DOS 2017

124

· DOS Abstracts

Ultrasound sensitivity and specificity for adverse reac-

tion to metal debris in patients with total hip arthro-

plasty

Rasmus Mikkelsen, Marianne Fløjstrup, Thomas Skjødt, Per Kjærsgaard-Ander-

sen, Claus Varnum

Department of Orthopaedic Surgery, Vejle Hospital; Department of Radiology,

Vejle Hospital; Department of Radiology, Vejle Hospital; Department of Ortho-

paedic Surgery, Vejle Hospital; Department of Orthopaedic Surgery, Vejle Hos-

pital

Background:

MRI is the most used technique for detection of adverse reaction

to metal debris (ARMD), although it is costly and less available than ultrasonog-

raphy (US). Few studies have measured whether US can detect ARMD.

Purpose / Aim of Study:

We aimed to investigate the sensitivity and speci-

ficity of US for ARMD in patients with total hip arthroplasty (THA). We also

investigated the sensitivity and specificity of US for ARMD in patients with THA

with pain.

Materials and Methods:

74 patients with primary unilateral THA were in-

cluded in a prospective cohort: 37 with modular neck femoral stem, 37 with

nonmodular femoral stem. All patients had pain assessed and their operated hip

scanned with MRI and US to look for pseudotumour (PT) and trochanteric bur-

sitis. Results of the MRI scans were used as the gold standard when calculating

sensitivity, specificity, positive predictive value (PPV) and negative predictive

value (NPV) of US.

Findings / Results:

21 patients had pain, and 53 patients had no pain. Mean

age at surgery and a follow-up of 2.7 years were similar in the two groups.

There were 5 PTs in the group with pain and 23 PTs in the group without pain

(p=0.183). Prevalence of trochanteric bursitis was similar in the two groups

(p=0.07). The sensitivity and specificity of US to detect PTs were 0.67 and

0.91, respectively, with a PPV of 0.82 and a NPV of 0.83. In patients with pain,

US had a sensitivity and specificity to detect PTs of 0.60 and 0.88, respectively,

and had a PPV of 0.60 and a NPV of 0.88. The sensitivity and specificity of US

to detect trochanteric bursitis was 0.07 and 0.84, respectively, with a PPV of

0.09 and a NPV of 0.80.

Conclusions:

US cannot replace MRI, but US did find some ARMD not seen on

MRI, why it is a useful supplement to MRI for diagnosing ARMD in patients with

THA. US did not perform better when used for patients with pain.

No conflicts of interest reported

76.