Investigation of the pressure value while performing biceps tenodesis for superior capsuler reconstruction.

BACKGROUND: To compare the histopathological results of biceps tenodesis (BT) performed with normal, low, and high pressures for superior capsule reconstruction (SCR) in rabbits with massive rotator cuff tears. MATERIALS AND METHODS: Thirty rabbits were divided into three groups. Rabbits 1-10 underwent SCR with BT at the same pressure (Group 1), value measured in the groove; 50% lower (Group 2); 50% higher (Group 3). After the 4-week follow-up, shoulder were en-bloc excised and histopathological evaluation was performed with modified Bonar's scale. Results were compared between the groups, statistically. RESULTS: Extracellular matrix were significantly lower in group 2 compared to the other groups (p < 0.05). Cellularity levels were significantly lower in group 2 compared to the other groups (p < 0.05). Group 2 had no difference between the sides (p > 0.05). Group 2 had lower vascularity levels compared to the other groups (p = 0.01). DICSUSSION: When the biceps tendon was in the bicipital groove and in a more mobile state with lower pressure exposure. BT performed with a tension that creates less pressure than the biceps in the groove is more successful in SCR.

The subacromial bursa modulates tendon healing after rotator cuff injury in rats.

Rotator cuff injuries result in more than 500,000 surgeries annually in the United States, many of which fail. These surgeries typically involve repair of the injured tendon and removal of the subacromial bursa, a synovial-like tissue that sits between the rotator cuff and the acromion. The subacromial bursa has been implicated in rotator cuff pathogenesis and healing. Using proteomic profiling of bursa samples from nine patients with rotator cuff injury, we show that the bursa responds to injury in the underlying tendon. In a rat model of supraspinatus tenotomy, we evaluated the bursa's effect on the injured supraspinatus tendon, the uninjured infraspinatus tendon, and the underlying humeral head. The bursa protected the intact infraspinatus tendon adjacent to the injured supraspinatus tendon by maintaining its mechanical properties and protected the underlying humeral head by maintaining bone morphometry. The bursa promoted an inflammatory response in injured rat tendon, initiating expression of genes associated with wound healing, including Cox2 and Il6. These results were confirmed in rat bursa organ cultures. To evaluate the potential of the bursa as a therapeutic target, polymer microspheres loaded with dexamethasone were delivered to the intact bursae of rats after tenotomy. Dexamethasone released from the bursa reduced Il1b expression in injured rat supraspinatus tendon, suggesting that the bursa could be used for drug delivery to reduce inflammation in the healing tendon. Our findings indicate that the subacromial bursa contributes to healing in underlying tissues of the shoulder joint, suggesting that its removal during rotator cuff surgery should be reconsidered.

Studying Edema Formation After Release of the Infraspinatus Muscle as an Experimental Model of Rotator Cuff Lesions in Sheep: A Histological Analysis.

BACKGROUND: Muscle edema formation and inflammatory processes are early manifestations of acute rotator cuff lesions in sheep. Histological analysis of affected muscles revealed edema formation, inflammatory changes, and muscle tissue disruption in MRs. HYPOTHESIS: Edema contributes to inflammatory reactions and early muscle fiber degeneration before the onset of fatty infiltration. STUDY DESIGN: Controlled laboratory study. METHODS: Osteotomy of the greater tuberosity, including the insertion of the infraspinatus tendon, was performed on 14 sheep. These experimental animal models were divided into 2 groups: a nontrauma group with surgical muscle release alone (7 sheep) and a trauma group with standardized application of additional trauma to the musculotendinous unit (7 sheep). Excisional biopsy specimens of the infraspinatus muscle were taken at 0, 3, and 4 weeks. RESULTS: Edema formation was histologically demonstrated in both groups and peaked at 3 weeks. At 3 weeks, signs of muscle fiber degeneration were observed. At 4 weeks, ingrowth of loose alveolar and fibrotic tissue between fibers was detected. Fatty tissue was absent. The diameter of muscle fibers increased in both groups, albeit to a lesser degree in the trauma group, and practically normalized at 4 weeks. Immunohistology revealed an increase in macrophage types 1 and 2, as well as inflammatory mediators such as prostaglandin E2 and nuclear factor kappa-light-chain-enhancer of activated B cells. CONCLUSION: Early muscle edema and concomitant inflammation precede muscle fiber degeneration and fibrosis. Edema formation results from tendon release alone and is only slightly intensified by additional trauma. CLINICAL RELEVANCE: This study illustrates that early edema formation and inflammation elicit muscle fiber degeneration that precedes fatty infiltration. Should this phenomenon be applicable to human traumatic rotator cuff tears, then surgery should be performed as soon as possible, ideally within the first 21 days after injury.

