Nonvascularized fibular grafting in nonunion of femoral neck fracture: A systematic review

Abstract

Nonunion of femoral neck fractures following primary fixation and neglected femoral neck fracture in young adults is a challenging task. Every effort should be directed toward hip joint salvage in these patients. Among different available options of hip salvage, nonvascularized fibular graft (NVFG) osteosynthesis is simple, easy to perform, and a successful technique. In this review, the available literature on NVFG in neglected and nonunion femoral neck fractures has been analyzed. After review of 15 articles on NVFG, the average nonunion rate was estimated to be 7.86% (range 0–31%). Six articles that evaluated the preoperative and postoperative osteonecrosis reported improvement in 50% patients. The clinical and/or functional outcome was good to excellent in 56–96% patients following fibular osteosynthesis. Few complications such as coxa vara deformity, limb shortening, and intraarticular penetration of the graft or hardware have been reported. However, there are minimal donor site morbidities such as mild ankle pain, transient loss of toe flexors and extensors and transient lateral popliteal nerve palsy.

INTRODUCTION

Management of neglected and nonunion of femoral neck fracture is a challenging task.¹,²,³,⁴ There is no exact definition of neglected femoral neck fracture in the literature. Some studies report more than 3 weeks of delay as neglected, while others take 6 weeks as the time limit. However, definition of nonunion is relatively clear. Zuckerman defined it as a lack of radiographic evidence of union 6 months after the fracture.⁵ The patient usually presents with pain on weight bearing after 3 months of fixation. Radiological evidence of nonunion becomes apparent within 1 year.⁶,⁷,⁸,⁹ The incidence of nonunion as reported in literature varies between 10% and 30%.⁴,¹⁰ The choice of treatment in such scenario depends on the age, the activity level, the duration of injury, the extent of displacement, and osteoporosis.⁴ This fracture is common in the elderly population in Western countries, but young individuals equally succumb to this injury in developing countries because of high incidence of road traffic accident.¹⁰ While nonunion following primary fixation in the young adults is a worrisome problem for the patients and the surgeon both throughout the world, many patients in the developing or underdeveloped countries do not seek medical treatment for months and remain neglected.

The treatment of nonunion or neglected femoral neck fracture in the elderly patients is a prosthetic replacement, and there is no controversy in such management.⁴,¹⁰,¹¹,¹²,¹³ However, there is no firm guideline to deal with femur neck fracture nonunion or neglected cases in the young individuals. Many hip preserving procedures are adopted in these young individuals. The procedures are either a proximal femoral osteotomy or bone grafting (muscle pedicle graft, vascularized or nonvascularized fibular graft [NVFG]) or a combination of osteotomy and bone grafting.¹⁰,¹¹,¹²,¹³ Proximal femoral osteotomy usually causes shortening, limping, and restriction of range of motion with the potential risk of nonunion at the osteotomy site.¹³ The vascularized bone grafting is technically more challenging and need expertise, but NVFG is simple and technically easier to perform.¹³

NVFG for femoral neck fracture was first used by Henderson in 1940.¹⁴ Subsequently, Inclan and Patrick also reported a favorable outcome with the use of NVFG in fracture neck of the femur.¹⁵,¹⁶ “One cancellous screw and a fibular graft” was popularized by Nagi et al. in 1981 and subsequently, it was routinely used for neglected femoral neck fracture.¹⁷ In this review, the success rate, outcome, and complications of NVFG in neglected and nonunion of femoral neck fracture will be appraised.

MATERIALS AND METHODS

The PubMed/Medline, Scopus, Embase, and Cochrane databases were searched using keywords “nonunion femoral neck fracture,” “neglected femoral neck fracture,” and “fibular graft” to retrieve articles evaluating the outcome of nonvascularized fibular graft in neglected and nonunion femoral neck fracture [Flow Chart 1]. A total of 304 articles were retrieved. After filtration, we could find 230 articles on human species published between January 01, 1980, and December 31, 2014, in English language. The case reports, letter to editors, review articles, and meta-analysis were excluded from this review. The abstract of the remaining articles was read and only those articles that evaluate the outcome of nonvascularized fibular graft in neglected and nonunion of femoral neck fracture were included for review. The references of these articles were also hand searched for any missing article. From 16 articles, one article¹⁸ on combined valgus osteotomy and fibular grafting were excluded as there were two principles of femoral neck fracture management. All total 15 articles were included in this review [Flow Chart 1].¹⁷,¹⁹,²⁰,²¹,²²,²³,²⁴,²⁵,²⁶,²⁷,²⁸,²⁹,³⁰,³¹,³²

Flow Chart 1.

