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Hemiarthroplasty of the hip and dislocation
Injury (1989) 20, 167-169
167
Binted in Great Britain
Hemiarthroplasty
of the hip and dislocation
R. W. Paton Hope Hospital, Salford
P. Hirst Manchester
Royal Infirmary, Manchester
studt~was utdrtahn on 171 patients who had suffereda subcapitaljkcfure of the neck of the femur befwem 1982 ana’ 1986. The aim was to compare the disbcatim rates in bipolar and morwpolarendoprostheses. The basic surgi~l appmches were utilized: the posterior and direct lateral. Fin4renabprosfb were empkyed: 7hompson’sMore’s (monopolar), Monk’s ‘hard top’, and Chamley+kfings (bipolar). There was no signijcanf difference in the dislocation rates between monopolar and bipolar devices. It is con&u& that the bipolar device5 do not offer any aaUitiona1 protectionagainst dislouzfionwhen comparedwith the traditional monopolar devices. A retmpecfive
Surgical experience was a constant factor, in that 90 per cent of the operations were undertaken by the same registrars. Between late 1981 and mid-1986,213 hemiarthroplasties were performed. There were 42 patients lost to follow-up or had case notes that could not be traced, leaving 171 cases in the study. There were 156 females and 15 males. The follow-up time was at least 6 months, with a maximum period of 4 years.
Introduction An accepted surgical treatment in the elderly for Garden types 3 and 4 subcapital fractures of the neck of the femur (Garden, 1961), is endoprosthetic replacement (D’arcy and Devas, 1976; Hodgkinson et al., 1988). These hemiarthroplasties may be the older monopolar (Thompson, 19%; Moore 1957), or more modem bipolar devices (Bateman, 1974; Monk 1976, Devas and Hinves 1983) (Figs. 1 and 2). The bipolar mechanism was developed in an attempt to reduce acetabular erosion. We have investigated retrospectively the dislocation rates between two monopolar and two bipolar prostheses. Patients and methods A retrospective trial was undertaken at Hope Hospital and Salford Royal Hospital, Salford. Four different hemiarthroplasties were employed for the treatment of displaced subcapital fractures of the neck of the femur in patients over the age of 65 years. The two monopolar prostheses were the Thompson (cemented), and the Moore (uncemented). The two bipolar devices were the Monks ‘hard top’ (cemented, Thompson stem) and the Charnley-Hastings (cemented). The type of prosthesis was determined by the wishes of the admitting consultant. Two basic surgical approaches were utilized; the posterior ‘Southern’ approach, and the direct lateral Hardinge or Liverpool approaches. 0 1989 Butterworth & Co (Publishers) Ltd OOZO-1383/89/03016743
$03.00
Figure 1. Monk’s ‘Hard-top’ Thompson stem.
Injury: the British Journal of Accident !Surgery (1989) Vol. ZO/No. 3
80 II ; 605
-
: L $
40.
Approach
E : 20. Dislocation 0, Total
r-l Lat.Post.Lat.Post.
a
otal Lat.Post.Lat.Post.
Thompson
Moore
Austin
40r
0 Total
b
Lat.Post.Lat.Post. Monk
‘Hard
Total
top’
Lat.Post.Lat.Post.
Charnley-Hasting
Figure 3. u, Monopolar group. b, Bipolar group. Graphic illustra-
tion of numbers of dislocation, when approach and prostheses are compared.
Figure 2. Charnley-Hastings
device. 8
Those patients having had the posterior approach spent 2 weeks rest in bed postoperatively, whereas those patients in which the lateral approach was used stayed in bed for only 2 days postoperatively. The rationale for this difference in treatment was that it was thought that the lateral was intrinsically more stable than the posterior approach.
