Remnant Tendon Preservation Enhances Rotator Cuff Healing: Remnant Preserving Versus Removal in a Rabbit Model

Evaluation of the management of rotator cuff injuries utilising superparamagnetic iron oxide tracking stem cells

BACKGROUND

The ultrastructure of the tendon-bone interface (TBI) is inherently complex. After arthroscopic reconstruction, it is often replaced by disorganized scar tissue, which increases the risk of re-tearing.Stem cell therapies offer a promising approach to regenerate the original tissue structure and enhance the healing environment. The effectiveness of these therapies depends on understanding the localization, proliferation, and overall behavior of the implanted stem cells. This study aimed to track the distribution of stem cells in a rat model of rotator cuff injury using Magnetic Resonance Imaging (MRI) and superparamagnetic iron oxide nanoparticles (SPIO) and to evaluate the mechanisms and therapeutic effects of stem cell therapy.

METHODS

Adipose-derived mesenchymal stem cells (ADSCs) were isolated and expanded, then labeled with SPIO at an optimized concentration. The visibility of these labeled cells was assessed via MRI, along with evaluations of their viability, potential toxicity, and migration capacity in vitro.For the in vivo study, rats with rotator cuff tears were divided into two groups: a control group that received a PBS injection, and a treatment group that received SPIO-labeled ADSCs (designated as S-A). MRI scans were conducted at 1, 2, and 4 weeks post-surgery, followed by histological analysis after the rats were euthanized. At 8 weeks post-surgery, rats were sacrificed, and their shoulder joints were analyzed biomechanically and histologically to assess the overall treatment efficacy.

RESULTS

SPIO nanoparticles were successfully incorporated into ADSCs, and MRI imaging demonstrated that these SPIO-labeled cells significantly enhanced MRI contrast without affecting cell viability, proliferation, or migration ability. Both MRI and histological analyses confirmed that the implanted stem cells survived and remained localized for at least two weeks. Further histological and biomechanical evaluations indicated that the stem cells facilitated the repair of the TBI. This repair process appeared to be mediated by an increase in M2 macrophage activity within the injured tissue, promoting improved local healing conditions.

CONCLUSION

This study confirms that labeling ADSCs with SPIO nanoparticles is an effective method for tracking these cells in vivo using MRI, providing a non-invasive approach to monitor the repair of injured TBI. Moreover, the localized survival of transplanted stem cells supports their role in enhancing TBI repair by modulating the local inflammatory response.

SCOI Row Technique Versus Double-Row Suture Bridge Technique for Repairing Rotator Cuff Tears: A Biomechanical and Histological Study in Rabbits

BACKGROUND

The double-row suture bridge (SB) is an effective technique for rotator cuff repair. However, because of high-tension sutures and tendon vascular insufficiency, nonunion or retearing of the rotator cuff after SB repair is common. The low-tension suture and microfracture features of the SCOI Row (SR) technique may help address these issues.

PURPOSE

To compare the biomechanical and histological outcomes of SR and SB techniques in treating rotator cuff tears in rabbits.

STUDY DESIGN

Controlled laboratory study.

METHODS

The study utilized a model of acute bilateral supraspinatus tendon tears in the shoulders of 42 New Zealand rabbits. The tear was randomly repaired using either the SR or SB technique on the left or right shoulder. Twelve rabbits were euthanized at 2, 4, and 8 weeks after surgery. Six rabbits were assigned for histological evaluation, while the other 6 were designated for biomechanical testing. Six of the original 42 animals were exclusively allocated for preliminary biomechanical testing at the 0-week time point.

RESULTS

At 8 weeks after surgery, all mended tendons were successfully attached to the footprint region of the greater tubercle without any postoperative complications. In comparison with the SB group, the SR group exhibited superior histological tendon-bone healing characterized by enhanced fibrocartilage regeneration, collagen composition, and fibrous tissue structure. The biomechanical results of the SR group exhibited superior performance compared with the SB group at both the 0- and 8-week postoperative assessments.

CONCLUSIONS

Both repair techniques have demonstrated effectiveness in the rabbit rotator cuff tear model. Nevertheless, when compared with SB, SR demonstrates superior advantages in enhancing biomechanical properties and histological tendon-bone healing.

CLINICAL RELEVANCE

This study proposes that the SR technique could serve as a viable treatment alternative for rotator cuff tears in humans, as it can improve tendon-bone healing and decrease the incidence of failed healing.

