Table 1 Description of eligible studies

Chang et al., 2014 [17]

Retrospective study

225 (15 M)

Laterality — NS

Preoperative primary TKA due to advanced primary KOA

69 + 6.5

26.8 + 3.5

100%

Pain, stiffness, physical function (WOMAC)

Physical status (SF-36)

Pain VAS

Radiographical changes

Diminished pain (β, 0.08, p = 0.28), physical function (β, −0.02, p = 0.80), and physical status (β, −0.001, p = 0.99): not associated with radiographic severity of lumbar spine degeneration

LBP severe grade (VAS 7–10): associated with knee pain (regression coefficient with 95% CI −11.66 (−21.50 to −1.82))

Function: Affected by severe LBP (VAS scores 7–10) (regression coefficient with 95% CI −17.8 (−26.36 to −9.24))

Poorer function: Associated with moderate symptom grade (regression coefficient with 95% CI −5.64 (−12.24 to 1.07)

Physical status: Affected by severe LBP (VAS scores 7–10) (regression coefficient with 95% CI −1.61 (−4.74 to −1.52)

Radiographic lumbar spine degeneration: Found in all study subjects without exception (patients’ percentage below mentioned)

• Mild degeneration: 11%

• Moderate degeneration: 72%

• Severe degeneration: 17%

Lumbar spine symptoms LBP VAS scores (mean ± SD, 3.1 ± 2.7): Considerable proportion of patients had coexisting moderate to severe symptoms at the time of TKA (patients’ percentage below mentioned)

• No/mild pain VAS 0–3 (60%)

• Moderate pain VAS 4–6 (28%)

• Severe pain VAS 7–10 (12%)

Huang et al., 2014 [18]

RCT

Eight — severe bilateral KOA patients with chronic nonspecific LBP group

Seven —healthy participants aged 23.00 (20.00/24.00) years, without OA, LBP, or other musculoskeletal symptoms (control group), 8 — bilateral KOA patients without LBP (NLBP group)

NS

NS

NS

Knee flexion

Pain

Functional disability of the patients with knee OA (Lequesne’s index scores)

Trunk flexion

Pelvic anterior tilt

Anterior trunk inclination angle

Physical disability due to back pain (RDQ)

Back pain intensity

(ODI)

Trunk flexion angles (°): Smaller in KOA patients compared to healthy people without KOA or LBP (median (IQR), with LBP −27.65 (−33.07/−20.10); non-LBP −27.44 (−32.83/−24.30); healthy −40.43 (−46.46/−36.44))

Trunk rotation angle (°): Smaller in NLBP group than that of the controls (median (IQR), with NLBP 6.01 (3.89/8.23); controls 9.15 (6.57/10.25)

Knee flexion angles in ipsilateral side of bending (°): Significantly smaller when doing the downward pickup movement in both the LBP and NLBP groups (median (IQR), with LBP −7.54 (−12.31/−3.78); non-LBP −6.39 (−12.95/−4.05); controls −19.89 (−31.63/−6.50))

Pelvic anterior tilt (°): Greater in KOA compared to the healthy people (median (IQR), with LBP −44.68 (−50.18/−40.52); NLBP −45.83 (−48.56/−39.38); healthy −32.61 (−37.05/−28.47))

Anterior trunk inclination angle(°): No significant difference between KOA and healthy people (median (IQR), with LBP −82.13 (−89.33/−73.23); NLBP −83.96 (−88.80/−74.07); controls −85.05 (−85.96/81.92)

Physical disability: Higher in LBP group (median (IQR), with LBP 9 (7.3/10.8); non-LBP 3.5 (2.0/5.8))

Levels of back pain intensity component: Higher in LBP group (median (IQR), with LBP 1.0 (1.0/2.0); non-LBP 0.5 (0.0/1.0))

Pain and functional disability of the patients with knee OA: No statistically significant difference between LBP and non LBP (median (IQR), with LBP 11.0 (9.3/15.0); 13.0 (10.0/14.0))

Iijima et al., 2018 [8]

Cross-sectional study

260 (22.3% M) — community-dwelling participants with knee OA (K/L grade ≥ 1), OA with LBP −151 and OA without LBP −109

OA with LBP 68.6 ± 9.3, OA without LBP 70.7 ± 9.0

OA with LBP 22.9 ± 3.7, OA without LBP 22.0 ± 3.2

58.1%

Knee pain severity and disability JKOM

Pain NRS

LBP: Associated with increased disability level (β: 0.69; 95% CI: 0.01 to 1.37) (p = 0.05)

