Joint unloading implant modifies subchondral bone trabecular structure in medial knee osteoarthritis: 2-year outcomes of a pilot study using fractal signature analysis

Figures & data

Figure 1 KineSpring^® Knee Implant System.

Figure 2 Semiautomated regions of interest by KneeAnalyzer.

Notes: Joint space boundary profiles for femur (blue); Joint space boundary profiles for tibial plateau at both the lateral compartment (red) and the medial (green) compartments; Regions for fractal signature analysis in the medial and lateral subchondral bone (light green boxes); Minimum joint width at the lateral compartment and the medial compartments (black).

Figure 3 Representative fractal signature curves, demonstrating fractal dimensions at the tibial cortex over a range of trabecular widths from 0.4 to 3.0 mm.

Notes: Fractal signature curves are fitted using a quadratic regression model, representing (from top to bottom) horizontal trabeculae in the medial compartment, vertical trabeculae in the medial compartment, horizontal trabeculae in the lateral compartment, and vertical trabeculae in the lateral compartment.
Abbreviation: FSA, fractal signature analysis.

Table 1 Baseline patient characteristics

Pt #	Age, yr	Sex	BMI, kg/m^2	K-L grade	WOMAC pain	WOMAC function	WOMAC stiffness	ROM, °
1	46	Female	30	2	65	72	63	135
2	53	Female	30	2	65	60	75	135
3	55	Male	33	3	40	34	50	120
4	49	Female	39	2	50	37	75	110
5	63	Male	31	3	65	71	63	115
6	56	Male	30	4	75	72	75	117
7	50	Male	25	3	20	15	25	115
8	44	Female	24	4	60	43	25	135
9	59	Male	32	3	45	41	25	140

Note:

° Represents degrees.

Abbreviations: BMI, body mass index; K-L, Kellgren–Lawrence; Pt #, patient number; ROM, range of motion; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index; yr, years.

Figure 4 Change in WOMAC subscores over 2 years following joint unloading implant.

Note: Values are median (interquartile range).
Abbreviations: WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index; yr, years.

Figure 5 Change in joint space width over 2 years following joint unloading implant.

Note: Values are median (interquartile range).
Abbreviation: yr, years.

Figure 6 Change in subchondral tibial fractal signatures for (A) vertical and (B) horizontal oriented trabeculae over 2 years following joint unloading implant.

Note: Values are median (interquartile range).