SCREWS VERSUS TWO HANSSON HOOK-PINS. N. Lykke, P. J. Lerud, K. Strømsøe, K.-G. Thorngren. From Aker University Hospital, Oslo, Norway. N. Lykke ...
Fixation of fractures of the femoral neck A PROSPECTIVE, RANDOMISED TRIAL OF THREE ULLEVAAL HIP SCREWS VERSUS TWO HANSSON HOOK-PINS N. Lykke, P. J. Lerud, K. Strømsøe, K.-G. Thorngren From Aker University Hospital, Oslo, Norway
n a prospective, randomised trial, we compared the use of three Ullevaal hip screws with that of two Hansson hook-pins in 278 patients with fractures of the femoral neck. Background factors were similar in both groups. Follow-up was for two years. There were no significant differences between the groups in length of time of surgery, hospital stay, general complications, mortality, pain or walking ability. Likewise, the rates of early failure of fixation, nonunion, and the need for reoperation did not differ significantly between the groups. The use of hook-pins was associated with less drill penetrations of the femoral head during surgery (odds ratio 2.6, p= 0.05) and a lower incidence of necrosis of the femoral head (odds ratio 3.5, p = 0.04). There was a strong relationship between poor reduction and fixation of the fracture and subsequent reoperation (p = 0.0005 and p = 0.0001, respectively). Likewise, peroperative drill penetration of the femoral head was associated with a greater risk of reoperation (p = 0.038). Both methods gave favourable results. In total, 22% of the patients needed a major reoperation (usually hemiarthroplasty), while in 7% of the cases the fixation device needed to be removed. Osteosynthesis as the sole method for operation of all fractures of the femoral neck was thus successful in 78% of patients. With selective treatment most of the remaining patients would have benefited if treated by a primary arthroplasty. Accurate selection requires the development of better prognostic methods.
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J Bone Joint Surg [Br] 2003;85-B:426-30. Received 19 August 2002; Accepted after revision 16 December 2002
N. Lykke, MD, Resident Orthopaedic Surgeon P. J. Lerud, MD, Consultant Orthopaedic Surgeon K. Strømsøe, Professor,MD, PhD, Professor of Orthopaedics Department of Surgery, Aker University Hospital, Tronheimsveien 235, 0514 Oslo, Norway. K.-G. Thorngren, MD, PhD, Professor of Orthopaedic Surgery Lund University Hospital, SE-22185, Lund, Sweden. Correspondence should be sent to Dr N. Lykke at Ullevaal Universitessykehus, Pastikkirurgisk Avdeling, N-0407 Oslo, Norway. ©2003 British Editorial Society of Bone and Joint Surgery doi.10.1302/0301-620X.85B3.13788 $2.00 426
The treatment of displaced fractures of the femoral neck differs greatly throughout the world.1-4 Internal fixation, hemiarthroplasty and total hip replacement are the current options. A treatment policy of primary arthroplasty for all displaced fractures of the femoral neck, however, can lead to over-treatment with femoral heads likely to heal being removed unnecessarily. In previous series investigating osteosynthesis, up to 70% of these fractures healed successfully.1,5-7 Some recent randomised reports comparing internal fixation with arthroplasty have shown a risk of failure of between 38% and 43% with osteosynthesis which required further surgery.8,9 Thus, we need to optimise the treatment of this common and resource-consuming condition. For the past decade primary reduction and osteosynthesis has been the method of choice in Scandinavia, particularly in Norway and Sweden. At our centre, we use closed reduction and internal fixation for all reducible fractures. Therefore, the setting was considered to be suitable for a randomised study of different methods of osteosynthesis. We wanted to compare the Hansson hook-pins, which are not used in Norway, with the Ullevaal hip screws, to see if it was possible to improve our understanding of osteosynthesis in the treatment of fractures of the femoral neck.
