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Failure of Austin Moore hemiarthroplasty: total hip replacement as a treatment strategy
Injury, Int. J. Care Injured 33 (2002) 19 – 21 www.elsevier.com/locate/injury
Failure of Austin Moore hemiarthroplasty: total hip replacement as a treatment strategy A.J. Cossey *, M.I. Goodwin Royal Bournemouth Hospital, Bournemouth, UK Accepted 12 June 2001
Abstract Forty six patients who underwent conversion of their Austin Moore hemiarthroplasty to a total hip replacement were assessed clinically and radiologically. Forty patients requiring conversion had either groin or thigh pain. Operative findings showed acetabular cartilage degeneration and femoral loosening as the main pathological process causing their symptoms. Total hip replacement gave complete resolution of the symptoms in 41 patients. We propose early conversion to total joint arthroplasty in patients with painful hemiarthroplasties. © 2002 Elsevier Science Ltd. All rights reserved.
1. Introduction Femoral neck fractures are occurring with increasing frequency [1,2] accounting for considerable morbidity and mortality in the osteoporotic population in industrialised western countries [3]. A total of 20% of orthopaedic beds in the UK are occupied by patients with such fractures and with greater numbers of active geriatric patients [4], the number of hemiarthroplasty procedures being performed will rise accordingly. Austin Moore hemiarthroplasties have favourable long-term follow-up data in the treatment of displaced femoral neck fractures [5 – 11]. Insertion is relatively straightforward allowing early mobilisation and restoration to a functional level of activity, therefore decreasing the overall morbidity and mortality to the patient [12]. However, long term results of the prosthesis also show associations with acetabular cartilage degeneration [12,15 – 18] and femoral loosening [13,14]. With 50% of the femoral neck fracture population surviving for 5 years or greater [14,19] long-term complications associated with the prosthesis will continue to rise. The aim of this study was to show that conversion to a total hip replacement for symptomatic, failed hemi* Corresponding author. Present address: 68 Purewell, Christchurch, Dorset BH23 1ES, UK. Tel.: +44-1202-480-057; fax: +44-1705-286-570.
arthroplasties is an excellent management strategy to give the patient a pain-free, functionally acceptable lifestyle.
2. Materials and methods From January 1st 1992 until 31st December 1996 a total of 46 patients underwent conversion of their Austin Moore hemiarthroplasty to a total hip replacement. These patients were referred back to orthopaedic clinics from their primary care team as no routine follow up for hemiarthroplasties is conducted at our institution. The patients were clinically and radiologically assessed by an Orthopaedic Surgeon (38 Consultant, eight Registrar/Staff Grades). Investigations conducted in clinic included a septic screen (full blood count, ESR, CRP) and plain anteroposterior and lateral X-rays of the symptomatic hip. Radiological examination assessed abnormal position of the prosthesis, inadequate contact with the calcar, descent of the prosthesis into the femur, radiolucencies around the prosthesis and protrusio acetabulae (medial migration of the prosthetic head beyond Kohler’s line) [21,25,26]. Treatment strategies prior to conversion were also reviewed. At operation the condition of the articular cartilage in the acetabulum, the stability of the prosthesis in the
0020-1383/02/$ - see front matter © 2002 Elsevier Science Ltd. All rights reserved. PII: S 0 0 2 0 - 1 3 8 3 ( 0 1 ) 0 0 0 9 6 - 1
20
A.J. Cossey, M.I. Goodwin / Injury, Int. J. Care Injured 33 (2002) 19–21 Table 3 Non-operative treatment prior to conversion
Table 1 Clinical findings at outpatient clinic assessment
Pain Pain and antalgic gait Pain and leg length discrepancy Pain antalgic gait and leg length discrepancy
n
%
18 12 14 2
39 26 30 5
proximal femur and any other associated pathological conditions found were documented by the surgeon. Clinical and radiological assessment of the patient’s 1-year post conversion to total hip replacement were conducted in routine orthopaedic clinics.
