Kartogenin Enhances Collagen Organization and Mechanical Strength of the Repaired Enthesis in a Murine Model of Rotator Cuff Repair.

PURPOSE: To investigate the use of kartogenin (KGN) in augmenting healing of the repaired enthesis after rotator cuff repair in a murine model. METHODS: Seventy-two C57BL/6 wild-type mice underwent unilateral detachment and transosseous repair of the supraspinatus tendon augmented with either fibrin sealant (control group; n = 36) or fibrin sealant containing 100 µmol/L of KGN (experimental group; n = 36) applied at the repair site. Postoperatively, mice were allowed free cage activity without immobilization. Mice were humanely killed at 2 and 4 weeks postoperatively. Repair site integrity was evaluated histologically through fibrocartilage formation and collagen fiber organization and biomechanically through load-to-failure testing of the supraspinatus tendon-bone construct. RESULTS: At 2 weeks, no differences were noted in percent area of fibrocartilage, collagen organization, or ultimate strength between groups. At 4 weeks, superior collagen fiber organization (based on collagen birefringence [17.3 ± 2.0 vs 7.0 ± 6.5 integrated density/µm2; P < .01]) and higher ultimate failure loads (3.5 ± 0.6 N vs 2.3 ± 1.1 N; P = .04) were seen in the KGN group. The percent area of fibrocartilage (13.2 ± 8.4% vs 4.4 ± 5.4%; P = .04) was higher in the control group compared with the KGN group. CONCLUSIONS: Rotator cuff repair augmentation with KGN improved the collagen fiber organization and biomechanical strength of the tendon-bone interface at 4 weeks in a murine model. CLINICAL RELEVANCE: These findings have implications for improving the structural integrity of the repaired enthesis and potentially reducing the retear rate after rotator cuff repair, which can ultimately lead to improvements in clinical outcomes.

Biomechanical, Histologic, and Molecular Evaluation of Tendon Healing in a New Murine Model of Rotator Cuff Repair.

PURPOSE: To develop a clinically relevant, robust murine model of rotator cuff tendon repair to examine cellular and molecular mechanisms of healing. METHODS: Sixty C57BL/6 male mice underwent rotator cuff transection and repair using microsurgical techniques. A modified Kessler suturing technique was used prior to tendon detachment. Sutures were passed through 2 intersecting bone tunnels that were made at the tendon attachment site. Mice were sacrificed at 2 and 4 weeks with subsequent biomechanical, histologic, micro-CT, and gene expression evaluations. RESULTS: Failure forces in the 2- and 4-week groups were 36% and 75% of the intact tendon, respectively. Histologic evaluation revealed complete reattachment of the tendon with no observable gap. Healing occurred by formation of fibrovascular tissue at the tendon-bone interface, similar to larger animal models. Molecular analysis revealed gene expression consistent with gradual healing of the reattached tendon over a period of 4 weeks. Comparisons were made using 1-way analysis of variance. CONCLUSIONS: This model is distinguished by use of microsurgical suturing techniques, which provides a robust, reproducible, and economic animal model to study various aspects of rotator cuff pathology. CLINICAL RELEVANCE: Improvement of clinical outcomes of rotator cuff pathology requires in-depth understanding of the underlying cellular and molecular mechanisms of healing. This study presents a robust murine model of supraspinatus repair to serve as a standard research tool for basic and translational investigations into signaling pathways, gene expression, and the effect of biologic augmentation approaches.

Expression of alarmins in a murine rotator cuff tendinopathy model.

The aim of this study was to investigate the presence of alarmins in a novel murine rotator cuff tendinopathy model. Alarmins have been described as essential early activators of an immune response to tissue damage. Subacromial impingement was induced in both shoulders of 37 male C57Bl/6 mice by placement of a small metal clip in the subacromial space. Animals were allocated to different time points up to 6 weeks. The morphology and cellularity of the supraspinatus tendon were evaluated by hematoxylin-eosin staining, alcian blue, and picrosirius red. The expression and localization of alarmins interleukin-33 (IL-33), c (HMGB1), hypoxia-inducible factor-1 subunit α (HIF1α), and S100A9 were evaluated by immunohistochemical staining and quantitative polymerase chain reaction. The percentage of positively stained cells with HMGB1 and IL-33 was significantly increased in the impingement group at 1w, 4w, and 6w. HIF1α staining was higher in the impingement group at 1w and 6w compared with the control group. HMGB1 gene expression was higher in the 5d impingement group and 6w impingement group. The gene expression of HIF1α was upregulated at all-time points in the impingement group (5d, 2w, 4w, and 6w). The expression of the S100A9 gene was also upregulated in the 5d impingement group. This is the first study to demonstrate the involvement of alarmins in the early phase of tendinopathy using a reproducible animal model. Alarmins may play an important role in the early phases of the development of tendinopathy They may represent potential therapeutic targets for treatment of tendinopathy.

