Motorised Intramedullary Bone Transport: A Scoping Review

Abstract

Background

Segmental bone defects present a significant reconstructive challenge in orthopaedic surgery and are traditionally reconstructed using external fixation. The advent of motorised intramedullary bone transport nails (BTNs) aims to mitigate complications associated with external fixation. Despite the theoretical advantages, the clinical efficacy and complication profile of BTNs remain unclear. This scoping review evaluates the current literature on the use of BTNs in segmental bone defect reconstruction.

Methodology

A search of PubMed, Google Scholar, and Cochrane Library databases was conducted following the PRISMA-ScR guidelines. Studies published between 2010 and 2024 that reported on motorised BTNs were included. Data extraction focused on patient demographics, defect characteristics, treatment strategies, complications, consolidation indices, and functional outcomes. Due to study heterogeneity, results were synthesised descriptively.

Results

Fifteen studies were included, comprising three retrospective cohorts, seven case series, and five case reports, totalling 61 patients. Most defects occurred in the femur (60.7%), with trauma (39.3%) as the most common aetiology. The mean defect size was 7.1 cm (range: 0.5–17 cm). The overall union rate was 92.3%, with a mean bone healing index (BHI) of 51.36 days/cm. A total complication incidence of 106.6% was reported, reflecting multiple complications in some patients, with device-related failures (22%), joint contractures (14%), and delayed union (9%) as common occurrences. While BTNs eliminate external fixation-associated morbidity, they introduce unique challenges such as mechanical failures and prolonged periods of non-weight-bearing. Patient-reported outcomes (PROMs) were rarely assessed, with only two studies reporting functional scores.

Conclusions

Motorised intramedullary bone transport offers a promising alternative to external fixation, particularly for femoral defects. However, BTNs introduce device-specific complications and remain costly and technically demanding. Current evidence is limited to small case series with heterogeneous methodologies, precluding definitive conclusions on superiority over external fixation. Future research should focus on multi-centre comparative studies with standardised outcome measures to establish the optimal role of BTNs in limb reconstruction.

Introduction

Segmental bone loss poses formidable reconstructive challenges.^1–4 These defects generally arise from trauma, infection or tumour resection and may be associated with soft tissue damage, requiring complex reconstruction.^5,6 Additional complicating factors in tumour resections include issues related to concomitant chemotherapy and radiation therapy, with slower regeneration formation and relative immunosuppression, again compounding reconstructive complications.⁶ While limb-salvage techniques have allow patients to avoid amputation in many scenarios, a single definitive procedure has been replaced with a complex reconstructive process requiring specialised levels of care, often expensive implants, multiple prolonged procedures, and significant morbidity.^2,7,8

Segmental bone transport harnesses the tension stress effect of distraction osteogenesis to generate new bone in the wake of an intercalary bone segment that is incrementally moved into the defect zone.^9,10 Historically, this approach is facilitated through the use of external fixation devices; however, these devices are associated with patient discomfort, prolonged external fixation times, pin site complications, and joint stiffness.^10–13 These challenges become even more pronounced when reconstructing femoral defects.¹⁴

To mitigate the use of external fixation and through advancements in intramedullary limb lengthening technology, fully internal, motorised nail systems that transport an intramedullary bone segment have been developed. Conceptually, fully internal bone transport systems promise a more ‘patient-friendly’ approach to segmental bone defect reconstruction, potentially reducing complications and improving patient comfort. However, the efficacy in complication mitigation and outcomes, combined with their relative novelty, complexity, and unique complication profile, needs examination in the available literature.^15,16

This scoping review evaluates the use of motorised intramedullary bone transport nails (BTNs) in segmental bone defect reconstruction. Specifically, it aims to (1) assess the efficacy, outcomes, and complication profiles of BTNs, (2) compare BTNs with external fixation, and (3) identify research gaps and future directions.

