Postoperative surgical site infection in patients treated with lumbosacral fusion has been believed to be caused by perioperative contamination (Perioperative Inside-Out infections) in patients with comorbidities. With the proximity of these incisions to the perianal region and limited patient mobility in the early post-operative period, local contamination from gastrointestinal and/or urogenital flora (Postoperative Outside-In infections) should be considered as a major source of complication.

A single center, retrospective review of adult patients treated with open posterior lumbosacral fusions between January 2014 and January 2021. We aimed to identify common factors in patients experiencing deep postoperative infections. Oncological, minimally invasive, primary infection, and index procedures carried out at other institutions were excluded.

We identified 489 eligible patients, 20 of which required debridement deep to the fascia (4.1%). Mean age (62.9 vs 60.8), operative time (420 vs 390 minutes), estimated blood loss (1772 vs 1790 mL) and median levels fused (8.5 vs 9) were similar between the infected and non-infected groups. There was a higher percentage of deformity patients (75% vs 29%) and increased BMI (32.7 vs 28.4) in the infected group. The mean time from primary procedure to debridement was 40.8 days. Four patients showed no growth on culture. Three showed Staphylococcus species (Perioperative Inside-Out infections) requiring debridement at a mean of 100.3 days (95%CI 0- 225 days). Thirteen patients showed infection with intestinal or urogenital pathogens (Postoperative Outside-In infections) requiring debridement at a mean of 20.0 days (95%CI 9-31 days). Postoperative Outside-In infections led to debridement 80.3 days earlier than Perioperative Inside-Out infections (p= 0.007).

In this series, 65% of deep infections were due to early local contamination by gastrointestinal and/or urogenital tracts pathogens. These infections were debrided significantly earlier than the Staphylococcus species infections. Due to the proximity of the incisions to the perianal region, there should be increased focus on post-operative local wound management to ensure these pathogens are away from the wound during the critical stages of wound healing.

Introduction: The results of treating chondral lesions with microfracture have been well documented. The lesion heals by fibrocartilage and the functional results tend to deteriorate through time.

Hypothesis: The use of steroids an platelet rich plasma (PRP) as coadjuvants to microfracture for the treatment of full thickness chondral lesions improve the results of this marrow stimulating technique.

Purpose: To macroscopically, histologically and molecularly evaluate the repair tissue generated after treating full thickness chondral lesions with microfracture and local steroids or PRP in an animal model.

Materials: Experimental in-vivo study in 40 femoral condyles (FC) from New Zealand rabbits. Chondral lesions were induced in all the samples and divided into 4 groups:

Group 1: control, lesion left untreated.

Animals were sacrificed after 3 months and the samples were evaluated macroscopically, histologically (H and E, Toluidine Blue) and molecularly (RT-PCR for Col1 and Col2). The results were analyzed with ANOVA and Bonferroni tests (p< 0.05).

Results: Macroscopy: the control group had no healing tissue. In all the other groups there was a variable presence of a fibrocartilaginous tissue without significant differences among groups.

Histology: all the groups had the presence of fibrocartilage.

Molecular analysis: all the groups had a significantly poorer Col2/Col1 relation when compared to normal hyaline cartilage, without significant difference among groups.

Conclusions: The local use of betamethasone and PRP as coadjuvants to microfracture does not improve the macroscopical, histological and molecular results of the treatment of full thickness chondral lesions.

Introduction: Bunnell suture technique is effective for tendon repair. A modification of the classic suture technique could increase ultimate failure point (UFP) on the suture-tendon site. The purpose of this study is to evaluate UFP of regular and modified Bunnell suture techniques on in vitro porcine patellar tendons.

Methods: Porcine patellar tendon samples (N=24) were used for this study, separating them in 2 groups: Group A: classic Bunnell suture on the tendon (N=12). Group B: two perpendicular Bunnell sutures at 90° between them on the tendon (N=12). After suturing the samples, axial traction until failure on the tendon-suture site was applied on samples of both groups documenting UFP with a tension sensor device. UFP was measured and described in Newtons for all samples. Statistics: Non parametric Mann-Whitney test for independent variables was used to analyze outcomes.

Results: The UFP for group A was 224 ± 38,9 N. The UFP for group B was 307 ± 19,9 N. We found statistical differences among groups (p=0,00006).

Discussion: In this study we analyzed the UFP of classic Bunnell suture technique vs. a modification adding a second Bunnell suture perpendicular to the classic technique. The purpose of this modification is to increase the contact area between the suture and the tendon, reaching a stronger disposition at suture-tendon site. This has been documented in the UFP values obtained.

Conclusion: Adding a perpendicular Bunnell suture run in porcine ex vivo patellar tendons increases UFP in tendon repair at tendon – suture site.