Uncemented monoblock trabecular metal posterior stabilized high-flex total knee arthroplasty: similar pattern of migration to the cruciate-retaining design — a prospective radiostereometric analysis (RSA) and clinical evaluation of 40 patients (49 knees) 60 years or younger with 9 years’ follow-up

Figures & data

Figure 1. Flowchart of the patients. TKA = total knee arthroplasty, RSA = radiostereometric analysis.

Table 1. Preoperative clinical data

Factor	Mean	Median	Range
Age (years)	55	56	40–60
Weight (kg)	88	85	57–120
Length (cm)	171	169	153–198
BMI	30	30	21–43
Extension lag (°)	13	15	0–30
Flexion (°)	117	125	80–135
Range of motion (°)	104	110	60–135
Knee Society (KS) score ^a	17	14	0–48
KS function score ^a	48	50	25–55
Knee alignment (°) ^b	176	174	163–196

^aKnee Society knee and Function score (max. 100).

^bHip Knee Ankle angle (varus < 180°, valgus > 180°).

Figure 2. Maximum migration (MTPM) for the NexGen Trabecular Metal posterior stabilized (PS) monoblock tibial component (red). For comparison values for the cruciate retaining (CR) variety of the same implant (blue) (Henricson and Nilsson 2016). Values are mean (95% confidence interval).

Figure 3. Maximum subsidence (negative y-axis translation) for the NexGen Trabecular Metal posterior stabilized (PS) monoblock tibial component (red). For legend, see Figure 2.

Figure 4. Rotation around the transverse (x-) axis of the knee (absolute values). For legend, see Figure 2. The majority of the TM PS implants rotated into posterior tilt.

Figure 5. Rotation around the longitudinal (y-) axis of the knee (absolute values). For legend, see Figure 2. The majority of the TM PS implants rotated externally.

Figure 6. Rotation around the sagittal (z-) axis of the knee (absolute values). For legend, see Figure 2. Rotation into varus or valgus was evenly distributed among the TM PS implants.

Figure 7. Individual MTPM values for the TM PS implants.

Table 2. Clinical and radiological data at the 9-year follow-up

Factor	Mean	SD	Median	Range
Knee Osteoarthritis Outcome Score (KOOS) ^a
Symptoms	85	13	86	64–100
Pain	87	15	92	42–100
Function, daily living	86	16	91	35–100
Function, sports and recreational activities	53	31	50	5–100
Quality of life	72	25	81	31–100
Forgotten Joint Score (FJS) ^a	65	26	73	23–100
Knee Society Knee Score ^a	97	3.9	100	80–100
Knee Society Pain Score ^b	50	1.3	50	40–50
Knee Society Function Score ^a	98	9.2	100	60–100
Extension lag (°)	2	2.2	0	0–15
Flexion (°)	131	10	130	120–145
Knee alignment postop (°) ^c	179	3.0	179	172–185
Tibial component
alignment frontal plane (°) ^d	89	2.0	89	83–93
posterior slope (°)	6	2.3	6	2–10

^a Maximum 100.

^b 50 = no pain

^c Hip–knee–ankle angle, < 180° = varus, > 180° = valgus alignment.

^d < 90° = varus, > 90° = valgus alignment.

Henricson A, Nilsson K G. Trabecular metal tibial knee component still stable at 10 years: an RSA study on 33 patients less than 60 years of age. Acta Orthop 2016; 87: 504–10.

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