Patients and Methods Between April 1997 and December 1998, 317 patients who were admitted to our unit with a unilateral fracture of the femoral neck were considered for entry into this study. For patients with dementia, their relatives were asked. Nine patients declined to participate. Of the 308 patients who gave informed consent, 30 were excluded. Two had a pathological fracture, two a combined cervical and trochanteric fracture, two a medial neck fracture during the healing period of a previous fracture and 24 had irreducible fractures, which were treated by hemiarthroplasty. In total, 278 patients were randomly assigned using numbered, sealed, opaque envelopes in blocks of 50, to treatment with either three Ullevaal screws (n = 131) or two hook-pins (n = 147). There were 229 women and 49 men with a mean age of 82 years (27 to 101). Before the fracture, 61% of the patients had lived in their own homes, and 73% could walk without walking aids (Table I). THE JOURNAL OF BONE AND JOINT SURGERY
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Table I. Details of the 278 patients who received either three Ullevaal screws (131 patients) or two Hansson hook-pins (147 patients) for the fixation of femoral fractures, by number and percentage Ullevaal Mean age in years (range) Gender (%) F M Living conditions Own home Nursing home Other Walking ability No aids/one crutch Walking aids Confined to bed Unknown Fracture severity Undisplaced Displaced
Hook-pins
95% CI
82 (27 to 101)
24 (18) 107 (82)
0.12 to 0.26 0.74 to 0.88
24 (16) 123 (84)
0.11 to 0.23 0.77 to 0.89
72 (55) 39 (30) 20 (15)
0.46 to 0.64 0.22 to 0.38 0.10 to 0.23
98 (67) 37 (25) 12 (8)
0.58 to 0.74 0.18 to 0.33 0.04 to 0.14
96 (73) 31 (24) 1 (1) 3 (2)
0.65 to 0.81 0.17 to 0.32 0 to 0.04 0.01 to 0.07
107 (73) 34 (23) 2 (1) 3 (2)
0.65 to 0.80 0.17 to 0.31 0 to 0.05 0 to 0.06
39 (30) 92 (70)
0.22 to 0.38 0.62 to 0.78
39 (27) 108 (73)
0.20 to 0.34 0.66 to 0.80
We classified the fractures into undisplaced (Garden I and II) and displaced (Garden III and IV);10,11 78 (28%) were undisplaced and 200 (72%) were displaced.10,11 No patients received traction preoperatively as Garden12 and Frandsen et al13 reported this to be unnecessary. Antibiotic prophylaxis consisted of two doses of cefalotin (2 g) intravenously. Thromboembolic prophylaxis consisted of 2500 IU low-molecular-weight heparin given subcutaneously early after admission and thereafter every 12 hours until surgery, followed by 5000 IU daily until discharge. A total of 39 surgeons with a great variety of experience operated on the patients within a mean of 22 hours (2 to 72) of admission. In each study group there was equal representation of residents (n = 197), orthopaedic surgeons (n = 64) and residents with accreditation in general surgery (n = 17). Each surgeon had undertaken three procedures of each kind before he or she could take part in the study. Using an extension table with a pressure-supporting mattress and spinal anaesthesia, we undertook closed reduction of displaced fractures, under biplanar fluoroscopic control. Both surgical procedures required a small incision in the skin and fascia, the use of Kirschner wires, and a drill guide. Radiographs were taken immediately after the procedure. Criteria for acceptable reduction were, on the anteroposterior (AP) view, no varus, maximum displacement of 2 mm and valgus alignment of 0˚ to 15˚, and on the lateral view, a maximum displacement of 2 mm while allowing 20˚ of ventral and 10˚ of dorsal angular displacement. The Ullevaal hip screw (Orthovita, Norway) has a shaft and wing diameter of 7.0 mm. The core diameter is 5.0 mm. Criteria for acceptable placement of the device were positioning of the two distal screws close to the calcar on the AP view, and dispersal of the screws ventrally and dorsally as much as was allowed by the anatomy of the femoral neck in the lateral view. The proximal screw on the AP view should be central on the lateral view. The Hansson hook-pin (Swemac, Linköping, Sweden) is a cannulated blunt pin (nail) with a diameter of 6.5 mm. It VOL. 85-B, No. 3, APRIL 2003
95% CI
81 (56 to 96)
has a thin blade (hook) lying inside, which is driven out of the tip of the pin during the procedure. Criteria for the acceptable placement of the device were positioning of the distal pin close to the calcar on the AP view and centrally on the lateral view. The proximal pin should be close to the calcar on the lateral view and central on the AP view. Both types of implant should be parallel to the axis of the femoral neck or in no more than 15˚ of valgus. In addition, they should have a subchondral placement in the femoral head with a maximum distance from the implant to the chondral margin of 5 mm. The patients were mobilised immediately after surgery and encouraged to bear weight. However, younger patients who were in good mental and physical condition, had only partial weight-bearing for the first 12 weeks. Clinical and radiological follow-up examinations were at four months, and at one and two years, postoperatively. Radiologists, with particular experience in orthopaedic radiology, evaluated the radiographs. The examining surgeon also evaluated the films at follow-up. We defined early fixation failure as loss of fixation resulting in displacement of the fracture within the first four months of surgery and late displacement or failure of healing was defined as nonunion. All complications were recorded even if the patient died during the twoyear follow-up period. Statistical analysis. Chi-squared and Fisher’s exact tests were used for statistical analysis. Statistical significance was defined as p ≤ 0.05.
