Improvement in the detection rate of PJI in total hip arthroplasty through multiple sonicate fluid cultures

The microbiological culture of sonicate fluid (SFC) of explanted endoprosthetic components has increased the rate of bacterial isolation in comparison to conventional microbiological methods. However, this creates the problem of interpreting cases of singular bacterial isolation through SFC, while all other microbiological samples remain negative. The aim of this study was to reference these singular positive SFC against, the histological classification of the periprosthetic membrane (PM), and the utilization of multiple SFC (separate sonication of individual endoprosthetic components). In this prospective study we compared the effect of multiple SFC for detection of periprosthetic joint infection (PJI) in patients with total hip revision surgery. All microbiological results were referenced against PM. Of the 102 cases there were 37 cases of PJI. Single SFC achieved the highest sensitivity of all individual parameters with 89% and a specificity of 72%. When multiple SFC were employed the sensitivity and specificity increased to 100%. There was a concordance of 86% between the PM and SFC. SFC achieved the highest sensitivity and it was possible to further improve the sensitivity and specificity when using multiple cultures. Multiple SFC and PM are beneficial to help reference singular bacterial isolations and achieve the diagnosis of PJI.

[Results after anterior cruciate ligament revision surgery]

Revision surgery after failed anterior cruciate ligament reconstructions has increased tremendously. Reasons for revisions are persistent loss of motion, recurrent joint laxity, a painful knee or joint infections. In a retrospective study with a mean follow-up of 35.2 months 82 patients were examined after revision surgery. Time interval between primary and revision surgery, causes of revisions and treatment modalities were evaluated and compared to subjective, clinical and radiological parameters. In all cases a clinical improvement could be achieved. But results after revision operations are inferior to first reconstructions. The mean Tegner score improved after revision surgery from 2.4 to 4.6 points. The mean Lysholm score increased after secondary surgery from 54 to 76 points. The overall IKDC results of follow-up showed category A - 35.4 %, B - 39 %, C - 13.4 % and D - 12.2 % of the patients. A distinction between patients with preoperative isolated loss of motion and patients with isolated joint laxity seems useful. Revision operations with an improvement of joint mobility showed a higher subjective satisfaction, a lower rate of joint instability and better overall IKDC result compared to those with a high grade of preoperative joint laxity. Better results could be also achieved for early revision compared to late revisions and also for autologous grafts compared to alloplastic revision plasty. Transplant retaining procedures are only possible in selected cases and showed no clinical benefit compared to second revision of cruciate replacements. As a result of this study we conclude that early revision operation and the use of an autologous graft can be recommended but the surgeon has to be prepared to encounter many demanding technical problems.

[Periprosthetic osseous changes 2, 4, and 6 years after implantation of cementless Zweymüller-stems-- A cross-sectional study]

AIM

According to the results of longitudinal studies, the use of distally anchored femoral prostheses leads to marked proximal stress shielding. Zweymüller stems should be controlled some years after implantation.

METHOD

In a cross-sectional study, we examined 92 patients clinically, radiologically, and osteodensitometrically 2, 4, and 6 years after implantation in order to assess the osseointegration of Zweymüller shafts as independently as possible of age. The non-operated contralateral limb or Gruen's zone 4 below the prosthesis was used as a control group.

RESULTS

At no time did the parameters assessed indicate any reduction in proximal bone density as compared with the control group. Zone 7 (medial-proximal) even showed an increase in bone density after 2 and 4 years. Nevertheless, absolute bone density was lowest proximally both pre- and postoperatively. Six years after implantation women even showed a 15 % increase in summated periprosthetic bone density as compared with the control group. No influence of femoral shape on bony remodeling was demonstrated.

CONCLUSION

Periprosthetic bony remodeling cannot be attributed exclusively to the shape of the shaft. Longitudinal studies do not adequately reflect the reduction in periprosthetic bone mass that occurs as a function of age and altered activity level. The osseointegration of hip prostheses is influenced by other factors such as musculoskeletal lines of force, sex, and age.

