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Natural history of impacted subcapital femoral fractures and its relevance to treatment options
Injury (1990) 21, 379-381
Printed in Great Britain
379
Natural history of impacted subcapital femoral fractures and its relevance to treatment options I. Otremskil, A. Katz’, S. Deke12, R. Salama’ and R. J. Newman3 ‘Ichilov Hospital, Tel-Aviv, Israel ?Soroko Hospital, Beer Sheba, Israel 3St James’s University Hospital,. Leeds, UK
A siudy of 723 patients with impacted, subcapital femoral fractures was undertaken to a%mine the natural history of this injury. It wasfound that the angle of the fracture, the degree of valgus and the a&a of retrovmion were without signij?ant e,$ect on the incia&ce of subsequent disimpacfion. Age was important, with a 20 per cent incia%nce of dtimpaction in patients over the age of 68 years. In patients younger than this the in&&me was only 2 per cent. These results indicate that conservative treatment may be appropriate for some younger patienk, but the &vantages of this approach mwt be compared with the medical, social and economic benejts of urly mobilization that the rehtively simpk operalive proczdure permits.
Introduction Most impacted subcapital femoral fractures are stable and heal with conservative treatment. Some, however, are unstable and disimpaction may occur even when the patient is confined to bed. Since there are no published criteria which satisfactorily differentiate the stable from the unstable fracture, internal fixation tends to be routinely practised on all such injuries (Boyd and Salvatore, 1964; Bentley, 1968, 1980). Until recently conservative treatment in the form of protected partial weight bearing was the method of choice for this fracture in our department, and this paper reviews our results in an attempt to determine the natural history of this injury and to define risk factors and indications for internal fixation.
Methods Patients A series of 123 consecutive patients with impacted subcapital femoral fractures were admitted to this hospital and were initially treated conservatively. The female to male ratio was 11: 1.3, the mean age was 65.6 f 9.2 years and the mean length of follow-up was 3 years. The fractures were defined as impacted when, on admission, the head of the femur was in valgus with penetration of the fragments superiorly, even in the presence of a breach in the inferior cortex in the anteroposterior radiograph or slight separation of the fragments anteriorly in the lateral 0 1990 Butterworth-Heinemann 0020-1383/90/060379-03
Ltd
radiograph. The fracture was considered disimpacted if the femoral head was in varus. The records were studied and surviving patients were examined and the functional results evaluated according to pain, limitation of movement and gait. The following angles were measured on the radiographs taken on admission: the angle of the fracture (Pauwel’s P-angle; Pauwels, 1935) and the angulation of the trabeculae both on the anteroposterior radiographs indicating the degree of valgus (Garden’s G-angle; Garden, 1971) and on the lateral radiographs indicating retroversion (Garden’s lateral angle; Garden, 1971). All subsequent radiographs were studied for evidence of displacement, union or avascular necrosis. The results were analysed statistically to determine the influence of each factor on disimpaction (x” Pearson test; Student’s t test). Treatment protocol All patients were treated non-operatively initially. Immediate partial weight bearing was permitted in 94 patients (76 per cent) and 3-4 days later, when radiographs did not show any change in the position of the fracture, they were discharged. After further satisfactory radiographs 6-8 weeks later they were allowed to bear full weight but with sticks until bony union was achieved. The 29 patients (24 per cent) in whom weight bearing was considered imprudent because of obesity or frailty were treated by rest in bed or in a chair for 2 months.
Results There were no significant differences between the two groups of patients with regard to age, demography or radiology. Disimpaction Disimpaction (Table I) occurred in 11 patients (8.9 per cent) overall within 2 to 80 days: four within the first 2 weeks, three between 2 and 4 weeks, three between 5 and 8 weeks and one disimpacted after 11 weeks. Although disimpaction was apparently higher in patients treated by immediate weight bearing the difference was not satistically significant. Similarly, there was no significant correlation between the incidence of disimpaction and the P-angle of the fracture,
Injury: the British Journal of Accident Surgery (1990) Vol. Zl/No. 6
380
Table I. The incidence of disimpaction according to management
Immediate weight bearing Non-weight bearing
Total
Number of patients
Disimpaction
Percentage
94
10
10.6
29
1
3.4
123
11
8.9
the G-angle of valgus or the G-lateral angle of retroversion.
