Biomechanics Of Repair Research Articles

Dermal Allograft Augmentation for Large and Massive Rotator Cuff Tears and Revisions: A Case Series.

Introduction Arthroscopic advancements have notably improved rotator cuff repair, yet the healing of tendons and retear risks still pose significant challenges, especially with massive and large tears. These larger tears have shown a quadruple increase in retear rate when the tear size grows from 1-3 cm. The prevalent cause of failure, particularly in tears with fatty degeneration, is suture tearing.As such, techniques that enhance tendon healing are pivotal due to their correlation with improved functional outcomes. Dermal allograft augmentation (DAA) is one method that has demonstrated improvements in rotator cuff repair biomechanics, as well as the promotion of vascularization and neotendon formation. This study evaluates the efficacy of DAA in the postoperative healing of large and massive rotator cuff tears, assessed through patient-reported outcomes and functional range of motion. Methods This retrospective study reviewed a single surgeon's database, selecting patients who underwent arthroscopic surgery for full-thickness rotator cuff tears measuring at least 3 cm, or those with maximum stage II fatty infiltration of the supraspinatus or infraspinatus muscle on MRI. We used three validated patient-reported outcome (PRO) measures, American Shoulder and Elbow Surgeon Score (ASES), Single Assessment Numeric Evaluation (SANE), and Simple Shoulder Test (SST), alongside a range of motion metrics, external rotation (ER), and forward flexion (FF). These were recorded pre-operatively and, at minimum, one year post-operatively, with a standard student t-test employed for comparative analysis. Results Out of 18 total patients, the average age was 61 years, and 83% were male. The cause of injury was mostly traumatic in nature (n=11), with the remainder being chronic (n=7). All three PROs (n=11) demonstrated a statistically significant increase in score including ASES (p=0.003), SANE (p=0.004), and SST (p=0.039). External rotation also significantly improved pre- to post-operative function (46 vs 58, p=0.049).Three patients (17%) suffered from a retear within three months of their rotator cuff repair. Two patients (11%) required a reverse shoulder arthroplasty within a year. Conclusion Our study demonstrated that DAA in rotator cuff repair yielded notable functional and clinical advancements, with a moderately low retear rate as confirmed by ultrasound. These outcomes suggest that DAA is a promising intervention for large and historically difficult rotator cuff tears, offering significant implications for future treatment protocols.

Transtibial Lateral Meniscal Root Repair Technique to Appose Remnant Root With Torn Body: The Double Compression Knot

Anterior cruciate ligament reconstructions are often performed with associated procedures, most commonly for associated meniscal tears. The lateral meniscal root tear is a commonly associated injury, which increases rotational instability and results in altered tibiofemoral biomechanics. Lateral meniscectomy results in poorer functional and long-term outcomes, making repair vital. The position of the lateral root tear makes its repair technique complicated. Because of the proximity to vessels posteriorly, the all-inside technique is considered potentially unsafe, and current transtibial repair techniques fail to appose the body with the root remnant. In the lineage of Laprade, who proclaimed the use of a transtibial suture for radial tears elsewhere in the knee in order to reduce the shear force, we describe a transtibial technique that optimizes meniscal apposition, theoretically improving the repair biomechanics and is technically easier to perform in comparison to suture hook techniques with one tunnel and one suture.

Biomechanical comparison of suture bridge rotator cuff repair with and without dermal allograft pledgets

