The role of inter-prosthetic distance, cortical thickness and bone mineral density in the development of inter-prosthetic fractures of the femur: a biomechanical cadaver study

TY - JOUR

T1 - The role of inter-prosthetic distance, cortical thickness and bone mineral density in the development of inter-prosthetic fractures of the femur: a biomechanical cadaver study

AU - Weiser, L

AU - Korecki, M A

AU - Sellenschloh, Kay

AU - Fensky, F

AU - Püschel, K

AU - Morlock, M M

AU - Rueger, J M

AU - Lehmann, W

N1 - ©2014 The British Editorial Society of Bone & Joint Surgery.

PY - 2014/10/1

Y1 - 2014/10/1

N2 - It is becoming increasingly common for a patient to have ipsilateral hip and knee replacements. The inter-prosthetic (IP) distance, the distance between the tips of hip and knee prostheses, has been thought to be associated with an increased risk of IP fracture. Small gap distances are generally assumed to act as stress risers, although there is no real biomechanical evidence to support this. The purpose of this study was to evaluate the influence of IP distance, cortical thickness and bone mineral density on the likelihood of an IP femoral fracture. A total of 18 human femur specimens were randomised into three groups by bone density and cortical thickness. For each group, a defined IP distance of 35 mm, 80 mm or 160 mm was created by choosing the appropriate lengths of component. The maximum fracture strength was determined using a four-point bending test. The fracture force of all three groups was similar (p = 0.498). There was a highly significant correlation between the cortical area and the fracture strength (r = 0.804, p < 0.001), whereas bone density showed no influence. This study suggests that the IP distance has little influence on fracture strength in IP femoral fractures: the thickness of the cortex seems to be the decisive factor.

AB - It is becoming increasingly common for a patient to have ipsilateral hip and knee replacements. The inter-prosthetic (IP) distance, the distance between the tips of hip and knee prostheses, has been thought to be associated with an increased risk of IP fracture. Small gap distances are generally assumed to act as stress risers, although there is no real biomechanical evidence to support this. The purpose of this study was to evaluate the influence of IP distance, cortical thickness and bone mineral density on the likelihood of an IP femoral fracture. A total of 18 human femur specimens were randomised into three groups by bone density and cortical thickness. For each group, a defined IP distance of 35 mm, 80 mm or 160 mm was created by choosing the appropriate lengths of component. The maximum fracture strength was determined using a four-point bending test. The fracture force of all three groups was similar (p = 0.498). There was a highly significant correlation between the cortical area and the fracture strength (r = 0.804, p < 0.001), whereas bone density showed no influence. This study suggests that the IP distance has little influence on fracture strength in IP femoral fractures: the thickness of the cortex seems to be the decisive factor.

KW - Aged

KW - Arthroplasty, Replacement, Hip

KW - Arthroplasty, Replacement, Knee

KW - Biomechanical Phenomena

KW - Bone Density

KW - Cadaver

KW - Female

KW - Femoral Fractures

KW - Femur

KW - Hip Prosthesis

KW - Humans

KW - Knee Prosthesis

KW - Male

KW - Middle Aged

KW - Models, Biological

KW - Osteoporotic Fractures

KW - Prosthesis Failure

KW - Stress, Mechanical

KW - Tomography, X-Ray Computed

U2 - 10.1302/0301-620X.96B10.33461

DO - 10.1302/0301-620X.96B10.33461

M3 - SCORING: Journal article

C2 - 25274925

VL - 96-B

SP - 1378

EP - 1384

JO - BONE JOINT J

JF - BONE JOINT J

SN - 2049-4394

IS - 10

ER -