Semi-Bone Tunnel Technique Using Double-Row Suture Bridge Combined With Platelet-Rich Plasma Hydrogel for Rotator Cuff Repair in a Rabbit Model.

BACKGROUND: The approach to managing the footprint area and reconstructing the tendon-bone interface (TBI) is critical for optimal healing. PURPOSE: To evaluate the outcomes of the semi-bone tunnel (SBT) technique using a double-row suture bridge combined with platelet-rich plasma (PRP) hydrogel for rotator cuff repair in a rabbit model. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 48 New Zealand White rabbits were divided into 4 groups. The supraspinatus tendons were severed at the footprint to create a rotator cuff tear model in the surgical groups. Rabbits were treated with the traditional onto-surface repair (control group), SBT technique (SBT group), and SBT technique combined with PRP hydrogel implantation (SBT+PRP group). The rabbits without surgery were the normal group. At 8 weeks after surgery, macroscopic observation, magnetic resonance imaging (MRI) and micro-computed tomography (µCT) examinations, histological evaluations, and biomechanical tests were performed to assess the curative effects of the given treatments. RESULTS: The MRI results showed that the repaired supraspinatus tendon presented a uniform signal, minimal inflammatory response, and the lowest signal-to-noise quotient value in the SBT+PRP group. The µCT results suggested that the SBT technique did not reduce the local bone mineral density in the TBI area compared with the onto-surface repair technique. The histological staining results showed that the regenerated TBI in the SBT+PRP group had a 4-layer structure similar to the natural tissue. The highest values for biomechanical properties were observed in the SBT+PRP group, and there was no significant difference between the SBT+PRP group and normal group. CONCLUSION: The SBT technique presented a better tendon-bone healing effect for rotator cuff tear in the rabbit model compared with the traditional onto-surface repair technique. The specimens in the SBT+PRP group had a similar TBI structure and biomechanical properties to the natural tissue. CLINICAL RELEVANCE: The SBT technique can be an alternative surgical approach for rotator cuff repair, especially for moderate to large tears and cases requiring scaffold implantation.

Can imaging determine if a rotator cuff tear is traumatic?

AIM: We reviewed the last decade of literature to update a previous publication on this topic by the senior author. In New Zealand, traumatic causation has implications for entitlement for treatment though the Accident Compensation Corporation (ACC). Acuity and chronicity may also be relevant in determining repairability. METHODS: Literature was reviewed regarding acromial morphology, greater tuberosity (GT) cysts, acromiohumeral interval (AHI), fatty degeneration and atrophy, acromioclavicular (AC) arthrosis, tendinopathy, bursal changes and other features. RESULTS: Some factors can be considered normal for those middle aged and older, including AC arthrosis, type 1 and 2 acromion and tendinopathy. Some factors may indicate acuity, including haemorrhage and debris, GT oedema, mid-substance soft tissue tear, kinking of the tendon and isolated complete subscapularis tears. Other factors may be associated with chronicity, including significant fatty degeneration, positive tangent sign for atrophy, anterior GT cysts, type 3 acromion, critical shoulder angle (CSA) >35 degrees and acromial index (AI) <0.7. CONCLUSION: A multitude of factors on imaging may infer, to a varying degree, the likelihood of acuity or chronicity. The patient history is also of importance in determining causation.

Fixation technique of biodegradable magnesium alloy suture anchor in the rotator cuff repair of the shoulder in a goat model: a technical note.

