Patient specific guides for total knee arthroplasty are ready for primetime

Table 1 Different industries with brand names, guide type, implant name and scanning modality

	Dupuy-Synthes	Smith and Nephew	Zimmer	Biomet
PSG	Trumatch	Visionaire	PSI	Signature
Guides	Cut	Cut	Pin	Pin
Implant	Sigma CR	Genesis II	NexGen	Vanguard CR
Imaging protocol	CT1	MRI2	CT or MRI1	CT or MRI1

¹Scan of the hip, knee and ankle join;

²MRI of the knee joint with long leg standing X-ray. PSI: Patient-specific instrument; PSG: Patient specific matched guides; CT: Computed tomography; MRI: Magnetic resonance imaging; CR: Computed radiography.

Table 2 Baseline demographics per alignment method, n (%)

	Trumatch	Visionaire	PSI	Signature	Conventional	P value
Number of patients	15	13	14	15	60
Mean age, yr (range)	72 (57-90)	72 (63-82)	69 (52-86)	68 (56-74)	65 (50-83)	0.097
Male	6 (40)	7 (54)	7 (50)	7 (47)	34 (57)	0.967
Mean BMI (range)	30 (23-36)	30 (23-37)	30 (26-36)	30 (23-38)	28 (21-37)	0.373
Severity OA
Moderate	13 (87)	11 (85)	13 (93)	14 (93)	53 (88)	0.991
Severe	2 (13)	2 (15)	1 (7)	1 (7)	7 (12)	0.959

PSI: Patient-specific instrument; BMI: Body mass index; OA: Osteoarthritis.

Table 3 Inter observer correlation coefficients

	HKA	FFC	FTC	LFC	LTC
Inter CC	0.811	0.879	0.883	0.850	0.943

HKA: Hip-knee-ankle angle; FFC: Frontal femoral component; FTC: Frontal tibial component; LFC: Flexion/extension of the femur component; LTC: Lateral tibial component; CC: Class correlation coefficient.

Table 4 Mean (SD) values and amount of patients and percentages of outliers of > 3˚ deviation of the planned alignment and postoperative alignment compared between the patient specific matched guides and the conventional group, n (%)

Outliers	PSG	Conventional	P value
HKA outliers	7 (12.28)	11 (18.33)	0.424
Mean (SD)	179.49 (2.24)	178.54 (2.27)	0.015
FFC outliers	0 (0)	11 (18.33)	0.000
Mean (SD)	89.44 (1.73)	88.03 (1.73)	0.000
FTC outliers	1 (1.75)	0 (0)	1.000
Mean (SD)	89.87 (1.32)	90.37 (1.38)	0.058
LFC outliers	9 (15.78)	35 (58.33)	0.000
Mean (SD)	86.09 (2.86)	86.04 (3.14)	0.314
LTC outliers	9 (15.78)	25 (41.67)	0.033
Mean (SD)	92.86 (2.64)	87.43 (2.63)	0.000

PSG: Patient specific matched guides; HKA: Hip-knee-ankle angle; FFC: Frontal femoral component; FTC: Frontal tibial component; LFC: Flexion/extension of the femur component; LTC: Lateral tibial component.

Table 5 Mean (SD) values and amount of patients and percentages of outliers of > 3˚ deviation of the planned alignment and postoperative alignment compared between the patient specific matched guides groups, n (%)

	Trumatch	Visionaire	PSI	Signature	P value
HKA outliers	3 (20.00)	1 (7.69)	2 (14.28)	1 (6.66)	0.819
Mean (SD)	178.5 (2.3)	181.3 (1.6)	180.6 (1.6)	177.9 (1.8)	0.000
FFC outliers	0	0	0	0	1.000
Mean (SD)	89.9 (1.6)	90.1 (1.5)	89.9 (1.2)	87.9 (1.8)	0.000
FTC outliers	0	0	1 (7.14)	0	1.000
Mean (SD)	89.3 (1.4)	90.0 (1.2)	89.9 (1.6)	90.6 (1.3)	0.081
LFC outliers	2 (13.33)	2 (15.38)	1 (7.14)	4 (26.66)	0.663
Mean (SD)	85.7 (1.6)	85.4 (2.1)	87.4 (1.9)	85.8 (4.5)	0.307
LTC outliers	2 (13.33)	4 (30.76)	2 (14.28)	1 (6.66)	0.594
Mean (SD)	92.7 (2.4)	91.2 (3.0)	94.8 (1.2)	92.8 (2.7)	0.000

PSI: Patient-specific instrument; HKA: Hip-knee-ankle angle; FFC: Frontal femoral component; FTC: Frontal tibial component; LFC: Flexion/extension of the femur component; LTC: Lateral tibial component.

