Single or Double Plating for Acromial Type III Fractures: Biomechanical Comparison of Load to Failure and Fragment Motion

Abstract

Background: Acromial Levy III fractures after inverse shoulder arthroplasty occur in up to 7% of patients. To date, it is not clear how these fractures should be treated as clinical outcomes remain unsatisfactory. The aim of this study was to evaluate the biomechanical performance of three different plating methods of type III acromion fractures. Methods: Levy III fractures in synthetic scapulae were fixed with three different methods. Angular stable locking plates were placed on the spina scapula to bridge the fracture either dorsally, caudally, or on both aspects by double plating. In a biomechanical experiment, the pull of the deltoid muscle at 40° abduction of the arm was simulated by cyclic loading with increasing load levels until failure. Failure load, cycles to failure, and fragment motions were evaluated. Results: The results showed that double plating (350 ± 63 N) withstood the highest loads until failure, followed by dorsal (292 ± 20 N) and caudal (217 ± 49 N) plating. Similarly, double plating showed significantly smaller fragment movement than the other two groups. Conclusions: Double plating appeared to provide the largest biomechanical stability in type III acromion fracture under arm abduction. Caudal plating in contract resulted in insufficient fracture stability and early failure and can thus not be recommended from a biomechanical point of view.

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

“…In a study by Katthagen et al [ 25 ], dual plating with two LCP plates revealed superior fixation strength compared with a single LCP plate. This was confirmed by a recent study by Hollensteiner et al [ 35 ], who showed that for Levy Type III fractures, dual plating using two LCP plates in a orthogonal configuration is stronger than a single plate positioned caudally or posteriorly. When only one plate is used for fracture fixation, a LCP plate has shown to have superior fixation strength compared to a single reconstruction or lateral locking plate, for Levy Type III fractures [ 26 ].…”

“…Although we were unable to determine the fixation construct with the best clinical performance, our study of pooled results suggests that using a single locking plating for lateral acromion and acromial base fractures (Levy Type I and II), and a dual plating construct for more medial fractures (Levy Type II and III) delivers a high union rate and a reasonably low complication rate. Together with the current biomechanical knowledge about acromion and scapular spine fractures following RSA [ 5 ] and plating techniques [ 35 ], it seems that dual plating reveals a stronger fixation construct than single plating and may yield superior outcomes in more medial fractures, although the latter is yet to be proven.…”

“…Notwithstanding, there is an ongoing debate whether single or dual plating should be preferred [ 35 ]. Of the included studies, eight fractures were fixed with a dual plating construct [ 18 , 31 , 32 , 33 ] and in nine fractures a single plate was used [ 16 , 17 , 29 , 30 , 31 , 34 ] (the remaining patient had a tension band wire construct [ 31 ]).…”

“…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 ].…”

“…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 ].…”