Overview of Bone Transport Techniques

Bone transport aims to gradually move a viable bone segment through the defect zone, promoting regenerated bone to form in the distraction gap.^14,15 Traditionally, various techniques have been utilised, each with unique benefits and limitations.

Traditional External Fixation Techniques

The Ilizarov method utilising circular external fixators remains the ‘gold-standard’ bone transport technique. This method of treatment preserves the local biomechanical environment necessary for bone healing by minimising iatrogenic injury through the use of percutaneous, wire fixation of all limb segments.¹⁷ However, complications such as pin site infections, soft tissue tethering and necrosis, and prolonged treatment duration limit long-term appeal.^3,12,17,18 Patients may also experience functional and physical limitations, such as joint stiffness and contractures resulting from prolonged immobilisation, gait abnormalities, and residual limb length discrepancies.⁷ The psychological burden of external fixation, which includes patient discomfort, reduced quality of life, and compliance issues, can significantly impact the overall treatment experience.⁶

Motorised Intramedullary Nailing Techniques

The development of motorised intramedullary BTNs aims to mitigate the drawbacks of external fixation. These nails rely on an internal motor to actuate an intercalary bone segment along the nail, thereby eliminating complications related to external fixator pins and improving patient comfort. The first documented use of this approach was reported in 2014 and ignited enthusiasm for this potential solution.¹ Initial enthusiasm was tempered by limited availability, device failures and high cost.⁵ Their use in the setting of infection also poses a risk of hardware-related sepsis.¹⁸ Despite these challenges, the appetite for these devices and their perceived benefits remains.⁶

Hybrid Techniques

Hybrid approaches such as lengthening over a nail (LON) or plate-assisted bone segment transport (PABST) have been implemented to harness the advantages of internal fixation. Although these approaches have successfully minimised external fixation time, they are technically demanding and harbour challenges and complications specific to each strategy.^2–4,14,17

Methodology

A scoping review was conducted according to the 2018 PRISMA extension for Scoping Reviews guidelines. [Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR)]. A literature search was conducted across PubMed, Google Scholar, and the Cochrane Library, with peer-reviewed articles published between 2010 and 2024 eligible for inclusion. Articles were selected based on relevance to BTNs, with emphasis on patient outcomes, complications, and consolidation times. Key search terms included ‘bone transport,’ ‘segmental bone defects,’ ‘bone transport nails,’ ‘hybrid bone transport,’ ‘motorised bone transport,’ and ‘bone defect.’ Boolean operators were applied to refine the search strategy, using combinations such as ‘bone transport AND motorised intramedullary nails’ and ‘external fixation OR bone transport nails.’ Reference lists of included articles were screened manually to identify additional studies. The final search was completed in November 2024.

Eligible studies encompassed retrospective analyses, prospective cohort studies, case reports and case series. Articles were required to report on key parameters, including patient demographics, defect characteristics, treatment strategies, and outcomes. Studies comparing BTNs with external fixation or hybrid techniques, such as PABST, were prioritised to ensure a balanced evaluation. Studies not written in English, those focusing solely on limb lengthening, and cases where bone transport data could not be disaggregated from limb lengthening cohorts, were excluded. Due to the novelty of motorised IMNs and the relatively low volume of published data, case reports were included to substantiate findings and demonstrate real-world applications.

Data synthesis involved both qualitative and quantitative approaches. Studies were grouped thematically, focusing on the use of motorised BTNs, comparisons with external fixation, and hybrid techniques. Consolidation indices, healing times, and complication rates were aggregated and summarised in tables to facilitate comparison. Complication profiles and unplanned surgical procedures were analysed to highlight patterns and identify recurring challenges (Fig. 1).

Fig. 1.

