Injury (1991)
22,
(I), 45-46
Dynamic
Prirzted in Great Britain
45
hip screws that fail
A. P. Thomas The Royal Hospital, Wolverhampton,
UK
A series of 87 frochanttic fractures of the femur treated by dynamic hip screw, was reviewed. The relationship between the position of thefracturefiagments and the position of the hip screw in the femoral head was investigated. Hip screws inserted into some parts of the femoral head were more likely to cut out than 0th. Somefractures were undisplaced or had been perfectly reduced. A lateral radiograph of some of the others showed that the femoral head and neck were aligned with the shaft. Only among these fractureswas thenumber of good screw placements as great as among those that were undisplaced or perfectly reduced.
Introduction In 1981, Jensen defined technical failure of fixation of trochanteric fractures as ‘Bending, breakage or loosening of the implant and cutting or penetration of the implant tip within or through the femoral head or neck confinements’. Bannister and Gibson (1983), Heyse-Moore et al. (1983) and Esser et al. (1986) have shown the lower rates of technical failure which can be achieved by using a dynamic hip screw rather than a Jewett nail-plate. However, a technical failure rate of 10 per cent is still the norm. When inserting a rigid nail and plate to fix a trochanteric fracture, it was accepted practice to aim to insert the tip of the device into the lower part of the femoral head, so that if the tip of the nail cut through the head there would be some distance for it to travel before it cut out completely. Mainds and Newman (1989) have recently shown that a dynamic hip screw is also less likely to cut out if put into the lower half of the femoral head. Technical failure of fixation can lead to prolonged bed rest, prolonged follow-up, or complete failure of the fixation (Heyse-Moore et al., 1983). It is important to make the fracture fixation as secure as possible. This paper investigates how the position of the fracture fragments when the dynamic hip screw is inserted, influences the positioning of the dynamic hip screw in the femoral head.
There were 73 women and 14 men. The average age was 82 years (range 42-105 years). The fractures were classified according to Jensen’s modification of the Evans classification as grade 1, 16; grade 2, 15; grade 3, 19; grade 4, 16; and grade 5,21 (Evans, 1949). The surgical treatment consisted of closed manipulative reduction on a traction table followed by insertion of the dynamic hip screw. No supplementary fixation was used. The fracture fragments were not impacted by drawing the hip screw back down the barrel of the plate. Three patients had a second operation in which the hip screw was re-inserted because of failure of the fixation achieved by the first operation. Therefore, there was a total of 90 hip screws inserted. The postoperative radiographs taken before weight bearing were used for the assessment. Assessment of screw placement The femoral head was considered to have three zones on the anteroposterior film and three zones on the lateral film, effectively creating nine columns (F&we I). Screws which were inserted in the middle column or the middle of the lower three columns were deemed good, those elsewhere in the lower two-thirds of the head satisfactory and those inserted in the margins of the head or the upper one-third of the head deemed poor. Assessment of reduction The fractures were divided into groups (Table I, first column). A fracture was considered to be reduced if the fragments
Patients and methods a U-month period, 95 patients had trochanteric fractures treated by dynamic hip screws in Wolverhampton. Their records and radiographs were examined and their progress assessed at least 9 months after the injury. Complete information was available on 87 fractures. During
0’1991
Butterworth-Heinemann
0020-1383/91/010045~2
Ltd
ti FigureI. The femoral head divided into zones.
46
Injury: the British Journal of Accident Surgery (1991) Vol. 22/No.
Table I. Screw placement Good Anatomically reduced Reduction Aligned and apposed Aligned, not apposed Apposed and not aligned Not aligned and not apposed Guidewire stabilization
Other
(Satis.)
