Table 2

Comparison of changes in primary and secondary outcomes at the main trial endpoint (24 months from baseline)

	Arthroscopic partial meniscectomy	95% CI	Skin incisions only	95% CI	Comparison	95% CI	P value
	Mean change	95% CI	Mean change	95% CI	Mean diff	95% CI	P value
Primary endpoint
KOOS₅	21.8	11.2 to 32.4	13.6	3.0 to 24.2	8.2	−3.4 to 19.8	0.161
KOOS₅ response (ie, at least 30% increase)*, n (%)	11 of 22 (50)		7 of 20 (35)		0.15†	−0.15 to 0.45	0.327‡
KOOS subscales
Pain	23.9	12.9 to 34.9	14.0	2.7 to 25.2	9.9	−2.1 to 21.9	0.110
Symptoms	16.8	6.6 to 27.0	10.2	−0.0 to 20.5	6.6	−4.3 to 17.4	0.240
Function in daily living	20.0	10.4 to 29.6	11.0	1.3 to 20.7	9.0	−1.4 to 19.4	0.095
Function in sport and recreation	18.5	2.5 to 34.5	12.9	−3.9 to 29.7	5.6	−11.8 to 23.0	0.529
Knee-related quality of life	23.1	12.0 to 34.1	11.5	0.3 to 22.7	11.5	−0.4 to 23.4	0.062
EQ-5D
VAS score	5.8	−2.6 to 14.2	12.4	3.8 to 21.0	−6.6	−15.7 to 2.6	0.164
EQ-5D-3L index value	0.16	0.08 to 0.23	0.11	0.03 to 0.19	0.05	−0.04 to 0.13	0.301
SF-36 (acute version)
Physical component summary	7.9	2.8 to 12.9	5.8	0.7 to 10.9	2.1	−3.3 to 7.5	0.452
Mental component summary	−1.2	−5.3 to 2.9	1.3	−2.9 to 5.5	−2.5	−6.8 to 1.8	0.256
GPE
Score, median (IQR)	6	5–6	5	4–6	1	0 to 2	0.122§
Response (ie, 6 or 7)¶, n (%)	14 of 21 (67)		7 of 19 (37)		0.30†	0.00 to 0.59	0.059‡
Physical performance measures
One-leg hop test (affected knee), cm**	8.7	−2.0 to 19.4	−0.2	−11.1 to 10.7	8.9	−3.2 to 21.0	0.155
One-leg hop test (non-affected knee), cm**	0.7	−9.7 to 11.1	−5.2	−15.7 to 5.4	5.9	−5.4 to 17.3	0.312
Knee bending test, max number of knee bends (affected knee), n**	2.1	−2.4 to 6.5	1.2	−3.3 to 5.8	0.9	−4.2 to 5.9	0.740
Knee bending test, max number of knee bends (non-affected knee), n**	−0.1	−4.3 to 4.2	2.1	−2.3 to 6.5	−2.2	−7.1 to 2.8	0.392
Isometric knee extensor strength (affected knee), Nm/kg**	0.98	0.70 to 1.27	0.81	0.53 to 1.09	0.17	−0.08 to 0.42	0.191
Isometric knee extensor strength (non-affected knee), Nm/kg**	0.94	0.61 to 1.27	0.72	0.40 to 1.04	0.23	−0.05 to 0.50	0.117

Data were analysed using repeated measures mixed linear models; no imputations for missing data at 3-month and 24-month follow-ups. Imputation of missing values at baseline was done for all variables by imputing the mean of the follow-up values. However, if one or both of the follow-up values were missing, no imputation of values at baseline was done.
*Two patients with missing data in the skin-incisions-only group were not included.
†Risk difference.
‡The P value for the risk ratio is obtained from a χ² test.
§The P value for the difference in medians is obtained from a Mann-Whitney U test.
¶One and three patients with missing data at follow-up in surgery and skin-incisions-only groups, respectively, were not included.
**One patient in the arthroscopic partial meniscectomy group and two patients in the placebo group had no baseline value, and it was not possible to impute a follow-up value since one or both of the follow-up values were missing as well, hence these patients could not be included in the analyses.
GPE, Global Perceived Effect; KOOS₅, Knee injury and Osteoarthritis Outcome Score subscale 5; SF-36, Short-Form 36 items; VAS, Visual Analogue Scale.