Magnetic Seeding of SPIO-BMSCs Into a Biphasic Scaffold Can Promote Tendon-Bone Healing After Rotator Cuff Repair

BACKGROUND

The tendon-bone interface (TBI) in the rotator cuff has a poor intrinsic capacity for healing, which increases the risk of retear after rotator cuff repair (RCR). However, facilitating regeneration of the TBI still remains a great clinical challenge. Herein, the authors established a novel strategy based on magnetic seeding to enhance the TBI regeneration.

HYPOTHESIS

Magnetic seeding bone marrow mesenchymal stem cells labeled with superparamagnetic iron oxide (SPIO-BMSCs) into a biphasic scaffold can promote tendon-bone healing after RCR.

STUDY DESIGN

Controlled laboratory study.

METHODS

BMSCs were labeled with SPIOs. Prussian blue staining, CCK-8 tests, Western blot, and quantitative reverse transcription polymerase chain reaction (PCR) were used to determine the optimal effect concentration of SPIOs on cell bioactivities and abilities. Then SPIO-BMSCs were magnetically seeded into a biphasic scaffold under a magnetic field. The seeding efficacy was assessed by a scanning electron microscope, and the potential mechanism in chondrogenic differentiation after seeding SPIO-BMSCs into the scaffold was evaluated by Western blot and PCR. Furthermore, the effect of SPIO-BMSC/biphasic scaffold on tendon-bone healing after RCR using a rat model was examined using histological analysis, enzyme-linked immunosorbent assay, and biomechanical evaluation.

RESULTS

BMSCs labeled with 100 μg/mL SPIO had no effect on cell bioactivities and the ability of chondrogenic differentiation. SPIO-BMSCs were magnetically seeded into a biphasic scaffold, which offered a high seeding efficacy to enhance chondrogenic differentiation of SPIO-BMSCs via the CDR1as/miR-7/FGF2 pathway for TBI formation in vitro. Furthermore, in vivo application of the biphasic scaffold with magnetically seeded SPIO-BMSCs showed their regenerative potential, indicating that they could significantly accelerate and promote TBI healing with superior biomechanical properties after RCR in a rat rotator cuff tear model.

CONCLUSION

Magnetically seeding SPIO-BMSCs into a biphasic scaffold enhanced seeding efficacy to promote cell distribution and condensation. This construct enhanced the chondrogenesis process via the CDR1as/miR-7/FGF2 pathway and further promoted tendon-bone healing after RCR in a rat rotator cuff tear model.

CLINICAL RELEVANCE

This study provides an alternative strategy for improving TBI healing after RCR.

Arthroscopic cuff repair: footprint remnant preserving versus debriding rotator cuff repair of transtendinous rotator cuff tears with remnant cuff

BACKGROUND

In transtendinous full thickness rotator cuff tears (FTRCT) with remnant cuff, conventionally, cuff remnant of the greater tuberosity (GT) is debrided for better tendon to bone healing. However, larger cuff defect caused overtension on the repaired tendon. The purpose of this study was to compare the clinical outcomes and tendon integrity between remnant preserving and remnant debriding cuff repairs in the transtendinous FTRCT with remnant cuff.

METHODS

From March, 2012 to October, 2017, a total of 127 patients who had the transtendinous FTRCT with remnant cuff were enrolled in this study. Rotator cuff tears were repaired arthroscopically, with patients divided into two groups: group I (n = 63), where rotator cuff remnants were preserved during the repair, and group II (n = 64), where the remnants were debrided during the repair. Clinical outcomes were assessed at the last follow-up (minimum 2 years) using the UCLA score, ASES score, SST score, Constant Shoulder score, and range of motion (ROM). The analysis of structural integrity and tendon quality was performed using the Sugaya classification on postoperative MRI scans at 8 months after surgery.

RESULTS

At the final follow-up, UCLA, ASES, SST, and CS scores significantly improved from preoperative values to postoperative (all p < 0.05): UCLA (I: 19.6 ± 6.0 to 31.7 ± 3.2, II: 18.0 ± 5.7 to 31.5 ± 3.2), ASES (I: 54.3 ± 10.7 to 86.5 ± 12.5, II: 18.0 ± 5.7 to 85.8 ± 12.4), SST (I: 5.6 ± 2.8 to 10.2 ± 2.0, II: 5.0 ± 2.9 to 10.1 ± 2.5), CS (I: 74.0 ± 17.2 to 87.8 ± 9.7, II: 62.0 ± 19.2 to 88.3 ± 6.2). However, there were no significant differences between the two groups (p > 0.05). Also, remnant preserving cuff repair yielded significantly better tendon quality on postoperative MRI (p < 0.05). The incidence of re-tear (Sugaya's Type IV and V) was not significantly different between the two groups (I:17% vs. II:19%; p = 0.053).

