Journal of Long-Term Effects of Medical Implants, 21(1): 63–69 (2011)
Fixation of Femoral Neck Fractures Using Divergent Versus Parallel Cannulated Screws Ioannis D. Papanastassiou,1,2* Andreas F. Mavrogenis,2 Zinon T. Kokkalis,2 Konstantinos Nikolopoulos,2 Konstantinos Skourtas,1 & Panayiotis J. Papagelopoulos2 1
First Department of Orthopedics, KAT Hospital, Athens, Greece; 2First Department of Orthopedics, Athens University Medical School, Athens, Greece
*Address all correspondence to Ioannis Papanastassiou, First Department of Orthopedics, KAT Hospital, Nikis 2 Kifissia, Athens, 145-61 Greece;
[email protected].
ABSTRACT: Controversy exists regarding the optimal method of internal fixation in femoral neck fractures. Biomechanical data suggest that calcar fixation is superior to central screws placement. We propose a divergent technique for placing 3 cannulated stainless steel screws engaging the calcar femorale. Fiftytwo patients admitted to our institution for a femoral neck fracture were treated with the divergent screw technique, over a 7-year period. Four patients were deceased and 4 were lost to follow-up. Of the remaining 44 patients there were 10 males and 34 females, aged from 33 to 78 years (mean, 58 years). All patients were operated on by the same surgeon and were followed-up for a minimum of 2 years (mean: 33.6 months, range: 2-6 years). Twenty-four patients sustained a non-displaced fracture (Garden I-II) and 20 sustained a displaced fracture (Garden III-IV) of the femoral neck. Mean Harris hip score (HHS) was 89.6 points. Avascular necrosis was evident in 4 patients (9%) with displaced fractures. Non-unions or failed internal fixations were not encountered. There was a significant difference in the HHS, in favor of the divergent group (P = 0.006), while more complications were encountered in the parallel group including 6 cases with non-union. In conclusion, parallel screw placement is not critical for an excellent clinical outcome. Our proposed fixation method using 3 screws that diverge and lie in different coronal planes (1 engaging the calcar femorale) with a free-hand technique may offer enhanced fixation. Biomechanical data along with larger clinical studies are needed to establish our proposed method. KEY WORDS: femoral neck fractures, internal fixation, stainless steel, cannulated screws, divergent, parallel
I. INTRODUCTION Hip fractures constitute a major health problem because of the disabling nature of these injuries. Due to aging of the population, the incidence of these fractures has been increasing, from 1.7 million in 1990 to an estimated 6.3 million by the year 2050.1,2 Current management for femoral neck fractures includes internal fixation for young patients ( 90 points); 8 patients had a good score (89-80 points); 2 patients had a fair score (79-70 points); and 2 patients had a poor score (< 70 points). One patient had a positive Trendelenburg’s sign. Non-unions or failed internal fixations were not encountered. Avascular necrosis (AVN) of the femoral head was evident in 4 patients with displaced neck fractures. Illustrative cases are presented in Figs. 2 and 3. The two cohorts were similar in age (58 vs. 56.7 years, P = 0.2) and identical in regards to non-displaced/displaced fracture ratio. Comparison with the control group showed that there was a statistically significant difference in the HHS in favor of the experimental (divergent) group (P = 0.006). More complications were encountered in the control (parallel) group. There were 4 cases of AVN and 6 cases of non-union in the parallel group, in contrast to 4 cases of AVN in the divergent group. Volume 21, Number 1, 2011
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Numbers were too small to provide a meaningful statistical analysis. V. DISCUSSION The most common complications of the cannulated screw internal fixation of femoral neck fractures are non-union and early displacement of the fracture and screws. Other complications are cut-out of the screws, wound infection or hematoma formation, local pain or tenderness, and, rarely, peritrochanteric fractures.3,20 Various configurations have been proposed for the internal fixation of femoral neck fractures, such as 2 parallel screws, 4 screws in a diamond-shaped pattern, or 3 screws in a triangular or vertical pattern.12,16 In 1961, Garden was the first to describe the use of crossed screws for the treatment of femoral neck fractures.13 Christie et al. also reported favorable results with divergent pins.14 In two recent studies, spreading of the screws in the lateral view was suggested.21,22 However, other studies suggested that parallel screws have superior results, being easier to insert and yielding fewer complications.23,24 It is obvious from the numerous studies published in the literature that the optimal number and configuration of the screws has not been determined yet and that great controversy exists.12 To the best of our knowledge, there are no other studies describing our proposed divergent type of screw configuration. The comparison with the control group indicates that there is at least a trend toward better functional results. However, it is not clear whether this difference of 7 points in the HHS (89.6 vs. 82.6) has clinical significance, since a difference of 10 points is needed to place a patient in a different category (eg, excellent vs. very good). Some authorities have also reported that a 30% difference is the minimal clinically important difference (MCID) in other self-reported scales (such as the pain score).25 Probably more clinically relevant is that fewer complications with lesser propensity for hardware loosening and non-union were encountered. Gurasami et al. also found a reduced rate of non-unions when the spreading of the screws in the lateral plane was greater.21 The