BACKGROUND: Shoulder disorders, particularly rotator cuff tears, are prevalent musculoskeletal conditions related to aging. Although the widely used suture anchor technique provides strong mechanical support to the tendon, it is associated with a risk of postoperative tendon retearing. The conventionally used titanium alloys can affect the interpretation of magnetic resonance imaging. Degradable magnesium alloys possess excellent biocompatibility, similar mechanical property to the bone, and stimulating bone formation ability from Mg2+. The purpose of this experiment was to develop innovative magnesium-based suture anchors to enhance rotator cuff repair by improving fixation materials, and to evaluate their feasibility in a goat model. METHODS: We developed fluoridized ZK60 suture anchors as the implantation material for two goats, who underwent rotator cuff repair surgery on both shoulders. Computed tomography (CT) and histological analysis were performed at 12 weeks postoperatively, and the results were compared between the magnesium and titanium alloy groups. Additionally, a hematological examination was conducted, which included assessments of red blood cells, white blood cells, platelets, coagulation function, liver function, kidney function, and magnesium ion concentration. RESULTS: The 12-week postoperative CT images showed intact MgF2 ZK60 suture anchors, effectively reconnecting the infraspinatus tendon to the humeral head. The anchors became less visible on CT scans, indicating absorption by surrounding tissues. New bone formation in the MgF2 group surpassed that in the Ti group, demonstrating superior osseointegration. The similarity between cortical bone and magnesium reduced stress-shielding and promoted bone regeneration. Histological analysis revealed successful tendon healing with MgF2 anchors, while the Ti group showed discontinuous interfaces and reduced collagen secretion. Hematological examination showed stable liver, renal function, and magnesium ion levels. CONCLUSIONS: The findings indicate that MgF2-coated suture anchors are feasible for rotator cuff repair and potentially other orthopedic applications. We hope that magnesium alloy anchors can become the solution for rotator cuff tendon repair surgery.

Experimental Study of Autologous Platelet-rich Plasma Combined With Sodium Hyaluronate on Tendon-bone Healing After Rotator Cuff Injury Repair in Rabbits.

OBJECTIVE: To investigate the therapeutic effects of autologous platelet-rich plasma (PRP) combined with sodium hyaluronate on tendon healing following rotator cuff injury repair in rabbits. METHODS: New Zealand white rabbits were randomly assigned to five groups: sham operation group, control group, PRP group, sodium hyaluronate group, and combined group, each comprising 12 rabbits. A rotator cuff injury model was established in all groups except the sham operation group. At 8 weeks post-surgery, 12 lateral rotator cuff specimens were taken from each group. Four specimens were randomly selected from each group for biomechanical testing, and analyses were conducted on the expression of vascular endothelial growth factor (VEGF), the fiber area ratio of COL-I and COL-III, and tissue morphology. RESULTS: The combined group exhibited the highest biomechanical strength in the cuff tissue of white rabbits (P < 0.05). There was no significant difference in VEGF levels among the five groups (F = 0.814, P = 0.523). However, a significant difference was observed in the ratio of fiber area between COL-I and COL-III groups (F = 11.600, P < 0.001), with the combined group scoring the highest (3.82 ± 0.47 minutes). The inflammatory infiltration in tendon-bone tissue was minimal, and histological morphology was optimal. CONCLUSION: The combination of PRP and sodium hyaluronate effectively promotes the repair of rotator cuff injuries and accelerates tendon-bone healing.

The association between a rotator cuff tendon tear and a tear of the long head of the biceps tendon: Chart review study.

Rotator cuff (RC) and long head of the biceps tendon (LHBT) tears are common shoulder problems presented to the orthopedic clinic. The aim of this study was to assess the association between RC and LHBT tears among a Saudi population sample. A total of 243 patients who were diagnosed with shoulder pain due to RC or LHBT tear between 2016 and 2018 using a magnetic resonance imaging scan were included in this study. Females comprised 66% of the sample, and 59% (n = 143) of the shoulders were on the right side. The mean age of the patients was 58 ± 11 years, ranging from 23 to 88 years. A significant association was detected between the LHBT and RC tears (P < 0.001). Out of 26 cases showing RC and LHBT tears, 81% had a full thickness tear, whereas 19% had a partial tear. The LHBT tears were presented significantly in 48% of cases with at least two completely torn RC compared to 10% in cases with one completely torn RC (P < 0.001). The LHBT tear was significantly observed in shoulders with RC tears including the tendons of subscapularis, supraspinatus, and infraspinatus, but not the teres minor (P < 0.001). Both types of tears were presented significantly in senior patients aged more than 65 years compared to younger patients (P < 0.01). Thus, the LHBT should be assessed carefully in shoulders with more than one RC tear or in chronic cases.

