Metal-on-metal hip arthroplasty: physical activity monitoring, outcomes and systemic toxicity

Jetse Jelsma

Research output: ThesisDoctoral ThesisExternal prepared

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The relationship between objectively measured physical activity and blood metal concentrations in patients with MoM hip replacements was investigated in two different cohort studies. The average number of steps per day of the patients in these studies was comparable to healthy subjects of the same age. This indicates a normal activity level of the patient population in this study. There was a wide variation in the cobalt concentrations of the patients. A significant correlation was found between cobalt concentrations and various parameters of daily physical activity (number of sit-to-stand transfers and high-intensity peaks). No statistically significant relationships were found between cobalt concentrations and daily time spent walking, total number of steps and total percentage of time physically active. It seems that quantitative general daily activities, such as normal walking, do not influence cobalt concentrations, or do so only slightly. Especially qualitative aspects of the activities (high intensity, fast walking, many sit-to-stand transfers) seem to influence cobalt concentrations. It also compared the activity found in patients with MoM prostheses with patients with conventional prostheses. The groups were similar in terms of gender, age at surgery, follow-up since surgery and BMI. Contrary to expectations, patients with an HRA were not found to be more physically active. Patients show similar physical activities independent of the type of implant. These patients were also asked to complete questionnaires (PROMs), asking about their physical activity. It turned out that these questionnaires hardly correspond to the objectively measured physical activity.
Using the Dutch National Register of Orthopaedic Implants (LROI), there was an investigation as to whether the replacement (revision) of a MoM prosthesis was comparable to the revision of a non-MoM prosthesis in terms of outcomes. Revision surgery for failed MoM hip replacements has a high risk of revisions, but this is comparable to the outcome of revisions for non-MoM hip replacements. Partial revision of the stem and MoM arthrodesis after the first revision show poor results in the surgical treatment of a failed MoM hip prosthesis.
After the implantation of a MoM hip prosthesis, patients have seen an increase in metal concentrations in the blood. Cobalt intoxication is an increasingly described complication with potentially severe symptoms; this is called 'Prosthetic Hip-Associated Cobalt Toxicity (PHACT)'. A literature review was carried out on the subject. The origin of most symptoms was in the sensory system (senses), followed by the cardiovascular (heart-vessel) and neurological (brain/nerves) systems. The threshold value of cobalt, at which symptoms start to appear, could not be determined due to the wide distribution of the concentrations described. In addition to this literature review, we asked patients whether they experienced any complaints. The results showed that oculo-vestibular (eye, hearing, balance organ) symptoms were more frequent in the groups with high cobalt concentration and with increasing prevalence for higher thresholds. This is an indication of the correlation between cobalt concentration and symptom prevalence.
Original languageEnglish
Awarding Institution
  • Maastricht University
  • Heyligers, Ide, Supervisor
  • Grimm, B.P., Co-Supervisor, External person
  • Schotanus, Martijn, Co-Supervisor
Award date21 Jan 2022
Place of PublicationMaastricht
Print ISBNs9789083189390
Publication statusPublished - 2022


  • Metal-on-metal hip replacement
  • Cobalt concentrations
  • Physical activity

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