Results The mean age in both the bipolar and monopolar groups was similar being 76.9 years and 80.8 years respectively. The mean in the series as a whole was 79.3 years. There were 10 dislocations giving an overall dislocation rate of 5.8 per cent. If the posterior and direct lateral approaches are taken separately, the dislocation rate was 8.6 per cent and 2.6 per cent respectively. The bipolar group (Monk and Charnley-Hastings) and the monopolar group (Thompson and Moore) dislocation rates were 4.8 per cent and 6.5 per cent respectively (T&e I, Fig3u, b, Table II and Fig. 4). The mean time to dislocation was 11.1 days (range l-40 days). There were two recurrent dislocations, a rate of 20 per cent. The mean age of those suffering a dislocation was 81.7 years (range 71-W years). As this was a retrospective study, it proved impossible to decide the aetiology of each dislocation. In the dislocation group the mortality rate was SO per cent on the same admission. The results were analysed statistically using the x2 test. There was no statistically significant difference in the dislocation rate between the bipolar and monopolar devices. On comparing the surgical approach, there was no sig-
0
Lat. Paz
u--l Total
Lat. Pos
Monopolar
Total
Lat. Pos
Bipolar
Total
both
groups
Figure 4. Monopolar and bipolar groups. Graphic illustrations of
type of prostheses and percentage of dislocation. Table I. Numbers of prostheses Number 1 Lateral
Posterior
Thompson
26 (2)
35 (4)
61
Moore Monk
25 (0) 13 (0) 14(O)
22 (1) 16 (2) 20(l) 93
5: 34 171
Charnley-Hastings Total
78
Total
( ) = number of dislocations.
Table II. Dislocation rate Lateral 09 Monopolar Bipolar Total
2.6
Posterior (W
Overall (%I
t::
6.5 4.8
8.6
5.8
Paton and Hit:
Hemiarthroplasty
169
of the hip and dislocation
r&cant difference, although the results were approaching statistical significance in favour of the direct lateral exposure (P < 0.08).
Discussion Postoperative dislocation of the herniarthroplasty is a serious complication with a mortality between 60 and 80 per cent (Chan and Hoskinson, X975; Lunt 1971). The rate of dislocation is increased by various risk factors such as age, medical condition, Parkinsonism, surgical approach, prosthetic malposition (Lunt, 1971; Chan and Hoskirtson, 1975; Staeheli et al., 1988). The published incidence of dislocation for hemiarthroplasty varies between I and 15 per cent (Chan and Hoskinson, 1975; D’arcy and Devas, 1976; Binns, 1985). The lowest rates of dislocation are associated with the anterior or trochanteric osteotomy approaches, and the highest rates are associated with the posterior exposure. The choice of the bipolar prosthesis should allow movement at the interbearing rather than between the head and the acetabulum. Theoretically this should confer the advantage of reducing acetabular wear and prosthetic migration. However, there is conflicting evidence on whether this mechanism works ‘in vivo’ (Drinker and Murray, 1979; Leyshon and Matthews, 1984; Phillips, 1987; Hodgkinson et at., 1988). It appears that the force required to dislocate the prosthesis from the acetabulum, exceeds the ability of the inner bearing to dissipate this force. The inner bearing has only a limited range of movement; 50” in the case of the Monk (Rees and Monk, 1986), and once this arc of movement is exceeded the prosthesis will act as a monopolar device. In this series, two cases required open reduction for failed closed manipulation. One prosthesis was the CharnleyHastings, and the other a Monk. On the attempted manipulation of the dislocation of the Charnley-Hastings prosthesis interprosthetic separation of the components occurred. This complication has been described by Rae and Paton (1988). The Monk prosthesis swivelled at the inner bearing, making closed reduction impossible. Therefore, open reduction may be necessary more often with bipolar devices, potentially increasing morbidity and mortality. The bipolar prosthesis does not offer any additional protection against dislocation when compared with the traditional monopolar device. If acetabular erosion is not significantly reduced by bipolar devices in the elderly, the added cost and increased risk of open reduction following dislocation would be a positive disadvantage. Monopolar devices through a lateral approach would be the most appropriate prostheses.
