A Journey to Remember: Unexpected Peg Fractures 10 Years After Total Knee Replacement in Technically Successful Uncomplicated Arthroplasties

Purpose or Learning Objective: (1) To highlight the possible complication of peg fracture observed a decade after technically successful uncomplicated total knee replacement (TKR). (2) To evaluate imaging modalities and optimum magnetic resonance imaging (MRI) sequences to aid the diagnostic pathway.

Methods or Background: Knee surgeons have observed patients presenting with unexpected polyethylene peg fractures a decade after technically successful uncomplicated knee arthroplasty with the Journey 1 bicruciate substituting (BCS) prosthesis. In 2005, the Journey 1 BCS (Smith & Nephew, UK) was introduced to produce better flexion and improved function with the “guided motion mechanism” based on a more natural anatomical design. At 10 later, we have become aware of patients presenting with sudden nontraumatic knee instability due to peg fractures proven on arthroscopy. The peg fractures may be missed on initial imaging with nonoptimized MRI sequences. MRI sequences were evaluated for detecting complications with various techniques and slice thicknesses.

Results or Findings: A total of 272 Journey 1 TKRs were inserted from June 2010 to June 2013. Early complications included anterolateral pain from iliotibial band irritation, possibly due to excessive femoral rollback and femorotibial dislocations. However, other than the small number of patients with these early complications, the rest achieved excellent outcome parameters regarding both range of movement and outcome scores.

Four patients have since been found to have peg fractures a decade after an uncomplicated TKR. Three of them have undergone revision surgery; a fourth is awaiting surgery. The observed imaging findings include a joint effusion, with truncation or discrete fracture of the peg of the polyethylene liner of the tibial component or an intra-articular loose fragment. On radiographs, there is anterior tibial translation in flexion that would need to be specifically requested because knee radiographs are usually done in extension. MRI sequences included axial, coronal, and sagittal short tau inversion recovery, and sagittal proton density or T1. Our unit included slice encoding for metal artifact correction (SEMAC) metal reduction sequences with 4- to 9-mm slices.

Conclusion: It would be beneficial for radiologists to be aware of potential polyethylene peg fractures in patients with Journey 1 TKR prostheses, using imaging findings and optimized MRI sequences as described here.

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Artikel online veröffentlicht:
22. Mai 2024