Editorial Commentary: The Difficulties of Assessing Return to Play and Return to Performance After Ulnar Collateral Ligament Reconstruction.

Ulnar collateral ligament (UCL) tears have moved from a career-ending injury to one in which success is almost expected from reconstruction. In reality, however, success from a UCL reconstruction is not guaranteed. As we have attempted to assess the true success rate of UCL reconstructions, we have also learned the difficulties of this assessment. Rates of return to sport after UCL reconstruction vary by level of play, the primary or revision status of the repair, along with the specific surgical techniques performed, the chronicity of the tear, the rehabilitation protocols associated with the surgery, and more. Return to sport is difficult to assess, as high school, collegiate, and even professional careers can be variable and there are no standard definitions of "returning to play." These variables also affect our assessments of performance after UCL reconstruction. Decisions for UCL reconstructions and appropriate counseling of patients regarding the likelihood of success currently remain an individual process.

Editorial Commentary: Utility of Patient-Reported Outcome Threshold Scores to Estimate Patient Satisfaction: 'Let's Ask the Patient!'

The reporting and analysis of patient-reported outcome measures have come a long way. Since the concept of the minimally clinically important difference was first introduced in 1989, threshold scores have grown to include substantial clinical benefit and patient acceptable symptomatic state (PASS). The initial motivation for developing these thresholds was rooted in separating clinical significance from statistical. These thresholds provide insight into the relationship between scores on patient-reported outcome measures (PROM) and patient-reported improvement and satisfaction. It follows that in order to evaluate PROM scores, the best method for deriving the threshold typically uses an anchor-based methodology, i.e., "ask the patient." Specifically, patients are asked how much change they've experienced and whether they consider their current state to be satisfactory. The responses to these questions are compared with the scores on PROMs to find outcome thresholds that best separate patients who reported no improvement from those who reported minimal improvement, substantial improvement, and satisfaction with their current state of health (PASS). The PASS is of particular importance as it speaks to what arguably matters most to patients-a satisfactory state of health. Finally, viewing the PASS from the perspective of variation from study to study rather than as a uniform classifier is needed to make use of the growing number of papers reporting these thresholds. Examining differences in PASS values across papers can provide insight into how well PROM scores reflect patient satisfaction in different settings.

Biologic Adjuvants to Rotator Cuff Repairs Induce Anti-inflammatory Macrophage 2 Polarization and Reduce Inflammatory Macrophage 1 Polarization In Vitro.

PURPOSE: To examine the effect of various biologic adjuvants on the polarization of macrophages in an in vitro model for rotator cuff tears. METHODS: Tissue was harvested from 6 patients undergoing arthroscopic rotator cuff repair. An in vitro model of the supraspinatus and subacromial bursa was created and treated with control, platelet-rich plasma (PRP), autologous activated serum (AAS), or a combination of PRP+AAS. The effect of treatment on macrophage polarization between M1 proinflammatory macrophages or M2 anti-inflammatory macrophages was measured using gene expression, protein expression, flow cytometry, and nitric oxide production. RESULTS: Tendon and bursa treated with PRP, AAS, and PRP+AAS significantly decreased the gene expression of M1 markers interleukin (IL)-12 and tumor necrosis factor-alpha while significantly increasing the expression of M2 markers arginase, IL-10, and transforming growth factor-ß (P < .05) compared with treatment with control. Enzyme-linked immunosorbent assay analysis of protein production demonstrated that, compared with control, coculture treated with PRP, AAS, and PRP+AAS significantly decreased markers of M1-macrophages (IL-6, IL-12, and tumor necrosis factor-alpha) while significantly increasing the expression of markers of M2-macrophages (arginase, IL-10, and transforming growth factor-beta) (P < .05). Flow cytometry analysis of surface markers demonstrated that compared with control, tendon and bursa treated with PRP, AAS, and PRP+AAS significantly decreased markers of M1-macrophages (CD80, CD86, CD64, CD16) while significantly increasing the expression of markers of M2-macrophages (CD163 and CD206) (P < .05). Treatment of the coculture with PRP, AAS, and PRP+AAS consistently demonstrated a decrease in nitric oxide production (P < .05) compared with control. AAS and PRP+AAS demonstrated an increased macrophage shift to M2 compared with PRP alone, whereas there was not as uniform of a shift when comparing PRP+AAS with AAS alone. CONCLUSIONS: In an in vitro model of rotator cuff tears, the treatment of supraspinatus tendon and subacromial bursa with PRP, AAS, and PRP+AAS demonstrated an increase in markers of anti-inflammatory M2-macrophages and a concomitant decrease in markers of proinflammatory M1-macrophages. AAS and PRP+AAS contributed to a large shift to macrophage polarization to the anti-inflammatory M2 compared with PRP. CLINICAL RELEVANCE: The mechanism of biologic adjuvant effects on the rotator cuff remains poorly understood. This study suggests that they may contribute to polarization of macrophages for their proinflammatory (M1) state to the anti-inflammatory (M2) state.

