All statistical analyses were performed using SPSS 20.0 software (SPSS, Inc., Chicago, IL). Inter-observer and intra-observer agreements were determined by performing weighted kappa coefficient calculation. According to Landis and Koch, kappa coefficients <0 indicate no agreement; 0.0 to 0.2, slight agreement; 0.21 to 0.4, fair agreement; 0.41 to 0.6, moderate agreement; 0.61 to 0.8, substantial agreement; and 0.81 to 1.0, almost perfect agreement.15 Descriptive statistics were used to summarize sample demographics and were presented in terms of means and standard deviations. A Mann-Whitney U test, the nonparametric alternative to the independent-samples t test, assessed differences in the mean values for d1, d2, and α by Garden stage group (I vs II). We considered P values of 0.05 or less to indicate statistical significance.
Of the available sample (n = 1040), 60 (5.8 %) participants within the Garden stage I group and 60 (5.8 %) participants within the Garden stage II group were chosen for further analysis. Within the Garden stage I group, 55% participants (33 of 60) had right femur fractures, 53% participants (35 of 60) were female and the mean age was 73 (range: 27–81 years of age). Similarly, within the Garden stage II group, 51.7% participants (31 of 60) had right femur fractures, 61.7% participants (37 of 60) were female and the mean age was 75 (range: 42–85 years of age). All patients underwent surgery (internal fixation or arthroplasty). The median follow-up period was 20.3 months. The inter-observer and intra-observer kappa values were 0.937 and 0.985, respectively. Current method has good reliability.
Garden Stage I Group
Upon examining the reconstructed models in Garden stage I group, we discovered that 9 of the 15 incomplete fractures were classified as “complete” according to the AP radiographs. In incomplete fracture of Garden stage I group, the average displacements d1 and d2 were 3.69 ± 1.77 mm and 14.51 ± 1.91 mm, respectively. The mean α was 4.91° ± 2.49°. For impacted fractures classified by radiographs, significant spatial displacement was observed (Figure 3). Twelve patients underwent internal fixation and none of them had ONFH, other 3 patients underwent arthroplasty. In impacted fracture of Garden stage I group, the average displacements d1 and d2 were 6.22 ± 3.36 and 10.30 ± 5.73 mm, respectively. The displacement of the femoral head center exceeded 10 mm in more than half of the participants (33 of 60 participants). Rotational displacement of the fractures was not readily observed using the CT scans alone; however, 3D reconstructed models showed marked rotational displacement of the femoral head. The mean α was 17.83° ± 10.72° and a rotational displacement of 10° to 50° was observed among 80% of the participants. Thirty-eight patients underwent internal fixation and 3 of them had ONFH, other 7 patients underwent arthroplasty.
Garden Stage II Group
All Garden stage II fractures were classified as complete but not displaced on the anteroposterior radiographs; however, 3D reconstruction revealed that all fractures had a spatial displacement (Figure 3). Compared to incomplete fracture of Garden stage I group, the spatial displacement parameters measured by AP radiographs were much higher. All of the femoral neck fractures showed rotational displacement. The mean d1 and d2 were 7.16 ± 4.58 and 12.95 ± 8.25 mm, respectively. The mean α was 18.77° ± 9.10°. An α > 20° was observed among 41.7% (25 of 60) of the participants. Forty-seven patients underwent internal fixation and 4 of them had ONFH, other 13 patients underwent arthroplasty.
Comparison on Garden Stage Groups
We compared the means for α, d1, and d2 across the Garden stage groups using a Mann-Whitney U test. There was no significant difference in α, d1, and d2 between impacted fracture and Garden stage II groups (P > 0.05). However, significant differences were found between incomplete fracture and Garden stage II groups (Figures 4–6).
The increased morbidity and mortality of undisplaced fractures associated with the femoral neck demands the immediate attention of the medical community.16,17 Fracture classification systems are considered as useful tools for making a decision on an adequate method of treatment and for disease prognosis evaluation.7 The Garden classification represents the most popular system currently used in clinical practice.8 Over its course of use in clinical settings, the reliability, reproducibility and ability to inform treatment procedures of the Garden classification has been brought to question.9,10,18,19
CT scanning has been preoperative routine examination for femoral neck fractures. In our studies, all CT data were obtained from preoperative routine examination. Results from our study demonstrated that the 3D reconstruction and modeling may be a better tool for assessing femoral neck fractures than an AP radiographs or 2D CTs. Specifically, we believe that the 3D modeling and reconstruction offer 3 distinct advantages to the use of an AP to evaluate, diagnose, and treat femoral neck fractures: increased precision in assessing spatial displacement; extent and rotational orientation of displacement; and time-efficiency.
