| Characteristic | N = 611 |
|---|---|
| Age (years) | 62 (13) |
| Height (cm) | 166 (9) |
| Weight (kg) | 106 (27) |
| BMI (kg/m^2) | 39 (10) |
| Left knee surgery | 37 (61%) |
| Right knee surgery | 37 (61%) |
| Both knees surgery | 13 (21%) |
| 1 Mean (SD); n (%) | |
Genicular nerve ablation outcomes
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.
Results
Baseline characteristics
Demographics of the study population (N = 61) are summarized in Table 1 below.
Baseline knee information is summarized in Table 2 below.
| Characteristic | N = 741 |
|---|---|
| side | |
| Left | 37 (50%) |
| Right | 37 (50%) |
| KL grade | |
| 1 | 1 (1.4%) |
| 2 | 3 (4.1%) |
| 3 | 16 (22%) |
| 4 | 54 (73%) |
| Medial joint space narrowing | 60 (81%) |
| Lateral joint space narrowing | 18 (24%) |
| Patellofemoral joint space narrowing | 40 (54%) |
| Most severe joint space narrowing | |
| Medial | 52 (71%) |
| Lateral | 7 (9.6%) |
| Patellofemoral | 14 (19%) |
| Unknown | 1 |
| Current pain score | 5.48 (2.08) |
| Unknown | 1 |
| Typical pain score (last week) | 6.67 (1.83) |
| Unknown | 1 |
| Worst pain score (last week) | 8.77 (1.46) |
| Unknown | 1 |
| Anterior location of pain | 62 (85%) |
| Unknown | 1 |
| Medial location of pain | 52 (71%) |
| Unknown | 1 |
| Lateral location of pain | 28 (38%) |
| Unknown | 1 |
| Location of worst pain | |
| Anterior | 33 (45%) |
| Medial | 29 (40%) |
| Lateral | 11 (15%) |
| Not applicable (no pain) | 0 (0%) |
| Unknown | 1 |
| WOMAC total | 55 (15) |
| Unknown | 1 |
| 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.
| Characteristic | 1 months, N = 411 | 3 months, N = 441 | 6 months, N = 391 | 12 months, N = 251 |
|---|---|---|---|---|
| Current pain score reduction | 2.8 (3.1) | 1.8 (3.2) | 0.4 (3.3) | 0.8 (3.7) |
| Typical pain score reduction (last week) | 3.8 (3.3) | 2.6 (3.2) | 1.2 (3.3) | 1.1 (3.6) |
| Worst pain score reduction (last week) | 4.4 (3.3) | 3.5 (3.2) | 2.0 (2.7) | 2.7 (3.2) |
| WOMAC total reduction | 26 (22) | 18 (20) | 12 (17) | 14 (24) |
| Unknown | 2 | 1 | 3 | 4 |
| 1 Mean (SD) | ||||
| Characteristic | 1 months, N = 191 | 3 months, N = 211 | 6 months, N = 181 | 12 months, N = 121 |
|---|---|---|---|---|
| Current pain score reduction | 2.5 (3.1) | 1.5 (3.7) | -0.1 (3.8) | -0.3 (4.2) |
| Typical pain score reduction (last week) | 3.6 (3.4) | 2.0 (3.6) | 0.4 (3.9) | 0.2 (3.7) |
| Worst pain score reduction (last week) | 4.68 (3.25) | 3.29 (3.02) | 1.89 (2.85) | 2.58 (3.00) |
| WOMAC total reduction | 27 (21) | 15 (20) | 9 (18) | 5 (18) |
| Unknown | 0 | 0 | 1 | 0 |
| 1 Mean (SD) | ||||
| Characteristic | 1 months, N = 221 | 3 months, N = 231 | 6 months, N = 211 | 12 months, N = 131 |
|---|---|---|---|---|
| Current pain score reduction | 3.0 (3.0) | 2.1 (2.9) | 0.8 (2.9) | 1.8 (2.9) |
| Typical pain score reduction (last week) | 3.9 (3.3) | 3.2 (2.7) | 1.9 (2.7) | 1.9 (3.4) |
| Worst pain score reduction (last week) | 4.1 (3.3) | 3.6 (3.4) | 2.1 (2.6) | 2.8 (3.4) |
| WOMAC total reduction | 25 (24) | 21 (21) | 15 (15) | 27 (26) |
| Unknown | 2 | 1 | 2 | 4 |
| 1 Mean (SD) | ||||
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 below shows the LME model for typical pain score reduction. The strongest predictor is baseline typical pain score, with one unit increase in the baseline score associated with a 0.98-unit higher reduction.
