Irreducible Femoral Head Fracture-Dislocation

September 2012: Treatment of Irreducible Femoral Head Fracture-Dislocation

This month's trauma case of the month was submitted by M.L. Chip Routt, Jr.,M.D. and features the case of a 55 years old male police officer was injured in a motorcycle crash. At the accident scene, he complained of severe right hip pain. He presented to the emergency room with similar complaints. His vitals signs were stable. On physical exam, his pelvic ring was stable but he was unable to actively move his right lower extremity due to hip discomfort. There were no obvious deformities. The injured hip was very slightly flexed and abducted, and in neutral rotation. The remainder of his exam was normal including his peripheral neurological assessment. The paramedics had applied a circumferential pelvic binder at the accident scene.

A screening pelvic anteroposterior radiograph identified a right hip fracture-dislocation. The binder was removed and the patient then underwent a pelvic computed tomography with reconstructed oblique images.  A displaced and comminuted femoral head fracture-dislocation along with a peripheral posterior wall acetabular fracture were noted on the imaging. The pelvic ring and the femoral necks were uninjured. The screening AP film was obtained with the binder in place.

The obturator and iliac oblique reconstructed images from the CT scan demonstrate the close apposition of the dislocated proximal femur to the cortical surface of the acetabular posterior wall.  

The outlet pelvic reconstructed image is very interesting since the dislocated proximal femur and acetabulum are nearly perfectly superimposed. The diagnosis could be missed if this particular image was used alone.

The inlet pelvic image also shows the dislocation and tight relationship of the dislocated proximal femur and the posterior acetabulum cortical surface, alerting the treating physician to the possibility of an irreducible injury using standard closed manipulative techniques.

The axial CT image indicates the injury details including but not limited to dislocation direction, femoral head fracture extent and comminution, acetabular posterior wall injury, loose fragments within the joint, the overall bone quality, patient body habitus, underlying conditions such as inguinal hernia, pelvic ring and soft tissue assessment, and status of the femoral neck.

Despite the radiographic indicators of a femoral head fracture dislocation that would likely be irreducible using standard closed manipulation techniques, the patient was counseled and opted for an attempted closed reduction. He was sedated with sufficient intravenous medications only after consenting to closed and potential urgent open reduction as needed. The attempted manipulative closed reduction was unsuccessful and the hip essentially had no movement. The attending orthopedic surgeon on call had performed the manipulative closed reduction but failed to move the hip. He noted that the injured hip felt “fixed and stable”. He concluded that despite more than adequate sedation, the hip injury was irreducible using closed reduction methods.

The patient was then taken urgently to the operating room where general anesthesia with full muscle relaxation was provided to the patient, and he was positioned supine on a radiolucent operating table. Using real time fluoroscopic guidance, the hip was imaged during a careful manipulative attempted reduction, but the dislocated proximal femur was essentially fixed in its position.

An open reduction was then performed. The patient was elevated from the table on two folded blankets placed posterior to the sacrum. The entire abdomen and right lower extremity were prepped and draped carefully after the perineum had been cleansed and isolated form the planned surgical field. Intravenous antibiotics were administered and a modified Smith-Petersen anterior surgical exposure of the hip was accomplished.

The 10cms incision began in the region of the anterior superior iliac spine and paralleled the interval between the tensor and sartorius muscles.

The rectus femoris muscle common tendon was isolated.

Next the rectus femoris common tendon was incised leaving a stump for later repair. The rectus femoris tendon was tagged with a suture distally and the muscle belly was retracted distally.

The anterior hip capsule was easily exposed completely by elevating the lateral  portion of the iliocapsularis muscle from it. The anterior capsule was completely intact. An oblique T-shaped capsulotomy was then used to expose the hip joint. The upper limb paralleled the uninjured anterior labrum and the lower limb paralleled the normal position of the femoral neck.

Retraction of the T-shaped capsulotomy revealed the injury, related hematoma, femoral head fracture fragments, otherwise empty acetabulum, and the posteriorly dislocated proximal femur. The femoral head fracture fragments were removed from the acetabulum and placed in a blood-saline soaked sponge in a protected area of the surgical assistant’s instrument table. The acetabulum was then thoroughly inspected visually including palpation of the anterior wall area to assure that there were no remaining bone cartilage, or other tissue fragments in the joint.  Then looking through the acetabulum, the posterior wall fracture and posterior labral injuries were easily seen. Very taut tendon structures were identified between the posterior wall area and the dislocated proximal femur. These tissues were located anterior to the femoral neck and were visualized through the wound. They were obstructing manual manipulation attempts. When traction was applied to the limb, these tendons became extremely tight and prevented all but minimal movement of the proximal femur. The sciatic nerve was noted on deeper inspection of the wound to be medial and posterior relative to the dislocated proximal femur. The tight tendons directly anterior to the femoral neck were then incised and the dislocated proximal femur became mobile immediately. Tight capsular tissues were then incised along the cranial aspect of the dislocated femoral head fracture surface and under direct visualization through the wound, the dislocated proximal femur was carefully and easily reduced into the acetabulum using manual traction on the lower limb. C-arm orthoganol fluoroscopy was used at this point to assure a congruent relationship between the reduced proximal femur and the acetabulum.

