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Krishnan P, Koh J, Pradhan S, Bobko A, Athiviraham A, Amirouche F. Analysis of abduction moment arms after rotator cuff tear and acellular dermal matrix allograft reconstruction. J Shoulder Elbow Surg 2023; 32:2207-2213. [PMID: 37276919 DOI: 10.1016/j.jse.2023.04.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Revised: 04/19/2023] [Accepted: 04/24/2023] [Indexed: 06/07/2023]
Abstract
BACKGROUND Biomechanical testing of abduction moment arms presents a useful method to assess the contributions of individual rotator cuff muscles to glenohumeral function. This study aimed to investigate the changes in abduction moment arms after the treatment of supraspinatus tears with superior capsular reconstruction (SCR), bursal acromial reconstruction (BAR), and a combined SCR-BAR procedure, all with human dermal allograft. METHODS We tested 7 fresh-frozen cadaveric specimens under 6 conditions: (1) intact, (2) 50% supraspinatus tear (partial tear), (3) 100% supraspinatus tear, (4) SCR, (5) SCR combined with BAR, and (6) BAR. In each condition, the moment arms for the individual muscles of the teres minor, subscapularis, and infraspinatus were calculated throughout 90° of abduction using a motion capture system. Analysis of variance and post hoc Tukey testing were performed to determine significance. RESULTS In the teres minor, the moment arms in the SCR (11.9 mm), BAR (10.1 mm), and SCR-BAR (11.9 mm) conditions were greater than those in the intact (8.5 mm; P = .001, P = .001, and P = .001, respectively), partial tear (9.1 mm; P = .001, P = .128, and P = .001, respectively), and complete tear (8.8 mm; P = .001, P = .011, and P = .001, respectively) conditions. Similarly, in the subscapularis, the moment arms in the SCR (13.4 mm), BAR (13.8 mm), and SCR-BAR (13.5 mm) conditions were greater than those in the intact (10.6 mm; P = .006, P = .001, and P = .003, respectively) and partial tear (10.4 mm; P = .006, P = .001, and P = .003, respectively) conditions. In the teres minor, the SCR (11.9 mm) and SCR-BAR (11.9 mm) conditions were also found to have significantly increased moment arms compared with the BAR condition (10.1 mm; P = .001 and P = .001, respectively). In the infraspinatus, the BAR condition (13.8 mm) was found to have a significantly decreased moment arm compared with the partial tear condition (15.8 mm, P = .026), with no other significant findings between conditions. CONCLUSION Our results suggest that the moment arm contributions of the individual muscles comprising the rotator cuff can change after reconstruction to compensate for tears. SCR and SCR-BAR increase the moment arms in the teres minor and subscapularis, potentially allowing for increased abduction ability.
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Affiliation(s)
- Pranav Krishnan
- Pritzker School of Medicine, The University of Chicago, Chicago, IL, USA.
| | - Jason Koh
- Department of Orthopaedic Surgery, NorthShore University Health System, Chicago, IL, USA
| | - Sonia Pradhan
- Department of Orthopaedics, University of Illinois at Chicago, Chicago, IL, USA
| | - Aimee Bobko
- Department of Orthopaedics, University of Illinois at Chicago, Chicago, IL, USA
| | | | - Farid Amirouche
- Department of Orthopaedics, University of Illinois at Chicago, Chicago, IL, USA; Department of Orthopaedic Surgery, NorthShore University Health System, Chicago, IL, USA
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Knighton TW, Chalmers PN, Sulkar HJ, Aliaj K, Tashjian RZ, Henninger HB. Reverse total shoulder glenoid component inclination affects glenohumeral kinetics during abduction: a cadaveric study. J Shoulder Elbow Surg 2022; 31:2647-2656. [PMID: 35931329 PMCID: PMC9669184 DOI: 10.1016/j.jse.2022.06.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 06/02/2022] [Accepted: 06/27/2022] [Indexed: 02/01/2023]
Abstract