Human Rotator Cuff Tears Reveal an Age-Dependent Increase in Markers of Cellular Senescence and Selective Removal of Senescent Cells With Dasatinib + Quercetin Increases Genetic Expression of COL1A1 In Vitro.

PURPOSE: To quantify cellular senescence in supraspinatus tendon and subacromial bursa of humans with rotator cuff tears and to investigate the in vitro efficacy of the senolytic dasatinib + quercetin (D+Q) to eliminate senescent cells and alter tenogenic differentiation. METHODS: Tissue was harvested from 41 patients (mean age, 62 years) undergoing arthroscopic rotator cuff repairs. In part 1 (n = 35), senescence was quantified using immunohistochemistry and gene expression for senescent cell markers (p16 and p21) and the senescence-associated secretory phenotype (SASP) (interleukin [IL] 6, IL-8, matrix metalloproteinase [MMP] 3, monocyte chemoattractant protein [MCP] 1). Senescence was compared between patients <60 and ≥60 years old. In part 2 (n = 6) , an in vitro model of rotator cuff tears was treated with D+Q or control. D+Q, a chemotherapeutic and plant flavanol, respectively, kill senescent cells. Gene expression analysis assessed the ability of D+Q to kill senescent cells and alter markers of tenogenic differentiation. RESULTS: Part 1 revealed an age-dependent significant increase in the relative expression of p21, IL-6, and IL-8 in tendon and p21, p16, IL-6, IL-8, and MMP-3 in bursa (P < .05). A significant increase was seen in immunohistochemical staining of bursa p21 (P = .028). In part 2, D+Q significantly decreased expression of p21, IL-6, and IL-8 in tendon and p21 and IL-8 in bursa (P < .05). Enzyme-linked immunosorbent assay analysis showed decreased release of the SASP (IL-6, MMP-3, MCP-1; P = .002, P = .024, P < .001, respectively). Tendon (P = .022) and bursa (P = .027) treated with D+Q increased the expression of COL1A1. CONCLUSIONS: While there was an age-dependent increase in markers of cellular senescence, this relationship was not consistently seen across all markers and tissues. Dasatinib + quercetin had moderate efficacy in decreasing senescence in these tissues and increasing COL1A1 expression. CLINICAL RELEVANCE: This study reveals that cellular senescence may be a therapeutic target to alter the biological aging of rotator cuffs and identifies D+Q as a potential therapy.

Elliptical and spherical heads show similar obligate glenohumeral translation during axial rotation in total shoulder arthroplasty.

BACKGROUND: Elliptical shape humeral head prostheses have been recently proposed to reflect a more anatomic shoulder replacement. However, its effect on obligate glenohumeral translation during axial rotation compared to a standard spherical head is still not well understood. The purpose of the study was to compare obligate humeral translation during axial rotation using spherical and elliptical shaped humeral head prostheses. It was hypothesized that the spherical head design would show significantly more obligate translation when compared to the elliptical design. METHODS: Six fresh-frozen cadaveric shoulders were utilized for biomechanical testing of internal (IR) and external (ER) rotation at various levels of abduction (0°, 30°, 45°, 60°) with lines of pull along each of the rotator cuff muscles. Each specimen underwent the following three conditions: (1) native; total shoulder arthroplasty (TSA) using (2) an elliptical and (3) spherical humeral head implant. Obligate translation during IR and ER was quantified using a 3-dimensional digitizer. The radius of curvature of the superoinferior and anteroposterior dimensions of the implants was calculated across each condition. RESULTS: Posterior and inferior translation as well as compound motion of spherical and elliptical heads during ER was similar at all abduction angles (P > 0.05, respectively). Compared to the native humeral head, both implants demonstrated significantly decreased posterior translation at 45° (elliptical: P = 0.003; spherical: P = 0.004) and 60° of abduction (elliptical: P < 0.001; spherical: P < 0.001). During internal rotation at 0° abduction, the spherical head showed significantly more compound motion (P = 0.042) compared to the elliptical head. The spherical implant also demonstrated increased anterior translation and compound motion during internal rotation at 60° abduction (P < 0.001) compared to the resting state. This difference was not significant for the native or elliptical head design at this angle (P > 0.05). CONCLUSION: In the setting of TSA, elliptical and spherical head implants showed similar obligate translation and overall compound motion during axial rotation. A gained understanding of the consequences of implant head shape in TSA may guide future surgical implant choice for better recreation of native shoulder kinematics and potentially improved patient outcomes. LEVEL OF EVIDENCE: Controlled Laboratory Study.

Editorial Commentary: Fascia Lata Allograft for Shoulder Superior Capsular Reconstruction: In the Fight Over Optimal Graft Choice for Irreparable Rotator Cuff Tears, Superior Capsular Reconstruction Proponents May Be Changing Their Gloves.

