Preoperative nasal All primary total hip arthroplasties (THA) and total knee arthroplasties (TKA) performed from January 2006 to April 2018 were retrospectively reviewed for the incidence of early PJI. Demographic parameters, risk factors for PJI (American Society of Anaesthesiologists classification, body mass index, smoking status, and diabetes mellitus) and implant types were collected. A preoperative screening and eradication protocol for nasal colonization of Aims
Methods
Patients from a randomised trial on resurfacing
hip arthroplasty (RHA) (n = 36, 19 males; median age 57 years, 24
to 65) comparing a conventional 28 mm metal-on-metal total hip arthroplasty
(MoM THA) (n = 28, 17 males; median age 59 years, 37 to 65) and
a matched control group of asymptomatic patients with a 32 mm ceramic-on-polyethylene
(CoP) THA (n = 33, 18 males; median age 63 years, 38 to 71) were
cross-sectionally screened with metal artefact reducing sequence-MRI
(MARS-MRI) for pseudotumour formation at a median of 55 months (23
to 72) post-operatively. MRIs were scored by consensus according
to three different classification systems for pseudotumour formation. Clinical scores were available for all patients and metal ion
levels for MoM bearing patients. Periprosthetic lesions with a median volume of 16 mL (1.5 to
35.9) were diagnosed in six patients in the RHA group (17%), one
in the MoM THA group (4%) and six in the CoP group (18%). The classification
systems revealed no clear differences between the groups. Solid
lesions (n = 3) were exclusively encountered in the RHA group. Two patients
in the RHA group and one in the MoM THA group underwent a revision
for pseudotumour formation. There was no statistically significant
relationship between clinical scoring, metal ion levels and periprosthetic
lesions in any of the groups. Periprosthetic fluid collections are seen on MARS-MRI after conventional
CoP THA and RHA and may reflect a soft-tissue collection or effusion. Currently available MRI classification systems seem to score
these collections as pseudotumours, causing an-overestimatation
of the incidence of pseudotumours. Cite this article:
The purpose of this study was to evaluate whether concerns about the release of metal ions in metal-on-metal total hip replacements (THR) should be extended to patients with metal-bearing total disc replacements (TDR). Cobalt and chromium levels in whole blood and serum were measured in ten patients with a single-level TDR after a mean follow-up of 34.5 months (13 to 61) using inductively-coupled plasma mass spectrometry. These metal ion levels were compared with pre-operative control levels in 81 patients and with metal ion levels 12 months after metal-on-metal THR (n = 21) and resurfacing hip replacement (n = 36). Flexion-extension radiographs were used to verify movement of the TDR. Cobalt levels in whole blood and serum were significantly lower in the TDR group than in either the THR (p = 0.007) or the resurfacing group (p <
0.001). Both chromium levels were also significantly lower after TDR These results suggest that there is minimal cause for concern about high metal ion concentrations after TDR, as the levels appear to be only moderately elevated. However, spinal surgeons using a metal-on-metal TDR should still be aware of concerns expressed in the hip replacement literature about toxicity from elevated metal ion levels, and inform their patients appropriately.
We undertook a randomised prospective follow-up study of changes in peri-prosthetic bone mineral density (BMD) after hip resurfacing and compared them with the results after total hip replacement. A total of 59 patients were allocated to receive a hip resurfacing (n = 29) or an uncemented distally fixed total hip replacement (n = 30). The BMD was prospectively determined in four separate regions of interest of the femoral neck and in the calcar region corresponding to Gruen zone 7 for the hip resurfacing group and compared only to the calcar region in the total hip replacement group. Standardised measurements were performed pre-operatively and after three, six and 12 months. The groups were well matched in terms of gender distribution and mean age. The mean BMD in the calcar region increased after one year to 105.2% of baseline levels in the resurfaced group compared with a significant decrease to 82.1% in the total hip replacement group (p <
0.001) by 12 months. For the resurfaced group, there was a decrease in bone density in all four regions of the femoral neck at three months which did not reach statistical significance and was followed by recovery to baseline levels after 12 months. Hip resurfacing did indeed preserve BMD in the inferior femoral neck. In contrast, a decrease in the mean BMD in Gruen zone 7 followed uncemented distally fixed total hip replacement. Long term follow-up studies are necessary to see whether this benefit in preservation of BMD will be clinically relevant at future revision surgery.