(Poor)
17
7
(5)
(2)
18
15
(10)
(5)
P=O.33
6
2
(1)
(1)
P>O.5
1
15
(7)
(8)
P= 0.0001
0
3
(0)
(3)
P= 0.082
6
0
P= 0.34
P=The probability of no difference from the anatomically reduced group calculated by Fisher’s Exact Test. in anatomical relationship. A fracture was considered apposed if the femoral neck and shaft fragments seemed to be touching. It was considered aligned if the lateral radiograph showed that the middle of the femoral shaft, the middle of the femoral neck and the middle of the femoral head were aligned such that the dynamic hip screw could pass through the centre of each of these structures. It was found difficult to align some fractures by manipulation alone. In six cases (four primary and two revisions) it was found helpful to stabilize the proximal fragment by passing a guidewire across the abductor muscles proximal to the greater trochanter, through the femoral head and into the acetabulum. This was done after the incision through skin and fascia lata with the leg internally rotated, after which external rotation produced a satisfactory alignment. These six cases were considered as a separate group. were
Results shows schematically the number of dynamic hip screws inserted in each column of the femoral head. Screws which were inserted touching or breaching the margins of the head are shown in the outer ring of the diagram. The nine cases in which there was a technical failure of the fixation are shown in brackets. Tuble I shows how many good, satisfactory and poor screw placements were achieved for each category of Figure 2
Superior
Anterior
(I (1) 1
10
1
35
1 7
1
) Posterior
1
reduction. The results in fractures which were aligned were similar to fractures which were reduced. Those which were not aligned had significantly worse results (Fisher’s Exact Test). A good screw position was achieved in each of the six cases in which a guidewire was used to stabilize the proximal fragment. In four fractures the fixation was revised because of fixation failure. None had any further technical failure.
Discussion The dynamic hip screw has greatly improved the prospect of obtaining a stable fixation on which elderly patients can walk. It is important to know how to insert the device for optimal fixation. Exact measurements of the radiographs are not discussed in this paper as these would not normally be available when putting in a hip screw. Mainds and Newman (1989) show that there is less chance of complete collapse of the fixation if the screw is in the lower half of the femoral head. In the present study it seems that within the lower two-thirds of the femoral head is satisfactory. Also, screws which are placed near the margins of the femoral head seem more likely to fail. There was no further failure of the fixation in cases which were revised because of a technical failure. This finding supports the proposition that technical failure was related to the way the operation was carried out. It is not strictly necessary for the neck of the femur to point towards the shaft in order to pass a dynamic hip screw across the middle of the shaft into the middle of the head. But there was only one case in which the shaft, neck and head were not in an approximately straight line as viewed on the lateral radiograph in which a good screw position was achieved. It was not necessary to have the fragments firmly impacted together to get a good screw position. A guidewire to stabilize the proximal fragment in the acetabulum allowed dynamic hip screws to be inserted in a good position when closed reduction was difficult. If a good alignment cannot be obtained by closed manipulation alone, some other technique for achieving a good alignment should be used before proceeding to insert the hip screw.
References Bannister G. C. and Gibson A. G. F. (1983) Jewett nail-plate or A0 dynamic hip screw for trochanteric fractures. J. Bone Joint Surg. 65B, 218. Esser M. P., Kassab J. Y. and Jones D. H. A. (1986) Trochanteric ’ fractures of the femur. 1. Bone Joint Sttrg. 688,557. Evans E. M. (1949) The treatment of trochanteric fractures of the femur. 1. Bone Joint Stlrg.31B, 190. Heyse-Moore G. H., MacEachem A. G. and Jameson Evans D. C. (1983) Treatment of intertrochanteric fractures of the femur. 1. Bone joint surg. 65B, 262. Jensen J. S. (1981) Trochanteric fractures: an epidemiological, clinical and biomechanical study. Acfa Orthop. Stand. Suppl. 188. Mainds C. C. and Newman R. J. (1989) Implant failures in patients with proximal fractures of the femur treated with a sliding screw device. InjuT 20, 98. Paper accepted
30 March 1990.
Inferior Figure 2. The number of dynamic hip screws placed in each zone of the femoral head. Technical failures in brackets.
Requesfs for reprints should be aa&essed fo: Mr A. P. Thomas, 5 Tall Trees Close, Catshill, Bromsgrove, Worcestershire 861 OHQ, UK.