Relationships of LBP and disability level: Slightly increased in moderate to severe LBP (β:1.01; 95% CI: 0.22 to 1.80) (p = 0.01)

Relationship between knee pain intensity and disability level: Higher in individuals with LBP (β: 0.62; 95% CI: 0.51 to 0.73) than in those without LBP (β: 0.40; 95% CI: 0.32 to 0.49)

Iwamura et al., 2020 [19]

NS

57 (10 M) DS patients who complicate KOA (KOA group), 127 (33 M) DS patients without KOA (non-KOA group)

72.7 ± 7.0, 69.4 ± 8.2

24.5 ± 3.8, 22.8 ± 2.8

NS

NS

Parameters in lumbo-pelvic sagittal alignment: PI, PT, LL, PI-LL, SS

Lumbo-pelvic sagittal alignment: Development and progression of KOA in DS patients is induced by significantly greater (p = 0.02) mismatches of lumbo-pelvic sagittal alignment

Parameters in lumbo-pelvic sagittal alignment: PI (°); PT(°); LL(°); PI-LL and SS (°) of KOA group and non-KOA group were mean ± SD, 27.2 ± 9.8 and 22.2 ± 8.6, 40.4 ± 15.8 and 42.6 ± 14.3, 17.9 ± 15.1 and 10.3 ± 12.9, and 30.6 ± 10.0 and 30.6 ± 8.9, respectively

Significant difference was observed in the rate of double adjacent level spondylolisthesis (p = 0.02) and in the following sagittal parameters: PT (p < 0.01), PI-LL (p < 0.01)

Kohno et al., 2020 [20]

Retrospective study

Patients with DLS comorbid with 42-mild OA group, 28 — moderate OA group, 40 — severe OA group

74

22.6 ± 3.2

23.4 ± 3.2

23.9 ± 2.9

NS

KFA

PI

PT

PI, PT, and KFA: Significantly greater in severe OA group, than mild OA group along with a smaller degree of LL than the mild-OA group preoperatively (all p < 0.05)

PI (°): Significantly greater in severe OA group ( mean ± SD, 7 ± 8.7) than the mild OA group (51.8 ± 9.6) (p = 0.05)

PT (°): Significantly greater in severe OA group ( mean ± SD, 28.8 ± 9.3) than the mild OA group (20.1 ± 8.3) (p < 0.01)

LL (°): Significantly smaller in severe OA ( mean ± SD, 38.7 ± 12.2) than the mild OA (45.6 ± 13.0) (p = 0.04)

KFA (°): Significantly greater in severe OA ( mean ± SD, 10.1 ± 5.3) group than the mild-OA (4.9 ± 6.8) group preoperatively (p = 0.02)

Rate of radiographic ASD: Higher in the severe-OA group than in the mild-OA group (p = 0.02) patients percentage (38%)

PT (°): Significantly greater in patients with ASD ( mean ± SD, 26.2 ± 7.0) in the severe-OA group than the patients without ASD (34.1 ± 10.8) (p = 0.02)

LL (°): Less in patients with ASD (mean ± SD, 34.9 ± 14.6), than without ASD (40.6 ± 9.9) (p = 0.26)

Rate of double-level listhesis: Significantly higher in the severe-OA group compared with the other groups (p = 0.01) (patients number %), mild OA group 12; moderate OA 31; severe OA 40

Staibano et al., 2014 [21]

Prospective cohort study

491 (40.1% M) patients with end-stage KOA

67.6 ± 9.6

31.9 ± 6.4

47.3%

NS

Back pain

Degree of disability due to back pain (ODI)

Degree of disability due to back pain: Minimal (mean ± SD, 14.5 ±14) due to back pain in preoperative TKA patients with none or very mild LBP (p = 0.01)

Pain on the ODI: Significantly higher among knee patients with a 68.4% (95% CI, 57.4–77.6%)

Stupar et al., 2010 [12]

Population-based cohort study

406 LBP

NS

NS

58%

Pain, stiffness, and physical function (WOMAC)

NS

Pain and disability: Not associated with LBP in individuals with KOA (β = 0; 95% CI, −3.39 to 3.39; p = 0.99)

Suri et al., 2010 [7]

NR

1389 (40.1% M) people with KOA

61.4 ± 9.1

30.2 ± 4.9

57.4%

Pain component (WOMAC)

