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Blaty T, Krueger D, Illgen R, Squire M, Heiderscheit B, Binkley N, Anderson P. DXA evaluation of femoral bone mineral density and cortical width in patients with prior total knee arthroplasty. Osteoporos Int 2019; 30:383-390. [PMID: 30171301 DOI: 10.1007/s00198-018-4682-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Accepted: 08/19/2018] [Indexed: 01/07/2023]
Abstract
UNLABELLED Periprosthetic fractures after total knee arthroplasty (TKA) have devastating consequences. Osteoporosis increases periprosthetic fracture risk, but distal femur bone mineral density (BMD) is not measured post-TKA. This study measured distal femur BMD and cortical width; both were lower in the TKA compared to the non-operated leg. BMD measurement reproducibility was good. Standardized DXA regions of interest are proposed. INTRODUCTION Periprosthetic fractures following total knee arthroplasty (TKA) are not rare. We hypothesized that TKA is associated with low BMD, potentially increasing periprosthetic fracture risk. However, distal femur dual energy x-ray (DXA) measurement is virtually never performed after TKA due to lack of standardized approaches. Thus, this study's aims were to develop standard DXA femur regions of interest (ROIs), assess cortical width, and determine measurement reproducibility in TKA patients. METHODS Thirty adults (15 M/15 F) age 59-80 years with unilateral, primary TKA within 2-5 years had femoral DXA scans performed in duplicate using a Lunar iDXA densitometer. In prior work, we established that femur BMD was lowest in the distal metaphysis and highest in mid-shaft. Thus, BMD and cortical width were measured at 15%, 25%, and 60% of the femur length measured from the distal notch. Femur BMD and cortical width were compared between limbs (TKA vs. non-operated side) by paired t test. RESULTS BMD was 3.2-9.9% lower (p < 0.001) in the operated femur at all custom ROIs; substantial between individual differences existed with some up to 30% lower. Cortical width was lower (p < 0.05) at the 25% ROI on the TKA side. BMD reproducibility was excellent; CV 0.85-1.33%. CONCLUSIONS Distal femur BMD can be reproducibly measured using DXA and is ~ 10% lower on the TKA leg. Similarly, medial and lateral cortices are thinner at the 25% ROI. These bone changes likely increase periprosthetic fracture risk. Further work to define and mitigate periprosthetic fracture risk after TKA is needed.
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Affiliation(s)
- T Blaty
- Osteoporosis Clinical Research Program, University of Wisconsin School of Medicine and Public Health, 2870 University Ave. Ste. 100, Madison, WI, 53705, USA
| | - D Krueger
- Osteoporosis Clinical Research Program, University of Wisconsin School of Medicine and Public Health, 2870 University Ave. Ste. 100, Madison, WI, 53705, USA
| | - R Illgen
- Department of Orthopedics and Rehabilitation, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - M Squire
- Department of Orthopedics and Rehabilitation, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - B Heiderscheit
- Department of Orthopedics and Rehabilitation, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - N Binkley
- Osteoporosis Clinical Research Program, University of Wisconsin School of Medicine and Public Health, 2870 University Ave. Ste. 100, Madison, WI, 53705, USA.
| | - P Anderson
- Department of Orthopedics and Rehabilitation, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
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Binkley N, Coursin D, Krueger D, Iglar P, Heiner J, Illgen R, Squire M, Lappe J, Watson P, Hogan K. Surgery alters parameters of vitamin D status and other laboratory results. Osteoporos Int 2017; 28:1013-1020. [PMID: 27826645 DOI: 10.1007/s00198-016-3819-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 10/24/2016] [Indexed: 12/12/2022]
Abstract
UNLABELLED Fracture liaison services often perform laboratory testing, but these results may be altered by surgery. In 40 hip arthroplasty patients, many laboratory parameters of bone health relevance were reduced by 8-22% on the first post-operative day. Laboratory results obtained in the immediate post-surgery interval do not reliably ascertain baseline status. INTRODUCTION As secondary causes of osteoporosis are common, fracture liaison services often perform laboratory testing in the immediate post-fracture interval. We hypothesized that laboratory results obtained shortly after surgery may not accurately ascertain baseline status. If true, such alterations might confound subsequent fracture prevention efforts. METHODS Patients undergoing elective total hip arthroplasty were studied as a surrogate for hip fracture patients. Blood and urine were obtained 2 weeks before surgery, before anesthetic induction, on post-operative day one, and 6 weeks after surgery. Serum total and free 25-hydroxyvitamin D (25(OH)D), vitamin D-binding protein (DBP), calcium, creatinine, albumin (Alb), alkaline phosphatase (ALP), plasma hemoglobin (Hgb) and urinary DBP/creatinine ratio (UDBP/Cr) were measured. RESULTS Forty volunteers (28 women; 12 men) with mean age of 65.7 [8.7] years were studied. Laboratory results were stable from 2 weeks before to the day of surgery. On the first day after surgery, total 25(OH)D, DBP, calcium, creatinine, ALP, and Alb declined 8-22% (p < 0.0001); free 25(OH)D and Hgb declined by 8 and 15% (p < 0.01), respectively; and UDBP/Cr increased 32% (p < 0.01). Using a 25(OH)D <30 ng/mL threshold, vitamin D inadequacy prevalence increased from 38% before surgery to 68% the day after (p < 0.001). All laboratory values returned to baseline at 6 weeks after surgery. CONCLUSIONS Laboratory values are reduced immediately following elective total hip arthroplasty. Testing at that time does not accurately ascertain baseline status and may lead to elevated estimates of vitamin D inadequacy, incorrect interventions, and misallocation of healthcare resources.
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Affiliation(s)
- N Binkley
- University of Wisconsin Osteoporosis Clinical Research Program, 2870 University Ave, Madison, WI, 53705, USA.
- Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA.
| | - D Coursin
- Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
- Department of Anesthesiology, University of Wisconsin School of Medicine and Public Health, 600 Highland Avenue, B6/319 CSC, Madison, WI, 53792-3272, USA
| | - D Krueger
- University of Wisconsin Osteoporosis Clinical Research Program, 2870 University Ave, Madison, WI, 53705, USA
| | - P Iglar
- Department of Population Health Sciences, University of Wisconsin School of Medicine and Public Health, 707 WARF Building, 610 North Walnut Street, Madison, WI, 53726, USA
| | - J Heiner
- Department of Orthopedics and Rehabilitation, University of Wisconsin School of Medicine and Public Health, 1685 Highland Avenue, Madison, WI, 53705-2281, USA
| | - R Illgen
- Department of Orthopedics and Rehabilitation, University of Wisconsin School of Medicine and Public Health, 1685 Highland Avenue, Madison, WI, 53705-2281, USA
| | - M Squire
- Department of Orthopedics and Rehabilitation, University of Wisconsin School of Medicine and Public Health, 1685 Highland Avenue, Madison, WI, 53705-2281, USA
| | - J Lappe
- Creighton University Osteoporosis Research Center, 601 N. 30th Street, Suite 4820, Omaha, NE, 68131, USA
| | - P Watson
- Creighton University Osteoporosis Research Center, 601 N. 30th Street, Suite 4820, Omaha, NE, 68131, USA
| | - K Hogan
- Department of Anesthesiology, University of Wisconsin School of Medicine and Public Health, 600 Highland Avenue, B6/319 CSC, Madison, WI, 53792-3272, USA
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