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A second proximal femoral fracture caused by failure of a sliding hip screw
Injury: International
694
the diagnosis is ‘obvious and easy to treat’ (Gogan et al., 1988). Our case report reveals that these observations are not always correct. The fracture can occur-e with an ideally placed hip screw, centrally placed and within 1 cm of the subchondral bone of the femoral head (Doppelt, 1980) without the predisposing factors of stress risers or alcoholic osteomalacia. This fracture can be difficult to diagnose if, as in our report, there is no history of a fall, and the original radiograph is normal. Our purpose in reporting this case is to draw attention to these discrepancies and broaden the awareness of this complication.
Journal of the Care of the Injured (1993)Vol.24/No.10 best answer for stabilization of intertrochanteric hip fractures. Orfhop. Clin. North Am. 11,507. Gogan W. G., Daum W. J., Simmons D. J. et al. (1988) Subcapital fracture of the hip following an intertrochanteric fracture. Clin. Orfhop. 232,205. Mariani E. M. and Rand J. A. (1989) Subcapital fractures after open reduction and internal fixation of intertrochanteric fractures of the hip. Clin. Orfkop. 254, 165. Tronzo R. G. (ed) (1973) Surgery of the hip joint. Philadelphia: Lea & Febiger, 52.
Paper accepted
References Doppelt S. H. (1980) The sliding compression
screw - todays
6 August
1993.
Requests for reprints should be addressed to: Dr R. H. Jinnah, 3449 Wilkens Avenue, Suite 305, Baltimore, MD 21229, USA.
A second proximal femoral fracture caused by failure of a sliding hip screw J. H. Marshall and J. P. Brooks Birmingham
Heartlands
Hospital,
Birmingham,
UK
Introduction
Discussion
We report a rare mode of failure of a sliding hip screw and the consequences thereof. We believe this case illustrates the need for careful rehabilitation should removal of a device of this type prove necessary.
Case report A 74-year-old female sustained a stable pattern intertrochanteric fracture of the right upper femur in August 1987. This was treated with a sliding 100 mm screw and a 4-hole 135” plate. Her post-operative recovery was uncomplicated and she was discharged from hospital bearing full weight 13 days later. Four months later she was asymptomatic; the radiological appearances are shown in Figure I. She remained symptom-free until 5 years later when she developed a sudden onset of severe pain in the right hip and inability to bear weight. There had been no further trauma. The radiograph (Figure 2) showed the implant to have broken and a fresh transcervical fracture of the femur had occurred. At operation there was considerable metallic staining of the tissues; the lag screw had fractured at its junction with the barrel leaving a residual length of 38 mm very firmly retained within the barrel of the plate. The original trochanteric fracture had united. Treatment consisted of insertion of a cemented total hip replacement. 0 1993 Butterworth-Heinemann 0020-1383/93/100694-03
Ltd
The sliding hip screw is a reliable implant for the fixation of proximal femoral fractures. To our knowledge only one case of breakage of the hip screw has been reported (Jakobsen, 1987), and this occurred in a patient with an unstable fracture pattern in whom ancillary fixation was employed. Caution was advised in the placement of such fixation; no such fixation, however, was used in this case. Various other modes of failure have been reported, with cutting out of the screw from the femoral head being the most common. Accurate placement of the hip screw has been emphasized by many authors as being important in the avoidance of failure of the implant in this manner (Davis et al., 1990; Mainds and Newman, 1989), whilst Davis et al. also conclude (1990) that the fracture should be reduced as accurately as possible. Our patient fulfilled both of these criteria and had remained symptom-free for 5 years, in contrast to the failures in the’above papers which had all occurred within 12 months of operation. Simpson et al. (1989) concluded that failure of a sliding hip screw was more likely to occur when the device had lost its sliding action. Kyle et al. (1980) showed that such jamming would occur when frictional forces are greater than the sliding force in the line of the screw. They produced a formula for predicting jamming based on the ratio of the length of the screw outside the barrel of
695
Case reports
Figure
1. a,b, Anteroposterior
Figure 2. a, b, Anteroposterior
and lateral views of fixation of p rimary intertrochanteric
and lateral views showing
implal nt failu re and secondary
fracture.
transcervical
fracture.
