the control group. In mechanical testing, the sheet group showed a significantly higher ultimate failure load than the control group at 8 weeks. Our results indicated that the rotator-cuff derived cell sheet could promote cartilage regeneration and angiogenesis at the enthesis, with superior mechanical strength compared with the control. Treatment for rotator cuff injury using cell sheets could be a promising strategy for enthesis of tendon tissue engineering. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:289-296, 2017.