Keywords

1 Aim of Surgery

The aim of hip fracture surgery is to allow immediate mobilization with full weight-bearing, aiming to achieve the previous level of function, ranging from maintaining normal walking in self-reliant elderly patients to pain relief in chronic bedridden nursing home residents. Three in four patients are expected to live beyond the first post-operative year, so proper surgery is required to alleviate an otherwise long-standing suboptimal functional level. Surgery is technically challenging, with body weight transfer through a broken oblique column, often with reduced bone quality due to osteoporosis—thus the risk of reoperation is high. A poorly operated hip fracture often leads to unequal leg length, pain and irreversible mobility loss, greatly influencing the quality of life.

2 Fracture Types

Hip fractures are divided into different types by the use of classification systems. A fracture classification should ideally have a high degree of reliability and reproducibility, be generally accepted, and have a prognostic validity in the clinical situation.

Historically, several classification systems have been proposed, but the following are the most commonly used in the literature. Hip fracture classifications are based on radiographic fracture patterns, while previous hip surgery, arthritis, cancer, dysplasia, bone quality, soft tissue and pain are normally not taken into account.

Hip fractures cover proximal femoral fractures predominantly located up to 5 cm distal to the lesser trochanter and are classified by fracture anatomy on plain radiographs (Fig. 9.1), if necessary supplemented by CT or MRI [1].

Fig. 9.1
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Antero-posterior radiograph of the right side proximal femur showing the anatomy and fracture positions. FNF femoral neck fracture, TF trochanteric fracture, Sub-TF sub-trochanteric fracture, LFW lateral femoral wall

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The hip joint capsule divides fractures into two main categories with an almost equal patient distribution: (1) Intra-capsular femoral neck fractures and (2) extra-capsular basicervical, trochanteric and sub-trochanteric fractures.

2.1 Intra-capsular Fracture Types

In a fragility fracture context, intra-capsular hip fractures are in fact through the femoral neck, as femoral head fractures are uncommon in the elderly.

Femoral neck fractures are at risk of non-union with/without mechanical collapse due to insufficient fixation and/or avascular necrosis of the femoral head. In adults, the femoral head is primarily supplied by the distal recurrent vessels entering the femur on the shaft side of the fracture. Avascular necrosis is caused by ischaemia hypothetically due to either a direct trauma to the arterial supply crossing the fracture-line or by a temporary arterial impingement, caused by vessel stretching or intra-capsular hematoma. Preoperative scintigraphy, electrode measurement and arthroscopic visualization of ischaemia have been tested but lack prognostic value. Since ischaemia could be temporary, acute reposition within hours (may be supplemented by hematoma emptying) has been suggested [2, 3].

Femoral neck fracture classification has historically been contentious with several different systems, primarily based on fracture displacement seen in the anterior–posterior radiographs. Garden’s Classification (Fig. 9.2) has in the last half a century been the most widespread. Fractures are divided into four stages based on fracture displacement [4]. Garden’s classification has only fair inter-observer reliability when using all four stages, but moderate to substantial if dichotomized into just undisplaced (Garden I–II) or displaced (Garden III–IV) fractures [5].

Fig. 9.2
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Garden’s classification. (Reproduced with permission and copyright © of the British Editorial Society of Bone and Joint Surgery)

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In addition, a vertical fracture line in the anterior–posterior radiograph or posterior wall multi-fragmentation, femoral head size and posterior tilt angulation seen in the lateral radiograph are believed to influence outcome [6,7,8,9]. However, the dualism of undisplaced versus displaced (with reference to Gardens stages I–II vs. III–IV) remains the most consistent predictor of failure and the most widespread fracture classification, with respectively around one-third and two-third of femoral neck fractures [10, 11].

2.2 Extra-capsular Fracture Types

Extra-capsular fractures are at risk of mechanical collapse and non-union due to insufficient fixation. The fracture line is anatomically located laterally to the nutrient vessels to the femoral head, so avascular necrosis is rarely seen, but muscle attachments often dislocate the fragments and bleeding into surrounding muscles can be severe and life-threatening. Classification systems are primarily based on fracture-line location and number of fragments.

