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Critical radiological analysis after Austin Moore hemiarthroplasty
Injury, Int. J. Care Injured (2004) 35, 1020—1024
Critical radiological analysis after Austin Moore hemiarthroplasty W.P. Yau*, K.Y. Chiu Department of Orthopaedic Surgery, The University of Hong Kong, Queen Mary Hospital, No. 102, Pokfulam Road, Hong Kong, PR China Accepted 28 August 2003
KEYWORDS Austin Moore hemiarthroplasty; Loosening; Stem fitness
Summary The aim of this study is to investigate the causes of prosthesis loosening in patients treated with Austin Moore hemiarthroplasty (AMA). The clinical and radiological outcomes were documented in a quantitative manner after 7 years follow-up of 144 patients. At the time of final follow-up, 52 patients had died and 48 patients were lost to follow-up, leaving a total of 44 patients for analysis. Immediate postoperative X-rays were studied for the initial alignment of prosthesis, the fit of the prosthesis and the degree of osteoporosis. X-rays on latest follow-up were studied for evidence of loosening. All patients were assessed clinically with the hip score of hospital for special surgery. It was found that hip pain was significantly related to subsidence and pivoting of the prosthesis (P ¼ 0:014 and 0.035, respectively). Significant increase in subsidence was noted if the stem of prosthesis was not fitting well within the shaft of femur (P ¼ 0:006). When the patient was younger than 73 years old at the time of operation, there was more subsidence of the prosthesis at the final follow-up (P ¼ 0:001). It was concluded that the fill of AMA within the shaft of femur should be greater than 70% to avoid early loosening. Relatively younger patients with acute fracture of the neck of femur should be treated by methods other than cementless AMA. ß 2003 Elsevier Ltd. All rights reserved.
Introduction Austin Moore hemiarthroplasty (AMA) is one of the commonly used methods in the treatment of displaced intra-capsular fracture of the neck of femur, especially in the geriatric age group.15 It allows patient to start early weight bearing, walking in a relatively pain free condition. However, complications, such as infection, dislocation, periprosthetic fracture, acetabular protrusion and loosening of *Corresponding author. Tel.: þ852-2855-4256; fax: þ852-2817-4392. E-mail address: [email protected] (W.P. Yau).
prosthesis do occur from time to time. These may lead to the need for revision, and the re-operation rate ranges from 4.5 to 24%.4,5,11,14 This paper addresses the problem of femoral stem loosening and attempts to investigate the possible causes of this.
Methodology A total of 144 consecutive Austin Moore hemiarthroplasties were performed for acute displaced fracture neck of femur in our institution. These patients were followed up with regular clinical
0020–1383/$ — see front matter ß 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.injury.2003.08.016
Critical radiological analysis after AMA
Table 1
Hip rating system of hospital for special surgery
Pain
Muscle power (MP) and motiona
0 2 4 6 8 10 0 2 4 6 8 10
Walking
0 2 4
Functional
All the time; unbearable; strong medication frequently All the time but bearable; strong medication essential; salicylates frequently None or little at rest; with activities; salicylates frequently When starting, then better, or after a certain activity; salicylates occasional Occasional and slight No pain Ankylosis with deformity Ankylosis with good functional position MP, poor to fair; arc of flexion less than 608; restricted lateral and rotary movement MP, fair to good; arc of flexion up to 908; fair lateral (108 abduction, 108 adduction) and rotary (108 internal rotation, 208 external rotation) movement MP, good or normal; arc of flexion over 908; good lateral (208 abduction, 208 adduction) and rotary (208 internal rotation, 408 external rotation) movement MP, normal; motion, normal or almost normal
8 10
Bedridden Wheelchair; transfer activities with walker Markedly restricted; no support–—house bound or one support–—less than one block or bilateral support–—less than three blocks Moderately restricted; no support–—less than one block or one support–—up to five blocks or bilateral support–—unrestricted Mildly restricted; no support–—limp or one support–—no limp Unrestricted; no support or appreciable limp
0 2 4 6 8 10
Completely dependent and confined Partially dependent Independent; limited housework, shops limitedly Most housework, shops freely, desk type work Very little restriction, can work on feet Normal activities
6
a
1021
Precedence was given to active movements.