BACKGROUND Optimal implant placement in reverse total shoulder arthroplasty (rTSA) remains controversial. Specifically, the optimal glenoid inclination is unknown. Therefore, a cadaveric shoulder simulator with 3-dimentional human motion specific to rTSA was used to study joint contact and muscle forces as a function of glenoid component inclination. METHODS Eight human cadaver shoulders were tested before and after rTSA implantation. Scapular plane abduction kinematics from control subjects and those with rTSA drove a cadaveric shoulder simulator with 3-dimentional scapulothoracic and glenohumeral motion. Glenoid inclination varied from -20° to +20°. Outputs included compression, superior-inferior (S/I) shear, and anterior-posterior shear forces from a 6° of freedom load cell in the joint, and deltoid and rotator cuff muscle forces. Data were evaluated with statistical parametric mapping and t-tests. RESULTS Inferior glenoid inclination (-) reduced S/I shear by up to 125% relative to superior inclination, with similar compression to the neutral condition (0°). Superior inclinations (+) increased the S/I shear force by approximately the same magnitude, yet decreased compression by 25% in the most superior inclination (+20°). There were few differences in deltoid or rotator cuff forces due to inclination. Only the middle deltoid decreased by approximately 7% for the most inferior inclination (-20°). Compared with native shoulders, the neutral (0°) rTSA inclination showed reduced forces of 30%-75% in the anterior deltoid and a trend toward decreased forces in the middle deltoid. Force demands on the rotator cuff varied as a function of elevation, with a trend toward increased forces in rTSA at peak glenohumeral elevation. CONCLUSIONS Inferior inclination reduces superior shear forces, without influencing compression. Superior inclination increased S/I shear, while decreasing compression, which may be a source of component loosening and joint instability after rTSA. Inferior inclination of the rTSA glenoid may reduce the likelihood of glenoid loosening by reducing the magnitude of cyclic shear and compressive loading during arm elevation activities, although this may be altered by specific-subject body habitus and motion. These factors are especially important in revision rTSA or glenoid bone grafting where there is already a 3-fold increase in glenoid baseplate loosening vs. primary rTSA.
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Affiliation(s)
- Tyler W Knighton
- Department of Orthopaedics, University of Utah, Salt Lake City, UT, USA; Department of Mechanical Engineering, University of Utah, Salt Lake City, UT, USA
| | - Peter N Chalmers
- Department of Orthopaedics, University of Utah, Salt Lake City, UT, USA
| | - Hema J Sulkar
- Department of Orthopaedics, University of Utah, Salt Lake City, UT, USA; Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA
| | - Klevis Aliaj
- Department of Orthopaedics, University of Utah, Salt Lake City, UT, USA; Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA
| | - Robert Z Tashjian
- Department of Orthopaedics, University of Utah, Salt Lake City, UT, USA
| | - Heath B Henninger
- Department of Orthopaedics, University of Utah, Salt Lake City, UT, USA; Department of Mechanical Engineering, University of Utah, Salt Lake City, UT, USA; Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA.
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Barragan Echenique DM, Dolan MT, Koh JL, Goldberg BA, Amirouche F. Infraspinatus Muscle Fiber Moment Arms During Abduction: A Biomechanical Comparison of Values for Intact Rotator Cuff, Supraspinatus Tear, Superior Capsular Reconstruction, and Reverse Total Shoulder Arthroplasty. Orthop J Sports Med 2022; 10:23259671221098378. [PMID: 35651480 PMCID: PMC9149620 DOI: 10.1177/23259671221098378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Accepted: 02/08/2022] [Indexed: 11/24/2022] Open
Abstract
Background: Lines of action of the superior, middle, and inferior infraspinatus muscle
fibers work together to produce moment arms that change throughout abduction
in an intact shoulder, after a supraspinatus tear, and after superior
capsular reconstruction (SCR) and reverse total shoulder arthroplasty
(rTSA). Purpose: To use moment arm values to indicate the efficacy of SCR and rTSA to restore
infraspinatus function during shoulder abduction. Study Design: Descriptive laboratory study. Methods: A total of 5 human cadaveric shoulders placed in a testing apparatus were
each actively abducted (0°-90°) under the following 4 conditions: intact,
complete supraspinatus tear, SCR, and rTSA. The 3-dimensional coordinates of
points were tracked along the origin and insertion of the superior, middle,
and inferior infraspinatus fibers during abduction. Moment arm values were
calculated using the origin-insertion method to determine abduction
contribution of infraspinatus fiber sections. Analysis of variance and post
hoc Tukey testing were used to compare differences in moment arms between
the 4 conditions and between fiber sections. Results: In the intact condition, the superior infraspinatus fibers had an abduction
moment that decreased with elevation until shifting to adduction.
