1 Introduction

Presently, the most accepted method of treating straightforward closed femoral diaphyseal fractures is with the use of an intramedullary (IM) nail due to a fracture healing rate of nearly 98%.¹ Despite these generally favorable results, bending of the nail secondary to additional trauma is a rare complication that has been reported only in case reports in the literature.^2–26 The type of nail, direction of bending, and presence of associated injuries all contribute to make this a technically demanding surgical problem oftentimes requiring a unique and elegant approach. Some surgeons have elected to fully transect the nail and remove the two pieces through either the fracture or the original proximal insertion site.^3–8 Others were successful in partially burring or drilling the nail at the apex of the deformity, and then manually straightening it so that it could be removed proximally in one piece.^9–15 Some groups preferred to employ closed or percutaneous methods to best preserve the soft tissue around the fracture site.^16,17 Regardless of the methods used to remove the nail, the fracture was then most frequently treated with repeat IM nailing for definitive fixation. Due to the limited number of case reports in the literature, however, no universally accepted technique for removal and revision has thus far been developed.

In this report, we present a case of one of the largest bent femoral IM nail deformities to date, and the largest to be removed in one piece. We also performed a systematic review of the literature to help provide a framework for approaching this challenging problem. The aims of this study were to (1) identify the most common mechanisms of injury, (2) identify any frequently associated injuries, (3) evaluate the surgical techniques employed, and (4) describe common pearls and pitfalls to approaching this injury. We hypothesized that outcomes would be generally favorable when bent femoral IM nails were treated with extraction and revision nailing, regardless of the technique employed for extraction.

1.1

1.1 Case report

Our patient is a previously healthy 16-year-old male who presented to our facility with a severely deformed right thigh after being involved in a motor vehicle collision eleven weeks status post intramedullary nailing for a femoral shaft fracture (Fig. 1). He was found to have refractured his femur through the initial fracture site. On x-ray his IM nail had bent to 65° of varus angulation. No evidence of a femoral neck fracture was found (Fig. 2).

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Fig. 1 Gross deformity present on admission.

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Fig. 2 Ap and lateral radiographic views of deformed intramedullary nail immediately after presentation.

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We performed exchange nailing in the lateral decubitus position with the aid of a proximal tibial traction pin. Preoperative fluoroscopic images were taken to identify the fracture site. This was marked and a 3 cm direct lateral incision was used revealing abundant callus. We debrided the callus along the lateral aspect of the fracture site enough to allow visualization of the bent nail. A cooled carbide burr allowed removal of the lateral aspect of the femoral cortex and callus. We then used sterile lubricant jelly at the fracture site to capture metal debris from the nail and began removing the lateral, or tension side, of the bent nail. Once approximately 50% of this nail was removed with the burr, care was taken to remove all sterile lubricant jelly and metal debris (Fig. 3). We then turned our attention distally to the distal interlocking screw. This was identified through a 1 cm lateral incision and removed under fluoroscopic guidance. Attention was then turned proximally where the proximal interlocking screw was removed halfway under fluoroscopic guidance, leaving it in to control for rotation during application of the extraction device. We then made an incision proximally through the previous entry incision. The greater trochanter nail site was found to have overgrown with bone callus and required debridement to the level of the proximal aspect of the intramedullary nail to allow for attachment of the extraction device to the nail. Once this was done, we turned our attention back to the fracture site. The nail was then bent back into the straight position through manual manipulation of the thigh under fluoroscopic guidance to ensure proper bending of the nail without causing a crimping or buckling deformity, which would create difficulty when attempting removal of the nail (Fig. 4). We then turned our attention back to the proximal aspect of the nail where we fully removed the proximal interlocking screw, and proceeded to remove the nail using the attached nail extractor with a back slap technique.

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Fig. 3 Intra-operative fluoroscopic image depicting hemisection of the nail using the carbide burr tip.

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Fig. 4 Straightening of the nail under fluoroscopic guidance.

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Reduction at the fracture site was verified visually through the incision and radiographically. We then placed a lateral entry intramedullary nail in standard fashion. At two months post-operatively, significant callous had formed around the fracture site with maintained length and alignment (Fig. 5). The patient was allowed to weight bear as tolerated at that point. At three year follow up, the fracture healed uneventfully without requiring additional surgery.

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Fig. 5 Ap/lateral radiographs at two months post-operatively showing a significant amount of healing fracture callous.

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2 Materials and methods

A written protocol was developed in adherence to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to conduct a systematic review of the available literature.²⁷ Pubmed/MEDLINE and Scopus/EMBASE databases were searched for relevant studies with the following search strategy: (bent OR deformed OR deformity) AND (femur OR femoral) AND (IM OR intramedullary) AND (nail OR rod OR device). All electronic databases were searched from their origination through January 1, 2020. Duplicates were removed from the results of the search. Two authors (M.L.D and A.B) independently reviewed all abstracts to screen for potential inclusion and then analyzed full text articles based off of inclusion/exclusion criteria. Inclusion criteria included all case reports or case series describing intact bent femoral IM nails published in English language peer reviewed journals. Exclusion criteria included articles published in other languages, abstracts/conference papers, nails already broken rather than bent, or cases describing nails inserted into other long bones such as the tibia or humerus. The references of articles that met criteria were also manually reviewed to ensure any additional relevant studies were not missed (Fig. 6).

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Fig. 6 Prisma flow diagram depicting the database searching and article screening process.