The mean age of the II patients with disimpaction was significantly higher (73 years) than the average age of all patients (65.5 years) and that of patients without disimpaction (64.8 years) (PC 0.01). Similarly, in patients treated by immediate weight bearing the mean age of patients with disimpaction was significantly higher (73.3 years) than the mean age of the whole group (66.7 years) and that of patients without disimpaction (65.9 years) (PC 0.01). The incidence of disimpaction in all patients tip fo a given age ‘A’ was compared with the incidence of disimpaction in all patients over that same given age ‘A’ and the statistical significance of each comparison was estimated. Comparisons were made for all ages from 57 to 80 years and this showed increasing incidence of disimpaction with age. The incidence of disimpaction in any group of patients above any given age ‘A’ was always higher than the incidence in the remaining group of patients below the age ‘A’ and the statistical significance of this difference was maximal at 68 years. Disimpaction occurred in 20 per cent of patients over the age of 68 years compared with only 2 per cent in those under 68 years. Healing All fractures which remained displacement within 6 months.
impacted
healed
without
Avascular necrosis Avascular necrosis occurred in 8 per cent of patients between 10 and 27 months, but none required surgical treatment during the period of this study. There was no significant difference in the incidence of avascular necrosis between those treated by immediate or delayed weight bearing. Function All surviving patients were reviewed and of those treated by partial non-weight bearing 47 per cent had an excellent result (no pain or limp and minimal limitation of movement), 47 per cent had a good result (mild transient pain, minimal limp or slight limitation of movement) and 6 per cent had a poor result (almost constant pain and significant limitation of movement and walking ability). Of those treated by immediate weight bearing, the functional results were insignificantly different with 45 per cent being rated as excellent and 55 per cent as good.
Discussion Disimpaction is the most important complication of conservative treatment of previously impacted fractures of the femoral neck. Provided the fracture remains impacted, healing usually ensues with good functional results. The risk of disimpaction is therefore the main objection to nonoperative treatment.
It is generally agreed that an increase in the Pauwel’s angle is associated with a poorer prognosis (Bunata et al., 1973; Crenshaw, 1987). It indicates either an increase in the degree of displacement or an increasing instability due to increase in the shearing forces which tend to displace the fracture. This is probably the reason why the degree of obliquity of the fracture line is the principal parameter which has been investigated previously (Crawford, 1960; Flatmark and Lone, 1960; Hansen and Solgaard, 1978). Bunata et al. (1973) concluded that there was significant correlation between stability of the fracture and the Pauwel’s angle, but this was not substantiated in our study. A possible explanation for these contradictions in the prognostic value of the Pauwel’s angle is that the measurements are generally made without consideration for the effect of varying degrees of rotation of the hip at the time the radiograph was taken. This is particularly important since the subcapital fracture is spiral (Lmton, 1949) and the fracture line appears differently if the limb is in different degrees of rotation (Bentley, 1980). Impacted fractures are more common in a younger age group than that affected by displaced fractures (Liiton, 1944, 1949; Eklund and Erikson, 1964; Bentley, 1980). Similarly, Hansen and Solgaard (1978) observed that the average age of those patients whose fractures disimpacted was 82 years compared with an average age of 74 years for those whose fractures remained impacted. Otherwise, age has generally attracted relatively little attention with regard to its effect on disimpaction, but the present paper has demonstrated a significant correlation. If a definite relationship exists between age and the rate of disimpaction an underlying age-related cause must be sought. Most authors agree with Linton (1949) that the mechanism of fractures of the femoral neck is a rotational strain and that impaction is no more than the first stage of displacement with contact still maintained between the fragments (Garden, 1961; Bentley, 1968, 1980). The term ‘impacted simply means that the injury has stopped short at the first stage of displacement in response to a force that, if continued, would have produced a fully displaced fracture. The degree of displacement, therefore, is probably a function of the force applied and the strength of the femoral neck, i.e. if more force is applied or if the bone is weaker the fracture will progress to a fully displaced one. With increasing age bone tends to become more fragile due to osteoporosis and fractures are more likely to progress either ab inifio or after a temporary ‘impaction’ stage. Failure of the bone of the neck may be due to comminution of the posterior cortex leading to eventual collapse and disimpaction. Thus, older patients may be predisposed to disimpaction because of age-related osteoporosis. In younger patients the stronger bone may resist further disimpaction and the fracture may therefore remain impacted. This study of the natural history of impacted subcapital femoral fractures has demonstrated that elderly patients are at a significant risk of disimpaction and primary internal fixation is mandatory. In younger patients the risk of disimpaction is much less (0 per cent in those less than 63 years and 2 per cent in those less than 68 years) and conservative treatment may be appropriate for some. The advantages of this approach, however, must be compared with the medical, social and economic benefits of early mobilization that the relatively simple operative procedure permits.