Effects of adipose-derived cell supplementation on tendon-bone healing in a rat model of chronic rotator cuff tear with suprascapular nerve injury.

OBJECTIVE: To investigate the effect of adipose-derived cells (ADCs) on tendon-bone healing in a rat model of chronic rotator cuff tear (RCT) with suprascapular nerve (SN) injury. METHODS: Adult rats underwent right shoulder surgery whereby the supraspinatus was detached, and SN injury was induced. ADCs were cultured from the animals' abdominal fat. At 6 weeks post-surgery, the animals underwent surgical tendon repair; the ADC (+ve) group (n = 18) received an ADC injection, and the ADC (-ve) group (n = 18) received a saline injection. Shoulders were harvested at 10, 14, and 18 weeks and underwent histological, fluorescent, and biomechanical analyses. RESULTS: In the ADC (+ve) group, a firm enthesis, including dense mature fibrocartilage and well-aligned cells, were observed in the bone-tendon junction and fatty infiltration was less than in the ADC (-ve) group. Mean maximum stress and linear stiffness was greater in the ADC (+ve) compared with the ADC (-ve) group at 18 weeks. CONCLUSION: ADC supplementation showed a positive effect on tendon-bone healing in a rat model of chronic RCT with accompanying SN injury. Therefore, ADC injection may possibly accelerate recovery in massive RCT injuries.

The Relationship Among Probable SARCopenia, Osteoporosis and SuprasPinatus Tendon Tears in Postmenopausal Women: The SARCOSP Study.

We aimed to investigate the relationship among probable sarcopenia, osteoporosis (OP) and supraspinatus tendon (SSP) tears in postmenopausal women. Postmenopausal women screened/followed for OP were recruited. Demographic data, comorbidities, exercise/smoking status, and handgrip strength values were recorded. Probable sarcopenia was diagnosed as handgrip strength values < 20 kg. Achilles and SSP thicknesses were measured using ultrasound. Among 1443 postmenopausal women, 268 (18.6%) subjects had SSP tears. Unilateral tears were on the dominant side in 146 (10.1%) and on the non-dominant side in 55 women (3.8%). In contrast to those without, women with SSP tears had older age, lower level of education, thinner SSP and lower grip strength (all p < 0.05). In addition, they had higher frequencies of hypertension, hyperlipidemia, DM, OP and probable sarcopenia, but lower exercise frequency (all p < 0.05). Binary logistic regression modeling revealed that age [odds ratio (OR): 1.046 (1.024-1.067 95% CI)], hypertension [OR: 1.560 (1.145-2.124 95% CI)], OP [OR: 1.371 (1.022-1.839 95% CI)] and probable sarcopenia [OR: 1.386 (1.031-1.861 95% CI)] were significant predictors for SSP tears (all p < 0.05). This study showed that age, presence of hypertension, probable sarcopenia and OP were related with SSP tears in postmenopausal women. To this end, although OP appeared to be related to SSP tears, SSP tear/thickness evaluation can be recommended for OP patients, especially those who have other risk factors such as older age, higher BMI, hypertension, and probable sarcopenia.

Teres minor denervation and pathologies resulting in shoulder joint instability and rotator cuff tears: A retrospective cross-sectional MRI study.

Teres minor denervation (TMD) has gained increasing attention in recent years, particularly with the advent of magnetic resonance imaging (MRI). The potential association between TMD and shoulder instability or rotator cuff tear remains a subject of interest in the orthopedic community. In this retrospective and cross-sectional study, authors aim to investigate the potential association between TMD and shoulder instability or rotator cuff tears. Authors retrospectively analyzed MRI findings from 105 patients with TMD, focusing on rotator cuff pathologies, posterior labrocapsular complex (PLCC) tears, and posteroinferior glenohumeral joint capsule alterations. Authors assessed the association between TMD and rotator cuff and PLCC tears. For the multivariate analysis, partial proportional odds models were constructed for subscapularis (SSC) and SSP tears. Rotator cuff tears were present in 82.9% of subjects, with subscapularis (SSC) tears being the most frequent (77.1%). A significant association was observed between TMD and rotator cuff pathology (P = .002). PLCC tears were found in 82.3% of patients, and humeral position relative to the osseous glenoid was noted in 60% of patients with TMD. A significant association was identified between TMD and shoulder instability or labral/capsular abnormalities (P < .001). More than half of the cases exhibited a long tethering appearance toward the axillary neurovascular bundle on T1-weighted sagittal images. Our findings suggest that TMD is significantly associated with rotator cuff tears and shoulder instability. This study highlights the importance of identifying and treating PLCC tears in patients with TMD to address shoulder instability. Further research is needed to elucidate the role of TMD in the pathogenesis of shoulder instability and rotator cuff pathology.