References Bateman J. E. (1974) Single assembly total hip prosthesis preliminary results. orthop. Dig. 2, 15. Binns M. (1985) Thompson hemi-arthroplasty through a trochanteric osteotomy approach. Injq 16,595. ChanR. N-W. and Hoskinson, J. (1975) Thompson’s prosthesis for fractured neck of femur. A comparison of surgical approaches. J. BoneJoint Surg. 5 7B,437. D'arcyJ. and Devas M. (1976) Treatment of fractures of the femoral neck by replacement with the Thompson prosthesis. ]. Bone]oint Surg. 58B, 279. Devas M. and Hinves B. (1983) Prevention of acetabular erosion after hemi-arthroplasty for fractured neck of femur. ]. BoneJoint .%rg. 65B, 548. Drinker H. and Murray W. R. (1979) The universal proximal femoral endoprosthesis. ]. Bone]oint 5%. 6lA, 1167. Garden R. S. (1961) Low angle fixation in fractures of the femoral neck. ]. &me joint Surg. 43B, 647. Hodgkinson J. P., Meadows T. H., Davies D. R. A. et al. (1988) A radiological assessment of interprosthetic movement in the Charnley-Hastings hemiarthoplasty. Injq 19, 18. Leyshon R. L. and Matthews J. P. (1984) Acetabular erosion and the Monk Hard-top’ prosthesis. ]. BoneJoint Surg. 668, 172. Lunt H. R. W. (1971) The role of prosthetic replacement of the head of the femur as primary treatment for subcapital fractures. Injury 3, 107. Monk C. J. E. (1976) Treatment of subcapital fractures of the neck of femur by replacement of the femoral head. Int. Congr. Ser. 377,65. Moore A. T. (1957) The self-locking metal hip prosthesis. ]. Bone Joint Swg. 39A, 811. Phillips T. W. (1987) The Bateman bipolar femoral head replacement. A fluoroscopic study of movement over a four year period. ]. Bow Joint Surg. 69B, 761. Rae P. J. and Paton R. W. (1988) Interprosthetic dislocation of the Charnley-Hastings prosthesis: brief report. ]. Bone ]oint Surg. 70B. 330. Rees D. and Monk C. J. E. (1986) Acetabular protrusion and the Monk duopleet prosthesis in subcapital femoral neck fractures. lnjuy 17,237. Staeheli J. W., Frassica F. J. and Sim F. H. (1988) Prosthetic replacement of the femoral head for fracture of the femoral neck in patients who have Parkinson disease. ]. Bone Joint Surg. 7OA, 565. Thompson F. R. (1954) Two and a half years’ experience with a vitalhum intramedullary hip prosthesis. ]. BoneJoint Surg 36A, 489.
Paper accepted 26 January 1989.
Acknowledgement We would like to thank the Consultant Orthopaedic Surgeons of Hope Hospital, Salford, for allowing us to review their patients.
Requ&s for reprints shouti be a&r& io: Mr Robin W. Paton, 30 Peckforton Close, Gatley, Cheadle, Cheshire SK8 4JA.
167
Binted in Great Britain
Hemiarthroplasty
of the hip and dislocation
R. W. Paton Hope Hospital, Salford
P. Hirst Manchester
Royal Infirmary, Manchester
studt~was utdrtahn on 171 patients who had suffereda subcapitaljkcfure of the neck of the femur befwem 1982 ana’ 1986. The aim was to compare the disbcatim rates in bipolar and morwpolarendoprostheses. The basic surgi~l appmches were utilized: the posterior and direct lateral. Fin4renabprosfb were empkyed: 7hompson’sMore’s (monopolar), Monk’s ‘hard top’, and Chamley+kfings (bipolar). There was no signijcanf difference in the dislocation rates between monopolar and bipolar devices. It is con&u& that the bipolar device5 do not offer any aaUitiona1 protectionagainst dislouzfionwhen comparedwith the traditional monopolar devices. A retmpecfive
Surgical experience was a constant factor, in that 90 per cent of the operations were undertaken by the same registrars. Between late 1981 and mid-1986,213 hemiarthroplasties were performed. There were 42 patients lost to follow-up or had case notes that could not be traced, leaving 171 cases in the study. There were 156 females and 15 males. The follow-up time was at least 6 months, with a maximum period of 4 years.
Introduction An accepted surgical treatment in the elderly for Garden types 3 and 4 subcapital fractures of the neck of the femur (Garden, 1961), is endoprosthetic replacement (D’arcy and Devas, 1976; Hodgkinson et al., 1988). These hemiarthroplasties may be the older monopolar (Thompson, 19%; Moore 1957), or more modem bipolar devices (Bateman, 1974; Monk 1976, Devas and Hinves 1983) (Figs. 1 and 2). The bipolar mechanism was developed in an attempt to reduce acetabular erosion. We have investigated retrospectively the dislocation rates between two monopolar and two bipolar prostheses. Patients and methods A retrospective trial was undertaken at Hope Hospital and Salford Royal Hospital, Salford. Four different hemiarthroplasties were employed for the treatment of displaced subcapital fractures of the neck of the femur in patients over the age of 65 years. The two monopolar prostheses were the Thompson (cemented), and the Moore (uncemented). The two bipolar devices were the Monks ‘hard top’ (cemented, Thompson stem) and the Charnley-Hastings (cemented). The type of prosthesis was determined by the wishes of the admitting consultant. Two basic surgical approaches were utilized; the posterior ‘Southern’ approach, and the direct lateral Hardinge or Liverpool approaches. 0 1989 Butterworth & Co (Publishers) Ltd OOZO-1383/89/03016743
$03.00
Figure 1. Monk’s ‘Hard-top’ Thompson stem.