Otremski et al.: Treatment options in impacted subcapital femoral fractures
References Bentley G. (1968) Impacted fractures of the neck of the femur. 1. &me loinf Surg. 5 OB, 55 I Bentley G. (1980) Treatment of non-displaced fractures of the femoral neck. Clin. Orthop. 152, 93. Boyd H. B. and Salvatore J. E. (1964) Acute fracture of the femoral neck: Internal fixation or prosthesis? J. Bone Joint Surg. 46A, 1066. Bunata A., Fahey A. and Drenman C. (1973) Factors influencing the stability and necrosis of impacted femoral neck fractures. JAM,4 233,41. Crawford H. B. (1960) Conservative treatment of impacted fractures of the femoral neck. A report of fifty cases. J BoneJoint Swg. 42A, 471. Crenshaw A. H. (1987) Camp&&sOprafive Swge~, Vol. 3,7th Ed. St Louis: C.V. Mosby, 1748. Eklund J. and E&son F. (1964) Fractures of the femoral neck with special regard to the treatment and prognosis of stable abduction fractures. Acfa Chir. Scand.127, 31.5. Flatmark A. L. and Lone T. (1962) The prognosis of abduction fracture of the neck of the femur. I. Bone Boinf 4rg. 44B, 324. Garden R. S. (1961) The structure and function of the proximal end of the femur. J. Bone JointSurg.43B, 5 76.
381
Garden R. S. (1971) Malreduction and avascular necrosis in subcapital fractures of the femur. J. Bone]oinf Surg.53B, 183. Hansen B. A. and Solgaard S. (1978) Impacted fractures of the femoral neck treated by early mobilisation and weight bearing. Acfa Orthop. Stand. 49,180. Linton P. (1944) On different types of intracapsular fractures of the femoral neck. Surgical investigation of origin, treatment, prognosis and complications in 365 cases. Acfa Chir. Stand. 90, Suppl. 86. Linton P. (1949) Types of displacement in fractures of the femoral neck and observation on impaction of fractures. 1. Bone Joint Surg. 3lB, 184. Pauwels F. (1935) Der Schenkenholsbruck em mechanisches Problems. Grundlagen des Heilungsvorganges. Prognose und kausale Therapie. Struttgart, Beilageheft zur Zeitschrift fur Orthopaedische Chirurgie, Ferdinand Enke. Paper accepted
21 January
1990.
lkpesfs for reprintsshod be addressedto: Dr I. Otremski, Department of Orthopaedic Surgery, Ichilov Hospital, Tel Aviv, 64239, Israel.
Printed in Great Britain
379
Natural history of impacted subcapital femoral fractures and its relevance to treatment options I. Otremskil, A. Katz’, S. Deke12, R. Salama’ and R. J. Newman3 ‘Ichilov Hospital, Tel-Aviv, Israel ?Soroko Hospital, Beer Sheba, Israel 3St James’s University Hospital,. Leeds, UK
A siudy of 723 patients with impacted, subcapital femoral fractures was undertaken to a%mine the natural history of this injury. It wasfound that the angle of the fracture, the degree of valgus and the a&a of retrovmion were without signij?ant e,$ect on the incia&ce of subsequent disimpacfion. Age was important, with a 20 per cent incia%nce of dtimpaction in patients over the age of 68 years. In patients younger than this the in&&me was only 2 per cent. These results indicate that conservative treatment may be appropriate for some younger patienk, but the &vantages of this approach mwt be compared with the medical, social and economic benejts of urly mobilization that the rehtively simpk operalive proczdure permits.
Introduction Most impacted subcapital femoral fractures are stable and heal with conservative treatment. Some, however, are unstable and disimpaction may occur even when the patient is confined to bed. Since there are no published criteria which satisfactorily differentiate the stable from the unstable fracture, internal fixation tends to be routinely practised on all such injuries (Boyd and Salvatore, 1964; Bentley, 1968, 1980). Until recently conservative treatment in the form of protected partial weight bearing was the method of choice for this fracture in our department, and this paper reviews our results in an attempt to determine the natural history of this injury and to define risk factors and indications for internal fixation.