Duration of postoperative immobilization affects MMP activity at the healing graft-bone interface: Evaluation in a mouse ACL reconstruction model.

Excessive MMP activity may impair tendon-to-bone healing. However, little is known about the effect of joint motion on MMP activity after ACL reconstruction. The aim of this study was to determine the effect of different durations of knee immobilization on MMP activity in a mouse ACL reconstruction model using a fluorescent MMP probe which detects MMP 2, 3, 9, and 13 and near-infra red in vivo imaging. Sixty C57BL male mice underwent ACL reconstruction. Post-operatively, the animals were treated with free cage activity (Group 1), or with the use of an external fixator to restrict knee motion and weight bearing for 5 days (Group 2), 14 days (Group 3), and 28 days (Group 4). At days 3, 7, 16, 23, and 30, five mice underwent IVIS imaging. At days 3, 7, 16, and 30, histological analysis was also performed. Probe signal intensity in the whole limb peaked at day 7, followed by a decrease at day 16, and maintenance up to day 30. There was no significant difference among groups at any time point based on IVIS, but histologic localization of MMP probe signal showed significantly less activity in Group 2 and Group 3 compared to Group 4 in the bone tunnel at day 30. We demonstrated that short-term immobilization led to less MMP activity around the bone tunnel compared with prolonged immobilization. A short period of immobilization after ACL reconstruction might enhance graft-bone interface healing by mitigating excess MMP expression. These findings have implications for post-operative rehabilitation protocols following ACL reconstruction. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:325-334, 2019.

Postoperative Tendon Loading With Treadmill Running Delays Tendon-to-Bone Healing: Immunohistochemical Evaluation in a Murine Rotator Cuff Repair Model.

Mechanical stress has an important effect on tendon-to-bone healing. The purpose of the present study was to compare tendon-to-bone healing in animals exposed to either tendon unloading (botulinum toxin injection) or excessive loading (treadmill running) in a murine rotator cuff repair model. Forty-eight C57BL/6 mice underwent unilateral supraspinatus tendon detachment and repair. Mice in the unloaded group were injected with botulinum toxin to the supraspinatus muscle. The contralateral shoulder of the unloaded group was used as a control. Mice were euthanized at 1, 2, and 4 weeks after surgery and evaluated with hematoxylin-eosin and immunohistochemical (IHC) staining for Ihh, Gli1, Wnt3a, and ß-catenin. The positive staining area on IHC and the Modified Tendon Maturing Score were measured. The score of the unloaded group was significantly higher (better healing) than that of the treadmill group at 4 weeks. Ihh and the glioma-associated oncogene homolog 1 (Gli1) positive area in the unloaded group were significantly higher than those of the control group at 1 week. The peak time-points of the Ihh and Gli1 positive area was 1 week for the unloaded group and 2 weeks for the treadmill group. The Wnt3a positive area in the unloaded group was significantly higher than that of the control group at 2 weeks. The ß-catenin positive area in the unloaded group was significantly higher than that of the treadmill group and the control group at 1 week. Our data indicated that the unloaded group has superior tendon maturation compared to the treadmill running group. Excessive tendon loading may delay the tendon healing process by affecting the activity of Ihh and Wnt/ß-Catenin pathways. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1628-1637, 2019.

Comparison of Bone Tunnel and Cortical Surface Tendon-to-Bone Healing in a Rabbit Model of Biceps Tenodesis.

