gms | German Medical Science

Objectives: The management of polytraumatized patients remains a challenging issue. Depending on the trauma severity, two orthopedic approaches are implemented to provide fracture stability to the injured bones: Early Total Care (ETC) or Damage Control Orthopedics (DCO). A soft callus is initially formed during healing that evolves into a hard, mineralized callus. In our study, we aimed to perform a comparative histological analysis of the callus formation process during ETC and DCO in a polytrauma scenario.

Methods: A standardized, rat multiple-trauma model was used. Adult male rats were randomly allocated into 3 groups: Sham (n=6), ETC (n=12), and DCO (n=12). Rats in the sham group underwent skin incision and catheter placement. Contrarily, rats in the ETC and DCO groups were subjected to multiple trauma (pulmonary contusion, femur shaft fracture, and hemorrhagic shock). Immediately following blood transfusion and resuscitation, surgical fixation with intramedullary nailing was conducted in the ETC group. In contrast, fractures in the DCO group were stabilized by external fixation. At day 6 post-surgery, rats in the DCO group were switched to intramedullary nailing (DCO-IN). At 1- and 3-weeks after surgical treatment, specimens were collected and processed for histological examination by HE, Masson’s trichrome, Saf-O, and TRAP staining.

Results and conclusion: At 1-week post-surgery, the DCO-IN group showed evidence of callus formation. However, no connection between both ends of the callus could be concluded. Callus was identified in all the specimens in the ETC group that began to connect from both ends of the fracture. The callus formed in the ETC group showed early cartilage-like matrix formation. This was not observed in the DCO-IN group. The cartilage-like matrix in the ETC group was confirmed by Saf-O staining. At 3-weeks, the ETC group featured a larger and aligned callus structure, with increased maturation, mature osteoid matrix and trabecular bone-like structures. Staining for collagen was positive in both groups. Newly formed bone areas were larger in the ETC group compared to the DCO-IN group. ETC surgical intervention better-supported bone remodeling when compared to DCO-IN.

Collectively, our data showed that animals under ETC management were able to form an initial, collagen-rich healing callus tissue that featured cartilage-like matrix areas, further maturing into woven trabecular bone and ossification sites at 3-weeks post-intervention. This healing process was impaired under DCO-IN surgical treatment.