Flowchart of included studies

Results

Data from 15 included studies were aggregated. The included studies comprised three retrospective cohort studies, seven case series, and five case reports. The overall level of evidence was low, averaging Level IV (range: III–V), reflecting the predominance of case reports and small case series in this emerging field. Despite the limited volume and quality of data, the inclusion of these lower-level studies was warranted given the novelty of motorised intramedullary bone transport techniques and the paucity of literature on this specific treatment modality. Given the heterogeneity of study designs, treatment techniques and methodologies, a formal critical appraisal was not performed. Instead, the quality of evidence was assessed descriptively based on study design, sample size, and relevance to the scoping review objectives. This approach ensured that lower levels of evidence, such as case reports, were included to provide comprehensive insights into this emerging field.

A total of 61 patients were included in the analysis, though variability in reported metrics across studies limited the ability to systematically compare outcomes. Most studies focused on individual case examples, highlighting experimental treatment approaches with non-standardised data collection. The largest cohort study, by Mikužis et al., included 15 patients, followed by cohorts of nine patients reported by Olesen et al. and Kern et al.^2,7,8,19 Geographically, 10 studies were conducted in Europe (47 patients), while the remaining five studies originated from the United States of America (14 patients).

The main themes emerging from these studies centred on the exploration of motorised intramedullary bone transport as a novel technique, comparisons of outcomes and complications with traditional approaches, and its application across various aetiologies and anatomical locations. The key findings have been listed below:

Patient Demographics

The mean age of the patients included in the review was 42.3 years (range: 14–77), with a predominance of male patients (n = 49, 80.3%) in most studies. Comorbidities, when reported, commonly included smoking and diabetes, though less frequent conditions such as obesity, alcohol dependency, lupus erythematosus, hypothyroidism, rheumatoid arthritis, and psoriasis were also noted. Specific documentation of comorbidities was inconsistent, with only eight studies including detailed information. This variability presents a limitation, as these factors are critical in assessing host status and often need optimisation before surgery, potentially influencing outcomes.

Additionally, bone reconstructive surgeries for segmental bone loss often follow a series of prior surgical interventions, but the specific number and nature of these procedures were not consistently recorded across studies. The absence of this data further complicates the interpretation of outcomes.

Defect Location, Size and Aetiology

The treated anatomical sites primarily involved the femur (37 of 61, 60.7%) and the tibia (24 of 61, 39.3%). Summers et al. emphasised the importance of distinguishing between these two regions in reporting due to notable differences in outcomes. The higher occurrence of femoral bone transports (60.7%) highlights the desire to find an alternative to external fixation in this anatomical region. This observation aligns with Olesen et al., who reported divergent outcomes and conclusions based on the anatomical location of bone transport, further underscoring the region-specific challenges and benefits of these procedures.

The most common aetiology for bone loss was trauma, accounting for 39.3% (24 of 61) of cases. However, details regarding the specific types of fractures were limited. Among the 24 fracture-related cases, 18 involved open fractures, with 12 classified as Gustilo-Anderson (GA) Grade IIIA and six as Grade IIIB. Non-unions accounted for 32.8% (20 of 61) of cases, encompassing both septic and aseptic non-unions, although the distinction was inconsistently reported. Other aetiology included osteomyelitis (14.8%, 9 of 61) and tumour resections (13.1%, 8 of 61). The prevalence of open fractures, septic non-unions, and osteomyelitis underscores the complexity of the cases in this cohort.

Despite the high occurrence of these types of injuries requiring soft tissue management, only six studies documented the use or need for soft tissue reconstruction, such as flaps or deformity-assisted closures. This lack of documentation severely limits the ability to assess the impact of soft tissue management on outcomes, and meaningful interpretation was not possible.

Reported defect sizes varied considerably, with a mean of 7.1 cm (range 0.5–17 cm). Most studies reported defect sizes within the 5–10 cm range, although outliers were noted across the dataset. Larger defects appeared to correlate with increased complication rates, which, while anticipated, were not explicitly cited by the authors as contributing factors to poorer outcomes. Notably, femoral defects of up to 6 cm can often be managed with acute shortening. Yang et al. and Tetsworth et al. demonstrated that acute shortening provided outcomes that were equivalent to or superior to traditional bone transport methods.^17,20 This finding highlights the need to critically consider the use of bone transport for smaller defects, given the relatively high complication rates, technical complexity, and significant costs associated with these procedures.

