Influence of sagittal plane malpositioning of the patella on anterior knee pain after tibia intramedullary nailing
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Purpose: Anterior knee pain (AKP) is one of the most common complications after tibia intramedullary surgery. We evaluated changes in patellar tendon length after tibia intramedullary nailing surgery using a transtendinous approach and assessed the importance of nail position in relation to the anterior tibial cortex and joint line. Methods: Two surgeons blinded to patients’ pain status measured both the knee Insall–Salvati and Caton–Deschamps indexes on 30° flexion lateral knee X-rays of 33 patients. Superior nail prominence (the distance from the proximal tip of the nail to the tibial plateau) and anterior nail prominence (the distance from the anterior tip of the nail to the anterior tibial cortex) were measured on the CT. Results: Clinical assessment showed that 10 patients (30 %) had AKP at the last follow-up. HSS and Lysholm scores and the incidence of AKP were similar between patients whose IM nails were removed and those who still had them. HSS score, Insall–Salvati, and Caton–Deschamps indexes were significantly lower in the operated extremity than in the healthy limb at last follow-up. No association was demonstrated between AKP and nail position in relation to the anterior tibial cortex or tibial plateau. Conclusions: According to our study, although the patellar tendon shortened significantly on the affected side compared with the contralateral side, these measurements did not correlate with the presence or absence of pain. AKP and functional knee scores after tibia IM nailing using a transtendinous approach were not associated with nail position in relation to the anterior tibial cortex or tibial plateau. Level of evidence: Level 3 (Case control study).