Imaging of low-grade bone infection with a technetium-99m labelled monoclonal anti-NCA-90 Fab' fragment in patients with previous joint surgery

Low-grade bone infection represents a serious clinical problem. Diagnostic options are often insufficient, yet the therapeutic implications of proven disease are important, especially in patients with prosthetic joint replacement. Technetium-99m labelled monoclonal anti-NCA-90 granulocyte antibody Fab' fragment (MN3 Fab') has been shown to be useful in bone and joint infection, but there are no data specifically referring to low-grade bone infection. We therefore analysed 38 scans in 30 consecutive patients (age range, 30-85 years; median age, 62 years) referred for suspected low-grade bone infection. There were 17 patients (21 scans) with total hip arthroplasty (THA), six with total knee arthroplasty (TKA), three who had undergone hip or knee surgery for trauma and five (seven scans) with resected hips and no endoprostheses (Girdlestone situations); one of these five patients had been investigated before with THA in situ and another prior to surgery for low-grade coxitis. There were no patients with rheumatoid arthritis as the underlying disease. Results were verified by means of bacteriological cultures, histopathological findings and/or follow-up and compared with the respective Zimmerli scores, which were used for clinical assessment of inflammatory activity. In one patient, the final diagnosis could not be established. One, 5 and 24 h after intravenous injection of up to 1.1 GBq of MN3 Fab', whole-body and planar scans were performed using a dual-head gamma camera. Scans were analysed visually and semiquantitatively adopting an arbitrary score ranging from 0 to 3. There were 13 true positive, 14 true negative and 10 false positive outcomes, yielding an overall sensitivity of 100%, an overall specificity of 58%, an accuracy of 73% and positive and negative predictive values of 57% and 100%, respectively. In patients with THA or TKA, accuracy was 81% and 80%, respectively, while it dropped to 43% in patients with Girdlestone situations owing to a high proportion of false positive findings (4/7) in this subgroup. Scintigraphic score was 1 in all of the false positive and in 11/13 true positive findings. The two remaining true positive findings displayed scintigraphic scores of 2 and 3, respectively. Scintigraphic and Zimmerli scores were loosely correlated (Spearman rho=0.38, P<0.05). Infection was excluded in 22/24 investigations with Zimmerli scores of <6. In this group, there were 13 scintigraphically true negative, nine false positive outcomes, and just two true positive outcomes. In 11/12 investigations with Zimmerli scores of 6 or 7, infection was verified and scintigraphic outcome was accordingly true positive, while the remaining patient was true negative. In conclusion, MN3 Fab' scintigraphy proved to be highly sensitive but not specific in diagnosing low-grade infections of the hip and knee regions in patients with previous joint surgery. The method seems reliable in excluding but not in proving the presence of infection. MN3 Fab' scintigraphy should not be applied in patients with Girdlestone situations. Assessment of infection using the Zimmerli score was more reliable than MN3 Fab' scintigraphy in this group of patients without rheumatoid arthritis as the underlying disease. Considering results from the literature concerning leucocyte scintigraphy, MN3 Fab' scintigraphy may be clinically useful in evaluating low-grade bone infection in THA and TKA patients with Zimmerli scores above 5 and concomitant rheumatoid arthritis or other inflammatory diseases.

[Recovery and duration of work disability after laparoscopic and conventional appendectomy. A prospective randomized study]

To evaluate whether laparoscopic appendectomy shortens the convalescence and the postoperative period until return to work when compared to conventional appendectomy, a prospective randomized trial was performed. The major endpoint of the study was the time until return to work; minor endpoints were postoperative pain, fatigue, operative time and postoperative morbidity. In all, 54 patients with a mean age of 29.5 +/- 10.1 years were randomized to open (n = 28) or laparoscopic appendectomy (n = 26). Age, sex, body mass index (BMI), American Society of Anesthesiology (ASA) rating, job status as well as histologic degree of inflammation of the appendix were comparable in the two groups. Operative time was 59.2 +/- 15.8 min for laparoscopic and 59.8 +/- 24.4 min for conventional appendectomy (P = 0.9). Some 16 laparoscopic appendectomies (62%) were performed by board-certified surgeons, while 23 conventional appendectomies (82%) were performed by residents (P = 0.003). Postoperative morbidity was comparable between the two groups. After laparoscopic appendectomy, pain was rated significantly lower on the first, second and fourth postoperative day when compared to the conventional group. There were no difference in postoperative fatigue between the groups. Time to return to work was 17.0 +/- 6.2 days in the laparoscopic group and 18.2 +/- 6.0 days in the conventional group (p = 0.5). Laparoscopic appendectomy has no advantages in terms of convalescence and time to return to work when compared to open appendectomy and should therefore be limited to selected cases.