Publications by authors named "Scott P Steinmann"

134 Publications

Effects of purified exosome product on rotator cuff tendon-bone healing in vitro and in vivo.

Biomaterials 2021 09 23;276:121019. Epub 2021 Jul 23.

Department of Orthopedic Surgery, Mayo Clinic Rochester, Rochester, MN, USA. Electronic address:

Exosomes have multiple therapeutic targets, but the effects on healing rotator cuff tear (RCT) remain unclear. As a circulating exosome, purified exosome product (PEP) has the potential to lead to biomechanical improvement in RCT. Here, we have established a simple and efficient approach that identifies the function and underlying mechanisms of PEP on cell-cell interaction using a co-culture model in vitro. In the in vivo trial, adult female Sprague-Dawley rats underwent unilateral surgery to transect and repair the supraspinatus tendon to its insertion site with or without PEP. PEP promoted the migration and confluence of osteoblast cells and tenocytes, especially during direct cell-cell contact. Expression of potential genes for RCT in vitro and in vivo models were consistent with biomechanical tests and semiquantitative histologic scores, indicating accelerated strength and healing of the RC in response to PEP. Our observations suggest that circulating exosomes provide an effective option to improve the healing speed of RCT after surgical repair. The regeneration of enthesis following PEP treatment appears to be related to a mutually reinforcing relationship between direct cell-cell contact and PEP activity, suggesting a dual approach to the healing process.
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http://dx.doi.org/10.1016/j.biomaterials.2021.121019DOI Listing
September 2021

Biomechanical Comparison of Augmentation of Engineered Tendon-Fibrocartilage-Bone Composite With Acellular Dermal Graft Using Double Rip-Stop Technique for Canine Rotator Cuff Repair.

Orthop J Sports Med 2020 Sep 2;8(9):2325967120939001. Epub 2020 Sep 2.

Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota, USA.

Background: The retear rate after rotator cuff repair remains unacceptably high. Various biological engineered scaffolds have been proposed to reduce the retear rate. We have developed a double rip-stop repair with medial row knot (DRSK) technique to enhance suture-tendon strength and a novel engineered tendon-fibrocartilage-bone composite (TFBC) for rotator cuff repair.

Hypothesis: DRSK rotator cuff repair augmented with TFBC will have better biomechanical properties than that of DRSK repair with an acellular dermal graft (DG).

Study Design: Controlled laboratory study.

Methods: Fresh-frozen canine shoulders (n = 30) and knees (n = 10) were used. TFBCs were harvested from the patellar tendon-tibia complex and prepared for rotator cuff repair. The infraspinatus tendon was sharply detached from its bony attachment and randomly assigned to the (1) control group: DRSK repair alone, (2) TFBC group: DRSK repair with TFBC, and (3) DG group: DRSK repair with DG. All specimens were tested to failure, and videos were recorded. The footprint area, tendon thickness, load to create 3-mm gap formation, failure load, failure modes, and stiffness were recorded and compared. Data were recorded as mean ± SD.

Results: The mean load to create a 3-mm gap in both the control group (206.8 ± 55.7 N) and TFBC group (208.9 ± 39.1 N) was significantly higher than that in the DG group (157.7 ± 52.3 N) ( < .05 for all). The failure load of the control group (275.7 ± 75.0 N) and TFBC group (275.2 ± 52.5 N) was significantly higher compared with the DG group (201.5 ± 49.7 N) ( < .05 for both comparisons). The stiffness of the control group (26.4 ± 4.7 N/mm) was significantly higher than of the TFBC group (20.4 ± 4.4 N/mm) and the DG group (21.1 ± 4.8 N/mm) ( < .05 for both comparisons).

Conclusion: TFBC augmentation showed superior biomechanical performance to DG augmentation in rotator cuff tears repaired using the DRSK technique, while there was no difference between the TFBC and control groups.

Clinical Relevance: TFBC may help to reduce retear or gap formation after rotator cuff repair using the DRSK technique.
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http://dx.doi.org/10.1177/2325967120939001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7476351PMC
September 2020

Biomechanical evaluation of a novel double rip-stop technique with medial row knots for rotator cuff repair: an in vitro study.

Bone Joint Res 2020 Jun 23;9(6):285-292. Epub 2020 Jul 23.

Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota, USA.

Aims: Many biomechanical studies have shown that the weakest biomechanical point of a rotator cuff repair is the suture-tendon interface at the medial row. We developed a novel double rip-stop (DRS) technique to enhance the strength at the medial row for rotator cuff repair. The objective of this study was to evaluate the biomechanical properties of the DRS technique with the conventional suture-bridge (SB) technique and to evaluate the biomechanical performance of the DRS technique with medial row knots.

Methods: A total of 24 fresh-frozen porcine shoulders were used. The infraspinatus tendons were sharply dissected and randomly repaired by one of three techniques: SB repair (SB group), DRS repair (DRS group), and DRS with medial row knots repair (DRSK group). Specimens were tested to failure. In addition, 3 mm gap formation was measured and ultimate failure load, stiffness, and failure modes were recorded.

Results: The mean load to create a 3 mm gap formation in the DRSK and DRS groups was significantly higher than in the SB group. The DRSK group had the highest load to failure with a mean ultimate failure load of 395.0 N (SD 56.8) compared to the SB and DRS groups, which recorded 147.1 N (SD 34.3) and 285.9 N (SD 89.8), respectively (p < 0.001 for both). The DRS group showed a significantly higher mean failure load than the SB group (p = 0.006). Both the DRS and DRSK groups showed significantly higher mean stiffness than the SB group.

Conclusion: The biomechanical properties of the DRS technique were significantly improved compared to the SB technique. The DRS technique with medial row knots showed superior biomechanical performance than the DRS technique alone.
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http://dx.doi.org/10.1302/2046-3758.96.BJR-2019-0196.R1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7376283PMC
June 2020

Static and Dynamic External Fixation are Equally Effective for Unstable Elbow Fracture-Dislocations.

J Orthop Trauma 2021 03;35(3):e82-e88

Department of Surgery, St. Joseph's Health Care, Hand and Upper Limb Centre, Western University, London, ON, Canada; and.

Objective: To compare the clinical outcomes of static versus dynamic external fixation for elbow fracture-dislocations with persistent instability after surgical management.

