General Information
This study was approved by the ethics committee of the PLA General Hospital. Twenty-six SAK patients (27 joints) treated in the Department of joint surgery of our hospital from March 2014 to April 2018 were retrospectively collected (Table 1). Three patients who did not complete the second-stage replacement were excluded. Of the remaining 23 patients (24 joints), 6 were males (7 joints) and 17 were females (17 joints). The average age was 61.6 years (45–75 years). Nine patients (9 joints) were treated with antibiotic-containing tibial plateau spacer (group A), and 14 patients (15 joints) were treated only with antibiotic cement beads (group B). In group A, 1 patient had a history of open knee surgery, 5 patients had a history of knee injection, 1 patient had a history of arthroscopy, 2 patients had unknown infection, and 8 patients had positive cultures (3 patients had fungal infection); In group B, 3 patients with a history of trauma, 5 patients had a history of knee injection, 3 patients had a history of arthroscopy, 3 patients had unknown infection causes, and 6 patients had positive cultures (1 patient had fungal infection, and 1 patient had mixed infection). All the patients were followed up for an average of 27 months.
Table 1
Basic information of the patients before surgery
Grouping (No) | Gender/age(years) | Affected side | Preoperative HSS | Preoperative ROM | Reason of knee infection | Results of culture |
A1 | F/70 | L | 32 | 40 | history of knee injection | Candida albicans |
A2 | F/60 | L | 48 | 100 | history of knee injection | Candida fris |
A3 | F /69 | L | 35 | 40 | history of knee injection | Candida parapsilosis |
A4 | F/65 | L | 41 | 20 | unknown | |
A5 | M/70 | L | 35 | 95 | History of arthroscopy | Micrococcus luteus |
A6 | F/68 | R | 61 | 85 | unknown | Propionibacterium acnes |
A7 | M/58 | L | 36 | 61 | history of knee injection | Nocardia, Gram-positive bacilli |
A8 | M/75 | R | 30 | 85 | history of knee injection | Staphylococcus warneri |
A9 | M/45 | L | 14 | 70 | History of knee incision for nail removal | Staphylococcus surface |
Average of group A | 4 M/5 F 64.4 | 7L/2R | 36.9 | 66.2 | | |
B1 | F/63 | R | 46 | 110 | history of knee injection | |
B2 | F/66 | R | 28 | 50 | unknown | |
B3 | F/58 | L | 8 | 40 | unknown | Staphylococcus aureus |
B4 | F/49 | R | 46 | 90 | History of arthroscopy | |
B5 (two sides) | M/62 | R | 27 | 20 | History of trauma | Gram-positive bacilli |
| | L | 23 | 45 | | |
B6 | F/71 | L | 23 | 10 | unknown | Staphylococcus aureus |
B7 | F/71 | L | 32 | 40 | history of knee injection | Staphylococcus aureus |
B8 | F/58 | R | 30 | 30 | History of arthroscopy | Aspergillus flavus |
B9 | M/55 | R | 45 | 60 | history of knee injection | |
B10 | F/57 | R | 20 | 20 | history of knee injection | Staphylococcus surface and Staphylococcus hominis |
B11 | F/66 | R | 40 | 40 | history of knee injection | |
B12 | F/48 | L | 35 | 60 | history of knee injection | |
B13 | F/57 | R | 19 | 60 | history of knee injection | |
B14 | F/55 | R | 35 | 40 | history of knee injection | |
Average of group B | 2M/12F 59.7 | 5L/10R | 30.4 | 47.7 | | |
Sum | 6M/17F 61.6 | 12L/12R | 32.9 | 54.6 | | |
Diagnostic criteria of SAK [15]
The diagnosis was combined with individual medical history, together with the symptoms and signs of clinical infection (painful effusion, restricted mobility, elevated skin temperature, or the presence of the same sinus as the joint); elevated serum inflammation markers (C-reactive protein [CRP > 10 mg / dL], erythrocyte sedimentation rate [ESR] > 30 mm / h), polymorphonuclear (PMN) cell count percentage > 90%); imaging-revealed narrowing of joint space and destruction of articular cartilage; surgery-revealed purulent slip in joint cavity, synovial membrane, or tissue; frozen sections (> 5 neutrophils / HPF) of suspicious infection during surgery, positive results of synovial fluid or tissue culture.