Methods Patients A series of 123 consecutive patients with impacted subcapital femoral fractures were admitted to this hospital and were initially treated conservatively. The female to male ratio was 11: 1.3, the mean age was 65.6 f 9.2 years and the mean length of follow-up was 3 years. The fractures were defined as impacted when, on admission, the head of the femur was in valgus with penetration of the fragments superiorly, even in the presence of a breach in the inferior cortex in the anteroposterior radiograph or slight separation of the fragments anteriorly in the lateral 0 1990 Butterworth-Heinemann 0020-1383/90/060379-03
Ltd
radiograph. The fracture was considered disimpacted if the femoral head was in varus. The records were studied and surviving patients were examined and the functional results evaluated according to pain, limitation of movement and gait. The following angles were measured on the radiographs taken on admission: the angle of the fracture (Pauwel’s P-angle; Pauwels, 1935) and the angulation of the trabeculae both on the anteroposterior radiographs indicating the degree of valgus (Garden’s G-angle; Garden, 1971) and on the lateral radiographs indicating retroversion (Garden’s lateral angle; Garden, 1971). All subsequent radiographs were studied for evidence of displacement, union or avascular necrosis. The results were analysed statistically to determine the influence of each factor on disimpaction (x” Pearson test; Student’s t test). Treatment protocol All patients were treated non-operatively initially. Immediate partial weight bearing was permitted in 94 patients (76 per cent) and 3-4 days later, when radiographs did not show any change in the position of the fracture, they were discharged. After further satisfactory radiographs 6-8 weeks later they were allowed to bear full weight but with sticks until bony union was achieved. The 29 patients (24 per cent) in whom weight bearing was considered imprudent because of obesity or frailty were treated by rest in bed or in a chair for 2 months.
Results There were no significant differences between the two groups of patients with regard to age, demography or radiology. Disimpaction Disimpaction (Table I) occurred in 11 patients (8.9 per cent) overall within 2 to 80 days: four within the first 2 weeks, three between 2 and 4 weeks, three between 5 and 8 weeks and one disimpacted after 11 weeks. Although disimpaction was apparently higher in patients treated by immediate weight bearing the difference was not satistically significant. Similarly, there was no significant correlation between the incidence of disimpaction and the P-angle of the fracture,
Injury: the British Journal of Accident Surgery (1990) Vol. Zl/No. 6
380
Table I. The incidence of disimpaction according to management
Immediate weight bearing Non-weight bearing
Total
Number of patients
Disimpaction
Percentage
94
10
10.6
29
1
3.4
123
11
8.9
the G-angle of valgus or the G-lateral angle of retroversion.
The mean age of the II patients with disimpaction was significantly higher (73 years) than the average age of all patients (65.5 years) and that of patients without disimpaction (64.8 years) (PC 0.01). Similarly, in patients treated by immediate weight bearing the mean age of patients with disimpaction was significantly higher (73.3 years) than the mean age of the whole group (66.7 years) and that of patients without disimpaction (65.9 years) (PC 0.01). The incidence of disimpaction in all patients tip fo a given age ‘A’ was compared with the incidence of disimpaction in all patients over that same given age ‘A’ and the statistical significance of each comparison was estimated. Comparisons were made for all ages from 57 to 80 years and this showed increasing incidence of disimpaction with age. The incidence of disimpaction in any group of patients above any given age ‘A’ was always higher than the incidence in the remaining group of patients below the age ‘A’ and the statistical significance of this difference was maximal at 68 years. Disimpaction occurred in 20 per cent of patients over the age of 68 years compared with only 2 per cent in those under 68 years. Healing All fractures which remained displacement within 6 months.
impacted
healed
without
Avascular necrosis Avascular necrosis occurred in 8 per cent of patients between 10 and 27 months, but none required surgical treatment during the period of this study. There was no significant difference in the incidence of avascular necrosis between those treated by immediate or delayed weight bearing. Function All surviving patients were reviewed and of those treated by partial non-weight bearing 47 per cent had an excellent result (no pain or limp and minimal limitation of movement), 47 per cent had a good result (mild transient pain, minimal limp or slight limitation of movement) and 6 per cent had a poor result (almost constant pain and significant limitation of movement and walking ability). Of those treated by immediate weight bearing, the functional results were insignificantly different with 45 per cent being rated as excellent and 55 per cent as good.
Discussion Disimpaction is the most important complication of conservative treatment of previously impacted fractures of the femoral neck. Provided the fracture remains impacted, healing usually ensues with good functional results. The risk of disimpaction is therefore the main objection to nonoperative treatment.