and radiological assessment. Fifty-two patients had died at the final follow-up. Forty-eight patients defaulted follow-up. Forty-four patients were available for recruitment into this study. The mean follow-up was 3:5 1:1 years (range 2—7 years). Patients were assessed clinically according to the hip rating system of hospital for special surgery (Table 1).16 Radiographs of the immediate postoperative period were compared with that of the latest follow-up. The degree of osteoporosis at the time of operation was assessed according to the Singh index.12 The initial alignment of the prosthesis (varus, neutral or valgus) was documented (Fig. 1). The relative fill of the implanted prosthesis on the AP X-ray was measured by calculating the fill of the prosthetic stem in the medullary canal at the level of lesser trochanter (Fig. 2). In the latest follow-up X-ray, any migration of prosthesis, in terms of change of position of prosthesis (pivoting) and subsidence were assessed. Presence of calcar resorption was noted. The degree of osteoporosis at the time of operation, the initial alignment of prosthesis, the relative
fill of prosthetic stem on the AP X-ray and the clinical outcome were correlated with the final X-ray changes. Bivariate correlation, independent Student’s t-test and chi-square test were used wherever appropriate. Statistical significance was assumed if P < 0:05.
Figure 1 The alignment of prosthesis in the early postoperative X-ray (the alignment of the prosthesis was defined by the relative position of the tip of the prosthesis to the inner cortex of shaft of femur).
1022
W.P. Yau, K.Y. Chiu
Figure 2 Relative fill of the stem of prosthesis to the medullary canal of femur at the level of lesser trochanter on AP X-ray (A and B).
Results There were 5 male and 39 female patients. The average age at the time of operation was 75:8 6:5 years (range 62—92). The duration of follow-up ranged from 24 to 84 months (mean 43.3; S.D. 13.6). Thirty-six patients had a Singh index of less than three and were classified as osteoporotic. The mean hip score of hospital for special surgery was 26.3 (S.D. 6.0; range 12—40). Forty patients had minimal or no pain (pain score <8) on followup. Twenty-eight patients were frequent walkers (walking score >6). Concerning the initial alignment during insertion of the prosthesis; 14 were put in
varus, 26 in neutral and 4 in valgus position. There were nine cases showing a change in the alignment, such as varus pivoting, in the radiographs at the latest follow-up. The fill of the stem of prosthesis at the level of calcar femorae on AP X-ray ranged from 63 to 96% (mean 79.0%; S.D. 6.7%). The mean subsidence was 3:9 4:3 mm (range 0—21.9 mm). Complete calcar resorption was observed in two patients only. Twenty-one patients were found to have partial calcar resorption. Hip pain at follow-up was found to be significantly related to subsidence (P ¼ 0:014; independent sample t-test) and pivoting of the prosthesis (P ¼ 0:035; independent sample t-test). The fill of the stem of prosthesis within the shaft of femur on AP X-ray was found to be significantly related to the degree of subsidence (P ¼ 0:006 if fill <70%, independent sample t-test) (Fig. 3). It was observed that when the patient was younger at the time of operation, there was more subsidence of the prosthesis (P ¼ 0:001 if age <73 years at operation, independent sample t-test) (Fig. 4). Linear regression was carried out to test the relative significance of the fill of stem of prosthesis and the age of patients in determining the degree of subsidence of the prosthesis. It was found that age of patient at the time of index surgery was the most significant factor in determining the final subsidence. No significant relationship was demonstrated between walking status and the long term radiological changes. The initial alignment (varus or valgus) was found to have no significant correlation with the radiological changes at the final follow-up. Calcar resorption was not related to the clinical outcome, initial fit of stem, nor subsidence at the latest follow-up.
Figure 3 Relationship of fill of AMA stem within the femur on AP X-ray with subsidence at follow-up.
Critical radiological analysis after AMA
Figure 4 Relationship of age of patients at index surgery with subsidence at follow-up.
