Mid-term outcomes of a kinematically designed cruciate retaining total knee arthroplasty

Table 1 Patient demographics

	Knees (n = 255)
Sex, n (%)
Male	88 (34.5)
Female	167 (65.5)
Age (yr) [range]	60.6 [32-83]
Race, n (%)
White	112 (43.9)
African American	63 (24.7)
Asian	10 (3.9)
Other	70 (27.5)
Smoking status, n (%)
Current	14 (5.5)
Former	92 (36.1)
Never	149 (58.4)
Insurance status, n (%)
Medicare	79 (31.0)
Medicaid	32 (12.5)
Commercial	144 (56.5)
ASA score, n (%)
1	4 (1.6)
2	148 (58.0)
3	102 (40.0)
4	1 (0.4)
BMI (kg/m2) [range]	33.5 [16.8-57.8]
CCI	3.0 ± 2.2
Primary diagnosis, n (%)
Primary OA	247 (96.9)
Post-Traumatic OA	7 (2.7)
AVN	1 (0.4)

ASA: American Society of Anesthesiologists; BMI: Body mass index; CCI: Charlson Comorbidity Index; OA: Osteoarthritis; AVN: Avascular necrosis.

Table 2 Intraoperative and implant variables

	Knees (n = 255)
Operative time (min) [range]	105.3 [65-237]
Liner, n (%)
Standard	213 (83.5)
Deep dish	42 (16.5)
Anesthesia, n (%)
General	21 (8.2)
Spinal/Regional/Block	234 (91.8)
Bearing surface, n (%)
Oxidized Zirconium-on-Polyethylene	57 (22.4)
Cobalt Chrome-on-Polyethylene	198 (77.6)
Technology, n (%)
Manual	158 (62.0)
Computer navigation	88 (34.5)
Robotic assistance	9 (3.5)

Table 3 Short-term clinical outcomes

	Knees (n = 255)
LOS (days) [range]	2.1 [0.3-19.5]
Time to follow-up (years) [range]	3.3 [2.1-6.6]
Discharge disposition, n (%)
Home	236 (92.5)
SNF	16 (6.3)
ARF	3 (1.2)
90-d ED visits, n (%)	18 (7.1)
Non-orthopedic related	6 (2.4)
Orthopedic related	12 (4.7)
Knee pain and swelling	6
Knee pain and erythema	1
Calf pain and lightheadedness	1
Groin pain	1
VTE	1
NSAID poisoning	1
Opioid poisoning	1
90-d readmissions, n (%)	3 (1.2)
PJI	1
AKI	1
Gastric bleed due to NSAID poisoning	1

LOS: Length of stay; SNF: Skilled nursing facility; ARF: Acute rehabilitation facility; ED: Emergency department; AKI: Acute kidney injury; NSAID: Non-steroidal anti-inflammatory drug; VTE: Venous thromboembolism; PJI: Peri-prosthetic joint infection.

Table 4 Long-term clinical outcomes

	Knees (n = 255)	Mean time to revision (years) [range]
Revisions, n (%)	4 (1.6)	1.1 [0.7-1.5]
Arthrofibrosis	2	1.3 [1.1-1.5]
Aseptic femoral loosening	1	1.1
PJI	1	0.7

PJI: Peri-prosthetic joint infection.

Table 5 Subanalysis: Survivorship by bearing surface material

	Cobalt chrome (n = 198)	Oxidized zirconium (n = 57)
Revisions, n (%)	4 (2.0)	0 (0)
Arthrofibrosis	2	0
Aseptic femoral loosening	1	0
PJI	1	0

PJI: Peri-prosthetic joint infection.

Table 6 Subanalysis: Survivorship by liner type

	Standard (n = 213)	Deep dish (n = 42)
Revisions, n (%)	3 (1.4)	1 (2.4)
Arthrofibrosis	1	1
Aseptic femoral loosening	1	0
PJI	1	0

PJI: Peri-prosthetic joint infection.

Table 7 Patient reported outcome measures (mean ± SD)

	Knees (n = 255)	P value
KOOS JR
Preoperative	43.3 (13.0)
6 mo	56.5 (16.1)
2 yr	62.2 (13.9)
Δ Preop to 6 mo	13.2 (16.4)	< 0.0001
Δ Preop to 2 yr	18.9 (16.9)	< 0.0001
PROMIS pain intensity
Preoperative	55.6 (6.9)
6 mo	50.1 (8.1)
2 yr	48.6 (7.6)
Δ Preop to 6 mo	-5.5 (8.2)	< 0.0001
Δ Preop to 2 yr	-7.0 (6.7)	< 0.0001
PROMIS pain interference
Preoperative	65.3 (5.7)
6 mo	61.4 (8.0)
2 yr	59.5 (8.0)
Δ Preop to 6 mo	-3.9 (7.5)	< 0.0001
Δ Preop to 2 yr	-5.8 (6.3)	< 0.0001
PROMIS mobility
Preoperative	35.5 (4.1)
6 mo	38.1 (4.3)
2 yr	40.3 (5.6)
Δ Preop to 6 mo	2.6 (4.8)	< 0.0001
Δ Preop to 2 yr	4.8 (3.5)	< 0.0001
PROMIS physical health
Preoperative	39.5 (7.3)
6 mo	41.8 (6.9)
2 yr	42.0 (6.1)
Δ Preop to 6 mo	2.3 (6.6)	0.029
Δ Preop to 2 yr	2.5 (5.4)	0.045

KOOS JR: Knee Injury and Osteoarthritis Outcome Score for Joint Replacement; PROMIS: Patient-Reported Outcomes Measurement Information System.