Tendon to bone healing: differences in biomechanical, structural, and compositional properties due to a range of activity levels

Association between timing of initiating supervised physical rehabilitation after rotator cuff repair and incidence of repeat repair and capsulitis: a population-based analysis

BACKGROUND

There is limited consensus on the optimal time to initiate supervised physical rehabilitation after a rotator cuff repair (RCR). We examined whether timing of initiating supervised physical rehabilitation was associated with repeat RCR or development of adhesive capsulitis within 12 months postoperatively in an observational cohort of commercially insured adults.

METHODS

This retrospective cohort study used the IBM MarketScan Commercial Claims and Encounters Database. We included adults aged 18-64 who underwent a unilateral outpatient RCR between 2017 and 2020 and initiated supervised physical rehabilitation 1-90 days postoperatively. Multivariable logistic regression models examined the adjusted association between time of initiating supervised physical rehabilitation (1-13, 14-27, 28-41, and 42-90 days postoperatively) and each of the primary outcomes: repeat RCR and capsulitis. In a sensitivity analysis, time to rehabilitation was alternatively categorized using a data-driven approach of quartiles (1-7, 8-16, 17-30, and 31-90 days postoperatively). We report adjusted odds ratios (OR).

RESULTS

Among 33,841 patients (86.7% arthroscopic index RCR), the median time between index RCR and rehabilitation initiation was 16 days (interquartile range 7-30), with 39.9% initiating rehabilitation at 1-13 days. Additionally, 2.2% underwent repeat RCR within 12 months, and 12-month capsulitis was identified in 1.9% of patients. There were no significant associations between timing of initiating rehabilitation and 12-month repeat RCR (OR 0.85-0.93, P = .18-.49) or 12-month capsulitis (OR 0.83-0.94, P = .22-.63). Lack of associations between timing and outcomes was supported in sensitivity analyses.

CONCLUSIONS

Timing of initiating rehabilitation was not significantly associated with adverse outcomes after RCR. The finding of no increased odds of repeat RCR or capsulitis with the earliest timing may support earlier initiation of rehabilitation to accelerate return to daily activities. Findings should be replicated in another dataset of similarly-aged patients.

The effect of rehabilitation time on functional recovery after arthroscopic rotator cuff repair: a systematic review and meta-analysis

Objective

We compared the effects of early and delayed rehabilitation on the function of patients after rotator cuff repair by meta-analysis to find effective interventions to promote the recovery of shoulder function.

Methods

This meta-analysis was registered in PROSPERO (CRD42023466122). We manually searched the randomized controlled trials (RCTs) in the Cochrane Library, Pubmed, Cochrane Library, EMBASE, the China National Knowledge Infrastructure (CNKI), the China VIP Database (VIP), and the Wanfang Database to evaluate the effect of early and delayed rehabilitation after arthroscopic shoulder cuff surgery on the recovery of shoulder joint function. Review Manager 5.3 software was used to analyze the extracted data. Then, the PEDro scale was employed to appraise the methodological quality of the included research.

Results

This research comprised nine RCTs and 830 patients with rotator cuff injuries. According to the findings of the meta-analysis, there was no discernible difference between the early rehabilitation group and the delayed rehabilitation group at six and twelve months after the surgery in terms of the VAS score, SST score, follow-up rotator cuff healing rate, and the rotator cuff retear rate at the final follow-up. There was no difference in the ASES score between the early and delayed rehabilitation groups six months after the operation. However, although the ASES score in the early rehabilitation group differed significantly from that in the delayed rehabilitation group twelve months after the operation, according to the analysis of the minimal clinically important difference (MCID), the results have no clinical significance.

Conclusions

The improvement in shoulder function following arthroscopic rotator cuff surgery does not differ clinically between early and delayed rehabilitation. When implementing rehabilitation following rotator cuff repair, it is essential to consider the paradoxes surrounding shoulder range of motion and tendon anatomic healing. A program that allows for flexible progression based on the patient's ability to meet predetermined clinical goals or criteria may be a better option.

Which is better? Early versus delayed rehabilitation after arthroscopic rotator cuff repair

PURPOSE

This study aimed to compare the 5-year clinical and functional outcomes, including repaired tendon healing status, between early and delayed rehabilitation after arthroscopic rotator cuff repair METHODS: A total of 75 patients with rotator cuff tears (less than 5 cm) underwent arthroscopic repairs over a 60-month period. Participants were randomly assigned to early and delayed postoperative rehabilitation groups with distinct protocols. Clinical and functional outcome measures included Constant score, University of California at Los Angeles (UCLA) score, visual analogue scale for pain and isokinetic dynamometer test for muscle strength recovery. Clinical and functional scores were compared between baseline and 5 years postoperatively. Radiologic assessment via magnetic resonance imaging was performed at a minimum of 12 months postoperatively for evaluations of tendon integrity and recurrent tears.

RESULTS

Baseline characteristics showed no statistically significant differences between groups. Both groups demonstrated equivalent improvement in range of motion and pain scores with no statistical differences. Clinical scores improved significantly in both groups by postoperative 12 months and plateaued. At the postoperative 5-year mark, the early group showed better improvement in the visual analogue scale and UCLA score, while the delayed group had superior Constant scores. Postoperative magnetic resonance imaging revealed six recurrent tears, two in the early group and four in the delayed group, with no statistical differences. Muscle strength recovery showed no differences between the two groups.

CONCLUSION

Both the early and the delayed rehabilitation groups showed similar outcomes in postoperative range of motion, functional scores, muscle strength recovery and tendon healing in the short- and mid-term follow-ups.

LEVEL OF EVIDENCE

Level III.

Anatomical design and production of a novel three-dimensional co-culture system replicating the human flexor digitorum profundus enthesis

The enthesis, the specialized junction between tendon and bone, is a common site of injury. Although notoriously difficult to repair, advances in interfacial tissue engineering techniques are being developed for restorative function. Most notably are 3D in vitro co-culture models, built to recreate the complex heterogeneity of the native enthesis. While cell and matrix properties are often considered, there has been little attention given to native enthesis anatomical morphometrics and replicating these to enhance clinical relevance. This study focuses on the flexor digitorum profundus (FDP) tendon enthesis and, by combining anatomical morphometrics with computer-aided design, demonstrates the design and construction of an accurate and scalable model of the FDP enthesis. Bespoke 3D-printed mould inserts were fabricated based on the size, shape and insertion angle of the FDP enthesis. Then, silicone culture moulds were created, enabling the production of bespoke anatomical culture zones for an in vitro FDP enthesis model. The validity of the model has been confirmed using brushite cement scaffolds seeded with osteoblasts (bone) and fibrin hydrogel scaffolds seeded with fibroblasts (tendon) in individual studies with cells from either human or rat origin. This novel approach allows a bespoke anatomical design for enthesis repair and should be applied to future studies in this area.

Application of Nondegradable Synthetic Materials for Tendon and Ligament Injury

Tendon and ligament injuries, prevalent requiring surgical intervention, significantly impact joint stability and function. Owing to excellent mechanical properties and biochemical stability, Nondegradable synthetic materials, including polyethylene terephthalate (PET) and polytetrafluoroethylene (PTFE), have demonstrated significant potential in the treatment of tendon and ligament injuries. These above materials offer substantial mechanical support, joint mobility, and tissue healing promotion of the shoulder, knee, and ankle joint. This review conclude the latest development and application of nondegradable materials such as artificial patches and ligaments in tendon and ligament injuries including rotator cuff tears (RCTs), anterior cruciate ligament (ACL) injuries, and Achilles tendon ruptures.

Hedgehog Activation for Enhanced Rotator Cuff Tendon-to-Bone Healing

BACKGROUND

Rotator cuff repair is a common orthopaedic procedure, yet the rate of failure to heal after surgery is high. Repair site rupture is due to poor tendon-to-bone healing and lack of regeneration of the native fibrocartilaginous enthesis. During development, the enthesis is formed and mineralized by a pool of progenitors activated by hedgehog signaling. Furthermore, hedgehog signaling drives regenerative enthesis healing in young animals, in contrast to older animals, in which enthesis injuries heal via fibrovascular scar and without participation of hedgehog signaling.

HYPOTHESIS

Hedgehog activation improves tendon-to-bone healing in an animal model of rotator cuff repair.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 78 adult Sprague-Dawley rats were used. Supraspinatus tendon injury and repair were completed bilaterally, with microsphere-encapsulated hedgehog agonist administered to right shoulders and control microspheres administered to left shoulders. Animals were sacrificed after 3, 14, 28, or 56 days. Gene expression and histological, biomechanical, and bone morphometric analyses were conducted.

RESULTS

At 3 days, hedgehog signaling pathway genes Gli1 (1.70; P = .029) and Smo (2.06; P = .0173), as well as Runx2 (1.69; P = .0386), a transcription factor of osteogenesis, were upregulated in treated relative to control repairs. At 14 days, transcription factors of tenogenesis, Scx (4.00; P = .041), and chondrogenesis, Sox9 (2.95; P = .010), and mineralized fibrocartilage genes Col2 (3.18; P = .031) and Colx (1.85; P = .006), were upregulated in treated relative to control repairs. Treatment promoted fibrocartilage formation at the healing interface by 28 days, with improvements in tendon-bone maturity, organization, and continuity. Treatment led to improved biomechanical properties. The material property strength (2.43 vs 1.89 N/m2; P = .046) and the structural property work to failure (29.01 vs 18.09 mJ; P = .030) were increased in treated relative to control repairs at 28 days and 56 days, respectively. Treatment had a marginal effect on bone morphometry underlying the repair. Trabecular thickness (0.08 vs 0.07 mm; P = .035) was increased at 28 days.

