International Classification of Diseases-10-Based Risk Stratification and Implant Selection for Knee Arthroplasty Among Patients Who Have Psychiatric and Neurologic Comorbidities: A Registry-Based Analysis of 549,234 Cases.

Abstract

Psychiatric and neurologic comorbidities may worsen outcomes after total knee arthroplasty (TKA) or unicompartmental knee arthroplasty (UKA). We compared risks across eight International Classification of Diseases, Tenth Revision, German Modification (ICD-10-GM) clusters-psychiatric F00 to F39 and neurologic G20 to G64-and by implant constraint (unconstrained, constrained, unicompartmental). We analyzed 549,234 primary knee arthroplasties (2012 to 2024) from a national arthroplasty registry. Patients who had diagnoses were matched one-to-one to controls without F00 to F99 or G00 to G99 codes, adjusting for age, sex, body mass index (BMI), Elixhauser index, fixation, and implant type. Kaplan-Meier with 95% confidence intervals (CIs) estimated eight-year incidence; multivariable Cox models estimated hazard ratios (HRs) by diagnoses and implant. Complication patterns varied by cluster. Revision risk was highest in F20 to F29 (schizophrenia spectrum; HR 1.92, P = 0.001) and G20 to G26 (extrapyramidal/parkinsonian; HR 1.66, P < 0.001). Infection peaked in F00 to F09 (organic/cognitive; HR 2.34, P < 0.001) and G60 to G64 (polyneuropathy; HR 1.52, P < 0.001). Loosening increased from F30 to F39 (affective; HR 1.50) and from G20 to G26 (extrapyramidal/parkinsonian; HR 1.92, P < 0.001). All-cause mortality was highest in F20 to F29 (schizophrenia spectrum; HR 3.01, P < 0.001), F00 to F09 (organic/cognitive; HR 2.28, P < 0.001), and G30 to G32 (degenerative central nervous system [CNS]; HR 2.65, P < 0.001). Periprosthetic fracture after UKA tripled in F30 to F39 (affective; HR 3.99, P < 0.001), G20 to G26 (extrapyramidal/parkinsonian; HR 3.70, P < 0.001), and G40 to G47 (episodic/paroxysmal; HR 3.78, P < 0.001). Constrained TKA amplified infection and mortality across clusters. UKA lowered mortality in some cohorts (e.g., F30 to F39 (affective); HR 0.52, P < 0.001), but carried the highest loosening and fracture risk. Psychiatric and neurologic comorbidities are heterogeneous, independent predictors of failure after TKA/UKA; implant design modifies risk. An ICD-10-GM-based, code plus-name approach may guide implant selection, discourage use of constrained or unicompartmental devices in patients who are vulnerable, and inform perioperative care.