Furthermore, Olesen et al. recommended shortening followed by secondary lengthening for defects below 3–4 cm in the tibia and 4–6 cm in the femur, suggesting that bone transport is not always necessary for managing smaller deficits. For defects exceeding 10 cm, bone transport alone was deemed suboptimal. Instead, acute shortening combined with bone transport and subsequent lengthening was advocated. This raises questions about the necessity of bone transport for smaller deficits, as these cases are often managed based on surgeon or patient preference rather than clear clinical indications.⁵

Surgical Techniques

The concept of ‘all-internal’ bone transport has evolved with variations in technique. Specific BTNs were used in 10 studies, accounting for 68.9% (42 of 61 patients), serving as both transport and stabilisation devices. Early adopters, including Kold et al. (2014) and Accadbled et al. (2019), used modified FITBONE nails (Wittenstein, Igersheim, Germany), while Krettek et al. (2017) employed a modified PRECICE nail (NuVasive Specialised Orthopaedics, Inc., Aliso Viejo, CA) combined with a Cylinder-Kombi-Tube Segmental Transport (CKTST) module (K-Implant, Hannover, Germany), as BTN technology was not yet commercially available. Among the BTN-treated patients, 52.4% (22 of 42) were managed with the PRECICE BTN and 35.7% (15 of 42) with the FITBONE nail.

A further five studies (31.1%, 19 of 61 patients) utilised the PABST technique, a ‘hybrid all-internal’ method that gained popularity between 2018 and 2021, likely due to the limited availability of BTNs. Wright et al. introduced a ‘dual-plating’ approach for femoral defects to counteract deforming forces associated with lateral plating. Although this added stability, it increased procedural complexity, particularly the need for medial femoral plating.

Several studies noted that bone defect location, soft tissue quality, and active or suspected infections were key factors in excluding motorised intramedullary nails.^2,4,7,12,18 Additionally, nail sizing, transport length, and the direction of transport (antegrade vs retrograde) were inconsistently reported, likely reflecting the variability in strategies tailored to specific pathologies. It is likely that a ‘best-fit’ philosophy is most commonly employed in these complex reconstructions.

The corticotomy level was another poorly documented parameter. Blair et al. highlighted the benefits of metaphyseal corticotomies due to superior vascularity, whereas diaphyseal corticotomies were associated with poorer regenerate formation.¹² The need for sufficient metaphyseal bone for nail interlocking often dictated the corticotomy site, potentially leading to suboptimal locations or the use of external fixation for peri-articular defects. Poor regenerate quality was linked to host factors, corticotomy techniques, and distraction rates, suggesting the corticotomy level may critically affect outcomes in bone transport nailing as an additional consideration specific to the utilisation of this technique.

Hardware removal was only documented in seven of the 15 studies, while nail exchanges were noted in five studies.^3,7,12,13,15 Although nail exchange is a routine step in BTN procedures, the lack of detailed reporting on complications or the timing of exchange procedures (e.g., during regenerate consolidation vs after union) represents a significant gap in the literature.

Distraction Protocols

Latency periods were reported in 12 of 15 studies and were typically clustered around 7 days, reflecting standard guidelines. Outliers such as Kold et al., Mikužis et al., and Krettek et al. reported latency periods extending up to 21 days, often based on clinical judgment or patient-specific factors.^1,7,21 Most studies reported a distraction rate of 0.25–0.33 mm per increment, applied 3–4 times daily, yielding a mean distraction rate of 0.79 mm/day. Slower rates were frequently adopted in cases of poor regenerative formation to optimise outcomes.