3. Results Of the 46 patients presenting with symptomatic hemiarthroplasties, 33 were female and 13 were male. Their mean age at the time of conversion was 76.1 years. Forty of the patients had experienced pain since the early rehabilitation phase following their hemiarthroplasty, sufficient to affect their sleep pattern and activities of daily living. The pain was located either in the groin and/or thigh and was associated with either an antalgic gait or a leg length discrepancy (Table 1). The mean time lapse from hemiarthroplasty insertion to presentation to clinic was 5.81 months. During this time period over 1900 Austin Moore Hemiarthroplasties were inserted. Haematological screens performed in clinic were all normal. AP and lateral radiographs showed a pathological process in 65% of cases, 35% being reported as normal (Table 2). Non-operative treatment prior to conversion was tried in 65% of patients (Table 3).The only modality to give favourable results was the use of an intra-articular injection of local anaesthetic and steroid, five out of the seven patients receiving the injection having short term pain relief. Operative findings at the time of conversion showed loosening of the prosthesis and acetabular cartilage degeneration as the main pathological processes leading to failure of the hemiarthroplasty (Table 4). Table 2 Plain X-ray (AP/LAT) results
Femoral loosening (translucent lines) \50% around prosthesis No calcar contact Migration prosthesis Protrusion Normal
Physiotherapy Heel raise Intra-articular local anaesthetic Walking aid No treatment
n
%
9 4 7 10 16
20 9 15 21 35
Following conversion to total hip replacement, 88% of patients had complete resolution of symptoms with return to a pain free daily living pattern and a good functional range of movement. Radiological assessment showed no evidence of early prosthetic migration or radiolucencies. Survivorship analysis of the patients once they had been converted showed three deaths within the 1 year of follow-up and no revision procedures. There were two superficial wound infections which responded to short courses of antibiotic therapy. There were no reported incidences of deep infection or dislocations.
4. Discussion The goal of treatment for displaced intra-capsular femoral neck fractures is to return the patient as rapidly as possible to their pre-injury functional state and to minimise the need for further operations [20]. The Austin Moore hemiarthroplasty has for decades fulfilled the above criteria [5,7,14,21– 25]. With increasing demands being placed on the prosthesis by fitter and more physically demanding patients there is a group of patients who develop early onset groin and thigh pain leading to a marked decrease in their quality of life. The question may be asked as to whether our initial management decision was correct, i.e. should any of the 46 failed hemiarthroplasties have had a different primary procedure to treat their fracture. The patients who required converting were 74 years of age or greater at the time of their original injury. They had a displaced intra-capsular fracture with most requiring polypharmaceuticals for multiple medical problems. With this background, we feel that Table 4 Operative findings at conversion
n
%
11
24
2 5 12 16
4 11 26 35
Femoral loosening Acetabular cartilage degeneration Femoral looseing and acetabular cartilage degeneration Trochanteric bursitis
n
%
22 8 14
48 17 31
2
4
A.J. Cossey, M.I. Goodwin / Injury, Int. J. Care Injured 33 (2002) 19–21
preservation of the femoral head by reduction and cannulated screw fixation would have a high risk of developing complications of fracture healing and therefore was not contemplated [21,25]. To perform primary total hip arthroplasty in this group of patients would also be fraught with many complications including an increased operating time, cardiovascular complications of cement usage and an increase in the overall dislocation rate [5,6,8,10]. We therefore felt that a simple and quick procedure would be the best primary procedure for these patients. Dorset has a static elderly population so we feel that very few patients, if any, would have proceeded to conversion in a different region. Pain following Austin Moore hemiarthroplasty is usually due to one of two pathological processes, articular cartilage degeneration in the acetabulum and loosening of the prosthesis in the proximal femur. These pathological processes are exacerbated by many factors including incongruencies between the femoral head and the acetabulum, the use of cement, excessive neck length, impaction at the time of injury, physiologically young, active patients and shear forces between the prosthesis and the cartilage [10,11,15– 17,23,24]. Our study showed that the best indicator of failure of the prosthesis is pain, either groin or thigh pain. Plain anteroposterior and lateral films do have a role in the assessment of the patient. Attempts should be made to exclude sepsis and haematological parameters should be checked (W.C.C., E.S.R. and C.R.P.). No patient in our study group had any evidence of infection. We found that conversion to a total hip replacement is very effective at alleviating symptoms and restoring the patient to a more satisfactory lifestyle [13,19,21,26]. Non operative forms of treatment gave poor results apart from intraarticular injections of steroid and local anaesthetic, which gave a therapeutic benefit to the patient and a diagnostic benefit to the surgeon. There is a group of patients who present early with pain following their hemiarthroplasty. Once infection has been ruled out as a cause of pain, early conversion to total joint arthroplasty should be undertaken. Our study showed that this gives an excellent therapeutic response with minimal complications.