BackgroundOne method to augment rotator cuff repair is to pass dermal allograft pledgets along the sutures that bridge from the medial to the lateral row. It remains unclear whether this augmentation method alters repair biomechanics. MethodsThis was a controlled laboratory study. After an a priori power analysis, nine pairs of rotator cuffs underwent double row suture bridge rotator cuff repair, half randomized to augmentation with dermal allograft pledgets passed along the suture bridge sutures. Repairs were then mounted on a material testing system and loaded cyclically 500 cycles to mesure applied force and displacement. Repairs then underwent ultimate failure testing and stiffness, ultimate failure force, and ultimate failure displacement were measured. Paired t-tests were performed to compare between groups. ResultsThere were no differences between groups in construct gapping with cyclic loading after 500 cycles (p = 0.885). There no differences between the augmented and control groups in yield force (103.5 ± 5.0 vs. 101.4 ± 5.9 N, respectively, p=0.183), stiffness (94.2 ± 13.9 vs. 90.9 ± 13.8, p=0.585), or ultimate failure force (255.3 ± 65.8 vs. 285.3 ± 83.2, p=0.315). There were no differences between groups in failure modes, with most specimens failing by cuff tissue tearing within or medial to the construct. ConclusionThe addition of dermal allograft pledgets does not positively or negatively influence the time-zero biomechanical characteristics of double-row suture bridge rotator cuff repair.

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

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. 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. 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. 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. 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.

Knotless Tendon Repair with a Resorbable Barbed Suture: An In-vivo Comparison in the Turkey Foot.

Background: Un-knotted barbed suture constructs are postulated to decrease repair bulk and improve tension loading along the entire repair site resulting in beneficial biomechanical repair properties. Applying this repair technique to tendons has shown good results in ex-vivo experiments previously but thus far no in-vivo study could confirm these. Therefore, this current study was conducted to assess the value of un-knotted barbed suture repairs in the primary repair of flexor tendons in an in-vivo setting. Methods: Two groups of 10 turkeys (Meleagris gallapovos) were used. All turkeys underwent surgical zone II flexor tendon laceration repairs. In group one, tendons were repaired using a traditional four-strand cross-locked cruciate (Adelaide) repair, while in group two, a four-strand knotless barbed suture 3D repair was used. Postoperatively repaired digits were casted in functional position, and animals were left free to mobilise and full weight bear, resembling a high-tension post-op rehabilitation protocol. Surgeries and rehabilitations went uneventful and no major complications were noted. The turkeys were monitored for 6 weeks before the repairs were re-examined and assessed against several outcomes, such as failure rate, repair bulk, range of motion, adhesion formation and biomechanical stability. Results: In this high-tension in-vivo tendon repair experiment, traditionally repaired tendons performed significantly better when comparing absolute failure rates and repair stability after 6 weeks. Nevertheless, the knotless barbed suture repairs that remained intact demonstrated benefits in all other outcome measures, including repair bulk, range of motion, adhesion formation and operating time. Conclusions: Previously demonstrated ex-vivo benefits of flexor tendon repairs with resorbable barbed sutures may not be applicable in an in-vivo setting due to significant difference in repair stability and failure rates. Level of Evidence: Level IV (Therapeutic).

Is posterior knee arthroscopy using posterior portals necessary for orthopedic surgeons? The latest evidence on applications and techniques.

Various uses of posterior knee arthroscopy have been shown, including all-inside repair of posterior meniscal lesions, posterior cruciate ligament (PCL) reconstruction or PCL avulsion fixation, extensile posterior knee synovectomy for pigmented villonodular synovitis or synovial chondromatosis, posterior capsular release in the setting of knee flexion contractures, and loose bodies removal. Posterior arthroscopy provides direct access to the posterior meniscal borders for adequate abrasion and fibrous tissue removal. This direct view of the knee posterior structures enables the surgeon to create a stronger biomechanical repair using vertical mattress sutures. During PCL reconstruction, posterior arthroscopy gives the surgeon proper double access to the tibial insertion site, which can result in less acute curve angles and the creation of a more anatomic tibial tunnel. Moreover, it gives the best opportunity to preserve the PCL remnant. Arthroscopic PCL avulsion fixation is more time-consuming with a larger cost burden compared to open approaches, but in the case of other concomitant intra-articular injuries, it may lead to a better chance of a return to pre-injury activities. The high learning curve and overcaution of neuromuscular injury have discouraged surgeons from practicing posterior knee arthroscopy using posterior portals. Evidence for using posterior portals by experienced surgeons suggests fewer complications. The evidence suggests toward learning posterior knee arthroscopy, and this technique must be part of the education about arthroscopy. In today's professional sports world, where the quick and complete return of athletes to their professional activities is irreplaceable, the use of posterior knee arthroscopy is necessary.

