Femoral neck targeting is the process of calculating the centre of the

femoral neck The femoral neck (also femur neck or neck of the femur) is a flattened pyramidal process of bone, connecting the femoral head with the femoral shaft, and forming with the latter a wide angle opening medialward. Structure The neck is flattene ...

during

hip resurfacing Hip resurfacing is a surgical alternative to total hip replacement (THR). The procedure consists of placing a cap (usually made of cobalt-chrome metal), which is hollow and shaped similarly to the cap of a mushroom, over the head of the femur whi ...

surgery. This can be done by hand or using electronic aides. __TOC__

Early implant failure

Studies on metal-on-metal (MoM) hip resurfacings have identified several factors contributing to early implant failure. Key among these are: # Incorrect alignment of the implant stem relative to the

axis. # Notching of the femoral neck during the preparation of the

femoral head The femoral head (femur head or head of the femur) is the highest part of the thigh bone (femur The femur (; : femurs or femora ), or thigh bone is the only long bone, bone in the thigh — the region of the lower limb between the hip and the ...

. # Exposure of

cancellous bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, an ...

following implantation.CT-based and fluoroscopy-based navigation for cup implantation in total hip arthroplasty (THA). In hip resurfacing surgery, accurately identifying the true centre of the femoral neck in both antero-posterior (AP) and lateral planes is crucial.OPN, 2008, June issue, Open debate This reference point is essential for the precise positioning of the femoral neck. Failure to correctly position the femoral component can lead to early implant failure.

Methods of femoral neck targeting

There are many methods surgeons use to calculate the true centre of the femoral neck. Today the methods broadly fall under two categories: # Navigational - which can be performed using

computer tomography A computed tomography scan (CT scan), formerly called computed axial tomography scan (CAT scan), is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers or ...

(CT) or

fluoroscopy Fluoroscopy (), informally referred to as "fluoro", is an imaging technique that uses X-rays to obtain real-time moving images of the interior of an object. In its primary application of medical imaging, a fluoroscope () allows a surgeon to see t ...

(X-ray). # By hand - using various alignment guides/ reference devices/ targeting devices to calculate the true centre of the femoral neck. The navigational systems were created to be an accurate means for surgeons to implant components with as much accuracy as possible. Studies have shown that this is largely true, but navigational systems are a very different means of femoral neck targeting, and require a steep

learning curve A learning curve is a graphical representation of the relationship between how proficient people are at a task and the amount of experience they have. Proficiency (measured on the vertical axis) usually increases with increased experience (the ...

. Below is a comparative analysis of both types of navigational targeting against traditional targeting techniques. A computer-assisted device to calculate the true centre of the femoral neck, without the above disadvantages, has not yet been created. The main issues with the current navigational systems are the levels of extra apparatus required in the

operating theatre An operating theater (also known as an Operating Room (OR), operating suite, operation suite, or Operation Theatre (OT)) is a facility within a hospital where surgical operations are carried out in an aseptic environment. Historically, the ter ...

. In the case of

, a "C-arm"

X-ray machine An X-ray machine is a device that uses X-rays for a variety of applications including medicine, X-ray fluorescence, electronic assembly inspection, and measurement of material thickness in manufacturing operations. In medical applications, X-ra ...

is used, which is a very large piece of apparatus. In the case of CT-based navigation,

computer software Software consists of computer programs that instruct the Execution (computing), execution of a computer. Software also includes design documents and specifications. The history of software is closely tied to the development of digital comput ...

and training in the use of such software is required, which again adds more apparatus to the

operating room Operation or Operations may refer to: Arts, entertainment and media * ''Operation'' (game), a battery-operated board game that challenges dexterity * Operation (music), a term used in musical set theory * ''Operations'' (magazine), Multi-Man ...

. The popularity of CT and fluoroscopy-based navigation amongst surgeons has been increasing in recent years. The application of these techniques however has been proven to be best suited for different types of surgery. Fluoroscopy-based methods are easier to handle in routine cases with normal

anatomy Anatomy () is the branch of morphology concerned with the study of the internal structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old scien ...

, or cases with lesser deformities. On the other hand, CT-scanning techniques have been better suited to cases of

congenital A birth defect is an abnormal condition that is present at childbirth, birth, regardless of its cause. Birth defects may result in disability, disabilities that may be physical disability, physical, intellectual disability, intellectual, or dev ...

and post-traumatic deformities. It is less suited to routine cases, due to the time-consuming pre-operative procedures e.g. setting up CT-scan, data transfer, planning. The conventional "by hand" calculations, however are much more popular overall. Most

operative techniques come with some form of guide instrumentation to find the true centre of the femoral neck. These conventional kits will most likely be the instruments that the surgeon will use first, and perhaps become accustomed to. The two most important factors though are # Conventional instrumentation is relatively more popular because it is small and hand-held, without the need for large pieces of apparatus. # They are relatively cheaper to buy. All things considered, computer-assisted technology has allowed surgeons to provide accurate femoral neck targeting, and is a viable option for this imperative step to hip resurfacing. It could be argued that the results of the Adept medial reference jig, first used in 2004 has overcome all of these difficulties; (1) the complete absence of femoral head notching, (2) the complete absence of femoral neck fractures and (3) the outstanding long term results. Likewise, the acetabular introducer has allowed surgeons to implant the socket so much more accurately (as well as being able to check the socket orientation so much more thoroughly) than was ever possible in a BHR; viz; National Joint Registry. Implant Summary Report for the ADEPT® Hip Resurfacing (Sizes 48-58 only). November 2018. Ref: Summary.Report.HP_Head_Adept Resurfacing Head (Sizes 48 - 58 only)_All.22/11/2018.22:08

References

{{DEFAULTSORT:Femoral Neck Targeting Orthopedic surgical procedures