Locking Plate Fixation with and without Inferomedial Screws for Proximal Humeral Fractures: A Biomechanical Study

Abstract

Purpose.

To compare the efficacy of locking plate fixation with and without inferomedial screws in maintaining the reduction of a proximal humeral fracture.

Methods.

22 synthetic humerus models were used. A standardised 3-part proximal humeral fracture with a 4-mm wedge segment was created and fixed with a locking plate and screws with (n=11) and without (n=11) inferomedial screws. The intrafragmentary motion of the construct at 250, 500, 750, and 1000 cycles of 532 N loading, and the load to failure of the 2 groups were compared.

Results.

Locking plate fixation with inferomedial screws reduced the mean intrafragmentary motion in all cycles (p±0.01) and increased the load to failure (1452 N vs. 1159 N, p±0.001), compared to fixation without inferomedial screws.

Conclusion.

Additional inferomedial screws provide medial column support for fracture healing. This may reduce intrafragmentary motion and thus implant complications resulting from varus malalignment such as screw perforation or loss of reduction.

Keywords

bone plates bone screws shoulder fracture

References

Neer

2nd . Displaced proximal humeral fractures. I. Classification and evaluation. J Bone Joint Surg Am 1970;52:1077–89.

Liew

Johnson

Patterson

King

Chess

. Effect of screw placement on fixation in the humeral head. J Shoulder Elbow Surg 2000;9:423–6.

Lever

Aksenov

Zdero

Ahn

McKee

Schemitsch

. Biomechanical analysis of plate osteosynthesis systems for proximal humerus fractures. J Orthop Trauma 2008;22:23–9.

Brunner

Sommer

Bahrs

Heuwinkel

Hafner

Rillmann

. Open reduction and internal fixation of proximal humerus fractures using a proximal humeral locked plate: A prospective multicenter analysis. J Orthop Trauma 2009;23:163–72.

Bjorkenheim

Pajarinen

Savolainen

. Internal fixation of proximal humeral fractures with a locking compression plate: A retrospective evaluation of 72 patients followed for a minimum of 1 year. Acta Orthop Scand 2004;75:741–5.

Kettler

Biberthaler

Braunstein

Zeiler

Kroetz

Mutschler

. Treatment of proximal humeral fractures with the PHILOS angular stable plate. Presentation of 225 cases of dislocated fractures [in German]. Unfallchirurg 2006;109:1032–40.

Thanasas

Kontakis

Angoules

Limb

Giannoudis

. Treatment of proximal humerus fractures with locking plates: A systematic review. J Shoulder Elbow Surg 2009;18:837–44.

Moonot

Ashwood

Hamlet

. Early results for treatment of three- and four-part fractures of the proximal humerus using the PHILOS plate system. J Bone Joint Surg Br 2007;89:1206–9.

Gardner

Weil

Barker

Kelly

Helfet

Lorich

. The importance of medial support in locked plating of proximal humerus fractures. J Orthop Trauma 2007;21:185–91.

10.

Gerber

Werner

Vienne

. Internal fixation of complex fractures of the proximal humerus. J Bone Joint Surg Br 2004;86:848–55.

11.

Kennedy

. Biomechanical and computational analysis of the use of void filling synthetic bone graft substitute in complex proximal humerus fractures. Dublin: Royal College of Surgeons in Ireland; 2009.

12.

Poppen

Walker

. Forces at the glenohumeral joint in abduction. Clin Orthop Relat Res 1978;135:165–70.

13.

Mandalidis

McGlone

Quigley

McInerney

O'Brien

. Digital fluoroscopic assessment of the scapulohumeral rhythm. Surg Radiol Anat 1999;21:241–6.

14.

Wheeler

Colville

. Biomechanical comparison of intramedullary and percutaneous pin fixation for proximal humeral fracture fixation. J Orthop Trauma 1997;11:363–7.

15.

Konrad

Bayer

Hepp

Voigt

Oestern

Kaab

. Open reduction and internal fixation of proximal humeral fractures with use of the locking proximal humerus plate. Surgical technique. J Bone Joint Surg Am 2010;92(Suppl 1):85–95.

16.

Micic

Kim

Shin

Kim

Park

. Analysis of early failure of the locking compression plate in osteoporotic proximal humerus fractures. J Orthop Sci 2009;14:596–601.

17.

Hepp

Lill

Bail

Korner

Niederhagen

Haas

. Where should implants be anchored in the humeral head? Clin Orthop Relat Res 2003;415:139–47.

18.

Koukakis

Apostolou

Taneja

Korres

Amini

. Fixation of proximal humerus fractures using the PHILOS plate: Early experience. Clin Orthop Relat Res 2006;442:115–20.

19.

Voigt

Woltmann

Partenheimer

Lill

. Management of complications after angularly stable locking proximal humerus plate fixation [in German]. Chirurg 2007;78:40–6.

20.

Kwon

Goertzen

O'Brien

Broekhuyse

Oxland

. Biomechanical evaluation of proximal humeral fracture fixation supplemented with calcium phosphate cement. J Bone Joint Surg Am 2002;84:951–61.

21.

Maldonado

Seebeck

Heller

Brandt

Hepp

Lill

. Straining of the intact and fractured proximal humerus under physiological-like loading. J Biomech 2003;36:1865–73.

22.

Gardner

Boraiah

Helfet

Lorich

. Indirect medial reduction and strut support of proximal humerus fractures using an endosteal implant. J Orthop Trauma 2008;22:195–200.

23.

Osterhoff

Baumgartner

Favre

Wanner

Gerber

Simmen

. Medial support by fibula bone graft in angular stable plate fixation of proximal humeral fractures: An in vitro study with synthetic bone. J Shoulder Elbow Surg 2011;20:740–6.

24.

Dunlap

Chong

Lucas

Cooke

. Structural properties of a novel design of composite analogue humeri models. Ann Biomed Eng 2008;36:1922–6.