No difference in load to failure or stiffness between transosseous tunnels, suture anchors, and cortical buttons for pectoralis major tendon repair: a systematic review & meta-analysis

PurposeSurgical options for pectoralis major tendon tears include primary repair, though there is no consensus as to which constructs are biomechanically superior for repair.MethodsA systematic review was performed by searching PubMed, the Cochrane library, and Embase using PRISMA guidelines to identify studies that analyzed the biomechanical properties of bone tunnels (BT), cortical buttons (CB) and suture anchors (SA) techniques for pectoralis major tendon repair. The search phrase implemented was ‘pectoralis major tendon repair biomechanics’. Studies that did not evaluate biomechanical outcome data, evaluated partial pectoralis major tendon tears, and non-English articles were excluded. Evaluated outcomes included ultimate load to failure (N) and stiffness (N/mm).ResultsSix studies met inclusion criteria, including a total of 124 cadaveric specimens, for pectoralis major tendon repair comparing BT with SA and CB. Pooled analysis from four studies reporting on ultimate load to failure between BT and SA failed to reveal a difference between BT and SA (p = 0.489). Pooled analysis from two studies reporting on stiffness failed to reveal a difference in favor of BT compared to SA (p = 0.705). Pooled analysis from four studies reporting on ultimate load to failure between BT and CB failed to reveal a difference between BT and CB (p = 0.567). Pooled analysis from two studies reporting on stiffness failed to reveal a difference in favor of BT compared to CB (p = 0.701).ConclusionsThere was no difference in load to failure or stiffness when using BT, CB, or SA in pectoralis major tendon repairs. This review reveals that clinical outcomes may better inform which fixation construct to implement in pectoralis major tendon repairs.Level of evidenceI.

A biomechanical comparison between transosseous cruciate sutures and suture anchors for triceps tendon repair: a systematic review and meta-analysis

Background: The most common surgical option for acute triceps tendon tears is primary repair. There is no consensus as to which fixation construct is biomechanically superior. The purpose of this study was to evaluate the biomechanical properties of transosseous cruciate (TC) versus suture anchors (SA) for triceps tendon repair. Methods: A systematic review was performed by searching PubMed, the Cochrane library, and Embase using Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines to identify studies that analyzed the biomechanical properties of TC and SA techniques for triceps tendon repair. The search phrase implemented was “triceps tendon repair biomechanics.” Evaluated outcomes included medial displacement, lateral displacement, and ultimate load to failure. Results: Four studies met inclusion criteria, including 74 cadaveric specimens (TC: 37, SA: 37), for triceps tendon repair comparing a transosseous technique with TC to SA fixation. Pooled analysis from four studies reporting on medial and lateral displacement revealed a statistically significant difference between TC and SA (P=0.048 and 0.006). Pooled analysis from three studies reporting on ultimate load to failure revealed a statistically significant difference in favor of SA compared to TC (P=0.035). Conclusions: Biomechanical testing of SA for triceps tendon repair is associated with higher ultimate load to failure and lower medial and lateral displacement when under load following repair. The findings of this biomechanical meta-analyses should be considered along with clinical outcome data when surgeons make a decision regarding triceps tendon repair techniques. Level of Evidence: Level II