Discussion Austin Moore hemiarthroplasty was originally designed for cementless application. Its initial stability inside the proximal femur depends on the principle of three point fixation with bone metal contact at multiple points. Fenestration over the proximal stem allows bone bar to form and this may add to an increase in stability. However, with the advance of total hip replacement and improvement in the understanding of biomechanics around the hip, the design and instrumentation of Austin Moore hemiarthroplasty can be considered to be rather primitive. AMA still serves as one of the commonly employed methods in treatment of geriatric fracture neck of femur.6 This is related to the relatively low cost, short duration of operation, acceptable intra-operative bleeding and reasonable clinical outcomes.7,10,11 In order to reduce the need of re-operation, it is important to identify the factors which lead to poor clinical outcomes. Symptomatic femoral loosening is one of the causes which lead to revision. The possible signs of femoral loosening include varus pivoting,9 subsidence,13 osteolysis along the stem of prosthesis1— 3,13 and lack of ossification in the fenestration hole of prosthesis.8 In this paper, we used significant subsidence and prosthesis migration (pivoting) as our definition of femoral loosening and we were able to show significant association of pain with these two parameters (P ¼ 0:014 and 0.035; independent sample t-test). Initial stability of Austin Moore hemiarthroplasty depends on multiple points of bone metal contact. Adequate fill of the prosthetic stem within the femur is important to ensure the prosthesis is sitting on the good quality cancellous bone in the periphery or even the cortical bone. We advocated a minimum
1023
of 70% canal fill by the stem of the prosthesis at the level of lesser trochanter on AP X-ray to avoid excessive subsidence of the prosthesis and pain (P ¼ 0:006, independent t-test). We failed to demonstrate any relationship between the degree of osteoporosis or the initial alignment of the AMA and radiological evidence of loosening at follow-up. Age was found to be significantly related to the degree of subsidence (P ¼ 0:038, bivariate correlation). Younger patients were more prone to have their implanted AMA subside (age < 73 years, subsidence ¼ 7.35 mm; age > 73 years, subsidence ¼ 2.64 mm; P ¼ 0:001, independent t-test). As a result, young patients with intra-capsular fracture neck of femur should be managed by methods other than Austin Moore hemiarthroplasty (e.g. internal fixation, total hip replacement, etc.).7,10,11 The issue of calcar resorption is complicated. If the initial contact between the collar of the AMA and the neck cut is good, stress will go from the collar of the prosthesis, through the calcar, down to the femoral shaft. Calcar resorption is expected to be absent or minimal. But, if the fit of the prosthesis to the medullary canal of the femur is excellent, stress may pass directly from the stem of the prosthesis to the shaft of the femur. Significant stress shielding and calcar resorption will occur. However, we failed to find any relationship between calcar resorption and clinical outcome. This series began with a total of 144 patients. At the time of final follow-up, only 44 patients were available for analysis. This was certainly one of the biggest limitations in this study. To conclude, Austin Moore hemiarthroplasty is a useful operation in treatment of intracapsular fracture neck of femur. However, careful selection of patients (e.g. more suitable for the geriatric age group) and observation of the technique in implanation (that is, optimize the fill of the prosthesis within the medullary canal) are mandatory for satisfactory clinical outcome and prolonging the survivorship of this prosthesis.
References 1. Anderson LD, Hamsa Jr WR, Waring TL. Femoral-head prostheses. a review of three hundred and fifty-six operations and their results. J Bone Joint Surg 1964;46A:1049. 2. Andersson G, Nielsen JM. Results after arthroplasty of the hip with Moore’s prosthesis. Acta Orthop Scand 1972;43: 397. 3. Barr JS, Donovan JF, Florence DW. Arthroplasty of the hip. Theoretical and practical considerations with a followup study of prosthetic replacement of the femoral head at the massachusetts general hospital. J Bone Joint Surg 1964; 46A:249.