Injury: the British Journal of Accident !Surgery (1989) Vol. ZO/No. 3
80 II ; 605
-
: L $
40.
Approach
E : 20. Dislocation 0, Total
r-l Lat.Post.Lat.Post.
a
otal Lat.Post.Lat.Post.
Thompson
Moore
Austin
40r
0 Total
b
Lat.Post.Lat.Post. Monk
‘Hard
Total
top’
Lat.Post.Lat.Post.
Charnley-Hasting
Figure 3. u, Monopolar group. b, Bipolar group. Graphic illustra-
tion of numbers of dislocation, when approach and prostheses are compared.
Figure 2. Charnley-Hastings
device. 8
Those patients having had the posterior approach spent 2 weeks rest in bed postoperatively, whereas those patients in which the lateral approach was used stayed in bed for only 2 days postoperatively. The rationale for this difference in treatment was that it was thought that the lateral was intrinsically more stable than the posterior approach.
Results The mean age in both the bipolar and monopolar groups was similar being 76.9 years and 80.8 years respectively. The mean in the series as a whole was 79.3 years. There were 10 dislocations giving an overall dislocation rate of 5.8 per cent. If the posterior and direct lateral approaches are taken separately, the dislocation rate was 8.6 per cent and 2.6 per cent respectively. The bipolar group (Monk and Charnley-Hastings) and the monopolar group (Thompson and Moore) dislocation rates were 4.8 per cent and 6.5 per cent respectively (T&e I, Fig3u, b, Table II and Fig. 4). The mean time to dislocation was 11.1 days (range l-40 days). There were two recurrent dislocations, a rate of 20 per cent. The mean age of those suffering a dislocation was 81.7 years (range 71-W years). As this was a retrospective study, it proved impossible to decide the aetiology of each dislocation. In the dislocation group the mortality rate was SO per cent on the same admission. The results were analysed statistically using the x2 test. There was no statistically significant difference in the dislocation rate between the bipolar and monopolar devices. On comparing the surgical approach, there was no sig-
0
Lat. Paz
u--l Total
Lat. Pos
Monopolar
Total
Lat. Pos
Bipolar
Total
both
groups
Figure 4. Monopolar and bipolar groups. Graphic illustrations of
type of prostheses and percentage of dislocation. Table I. Numbers of prostheses Number 1 Lateral
Posterior
Thompson
26 (2)
35 (4)
61
Moore Monk
25 (0) 13 (0) 14(O)
22 (1) 16 (2) 20(l) 93
5: 34 171
Charnley-Hastings Total
78
Total
( ) = number of dislocations.
Table II. Dislocation rate Lateral 09 Monopolar Bipolar Total
2.6
Posterior (W
Overall (%I
t::
6.5 4.8
8.6
5.8
Paton and Hit:
Hemiarthroplasty
169
of the hip and dislocation
r&cant difference, although the results were approaching statistical significance in favour of the direct lateral exposure (P < 0.08).