Hybrid Knot and Knotless Suture Anchor Repair for Patellar Tendon Rupture

Background: Patellar tendon ruptures are the third-most common injury involving the knee extensor mechanism. They typically occur in men under 40 years old as a result of eccentric quadriceps contraction while the knee is flexed and the foot is planted.1 The optimal treatment is surgical repair within 2 weeks of injury to prevent scar formation, degeneration, and loss of tendon excursion. Indications: Operative management is generally indicated for patellar tendon ruptures. In this case, a physically active, healthy 24-year-old man presented with acute pain, extensor lag, and patella alta related to a basketball injury. He was diagnosed with acute patellar tendon rupture/extensor mechanism disruption and indicated for surgery. Technique description: We describe a technique for primary patellar tendon repair which uses both knot-based and knotless suture anchor fixation. Using a pulley effect, sutures in the inferior patellar anchors are used to reduce and repair the patellar tendon back to its bony origin. Patellar anchor-based tapes and a suprapatellar traction suture are affixed with knotless anchors to the proximal tibia to reinforce the repair. Anchor-based suture limbs are used to repair the medial and lateral retinacula. Results: The senior authors’ experience with this technique has been excellent restoration of extensor mechanism function, with rehabilitation permitting early range of motion and no major complications or failures. This patient returned to unassisted activities of daily living between 8 and 12 weeks and had returned to gym workouts and recreational sports at 12 months. Discussion/conclusion: Biomechanical studies have demonstrated that compared with transosseous repair, suture anchor repair decreases gap formation and improves ultimate load to failure. Advantages of suture anchor repair include smaller incision, less tissue dissection, shorter operative time, and improved repair biomechanics. Our technique follows a principle of tendon repair using a high number of suture and tape limbs to span the repair. In addition, this technique incorporates a “double row” of suture anchors and spans the primary repair with a suture and tape “internal brace.” The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Morphological Structure Analysis of Taxus Based on Plant Biomechanics

Although biomechanics has been developing for years, the research breakthrough of biomechanics at this stage is mainly to solve life and health problems (e.g., vascular mechanics, molecular cell biomechanics, as well as tissue repair biomechanics). There is not much research on plants. This study mainly considers some cutting-edge biomechanical studies in plants in recent years, focusing on Taxus Linn, combined with the observed morphological characteristics of Taxus, and analyzes the physiological structure of Taxus from three aspects of roots, stems and leaves. The morphological development of Taxus root is correlated with the mechanical action of wind and soil, and adapts and evolves with the environment. The stress and strain of stem cells have an effect on the cell morphology and then the appearance and function of stem. The transportation of leaf can be simulated by hydrodynamic model, and relevant calculations are used to explain the length and structure of Taxus leaf. Understanding Taxus from the perspective of plant biomechanics takes on a critical significance in studying the growth mode of Taxus, its relationship with the environment and biological metabolism. According to the above analyses and results, there will also be traces of how to protect wild populations, how to breed scientifically, and how to maximize the extraction of plant metabolites.

Ex Vivo Model of Ischemic Mitral Regurgitation and Analysis of Adjunctive Papillary Muscle Repair.

Ischemic mitral regurgitation (IMR) is particularly challenging to repair with lasting durability due to the complex valvular and subvalvular pathologies resulting from left ventricular dysfunction. Ex vivo simulation is uniquely suited to quantitatively analyze the repair biomechanics, but advancements are needed to model the nuanced IMR disease state. Here we present a novel IMR model featuring a dilation device with precise dilatation control that preserves annular elasticity to enable accurate ex vivo analysis of surgical repair. Coupled with augmented papillary muscle head positioning, the enhanced heart simulator system successfully modeled IMR pre- and post-surgical intervention and enabled the analysis of adjunctive subvalvular papillary muscle repair to alleviate regurgitation recurrence. The model resulted in an increase in regurgitant fraction: 11.6 ± 1.7% to 36.1 ± 4.4% (p<0.001). Adjunctive papillary muscle head fusion was analyzed relative to a simple restrictive ring annuloplasty repair and, while both repairs successfully eliminated regurgitation initially, the addition of the adjunctive subvalvular repair reduced regurgitation recurrence: 30.4 ± 5.7% vs. 12.5 ± 2.6% (p=0.002). Ultimately, this system demonstrates the success of adjunctive papillary muscle head fusion in repairing IMR as well as provides a platform to optimize surgical techniques for increased repair durability.

Adipose-Derived Mesenchymal Stem Cell Treatments and Available Formulations.