Basicervical fractures are a few percent of borderline cases between the intra- and extra-capsular fractures, anatomically positioned on the capsular attachment line. The AO/OTA classification describes them as intra-capsular, but biomechanically they behave like the extra-capsular fractures [12]—except for the risk of rotation of the medial segment due to lack of muscle attachments.

Trochanteric fractures cover the trochanteric area from the capsule until just below the lesser trochanter. The often-used unnecessary prefixes per-, inter- and trans- are undefined, confusing and unhelpful for classification.

The AO/OTA Classification (Fig. 9.3) from 1987 is nowadays the most widespread. It divides the 31-A trochanteric area into nine types by severity (1-2-3, each subtyped.1-.2-.3) [13].

Fig. 9.3
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AO/OTA Classification for trochanteric fractures (Reproduced with permission from J Orthop Trauma)

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Fracture type 31-A1 covers the simple two-part fractures, while 31-A2 demands a detached lesser trochanter, with an intact (31-A2.1) or a detached greater trochanter (31-A2.2-3). 31-A3 covers fracture lines through the lateral femoral wall—defined as the lateral cortex distal to the greater trochanter—in which the subgroup 31-A3.1 represents the reverse fracture and 31-A3.2 the transversal, while the most comminuted 31-A3.3 fracture demands both a fractured lateral femoral wall and a detached lesser trochanter.

The AO/OTA classification covers most fractures within previous classification systems, except the few trochanteric fractures with a detached greater trochanter and an intact lesser trochanter. The reliability when using all nine types is poor, but increases to substantial if only classifying into the three main groups (A1-2-3) [14].

Subtrochanteric fractures are positioned distally to the trochanters, and constitute around 5% of all hip fractures. These have historically been classified by as many as 15 different systems, most often into the 8 types from 0 to 5 cm below the lesser trochanter by Seinsheimer or the 15 types from 0 to 3 cm in the AO/OTA classification for femoral shaft fractures, the type 32ABC(1-3).1 sub-division. A review doubts the value of such division and proposes simplicity into: (1) a stable two-part and unstable, (2) three-part and (3) more comminuted fractures from 0 to 5 cm below the lessor trochanter, without involvement of the trochanters. It however still has to be established whether this easier classification is useful and necessary for decision-making and prognosis [13, 15, 16].

3 Implants

There are two major strategies for treating hip fractures, prosthesis or osteosynthesis. A prosthesis involves removing the fracture site, and replacing the femoral head with a hemi-arthroplasty or total hip arthroplasty, the latter also including an acetabular cup. An osteosynthesis involves reducing bone fragments to an acceptable position and retaining them until healing—usually with parallel implants, sliding hip screw or intramedullary nail (Fig. 9.4).

Fig. 9.4
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The main implant groups for hip fracture surgery

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Prostheses are inserted with the patient supine or lateral depending on the surgical approach, while osteosynthesis is always performed through one or more lateral approaches, with the patient supine on a traction table and the use of a radiographic image-intensifier. There are pros and cons for all implants, but all are dependent on proper use, which is why well-defined implant position measurements are needed for optimal evaluation of one implant against another.

Parallel implants are inserted with limited operative bleeding and soft tissue damage through a few lateral stab incisions or a single <5 cm incision. In spite of many clinical and cadaver studies, choice (screws/hookpins) and number (2/3/4) of implants lack consensus [17]. Parallel implants permit fracture compression and they should be inserted as vertically as possible and in different head quadrants. Furthermore, the posterior implant should have posterior cortex contact and the inferior implant calcar contact to achieve three-point fixation that best supports weight transfer from (1) the subchondral bone to (2) a calcar seat and (3) a lateral femoral cortex counterpoint [18]. The main reasons for failure are non-union, with or without mechanical collapse, due to insufficient fixation and/or avascular necrosis. Also, a femoral neck shortened heling position is associated with poor functional outcome [19]. Salvage normally necessitates a hip prosthesis or, depending on the patient’s demand, a simple removal of the femoral head. A new fall can result in fractures around the parallel implants, which should be reoperated with a sliding hip screw or an intramedullary nail.

Sliding hip screws have been the Gold Standard for treating trochanteric fractures for several decades—but have recently also gained ground for femoral neck fractures [17]. After reduction, the femoral head fragment is held by a large diameter screw, which can slide inside an approximately 135° angle plate attached laterally to the femoral shaft. The implant is inserted under the lateral vastus muscle through a single lateral approach, around 10 cm long depending on chosen plate length.

