Franck Mabesoone
Department of Orthopaedics and Traumatology,
Hôpital Pitié-Salpétrière- F-75013 Paris, France

INTRODUCTION

Over the past 50 years, much has been published on the different methods for the fixation of trochanteric fractures. In order to appreciate the results, one needs to understand the fracture patterns involved. Many classification systems have been devised; however, since each has had a different object, none has been unanimously adopted by the orthopaedic community. Some of the systems proposed have confined themselves to a simple anatomical description of the patterns observed (Evans; Ramadier; Decoulx and Lavarde). Other, more recent, systems were designed to provide prognostic information on the prospect of achieving and maintaining reduction of the different types of fractures (Tronzo; Ender; Jensen's modification of the Evans grading; Müller et al.).

In present-day surgical practice, it is important to know whether a fracture is stable or unstable: The answer to this question will guide the reduction technique, the type of fixation to be used, and the postoperative management. A good classification must provide information on the fracture's potential of being anatomically reduced, with good apposition of the fragments. Also, it should be possible to tell, in the light of the classification, whether a particular fracture is likely to become secondarily displaced after fixation; this information must be available before the patient is allowed to weight-bear. This new approach has made it possible to develop fixation hardware whose design takes account of the biomechanical properties of fractures, in order to arrive at more dynamic modes of fixation. Finally, any classification system that aspires to universal adoption must be easy to use and reproducible; only if these criteria are met can it facilitate communication among surgeons.

After the first papers showing the superiority of the surgical treatment of trochanteric fractures over other management modalities, attempts were made to classify the different fracture types in the light of the various authors' first experience with internal fixation. A review of the literature shows many proposed classification systems (see Table above). Some of these will discussed in greater detail in this review article, either because they are widely used, or because they provide important anatomical or biomechanical information.

THE EVANS CLASSIFICATION
(Fig. 1)

Figure 1 Evans' classification
Type I: Undisplaced 2-fragment fracture
Type II: Displaced 2-fragment fracture
Type III: 3-fragment fracture without posterolateral support, owing to displacement of greater trochanter fragment
Type IV: 3-fragment fracture without medial support, owing to displaced lesser trochanter or femoral arch fragment
Type V: 4-fragment fracture without posterolateral and medial support (combination of Type III and Type IV)
R: Reversed obliquity fracture

As early as 1949, EM Evans devised a classification system that had the twin merits of reproducibility and ease of use. It has been widely used in the English-speaking countries. In this system, fractures of the trochanteric region are subdivided into five types. The first two types are two-fragment fractures, with a fracture line running parallel to the intertrochanteric line, without separation of the trochanters. The fractures may be undisplaced (Type I) or displaced (Type II). Type III is a three-fragment fracture, without posterolateral support owing to displacement of the greater trochanter. Type IV also has three fragments; however, in this type, there is no medial support, because of displacement of the lesser trochanter or fracture of the medial arch. In the four-fragment fracture (Type V), there is neither medial nor posterolateral support, since the comminution involves the greater and the lesser trochanter.

Evans also described a fracture with a subtrochanteric fracture line that runs obliquely upwards and inwards; he called this pattern a reversed obliquity fracture. The mechanical properties of this pattern are worth noting: Reversed obliquity fractures are inherently unstable. The femoral shaft tends to displace medially by the downward and outward sliding of the greater trochanter; fixation, especially by sliding screws, is incapable of controlling this displacement.

The modified grading proposed by Jensen and Michaelson in 1975 was intended to improve the predictive value of the Evans system, to indicate which fractures could be reduced anatomically and which were at risk for secondary displacement after fixation. An analysis, published in 1980, of the reduction of fractures in 234 patients managed with sliding screw-plate internal fixation made it possible for the number of patterns to be reduced to three, the criterion being reducibility. Class I includes two-fragment fractures, which are considered stable. A study of this pattern shows that such fractures may readily be reduced in the coronal and the sagittal plane. Class II contains Evans Type III and Type IV fractures, which are difficult to reduce in either the coronal or the sagittal plane; while Class III (Evans Type V) consists of very unstable fractures, which are difficult to reduce in both planes. In the light of a comparison with four other grading systems, the authors showed that this modified Evans system had the best predictive value regarding the reduction potential, and would, therefore, also indicate the likely risk of secondary displacement of the different fractures.