696
Injury: International Journal of the Care of the Injured (1993) Vol. 24/No. 10
The subsequent acute breakage of the implant led to sudden loading of the femoral neck which had been previously protected and offloaded by the presence of the implant. This sudden loading of the osteoporotic femoral neck led to its acute fracture. This case would seem to suggest that when removal of an implant of this type is necessary then it should be followed by a period of careful rehabilitation to avoid further osteoporotic fracture.
Figure 3. A typical sliding hip screw to demonstrate lengths Lb
and L,,.
the plate (L,) to the length inside (Lb) (Figure.3). For the 135” plate, jamming could be expected when L,/L,, is 4.7 or greater. In this case, however, L, was 62 mm, I+ was 38mm and therefore I,,,/& equalled 1.63. Theoretically, therefore, jamming of the implant should not have occurred; nevertheless, the findings at the second operation suggest that such jamming did occur after a considerable period of friction between the barrel and the screw which was responsible for the intense metallic staining of the tissues. Furthermore, the reduction of the fracture and its inherent stability had obviated the need for a sliding action to take place in this case. We believe that the implant failed under cyclical loading with the production of stress concentration at the end of the barrel.
References Davis T. R. C., Sher J. L, Horsman A. et al. (1990) Intertrochanteric femoral fractures. J. Bone Joint Surg. f&-J 72B, 26. Jakobsen B. W. (1987) Breakage of a sliding hip screw. Acfa Orfhop. Stand. 58,292. Kyle R. F., Wright T. M. and Burstein A. H. (1980) Biomechanical analysis of the sliding characteristics of compression hip screws. 1. Bone joint Surg. (Am.) 62A, 1308. Mainds C. C. and Newman R. J. (1989) Implant failures in patients with proximal fractures of the femur treated with a sliding screw device. Injury 20, 98. Simpson A. H. R. W., Varty K. and Dodd C. A. F. (1989) Sliding hip screws: modes of failure. Injury 20, 227. Paper accepted
4 August
1993.
Requests for reprints should be addressed to: Mr J. H. Marshall, Birmingham Heartlands Hospital, Bordesley Green East, Birmingham B9 5SS, UK.
694
the diagnosis is ‘obvious and easy to treat’ (Gogan et al., 1988). Our case report reveals that these observations are not always correct. The fracture can occur-e with an ideally placed hip screw, centrally placed and within 1 cm of the subchondral bone of the femoral head (Doppelt, 1980) without the predisposing factors of stress risers or alcoholic osteomalacia. This fracture can be difficult to diagnose if, as in our report, there is no history of a fall, and the original radiograph is normal. Our purpose in reporting this case is to draw attention to these discrepancies and broaden the awareness of this complication.
Journal of the Care of the Injured (1993)Vol.24/No.10 best answer for stabilization of intertrochanteric hip fractures. Orfhop. Clin. North Am. 11,507. Gogan W. G., Daum W. J., Simmons D. J. et al. (1988) Subcapital fracture of the hip following an intertrochanteric fracture. Clin. Orfhop. 232,205. Mariani E. M. and Rand J. A. (1989) Subcapital fractures after open reduction and internal fixation of intertrochanteric fractures of the hip. Clin. Orfkop. 254, 165. Tronzo R. G. (ed) (1973) Surgery of the hip joint. Philadelphia: Lea & Febiger, 52.
Paper accepted
References Doppelt S. H. (1980) The sliding compression
screw - todays
6 August
1993.
Requests for reprints should be addressed to: Dr R. H. Jinnah, 3449 Wilkens Avenue, Suite 305, Baltimore, MD 21229, USA.
A second proximal femoral fracture caused by failure of a sliding hip screw J. H. Marshall and J. P. Brooks Birmingham
Heartlands
Hospital,
Birmingham,
UK
Introduction
Discussion
We report a rare mode of failure of a sliding hip screw and the consequences thereof. We believe this case illustrates the need for careful rehabilitation should removal of a device of this type prove necessary.
