Intrapelvic Migration of the Trial Femoral Head during Total Hip Arthroplasty: Is Retrieval Necessary? A Report of Four Cases

Abstract

When testing intra-operative range of motion during a total hip arthroplasty procedure with trial components, there is potential for the femoral head to dissociate from the trial neck. We report the dissociation of the trial femoral head with migration of the head into the pelvis while checking for anterior stability of the total hip arthroplasty construct. Options for retrieval of the head are outlined.

Use of modular trial components to assess optimal component positioning for stability, soft tissue tensioning, and leg length equalization during total hip arthroplasty has become a common routine. A previous case of trial femoral head dissociation with migration of the head into the pelvis without retrieval has been reported.¹ Two letters to the editor following this report questioned this approach.^2,3 The present report describes four cases of this occurrence with recommendations based on the cumulative experience.

Case 1: A 67-year-old male with a history of hypertension and coronary artery disease underwent a left cementless total hip replacement for osteoarthritis through a posterolateral approach to the hip in the lateral position. After preparation of the acetabulum, the acetabular component was placed in approximately 35 to 40 degrees of lateral opening and 20 degrees of anteversion. Dome screws were placed to augment shell fixation, and a 26-millimeter inner diameter neutral trial acetabular liner was placed. Extensive anterior and posterior acetabular osteophytes were debrided. The femoral canal was reamed and broached to prepare for the insertion of an extensively coated cementless stem. A modular head and neck trial was assembled and placed on the femoral broach. While checking for anterior hip stability by hyperextending and externally rotating the femur, the trial femoral head dissociated from the neck and migrated through a rent in the anterior capsule created during anterior acetabular osteophyte excision. It then passed along the psoas tendon and into the pelvis. Numerous attempts were made to retrieve the head by placing one or two fingers along the psoas tendon into the pelvis with the hip flexed and extended. The head could be spun around but not retrieved. Because of the patient's relatively poor health and the fact that the head had no sharp corners to perforate any intrapelvic structures, it was decided to leave the head in the pelvis. The components were placed with excellent anterior and posterior stability. The total operative time was 105 minutes. The patient and family were told of the occurrence and agreed to no further intervention unless the patient became symptomatic. The femoral head shadow was seen on the postoperative pelvis radiograph (Figure 1). The patient developed a myocardial infarction three days later and had a coronary artery bypass seven weeks postoperatively, from which he completely recovered. He is walking unlimited distances without pain or impingement symptoms two years postoperatively.

Figure 1.

Postoperative pelvis radiograph with arrows around the migrated femoral head trial.

Case 2: A 66-year-old male underwent right cementless total hip arthroplasty for osteoarthritis. The procedure was similar to that described in case one. Once again while checking for anterior stability, the femoral head dissociated and migrated into the pelvis along the psoas tendon. Retrieval using the same maneuvers was again unsuccessful. The patient and family were told of the occurrence as well as our previous experience and agreed with the approach to observe for symptoms. Postoperative radiographs demonstrated the trial femoral head to be located within the pelvis (Figure 2). The patient recovered uneventfully until the sixth postoperative week when he felt a clicking noise in his hip with loss of motion. He was taken to the operating room where an eight-centimeter incision was made starting two centimeters proximal and posterior to the anterior superior iliac spine and extending distally along the lines of the proximal portion of a Smith-Petersen incision. The dissection was then carried medial to the sartorius. The femoral head trial was palpated between the iliacus and the bony pelvis and was held securely between two fingers while bluntly dissecting onto the ball in order to retrieve it. The procedure took 20 minutes. The patient is functioning well two years later without symptoms.

Figure 2.

Postoperative pelvis radiograph with arrows around the migrated femoral head trial.

Case 3: A 78-year-old female underwent a hybrid total hip arthroplasty through a posterolateral approach. After placement of the acetabular component and broaching for the cemented femoral component, trial reduction was performed. The trial femoral head dissociated from the neck and migrated into the pelvis along the psoas tendon. It could not be retrieved through the incision. It was decided to retrieve the component through another incision. The permanent femoral component was cemented into place and the wound closed.

The patient was repositioned in the supine position, and the pelvis was prepped and draped for an ilioinguinal approach. An incision was made starting two centimeters medial to the anterior-superior iliac spine and extending toward the pubic tubercle. The external oblique muscle was divided along its fibers and the internal oblique was separated from its insertion with electrocautery. A retroperitoneal approach was followed to the psoas muscle and the trial head was easily retrieved. The wound was closed, and the patient recovered uneventfully and was functioning well six months postoperatively.

Case 4: A 58-year-old female with a previous spinal cord stroke underwent a revision total hip replacement for instability through a posterolateral approach to the hip in the lateral decubitus position. The acetabular component was revised using a 52-millimeter cementless acetabular component, and a 28-millimeter trial liner was placed. A trial femoral head was placed on the secure stem and, while checking anterior stability, the head dissociated and migrated along the psoas tendon into the pelvis. As in the other three cases it could not be retrieved. The permanent acetabular liner and femoral head were inserted. The hip was closed. The patient was placed supine and the pelvis prepped. Once again the same retroperitoneal approach was used to retrieve the trial component, which was situated beneath the iliacus as in case two. The patient was functioning well six months postoperatively.

DISCUSSION

It is always concerning to the surgeon when hardware that is used during a procedure breaks or migrates to an unretrievable position. When a trial femoral head dissociates from the neck and migrates along the psoas tendon and muscle into the pelvis, it is especially frustrating. As described in the present study and a previous report, as well as letters to the editor, the trial femoral head probably cannot be retrieved from the pelvis through only a hip incision (Figure 3). If the head dissociates during trialing for anterior stability, one should tell the tissue-retracting assistant not to move and try to retrieve the head before it migrates along the psoas tendon into the pelvis. Furthermore, one should try not to push it superiorly along the tendon. If it migrates, one can usually palpate the ball with a finger, but it spins away from the finger and cannot be retrieved. Although this should be attempted, it will probably not be successful. We recommend making a six to seven centimeter incision along the iliac crest and extending it slightly anterior and medial to the anterior superior iliac spine. Then one should place his or her finger along the inner wall of the iliac wing by reflecting the iliacus medially. This may allow the surgeon to push the femoral head (using one's finger or napkin ring forcep) back down to the pelvic rim and anterior to the hip joint, allowing retrieval. The senior author recently recommended this strategy to a surgeon who called him from an operating room with this same problem. If this maneuver does not work, by extending the incision distally (if the area is prepped) and retracting the tissues medial to the sartorius, the head can be retrieved or pushed back into the hip incision wound. If this maneuver does not work, one should complete the hip replacement procedure and consider redraping in the supine position and making a retroperitoneal approach to the pelvis to retrieve the head. If the decision is made not to retrieve the trial head, the surgeon should inform the patient and family that he or she may become symptomatic and require trial component removal at a later date.

Figure 3.

Pelvis anatomy demonstrating the femoral head trial positioned anterior to the iliacus and psoas muscle as in Case 3 with arrow demonstrating the position of the trial at the time of retrieval in Case 2 and Case 4.