Infection after surgery to treat a tibial shaft fracture can have devastating consequences, with significant associated costs and burdens. Although research has identified general risk factors that increase the likelihood of infection (including complexity of injury and fracture patterns and patient-related factors such as smoking and diabetes), predicting risks for individual patients remains difficult.
In a recent study in The Journal, investigators from the Machine Learning Consortium reported on an algorithm they developed to predict the risk of infection in specific patients who receive operative treatment for a tibial shaft fracture. To develop their model, the researchers used high-quality data from the SPRINT (Study to Prospectively Evaluate Reamed Intramedullary Nails in Patients with Tibial Fractures) and FLOW (Fluid Lavage of Open Wounds) randomized controlled trials.
The Australian researchers “trained” 5 machine learning algorithms and tested them against various performance measures to evaluate 1,822 fractures, including 170 (9%) that developed an infection. Based on predictive performance in that derivation portion of the study, 3 algorithms were validated and 1 prediction model was found to be superior. In that model, Gustilo-Anderson Type IIIA and IIIB fractures, age, AO/OTA type 42C3 fractures, crush injuries, and falls were the strongest predictors of infection.
Researchers have made their model available in an online, open-access prediction tool. Although the authors emphasize that this preliminary tool is intended for research and not for widespread clinical use, I think it has profoundly positive potential. Being able to risk-stratify a patient with a tibial shaft fracture at or near the time of admission could allow surgeons to closely monitor—and intervene sooner—in fracture cases at risk for infection, thereby possibly preventing devastating complications. This prediction tool certainly needs external validation prior to “prime-time” adoption, but when it comes to exploring artificial intelligence and machine learning in orthopaedics, the future is now.
Matthew R. Schmitz, MD
JBJS Deputy Editor for Social Media
In our ongoing attempt to identify pharmacologic interventions that improve fracture healing, the sclerostin inhibitor romosozumab is a logical candidate, as it has been shown to decrease bone resorption, improve bone healing in animal and human studies, and reduce the prevalence of some fragility fractures in postmenopausal women. In the August 19, 2020 issue of The Journal, Bhandari et al. present the results of a randomized trial comparing romosozumab to placebo in the healing of tibial diaphyseal fractures treated with intramedullary (IM) nails. Tibial shaft fractures are common in adults, but even after IM nail fixation there is a significant rate of healing failure and subpar functional outcomes with this fracture type.
The study by Bhandari et al. was very well designed and conducted with high-quality data collection. In terms of the primary outcome—median time to radiographic healing—there was no significant difference between the placebo group (n=100) and 9 romosozumab groups (n=293 total, testing 3 different dose levels and 3 different frequencies). Additionally, analysis revealed no differences between placebo and romosozumab groups in median time to clinical healing or in changes in physical function from baseline. (See related OrthoBuzz post about a recent randomized trial investigating romosozumab for hip fractures.)
Kudos to Amgen for funding the trial and for allowing the 66-center, international academic consortium that conducted it to publish the results, warts and all. Such negative findings appropriately inform decisions about which compounds to investigate and about study designs for retesting the same compounds. For example, Bhandari et al. encourage further study of romosozumab in tibial-fracture patients at high risk of poor fracture healing, such as those with diabetes or patients undergoing treatment with corticosteroids.
We are likely to see many such “failures” in the search for pharmacological adjuncts to improve fracture healing, but it seems our orthopaedic community has laid out a clear roadmap for studying this important question further.
Marc Swiontkowski, MD
OrthoBuzz regularly brings you a current commentary on a “classic” article from The Journal of Bone & Joint Surgery. These articles have been selected by the Editor-in-Chief and Deputy Editors of The Journal because of their long-standing significance to the orthopaedic community and the many citations they receive in the literature. Our OrthoBuzz commentators highlight the impact that these JBJS articles have had on the practice of orthopaedics. Please feel free to join the conversation about these classics by clicking on the “Leave a Comment” button in the box to the left.
Prior to the innovative work of Gus Sarmiento in the 1960s, most orthopaedic surgeons treated tibial shaft fractures with a prolonged period of immobilization, in a long-leg non-weight bearing cast. While the fracture usually healed, knee joint stiffness and atrophy of the entire limb usually resulted as well.
In this 1967 JBJS classic, Sarmiento extended the concept of early weight-bearing treatment of these fracture as advocated by Dehne and others by incorporating the limb in a below-the-knee total-contact plaster cast, a technique that had recently been developed for the early rehabilitation of a below-the-knee amputation. The skin-tight plaster cast was applied over a single layer of stockinette one to two weeks after the acute swelling had subsided. It was molded proximally to contain the muscles of the proximal leg, and it had medial and lateral condylar flares, similar to a patellar-tendon-bearing (PTB) prosthesis.
Sarmiento encouraged early weight bearing in the cast, as he believed that doing so stimulated fracture healing. His confidence was borne out by this report of 100 consecutive tibial shaft fractures treated with a PTB cast. All 100 fractures healed, and healing occurred with minimal deformity or shortening. This success soon led to Sarmiento’s development of a functional below-the-knee tibial fracture brace made of Orthoplast®, a thermoplastic material which, when heated in a water bath, could be molded easily to the injured limb.
While today most tibial shaft fractures are treated with intramedullary nails, the principles developed by Sarmiento still apply, as the nail acts much like the fracture brace to maintain alignment during the healing process. Fracture healing is enhanced by weight bearing, and joint stiffness and muscle atrophy are avoided by early motion.
Sarmiento’s concept of functional treatment was later extended to the treatment of humeral and ulnar shaft fractures, which commonly continue today to be managed effectively with fracture braces that he developed. This emphasis upon early functional restoration while the fracture is healing has allowed many patients to achieve faster healing and to resume full function much sooner.
James D. Heckman, MD
JBJS Editor Emeritus