Table 1

Demographics and descriptive statistics of cohort

	Chondroplasty cohort		Knee arthroplasty cohort
	All cases		No previous chondroplasty		Previous chondroplasty
	n	%	n	%	n	%
Total	157 730	100.00	568 140	94.05	35 916	5.95
Sex
Male	81 884	51.91	244 684	43.07	15 512	43.19
Female	75 846	48.09	323 456	56.93	20 404	56.81
Age group (years)
<20	2868	1.82	1179	0.21	1	<0.01
20–39	24 648	15.63	1568	0.28	353	0.98
40–59	83 258	52.79	85 797	15.1	14 023	39.04
60–79	45 191	28.65	400 541	70.5	20 361	56.69
80+	1765	1.12	79 055	13.91	1178	3.28
Charlson comorbidity index
0	121 605	77.10	534 399	94.06	27 331	76.1
1–15	34 719	22.01	31 683	5.58	8175	22.76
16–30	1296	0.82	1879	0.33	393	1.09
31–50	110	0.07	179	0.03	17	0.05
Index of multiple deprivation (quintiles)
1=least deprived	36 043	23.21	121 813	21.44	7921	22.05
2	35 189	22.66	127 672	22.47	7938	22.1
3	32 493	20.92	123 160	21.68	7806	21.73
4	27 312	17.59	103 236	18.17	6372	17.74
5=most deprived	24 266	15.62	85 283	15.01	5416	15.08
Missing	2427		6976		463
Rurality
Urban	119 766	76.42	423 895	74.61	27 157	75.61
Rural	36 953	23.58	141 271	24.87	8634	24.04
Missing	1011		2974		125
Ethnicity
White	141 928	94.43	525 934	92.57	34 349	95.64
Mixed	953	0.63	1844	0.32	115	0.32
Asian	4511	3.00	19 203	3.38	804	2.24
Black	2122	1.41	5840	1.03	193	0.54
Other	792	0.53	1367	0.24	68	0.19
Missing	7424		13 952		387
Concurrent procedures
None	65 987	41.84	–	–	–	–
Meniscal	91 743	58.16	–	–	–	–