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The Orthopod

The Official Publication of the
American Osteopathic Academy of Orthopedics

Abstracts

Posterior Tilt Predicts Failure in Garden I and II Femoral Neck Fractures

By Nicholas Lampasona OMS-III1, Drew Papadelis DO, PGY-22
1Nova Southeastern University Dr. Kiran C Patel College of Osteopathic Medicine
Ft. Lauderdale, FL
2Philadelphia College of Osteopathic Medicine – Department of Orthopedics
Philadelphia, PA

Introduction: Internal fixation with cannulated screws has long been the standard of care for Garden I and II femoral neck fractures1. Complications however are not uncommon and failure rates of internal fixation in this fracture population can approach 20%1. There is a paucity of evidence to support objective factors that can be attributed to this rate of failure. Age, ASA score and gender have previously been discussed as predictors of outcomes, but data is not consistent. A new measurement, the posterior tilt angle has been recently discussed as a specific measurement to guide treatment specifically in nondisplaced femoral neck fractures1-5,7. The posterior tilt angle is measured on the femoral neck as an angle between the mid-column line and the radius-column line on a lateral radiograph5. This angle is clearly illustrated in figure 1 and can be measured on radiograph as well as on CT scan as seen in figure 2. High Interobserver agreement for measuring the posterior tilt angle has been demonstrated amongst orthopedic surgeons4. These recent findings discussed in this metanalysis hold significance to orthopedic surgeons treating hip fractures, as posterior tilt is not currently factored into the Garden classification system which classically guides treatment for femoral neck fractures. Failure of internal fixation in Garden I and II fractures requires subsequent operative interventions; A primary treatment plan of hip arthroplasty may be beneficial in patients with nondisplaced femoral neck fractures with increasing posterior tilt to avoid postoperative complications and subsequent surgery7.

Methods: The posterior tilt angle is measured as an angle between the mid-column line and the radius-column line on a lateral radiograph5. Through metanalysis, with searches directed through the PubMed database, this paper examines prospective and retrospective systematic reviews, cohort studies and case control studies and reports the data found. Studies included examine the posterior tilt angle in Garden I and II fracture patterns with a primary goal to extrapolate data and report significant conclusions as compared to other predictors of outcomes in the Garden I and II fracture population.

Results: Posterior tilt angle has shown to be a statistically significant predictor of fracture failure in Garden I and II fracture patterns1-5,7. Many studies have found posterior tilt angles greater than 20 degrees to correlate with a higher rate of complication or failure3,5,7,8. One study in particular divided populations into 3 groups of posterior tilt angle, 0-9, 10-19 and greater than 20 degrees3.

This study demonstrated increased failure with increasing posterior tilt but only found statistical significance at posterior tilt above 20 degrees3. Another study showed statistical significance of failure with any degree of posterior tilt2. Increasing age has also correlated to fixation failure, but in many studies, this was not statistically significant. Gender has also proved to be a non- statistically significant indicator of failure. High interobserver agreement for measuring posterior tilt on plain radiographs and CT have been shown9. This agreement rate is improved with availability of both plain radiograph and CT imaging9. The evidence against posterior tilt predicting fixation failure in Garden I and II fractures is scarce. The one study found that failed to demonstrate any statistical significance between posterior tilt and fracture failure did not include 27 of the 45 reoperations in their analysis6. These exlusions included reoperation due to local pain (n=19), revision closed reduction percutaneous pinning (CRPP) (n=2) and subsequent adjacent fracture (n=6)6.

Figure 1: AP and Lateral radiographs defining posterior tilt as the angle measured between the mid-column line and radius column line5
Figure 2: Representation of posterior tilt easily depicted on a CT scan12.

Discussion: Arthroplasty has been discussed as an alternative primary treatment plan with less risk of failure in patients with Garden I or II fractures with posterior tilt over 20 degrees1-5, 7,8. This may especially be relevant in elderly patients to prevent subsequent surgeries. Complications reported in the Garden I and II fracture population include early displacement, avascular necrosis, malunion, nonunion and loss of screw purchase1-3. These complications warrant subsequent full or hemiarthroplasty1-3 According to literature, reoperation rates in Garden I and II fractures treated with the cannulated screw system range from 7-22% which may largely be due to posterior tilt angles1. Stratifying by posterior tilt angles greater than or less than 20 degrees, has found a fixation failure rate of 19% vs 11% respectively3.

The evidence that posterior tilt does not significantly contribute to the rate of failure in Garden I and II femoral neck fractures has limitations with scarce support6. The study demonstrating this lack of correlation found an average posterior tilt angle of 12 degrees6. This angle is significantly less than the representative 20 degree angle that most studies have established to predict fracture failure. Furthermore, this same study failed to analyze 27 of the 45 reoperations done in their patient population6. A large fraction of these reoperations was done due to local pain which can be an early predictor of AVN6,9.

Measuring the posterior tilt angle has proven to be reliable and replicable as demonstrated by orthopedic surgeons4. A group of eight orthopedic surgeons read and assessed 50 radiographs of Garden I and II fracture patterns for posterior tilt over two sessions, with a 6-week washout period in between sessions. Overall intraclass correlation coefficient (ICC) of the assessments made was rated as excellent, with no difference in reliability between the two sessions4.

