The literature search was conducted using electronic databases, including PubMed, Clinical Key/Elsevier, EBSCO Discovery Service, MD Consult Science Direct, Scopus, EMBASE, Medscape, and Google Scholar. The search encompassed publications in any language and utilized the following terms: "intramedullary nail," "removal," "bent," "nail removal," and "removal technique." This comprehensive search yielded a total of 30 published case reports. Upon retrieval of the relevant texts, a detailed examination was performed to evaluate all removal techniques used from 1970 to the present. While various authors claimed to introduce novel techniques, it was observed that most of these techniques shared similar features and steps, often representing modifications of previously described methods [3,35]. In essence, five primary methods for the removal of bent intramedullary nails (IMN) were identified:

1. No additional intervention is required during standard extirpation.
2. The straightening in situ is followed by the standard extirpation.
3. Afterwards, the nail is manually straightened after partial weakening.
4. Extraction of the nail in two pieces after fully cutting it.
5. An axial bone window is created.

In this article, these techniques will be described in sequence, providing valuable insights into their respective procedures and applications.

No additional intervention is required during standard extirpation
This technique capitalizes on the inherent flexibility of intramedullary nails and is based on the assumption that bent nails will conform to the shape of the intramedullary canal during standard removal without causing any harm or additional fractures. Yip and Leung pointed out that the anatomic anterolateral bowing of the femur and the larger proximal intramedullary canal of the tibia further facilitate the removal of a bent nail [3]. Additionally, Biert and Edwards suggested that bent nails, especially those made of titanium, tend to lose their original strength and adapt more easily to the medullary canal than expected [4]. A significant advantage of this technique is that it protects the bone and soft tissues by employing external correction maneuvers and open surgery, without requiring any specialized tools or equipment beyond the standard nail extirpation set. However, it is crucial to carefully evaluate the strength and stiffness of the nail when considering this technique. In cases where the nail is thick and composed of stainless steel, the anticipated rebending to its original shape may not occur, potentially leading to additional fractures. Moreover, if the degree of angulation is high (≥ 20 degrees), this technique may also cause further fracture, as the nail can become firmly stuck in the canal [5]. Therefore, the indication for this technique is primarily thin, titanium nails, associated with a simple fracture, and preferably featuring anterolateral bending of the femoral nail and apex posterior bending of the tibia, with an angulation of less than 20 degrees [3].

The straightening in situ is followed by the standard extirpation
In this technique, the bent nail is corrected using external reduction maneuvers and subsequently removed through standard extirpation. External reduction of a bent nail can be achieved either manually or with the assistance of a specialized tool. Some authors have attempted manual reduction maneuvers as the initial correction technique, but they have reported limited success in achieving complete correction. Patterson and Ramser utilized a perineal post as a fulcrum to provide the necessary reduction force [6]. On the other hand, Haffernan et al. argued that while varus-valgus angulations can be corrected through manual reduction, anteroposterior angulations are more challenging, and attempting the reduction manually may lead to extensive soft tissue injuries. Therefore, they advocated for the use of the F-tool, a specially designed instrument for the reduction of long bones, to correct the nail [7].

The F-Tool, manufactured by Synthes, West Chester, PA, comprises three arms and is designed to facilitate the manual reduction of long bone fractures. By clamping the extremity between two arms and applying force in opposite directions (two-point bending) with the third arm, reduction is achieved. However, this closed reduction technique may be associated with certain complications. For instance, excessive force might be required to correct thick nails, potentially leading to soft tissue injuries, including damage to collateral ligaments around the knee. Additionally, the location of the angulations on the nail is crucial because if the nail is bent too proximally or too distally, more powerful reduction maneuvers may be necessary due to the shorter moment arm. In some cases, secondary fractures may occur, especially in osteoporotic patients or in those with longitudinal cracks.

