Clinical outcomes of patients with Garden I and II femoral neck fractures as verified on MRI: a retrospective case series.

BACKGROUND: Between 2 to 10% of non-displaced femoral neck fractures (nFNF) cannot be diagnosed on plain radiographs and require further imaging investigation to be detected or verified. These fractures are referred to as occult hip fractures. This study aimed to report treatment failures, reoperations and mortality in a consecutive series of occult femoral neck fractures (FNF) treated with internal fixation (IF). METHODS: A retrospective multicenter study was performed based on a consecutive series of patients aged ≥ 60 years with an occult magnetic resonance imaging (MRI) verified Garden I and II FNF sustained after a trauma and treated with primary IF. We included 93 patients with a minimum 2-year follow-up. Radiographic assessment encompassed pre- and postoperative tilt, implant inclination, MRI and treatment failure. Data on reoperation and mortality were collected. Treatment failure was defined as fixation failure, nonunion, avascular necrosis or posttraumatic osteoarthritis. RESULTS: The study comprised of 93 patients (72% women, 67/93) with a mean age of 82 (range, 60-97) years. Overall, 6 (6%) patients had major reoperations. 2 (2%) had minor reoperations. One-month mortality was 7%, 1-year mortality was 20% and 2-year mortality was 31%. CONCLUSION: This multicenter cohort study identifies a subgroup of elderly patients with MRI verified Garden I and II FNFs sustained after trauma, i.e. occult fractures. These fractures seem to have a lower complication rate compared to nFNF identified on plain radiographs. LEVEL OF EVIDENCE: Prognostic Level V. See Instructions to Authors for a complete description of levels of evidence.

Magnetic resonance imaging for verifying hip fracture diagnosis why, when and how?

INTRODUCTION: Hip fractures are commonly diagnosed by plain radiography. When a patient presents with negative radiographs and high clinical suspicion of fracture, guidelines recommend proceeding with magnetic resonance imaging (MRI) to diagnose the patient. The aim of this study was to assess the use of MRI in diagnosing hip fractures following trauma to the hip and describe clinical outcome after MRI-diagnosed hip fractures. The perspective was to develop new recommendations for MRI use. MATERIALS AND METHODS: 616 patients at a university hospital fulfilled the inclusion criteria of having an MRI scan of the hip following trauma between the years of 2005 and 2014. Data was collected from the patients' medical records. RESULTS: The annual number of MRIs increased over the ten-year period. Out of 616 MRI scans 228 (37%) showed fracture of the hip with a dominance of trochanteric fractures, 185 (30%) revealed pelvic fracture and 183 (29%) were negative. No patient with acute pelvic fracture had associated fracture of the hip. The main reason to proceed with MRI was a strong clinical suspicion of fracture in patients with negative initial radiographs. Amongst the 228 patients with fracture, 187 (82%) were treated operatively. Of patients with hip fracture, 90 (39%) patients suffered a general complication and 11 (5%) had hip complications. The complication rate of patients with fracture on MRI was compared to that of a cohort of general hip fracture patients at our hospital. No significant difference in twelve months' survival or general complications could be found, but the MRI group had a significantly lower hip complication rate. CONCLUSION: The diagnosis set by MRI, with high share of pelvic fractures or no fracture, reflects the difficulty in differential diagnosing this group of patients. The rate of occult hip fractures was low and patients with pelvic fractures already known from X-ray did not have additional hip fractures. We found an increase in the annual number of MRIs during the 10-year-period. MRI-diagnosed hip fracture patients do not suffer more complications than the regular hip fracture patient.