References [1] Alffram PA. An epidemiologic study of cervical and trochanteric fracture of the femur in an urban population. Analysis of 1,664 cases with special reference to etiologic factors. Acta Orthop Scand 1964;I(Suppl.):65. [2] Boyce WJ, Vessey MP. Rising incidence of fracture of the proximal femur. Lancet 1985;I:150.
21
[3] Solomon L. Osteoporosis and the fracture of the femoral neck in the South Africa Bantu. J Bone Joint Surg [Br] 1968;50B:2. [4] Lewis FA. Fracture of neck of the femur: changing incidence. Br Med J 1981;283:1217. [5] Kyle RF, Cabanela ME, Russell TA, et al. Fractures of the proximal part of the femur. J Bone Joint Surg 1994;76A:924 –50. [6] Gebhard JS, Amstutz HC, Zinar DM, Dorey FJ. A comparison of total hip arthroplasty and hemiarthroplasty for treatment of acute fracture of the femoral neck. Clin Orthop Relat Res 1992;282:123 – 31. [7] Lunceford EM. Use of the Moore self-locking vitalium prosthesis in acute fractures of the femoral neck. J Bone Joint Surg 1965;47A:832. [8] Koval KJ, Zuckerman JD. Hip fractures: I. Overview and evaluation and treatment of FNFs. JAAOS 1994;2:141 – 9. [9] Kwok D, Cruess RL. A retrospective study of Moore and Thompson hemiarthroplasty. Clin Orthop 1982;169:179 –85. [10] Hinchey JJ, Day PL. Primary prosthetic replacement in fresh femoral-neck fractures: a review of 294 consecutive cases. J Bone Joint Surg [Am] 1964;46-A:223 – 40. [11] Anderson LD, Hamsa WR Jr, Waring TL. Femoral-head prosthesis. A review of three hundred and fifty operations and their results. J Bone Joint Surg 1964;46-A:1049 – 65. [12] D’Arcy J, Devas M. Treatment of fractures of the femoral neck by replacement with the Thompson prosthesis. J Bone Joint Surg 1976;58-B(3):279 – 86. [13] Massie WK. Treatment of femoral neck fractures emphasising long-term follow-up observations on aseptic necrosis. Clin Orthop 1973;92:16. [14] Jalovaara P, Virkkunen H. Quality of life after primary hemiarthroplasty for femoral neck fracture: 6-year follow up of 185 patients. Acta Orthop Scand 1991;62:208. [15] Cook SD, Thomas KA, Kester MA. Wear characteristics of the canine acetabulum against different temoral prosthesis. J Bone Joint Surg 1989;71-B(2):189 – 97. [16] Cruess RL, Kwok DC, Duc PN, Lecavalier MA, Dang GT. The response of articular cartilage to weight bearing against metal. A study of hemiarthroplasty of the hip in the dog. J Bone Joint Surg 1984;66-B(4):592 – 7. [17] Kaltsas DS, Klugman DJ. Acetabular erosion: a comparison between the Austin Moore and Monk hard top prosthesis. Injury 1986;17:230 – 6. [18] Phillips TW. Thompson hemiarthroplasty and acetabular erosion. J Bone Joint Surg 1989;71A:913 – 7. [19] Nilsson LT, Stro¨ mqvist B, Thorngren KG. Nailing of femoral neck fracture: clinical and sociologic 5-year follow up of 510 consecutive hips. Acta Orthop Scand 1988;59:365. [20] Dorr LD, Glousman R, Hoy ALS, et al. Treatment of femoral neck fractures with total hip replacement versus cemented and non-cemented hemiarthroplasty. J Arthroplasty 1986;1:21 –8. [21] Kofoed H, Kofoed J. Moore prosthesis in the treatment of fresh femoral neck fractures. A critical review with special attention to secondary acetabular degeneration. Injury 1983;14:531 – 40. [22] Moore AT, Bohlman HR. Metal hip joint. J Bone Joint Surg 1943;25:688 – 92. [23] Gingras MB, Clarke J, Evart CM. Prosthesis replacement in femoral neck fracture. Clin Orthop 1980;152:147. [24] Andersson G, M(ller-Nielsen J. Results after arthroplasty of the hip with Moore’s prosthesis. Acta Orthop Scand 1972;43:39. [25] Pun WK, Chow SP, Ip FK, Chan KC, Leong JCY. Long term follow up of Austin Moore hemiarthroplasty for femoral neck fractures. JR Coll Surg Edinb 1988;33:299 – 302. [26] Greenough CG, Jones JR. Primary total hip replacement for displaced subcapital fractures of the femur. J Bone Joint Surg 1988;70B:639.