Optimal treatment of irreparable rotator cuff tears is still debated. Proponents of the superior capsule reconstruction (SCR) have previously used fascia lata autograft and acellular dermal allograft. Interest is growing in using fascia lata allograft as a new graft material. Well-designed biomechanical studies are important to understand the mechanical properties of the superior capsular tissue and fascia lata allograft. Recent biomechanical research shows that fascia lata allograft has similar initial stiffness (over the first 2 mm) and ultimate load compared to the native superior capsule. That said, ultimate load is the load at which a construct fails, whereas the yield point is the load on the stress-strain curve at which a material transitions from elastic to plastic deformation. In the shoulder where the SCR, for example, is going to be repetitively loaded, it is potentially more meaningful to talk about the yield point in order to stay within the elastic range. Using this framework, the yield point for fascia lata allograft is approximately one third the yield point of native capsular tissue. Additionally, "initial" stiffness is not the entire story. At greater loads, fascia lata allograft has higher displacement compared to native tissue. Of importance, fascia lata allograft failed by sutures slowly cutting through the allograft tissue; this may represent a limitation of the construct that could be addressed using stitch configurations resistant to cut through. Fascia lata allograft is a promising solution for SCR. Biomechanical studies require nuanced interpretation, and most of all, do not evaluate clinical healing.

Superior Capsular Reconstruction Partially Restores Native Glenohumeral Joint Loads in a Dynamic Biomechanical Shoulder Model.

PURPOSE: To evaluate the effect of an irreparable posterosuperior rotator cuff tear (PSRCT) on glenohumeral joint loads and to quantify improvement after superior capsular reconstruction (SCR) using an acellular dermal allograft. METHODS: Ten fresh-frozen cadaveric shoulders were tested using a validated dynamic shoulder simulator. A pressure mapping sensor was placed between the humeral head and glenoid surface. Each specimen underwent the following conditions: (1) native, (2) irreparable PSRCT, and (3) SCR using a 3-mm-thick acellular dermal allograft. Glenohumeral abduction angle (gAA) and superior humeral head migration (SM) were measured using 3-dimensional motion-tracking software. Cumulative deltoid force (cDF) and glenohumeral contact mechanics, including glenohumeral contact area and glenohumeral contact pressure (gCP), were assessed at rest, 15°, 30°, 45°, and maximum angle of glenohumeral abduction. RESULTS: The PSRCT resulted in a significant decrease of gAA along with an increase in SM, cDF, and gCP (P < .001, respectively). SCR did not restore native gAA (P < .001); however, SM was significantly reduced (P < .001). Further, SCR significantly reduced deltoid forces at 30° (P = .007) and 45° of abduction (P = .007) when compared with the PSRCT. SCR did not restore native cDF at 30° (P = .015), 45° (P < .001), and maximum angle (P < .001) of glenohumeral abduction. Compared with the PSRCT, SCR resulted in a significant decrease of gCP at 15° (P = .008), 30° (P = .002), and 45° (P = .006). However, SCR did not completely restore native gCP at 45° (P = .038) and maximum abduction angle (P = .014). CONCLUSIONS: In this dynamic shoulder model, SCR only partially restored native glenohumeral joint loads. However, SCR significantly decreased glenohumeral contact pressure, cumulative deltoid forces, and superior migration, while increasing abduction motion, when compared with the posterosuperior rotator cuff tear. CLINICAL RELEVANCE: These observations raise concerns regarding the true joint-preserving potential of SCR for an irreparable posterosuperior rotator cuff tear, along with its ability to delay progression of cuff tear arthropathy and eventual conversion to reverse shoulder arthroplasty.

Is there value in the routine practice of discarding the incision scalpel from the surgical field to prevent deep wound contamination with Cutibacterium acnes? An update.

BACKGROUND: Cutibacterium acnes is the most common microbe implicated in periprosthetic infection in shoulder arthroplasty. We present an update of a previous pilot study in which we demonstrated the persistence of C acnes on the skin and contamination of the scalpel used for the initial skin incision despite a robust presurgical skin preparation protocol. METHODS: We collected a consecutive case series of patients undergoing primary or revision anatomic or reverse total shoulder arthroplasty performed by a single fellowship-trained surgeon at a tertiary referral hospital from November 2019 to December 2022. The scalpel blade used for the initial skin incision in each patient was swabbed, with cultures being held for 21 days according to a C acnes-specific protocol. Demographic data, medical comorbidities, surgical information, culture results, and infections were documented. RESULTS: We identified 100 patients (51 men and 49 women) who met the inclusion criteria (mean age, 66.91 years; age range, 44-93 years). Cultures returned positive findings for C acnes in 12 patients (12%), 11 of whom were men (odds ratio, 13.2; 95% confidence interval, 1.73-194.87). No association was found between positive culture findings and age, body mass index, medical comorbidities, or procedure type. No postoperative infections occurred in this patient cohort, and the patients will continue to be monitored for the development of infection. CONCLUSION: Despite stringent presurgical preparation and scrub protocols, a significant portion of patients undergoing shoulder arthroplasty have C acnes in culturable quantities on their skin at the time of incision. C acnes contamination is much more common in male patients. These findings should be taken into consideration regarding preventive measures such as discarding the initial scalpel and avoiding unnecessary dermal contact during the procedure.