The femoral head fracture fragment was then prepared for reduction and fixation on the surgical assistant’s table. The cancellous surface hematoma and loose debris were removed. Three glide holes were then drilled through the femoral head fracture fragment perpendicular to the fracture plane. These were positioned caudally on the femoral head fracture fragment and with sufficient separation between the glide holes to allow stable fixation. The depth of the cartilage was identified to plan for countersinking of the screw heads. 

The proximal femur was then atraumatically manipulated and surgically dislocated anteriorly through the oblique T-shaped capsulotomy so the femoral head fracture fragment could be reduced under direct visualization onto the proximal femur. Narrow diameter wires inserted through the area of the fovea centralis held the reduction initially, the pathways drilled, and then small fragment screws were inserted using the glide holes. Chondral surface comminution and missing cartilage of the cranial femoral head area made that aspect of the reduction challenging, but the caudal cortical fracture surfaces were used to guide the reduction. The temporary wires were removed and the hip was carefully relocated.

Intraoperative fluoroscopy confirmed the reduction accuracy and screw locations. Dynamic real time C-arm images showed that the screws were completely contained within the bone and did not extrude. The hip joint was stressed to extremes of passive motion (including full flexion, adduction, internal rotation) while observing the fluoroscopic imaging to assure stability. The peripheral posterior wall and capsular avulsion injuries were treated without surgical stabilization. After throrough irrigation of the wound and hip joint, the T-shaped capsulotomy and the rectus femoris tenotomy were repaired. 

The wound was closed routinely in layers over two suction drains.

Plain pelvic radiographs and a CT scan demonstrated the reduction and screw locations.

After surgery, intravenous antibiotics were administered for 24 hours, and venous thrombosis prophylaxis provided. He began his rehabilitation on the first day after surgery with unrestricted passive range of hip motion, isometric exercises, and protected weight bearing on the injured side. Oral indomethacin was prescribed for 6 weeks after surgery to avoid symptomatic ectopic bone formation. During the second six weeks postoperative phase, he advanced to progressive resistance exercises and weight bearing. At his three months postoperative clinic visit, he was full weight bearing, reported a slight limp due to residual weakness “ at the end of the day”, denied hip pain, and had 15 degrees of decreased hip internal rotation compared to the contralateral normal hip. His pelvic radiographs demonstrated a symmetrical and normal hip joint space, no implant changes, no signs nor symptoms of aseptic necrosis, and no evidence of ectopic bone formation.

Femoral head fracture dislocations usually are associated with posterior directional dislocations and antero-medial femoral head fracture locations. The peripheral posterior wall and capsule and labrum are also commonly avulsed in these injuries. For the common injury patterns, the femur is flexed, adducted, and internally rotated on the injury anteroposterior pelvic film. Prior to any closed reduction attempts, the treating physician must first assure that adequate pharmacological relaxation is achieved and the femoral neck is intact.

While uncommon, irreducible femoral head fracture dislocations have a characteristic radiographic appearance in that the femur is only slightly flexed, is in neutral rotation, and is without adduction or abduction. The dislocated femoral head is tightly positioned against the cortical surface of the posterior acetabular wall. Soft tissue structures are displaced and cause the dislocated proximal femur to be relatively immobile. The piriformis tendon, obturator internus tendon, labrum, and hip capsular and labral tissues have all been identified intraoperatively as obstructing both closed and open reduction. These obstructing tissues are located anterior to the proximal femur and therefore best seen using an anterior surgical exposure. The anterior exposure also allows improved access to the antero-medial femoral head fracture fragment and proximal femur for accurate reduction and stable fixation. The oblique T-shaped capsulotomy spares the anterior labrum and does not compromise femoral head blood supply. The rectus femoris tenotomy allows the repaired femoral head to be easily reduced back into the acetabulum after the anterior surgical dislocation. Once repaired and reduced, the hip joint must be examined in the operating room using fluoroscopy to assure stability. If the hip joint is still unstable with passive flexion and internal rotation after accurate reduction and stabilization of the femoral head fracture, the posterior capsular-labrum-wall warrant repair. Oral indomethacin seems to decrease the incidence and severity of hip region ectopic bone formation after open reduction and internal fixation of femoral head fracture dislocations via the anterior surgical exposure.

Symptomatic ectopic bone formation resulted in this different patient who was unable to take indomethacin after surgery.  Because the hip cartilage relies on motion for its preservation, early ectopic bone excision is indicated in these patients.

Authored By: M.L. Chip Routt, Jr.,M.D