Intramedullary (IM) nailing is considered the gold standard for the treatment of diaphyseal fractures of long bones such as the femur, tibia, and humerus. Biomechanical principles, invasiveness, preservation of biology, and early mobilization have ensured positive outcomes for various patterns of fractures [1]-[3]. The last two decades have seen improvements in materials technology, locking design, reaming, and proximal fixation, which have significantly improved the outcomes for this procedure [4][5].

Although these advances in technology have improved the situation, complications related to mechanics are still a concern. Failures related to the implant—such as nail fractures—are rare but catastrophic events that often require high-sophistication revision surgeries, prolonged rehabilitation periods, as well as rising healthcare costs [6]-[9]. A fractured nail generally represents a fatigue fracture that occurs because of cyclic loading in a stable environment.

Incidence of IM nail fractures has been variably reported in the literature ranging from less than 1% in large cohorts or database analysis to over 7% in high-risk fractures [6]-[9]. This wide variation can be attributed to differences in locations of fractures, type of implants used, surgical practices, patient-related issues, or duration of follow-ups. There are certain fractures that are susceptible to failure of the IM nail due to the biomechanical conditions of the particular area of the femur bone. These are subtrochanteric fractures of the femur bone [10]-[13].

Several studies have identified risk factors for implant failure based on fracture patterns or surgical techniques. Poor reduction in varus has been identified as an important factor because it impacts loading from the bone-implant system to the implant itself, leading to quicker fatigue failure [10]-[12]. Fractures with complex patterns (AO/OTA 42C), delayed unions, and nonunions increase the time for loading cycles of the implant, thus potentially leading to implant failure [12][14][15]. While newer implants are designed to reduce stresses, the dominance of fracture patterns and reduction are more important in implant viability.

Various studies have found implant fractures in different parts of the body:

Ricci et al. (2014) found a fracture completion rate of 0.87% in 2175 femoral shaft fractures treated using Recon nails [6].The failure rate was 2.34% in 1069 subtrochanteric fractures fixed with PFNA/Gamma nails, reported by von Rüden et al. (2015) [7].A breakage rate of 0.56% was found by Chitnis et al. (2018) in a large database study of 10,000 hip and femur fractures [9].Smaller series, such as Haidukewych (2009), reported breakage rates of up to 7.1% in subtrochanteric fractures.

Despite multiple observational studies reporting implant breakage after intramedullary nailing, the true pooled incidence across long bones and the consistency of reported predictors remain unclear. No prior meta-analysis has comprehensively synthesized this evidence using contemporary PRISMA methodology. The objectives of this systematic review and meta-analysis were therefore to estimate the pooled incidence of implant breakage following intramedullary nailing of long bone fractures, explore heterogeneity through subgroup analysis by fracture location, and summarize predictors of mechanical failure reported across studies.

This systematic review and meta-analysis demonstrate that implant breakage following IM nailing of long bone fractures is an uncommon event, with a pooled incidence of less than 1%. However, when it occurs, it is associated with substantial morbidity and often necessitates complex revision procedures. The pooled incidence observed in this study aligns closely with large cohort and database analyses, such as that by Chitnis et al. (0.56%), while encompassing the higher failure rates reported in selected high-risk fracture subsets [6]-[9].

A key finding of this analysis is the significantly higher risk of implant breakage in subtrochanteric fractures compared with other long bone locations. This observation is biomechanically plausible and consistent with prior literature. The subtrochanteric region is subjected to high bending moments and shear forces during normal gait, compounded by the eccentric loading environment of the proximal femur [16][17]. Even minor malalignment, particularly varus malreduction, can dramatically increase stress concentration at the nail–bone interface, converting a load-sharing construct into a load-bearing one and accelerating fatigue failure [11][14][17].

Complex fracture patterns (AO/OTA 42C) further compromise mechanical stability and fracture biology. These injuries often require prolonged healing times and are associated with delayed union or nonunion, thereby extending the duration of cyclic loading on the implant [10][12][14][15]. The present review reinforces the concept that implant breakage is rarely an isolated implant-related issue, but rather a downstream manifestation of adverse fracture mechanics and biology.

Importantly, the updated risk of bias assessment demonstrated that most included studies were at serious risk of bias, predominantly due to residual confounding and retrospective design. However, no study was judged to be at critical risk of bias following exclusion of administrative database-only analyses lacking radiographic outcome verification. This strengthens confidence in the validity of the pooled incidence estimate while underscoring the need for cautious interpretation of causal predictors.

The substantial statistical heterogeneity observed (I² = 92%) likely reflects clinical and methodological diversity across studies, including differences in fracture location, implant design, patient populations, follow-up duration, and definitions of mechanical failure. Such heterogeneity is expected in meta-analyses of surgical outcomes and supports the use of a random-effects model.

Implant breakage following intramedullary nailing of long bone fractures is uncommon but clinically significant. Subtrochanteric fracture location, malreduction, complex fracture patterns, and impaired fracture healing are consistently associated with increased risk. Attention to fracture reduction quality, implant selection, and postoperative management may help minimize mechanical failure.

The findings of this review have several practical implications:

Precise fracture reduction, particularly avoidance of varus malalignment, should be prioritized.Nail length, diameter, and proximal fixation strategy should be individualized based on fracture morphology and patient factors.Adjunctive techniques, such as poller screws or augmentation plating in selected cases, may reduce mechanical stress.Patients with high-risk fracture patterns should undergo close radiographic surveillance to detect delayed union or nonunion early.

The strengths of this study include a comprehensive literature search, adherence to PRISMA 2020 standards, inclusion of large cohort and multicenter studies, and subgroup analysis by fracture location. Limitations include the predominance of retrospective designs, substantial heterogeneity (I² = 92%), and inability to quantitatively pool effect sizes for individual predictors due to inconsistent reporting. Moreover, publication bias is possible, as studies reporting zero or very low rates of implant breakage may be less likely to be published, potentially inflating pooled incidence estimates.

Prospective multicenter registries with standardized reporting of fracture characteristics, reduction quality, and implant parameters are needed to refine predictive models for implant breakage and guide evidence-based surgical decision-making.