22,
(I), 45-46
Dynamic
Prirzted in Great Britain
45
hip screws that fail
A. P. Thomas The Royal Hospital, Wolverhampton,
UK
A series of 87 frochanttic fractures of the femur treated by dynamic hip screw, was reviewed. The relationship between the position of thefracturefiagments and the position of the hip screw in the femoral head was investigated. Hip screws inserted into some parts of the femoral head were more likely to cut out than 0th. Somefractures were undisplaced or had been perfectly reduced. A lateral radiograph of some of the others showed that the femoral head and neck were aligned with the shaft. Only among these fractureswas thenumber of good screw placements as great as among those that were undisplaced or perfectly reduced.
Introduction In 1981, Jensen defined technical failure of fixation of trochanteric fractures as ‘Bending, breakage or loosening of the implant and cutting or penetration of the implant tip within or through the femoral head or neck confinements’. Bannister and Gibson (1983), Heyse-Moore et al. (1983) and Esser et al. (1986) have shown the lower rates of technical failure which can be achieved by using a dynamic hip screw rather than a Jewett nail-plate. However, a technical failure rate of 10 per cent is still the norm. When inserting a rigid nail and plate to fix a trochanteric fracture, it was accepted practice to aim to insert the tip of the device into the lower part of the femoral head, so that if the tip of the nail cut through the head there would be some distance for it to travel before it cut out completely. Mainds and Newman (1989) have recently shown that a dynamic hip screw is also less likely to cut out if put into the lower half of the femoral head. Technical failure of fixation can lead to prolonged bed rest, prolonged follow-up, or complete failure of the fixation (Heyse-Moore et al., 1983). It is important to make the fracture fixation as secure as possible. This paper investigates how the position of the fracture fragments when the dynamic hip screw is inserted, influences the positioning of the dynamic hip screw in the femoral head.
There were 73 women and 14 men. The average age was 82 years (range 42-105 years). The fractures were classified according to Jensen’s modification of the Evans classification as grade 1, 16; grade 2, 15; grade 3, 19; grade 4, 16; and grade 5,21 (Evans, 1949). The surgical treatment consisted of closed manipulative reduction on a traction table followed by insertion of the dynamic hip screw. No supplementary fixation was used. The fracture fragments were not impacted by drawing the hip screw back down the barrel of the plate. Three patients had a second operation in which the hip screw was re-inserted because of failure of the fixation achieved by the first operation. Therefore, there was a total of 90 hip screws inserted. The postoperative radiographs taken before weight bearing were used for the assessment. Assessment of screw placement The femoral head was considered to have three zones on the anteroposterior film and three zones on the lateral film, effectively creating nine columns (F&we I). Screws which were inserted in the middle column or the middle of the lower three columns were deemed good, those elsewhere in the lower two-thirds of the head satisfactory and those inserted in the margins of the head or the upper one-third of the head deemed poor. Assessment of reduction The fractures were divided into groups (Table I, first column). A fracture was considered to be reduced if the fragments
Patients and methods a U-month period, 95 patients had trochanteric fractures treated by dynamic hip screws in Wolverhampton. Their records and radiographs were examined and their progress assessed at least 9 months after the injury. Complete information was available on 87 fractures. During
0’1991
Butterworth-Heinemann
0020-1383/91/010045~2
Ltd
ti FigureI. The femoral head divided into zones.
46
Injury: the British Journal of Accident Surgery (1991) Vol. 22/No.
Table I. Screw placement Good Anatomically reduced Reduction Aligned and apposed Aligned, not apposed Apposed and not aligned Not aligned and not apposed Guidewire stabilization
Other
(Satis.)
