Comparing internal fixation constructs for scapular spine insufficiency fractures following reverse shoulder arthroplasty

Abstract

Introduction: There is limited research on the surgical management techniques for scapular spine fractures after reverse shoulder arthroplasty (RTSA). As such, the purpose of this in vitro biomechanical study was to compare 4 fixation constructs to stabilize scapular spine insufficiency fractures. Methods: Twelve paired fresh-frozen cadaveric scapulae (N ¼ 24) were randomized into 4 fixation groups: subcutaneous border plating (AE hook) and supraspinatus fossa plating (AE hook). A Levy type II fracture was simulated. Each specimen was cyclically loaded incrementally up to 700 N in 50 N steps or until failure. Between 50 and 200 N construct stiffness was measured, and stability failure was defined as displacement greater than 2.5 mm. Results: Seventy-nine percent (19 of 24) of the specimens failed before the maximum load of 700 N. The average survival force with subcutaneous border plating was 480 AE 80 N compared with 380 AE 30 N for supraspinatus fossa plating (P ¼ .3). Fixation construct failure was significantly more likely with fossa plating over subcutaneous plating (P ¼ .012). The presence of the lateral plate hook was beneficial in preventing failure of the lateral acromion (P ¼ .016). Conclusion: When appropriately surgically indicated, a dorsally applied plate to the subcutaneous border of the scapular spine with a lateral inferior supporting hook may be advantageous for internal fixation of type II scapular spine insufficiency fractures after RTSA.

Double plating is associated with higher fixation strength than single plating in osteoporotic fractures of the scapular spine: a biomechanical study

“…More recently, Ting et al could demonstrate that subcutaneous border plating is biomechanically superior to plating in the supraspinatus fossa [ 22 ]. Both studies evaluated measures for additional fracture fixation.…”

Treatment strategies for scapular spine fractures: a scoping review

“… 37 Another biomechanical study, by Ting et al, reported that direct subcutaneous plating of the scapular spine is more stable than supraspinatus fossa plating. 38 In our cohort, the patients achieved good results concerning range of motion after operative treatment. 13 – 17 In only one case, the patient had a slightly limited range of motion and mild pain.…”

Acromial and Scapular Spine Fractures following Reverse Total Shoulder Arthroplasty—A Systematic Review of Fixation Constructs and Techniques

“…Within the identified cohort of 18 fractures, one was classified as a Levy Type I fracture [ 16 ], 10 were Levy Type II fractures [ 17 , 30 , 31 , 32 , 33 ], and the remaining 7 fractures were defined as Levy Type III [ 18 , 29 , 34 ]. Fractures were classified according to Levy et al in two studies (four fractures) [ 13 , 17 , 19 , 34 ], with Levy classification ascertained by the authors for the other seven studies.…”

“…Positioning of the plates has also been investigated and it has been shown that plates can be placed superiorly (along the supraspinatus fossa), posteriorly (along the scapular spine) or caudally (along the infraspinatus fossa) [ 13 , 25 , 26 , 35 ]. For single plating, applying the plate over the posterior aspect of the scapular spine might be the strongest option [ 13 ]. When dual plating is performed, placing the plates over the posterior and caudal aspect of the scapular spine might provide the strongest fixation [ 25 , 35 ].…”

“…Unfavorable design features such as glenoid-sided lateralization make acromial fractures challenging to treat [ 12 , 13 ]. Other structural factors which may undermine healing include base-plate screws potentially weakening the scapular spine, poor bone stock and plates being positioned on the tension side of the fracture (increasing screw cut-out risk) [ 14 ].…”