Session VII Pelvis and Acetabulum

Acute Blood Flow Changes to the Femoral Head Following Acetabular Fracture/Dislocations: A Prospective Study

James J. Yue, MD, John K. Sontich, MD, Stefan D. Miron MD, John H. Wilber, MD, Brendan M. Patterson, MD

Case Western Reserve University, MetroHealth Medical Ctr., Departments of Orthopaedic Surgery and Radiology, Cleveland, OH

Purpose: This study was performed to prospectively investigate acute changes in blood flow to the femoral head after traumatic acetabular fracture/dislocations and to correlate these changes with dislocation times and open reduction and internal fixation.

Materials and Methods: From June 1994 to February 1996, fifty-four consecutive patients with acetabular fracture/dislocations were prospectively collected for this study. After admission and stabilization, plain radiographs and computed tomography scans were performed. Single photon emission computed tomography (SPECT) scans were obtained after hip relocations and both pre-operatively and post-operatively following open reduction and internal fixation of displaced acetabular fractures.

Results: The median age of these patients was 35 (range 15 to 85). Forty -five patients sustained dislocations (40 posterior, 1 central, 1 anterior, and 2 inferior). Of these 45 dislocations, 35 patients sustained fracture/dislocations and 10 patients sustained isolated dislocations. Nine patients sustained isolated acetabular fractures without dislocations. The median dislocation time was 4.00 hours (range 1-24 hours). Twenty-nine hips were reduced in the emergency department and 15 hips were reduced in the operating room (12 closed and 3 open). The median time to SPECT scanning was 2 days following relocation.

SPECT scanning revealed an avascular pattern of blood flow in five patients (10%). Dislocation times over 9 hours were associated with significantly higher rates (p<0.01) of avascular patterns of blood flow to the femoral head. Three of thirty-three patients (9%) with an acetabular fracture and dislocation had SPECT scans consistent with an avascular pattern of blood flow to the femoral head. Two of ten patients (20%) with isolated dislocations exhibited an avascular pattern of blood flow to the femoral head. All eight acetabular fractures without dislocation did not exhibit evidence of an avascular pattern of blood flow to the femoral head. The average age of the five patients with an avascular pattern of blood flow was 42 (range 17-78 years old). Four hips were closed reduced, 1 was openly reduced and internally fixed, and 1 was closed reduced and then underwent a secondary acetabular ORIF. ORIF was not statistically associated with an avascular pattern of blood flow (p>0.05). An episode of hypotension was present in 11% of all patients included in this study and was present in 1 out of 5 patients (20%) with an avascular pattern of blood flow (p>0.05). Injuries to the sacro-iliac joint were present on SPECT scans in 23% of all patients.

Discussion: Collier (J Nucl Med 26:979-987, 1985) and Gruen (JOT 2: 5-9, 1988) have examined acetabular peri-articular trauma using SPECT scanning. Our findings are similar to but distinct from these two previous studies in terms of our analysis of dislocation times and operative procedures. Our findings are also supportive of our angiographic cadaveric studies (OTA, 1995) which revealed variable femoral head filling following posterior hip dislocations.

Summary: An avascular pattern of blood flow to the femoral head as determined by SPECT scanning does occur in patients with hip dislocations and fracture/dislocations of the acetabulum in the early injury period. Dislocation times greater than 9 hours may exacerbate these changes in blood flow. Operative approaches for open reduction of the hip and internal fixation of acetabular fractures do not appear to effect blood flow to the femoral head. Lastly, injuries to the sacro-iliac joint occur in over 20% of patients with fracture/dislocations of the acetabulum.