Biomechanical evaluation of subscapularis peel repairs augmented with the long head of the biceps tendon for anatomic total shoulder arthroplasty.

BACKGROUND: Subscapularis failure is a troublesome complication following anatomic total shoulder arthroplasty (aTSA). Commonly discarded during aTSA, the long head of the biceps tendon (LHBT) may offer an efficient and cheap autograft for the augmentation of the subscapularis repair during aTSA. The purpose of this study was to biomechanically compare a standard subscapularis peel repair to 2 methods of subscapularis peel repair augmented with LHBT. METHODS: 18 human cadaveric shoulders (61 ± 9 years of age) were used in this study. Shoulders were randomly assigned to biomechanically compare subscapularis peel repair with (1) traditional single-row repair, (2) single row with horizontal LHBT augmentation, or (3) single row with V-shaped LHBT augmentation. Shoulders underwent biomechanical testing on a servohydraulic testing system to compare cyclic displacement, load to failure, and stiffness. RESULTS: There were no significant differences in the cyclic displacement between the 3 techniques in the superior, middle, or inferior portion of the subscapularis repair (P > .05). The horizontal (436.7 ± 113.3 N; P = .011) and V-shape (563.3 ± 101.0 N; P < .001) repair demonstrated significantly greater load to failure compared with traditional repair (344.4 ± 82.4 N). The V-shape repair had significantly greater load to failure compared to the horizontal repair (P < .001). The horizontal (61.6 ± 8.4 N/mm; P < .001) and the V-shape (62.8 ± 6.1; P < .001) repairs demonstrated significantly greater stiffness compared to the traditional repair (47.6 ± 6.2 N). There was no significant difference in the stiffness of the horizontal and V-shape repairs (P = .770). CONCLUSIONS: Subscapularis peel repair augmentation with LHBT autograft following aTSA confers greater time zero load to failure and stiffness when compared to a standard subscapularis peel repair.

Elliptical heads result in increased glenohumeral translation along with micro-motion of the glenoid component during axial rotation in total shoulder arthroplasty.

INTRODUCTION: Elliptical-shaped humeral head prostheses have recently been proposed to reflect a more anatomic shoulder replacement. However, its subsequent effect on micro-motion of the glenoid component is still not understood. MATERIALS AND METHODS: Six fresh-frozen, cadaveric shoulders (mean age: 62.7 ± 9.2 years) were used for the study. Each specimen underwent total shoulder arthroplasty using an anatomic stemless implant. At 15°, 30°, 45° and 60° of glenohumeral abduction, 50° of internal and external rotations in the axial plane were alternatingly applied to the humerus with both an elliptical and spherical humeral head design. Glenohumeral translation was assessed by means of a 3-dimensional digitizer. Micro-motion of the glenoid component was evaluated using four high-resolution differential variable reluctance transducer strain gauges, placed at the anterior, posterior, superior, and inferior aspect of the glenoid component. RESULTS: The elliptical head design showed significantly more micro-motion in total and at the superior aspect of glenoid component during external rotation at 15° (total: P = 0.004; superior: P = 0.004) and 30° (total: P = 0.045; superior: P = 0.033) of abduction when compared to the spherical design. However, during internal rotation, elliptical and spherical heads showed similar amounts of micro-motion at the glenoid component at all tested abduction angles. When looking at glenohumeral translation, elliptical and spherical heads showed similar anteroposterior and superoinferior translation as well as compound motion during external rotation at all tested abduction angles. During internal rotation, the elliptical design resulted in significantly more anteroposterior translation and compound motion at all abduction angles when compared to the spherical design (P < 0.05). CONCLUSION: In the setting of total shoulder arthroplasty, the elliptical head design demonstrated greater glenohumeral translation and micro-motion at the glenoid component during axial rotation when compared to the spherical design, potentially increasing the risk for glenoid loosening in the long term. LEVEL OF EVIDENCE: Controlled Laboratory Study.

Characterization of murine subacromial bursal-derived cells.