THE RAMADIER CLASSIFICATION
(Fig. 2)

Figure 2 Ramadier's classification
a: Cervico-trochanteric fractures
b: Simple pertrochanteric fractures
c: Complex pertrochanteric fractures
d: Pertrochanteric fractures with valgus displacement
e: Pertrochanteric fractures with an intertrochanteric fracture line
f: Trochantero-diaphyseal fractures
g: Subtrochanteric fractures

Decoulx and Lavarde's classification (1969)
Cervico-trochanteric fractures (a)
Pertrochanteric fractures (b,c,d)
Subtrochanteric fractures (e)
Subtrochantero-diaphyseal fractures (f)

In 1956, Ramadier established a grading system that came to be widely used in France. He described four basic patterns, under four main headings, as a function of the fracture line. He recognized cervico-trochanteric fractures (a), with a fracture line at the base of the femoral neck. According to Ramadier and Bombard, these fractures account for 27% of all the fractures in the trochanteric region. The fractures are usually impacted, and the displacement of the fragments produces a coxa vara deformity and internal rotation. Simple pertrochanteric fractures (b) account for 24% of trochanteric fractures; they have a fracture line that runs parallel to the intertrochanteric line; frequently, the lesser trochanter is broken off. The greater trochanter is not, or only marginally, involved. Complex pertrochanteric fractures (c), which account for 31% of all fractures in the region, have an additional fracture line that separates most of the greater trochanter from the femoral shaft; the lesser trochanter is often fractured. There will be a greater or lesser amount of displacement. Ramadier described two infrequently encountered patterns: Pertrochanteric fractures impacted in a valgus displacement (d), with a fracture line that begins on the greater trochanter and finishes below the lesser trochanter; and low pertrochanteric fractures (e). Trochantero-diaphyseal fractures (f), which make up 10% of all fractures in the region, have a fracture line that follows a spiral line through the greater trochanter and into the proximal shaft. Often, the pattern contains a third fragment; there may be major displacement. Subtrochanteric fractures (g) have a more or less horizontal fracture line that runs below the two trochanters. Displacement may be substantial: The proximal fragment is put into flexion by the action of the iliopsoas, and the shaft fragment tends to drop backwards.

Decoulx and Lavarde (1969) enhanced the above system by the addition of a further pattern that had previously been described by Ehalt - a trochanteric fracture with a more distal fracture line, which is slightly concave proximally and which crosses the intertrochanteric line just above the lesser trochanter. They called this pattern an intertrochanteric fracture, and made it part of a five-grade classification: cervico-trochanteric fractures; pertrochanteric fractures; intertrochanteric fractures; subtrochantero-diaphyseal fractures; and subtrochanteric fractures (Fig. 2).

THE BRIOT CLASSIFICATION
(Fig. 3)

Figure 3 Briot's grading of diaphyseo-trochanteric fractures
A Evans' reversed obliquity fracture
B "Basque roof" fractures
C Boyd's "steeple" fracture
D Fractures with an additional fracture line ascending to the intertrochanteric line
E Fractures with additional fracture lines radiating through the greater trochanter

In 1980, Briot tried to simplify the Ramadier system and to introduce biomechanical concepts. He merged the cervico-trochanteric and the pertrochanteric fractures. In his opinion, a fracture at the base of the neck, with a line running parallel to the intertrochanteric line and medial to the iliofemoral ligaments, was as difficult to fixate and reduce as were pertrochanteric fractures with a line lateral to these ligaments. To the previous system, Briot added fractures with an oblique line running upwards and inwards; however, by definition, he excluded subtrochanteric fractures, because they do not affect the trochanters, and because the mechanical problems involved in this pattern are totally different, even where these fractures are associated with undisplaced fractures of the greater trochanter or a detachment of the lesser trochanter. In this way, Briot established three well-defined patterns of trochanteric region fractures:

(1) pertrochanteric fractures with a fracture line running parallel to the intertrochanteric line, which may detach a posterior cortical fragment (this lesion will be discussed further below). Under the same heading, Briot considers pertrochantero-diaphyseal fractures with a downward and inward slanting line that continues distal to the lesser trochanter.