CONCLUSION

Hedgehog agonist treatment activated hedgehog signaling at the tendon-to-bone repair site and prompted increased mineralized fibrocartilage production. This extracellular matrix production and mineralization resulted in improved biomechanical properties, demonstrating the therapeutic potential of hedgehog agonism for improving tendon-to-bone healing after rotator cuff repair.

CLINICAL RELEVANCE

This study demonstrates the therapeutic potential of hedgehog agonist treatment for improving tendon-to-bone healing after rotator cuff injury and repair.

Losartan in Combination With Bone Marrow Stimulation Showed Synergistic Effects on Load to Failure and Tendon Matrix Organization in a Rabbit Model

PURPOSE

To investigate the effects of combining bone marrow stimulation (BMS) with oral losartan to block transforming growth factor β1 (TGF-β1) on biomechanical repair strength in a rabbit chronic injury model.

METHODS

Forty rabbits were randomly allocated into 4 groups (10 in each group). The supraspinatus tendon was detached and left alone for 6 weeks to establish a rabbit chronic injury model and was then repaired in a surgical procedure using a transosseous, linked, crossing repair construct. The animals were divided into the following groups: control group (group C), surgical repair only; BMS group (group B), surgical repair with BMS of the tuberosity; losartan group (group L), surgical repair plus oral losartan (TGF-β1 blocker) for 8 weeks; and BMS-plus-losartan group (group BL), surgical repair plus BMS plus oral losartan for 8 weeks. At 8 weeks after repair, biomechanical and histologic evaluations were performed.

RESULTS

The biomechanical testing results showed significantly higher ultimate load to failure in group BL than in group B (P = .029) but not compared with group C or group L. A 2 × 2 analysis-of-variance model found that the effect of losartan on ultimate load significantly depended on whether BMS was performed (interaction term F1,28 = 5.78, P = .018). No difference was found between the other groups. No difference in stiffness was found between any groups. On histologic assessment, groups B, L, and BL showed improved tendon morphology and an organized type I collagen matrix with less type III collagen compared with group C. Group BL showed the most highly organized tendon matrix with more type I collagen and less type III collagen, which indicates less fibrosis. Similar results were found at the bone-tendon interface.

CONCLUSIONS

Rotator cuff repair combined with oral losartan and BMS of the greater tuberosity showed improved pullout strength and a highly organized tendon matrix in this rabbit chronic injury model.

CLINICAL RELEVANCE

Tendon healing or scarring is accompanied by the formation of fibrosis, which has been shown to result in compromised biomechanical properties, and is therefore a potential limiting factor in healing after rotator cuff repair. TGF-β1 expression has been shown to play an important role in the formation of fibrosis. Recent studies focusing on muscle healing and cartilage repair have found that the downregulation of TGF-β1 by losartan intake can reduce fibrosis and improve tissue regeneration in animal models.

Quadriceps injuries

Injuries to the quadriceps muscle group are common in athletes performing high-speed running and kicking sports. The complex anatomy of the rectus femoris puts it at greatest risk of injury. There is variability in prognosis in the literature, with reinjury rates as high as 67% in the severe graded proximal tear. Studies have highlighted that athletes can reinjure after nonoperative management, and some benefit may be derived from surgical repair to restore function and return to sport (RTS). This injury is potentially career-threatening in the elite-level athlete, and we aim to highlight the key recent literature on interventions to restore strength and function to allow early RTS while reducing the risk of injury recurrence. This article reviews the optimal diagnostic strategies and classification of quadriceps injuries. We highlight the unique anatomy of each injury on MRI and the outcomes of both nonoperative and operative treatment, providing an evidence-based management framework for athletes.

Preclinical tendon and ligament models: Beyond the 3Rs (replacement, reduction, and refinement) to 5W1H (why, who, what, where, when, how)

Several tendon and ligament animal models were presented at the 2022 Orthopaedic Research Society Tendon Section Conference held at the University of Pennsylvania, May 5 to 7, 2022. A key objective of the breakout sessions at this meeting was to develop guidelines for the field, including for preclinical tendon and ligament animal models. This review summarizes the perspectives of experts for eight surgical small and large animal models of rotator cuff tear, flexor tendon transection, anterior cruciate ligament tear, and Achilles tendon injury using the framework: "Why, Who, What, Where, When, and How" (5W1H). A notable conclusion is that the perfect tendon model does not exist; there is no single gold standard animal model that represents the totality of tendon and ligament disease. Each model has advantages and disadvantages and should be carefully considered in light of the specific research question. There are also circumstances when an animal model is not the best approach. The wide variety of tendon and ligament pathologies necessitates choices between small and large animal models, different anatomic sites, and a range of factors associated with each model during the planning phase. Attendees agreed on some guiding principles including: providing clear justification for the model selected, providing animal model details at publication, encouraging sharing of protocols and expertise, improving training of research personnel, and considering greater collaboration with veterinarians. A clear path for translating from animal models to clinical practice was also considered as a critical next step for accelerating progress in the tendon and ligament field.

Structural and functional heterogeneity of mineralized fibrocartilage at the Achilles tendon-bone insertion

A demanding task of the musculoskeletal system is the attachment of tendon to bone at entheses. This region often presents a thin layer of fibrocartilage (FC), mineralized close to the bone and unmineralized close to the tendon. Mineralized FC deserves increased attention, owing to its crucial anchoring task and involvement in enthesis pathologies. Here, we analyzed mineralized FC and subchondral bone at the Achilles tendon-bone insertion of rats. This location features enthesis FC anchoring tendon to bone and sustaining tensile loads, and periosteal FC facilitating bone-tendon sliding with accompanying compressive and shear forces. Using a correlative multimodal investigation, we evaluated potential specificities in mineral content, fiber organization and mechanical properties of enthesis and periosteal FC. Both tissues had a lower degree of mineralization than subchondral bone, yet used the available mineral very efficiently: for the same local mineral content, they had higher stiffness and hardness than bone. We found that enthesis FC was characterized by highly aligned mineralized collagen fibers even far away from the attachment region, whereas periosteal FC had a rich variety of fiber arrangements. Except for an initial steep spatial gradient between unmineralized and mineralized FC, local mechanical properties were surprisingly uniform inside enthesis FC while a modulation in stiffness, independent from mineral content, was observed in periosteal FC. We interpreted these different structure-property relationships as a demonstration of the high versatility of FC, providing high strength at the insertion (to resist tensile loading) and a gradual compliance at the periosteal surface (to resist contact stresses). STATEMENT OF SIGNIFICANCE: Mineralized fibrocartilage (FC) at entheses facilitates the integration of tendon in bone, two strongly dissimilar tissues. We focus on the structure-function relationships of two types of mineralized FC, enthesis and periosteal, which have clearly distinct mechanical demands. By investigating them with multiple high-resolution methods in a correlative manner, we demonstrate differences in fiber architecture and mechanical properties between the two tissues, indicative of their mechanical roles. Our results are relevant both from a medical viewpoint, targeting a clinically relevant location, as well as from a material science perspective, identifying FC as high-performance versatile composite.

Mechanics and differential healing outcomes of small and large defect injuries of the tendon-bone attachment in the rat rotator cuff

INTRODUCTION

Rotator cuff tear size affects clinical outcomes following rotator cuff repair and is correlated with the risk of recurrent tendon defects. This study aimed to understand if and how the initial defect size influences the structural and mechanical outcomes of the injured rotator cuff attachment in vivo.

METHODS

Full-thickness punch injuries of the infraspinatus tendon-bone attachment in Long Evans rats were created to compare differences in healing outcomes between small and large defects. Biomechanical properties, gross morphology, bone remodeling, and cell and tissue morphology were assessed at both 3- and 8-weeks of healing.

RESULTS

At the time of injury (no healing), large defects had decreased mechanical properties compared to small defects, and both defect sizes had decreased mechanical properties compared to intact attachments. However, the mechanical properties of the two defect groups were not significantly different from each other after 8-weeks of healing and significantly improved compared to no healing but failed to return to intact levels. Local bone volume at the defect site was higher in large compared to small defects on average and increased from 3- to 8-weeks. In contrast, bone quality decreased from 3- to 8-weeks of healing and these changes were not dependent on defect size. Qualitatively, large defects had increased collagen disorganization and neovascularization compared to small defects.

DISCUSSION

In this study, we showed that both large and small defects did not regenerate the mechanical and structural integrity of the intact rat rotator cuff attachment following healing in vivo after 8 weeks of healing.

Multiparity and Aging Impact Chondrogenic and Osteogenic Potential at Symphyseal Enthesis: New Insights into Interpubic Joint Remodeling

Pregnancy and childbirth cause adaptations to the birth canal to allow for delivery and fast recovery. To accommodate delivery through the birth canal, the pubic symphysis undergoes changes that lead to the interpubic ligament (IpL) and enthesis formation in primiparous mice. However, successive deliveries influence joint recovery. We aimed to understand tissue morphology and chondrogenic and osteogenic potential at symphyseal enthesis during pregnancy and postpartum in primiparous and multiparous senescent female mice. Morphological and molecular differences were found at the symphyseal enthesis among the study groups. Despite the apparent incapacity to restore cartilage in multiparous senescent animals, the symphyseal enthesis cells are active. However, these cells have reduced expression of chondrogenic and osteogenic markers and are immersed in densely packed collagen fibers contiguous to the persistent IpL. These findings may indicate alterations of key molecules in the progenitor cell population maintenance of the chondrocytic and osteogenic lineages at the symphyseal enthesis in multiparous senescent animals, possibly compromising the mouse joint histoarchitecture recovery. This sheds light on the distention of the birth canal and the pelvic floor that may play a role in pubic symphysis diastasis (PSD) and pelvic organ prolapse (POP), both in orthopedic and urogynecological practice in women.