Discussion Postoperative dislocation of the herniarthroplasty is a serious complication with a mortality between 60 and 80 per cent (Chan and Hoskinson, X975; Lunt 1971). The rate of dislocation is increased by various risk factors such as age, medical condition, Parkinsonism, surgical approach, prosthetic malposition (Lunt, 1971; Chan and Hoskirtson, 1975; Staeheli et al., 1988). The published incidence of dislocation for hemiarthroplasty varies between I and 15 per cent (Chan and Hoskinson, 1975; D’arcy and Devas, 1976; Binns, 1985). The lowest rates of dislocation are associated with the anterior or trochanteric osteotomy approaches, and the highest rates are associated with the posterior exposure. The choice of the bipolar prosthesis should allow movement at the interbearing rather than between the head and the acetabulum. Theoretically this should confer the advantage of reducing acetabular wear and prosthetic migration. However, there is conflicting evidence on whether this mechanism works ‘in vivo’ (Drinker and Murray, 1979; Leyshon and Matthews, 1984; Phillips, 1987; Hodgkinson et at., 1988). It appears that the force required to dislocate the prosthesis from the acetabulum, exceeds the ability of the inner bearing to dissipate this force. The inner bearing has only a limited range of movement; 50” in the case of the Monk (Rees and Monk, 1986), and once this arc of movement is exceeded the prosthesis will act as a monopolar device. In this series, two cases required open reduction for failed closed manipulation. One prosthesis was the CharnleyHastings, and the other a Monk. On the attempted manipulation of the dislocation of the Charnley-Hastings prosthesis interprosthetic separation of the components occurred. This complication has been described by Rae and Paton (1988). The Monk prosthesis swivelled at the inner bearing, making closed reduction impossible. Therefore, open reduction may be necessary more often with bipolar devices, potentially increasing morbidity and mortality. The bipolar prosthesis does not offer any additional protection against dislocation when compared with the traditional monopolar device. If acetabular erosion is not significantly reduced by bipolar devices in the elderly, the added cost and increased risk of open reduction following dislocation would be a positive disadvantage. Monopolar devices through a lateral approach would be the most appropriate prostheses.
References Bateman J. E. (1974) Single assembly total hip prosthesis preliminary results. orthop. Dig. 2, 15. Binns M. (1985) Thompson hemi-arthroplasty through a trochanteric osteotomy approach. Injq 16,595. ChanR. N-W. and Hoskinson, J. (1975) Thompson’s prosthesis for fractured neck of femur. A comparison of surgical approaches. J. BoneJoint Surg. 5 7B,437. D'arcyJ. and Devas M. (1976) Treatment of fractures of the femoral neck by replacement with the Thompson prosthesis. ]. Bone]oint Surg. 58B, 279. Devas M. and Hinves B. (1983) Prevention of acetabular erosion after hemi-arthroplasty for fractured neck of femur. ]. BoneJoint .%rg. 65B, 548. Drinker H. and Murray W. R. (1979) The universal proximal femoral endoprosthesis. ]. Bone]oint 5%. 6lA, 1167. Garden R. S. (1961) Low angle fixation in fractures of the femoral neck. ]. &me joint Surg. 43B, 647. Hodgkinson J. P., Meadows T. H., Davies D. R. A. et al. (1988) A radiological assessment of interprosthetic movement in the Charnley-Hastings hemiarthoplasty. Injq 19, 18. Leyshon R. L. and Matthews J. P. (1984) Acetabular erosion and the Monk Hard-top’ prosthesis. ]. BoneJoint Surg. 668, 172. Lunt H. R. W. (1971) The role of prosthetic replacement of the head of the femur as primary treatment for subcapital fractures. Injury 3, 107. Monk C. J. E. (1976) Treatment of subcapital fractures of the neck of femur by replacement of the femoral head. Int. Congr. Ser. 377,65. Moore A. T. (1957) The self-locking metal hip prosthesis. ]. Bone Joint Swg. 39A, 811. Phillips T. W. (1987) The Bateman bipolar femoral head replacement. A fluoroscopic study of movement over a four year period. ]. Bow Joint Surg. 69B, 761. Rae P. J. and Paton R. W. (1988) Interprosthetic dislocation of the Charnley-Hastings prosthesis: brief report. ]. Bone ]oint Surg. 70B. 330. Rees D. and Monk C. J. E. (1986) Acetabular protrusion and the Monk duopleet prosthesis in subcapital femoral neck fractures. lnjuy 17,237. Staeheli J. W., Frassica F. J. and Sim F. H. (1988) Prosthetic replacement of the femoral head for fracture of the femoral neck in patients who have Parkinson disease. ]. Bone Joint Surg. 7OA, 565. Thompson F. R. (1954) Two and a half years’ experience with a vitalhum intramedullary hip prosthesis. ]. BoneJoint Surg 36A, 489.
Paper accepted 26 January 1989.
Acknowledgement We would like to thank the Consultant Orthopaedic Surgeons of Hope Hospital, Salford, for allowing us to review their patients.
Requ&s for reprints shouti be a&r& io: Mr Robin W. Paton, 30 Peckforton Close, Gatley, Cheadle, Cheshire SK8 4JA.