Results The two groups were comparable with regard to background factors, such as gender, age, prefracture home circumstances, prefracture walking ability and severity of the fracture (Table I). There were no significant differences between the two groups with regard to the delay between fracture and operation or admission and operation. Nor did the length of time
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Table II. Quality of surgery, systemic complications and wound problems after surgery for the fixation of femoral fractures using either three Ullevaal screws or two Hansson hook-pins, by number and percentage Ullevaal (n = 131)
95% CI
Length of time of surgery in minutes (range) 37 (14 to 85) Fracture reduction Acceptable 115 (88) 1 complication 9 (7) 2 to 5 complications 7 (5) Positioning of the device Good 98 (75) Fair 28 (21) Poor 5 (4) Drill penetration 16 (12) Deep-vein thrombosis 1 (1) Pneumonia 3 (2) Haematoma 3 (2) Superficial infection 1 (1)
Hook-pins (n = 147)
95% CI
34 (12 to 80) 0.81 to 0.93 0.03 to 0.13 0.02 to 0.11
130 (88) 7 (5) 10 (7)
0.82 to 0.93 0.02 to 0.10 0.03 to 0.12
0.67 to 0.82 0.15 to 0.29 0.01 to 0.09 0.07 to 0.19 0 to 0.04 0.01 to 0.07 0.01 to 0.07 0 to 0.04
115 (78) 28 (19) 5 (3) 7 (5) 1 (1) 1 (1) 3 (2) 2 (1)
0.71 to 0.85 0.13 to 0.26 0.01 to 0.08 0.02 to 0.10 0 to 0.04 0 to 0.04 0 to 0.06 0 to 0.05
Table III. The number of complications of healing after surgery for the fixation of femoral fractures using either three Ullevaal screws or two Hansson hook-pins, by number and percentage Ullevaal (n = 131) Fracture severity Number of early fixation failures (number reoperated) Undisplaced Displaced Total Number of nonunion (number reoperated) Undisplaced Displaced Total Number of segmental collapses (number reoperated) Undisplaced Displaced Total
95% CI
39 undisplaced 92 displaced
Hook-pins (n = 147)
95% CI
39 undisplaced 108 displaced
3 (3) 23 (22) 26 (25)
0.02 to 0.21 0.17 to 0.35 0.13 to 0.28
1 (1) 24 (20) 25 (21)
0 to 0.14 0.15 to 0.31 0.11 to 0.24
1 (1) 2 (1) 3 (2)
0 to 0.14 0 to 0.08 0.01 to 0.07
1 (0) 5 (5) 6 (5)
0 to 0.14 0.02 to 0.11 0.02 to 0.09
3 (1) 12 (3) 15 (4)
0.02 to 0.21 0.07 to 0.22 0.07 to 0.18
4 (2) 4 (1) 8 (3)
0.03 to 0.24 0.01 to 0.09 0.02 to 0.10
of surgery differ significantly between the two groups (Table II). In total, 17 patients in the Ullevaal and 16 in the hook-pin group (12% in each group) did not fulfil the criteria for acceptable reduction. Five of the reduced fractures (7%) had more than one complication. Thus a total of 245 fractures (88%) fulfilled the criteria for reduction (Table II). We considered the positioning of the internal device to be good or fair in 96% and 97% of the patients in the Ullevaal and hook-pin groups, respectively. Perioperative drill penetration of the femoral head showed a significant difference (odds ratio 2.6, p = 0.050) with 12% in the Ullevaal screw group and 5% in the hook-pin group, respectively (Table II). The number of reoperations during the hospital stay was 3% in each group. There were few general complications, and no significant differences between the two groups (Table II). Mortality during the hospital stay was low, 3% in each group. After four months, 15% and 10% of the patients in the Ullevaal and hook-pin groups, respectively, had died. The mortality after two years was a mean of 33%, 34% in the Ullevaal