Superior capsular reconstruction using hybrid graft for irreparable massive rotator cuff tear

PURPOSE

To evaluate the clinical and radiological outcomes of arthroscopic superior capsular reconstruction (SCR) using hybrid grafts composed of tensor fascia lata autografts and human dermal allografts.

METHODS

This study included 30 patients with chronic irreparable posterosuperior rotator cuff tears (RCTs) who underwent arthroscopic SCR using a hybrid graft composed of tensor fascia lata autograft and human dermal allograft. Clinical outcomes were evaluated using the pain visual analogue scale score, shoulder range of motion, American Shoulder and Elbow Surgeons score, constant score, University of California-Los Angeles score, and simple shoulder test score preoperatively and at least 2 years after surgery. Radiographic analysis included the Hamada classification grade, acromiohumeral distance (AHD), and graft integrity at 2 years after surgery.

RESULTS

All patients exhibited significant clinical improvement in all functional outcome measurements, except external rotation (all P < 0.05). The number of patients who exhibited pseudoparalysis decreased from 7 (23.3%) to 2 (6.7%) postoperatively. Complications were not observed. Radiologically, the mean postoperative AHD increased significantly from 6.9 ± 1.6 cm to 8.8 ± 2.1 cm at 2 years postoperatively (P < 0.001). Twenty five out of the 30 (83.3%) patients showed successful graft healing, and all healing failures occurred on the humeral side. The differences between the healed-graft and failed-graft groups were significantly lower graft thickness (P = 0.001) and smaller AHD (P < 0.001) in the failed-graft group. Every functional outcome scores were not statistically different between healed-graft and failed-graft groups.

CONCLUSIONS

An arthroscopic SCR technique using a hybrid graft consisting of a tensor fascia lata autograft and human dermal allograft showed satisfactory clinical outcomes in patients with irreparable RCTs.

LEVEL OF EVIDENCE

IV.

Effect of Octacalcium Phosphate Crystals on the Osteogenic Differentiation of Tendon Stem/Progenitor Cells In Vitro

Synthetic octacalcium phosphate (OCP) activates bone tissue-related cells, such as osteoblasts, osteoclasts, and vascular endothelial cells. However, the effect of OCP on tendon-related cell activation remains unknown. This study examined the response of rat tendon stem/progenitor cells (TSPCs) to OCP and related calcium phosphate crystals in vitro. TSPCs were cultured with OCP and Ca-deficient hydroxyapatite (CDHA) obtained from the original OCP hydrolysis to assess the activity of alkaline phosphatase (ALP) and the expression of osteogenesis-related genes. Compared with CDHA, the effect of OCP on promoting the osteogenic differentiation of TSPCs was apparent: the ALP activity and mRNA expression of RUNX2, Col1a1, OCN, and OPN were higher in OCP than in CDHA. To estimate the changes in the chemical environment caused by OCP and CDHA, we measured the calcium ion (Ca²⁺) and inorganic phosphate (Pi) ion concentrations and pH values of the TSPCs medium. The results suggest that the difference in the osteogenic differentiation of the TSPCs is related to the ionic environment induced by OCP and CDHA, which could be related to the progress of OCP hydrolysis into CDHA. These results support the previous in vivo observation that OCP has the healing function of rabbit rotator cuff tendon in vivo.

Enhanced healing outcomes in MRL/MpJ mouse tissues conserved in insertion site following surgical repair

BACKGROUND

Surgical repair of supraspinatus tendons (SSTs) has a high failure rate at the insertion site. A significant hurdle to therapeutic development is that effective intrinsic healing mechanisms are unknown. The MRL/MpJ (MRL) mouse exhibits tissue-specific enhanced healing; however, these tissues exhibit disparate properties from the complex SST. The extent of SST healing in the complex environment of the rotator cuff is unknown. We hypothesized that MRL mice would exhibit enhanced restoration of the structurally complex insertion site, resulting in functional improvements.

METHODS

B6 and MRL mice underwent SST detachment and immediate surgical repair. Mice were analyzed for gait assessment after either 2 or 6 weeks and were then killed humanely for immunohistologic analysis.

RESULTS

MRL SSTs demonstrated enhanced recovery of zonal architecture and bone structure compared with B6 SSTs. MRL SSTs exhibited decreased levels of type III collagen at 2 weeks and increased levels of type I procollagen at 6 weeks compared with B6 SSTs. MRL mice experienced initial gait deficits at 2 weeks that had recovered by 6 weeks.

DISCUSSION

The temporal balance of collagen in MRL mice suggests recovery toward naive composition. Initial gait deficits in MRL mice may provide a protective loading environment that is ultimately beneficial. The mechanisms of enhanced healing observed previously in MRL mice may be conserved in the complex SST, providing a platform to interrogate specific aspects of improved healing.

The clinical outcome of physiotherapy after reversed shoulder arthroplasty: a systematic review

PURPOSE

The purpose of this systematic review was to analyze the current literature on the clinical outcomes of physiotherapy (PT) program after reversed total shoulder arthroplasty (rTSA) and to summarize the improvements in this population.

METHODS

A search was performed in four databases (MEDLINE, Embase, PubMed, Google Scholar) from its inception to 30 April 2020. Data were extracted to describe the study design and rehab programs. The quality of evidence was assessed as high, moderate, and low-level according to the Evaluation of Quality of an Intervention Study critical appraisal criteria.

RESULTS

There were 22 eligible studies including two randomized controlled trials, four prospective cohort studies, 10 retrospective reviews, five case-series, and one case-control study, with the sample sizes ranging from 9 to 474 patients followed for 1-10 years. All studies indicated substantial improvement in patients after PT program in terms of functional outcomes and forward flexion.

CONCLUSIONS

High-quality RCTs are required to provide more conclusive results. We identified substantial variation in the post-operative PT programs except for the progressive mobilization strategy and the common management following surgery to increase the soft tissue healing within 4-6 weeks.Implications for RehabilitationThe reverse shoulder arthroplasty (rTSA) has been widely utilized for patients with rotator cuff arthropathy, primary arthritis, and proximal fractures.A successful outcome of rTSA is not only depending on the surgical management, but also depended on physiotherapy (PT) programs.Our systematic review concluded that a 12-week PT program starting with immobilization for 4-6 weeks, followed by 3-4 phases PT exercises including PROM, AAROM, AROM, and strength training was recommended as common management for patients received rTSA.Due to the huge variation in the included studies, the evidence of PT protocol in our study was not sufficient to summarize the better clinical practice suggestions regarding rTSA rehabilitation.

Effectiveness of Bone Marrow-Derived Platelet-Rich Fibrin on Rotator Cuff Healing in a Rabbit Degenerative Model

BACKGROUND

Platelet-rich fibrin (PRF) is a second-generation platelet concentrate. Although peripheral blood-derived PRF (P-PRF) is commonly applied in biological augmentation, there is no report about the therapeutic effect of bone marrow-derived PRF (BM-PRF) for degenerative rotator cuff tears (RCTs).

PURPOSE/HYPOTHESIS

To examine the effects of platelet-rich plasma (PRP), P-PRF, and BM-PRF during rotator cuff repair (RCR) in degenerative RCTs in rabbits. We hypothesized that BM-PRF would accelerate the bone-tendon healing after RCR.

STUDY DESIGN

Controlled laboratory study.

METHODS

Degenerative RCT models were created 2 weeks before beginning the study, and 68 juvenile rabbits were divided into 4 groups: the control, PRP, P-PRF, and BM-PRF groups. RCR without augmentation was done in the control group. PRP was prepared by centrifuging peripheral blood twice using a plastic tube. P-PRF and BM-PRF were prepared by centrifuging peripheral blood and bone marrow, respectively, using a glass tube. Rabbits from PRP, P-PRF, and BM-PRF groups were administered the augmentation in a similar fashion for RCR, between the rotator cuff and the footprint of the humerus. At 4, 8, and 12 weeks, rabbits were euthanized and histologically assessed using hematoxylin and eosin staining, Alcian blue staining, and immunohistochemical staining for type I and III collagen. The sections were also evaluated with immunofluorescence staining of vascular endothelial growth factor (VEGF) at 4 weeks.

RESULTS

The continuity was significantly better in the BM-PRF group at 4 weeks (P < .05). Immunofluorescence staining demonstrated that VEGF-positive stained cells were significantly greater in the BM-PRF group than in the control group (P < .01). The modified tendon maturing score was significantly greater in the BM-PRF group than in the control and PRP groups at 12 weeks (P < .05). There was no significant difference in the modified tendon maturing score of the P-PRF group compared with the control group.

CONCLUSION

The rabbit model of degenerative RCTs demonstrated that RCR combined with BM-PRF enhanced tendon-bone continuity and increased the VEGF-positive cells at 4 weeks and obtained preferable tendon-bone maturation at 12 weeks.

CLINICAL RELEVANCE

RCR augmented with BM-PRF has the potential to improve clinical outcomes for RCTs.

Clinical perspectives for repairing rotator cuff injuries with multi-tissue regenerative approaches

Background

In the musculoskeletal system, bone, tendon, and muscle form highly integrated multi-tissue units such as the rotator cuff complex, which facilitates functional and dynamic movement of the shoulder joint. Understanding the intricate interplay among these tissues within clinical, biological, and engineering contexts is vital for addressing challenging issues in treatment of musculoskeletal disorders and injuries.

Methods

A wide-ranging literature search was performed, and findings related to the socioeconomic impact of rotator cuff tears, the structure-function relationship of rotator cuff bone-tendon-muscle units, pathophysiology of injury, current clinical treatments, recent state-of-the-art advances (stem cells, growth factors, and exosomes) as well as their regulatory approval, and future strategies aimed at engineering bone-tendon-muscle musculoskeletal units are outlined.