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TABLE 1. Patient’s Demographic Data (sex, age, Garden type, and complications) Patients’ Data Pt Sex Age Garden HHS Complications 1 M 64 4 74 2 F 47 2 91 3 F 58 1 93 4 F 52 4 91 5 F 53 1 89 6 M 65 2 94 7 F 55 2 100 8 F 57 1 90 9 F 58 3 48 AVN 10 F 51 3 82 11 M 33 4 100 12 F 55 2 100 13 F 68 3 90 14 F 47 2 92 15 F 66 1 100 16 M 50 3 94 17 F 74 3 80 AVN 18 F 58 4 90 19 F 61 2 91 20 F 66 1 100 21 F 60 2 82 22 M 78 3 100 23 F 53 3 82 24 F 64 1 100 25 F 58 4 90 26 F 54 4 91 27 M 63 2 94 28 M 76 3 100 29 F 58 2 82 30 F 58 3 48 AVN 31 F 57 2 100 32 F 49 2 90 33 M 62 4 74 34 F 59 2 91 35 F 57 2 100 36 F 49 2 92 37 F 55 1 89 38 M 52 3 94 39 F 72 3 80 AVN 40 F 58 1 90 41 M 35 4 100 42 F 58 1 93 43 F 64 1 100 44 F 66 3 91
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B
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C
FIGURE 2. A: 50-year-old male patient with Garden-III fracture. Successful closed reduction was performed during the operation. B-C: Anteroposterior (B) and lateral (C) radiograph of the left hip 27 months after the injury shows successful healing of the femoral neck fracture (HHS: 94). Figure 2B depicts backing of the screws, indicating impaction of the neck fracture. A
B
C
FIGURE 3. A: 55-year-old female patient with Garden-II fracture. B-C: Anteroposterior (B) and lateral (C) radiograph 25 months postoperative shows successful fracture healing (HHS: 100).
divergent screw technique places the screws in a fashion that prevents rotation of the head and posterior collapse by the screws locking one on the other, as well as by providing a better “grip” within the femoral head. This benefit is unlikely to result from techniques where multiple pins or screws are placed in parallel in the same coronal plane.14 The insertion of the second screw is very important. This screw should be inserted in proximity to the calcar femorale to provide maximal medial cortical support.2,16–18 In fact, as highlighted by some authorities, only two screws may be adequate if they engage the posteroinferior calcar area.18 As shown in a cadaver biomechanical study the calcar fixation group showed better impaction and increased stiffness, whereas all catastrophic failures and increased Volume 21, Number 1, 2011
varus malformation were encountered in the conventional triangular parallel group.15 We attribute the lack of varus displacement and non-unions in our study group to this calcar screw, along with the screws spreading in the lateral plane. Another important conclusion from this study is that parallel screw insertion is not mandatory; consequently, special intraoperative guide wires are not needed. Sometimes it is difficult to conform the guide wires to the individual anatomy, so a larger surgical exposure is then required. Without these tools, this need for a bigger surgical exposure is obviated. Bout et al. also recommends against using drill guides and did not suggest that exact parallelism was significant.18 Additionally, we have encountered a couple of cases of subtrochanteric
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fractures following fixation with parallel screws, in line with previous published studies.20 To our experience, this complication was due to violation of the lateral cortex by multiple drill holes, in an effort to put the screws in a parallel/triangular fashion. Our modified technique, after a relatively short learning period (3-4 cases), is easily mastered, reproducible, and with low cost. Limitations of this study are the small number of patients and the retrospective data collection. Another possible argument against our proposed method is that the divergent configuration of the screws may prevent impaction of the femoral neck fracture. However, this can be avoided if the traction is gently released before the tightening of the screws. In fact, as seen from our cases, impaction of the fracture frequently occurred (Fig. 2). We believe that the degree of divergence (~30o) was not sufficient to prevent fracture impaction. Also, there are authorities who assert that compression in femoral head fractures has been proved to be not significant.26 In conclusion, we believe that parallel screw placement is not critical for an excellent clinical outcome. Our proposed fixation method using 3 screws that diverge and lie in different coronal planes (1 engaging the calcar femorale) with a freehand technique may offer enhanced fixation. Biomechanical data along with larger clinical studies are needed to establish our proposed method. REFERENCES 1. Cooper C, Campion G, Melton LJ 3rd. Hip fractures in the elderly: a world-wide projection. Osteoporos Int. 1992;2:285–9. 2. Tidermark J, Ponzer S, Svensson O, Soderqvist A, Tornkvist H. Internal fixation compared with total hip replacement for displaced femoral neck fractures in the elderly. A randomised, controlled trial. J Bone Joint Surg Br. 2003;85:380–8. 3. Lu-Yao GL, Keller RB, Littenberg B, Wennberg JE. Outcomes after displaced fractures of the femoral neck. A meta-analysis of one hundred and six published reports. J Bone Joint Surg Am. 1994;76:15–25.
