SIMULTANEOUS BILATERAL FRACTURE NECK OF FEMUR FRACTURES: ONE FROM EPILEPSY, ANOTHER FROM ELECTRICITY

Presenting Author - VISHESH KHANNA
Post-traumatic tibial post fracture with base plate loosening in a posterior stabilised total knee arthroplasty. Presenting Author - VISHESH KHANNA Introduction: Posterior stabilised (PS) knees rely on a cam-post mechanism to replicate native femoral rollback and limit posterior displacement in total knee replacement (TKR). Predisposed to damage and eventual breakage, severe polyethylene wear can occur in 30–40% cases. Notwithstanding this, tibial post fractures have been sparsely and variably reported (0.5-12%). Even rarer is a tibial tray loosening with the post fracture. Varying post location, geometry, mechanics and implantation errors can prove influential. From our centre, performing well over 2,500 knees a year, we report a case of polyethylene post fracture in a patient following a recent fall 3 years post-TKR. Methods: A 61-year-old lady, operated for bilateral TKR 3 years back with Stryker hi-flex design, had uneventful intraoperative and postoperative courses. With a 00-1350 range-of-motion (ROM), she was comfortably performing all her daily tasks. She presented to us 2 years postoperatively with sudden onset of progressive pain and instability of her right knee accompanied by a clicking sound. She had sustained a domestic fall 45 days ago. Initially ambulatory, gradual worsening of symptoms had now led to difficulty in walking and frequent falls. Examination findings included mild effusion, restricted ROM (50-900), varus/valgus/mid-flexion instability. Patellar clunk signs were present and the tibia was seen subluxating over the femur in terminal extension. Lachman and posterior drawer tests were positive. Knee radiographs were consistent with instability, tibial base plate loosening and malalignment. We made the diagnosis of an insert fracture after corroborating the clunk, positive posterior drawer test and radiographs. After discussing with the patient, a poly exchange and tibial revision were planned. Results: Through the previous approach, the right knee was exposed. The broken tibial post was found embedded in the intercondylar notch with well-formed fibrous tissue all around. The stump of the post was flattened. Although the poly appeared intact without signs of wear (except posteromedially) we did notice tibial base plate loosening which was extracted, confirmed for intactness and reimplanted. We decided to replace the original 10mm hi-flex poly with a 15mm standard PS poly. Stability was confirmed in flexion, extension, mid-flexion and mediolateral planes. Patellar mal-tracking and clunk were relegated and closure was done. Early physiotherapy was started and 11-month follow-up revealed ROM of 00-1350 without any instability. Conclusions: Polyethylene breakage post-TKR is a rare, troublesome complication following trauma and should be treated with polyethylene exchange lest it may cause eventual tibial base plate loosening and implant failure.