Increased Precision in Assessing Spatial Displacement
Perhaps the greatest disadvantage of the Garden classification is its inability to accurately assess the spatial displacement of the femoral head, a characteristic that is essential to the informing of treatment and reduction of clinical complications.13 Zlowodzki et al found that orthopedic surgeons were able to easily differentiate undisplaced and displaced fractures but were not as successful indistinguishing between the 4 classes of the Garden classification.9 It is pertinent to note that greater number of examiners had reported the total rate of reoperation, complications and mortality was significantly higher for displaced fractures than for undisplaced fractures.6,11,16,20 Thus, some have suggested that the system be collapsed into 2 categories: femoral neck fractures without displacement (Gardens I and II) and femoral neck fractures with displacement (Gardens III and IV).6,21
The displacement of femoral neck fractures is an important characteristic to consider when developing a treatment plan. Some advocate for nonoperative treatment of these injuries, noting that these fractures are often incomplete and stable.22,23 Complications (eg, osteonecrosis, secondary displacement, or pseudoarthrosis) are quite common following operative interventions; it is estimated that between 24% and 50% experience these complications.24–27 For instance, Gjertsen et al observed nonunion in 20% of patients and avascular necrosis in 3% at the 1-year follow-up for surgical intervention of undisplaced fractures.15 Furthermore, the reoperation rate for the undisplaced fractures is between 11% and 19%, due to fracture healing complications.6,16,28
Evidence is building that a CT scan better detect subtle comminution and detailed displacement than an AP radiograph.29,30 Katz et al claimed that a CT may be more useful for understand the invasion of distal radius fractures resulted in increased inter-rater reliability in the proposed management of these injuries and improved the sensitivity of measurement of articular surface gapping and comminution.5 Lasanianos et al reported that CT scan was more appropriate means to verify the hidden fractures and predicted the further complications in femoral neck fracture.32 An inherent limitation of the 2D CT is that sequential 2D images skip disruptions in the parallel radiographic planes; this often makes the interpretation of the 2D images confusing or inerrant. For this reason, the authentic displacement of the femoral head is in 3D reconstruction offers advantages to the 2D approach and should be further investigated.33
The use of 3D CT may offer improved intra-rater and inter-rater agreement, as well as improved sensitivity, specificity, and accuracy for the detection of spatial displacement.34–36 For instance, Gose et al found that 3D reconstructions was beneficial for the analysis of the femoral offset, the neck-shaft angle and the femoral anteversion of individuals with cerebral palsy,34 while Li et al found that 3D reconstructions were useful for measuring the antero-lateral coverage of femoral head.33 It is our belief that 3D CTs are the most accurate and direct method available for the assessment of spatial displacement in femoral head fractures.
Extent and Rotational Orientation of Displacement
A major finding from our study in the discovery that 9 of 15 participants in the Garden stage I group had been misclassified by an AP radiograph as having an “incomplete” fracture. Others have noted the inerrant nature of AP radiographs in identifying the extent of the femoral neck fractures13 and is has been suggested that these fractures involve variable degrees of displacement.37 Ideally, a 3D reconstruction would be used to differentiate the extent of the displacement.37
As compared to an AP radiograph, 3D reconstruction and modeling are capable of measuring the rotational displacement of femoral neck fractures. In the present study, nearly half of the participants in the Garden stage I group showed a great rotational displacement of the femoral head in the 3D model; however, the AP radiograph was unable to detect the rotational orientation of the fracture. For the Garden stage II group, we detected prominent rotational displacement and spatial displacement of the femoral head in all 60 participants.
Aside from its use in the evaluation of femoral neck fractures, a solid understanding of the extent and rotational orientation of displacement is critical to the therapeutic strategy and prognosis of individuals with femoral neck fractures. Beyond the improvement in the assessment and detection of femoral neck fractures, these characteristics are crucial to the prediction of postoperative complications11 and reoperations.16 However, these previous studies are plagued with confounding bias due to the dependence on radiographs to determine the extent and rotational orientation, which offer unacceptable intra- and inter-rater reliability (Tables 1 and 2).