For future treatment plans and to support evidence-based practice, prospective randomized double blind studies may be needed to fully delineate the role that posterior tilt angles play in nondisplaced femoral neck fractures. An ideal study would be one that randomizes posterior tilt angles over 20 degrees into one of two treatment plans: canulated screw system (CSS) control group or arthroplasty. Decreased failure rates found in the aforementioned study in patients with posterior tilt angles greater than 20 degrees treated with arthroplasty as compared to control groups would help support this change in primary treatment plan. Results from such study may suggest that patients with high degrees of posterior tilt angles in Garden I and II fracture patterns undergo primary arthroplasty, and those with less degrees of posterior tilt undergo the traditional CSS procedure.

In some of Garden’s original work, he postulated that any subcapital rotation of the femoral neck may obliterate the supplying arteries to the femoral head, indicating a cause for avascular necrosis10. Further, Garden noticed that when the posteroinferior aspect of the subcapital fracture becomes comminuted, stability is lost and a “lateral rotation” deformity ensues11. This may be equivalent to posterior tilt. Garden states, this deformity results in avulsion of the fixated bone from the cancellous head11. Disruption of the union may be responsible for subsequent avascular necrosis.

The question of treatment plan in Garden I and II femoral neck fractures may come down to thorough preoperative assessment and patient lifestyle/expected lifespan consideration. Routinely, surgical decisions in every other part of the body are not made without at least two orthogonal views on imaging, the hip should be no different. As reported, posterior tilt can be accurately measured on both lateral x-ray and CT scan12. For patients lacking true laterals on x- ray, evidence has shown that preoperative CT scan will accurately assess posterior tilt12. Intraoperative lateral views under fluoroscopy may also be an option, pending patient hip flexibility.

References

  1. Biz C, Tagliapietra J, Zonta F, Belluzzi E, Bragazzi NL, Ruggieri P. Predictors of early failure of the cannulated screw system in patients, 65 years and older, with non-displaced femoral neck fractures. Aging Clin Exp Res. 2019.
  1. Do LND, Kruke TM, Foss OA, Basso T. Reoperations and mortality in 383 patients operated with parallel screws for Garden I-II femoral neck fractures with up to ten years follow-up. Injury. 2016;47(12):2739-42.
  1. Dolatowski FC, Adampour M, Frihagen F, Stavem K, Erik Utvag S, Hoelsbrekken SE. Preoperative posterior tilt of at least 20 degrees increased the risk of fixation failure in Garden-I and -II femoral neck fractures. Acta Orthop. 2016;87(3):252-6.
  1. Dolatowski FC, Hoelsbrekken SE. Eight orthopedic surgeons achieved moderate to excellent reliability measuring the preoperative posterior tilt angle in 50 Garden-I and Garden-II femoral neck fractures. J Orthop Surg Res. 2017;12(1):133.
  2. Palm H, Gosvig K, Krasheninnikoff M, Jacobsen S, Gebuhr P. 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. 2009;80(3):303-7.
  1. Lapidus LJ, Charalampidis A, Rundgren J, Enocson A. Internal fixation of garden I and II femoral neck fractures: posterior tilt did not influence the reoperation rate in 382 consecutive hips followed for a minimum of 5 years. J Orthop Trauma. 2013;27(7):386-90; discussion 90-1.
  1. Okike K, Udogwu UN, Isaac M, Sprague S, Swiontkowski MF, Bhandari M, et al. Not All Garden-I and II Femoral Neck Fractures in the Elderly Should Be Fixed: Effect of Posterior Tilt on Rates of Subsequent Arthroplasty. J Bone Joint Surg Am. 2019;101(20):1852-9.
  1. Dolatowski FC, Frihagen F, Bartels S, Opland V, Šaltytė Benth J, Talsnes O, Hoelsbrekken SE, Utvåg SE. Screw Fixation Versus Hemiarthroplasty for Nondisplaced Femoral Neck Fractures in Elderly Patients: A Multicenter Randomized Controlled Trial. J Bone Joint Surg Am. 2019 Jan 16;101(2):136-144. doi: 10.2106/JBJS.18.00316. PMID: 30653043.
  1. Ando W, Sakai T, Fukushima W, Kaneuji A, Ueshima K, Yamasaki T, Yamamoto T, Nishii T; Working group for ONFH guidelines, Sugano N. Japanese Orthopaedic Association 2019 Guidelines for osteonecrosis of the femoral head. J Orthop Sci. 2020 Dec 30:S0949-2658(20)30259-1. doi: 10.1016/j.jos.2020.06.013. Epub ahead of print. PMID: 33388233.
  1. Garden RS. Low-angle fixation in fractures of the femoral neck. The Journal of Bone and Joint Surgery. British volume. 1961 Nov;43(4):647-63.
  1. GARDEN RS. STABILITY AND UNION IN SUBCAPITAL FRACTURES OF THE FEMUR. J Bone Joint Surg Br. 1964 Nov;46:630-47. PMID: 14251448.
  1. Zamora T, Klaber I, Ananias J, Bengoa F, Botello E, Amenabar P, et al. The influence of the CT scan in the evaluation and treatment of nondisplaced femoral neck fractures in the elderly. Journal Of Orthopaedic Surgery (Hong Kong). 2019;27(2):2309499019836160-.