An eighty-one-year-old man with a history of Paget disease involving
the pelvis and hips fell and sustained a subcapital fracture of
the right hip (Fig. 1). Preoperative radiographs indicated
that the hip-joint space had changes consistent with degenerative
arthritis; therefore, we recommended a total hip replacement.
The patient was taken to the operating room for a right hybrid total
hip replacement (a cementless acetabular component and a cemented
femoral stem). After induction of general anesthesia, he was placed
in the left lateral decubitus position. A lateral Hardinge approach
was used. The anterior aspect of the hip capsule was excised. The
fracture site was identified, and the femoral head was removed with
use of a corkscrew. The acetabulum was reamed to 53 mm. An inferior
cyst in the acetabulum was grafted with cancellous bone from the
reaming. A 54-mm Reflection FSO porous-coated hemispherical cementless
cup (Smith and Nephew Richards, Memphis, Tennessee) was impacted
into the acetabulum in approximately 45° of abduction and 15° of
anteversion. A trial acetabular liner was then placed within the
cup.
We then prepared the femoral side with use of the Spectron system
(Smith and Nephew Richards). A number-4 broach was inserted into
the femoral canal, and a 28-mm standard head-and-neck trial component
was placed on it. A trial reduction of the hip joint was performed.
When we attempted to redislocate the trial femoral component from
the acetabulum, the soft tissues were quite tight and the trial
femoral head became disengaged and lodged under the rectus femoris
muscle anteriorly. It then migrated over the anterior column of
the acetabulum and over the pelvic brim along the inner table of the
pelvis. We attempted to remove it manually by passing our fingers
and a curved hemostat along the anterior column of the acetabulum
and over the inner table. We could not palpate the trial head. We
thought that it had migrated along the inner table of the pelvis
and was likely lying just anterior to the sacroiliac joint. It is
possible that attempts at retrieval actually pushed the trial femoral
head farther into the pelvis. After consultation with a general
surgeon and a senior orthopaedic surgeon, we decided to leave the
trial head in place and not to retrieve it. We then completed the
total hip replacement with a cemented femoral stem and a 28-mm femoral
head. Range of motion and stability of the hip joint were satisfactory.
Postoperatively, a plain radiograph of the hip showed satisfactory
positioning of the components (Fig. 2). A computed tomographic scan of
the pelvis showed the trial femoral head to be lying just anterior
to the right sacroiliac joint (Fig. 3). The patient and his family were
informed of the complication. The potential risks and benefits of
surgical retrieval of the trial femoral head were discussed with
the patient; he did not wish to undergo additional surgery. The
remainder of the postoperative course was uneventful.
At the three-month follow-up visit, the patient was walking with
a cane and did not report any notable pain in the right hip or the
pelvis.
The trial femoral head that was left in the patient’s
pelvis was a sterile, round, smooth plastic component produced from acetyl
copolymer resin (Hoechst Celanese M25; Smith and Nephew Richards).
We thought that it would be unlikely to cause any problems such
as penetration or laceration of vital structures. We contacted the
manufacturer to determine if any complications had been noted in
association with the retention of this material in the pelvis and
were told that no long-term problems had been reported.
A detailed discussion was held with the patient and his family, and
elective removal of the trial femoral head was offered. It was decided
that, given the patient’s advanced age and medical status,
it would be better to leave the trial femoral head in place. He
felt that he was doing relatively well overall, and he did not wish
to have another operation.
Some situations may warrant removal of a trial femoral head. These
situations include those involving compression of vital structures
such as nerves, vessels, or the ureter. In a younger patient, it
may be desirable to remove the trial head since the long-term effects
of this foreign body are not known.
Our review of the English-language literature did not reveal any
case reports or studies in which this particular complication has
been described. Modularity in total hip arthroplasty gives the surgeon
various options to obtain adequate range of motion and stability10,11. With modular hip-arthroplasty
components, the trial femoral head can easily disengage from the
trunion of the femoral neck during reduction and dislocation. Even
the prosthetic femoral head can detach from the trunion of the femoral
neck12. In our patient, dissociation
of the trial femoral head from the femoral component eventually
led to intrapelvic retention of the trial head (either as a result
of dislocating the hip or from attempts to retrieve the femoral
head). Our surgical approach also may have facilitated intrapelvic
displacement. The anterior capsulectomy, which is routine in the
lateral approach to the hip, may have removed a potential restraint
and allowed the trial femoral head to migrate anteriorly.
It should be emphasized that, when hip reductions and dislocations
are performed with modular components, extra attention should be
paid to soft-tissue tension. If the soft tissues are tight, it is
possible for the surgeon to lose control of modular components,
causing them to become disengaged from one another. Our patient’s
immediate and short-term course was uneventful; however, the long-term
outcome is not known. Therefore, this patient will require ongoing
vigilance for the possibility of future complications related to
intrapelvic retention of the trial femoral head.