Proposal for a classification system of radiographic bone changes after cervical disc replacement

Table 1 Summary of agreement in radiographic assessments in proposed classification system

Variable	Agreement pairs	Total pairs	Overall agreement (%)	95% LB	95% UB	90% LB	90% UB
Superior vertebra bone loss—SA	219	375	58.4	51.5	82.7	53.5	80.0
Superior vertebra bone loss—SM	353	375	94.1	86.9	100.0	88.7	100.0
Superior vertebra bone loss—SP	297	375	79.2	70.4	95.5	72.4	92.9
Inferior vertebra bone loss—IA	229	375	61.1	52.5	86.1	54.9	83.1
Inferior vertebra bone loss—IM	355	375	94.7	86.9	100.0	88.4	100.0
Inferior vertebra bone loss—IP	350	375	93.3	85.1	100.0	86.7	100.0
Superior radiolucent line—SA	274	375	73.1	61.3	91.2	63.2	88.9
Superior radiolucent line—SM	302	375	80.5	69.9	95.2	71.7	93.9
Superior radiolucent line—SP	284	375	75.7	67.2	93.1	68.5	91.5
Inferior radiolucent line—IA	323	375	86.1	78.1	97.3	79.9	96.3
Inferior radiolucent line—IM	334	375	89.1	79.7	100.0	81.3	98.7
Inferior radiolucent line—IP	335	375	89.3	81.6	100.0	83.2	98.7
Progressive radiolucent line	311	375	82.9	74.4	96.5	75.9	95.3
Severity of bone loss	187	375	49.9	45.1	73.1	46.7	70.4
Progressive bone loss	245	370	66.2	59.7	87.7	62.0	83.7
Superior heterotopic bone formation—SA	317	375	84.5	75.7	96.5	77.9	94.8
Superior heterotopic bone formation—SP	282	375	75.2	66.9	91.5	69.5	90.1
Inferior heterotopic bone formation—IA	344	375	91.7	83.2	100.0	84.8	100.0
Inferior heterotopic bone formation—IP	335	375	89.3	81.3	98.7	82.9	98.7
Subsidence	291	355	82.0	73.1	94.9	75.1	93.7
Migration	325	360	90.3	83.2	100.0	85.1	97.9
Loss of core implant height	341	375	90.9	83.2	100.0	85.1	98.7
Olisthesis	270	375	72.0	64.8	91.7	65.9	89.7

ISSN: 1749-799X