Transport Index

The transport index (days/cm) varied significantly due to inconsistencies in reporting and patient-specific protocols. Of the six studies providing sufficient data, the index ranged from 10 to 23.8 days/cm, with the majority (4/6) clustering between 10 and 12.6 days/cm, reflecting efficient transport times in most cases. However, the sparse reporting of this parameter highlights the need for standardisation in future research.⁵

Outcomes

One of the most critical parameters in assessing the efficacy of bone transport techniques is the rate of successful consolidation and healing. Among the studies reviewed, 12 of 15 studies reported their rates of successful union, with an average success rate of 92.3%. This included one patient lost to follow-up, one incomplete union at the time of reporting, and two non-unions. While high consolidation rates suggest favourable outcomes for motorised intramedullary nails (BTNs), the time required for union, both at the regenerate and the docking sites, emerges as a pivotal factor in evaluating the overall success of the technique.

However, as noted by Summers et al., the evaluation of healing time remains challenging due to inconsistencies in reporting and terminology across studies.⁵ Variations in definitions such as ‘bone healing time,’ ‘consolidation time,’ and ‘regenerate healing index’ make comparisons between techniques unreliable. For instance:

• Geiger et al. defined ‘bone healing time’ as the period starting with BTN insertion and ending once the bone has consolidated throughout its length.¹⁸

• Olesen et al. described ‘consolidation time’ as the interval from corticotomy to radiographic consolidation.²

• Summers et al. used the duration from the end of bone transport to complete radiographic union, bypassing limitations linked to implants and regenerate quality.⁵

• By contrast, Barinaga et al. and Wright et al. excluded this parameter altogether from their analyses.¹⁴

From the available data (6 of 15 studies), the reported bone healing index (BHI) averaged 51.36 days/cm (range 23.7–88.2 days/cm), while the consolidation index (CI), reported in two studies, ranged from 0.8 to 1.26 months/cm. While these indices provide insight into the healing process, their interpretation remains problematic due to the lack of standardised definitions and reporting.

When evaluating motorised intramedullary nail techniques, especially when compared to traditional external fixation, caution must be exercised. The variability in reported metrics, small cohort sizes, and heterogeneity in study designs limit the generalisability of findings. Only with standardised reporting and larger datasets can meaningful conclusions about the relative advantages and disadvantages of these methods be reliably drawn.

Complications

Bone defect reconstruction is inevitably associated with high complication rates due to local and systemic host compromise, a history of prior surgical interventions and inherent complexity of bone regeneration. Given these challenges, it is unsurprising that bone transport procedures demonstrate a higher incidence of complications compared to most other orthopaedic interventions. The introduction of all-internal bone transport systems aimed to address the high complication rates associated with external fixation, with the objective of reducing morbidity while maintaining effective bone regeneration.

To systematically evaluate complications in limb reconstruction, Paley developed a classification system that was later modified by Black et al., categorising adverse events into ‘problems,’ ‘obstacles,’ and ‘complications.^22,23 Despite this established framework, only Mikužis et al. appropriately applied the classification in their study, whereas the remaining studies broadly documented complications without standardised reporting.⁷ This lack of uniformity necessitated extrapolating complication rates from available data, introducing potential discrepancies in interpretation. Furthermore, as highlighted by Summers et al., significant variability in what constitutes a complication was observed.⁵ For example, some authors classified routine docking site procedures or implant-related revisions as expected interventions, while others considered them complications requiring unplanned surgical intervention.

Incidence and Nature of Complications

Among the 13 of 15 studies that reported complications, the mean incidence was 106.6%, with individual studies ranging from 22% to 200%. The largest cohort by Mikužis et al. documented 24 complications in 11 of 15 patients, with 19 unplanned surgical interventions required in 10 patients.⁷ The remaining two studies (3 of 61 patients) did not specifically report complications or unplanned surgical interventions. In total, 65 complications were documented across the 61-patient cohort, with the most common being screw failure (22%, 14 of 65), joint contractures (14%, 9 of 65), residual deformity (14%, 9 of 65), receiver failure (9%, 6 of 65), and delayed union (9%, 6 of 65).