Results

Rotator cuff injuries are a significant socioeconomic burden on numerous healthcare systems that may be addressed by treating the rotator cuff as a single complex, given its highly integrated structure-function relationship as well as degenerative pathophysiology and limited healing in bone-tendon-muscle musculoskeletal tissues. Current clinical practices for treating rotator cuff injuries, including the use of commercially available devices and evolving trends in surgical management have benefited patients while advances in application of stem/progenitor cells, growth factors, and exosomes hold clinical potential. However, such efforts do not emphasize targeted regeneration of bone-tendon-muscle units. Strategies aimed at regenerating bone-tendon-muscle units are thus expected to address challenging issues in rotator cuff repair.

Conclusions

The rotator cuff is a highly integrated complex of bone-tendon-muscle units that when injured, has severe consequences for patients and healthcare systems. State-of-the-art clinical treatment as well as recent advances have resulted in improved patient outcome and may be further enhanced by engineering bone-tendon-muscle multi-tissue grafts as a potential strategy for rotator cuff injuries.

Translational Potential of this Article

This review aims to bridge clinical, tissue engineering, and biological aspects of rotator cuff repair and propose a novel therapeutic strategy by targeted regeneration of multi-tissue units. The presentation of these wide-ranging and multi-disciplinary concepts are broadly applicable to regenerative medicine applications for musculoskeletal and non-musculoskeletal tissues.

Evidence analysis on the utilization of platelet-rich plasma as an adjuvant in the repair of rotator cuff tears

BACKGROUND

Platelet-rich plasma has been gaining popularity as an agent for biological augmentation either as the sole treatment modality or as an adjunct to surgical repair. There is substantial discrepancy in the results of the published meta-analyses; and the true efficacy and role of using autologous platelet-rich plasma (PRP) at the time of rotator cuff repair is still ambiguous.

AIM

To performed this systematic overview on the overlapping meta-analyses that analyzed autologous PRP as an adjuvant in the repair of rotator cuff tears and identify the studies which provide the current best evidence on this subject and generate recommendations for the same.

METHODS

We conducted independent and duplicate electronic database searches in PubMed, Web of Science, Scopus, Embase, Cochrane Database of Systematic Reviews, Reference Citation Analysis and the Database of Abstracts of Reviews of Effects on September 8, 2021 to identify meta-analyses that analyzed the efficacy of PRP as an adjuvant in the repair of rotator cuff tears. Methodological quality assessment was made using Oxford Levels of Evidence, AMSTAR scoring and AMSTAR 2 grades. We then utilized the Jadad decision algorithm to identify the study with the highest quality to represent the current best evidence to generate the recommendation.

RESULTS

Twenty meta-analyses fulfilling the eligibility criteria were included. The AMSTAR scores of the included studies varied from 6-10 (mean: 7.9). All the included studies had critically low reliability in their summary of results due to their methodological flaws according to AMSTAR 2 grades. Significant heterogeneity was observed in the reporting of VAS, function outcome scores (long-term UCLA score, ASES score, SST score), operative time and long-term re-tear rates. Recent meta-analyses are more supportive of the role of intra-operative administration of PRPs at the bone-tendon interface in improving the overall healing and re-tear rates, functional outcome and pain. The initial size of the tear and type of repair performed do not seem to affect the benefit of PRPs. Among the different preparations used, leucocyte poor (LP)-PRP possibly offers the greatest benefit as a biological augment in these situations.

CONCLUSION

Based on this systematic overview, we give a level II recommendation that intra-operative use of PRPs at the bone-tendon interface can augment the healing rate, reduce re-tears, enhance functional outcome and mitigate pain in patients undergoing arthroscopic rotator cuff repair. LP-PRP possibly offers the greatest benefit in terms of healing rates, as compared with other platelet preparations.

Arthroscopic Rotator Cuff Repair with Biphasic Interpositional Allograft Augmentation

Rotator cuff repair in the setting of a chronic tear or poor tissue quality presents a surgical challenge because of the high risk of structural failure. Patients with an increased risk of retear may be candidates for enthesis augmentation with a novel, biphasic allograft, composed of a demineralized cancellous matrix with a layer of mineralized bone. This interpositional graft was designed with the intention to promote both soft-tissue and osseous integration into the matrix, thereby conferring greater stability and regeneration of the transitional zone of the rotator cuff enthesis. Here, we describe a technique for a transosseous-equivalent supraspinatus repair with placement of a biphasic interpositional allograft.

Hydroxyapatite gradient on poly (vinyl alcohol) hydrogels surface to mimic calcified cartilage zone for cartilage repair

Poly (vinyl alcohol) (PVA) hydrogels are considered promising artificial articular cartilage. However, the weak attachment between PVA hydrogels and subchondral bone limit its application in the biomedical field. In this article, we present a new method to improve the mineralization of PVA hydrogels, and fabricate PVA hydrogels with continuously graded hydroxyapatite coating. The surface of the hydrogels was modified by dopamine self-polymerization and alendronate conjugation subsequently. Based on these, we used simulated body fluids to mineralize the hydrogels to mimic calcified cartilage zone. The modified surface of the PVA hydrogels showed excellent mineralization ability with continuously graded hydroxyapatite (HA). As the main component of human bones, HA can be chemically bonded body tissue on the interface, showing great biological activity. With the content of HA increasing, the cell adhesion ability of the hydrogels was enhanced, which helped the hydrogels integrate tightly with subchondral bone. These results demonstrate that the modified hydrogels could be promising substitutes for articular cartilage.

Clinical results of the Keck and Kelly Wedge Osteotomy approach in Haglund's deformity: Minimum 3-year follow-up

BACKGROUND AND PURPOSE

The Haglund's deformity, which may be difficult to treat non-surgically, is caused by a prominent bone hump in the posterosuperior region of the calcaneus and may be associated with bursitis and foot pain. Many surgical treatments for resistant Haglund deformities have been described. Here, we evaluate the AOFAS scores, pain and other characteristics of patients undergoing removal of the dorsally based wedge from the posterior calcaneus with the Keck and Kelly procedure.

MATERIALS AND METHODS

The study included 20 patients who had undergone the Keck and Kelly procedure at our center, from 2011 to 2019, and had attended follow-up for at least three years. Analyses were performed retrospectively. Preoperative (immediately before surgery) and postoperative (at last assessment) American Orthopedic Foot and Ankle Society (AOFAS) and visual analog pain scale scores (VAS) were determined, and calcaneal inclination angles were radiologically measured. Additionally, calcaneal pitch angle (CPA), Fowler and Philip angle (FPA), and Bohler angle were recorded.

RESULTS

Fourteen patients were female, and six were male, mean age was 45.8 ± 8.1 years. AOFAS scores were significantly increased, whereas VAS scores were significantly decreased after surgery. Postoperative AOFAS scores were correlated with preoperative VAS, CPA, and FPA values. Preoperative VAS scores were correlated with CPA, FPA, and Bohler angle values. FPA and CPA values were correlated positively.

CONCLUSIONS

It was found that ankle functions improved, and pain levels decreased after Keck and Kelly Wedge Osteotomy was applied for the treatment of Haglund's deformity. CPA and FPA were associated with both pain levels and ankle function. The Keck and Kelly Wedge Osteotomy procedure appears to be a preferable approach for the surgical treatment of Haglund's deformity.

Scaffold-Mediated Immunoengineering as Innovative Strategy for Tendon Regeneration

Tendon injuries are at the frontier of innovative approaches to public health concerns and sectoral policy objectives. Indeed, these injuries remain difficult to manage due to tendon’s poor healing ability ascribable to a hypo-cellularity and low vascularity, leading to the formation of a fibrotic tissue affecting its functionality. Tissue engineering represents a promising solution for the regeneration of damaged tendons with the aim to stimulate tissue regeneration or to produce functional implantable biomaterials. However, any technological advancement must take into consideration the role of the immune system in tissue regeneration and the potential of biomaterial scaffolds to control the immune signaling, creating a pro-regenerative environment. In this context, immunoengineering has emerged as a new discipline, developing innovative strategies for tendon injuries. It aims at designing scaffolds, in combination with engineered bioactive molecules and/or stem cells, able to modulate the interaction between the transplanted biomaterial-scaffold and the host tissue allowing a pro-regenerative immune response, therefore hindering fibrosis occurrence at the injury site and guiding tendon regeneration. Thus, this review is aimed at giving an overview on the role exerted from different tissue engineering actors in leading immunoregeneration by crosstalking with stem and immune cells to generate new paradigms in designing regenerative medicine approaches for tendon injuries.

OUP accepted manuscript

The tendon enthesis plays a critical role in facilitating movement and reducing stress within joints. Partial enthesis injuries heal in a mechanically inferior manner and never achieve healthy tissue function. The cells responsible for tendon-to-bone healing remain incompletely characterized and their origin is unknown. Here, we evaluated the putative role of mouse skeletal stem cells (mSSCs) in the enthesis after partial-injury. We found that mSSCs were present at elevated levels within the enthesis following injury and that these cells downregulated TGFβ signaling pathway elements at both the RNA and protein levels. Exogenous application of TGFβ post-injury led to a reduced mSSC response and impaired healing, whereas treatment with a TGFβ inhibitor (SB43154) resulted in a more robust mSSC response. Collectively, these data suggest that mSSCs may augment tendon-to-bone healing by dampening the effects of TGFβ signaling within the mSSC niche.

The Evolution of Arthroscopic Rotator Cuff Repair

Over the past 30 years, arthroscopic rotator cuff repair (ARCR) has evolved to become the gold standard in treating rotator cuff pathology. As procedural concepts of ARCR continue to improve, it is also continually compared with the open rotator cuff repair as the historical standard of care. This review highlights the evolution of ARCR, including a historical perspective; the anatomic, clinical, and surgical implications of the development of an arthroscopic approach; how arthroscopy improved some of the problems of the open approach; adaptations in techniques and technologies associated with ARCR; future perspectives in orthobiologics as they pertain to ARCR; and lastly, the clinical improvements, or lack of improvements, with all of these adaptations.