The use of human adipose-derived mesenchymal stem cells (ADSCs) has gained attention due to its potential to expedite healing and the ease of harvesting; however, clinical evidence is limited, and questions concerning optimal method of delivery and long-term outcomes remain unanswered. Administration of ADSCs in animal models has been reported to aid in improved healing benefits with enhanced repair biomechanics, superior gross histological appearance of injury sites, and higher concentrations of growth factors associated with healing compared to controls. Recently, an increasing body of research has sought to examine the effects of ADSCs in humans. Several available processing techniques and formulations for ADSCs exist with evidence to suggest benefits with the use of ADSCs, but the superiority of any one method is not clear. Evidence from the most recent clinical studies available demonstrates promising outcomes following treatment of select musculoskeletal pathologies with ADSCs despite reporting variability among ADSCs harvesting and processing; these include (1) healing benefits and pain improvement for rotator cuff and Achilles tendinopathies, (2) improvements in pain and function in those with knee and hip osteoarthritis, and (3) improved cartilage regeneration for osteochondral focal defects of the knee and talus. The limitation to most of this literature is the use of other therapeutic biologics in combination with ADSCs. Additionally, many studies lack control groups, making establishment of causation inappropriate. It is imperative to perform higher-quality studies using consistent, predictable control populations and to standardize formulations of ADSCs in these trials.

The biomechanics of subscapularis repair in reverse shoulder arthroplasty: The effect of lateralization and insertion site.

Functional outcomes of subscapularis (SSc) repair following reverse shoulder arthroplasty (RSA) remains controversial. SSc repair in combination with glenosphere lateralization was reported to yield worse clinical outcomes compared with the non-lateralized glenosphere. The aim of this biomechanical study was to investigate how glenosphere lateralization and different re-insertion sites can affect the biomechanics of the SSc after RSA. Nine patient-specific RSA shoulder models were created from patients' computed tomography scans. Moment arms and SSc length were calculated for abduction, forward flexion, and internal rotation in 20° and 90° abduction for three configurations of glenosphere lateralization (standard/+0, +5, and +10 mm) and three SSc repair sites (native, superior, and inferior) and compared with the native shoulder. When compared with the native shoulder, RSA resulted in large adducting SSc moment arms that were antagonistic to the deltoid. Glenosphere lateralization had no effect on SSc moment arms in any motion. However, lateralization increased SSc tension beyond its anatomic length for +5 and +10 mm of lateralization when attached to its native insertion. A superior SSc repair site created the least adductive moment arm as well as the least amount of SSc lengthening. Increased glenosphere lateralization showed a significant increase in the SSc length, which in combination with its adductive moment arm can be antagonistic to deltoid function. However, a superior SSc repair site may help reduce the adductive SSc moment arm and allow for reduced tension on the repair as its length in that location is less than that of the native SSc. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:888-894, 2020.

Metal trabecular bone reconstruction system better improves clinical efficacy and biomechanical repair of osteonecrosis of the femoral head than free vascularized fibular graft: A case-control study.

In this study, we aim to compare and analyze the biomechanical repair and clinical efficacy of osteonecrosis of the femoral head (ONFH) with the use of metal trabecular bone reconstruction system and free vascularized fibular graft. The study enrolled 66 adult patients from medical records of nontraumatic ARCO 2A-3B stage ONFH. A simple ONFH model without surgical treatment was established in 13 cases, 29 cases were treated with metal trabecular bone reconstruction system, and 24 cases were treated with free vascularized fibular graft. Computer-recognized and extracted femur outlines were imported, and three-dimensional reconstructions were performed. The stress concentration and stress peak value were analyzed, and the Harris score, visual analog scale pain score, and operation status of the above patients were compared. Finally, quality of life assessment was performed using SF-36 scale. Metal trabecular bone reconstruction system provided less operation time, blood loss, and the total length of postoperative hospital stay than free vascularized fibular graft. Metal trabecular bone reconstruction system promoted bone reconstruction, increased bone mineral density and Harris score. The total clinical effective rate of young patients (20-40 years) was higher than that of older patients (41-60 years). Metal trabecular bone reconstruction system provided higher physical component summary, mental component summary, and role/social component summary than free vascularized fibular graft. This study demonstrates that both metal trabecular bone reconstruction system and free vascularized fibular graft can prevent or delay the progression of ONFH, while metal trabecular bone reconstruction system is a better choice because of better short-term clinical efficacy.