CONCLUSIONS

Remnant preserving rotator cuff repairs, which facilitate tendon-to-tendon healing, are superior in terms of tendon quality and are the preferred option for transtendinous FTRCT.

TRIAL REGISTRATION

Retrospectively registered.

Platelet-rich plasma-derived exosomes promote rotator cuff tendon-bone healing

BACKGROUND

Rotator cuff tear (RCT) is the most common type of shoulder joint injury, platelet-rich plasma-derived exosomes (PRP-exos) are highly promising in tissue repair and regeneration. The purpose of this study was to determine the function of PRP-exos in rotator cuff tendon-bone healing.

METHODS

PRP-exos were isolated from the rabbit whole blood by differential ultracentrifugation and characterized through transmission electron microscopy assay, nanoparticle tracking analysis, and western blotting. Alkaline phosphatase and Von Kossa staining were used to show tendon-derived stem cell (TDSC) differentiation. RT-qPCR and western blotting were performed to detect COL II, SOX-9, and TIMP-1. To determine the therapeutic effects of PRP-exos in vivo. Thirty New Zealand white rabbits were divided into control, model, and PRP-exos groups. The RCT animal model was constructed. The changes in tendon-bone tissue were determined by HE staining. Contents of COL-II, SOX-9, and TIMP-1 were determined by immunohistochemistry staining.

RESULTS

PRP-exos were successfully isolated from rabbit blood. PRP-exos promoted TDSC proliferation and differentiation and also induced tendon-specific markers COL II, SOX-9, and TIMP-1 production. In vivo study revealed that PRP-exos promoted early healing of injured tendons. Rabbits treated with PRP-exos had better tissue arrangement in the tear site. Additionally, the contents of COL II, SOX-9, and TIMP-1 were also increased in the RCT rabbit model after PRP-exos treatment.

CONCLUSIONS

PRP-exos enhanced tendon-bone healing by promoting TDSC proliferation and differentiation. This finding indicates that PRP-exos can serve as a promising strategy to treat rotator cuff tendon-bone healing.

Engineered Decellularized Tendon Matrix Putty Preserves Native Tendon Bioactivity to Promote Cell Proliferation and Enthesis Repair

Rotator cuff tears are a common soft tissue injury that can significantly decrease function of the shoulder and cause severe pain. Despite progress in surgical technique, rotator cuff repairs (RCRs) do not always heal efficiently. Many failures occur at the bone-tendon interface as a result of poor healing capacity of the tendon and failure to regenerate the native histological anatomy of the enthesis. While allografts are commercially available, clinical use is limited as they do not stimulate tissue regeneration and are associated with a structural failure of up to 40% in re-tear cases. Novel tissue engineering strategies are being developed with promise, but most involve addition of cells and/or growth factors which extends the timeline for clinical translation. Thus, there exists a significant unmet clinical need for easily translatable surgical augmentation approaches that can improve healing in RCR. Here we describe the development of a decellularized tendon matrix (DTM) putty that preserves native tendon bioactivity using a novel processing technique. In vitro, DTM promoted proliferation of tenocytes and adipose-derived stem cells with an increase in expression-specific transcription factors seen during enthesis development, Scleraxis and Sox9. When placed in a rabbit model of a chronic rotator cuff tear, DTM improved histological tissue repair by promoting calcification at the bone-tendon interface more similar to the normal fibrocartilaginous enthesis. Taken together, these data indicate that the engineered DTM putty retains a pro-regenerative bioactivity that presents a promising translational strategy for improving healing at the enthesis.

High degree of consensus on diagnosis and management of rotator cuff tears: a Delphi approach

PURPOSE

To develop a consensus on diagnosis and treatment of rotator cuff tears. The study focused on selected areas: imaging, prognostic factors, treatment options, surgical techniques.

