The real fracture of femoral neck

Abstracts

Cento e vinte e seis cabeças femorais retiradas durante artroplastias de quadril para tratamento de fraturas do colo do fêmur foram estudadas macroscopicamente e radiograficamente quanto ao traço de fratura e a existência de colo inferior que pode permanecer junto com a cabeça femoral. Chegou-se a conclusão que as fraturas do colo do fêmur obedecem a uma constância quanto ao traço de fratura, e que não existe a fratura subcapital verdadeira, pois em todos os casos analisados havia um fragmento de colo junto com a cabeça (esporão).

ARTIGO ORIGINAL

The real fracture of femoral neck

Carlos Roberto Schwartsmann^I; Gustavo Kaempf de Oliveira^II; Ricardo Kaempf de Oliveira^III; Leonardo Carbonera Boschin^III; Fernando Carlos Mothes^III; Ricardo Canquerini da Silva^IV

^IProfessor Titular de Ortopedia e Traumatologia da Fundação Faculdade de Ciências Médicas de Porto Alegre e Chefe do Serviço de Ortopedia e Traumatologia do Complexo Hospitalar Santa Casa de Porto Alegre

^IIOrtopedista membro da SBOT

^IIIResidentes do Serviço de Ortopedia e Traumatologia do Complexo Hospitalar Santa Casa de Porto Alegre

^IVEstagiário do Serviço de Ortopedia e Traumatologia do Complexo Hospitalar Santa Casa de Porto Alegre

SUMMARY

Hundred and six femoral necks collected during hip arthroplasty for treatment of fracture of femoral neck were studied macroscopically and radiographically with attention to the fracture line and the existence of the inferior neck that can remain with the femoral neck.

The conclusion was that fractures of femoral neck follow a constant regarding the line of fracture, and that a true subcapital fracture does not exist, since in all studied cases there was a fragment of neck in the femoral head (spur).

INTRODUCTION

Due to the importance of the femoral neck fractures, considered its frequency and severity, there are numerous publications about this subject. The textbooks bring the classification according to displacement (GARDEN)⁽⁷⁾, with respect to the fracture line (PAUWELS)⁽¹⁴⁾ and anatomical situation. The anatomical classification, described in the textbooks of Rockwood⁽¹⁴⁾, Watson-Jones⁽¹⁸⁾, Apley⁽¹⁾ e Murray⁽¹³⁾, divide the fractures in three types: Subcapital, mediocervical e basocervical.

Garden⁽⁸⁾ e Klenerman⁽¹⁰⁾ were the first to call attention to the fact that radiologically the line of fracture seems to vary in position, pending on the rotation of the femoral neck and leg and therefore the subcapital and mediocervical would be the same.

In a tentative to prove the veracity of these observations 126 femoral heads ressected during total or partial hip arthroplasty, were studied.

MATERIAL AND METHODS

126 intact femoral heads were removed during partial or total hip arthroplasty due to femoral neck fracture, from January/1991 to March/1999. Each head was studied macroscopically and radiologically with the intention of measuring the size of the femoral head, the type of fracture line and the presence of a spur in the femoral neck.

Eighty three patients were female (65,87%) The youngest patient was 46 years old and the eldest was 96 years old. The average age was 76,7 years. The side more frequently involved was the left side, 89 times (70,63%). In 86 cases (68,25%) partial hip prosthesis were used, and total arthroplasty in the remaining patients. No fracture was considered as true subcapital, i.e., with the fracture line marginal to the articular surface of the femoral head.

All cases had a pattern relatively constant of the fracture line: the fracture line starts in the lateral cervico-capital junction and goes in a oblique way trough the neck untill the inferomedial cortex, creating a spur. The average size of the spur was 13,24 mm. The smaller one had 4 mm and the bigger one 39 mm.

The size of the femoral head ranged from 39 to 53 mm, average 46,2 mm. There was no relation between the size of the head and the size of the spur.

Those cases where there was much time between the fracture and surgery, what causes a loss of the bone characteristics of the head due to sinovial lysis, were excluded from this study, as well as those heads broken during surgery.