Design: Comparative, retrospective review.

Setting: Two tertiary referral upper-extremity centers.

Patients: Twenty-four elbows requiring external fixation for persistent elbow instability within 90 days of surgical management of an elbow fracture-dislocation.

Intervention: Static and dynamic external fixation was used in 16 and 8 patients, respectively, for a median of 39 days (interquartile range, 33-48 days).

Main Outcome Measurements: Elbow range of motion, complications, and revision surgeries.

Results: Immediately after static and dynamic external fixation removal, there was no difference in elbow extension [33 degrees ± 16 degrees vs. 41 degrees ± 13 degrees, mean difference (MD) 7 degrees, 95% confidence interval (CI) -6 degrees-22 degrees] or flexion (114 degrees ± 35 degrees vs. 118 degrees ± 11 degrees, MD 4 degrees, 95% CI -23 degrees-132 degrees), respectively. At last follow-up, static and dynamic external fixation groups had no difference in elbow extension (27 degrees ± 13 degrees vs. 24 degrees ± 10 degrees, MD -3 degrees, 95% CI -15 degrees-7 degrees) or flexion (129 degrees ± 12 degrees vs. 128 degrees ± 14 degrees, MD -1 degree, 95% CI -13 degrees-10 degrees), respectively. Static and dynamic external fixation groups had no difference in complications [7 (44%) vs. 5 (63%), difference 19%, 95% CI -23%-54%] or revision surgeries [6 (38%) vs. 4 (50%), difference 13%, 95% CI -27%-49%].

Conclusions: No difference in range of motion, complications, and revision surgeries was detected after static versus dynamic external fixation of persistently unstable elbow fracture-dislocations. Due to ease of application, static external fixation is our preferred treatment for these injuries.

Level Of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
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http://dx.doi.org/10.1097/BOT.0000000000001876DOI Listing
March 2021

Anchor placement to glenoid rim during Bankart repair recreates contact area of anterior capsulolabral complex on glenoid better than onto articular surface.

Eur J Orthop Surg Traumatol 2020 Oct 16;30(7):1257-1262. Epub 2020 May 16.

Biomechanics Laboratory and Tendon and Soft Tissue Biology Laboratory, Division of Orthopedic Research, Mayo Clinic, Rochester, MN, USA.

Purpose: This study aimed to compare the contact areas of Bankart repair with suture anchors placed on the articular surface of the glenoid versus at the rim of the glenoid because it is unclear which technique most effectively restores the footprint after Bankart repair.

Methods: Ten fresh frozen cadaveric shoulders (mean age 70.7 years) were dissected. The attachment site of the capsulolabral complex from the 1 o' clock position to the 6 o'clock position was marked with ink, and the contact area of the anterior-inferior capsulolabral complex on the glenoid neck was measured using imageJ. Bankart lesions were created, and two types of Bankart repair were performed on each specimen. The suture anchors were inserted at the glenoid rim (Rim group) and onto the glenoid articular surface 2 mm from the rim (Surface group). Using pressure-sensitive films, we examined the interface contact area.

Results: The Rim group recreated 64.9% of the native surface area, while the Surface group recreated 47.3% of the area. The Rim group recreated significantly greater contact area compared to the Surface group (P = 0.0008).

Conclusion: The anchor placement to the glenoid rim recreates the footprint of the capsulolabral complex on the anterior inferior glenoid better than the anchor placement onto the articular surface.
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http://dx.doi.org/10.1007/s00590-020-02694-3DOI Listing
October 2020

Editorial Commentary: Elbow Arthroscopy Is a Safe Procedure. Sure.

Arthroscopy 2020 05;36(5):1291-1292

University of Tennessee College of Medicine Chattanooga.

Elbow arthroscopy is a procedure that is of great potential use and yet also of grave potential risks. To balance the risk-versus-reward consideration, one must be aware of the potential complications associated with this procedure, weigh them against the potential advantages, and understand one's own skills and familiarity with the procedure. There is no doubt that elbow arthroscopy has changed and even revolutionized our management of pathology about the elbow; however, one must bear in mind that this comes at a risk of complications that cannot be reduced to zero.
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http://dx.doi.org/10.1016/j.arthro.2020.03.030DOI Listing
May 2020

Bankart repair alone in combined Bankart and superior labral anterior-posterior lesions preserves range of motion without compromising joint stability.

JSES Int 2020 Mar 21;4(1):63-67. Epub 2020 Jan 21.

Division of Orthopedic Research, Mayo Clinic, Rochester, MN, USA.

Hypothesis: The purpose was to investigate joint stability and range of motion after a Bankart repair without superior labral anterior-posterior (SLAP) repair (termed "Bankart repair") and after combined Bankart and SLAP repairs (termed "combined repair").

Methods: Eight fresh-frozen shoulders were used. Combined Bankart and SLAP lesions were created (10- to 6-o'clock positions). The labrum and capsule were repaired at the 2-o'clock, 3:30 clock-face, and 5-o'clock positions in the Bankart repair group and at the 11-o'clock, 1-o'clock, 2-o'clock, 3:30 clock-face, and 5-o'clock positions in the combined repair group. The internal- and external-rotation ranges of motion were determined with the arm positioned at 0° and 60° of glenohumeral abduction. The rotation angle was defined when a constant torque of 200 N-mm was applied. Joint stability was measured with a custom stability-testing device. The peak translational force in the anterior-posterior direction was measured with the arm at the end range of external rotation.

Results: External rotation angles were greater at 0° and 60° of abduction in the Bankart repair group than in the combined repair group (0° of abduction, < .01; 60° of abduction, < .05). The internal rotation angle was greater at 60° of abduction in the Bankart repair group than in the combined repair group ( < .01). The stability between the 2 groups was not significantly different ( = .60).

Conclusion: In patients with combined Bankart and SLAP lesions and the need for a wide range of motion, a Bankart repair alone may provide a greater range of motion without compromising the joint stability at the end range compared with a combined repair.
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http://dx.doi.org/10.1016/j.jseint.2019.11.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7075760PMC
March 2020

Locking plate fixation of proximal humerus fractures in patients older than 60 years continues to be associated with a high complication rate.

