Periprosthetic gout flare after total knee arthroplasty: A misdiagnostic case report / 北京大学学报(医学版)

Periprosthetic gout flare is a rare arthritic condition after total knee arthroplasty, but the symptoms of gout may have often been mistaken as acute periprosthetic infection given their similarity. Misdiagnosis as periprosthetic infection can lead to unnecessary surgery, long-term dependence on anti-biotics, and even malfunction of the involved knee joint. Here, we report a case study of a patient with immunodeficiency condition of long-term oral glucocorticoid and diabetes mellitus, who had undergone a knee replacement 8 weeks before. The initial symptoms of fever and joint pain together with the dysfunction of her right knee with elevated inflammatory markers, such as increased serum leukocytes, erythrocyte sedimentation rate, C-reactive protein, and synovial cell counts led to a diagnosis of acute periprosthetic infection. Arthrocentesis and bacterial culture were performed preoperatively. According to the current Musculoskeletal Infection Society (MSIS) criteria for diagnosis of periprosthetic infection, the case was classified as periprosthetic infection and a prosthesis retained debridement surgery was performed. However we got negative culture results in all the pre-operative and intro-operative samples. The symptoms as well as the laboratory inflammatory markers improved shortly after the debridement surgery until the 11th day when all the similar systemic and local symptoms recurred. With a remedial crystal analysis of synovial fluid from the patient, gouty flare was found to be the cause of acute arthritis finally. Accor-dingly, after anti-gout medications were administrated, the symptoms associated with acute arthritis gra- dually subsided, and there was no recurrence during a 24-month follow-up. This article described the cli-nical manifestation, diagnosis and differential diagnosis, treatment of a case of periprosthetic gout. Although relatively rare, gout should be considered as a differential diagnosis in suspected periprosthetic infection. Current criteria for periprosthetic infection can not exclude the diagnosis of periprosthetic gout flare, it is therefore imperative that the analysis of joint aspirate for crystals be conducted to determine the correct course of treatment, or unnecessary surgical procedure may be performed in periprosthetic gout case.

The etiologies and prevention of patellar instability after un-resurfaced total knee arthroplasty / 中华外科杂志

<p><b>OBJECTIVE</b>To investigate the etiologies and prevention of patellar instability after total knee arthroplasty (TKA).</p><p><b>METHODS</b>From September 1997 to April 2005, 94 patients (105 knees) underwent TKA without patellar resurfacing. All of them were osteoarthritis. Ten patients (14 knees) were performed with Rotation Knee (RK) prostheses. Forty patients were performed with mobile bearing TACK prostheses, and 44 patients with GEMINI prostheses. Subluxation and tilt of patella were evaluated by X-rays before or after operation.</p><p><b>RESULTS</b>The incidence of patellar instability after operation was 28.6% in patients who had genu valgus deformity, and was 29.5% in whom had patellar instability preoperative. The incidence of patellar instability in RK, TACK, and GEMINI group was 28.6%, 20.9%, and 16.7% respectively after operations. Four patients had obvious femoral or tibial components malrotation.</p><p><b>CONCLUSIONS</b>The etiologies of patellofemoral instability include pre-operative conditions, prosthetic design, and improper positioning of the prosthetic component. So the suitable component design and skillful operative technique will help the surgeon to avoid this complication.</p>

Change in the joint line after total knee arthroplasty / 中华外科杂志

<p><b>OBJECTIVE</b>To investigate the change in joint line after knee arthroplasty.</p><p><b>METHODS</b>A total of 43 patients had 25 primary cruciate-retaining total knee replacements (Link Gemini MKII) and 25 rotational knee replacements (Link Endo-Model Rotational Knee System) sacrificing collateral ligaments and cruciate ligaments. Lateral radiographs were made both preoperatively and postoperatively. The change in the relative position of the joint line preoperatively and postoperatively was defined as the difference between the perpendicular distance from the weight-bearing surface of the tibial plateau to the tibial tubercle of the natural tibia (JL) and perpendicular distance from the weight-bearing surface of the prosthetic tibial component to the tibial tubercle (JL'). This distance was JL'-JL. The statistical differences between 2 groups were analyzed.</p><p><b>RESULTS</b>The distance of JL'-JL was 2.0 mm (-1.3 - 7.2 mm) in 22 patients with Gemini replacement, whereas the distance was 3.1 mm (-1.5 - 12.3 mm) in the other patients with rotational knee system. The difference was significant.</p><p><b>CONCLUSIONS</b>If the collateral ligaments and cruciate ligaments are removed during the knee replacement operations, the prosthetic joint line is likely to be malpositioned proximally. The fibular styloid and medial or lateral epicondylar reference points can be used to determine proper position of the joint line during operation.</p>