Page 173 - Reconstructive Techniques in Musculoskeletal Tumor Surgery

expressed in odds ratios (OR), 95% con dence intervals (95% CI) and p-values. SPSS 21.0 (IBM Corp, Armonk, NY, USA) was used for statistical analysis, with the level of signi cance at p < 0.05.
Results
There were a total of 15 non-uniting osteotomies (15/96, 16%). Revision operations for nonunion were performed after a median of 17.5 months (range, 4 months to 9 years) after the index procedure. Twenty-three osteotomies (24%) were classi ed as grade 1, 29 (30%) as grade 2A, 28 (29%) as grade 2B and 16 (17%) as grade 3, respectfully. The kappa value between the two observers was 0.734 (substantial20). The classi cation of the two observers was identical for 79 osteotomies (82%); further discussion to achieve consensus was needed for 17 osteotomies (18%). Nonunion was the cause for revision surgery in none of the 23 osteotomies that were classi ed as grade 1, in two of 29 (7%) that were classi ed as grade 2A, in ve of 28 (18%) that were classi ed as grade 2B, and in 8 of 16 (50%) osteotomies that were classi ed as grade 3 (Table 2).
Table 2. Table showing the number of osteotomies included in each category, the number of osteotomies
that were revised for nonunion, and the corresponding odds ratios, 95% con dence intervals and p-values.
Because there were zero events in the grade 1 osteotomies, we chose to use grade 3 osteotomies as the 8 reference category. For the same reason, the odds ratio, 95% con dence interval and p-value could not be
calculated for grade 1 osteotomies
Classi cation, Total number of Number revised % Non- 95% con dence P-value category osteotomies for nonunion Union interval
Lower Upper
Grade 1 23 0 0% - - -
Allograft nonunion
Grade 2A Grade 2B Grade 3
29 2 28 5 16 8
7% 0.01 0.42 0.003 18% 0.05 0.86 0.03 50% Ref. Ref. -
Twelve of 61 femoral osteotomies (20%) and three of 35 tibial osteotomies (9%) did not initially heal (p=0.149). The risk of nonunion was not signi cantly associated with patient age, although the risk was slightly lower in patients of 16 years or younger (7/52, 13%) than in patients aged over 16 years (13/60, 22%) (p = 0.258). Also, epimetaphyseal junctions appeared to have a slightly lower risk of nonunion (5/40, 13%) than diaphyseal osteotomies (15/72, 21%) (p = 0.270).
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