Anatomy and histomorphology of the flexor digitorum profundus enthesis: functional implications for tissue engineering and surgery

Background

The enthesis possesses morphological adaptations across the soft-hard tissue junction which are not fully restored during surgical avulsion repairs. This loss of anatomical structure, highly related to function, contributes to poor clinical outcomes. Investigating the native macro- and micro-structure of a specific enthesis can provide functional and biomechanical insights to develop specialised, novel tissue-engineered therapeutic options and potentially improve current surgical treatments for avulsion injuries.

Methods

This study examines the anatomy and histomorphology of the flexor digitorum profundus (FDP) enthesis in 96 fresh-frozen human cadaveric fingers, quantitatively and qualitatively analyzing the shape, size, angle of tendon fibres and histological architecture, and explores differences in sex, finger and distance along the enthesis using linear mixed effects models.

Results

Macroscopically, results showed a consistent trapezoidal insertion shape of 29.29 ± 2.35 mm² mean surface area, but with significant morphometric size differences influenced primarily by the smaller dimensions of the little finger. Microscopically, a fibrocartilaginous enthesis was apparent with a 30.05 ± 0.72^o mean angle of inserting tendon fibres, although regional variation in fibrocartilage and the angle change of tendon fibres before insertion existed.

Conclusions

The implication of these findings on native and specific FDP enthesis function is discussed whilst providing recommendations for optimal FDP enthesis recreation for interfacial tissue engineers and hand surgeons. The study emphasizes the importance of region-specific knowledge whilst also describing methods applicable to assessing any soft tissue insertion.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04922-1.

Comparison of Structural Properties Between Postnatal and Adult Tendon Insertion with FIB/SEM Tomography in Rat

OBJECTIVE

The repaired tendon-bone interface after rotator cuff (RC) repair has been identified as a mechanical weak point, which may contribute to re-tearing. Analyzing the postnatal development of a normal tendon insertion in detail may be useful in helping to promote the regeneration of a normal tendon insertion. We verified the morphological differences between postnatal and adult tendon insertions in terms of the cellular structural properties using FIB/SEM tomography.

MATERIALS AND METHOD

SPostnatal and adult Sprague-Dawley rats were used as a model of tendon insertion. The morphological structure of the insertion was evaluated using hematoxylin and eosin (HE) staining, and the 3D ultrastructure of the cells in the insertion was evaluated using FIB/SEM tomography. Additionally, the volume of the cell bodies, nuclei, and cytoplasm were measured and compared in a quantitative analysis.

RESULTS

On conventional histology, the boundary line between the fibrocartilage and mineralized cartilage was flat in the adult insertions; however, the boundary line between the mineralized cartilage and bone formed deep interdigitations. The morphology of the cells among the collagen bundles in the adult insertions was completely different from those in the postnatal insertions at the 3D ultrastructural level. The cellular structural properties were statistically different between the postnatal and adult insertions.

CONCLUSIONS

In the present study, the morphological differences between postnatal and adult tendon insertion in terms of the ultrastructural cellular properties were clarified. These findings may aid in determining how to regenerate a clinically stable tendon insertion at the tendon-bone interface after RC repair.

Rehabilitation protocols following rotator cuff repair: a meta-analysis of current evidence

BACKGROUND

Rotator cuff tears are a common shoulder pathology with an increasing incidence. The optimum post-operative rehab protocol remains unclear and can consist of either conservative rehabilitation or more aggressive early range-of-motion. Multiple studies have assessed these treatment protocols. This meta-analysis aims to compare post-operative clinical outcomes following either conservative or aggressive rehabilitation post rotator cuff repair.

METHODS

A systematic electronic literature search was undertaken using a number of databases. Eligible studies included randomized control trials published between January 2013 and April 2019 in English with patients having had received rotator cuff repair. Post-operative clinical outcomes considered included shoulder range-of-motion, overall function status (Costant-Murley score) and rates of rotator-cuff re-tear. Studies were evaluated for methodological quality in accordance with the Physiotherapy Evidence Database (PEDro) scale. Summarized pooled statistics were calculated using Review Manager (v5.3) software.

RESULTS

A total of six randomized controlled trials were included. Standardized mean difference (SMD) in shoulder flexion, abduction and external rotation was not statistically significant at either 6 or 12 months post rotator cuff repair. Functional assessment suggests a slight benefit in Constant-Murley Score (SMD = 1.77; 95% CI -3.93, 7.47) in aggressive treatment groups with no significant risk increase for cuff re-tear (RR = 1.22; 95% CI 0.60, 2.47).

CONCLUSION

This meta-analysis suggests there is no clear benefit of either rehabilitation protocol when considering range-of-motion, with a possible benefit in functional outcome at the cost of increased re-tear risk post aggressive rehabilitation. Both protocols have been shown to offer safe reproducible short- and long-term outcomes.

Platelet-Rich Product Supplementation in Rotator Cuff Repair Reduces Retear Rates and Improves Clinical Outcomes: A Meta-analysis of Randomized Controlled Trials

PURPOSE

The purpose of this study was to conduct a comprehensive systematic review and meta-analysis to investigate the clinical and imaging outcomes of all 4 types of platelet-rich therapies (pure platelet-rich plasma [P-PRP], leukocyte and platelet-rich plasma, pure platelet-rich fibrin, and leukocyte and platelet-rich fibrin) in rotator cuff repairs.

METHODS

A systematic literature search was performed to identify rotator cuff tears comparing any of the 4 types of platelet-rich products (PRP) to a control in rotator cuff repair. Data extracted from the studies included retear rates diagnosed with imaging studies, as well as outcome scores such as Constant, American Shoulder and Elbow Surgeons (ASES), University of California Los Angeles (UCLA), Simple Shoulder Test (SST), and visual analog scale (VAS). Meta-analyses compared postoperative outcome scores and retear rates between the control and study groups.

RESULTS

Seventeen studies were included in the meta-analysis. When pooling data from all studies, retear rate for the treatment group was 19.3%, compared to 25.4% for the control group (odds ratio [OR] 0.59, P = .0037). When stratified based on PRP type, only P-PRP resulted in a significant reduction in retear rate (OR 0.26, P = .0005). Overall, treatment with PRP significantly improved Constant scores when compared to controls (mean difference [MD] 2.41, P =.0027), as well as VAS scores (MD -0.12, P = .0014), and SST scores (MD 0.41, P = .0126). There was no significant difference in ASES scores (MD 0.37, P = .7762) or UCLA scores (MD 0.76, P =0.2447) between treatment and controls when pooling data from all studies.

CONCLUSIONS

This analysis demonstrates significant reductions in retear rates when rotator cuff repair is augmented with PRP. P-PRP appears to be the most effective formulation, resulting in significantly improved retear rates and clinical outcome scores when compared with controls.

Use of biologics in rotator cuff disorders: Current concept review

Poor tendon to bone healing following rotator cuff repair has led to the continued interest and investigation into biological augmentation. The biology of tendinopathy is not fully understood and consequently the availability of disease modifying therapeutic targets is limited. A ceiling of benefit has been reached by mechanical optimisation of rotator cuff repair and thus, in order to improve healing rates, a biological solution is required. This review focuses on the strategies to biologically augment rotator cuff disorders with an emphasis on rotator cuff repair. Leucocyte rich platelet rich plasma has been shown to improve healing rates without clinically relevant improvements in outcome scores. Similarly, improved healing rates have also been reported with bone marrow stimulation and in long-term follow-up with bone marrow concentrate. Extracellular matrix (ECM) and synthetic scaffolds can increase healing through mechanical and or biological augmentation. A potential third category of scaffold is bio-inductive and has no mechanical support. Studies involving various scaffolds have shown promising results for augmentation of large to massive tears and is likely to be most beneficial when tendon quality is poor, however level I evidence is limited.

The Relationship of Staged, Bilateral Arthroscopic Primary Rotator Cuff Repair Timing and Postoperative Complications

BACKGROUND

Although previous studies have reported acceptable clinical outcomes after simultaneous, single-stage bilateral and staged bilateral rotator cuff repair (RCR), few studies have been adequately powered to compare postoperative complication rates at various time intervals between procedures.

PURPOSE

To examine the relationship between the timing of bilateral arthroscopic RCR and complications.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

Patients from the Medicare data set within the PearlDiver database who underwent bilateral RCR between 2005 and 2014 were identified. These patients were then stratified by time between surgeries into cohorts: (1) single stage, (2) <3 months, (3) 3 to 6 months, (4) 6 to 9 months, (5) 9 months to 1 year, and (6) 1 to 2 years. Surgical and medical complications of these cohorts were compared with those of a control cohort of patients who underwent bilateral RCR >2 years apart using a regression analysis.

RESULTS

A total of 11,079 patients who underwent bilateral RCR were identified. Patients who underwent single-stage bilateral arthroscopic RCR experienced higher rates of revision RCR (odds ratio [OR], 2.1; P < .0001), reverse total shoulder arthroplasty (RTSA) (OR, 2.47; P < .0001), and postoperative infection (OR, 2.18; P = .007) in addition to higher rates of venous thromboembolism (VTE) (OR, 1.78; P = .031) and emergency department visits (OR, 1.51; P = .002) compared with the control group. Patients who underwent bilateral RCR with a <3-month interval had higher rates of revision surgery (OR, 1.56; P = .003), RTSA (OR, 1.89; P = .002), and lysis of adhesions (OR, 2.31; P < .0001) in addition to increased rates of VTE (OR, 1.92; P = .015) and emergency department visits (OR, 1.62; P < .0001) compared with the control group. There were no differences in any surgical or medical complications when surgeries were staged by ≥3 months compared with controls.

