Association between bone trace metal accumulation and idiopathic aseptic osteonecrosis of the femoral head in a mining region of Katanga (DR Congo).

BACKGROUND

Aseptic osteonecrosis of the femoral head (ONFH) is a debilitating orthopedic disorder that predominantly affects young adults and has a multifactorial etiology. In mining-intensive regions such as Katanga (Democratic Republic of the Congo), chronic exposure to trace metal elements (TMEs) has raised concerns about potential environmental contributors to bone disease. This study aimed to investigate the association between bone TME accumulation and the occurrence of idiopathic ONFH in an environmentally exposed population.

METHODS

A case-control study was conducted between 2017 and 2025 at Medpark Clinic, Lubumbashi. Femoral head specimens were collected from 56 patients undergoing total hip arthroplasty, including 36 cases of idiopathic ONFH and 20 controls with primary osteoarthritis. Bone concentrations of eleven TMEs (Pb, Co, Cd, Cr, Zn, Cu, As, Mn, Mg, Ni, Al) were quantified using inductively coupled plasma-optical emission spectrometry (ICP-OES). Exposure was defined as a Z-score > 2 compared with a local reference population. Bivariate and multivariate logistic regression analyses were performed to assess associations.

RESULTS

Patients with ONFH were significantly younger than controls (mean age: 49.5 vs. 62.9 years; p = 0.004). Bone concentrations of lead and cobalt were markedly higher in ONFH cases. In multivariate analysis, elevated bone lead levels (adjusted OR = 23.75; 95% CI: 2.30-181.57) and age ≤ 50 years were independently associated with ONFH. No significant associations were found for other TMEs.

CONCLUSION

This study provides the first direct evidence that chronic bone accumulation of lead and cobalt is strongly associated with idiopathic ONFH in a mining-exposed African population. These findings highlight the urgent need for environmental monitoring, targeted public health interventions, and early clinical surveillance in high-risk regions.