Radiographic Risk Factors for Interprosthetic Femur Fractures

Transcription

1 Radiographic Risk Factors for Interprosthetic Femur Fractures Jason S Lipof, MD Ari D Amitai, MD John P Ketz, MD Kyle T Judd, MD Gillian L Soles, MD Catherine A Humphrey, MD John T Gorczyca, MD

2 The authors of this presentation have no financial conflicts or disclosures

3 Introduction Total Hip Arthroplasty (THA) and Total Knee Arthroplasty (TKA) are common ~ 2.5 million Americans with THA 1 ~ 4.7 million Americans with TKA 1 ~ 1 million new THA and TKA yearly 2 Over 300,000 people >65 years old hospitalized for hip fractures yearly in US 3 Increased incidence of arthroplasty Increased incidence of ipsilateral TKA and THA Greater Survivorship and activity Increased risk of falls and fracture Incidence of Interprosthetic Fractures (IP) likely to increase over time 3

4 Incidence of Periprosthetic Fractures 6,7,8 THA 0.1%-6% IP Femur Fx? TKA 0.3%-5.5% 4

5 Introduction Limited clinical data evaluating potential risks for fracture Interprosthetic distance, Cortical Width, Medullary Diameter Bone strength and cortical width may be more predictive than interprosthetic distance 4,5 5

6 Hypothesis A difference in cortical width and medullary diameter will exist between two groups of patients; those sustaining interprosthetic femur fractures, and those with ipsilateral implants and intact femurs. 6

7 Materials and Methods CPT codes to identify patients undergoing treatment of periprosthetic femur fx CPT codes used to find cohort having undergone ipsilateral THA/TKA Chart review for age, sex, diagnosis of osteoporosis Intact femoral isthmus identified Medullary Diameter (MD) & Cortical Width (CW) measured using PACS Independent Sample T-test performed Mean MD, CW, and ratio of MD/CW P<0.05 7

8 Materials and Methods Cortical width measured at isthmus by summing the thickness of medial and lateral cortices. 8

9 Materials and Methods Medullary diameter also measured at isthmus 9

10 Results Interprosthetic Fractures (n=23) Intact Cohort (n=25) Age Sex Female 18 Male 5 Female 17 Male 8 Cemented Implant 6 (26%) 1 (4%) Dx of Osteoporosis 7 (30%) 6 (24%) 10

11 Results Interprosthetic Fractures (n=23) Intact Cohort (n=25) Cortical Width (mm) Medullary Diameter (mm) MD:CW Mean SD Mean SD P-value < < < % of difference (-6.42, -2.55) (4.34, 8.62) (0.55, 1.25) 11

12 Results Intraclass Correlation Coefficient CW MD 95% Confidence Interval 95% Confidence Interval Intraclass Intraclass Correlation b Lower Bound Upper Bound Correlation Lower Bound Upper Bound Single Measures Average Measures

13 Conclusion Cortical Width and Medullary Diameter may be predictive of increased risk for interprosthetic fractures of the femur Radiographic measures may help identify at risk patients for inclusion in fracture prevention programs and treatment of osteoporosis Age-dependent risk increased survivorship, aging population Few patients in either group had been given a formal diagnosis of osteoporosis May indicate need for increased surveillance 13

14 Limitations Radiographs not calibrated Unable to measure interprosthetic distance Retrospective review 14

15 References 1 Steiner C, Andrews R, Barrett M, Weiss A. HCUP ProjectionsMobility/Orthopedic Procedures 2003 to HCUP Projections Report # Sep 20. U.S. Agency for Healthcare Research and Quali: ty. 2 Prevalence of Total Hip and Knee Replacement in the United States Hilal Maradit Kremers, Dirk R. Larson, Cynthia S. Crowson, Walter K. Kremers, Raynard E. Washington, Claudia A. Steiner, William A. Jiranek, Daniel J. Berry J Bone Joint Surg Am Sep 2015, 97 (17) HCUPnet. Healthcare Cost and Utilization Project (HCUP) Agency for Healthcare Research and Quality, Rockville, MD. Accessed 5 August Lehmann, Wolfgang, et al. "Biomechanical evaluation of peri-and interprosthetic fractures of the femur." Journal of Trauma and Acute Care Surgery 68.6 (2010): Iesaka, Kummer, et al. Stress risers between two ipsilateral intramedullary stems: a finite element and biomechanical analysis. Journal of Arthroplasty. 2005; 20(3): Berry DJ. Epidemiology of periprosthetic fractures after major joint replacement: hip and knee. Orthop Clin North Am. 1999;30: Rorabeck CH, Taylor JW. Periprosthetic fractures of the knee complicating total knee arthroplasty. Orthop Clin North Am. 1999;30: Kenny P, Rice J, Quinlan W. Interprosthetic fracture of the femoral shaft. J Arthroplasty. 1998;13:

16 Thank You 16

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