Conversely, the middle and inferior fibers had an adduction moment that
turned to abduction (mean moment arm values from 0° to 90°: inferior, from
–5.9 to 19.4 mm; middle, from –4.7 to 15.9 mm; superior, from 5.6 to –5.1
mm; P < .05). After a supraspinatus tear, superior
fibers lacked any torque, and inferior and middle fibers lost adduction
potential (inferior, from 4.8 to 14.0 mm; middle, from –0.2 to 9.6 mm;
superior, from 1.0 to 0.7 mm; P < .05). SCR restored the
initial superior fiber abduction moment (5.6 mm at 0°; P
< .05); middle and inferior fibers had some restoration but were weaker
than intact fibers. Loss of abduction moment in all fibers was seen with
rTSA (inferior, from –9.6 to –1.6 mm; middle, from –10.5 to –3.6 mm;
superior, from –1.7 to –4.6 mm; P < .05). Conclusion: Infraspinatus fiber groups had different and inverse moment arms during
scapular plane elevation. SCR most closely resembled the intact shoulder,
whereas rTSA transformed the infraspinatus into an adductor. Clinical Relevance: These results support the efficacy of SCR at restoring biomechanical muscle
function and suggest that the changes in moment arms for each fiber group be
considered when choosing treatment modalities and rehabilitation protocols
after rotator cuff tear.
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Affiliation(s)
| | - Martine T. Dolan
- Department of Orthopaedic Surgery, University of Illinois, Chicago, Illinois, USA
| | - Jason L. Koh
- Orthopaedic and Spine Institute, Department of Orthopaedic Surgery, Northshore University HealthSystem, an Affiliate of University of Chicago Pritzker School of Medicine, Evanston, Illinois, USA
- Department of Orthopaedics, Shoulder and Elbow Surgery, University of Chicago, Chicago, Illinois, USA
| | - Benjamin A. Goldberg
- Department of Orthopaedic Surgery, University of Illinois, Chicago, Illinois, USA
| | - Farid Amirouche
- Department of Orthopaedic Surgery, University of Illinois, Chicago, Illinois, USA
- Orthopaedic and Spine Institute, Department of Orthopaedic Surgery, Northshore University HealthSystem, an Affiliate of University of Chicago Pritzker School of Medicine, Evanston, Illinois, USA
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Labib M, Amirouche F, Pradhan S, Bobko A, Koh J. A Biomechanical Analysis of Shoulder Muscle Excursions During Abduction, After the Treatment of Massive Irreparable Rotator Cuff Tears Using Superior Capsular Reconstruction (SCR), Bursal Acromial Reconstruction (BAR), and SCR with BAR. J Shoulder Elb Arthroplast 2022; 6:24715492221109001. [PMID: 35782774 PMCID: PMC9240589 DOI: 10.1177/24715492221109001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 05/19/2022] [Accepted: 06/02/2022] [Indexed: 01/17/2023] Open
Abstract
Introduction Current understanding of the biomechanical effects of treatment options for irreparable rotator cuff (RC) tears is lacking. This study examines how shoulder muscle lengths and excursions are affected by superior capsular reconstruction (SCR), bursal acromial reconstruction (BAR), and SCR with BAR, following a complete supraspinatus tear. Method Six fresh-frozen cadaveric shoulders were examined. Deltoid and RC muscle lengths were measured at 0, 30, 45, 60, and 90° of shoulder abduction under six conditions: (1) intact, (2) partially torn supraspinatus, (3) completely torn supraspinatus, (4) SCR, (5) SCR with BAR, and (6) BAR. Muscle excursions from 0–90° of abduction were then calculated. Results Subscapularis muscle lengths after SCR, BAR, and SCR with BAR were significantly greater (post-hoc Tukey HSD test; p < .01) compared to the other conditions. Supraspinatus, infraspinatus, teres minor, and deltoid lengths were not significantly different (ANOVA test; p > .01) between the conditions. All muscle excursions remained statistically similar between the conditions (ANOVA test; p > .01). Conclusion These findings demonstrate that the use of SCR, BAR, or SCR with BAR for a complete supraspinatus tear, may increase subscapularis muscle length while maintaining other shoulder muscle lengths. An increase in subscapularis length can allow for more effective subscapularis muscle strengthening and increased compensatory function in the long term. Additionally, all shoulder muscle excursions are preserved after partial or complete supraspinatus tears and after SCR, BAR, or SCR with BAR. Therefore, these surgical treatments can initially normalize shoulder muscle function during 0–90° of abduction, after an irreparable supraspinatus tear.
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Affiliation(s)
- Michael Labib
- Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Farid Amirouche
- Department of Orthopaedics, University of Illinois, Chicago, IL, USA
- Department of Orthopaedics, NorthShore University HealthSystem, Evanston, IL, USA
| | - Sonia Pradhan
- Department of Orthopaedics, University of Illinois, Chicago, IL, USA
| | - Aimee Bobko
- Department of Orthopaedics, University of Illinois, Chicago, IL, USA
| | - Jason Koh
- Department of Orthopaedics, NorthShore University HealthSystem, Evanston, IL, USA
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