Few studies stratified complications according to the Modified Black et al. classification, limiting direct comparisons with Liu et al., whose retrospective series of 282 bone transport cases using external fixators provided a more standardised complication assessment.¹⁷

Comparison between BTN and External Fixation Complications

A distinction must be made between implant-related complications and distraction osteogenesis-related complications.

• Bone transport nail-specific device-related complications:

  • – Screw failure

  • – Nail recharging

  • – Receiver failure

  • – Internal nail failure.

• External fixation device complications:

  • – Pin-site infections

  • – Axial deviation of the transport segment.

• Distraction osteogenesis complications common to both techniques:

  • – Poor regenerative formation

  • – Regenerate fracture

  • – Sepsis

  • – Joint contractures

  • – Residual deformity

  • – Neurological deficits.

Liu et al. identified pin-site infections (65.96%) and axial deviation (40.78%) as the two most common complications in external fixator-based bone transport. However, only 5% (3 of 60) of pin-site infections and 24.35% (28 of 115) of axial deviations were considered major complications requiring intervention. Thus, while their dataset reported a high rate of complications, most major complications were transport-related rather than device-related.

Furthermore, they did not stratify complications according to device or limb segment. All femoral bone transports (62 of 282) and 41.8% (92 of 220) of tibial bone transports were managed by mono-lateral external fixation. Hence, stratification of implant-related complications may vary significantly depending on whether they occurred in femoral or tibial defects and by the device used for reconstruction.⁵

Among BTN patients, device-related complications requiring surgical intervention accounted for 36% (23 of 65) of all complications, whereas transport-related complications accounted for 64% (42 of 65). This suggests that irrespective of the chosen transport method, transport-related complications are likely influenced by host factors, injury severity, and treatment complexity, rather than solely by the type of implant used.

Thus, while motorised intramedullary BTNs eliminate many complications associated with external fixation—such as pin-site infections, axial deviation, and soft-tissue tethering—they introduce unique device-related challenges. These frequently necessitate significant surgical interventions, increase treatment costs, prolong treatment duration, and contribute to patient morbidity. However, due to inconsistencies in complication reporting, meaningful conclusions regarding the comparative complication profiles of BTNs vs external fixation remain difficult to draw. Future studies must focus on standardised reporting of complications and device-specific failure analysis to enable reproducible and reliable comparisons between treatment modalities.

Functional Outcomes

Assessing the functional outcomes of BTNs is critical in determining their viability as a treatment option. This is particularly relevant given the significant functional limitations associated with prolonged external fixation, which BTNs are conceptually designed to mitigate. Three key parameters were commonly reported:

• Residual deformity, including limb length discrepancy (LLD) and angular deformities.

• Time to partial and full weight-bearing (PWB & FWB).

• Patient-reported outcomes (PROMs)–only in 2 of 15 studies.

Residual Deformity

Only four studies (33 of 61 patients) documented residual deformities. The largest cohort, Mikužis et al. (15 patients), reported that 10 of 15 patients had a residual LLD of <10 mm, while four patients had no discrepancy. One patient had a 30 mm residual femoral deficiency.⁷ Accadbled et al. reported a mean LLD of 31.7 mm (range 13–66 mm).^{1 1} Carrión Martínez. documented a 45 mm LLD following tibial non-union resection complicated by sepsis.¹⁶ Summers et al. noted that achieving equal limb lengths was not a primary objective; instead, they aimed for LLDs of 1–2 cm to reduce transport distances, as minor discrepancies are generally well tolerated.⁵ Wright et al. did not consider LLD an important functional outcome.¹⁴

Only Mikužis et al. documented residual angular deformities, with one patient having a 10-degree sagittal plane deformity.⁷

Weight-bearing and Functional Recovery

Time to weight-bearing was frequently reported (11 of 15 studies), but protocols varied significantly based on the device used and institutional protocols:

• Five studies allowed PWB from postoperative day 1.