Bek et al. reported an instance of an additional fracture line appearing after attempting manual reduction of a bent inflatable nail. This highlights the importance of careful consideration and assessment of the appropriateness of the manual reduction technique in specific cases, especially when dealing with challenging nail deformities or certain patient factors that may increase the risk of complications [8].

Afterwards, the nail is manually straightened after partial weakening
This technique represents one of the most commonly employed methods found in the existing literature. It revolves around the concept of weakening the nail before an external reduction can be easily achieved through manual strength. The process of partial resection or transection of the nail can be carried out using either an open or closed approach [9]. During this technique, the partial weakening or resection of the nail should be focused on the apex or tip to attain a straightened nail. If surgical exposure of the apex is feasible, this approach can be effectively utilized [10].

In the study conducted by Apivatthakakul and Chiewchantanakit, they described a percutaneous approach to weaken the nail [11]. In this method, they performed a partial resection or transection using a metal cutting drill bit and trochar sleeve through a small incision. This percutaneous technique offers the advantage of minimal invasiveness, potentially reducing the risk of complications and facilitating a quicker recovery.

The choice between open and closed approaches for partial resection or transection depends on the specific case and the location of the deformity apex. Surgeons must carefully evaluate each patient's condition to determine the most appropriate and feasible method for weakening the nail before proceeding with external reduction maneuvers [12].

Extraction of the nail in two pieces after fully cutting it
This technique involves an open surgical approach, requiring complete exposure of the nail at the site of angulation. Specialized instruments are used to cut the nail during the procedure. There are various options for cutting the nail, including motorized or manual metal cutting saws. Some of the tools used in the literature include the dental drill, Midas Rex high-speed burr, Ansbach metal-cutting oscillating circular saw, simple manual metal cutting saw, and jumbo pin cutters [13].

One crucial consideration during the procedure is to minimize the risk of soft tissue damage and necrosis caused by extensive heat generation. To achieve this, continuous irrigation with saline should be employed during the transection of the nail [14]. Additionally, copious debridement should be performed to remove any metal debris that may be produced during the cutting process. Failure to remove these metal debris could potentially lead to complications such as nonunion and infection [16].

The extraction of the bent intramedullary nail is typically carried out in two steps. The proximal part of the nail is extracted using standard techniques, while the distal part is removed through the fracture site. However, in some cases, the nail may become lodged in the intramedullary canal, making its extraction challenging. In such instances, a longitudinal cortical osteotomy may be necessary to free the nail and facilitate its complete removal [15].

As with any surgical procedure, careful attention must be given to patient-specific factors and the nature of the nail deformity to ensure the success and safety of the open surgical technique for nail removal. Proper execution of the procedure, along with meticulous postoperative care, is essential to achieve favorable outcomes and reduce the risk of complications [17].

An axial bone window is created
In this technique, a longitudinal bone flap is created along the bone to completely expose the bent intramedullary nail. The nail is first removed from the proximal bone fragment, and then it is twisted 180 degrees to facilitate its extraction from the distal fragment. Subsequently, the bone flap is stabilized using plates and/or cables. This particular approach has been employed by two authors for different purposes. Sakellariou et al. described using this technique as a secondary solution when external manual reduction had previously failed to correct the nail deformity. On the other hand, Bicici et al. resorted to this method to remove a portion of the nail that had become stuck in the proximal femur [18, 19]. It's important to note that this technique comes with some significant drawbacks. The procedure involves a wide incision and extensive dissection of soft tissues, which can lead to increased morbidity and a higher risk of complications. Additionally, additional osteotomy may be required, further adding to the complexity of the surgery and the potential for complications.

Due to the invasive nature of this technique and the associated risks, it is generally considered a less favorable option compared to other less invasive methods. However, in cases where other techniques have failed or when dealing with particularly challenging scenarios, it can serve as a viable alternative for removing a bent intramedullary nail in the lower extremity. As with any surgical procedure, careful patient selection and comprehensive preoperative planning are essential to optimize outcomes and minimize potential complications [19].