SPRINT Trial
Reamed versus Unreamed Intramedullary Nailing of Tibial Fractures
SPRINT Investigators · J Bone Joint Surg Am · 2008
The SPRINT trial demonstrated that reamed intramedullary nailing significantly reduces the risk of secondary reoperations to promote union in closed tibial shaft fractures compared to unreamed nailing, with no significant difference observed in open fractures.
Citation & links
Study to Prospectively Evaluate Reamed Intramedullary Nails in Patients with Tibial Fractures (SPRINT) Investigators, Bhandari M, Guyatt G, Tornetta P 3rd, Schemitsch EH, Swiontkowski M, Sanders D, Walter SD. Randomized trial of reamed and unreamed intramedullary nailing of tibial shaft fractures. J Bone Joint Surg Am. 2008 Dec;90(12):2567-2578.
Key findings
- 1.Overall cohort analysis demonstrated a non-significant trend favouring reamed nailing for reducing secondary surgical interventions (relative risk [RR] 0.82; 95% CI, 0.63 to 1.07; p = 0.14).
- 2.Pre-specified subgroup analysis revealed a statistically significant reduction in secondary procedures among closed fractures treated with reamed nails (RR 0.67; 95% CI, 0.47 to 0.96; p = 0.03).
- 3.Among patients with open fractures, reamed and unreamed techniques had similar reoperation rates (RR 1.12; 95% CI, 0.75 to 1.68; p = 0.58).
- 4.The primary driver for the difference in closed fractures was a higher requirement for dynamisation, bone grafting, or exchange nailing to address nonunion/delayed union in the unreamed group.
- 5.Hardware failure (interlocking screw breakage) occurred more frequently in the unreamed nail cohort.
- 6.No significant differences were identified between groups regarding deep infection rates (including open fracture cohorts), compartment syndrome, acute respiratory distress syndrome, or mortality.
- 7.One-year functional scores and quality of life measures (SF-36, SMFA) were comparable between treatment arms.
Background
Historically, substantial controversy surrounded whether intramedullary nailing of tibial shaft fractures should involve reaming of the canal. Proponents of reaming argued that it allows insertion of larger-diameter, stiffer implants with superior biomechanical stability and deposits osteoinductive autologous reamings at the fracture zone. Conversely, opponents feared that canal reaming might disrupt the endosteal blood supply, exacerbate cortical ischaemia, precipitate acute compartment syndrome, or increase infection and systemic pulmonary embolisation risks—especially in severe soft-tissue compromise or polytrauma. Prior trials lacked statistical power to definitively resolve this debate.
Methods
The Study to Prospectively Evaluate Reamed Intramedullary Nails in Patients with Tibial Fractures (SPRINT) was a pragmatic, multicentre, blinded randomised controlled trial conducted across 29 trauma centres in the United States, Canada, and the Netherlands. A total of 1,319 skeletally mature patients (1,226 included in the final analysis) with diaphyseal tibial fractures amendable to intramedullary nailing were randomised via a concealed centralised telephone allocation system to receive either reamed or unreamed nail insertion. Primary outcomes focused on secondary surgical interventions to achieve union (such as bone grafting, exchange nailing, or dynamisation) or reoperation for deep infection. Outcomes were blindly adjudicated using cropped radiographs focused strictly on the fracture site to mask nail diameter.
Clinical implications
The SPRINT trial established reamed intramedullary nailing as the standard of care for closed diaphyseal tibial fractures, successfully dispelling historical concerns regarding local and systemic complications. Furthermore, it showed that reaming does not increase infection risks even in open fractures, providing strong biological and clinical reassurance for reamed fixation across diverse clinical presentations.
Critical appraisal
Strengths include the rigorous multicentre randomised design, concealment of allocation, high follow-up rates (>90%), and an ingenious blinding strategy (cropping digital radiographs to obscure nail calibre from the outcome adjudication committee). Limitations include the open-label nature of surgery for the operating surgeon, significant post-hoc reliance on the closed versus open subgroup interaction, and heterogeneity in secondary procedural thresholds across individual institutions.
Teaching note
In viva examinations, SPRINT is the benchmark reference when discussing tibial shaft fixation. Candidates must highlight that reaming closed fractures reduces nonunion and reoperation without increasing complications, and that reaming in open fractures does not elevate deep infection rates.
Exam-tested points
- ›SPRINT stands for the Study to Prospectively Evaluate Reamed Intramedullary Nails in Patients with Tibial Fractures, published in JBJS Am in 2008.
- ›Reamed nailing significantly reduced reoperations to achieve union in closed tibial fractures (RR 0.67).
- ›In open tibial fractures, reamed and unreamed nailing demonstrated equivalent reoperation and union outcomes.
- ›Reaming did not increase the incidence of deep infection, even in Gustilo-Anderson open fracture types.
- ›Canal reaming did not elevate the risk of systemic pulmonary complications (ARDS/PE) or compartment syndrome.
- ›Unreamed nails were associated with higher mechanical complication rates, notably locking screw breakage.
- ›Outcome assessment relied on blinded adjudication using cropped radiographic images to prevent unblinding based on nail diameter.
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