Table 2.

Significance of patient, pre-, intra- and post-operative factors for length of stay

Factors	Available data	Statistical test	P	R
Patient age	112	Spearman’s	0.0138	0.0215
Patient sex	112	MWU	0.075
Marital status	112	KW	0.170
Lives with (alone, live with someone)	112	MWU	0.045
Support available on discharge	109	MWU	0.832
Pre-op mobility (independent without aids, walking stick, crutches, frame, wheelchair)	109	KW	0.00941
Comorbidity score	112	Spearman’s	0.137	0.140
BMI	112	Spearman’s	0.00839	−0.246
ASA grade	112	KW	0.400
Other previous joint replacements	112	KW	0.422
Pre-op Hb	112	Spearman’s	0.000485	−0.301
Pre-op platelets	112	Spearman’s	0.186	0.117
Type of anaesthetic (general vs. spinal)	112	MWU	0.84
Use of a local nerve block	112	KW	0.395
Tourniquet time	109	Spearman’s	0.059	−0.181
Weekday of surgery	112	KW	0.142
am vs. pm surgery	112	MWU	0.270
Post-op Hb	112	Spearman’s	0.000886	−0.287
Post-op platelets	112	Spearman’s	0.560	0.052
Hb drop	112	Spearman’s	0.560	0.051
Platelet drop	112	Spearman’s	0.478	0.063
Need for post-op blood transfusion	112	MWU	1.15E−05
Volume of autologous blood reinfusion	108	Spearman’s	0.915	−0.010
ITU/HDU admission	112	KW	0.0597
Day first shown exercises by the physiotherapist	112	KW	0.269
Able to mobilise within 24 hours of surgery	112	MWU	0.0140
Able to mobilise within 48 hours of surgery	112	MWU	0.00200
Post-op complications	110	KW	5.40E−09
Use of oral strong opioid analgesia	112	MWU	0.00318
Mobility on discharge (discharged on crutches or a walking frame)	112	MWU	0.00173
Post-op day mobilised 10 m	112	Spearman’s	2.26E−06	0.420
Post-op day achieved 90° knee flexion	92	Spearman’s	1.34E−13	0.677

BMI body mass index, MWU Mann-Whitney U test, KW Kruskall-Wallis test, Spearman’s Spearman’s rank correlation coefficient