Failure of Austin Moore hemiarthroplasty: total hip replacement as a treatment strategy A.J. Cossey *, M.I. Goodwin Royal Bournemouth Hospital, Bournemouth, UK Accepted 12 June 2001
Abstract Forty six patients who underwent conversion of their Austin Moore hemiarthroplasty to a total hip replacement were assessed clinically and radiologically. Forty patients requiring conversion had either groin or thigh pain. Operative findings showed acetabular cartilage degeneration and femoral loosening as the main pathological process causing their symptoms. Total hip replacement gave complete resolution of the symptoms in 41 patients. We propose early conversion to total joint arthroplasty in patients with painful hemiarthroplasties. © 2002 Elsevier Science Ltd. All rights reserved.
1. Introduction Femoral neck fractures are occurring with increasing frequency [1,2] accounting for considerable morbidity and mortality in the osteoporotic population in industrialised western countries [3]. A total of 20% of orthopaedic beds in the UK are occupied by patients with such fractures and with greater numbers of active geriatric patients [4], the number of hemiarthroplasty procedures being performed will rise accordingly. Austin Moore hemiarthroplasties have favourable long-term follow-up data in the treatment of displaced femoral neck fractures [5 – 11]. Insertion is relatively straightforward allowing early mobilisation and restoration to a functional level of activity, therefore decreasing the overall morbidity and mortality to the patient [12]. However, long term results of the prosthesis also show associations with acetabular cartilage degeneration [12,15 – 18] and femoral loosening [13,14]. With 50% of the femoral neck fracture population surviving for 5 years or greater [14,19] long-term complications associated with the prosthesis will continue to rise. The aim of this study was to show that conversion to a total hip replacement for symptomatic, failed hemi* Corresponding author. Present address: 68 Purewell, Christchurch, Dorset BH23 1ES, UK. Tel.: +44-1202-480-057; fax: +44-1705-286-570.
arthroplasties is an excellent management strategy to give the patient a pain-free, functionally acceptable lifestyle.
2. Materials and methods From January 1st 1992 until 31st December 1996 a total of 46 patients underwent conversion of their Austin Moore hemiarthroplasty to a total hip replacement. These patients were referred back to orthopaedic clinics from their primary care team as no routine follow up for hemiarthroplasties is conducted at our institution. The patients were clinically and radiologically assessed by an Orthopaedic Surgeon (38 Consultant, eight Registrar/Staff Grades). Investigations conducted in clinic included a septic screen (full blood count, ESR, CRP) and plain anteroposterior and lateral X-rays of the symptomatic hip. Radiological examination assessed abnormal position of the prosthesis, inadequate contact with the calcar, descent of the prosthesis into the femur, radiolucencies around the prosthesis and protrusio acetabulae (medial migration of the prosthetic head beyond Kohler’s line) [21,25,26]. Treatment strategies prior to conversion were also reviewed. At operation the condition of the articular cartilage in the acetabulum, the stability of the prosthesis in the
0020-1383/02/$ - see front matter © 2002 Elsevier Science Ltd. All rights reserved. PII: S 0 0 2 0 - 1 3 8 3 ( 0 1 ) 0 0 0 9 6 - 1
20
A.J. Cossey, M.I. Goodwin / Injury, Int. J. Care Injured 33 (2002) 19–21 Table 3 Non-operative treatment prior to conversion
Table 1 Clinical findings at outpatient clinic assessment
Pain Pain and antalgic gait Pain and leg length discrepancy Pain antalgic gait and leg length discrepancy
n
%
18 12 14 2
39 26 30 5
proximal femur and any other associated pathological conditions found were documented by the surgeon. Clinical and radiological assessment of the patient’s 1-year post conversion to total hip replacement were conducted in routine orthopaedic clinics.