We believe that Garden stages I and II fractures, particularly impacted fractures, classified by AP radiographs may be minimally displaced fractures, as opposed to stable or “undisplaced” fractures. Consequently, we suspect that this may lead to an increase in the number of fractures being classified within a higher Garden class (eg, stage III or IV). This is plausible, considering that the Garden classification was originally designed to focus on the trabeculae within the acetabulum and the femoral head, which do not sufficiently describe the without additional imaging perspectives. We believe that this warrants a correction to the Garden classification to include 2 new substages for undisplaced fractures: Garden Ia, Incomplete fracture; Garden Ib, Impacted fracture; Garden II, Complete fracture with minor displacement. This adjustment to the traditional Garden classification has been further supported in contemporary researchers.9
Strengths and Limitations
The use of CT imaging introduced an increased risk of radiation exposure risk to the participants. Although radiation exposure of patients is a concern, we believe that controlled and limited doses of irradiation are acceptable to detect the accurate femoral displacement instead of requiring repeat scanning or radiation by 2D imaging. Howard et al indicated that only a small percentage of performed patient examinations triggered a notification or alert event from CT, the impact on workflow of adopting these features was negligible, following low dose exposure CT technology widely used, the radiation hazard can be reduced.38
Another limitation of our study exists in the relatively small sample size; we acknowledge that further studies with larger sample size are needed to confirm our current findings.
This study was designed to help develop and quick and reliable method for assessing displacement for physicians, nurses, and technicians. Although this objective is still novel, our study did include the measurement of Garden stage I or II of the femoral neck fractures. In further studies, we plan to investigate the association between spatial displacement and fracture stage. Additionally, our study did not directly evaluate whether the use of 3D CT scan better inform treatment plans or predict outcomes; further studies are needed to investigate explicitly determine these relationships.
Despite methodological limitations, our study provides evidence for the appropriate use of 3D reconstruction and digital measurement technologies for assessment of undisplaced femoral neck fractures. This method provides more accuracy in evaluating the spatial displacement, extent and rotational orientation of the fracture than 2D examinations. Additionally, this study highlights a new quick and efficient method to accurately understand the true spatial displacement and rotation in undisplaced femoral neck fractures, which could guide orthopedists in making preoperative plans and offer reasonable treatment options to individuals with femoral neck fractures.
1. Conn KS, Parker MJ. Undisplaced intracapsular hip fractures: results of internal fixation in 375 patients. Clin Orthop Relat Res
2. Bjørgul K, Reikerås O. Outcome of undisplaced and moderately displaced femoral neck fractures. Acta Orthop
3. Frandsen PA, Andersen E, Madsen F, et al. Garden's classification of femoral neck fractures. An assessment of inter-observer variation. J Bone Joint Surg Br
4. Bradley M, Shaw M, Fox D. The Bristol Hip View: a new hypothetical radiographic projection for femoral neck fractures. Br J Radiol
5. Katz MA, Beredjiklian PK, Bozentka DJ, et al. Computed tomography scanning of intra-articular distal radius fractures: does it influence treatment? J Hand Surg Am
6. Rogmark C, Carlsson A, Johnell O, et al. A prospective randomised trial of internal fixation versus arthroplasty for displaced fractures of the neck of the femur. Functional outcome for 450 patients at two years. J Bone Joint Surg Br
7. Thomsen NO, Jensen CM, Skovgaard N, et al. Observer variation in the radiographic classification of fractures of the neck of the femur using Garden's system. Int Orthop
8. Lasanianos N, Kanakaris N, Giannoudis PV. An occult acetabular fracture preceding a femoral neck fracture. Orthopedics
2009; 32: pii: orthosupersite.com/view.asp?rID=41935. doi:10.3928/01477447-20090624-28.