group and 33% in the hook-pin group. None of these differences was significant. The mean hospital stay was ten days in the Ullevaal group and 12 days in the hook-pin group. The median stay was the same (8 days) in both groups. The pattern of discharge from hospital did not differ significantly. Most patients were discharged to rehabilitation centres (49% of the Ullevaal group and 47% of the hook-pin group) or nursing homes (32% and 34%, respectively). Only 8% of the Ullevaal group and 7% of the hook-pin group went directly home. After four months, most of the surviving patients had returned to their previous living conditions in their own homes (62% of the Ullevaal group and 60% of the hook-pin group), with only 37% and 39%, respectively, living in nursing-homes. Living conditions were not specified for the rest of the patients. Two years after the fracture, 62% of the patients in the Ullevaal group were still alive and living in their own homes, compared with 71% in the hook-pin group; 36% and 29% of the patients, respectively, lived in nursing homes. THE JOURNAL OF BONE AND JOINT SURGERY
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The rate of local wound complications was low with no differences between the two groups (Table II). There were no deep wound infections. Early failure of fixation occurred in 26 patients (20%) with Ullevaal screws and 25 (19%) required an arthroplasty. Correspondingly, 25 (17%) of the hook-pin patients suffered an early failure of fixation. Of these, 21 (14%) required an arthroplasty (Table III). Nonunion occurred in three (2%) and six patients (4%) in the Ullevaal and hook-pin group and surgery was necessary in two (1%) and five patients (3%), respectively. Segmental collapse occurred in 15 patients (11%) in the Ullevaal group, of whom four underwent arthroplasty, compared with eight (5%) in the hook-pin group with three requiring arthroplasty. The difference in the incidence of necrosis of the femoral head was significantly lower in the hook-pin group for displaced fractures (odds ratio 3.5, p = 0.036). There was a trend towards fewer reoperations by an arthroplasty if an experienced orthopaedic surgeon had operated upon the patients. There was a significant correlation (p = 0.038) between drill penetration of the femoral head and later reoperations. If drill penetration occurred, 46% of the patients later required a prosthesis, compared with 19% if no drill penetration had occurred. There was a highly significant correlation (p = 0.0005) between the accuracy of the reduction of the fracture and the need for later reoperation, as well as the positioning of the implant (p = 0.0001). For implants in which the position was rated as good, 16% required an arthroplasty, for those rated as fair 32% had an arthroplasty, and for those rated as bad, 80% had an arthroplasty. In 189 patients the reduction and placement of the device were rated as good and no drill penetration had occurred. In this group of patients with optimal operative outcome, the need for arthroplasty was 14% in the Ullevaal group and 11% in the hook-pin group. A successful result was thus achieved in 86% of the Ullevaal group and 89% of the hookpin group, excluding the need to remove the fixation device. After two years, 77% of the patients in the Ullevaal and 69% in the hook-pin group felt no pain when walking on the operated hip while 4% in each group felt severe pain when walking. Because of disturbed cognitive function, we were not able to evaluate pain when walking in 12% in the Ullevaal group and 10% of the hook-pin group. Only 4% reported pain at rest, while 88% of the patients had no pain at rest. In 8% of patients it was not possible to evaluate pain at rest because of disturbed cognitive functions. There were no differences between the two groups. In total, 17% of the patients who reported impaired walking ability could not walk as well as before the fracture and 47% walked without impairment compared with before the fracture; 37% could not assess this.