(Poor)
17
7
(5)
(2)
18
15
(10)
(5)
P=O.33
6
2
(1)
(1)
P>O.5
1
15
(7)
(8)
P= 0.0001
0
3
(0)
(3)
P= 0.082
6
0
P= 0.34
P=The probability of no difference from the anatomically reduced group calculated by Fisher’s Exact Test. in anatomical relationship. A fracture was considered apposed if the femoral neck and shaft fragments seemed to be touching. It was considered aligned if the lateral radiograph showed that the middle of the femoral shaft, the middle of the femoral neck and the middle of the femoral head were aligned such that the dynamic hip screw could pass through the centre of each of these structures. It was found difficult to align some fractures by manipulation alone. In six cases (four primary and two revisions) it was found helpful to stabilize the proximal fragment by passing a guidewire across the abductor muscles proximal to the greater trochanter, through the femoral head and into the acetabulum. This was done after the incision through skin and fascia lata with the leg internally rotated, after which external rotation produced a satisfactory alignment. These six cases were considered as a separate group. were
Results shows schematically the number of dynamic hip screws inserted in each column of the femoral head. Screws which were inserted touching or breaching the margins of the head are shown in the outer ring of the diagram. The nine cases in which there was a technical failure of the fixation are shown in brackets. Tuble I shows how many good, satisfactory and poor screw placements were achieved for each category of Figure 2
Superior
Anterior
(I (1) 1
10
1
35
1 7
1
) Posterior
1
reduction. The results in fractures which were aligned were similar to fractures which were reduced. Those which were not aligned had significantly worse results (Fisher’s Exact Test). A good screw position was achieved in each of the six cases in which a guidewire was used to stabilize the proximal fragment. In four fractures the fixation was revised because of fixation failure. None had any further technical failure.
Discussion The dynamic hip screw has greatly improved the prospect of obtaining a stable fixation on which elderly patients can walk. It is important to know how to insert the device for optimal fixation. Exact measurements of the radiographs are not discussed in this paper as these would not normally be available when putting in a hip screw. Mainds and Newman (1989) show that there is less chance of complete collapse of the fixation if the screw is in the lower half of the femoral head. In the present study it seems that within the lower two-thirds of the femoral head is satisfactory. Also, screws which are placed near the margins of the femoral head seem more likely to fail. There was no further failure of the fixation in cases which were revised because of a technical failure. This finding supports the proposition that technical failure was related to the way the operation was carried out. It is not strictly necessary for the neck of the femur to point towards the shaft in order to pass a dynamic hip screw across the middle of the shaft into the middle of the head. But there was only one case in which the shaft, neck and head were not in an approximately straight line as viewed on the lateral radiograph in which a good screw position was achieved. It was not necessary to have the fragments firmly impacted together to get a good screw position. A guidewire to stabilize the proximal fragment in the acetabulum allowed dynamic hip screws to be inserted in a good position when closed reduction was difficult. If a good alignment cannot be obtained by closed manipulation alone, some other technique for achieving a good alignment should be used before proceeding to insert the hip screw.
References Bannister G. C. and Gibson A. G. F. (1983) Jewett nail-plate or A0 dynamic hip screw for trochanteric fractures. J. Bone Joint Surg. 65B, 218. Esser M. P., Kassab J. Y. and Jones D. H. A. (1986) Trochanteric ’ fractures of the femur. 1. Bone Joint Sttrg. 688,557. Evans E. M. (1949) The treatment of trochanteric fractures of the femur. 1. Bone Joint Stlrg.31B, 190. Heyse-Moore G. H., MacEachem A. G. and Jameson Evans D. C. (1983) Treatment of intertrochanteric fractures of the femur. 1. Bone joint surg. 65B, 262. Jensen J. S. (1981) Trochanteric fractures: an epidemiological, clinical and biomechanical study. Acfa Orthop. Stand. Suppl. 188. Mainds C. C. and Newman R. J. (1989) Implant failures in patients with proximal fractures of the femur treated with a sliding screw device. InjuT 20, 98. Paper accepted
30 March 1990.
Inferior Figure 2. The number of dynamic hip screws placed in each zone of the femoral head. Technical failures in brackets.
Requesfs for reprints should be aa&essed fo: Mr A. P. Thomas, 5 Tall Trees Close, Catshill, Bromsgrove, Worcestershire 861 OHQ, UK.