CONCLUSION

Patients with Medicare undergoing single-stage and staged bilateral RCR who had the second repair within 3 months had significantly higher rates of multiple medical and surgical complications compared with patients waiting >2 years between procedures.

Superior mechanical recovery in male and female MRL/MpJ tendons is associated with a unique genetic profile

Tendon ruptures heal by forming a mechanically inferior scar. We have shown that male Murphy Roths large (MRL/MpJ) mice exhibit improved tendon healing, suggesting that they can inform biological mechanisms that lead to effective tendon healing. As sex impacts healing, we assessed the effect of sex on tendon healing in MRL/MpJ and normal healer C57BL/6 (B6) mice and compared the associated biological environment with identify genes that may be integral to the improved healing outcome. We hypothesized that (a) male MRL/MpJ mice will heal with improved mechanical properties compared to females; and (b) that regenerative tendon healing will be associated with decreased fibrotic pathways, decreased inflammation, and increased activity of matrix metalloproteinases (MMPs). A midsubstance punch was introduced, and tendons were harvested after (a) 1 or 7 days for profiling of 84 genes; (b) 7 or 14 days for the assessment of MMP-2 and MMP-9 activity; and (c) 6 weeks for mechanical assessment. MRL/MpJ tendons healed with the better restoration of mechanical properties than B6 tendons. Sex did not affect the mechanical properties of healing B6 or MRL/MpJ tendons. Comparison of the gene expression profiles in the context of the mechanical outcome revealed several differences between MRL/MpJ and B6 tendon healing, including, lower inflammation, an earlier higher expression of TGF-β-related genes that diminish by 7 days, and genes associated with enhanced cell migration in MRL/MpJ in comparison to B6 tendons. We expect that the timecourse and expression levels of these genes in scarless MRL/MpJ tendon healing represent the balanced environment that leads to improved tendon healing.

Neonatal Spinal Cord Transection Decreases Hindlimb Weight-Bearing and Affects Formation of Achilles and Tail Tendons

Mechanical loading may be required for proper tendon formation. However, it is not well understood how tendon formation is impacted by the development of weight-bearing locomotor activity in the neonate. This study assessed tendon mechanical properties, and concomitant changes in weight-bearing locomotion, in neonatal rats subjected to a low thoracic spinal cord transection or a sham surgery at postnatal day (P)1. On P10, spontaneous locomotion was evaluated in spinal cord transected and sham controls to determine impacts on weight-bearing hindlimb movement. The mechanical properties of P10 Achilles tendons (ATs), as representative energy-storing, weight-bearing tendons, and tail tendons (TTs), as representative positional, non-weight-bearing tendons were evaluated. Non- and partial weight-bearing hindlimb activity decreased in spinal cord transected rats compared to sham controls. No spinal cord transected rats showed full weight-bearing locomotion. ATs from spinal cord transected rats had increased elastic modulus, while cross-sectional area trended lower compared to sham rats. TTs from spinal cord transected rats had higher stiffness and cross-sectional area. Collagen structure of ATs and TTs did not appear impacted by surgery condition, and no significant differences were detected in the collagen crimp pattern. Our findings suggest that mechanical loading from weight-bearing locomotor activity during development regulates neonatal AT lateral expansion and maintains tendon compliance, and that TTs may be differentially regulated. The onset and gradual increase of weight-bearing movement in the neonate may provide the mechanical loading needed to direct functional postnatal tendon formation.

Fractional-order viscoelastic model of musculoskeletal tissues: correlation with fractals

Self-similar fractals are widely obtained from biomaterials within the human musculoskeletal system, and their viscoelastic behaviours can be described by fractional-order derivatives. However, existing viscoelastic models neglect the internal correlation between the fractal structure of biomaterials and their fractional-order temporal responses. We further expanded the fractal hyper-cell (FHC) viscoelasticity theory to investigate this spatio-temporal correlation. The FHC element was first compared with other material elements and spring–dashpot viscoelastic models, thereby highlighting its discrete and fractal nature. To demonstrate the utility of an FHC, tree-like, ladder-like and triangle-like FHCs were abstracted from human cartilage, tendons and muscle cross-sections, respectively. The duality and symmetry of the FHC element were further discussed, where operating the duality transformation generated new types of FHC elements, and the symmetry breaking of an FHC altered its fractional-order viscoelastic responses. Thus, the correlations between the staggering patterns of FHCs and their rheological power-law orders were established, and the viscoelastic behaviour of the multi-level FHC elements fitted well in stress relaxation experiments at both the macro- and nano-levels of the tendon hierarchy. The FHC element provides a theoretical basis for understanding the connections between structural degeneration of bio-tissues during ageing or disease and their functional changes.

Augmenting Tendon-to-Bone Repair with Functionally Graded Scaffolds

Tendon-to-bone repair often fails because the functionally graded attachment is not regenerated during the healing process. Biomimetic scaffolds that recapitulate the unique features of the native tendon-to-bone attachment hold great promise for enhancing the healing process. Among various types of scaffolds that are developed and evaluated for tendon-to-bone repair, those with gradations (in either a stratified or a continuous fashion) in composition, structure, mechanical properties, and cell phenotype have gained the most attention. In this progress report, the recent efforts in the rational design and fabrication of functionally graded scaffolds based upon electrospun nanofiber mats and inverse opal structures, as well as the evaluation of their applications in augmenting tendon-to-bone repair, are reviewed. This report concludes with perspectives on the necessary future steps for clinical translation of the scaffolds.

The biomechanics of the rotator cuff in health and disease - A narrative review

The rotator cuff has an important role in the stability and function of the glenohumeral joint. It is a complex anatomic structure commonly affected by injury such as tendinopathy and cuff tears. The rotator cuff helps to provide a stabilising effect to the shoulder joint by compressing the humeral head against the glenoid cavity via the concavity compression mechanism. To appreciate the function of the cuff it is imperative to understand the normal biomechanics of the cuff as well as the mechanisms involved in the pathogenesis of cuff disease. The shoulder joint offers a wide range of motion due to the variety of rotational moments the cuff muscles are able to provide. In order for the joint to remain stable, the cuff creates a force couple around the glenohumeral joint with coordinated activation of adjacent muscles, which work together to contain the otherwise intrinsically unstable glenohumeral joint and prevent proximal migration of the humerus. Once this muscular balance is lost, increased translations or subluxation of the humeral head may result, leading to changes in the magnitude and direction of the joint reaction forces at the glenohumeral joint. These mechanical changes may then result in a number of clinical presentations of shoulder dysfunction, disease and pain. This narrative review aims to highlight the importance of functional rotator cuff biomechanics whilst assessing the kinetics and kinematics of the shoulder joint, as well as exploring the various factors involved in cuff disease.

Rehabilitation Protocols for Superior Capsular Reconstruction Are Variable: A Systematic Review

Purpose

To screen manuscripts that discuss rehabilitation protocols for patients who underwent superior capsular reconstruction (SCR) to elucidate whether a standard rehabilitation algorithm exists for SCR.

Methods

A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta Analyses (i.e., PRISMA) guidelines. PubMed (MEDLINE) and Embase were searched using pertinent Boolean operation terms “superior capsular reconstruction” and “rotator cuff repair rehabilitation,” and articles that included rehabilitation protocols following superior capsular reconstruction surgery were reviewed. Two independent reviewers performed the search and quality assessment.

Results

A total of 549 articles were yielded after our database search. Fourteen studies fulfilled our inclusion criteria and were included in the review. Study designs included 9 editorials, 3 case series, and 2 case reports. Each study included in this review used a unique rehabilitation algorithm that posed significant variability between the protocols. Four phases were identified to summarize each protocol and were used as a basis of discussion—sling versus brace time (3-6 weeks for comfort/removal vs complete immobilization), passive range of motion (immediately after surgery to initiation at 6 weeks), active range of motion (4-8 weeks), and strengthening/return to full activity (12-52 weeks). Initiation of rehabilitation, length of time spent in each phase, types of exercises, and overarching goals for return to function were significantly variable and were decided upon by the surgeon based on current massive rotator cuff repair protocols. Presently, there is no standard rehabilitation protocol for SCR.

Conclusions

SCR is a relatively new procedure that is gaining rapid popularity with promising outcomes. Based on our review, there is no standard rehabilitation protocol in place; thus, it is not possible to recommend an evidence-based rehabilitation protocol following SCR at this time.

Level of Evidence

Level V, systematic review of Level IV and V studies.

Nanofiber Scaffolds by Electrospinning for Rotator Cuff Tissue Engineering

Rotator cuff tears continue to be at risk of retear or failure to heal after surgical repair, despite the use of various surgical techniques, which stimulate development of novel scaffolding strategies. They should be able to address the known causes of failure after the conventional rotator cuff repair: (1) failure to reproduce the normal tendon healing process, (2) resultant failure to reproduce four zones of the enthesis, and (3) failure to attain sufficient mechanical strength after repair. Nanofiber scaffolds are suited for this application because they can be engineered to mimic the ultrastructure and properties of the native rotator cuff tendon. Among various methods for tissue-engineered nanofibers, electrospinning has recently been highlighted in the rotator cuff field. Electrospinning can create fibrous and porous structures that resemble natural tendon's extracellular matrix. Other advantages include the ability to create relatively large surface-to-volume ratios, the ability to control fiber size from the micro to the nano scale, and the flexibility of material choices. In this review, we will discuss the anatomical and mechanical features of the rotator cuff tendon, their potential impacts on improper healing after repair, and the current knowledge of the use of electrospinning for rotator cuff tissue engineering.

