Leg Length discrepancy (LLD) is a well known complication following hip arthroplasty. There are many papers looking at LLD after total hip replacement however there are none looking at LLD after hip hemiarthroplasty for fracture neck of femur. Our aim was to accurately assess leg length discrepancy following cemented hip hemiarthroplasty.
Sixty consecutive patients who underwent cemented hip hemiarthroplasty for fracture neck of femur between 2008 and 2009 were selected for the study. Patient details including implant sizes, were collected from theatre records.
We used the trauma cad software to accurately calculate LLD after appropriate calibration. We measured pre & post-operative femoral position to calculate the degree of LLD. The LLD’s were calculated by two observers to look for any inter-observer differences.
We excluded cases where the xray was too externally rotated, missed out the greater trochanter or no post-op xrays were available.
ixteen cases were excluded for not meeting the inclusion criteria. In the remaining forty four patients, the mean leg length discrepancy was a 5.6 mm increase in length with a range of 5.3 mm shortening to 20.7 mm lengthening. The 95% confidence intervals was 1.8 mm above and below the mean.
Pearson’s correlation coefficient between pre and post operative leg length showed no significant length discrepancy with a coefficient of 0.42.
There was no significant inter – observer error.
Many studies looking at LLD after total hip arthroplasty had a mean lengthening of 9mm. Our study has shown that hip hemiarthroplasties have marginally better results.
However some LLD still exists and we feel that this could have been due to the absence of pre-op templating, inaccurate femoral cut and the inability of the implant to accommodate variations in patient femoral neck angle.
We believe that correcting these issues could reduce LLD, accurately restore normal anatomy and reduce the potential complications of low back pain, nerve palsy and abnormal gait associated with LLD.
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