Abstract
There is very little literature on whether a simple radiographic measurement of native
femoral head size correlates with implanted acetabular cup size. We hypothesized that
there would be a high correlation between the radiographically measured native femoral
head and implanted acetabular component size in primary total hip arthroplasty (THA).
We conducted a retrospective study of 277 consecutive patients who underwent primary
THA. Patients with prior contralateral THA or a history of congenital deformity were
excluded (n = 95). We used the postoperative anteroposterior (AP) pelvic view to calibrate the
image using known implanted femoral head component size. We then measured the diameter
of the contralateral native femoral head under the assumption that femoral heads are
generally symmetrical in patients. Two of the authors performed all measurements.
To determine if native femoral head size was correlated with acetabular component
size we used the Pearson correlation coefficient (r). There was a high correlation between contralateral native femoral head size and
acetabular component size (r = 0.86, 95% confidence interval [CI]: 0.82–0.89). The median difference in radiographically
measured native femoral head size and acetabular component size was 7 mm (interquartile
range [IQR] = 5–8). Our data showed a high correlation between acetabular component
size and radiographically measured contralateral native femoral head size, with the
difference being 7 mm. In addition to verifying the actual femoral head size with
calipers during surgery, this simple radiographic measurement, which could be done
on the affected or contralateral hip, may help surgeons to plan better and improve
preoperative templating in primary THA.
Keywords
primary total hip arthroplasty - preoperative planning and templating - acetabular
component size
