Background: Infection diagnosis in THA remains difficult in some cases. Intraoperative analysis of frozen sections is related to the high sensitivity, specificity, positive predictive value, negative predictive value and accuracy. However, it is a technically demanding procedure and is not a universally accepted method. In the present study, we compared interleukin-6 (IL6) serum level with the erythrocyte sedimentation rate (ESR), the level of C-reactive protein (CRP) and the analysis of frozen sections of intraoperative specimens (FS).

Materials: Sixty-nine patients with a THA needing a reoperation due to a suspected infection or another aseptic failure were studied. Patients with chronic inflam-matory diseases, antibiotic treatment prior to surgery, Paget’s diseases and immunodeficiency syndromes were excluded from the study. The mean age at the time of the operation was 68 years old (range: 39 to 91). ESR, CRP and the serum level of IL6 were measured in blood samples before surgery. The cut-off levels were: ESR: ≥ 32 mm/hr, CRP: ≥ 3.2 mg/dl and interleukin-6 ≥ 12 pg/ml. Intraoperatively, samples of tissues were taken to be analyzed immediately on FS, to be routinely processed at the moment and to be referred for bacteriological cultures and histological study.

Results: Eleven (16%) of the 69 hips were infected. ESR showed a sensitivity of 0.72 (0.41 to 1.00), a specificity of 0.86 (0.76 to 0.95), a positive predictive value of 0.50 (0.22 to 0.77), and a negative predictive value of 0.94 (0.84 to 1.00).CRP showed a sensitivity of 0.72 (0.41 to 1.00), a specificity of 0.91 (0.83 to 0.99), a positive predictive value of 0.61 (0.31 to 0.91), and a negative predictive value of 0.94 (0.87 to 1.00). IL6 showed a sensitivity of 0.36 (0.30 to 0.69), a specificity of 0.94 (0.88 to 1.00), a positive predictive value of 0.57 (0.13 to 1.00), and a negative predictive value of 0.88 (0.80 to 0.97). The evaluation of the FS showed a sensitivity of 0.81 (0.54 to 1.00), a specificity of 0.98 (0.94 to 1.00), a positive predictive value of 0.90 (0.66 to 1.00), and a negative predictive value of 0.96 (0.91 to 1.00).The combination of CRP and IL6 identified all patients with deep infection of the implant and showed a sensitivity of 0.57 (0.13 to 1.00), a specificity of 1.00 (0.99 to 1.00), a positive predictive value of 1.00 (0.87 to 1.00), and a negative predictive value of 0.94 (0.87 to 1.00).

Conclusion: In this study, we obtained similar results combining CRP and IL6 as with the analysis of the frozen sections, which has been in the past our first option to determine whether a THA is infected or not. IL6 and CRP may be used as a valuable routine diagnostic tool in revision THA.

Introduction: Autologous chondrocyte implantation (ACI) has been developed in order to repair cartilage successfully. Experimental models are based on osteochondral defects with potentially triphasic chondrogenic system: periosteal flaps, bone marrow cells and transplanted chondrogenic cells. All these three have chondrogenic activity so it is difficult to determinate the role of the implanted cells unless appropriate control is set up.

The purpose of this study is to determinate if the inoculation of chondrocytes under periosteal flaps does improve the chondrogenic potential of periosteal flaps.

MATERIALS AND Methods: 10 New Zealand rabbits, 8 months old were used. Right knees served as study group (ACI Group; N5: Chondrocytes + Periosteal Flap) – (Fibroblast Group: N5 Fibroblast + Periosteal Flap) and left knees as control group (N: 10: osteochondral defect alone). During the first procedure dermal fibroblast cells were isolated from skin biopsy and chondrocytes were isolated from the medial femoral condyle as a full thickness of the right and left knee were done. Chondrocytes and dermal fibroblasts cells were incubated for 4 weeks. Then they were implanted under periostel flap according to study group.

Chondrocyte and Fibroblast Implantation:

A parapatellar incision was performed on both knees. Defect was cleaned and on study group the periosteum taken from the tibia was sutured leaving one edge free to inoculate the chondrocytes or fibroblast according to group using a needle Then the defect was closed using fibrin glue. The animals were euthanatized 8 months postoperative.

Analysis: Specimens were evaluated using Hematoxylin and Eosin. Safranine and inmunohistochemistry for Collagen Type 2 using the ICRS score system.

Statistical Analysis: T student, Fisher and confidence interval were used. A p value < 0,05 was considered significant.

Results: Control non treated group presented a histological score grade mean IV (95% CI: 44–97)

The ACI group showed a tissue type means II (ICRS) (95% CI: 28–99%) Collagen type 2 was evident only in the deep layers. The fibroblast group did show a reparative tissue, tissue type mean II (95% CI: 28–99%) Collagen type 2 was evident in deep layers

DISCUSSION: According to this study the inoculation of chondrocytes under periosteal flaps does not improve significally the chondrogenic potential of periosteal flaps.(p: 0,77). Comparing the same procedure with chondrogenic and non chondrogenic cell lines could determinate the role of different chondrogenic components (periosteum and chondrocytes). Probably the chondrogenic capacity of the periosteum is sufficient to stimulate a reparative tissue. However none of these procedures could establish an adult normal cartilage hyaline tissue.