Abstract
Introduction
One of the more common complaints from patients in their post-operative total knee arthroplasty (TKA) is the perceived feeling of the operative leg feeling longer than the non-operative leg. Studies have shown that the leg length discrepancies may occur in up to 80% of patients following unilateral TKA patients. The purpose of this study was to determine the incidence of leg length discrepancy (LLD) after primary TKA as well as determine the correlation between deformity and incidence of LLD.
Methods
We retrospectively reviewed 1108 patients who underwent a primary unilateral TKA at a single institution. 97 patients were excluded for lack of imaging, prior total hip replacement or body mass index greater than 40 kg/m2. Hip to ankle biplanar radiographs were obtained pre-operative and 6 weeks postoperatively for all patients. Two independent observers measures leg length, femur length, tibia length, overall alignment and deformity present for all radiographs.
Results
1,101 patients were included. Mean overall lengthening was 3.4 mm [Range −21 to 22.8mm; SD 7.4] with 81% of limbs lengthened. In our cohort, 9% of patients had LLD greater than 10 mm and 43% of patients had LLD of more than 5mm after TKA. Post-operative radiographic LLD was associated with increased pre-operative LLD (P<.001) and with female gender (p=0.03). Patients with pre-operative valgus deformity were more likely to have an increased lengthening of greater than 5mm compared to patients with varus deformity (OR:1.66).
Conclusion
43% of patients will have a LLD >5mm following correction of deformity and ligament balances in knee replacement surgery. Surgeons should be aware and this should be reviewed with patients as part of their expectations of surgery.
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