• Two studies delayed PWB until 30–60 days postoperatively.

• Most studies initiated FWB only after docking was completed, with timelines ranging from 60 to 918 days after surgery.

This wide variability was influenced by implant diameter, bone transport distance, postoperative complications and the need for revision surgeries or additional procedures. Consequently, direct comparisons with external fixation are difficult. However, external fixators allow immediate weight-bearing due to the inherent stability of the terminal bone segments. While external fixation is often physically and psychologically challenging, BTNs introduce prolonged non-weight-bearing periods, which can significantly affect functional recovery and patient eligibility for all-internal bone transport.

Patient-reported Outcomes (PROMs)

Only two studies reported PROMs, highlighting the paucity of data on patient satisfaction and quality of life. Summers et al. found no statistically significant difference in the EQ-5D index (mean: 0.536, SD: 0.324) compared to the UK population.⁵ They attributed this to small sample sizes and were unable to determine whether BTNs effectively reduced disease burden. Accadbled et al. evaluated reconstructive limb lengthening following tumour resection in adolescents, reporting an increase in the Musculoskeletal Tumour Society (MSTS) score from 52.7 to 79.9.¹¹ They advocated for all-internal lengthening, citing favourable functional outcomes post-resection.

Given the lack of routine functional scoring and the heterogeneous pre-treatment pathologies, definitive conclusions regarding functional benefits remain inconclusive. The complex and varied aetiologies, as well as prior surgical interventions, likely play a significant role in influencing post-treatment functional outcomes.

Follow-up

Follow-up ranged from 8 to 89 months, with most studies concluding follow-up 1–2 years after nail removal.

Conclusion

The emergence of ‘all-internal’ bone transport techniques has provided surgeons with an alternative to external fixation, theoretically reducing its associated complications. However, current evidence is limited to small cohorts and case series, restricting the ability to draw definitive conclusions on their efficacy or to objectively compare their theoretical advantages over external fixation. Beyond the choice of treatment modality, segmental bone defects remain a complex pathology characterised by significant morbidity, prolonged treatment courses, and challenging prior interventions.

Bone transport, regardless of the technique used, is inherently associated with high complication rates. Determining whether BTNs or hybrid ‘all-internal’ techniques represent a superior alternative to traditional external fixation remains uncertain. While BTNs successfully eliminate external fixation-related complications, they introduce a distinct set of unique, device-specific, mechanical complications that remain a limitation of the current generation of implants. The challenges of external fixation in femoral transports are particularly pronounced, making BTNs a preferable option for femoral defects. However, the role of hybrid techniques, despite their increased complexity, remains to be fully defined. In contrast, for tibial bone transport, BTNs and hybrid techniques do not yet demonstrate clear advantages over external fixation in defects that permit their use.

Caution must be exercised when interpreting the available literature on all-internal bone transport. The limited number of studies, inconsistent outcome metrics, and varied methodologies result in ideological advantages and subjective recommendations often based on anecdotal evidence rather than robust comparative data. Future research should focus on larger, multi-centre, comparative patient cohorts, with standardised reporting metrics, and refinement of standard surgical protocols, to establish not only the true efficacy of all-internal bone transport but also its potential role as a definitive alternative to external fixation.

Artificial Intelligence (AI) Disclosure

No AI was used in the writing of this article.

Authors' Contribution

Dr EJ Fuzy – Conceptualisation, data collection and writing.

Prof N Ferreira – Conceptualisation, review moderation.

Dr J Haribhai – Data collection.

Orcid

Edward J Füzy https://orcid.org/0000-0002-2998-0829

Jayesh D Haribhai https://orcid.org/0009-0001-9211-9716

Nando Ferreira https://orcid.org/0000-0002-0567-3373