PURPOSE/AIM: The purpose of this study is to identify a cell population within the murine subcromial bursal-derived cells with characteristics compatible to an accepted mesenchymal stem cell description given by the International Society for Cellular Therapy (ISCT). MATERIALS AND METHODS: Murine subacromial bursa was harvested using microsurgical technique. Subacromial bursal-derived cells were classified through colony-forming units, microscopic morphology, fluorescent-activated cell sorting, and differentiation into chondrogenic, adipogenic, and osteogenic lineages. RESULTS: Subacromial bursal samples exhibited cell growth out of the tissue for an average of 115 ± 29 colony-forming units per 1 mL of complete media. Subacromial bursal-derived cells exhibited a long, spindle-shaped, fibroblast-like morphology. Subacromial bursal-derived cells positively expressed mesenchymal stem cell markers CD73, CD90, and CD105, and negatively expressed mesenchymal stem cell markers CD31 and CD45. Subacromial bursal-derived cells, examined by Image J analysis and quantitative gene expression, were found to differentiate into chondrogenic, adipogenic, and osteogenic lineages. CONCLUSIONS: This study demonstrated the feasibility of harvesting murine subacromial bursal tissue and identified a cell population within the subacromial bursa with characteristics compatible to an accepted mesenchymal stem cell description. The results of this study suggest that the mouse subacromial bursal-derived cell population harbors mesenchymal stem cells. Murine subacromial bursal tissue is a potential source for obtaining cells with mesenchymal stem cell characteristics for future utilization in orthopedic research to look into treatment of rotator cuff pathology.

Current concepts in acromioclavicular joint (AC) instability - a proposed treatment algorithm for acute and chronic AC-joint surgery.

BACKGROUND: There exists a vast number of surgical treatment options for acromioclavicular (AC) joint injuries, and the current literature has yet to determine an equivocally superior treatment. AC joint repair has a long history and dates back to the beginning of the twentieth century. MAIN BODY: Since then, over 150 different techniques have been described, covering open and closed techniques. Low grade injuries such as Type I-II according to the modified Rockwood classification should be treated conservatively, while high-grade injuries (types IV-VI) may be indicated for operative treatment. However, controversy exists if operative treatment is superior to nonoperative treatment, especially in grade III injuries, as functional impairment due to scapular dyskinesia or chronic pain remains concerning following non-operative treatment. Patients with a stable AC joint without overriding of the clavicle and without significant scapular dysfunction (Type IIIA) may benefit from non-interventional approaches, in contrast to patients with overriding of the clavicle and therapy-resistant scapular dysfunction (Type IIIB). If these patients are considered non-responders to a conservative approach, an anatomic AC joint reconstruction using a hybrid technique should be considered. In chronic AC joint injuries, surgery is indicated after failed nonoperative treatment of 3 to 6 months. Anatomic AC joint reconstruction techniques along with biologic augmentation (e.g. Hybrid techniques, suture fixation) should be considered for chronic high-grade instabilities, accounting for the lack of intrinsic healing and scar-forming potential of the ligamentous tissue in the chronic setting. However, complication and clinical failure rates remain high, which may be a result of technical failures or persistent horizontal and rotational instability. CONCLUSION: Future research should focus on addressing horizontal and rotational instability, to restore native physiological and biomechanical properties of the AC joint.

Subacromial Bursal Tissue and Surrounding Matrix of Patients Undergoing Rotator Cuff Repair Contains Progenitor Cells.

PURPOSE: To build upon previous literature to identify a complete analysis of cellular contents of subacromial bursal tissue as well as the matrix surrounding the rotator cuff. METHODS: Samples of subacromial bursal tissue and surrounding matrix milieu from above the rotator cuff tendon and above the rotator cuff muscle bellies were obtained from 10 patients undergoing arthroscopic rotator cuff repair. Samples were analyzed using fluorescent-activated cell sorting and histologic analysis with staining protocols (Oil Red O, Alcian Blue, and Picro-Sirius Red), for identification of matrix components, including fat, proteoglycans, and collagen. RESULTS: Progenitor cells and fibroblast-type cells were present in significant amounts in subacromial bursal tissue in both tissues obtained from over the tendinous and muscle belly portions. Markers for neural tissue, myeloid cells, and megakaryocytes also were present to a lesser extent. There were prominent amounts of fat and proteoglycans present in the matrix, based on ImageJ analysis of stained histologic slides. CONCLUSIONS: The subacromial bursal tissue and surrounding matrix of patients undergoing rotator cuff repair contains progenitor cells in significant concentrations both over the tendon and muscle belly of the rotator cuff. CLINICAL RELEVANCE: This presence of progenitor cells, in particular, in the subacromial bursal tissue provides a potential basis for future applications of augmentation purposes in rotator cuff healing, and calls into question the practice of routine bursectomy. As the potential role of bursal tissue contents in growth and regeneration in the setting of rotator cuff healing is more well understood, maintaining this tissue may become more relevant. Concentration of these cellular components for use in autologous re-implantation is also an avenue of interest.

Three-Dimensional Footprint Mapping of the Deltoid and Trapezius: Anatomic Pearls for Acromioclavicular Joint Reconstruction.