Natural History of Quantitative Fatty Infiltration and 3D Muscle Volume After Nonoperative Treatment of Symptomatic Rotator Cuff Tears: A Prospective MRI Study of 79 Patients.

BACKGROUND: The severity of fatty infiltration (FI) predicts the treatment outcome of rotator cuff tears. The purpose of this investigation was to quantitatively analyze supraspinatus (SSP) muscle FI and volume at the initial presentation and after a 3-month minimum of conservative management. We hypothesized that progression of FI could be predicted with initial tear size, FI, and muscle volume. METHODS: Seventy-nine shoulders with rotator cuff tears were prospectively enrolled, and 2 magnetic resonance imaging (MRI) scans with 6-point Dixon sequences were acquired. The fat fraction within the SSP muscle was measured on 3 sagittal slices, and the arithmetic mean was calculated (FI SSP ). Advanced FI SSP was defined as ≥8%, pathological FI SSP was defined as ≥13.5%, and relevant progression was defined as a ≥4.5% increase in FI SSP . Furthermore, muscle volume, tear location, size, and Goutallier grade were evaluated. RESULTS: Fifty-seven shoulders (72.2%) had normal FI SSP , 13 (16.5%) had advanced FI SSP , and 9 (11.4%) had pathological FI SSP at the initial MRI scan. Eleven shoulders (13.9%) showed a ≥4.5% increase in FI SSP at 19.5 ± 14.7 months, and 17 shoulders (21.5%) showed a ≥5-mm 3 loss of volume at 17.8 ± 15.3 months. Five tears (7.1%) with initially normal or advanced FI SSP turned pathological. These tears, compared with tears that were not pathological, had significantly higher initial mediolateral tear size (24.8 compared with 14.3 mm; p = 0.05), less volume (23.5 compared with 34.2 mm 3 ; p = 0.024), more FI SSP (9.6% compared with 5.6%; p = 0.026), and increased progression of FI SSP (8.6% compared with 0.5%; p < 0.001). An initial mediolateral tear size of ≥20 mm yielded a relevant FI SSP progression rate of 81.8% (odds ratio [OR], 19.0; p < 0.001). Progression rates of 72.7% were found for both initial FI SSP of ≥9.9% (OR, 17.5; p < 0.001) and an initial anteroposterior tear size of ≥17 mm (OR, 8.0; p = 0.003). Combining these parameters in a logistic regression analysis led to an area under the receiver operating characteristic curve (AUC) of 0.913. The correlation between FI SSP progression and the time between MRI scans was weak positive (ρ = 0.31). CONCLUSIONS: Three risk factors for relevant FI progression, quantifiable on the initial MRI, were identified: ≥20-mm mediolateral tear size, ≥9.9% FI SSP , and ≥17-mm anteroposterior tear size. These thresholds were associated with a higher risk of tear progression: 19 times higher for ≥20-mm mediolateral tear size, 17.5 times higher for ≥9.9% FI SSP , and 8 times higher for ≥17-mm anteroposterior tear size. The presence of all 3 yielded a 91% chance of ≥4.5% progression of FI SSP within a mean of 19.5 months. LEVEL OF EVIDENCE: Diagnostic Level II . See Instructions for Authors for a complete description of levels of evidence.

Differences in Clinical Outcomes Between Patients With Retear After Supraspinatus Tendon Repair and Those With Intact Repair at 5-Year Follow-up.

