Genicular nerve ablation outcomes

Author

Lu Mao

Published

September 3, 2026

Statistical analysis

Categorical variables are summarized as counts and percentages, while continuous variables are summarized as means and standard deviations. Linear mixed effects (LME) models are used to assess the association of baseline factors with the longitudinal reduction in typical pain score and WOMAC total score. The models include random intercepts for each subject to account for the with-subject correlation. A p-value of less than 0.05 is considered statistically significant. All analyses are performed using R (version 4.3.1). In particular, LME models are fitted using the lme4 package in R.

# A tibble: 4 × 3
  redcap_event_name     N_excluded_surg N_excluded_inj
  <chr>                           <int>          <int>
1 12_month__right_arm_1               7              9
2 1_month__right_arm_1                0              3
3 3_month__right_arm_1                2              5
4 6_month__right_arm_1                3              3

Results

Baseline characteristics

Demographics of the study population (N = 77) are summarized in Table 1 below.

Table 1: Demographics of the study population

Characteristic	N = 77¹
Age (years)	63 (12)
Sex
Female	67 (87%)
Male	10 (13%)
Height (cm)	165 (9)
Weight (kg)	107 (27)
BMI (kg/m^2)	39 (10)
Left knee surgery	50 (65%)
Right knee surgery	50 (65%)
Both knees surgery	23 (30%)
¹ Mean (SD); n (%)

Baseline knee information is summarized in Table 2 below.

Table 2: Baseline knee information

Characteristic	N = 100¹
side
Left	50 (50%)
Right	50 (50%)
KL grade
1	1 (1.0%)
2	3 (3.0%)
3	20 (20%)
4	76 (76%)
Medial joint space narrowing	85 (85%)
Lateral joint space narrowing	31 (31%)
Patellofemoral joint space narrowing	65 (65%)
Most severe joint space narrowing
Medial	70 (71%)
Lateral	9 (9.1%)
Patellofemoral	20 (20%)
Unknown	1
Current pain score	5.68 (2.15)
Typical pain score (last week)	6.68 (1.91)
Worst pain score (last week)	8.80 (1.39)
Anterior location of pain	78 (78%)
Medial location of pain	72 (72%)
Lateral location of pain	42 (42%)
Location of worst pain
Anterior	37 (37%)
Medial	43 (43%)
Lateral	20 (20%)
Not applicable (no pain)	0 (0%)
WOMAC total	54 (15)
¹ n (%); Mean (SD)

The one observation missing joint space narrowing is shown below.

study_id	side	most_severe_joint_space_na
68	Right	NA

Post operative outcomes

Post operative pain and WOMAC score reductions (from baseline) at 1, 3, 6 and 12 months are summarized in Table 3 below. The table is stratified by knee side (left or right) and overall. For the left knee, the reductions appear to dinimish over time; for the right knee, they are more persistent.

Table 3: Follow-up pain score and WOMAC reductions at 1, 3, 6 and 12 months

Overall
Characteristic	1 months N = 48¹	3 months N = 48¹	6 months N = 37¹	12 months N = 20¹
Current pain score reduction	3.0 (2.9)	2.2 (3.2)	1.2 (3.2)	-0.1 (3.0)
Typical pain score reduction (last week)	3.8 (3.1)	2.7 (3.0)	1.7 (3.1)	0.4 (2.6)
Worst pain score reduction (last week)	4.35 (3.01)	3.38 (2.88)	2.32 (2.61)	2.15 (2.37)
WOMAC total reduction	26 (21)	18 (20)	14 (18)	9 (15)
Unknown	2	1	3	2
¹ Mean (SD)

Overall
Characteristic	1 months N = 48¹	3 months N = 48¹	6 months N = 37¹	12 months N = 20¹
Current pain score reduction (%)	45 (47)	29 (56)	7 (74)	-19 (73)
Typical pain score reduction (last week) (%)	47 (38)	33 (46)	15 (65)	-1 (53)
Worst pain score reduction (last week) (%)	47 (34)	36 (31)	25 (31)	22 (25)
WOMAC total reduction (%)	43 (31)	33 (35)	23 (38)	14 (29)
Unknown	2	1	3	2
¹ Mean (SD)

Left knee
Characteristic	1 months N = 23¹	3 months N = 23¹	6 months N = 18¹	12 months N = 11¹
Current pain score reduction	2.9 (2.9)	1.9 (3.6)	1.4 (3.5)	-0.5 (3.2)
Typical pain score reduction (last week)	3.9 (3.0)	2.5 (3.5)	1.6 (3.3)	0.2 (2.5)
Worst pain score reduction (last week)	4.74 (2.90)	3.30 (2.84)	2.44 (2.75)	2.45 (2.42)
WOMAC total reduction	27 (19)	17 (19)	12 (19)	8 (13)
¹ Mean (SD)

Left knee
Characteristic	1 months N = 23¹	3 months N = 23¹	6 months N = 18¹	12 months N = 11¹
Current pain score reduction (%)	45 (51)	22 (62)	5 (90)	-40 (85)
Typical pain score reduction (last week) (%)	49 (38)	28 (54)	8 (84)	-9 (59)
Worst pain score reduction (last week) (%)	53 (31)	36 (31)	26 (34)	25 (27)
WOMAC total reduction (%)	47 (28)	29 (31)	16 (43)	12 (30)
¹ Mean (SD)