PURPOSE: To perform a quantitative anatomic evaluation of the deltoid and trapezius footprints in relation to the lateral clavicle and acromioclavicular (AC) joint capsule to assist in surgical technique of AC joint reconstructions. METHODS: Fourteen fresh-frozen human cadaveric shoulders from 9 donors were analyzed. Meticulous dissection of the deltoid origin and trapezius insertions to the clavicle and AC joint was performed. Footprints were reconstructed using a MicroScribe digitizer. The inferior extension of the deltoid origin beneath the lateral clavicle and the footprints of the deltoid and trapezius onto the acromioclavicular ligamentous complex (ACLC) were quantified. Reproducibility was assessed by redigitizing 5 shoulders in a blinded and random fashion. RESULTS: The anterior deltoid fibers extended on average 4.0 ± 1.6 mm inferiorly with respect to the anteroinferior clavicular ridge and attached to 90.9 ± 7.3% of the anterior ACLC. The trapezius inserted onto the posterior and superior ACLC, covering 15.3 ± 3.4% of the anterior-posterior width of the superior capsule. The deltopectoral interval was 6 cm, or 37% the length of the clavicle from the distal end of the clavicle. CONCLUSIONS: The deltoid has superior, anterior, and not as well described, inferior attachments to the lateral clavicle. Furthermore, the deltoid and trapezius muscles have intimate attachments to the AC joint capsule, particularly the trapezius to the posterior and posterosuperior capsule. Lastly, the deltoid origin attaches to the lateral 6 cm of the clavicle. CLINICAL RELEVANCE: Subperiosteal elevation of the deltoid off the lateral clavicle starting superiorly, anteriorly, and lastly inferiorly will reduce deltoid muscle injury and improve visibility of the coracoid process during reconstruction. Furthermore, knowledge of the attachments of the deltoid and trapezius to the ACLC may help limit iatrogenic injury to these dynamic stabilizers.

Bursal Acromial Reconstruction (BAR) Using an Acellular Dermal Allograft for Massive, Irreparable Posterosuperior Rotator Cuff Tears: A Dynamic Biomechanical Investigation.

PURPOSE: To investigate the effect of bursal acromial reconstruction (BAR) using an acellular dermal allograft on glenohumeral joint kinematics including maximum abduction angle, glenohumeral superior translation, cumulative deltoid force, and subacromial contact pressure. METHODS: In this dynamic biomechanical cadaveric shoulder study, 8 fresh-frozen cadaveric shoulders (age 53.4 ± 14.2 years, mean ± standard deviation) were tested using a dynamic shoulder testing system. Maximum abduction angle (MAA), glenohumeral superior translation (ghST), maximum cumulative deltoid force (cDF), and subacromial peak contact pressure (sCP) were compared across 3 conditions: (1) intact shoulder; (2) massive retracted irreparable posterosuperior rotator cuff tear (psRCT) according to Patte III; and (3) BAR. Additionally, humeral head containment was measured using contact pressure. RESULTS: Compared with the simulated psRCT, BAR significantly increased mean MAA and significantly decreased ghST (P < .001, respectively) and cDF (P = .017) Additionally, BAR was found to significantly decrease sCP compared with psRCT (P = .024). CONCLUSION: In a dynamic biomechanical cadaveric shoulder simulator, resurfacing the undersurface of the acromion using the BAR technique leads to significantly improved ghST, MAA, cDF, and sCP compared with the irreparable rotator cuff tear. CLINICAL RELEVANCE: With the BAR technique, native humeral containment may be restored, which can potentially delay progressive subacromial and glenoidal abrasive wear and improve overall shoulder function. As such, the proposed BAR technique can be considered as a technically feasible and potentially cost- and timesaving procedure, as no bone anchors are needed, glenoidal or humeral side graft ruptures can be avoided, and postoperative rehabilitation can be started immediately. However, future clinical studies are needed.

Biologically Augmented Suture for Ligament Bracing Procedures Positively Affects Human Ligamentocytes and Osteoblasts In Vitro.