METHODS

Panel was composed of all members of the shoulder committee of the Italian Society of Arthroscopy, Knee, Upper arm, Sport, Cartilage and Orthopedic techniques (SIAGASCOT). Four rounds were performed. The first round consisted of gathering questions which were then divided into seven blocks referring to: imaging, patient-related prognostic factors, treatment options, surgical steps, reparative techniques, surgical predictive factors, advanced techniques. Subsequent rounds consisted of condensation by means of online questionnaire and debates. Consensus was defined as two-thirds agreement on one answer. Descriptive statistic was used to summarize the data.

RESULTS

Forty-one shoulder experts were involved. Fifty-six statements were finally formulated. A consensus could be achieved on 51. Experts agreed that preoperative magnetic resonance imaging is strongly recommended because it allows a careful evaluation of tear characteristics, while the role of US remains debatable. Controversial patient-related factors such as age, comorbidities, smoking and stiffness do not contraindicate the repair. From a surgical standpoint, the experts highlighted that pseudo-paralysis is not a contraindication to rotator cuff repair. Consensus on specific surgical steps was also achieved: capsular release should be performed only in stiff shoulders; footprint preparation is mandatory, while debridement of tendon edges is not essential. If necessary, a rotator interval release could be performed without interrupting the continuity between subscapularis and supraspinatus tendon; posterior delamination should be always included in the repair. Advanced techniques such as tendon transfers should be selected based on the main clinical deficit, while the superior capsule reconstruction plays a role only in combination with a functional repair.

CONCLUSION

A consensus was achieved almost on every topic of controversy explored. Particularly, MRI was deemed necessary to determine tear characteristics, while radiographs remain important for differential diagnosis; age should not be considered a contraindication to surgery; pseudo-paralysis does not represent a contraindication to arthroscopic rotator cuff repair, but superior capsule reconstruction plays a role only in combination with a functional repair. Latissimus dorsi transfer plays a role when the main functional deficit is in elevation, while the lower trapezius transfer plays a role when the main functional deficit is the external-rotation.

LEVEL OF EVIDENCE

V.

Outcomes After Superior Capsular Reconstruction With an Achilles Tendon-Bone Allograft Using the Modified Keyhole Technique: A 2-Year Follow-up of a Novel Technique for Irreparable Rotator Cuff Tears

Background

Despite improved outcomes, failure or nonhealing of graft materials has been reported after superior capsular reconstruction (SCR) for massive irreparable rotator cuff tears.

Purpose

To evaluate the short-term clinical and radiological outcomes of a novel technique for SCR using an Achilles tendon-bone allograft.

Study Design

Case series; Level of evidence, 4.

Methods

We performed a retrospective review of patients who underwent SCR using an Achilles tendon-bone allograft with the modified keyhole technique and who had a minimum follow-up of 2 years. The visual analog scale score for pain, American Shoulder and Elbow Surgeons score, and Constant score were evaluated as subjective outcomes, while range of motion of the shoulder joint and isokinetic strength were evaluated as objective outcomes. The acromiohumeral interval (AHI), bone-to-bone healing of the allograft and humeral head on computed tomography, and graft integrity on magnetic resonance imaging were evaluated as radiological outcomes.

Results

This study included 32 patients with a mean age of 56.8 ± 4.2 years and a mean follow-up of 28.4 ± 6.2 months. A significant improvement from preoperatively to the last follow-up was seen in the mean visual analog scale score for pain (from 6.7 to 1.8), American Shoulder and Elbow Surgeons score (from 42.7 to 83.8), Constant score (from 47.2 to 78.5), and AHI (from 4.8 to 8.2 mm) (P < .001 for all) as well as range of motion in forward elevation and internal rotation (P < .001 for both). Medial-to-lateral graft integrity was good in all patients. Nonunion at the fitting zone of the keyhole on the greater tuberosity was diagnosed in 1 case (3.1%), and failure of incorporation between the allograft and remnant tendon at the site of posterior margin convergence was observed in 4 cases (12.5%).

Conclusion

The outcomes after SCR using an Achilles tendon-bone allograft and the keyhole technique improved, with an increased AHI and excellent integrity in the medial and lateral directions compared with preoperatively. This technique is a reasonable option for the surgical treatment of irreparable rotator cuff tears.

Cancellous bone should not be exposed during medialized rotator cuff repair based on bone-to-tendon healing in a rat mode

PURPOSE

To compare the biological bone-to-tendon healing using three different medialized bone bed preparation techniques (i.e. cortical bone exposure, cancellous bone exposure, and no cartilage removal) in a rat model of medialized rotator cuff repair.