9. Melvin JS, Matuszewski P, Scolaro J, et al. The role of computed tomography in the diagnosis and management of femoral neck fractures in the geriatric patient. Orthopedics
10. Li L, Jia J, Zhao Q, et al. Evaluation of femoral head coverage following Chiari pelvic osteotomy in adolescents by three-dimensional computed tomography and conventional radiography. Arch Orthop Trauma Surg
11. Toh EM, Sahni V, Acharya A, et al. Management of intracapsular femoral neck fractures in the elderly: is it time to rethink our strategy? Injury
12. Gose S, Sakai T, Shibata T, et al. Morphometric analysis of the femur in cerebral palsy: 3-dimensional CT study. J Pediatr Orthop
13. Garden RS. Low-angle fixation in fractures of the femoral neck. J Bone Joint Surg Br
14. Chen W, Li Z, Su Y, et al. Garden stage I fractures myth or reality? A prospective study comparing CT scans with X-ray findings in Garden stage I femoral neck fractures. Bone
15. Gjertsen JE, Fevang JM, Matre K, et al. Clinical outcome after undisplaced femoral neck fractures. Acta Orthop
16. Dettoni F, Peveraro A, Dettoni A, et al. Epidemiology of hip fractures in northwestern Italy: a multicentric regional study on incidence of hip fractures and their outcome at 3-year follow-up. Musculoskelet Surg
17. Karaeminogullari O, Demirors H, Atabek M, et al. Avascular necrosis and nonunion after osteosynthesis of femoral neck fractures: effect of fracture displacement and time to surgery. Adv Ther
18. Gaspar D, Crnković T, Durovic D, et al. AO group, AO subgroup, Garden and Pauwels classification systems of femoral neck fractures: are they reliable and reproducible? Med Glas (Zenica)
19. Estrada LS, Volgas D, Stannard JP, et al. Fixation failure in femoral neck fractures. Clin Orthop Relat Res
20. Palm H, Gosvig K, Krasheninnikoff M, et al. A new measurement for posterior tilt predicts reoperation in undisplaced femoral neck fractures: 113 consecutive patients treated by internal fixation and followed for 1 year. Acta Orthop
21. Clement ND, Green K, Murray N, et al. Undisplaced intracapsular hip fractures in the elderly: predicting fixation failure and mortality. A prospective study of 162 patients. J Orthop Sci
22. Johnell O, Kanis J. An estimate of the worldwide prevalence and disability associated with osteoporotic fractures. Osteoporos Int
23. Wang Y, Zeng Y, Dai K, et al. Normal lower-extremity alignment parameters in healthy Southern Chinese adults as a guide in total knee arthroplasty. J Arthroplasty
24. Zlowodzki M, Bhandari M, Keel M, et al. Perception of Garden's classification for femoral neck fractures: an international survey of 298 orthopaedic trauma surgeons. Arch Orthop Trauma Surg
25. Otremski I, Katz A, Dekel S, et al. Natural history of impacted subcapital femoral fractures and its relevance to treatment options. Injury
26. Patange SRSP, Lewi LJ, Haddad Z, et al. Three-column classification and Schatzker classification: a three- and two-dimensional computed tomography characterisation and analysis of tibial plateau fractures. Eur J Orthop Surg Traumatol
27. Gras F, Marintschev I, Klos K, et al. Screw placement for acetabular fractures: which navigation modality (2-dimensional vs. 3-dimensional) should be used? An experimental study. J Orthop Trauma
28. Verheyen CC, Smulders T, van Walsum AD. High secondary displacement rate in the conservative treatment of impacted femoral neck fractures in 105 patients. Arch Orthop Trauma Surg
29. Kannus P, Parkkari J, Sievanen H, et al. Epidemiology of hip fractures. Bone
30. Perron AD, Miller M, Brady WJ. Orthopedic pitfalls in the ED: slipped capital femoral epiphysis. Am J Emerg Med
31. Oakes DA, Jackson K, Davies MR, et al. The impact of the garden classification on proposed operative treatment. Clin Orthop Relat Res
32. Tidermark J. Quality of life and femoral neck fractures. Acta Orthop Scand Suppl
33. Azar MS, Saravi M, Kariminasab MH, et al. Complete spontaneous improvement of non-displaced femoral neck fracture without any surgery modality. Am J Case Rep
34. Tornetta P III, Kain M, Creevy WR. Diagnosis of femoral neck fractures in patients with a femoral shaft fracture. Improvement with a standard protocol. J Bone Joint Surg Am
35. Du CL, Ma XL, Zhang T, et al. Reunderstanding of garden stage I femoral neck fractures by 3-dimensional reconstruction. Orthopedics
36. Parker MJ, White A, Boyle A. Fixation versus hemiarthroplasty for undisplaced intracapsular hip fractures. Injury
37. Cumming RG, Nevitt MC, Cummings SR. Epidemiology of hip fractures. Epidemiol Rev
Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.
38. Howard ME, McCollough CH, Leng S. Use of CT dose notification and alert values in routine clinical practice. J Am Coll Radiol
2014; doi:10.1016/j.jacr.2013.12.017 [Epub ahead of print].