ABSTRACT
PURPOSE: To describe and quantify a radiological phenomenon where the distal tibial plafond appears in valgus malalignment in intra-operative fluoroscopy owing to 15 degrees craniocaudal angulation of the X-ray beam. METHODS: The lateral distal tibial angle (LDTA) of 14 male and 9 female skeletally mature patients was measured by a single reviewer using 2 types of anteroposterior radiographs, in which the X-ray beam was projected at 0 (orthogonal to the ankle) and then at 15 (in a craniocaudal direction) degrees. The LDTA was the angle between the long axis of the tibia and a line drawn across the most radiodense part of the tibial plafond. The paired t-test was used to compare the LDTA of the 2 measurements. RESULTS: The mean LDTA on the 0-degree orthogonal radiographs was 89 (range, 87-92) degrees, whereas the mean LDTA on the 15-degree craniocaudal radiographs was 79 (range, 77-81) degrees. The mean difference was 10 degrees (range, 9-12; p<0.0001). In the 15-degree craniocaudal radiographs, the ankle joint appeared to have valgus malalignment. CONCLUSION: During intramedullary nailing of the tibia, the knee is usually flexed and the image intensifier may not swing over far enough. This can result in well-aligned reduction being incorrectly viewed as having valgus malalignment or a varus-malaligned fracture being incorrectly viewed as reduced.
Subject(s)
Coxa Valga/diagnostic imaging , Fracture Fixation, Intramedullary/methods , Tibia/diagnostic imaging , Tibial Fractures/diagnostic imaging , Adult , Coxa Valga/etiology , Coxa Valga/surgery , Female , Follow-Up Studies , Fracture Healing , Humans , Male , Radiography , Tibia/surgery , Tibial Fractures/complications , Tibial Fractures/surgery , Young AdultABSTRACT
The aim of this study was to quantify the incidence and severity of tibial component overhang in total knee replacement and find any relationship between overhang and functional outcome. 532 anteroposterior radiographs of total knee replacements were reviewed retrospectively to identify medial or lateral overhang of the tibial component. Patients completed an Oxford knee score (OKS) questionnaire at mean follow-up of 36 months. Overhang of the tibial component was noted in 13.4% of patients with a mean OKS of 353. Severity of overhang did not correlate with OKS. Overhang of the tibial component is common. However, in this study it was not associated with a worse than expected outcome and increasing severity did not correlate with worse functional scores.