BACKGROUND: It is well known that rotator cuff repair is associated with an overall retear rate of 21% to 26%. However, a cuff retear may not necessarily be associated with poor clinical outcomes. HYPOTHESIS: There would be no difference in clinical outcomes between patients with a cuff retear and those with an intact repair at a midterm follow-up of 5 years. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A retrospective study was conducted involving patients who received arthroscopic complete repair of the supraspinatus tendon between January 2009 and December 2017. Patients who did not have a postoperative magnetic resonance imaging (MRI) scan or who had a follow-up of <5 years were excluded. Clinical outcomes, including the visual analog scale (VAS) score, American Shoulder and Elbow Surgeons (ASES) score, and active forward flexion (FF) of the involved shoulder were assessed at the 2-year and 5-year follow-up points. RESULTS: The study group included 105 patients with a mean follow-up of 85 months. MRI scans were performed at a mean of 20 months. Fourteen full-thickness cuff retears and 91 intact repairs were identified using postoperative MRI scans. Significant improvement in VAS score, ASES score, and FF were found between the preoperative assessment and the 2 designated follow-up points (2 years and 5 years) in both the cuff retear and the intact repair groups (P < .001). The VAS and ASES scores at the 2-year follow-up for the intact repair group were 1.8 ± 2.0 and 80.7 ± 18.1, respectively. The corresponding values for the retear group were 2.3 ± 2.2 and 71.9 ± 19.5, respectively. No significant difference was found between the 2 groups in the VAS and ASES scores at the 2-year follow-up. However, patients with an intact repair had a better VAS score (1.4 ± 1.8; P = .049) and ASES score (81.7 ± 17; P = .019) than those with a cuff retear at the 5-year assessment (3.0 ± 2.8 and 67.1 ± 22.9, respectively). In the intact repair group, 91% of patients achieved the minimal clinically important difference for the 5-year VAS score, compared with 54% in the cuff retear group (P < .001). The corresponding values for the 5-year ASES score were 80% and 54%, respectively (P = .044). FF measurements at the 5-year follow-up in patients with intact repair and those with a cuff retear were 161°± 23° and 144°± 37°, respectively (P = .059). Continuous improvement in VAS score and FF between the 2-year and 5-year follow-up was observed in the intact repair group (P = .005 and P = .04, respectively). CONCLUSION: The patients with an intact repair had better VAS and ASES scores compared with those who had a cuff retear at a midterm follow-up of 5 years. Between the 2-year and the 5-year follow-up, some further improvement was observed in the VAS score and FF in the intact repair group.

In-situ gelation of fibrin gel encapsulating platelet-rich plasma-derived exosomes promotes rotator cuff healing.

Although platelet-rich plasma-derived exosomes (PRP-Exos) hold significant repair potential, their efficacy in treating rotator cuff tear (RCT) remains unknown. In light of the potential for clinical translation of fibrin gel and PRP-Exos, we evaluated their combined impact on RCT healing and explored suitable gel implantation techniques. In vitro experiments demonstrated that PRP-Exos effectively enhanced key phenotypes changes in tendon stem/progenitor cells. Multi-modality imaging, including conventional ultrasound, shear wave elastography ultrasound, and micro-computed tomography, and histopathological assessments were performed to collectively evaluate the regenerative effects on RCT. The regenerated tendons exhibited a well-ordered structure, while bone and cartilage regeneration were significantly improved. PRP-Exos participated in the healing process of RCT. In-situ gelation of fibrin gel-encapsulated PRP-Exos at the bone-tendon interface during surgery proved to be a feasible gel implantation method that benefits the healing outcome. Comprehensive multi-modality postoperative evaluations were necessary, providing a reliable foundation for post-injury repair.

Editorial Commentary: Improved Suture Configurations Can Enhance Shoulder Rotator Cuff Healing: The Cuff Doesn't Always Heal-But We Can Nudge It in the Right Direction.

The success of rotator cuff repair is often measured by patient-reported outcomes or structural healing on magnetic resonance imaging. Ideally, we can achieve both a satisfied patient and a healed tendon. Various technical modifications and stitch patterns have been presented in an effort to achieve the perfect rotator cuff repair. It appears the independently popular suture bridge technique and Mason-Allen stitch may do their best work when combined together. First, double-row repair "anchors down" the tendon to its footprint, and suture bridge adds to this concept with double-row compressive interlinking suture. Second, the Mason-Allen stitch, combining a horizontal stich and a simple stitch that passes around the horizontal, leverages the rip-stop concept where an "anchor suture" is included as a suture is passed around friable tendon like steel rebar rods strengthening concrete. In the midst of many factors out of the surgeon's control during the healing process, we are compelled to listen when a change in our technique might actually make a difference.