Bone Fracture Acute Phase Response\u2014A Unifying Theory of Fracture Repair: Clinical and Scientific Implications

Bone fractures create five problems that must be resolved: bleeding, risk of infection, hypoxia, disproportionate strain, and inability to bear weight. There have been enormous advancements in our understanding of the molecular mechanisms that resolve these problems after fractures, and in best clinical practices of repairing fractures. We put forth a modern, comprehensive model of fracture repair that synthesizes the literature on the biology and biomechanics of fracture repair to address the primary problems of fractures. This updated model is a framework for both fracture management and future studies aimed at understanding and treating this complex process. This model is based upon the fracture acute phase response (APR), which encompasses the molecular mechanisms that respond to injury. The APR is divided into sequential stages of “survival” and “repair.” Early in convalescence, during “survival,” bleeding and infection are resolved by collaborative efforts of the hemostatic and inflammatory pathways. Later, in “repair,” avascular and biomechanically insufficient bone is replaced by a variable combination of intramembranous and endochondral ossification. Progression to repair cannot occur until survival has been ensured. A disproportionate APR—either insufficient or exuberant—leads to complications of survival (hemorrhage, thrombosis, systemic inflammatory response syndrome, infection, death) and/or repair (delayed- or non-union). The type of ossification utilized for fracture repair is dependent on the relative amounts of strain and vascularity in the fracture microenvironment, but any failure along this process can disrupt or delay fracture healing and result in a similar non-union. Therefore, incomplete understanding of the principles herein can result in mismanagement of fracture care or application of hardware that interferes with fracture repair. This unifying model of fracture repair not only informs clinicians how their interventions fit within the framework of normal biological healing but also instructs investigators about the critical variables and outputs to assess during a study of fracture repair.

Shoulder biomechanics of RC repair and Instability: A systematic review of cadaveric methodology

BackgroundNumerous biomechanical studies have addressed normal shoulder function and the factors that affect it. While these investigations include a mix of in-vivo clinical reports, ex-vivo cadaveric studies, and computer-based simulations, each has its own strengths and limitations. A robust methodology is essential in cadaveric work but does not always come easily. Precise quantitative measurements are difficult in in-vivo studies, and simulation studies require validation steps. This review focuses on ex-vivo cadaveric studies to emphasize the best research methodologies available to simulate physiologically and clinically relevant shoulder motion. MethodsA PubMed and Web of Science search was conducted in March 2017 (and updated in May 2018) to identify the cadaveric studies focused on the shoulder and its function. The key words for this search included rotator cuff (RC) injuries, RC surgery, and their synonyms. The protocol of the study was registered on PROSPERO and is accessible at CRD42017068873. ResultsThirty one studies consisting of 167 specimens with various biomechanical methods met our inclusion criteria. All studies were level V cadaveric studies. Cadaveric biomechanical models are widely used to study shoulder instability and RC repair. These models are commonly limited to the glenohumeral joint by a fixed scapula, passively and discretely move the humerus, and statically load the RC without regard for the integrity of the glenohumeral capsule. ConclusionAll studies captured in this review evaluated shoulder biomechanics. Recent studies in patients suggest that some assumptions made in this space may not fully characterize motion of the human shoulder. With reproducible scapular positioning, dynamic RC activation, and preservation of glenohumeral capsule integrity, cadaveric studies can facilitate proper validation for simulation models and broaden our understanding of the shoulder environment during motion in healthy and disease states.

How should I fixate the subscapularis in total shoulder arthroplasty? A systematic review of pertinent subscapularis repair biomechanics.