(2) the intertrochanteric fractures described by Decoulx;

(3) diaphyseo-trochanteric fractures (Fig. 3) with a fracture line running upwards and outwards that extends to, but not beyond, the intertrochanteric line. One pattern in this group would be Evans' reversed obliquity fracture; while the fracture line may also turn back and continue downwards along the intertrochanteric line, to produce the steeple-shaped pattern described by Boyd.


THE ENDER CLASSIFICATION
(Fig. 4)

Figure 4 Ender's classification
Trochanteric eversion fractures
-1 Simple fractures
-2 Fractures with a posterior fragment
-3 Fractures with lateral and proximal displacement
Trochanteric inversion fractures
-4 With a pointed proximal fragment spike
-5 With a rounded proximal fragment beak
-6 Intertrochanteric fractures
Subtrochanteric fractures
-7 and 7a Transverse or reversed obliquity fractures
-8 and 8a Spiral fractures

Some authors have adopted a more pragmatic approach: Instead of merely describing the patterns of trochanteric fractures, they have analysed the potential for achieving reduction potential and for the maintenance of reduction following fixation.

In 1970, HG Ender, in his description of a technique for condylocephalic nailing, gave a fracture grading system based upon the fracture mechanism. The first type is represented by eversion fractures, with an anterior opening of the fracture site (1), sometimes involving the separation of a posterior fragment (2). In this group, Ender described fractures with substantial lateral and posterior displacement of the distal fragment (3), which shows that major soft tissue damage has occurred, resulting in severe instability.

The second group consists of impaction (inversion and adduction) fractures ; typically, the distal medial beak of the neck fragment is impacted in the metaphysis (4 and 5).

The last two groups are intertrochanteric fractures (6) and subtrochanteric fractures (7 and 8).

Ender felt that a knowledge of the fracture mechanism was useful when it came to performing external reduction manoeuvres before doing closed nailing using his hardware. As a result, the Ender grading system has been applied only in conjunction with Ender's condylocephalic nailing system.

THE AO CLASSIFICATION
(Fig. 5)

Figure 5 AO classification
A1: Simple (2-fragment) pertrochanteric area fractures
A1.1 Fractures along the intertrochanteric line
A1.2 Fractures through the greater trochanter
A1.3 Fractures below the lesser trochanter
A2: Multifragmentary pertrochanteric fractures
A2.1 With one intermediate fragment (lesser trochanter detachment)
A2.2 With 2 intermediate fragments
A2.3 With more than 2 intermediate fragments
A3: Intertrochanteric fractures
A3.1 Simple, oblique
A3.2 Simple, transverse
A3.3 With a medial fragment

The AO classification, proposed by Müller et al. in 1980-1987, attempts to be descriptive and to provide prognostic information, in the light of what can be done with present-day fixation techniques. Type A fractures are fractures of the trochanteric area. These fractures are divided into three groups.

Group A1 contains the simple (two-fragment) pertrochanteric fractures whose fracture line runs from the greater trochanter to the medial cortex; this cortex is interrupted in only one place. There are three subgroups, reflecting the pattern of the medial fracture line: A1.1 fractures run above the lesser trochanter; A1.2 fractures have calcar impaction in the metaphysis; while A1.3 fractures are trochantero-diaphyseal fractures that finish up distal to the lesser trochanter.

The fractures in Group A2 have a fracture line pattern identical to that of Group A1 fractures; however, the medial cortex is comminuted. They are subdivided into A2.1 fractures, with one intermediate fragment; A2.2 fractures, with two fragments; and A2.3 fractures, with more than two intermediate fragments.