PRISMA flow chart

RESULTS

Indications of fibular graft

All articles except by Dooley and Hooper²⁰ used NVFG in young adults below 60 years of age for neglected and nonunion of femoral neck fracture fixation. The definition of neglected femoral neck fracture varies in these articles. Nine articles reported more than 3 weeks of delay as neglected,¹⁷,²³,²⁴,²⁶,²⁷,²⁸,²⁹,³⁰,³² whereas remaining articles mentioned more than 6 weeks as the definition of neglected fracture.¹⁹,²⁵,³¹ However, the definition of nonunion is quite clear.²⁰,²¹,²² No evidence of progressive healing on anteroposterior and lateral radiographs and disabling hip pain within 6 months of primary fixation was considered as nonunion. Sen et al. had 16 nonunion after cannulated cancellous screw fixation and 6 nonunions after dynamic screw fixation, whereas Elgafy et al. reported eight nonunions after cannulated cancellous screw fixation, seven nonunions after dynamic screw fixation, and two after initial conservative treatment. Dooley and Hooper did not find an obvious cause of nonunions in all of their cases, but they could identify four nonunions because of inability to recognize the original fracture and ten nonunions were because of poor reduction or inadequate fixation. As per the Sandhu et al., Grade I femoral neck nonunion (proximal fragment >2.5 cm, irregular fracture margin, fracture gap of <1 cm, and viable femoral head) has union rate of 100% followed by 89% in Grade II (proximal fragment >2.5 cm, smooth fracture margin, fracture gap between 1 and 2.5 cm, and viable femoral head) and 33% in Grade III (proximal fragment <2.5 cm, smooth fracture margin, fracture gap between >2.5 cm, and osteonecrotic femoral head) after NVFG osteosynthesis. Partial resorption of neck and presence of osteonecrosis in the femoral head are not a contraindication and it may show improvement after fibular osteosynthesis.¹⁷,¹⁹,²¹,²⁵,²⁶ Thus, neglected or nonunion femoral neck fracture (whether displaced or undisplaced) with proximal fragment more than 2.5 cm and fracture gap of <2.5 cm can be effectively treated with NVFG osteosynthesis.

Methods of reduction, supplementary fixation, and rehabilitation

Closed reduction or open reduction

Two articles by Nagi et al. reported open reduction (OR)¹⁷,¹⁹ and another seven reported closed reduction (CR) of the fracture site.²²,²³,²⁸,²⁹,³⁰,³¹,³² Five articles reported CR where possible and OR when CR failed.²⁰,²¹,²⁴,²⁵,²⁶ The authors supporting OR assert that by opening the nonunion site, the interposed fibrous tissue between the fracture fragments can be removed. Moreover, the fracture ends can be freshened, and the neck-shaft angle can be adjusted. The other group of authors who claim that there is no need to open the fracture site believes that the fibular graft acts as a biological augmentation and stimulate union in the interposed fibrous tissue that gets converted to osseous tissue. By not opening the fracture site, it preserves the blood supply of the femoral head.¹¹ The best approach seems to be intermediate between these two. An initial CR (traction in 45° flexion and then slight abduction followed by extension and internal rotation to 30–45° to bring the limb parallel to the trunk) should be attempted on a traction table.²³,²⁴,²⁸,²⁹,³⁰,³¹,³² When CR fails (in grossly displaced fracture with neck resorption), OR through Watson–Jones anterolateral approach must be performed.²¹,²⁴,²⁵,²⁶

Nail, screw, or angle fixed device

Thirteen of fifteen articles reported use of cancellous screws (preferably cannulated) as the supplementary fixation.¹⁷,²⁰,²²,²³,²⁴,²⁵,²⁶,²⁷,²⁸,²⁹,³⁰,³¹,³² Dooley and Hooper used nail or plate as the supplementary fixation. Angle fixed device was reported in our own previous article.²¹ We believed that numerous complications such as graft slippage and fibular graft fracture that have been reported with the use cancellous screw were because of excessive force exerted on the graft and not offloaded by the screws. Angled blade plate (ABP) provides better stability because of its rectangular shape and resists more torsional and shearing forces.²¹ However, placement of ABP is technically more challenging. After this review, it is fairly apparent that a fibular graft with cannulated screws is an optimal fixation for neglected and nonunion cases of femoral neck fracture. This is technically simple and can be performed in most of the center.

