Preoperative patellofemoral anatomy affects failure rate after isolated patellofemoral inlay arthroplasty

Table 1 Outcome scores of the total study group, the non-failed group, and clinical failures (patients not achieving MCID for WOMAC total or VAS pain at 24 months)

	Total study group	Non-failed	Clinical failures
VAS pain preoperative	5.6 ± 2.0	6.2 ± 1.8	4.0 ± 1.4^b
VAS pain 24 months	2.9 ± 1.9^a	2.6 ± 2.1^a	3.8 ± 0.9^b
VAS pain delta	2.6 ± 2.2	3.6 ± 1.9	0.2 ± 0.8^b
WOMAC total preoperative	67.8 ± 13.6	65.7 ± 14.3	73.5 ± 10.2
WOMAC total 24 months	79.0 ± 15.3^a	83.2 ± 13.4^a	67.9 ± 14.9^b
WOMAC total delta	11.2 ± 19.1	17.6 ± 17.7	−5.5 ± 11^b
WOMAC pain preoperative	64.9 ± 18.6	60.8 ± 18.7	75.0 ± 14.5 ^b
WOMAC pain 24 months	82.0 ± 15.4^a	85.4 ± 15.5^a	73.5 ± 12.0^b
WOMAC pain delta	17.1 ± 22.2	24.6 ± 20.1	−1.5 ± 15.8^b
WOMAC stiffness preoperative	59.3 ± 22.1	56.5 ± 23.1	66.3 ± 18.7
WOMAC stiffness 24 months	70.4 ± 22.1^a	76.0 ± 18.7^a	56.3 ± 24.5^b
WOMAC stiffness delta	11.1 ± 31.1	19.6 ± 27.9	−10.1 ± 29.6^b
WOMAC function preoperative	69.8 ± 14.1	68.2 ± 15.2	73.7 ± 10.4
WOMAC function 24 months	78.9 ± 15.8^a	83.4 ± 13.9^a	67.6 ± 15.1^b
WOMAC function delta	8.4 ± 19.2	14.2 ± 19.1	−6.1 ± 9.2^b
Lysholm preoperative	41.2 ± 18.2	40.2 ± 18.6	43.9 ± 17.8
Lysholm 24 months	65.3 ± 20.4^a	69.1 ± 20.3^a	55.3 ± 18.0^b
Lysholm delta	24.0 ± 20.0	28.9 ± 21.2	11.4 ± 7.5^b

Patients undergoing conversion to total knee arthroplasty were excluded from data analysis
Values are shown as mean ± standard deviation
MCID minimal clinically important difference, VAS Visual analog scale, WOMAC Western Ontario McMaster Universities Osteoarthritis Index
^aStatistically significant improvement compared to preoperative (p < 0.05)
^bStatistically significant difference compared to “non-failed” (p < 0.05)