TY - JOUR
T1 - Biomechanical comparison of zoned-conformity glenoid versus standard glenoid in total shoulder arthroplasty
T2 - impact on rotator cuff strain and glenohumeral translation
AU - Wright, Melissa A.
AU - Abbasi, Pooyan
AU - Murthi, Anand M.
N1 - Funding Information:
Anand M. Murthi is a board or committee member of American Academy of Orthopaedic Surgeons, American Shoulder and Elbow Surgeons, and American Shoulder and Elbow Surgeons Foundation; is on the editorial or governing board of American Journal of Orthopedics, Current Orthopaedic Practice, Journal of Shoulder and Elbow Arthroplasty, and Journal of Shoulder and Elbow Surgery; receives publishing royalties and financial or material support from American Journal of Orthopedics, Current Orthopaedic Practice, and Wolters Kluwer Health–Lippincott Williams & Wilkins receives research support from Arthrex; receives intellectual property royalties from Globus Medical and Ignite Orthopedics; is a paid consultant for Globus Medical and Ignite Orthopedics; and is on the scientific advisory board of Catalyst Shoulder.
Publisher Copyright:
© 2021 Journal of Shoulder and Elbow Surgery Board of Trustees
PY - 2021/7
Y1 - 2021/7
N2 - Background: Current standard total shoulder arthroplasty glenoid implants allow for high levels of glenohumeral mismatch and associated high levels of humeral head translation to improve range of motion and reduce rim stresses on the glenoid. However, high levels of glenohumeral mismatch could also increase glenoid edge loading, eccentric wear, and rotator cuff strain. A zoned-conformity glenoid may be able to reduce the forces on the rotator cuff and glenoid. We compared rotator cuff strain and glenohumeral translation between a standard glenoid (SG) with moderate glenohumeral mismatch and a zoned-conformity glenoid (conforming glenoid [CG]) that limits mismatch. We hypothesized that the CG would have lower levels of strain on the rotator cuff and lower levels of humeral head translation compared with the SG. Methods: Eight fresh frozen cadaveric shoulders, aged 72 years (range, 67-76 years), were used in this biomechanical study. The specimens were first tested in the intact state. We cycled them 3 times from 0° to 60° of abduction and measured the superiorly-inferiorly and anteriorly-posteriorly directed forces at the joint, compressive forces applied to the glenoid, and humeral head translation. The specimens were then implanted with a standard press-fit humeral component and a polyethylene glenoid with 3 peripherally cemented pegs and a central press-fit peg. Testing was repeated. Finally, the SG was removed, the CG was implanted, and each specimen was tested a third time. Results: The average superiorly directed force at the glenohumeral joint was significantly lower in the intact and CG groups (18.1 ± 18.6 N and 19.8 ± 16.2 N, respectively) than in the SG group (29.3 ± 21.9 N, P = .024). The maximum force directed against the glenoid was also significantly lower in the CG group (87.6 ± 11.7 N) than in the SG (96.0 ± 7.3 N) and intact (98.9 ± 16.5 N) groups (P = .035). No difference was observed in humeral head translation in the anterior-posterior plane from 0° to 60° of abduction (P = .998) or in the superior-inferior plane (P = .999). Conclusion: A zoned-conformity glenoid was associated with similar humeral head translation but significantly lower superior forces against the rotator cuff and a significantly lower maximum force against the glenoid compared with an SG implant. These biomechanical findings suggest that a zoned-conformity implant warrants further study in the effort to maintain humeral head translation while reducing rotator cuff and glenoid forces for successful outcomes of total shoulder arthroplasty.
AB - Background: Current standard total shoulder arthroplasty glenoid implants allow for high levels of glenohumeral mismatch and associated high levels of humeral head translation to improve range of motion and reduce rim stresses on the glenoid. However, high levels of glenohumeral mismatch could also increase glenoid edge loading, eccentric wear, and rotator cuff strain. A zoned-conformity glenoid may be able to reduce the forces on the rotator cuff and glenoid. We compared rotator cuff strain and glenohumeral translation between a standard glenoid (SG) with moderate glenohumeral mismatch and a zoned-conformity glenoid (conforming glenoid [CG]) that limits mismatch. We hypothesized that the CG would have lower levels of strain on the rotator cuff and lower levels of humeral head translation compared with the SG. Methods: Eight fresh frozen cadaveric shoulders, aged 72 years (range, 67-76 years), were used in this biomechanical study. The specimens were first tested in the intact state. We cycled them 3 times from 0° to 60° of abduction and measured the superiorly-inferiorly and anteriorly-posteriorly directed forces at the joint, compressive forces applied to the glenoid, and humeral head translation. The specimens were then implanted with a standard press-fit humeral component and a polyethylene glenoid with 3 peripherally cemented pegs and a central press-fit peg. Testing was repeated. Finally, the SG was removed, the CG was implanted, and each specimen was tested a third time. Results: The average superiorly directed force at the glenohumeral joint was significantly lower in the intact and CG groups (18.1 ± 18.6 N and 19.8 ± 16.2 N, respectively) than in the SG group (29.3 ± 21.9 N, P = .024). The maximum force directed against the glenoid was also significantly lower in the CG group (87.6 ± 11.7 N) than in the SG (96.0 ± 7.3 N) and intact (98.9 ± 16.5 N) groups (P = .035). No difference was observed in humeral head translation in the anterior-posterior plane from 0° to 60° of abduction (P = .998) or in the superior-inferior plane (P = .999). Conclusion: A zoned-conformity glenoid was associated with similar humeral head translation but significantly lower superior forces against the rotator cuff and a significantly lower maximum force against the glenoid compared with an SG implant. These biomechanical findings suggest that a zoned-conformity implant warrants further study in the effort to maintain humeral head translation while reducing rotator cuff and glenoid forces for successful outcomes of total shoulder arthroplasty.
KW - Basic Science Study
KW - Biomechanics
KW - glenohumeral biomechanics
KW - glenohumeral mismatch
KW - glenoid wear
KW - rotator cuff strain
KW - Shoulder arthroplasty
UR - http://www.scopus.com/inward/record.url?scp=85105246836&partnerID=8YFLogxK
U2 - 10.1016/j.jse.2021.03.137
DO - 10.1016/j.jse.2021.03.137
M3 - Article
C2 - 33774167
AN - SCOPUS:85105246836
SN - 1058-2746
VL - 30
SP - S109-S115
JO - Journal of Shoulder and Elbow Surgery
JF - Journal of Shoulder and Elbow Surgery
IS - 7
ER -