Outcomes of Surgical Repair Versus Primary Tenodesis for Proximal Rectus Femoris Avulsion Injuries in Professional Athletes

BACKGROUND

Surgical repair of proximal rectus femoris avulsion injuries is associated with prolonged periods of rehabilitation and highly variable risk of injury recurrence. Surgical tenodesis of these injuries is often reserved for recurrent injuries or revision surgery. To our knowledge, the outcomes of proximal rectus femoris avulsion injuries treated with surgical repair versus primary tenodesis have not been previously reported.

HYPOTHESIS

Primary tenodesis of proximal rectus femoris avulsion injuries is associated with reduced risk of injury recurrence as compared with surgical repair.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

This study included 25 patients (22 male and 3 female) who underwent surgical repair versus 30 patients (26 male and 4 female) who received primary tenodesis for proximal rectus femoris avulsion injuries. Predefined outcomes were recorded at regular intervals after surgery. Mean follow-up time was 27.9 months (range, 24.0-31.7 months) from date of surgery.

RESULTS

All patients returned to their preinjury levels of sporting activity. Primary tenodesis was associated with earlier return to preinjury level of sporting function as compared with surgical repair (mean ± SD, 12.4 ± 1.6 vs 15.8 ± 2.2 weeks; P < .001) and reduced risk of recurrence (0% vs 16%; P < .001). At 1-year follow-up, there was no difference in surgical repair versus primary tenodesis relating to patient satisfaction scores (12 very satisfied and 13 satisfied vs 16 very satisfied and 14 satisfied; P = .70), isometric quadriceps strength (95.6% ± 2.8% vs 95.2% ± 6.3%; P = .31), Tegner scores (median [interquartile range], 9 [8-9] vs 9 [8-9]; P = .54), and lower extremity functional scores (73 [72-76] vs 74 [72-75]; P = .41). High patient satisfaction, quadriceps muscle strength, and functional outcome scores were maintained and remained comparable between treatment groups at 2-year follow-up.

CONCLUSION

Primary tenodesis was associated with reduced time for return to preinjury level of sporting function and decreased risk of injury recurrence when compared with surgical repair for proximal rectus femoris avulsion injuries. There were no differences in patient satisfaction, functional outcome scores, and quadriceps muscle strength between the treatment groups at 1- and 2-year follow-up.

Reconstruction of large chronic rotator cuff tear can benefit from the bone-tendon composite autograft to restore the native bone-tendon interface

Purpose

We designed a paired controlled study to investigate the advantages of using bone–tendon composite autograft to reconstruct chronic rotator cuff tear compared with primary repair and provide some evidence to use the bone–tendon composite autograft.

Method

Thirty-eight Sprague–Dawley rats were used. The native bone–tendon junctions of supraspinatus and Achilles tendon insertion from two rats were harvested for gross and histological observation. Another thirty-six rats had bilateral supraspinatus tenotomy from the great tuberosity. Three weeks later, primary repair (simple tendon pullout direct repair to bone) was performed on one side and the other side was reconstructed using an Achilles–calcaneus composite autograft from the ipsilateral leg. Nine rats were sacrificed for biomechanical testing and another three were sacrificed for histological evaluation at 3, 6, and 9 weeks after surgery, respectively.

Results

The Achilles–calcaneus composite autograft group showed significantly better biomechanical characteristics at 3 and 6 weeks in terms of maximum load and stiffness. Tissue histology demonstrated an organised extracellular matrix, a clear tidemark, and distinct fibrocartilage layers in the composite graft group, similar to those of the native bone–tendon interface. Additionally, clear bone-to-bone healing and tendon-to-tendon healing were observed. By contrast, the conventional primary repair could not regenerate the structure of the native bone–tendon interface.

Conclusions

Bone–tendon autograft for chronic rotator cuff reconstruction is superior to the primary repair regarding biomechanical property and histological structure. Our study may provide some evidence in support of the reconstruction of a chronic rotator cuff tear using bone–tendon composite autografts in clinical practice.

The Translational potential of this article

The current study finds the bone-tendon autograft can restore the normal bone-tendon interface, which can not regenerate after repair and is the key factor affecting re-tear. The bone-tendon autografts from our body can be the candidates for rotator cuff tear reconstruction especially the large to massive rotator cuff tear in the future to reduce the re-tear after rotator cuff tear.

Shoulder biomechanics in normal and selected pathological conditions

The stability of the glenohumeral joint depends on soft tissue stabilizers, bone morphology and dynamic stabilizers such as the rotator cuff and long head of the biceps tendon. Shoulder stabilization techniques include anatomic procedures such as repair of the labrum or restoration of bone loss, but also non-anatomic options such as remplissage or tendon transfers.

Rotator cuff repair should restore the cuff anatomy, reattach the rotator cable and respect the coracoacromial arch whenever possible. Tendon transfer, superior capsular reconstruction or balloon implantation have been proposed for irreparable lesions.

Shoulder rehabilitation should focus on restoring balanced glenohumeral and scapular force couples in order to avoid an upward migration of the humeral head and secondary cuff impingement. The primary goal of cuff repair is to be as anatomic as possible and to create a biomechanically favourable environment for tendon healing.

Cite this article: EFORT Open Rev 2020;5:508-518. DOI: 10.1302/2058-5241.5.200006

Clinical Outcomes of the Central Third Patellar Tendon Versus Four-strand Hamstring Tendon Autograft Used for Anterior Cruciate Ligament Reconstruction: A Systematic Review and Subgroup Meta-analysis of Randomized Controlled Trials

BACKGROUND

The most frequently used auto-grafts for ACL reconstruction (ACLR) are bone-patellar tendon-bone (BPTB) and four-strand hamstring tendon (4S-HT), but significant controversy exists about which graft is better. This study aimed to compare the knee outcomes following ACLR with BPTB and 4S-HT autografts.

METHODS

Subgroup meta-analyses were performed basing on available randomised controlled trials (RCTs) according to different follow-up intervals. 23 RCTs were eligible for inclusion, involving 933 participants in each treatment group.

RESULTS

Only short-term (≤2 years) knee anteroposterior and rotational stability were significantly poorer with 4S-HT when compared to BPTB autograft, as judged by side-to-side difference on knee laxity (WMD=-0.50, 95%CI -0.81~-0.18, p=0.002) and pivot-shift test (OR=0.58, 95%CI 0.39~0.88, p=0.010), respectively. The IKDC objective grade was evident to be in favour of 4S-HT group in mid-term (3-5 years) follow-up (OR=0.63, 95%CI 0.43~0.92, p=0.017). Several donor-site related complications, including anterior knee pain, pain with kneeling and extension deficit, were more frequent in BPTB autograft group, while lower short-term iskinetic peak flexion torques both at 60°/S (WMD=8.93, 95%CI 7.88~9.99, p<0.001) and 240°/S (WMD=11.63, 95%CI 9.92~13.34, p<0.001) were caused by HT harvesting.

CONCLUSION

BPTB was associated with inferior mid- to long-term (>5 years) knee functional outcomes, and increased frequency of donor-site complications. In contrast, only short-term knee laxity was increased for 4S-HT autograft, which is expected to be improved by providing more conservative rehabilitation protocol and aperture fixation methods.

Clinical and sonographic evaluation of Endobutton distal biceps brachii tendon repair: what constitutes normal post-operative appearances?

OBJECTIVE

Distal biceps brachii tendon (DBBT) rupture is an uncommon but functionally significant injury given the loss of supination, flexion strength and pain that often result. Prompt surgical repair is preferred in most patients. Clinicoradiological post-operative follow-up is typically performed to assess DBBT repair integrity and function, frequently using ultrasound, though to date, no studies have described post-operative DBBT repair sonographic appearances. The purpose of this study was to evaluate post-operative DBBT sonographic appearances in the context of Endobutton repair with the following aims:i.Establish typical ultrasound appearances 12 months post-surgeryii.Establish the relationship between ultrasound appearances and clinical/functional outcomes.

MATERIALS AND METHODS

Sixty patients between February 2016 and October 2017 undergoing DBBT repair were prospectively recruited, all undergoing clinical and sonographic assessment 12 months post-surgery. Ultrasound data was collected on tendon integrity, tendon calibre and presence of intratendinous calcification, peritendinous fluid and peritendinous soft tissue/scarring. Clinical data was collected on active range of motion (ROM) (flexion, extension, supination, pronation) and strength (flexion and supination).

RESULTS

A total of 57/60 patients had intact DBBT repairs identified sonographically and clinically at 12 months. DBBT repairs had significantly increased cross-sectional area (mean 260%, 95% CI: 217%, 303%) compared with non-operated DBBT. Ninety-three percent of DBBT repairs were hypoechoic. Thirty percent contained intratendinous calcification. Peritendinous fluid/soft tissue was rarely observed. There was no significant correlation between DBBT calibre and strength/ROM parameters.

CONCLUSION

Normal post-operative sonographic appearances of Endobutton DBBT repair comprise a hypoechoic tendon significantly increased in calibre compared with non-operated tendon ± intratendinous calcification. DBBT repair calibre varies greatly, but is not associated with any significant difference in strength/ROM.

Adhesive-based tendon-to-bone repair: failure modelling and materials selection

Surgical reattachment of tendon to bone is a procedure marked by high failure rates. For example, nearly all rotator cuff repairs performed on elderly patients with massive tears ultimately result in recurrence of tearing. These high failure rates have been attributed to stress concentrations that arise due to the mechanical mismatch between tendon and bone. Although recent studies have identified potential adhesives with mechanical properties tuned to alleviate these stress concentrations, and thereby delay the onset of failure, resistance to the progression of failure has not been studied. Here, we refined the space of adhesive material properties that can improve surgical attachment by considering the fracture process. Using cohesive zone modelling and physiologically relevant values of mode I and mode II adhesive fracture toughnesses, we predicted the maximum displacement and strength at failure of idealized, adhesively bonded tendon-to-bone repairs. Repair failure occurred due to excessive relative displacement of the tendon and bone tissues for strong and compliant adhesives. The failure mechanism shifted to rupture of the entire repair for stiffer adhesives below a critical shear strength. Results identified a narrow range of materials on an Ashby chart that are suitable for adhesive repair of tendon to bone, including a range of elastomers and porous solids.