To reduce the risk of cut-out of the screw into the hip joint, it should be positioned centrally or central-inferiorly in the femoral neck with the tip attached subchondrally in the femoral head, providing a short so-called tip-apex distance [20]. Beyond cut-out, the common reasons for failure are mechanical collapse, with or without non-union and a distal peri-implant fracture. Depending on femoral head bone status, salvage can be an intramedullary nail or a distally seated hip prosthesis.

Intramedullary nails have, during the last decade, outnumbered sliding hip screws as treatment for trochanteric fractures [21]. After reduction, the femoral head fragment is held by a large diameter screw, which can slide at an angle of approximately 130° through an intramedullary nail with 1–2 distal locking screws. The nail is inserted at the greater trochanter tip, through a 5-cm lateral incision, with the sliding and locking screw(s) inserted by use of a guide through stab incisions in the lateral vastus muscle. A central-inferior position in the femoral head and a short tip–apex distance for the threaded types is important, while the new bladed types might need more distance [22, 23].

Some old nails had a reputation for risking a shaft fracture, but newer nails have moved beyond this, although the many new smaller designs, with different screw, blade, sleeve, locking and anti-rotation mechanisms, lack convincing clinical evidence so far [24, 25].

Reasons for failure are the same as for the sliding hip screws, and salvage can be a distally seated hip prosthesis for bone collapse. In case of a distal peri-implant fracture, a longer nail or a condylar plate can be used, depending on the nail length.

Prostheses involve a metal femoral head replacement attached by a stem seated in the shaft cavity. To fit individual patients’ anatomy, implants are modular and assembled during surgery; thus mono-blocks are no longer recommended [26]. Reoperations are primarily caused by repeated dislocations or by a peri-prosthetic fracture (produced during insertion or subsequent to a new fall). For dislocations, closed reduction is the norm, but reposition or modification with a low-range-of-motion constrained liner is necessary in recurrent cases. Peri-prosthetic fractures are treated with circumferential wires and/or a plate, and a loose prosthesis is changed or removed depending on the patient’s demands.

Hemi-arthroplasties (HA) traditionally have reduced dislocation rate, shorter operating time and less blood loss than a total hip arthroplasty. Reports of acetabular chondral erosion, following unipolar HA, have encouraged bipolar heads with an additional ball joint—their efficiency is, however, still debated [27,28,29].

Total Hip Arthroplasties (THA) also replace the acetabular cartilage, theoretically a source of pain and thus reduced functional ability. THAs might provide a better result than HAs in active, independent living, and cognitively intact patients, but more studies are warranted [28, 30,31,32,33]. Despite the higher implant price, the total cost of using THA could be lower when taking complications and function into account, in the healthiest patients [34]. THAs, however, have an increased dislocation risk [28, 30, 31, 35], which might be reduced by the technically demanding new dual-mobility type [36,37,38].

Beyond optimal implant positioning, the dislocation rate following both HA and THA might be reduced to 1–3% of patients if using the antero-lateral approach, compared to 4–14% if using the postero-lateral approach, although the latter can probably be improved by an optimal capsular and muscle repair [39,40,41]. The only randomized study, however, found no difference in dislocation rate between the two methods [42], and a register study found that the consequences of surgical approach for soft tissue, pain and mobility might be minimal [43]. It may be that dual-mobility cups can justify the continued use of the postero-lateral approach [36,37,38].

Cementation is associated with more dislocations in some studies but less in others. Cementation seems to improve patient mobility, reduce pain and the rate of peri-prosthetic fractures (1–7% for uncemented prostheses), although only a few studies include the newer hydroxyapatite-coated surfaces. Cementation probably increases risk of air embolism, blood loss and operation time, but registries have shown that a higher acute mortality appears to equilibrate after a couple of months [2, 28, 29, 44,45,46].

4 Surgical Management

Patients should receive their operation as soon as possible, because the negative impact on body functions, while waiting for surgery, appears to be significant. Surgery on the day of, or the day after admission (less than 36 h) is recommended, although studies to prove this are difficult, because stratification by comorbidities is challenging [47,48,49,50,51].