METHODS

Twenty-one male Sprague-Dawley rats with 42 shoulders were subjected to bilateral supraspinatus tenotomy from the greater tuberosity. The rotator cuff was repaired using medialized anchoring with the cortical bone exposed, the cancellous bone exposed, or no cartilage removed. Four and three rats in each group were killed for biomechanical testing and histological evaluation, respectively, at postoperative 6 weeks.

RESULTS

All rats survived until the end of the study, but one infected shoulder in the cancellous bone exposure group was excluded from further analysis. Compared with the cortical bone exposure and no cartilage removal groups, the rotator cuff healing of the cancellous bone exposure group showed significantly lower maximum load (cancellous bone exposure group: 26.2 ± 2.3 N, cortical bone exposure group: 37.6 ± 7.9 N, no cartilage removal group: 34.6 ± 7.2 N, P = 0.005 and 0.029) and less stiffness (cancellous bone exposure group: 10.5 ± 2.4 N/mm, cortical bone exposure group: 17.4 ± 6.7 N, no cartilage removal group: 16.0 ± 3.9 N, P = 0.015 and 0.050) at postoperative 6 weeks. In all three groups, the repaired supraspinatus tendon healed towards the original insertion rather than the medialized insertion. The cancellous bone exposure group showed inferior fibrocartilage formation and insertion healing.

CONCLUSIONS

The medialized bone-to-tendon repair strategy does not guarantee complete histological healing, and the removal of excessive bony structure impairs bone-to-tendon healing. This study concludes that surgeons should not expose the cancellous bone during the medialized rotator cuff repair.

Outcomes After Combined Remnant Preservation and Bone Marrow Stimulation for Acute Rotator Cuff Tears

Background

Both remnant preservation (RP) and bone marrow stimulation (BMS) enhance the healing potential of the repaired rotator cuff by improving the biological milieu of the tendon-bone interface.

Purpose

To evaluate the clinical and imaging outcomes of arthroscopic rotator cuff repair using a combined RP-BMS technique in patients with acute rotator cuff tears.

Study Design

Cohort study; Level of evidence, 3.

Methods

Between January 2016 and June 2019, a total of 56 patients were diagnosed with acute rotator cuff tears; 29 patients underwent conventional repair (group 1), and 27 patients underwent RP-BMS (group 2). At a minimum follow-up period of 2 years, the authors compared clinical outcomes with the University of California-Los Angeles; Constant; American Shoulder and Elbow Surgeons; and pain visual analog scale scores as well as shoulder range of motion. Tendon integrity and retear were assessed on magnetic resonance imaging according to the Sugaya classification (intact, grades 1-3; retear, grades 4-5). Between-group comparisons were conducted using the Student t test or Mann-Whitney U test for continuous variables and the Pearson chi-square test or Fisher exact test for categorical variables.

Results

In both groups, patients had significant preoperative to postoperative improvement on all clinical outcome measures (P = .001 for all). Shoulder abduction in group 2 was significantly greater compared with group 1 at the postoperative 3-month (107.37° ± 8.32° vs 95.44° ± 8.78°; P = .001), 6-month (155.25° ± 10.02° vs 144.72° ± 9.28°; P = .001), and final (165.15° ± 9.17° vs 158.31° ± 8.01°; P = .021) follow-ups. At the final follow-up, significantly more patients in group 2 had intact tendons (Sugaya grades 1-3) compared with group 1 (P = .015), and the tendon retear rate was lower in group 2 (1/27; 3.70%) than in group 1 (7/29; 24.14%) (P = .033).

Conclusion

Both surgical techniques led to satisfactory clinical outcomes, but shoulder abduction was greater after the RP-BMS technique compared with conventional repair. RP-BMS may be an alternative surgical technique to improve tendon integrity and retear rates after the repair of acute rotator cuff tears.

3D cell-printing of gradient multi-tissue interfaces for rotator cuff regeneration

Owing to the prevalence of rotator cuff (RC) injuries and suboptimal healing outcome, rapid and functional regeneration of the tendon–bone interface (TBI) after RC repair continues to be a major clinical challenge. Given the essential role of the RC in shoulder movement, the engineering of biomimetic multi-tissue constructs presents an opportunity for complex TBI reconstruction after RC repair. Here, we propose a gradient cell-laden multi-tissue construct combined with compositional gradient TBI-specific bioinks via 3D cell-printing technology. In vitro studies demonstrated the capability of a gradient scaffold system in zone-specific inducibility and multi-tissue formation mimicking TBI. The regenerative performance of the gradient scaffold on RC regeneration was determined using a rat RC repair model. In particular, we adopted nondestructive, consecutive, and tissue-targeted near-infrared fluorescence imaging to visualize the direct anatomical change and the intricate RC regeneration progression in real time in vivo. Furthermore, the 3D cell-printed implant promotes effective restoration of shoulder locomotion function and accelerates TBI healing in vivo. In summary, this study identifies the therapeutic contribution of cell-printed constructs towards functional RC regeneration, demonstrating the translational potential of biomimetic gradient constructs for the clinical repair of multi-tissue interfaces.