1024
4. Clayer M, Bruckner J. The outcome of Austin Moore hemiarthroplasty for fracture of the femoral neck. Am J Orthop 1997;26:681—4. 5. Cossey AJ, Goodwin MI. Failure of Austin Moore hemiarthroplasty: total hip replacement as a treatment strategy. Injury 2002;33:19—21. 6. Crossman PT, Khan RJK, MacDowell A, Gardner AC, et al. A survey of the treatment of displaced intracapsular femoral neck fractures in the UK. Injury 2002;33:383—6. 7. Heikkinen T, Wingstrand H, Partanen J, Thorngren KG, et al. Hemiarthroplasty or osteosynthesis in cervical hip fractures: matched-pair analysis in 892 patients. Arch Orthop Trauma Surg 2002;122:143—7. 8. Jensen JS, Holstein P. A long term follow-up of Moore arthroplasty in femoral neck fractures. Acta Orthop Scand 1975;46:764. 9. Johnston CE, Ripley LP, Bray CB. Primary endoprosthetic replacement for acute femoral neck fractures. A review of 150 cases. Clin Orthop 1982;167:123. 10. Parker MJ, Pryor GA. Internal fixation or arthroplasty for displaced cervical hip fractures in the elderly: a randomised
W.P. Yau, K.Y. Chiu
11.
12.
13.
14.
15. 16.
controlled trial of 208 patients. Acta Orthop Scand 2000; 71:440—6. Ravikumar KJ, Marsh G. Internal fixation versus hemiarthroplasty versus total hip arthroplasty for displaced subcapital fractures of femur–—13 year results of a prospective randomised study. Injury 2000;31:793—7. Singh M, Nagrath AR, Maini PS. Changes in trabecular pattern of the upper end of the femur as an index of osteoporosis. J Bone Joint Surg 1970;52A:457. Sonne-Holm S, Walter S, Jensen JS. Moore hemi-arthroplasty with and without bone cement in femoral neck fractures. A clinical controlled trial. Acta Orthop Scand 1982;53:953. Tellisi N, Wahab KH. Re-operations following Austin Moore hemiarthroplasty: a district hospital experience. Injury 2001;32:465—7. Tillberg. Treatment of fractures of the femoral neck by primary arthroplasty. Acta Orthop Scand 1976;47:209. Wilson Jr PD, Anstytz HC, Czerniecki A. Total hip replacement with fixation by acrylic cement. J Bone Joint Surg 1972;54A:207.
Critical radiological analysis after Austin Moore hemiarthroplasty W.P. Yau*, K.Y. Chiu Department of Orthopaedic Surgery, The University of Hong Kong, Queen Mary Hospital, No. 102, Pokfulam Road, Hong Kong, PR China Accepted 28 August 2003
KEYWORDS Austin Moore hemiarthroplasty; Loosening; Stem fitness
Summary The aim of this study is to investigate the causes of prosthesis loosening in patients treated with Austin Moore hemiarthroplasty (AMA). The clinical and radiological outcomes were documented in a quantitative manner after 7 years follow-up of 144 patients. At the time of final follow-up, 52 patients had died and 48 patients were lost to follow-up, leaving a total of 44 patients for analysis. Immediate postoperative X-rays were studied for the initial alignment of prosthesis, the fit of the prosthesis and the degree of osteoporosis. X-rays on latest follow-up were studied for evidence of loosening. All patients were assessed clinically with the hip score of hospital for special surgery. It was found that hip pain was significantly related to subsidence and pivoting of the prosthesis (P ¼ 0:014 and 0.035, respectively). Significant increase in subsidence was noted if the stem of prosthesis was not fitting well within the shaft of femur (P ¼ 0:006). When the patient was younger than 73 years old at the time of operation, there was more subsidence of the prosthesis at the final follow-up (P ¼ 0:001). It was concluded that the fill of AMA within the shaft of femur should be greater than 70% to avoid early loosening. Relatively younger patients with acute fracture of the neck of femur should be treated by methods other than cementless AMA. ß 2003 Elsevier Ltd. All rights reserved.
Introduction Austin Moore hemiarthroplasty (AMA) is one of the commonly used methods in the treatment of displaced intra-capsular fracture of the neck of femur, especially in the geriatric age group.15 It allows patient to start early weight bearing, walking in a relatively pain free condition. However, complications, such as infection, dislocation, periprosthetic fracture, acetabular protrusion and loosening of *Corresponding author. Tel.: þ852-2855-4256; fax: þ852-2817-4392. E-mail address: [email protected] (W.P. Yau).
prosthesis do occur from time to time. These may lead to the need for revision, and the re-operation rate ranges from 4.5 to 24%.4,5,11,14 This paper addresses the problem of femoral stem loosening and attempts to investigate the possible causes of this.
