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.

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.

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.

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.

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.

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.

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.

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.

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.

Recurrence of Enchondroma in a Middle Finger after Curettage and Back-filling with Calcium Phosphate Bone Cement: a Case Report.

We report a case of recurrence of enchondroma in a middle finger after curettage and back-filling with calcium phosphate bone cement (CPC). The radiograph showed a lytic lesion around the CPC filling which showed no signs of absorption after 12 years. The tumor was curated easily, however, a steel bar was needed to remove the CPC mass in a carefully manner not to break the cortex. CPC has an advantage of immediate biomechanical stability, on the other hand, a disadvantage of being unabsorbed inside of bone. Although enchondroma has a low recurrence rate after surgery generally, in consideration of recurrence, we recommend the use of absorbable materials when a use of artificial bone substitute to fill the defect is planned.

Ultrasound measurement of median nerve cross-sectional area at the inlet and outlet of carpal tunnel after carpal tunnel release compared to electrodiagnostic findings.

INTRODUCTION: Ultrasound measurement of the cross-sectional area (CSA) of the median nerve can give information about regeneration of the nerve after carpal tunnel release (CTR), but the changes at selected follow-up points up to 1 year compared to electrodiagnostic findings are not known. We postoperatively measured the CSA of the median nerve with ultrasound and compared the measurements with electrophysiological findings over 12 months after open CTR. MATERIALS AND METHODS: In 21 hands that underwent open CTR, the CSA of the median nerve was measured at the inlet (proximal CSA) and outlet (distal CSA) of the carpal tunnel at 3- 6- and 12-month follow-up. The respective ratios [(CSA postoperatively/CSA preoperatively) × 100] were calculated and correlated with distal motor latency (DML) and sensory nerve conduction velocity (SCV). RESULTS: The proximal CSA ratio was 88.9, 84.5, and 78.4 % at 3-, 6-, and 12-month follow-up, respectively. Each value was significantly lower than that before surgery. The distal CSA ratio was 104.3, 99.1, and 91.8 % at 3-, 6-, and 12-month follow-up, respectively. The values were not significantly different compared to preoperative values. CONCLUSIONS: The proximal CSA of the median nerve decreased continuously over the time after CTR while the distal CSA increased up to 3 months before it decreased continuously, too.

Characterization of progenitor cells derived from torn human rotator cuff tendons by gene expression patterns of chondrogenesis, osteogenesis, and adipogenesis.

BACKGROUND: It is important to regenerate the tendon-to-bone interface after rotator cuff repair to prevent re-tears. The cells from torn human rotator cuff were targeted, and their capacity for multilineage differentiation was investigated. METHODS: The edges of the rotator cuff were harvested during arthroscopic rotator cuff repair from nine patients, minced into pieces, and cultured on dishes. Adherent cells were cultured, phenotypically characterized. Then expandability, differentiation potential and gene expression were analyzed. RESULTS: Flow cytometry revealed that the mesenchymal stem cells (MSC)-related markers CD29, CD44, CD105, and CD166 were positive. However, CD14, CD34, and CD45 were negative. On RT-PCR analyses, the cells showed osteogenic, adipogenic, and chondrogenic potential after 3 weeks of culture under the respective differentiation conditions. In addition, SOX9, type II collagen, and type X collagen expression patterns during chondrogenesis were similar to those of endochondral ossification at the enthesis. CONCLUSIONS: The cells derived from torn human rotator cuff are multipotent mesenchymal stem cells with the ability to undergo multilineage differentiation, suggesting that MSCs form this tissue could be regenerative capacity for potential self-repair.

Carpal Tunnel Syndrome Caused by Tumoral Calcinosis.

We present a case of carpal tunnel syndrome caused by systemic tumoral calcinosis. A 54-year-old woman experienced hand numbness that persisted for nine months. She had no family history or medical problem. A plain radiograph of her right wrist showed a calcified mass on the volar side of the wrist joint. The patient also experienced pain in her contralateral wrist joint and both right and left shoulders, which had calcification on radiography around the joint. Her condition was diagnosed as carpal tunnel syndrome caused by systemic tumoral calcinosis and a resection biopsy was performed. Histopathological analysis of the biopsied specimen showed basophile deposition inside the fibrous connective tissue. At 14 months after the treatment, she no longer had pain or numbness in her fingers and there was no recurrence of the mass. This patient's condition is considered as a case of nonfamilial, systemic primary tumoral calcinosis. Since incomplete resection leads to a recurrence of the lesion, a follow-up radiography examination is needed to monitor symptom recurrence.

Application of Pain Quantitative Analysis Device for Assessment of Postoperative Pain after Arthroscopic Rotator Cuff Repair.

PURPOSE: The PainVision™ system was recently developed for quantitative pain assessment. Here, we used this system to evaluate the effect of plexus brachialis block on postoperative pain after arthroscopic rotator cuff repair. METHODS: Fifty-five patients who underwent arthroscopic rotator cuff repair were included in this study. First 26 cases received no plexus brachialis block (control group), and the next 29 cases received the plexus brachialis block before surgery (block group). Patients completed the visual analog scale at 4, 8, 16, and 24 hours after surgery, and the intensity of postoperative pain was assessed with PainVision™ at 16 hours. The postoperative use of non-steroidal anti-inflammatory agents was also recorded. RESULTS: The pain intensity at 16 hours after surgery assessed by PainVision™ was significantly lower in the block group than in the control group (block, 252.0 ± 47.8, control, 489.0 ± 89.1, P < 0.05). However, there were no differences in the VAS values at 16 hours between the 2 groups (block, 4.3 ± 0.6, control, 5.7 ± 0.4, P = N.S.). The pain intensity and VAS at 16 hours after surgery were highly correlated (r = 0.59, P = 0.006 in the block group and r = 0.62, P = 0.003 in the control group). The effect size of the assessment by PainVision™ was bigger than that of VAS (r=0.31 in VAS and 0.51 in Pain vision). CONCLUSION: The PainVision™ system could be useful to evaluate postoperative pain because it enables the quantification and comparison of pain intensity independent of individual pain thresholds.