Editorial Commentary: Biocomposite Implant Combined With Local Human Recombinant Parathyroid Hormone Enhances the Histological Quality and Biomechanical Strength of Rotator Cuff Repairs.

Rates of rotator cuff repair retear remain unacceptably high and are frequently the source of diminished shoulder function and patient dissatisfaction. Endocrinopathies have been implicated in these processes. Parathyroid hormone (PTH) activates chondrogenesis and angiogenesis at the enthesis and prevents fatty infiltration and atrophy in rotator cuff musculature. These facts have spurred interest in the therapeutic benefits of PTH as a means to enhance tendon healing and strengthen the bone in and around tendon repairs. New research demonstrates that recombinant human PTH delivered locally through a process of coupling it to a bioengineered scaffold "sheath" may be beneficial. The growth factor, encased within polycaprolactone (PCL), is slowly released as the PCL degrades to extend drug delivery time. The augmentation of rotator cuff repairs with this biocomposite material improves short-term structural tissue integrity and promotes the formation of more organized and stronger tendon-to-bone interface in a rabbit model.

Dual Growth Factor Delivery Using Photo-Cross-Linkable Gelatin Hydrogels for Effectively Reinforced Regeneration of the Rotator Cuff Tendon.

Rotator cuff tears are currently treated with drugs (steroids and nonsteroidal anti-inflammatory drugs) and surgery. However, the damaged rotator cuff requires a considerable amount of time to regenerate, and the regenerated tissue cannot restore the same level of function as that before the damage. Although growth factors can accelerate regeneration, they are difficult to be used alone because of the risk of degradation and the difficulties in ensuring their sustained release. Thus, hydrogels such as gelatin are used, together with growth factors. Gelatin is a biocompatible and biodegradable hydrogel derived from collagen; therefore, it closely resembles the components of native tissues and can retain water and release drugs continuously, while also showing easily tunable mechanical properties by simple modifications. Moreover, gelatin is a natural biopolymer that possesses the ability to form hydrogels of varying compositions, thereby facilitating effective cross-linking. Therefore, gelatin can be considered to be suitable for rotator-to-tendon healing. In this study, we designed photo-cross-linkable gelatin hydrogels to enhance spacing and adhesive effects for rotator cuff repair. We mixed a ruthenium complex (Ru(II)bpy32+) and sodium persulfate into gelatin-based hydrogels and exposed them to blue light to induce gelation. Basic fibroblast growth factor and bone morphogenetic protein-12 were encapsulated in the gelatin hydrogel for localized and sustained release into the wound, thereby enhancing the cell proliferation. The effects of these dual growth factor-loaded hydrogels on cell cytotoxicity and tendon regeneration in rotator cuff tear models were evaluated using mechanical and histological assessments. The findings confirmed that the gelatin hydrogel was biocompatible and that treatment with the dual growth factor-loaded hydrogels in in vivo rotator cuff tear models promoted regeneration and functional restoration in comparison with the findings in the nontreated group. Therefore, growth factor-loaded gelatin-based hydrogels may be suitable for the treatment of rotator cuff tears.

Subacromial Balloon Spacer Does Not Reduce the Retear Rate for Massive Rotator Cuff Tears: A Comparative Study.

PURPOSE: To determine whether a subacromial spacer decreases the recurrent rotator cuff tear rate in arthroscopically managed massive rotator cuff tears (MRCTs) with 1 year of follow-up. METHODS: We selected all patients who met the following criteria: (1) an MRCT excluding Collin type A, (2) Goutallier stage equal or less than 2, and (3) complete arthroscopic repair of the MRCT. Patients were allocated into 2 groups: A (without subacromial spacer) or B (with subacromial spacer) for a prospective evaluation 1 year after surgery. The primary outcome was the retear rate, determined with magnetic resonance imaging (MRI) according to the classification of Sugaya. Secondary outcome measures were the functional outcomes using visual analog score, Shoulder Subjective Value, and Constant-Murley Score. Preoperative rotator cuff characteristics such as number of tendons involved and the tear retraction also were evaluated. Patient-related data such as sex, age, laterality, history of smoking, and diabetes mellitus were analyzed. RESULTS: In total, 31 patients were included in group A and 33 in group B. Preoperatively, only 2 differences were found between both groups: a significant (but not clinical) greater Constant score in group A (P = .034) and a slightly greater retraction of the supraspinatus in group B (P = .0025). The overall retear rate between the 2 groups was similar regarding the number of patients (P = .746) and the total number of tendons involved in the recurrent tear (P = .112). At 1-year follow-up, no differences were found in VAS (P = .397), SSV (P = .309), and Constant score (P = .105). CONCLUSIONS: In reparable massive rotator cuff tears (excluding Collin type A), the augmentation of repair with a subacromial spacer did not significantly reduce the number of patients with recurrent rotator cuff tears identified by MRI. It was also ineffective in reducing the number of re-ruptured tendons in these patients. No patient-reported or clinically significant findings were noted in Constant, SSV, and VAS scores at 1-year postoperative follow-up. Patients with MRI findings of a healed rotator cuff (Sugaya 1-3) had better clinical outcomes compared with those without. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Fibroblast Growth Factor Soaked Collagen Membrane Shows No Biomechanical or Histological Advantages in the Treatment of Chronic Rotator Cuff Tears in a Rabbit Model.

