The treatment principle of knee SA to date includes surgical treatment and appropriate antibiotics19. However, the effect of the above treatments on advanced infectious arthritis is very poor, yet there is no established guidelines for such conditions, especially in the demanding adults. Though limited therapeutic options, there were several researches put effects on applying two-stage approach to primary TKA and tried to improve the efficiency2,3,11,20. In our study, demands in eliminating infection, relieving symptoms and returning function were fulfilled, Also, we reported similar experience and endings as previous studies, though with small sample size. Therefore, two-stage TKA could be treated as a potential option in sever knee SA management.
Patients enrolled to this study were all diagnosed of knee SA, which fulfilled the criteria of badly damaged knee joint, exfoliated cartilage and failure in controlling infection by arthroscopy and open debridement. We referred the operation mode from B Hochreiter et al.11. Regarding the femoral cutting, we applied the simple extramedullary guiding method in first stage, which achieved the therapeutic outcomes of decreasing risk of surgery-related infection spreading and better function recovery. Previous study reported21 that valgus angles in 30–51% of patients who received TKA were ranged beyond the Valgus Cut Angle (i.e., 5 to 7 degrees), which unfitted to intramedullary guide tools, and such unfittness resulted the malalignment of knee after TKA. Thus, in the first-stage, we applied the simple extramedullary guiding method in cutting distal femur to all eleven patients, which was equivalent to individualized valgus, and the alignment of all eleven patients were approprate. In addition, extramedullary guiding method could reduce the spread of infection and decrease the risk of bleeding and fat embolism. Further more, this extramedullary guiding method does not need C-arm fluoroscopy for femoral head during operation which could reduce radiation injury of patient.
CRP of all eleven patients were returned to normal level within six weeks after the first stage, though ESR decreasing slower. Previous studies suggested that spacer surface biofilm formation due to long interval period would casue infection recurrence. Our patients were suggested to receive the second-stage surgery within three months, whereas fulfill the criteria that ≥ 2 times CRP test results in normal range, ESR halfly decreased and no infected symptoms such as joint redness, fever, wound drainage and unreasonable knee pain.
Infection were eliminated in all eleven patients, and their knee joint function also returned to the level for supporting daily activities. However, patient 3 and 6 did not fully follow our advice on functional exercise after the first stage, which resulted rigid knee joint surrounded by scar tissues. Thus, we had to perform the tibial tubercle osteotomy to expose the joint clearly and help to finish the operation in the second-stage surgery. Nevertheless, they had smaller ROM than other patients after surgery. We emphasized and strengthened functional exercise to them, including knee flexion and extension, lower limb muscle strength exercise and partial-weight bearing exercise, which accelerated their recovery in post-operation. In corresponding to our results, the knee joint function (i.e., HSS score) would significantly increase after both two stages. Therefore the function exercise should be insisted across the whole process especially within one month after each operation, which do affects the effect of this surgery.
Previous studies on age and gender mainly focused on patients with osteoarthritis undergoing primary TKA, which reported that patients received primary TKA of female were averagely postponeed three years later than male and had lower Knee Function scores than men preoperatively and postoperatively22. Such fingings demonstrated that earlier initiation of treatment may enhance postoperative outcomes in women. Another study23 revealed that female gender, younger age and worse preoperative pain predict greater risk of moderate-severe pain postoperatively in patients with primary and revision TKA. However, the information on such factors influcing the functional outcomes of two-stage TKA of knee SA is indeed scant. We did the comparisons on age, gender, micro-organism culture result and comorbidities but failed to identify difference. Otherwise, previous studies had only focused on elderly patients and we performed two-stage TKA in two young patient (i.e., 22,31 years old) whose knee joint were with serious damaging, cartilage denudation and flexion deformity. Arthroscopic and open debridement failed to control his advanced infection. Eventually we had to perform two-stage TKA to save him from joint arthrodesis. However, further studies of randomized controlled trial and appreciate sample size are expected.
However, just like many previous studies2,11,20,24, our study has some limitations. First of all, our study was a retrospective study with a limited number of patients, the reason is that advanced knee arthritis combined with severe knee joint disability is not common but is difficult to treat. Second, we had no control group.Though small sample size, our study provided valuable information to this rare clinical challenge. We could conclude that the two-stage TKA with antibiotic-laden cement spacer should be considered as a potential option in the treatment of non-salvageable knee SA, as well as the application of extramedullary guiding method.
Conclusion: Two-stage TKA with extramedullary guiding method is an effective treatment in SA in knee joint in controlling infection, relieving clinical severity and improving function of keen joint thereafter.