BACKGROUND: Many orthopaedic surgical procedures involve reattachment of a single tendon to bone. Whether tendon-to-bone healing is better facilitated by tendon fixation within a bone tunnel or on a cortical surface is unknown. The purpose of this study was to evaluate tendon-healing within a bone tunnel compared with that on the cortical surface in a rabbit model of biceps tenodesis. METHODS: Thirty-two rabbits (24 weeks of age) underwent unilateral proximal biceps tenodesis with tendon fixation within a bone tunnel (BT group) or on the cortical surface (SA [surface attachment] group). Postoperatively, rabbits were allowed free-cage activity without immobilization. All rabbits were killed 8 weeks after surgery. Healing was assessed by biomechanical testing, microcomputed tomography (micro-CT), and histomorphometric analysis. RESULTS: Biomechanical testing demonstrated no significant difference between the groups in mean failure loads (BT: 56.8 ± 28.8 N, SA: 55.8 ± 14.9 N; p = 0.92) or stiffness (BT: 26.3 ± 16.6 N/mm, SA: 32.3 ± 9.6 N/mm; p = 0.34). Micro-CT analysis demonstrated no significant difference between the groups in mean volume of newly formed bone (BT: 69.3 ± 13.9 mm, SA: 65.5 ± 21.9 mm; p = 0.70) or tissue mineral density of newly formed bone (BT: 721.4 ± 10.9 mg/cm, SA: 698.6 ± 26.2 mg/cm; p = 0.07). On average, newly formed bone within the tunnel represented only 5% of the total new bone formed in the BT specimens. Histological analysis demonstrated tendon-bone interdigitation and early fibrocartilaginous zone formation on the outer cortical surface in both groups. In contrast, minimal tendon-bone bonding was observed within the tunnel in the BT specimens. CONCLUSIONS: Tendon fixation in a bone tunnel and on the cortical surface resulted in similar healing profiles. For tendons placed within a bone tunnel, intratunnel healing was minimal compared with the healing outside the tunnel on the cortical surface. CLINICAL RELEVANCE: The creation of large bone tunnels, which can lead to stress risers and increase the risk of fracture, may not be necessary for biceps tenodesis procedures.

Evaluating the role of subacromial impingement in rotator cuff tendinopathy: Development and analysis of a novel murine model.

Subacromial impingement of the rotator cuff is understood as a contributing factor in the development of rotator cuff tendinopathy. However, changes that occur in the impinged tendon are poorly understood and warrant further study. To enable further study of rotator cuff tendinopathy, we performed a controlled laboratory study to determine feasibility and baseline characteristics of a new murine model for subacromial impingement. This model involves surgically inserting a microvascular clip into the subacromial space in adult C57Bl/6 mice. Along with a sham surgery arm, 90 study animals were distributed among time point groups for sacrifice up to 6 weeks. All animals underwent bilateral surgery (total N = 180). Biomechanical, histologic, and molecular analyses were performed to identify and quantify the progression of changes in the supraspinatus tendon. Decreases in failure force and stiffness were found in impinged tendon specimens compared to sham and no-surgery controls at all study time points. Semi-quantitative scoring of histologic specimens demonstrated significant, persistent tendinopathic changes over 6 weeks. Quantitative real-time polymerase chain reaction analysis of impinged tendon specimens demonstrated persistently increased expression of genes related to matrix remodeling, inflammation, and tendon development. Overall, this novel murine subacromial impingement model creates changes consistent with acute tendonitis, which may mimic the early stages of rotator cuff tendinopathy. A robust, simple, and reproducible animal model of rotator cuff tendinopathy is a valuable research tool to allow further studies of cellular and molecular mechanisms and evaluation of therapeutic interventions in rotator cuff tendinopathy. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2780-2788, 2018.

Gender influence on hospital mortality after coronary artery bypass surgery.

There is still controversy about the influence of gender on hospital mortality after coronary artery bypass grafting. We analyzed various risk factors in 1,258 patients undergoing isolated on-pump coronary artery bypass, of whom 19 (1.5%) died in hospital. There were 937 men (74.5%) and 321 women (25.5%). Compared to men, women were older with a higher mean body mass index, twice as many were hypertensive and diabetic, and they had higher serum cholesterol and triglycerides. Men smoked more, had lower ejection fractions, more myocardial infarctions and poorer functional status. Female sex, congestive heart failure, low ejection fraction, diabetes, previous percutaneous interventions and chronic lung disease were more prevalent among the patients who died. These factors were used to form a logistic regression model in which sex did not have an independent influence on hospital mortality. The difference between men and women can be explained by differences in risk factor profile.

Evaluation of the outcome of complete sinus excision with reconstruction of the umbilicus in patients with umbilical pilonidal sinus.

Umbilical pilonidal sinus is a cause of umbilical discharge. In this study, the outcome of complete excision of the umbilical sinus with umbilical reconstruction is considered. Adult patients with umbilical pilonidal sinus who had not undergone any previous surgeries were operated on using a technique that involves complete excision of the sinus after eversion of the umbilicus followed by reconstruction of the umbilicus. Patients were then followed; and wound complications, recurrence, and patient satisfaction were evaluated at postoperative visits. A total of 45 patients underwent the operation; 39 (86.5%) were male, and 6 (13.5%) were female. The mean age was 22.6 years (18-27 years). Six male patients had synchronous sacrococcygeal pilonidal disease. The mean follow-up period was 34 months (3-62 months). Only four patients had wound drainage after operation, and all required drainage of the wound. No recurrence was observed during the follow-up period, and all patients were satisfied with the appearance of their umbilicus. The technique of complete sinus excision and umbilical reconstruction is an effective and acceptable method for treating umbilical pilonidal sinus and may be recommended for primary treatment of this disease.