Surgical drains [52], and pre-operative traction is no longer recommended [53]. Conservative treatment should be avoided in modern healthcare systems [54], except in the case of few terminally ill patients who can be kept pain-free by analgesics in their last few days of life.

Patients sustaining a metastatic fracture should be identified, the cancer investigated and the proximal femur fixed in a way that takes into account the growing cancer, normally by use of a long nail or a distally seated THA.

Prophylactic antibiotic treatment should be given. Deep infection is rare (Table 9.1), but potentially devastating, often with several procedures and implant removal. While treating the infection, an external fixator can be used to keep extra-capsular fractures reduced. Predictors of infections are primarily the surgeon’s experience and the operation duration [55, 56].

Table 9.1 Overall rates of surgical complications
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4.1 Intra-capsular Operations

The overall choice stands between (1) femoral head removal and insertion of a prosthesis, or (2) femoral head preservation by internal fixation, wherein the main overall predictor for failure is initial fracture displacement [3]. However, patient age, co-morbidity, mobility demands and so on should also be taken into account in the choice of implant. Patients should be asked about pre-fracture hip pain and a THA is chosen if hip arthritis coexists.

Undisplaced femoral neck fractures may be complicated by non-union, with or without fracture collapse and, after a minimum of 3–6 months, radiographically evident avascular necrosis of the femoral head (Table 9.1). Around three-quarters of the undisplaced fractures are treated with parallel screws or pins, which appears to be adequate [3, 17]. The sliding hip screw is comparable and enables a more stable fixation due to the fixed angle attachment when three-point fixation is unachievable due to a vertical and/or basal fracture line—but necessitates a larger incision. Also, posterior tilt might increase the reoperation rate [7, 8], suggesting that this may be an indication for prosthesis, rather than osteosynthesis.

Displaced femoral neck fractures are followed by the same complications after internal fixation as the undisplaced—but at a higher rate (Table 9.1).

If using internal fixation, the fracture must be anatomically reduced within a short time and the implants optimally positioned. Prostheses are now the most common treatment for displaced fractures, with improved results (Table 9.1) varying with the approach, cementation and THA/HA [2, 17, 18, 21, 44, 45, 57, 58].

A large number of studies report a significantly lower reoperation rate following a prosthetic replacement. Newer studies also find less pain, better hip function and higher patient satisfaction after a prosthesis. However, this is at the expense of a greater primary operation (operating time, soft tissue damage, blood loss and impact on body functions) resulting in a higher immediate mortality. Fortunately, this appears to equilibrate later [2, 29, 57,58,59].

Using internal fixation for all displaced fractures, with the insertion of a prosthesis later if required, is not recommended as a salvage prosthesis insertion has a much higher complication risk than a primary. Prostheses, however, have a shorter lifetime in mobile young patients who might outlive their prosthesis once or more. It has therefore been suggested to use an internal fixation in the younger patients, THA in active patients aged around 65–80 years and HA in the oldest. [2, 29, 35, 60].

The subgroup of demented patients might benefit more from internal fixation—their functional scores are generally low—but the literature is so far limited [61, 62]. Osteosynthesis in most fragile patients, who are demented or have a high risk of dying on the operation table, should however be used with caution, as the fixation often turns out to be inadequate and painful in the short term—requiring a reoperation—if the patients live longer than expected. In a few selected bedridden, oldest patients, a simple removal of the femoral head can be chosen as the primary procedure to reduce fracture pain and eliminate complications.

4.2 Extra-capsular Operations

Basicervical fractures are treated with a sliding hip screw, attached to a short lateral plate. Parallel implants are insufficient because of the lack of implant support by the calcar bone area [12].

Trochanteric fractures may be complicated by a non-union or mechanical collapse in 1–10% of patients. The pull of muscles often displaces fragments, while a near-anatomical reduction is necessary for the majority of weight to pass through the bone. Use of retractors and/or a posterior-reduction device on the fracture table is recommended to prevent sagging of the fracture.

During the early post-operative months, an inadequate reduction and implant position may lead to femoral shaft medialization and femoral head varus position with risk of a screw cut-out, pain and a shortened femoral neck- and leg-length. The overall rate of reoperation is 2–10%. [25, 63,64,65]. A salvage prosthesis can be inserted primarily, but this is challenging due to the damaged bone stock.