One screw or multiple screws

Except Nagi et al.¹⁷,¹⁹ all authors recommended placement of two or three screws (6.5 mm or 7 mm cannulated cancellous screw) along with the fibular graft. The authors believe that multiple screw fixation allows early rehabilitation of the patients in the postoperative period. While Nagi et al.¹⁷,¹⁹ recommended hip spica cast for more than 6 weeks in their patients because of inadequate stability by one supplementary screw, remaining all authors²⁰,²¹,²²,²³,²⁴,²⁵,²⁶,²⁷,²⁸,²⁹,³⁰,³¹ allowed early postoperative partial weight bearing in their patients because of better stability. Thus, additional support with two or more cannulated screws is desirable in NVFG osteosynthesis.

One graft or dual graft

Most of the articles reviewed used only one fibular graft for osteosynthesis [Figure 1].¹⁷,¹⁹,²⁰,²¹,²²,²³,²⁵,²⁶,²⁷,²⁸,²⁹,³¹ However, three articles²⁴,³⁰,³² reported about the dual fibular graft fixation. Sandhu et al.³² used one cancellous screw and a double fibular graft in 86.3% patients and two cancellous screws with one free fibular graft in 13.7%. They noted union in all of their patients with single fibular graft who were of Grade I nonunion as per Sandhu et al. In double fibular graft group, they noted 100% union in Grade 1, 89% in Grade II, and 33% in Grade III. Pal et al.²⁴ used two fibular grafts with one screw for those patients who had a longer delay and greater resorption of the neck and/or posterior comminution of the femoral neck. For other neglected patients, they used only one graft and two screws. But nothing could be concluded from this article as it was not a comparative study rather the authors themselves divided the patients into these two groups of treatment and just reported the outcome combinedly. However, they noted a longer time for union in some of their patients who had excessive resorption of neck (treated with dual fibular graft). Similarly the report of Jaiswal et al.,³⁰ who divided the patients into two treatment groups (dual fibular graft and dual graft + one screw), also could not provide extra information about the advantage of dual grafting. As per the current evidence, one fibular graft and two supplementary screws are adequate.

Figure 1.

X-ray left hip joint anteroposterior view showing (a) A 30-year-old female with 6-month-old femoral neck fracture; (b) the fracture has united after nonvascularized fibular graft osteosynthesis (c and d) After 13 years the hip joint is still preserved with good functional outcome (Courtesy: Professor Nagi)

Rehabilitation

Except by Nagi et al.¹⁷,¹⁹ remaining all authors adopted an early rehabilitation. Nagi et al.¹⁷,¹⁹ used hip spica cast for 6 weeks because of one supplementary screw in their patients and hence the fixation was inadequate. Remaining all authors allowed immediate postoperative nonweight bearing walking on crutches for 6–8 weeks and then partial weight bearing. Complete weight bearing was restricted until radiological evidence of union was noticed.

Clinical outcome

Nonunion

On cumulative evaluation of the patients in the reviewed articles, the average nonunion rate after NVFG is 7.86% [range: 0–31%, Table 1].¹⁷,¹⁹,²⁰,²¹,²²,²³,²⁴,²⁵,²⁶,²⁷,²⁸,²⁹,³⁰,³¹,³² The nonunion rate in 12 of 15 studies was <10%.

Table 1.

Studies evaluating the outcome of fibular osteosynthesis in neglected and nonunion of femoral neck fracture

Osteonecrosis

All except two studies²²,²⁷ have mentioned the number patients who developed osteonecrosis or who had progression of osteonecrosis. The incidence of postoperative osteonecrosis varies between 0% and 21%.¹⁷,¹⁹,²⁰,²¹,²³,²⁴,²⁵,²⁶,²⁸,²⁹,³⁰,³¹,³² Six studies¹⁷,¹⁹,²¹,²³,²⁵,³² where the preoperative and postoperative osteonecrosis status are mentioned clearly indicate that there is an improvement in osteonecrosis after fibular osteosynthesis. A total of 26 patients (total avascular necrosis in these six articles) had osteonecrosis in the preoperative period and only 13 patients remained osteonecrotic in the postoperative period [improvement in 50% of patients, Table 1].

