Lower limb bone geometry in adult individuals with X-linked hypophosphatemia: an observational study

Abstract

Summary We assessed lower-limb geometry in adults with X-linked hypophosphatemia (XLH) and controls. We found large differences in multiple measures including femoral and tibial torsion, bowing and cross-sectional area and acetabular version and coverage which may contribute to clinical problems such as osteoarthritis, fractures and altered gait common in XLH. Purpose Individuals with X-linked hypophosphatemia (XLH) are at risk of lower-limb deformities and early onset of osteoarthritis. These two factors may be linked, as altered biomechanics is a risk factor for osteoarthritis. This exploratory evaluation aims at providing clues and concepts for this association to facilitate future larger-scale and longitudinal studies on that aspect. Methods For this observational study, 13 patients with XLH, aged 18–65 years (6 female), were compared with sex-, age- and weight-matched healthy individuals at a single German research centre. Femoral and hip joint geometry, including femoral and tibial torsion and femoral and tibial shaft bowing, bone cross-sectional area (CSA) and acetabular version and coverage were measured from magnetic resonance imaging (MRI) scans. Results Total femoral torsion was 29° lower in individuals with XLH than in controls ( p < 0.001), mainly resulting from lower intertrochanteric torsion (ITT) ( p < 0.001). Femoral lateral and frontal bowing, tibial frontal bowing, mechanical axis, femoral mechanical–anatomical angle, acetabular version and acetabular coverage were all greater and tibial torsion lower in individuals with XLH as compared to controls (all p < 0.05). Greater femoral total and marrow cavity CSA, greater tibial marrow cavity CSA and lower cortical CSA were observed in XLH (all p < 0.05). Discussion We observed large differences in clinically relevant measures of tibia and particularly femur bone geometry in individuals with XLH compared to controls. These differences may plausibly contribute to clinical manifestations of XLH such as early-onset osteoarthritis, pseudofractures and altered gait and therefore should be considered when planning corrective surgeries. Supplementary Information The online version contains supplementary material available at 10.1007/s00198-022-06385-z.

Associations between long-term exercise participation and lower limb joint and whole-bone geometry in young and older adults

“…MRI images were analysed using ImageJ (version 1.52 h) as in Scorcelletti et al ( Scorcelletti et al, 2022 ). All the following angles are measured in degrees.…”

Operative Korrektur der Beinachse bei X-chromosomaler Hypophosphatämie

“…Diese sagittalen Fehlstellungen treten jedoch nicht bei allen PatientInnen und in sehr unterschiedlichem Ausmaß auf. In transversaler Ebene ist nach rezenter Forschung einer verstärkten Außendrehung (Maltorsion) des Femurs [8,9] und verstärkte Innendrehung der Tibia [4,8,10] vorliegend (▶Abb. 1).…”

“…Auch das Acetabulum sowie das Becken zeigen bei PatientInnen Abweichungen von der Norm [8,10] -Veränderungen, die jedoch bislang in der XLH Betreuung nicht chirurgisch adressiert wurden.…”

“…Die rezente Forschung zeigt deutlich, dass Beindeformitäten in komplexerem Ausmaß vorliegen als bislang vermutet [3][4][5][8][9][10] (▶Abb. 1).…”

The contribution of a novel PHEX gene mutation to X-linked hypophosphatemic rickets: a case report and an analysis of the gene mutation dosage effect in a rat model

“…XLH patients commonly exhibit clinical manifestations such as progressive skeletal deformities, growth retardation, and dental hypoplasia. However, the severity of these manifestations varies greatly, particularly in terms of femoral morphology ( 2 ). Joint pain and osteoarthritis are frequent complications experienced by XLH patients due to skeletal deformities, fractures, enthesopathy, spinal stenosis, and hearing loss ( 3 ).…”