Methodology A total of 144 consecutive Austin Moore hemiarthroplasties were performed for acute displaced fracture neck of femur in our institution. These patients were followed up with regular clinical
0020–1383/$ — see front matter ß 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.injury.2003.08.016
Critical radiological analysis after AMA
Table 1
Hip rating system of hospital for special surgery
Pain
Muscle power (MP) and motiona
0 2 4 6 8 10 0 2 4 6 8 10
Walking
0 2 4
Functional
All the time; unbearable; strong medication frequently All the time but bearable; strong medication essential; salicylates frequently None or little at rest; with activities; salicylates frequently When starting, then better, or after a certain activity; salicylates occasional Occasional and slight No pain Ankylosis with deformity Ankylosis with good functional position MP, poor to fair; arc of flexion less than 608; restricted lateral and rotary movement MP, fair to good; arc of flexion up to 908; fair lateral (108 abduction, 108 adduction) and rotary (108 internal rotation, 208 external rotation) movement MP, good or normal; arc of flexion over 908; good lateral (208 abduction, 208 adduction) and rotary (208 internal rotation, 408 external rotation) movement MP, normal; motion, normal or almost normal
8 10
Bedridden Wheelchair; transfer activities with walker Markedly restricted; no support–—house bound or one support–—less than one block or bilateral support–—less than three blocks Moderately restricted; no support–—less than one block or one support–—up to five blocks or bilateral support–—unrestricted Mildly restricted; no support–—limp or one support–—no limp Unrestricted; no support or appreciable limp
0 2 4 6 8 10
Completely dependent and confined Partially dependent Independent; limited housework, shops limitedly Most housework, shops freely, desk type work Very little restriction, can work on feet Normal activities
6
a
1021
Precedence was given to active movements.
and radiological assessment. Fifty-two patients had died at the final follow-up. Forty-eight patients defaulted follow-up. Forty-four patients were available for recruitment into this study. The mean follow-up was 3:5 1:1 years (range 2—7 years). Patients were assessed clinically according to the hip rating system of hospital for special surgery (Table 1).16 Radiographs of the immediate postoperative period were compared with that of the latest follow-up. The degree of osteoporosis at the time of operation was assessed according to the Singh index.12 The initial alignment of the prosthesis (varus, neutral or valgus) was documented (Fig. 1). The relative fill of the implanted prosthesis on the AP X-ray was measured by calculating the fill of the prosthetic stem in the medullary canal at the level of lesser trochanter (Fig. 2). In the latest follow-up X-ray, any migration of prosthesis, in terms of change of position of prosthesis (pivoting) and subsidence were assessed. Presence of calcar resorption was noted. The degree of osteoporosis at the time of operation, the initial alignment of prosthesis, the relative
fill of prosthetic stem on the AP X-ray and the clinical outcome were correlated with the final X-ray changes. Bivariate correlation, independent Student’s t-test and chi-square test were used wherever appropriate. Statistical significance was assumed if P < 0:05.
Figure 1 The alignment of prosthesis in the early postoperative X-ray (the alignment of the prosthesis was defined by the relative position of the tip of the prosthesis to the inner cortex of shaft of femur).
1022
W.P. Yau, K.Y. Chiu
Figure 2 Relative fill of the stem of prosthesis to the medullary canal of femur at the level of lesser trochanter on AP X-ray (A and B).