Hip scores

There was no uniformity in the evaluation of hip function or functional outcome. Various scores were used by the authors. The clinical and/or functional outcome was good to excellent in 56–96% of patients following fibular osteosynthesis [Figure 1 and Table 2].¹⁷,¹⁹,²⁰,²¹,²²,²³,²⁴,²⁵,²⁶,²⁷,²⁸,²⁹,³⁰,³¹,³²

Table 2.

Functional outcome and complications of fibular osteosynthesis in neglected and nonunion of femoral neck fracture

Complications

Apart from nonunion and osteonecrosis, most common complications after fibular osteosynthesis are coxa vara deformity, limb shortening, and intraarticular penetration of the graft or hardware.¹⁷,¹⁹,²¹,²²,²³,²⁴,²⁵,²⁶,²⁷,²⁸,²⁹,³⁰,³¹,³² Very few cases of graft fracture and slippage have been reported.²⁰,²³,²⁴,²⁵,²⁶,²⁷,²⁸,³² Contrary to it, donor site morbidity has not been reported so commonly. Few articles have reported mild ankle pain, transient loss of toe flexors and extensors, and transient lateral popliteal nerve palsy [Table 2].²¹,²⁶,²⁹

DISCUSSION

Fibular osteosynthesis in neglected femoral neck fracture was popularized by Nagi et al.¹⁷ They used one cancellous screw and a fibular graft in their patients and reported union in all of them. They acknowledge that fibular osteosynthesis not only promotes union, it also improves the osteonecrosis in the femoral head. They advocated that mechanical fixation by various devices depends upon the physical pressure exerted by the nail and the bone. Normal vascular bones start resorption around the implant because of the physical load and hence it starts loosening leading to nonunion. However, the fibular graft provides biological fixation by beginning to fuse with the parent bone at the end of 3–4 weeks and thus implant loosening does not occur.

The hip salvage concept in nonunion or neglected cases of fracture neck femur is of two types: (1) Techniques to improve the mechanical environment around the fracture site and (2) techniques to improve the biological environment at the nonunion site by bone grafting.³,⁴,³³,³⁴ The exact indication of fibular graft in the nonunion or neglected condition has not been elucidated. From the review, we conclude that NVFG is a suitable option for displaced/nondisplaced femoral neck fracture nonunion with a proximal fragment of size larger than 2.5 cm with or without femoral neck resorption and osteonecrosis.³,⁴,¹⁰,¹¹,¹²,¹³,²¹,²²,²³,²⁴,²⁵,²⁶,²⁷,²⁸,²⁹,³⁰,³¹,³² A concomitant proximal femoral valgus osteotomy with fibular graft may be indicated in femoral neck fracture nonunion with varus hip.¹⁰,¹¹

Fibula being cortical bone provides mechanical strength to the fixation besides stimulating union. The incorporation of fibular graft with the surrounding bone gives biological fixation. Once the graft is revascularized, the osteoblasts stimulated by bone morphogenic protein replace the resorbed bone of the femoral neck and subchondral region. If this bone is appropriately stressed, the graft acquires sufficient strength to handle the observed forces.³,⁴,¹⁰,¹¹,¹²,¹³,¹⁷

From this review, it is quite evident that “one fibular graft and two cancellous screws” are optimal for fixation of neglected and nonunion cases. An early rehabilitation with crutch walking can be initiated immediately after surgery and complete weight bearing can be restricted till union at the fracture site. The success rate of NVFG is impressive with nonunion rate <10%. Besides that, there is usually an improvement in osteonecrosis in about 50% patients. There are few complications and minimal donor site morbidity after autogenous NVFG fixation. The coxa vara deformity and leg length discrepancy that have been reported after NVFG is because of preoperative varus alignment/varus malreduction during surgery. Even in varus hip, fibular graft osteosynthesis promotes union; however, residual coxa vara and limb shortening persists. In such cases, combined valgus osteotomy and fibular graft can provide a better outcome.

To conclude, in patients younger than 60 years of age with neglected femoral neck fracture or nonunion, all efforts should be directed toward hip salvage. NVFG osteosynthesis has encouraging results in such instances. It is technically less demanding, simple, and can be performed in almost all centers where image intensifier is available.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.