The present study aimed to review the biomechanical outcomes of subscapularis repair techniques during total shoulder arthroplasty (TSA) to assist in clinical decision making. A systematic review of multiple databases was performed by searching PubMed, Scopus, Cochrane Library, Google Scholar, and all databases within EBSCOhost to find biomechanical studies of subscapularis repair techniques in cadaveric models of TSA. Nine studies met the inclusion criteria. In the majority of studies, lesser tuberosity osteotomy (LTO) techniques had greater load to failure and less cyclic displacement compared to subscapularis tenotomy or peel methods. LTO repairs with sutures wrapped around the humeral stem demonstrated superior biomechanical outcomes compared to techniques using only a tension band. In terms of load to failure, the strongest repair of any study was a dual-row fleck LTO using four sutures wrapped around the stem. Several cadaveric studies have shown superior biomechanical outcomes with LTO techniques compared to tenotomy. In the majority of studies, the strongest subscapularis repair technique in terms of biomechanical outcomes is a compression LTO. Using three or more sutures wrapped around the implant and the addition of a tension suture may increase the biomechanical strength of the LTO repair.

Effect of Pulsed Wave Low-Level Laser Therapy on Tibial Complete Osteotomy Model of Fracture Healing With an Intramedullary Fixation.

Background:Fractures pose a major worldwide challenge to public health, causing tremendous disability for the society and families. According to recent studies, many in vivo and in vitro experiments have shown the positive effects of PW LLLT on osseous tissue.Objectives:The aim of this study was to evaluate the outcome of infrared pulsed wave low-level laser therapy (PW LLLT) on the fracture healing process in a complete tibial osteotomy in a rat model, which was stabilized by an intramedullary pin.Materials and Methods:This experimental study was conducted at Shahid Beheshti University of Medical Sciences in Tehran, Iran. We performed complete tibial osteotomies in the right tibias for the population of 15 female rats. The rats were divided randomly into three different groups: I) Control rats with untreated bone defects; II) Rats irradiated by a 0.972 J/cm2 PW LLLT; and III) Rats irradiated by a 1.5 J/cm2 PW LLLT. The right tibias were collected six weeks following the surgery and a three-point bending test was performed to gather results. Immediately after biomechanical examination, the fractured bones were prepared for histological examinations. Slides were examined using stereological method.Results:PW LLLT significantly caused an increase in maximum force (N) of biomechanical repair properties for osteotomized tibias in the first and second laser groups (30.0 ± 15.9 and 32.4 ± 13.8 respectively) compared to the control group (8.6 ± 4.5) LSD test, P = 0.019, P = 0.011 respectively). There was a significant increase in the osteoblast count of the first and second laser groups (0.53 ± 0.06, 0.41 ± 0.06 respectively) compared to control group (0.31 ± 0.04) (LSD test, P = 0001, P = 0.007 respectively).Conclusions:This study confirmed the efficacy of PW LLLT on biomechanical strength, trabecular bone volume, callus volume, and osteoblast number of repairing callus in a complete tibial osteotomy animal model at a relatively late stage of the bone healing process.

Controversial Treatments of Shoulder Injuries

Repair of shoulder injuries is rising and multiple treatment options exist. Multiple factors are involved in satisfactory healing of the rotator cuff including the quality of the tendon and muscle, repair biomechanics, and patient quality. This article discusses patch reinforcement in the repair of rotator cuffs, as well as about biologics that are available for rotator cuff repair, treating fractures with reverse arthroplasty, and indications for hemiarthroplasty and total shoulder replacement.

Arthroscopic Transosseous-Equivalent Rotator Cuff Repair

Rotator cuff repair techniques continue to evolve in an effort to improve repair biomechanics, maximize the biologic environment for tendon healing, and ultimately improve patient outcomes. The arthroscopic transosseous-equivalent technique was developed to replicate the favorable tendon-bone contact area for healing seen in open transosseous tunnel repair. In this technical note and accompanying video, we present our all-arthroscopic transosseous-equivalent rotator cuff repair technique with a focus on technical pearls.