The Trifecta of Physiological States: Assessing the Synergistic Impacts of Frailty, Sarcopenia, and Osteoporosis in the Adult Spinal Deformity Population

Background: Adult spinal deformity (ASD) has been shown to compromise quality of life, and surgical correction has been shown to increase both short- and long-term patient reported and clinical outcomes. However, complication rates remain high, especially among patients with notable comorbidities like frailty, sarcopenia, and osteoporosis potentially negatively impacting outcomes. However, these three significant comorbidities have not been assessed in tandem in previous literature.

Purpose: To assess the synergistic effects of increasing frailty, sarcopenia, and osteoporosis on patient-reported, radiographic, and clinical outcomes in adult spinal deformity surgery.

Methods: Inclusion criteria were operative ASD patients (coronal Cobb angle≥20°, SVA≥50mm, PT≥25°, and/or thoracic kyphosis>60°) >18yrs with complete baseline (BL) and 2-year (2Y) radiographic/HRQL data. Two groups were created for initial comparison: those deemed frail (F) or severely frail (SF) by mASD-FI, with concurrent diagnoses of osteoporosis and sarcopenia per European Working Group on Sarcopenia in Older People (EWGSOP) psoas cross-sectional area thresholds (FOS+), and those without (FOS-) via means comparison analysis. Patients were further stratified and assessed by presence and influence of individual aforementioned comorbidities via three-way ANOVA. Backstep logistic regression analysis assessed risk of achieving Smith et al. Best Clinical Outcomes (BCO) while controlling for age, levels fused, and severity of deformity per PI-LL.

Results: 220 patients with adult spinal deformity were assessed (58.3 ± 10.7 years, 57% female, BMI 30.0±7.3 kg/m2, 36% osteoporosis), and underwent surgical correction (levels fused 5.2 ± 2.6, EBL: 772 ± 672 mL, operative time: 399 ± 139 min, LOS: 6.2 ± 8.1 days). By surgical approach, 13.8% anterior-only, 51.7% posterior-only, and 34.5% combined. 53.1% of patients underwent osteotomy (4.6% had a three-column osteotomy), and 46% received BMP. Overall, 16.4% of the cohort were classified as FOS+. At baseline, FOS+ were older (65.33 vs 55.67, p=.044), and had a greater total Charlson Comorbidity Index scores than FOS- patients. Furthermore, FOS+ patients were significantly more likely to be female (76% vs 53%, p<.001) compared to FOS- patients. Three-way analysis revealed that increasingly frail FOS+ patients with or without osteoporosis were more likely to present with worse radiographic markers at BL per PI-LL (p=.005), SVA (p=.043), and PT (p=.035). Peri-operatively, and controlling for age and levels fused, FOS+ patients were significantly more likely to experience any neurological complication within 90 days of surgery (p=.004). Post-operatively, FOS- patients demonstrated lower mean disability per ODI and SRS-22 Appearance subdomains (p=.031, p<.001). Adjusted regression analysis demonstrated that FOS- were also significantly more likely to achieve BCO by 2Y post-operatively (p=.039).

Conclusion: Increased frailty, in conjunction with a history of osteoporosis and sarcopenia, demonstrates a unique trifecta of comorbidities that may increase the risk of suboptimal post-operative outcomes. The present study demonstrates that frail, osteoporotic, and sarcopenic patients are more likely to be female, and may be at increased risk of neurological complications. Furthermore, the disability ceiling may be lower for such patients, as are rates of meeting optimal clinical outcomes post-operatively. However, further study is needed to more granularly assess the incidence and impact of each comorbidity in such patients.