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A standardized template was created to extract data in a systematic method including author, year of publication, patient demographics, degree of angulation, mechanism of injury, time since initial procedure to reinjury, nail characteristics, surgical treatment, and clinical outcomes. Due to the rarity of the injury and paucity of case reports, comparative statistical analysis was not feasible.

3 Results

The literature search revealed 32 published reports of deformed IM nails. Two reports were not in the English language.^28,29 Two were unable to be obtained at our institution,^30,31 one was a conference paper and not published in a peer review journal,³² and two included descriptions of cases involving nails that were already broken in situ.^33,34 Therefore, a total of 27 cases in 25 reports met inclusion criteria and were included in qualitative analysis.

4 Discussion

Nail bending is a rare complication of treating midshaft femur fractures with intramedullary nail fixation. The most common clinical presentation described in the examined case reports was that of a young male sustaining a secondary high energy traumatic event leading to a varus or apex anterior deformity, either through a new femur fracture or the original fracture site. This is consistent with what was observed in our case report. Despite the various nuances encountered by the authors in each of the cases, the surgical techniques employed were one of six general treatment strategies: full transection of the nail, partial sectioning and manual straightening, limited corticotomy or creation of a longitudinal bone window, straightening with the assistance of a plate and reduction clamps, closed manipulation, or simple extraction without the need for manipulation. Regardless of the method used for extraction, however, nearly all of the residual femur fractures were then treated with revision IM nailing.

The earliest report of femur intramedullary nail bending was by Bielejeski and Garrick in 1970, who used a dental drill to cut a 12 mm stainless steel nail in half and remove the remnants through the fracture site.³ Since that time, more methods have evolved, but no universally accepted technique has emerged as each case must be addressed on an individual basis. In some cases, the degree of the deformity and the type of nail permitted the use of minimally invasive techniques for straightening and removing the nail. Patterson and Ramser were able to straighten the nail using a closed reduction technique with a perineal post to act as a fulcrum.¹⁷ Apivatthakakul and Chiewchantanakit employed a trochar sleeve to percutaneously access the apex of the deformed nail, then partially sectioned it using a metal cutting drill bit, which allowed them to manually reduce the deformity.¹⁶ In both cases, the soft tissue preservation around the fracture site was maximized. We also focused our dissection to the lateral apex of the deformity and carefully minimized unnecessary dissection, and used sterile surgical lubricant to capture metal debris intraoperatively. A key difference between these cases and our patient is the smaller angle of traumatic deformity present in these cases. In fact, our case represents one of the largest reported deformities to date, second only to the 85° varus deformity reported by Nicolaides et al.⁶ In their report, however, the nail was fully sectioned prior to removal and required significant soft-tissue disruption from a wide exposure, with diminished quadriceps function as a result.

Our patient may not have been fully healed at the time of his reinjury. We considered it fortunate that the nail was removable in one piece after hemisection and straightening. Our backup plan, should the nail have broken into two pieces, was first to employ the use of the long surgical hooked extraction guidewire (Synthes Proximal Femoral Nail Removal Set, Synthes, Paoli, PA) to extract the distal fragment through the proximal incision. The next choice would have been to extract the distal fragment through the fracture site, which would have necessitated a larger incision and dissection.

Comprehensive pre-operative planning is imperative when considering treatment of a bent IM nail. First, appropriate radiographic evaluation should be performed to determine the degree of angulation and whether the nail will be amenable to removal without manipulation^2,20 or if manipulation will be required. Next, the exact type of implant in place must be determined so that the appropriate extraction set can be made available and the technique for extraction can be formulated. For slotted, hollow IM nails, minimally invasive techniques can often be employed and in situ restraightening performed.^11,16,21 Nonslotted nails often require more extensive transection followed by partial or complete removal of implants.²² Surgical dissection near the fracture site should always be kept to a minimum to avoid disruption of the soft tissue and vascular supply. Following nail removal, consideration should be given to reaming and upsizing the diameter of the nail for additional stability.^{2,11,13,14,17,23} Finally, the surgical team should develop multiple back-up plans prior to beginning the case because the initially planned strategy can occasionally fail. For example, Nicolaides et al. describe attempting 5 different strategies prior to successfully extracting a 32° bent nail.⁶

An appropriate workflow for approaching the bent femoral intramedullary nail begins with prevention. Surgeons should closely monitor post-operative patients following treatment of femoral shaft fractures with IM nails through serial radiographs to ensure fracture healing. Consideration should also be given to obtaining Vitamin D levels so that any nutritional deficiencies could be identified and addressed to prevent cases of delayed or nonunion, as each case of atraumatic nail bending occurred through a fracture that had not yet healed. Once the nail has bent, however, surgical treatment is almost always indicated and one of the six general techniques should be selected. For nails bent up to 20°, standard removal without manipulation can be attempted first and is oftentimes successful. For nails between 20 and 30°, closed manipulation with a perineal post as a fulcrum can be tried first, with alternative back-up plans if unsuccessful. For any nails that cannot be extracted without manipulation or through closed means, partial or full transection of the nail is most frequently successful regardless of degree of angulation.

5 Conclusion

Bent IM nails are a rarely encountered challenge to the treating orthopaedic surgeon. No one technique has been identified as “the gold standard” and each case must be approached with its unique characteristics in mind. Hemisectioning of the nail over the apex can in essence allow a “closing wedge” osteotomy of the deformed nail and preservation of enough metal so that plastic deformation of the intact concave portion will permit straightening and removal using standard instrumentation.

Disclosure of funding

No funding was received for this study.