| Characteristic | Beta | 95% CI1 | p-value |
|---|---|---|---|
| time | <0.001 | ||
| 1 months | — | — | |
| 3 months | -1.0 | -1.9, -0.17 | |
| 6 months | -2.3 | -3.2, -1.4 | |
| 12 months | -2.2 | -3.3, -1.1 | |
| Age (years) | -0.04 | -0.11, 0.03 | 0.3 |
| sex | 0.5 | ||
| Female | — | — | |
| Male | -0.78 | -3.1, 1.5 | |
| BMI (kg/m^2) | -0.01 | -0.10, 0.09 | >0.9 |
| side | 0.2 | ||
| Left | — | — | |
| Right | 0.69 | -0.48, 1.9 | |
| KL grade | 0.46 | -1.1, 2.0 | 0.6 |
| Medial joint space narrowing | -0.52 | -3.5, 2.5 | 0.7 |
| Lateral joint space narrowing | 1.7 | -0.43, 3.9 | 0.12 |
| Patellofemoral joint space narrowing | -0.82 | -2.3, 0.62 | 0.3 |
| Most severe joint space narrowing | 0.5 | ||
| Medial | — | — | |
| Lateral | 0.30 | -3.9, 4.5 | |
| Patellofemoral | -1.5 | -4.1, 1.1 | |
| Current pain score | 0.13 | -0.26, 0.53 | 0.5 |
| Typical pain score (last week) | 1.0 | 0.49, 1.5 | <0.001 |
| Worst pain score (last week) | -0.03 | -0.64, 0.59 | >0.9 |
| Anterior location of pain | -0.94 | -3.2, 1.3 | 0.4 |
| Medial location of pain | 0.62 | -1.7, 2.9 | 0.6 |
| Lateral location of pain | -0.69 | -2.2, 0.81 | 0.4 |
| location_worst_pain | 0.079 | ||
| Anterior | — | — | |
| Medial | -1.4 | -3.1, 0.20 | |
| Lateral | -2.6 | -5.9, 0.72 | |
| WOMAC total | -0.02 | -0.07, 0.04 | 0.6 |
| 1 CI = Confidence Interval | |||
The LME model for WOMAC total score reduction is shown in Table 5 below. The strongest predictor is baseline WOMAC total score, with one unit increase in the baseline score associated with a 0.53-unit higher reduction.
| Characteristic | Beta | 95% CI1 | p-value |
|---|---|---|---|
| time | <0.001 | ||
| 1 months | — | — | |
| 3 months | -8.5 | -15, -2.4 | |
| 6 months | -12 | -19, -6.1 | |
| 12 months | -11 | -19, -3.4 | |
| Age (years) | 0.02 | -0.49, 0.53 | >0.9 |
| sex | 0.7 | ||
| Female | — | — | |
| Male | 3.6 | -13, 20 | |
| BMI (kg/m^2) | -0.47 | -1.2, 0.26 | 0.2 |
| side | 0.15 | ||
| Left | — | — | |
| Right | 6.1 | -2.1, 14 | |
| KL grade | 5.2 | -6.0, 16 | 0.4 |
| Medial joint space narrowing | -10 | -34, 13 | 0.4 |
| Lateral joint space narrowing | 11 | -5.6, 27 | 0.2 |
| Patellofemoral joint space narrowing | -4.6 | -15, 6.3 | 0.4 |
| Most severe joint space narrowing | 0.3 | ||
| Medial | — | — | |
| Lateral | -12 | -45, 21 | |
| Patellofemoral | -16 | -36, 4.2 | |
| Current pain score | -0.18 | -3.3, 2.9 | >0.9 |
| Typical pain score (last week) | 2.3 | -1.6, 6.2 | 0.3 |
| Worst pain score (last week) | 0.17 | -4.7, 5.0 | >0.9 |
| Anterior location of pain | -0.66 | -17, 16 | >0.9 |
| Medial location of pain | 4.5 | -16, 24 | 0.7 |
| Lateral location of pain | -2.8 | -15, 9.3 | 0.6 |
| location_worst_pain | 0.7 | ||
| Anterior | — | — | |
| Medial | -3.7 | -15, 8.1 | |
| Lateral | -8.9 | -35, 17 | |
| WOMAC total | 0.59 | 0.20, 0.99 | 0.003 |
| 1 CI = Confidence Interval | |||