Group A3 fractures are characterized by a line that passes from the lateral femoral cortex below the greater trochanter to the proximal border of the lesser trochanter; often there is also an undisplaced fracture separating the greater trochanter. A3.1 fractures are reverse intertrochanteric fractures (with an oblique fracture line); while A3.2 fractures are transverse (intertrochanteric). A3.3 fractures involve the detachment of the lesser trochanter, and are notoriously difficult to reduce and stabilize.

SOURCES OF INSTABILITY

The mechanical rôle of the medial arch, and the implications of its failure in trochanteric fractures, have been stressed in a number of papers. In particular, Evans has drawn attention to medial arch compromise as a source of instability. His own Types IV and V are the most unstable patterns. If the calcar is involved, there will be instability in the coronal plane. There is less agreement on the extent to which stability is affected by lesser trochanter fractures.

Some authors think that medial stability is usually preserved if only the lesser trochanter is fractured, since the structure described as a "massive cancellous apophysis behind the calcar" does not have a major weight-bearing function.

In 1964, Ottolenghiin distinguished between intradigital fractures, whose fracture line is medial to the digital fossa of the greater trochanter, and extradigital fractures (Fig. 6).


Figure 6
Extradigital fracture line (Ottolenghi)
posterior opening
From above

The latter, whose line is more lateral than in the usual patterns, will leave all the rotator insertions on the proximal fragment. Displacement of the neck and trochanter fragment in external rotation will open up the fracture at the back; reduction must be achieved by external rotation of the shaft fragment.

The detachment of the posterior portion of the greater trochanter may also pose major problems. It has been held responsible for difficult reduction in the sagittal plane. Boyd and Griffin (1949) were the first to consider the instability of trochanteric fractures in the coronal as well as the sagittal plane. This concept was also embodied in the classification established by Tronzo in 1973. Among Tronzo's patterns, there are three involving an explosion of the posterior wall (Fig. 7):


Figure 7
Tronzo's classification
Posterior view
Type 3 | Type 3 Variant | Type 4
Fractures with posterior comminution

In the first, the neck spike is telescoped into the shaft fragment, and there is a large lesser trochanter fragment. In the second, the greater trochanter is also totally broken off; while, in the third, the neck spike is not telescoped into the shaft, but is displaced medial to the shaft. This grading system gives a good indication of the degree of instability of a given fracture, from lack of medial and/or posterior support. However, the system may be somewhat too complex for wider use.

Briot studied the way in which the posterior wall of the trochanteric region affects the stability of trochanteric fractures. Damage to the posterior wall is a major source of sagittal instability, and, in particular, external rotation. From cadaver studies, Briot found that the fracture may detach a posterior plate, situated between the lateral lip of the linea aspera and the spiral line, comprising the intertrochanteric crest and the lesser trochanter. This plate may be completely avulsed, sometimes with additional fractures lines; equally, it may be separated from the femur in its upper part (Fig. 8).


Figure 8
Briot's posterior plate fractures
Briot's posterior plate fractures

a Boundaries of posterior plate
b Maximum extent of plate
c Possible fracture lines

It is thought that this posterior comminution causes malunion in external rotation. Ender described this fracture, with detachment of a posterior fragment, among his Type 2 fractures in external rotation; however, he stressed the rôle of the soft tissue lesions in his Type 3 fractures.

CONCLUSION

The different classification systems devised to date for the grading of trochanteric fractures contain several points that are of importance in the analysis of radiographs of such fractures.

Stable two-fragment fractures, with a pertrochanteric or a paratrochanteric (basicervical) line, may be considered as one category, since their grading, reduction, and stabilization are straightforward.

Two factors must be considered in the assessment of stability: loss of medial support, as a result of a separation of the lesser trochanter in association with a fracture of the medial arch; and comminution of the posterior cortex, which is frequently associated with a separation of the greater trochanter. The fracture must be reduced in internal rotation, to close the anterior gap and to replace the posterior cortical fragments.