Electrophysiological assessment of carpal tunnel syndrome in elderly patients: one-year follow-up study.

PURPOSE: To objectively assess elderly patients with carpal tunnel syndrome to characterize their preoperative severity and prognosis after carpal tunnel release using a electrophysiological severity scale. METHODS: Electrophysiologic assessment was performed preoperatively and 1 year postoperatively following carpal tunnel release in 112 hands in patients over 70 years of age prospectively by the use of the following electrophysiological severity scale: stage 1, normal distal motor latency (DML) and normal sensory conduction velocity (SCV); stage 2, DML ≥ 4.5 milliseconds and normal SCV; stage 3, DML ≥ 4.5 milliseconds and SCV < 40.0 m/s; stage 4, DML ≥ 4.5 milliseconds and non-measurable SCV; stage 5; non-measurable DML and non-measurable SCV. Additionally, the outcomes of clinical symptoms of pain, nocturnal symptoms, numbness, loss of 2-point discrimination in the median nerve territory, and thenar atrophy were assessed. RESULTS: The mean age of patients was 77 years at the time of the operation. Preoperatively, the most common severity was stage 5 (70 of 112 hands, 63%), and clustering stage 4 and 5 together as severe resulted in 103 hands (92%). One year postoperatively, 97 hands (87%) demonstrated at least one stage improvement, and the numbers of mild (stage 1 or 2) increased from 3 (3%) to 45 hands (40%). Parallel with the electrophysiological improvement, pain and nocturnal symptoms resolved in 17 of 17 hands and 11 of 11 hands, respectively, in whom they were present preoperatively. Numbness, loss of 2-point discrimination, and thenar atrophy demonstrated the improvement in 96 of 112 (86%) hands, in 58 of 112 (52%) hands, and in 80 of 96 (83%) hands. CONCLUSIONS: We observed electrophysiologic improvement in 86% of elderly patients following carpal tunnel release. Electrophysiologic outcomes correlated with improvement in clinical variables. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Regeneration of rotator cuff tear using electrospun poly(d,l-Lactide-Co-Glycolide) scaffolds in a rabbit model.

PURPOSE: The purpose of this study was to evaluate an application of poly(d,l-lactide-co-glycolide) (PLG) scaffold created by electrospinning in a rabbit rotator cuff defect model. METHODS: Forty-two Japanese white rabbits were used in this study. Defects of the infraspinatus tendon were created, and the PLG scaffolds were implanted. Contralateral infraspinatus tendons were reattached without creating defects. Histologic analyses were performed 4, 8, and 16 weeks after the operation, and mechanical evaluations were performed 0, 4, 8, and 16 weeks after the operation. RESULTS: Scaffold fibers remained without dissolution and spindle-shaped cells were observed inside of the scaffold at 4 weeks postoperatively. At 8 weeks, the PLG scaffold had dissolved and bone formation was observed at the scaffold-bone interface. At 16 weeks, the scaffold-bone interface matured and expression of type II collagen was observed. A statistical difference in ultimate failure load was not seen between the scaffold group and reattachment group or normal tendon after 8 weeks postoperatively. The stiffness in the scaffold group was not significantly different from that in the reattachment group at each time point. However, it was significantly weaker than normal tendon at each time point. CONCLUSIONS: Transplantation of cell-free PLG scaffold showed cell migration and type II collagen and proteoglycan expression at the scaffold-bone junction by 16 weeks postoperatively with a sufficient ultimate failure load in a rabbit rotator cuff defect model. CLINICAL RELEVANCE: The PLG scaffold could be applied to bridge rotator cuff defects. The results showed that bridging with scaffold can be equivalent to reattachment.

Localization of vascular endothelial growth factor during the early stages of osteochondral regeneration using a bioabsorbable synthetic polymer scaffold.

Vascular endothelial growth factor (VEGF) plays a critical role in chondrogenic differentiation in the growth plate of the epiphysis. This function is necessary for chondrocyte survival in cartilage development. We investigated the localization of VEGF in the osteochondral regeneration process using a bioabsorbable polymer scaffold. Osteochondral defects (5 mm in diameter and 5 mm in depth) were made on the femoral condyle of forty-eight skeletally mature female Japanese white rabbits. In total, twenty-four defects were filled with poly(DL-lactide-co-glycolide) scaffolds and the others were left untreated. The regeneration process was investigated macroscopically, histologically, immunohistochemically, and by gene expression analysis. In the early stages of osteochondral regeneration, bone ingrowth was observed in the deep zone of the scaffold with continuous VEGF expression; cartilage regeneration was observed in the superficial zone of the scaffold with decreased VEGF expression. In contrast, when the defect was left untreated, VEGF localization was observed throughout the entire defect area, and cartilage regeneration at the articular surface was delayed. We conclude that decrease in localization of VEGF at the articular surface in the postoperative early stage is closely related to the progression of cartilage regeneration in osteochondral defects.