Retears and Concomitant Functional Impairments After Rotator Cuff Repair: Shoulder Activity as a Risk Factor

BACKGROUND

Most patients return successfully to shoulder involving sports or activity after rotator cuff repairs. It has not been decided yet whether postoperative participation in shoulder activity adds to the risk of retear.

PURPOSE/HYPOTHESIS

The purpose was to verify whether patients who participate in shoulder activities after rotator cuff repair have a higher risk of structural failure than nonactive patients and to investigate the relationship between postoperative shoulder function and tendon integrity in active and nonactive patients. The hypotheses were that (1) active patients have a higher retear rate than nonactive patients and (2) structural failure is associated with worse functional outcomes in active patients.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A cohort study was performed using 145 patients who underwent arthroscopic rotator cuff repair from 2015 to 2017. Functional assessments and magnetic resonance imaging were performed at least 24 months postoperatively. Shoulder activities since 6 months after surgery were rated in 4 categories (sports, job, activities of daily life, and weight of general lifting) as sedentary, light, moderate, or strenuous. The activity level of each patient was defined by the highest rated category. Patients who were involved in light, moderate, and strenuous activity were identified as active for the present study, and the rest were defined as sedentary. The proportion of retears between groups and the functional conditions between retorn and intact tendons were compared.

RESULTS

A total of 48 patients were enrolled in the active group, and 97 were enrolled in the sedentary group. The active group demonstrated a significantly higher retear rate than the sedentary group (27.1% vs 11.3%, respectively; P = .016; risk ratio, 2.39 [95% CI, 1.16-4.93]). In the active group, patients with retears showed higher visual analog scale scores for pain, decreased abduction strength, and lower shoulder functional scores (American Shoulder and Elbow Surgeons score, Fudan University Shoulder Score, and Constant-Murley score) than those with healed tendons, whereas in the sedentary group, functional outcomes were generally similar across patients with and without retears.

CONCLUSION

Shoulder activity after the early postoperative period was associated with a high risk of retears in patients who underwent rotator cuff repair. A correlation between inhibited function and structural failure was detected but only in active patients, while sedentary patients with retears retained functional improvements similar to those with intact tendons.

lncRNA-H19/miR-29a axis affected the viability and apoptosis of keloid fibroblasts through acting upon COL1A1 signaling

This study was intended to clarify the potential of applying the long-chain noncoding RNA H19/miR-29a axis in keloid treatment by elucidating its correlation with the activity of fibroblasts. In this study, 80 keloid tissues, 63 normal fibrous tissues, and 91 normal skin tissues were collected in advance, and concurrently, fibroblasts separated from the tissues were cultured. Besides this, the si-H19, pcDNA3.1-H19, miR-29a mimic, and miR-29a inhibitor were transfected to keloid fibroblasts, whose proliferation, apoptosis, and metastasis were appraised by employing the colony formation assay, flow cytometry, and transwell assay. In addition, the luciferase reporter gene assay was carried out to determine whether targeted regulation was present between H19 and miR-29a, as well as between miR-29a and COL1A1. The study results demonstrated that keloid tissues and fibroblasts exhibited observably upregulated H19 expression and downregulated miR-29a expression, relative to normal skin tissues and fibroblasts (P < .05). Also observed was a negative correlation between H19 expression and miR-29a expression among the gathered keloid tissues (r_s  = -.267, P = .017). Furthermore, in vitro transfection of pcDNA3.1-H19 or miR-29a inhibitor could intensify viability, proliferation, migration, and invasion of the fibroblasts (P < .05), while silencing of H19 and overexpression of miR-29a hindered both metastasis and multiplication of the fibroblasts significantly (P < .05). In addition, H19 was capable of altering miR-29a expression within fibroblasts by directly sponging it, and overexpression of COL1A1 could deter the impact of miR-29a on viability, proliferation, migration, and invasion of fibroblasts (P < .05). In conclusion, H19 might facilitate proliferation and metastasis of fibroblasts by modifying downstream miR-29a and COL1A1, which was expected to allow for development of keloid-targeted treatments.

Biphasic Hydrogels Integrating Mineralized and Anisotropic Features for Interfacial Tissue Engineering

The innate graded structural and compositional profile of musculoskeletal tissue interfaces is disrupted and replaced by fibrotic tissue in the context of disease and degeneration. Tissue engineering strategies focused on the restoration of the transitional complexity found in those junctions present special relevance for regenerative medicine. Herein, we developed a gelatin-based multiphasic hydrogel system, where sections with distinct composition and microstructure were integrated in a single unit. In each phase, hydroxyapatite particles or cellulose nanocrystals (CNC) were incorporated into an enzymatically cross-linked gelatin network to mimic bone or tendon tissue, respectively. Stiffer hydrogels were produced with the incorporation of mineralized particles, and magnetic alignment of CNC resulted in anisotropic structure formation. The evaluation of the biological commitment with human adipose-derived stem cells toward the tendon-to-bone interface revealed an aligned cell growth and higher synthesis and deposition of tenascin in the anisotropic phase, while the activity of the secreted alkaline phosphatase and the expression of osteopontin were induced in the mineralized phase. These results highlight the potential versatility offered by gelatin-transglutaminase enzyme tandem for the development of strategies that mimic the graded, composite, and complex intersections of the connective tissues.

Cell-cell junctions in developing and adult tendons

Tendons connect muscles to bones to transfer the forces necessary for movement. Cell-cell junction proteins, cadherins and connexins, may play a role in tendon development and injury. In this review, we begin by highlighting current understanding of how cell-cell junctions may regulate embryonic tendon development and differentiation. We then examine cell-cell junctions in postnatal tendon, before summarizing the role of cadherins and connexins in adult tendons. More information exists regarding the role of cell-cell junctions in the formation and homeostasis of other musculoskeletal tissues, namely cartilage and bone. Therefore, to inform future tendon studies, we include a brief survey of cadherins and connexins in chondrogenesis and osteogenesis, and summarize how cell-cell junctions are involved in some musculoskeletal tissue pathologies. An enhanced understanding of how cell-cell junctions participate in tendon development, maintenance, and disease will benefit future regenerative strategies.

Traumatic injury of the knee extensor mechanism in skeletally immature patients: Outcome and classification

BACKGROUND

The literature is limited on the etiology and outcome of acute traumatic knee extensor mechanism injuries in skeletally immature patients with lack of a reliable classification system.

METHODS

Data on patients who sustained an acute traumatic injury of the knee extensor mechanism were reviewed with a minimum of 12-month follow-up. Functional outcome was evaluated regarding knee active range of motion. Functional outcome was described using the Knee Society Score (KSS). Data were expressed as mean ± standard deviation.

RESULTS

Seventy-two patients with 74 knee extensor mechanism injuries were identified. The age at the time of injury was 13.9 ± 1.9 years. They included 59 injuries with tibial tubercle avulsion fracture, six injuries with patellar tendon avulsion without bone injury, six injuries with combined patellar tendon avulsion with tibial tubercle fracture, two injuries with sleeve fracture, and one injury with quadriceps tendon avulsion. According to our classification, type IB1 injury was the commonest injury (79.7%). The time to return to sports was 5.23 ± 2.98 months. The flexion was 128.7° ± 13.3°. A mean terminal extension lag of 5.6° was detected in three patients (4.1%). The KSS was 94.8 ± 8.1 and the functional outcome was graded excellent in 64 patients (88.9%), good in seven patients (9.7%), and fair in one patient (1.4%).

CONCLUSIONS

Traumatic injuries of the knee extensor mechanism in skeletally immature patients represent a wide variety of injuries including bony injuries in 82.4% of cases reviewed, tendinous injuries in 9.5%, and both bone and tendinous injuries in 8.1%. Our proposed classification system provides a more precise description of the injury pattern.

Early and Delayed Postoperative Rehabilitation after Arthroscopic Rotator Cuff Repair: A Comparative Study of Clinical Outcomes

BACKGROUND

The duration of immobilization after arthroscopic rotator cuff repair and the optimal time to commence rehabilitation are still the subject of ongoing debates. This study was undertaken to evaluate the functional outcome and rotator cuff healing status after arthroscopic rotator cuff repair by comparing early and delayed rehabilitation.

METHODS

Totally, 76 patients with small, medium, and large sized rotator cuff tears underwent arthroscopic repair using the suture-bridge technique. In early rehabilitation group, 38 patients commenced passive range of motion at postoperative day 2 whereas 38 patients assigned to the delayed rehabilitation group commenced passive range of motion at postoperative week 3. At the end of the study period, clinical and functional evaluations (Constant score, the University of California, Los Angeles [UCLA] shoulder score) were carried out, subsequent to measuring the range of motion, visual analogue scale for pain, and isokinetic dynamometer test. Rotator cuff healing was confirmed by magnetic resonance imaging at least 6 months after surgery.

RESULTS

No significant difference was obtained in range of motion and visual analogue scale between both groups. Functional outcomes showed similar improvements in the Constant score (early: 67.0-88.0; delayed: 66.9-91.0; p<0.001) and the UCLA shoulder score (early: 20.3-32.3; delayed: 20.4-32.4; p<0.001). Furthermore, rotator cuff healing showed no significant differences between the groups (range, 6-15 months; average, 10.4 months).

CONCLUSIONS

Delayed passive rehabilitation does not bring about superior outcomes. Therefore, early rehabilitation would be useful to help patients resume their daily lives.