One fracture pattern warrants separate consideration - the reversed obliquity fracture described by Evans. This fracture is similar to subtrochanteric fractures, in that it is difficult to reduce and causes major instability.

This review does not attempt to draw up yet another classification. Such an attempt would not be very productive, since there is no such thing as a perfect system for the grading of trochanteric fractures. Any system to be used in traumatology needs to be simple, and precise enough to produce the same results when used by different observers, or by the same observers at different points in time . Equally, it must be go beyond a mere description, to provide predictive information regarding the stability potential of the various fracture patterns.

Evans' classification (1949)
Type I: Undisplaced 2-fragment fracture
Type II: Displaced 2-fragment fracture
Type III: 3-fragment fracture without posterolateral support
Type IV: 3-fragment fracture without medial support,
Type V: 4-fragment fracture without posterolateral and medial support
Reversed obliquity fracture
Boyd and Griffin's classification (1949)
Linear intertrochanteric line fractures
Intertrochanteric line fractures with comminution
Subtrochanteric fractures
Fractures of the trochanteric region and the proximal shaft
Ramadier's classification (1956)
(a) Cervico-trochanteric fractures
(b) Simple pertrochanteric fractures
(c) Complex pertrochanteric fractures
(d) Pertrochanteric fractures with valgus displacement
(e) Pertrochanteric fractures with an intertrochanteric fracture line
(f) Trochantero-diaphyseal fractures
(g) Subtrochanteric fractures
Decoulx & Lavarde's classification (1969)
Cervico-trochanteric fractures
Pertrochanteric fractures
Intertrochanteric fractures
Subtrochanteric fractures
Subtrochantero-diaphyseal fractures
Ender's classification (1970)
Trochanteric eversion fractures
Type 1: Simple fractures
Type 2: Fractures with a posterior fragment
Type 3: Fractures with lateral and proximal displacement
Trochanteric inversion fractures
Type 4: With a pointed proximal fragment spike
Type 5: With a rounded proximal fragment beak
Intertrochanteric fractures :Type 6
Subtrochanteric fractures
Types 7 and 7a: Transverse or reversed obliquity fractures
Types 8 and 8a: Spiral fractures
Tronzo's classification (1973)
Type 1: Incomplete fractures
Type 2: Uncomminuted fractures, with or without displacement; both trochanters fractured
Type 3: Comminuted fractures, large lesser trochanter fragment; posterior wall exploded; neck beak impacted in shaft
Type 3 Variant: As above, plus greater trochanter fractured off and separated
Type 4: Posterior wall exploded, neck spike displaced outside shaft
Type 5: reverse obliquity fracture, with or without greater trochanter separation
Jensen's classification (1975)
Displaced or undisplaced stable 2-fragment fractures
Unstable 3-fragment fractures with greater or lesser trochanter fracture
4-fragment fractures
Deburge's classification (1976)
Cervico-trochanteric fractures
Pertrochanteric fractures
Intertrochanteric fractures
Subtrochanteric fractures
Trochantero-diaphyseal fractures
Briot's classification (1980)
(1) Pertrochanteric fractures
- simple
- with posterior wall explosion
- extending into the shaft
(2) Intertrochanteric fractures
(3) Diaphyseo-trochanteric fractures
- Evans' reversed obliquity fracture
- "Basque roof" fractures
- Boyd's "steeple" fracture
- fractures with an additional line ascending to the intertrochanteric line
- Fractures with additional fracture lines radiating through the greater trochanter
AO classification (1981)
Group A1: Simple (2-fragment) pertrochanteric area fractures
A1.1 Fractures along the intertrochanteric line
A1.2 Fractures through the greater trochanter
A1.3 Fractures below the lesser trochanter
Group A2: Multifragmentary pertrochanteric fractures
A2.1 With one intermediate fragment
A2.2 With 2 intermediate fragments
A2.3 With more than 2 intermediate fragments
Group A3: Intertrochanteric fractures
A3.1 Simple, oblique
A3.2 Simple, transverse
A3.3 With a medial fragment