J Shoulder Elbow Surg 2020 Aug 19;29(8):1689-1694. Epub 2020 Feb 19.

Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA.

Background: Locking plate technology has increased the frequency of open reduction and internal fixation (ORIF) of proximal humerus fractures (PHF). A number of technical pearls have been recommended to lower the complication rate of ORIF. These pearls are particularly relevant for patients aged >60 years, when nonoperative treatment and arthroplasty are alternatives commonly considered. There have been few large, single-center studies on the modern application of this technology.

Methods: Between 2005 and 2015, a total of 173 PHFs in patients aged >60 years were treated at our institution with ORIF using locking plates. Failure was defined as reoperation or radiographic evidence of failure. Average follow-up was 6.1 years.

Results: There was an overall complication rate of 44%. The overall failure rate was 34% and correlated with fracture type: 26% failure rate in 2-part fractures (16 failures), 39% in 3-part fractures (23 failures), and 45% in 4-part fractures (11 failures). There was no difference between the failure rate with and without fibular allograft (33% vs. 34%). Most patients with radiographic or clinical failure did not undergo reoperation. The overall reoperation rate was 11% (14 patients). Seven percent of 2-part fractures (4 shoulders), 14% of 3-part fractures (8 shoulders), and 18% of 4-part fractures (2 shoulders) required reoperation.

Conclusions: ORIF of PHFs with locking plates in patients aged >60 years resulted in a 44% complication and 34% failure rate. There was a trend toward higher complication and failure rates in older patients and more complex fractures. Refinement in fixation techniques and indications are necessary to optimize the surgical management of PHFs.
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http://dx.doi.org/10.1016/j.jse.2019.11.026DOI Listing
August 2020

Managing Glenoid Deformity in Shoulder Arthroplasty: Role of New Technology (Computer-Assisted Navigation and Patient-Specific Instrumentation).

Instr Course Lect 2020 ;69:583-594

The glenoid is considered a weak link in total shoulder arthroplasty because failure on the glenoid side is one of the most common reasons for revision of total shoulder arthroplasty. Glenoid wear is commonly seen in glenohumeral arthritis and compromises glenoid bone stock and also alters the native version and inclination of the glenoid. It is critical to recognize glenoid wear and correct it intraoperatively to avoid component malposition, which can negatively affect the survivorship of the glenoid implant. The end point of correction for the glenoid wear in shoulder arthroplasty is controversial, but anatomic glenoid component positioning is likely to improve long-term survivorship of the total shoulder arthroplasty. Preoperative three-dimensional (3-D) computer planning software, based on CT, is commercially available. It allows the surgeon to plan implant type (anatomic versus reverse), size, and position on the glenoid, and also allows for templating deformity correction using bone graft and/or augments. Guidance technology in the form of computer-assisted surgery (CAS) and patient-specific instrumentation (PSI) allows the surgeon to execute the preoperative plan during surgery with a greater degree of accuracy and precision and has shown superiority to standard instrumentation. However, the proposed benefits of this technology including improved glenoid survivorship, reduced revision arthroplasty rate and cost-effectiveness have not yet been demonstrated clinically. In this review, we present the current evidence regarding PSI and CAS in managing glenoid deformity in total shoulder arthroplasty.
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February 2020

The vascularized medial femoral condyle free flap for reconstruction of segmental recalcitrant nonunion of the clavicle.

J Shoulder Elbow Surg 2019 Dec 29;28(12):2364-2370. Epub 2019 Jul 29.

Division of Plastic Surgery, Mayo Clinic, Rochester, MN, USA. Electronic address:

Background: Recalcitrant clavicular nonunion is a rare but complicated problem of clavicular fracture fixation. Nonunion is most often treated with clavicular shortening or in extreme cases vascularized bone grafting. Herein we describe our experience using the vascularized medial femoral condyle (MFC) free flap for the reconstruction of segmental defects in cases of recalcitrant clavicular nonunion.

Methods: A retrospective chart review was conducted of patients with symptomatic recalcitrant nonunion of the clavicle who underwent reconstruction with the vascularized MFC free flap from June 2003 to January 2018. Patients' demographics, time to union, and postoperative complications were collected.

Results: A total of 7 patients (6 women; 39.8 ± 9.01 years old) underwent clavicular reconstruction after an average of 3.7 ± 1.3 previous surgical procedures. Average preoperative visual analog scale score for pain was 4.1. The graft size ranged from 2 to 5 cm in length with approximately 1 cm in width and depth. The average time of total nonunion was 66 ± 48.2 months before surgery. All flaps survived and all clavicles healed with an average time to radiographic union of 15 ± 6.7 months. Patients regained full shoulder motion, and average postoperative visual analog scale score was 1.6 ± 1.8. All patients returned to their preoperative employment status. Donor site morbidity from the knee was minimal.

Conclusion: The MFC free flap is a good option for recalcitrant bone nonunion of the clavicle where larger vascularized flaps are not warranted. It is effective and offers minimal donor site morbidity.
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http://dx.doi.org/10.1016/j.jse.2019.04.044DOI Listing
December 2019

Fingerbreadths Rule in Determining the Safe Zone of the Radial Nerve and Posterior Interosseous Nerve for a Lateral Elbow Approach: An Anatomic Study.

J Am Acad Orthop Surg Glob Res Rev 2019 Feb 20;3(2):e005. Epub 2019 Feb 20.

Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN (Dr. Simon, Dr. Streubel, Dr. Sánchez-Sotelo, Dr. Steinmann, and Dr. Adams).

Introduction: The purpose of this study was to investigate whether a safe zone rule could be applied to prevent iatrogenic injuries to the radial nerve (RN); and determine whether there is a relationship between the diameter of the radial head and capitellum and the distance of the posterior interosseous nerve (PIN) to the radiocapitellar joint.

Methods: Ten fresh-frozen cadaveric specimens were used to measure the distances between the RN and the lateral epicondyle; the PIN and the radiocapitellar joint; the lateral epicondyle and the PIN as it crossed the ulnohumeral joint; the diameter of the radial head; the width of the capitellum; and the fingerbreadths of the specimens.