PURPOSE: To investigate the histological and biomechanical effects of a fibroblast growth factor (FGF-2)-soaked collagen membrane used to treat a full-thickness chronic rotator cuff (RC) rupture in a rabbit model. METHODS: Forty-eight shoulders from 24 rabbits were used. At the beginning of the procedure, 8 rabbits were killed to assess the control group (Group IT) with intact tendons. To establish a chronic RC tear model, a full-thickness subscapularis tear was created on both shoulders of the remaining 16 rabbits and left for 3 months. The transosseous mattress suture technique was used to repair tears in the left shoulder (Group R). The tears in the right shoulder (Group CM) were treated using the same approach, with an FGF-soaked collagen membrane inserted and sutured over the repair site. Three months after the procedure, all rabbits were killed. Biomechanical testing was performed on the tendons to determine failure load, linear stiffness, elongation intervals, and displacement. Histologically, the modified Watkins score was used to evaluate tendon-bone healing. RESULTS: There was no significant difference among the three groups in terms of failure load, displacement, linear stiffness, and elongation (P > .05). The total modified Watkins score was not affected by applying the FGF-soaked collagen membrane to the repair site (P > .05). Fibrocytes, parallel cells, large-diameter fibers, and the total modified Watkins score were significantly lower in both repair groups when compared to the intact tendon group (P < .05). CONCLUSIONS: In addition to tendon repair, FGF-2 soaked collagen membrane -application at the repair site provides neither biomechanical nor histological advantages in the treatment of chronic RC tears. CLINICAL RELEVANCE: FGF-soaked collagen membrane augmentation provides no impact on the chronic RC tear healing tissue. The need to investigate alternative methods that may have a positive effect on healing in chronic RC repairs continues.

Estrogen and testosterone supplementation improves tendon healing and functional recovery after rotator cuff repair.

Failure of healing after rotator cuff repair (RCR) is common. The purpose of the current study was to evaluate the effect of systemic estrogen or testosterone supplementation on tendon healing after RCR. Seventy-two adult male mice were utilized for all experiments. The supraspinatus tendon was transected and repaired with 6-0 Prolene suture on the left shoulder of 51 animals. Mice were segregated into three groups postoperative: (1) vehicle group (VG; n = 18), (2) estrogen group (EST; n = 17), and (3) testosterone group (TST; n = 16). An unrepaired control group (unrepaired, n = 21) did not have surgery. Utilizing these animals, histological analysis, activity testing, biomechanical testing and RNA sequencing (RNA-seq) was performed. At 8 weeks post-RCR, TST, and EST supplementation improved the overall histologic structure of the repaired enthesis site. No differences in ultimate failure loads or stiffness were detected between VG, EST, and TST groups after biomechanical testing. RCR caused a reduction in wheel activity compared to unrepaired controls and supplementation with TST restored wheel activity. RNA-seq analysis indicated that estrogen and testosterone regulated different pathways associated with enthesis healing, including a suppression of inflammatory signaling. Supplementation with sex hormones improved the structure of the repaired tendon enthesis and significantly regulated expression of diverse pathways regulating multiple biological processes. Testosterone administration following RCR restored wheel activity without having a detrimental impact on biomechanical strength. Future human studies of sex hormone supplementation after RCR are warranted as supplementation in an animal model may improve tendon enthesis healing.