Results There were 5 male and 39 female patients. The average age at the time of operation was 75:8 6:5 years (range 62—92). The duration of follow-up ranged from 24 to 84 months (mean 43.3; S.D. 13.6). Thirty-six patients had a Singh index of less than three and were classified as osteoporotic. The mean hip score of hospital for special surgery was 26.3 (S.D. 6.0; range 12—40). Forty patients had minimal or no pain (pain score <8) on followup. Twenty-eight patients were frequent walkers (walking score >6). Concerning the initial alignment during insertion of the prosthesis; 14 were put in
varus, 26 in neutral and 4 in valgus position. There were nine cases showing a change in the alignment, such as varus pivoting, in the radiographs at the latest follow-up. The fill of the stem of prosthesis at the level of calcar femorae on AP X-ray ranged from 63 to 96% (mean 79.0%; S.D. 6.7%). The mean subsidence was 3:9 4:3 mm (range 0—21.9 mm). Complete calcar resorption was observed in two patients only. Twenty-one patients were found to have partial calcar resorption. Hip pain at follow-up was found to be significantly related to subsidence (P ¼ 0:014; independent sample t-test) and pivoting of the prosthesis (P ¼ 0:035; independent sample t-test). The fill of the stem of prosthesis within the shaft of femur on AP X-ray was found to be significantly related to the degree of subsidence (P ¼ 0:006 if fill <70%, independent sample t-test) (Fig. 3). It was observed that when the patient was younger at the time of operation, there was more subsidence of the prosthesis (P ¼ 0:001 if age <73 years at operation, independent sample t-test) (Fig. 4). Linear regression was carried out to test the relative significance of the fill of stem of prosthesis and the age of patients in determining the degree of subsidence of the prosthesis. It was found that age of patient at the time of index surgery was the most significant factor in determining the final subsidence. No significant relationship was demonstrated between walking status and the long term radiological changes. The initial alignment (varus or valgus) was found to have no significant correlation with the radiological changes at the final follow-up. Calcar resorption was not related to the clinical outcome, initial fit of stem, nor subsidence at the latest follow-up.
Figure 3 Relationship of fill of AMA stem within the femur on AP X-ray with subsidence at follow-up.
Critical radiological analysis after AMA
Figure 4 Relationship of age of patients at index surgery with subsidence at follow-up.
Discussion Austin Moore hemiarthroplasty was originally designed for cementless application. Its initial stability inside the proximal femur depends on the principle of three point fixation with bone metal contact at multiple points. Fenestration over the proximal stem allows bone bar to form and this may add to an increase in stability. However, with the advance of total hip replacement and improvement in the understanding of biomechanics around the hip, the design and instrumentation of Austin Moore hemiarthroplasty can be considered to be rather primitive. AMA still serves as one of the commonly employed methods in treatment of geriatric fracture neck of femur.6 This is related to the relatively low cost, short duration of operation, acceptable intra-operative bleeding and reasonable clinical outcomes.7,10,11 In order to reduce the need of re-operation, it is important to identify the factors which lead to poor clinical outcomes. Symptomatic femoral loosening is one of the causes which lead to revision. The possible signs of femoral loosening include varus pivoting,9 subsidence,13 osteolysis along the stem of prosthesis1— 3,13 and lack of ossification in the fenestration hole of prosthesis.8 In this paper, we used significant subsidence and prosthesis migration (pivoting) as our definition of femoral loosening and we were able to show significant association of pain with these two parameters (P ¼ 0:014 and 0.035; independent sample t-test). Initial stability of Austin Moore hemiarthroplasty depends on multiple points of bone metal contact. Adequate fill of the prosthetic stem within the femur is important to ensure the prosthesis is sitting on the good quality cancellous bone in the periphery or even the cortical bone. We advocated a minimum
1023
of 70% canal fill by the stem of the prosthesis at the level of lesser trochanter on AP X-ray to avoid excessive subsidence of the prosthesis and pain (P ¼ 0:006, independent t-test). We failed to demonstrate any relationship between the degree of osteoporosis or the initial alignment of the AMA and radiological evidence of loosening at follow-up. Age was found to be significantly related to the degree of subsidence (P ¼ 0:038, bivariate correlation). Younger patients were more prone to have their implanted AMA subside (age < 73 years, subsidence ¼ 7.35 mm; age > 73 years, subsidence ¼ 2.64 mm; P ¼ 0:001, independent t-test). As a result, young patients with intra-capsular fracture neck of femur should be managed by methods other than Austin Moore hemiarthroplasty (e.g. internal fixation, total hip replacement, etc.).7,10,11 The issue of calcar resorption is complicated. If the initial contact between the collar of the AMA and the neck cut is good, stress will go from the collar of the prosthesis, through the calcar, down to the femoral shaft. Calcar resorption is expected to be absent or minimal. But, if the fit of the prosthesis to the medullary canal of the femur is excellent, stress may pass directly from the stem of the prosthesis to the shaft of the femur. Significant stress shielding and calcar resorption will occur. However, we failed to find any relationship between calcar resorption and clinical outcome. This series began with a total of 144 patients. At the time of final follow-up, only 44 patients were available for analysis. This was certainly one of the biggest limitations in this study. To conclude, Austin Moore hemiarthroplasty is a useful operation in treatment of intracapsular fracture neck of femur. However, careful selection of patients (e.g. more suitable for the geriatric age group) and observation of the technique in implanation (that is, optimize the fill of the prosthesis within the medullary canal) are mandatory for satisfactory clinical outcome and prolonging the survivorship of this prosthesis.