Results: Four fingerbreadths determined a safe zone between the lateral epicondyle and the RN proximally at the point at which it pierced the intermuscular septum and the mid-lateral portion of the humeral shaft. Two fingerbreadths provided a safe zone for the PIN from the radiocapitellar joint to the midpoint of the axis of the radius only with the forearm in pronation.

Conclusion: A four-finger rule, two-finger rule, and radial head diameter or capitellum size may predict a safe zone for the RN and PIN except for the segment of the nerve where it crosses the anterior cortex of either the humerus or radius.

Level Of Evidence: Preclinical cadaveric study.
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http://dx.doi.org/10.5435/JAAOSGlobal-D-19-00005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6587517PMC
February 2019

Primary reverse shoulder arthroplasty using contemporary implants is associated with very low reoperation rates.

J Shoulder Elbow Surg 2019 Jun 20;28(6S):S175-S180. Epub 2019 Apr 20.

Department of Orthopaedic Surgery, Mayo Clinic, Rochester, MN, USA. Electronic address:

Background: The early results of reverse shoulder arthroplasty (RSA) were influenced to some extent by the use of first-generation implants and surgeons' learning curves, resulting in relatively high reoperation rates. The purpose of this study was to quantify the burden of and identify the indications for reoperation after primary RSA using contemporary implants and techniques.

Methods: A retrospective review of 1649 primary RSAs implanted consecutively between 2009 and 2015 at a single institution was conducted. All arthroplasties were performed by 5 fellowship-trained shoulder surgeons at a tertiary referral center. Demographic characteristics, indications for primary RSA, and reoperations were analyzed and categorized for trends associated with each type of reoperation performed.

Results: A total of 39 reoperations (2.37%) were performed for a variety of indications. Overall, only a few patients with infection or instability required reoperation (0.55%). The most common indications for reoperation were related to the humeral component (1.03%); the majority of humeral component complications were related to a specific design flaw of 1 implant system. RSAs performed for proximal humeral fracture sequelae more commonly underwent reoperation owing to instability or humeral component-related issues; all 4 cases of aseptic humeral stem loosening occurred in the setting of proximal humeral fracture sequela treatment. Only 0.36% of all primary RSAs required reoperation because of glenoid complications.

Conclusions: Primary RSA performed with contemporary implants and surgical techniques seems to be associated with a very low rate of reoperation. The most common reasons for reoperation were humeral component fracture for 1 particular implant, humeral loosening, dislocation, infection, and glenoid failure, each occurring at a rate under 1%.
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http://dx.doi.org/10.1016/j.jse.2019.01.026DOI Listing
June 2019

The effect of subscapularis muscle contraction on coaptation of anteroinferior glenohumeral ligament-labrum complex after Bankart repair.

J Biomech 2019 03 22;85:134-140. Epub 2019 Jan 22.

Division of Orthopedic Research, Mayo Clinic, Rochester, MN, United States. Electronic address:

Facilitation of healing is important for the anteroinferior glenohumeral ligament-labrum complex (AIGHL-LC) after Bankart repair in shoulder dislocation. The purpose of this study was to investigate the effect of subscapularis muscle loading on contact area and contact pressure between the subscapularis and AIGHL-LC and between the glenoid bone and the AIGHL-LC following Bankart repair. Twenty-two fresh-frozen cadaveric shoulders were used. They were attached to a shoulder-positioning device to which a compression force was applied. Loads applied to the supraspinatus, infraspinatus, and teres minor tendons were held constant. The loads applied to the subscapularis tendon were set at 0, 10, 20, and 30 Newton (N). Contact pressure and area between the subscapularis and the AIGHL-LC were measured with the arm at 4 rotational positions: 60° and 30° internal, neutral, and 30° external. After the Bankart lesion was created, the contact area and pressure between the AIGHL-LC and glenoid bone were measured while Bankart repair was performed with or without loading of the subscapularis. The contact area and pressures with 10, 20, and 30 N of subscapularis loadings were significantly greater than with 0 N of subscapularis loading at 60° internal rotation and 30° external rotation (P < .05). After Bankart repair, contact area and pressure with subscapularis loading between the AIGHL-LC and glenoid bone were significantly greater than without subscapularis loading (P < .01). We conclude that isometric contraction exercises of the subscapularis might facilitate healing of the AIGHL-LC after Bankart repair.
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http://dx.doi.org/10.1016/j.jbiomech.2019.01.023DOI Listing
March 2019

Engineered tendon-fibrocartilage-bone composite and bone marrow-derived mesenchymal stem cell sheet augmentation promotes rotator cuff healing in a non-weight-bearing canine model.

Biomaterials 2019 02 29;192:189-198. Epub 2018 Oct 29.

Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA. Electronic address:

Reducing rotator cuff failure after repair remains a challenge due to suboptimal tendon-to-bone healing. In this study we report a novel biomaterial with engineered tendon-fibrocartilage-bone composite (TFBC) and bone marrow-derived mesenchymal stem cell sheet (BMSCS); this construct was tested for augmentation of rotator cuff repair using a canine non-weight-bearing (NWB) model. A total of 42 mixed-breed dogs were randomly allocated to 3 groups (n = 14 each). Unilateral infraspinatus tendon underwent suture repair only (control); augmentation with engineered TFBC alone (TFBC), or augmentation with engineered TFBC and BMSCS (TFBC + BMSCS). Histomorphometric analysis and biomechanical testing were performed at 6 weeks after surgery. The TFBC + BMSCS augmented repairs demonstrated superior histological scores, greater new fibrocartilage formation and collagen fiber organization at the tendon-bone interface compared with the controls. The ultimate failure load and ultimate stress were 286.80 ± 45.02 N and 4.50 ± 1.11 MPa for TFBC + BMSCS group, 163.20 ± 61.21 N and 2.60 ± 0.97 MPa for control group (TFBC + BMSCS vs control, P = 1.12E-04 and 0.003, respectively), 206.10 ± 60.99 N and 3.20 ± 1.31 MPa for TFBC group (TFBC + BMSCS vs TFBC, P = 0.009 and 0.045, respectively). In conclusion, application of an engineered TFBC and BMSCS can enhance rotator cuff healing in terms of anatomic structure, collagen organization and biomechanical strength in a canine NWB model. Combined TFBC and BMSCS augmentation is a promising strategy for rotator cuff tears and has a high potential impact on clinical practice.
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http://dx.doi.org/10.1016/j.biomaterials.2018.10.037DOI Listing
February 2019

Open Treatment of Olecranon Fractures with Plate Fixation.