Inclusion criteria
1) the patient should be confirmed SAK; 2) Anti-infection or other surgical methods were not effective; 3) the patient had obvious knee joint pain and limited joint movement. X-ray of knee joint before surgery indicated degenerative changes of knee joint; 4) the patient had preoperative evaluation of being able to tolerate surgery and had no mental illness. 5) the patient fully understood the meaning and risks of secondary surgery and signed relevant medical documents.
Exclusion criteria
1) the patient had still good knee function and the symptoms were mild; 2) the patient had complicated infection of other parts (lung, urinary system, femur, tibia, etc.); 3) the patient can’t complete secondary replacement.
Treatment
Stage I surgery: The median incision and lateral medial approach of the patella used in conventional TKA were performed. During the operation, 3 to 5 suspicious infected tissues in different parts were sampled for rapid intraoperative frozen slice examination, the results of which in all patients indicated that the knee joint was infected. Thorough debridement and repeated flushing with hydrogen peroxide, iodine, and saline was then performed within the reach of surgical field. For the patients in group A (antibiotic methyl-methacrylate cement polymer, Heraeus Medical GmbH, Wehrheim / Ts., Germany), the tibial plateau was performed 9-mm osteotomy to fully expose and clean the joint capsule. A temporary prepared tibial plateau was fixed on the tibial plateau (Fig. 1A); and the antibiotic cement beads were placed on the front and sides of the knee capsule (Fig. 1B). The strategy for antibiotic use was the same in the two groups. For the patients with unidentified pathogen, 4 g of vancomycin powder (VIANEX SA, Athens, Greece) + 2 g of meropenem (Sumitomo Dainippon Pharma Co. Ltd., Osaka, Japan) were placed in 40 g of bone cement; For the patients with known culture results before surgery, appropriate doses of antibiotics or antifungal drugs according to the results of drug sensitivity test were added. Negative pressure drainage tube was applied after the surgery was completed.
After surgery, the affected knee joint was kept straight, and the drainage tube was withdrawn when the drainage was less than 50 ml / day and clear. After drainage tube withdrawal, partial weight-bearing activities were allowed under the protection of knee braces. After surgery, 6-week routine intravenous broad-spectrum antibiotics (when the culture result was negative) or corresponding sensitive antibiotics was administrated; then, oral antibiotics was administrated for at least 6 weeks or until the clinical symptoms and signs disappearred and ESR/CRP returned to normal (Fig. 2). Once the clinical indexes were normal for two times, the spacer can be removed for knee joint replacement.
Stage 2 surgery: The same original knee incision and original approach were used in the Stage 2 knee replacement surgery. After exposing the joints, 3 to 5 soft tissues of different parts were sampled for rapid intraoperative frozen slice examination. The results showed that the joint replacement can be performed as planned when the infection was ruled out. After removing the spacer, the joint cavity was fully washed and cleaned, and the surgery was then completed according to the method of initial knee joint replacement. Because tibial plateau osteotomy had been completed in the patients with tibial plateau placer having been placed in Stage 1 surgery, this step can be omitted in Stage 2. Postoperative treatment and functional exercise were performed in accordance to conventional TKA.
If the patient's interval clinical evidence or Stage 2 intraoperative freezing slice test indicated persistent knee infection, the same bone cement spacer as before should be replaced again in combination with systemic antibiotic for continuous anti-infective treatment. One patient in each group received such spacer replacement.
Data collection
1) the patients’ hospital medical history, relevant medical history, and relevant test results, as well as previous invasive knee operations, time, effects, and outcome, were reviewed; 2) the patients’ mobility and knee function scores (HSS scoring system) before and after surgery in hospital were recorded; 3) the patients were followed up after joint replacement, reviewed the X-ray images of the knee joint, blood routine, ESR, CRP, joint mobility, and HSS score.
Statistical analysis
To evaluate the efficacy of staged surgery in each group, univariate analysis (ANOVA) was used to compare the differences in ROM and functional score (HSS) before surgery, during the interval period, and after replacement. The SNK-t test was then used to compare the functional and activity differences in each group between any two periods. In order to compare the differences in the efficacy between the two groups, the independent-sample t test was used to compare the function and ROM at the same period. All data results were analyzed using SPSS 20.0 with P < 0.05 being considered as statistical significance.