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The Bone & Joint Journal
Vol. 102-B, Issue 11 | Pages 1582 - 1586
1 Nov 2020
Håberg Ø Foss OA Lian ØB Holen KJ


To assess if congenital foot deformity is a risk factor for developmental dysplasia of the hip (DDH).


Between 1996 and 2012, 60,844 children were born in Sør-Trøndelag county in Norway. In this cohort study, children with risk factors for DDH were examined using ultrasound. The risk factors evaluated were clinical hip instability, breech delivery, a family history of DDH, a foot deformity, and some syndromes. As the aim of the study was to examine the risk for DDH and foot deformity in the general population, children with syndromes were excluded. The information has been prospectively registered and retrospectively analyzed.

Bone & Joint Research
Vol. 3, Issue 11 | Pages 317 - 320
1 Nov 2014
Basso T Klaksvik J Foss OA


In ex vivo hip fracture studies femoral pairs are split to create two comparable test groups. When more than two groups are required, or if paired femurs cannot be obtained, group allocation according to bone mineral density (BMD) is sometimes performed. In this statistical experiment we explore how this affects experimental results and sample size considerations.


In a hip fracture experiment, nine pairs of human cadaver femurs were tested in a paired study design. The femurs were then re-matched according to BMD, creating two new test groups. Intra-pair variance and paired correlations in fixation stability were calculated. A hypothetical power analysis was then performed to explore the required sample size for the two types of group allocation.