JBJS Essent Surg Tech 2018 Mar 10;8(1):e1. Epub 2018 Jan 10.

Mayo Clinic, Rochester, Minnesota.

Fractures of the olecranon are sometimes difficult to treat. The steps for operative plate fixation of olecranon fractures consist of (1) a dorsal incision, (2) exposure using full-thickness flaps, (3) removal of hematoma from the fracture site, (4) fracture reduction, (5) provisional fixation, (6) plate application, (7) proximal fixation, (8) distal fixation, and (9) layered wound closure. Although this is generally a straightforward procedure, several specific steps may make fixation easier and improve outcomes. Outcomes following olecranon fracture fixation are generally good. Patients should expect some loss of terminal extension and a potential for symptoms related to implant prominence, especially in slender patients. Ulnar nerve symptoms are unusual but possible.
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http://dx.doi.org/10.2106/JBJS.ST.15.00012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6143301PMC
March 2018

Open Treatment of Radial Head Fractures.

JBJS Essent Surg Tech 2017 Dec 13;7(4):e35. Epub 2017 Dec 13.

Mayo Clinic, Rochester, Minnesota.

Radial head fractures may commonly be treated by (1) open reduction and internal fixation (ORIF), (2) radial head excision, or (3) radial head replacement. If there is no associated elbow instability with lateral ulnar collateral ligament (LUCL) injury, the preferred approach is via a split in the extensor digitorum communis (EDC) origin. This provides a wide exposure but limits the risk of injury to the LUCL and associated instability. The radial head is fixed, excised, or replaced. Open treatment of radial head fractures begins with the following steps: (1) a laterally based incision is centered over the radiocapitellar joint, (2) the EDC is split at the midline of the radial head and elevated off the bone anteriorly and superiorly, and dissection proceeds distally, splitting the extensor origin along its fibers, and (3) the capsule is opened and the radial head fracture, identified. For ORIF, provisional fixation is then obtained with Kirschner wires and small bone reduction clamps. Headless low-profile screws are preferred if possible. If a plate is used, the dissection proceeds distally and the posterior interosseous nerve may need to be identified and protected. Definitive fixation is applied in the safe zone for implant placement (i.e., a right angle based laterally when the forearm is in a neutral position). For excision of the radial head as definitive treatment or for radial head replacement, the fragments are removed and an oscillating saw is used to remove additional radial neck or other fragments. When radial head excision is the definitive treatment, the radial neck is planed to a smooth contour that allows for placement of the prosthesis or for smooth motion without impingement at the proximal radioulnar joint. An indication for radial head replacement is suspicion of an Essex-Lopresti-type injury or demonstration of longitudinal instability of the forearm with excessive motion when a "push-pull" test is performed under fluoroscopy of the wrist while traction is applied to the radial neck. The final step of open treatment of radial head fractures, before the wound is closed in layers, consists of assessment of the range of motion and use of fluoroscopy to confirm appropriate fixation, resection, or prosthetic position. Outcomes following radial head fixation, resection, or arthroplasty for isolated radial head fractures are generally favorable. Loss of motion is particularly problematic in the pronation-supination arc in the setting of plate fixation, and patients are generally counseled that implant removal is often necessary. Loss of motion in the flexion-extension arc, particularly loss of terminal extension, may be noted. Resection of the radial head results in radiographic evidence of degenerative changes along the ulnohumeral joint, but this may be well tolerated as symptoms develop slowly, particularly in older patients. Radial head replacement results in changes in the capitellum over time, but these are usually asymptomatic.
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http://dx.doi.org/10.2106/JBJS.ST.15.00073DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6132991PMC
December 2017

Hemiarthroplasty Is an Option for Patients Older Than 70 Years With Glenohumeral Osteoarthritis.

Orthopedics 2018 Jul 26;41(4):222-228. Epub 2018 Jun 26.

Hemiarthroplasty (HA) of the shoulder has several potential advantages over total shoulder arthroplasty (TSA), particularly in the elderly population. This study reviewed long-term results of HA and TSA in patients older than 70 years with glenohumeral osteoarthritis. During a 30-year period, 403 shoulders had undergone HA (n=74) or TSA (n=329) for glenohumeral osteoarthritis. Outcome measures included pain, range of motion, and postoperative modified Neer ratings. All patients were included in the mortality and revision analyses. A total of 289 shoulders (44 HAs and 245 TSAs; mean patient age, 75 years) with a minimum of 5 years of follow-up or follow-up until revision were included. Both groups showed significant improvements in pain, abduction, and external rotation. No significant differences were detected between groups in postoperative pain, range of motion, or modified Neer ratings. Operative time was significantly lower in the HA group. There was no statistically significant difference detected in implant revision-free survival between TSA and HA (hazard ratio, 3.09) or in overall survival hazard ratio. At long-term follow-up, both HAs and TSAs provided good function in the elderly population. Patients who underwent TSA and patients who underwent HA had similar results, but the latter had a shorter operative time and lower revision rate. Hemiarthroplasty is a reasonable option for patients older than 70 years with end-stage glenohumeral osteoarthritis. [Orthopedics. 2018; 41(4):222-228.].
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http://dx.doi.org/10.3928/01477447-20180621-03DOI Listing
July 2018

Novel engineered tendon-fibrocartilage-bone composite with cyclic tension for rotator cuff repair.

J Tissue Eng Regen Med 2018 07 3;12(7):1690-1701. Epub 2018 Jun 3.

Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA.

