PMID- 37419441
OWN - NLM
STAT- MEDLINE
DCOM- 20231114
LR  - 20231114
IS  - 1532-6500 (Electronic)
IS  - 1058-2746 (Linking)
VI  - 32
IP  - 12
DP  - 2023 Dec
TI  - Impact of reverse shoulder arthroplasty design and patient shoulder size on 
      moment arms and muscle fiber lengths in shoulder abductors.
PG  - 2550-2560
LID - S1058-2746(23)00495-0 [pii]
LID - 10.1016/j.jse.2023.05.035 [doi]
AB  - BACKGROUND: Reverse shoulder arthroplasty (RSA) increases the moment arm of the 
      deltoid; however, there is limited knowledge on the accompanying changes in 
      muscle architecture that play a role in muscle force production. The purpose of 
      this study was to use a geometric shoulder model to evaluate the anterior 
      deltoid, middle deltoid, and supraspinatus regarding (1) the differences in 
      moment arms and muscle-tendon lengths in small, medium, and large native 
      shoulders and (2) the impact of 3 RSA designs on moment arms, muscle fiber 
      lengths, and force-length (F-L) curves. METHODS: A geometric model of the native 
      glenohumeral joint was developed, validated, and adjusted to represent small, 
      medium, and large shoulders. Moment arms, muscle-tendon lengths, and normalized 
      muscle fiber lengths were assessed for the supraspinatus, anterior deltoid, and 
      middle deltoid from 0 degrees  to 90 degrees  of abduction. RSA designs were modeled and 
      virtually implanted, including a lateralized glenosphere with an inlay 135 degrees  
      humeral component (lateral glenoid-medial humerus [LGMH]), a medialized 
      glenosphere with an onlay 145 degrees  humeral component (medial glenoid-lateral humerus 
      [MGLH]), and a medialized glenosphere with an inlay 155 degrees  humeral component 
      (medial glenoid-medial humerus [MGMH]). Descriptive statistics were used to 
      compare moment arms and normalized muscle fiber lengths. RESULTS: As shoulder 
      size increased, the moment arms and muscle-tendon lengths for the anterior 
      deltoid, middle deltoid, and supraspinatus increased. All RSA designs achieved 
      greater moment arms for the anterior and middle deltoid, with the MGLH design 
      achieving the largest increase. The resting normalized muscle fiber length of the 
      anterior and middle deltoid was substantially increased in the MGLH (1.29) and 
      MGMH (1.24) designs, shifting the operating ranges of these muscles to the 
      descending portions of their F-L curves, whereas the LGMH design maintained a 
      resting deltoid fiber length (1.14) and operating range similar to the native 
      shoulder. All RSA designs demonstrated a decrease in the native supraspinatus 
      moment arm in early abduction, with the largest decrease in the MGLH design 
      (-59%) and minimal decrease in the LGMH design (-14%). The supraspinatus operated 
      on the ascending limb of its F-L curve in the native shoulder and remained on 
      this portion of the F-L curve for all RSA designs. CONCLUSION: Although the MGLH 
      design maximizes the abduction moment arm for the anterior and middle deltoid, 
      overlengthening of the muscle may compromise deltoid muscle force production by 
      forcing the muscle to operate on the descending portion of its F-L curve. In 
      contrast, the LGMH design increases the abduction moment arm for the anterior and 
      middle deltoid more modestly while allowing the muscle to operate near the 
      plateau of its F-L curve and maximizing its force-producing potential.
CI  - Copyright (c) 2023 Journal of Shoulder and Elbow Surgery Board of Trustees. 
      Published by Elsevier Inc. All rights reserved.
FAU - Levin, Jay M
AU  - Levin JM
AD  - Department of Orthopaedic Surgery, Duke University Medical Center, Durham, NC, 
      USA. Electronic address: jay.m.levin@duke.edu.
FAU - Pugliese, Mattia
AU  - Pugliese M
AD  - Department of Orthopaedic Surgery, Concordia Hospital, Rome, Italy.
FAU - Gobbi, Fabrizio
AU  - Gobbi F
AD  - Department of Orthopaedic Surgery, Concordia Hospital, Rome, Italy.
FAU - Pandy, Marcus G
AU  - Pandy MG
AD  - Department of Mechanical Engineering, The University of Melbourne, Parkville, 
      VIC, Australia.
FAU - Di Giacomo, Giovanni
AU  - Di Giacomo G
AD  - Department of Orthopaedic Surgery, Concordia Hospital, Rome, Italy.
FAU - Frankle, Mark A
AU  - Frankle MA
AD  - Shoulder & Elbow Service, Florida Orthopaedic Institute, Tampa, FL, USA.
LA  - eng
PT  - Journal Article
DEP - 20230705
PL  - United States
TA  - J Shoulder Elbow Surg
JT  - Journal of shoulder and elbow surgery
JID - 9206499
SB  - IM
MH  - Humans
MH  - Shoulder/surgery
MH  - *Arthroplasty, Replacement, Shoulder
MH  - Biomechanical Phenomena
MH  - *Shoulder Joint/surgery/physiology
MH  - Muscle Fibers, Skeletal
MH  - Range of Motion, Articular/physiology
OTO - NOTNLM
OT  - Reverse shoulder arthroplasty
OT  - biomechanical
OT  - center of rotation
OT  - force-length
OT  - lateralize
OT  - model
OT  - muscle architecture
OT  - shoulder
EDAT- 2023/07/08 10:42
MHDA- 2023/11/14 06:42
CRDT- 2023/07/07 19:29
PHST- 2023/03/03 00:00 [received]
PHST- 2023/05/17 00:00 [revised]
PHST- 2023/05/28 00:00 [accepted]
PHST- 2023/11/14 06:42 [medline]
PHST- 2023/07/08 10:42 [pubmed]
PHST- 2023/07/07 19:29 [entrez]
AID - S1058-2746(23)00495-0 [pii]
AID - 10.1016/j.jse.2023.05.035 [doi]
PST - ppublish
SO  - J Shoulder Elbow Surg. 2023 Dec;32(12):2550-2560. doi: 10.1016/j.jse.2023.05.035. 
      Epub 2023 Jul 5.