Clinical characteristics of patients with type 2 diabetes mellitus and severe osteoarthritis

Abstract

Purpose: Type 2 diabetes mellitus (DM) and associated complications can make effective clinical management of osteoarthritis (OA) challenging. Prior studies have focused on the prevalence of OA among DM patients, but few studies have considered the reverse. Examining DM among patients with OA merits benefits for patients and musculoskeletal clinicians. Patients with DM undergoing a total knee (TKA) or hip (THA) arthroplasty, a viable intervention for terminal OA, are at high risks for adverse outcomes. Hence, gaining insight into the impact of DM on THA/TKA are necessary for reducing risks and determining effective intervention algorithms. The aims of this study are to examine patients with terminal OA and subsequent THA/TKA for: (1) determining the prevalence of DM; and (2) identifying the clinical severity and comorbidities of DM. Methods: We retrospectively screened 500 consecutive patients at University of Texas Medical Branch between January 2008 and April 2013 using the Current Procedure Terminology (CPT) codes for THA and TKA. Patients, who met a priori determined criteria to ensure THA and TKA were due to terminal OA, were reviewed for demographics (i.e., age and sex); clinical severity of DM and OA (i.e., smoking, body mass index, BMI, hemoglobin A1c, HgbA1c, DM management, bilateral OA, prior arthroplasty and time from DM to THA/TKA); and DM comorbidities (i.e., hypertension, dyslipidemia, nephropathy, diabetic neuropathy). We used omnibus comparisons to determine group differences within THA and TKA sub-groups with one-way ANOVA for continuous and chi-square for nominal variables. We used descriptive statistics to characterize DM. As a secondary, post hoc, analyses we graphed and visually examined the relationship between age and BMI for those with and without DM. Results: Of 137 THA and 223 TKA patients that met the a priori criteria, the prevalence of DM was 19% for THA and 24.2% for TKA. Patients with DM, for both THA and TKA sub-groups, were older than no DM (Table 1). We found significant group differences for sex, hypertension, nephropathy, dyslipidemia, bilateral OA, and prior arthroplasty (Table 1). The average time between DM diagnosis and TKA/THA was 9.8 years, the average HgbA1c level was 7.0, and DM management included oral (71.3%), insulin (6.30%), and both oral and insulin (10.0%). Peripheral neuropathy was present in 18.5% of TKA and 42.3% of THA cases. From secondary analyses of age and BMI, we observed slopes for the DM and no DM groups that were paralleling but had a larger y-intercept for DM (Fig. 1). Conclusions: We found a high prevalence of DM and comorbidities, among patients pursuing THA/TKA for terminal OA. Thus, musculoskeletal clinicians must consider DM presence when developing THA/TKA algorithms. DM, hypertension, and dyslipidemia, together, make up the metabolic syndrome. Metabolic syndrome has its own OA phenotype and includes patients with the most advanced ages and largest BMI than other OA phenotypes. In this study, those with DM are older than without DM when at the same BMI, which, in turn, may be due to THA/TKA delays. THA/TKA delays for patients with DM occur when HgbA1c levels are > 7.0 with the hopes of avoiding adverse events. However, this practice is problematic, because, for some patients, waiting for Hgb1Ac levels to drop below 7.0 may never occur, require up to 3 years, or be ineffective at avoiding adverse events. Delaying TKA/THA can also progress DM comorbidities including diabetic neuropathy, which facilitates inefficient movements and OA progression. The prevalence of diabetic neuropathy for our DM and THA/TKA cohort are larger than reported in the literature for those with DM only. Although more research is needed, this study suggests that current management algorithm for patients with DM are inadequate and delaying THA/TKA. We speculate that due to the inherent and progressive compromises of DM, terminal OA intervention algorithms need to consider earlier THA/TKA and to be defined for this sub-group.