Similar TKA designs with differences in clinical outcome

Figures & data

Figure 1. A. Sagittal view of the PFC design (left) and the CKS design (right). B. Anterior view of a computer model of the femoral components. Notice the lateral orientation of the trochlea in PFC (left) and neutral orientation in the CKS component (right). C. Posterior view of the tibial and PE insert components. The central posterior edge of the CKS insert (right) is relatively sharp compared to the PFC insert (left).

Table 1. Patient demographics and baseline clinical status

	PFC group (n = 38)	CKS group (n = 39)
Sex (female/male)	26/12	24/15
Age, years	65 (10; 45–81)	69 (11; 48–88)
Height, cm	169 (9; 154–187)	170 (11; 148–190)
Weight, kg	85 (18; 61–130)	82 (15; 60–120)
BMI	30 (5; 21–45)	28 (4; 21–39)
Diagnosis (OA/RA)	33/5	37/2
ROM, degrees
Extension	–4 (6; -20 to 0)	–5 (6; -20 to 5)
Flexion	109 (14; 75–135)	111 (19; 70–140)
Total ROM	104 (16; 65–125)	106 (20; 70–140)
KSS, points
Knee	53 (17; 9–95)	51 (17; 15–91)
Function	37 (20; -5–70)	42 (20; -10–90)
Total	89 (32; 4–150)	92 (29; 40–177)
WOMAC score, points	54 (13; 25–75)	52 (14; 25–95)
VAS pain	62 (17; 26–90)	55 (17; 20–91)

Figure 2. Flow diagram according to the CONSORT guidelines.

Table 2. Clinical results

	PFC group (n=38)	CKS group (n=39)	p-value
Revisions (no.)	1	6	0.1 ^a
Reoperations (no.)	1	8	0.03 ^a
ROM (deg)
Extension	-0.8 (4.1; -20–5)	-3.3 (6.9; -20–10)	0.05 ^b
Flexion	108 (15; 80–135)	104 (17; 65–140)	0.2 ^b
Total ROM	108 (17; 65–135)	100 (21; 45–140]	0.09 ^b
KSS (points)
Knee	88 (12; 59–100)	80 (19; 35–100	0.04 ^b
Function	65 (27; -20–100)	55 (30; -10–100	0.1 ^b
Total	153 (30; 71–200)	135 (43; 40–200)	0.04 ^b
WOMAC score (points)	20 (16; 0–57)	24 (22; 0–79)	0.3 ^b
VAS satisfaction	83 (20; 0–100)	71 (27; 0–100)	0.03 ^b
VAS pain	17 (24; 0–80)	24 (26; 0–70)	0.3 ^b
Radiolucency (no.)	2	3	1 ^a

^a Fisher exact test and ^b Student t-test.

Figure 3. Kaplan-Meier survival plots. A. With revision for any reason as endpoint, the PFC group had a survival of 97% (95% CI: 92–100) after 8 years and the CKS group had a survival of 84% (72–96) (p = 0.05). B. With aseptic revision as endpoint, the PFC group had a survival of 97% (92–100) after 8 years and the CKS group had a survival of 89% (78–99) (p = 0.2).

Figure 4. Kaplan-Meier survival plots. A. With any reoperation as endpoint, the PFC group had a survival of 97% (95% CI: 92–100) after 8 years and the CKS group had a survival of 79% (66–92) (p = 0.02). B. With aseptic reoperation as endpoint, the PFC group had a survival of 97% (92–100) after 8 years and the CKS group had a survival of 85% (73–97) (p = 0.08).