Right knee
Characteristic	1 months N = 25¹	3 months N = 25¹	6 months N = 19¹	12 months N = 9¹
Current pain score reduction	3.1 (3.0)	2.4 (2.8)	0.9 (3.0)	0.4 (2.7)
Typical pain score reduction (last week)	3.7 (3.1)	2.9 (2.7)	1.8 (2.9)	0.7 (2.9)
Worst pain score reduction (last week)	4.00 (3.12)	3.44 (2.97)	2.21 (2.55)	1.78 (2.39)
WOMAC total reduction	24 (23)	20 (21)	17 (16)	11 (20)
Unknown	2	1	3	2
¹ Mean (SD)

Right knee
Characteristic	1 months N = 25¹	3 months N = 25¹	6 months N = 19¹	12 months N = 9¹
Current pain score reduction (%)	44 (45)	36 (51)	9 (57)	6 (50)
Typical pain score reduction (last week) (%)	45 (39)	38 (37)	22 (39)	8 (46)
Worst pain score reduction (last week) (%)	41 (36)	37 (32)	25 (28)	18 (24)
WOMAC total reduction (%)	38 (34)	36 (39)	32 (31)	18 (30)
Unknown	2	1	3	2
¹ Mean (SD)

Figure 1: Follow-up pain score and WOMAC reductions (overall) at 1, 3, 6 and 12 months

Longitudinal modeling

Linear mixed effects (LME) models are fitted to assess the association of baseline factors with the longitudinal reduction in typical pain score and WOMAC total score. The models include random intercepts for each subject to account for the with-subject correlation.

Table 4 and Table 5 show the results of univariate LME models for typical pain score reduction and WOMAC total score reduction, respectively, with each predictor adjusting for time.

Table 4: Univariate linear mixed effects models for typical pain score reduction with each predictor, adjusting for time.

Predictor	Beta	95% CI	p-value
Age (years)	0.02	-0.04, 0.07	0.6
Male vs Female	-1.2	-3.3, 0.97	0.3
side			0.8
—Left
—Right	-0.10	-1.0, 0.83
BMI (kg/m^2)	0.07	-0.01, 0.15	0.087
KL grade 4 vs 1–3	1.6	-0.10, 3.3	0.065
Medial joint space narrowing	1.3	-0.34, 3.0	0.12
Lateral joint space narrowing	1.5	0.05, 2.9	0.043
Patellofemoral joint space narrowing	-1.8	-3.0, -0.53	0.005
Most severe joint space narrowing			0.4
—Medial
—Lateral	-0.29	-2.8, 2.2
—Patellofemoral	-1.2	-2.9, 0.51
Current pain score	0.61	0.32, 0.90	<0.001
Typical pain score (last week)	0.97	0.72, 1.2	<0.001
Worst pain score (last week)	0.63	0.26, 1.0	<0.001
Anterior location of pain	0.25	-1.7, 2.2	0.8
Medial location of pain	2.8	1.6, 4.0	<0.001
Lateral location of pain	-0.89	-2.0, 0.22	0.12
location_worst_pain			<0.001
—Anterior
—Medial	-0.95	-2.6, 0.74
—Lateral	-4.4	-6.1, -2.7
WOMAC total	0.04	0.00, 0.09	0.057
Nerve block pain relief category			0.005
—50-75% pain relief
—75.1-99.9% pain relief	2.6	0.93, 4.2
—100% pain relief	0.53	-0.86, 1.9

Table 5: Univariate linear mixed effects models for WOMAC total score reduction with each predictor, adjusting for time.

Predictor	Beta	95% CI	p-value
Age (years)	0.08	-0.33, 0.48	0.7
Male vs Female	0.54	-13, 14	>0.9
side			0.3
—Left
—Right	2.8	-2.9, 8.5
BMI (kg/m^2)	0.36	-0.19, 0.91	0.2
KL grade 4 vs 1–3	3.3	-8.2, 15	0.6
Medial joint space narrowing	1.3	-9.5, 12	0.8
Lateral joint space narrowing	6.2	-2.8, 15	0.2
Patellofemoral joint space narrowing	-11	-19, -3.7	0.003
Most severe joint space narrowing			0.032
—Medial
—Lateral	-6.9	-24, 10
—Patellofemoral	-14	-24, -3.3
Current pain score	2.3	0.45, 4.2	0.015
Typical pain score (last week)	2.7	0.83, 4.7	0.005
Worst pain score (last week)	2.6	0.28, 5.0	0.028
Anterior location of pain	4.4	-8.9, 18	0.5
Medial location of pain	12	3.9, 20	0.003
Lateral location of pain	0.84	-6.2, 7.9	0.8
location_worst_pain			0.012
—Anterior
—Medial	-1.8	-12, 8.3
—Lateral	-16	-27, -5.4
WOMAC total	0.60	0.34, 0.86	<0.001
Nerve block pain relief category			0.11
—50-75% pain relief
—75.1-99.9% pain relief	11	0.78, 21
—100% pain relief	5.3	-4.0, 15

Nerve block pain relief

Table 6: Nerve block pain relief category

Characteristic	N = 93¹
NB_pain_relief_cat
50-75% pain relief	31 (33%)
75.1-99.9% pain relief	16 (17%)
100% pain relief	46 (49%)
¹ n (%)