Patellar complications after total knee arthroplasty.

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Abstract

[Indexed for MEDLINE] 2. J Am Acad Orthop Surg. 2019 Sep 1;27(17):642-651. doi: 10.5435/JAAOS-D-18-00347. Flexion Instability After Total Knee Arthroplasty. Stambough JB(1), Edwards PK, Mannen EM, Barnes CL, Mears SC. Author information: (1)From the Department of Orthopaedic Surgery, University of Arkansas for Medical Sciences, Little Rock, AR. Flexion instability after total knee arthroplasty (TKA) is caused by an increased flexion gap compared with extension gap. Patients present with recurrent effusions, subjective instability (especially going downstairs), quadriceps weakness, and diffuse periretinacular pain. Manual testing for laxity in flexion is commonly done to confirm a diagnosis, although testing positions and laxity grades are inconsistent. Nonsurgical treatment includes quadriceps strengthening and bracing treatment. The mainstays to surgical management of femoral instability involve increasing the posterior condylar offset, decreasing the tibial slope, raising the joint line in combination with a thicker polyethylene insert, and ensuring appropriate rotation of implants. Patient outcomes after revision TKA for flexion instability show the least amount of improvement when compared with revisions for other TKA failure etiologies. Future work is needed to unify reproducible diagnostic criteria. Advancements in biomechanical analysis with motion detection, isokinetic quadriceps strength testing, and computational modeling are needed to advance the collective understanding of this underappreciated failure mechanism. DOI: 10.5435/JAAOS-D-18-00347 PMCID: PMC6938456