Colorectal carcinoma: a retrospective, descriptive study of age, gender, subsite, stage, and differentiation in Iran from 1995 to 2001 as observed in Tehran University.

PURPOSE: Colorectal carcinoma is one of the most common cancers in the world as well as in Iran. There are differences in subsite of the carcinoma when considering age and gender. This study was designed to describe the distribution of colorectal carcinoma by age at diagnosis, gender, and subsite of the tumor. These factors also are evaluated in conjunction with disease stage and tumor differentiation at the time of diagnosis. METHODS: Data from 419 patients from a population that receives no screening between April 1995 and March 2001 operated on in the Cancer Institute and Imam Khomieni Hospital with a diagnosis of colorectal cancer were used to describe distribution of the colorectal carcinoma by age, gender, tumor subsite and pathology, and stage at diagnosis. RESULTS: There were 403 (96.2 percent) cases of adenocarcinoma. Males and females constituted 52.4 and 47.6 percent of cases, respectively. The mean age was 52.3 years. Patients were divided into two age groups (40 years and younger, and older than 40 years); 16.4 percent of patients had tumors in the proximal colon and 83.6 percent in distal parts. Most patients were Stage II and III (48.1 and 33.4 percent, respectively). Tumor subsite distribution was almost the same between the two age groups (aged 40 years and younger: proximal, 18.5 percent, and distal, 81.5 percent; older than aged 40 years: proximal, 15.7 percent, and distal, 84.3 percent). Most patients in the younger age group were Stage III (45 percent) and in the older age group were Stage II (53.2 percent; P<0.001). Tumor differentiation proportions in patients aged 40 years and younger were: good, 24.4 percent; moderate, 53.6 percent; poor, 22 percent; and in patients older than aged 40 years were: good, 41.5 percent; moderate, 52.6 percent; poor, 5.9 percent (P<0.001). There were no differences in stage and tumor differentiation between two genders, but most of the patients with tumors in proximal colon were males (62.5 percent; P=0.1). CONCLUSIONS: Most of the colorectal carcinomas were in distal parts in our study, so most of these carcinomas can be detected by proctosigmoidoscopy. Because younger patients had more advanced disease, the importance of screening and "clinical suspicion" in the young is important.

Comparison of outcomes in Z-plasty and delayed healing by secondary intention of the wound after excision of the sacral pilonidal sinus: results of a randomized, clinical trial.

PURPOSE: Pilonidal sinus is a common disease, mostly among young males. Although the conventional surgery, secondary repair of the wound after wide excision with or without curettage, is not technically difficult, it takes a long time, weeks or months, for a wound to heal. In this study, we compared outcomes and complications of Z-plasty repair with outcomes and complications of delayed healing by secondary intention (conventional surgery). METHODS: In a randomized, clinical trial, we recruited 72 patients in each arm. All of the patients were operated on by a general surgeon and were followed up for variable periods. Patients in the Z-plasty arm were followed for a mean period of 22.01 months. Patients conventional surgery arm were followed for a mean period of 22.23 months. The main studied outcomes were healing of the wound and disease recurrence during the follow-up period. The main complications that were taken into account were bleeding, hematoma, infection, and recurrence. RESULTS: The two arms were comparable in the age and gender distributions, duration of disease, and history of any types of operations. The duration of hospitalization after the operation was shorter in the conventional surgery group (1.76+/-0.75 days vs. 2.86+/-0.73 days, P<0.001). However, wounds healed much faster in the Z-plasty group (15.4 vs. 41 days, P<0.001). Moreover, it took longer for patients in the conventional surgery group to return to normal activity (17.5 vs. 11.9 days, P<0.001). There was no difference in postoperative complications regarding bleeding, hematoma, infection, or recurrence during the follow-up period in two arms. CONCLUSIONS: Healing was considerably faster in patients who were treated with Z-plasty technique of wound closure. This procedure can be used as a desirable treatment for pilonidal sinus, which is a noncomplex method without increased rate of complications. Nonetheless, it might slightly increase the duration of hospitalization.