Porous tantalum rod implantation is associated with low survival rates in patients with type C2 osteonecrosis of the femoral head but has no effect on the clinical outcome of conversion total hip arthroplasty: a retrospective study with an average 8-year follow-up

Table 3 HHS before surgery and follow-up

Time points	Groups (HHS Median [percentile25-percentile75])				Overall
Time points	Stage II	Stage III	Type C1	Type C2	Overall
Pre-op	59 (56–61)	53 (46–56)	57 (52–61)	61 (55–63)	59 (55–61)
24 ms	86 (83–90) ^**	79 (68–84) ^{**, ¶¶}	86 (82–90) ^**	68 (61–83) ^¶¶	85 (79–90) ^**
60 ms	89 (88–91) ^**	90 (78–91) ^**	90 (87–91) ^**	82 (65–88) ^¶	89 (86–91) ^**
96 ms	94 (90–96) ^**	92 (90–95) ^**	94 (91–96) ^**	89 (70–94) ^*	94 (91–96) ^**

^**: Significant difference compared to pre-op HHS score in each group (P < 0.01); *: Significant difference compared to pre-op HHS score in each group (P < 0.05)
^¶: Significant difference compared to stage II / Type C1 at the same time point (P < 0.05)
^¶¶: Significant difference compared to stage II / Type C1 at the same time point (P < 0.01)

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