Surgical repair of rotator cuff tears presents a significant clinical challenge with high failure rates and inferior functional outcomes. Graft augmentation improves repair outcomes; however, currently available grafting materials have limitations. Although cell-seeded decellularized tendon slices may facilitate cell infiltration, promote tendon incorporation, and preserve original mechanical strength, the unique fibrocartilage zone is yet to be successfully reestablished. In this study, we investigated the biological and mechanical properties of an engineered tendon-fibrocartilage-bone composite (TFBC) with cyclic tension (3% strain; 0.2 Hz). Decellularized TFBCs seeded with bone marrow-derived mesenchymal stem cell (BMSCs) sheets and subjected to mechanical stimulation for up to 7 days were characterised by histology, immunohistochemistry, scanning electron microscopy, mechanical testing, and transcriptional regulation. The decellularized TFBC maintained native enthesis structure and properties. Mechanically stimulated TFBC-BMSC constructs displayed increased cell migration after 7 days of culture compared with static groups. The seeded cell sheet not only integrated well with tendon scaffold but also distributed homogeneously and aligned to the direction of stretch under dynamic culture. Developmental genes were regulated including scleraxis, which was significantly upregulated with mechanical stimulation. The Young's modulus of the cell-seeded constructs was significantly higher compared with the noncell-seeded controls. In conclusion, the results of this study reveal that the TFBC-BMSC composite provides an ideal multilayer construct for cell seeding and growth, with mechanical preconditioning further enhances cell penetration and differentiation. The BMSC cell sheet revitalised TFBC in conjunction with mechanical stimulation could serve as a novel and primed biological patch to improve rotator cuff repair.
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http://dx.doi.org/10.1002/term.2696DOI Listing
July 2018

Assessing glenosphere position: superior approach versus deltopectoral for reverse shoulder arthroplasty.

J Shoulder Elbow Surg 2018 Mar 19;27(3):455-462. Epub 2017 Dec 19.

Department of Orthopedics, Mayo Clinic, Rochester, MN, USA. Electronic address:

Background: The anterosuperior (AS) approach for reverse total shoulder arthroplasty (RTSA) has been reported as a risk factor for baseplate malposition because of potential difficulty in glenoid exposure. The objective of this study was to compare glenoid baseplate position between the AS and deltopectoral (DP) approaches in relation to the surgeon's experience and to evaluate the effect of placement on clinical outcomes.

Methods: There were 109 shoulders that underwent RTSA for cuff tear arthropathy or osteoarthritis with cuff tearing by a single surgeon. The AS approach was used in 87 shoulders. Clinical, radiographic, and functional outcomes were assessed for all patients with a minimum of 2 years of follow-up. Initial postoperative radiographs of all 109 shoulders were assessed for baseplate positioning.

Results: The mean change in glenoid inclination was 3.0° inferior with the AS approach and 2.5° inferior with the DP approach (P = .68). Pain scores (P = .14), range of motion, and American Shoulder and Elbow Surgeons scores (P = .16) improved in both groups, without a difference between approach. Scapular notching was noted in 68.5% of AS shoulders and 72.4% of DP shoulders (P = .78). Over time, there was a trend to place the glenoid baseplate more caudal with less inferior tilt.

Discussion And Conclusion: Both approaches produce similar baseplate position, clinical outcomes, and rates of scapular notching when they are used for RTSA. Attempts to inferiorize the glenoid baseplate through the AS approach may increase the risk of superior inclination.
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http://dx.doi.org/10.1016/j.jse.2017.10.013DOI Listing
March 2018

Quantifying extensibility of rotator cuff muscle with tendon rupture using shear wave elastography: A cadaveric study.

J Biomech 2017 08 21;61:131-136. Epub 2017 Jul 21.

Biomechanics Laboratory, Division of Orthopedic Research, Mayo Clinic, Rochester, MN, United States. Electronic address:

Surgical repair for large rotator cuff tear remains challenging due to tear size, altered muscle mechanical properties, and poor musculotendinous extensibility. Insufficient extensibility might lead to an incomplete reconstruction; moreover, excessive stresses after repair may result in repair failure without healing. Therefore, estimates of extensibility of cuff muscles can help in pre-surgical planning to prevent unexpected scenarios during surgery. The purpose of this study was to determine if quantified mechanical properties of the supraspinatus muscle using shear wave elastography (SWE) could be used to predict the extensibility of the musculotendinous unit on cadaveric specimens. Forty-five fresh-frozen cadaveric shoulders (25 intact and 20 with rotator cuff tear) were used for the study. Passive stiffness of 4 anatomical regions in the supraspinatus muscle was first measured using SWE. After detaching the distal edge of supraspinatus muscle from other cuff muscles, the detached muscle was axially pulled with the scapula fixed. The correlation between the SWE modulus and the extensibility of the muscle under 30 and 60N loads was assessed. There was a significant negative correlation between SWE measurements and the experimental extensibility. SWE modulus for the anterior-deep region in the supraspinatus muscle showed the strongest correlation with extensibility under 30N (r=0.70, P<0.001) and 60N (r=0.68, P<0.001). Quantitative SWE assessment for the supraspinatus muscle was highly correlated with extensibility of musculotendinous unit on cadaveric shoulders. This technique may be used to predict the extensibility for rotator cuff tears for pre-surgical planning.
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http://dx.doi.org/10.1016/j.jbiomech.2017.07.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5581304PMC
August 2017

Rotator cuff repair with a novel mesh suture: An ex vivo assessment of mechanical properties.

J Orthop Res 2018 03 21;36(3):987-992. Epub 2017 Aug 21.

Biomechanics Laboratory, Division of Orthopedic Research, Department of Orthopedic Surgery, Mayo Clinic, 200 First St SW, Rochester, Minnesota, 55905.

Surgical repair is a common treatment for rotator cuff tear; however, the retear rate is high. A high degree of suture repair strength is important to ensure rotator cuff integrity for healing. The purpose of this study was to compare the mechanical performance of rotator cuffs repaired with a mesh suture versus traditional polydioxanone suture II and FiberWire sutures in a canine in vitro model. Seventy-two canine shoulders were harvested. An infraspinatus tendon tear was created in each shoulder. Two suture techniques-simple interrupted sutures and two-row suture bridge-were used to reconnect the infraspinatus tendon to the greater tuberosity, using three different suture types: Mesh suture, polydioxanone suture II, or FiberWire. Shoulders were loaded to failure under displacement control at a rate of 20 mm/min. Failure load was compared between suture types and techniques. Ultimate failure load was significantly higher in the specimens repaired with mesh suture than with polydioxanone suture II or FiberWire, regardless of suture technique. There was no significant difference in stiffness among the six groups, with the exception that FiberWire repairs were stiffer than polydioxanone suture II repairs with the simple interrupted technique. All specimens failed by suture pull-out from the tendon. Based on our biomechanical findings, rotator cuff repair with the mesh suture might provide superior initial strength against failure compared with the traditional polydioxanone suture II or FiberWire sutures. Use of the mesh suture may provide increased initial fixation strength and decrease gap formation, which could result in improved healing and lower re-tear rates following rotator cuff repair. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:987-992, 2018.
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http://dx.doi.org/10.1002/jor.23668DOI Listing
March 2018

Intra-articular injection of a substance P inhibitor affects gene expression in a joint contracture model.

