- Demographic characteristics
In the destination joint spacer group, 10 patients could not tolerate prosthesis reimplantation because of complicated underlying diseases, 8 patients refused reimplantation due to being satisfied with function, and 3 patients were unable to undergo reimplantation due to economic and other factors. These patients were treated with antibiotics for 76 (48-96) days after joint spacer implantation. The mean age was 67.52 ±11.61 (45-88) years, and there were 9 males, 12 females, 14 hips (3 cases of type I and 11 cases of type II) and 7 knee joints (5 cases of type I and 2 cases of type II). The mean preoperative CRP level was 38.75 ±40.11 mg/L, the ESR was 64.19 ±33.18 mm/h, the SF-WBC count was 36783.24 ±6737.19 L, the PMN% was 84.16 ±8.32%, and the CCI was 4.67 ±1.88%. There were 41 patients in the temporary spacer group, with a mean age of 63.9 ±8.87 years. There were 17 males and 24 females, with 24 hips (11 cases of type I and 13 cases of type II) and 17 knee joints (9 cases of type I and 8 cases of type II). The mean preoperative CRP level was 35.42 ±30.74 mg/L, the ESR was 76.49 ±42.50 mm/h, the SF-WBC count was 23759.12 ±7038.58 ml, and the PMN% was 81.96 ±8.16. The mean CCI was 2.15 ±0.88. The CCI of the destination joint spacer group was higher than that of the temporary joint spacer group, and there were no significant differences in other demographic characteristics between the two groups.
- Comparison of the infection-relief rate and efficacy
The eradication of infection was defined according to Delphi-based international multidisciplinary consensus16. The comparisons of infection-relief rates were shown in Table 2.
In the destination joint spacer group, there were 3 cases of recurrent infection (14.29%). In 2 of these cases, the joint spacers were removed, and antibiotic-impregnated joint spacers were reimplanted after debridement; in another case, the joint spacer was removed with left exclusion after debridement. In the two-stage revision group, there were 4 cases of recurrent infection (9.76%). Among the cases of recurrent infection, 2 patients underwent DAIR, and 2 patients underwent one-stage revision. There was no significant difference in the infection-relief rate between the two groups.
This might be attributed to sufficient course of systemic antibiotics administration, and high local antibiotics concentration, which play an important role in PJI infection control. And the infection-relief rate might not be related to the material retained in the joint.
There were no significant differences in preoperative visual analog scale (VSA) score, Harris hip score (HHS), knee society score (KSS) or postoperative VSA between the two groups, but the postoperative HSS and KSS in the two-stage revision group (76.88 ±10.70 and 73.35 ±8.57, respectively) were higher than those in the destination joint spacer group (50.64 ±5.47 and 47.14 ±10.07, respectively). One patient suffered from non-PJI-related death (death of severe liver cirrhosis) in the destination group, and 1 patient died after two-stage revision; the cause of death was unknown.
- Comparison of complications
The comparison of complications between the two groups is listed in Table 3.
In the destination joint spacer group, two patients suffered from spacer fractures 3 and 5 years after spacer implantation (both were knees with type I spacers), respectively. Infection relief was confirmed after combining the clinical symptoms and signs with the laboratory test results, so the prostheses were reimplanted after debridement. There were 3 cases of dislocation (hip: 2 cases, both with type I spacers; knee: 1 case, type I spacer): 2 cases were successfully reduced, and 1 patient underwent surgery. There was 1 case of a periarticular fracture (hip, type I) and 3 cases of deep venous thrombosis, and these patients received oral anticoagulant therapy after joint spacer implantation. The complications odds ratio (OR) of type I to typeⅡwas 10 [(6/2)/(3/10)].
Among the patients who underwent implantation of temporary joint spacers and prosthesis reimplantation, 1 patient suffered from a periprosthetic hip joint fracture after an accidental fall, so he received surgical treatment; 1 patient suffered from hip dislocation after reimplantation and was successfully reduced; and 1 patient suffered from deep venous thrombosis of the lower extremity. The total incidence of complications in the destination group was higher than that in the two-stage revision group. Further analysis showed that in the destination joint spacer group, for hips (14 cases), there were 3 cases with type I spacers and 2 cases with dislocations (66.67%), and there were 11 cases with type II spacers (78.57%); however, there have been no complications so far, and there was a significant difference in the incidence of complications between the two types of hip spacers (P= 0.033). For knees (7 cases), there were 5 cases with type I spacers and 2 cases of spacer fractures with 1 case of dislocation, and the complication rate was 60%. While there were no complications in cases with type II spacers, there was no difference in the incidence of complications between the two types of knee spacers (P=0.429).