References 1. Anderson LD, Hamsa Jr WR, Waring TL. Femoral-head prostheses. a review of three hundred and fifty-six operations and their results. J Bone Joint Surg 1964;46A:1049. 2. Andersson G, Nielsen JM. Results after arthroplasty of the hip with Moore’s prosthesis. Acta Orthop Scand 1972;43: 397. 3. Barr JS, Donovan JF, Florence DW. Arthroplasty of the hip. Theoretical and practical considerations with a followup study of prosthetic replacement of the femoral head at the massachusetts general hospital. J Bone Joint Surg 1964; 46A:249.
1024
4. Clayer M, Bruckner J. The outcome of Austin Moore hemiarthroplasty for fracture of the femoral neck. Am J Orthop 1997;26:681—4. 5. Cossey AJ, Goodwin MI. Failure of Austin Moore hemiarthroplasty: total hip replacement as a treatment strategy. Injury 2002;33:19—21. 6. Crossman PT, Khan RJK, MacDowell A, Gardner AC, et al. A survey of the treatment of displaced intracapsular femoral neck fractures in the UK. Injury 2002;33:383—6. 7. Heikkinen T, Wingstrand H, Partanen J, Thorngren KG, et al. Hemiarthroplasty or osteosynthesis in cervical hip fractures: matched-pair analysis in 892 patients. Arch Orthop Trauma Surg 2002;122:143—7. 8. Jensen JS, Holstein P. A long term follow-up of Moore arthroplasty in femoral neck fractures. Acta Orthop Scand 1975;46:764. 9. Johnston CE, Ripley LP, Bray CB. Primary endoprosthetic replacement for acute femoral neck fractures. A review of 150 cases. Clin Orthop 1982;167:123. 10. Parker MJ, Pryor GA. Internal fixation or arthroplasty for displaced cervical hip fractures in the elderly: a randomised
W.P. Yau, K.Y. Chiu
11.
12.
13.
14.
15. 16.
controlled trial of 208 patients. Acta Orthop Scand 2000; 71:440—6. Ravikumar KJ, Marsh G. Internal fixation versus hemiarthroplasty versus total hip arthroplasty for displaced subcapital fractures of femur–—13 year results of a prospective randomised study. Injury 2000;31:793—7. Singh M, Nagrath AR, Maini PS. Changes in trabecular pattern of the upper end of the femur as an index of osteoporosis. J Bone Joint Surg 1970;52A:457. Sonne-Holm S, Walter S, Jensen JS. Moore hemi-arthroplasty with and without bone cement in femoral neck fractures. A clinical controlled trial. Acta Orthop Scand 1982;53:953. Tellisi N, Wahab KH. Re-operations following Austin Moore hemiarthroplasty: a district hospital experience. Injury 2001;32:465—7. Tillberg. Treatment of fractures of the femoral neck by primary arthroplasty. Acta Orthop Scand 1976;47:209. Wilson Jr PD, Anstytz HC, Czerniecki A. Total hip replacement with fixation by acrylic cement. J Bone Joint Surg 1972;54A:207.