J Cell Biochem 2018 02 20;119(2):1326-1336. Epub 2017 Nov 20.

Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota.

Substance P (SP), a neurotransmitter released after injury, has been linked to deregulated tissue repair and fibrosis in musculoskeletal tissues and other organs. Although SP inhibition is an effective treatment for nausea, it has not been previously considered as an anti-fibrotic therapy. Although there are extensive medical records of individuals who have used SP antagonists, our analysis of human registry data revealed that patients receiving these antagonists and arthroplasty are exceedingly rare, thus precluding a clinical evaluation of their potential effects in the context of arthrofibrosis. Therefore, we pursued in vivo studies to assess the effect of SP inhibition early after injury on pro-fibrotic gene expression and contractures in an animal model of post-traumatic joint stiffening. Skeletally mature rabbits (n = 24) underwent surgically induced severe joint contracture, while injected with either fosaprepitant (a selective SP antagonist) or saline (control) early after surgery (3, 6, 12, and 24 h). Biomechanical testing revealed that differences in mean contracture angles between the groups were not statistically significant (P = 0.27), suggesting that the drug neither mitigates nor exacerbates joint contracture. However, microarray gene expression analysis revealed that mRNA levels for proteins related to cell signaling, pro-angiogenic, pro-inflammatory, and collagen matrix production were significantly different between control and fosaprepitant treated rabbits (P < 0.05). Hence, our study demonstrates that inhibition of SP alters expression of pro-fibrotic genes in vivo. This finding will motivate future studies to optimize interventions that target SP to reduce the formation of post-traumatic joint contractures.
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http://dx.doi.org/10.1002/jcb.26256DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6388635PMC
February 2018

Change in the Distance From the Axillary Nerve to the Glenohumeral Joint With Shoulder External Rotation or Abduction Position.

Hand (N Y) 2017 07 13;12(4):395-400. Epub 2016 Oct 13.

3 Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA.

Background: This study investigated whether axillary nerve (AN) distance to the inferior border of the humeral head and inferior glenoid would change while placing the glenohumeral joint in different degrees of external rotation and abduction.

Methods: A standard deltopectoral approach was performed on 10 fresh-frozen cadaveric specimens. The distance between AN and the inferior border of the humeral head and inferior glenoid while placing the shoulder in 0°, 45°, and 90° of external rotation or abduction was measured. Continuous variables for changes in AN position were compared with paired 2-tailed Student t test.

Results: The mean distance between the AN and the humeral head with the shoulder in 0°, 45°, and 90° of external rotation and 0° of abduction was 13.77 mm (SD 4.31), 13.99 mm (SD 4.12), and 16.28 mm (SD 5.40), respectively. The mean distance between the AN and glenoid with the shoulder in 0°, 45°, and 90° of external rotation was 16.33 mm (SD 3.60), 15.60 mm (SD 4.19), and 16.43 (SD 5.35), respectively. The mean distance between the AN and the humeral head with the shoulder in 0°, 45°, and 90° of abduction and 0° of external rotation was 13.76 mm (SD 4.31), 10.68 mm (SD 4.19), and 3.81 mm (SD 3.08), respectively. The mean distance between the AN and glenoid with the shoulder in 0°, 45°, and 90° of abduction was 16.33 mm (SD 3.60), 17.66 mm (SD 5.80), and 12.44 mm (SD 5.57), respectively.

Conclusions: The AN position relative to the inferior aspect of the glenohumeral joint does not significantly change despite position of external rotation. Increasing shoulder abduction over 45° decreases the distance from the glenohumeral joint to the AN and should be avoided.
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http://dx.doi.org/10.1177/1558944716668849DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5484444PMC
July 2017

The effect of scapular position on subacromial contact behavior: a cadaver study.

J Shoulder Elbow Surg 2017 May 11;26(5):861-869. Epub 2017 Jan 11.

Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA. Electronic address:

Background: Patients with subacromial impingement were reported to show abnormal scapular positions during shoulder elevation. However, the relationship between the scapular positions and subacromial impingement is unclear. The purpose of this study was to biomechanically determine the effect of scapular position on subacromial contact behavior by using fresh frozen cadavers.

Methods: The peak contact pressure on the coracoacromial arch was measured with a flexible tactile force sensor in 9 fresh frozen cadaver shoulders. The measurement was performed during passive glenohumeral elevation in the scapular plane ranging from 30° to 75°. The scapular downward and internal rotations and anterior tilt were simulated by tilting the scapula in 5° increments up to 20°. The measurement was also performed with combination of scapular downward and internal rotations and anterior tilt positions.

Results: The peak contact pressure decreased linearly with anterior tilt, and a significant difference between neutral scapular position (1.06 ± 0.89 MPa) and anterior tilt by 20° (0.46 ± 0.18 MPa) was observed (P < .05). However, the scapular positioning in the other directions did not change the peak contact pressure significantly. Furthermore, any combination of abnormal scapular positions did not affect peak contact pressure significantly.

Conclusion: Scapular anterior tilt decreased peak contact pressure during passive shoulder elevation. In addition, scapular downward and internal rotations had little effect on peak contact pressure. The abnormal scapular motion reported in previous studies might not be directly related to symptoms caused by subacromial impingement.
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http://dx.doi.org/10.1016/j.jse.2016.10.009DOI Listing
May 2017

Effect of smoking on complications following primary shoulder arthroplasty.

J Shoulder Elbow Surg 2017 Jan 31;26(1):1-6. Epub 2016 Oct 31.

Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA. Electronic address:

Background: The purpose of this study was to examine the effect of smoking on the incidence of complications after primary anatomic total shoulder arthroplasty (TSA) and reverse shoulder arthroplasty (RSA).