PURPOSE: The purpose was to evaluate the response of human ligamentocytes and osteoblasts after biological augmentation with thrombin, concentrated bone marrow aspirate (cBMA), or platelet-rich plasma (PRP) on two different types of nonresorbable flat braided suture used for ligament bracing. METHODS: Uncoated (U) and collagen-coated (C) flat braided suture material was augmented with either thrombin (T), cBMA (B), PRP (P), or a combination of these three (A), while platelet-poor plasma was used as a source for fibrin (F) in each assay. Previously cultured ligamentocytes and osteoblasts were added with a defined density and assayed after the required time period for adhesion, proliferation, and alkaline phosphatase activity. RESULTS: Biological augmentation of uncoated [(UFT, UFBT, UFA; P < .001), (UFPT; P = .017)] and collagen-coated suture (CFT, CFPT, CFBT, CFA; P < .001) led to a significantly higher ligamentocyte adhesion. Significantly higher adhesion was also observed for osteoblasts (UFT, UFPT, UFBT, UFA; P < .001; CFT, CFPT, CFBT, CFA; P < .001). Similarly, ligamentocyte proliferation was significantly higher [(UFT, UFPT, UFA; P = .009), (UFBT; P = .001), (CFT; P = .009), (CFBT; P = .001), and (CFA; P = .01)]. Osteoblasts showed significantly higher proliferation as well [(UFT, UFPT, UFA; P = .002), (UFBT; P = .001); (CFT: P = .003), and (CFPT, CFBT, CFA; P = .001)]. Augmentation with thrombin, PRP, and BMA for uncoated (UFT; P = .006, UFPT; P = .035, UFBT; P = .001) and BMA for coated suture (CFBT; P = .027) led to significantly higher alkaline phosphatase activity. CONCLUSION: Biological enhancement of suture used for ligament bracing significantly increased ligamentocyte and osteoblast adhesion and proliferation, as well as alkaline phosphatase activity of osteoblasts in an in vitro model. After biological augmentation, cellular adhesion, proliferation, and alkaline phosphatase activity changed up to 1,077%, 190%, and 78%, respectively. Furthermore, no overall superiority between uncoated or collagen-coated suture material was observed for cellular adhesion, proliferation, or alkaline phosphatase activity. CLINICAL RELEVANCE: This study provides in vitro data on a new treatment concept of biologic augmentation for acute ligamentous lesions treated with ligament bracing that has not been widely described. This concept may improve the healing of injured ligaments, in addition to providing immediate biomechanical stabilization.

Increased Glenohumeral Joint Loads Due to a Supraspinatus Tear Can Be Reversed With Rotator Cuff Repair: A Biomechanical Investigation.

PURPOSE: To evaluate the effect of an isolated full-thickness supraspinatus (SSP) tear on glenohumeral kinematics and contact mechanics, as well as to quantify improvement following rotator cuff repair (RCR). METHODS: Ten fresh-frozen cadaveric shoulders (mean age: 63.1 ± 4.6 years) were tested using a dynamic shoulder simulator. A pressure-mapping sensor was placed between the humeral head and the glenoid. Each specimen underwent the following three conditions: 1) native, 2) isolated full-thickness SSP tear, and 3) RCR. Maximum abduction angle (MAA) and superior humeral head migration (SHM) were measured using 3D motion tracking software. Cumulative deltoid force (CDF) and glenohumeral contact mechanics, including contact area (GCA) and contact pressure (GCP), were assessed at the resting position, as well as at 15°, 30°, 45°, and 60° of glenohumeral abduction. RESULTS: Compared to native, the SSP tear resulted in a significant decrease in MAA (Δ-8.3°; P < .001) along with a SHM of 6.4 ± 3.8 mm, while significantly increasing CDF (Δ20.5 N; P = .008), GCP (Δ63.1 kPa; P < .001), and peak GCP (Δ278.6 kPa; P < .001), as well as decreasing GCA (Δ-45.8 mm2; P < .001) at each degree of abduction. RCR reduced SHM to 1.2 ± 2.5 mm, while restoring native MAA, CDF (Δ1.8 N), GCA (Δ4.5 mm2), GCP (Δ-4.5 kPa) and peak GCP (Δ19.9 kPa) at each degree of abduction (P > .999, respectively). CONCLUSION: In a dynamic biomechanical cadaveric model, increased glenohumeral joint loads due to a full-thickness SSP tear can be reversed with RCR. More specifically, RCR restored native glenohumeral contact area and contact pressure, while preventing superior humeral head migration and decreasing compensatory deltoid forces. CLINICAL RELEVANCE: These time 0 observations indicate that undergoing rotator cuff repair may prevent the development of degenerative changes by significantly reducing glenohumeral joint loads and ensuring sufficiently stable joint kinematics.

Suture Tape Augmentation for the Repair of Index Finger Radial Collateral Ligament Injury: A Biomechanical Study.

PURPOSE: Despite their clinical importance in maintaining the stability of the pinch mechanism, injuries of the radial collateral ligament (RCL) of the index finger may be underrecognized and underreported. The purpose of this biomechanical study was to compare the repair of index finger RCL tears with either a standard suture anchor or suture tape augmentation. METHODS: The index fingers from 24 fresh-frozen human cadavers underwent repair of torn RCLs using either a standard suture anchor or suture tape augmentation. Following the repairs, the initial displacement of the repair with a 3-N ulnar deviating load was evaluated. Next, the change in displacement (cyclic deformation) of the repair after 1,000 cycles of 3 N of ulnar deviating force was calculated (displacement of the 1000th cycle - displacement of the first cycle). Finally, the amount of force required to cause clinical failure (30° ulnar deviation) of the repair was determined. RESULTS: Suture tape augmentation repairs displayed significantly less cyclic deformation (0.8 ± 0.5 mm) after cyclic loading than suture anchor repairs (1.8 ± 0.7 mm). There was no significant difference in the force required to cause the clinical failure of the repairs between the suture tape (35.1 ± 18.1 N) and suture anchor (24.5 ± 9.2 N) repairs. CONCLUSIONS: Index finger RCL repair with suture tape augmentation results in decreased deformation with repetitive motion compared with RCL repair alone. CLINICAL RELEVANCE: Suture tape augmentation may allow for early mobilization following index finger RCL repair by acting as a brace that protects the repaired ligament from deforming forces.

