2.1. Materials
This is a retrospective study in which we reviewed and analyzed data from 11 patients with knee joint bone infections who were treated at our hospital’s Bone Infection Reconstruction Center from July 2014 to July 2022. The cohort comprised 8 females and 3 males with an average age of 74.27 years, with the youngest being 70. Among them, 4 experienced reinfection after knee joint revision replacement and 7 had knee joint bone infection (Table 1). All patients underwent a two-stage treatment approach involving an initial surgery to control the infection, followed by the use of antibiotic bone cement combined with tibial intramedullary nail as the ultimate treatment technique.The surgical methodology was rigorously evaluated and received approval from the Institutional Review Board (IRB) of our hospital’s Medical Ethics Committee, adhering to the highest standards of ethical practice and patient consent. All methods were carried out in accordance with relevant guidelines and regulations(IRB No: 20140714-10)
Table 1
Details of patients who underwent antibiotic-loaded bone cement combined with tibial intramedullary nail as the ultimate treatment for elderly knee joint bone infection
Case | Gender | Age(y) | Main diagnosis | Site | Side | Stiffness(Y/N) | Length of bone loss(cm) | Shortened length of limb(cm) | Times of surgery | Ultimate operation duration (minuter) | Follow-up period(month) |
1 | F | 73 | Chronic osteomyelitis | distal femur | left | Y | 13 | 0.7 | - | 187 | 60 |
2 | F | 71 | Chronic osteomyelitis | distal femur | right | Y | 14 | 0.5 | - | 176 | 54 |
3 | F | 76 | Reinfection after revision replacement | knee joint | Left | - | 12 | 1.0 | 4 | 201 | 47 |
4 | M | 78 | Reinfection after revision replacement | knee joint | Left | - | 13 | 0.5 | 3 | 173 | 38 |
5 | F | 70 | Chronic osteomyelitis | proximal tibia | right | Y | 10 | 0.7 | - | 167 | 36 |
6 | F | 72 | Chronic osteomyelitis | distal femur | left | Y | 12 | 0.3 | - | 190 | 28 |
7 | M | 73 | Reinfection after revision replacement | knee joint | right | - | 11 | 0.6 | 4 | 189 | 37 |
8 | F | 81 | Chronic osteomyelitis | distal femur and proximal tibia | left | - | 11 | 0.8 | - | 178 | 35 |
9 | F | 73 | Chronic osteomyelitis | distal femur and proximal tibia | right | - | 11 | 0.9 | - | 185 | 24 |
10 | F | 78 | Chronic osteomyelitis | distal femur | left | - | 13 | 0.8 | - | 165 | 26 |
11 | M | 72 | Reinfection after revision replacement | knee joint | right | - | 13 | 0.5 | 5 | 172 | 29 |
±S | - | 74.27 ± 3.47 | - | - | | - | 12.09 ± 0.37 | 0.66 ± 0.21 | - | 180.27 ± 11.06 | 37.64 ± 3.51 |
2.2. Operative technique (Fig. 1)
Stage 1 - Infection Control: The procedure begins by exposing the infected region surrounding the knee joint. Any present internal fixation or prosthetic material in the affected area is removed. The surgical team meticulously debrides the site, removing all inflammatory granulation and necrotic tissue. During this process, tissue samples are collected for subsequent pathological and microbiological analysis. Debridement continues until healthy bleeding bone, often referred to as the ‘paprika sign’ is evident, indicating the limit of infection clearance. For extensive segments of infected bone, en-bloc resection may be necessary, and patellectomy is performed if deemed essential. The area is then lavaged sequentially with hydrogen peroxide, saline, povidone-iodine solution, and again with saline to reduce the bioburden to a minimal level. The resultant cavity is filled with an antibiotic-loaded bone cement (PALACOS®R + G*,Heraeus Group,Germany), using a mix ratio of vancomycin to cement of 5:1. To maintain structural stability, external fixation is applied, utilizing either dedicated external fixation devices or an external fixator to secure the bone ends.
Stage 2 - Definitive Treatment: Approximately 6 to 8 weeks following the initial surgery, contingent upon the patient’s clinical presentation, imaging results, and laboratory findings indicating infection control, the second-stage surgery is commenced. This phase involves the use of antibiotic-loaded bone cement combined with tibial intramedullary nail as a definitive therapeutic measure.
Begin the removal process by carefully disassembling the external fixation device or fixator. Reopen the initial surgical incision to access the defect area. Employ an osteotome with precision to chisel away the bone cement that fills the defect. After the cement has been removed, meticulously prepare the terminal bone surfaces to promote an optimal interface and adhesion for the subsequent application of new bone cement. Thoroughly irrigate the site with a sequence of hydrogen peroxide, saline solution, povidone-iodine solution, and another round of saline to cleanse the area.
Careful selection of the tibial intramedullary nail from Double Medical Technology Co., Ltd., China, is imperative, ensuring that its length and diameter are tailored to the patient’s specific tibial anatomy. During the procedure, the chosen intramedullary nail is inserted along the tibial medullary canal. It is positioned so that its proximal end can be retracted into the femoral medullary canal for optimal alignment. Once the nail is withdrawn into the correct position, with its end secured within the femoral canal, it’s locked in place to ensure stability between the femur and tibia. Throughout the procedure, attention is given to preserving the alignment of the femur and tibia, as well as ensuring limb length equality. Using fluoroscopic guidance, locking screws are carefully driven and tightened at both the proximal and distal ends of the nail to achieve a robust stabilization of the joint.
Commence by thoroughly mixing one sachet of bone cement with the monomer until a homogenous consistency is obtained. Proceed to meticulously pack this mixture into the medullary cavities at both the femoral and tibial ends. This serves to securely anchor the intramedullary nail in place at each extremity. Subsequently, measure the defect and prepare an adequate quantity of the bone cement mixture to fill the void completely. Once the bone cement has been confirmed to have set firmly, place a drainage tube to prevent fluid accumulation. Finally, suture the wound with precision to promote optimal healing.
Three days postoperatively, the patient was able to bear weight with the assistance of crutches.
2.3. Outcome measures
Preoperative, intraoperative, and postoperative documentation must include specific metrics to assess the surgical outcome and patient recovery:
Preoperative Documentation:
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Record the Western Ontario and McMaster Universities Osteoarthritis Index (WOWAC) score[23] of the knee joint to assess the baseline functional status.
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Document the number of prior surgical procedures performed on the affected limb.
Intraoperative Documentation:
Postoperative Documentation:
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Document the WOWAC score of the affected limb at the final follow-up to evaluate the outcome.
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Measure and record any discrepancy in the length between both lower limbs.
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Catalog any surgery-related complications, such as recurrent infections or peri-implant fractures.