Table 6 Mean (SD) values and amount of patients and percentages of outliers of > 3˚ deviation of the planned alignment and postoperative alignment compared between the cut (n = 28, Trumatch and Visionaire) and pin (n = 29, patient-specific instrument and signature) patient specific matched guides group, n (%)

	Cut PSG	Pin PSG	P value
HKA outliers	4 (14.3)	3 (10.3)	1.000
Mean (SD)	179.9 (2.4)	179.3 (2.2)	0.342
FFC outliers	0	0	1.000
Mean (SD)	90.0 (1.5)	89.6 (1.8)	0.022
FTC outliers	0	1 (3.4)	1.000
Mean (SD)	89.6 (1.3)	90.2 (1.5)	0.115
LFC outliers	4 (14.3)	5 (17.2	1.000
Mean (SD)	85.6 (1.8)	86.6 (3.5)	0.184
LTC outliers	6 (21.4)	3 (10.3)	0.477
Mean (SD)	92.0 (2.7)	93.8 (2.3)	0.009

PSG: Patient specific matched guides; HKA: Hip-knee-ankle angle; FFC: Frontal femoral component; FTC: Frontal tibial component; LFC: Flexion/extension of the femur component; LTC: Lateral tibial component.

Table 7 Published level I studies with significant percentage of outliers of > 3˚ deviation between the patient specific matched guides and conventional intramedular and/or extramedular alignment method for hip-knee-ankle angle axis, frontal femoral component, frontal tibial component, flexion/extension of the femur component, lateral tibial component and axial rotation of the femur and/or tibia component controlled with postoperative X-ray (long-leg standing and/or lateral X-rays) and/or computed tomography

Outliers (%) > 3° deviation	PSG system	Modality	Conventional	Control	Sample size	Significant outliers (%)
			femur/tibia		(PSG/conventional)	(PSG/conventional)
Boonen et al[16]	Signature	MRI	Intra	X-ray	90/90	LFC (49/65)1
Chareancholvanich et al[17]	PSI	MRI	Intra/Extra	X-ray and CT	40/40	FFC (0/18)1
Chotanaphuti et al[18]	TruMatch	CT	Intra/Extra	X-ray and CT	40/40	NA
Hamilton et al[19]	TruMatch	Scout CT	Intra/Extra	X-ray	26/26	LTC (65/50)2
Ng et al[22] [Outliers (%) > 2° deviation]	PSI	MRI	Intra	CT	51/27	FTC (27/67)2, Femoral rotation (16/67)2, Tibial rotation (22/95)2
Pfitzner et al[24]	TruMatch	CT	Intra/Extra	X-ray and CT	(30/30)/30	HKA (30/7/43)2
	Visionaire	MRI + X-ray				FTC (13/3/23)1
						Femoral rotation (1/13 /50)1
Victor et al[25]	Signature	MRI, CT	Intra/Extra	X-ray and CT	(16/16/16/16)/64	FTC (15/3)1
	TruMatch	MRI + X-ray				LTC (21/3)2
	Visionaire	MRI				HKA (6/25/45/19)1, 3
	PSI					LFC (62/20/20/56)2, 3
Kotela et al[26]	Signature	CT	Intra/Extra	X-ray	49/46	FTC (39/20)1
Woolson et al[27]	TruMatch	CT	Intra/Extra	CT	22/26	LTC (32/8)1
Current study	Signature	MRI	Intra	X-ray	(15/13/14/15)/60	FFC (022)2
	TruMatch	CT				LFC (16/67)2
	Visionaire	MRI + X-ray				LTC (16/42)1
	PSI	MRI

¹Statistically significant different, P≤ 0.05;

²Statistically significant different, P≤ 0.005;

³Outliers > 3° deviation between the different PSG groups. NA: Not applicable for outliers; PSG: Patient specific matched guides; PSI: Patient-specific instrument; CT: Computed tomography; MRI: Magnetic resonance imaging; Intra: Intramedular; Extra: Extramedular; HKA: Hip-knee-ankle angle; FFC: Frontal femoral component; FTC: Frontal tibial component; LFC: Flexion/extension of the femur component; LTC: Lateral tibial component.