Methods: All patients who underwent primary TSA or RSA at our institution between 2002 and 2011 and had a minimum 2-year follow-up were included. Smoking status was assessed at the time of surgery. Current smokers, former smokers, and nonsmokers were compared for periprosthetic infection, fractures (intraoperative and postoperative), and loosening after surgery.

Results: The cohort included 1834 shoulders in 1614 patients (814 in smokers and 1020 in nonsmokers). Complications occurred in 73 patients (75 shoulders; 44 in smokers and 31 in nonsmokers). There were 20 periprosthetic infections (16 in smokers and 4 in nonsmokers), 27 periprosthetic fractures (14 in smokers and 13 in nonsmokers), and 28 loosenings (14 in smokers and 14 in nonsmokers). Smokers had lower periprosthetic infection-free survival rates (95.3%-99.4% at 10 years; P = .001) and overall complication-free survival rates (78.4%-90.2%; P = .012) than nonsmokers. Multivariable analyses showed that both current and former smokers had significantly higher risk of periprosthetic infection in comparison with nonsmokers (hazard ratio [HR], 7.27 and 4.56, respectively). In addition, current smokers showed a higher risk of postoperative fractures than both former smokers (HR, 3.63) and nonsmokers (HR, 6.99).

Conclusions: This study demonstrates that smoking is a significant risk factor of complications after TSA and RSA. These findings emphasize the need for preoperative collaborative interventions, including smoking cessation programs.
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http://dx.doi.org/10.1016/j.jse.2016.09.011DOI Listing
January 2017

Repairing the Capsule to the Transferred Coracoid Preserves External Rotation in the Modified Latarjet Procedure.

J Bone Joint Surg Am 2016 Sep;98(17):1484-9

Department of Orthopedic Surgery (Y.I., A.W.H., J.W.S., S.P.S., and K.-N.A.) and Department of Physical Medicine and Rehabilitation (K.D.Z.), Mayo Clinic, Rochester, Minnesota

Background: It is not clear whether the anterior capsule should be repaired to the coracoid process or to the native glenoid during the modified Latarjet procedure. We investigated joint stability and range of motion of the shoulder after the modified Latarjet procedure with both of these methods of capsular repair.

Methods: Eighteen fresh-frozen cadaveric shoulders were used. After a Bankart lesion and 6-mm glenoid defect were created, the coracoid process was transferred to the glenoid and fixed with screws. The anterior capsule was repaired either to the coracoid process (coracoid group) or to the native glenoid (glenoid group). The ranges of internal and external axial rotation were measured with the arm at 0° and 60° of glenohumeral abduction. The range of motion was measured with a constant torque of 200 N-mm. Joint stability was measured using a custom stability testing device. The stability ratio in the anterior-posterior direction was measured with the arm at maximal external rotation and neutral rotation.

Results: The range of external rotation was greater at both 0° and 60° of abduction in the coracoid group compared with the glenoid group (p < 0.05). The range of internal rotation was not significantly different between groups. The end-range stability ratio was not significantly different between groups, but the mid-range stability ratio was significantly greater in the glenoid group.

Conclusions: Because the difference in the mid-range stability may not be clinically relevant, we recommend repairing the capsule to the coracoid, as that preserves the range of motion in external rotation.

Clinical Relevance: Repairing the capsule to the transferred coracoid during the modified Latarjet procedure appears to be beneficial to avoid the limited range of motion in external rotation, but the direct contact of the humeral head and the transferred coracoid might confer a risk of osteoarthritis. Long-term consequences in the clinical setting need to be clarified.
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http://dx.doi.org/10.2106/JBJS.15.01069DOI Listing
September 2016

Biomechanical Effect of Margin Convergence Techniques: Quantitative Assessment of Supraspinatus Muscle Stiffness.

PLoS One 2016 1;11(9):e0162110. Epub 2016 Sep 1.

Biomechanics laboratory, Division of Orthopedic Research, Mayo clinic, Rochester, Minnesota, United States of America.

Although the margin convergence (MC) technique has been recognized as an option for rotator cuff repair, little is known about the biomechanical effect on repaired rotator cuff muscle, especially after supplemented footprint repair. The purpose of this study was to assess the passive stiffness changes of the supraspinatus (SSP) muscle after MC techniques using shear wave elastography (SWE). A 30 × 40-mm U-shaped rotator cuff tear was created in 8 cadaveric shoulders. Each specimen was repaired with 6 types of MC technique (1-, 2-, 3-suture MC with/without footprint repair, in a random order) at 30° glenohumeral abduction. Passive stiffness of four anatomical regions in the SSP muscle was measured based on an established SWE method. Data were obtained from the SSP muscle at 0° abduction under 8 different conditions: intact (before making a tear), torn, and postoperative conditions with 6 techniques. MC techniques using 1-, or 2-suture combined with footprint repair showed significantly higher stiffness values than the intact condition. Passive stiffness of the SSP muscle was highest after a 1-suture MC with footprint repair for all regions when compared among all repair procedures. There was no significant difference between the intact condition and a 3-suture MC with footprint repair. MC techniques with single stitch and subsequent footprint repair may have adverse effects on muscle properties and tensile loading on repair, increasing the risk of retear of repairs. Adding more MC stitches could reverse these adverse effects.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0162110PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5008765PMC
August 2017

Distal biceps tendon history, updates, and controversies: from the closed American Shoulder and Elbow Surgeons meeting-2015.

J Shoulder Elbow Surg 2016 Oct 10;25(10):1717-30. Epub 2016 Aug 10.

Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA.

Understanding of the distal biceps anatomy, mechanics, and biology during the last 75 years has greatly improved the physician's ability to advise and to treat patients with ruptured distal tendons. The goal of this paper is to review the past and current advances on complete distal biceps ruptures as well as controversies and future directions that were discussed and debated during the closed American Shoulder and Elbow Surgeons meeting in 2015.
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http://dx.doi.org/10.1016/j.jse.2016.05.025DOI Listing
October 2016

Irreducible anteromedial radial head dislocation caused by the brachialis tendon: a case report.

J Shoulder Elbow Surg 2016 08;25(8):e232-5

Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA. Electronic address:

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http://dx.doi.org/10.1016/j.jse.2016.04.017DOI Listing
August 2016
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