3. Results Of the 46 patients presenting with symptomatic hemiarthroplasties, 33 were female and 13 were male. Their mean age at the time of conversion was 76.1 years. Forty of the patients had experienced pain since the early rehabilitation phase following their hemiarthroplasty, sufficient to affect their sleep pattern and activities of daily living. The pain was located either in the groin and/or thigh and was associated with either an antalgic gait or a leg length discrepancy (Table 1). The mean time lapse from hemiarthroplasty insertion to presentation to clinic was 5.81 months. During this time period over 1900 Austin Moore Hemiarthroplasties were inserted. Haematological screens performed in clinic were all normal. AP and lateral radiographs showed a pathological process in 65% of cases, 35% being reported as normal (Table 2). Non-operative treatment prior to conversion was tried in 65% of patients (Table 3).The only modality to give favourable results was the use of an intra-articular injection of local anaesthetic and steroid, five out of the seven patients receiving the injection having short term pain relief. Operative findings at the time of conversion showed loosening of the prosthesis and acetabular cartilage degeneration as the main pathological processes leading to failure of the hemiarthroplasty (Table 4). Table 2 Plain X-ray (AP/LAT) results
Femoral loosening (translucent lines) \50% around prosthesis No calcar contact Migration prosthesis Protrusion Normal
Physiotherapy Heel raise Intra-articular local anaesthetic Walking aid No treatment
n
%
9 4 7 10 16
20 9 15 21 35
Following conversion to total hip replacement, 88% of patients had complete resolution of symptoms with return to a pain free daily living pattern and a good functional range of movement. Radiological assessment showed no evidence of early prosthetic migration or radiolucencies. Survivorship analysis of the patients once they had been converted showed three deaths within the 1 year of follow-up and no revision procedures. There were two superficial wound infections which responded to short courses of antibiotic therapy. There were no reported incidences of deep infection or dislocations.
4. Discussion The goal of treatment for displaced intra-capsular femoral neck fractures is to return the patient as rapidly as possible to their pre-injury functional state and to minimise the need for further operations [20]. The Austin Moore hemiarthroplasty has for decades fulfilled the above criteria [5,7,14,21– 25]. With increasing demands being placed on the prosthesis by fitter and more physically demanding patients there is a group of patients who develop early onset groin and thigh pain leading to a marked decrease in their quality of life. The question may be asked as to whether our initial management decision was correct, i.e. should any of the 46 failed hemiarthroplasties have had a different primary procedure to treat their fracture. The patients who required converting were 74 years of age or greater at the time of their original injury. They had a displaced intra-capsular fracture with most requiring polypharmaceuticals for multiple medical problems. With this background, we feel that Table 4 Operative findings at conversion
n
%
11
24
2 5 12 16
4 11 26 35
Femoral loosening Acetabular cartilage degeneration Femoral looseing and acetabular cartilage degeneration Trochanteric bursitis
n
%
22 8 14
48 17 31
2
4
A.J. Cossey, M.I. Goodwin / Injury, Int. J. Care Injured 33 (2002) 19–21
preservation of the femoral head by reduction and cannulated screw fixation would have a high risk of developing complications of fracture healing and therefore was not contemplated [21,25]. To perform primary total hip arthroplasty in this group of patients would also be fraught with many complications including an increased operating time, cardiovascular complications of cement usage and an increase in the overall dislocation rate [5,6,8,10]. We therefore felt that a simple and quick procedure would be the best primary procedure for these patients. Dorset has a static elderly population so we feel that very few patients, if any, would have proceeded to conversion in a different region. Pain following Austin Moore hemiarthroplasty is usually due to one of two pathological processes, articular cartilage degeneration in the acetabulum and loosening of the prosthesis in the proximal femur. These pathological processes are exacerbated by many factors including incongruencies between the femoral head and the acetabulum, the use of cement, excessive neck length, impaction at the time of injury, physiologically young, active patients and shear forces between the prosthesis and the cartilage [10,11,15– 17,23,24]. Our study showed that the best indicator of failure of the prosthesis is pain, either groin or thigh pain. Plain anteroposterior and lateral films do have a role in the assessment of the patient. Attempts should be made to exclude sepsis and haematological parameters should be checked (W.C.C., E.S.R. and C.R.P.). No patient in our study group had any evidence of infection. We found that conversion to a total hip replacement is very effective at alleviating symptoms and restoring the patient to a more satisfactory lifestyle [13,19,21,26]. Non operative forms of treatment gave poor results apart from intraarticular injections of steroid and local anaesthetic, which gave a therapeutic benefit to the patient and a diagnostic benefit to the surgeon. There is a group of patients who present early with pain following their hemiarthroplasty. Once infection has been ruled out as a cause of pain, early conversion to total joint arthroplasty should be undertaken. Our study showed that this gives an excellent therapeutic response with minimal complications.
References [1] Alffram PA. An epidemiologic study of cervical and trochanteric fracture of the femur in an urban population. Analysis of 1,664 cases with special reference to etiologic factors. Acta Orthop Scand 1964;I(Suppl.):65. [2] Boyce WJ, Vessey MP. Rising incidence of fracture of the proximal femur. Lancet 1985;I:150.
