Biomechanical evaluation of 3 stabilization methods on acromioclavicular joint dislocations

TY - JOUR

T1 - Biomechanical evaluation of 3 stabilization methods on acromioclavicular joint dislocations

AU - Nüchtern, Jakob

AU - Sellenschloh, Kay

AU - Bishop, Nick

AU - Jauch, Sabrina

AU - Briem, Daniel

AU - Hoffmann, Michael

AU - Lehmann, Wolfgang

AU - Püschel, Klaus

AU - Morlock, Michael M

AU - Rueger, Johannes

AU - Großterlinden, Lars

PY - 2013/6/1

Y1 - 2013/6/1

N2 - BACKGROUND: Traumatic acromioclavicular (AC) joint dislocations can be addressed with several surgical stabilization techniques. The aim of this in vitro study was to evaluate biomechanical features of the native joint compared with 3 different stabilization methods: locking hook plate (HP), TightRope (TR), and bone anchor system (AS).HYPOTHESIS: The HP provides higher stiffness than the anatomic reconstruction techniques.STUDY DESIGN: Controlled laboratory study.METHODS: A new biomechanical in vitro model of the AC joint was used to analyze joint stability after surgical repair (HP, TR, and AS). Eighteen cadaveric specimens were randomized for bone density and diameter in the midclavicle section. Joint stiffness was measured by applying an axial load and a defined physiological range of motion for internal and external rotations and upward and downward rotations. Data were recorded at 3 stages: for the native joint after dissecting the AC ligaments, directly after repair, and after axial cyclic loading (1000 cycles with 20 and 70 N at 1 Hz). To evaluate which implant mimics physiological joint properties best, axial stiffness of vertical stability was assessed in combination with rotation. Finally, static loading in the superior direction was applied until failure of the joints occurred.RESULTS: Axial stiffness of the TR and AS groups was 2-fold higher than for the HP group and the native joint (67.1, 66.1, and 22.5 N/mm, respectively; P < .004). Decreased load-to-failure rates were recorded in the HP group compared with the TR and AS groups (248.9 ± 72.7, 832.0 ± 401.4, and 538.0 ± 166.1 N, respectively). The stiffness of the rotations was not significantly different between the treatment methods but was lower in horizontal and downward rotations compared with the native state. Thus, native AC ligaments contributed a significant share to joint stiffness.CONCLUSION: The TR and AS groups demonstrated higher vertical load capacity. Compared with the TR and AS, the HP demonstrated an axial stiffness closest to the native joint. For restoring physiological properties, reconstruction of the AC ligaments may be necessary.CLINICAL RELEVANCE: The results show different biomechanical properties of the HP and anatomic reconstructions.

AB - BACKGROUND: Traumatic acromioclavicular (AC) joint dislocations can be addressed with several surgical stabilization techniques. The aim of this in vitro study was to evaluate biomechanical features of the native joint compared with 3 different stabilization methods: locking hook plate (HP), TightRope (TR), and bone anchor system (AS).HYPOTHESIS: The HP provides higher stiffness than the anatomic reconstruction techniques.STUDY DESIGN: Controlled laboratory study.METHODS: A new biomechanical in vitro model of the AC joint was used to analyze joint stability after surgical repair (HP, TR, and AS). Eighteen cadaveric specimens were randomized for bone density and diameter in the midclavicle section. Joint stiffness was measured by applying an axial load and a defined physiological range of motion for internal and external rotations and upward and downward rotations. Data were recorded at 3 stages: for the native joint after dissecting the AC ligaments, directly after repair, and after axial cyclic loading (1000 cycles with 20 and 70 N at 1 Hz). To evaluate which implant mimics physiological joint properties best, axial stiffness of vertical stability was assessed in combination with rotation. Finally, static loading in the superior direction was applied until failure of the joints occurred.RESULTS: Axial stiffness of the TR and AS groups was 2-fold higher than for the HP group and the native joint (67.1, 66.1, and 22.5 N/mm, respectively; P < .004). Decreased load-to-failure rates were recorded in the HP group compared with the TR and AS groups (248.9 ± 72.7, 832.0 ± 401.4, and 538.0 ± 166.1 N, respectively). The stiffness of the rotations was not significantly different between the treatment methods but was lower in horizontal and downward rotations compared with the native state. Thus, native AC ligaments contributed a significant share to joint stiffness.CONCLUSION: The TR and AS groups demonstrated higher vertical load capacity. Compared with the TR and AS, the HP demonstrated an axial stiffness closest to the native joint. For restoring physiological properties, reconstruction of the AC ligaments may be necessary.CLINICAL RELEVANCE: The results show different biomechanical properties of the HP and anatomic reconstructions.

KW - Acromioclavicular Joint

KW - Analysis of Variance

KW - Biomechanical Phenomena

KW - Cadaver

KW - Humans

KW - Joint Instability

KW - Orthopedic Procedures

KW - Range of Motion, Articular

KW - Rotation

KW - Shoulder Dislocation

U2 - 10.1177/0363546513484892

DO - 10.1177/0363546513484892

M3 - SCORING: Journal article

C2 - 23618701

VL - 41

SP - 1387

EP - 1394

JO - AM J SPORT MED

JF - AM J SPORT MED

SN - 0363-5465

IS - 6

ER -