It is generally agreed that an increase in the Pauwel’s angle is associated with a poorer prognosis (Bunata et al., 1973; Crenshaw, 1987). It indicates either an increase in the degree of displacement or an increasing instability due to increase in the shearing forces which tend to displace the fracture. This is probably the reason why the degree of obliquity of the fracture line is the principal parameter which has been investigated previously (Crawford, 1960; Flatmark and Lone, 1960; Hansen and Solgaard, 1978). Bunata et al. (1973) concluded that there was significant correlation between stability of the fracture and the Pauwel’s angle, but this was not substantiated in our study. A possible explanation for these contradictions in the prognostic value of the Pauwel’s angle is that the measurements are generally made without consideration for the effect of varying degrees of rotation of the hip at the time the radiograph was taken. This is particularly important since the subcapital fracture is spiral (Lmton, 1949) and the fracture line appears differently if the limb is in different degrees of rotation (Bentley, 1980). Impacted fractures are more common in a younger age group than that affected by displaced fractures (Liiton, 1944, 1949; Eklund and Erikson, 1964; Bentley, 1980). Similarly, Hansen and Solgaard (1978) observed that the average age of those patients whose fractures disimpacted was 82 years compared with an average age of 74 years for those whose fractures remained impacted. Otherwise, age has generally attracted relatively little attention with regard to its effect on disimpaction, but the present paper has demonstrated a significant correlation. If a definite relationship exists between age and the rate of disimpaction an underlying age-related cause must be sought. Most authors agree with Linton (1949) that the mechanism of fractures of the femoral neck is a rotational strain and that impaction is no more than the first stage of displacement with contact still maintained between the fragments (Garden, 1961; Bentley, 1968, 1980). The term ‘impacted simply means that the injury has stopped short at the first stage of displacement in response to a force that, if continued, would have produced a fully displaced fracture. The degree of displacement, therefore, is probably a function of the force applied and the strength of the femoral neck, i.e. if more force is applied or if the bone is weaker the fracture will progress to a fully displaced one. With increasing age bone tends to become more fragile due to osteoporosis and fractures are more likely to progress either ab inifio or after a temporary ‘impaction’ stage. Failure of the bone of the neck may be due to comminution of the posterior cortex leading to eventual collapse and disimpaction. Thus, older patients may be predisposed to disimpaction because of age-related osteoporosis. In younger patients the stronger bone may resist further disimpaction and the fracture may therefore remain impacted. This study of the natural history of impacted subcapital femoral fractures has demonstrated that elderly patients are at a significant risk of disimpaction and primary internal fixation is mandatory. In younger patients the risk of disimpaction is much less (0 per cent in those less than 63 years and 2 per cent in those less than 68 years) and conservative treatment may be appropriate for some. The advantages of this approach, however, must be compared with the medical, social and economic benefits of early mobilization that the relatively simple operative procedure permits.
Otremski et al.: Treatment options in impacted subcapital femoral fractures
References Bentley G. (1968) Impacted fractures of the neck of the femur. 1. &me loinf Surg. 5 OB, 55 I Bentley G. (1980) Treatment of non-displaced fractures of the femoral neck. Clin. Orthop. 152, 93. Boyd H. B. and Salvatore J. E. (1964) Acute fracture of the femoral neck: Internal fixation or prosthesis? J. Bone Joint Surg. 46A, 1066. Bunata A., Fahey A. and Drenman C. (1973) Factors influencing the stability and necrosis of impacted femoral neck fractures. JAM,4 233,41. Crawford H. B. (1960) Conservative treatment of impacted fractures of the femoral neck. A report of fifty cases. J BoneJoint Swg. 42A, 471. Crenshaw A. H. (1987) Camp&&sOprafive Swge~, Vol. 3,7th Ed. St Louis: C.V. Mosby, 1748. Eklund J. and E&son F. (1964) Fractures of the femoral neck with special regard to the treatment and prognosis of stable abduction fractures. Acfa Chir. Scand.127, 31.5. Flatmark A. L. and Lone T. (1962) The prognosis of abduction fracture of the neck of the femur. I. Bone Boinf 4rg. 44B, 324. Garden R. S. (1961) The structure and function of the proximal end of the femur. J. Bone JointSurg.43B, 5 76.
381
Garden R. S. (1971) Malreduction and avascular necrosis in subcapital fractures of the femur. J. Bone]oinf Surg.53B, 183. Hansen B. A. and Solgaard S. (1978) Impacted fractures of the femoral neck treated by early mobilisation and weight bearing. Acfa Orthop. Stand. 49,180. Linton P. (1944) On different types of intracapsular fractures of the femoral neck. Surgical investigation of origin, treatment, prognosis and complications in 365 cases. Acfa Chir. Stand. 90, Suppl. 86. Linton P. (1949) Types of displacement in fractures of the femoral neck and observation on impaction of fractures. 1. Bone Joint Surg. 3lB, 184. Pauwels F. (1935) Der Schenkenholsbruck em mechanisches Problems. Grundlagen des Heilungsvorganges. Prognose und kausale Therapie. Struttgart, Beilageheft zur Zeitschrift fur Orthopaedische Chirurgie, Ferdinand Enke. Paper accepted
21 January
1990.
lkpesfs for reprintsshod be addressedto: Dr I. Otremski, Department of Orthopaedic Surgery, Ichilov Hospital, Tel Aviv, 64239, Israel.