DISCUSSION

In 1838, Ward⁽¹⁹⁾ described the lines internal trabecula of the neck showing the differences of bone density in this local. In 1961, Garden⁽⁸⁾ suggested that compressive forces act in spiral way, in the oblique and vertical direction upon the hip. These theories already could show that it would be logical that a neck fracture should follow the strength lines that act in this articulation ⁽⁴⁾.

Böhler⁽³⁾ classifies the neck fractures in abduction and aduction, Pauwels⁽¹⁴⁾ classifies according to the fracture line and Garden⁽⁷⁾ considering the displacement. However, recent books classify these fractures in two types: intra-articular and extra-articular. The intra-articular are subdivided in subcapital e transcervical^{(1,2,,5,6,14,15,17,18)} and the basocervical fracture is considered as the extra-articular type.

The word subcapital is used for fractures that occur imediately below the epiphisis. The word transcervical means that the fracture occurred transversaly, in the mid way from the femoral head and the intertrocanteric region.

However, many authors place doubts on the real existence of these two types of fractures. Klenerman⁽¹⁰⁾, Linton⁽¹²⁾ and Garden⁽⁷⁾ propose that a subcapital fracture can be erroneously interpreted as a transcervical fracture, depending on the degree of rotation of the fractured member at the moment of the radiography.

Hirsch⁽⁹⁾ demonstrated in 1965, that fracture of femoral neck can be produced in the laboratory by a vertical strength placed over the head, while the neck receives a simultaneous axial compression. Kocher⁽¹¹⁾ reproduced a fracture of femoral neck in cadavers applying a pressure over the long axis of the femur and causing a lateral rotation to the member. He believed that the head would stay fixed in the acetabular cavity by the round ligamment and ileofemoral capsule, while the neck would spin posteriorly. That could explain the comminutive aspect seen in circa of 50% of the fractures of femoral neck.

Probably the mechanism described by Kocher⁽¹¹⁾ is what really happens in patients. The existence of a constant pattern of the fractures in the 126 cases reinforces the theory of Garden⁽⁷⁾, that the different types of fracture of femoral neck represent different stages of rotation of the same type of fracture.

Klenerman⁽¹⁰⁾ (1970) described a constant pattern of the fractures of femoral neck, in which the fracture line runs obliquely starting at the junction cervicocapital lateral, at the level of the phisis scar, in direction to the medial cortex of the neck, causing a bigger or smaller spur.

The classification that includes the subcapiatal fracture as type of fracture, is due to an error in the analysis of the radiological exam, that changes the line of fracture depending of the rotation of the ileg and femoral head, giving the false impression of its existence ^(16).

CONCLUSIONS

1) The fracture line of the femoral neck follows a pattern relatively constant;

2) Allways exists a spur, showing that the fracture line is oblique from the lateral cervicocapital junction till the medial cortex.;

3) True subcapital fracture, according to classical descriptions, was not found;

4) The more correct anatomical classification is to divide the fractures of femoral neck in two major groups: intra or extracapsular.

REFERENCES

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• 2. Aston, J.N.: A short textbook of orthopaedics and traumatology. London, English Universities Press, 1967.
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• 11. Kocher, T.: Beitrge Zur Kenntniss Einiger Praktisch Wichtiger Fracturformen. Basel and Leipzig, C. Sallman, 1896.
• 12. Linton, P.: On the different types of intracapsular fractures of the femoral neck. Acta Chir Scand Suppl: 86, 1944.
• 13. Murray, R.O.: Skeletal trauma, in Textbook of radiology. Sutton, 1969.
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• 15. Schwartsmann, C.R., Menegassi, Z.,: A fratura medio-cervical existe?. Rev Bras Ortop 25 (4): 87-89, 1990.
• 16. Smith-Petersen, M.N., Cave, E.F., Van Gorder, G.W.: Intracapsular fractures of the neck of the femur. Arch Surg 23: 715, 1931.
• 17. Tronzo, R.G.: Surgery of the hip joint. Philadelphia, Lea & Febiger, 1973
• 18. Watson-Jones: Fractures and joint injuries. Fifth edition. Edinburgh, London and New York, Churchill Livingstone, 1976 p. 927..
• 19. Ward, F.O.: Outlines of human osteology, p. 370 , Henry Renshaw, 1838.

Publication Dates

• Publication in this collection
  07 May 2007
• Date of issue
  Sept 2000