21
[3] Solomon L. Osteoporosis and the fracture of the femoral neck in the South Africa Bantu. J Bone Joint Surg [Br] 1968;50B:2. [4] Lewis FA. Fracture of neck of the femur: changing incidence. Br Med J 1981;283:1217. [5] Kyle RF, Cabanela ME, Russell TA, et al. Fractures of the proximal part of the femur. J Bone Joint Surg 1994;76A:924 –50. [6] Gebhard JS, Amstutz HC, Zinar DM, Dorey FJ. A comparison of total hip arthroplasty and hemiarthroplasty for treatment of acute fracture of the femoral neck. Clin Orthop Relat Res 1992;282:123 – 31. [7] Lunceford EM. Use of the Moore self-locking vitalium prosthesis in acute fractures of the femoral neck. J Bone Joint Surg 1965;47A:832. [8] Koval KJ, Zuckerman JD. Hip fractures: I. Overview and evaluation and treatment of FNFs. JAAOS 1994;2:141 – 9. [9] Kwok D, Cruess RL. A retrospective study of Moore and Thompson hemiarthroplasty. Clin Orthop 1982;169:179 –85. [10] Hinchey JJ, Day PL. Primary prosthetic replacement in fresh femoral-neck fractures: a review of 294 consecutive cases. J Bone Joint Surg [Am] 1964;46-A:223 – 40. [11] Anderson LD, Hamsa WR Jr, Waring TL. Femoral-head prosthesis. A review of three hundred and fifty operations and their results. J Bone Joint Surg 1964;46-A:1049 – 65. [12] D’Arcy J, Devas M. Treatment of fractures of the femoral neck by replacement with the Thompson prosthesis. J Bone Joint Surg 1976;58-B(3):279 – 86. [13] Massie WK. Treatment of femoral neck fractures emphasising long-term follow-up observations on aseptic necrosis. Clin Orthop 1973;92:16. [14] Jalovaara P, Virkkunen H. Quality of life after primary hemiarthroplasty for femoral neck fracture: 6-year follow up of 185 patients. Acta Orthop Scand 1991;62:208. [15] Cook SD, Thomas KA, Kester MA. Wear characteristics of the canine acetabulum against different temoral prosthesis. J Bone Joint Surg 1989;71-B(2):189 – 97. [16] Cruess RL, Kwok DC, Duc PN, Lecavalier MA, Dang GT. The response of articular cartilage to weight bearing against metal. A study of hemiarthroplasty of the hip in the dog. J Bone Joint Surg 1984;66-B(4):592 – 7. [17] Kaltsas DS, Klugman DJ. Acetabular erosion: a comparison between the Austin Moore and Monk hard top prosthesis. Injury 1986;17:230 – 6. [18] Phillips TW. Thompson hemiarthroplasty and acetabular erosion. J Bone Joint Surg 1989;71A:913 – 7. [19] Nilsson LT, Stro¨ mqvist B, Thorngren KG. Nailing of femoral neck fracture: clinical and sociologic 5-year follow up of 510 consecutive hips. Acta Orthop Scand 1988;59:365. [20] Dorr LD, Glousman R, Hoy ALS, et al. Treatment of femoral neck fractures with total hip replacement versus cemented and non-cemented hemiarthroplasty. J Arthroplasty 1986;1:21 –8. [21] Kofoed H, Kofoed J. Moore prosthesis in the treatment of fresh femoral neck fractures. A critical review with special attention to secondary acetabular degeneration. Injury 1983;14:531 – 40. [22] Moore AT, Bohlman HR. Metal hip joint. J Bone Joint Surg 1943;25:688 – 92. [23] Gingras MB, Clarke J, Evart CM. Prosthesis replacement in femoral neck fracture. Clin Orthop 1980;152:147. [24] Andersson G, M(ller-Nielsen J. Results after arthroplasty of the hip with Moore’s prosthesis. Acta Orthop Scand 1972;43:39. [25] Pun WK, Chow SP, Ip FK, Chan KC, Leong JCY. Long term follow up of Austin Moore hemiarthroplasty for femoral neck fractures. JR Coll Surg Edinb 1988;33:299 – 302. [26] Greenough CG, Jones JR. Primary total hip replacement for displaced subcapital fractures of the femur. J Bone Joint Surg 1988;70B:639.