NS

LBP: Significantly associated with increased functional score (β = 1; p < 0.01) (WOMAC score with LBP mean ± SD, 6.5 ± 4.1, without LBP 5.2 ± 3.4)

Taniguchi et al., 2021 [23]

Cross-sectional

586 (116 M) participants with x-ray-confirmed KOA

68.8 ± 5.2

NS

NS

Functional abilities related to knee (KSS)

Lumbar kyphosis

LBP and lumbar kyphosis: Independently associated with a lower function (LBP alone MD 95% CI, −4.96 (−7.56 to 13, −2.36); lumbar kyphosis alone, −4.47 (−8.51 to −0.43)

Coexistence of LBP and lumbar kyphosis −13.86 (−18.86 to −8.86))

Coexistence of LBP and lumbar kyphosis: Was associated with a lower function in women (MD 95% CI −4.49 (−6.42 to −2.55))

Van Erp et al., 2020 [16]

Cohort study

421 (116 M) hip and KOA

56.1 ± 5

26.6 ± 4

NS

NS

PI

PI (°): Significantly higher incidence of knee OA was observed in patients with a high PI, compared with those with normal PI (OR 1.70, 95% CI 1.07 to 2.71) (p = 0.02) or low PI (OR 1.62, 95% CI 1.04 to 2.53 (p = 0.03)

High PI (> 60°): Is a risk factor for development of spondylolisthesis (L4 to L5, p = 0.02) and KOA (p = 0.03)

Wang et al., 2016 [9]

Cross-sectional study

59 (16) patients with severe KOA, 58 (14) asymptomatic persons free from KOA

65.9, 62.9

NS

66.1%

NS

Sagittal alignment of the pelvis and hip: PI, PT, SS, PFA, SFA, FI, spinosacral angle, and C7 tilt

Sagittal alignment: No significant difference between KOA patients with and without LBP

Comparable PI, SS, and PT values were revealed between the two groups, suggesting similar sagittal morphology and pelvic alignment

PI (°): With LBP mean ± SD, (48.5 ± 10.4); without LBP (45.0 ± 10.0) (p = 0.68)

SS (°): With LBP (36.2 ± 9.2); without LBP (32.9 ± 8.4) (p = 0.92)

PT (°): With LBP (12.5 ± 6.3); without LBP (12.2 ± 7.1) (p = 0.32)

Severe KOA patients showed significantly larger FI (11.3° versus 4.2°, p < 0.01) and smaller SFA (43.1° versus 51.8°, p < 0.01) and PFA (2.2° versus 9.1°, p < 0.01) values compared with controls

These results indicate flexed knee and hip joints among patients with severe KOA

C7 tilt: Significantly smaller among severe KOA patients compared with controls (88.4° versus 92.9°, p < 0.01), indicating forward inclination of the spine

Wolfe et al., 1996 [6]

NS

368 (23.1% M) diagnosed clinically as having KOA

NS

31.0

54.6%

NS

Disability (HAQ)

Pain VAS

Back pain: Strongly associated with knee pain (p = 0.03)

Knee pain VAS (1–1.9): OR 2.18, 95% CI (2.03, 3.83)

Knee pain VAS (≥ 2): OR 4.89, 95% CI (2.60, 9.20)

Disability (p < 0.01): Strongly associated with back pain (p = 0.03)

Disability (1–1.9): OR 2.12, 95% CI (1.37, 3.30)

Disability (≥ 2): OR 6.84, 95% CI (2.87, 16.26)

Yasuda et al., 2020 [22]

Large cohort study of volunteers

396 (160 M) volunteers over 50 years of age

74.4

NS

NS

KL grading scale

Spinopelvic sagittal alignment: PT, PI, LL, thoracic kyphosis, and SVA, ODI

Lumbo-pelvic sagittal alignment: Poor in individuals over 50 years of age with severe KOA and has stronger relationship with progression severity of KOA in women than in men

PT (°): Mean ± SD, KL1 (15.8 ± 7.5), KL2 (20.1 ± 8.8), KL3 (21.4 ± 9.2), KL4 (24.7 ± 9.5) (p = < 0.01)

Degree of disability due to back pain: Progression severity of KOA had more impact on stronger relationship with disability-related LBP in (women > men) (p = 0.02)

ODI score: KL1 ( mean ± SD, 9.9 ± 10.8), KL2 (12.2 ± 11.9), Kl3 (1 ± 12.1), KL4 (16.1 ± 13.0)

ODI score: Higher in the KL4 than in the KL1