Prevalence and Risk Factors of Osteoporosis in Chinese Postmenopausal Women Awaiting Total Knee Arthroplasty

Figures & data

Table 1 Demographics and Characteristics of Women Awaiting TKA

Variables	n (%)
Age (years)
<60	22 (10.78%)
≥60, <70	84 (41.18%)
≥70, <80	78 (38.24%)
≥80	20 (9.80%)
Knee OA side
Double	180 (88.2%)
Single	24 (11.8%)
Kellgren-Lawrence grade of study side
III	74 (36.3%)
IV	130 (63.7%)
Bone quality status based on the lowest T-score among multiple sites
Osteoporosis	122 (59.8%)
Osteopenia	72 (35.3%)
Normal	10 (4.9%)

Abbreviations: TKA, total knee arthroplasty; OA, osteoarthritis.

Figure 1 Distribution of bone quality status of different age groups. *P<0.05, ***P<0.001.

Abbreviation: ns, no significance.

Figure 2 Osteoporosis prevalence based on different DXA examination sites. **P<0.01, ***P<0.001.

Abbreviation: OP, osteoporosis.

Table 2 The Exact Number of Different Sites Tested Positive for OP and Their Diagnostic Discordance

Site Positive for OP	Number	Percentage of Number of Site Negative for OP (n)
		Femoral Neck	Proximal Femur	Lumbar Spine
Femoral neck	58	—	58.62% (34)	17.24% (10)
Proximal femur	28	14.29% (4)	—	7.14% (2)
Lumbar spine	111	56.76% (63)	76.58% (85)	—
Multiple sites	122	—	—	—

Abbreviation: OP, osteoporosis.

Figure 3 BMD of the femoral neck (A) and the lumbar spine (B) of different age groups compared to the age/ethnicity-adjusted reference population. *P<0.05, **P<0.01, ***P<0.001.

Abbreviations: BMD, bone mineral density; FN, femoral neck; LS, lumbar spine; ns, no significance.

Table 3 Comparison Between Non-OP and OP Women Awaiting TKA

Variables	Non-OP (n=82)	OP (n=122)	P-value
Demographics
Age (years) *	67.85 (61.93, 74.85)	70.55 (65.48, 75.85)	0.023
BMI (kg/m^2)	26.21 ± 3.93	25.00 ± 4.07	0.035
Disease course
Symptom duration (years) *	10.00 (5.00, 10.25)	8.00 (3.00, 10.00)	0.192
Blood nutritional marker
Hemoglobin (g/L) *	122.00 (116.00, 129.50)	122.00 (115.00, 129.25)	0.885
Lymphocyte count (10^9/L) *	1.65 (1.40, 2.04)	1.67 (1.32, 2.03)	0.736
Prealbumin (mg/L)	213.16 ± 39.77	211.44 ± 43.89	0.777
Total protein (g/L)	68.19 ± 5.10	67.7 ± 5.04	0.509
Albumin (g/L)	41.28 ± 3.27	41.24 ± 2.90	0.916
Serum chemistry profile
Ca^2+ (mmol/L) *	2.26 (2.21, 2.33)	2.26 (2.21, 2.33)	0.859
Creatinine (mmol/L) *	60.00 (53.00, 66.50)	59.00 (52.00, 66.00)	0.824
eGFR (mL/min/1.73m^2) *	93.30 (86.45, 100.55)	91.95 (83.10, 98.58)	0.208
Incidence of OA-related parameters
Bilateral knee OA	85.4% (n=70)	90.2% (n=110)	0.297
Varus deformity	56.1% (n=46)	71.3% (n=87)	0.025
Valgus deformity	20.7% (n=17)	15.6% (n=19)	0.343
Flexion contracture	41.5% (n=34)	41.8% (n=51)	0.961
K-L Grade IV	61.0% (n=50)	65.6% (n=80)	0.503
Patellofemoral OA	74.4% (n=61)	75.4% (n=92)	0.869
Attrition	30.5% (n=25)	26.2% (n=32)	0.506

Notes: Variables with “*” were demonstrated in median with interquartile range and compared between groups using Mann–Whitney U-test. Bolded values indicate statistical significance (P<0.05).

Abbreviations: OP, osteoporosis; TKA, total knee arthroplasty; BMI, body mass index; Ca²⁺, calcium; eGFR, estimated glomerular filtration rate; OA, osteoarthritis; K-L, Kellgren-Lawrence.

Table 4 Binary Logistic Regression Analysis for the Determination of Independent OP Risk Factors in Postmenopausal Women Awaiting TKA

Variables	Odds Ratio(95% CI)	S.E.	Wald	P-value
Age (years)
≥60	7.76 (2.49–24.18)	0.58	12.51	<0.001
BMI (kg/m2)
<25	1.85 (1.01–3.40)	0.31	3.91	0.048
Varus deformity	2.10 (1.13–3.92)	0.32	5.43	0.020

Note: Bolded values indicate statistical significance (P<0.05).

Abbreviations: OP, osteoporosis; TKA, total knee arthroplasty; BMI, body mass index; CI, confidence interval; S.E., standard error.