Case report A 74-year-old female sustained a stable pattern intertrochanteric fracture of the right upper femur in August 1987. This was treated with a sliding 100 mm screw and a 4-hole 135” plate. Her post-operative recovery was uncomplicated and she was discharged from hospital bearing full weight 13 days later. Four months later she was asymptomatic; the radiological appearances are shown in Figure I. She remained symptom-free until 5 years later when she developed a sudden onset of severe pain in the right hip and inability to bear weight. There had been no further trauma. The radiograph (Figure 2) showed the implant to have broken and a fresh transcervical fracture of the femur had occurred. At operation there was considerable metallic staining of the tissues; the lag screw had fractured at its junction with the barrel leaving a residual length of 38 mm very firmly retained within the barrel of the plate. The original trochanteric fracture had united. Treatment consisted of insertion of a cemented total hip replacement. 0 1993 Butterworth-Heinemann 0020-1383/93/100694-03
Ltd
The sliding hip screw is a reliable implant for the fixation of proximal femoral fractures. To our knowledge only one case of breakage of the hip screw has been reported (Jakobsen, 1987), and this occurred in a patient with an unstable fracture pattern in whom ancillary fixation was employed. Caution was advised in the placement of such fixation; no such fixation, however, was used in this case. Various other modes of failure have been reported, with cutting out of the screw from the femoral head being the most common. Accurate placement of the hip screw has been emphasized by many authors as being important in the avoidance of failure of the implant in this manner (Davis et al., 1990; Mainds and Newman, 1989), whilst Davis et al. also conclude (1990) that the fracture should be reduced as accurately as possible. Our patient fulfilled both of these criteria and had remained symptom-free for 5 years, in contrast to the failures in the’above papers which had all occurred within 12 months of operation. Simpson et al. (1989) concluded that failure of a sliding hip screw was more likely to occur when the device had lost its sliding action. Kyle et al. (1980) showed that such jamming would occur when frictional forces are greater than the sliding force in the line of the screw. They produced a formula for predicting jamming based on the ratio of the length of the screw outside the barrel of
695
Case reports
Figure
1. a,b, Anteroposterior
Figure 2. a, b, Anteroposterior
and lateral views of fixation of p rimary intertrochanteric
and lateral views showing
implal nt failu re and secondary
fracture.
transcervical
fracture.
696
Injury: International Journal of the Care of the Injured (1993) Vol. 24/No. 10
The subsequent acute breakage of the implant led to sudden loading of the femoral neck which had been previously protected and offloaded by the presence of the implant. This sudden loading of the osteoporotic femoral neck led to its acute fracture. This case would seem to suggest that when removal of an implant of this type is necessary then it should be followed by a period of careful rehabilitation to avoid further osteoporotic fracture.
Figure 3. A typical sliding hip screw to demonstrate lengths Lb
and L,,.
the plate (L,) to the length inside (Lb) (Figure.3). For the 135” plate, jamming could be expected when L,/L,, is 4.7 or greater. In this case, however, L, was 62 mm, I+ was 38mm and therefore I,,,/& equalled 1.63. Theoretically, therefore, jamming of the implant should not have occurred; nevertheless, the findings at the second operation suggest that such jamming did occur after a considerable period of friction between the barrel and the screw which was responsible for the intense metallic staining of the tissues. Furthermore, the reduction of the fracture and its inherent stability had obviated the need for a sliding action to take place in this case. We believe that the implant failed under cyclical loading with the production of stress concentration at the end of the barrel.
References Davis T. R. C., Sher J. L, Horsman A. et al. (1990) Intertrochanteric femoral fractures. J. Bone Joint Surg. f&-J 72B, 26. Jakobsen B. W. (1987) Breakage of a sliding hip screw. Acfa Orfhop. Stand. 58,292. Kyle R. F., Wright T. M. and Burstein A. H. (1980) Biomechanical analysis of the sliding characteristics of compression hip screws. 1. Bone joint Surg. (Am.) 62A, 1308. Mainds C. C. and Newman R. J. (1989) Implant failures in patients with proximal fractures of the femur treated with a sliding screw device. Injury 20, 98. Simpson A. H. R. W., Varty K. and Dodd C. A. F. (1989) Sliding hip screws: modes of failure. Injury 20, 227. Paper accepted
4 August
1993.
Requests for reprints should be addressed to: Mr J. H. Marshall, Birmingham Heartlands Hospital, Bordesley Green East, Birmingham B9 5SS, UK.