The utility of the biceps palpation-rotation test in diagnosing partial distal biceps tendon tears.

BACKGROUND: Partial tears of the distal biceps tendon can be difficult to diagnose based on clinical examination and magnetic resonance imaging (MRI). METHODS: Patients from a single surgeon's practice from 2000 to 2018 with a partial distal biceps tendon tear were retrospectively reviewed to determine the utility of the distal biceps palpation-rotation test in the detection of partial tears. This test is performed by palpating the bicipital tuberosity at the lateral forearm while ranging the forearm from supination to pronation with the arm adducted at the patient's side and the elbow flexed to 90°. A positive test elicits tenderness at the tuberosity with the arm in pronation but not in supination. Examination findings were correlated with MRI reports confirming a partial tear. Twelve cadaveric arms were dissected to determine overall pronosupination range of motion, the degree of pronation at which the bicipital tuberosity is maximally palpable, and anatomic measurements of the bicipital tuberosity to guide the optimal technique when carrying out the maneuver. RESULTS: Ninety-nine patients were diagnosed with a partial distal biceps tendon, of whom 34 had available MRI reports and complete physical examination documentation. Thirty-three of 34 patients (97%) had partial tears on MRI. The hook test was negative in all cases. All patients had tenderness with resisted supination. In those with MRI-confirmed partial tears, the palpation-rotation test was positive in all patients (100% sensitivity). The bicipital tuberosity was maximally palpated at the dorsolateral forearm at a mean 20° of pronation, and the proximal and distal boundaries of the radial tuberosity were 2.5 cm and 5.3 cm, on average, distal to the radial head, respectively. CONCLUSION: A positive palpation-rotation test was seen in 33 of 33 patients (100% sensitivity), as correlated with MRI. The combination of an intact distal biceps tendon within the antecubital fossa, tenderness on resisted supination, and a positive palpation-rotation test are highly suggestive of a partial distal biceps tendon tear.

Biomechanical comparison of lower trapezius and latissimus dorsi transfer for irreparable posterosuperior rotator cuff tears using a dynamic shoulder model.

BACKGROUND: In the setting of irreparable posterosuperior rotator cuff tears (PSRCTs), lower trapezius transfer (LTT) may be anatomically better positioned for restoring the muscular force couple compared with latissimus dorsi transfer (LDT). The purpose of the study was to evaluate the effect of LTT and LDT on glenohumeral kinematics using a dynamic shoulder model. METHODS: Ten fresh-frozen cadaveric shoulders (mean age: 56.5 ± 17.2 years) were tested using a dynamic shoulder simulator. The maximum abduction angle (MAA), superior humeral head migration (SHM), and cumulative deltoid forces (CDFs) were compared across 4 conditions: (1) native; (2) irreparable PSRCT; (3) LTT using an Achilles tendon allograft; and (4) LDT. MAA and SHM were measured using 3-dimensional motion tracking. CDF was recorded in real time throughout the dynamic abduction motion by load cells connected to actuators. RESULTS: Compared to the native state, the PSRCT resulted in a significant decrease (Δ-24.1°; P < .001) in MAA, with a subsequent significant increase after LTT (Δ13.1°; P < .001) and LDT (Δ8.9°; P < .001). LTT achieved a significantly greater MAA than LDT (Δ4.2°; P = .004). Regarding SHM, both LTT (Δ-9.4 mm; P < .001) and LDT (Δ-5.0 mm; P = .008) demonstrated a significant decrease compared with the PSRCT state. LTT also achieved significantly less SHM compared with the LDT (Δ-4.4 mm; P = .011). Further, only the LTT resulted in a significant decrease in CDF compared with the PSRCT state (Δ-21.3 N; P = .048), whereas LTT and LDT showed similar CDF (Δ-11.3 N; P = .346). However, no technique was able to restore the MAA, SHM, and CDF of the native shoulder (P < .001, respectively). CONCLUSION: LTT and LDT both achieved a significant increase in MAA along with significantly less SHM compared with the PSRCT state. Although LTT required significantly less compensatory deltoid forces compared with the PSRCT state, this was not observed for the LDT. Further, the LTT prevented loss of abduction motion and SHM more sufficiently. In the challenging treatment of irreparable PSRCTs, LTT may restore native glenohumeral kinematics more sufficiently, potentially leading to improved postoperative functional outcomes.