•

A biomimetic cellular TBI scaffold was 3D bioprinted with dECM bioinks.

•

A gradient multi-tissue construct was implanted for RC repair in vivo.

•

Targeted NIR fluorescence imaging facilitated real-time monitoring of TBI regeneration.

•

The scaffolds had therapeutic contribution on gradient TBI regeneration and functional recovery.

H-loop Knotless Double-Row Repair Versus Knotted Suture Bridge for Rotator Cuff Tears: A Biomechanical and Histological Study in an Animal Model

BACKGROUND

Knotted suture bridge repair (KSBR) has been widely proven to be an effective method for rotator cuff repairs. However, the occurrence of type 2 failure after suture bridge repair remains a frequent problem because of the stress concentration and disturbance of tendon perfusion in the medial row. The authors have developed the H-loop knotless double-row repair (HLDR) to counteract these problems.

PURPOSE

To compare the biomechanical and histological outcomes of HLDR and KSBR for rotator cuff tear in the rabbit model.

STUDY DESIGN

Controlled laboratory study.

METHODS

Acute bilateral supraspinatus tears were created on the shoulders of 46 New Zealand White rabbits. HLDR and KSBR were randomly performed on the left side or right side. Thirteen animals each were sacrificed at 2, 4, and 8 weeks after surgery (n = 39), with 6 rabbits used for histological evaluation and the other 7 rabbits for biomechanical testing. The remaining 7 animals from the original 46 were only used for initial biomechanical evaluation at week 0.

RESULTS

Macroscopically, all repaired tendons were connected to their footprint on the greater tuberosity without postoperative complications at 8 weeks after surgery. The HLDR group had significantly better histological bone-to-tendon integration compared with the KSBR group in terms of fibrocartilage regeneration, collagen composition, and fiber organization. The biomechanical outcomes in the HLDR group were demonstrated to be better than those of the KSBR group at time 0 and 8 weeks after surgery.

CONCLUSION

Both repair techniques were effective for rotator cuff tears in a rabbit rotator cuff tear model; however, HLDR demonstrated more advantages in improving biomechanical properties and histological tendon-to-bone healing compared with KSBR.

CLINICAL RELEVANCE

This animal study suggested that HLDR might be an alternative choice for rotator cuff tears in humans to increase tendon-to-bone healing and reduce the rate of failure to heal.

Differentiation Ability of Tendon-Derived Stem Cells and Histological Characteristics of Rotator Cuff Remnant on the Greater Tuberosity Degenerated With Age and Chronicity

PURPOSE

To explore and measure the presence and activity of tendon-derived stem cells (TDSCs), as well as histological changes of rotator cuff remnant by age and chronicity of the rotator cuff tear (RCT).

METHODS

154 patients with a full-thickness tear of supraspinatus and/or infraspinatus tendon were included. 52 qualified remnants of the greater tuberosity were captured through arthroscopy. TDSCs in the remnants were isolated for proliferation ability, basal gene expression, and trilineage differentiation detection. Histological characteristics were evaluated by observation of staining under a light microscope and transmission electron microscopy (TEM). To observe the effect of age, samples were divided into two groups: young (＜60 years old) and old (≥60 years old). For chronicity comparison, samples were divided into three groups: acute group (＜3 months), intermediate group (3-12 months), and chronic group (≥12 months).

RESULTS

Between age groups, the remnants in older patients were found to have lower TDSC proliferation ability (cell counting kit-8 results, old: .5325 ± .050, young: .6623 ± .196; P = .008) and basal expression of aggrecan (.630 ± .239; P = .002) and TGF-β1 (transforming growth factor-β1, .589 ± .326, P = .008), weaker ability of chondrogenic differentiation. Furthermore, the remnant tendons in chronic group was found to have weaker adipogenic and chondrogenic differentiation ability of TDSCs, lower tendon degenerative score (acute: 3.57 ± 1.902, intermediate: 5.94 ± 2.313, chronic: 6.86 ± 2.193; P = .023), increased type III collagen region ratio in insertion area (acute: 86.10% ± 8.29%, intermediate: 94.06% ± 5.36%, chronic: 98.90% ± .49%; P = .023), and larger fibril diameters.