4. Parker MJ, Pryor GA. Internal fixation or arthroplasty for displaced cervical hip fractures in the elderly: a randomised controlled trial of 208 patients. Acta Orthop Scand. 2000;71:440–6. 5. Toh EM, Sahni V, Acharya A, Denton JS. Management of intracapsular femoral neck fractures in the elderly; is it time to rethink our strategy? Injury. 2004;35:125–9. 6. Holmberg S, Kalen R, Thorngren KG. Treatment and outcome of femoral neck fractures. An analysis of 2418 patients admitted from their own homes. Clin Orthop Relat Res. 1987:42–52. 7. Barnes R, Brown JT, Garden RS, Nicoll EA. Subcapital fractures of the femur. A prospective review. J Bone Joint Surg Br. 1976;58:2–24. 8. Clark DI, Crofts CE, Saleh M. Femoral neck fracture fixation. Comparison of a sliding screw with lag screws. J Bone Joint Surg Br. 1990;72:797–800. 9. Holmes CA, Edwards WT, Myers ER, Lewallen DG, White AA 3rd, Hayes WC. Biomechanics of pin and screw fixation of femoral neck fractures. J Orthop Trauma. 1993;7: 242–7. 10. Parker MJ, Blundell C. Choice of implant for internal fixation of femoral neck fractures. Meta-analysis of 25 randomised trials including 4,925 patients. Acta Orthop Scand. 1998;69:138–43. 11. Baitner AC, Maurer SG, Hickey DG, Jazrawi LM, Kummer FJ, Jamal J, Goldman S, Koval KJ. Vertical shear fractures of the femoral neck. A biomechanical study. Clin Orthop Relat Res. 1999:300–5. 12. Selvan VT, Oakley MJ, Rangan A, Al-Lami MK. Optimum configuration of cannulated hip screws for the fixation of intracapsular hip fractures: a biomechanical study. Injury. 2004;35:136–41. 13. Garden R. Low angle fixation in fractures of the femoral neck. J Bone Joint Surg Br. 1961;43:647–63. 14. Christie J, Howie CR, Armour PC. Fixation of displaced subcapital femoral fractures. Compression screw fixation versus double divergent pins. J Bone Joint Surg Br. 1988;70:199–201. 15. Booth KC, Donaldson TK, Dai QG. Femoral neck fracture fixation: a biomechanical study
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21. Gurusamy K, Parker MJ, Rowlands TK. The complications of displaced intracapsular fractures of the hip: the effect of screw positioning and angulation on fracture healing. J Bone Joint Surg Br. 2005;87:632–4. 22. Lykke N, Lerud PJ, Stromsoe K, Thorngren KG. Fixation of fractures of the femoral neck. A prospective, randomised trial of three Ullevaal hip screws versus two Hansson hookpins. J Bone Joint Surg Br. 2003;85:426–30. 23. Parker MJ. Parallel Garden screws for intracapsular femoral fractures. Injury. 1994;25:383–5. 24. Parker MJ, Porter KM, Eastwood DM, Schembi Wismayer M, Bernard AA. Intracapsular fractures of the neck of femur. Parallel or crossed garden screws? J Bone Joint Surg Br. 1991;73:826–7. 25. Gatchel RJ, Mayer TG. Testing minimal clinically important difference: additional comments and scientific reality testing. Spine J. 2010;10:330–2. 26. Frandsen PA, Andersen P Jr, Christoffersen H, Thomsen PB. Osteosynthesis of femoral neck fracture. The sliding-screw-plate with or without compression. Acta Orthop Scand. 1984;55:620–3.