The choice of implant is between the sliding hip screw and an intramedullary nail but, after many cohort studies and more than 40 RCTs since the past three decades, the comparison remains inconclusive overall. The current status appears to be that, although the sliding hip screw remains the recommended implant, nails might have an advantage on mobility or in the more unstable trochanteric fracture [24, 66, 67]. The Norwegian national registry reported fewer reoperations after sliding hip screws in 7643 stable (AO/OTA type 31A1) and after nails in 2716 unstable trochanteric fractures (AO/OTA type 31A3) [64, 65]. However, a systematic review of the six RCTs on a total of 265 patients with AO/OTA type A3 fractures found comparable fracture healing complication rates for sliding hip screws and intramedullary nails—and more RCTs on fracture subgroups are warranted [68].

Often lateralization and femoral neck shortening are seen following the unstable trochanteric fractures, probably due to a lack of a buttress from the lateral femoral wall. A trochanteric buttress shield might prevent lateralization, but the evidence is not convincing and the method demands a much larger incision than simply inserting the well-known intramedullary femoral nail. The sliding hip screw might be insufficient for fractures with a detached greater trochanter (AO/OTA type A2.2 and A2.3) as the resulting thin lateral femoral wall is at risk of per-operative fracture. The integrity of the lesser trochanter does not seem to influence outcome, and unstable trochanteric fractures should probably thus be defined by a detached greater trochanter or a lateral femoral wall fracture (AO/OTA type 31A.2.2-2.3 + A3) [69, 70].

So far knowledge is limited on whether the use of the longest possible nail can reduce risk of later shaft-fractures, although femoral shaft bending, entry-point and distal locking appears more challenging in long nails [71].

Sub-trochanteric fractures are nowadays most often treated with a long nail, which is probably beneficial with reoperation rates declining by 5–15%. Most literature, however, also included the AO/OTA 31A3 fractures, due to difficulties of differentiation and more knowledge is needed. Circumferential wires can be added for keeping the oblique and comminuted fractures reduced with a low risk of bone-necrosis [15, 72].

5 Surgical Algorithms and National Guidelines

As indicated earlier, the published evidence in the last decades has created a degree of consensus for the surgical treatment of hip fractures. In everyday clinical practice, the exact choice of implant however often remains uncertain, and an easily used surgical algorithm for all hip fracture patients might be warranted.

Younger, less experienced surgeons probably feel more confident when guided by a strict algorithm, while older surgeons could feel that their individual right of choice is being restricted. It is, however, important to underline that a treatment algorithm does not negate the individual surgeon’s responsibility for the individual patient. A surgeon still has the right and duty, now and then, to defy a guideline due to individual circumstances, but the decision to do so should be justified in the patient record.

Creating an algorithm that embraces the heterogeneous group of hip fracture patients is challenging, and the balance between detail and usability must be considered. Many published articles recommend treatment for some aspects, but only a few authors have published comprehensive decision-tree algorithms for hip fracture surgery—among which the simple, exhaustive and exclusive Copenhagen Algorithm (Fig. 9.5) appears to be the best scientifically evaluated [9, 73].

Fig. 9.5
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An algorithm for hip fracture surgery (Reproduced with permission from Acta Orthop)

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National guidelines including surgery have emerged in Australia, New Zealand, United States and most European countries during the last decades. Consensus is widespread for some overall recommendations based on the same evidence.

Among the intra-capsular fractures, all recommend internal fixation for undisplaced femoral neck fractures and to some extent prosthetic replacement for the displaced in elderly patients. Among the extra-capsular fractures, the sliding hip screw is recommended for the stable (often defined as AO/OTA type A1) while a nail is recommended for the unstable fractures (often defined as AO/OTA type A3 and further distal). The purpose of national guidelines is to recommend evidence-based surgical treatment for improving outcome. National hip fracture registries have gained ground, especially in the last decades, to enable continued evaluation of treatment quality and the identification of positive and negative outliers. [10, 73, 74].

The multidisciplinary global fragility fracture network has now the strategic focus of facilitating national (or regional) consensus guidelines including quality standards and systematic performance measurement—and offers an easily used minimum data set for hip fracture audit [74]. Hopefully, such knowledge dissemination not only helps to overcome barriers to implementation, but also to globally spread evidence-based national guidelines, standards and registries for improving the surgical quality.