CONCLUSION

Differentiation ability of TDSCs derived from the rotator cuff remnant was reduced with age and chronicity. Histological degeneration of remnant tendon deteriorated with chronicity. Remnant in the greater tuberosity was still alive, but those in young or acute injury patients were more active after full-thickness RCT.

CLINICAL RELEVANCE

TDSCs exist in rotator cuff remnant on the greater tuberosity and have multilineage differentiation ability. But the remnant degenerated with age and chronicity.

Failure Rate After Superior Capsular Reconstruction With Achilles Tendon-Bone Allograft for Irreparable Rotator Cuff Tears

Background

Superior capsular reconstruction (SCR) is an alternative to reverse shoulder arthroplasty for irreparable rotator cuff tears (IRCTs). The reconstructed capsule acts as a static restraint to prevent superior migration of the humeral head. Traditional SCR uses a fascia lata autograft, which has shown failure at the greater tuberosity. An Achilles tendon-bone allograft has been proposed to improve the failure rate.

Purpose

To evaluate the surgical outcomes of SCR using an Achilles tendon-bone allograft for the treatment of IRCTs.

Study Design

Case series; Level of evidence, 4.

Methods

We retrospectively evaluated 6 patients with massive IRCTs who underwent SCR using an Achilles tendon-bone allograft between January 2017 and January 2018. Clinical outcomes were assessed using range of motion, the American Shoulder and Elbow Surgeons score, and the visual analog scale for pain. The acromiohumeral distance and the status of graft integrity were evaluated using serial magnetic resonance imaging. Second-look arthroscopy surgery was performed to evaluate graft integrity at the mean of 7.5 months postoperative.

Results

The mean ± SD clinical follow-up period was 14.5 months (range, 12-17 months). The American Shoulder and Elbow Surgeons and visual analog scale scores improved from 42.8 ± 11.9 and 4.0 ± 1.2 to 62.1 ± 14.7 and 2.8 ± 1.4, respectively. Forward flexion and external rotation improved from 98° ± 36° and 58° ± 4° to 123° ± 20° and 39° ± 8°, respectively. The acromiohumeral distance improved from 3.9 ± 0.8 mm to 6.4 ± 2.2 mm at final follow-up. However, second-look arthroscopy at a mean of 7.6 months postoperatively confirmed a graft failure rate of 83.3%.

Conclusion

SCR using an Achilles tendon-bone allograft for the treatment of IRCTs had a high graft failure rate among patients in this case series.

3D cell-printing of tendon-bone interface using tissue-derived extracellular matrix bioinks for chronic rotator cuff repair

The tendon-bone interface (TBI) in rotator cuffs exhibits a structural and compositional gradient integrated through the fibrocartilaginous transition. Owing to restricted healing capacity, functional regeneration of the TBI is considered a great clinical challenge. Here, we establish a novel therapeutic platform based on 3D cell-printing and tissue-specific bioinks to achieve spatially-graded physiology for functional TBI regeneration. The 3D cell-printed TBI patch constructs are created via a spatial arrangement of cell-laden tendon and bone-specific bioinks in a graded manner, approximating a multi-tissue fibrocartilaginous interface. This TBI patch offers a cell favorable microenvironment, including high cell viability, proliferative capacity, and zonal-specific differentiation of encapsulated stem cells for TBI formation in vitro. Furthermore, in vivo application of spatially-graded TBI patches with stem cells demonstrates their regenerative potential, indicating that repair with 3D cell-printed TBI patch significantly accelerates and promotes TBI healing in a rat chronic tear model. Therefore, our findings propose a new therapeutic strategy for functional TBI regeneration using 3D cell-printing and tissue-specific decellularized extracellular matrix (dECM) bioink-based approach.

Editorial Commentary: Make Use of the Native Insertion Structure in Rotator Cuff Repair

When there is remnant tendon stump on the footprint in rotator cuff tear, preserving the whole insertion structure and reattaching the rotator cuff to the footprint or tendon stump results in a better rotator cuff-greater tuberosity connection.