Discussion The outcome of a fracture of the femoral neck is dependent both on biological and biomechanical factors. Damage to VOL. 85-B, No. 3, APRIL 2003
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the circulation of the femoral head can lead to complications of healing, such as nonunion and necrosis of the femoral head (segmental collapse). The mechanical stability of the fracture after reduction and fixation prevents early displacement. The impact of the trauma at the moment of fracture can cause major damage to vessels, impairing the circulation of the femoral head. Accurate reduction and adequate positioning of the implant restore stability and create favourable conditions for healing of the fracture. The healing pattern of the fracture is by direct primary consolidation. Scintigraphic studies of the circulation of the femoral head show a correlation between decreased blood flow and early displacement.14 This relates to Garden grades III and IV fractures. The frequency of complications of healing ranges in the literature from 15% to 40%.1,5,6,15 Our study shows that suboptimal reduction of the fracture, inaccurate positioning of the implant and peroperative drill penetration impair fracture healing, leading to an increased need for secondary arthroplasty. One explanation for the relationship between drill penetration and the increased need for arthroplasty may be that the penetration of the joint by the drill creates a communication between the joint and the fracture. Synovial fluid may then irrigate the site of the screw and disturb the healing process. Both methods of osteosynthesis resulted in favourable rates of healing. The hook-pin method had significantly fewer penetrations of the femoral head during surgery and a lower incidence of necrosis of the femoral head. The alternative treatment to osteosynthesis for displaced fractures of the femoral neck is arthroplasty, but this will subject many patients to unnecessary major surgery with the sacrifice of undamaged femoral heads. The ideal situation would be to predict preoperatively the healing outcome in fractures of the femoral neck. This has proved to be difficult using plain radiographs.16-19 One reason is that preserved vessels may remain attached to the periosteum in moderately displaced fractures.1,18 Preoperative scintimetry to measure the circulation is resource-consuming, delays the operation and needs special positioning to obtain accurate images.20 It is not used routinely. There is a great need for better preoperative indicators, and a need to optimise the technique of osteosynthesis in the treatment of fractures of the femoral neck. Osteosynthesis has been the primary method for the treatment of such fractures in Norway for decades. Other comparative studies have been mainly in centres more skilled in arthroplasty techniques. This may explain why the overall results in our study showed a high rate of healing, with a total two-year need for secondary arthroplasty in only 22% of the patients; 10% of the undisplaced and 26% of the displaced fractures. This means that about 75% of the displaced and reducible fractures healed uneventfully. For the patients with optimal reduction and positioning of the device, the rate of success increased to almost 90%. This was achievable even when 39 different surgeons, mostly residents under training, carried out the pro-
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cedure and reflects the situation in most Norwegian hospitals. There are no previously published randomised studies comparing the insertion of three Ullevaal hip screws19 with that of two Hansson hook-pins. In 1998, Alho et al7 compared the Ullevaal method with the use of Olmed and Tronzo screws in a randomised trial; 12.6% of patients in the Ullevaal group needed a major reoperation, but there were no significant differences between the methods. A significant proportion of patients was subjected, however, to hemiarthroplasty without an attempt at primary reduction of the fracture. Hook-pins have previously been compared in randomised studies with the sliding screw plate, the Rydell four-flanged nail, Uppsala screws and AO screws. In 1995, Elmerson et al10 presented a two-year follow-up study comparing hook-pins with the sliding screw plate. There were no significant differences and 21% of the hook-pin patients subsequently required hemiarthroplasty. In a randomised study of 410 patients, with follow-up of two years, Sernbo et al21 found no significant differences between the Rydell nail and the hook-pin. They reported a secondary salvage arthroplasty rate of 9% (undisplaced) and 29% (displaced) in the hook-pin group. Nilsson et al11 reported a salvage arthroplasty rate of 16%, regardless of grade of displacement, in a two-year follow-up study of 191 prospective patients. In 1991, Svendsen, Hermansson and Noer22 reported a salvage arthroplasty rate of 19% for 78 non-randomised patients with a two-year follow-up. One year later, Strömqvist et al,5 reporting on 626 consecutive patients, recorded secondary arthroplasties for 13% of undisplaced and 19% of displaced fractures of the femoral neck. In the recent randomised study of Rogmark et al9 comparing hook-pins with arthroplasty, 43% of the osteosynthesis group required reoperation. The secondary arthroplasty rate in the previous literature mainly ranges from 20% to 30% for displaced fractures, but the recent study of Rogmark et al9 has an exceptionally high reoperation rate. It is, however, evident from the earlier consecutive prospective series, and from our study, that osteosynthesis is the method of choice for most displaced fractures of the femoral neck. Attention to the quality of the reduction of the fracture and the positioning of the fixation device are of the utmost importance. If the fracture heals uneventfully, which is usually apparent within two years, the patient has a hip which will, theoretically, last for the rest of his or her life. An arthroplasty may result in complications, with loosening or cartilage wear (for hemiarthroplasties) and periprosthetic fractures. Thus, it is important to select the right method for each patient. When given the choice at the end of the trial, all the surgeons preferred the Hansson hook-pin method because of its user-friendliness. This was because the instrument guide
allowed better positioning of the pins with less risk of penetration than that with Ullevaal screws. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.
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