Complications of anterior subcutaneous internal fixation for unstable pelvis fractures: a multicenter study.
ABSTRACT Stabilization after a pelvic fracture can be accomplished with an anterior external fixator. These devices are uncomfortable for patients and are at risk for infection and loosening, especially in obese patients. As an alternative, we recently developed an anterior subcutaneous pelvic internal fixation technique (ASPIF).
We asked if the ASPIF (1) allows for definitive anterior pelvic stabilization of unstable pelvic injuries; (2) is well tolerated by patients for mobility and comfort; and (3) has an acceptable complication rate.
We retrospectively reviewed 91 patients who incurred an unstable pelvic injury treated with an anterior internal fixator and posterior fixation at four Level I trauma centers. We assessed (1) healing by callous formation on radiographs and the ability to weightbear comfortably; (2) patient function by their ability to sit, stand, lie on their sides, and how well they tolerated the implants; and (3) complications during the observation period. The minimum followup was 6 months (mean, 15 months; range, 6-40 months).
All 91 patients were able to sit, stand, and lie on their sides. Injuries healed without loss of reduction in 89 of 91 patients. Complications included six early revisions resulting from technical error and three infections. Irritation of the lateral femoral cutaneous nerve was reported in 27 of 91 patients and resolved in all but one. Heterotopic ossification around the implants, which was asymptomatic in all cases, occurred in 32 of 91 patients.
The anterior internal fixator provided high rates of union for the anterior injury in unstable pelvic fractures. Patients were able to sit, stand and ambulate without difficulty. Infections and aseptic loosening were reduced but heterotopic ossification and irritation of the LFCN are common.
Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
- SourceAvailable from: Alexander Hofmann[Show abstract] [Hide abstract]
ABSTRACT: Fragility fractures of the pelvic ring (FFP) are increasing in frequency and require challenging treatment. A new comprehensive classification considers both fracture morphology and degree of instability. The classification system also provides recommendations for type and invasiveness of treatment. In this article, a literature review of treatment alternatives is presented and compared with our own experiences. Whereas FFP Type I lesions can be treated conservatively, FFP Types III and IV require surgical treatment. For FFP Type II lessions, percutaneous fixation techniques should be considered after a trial of conservative treatment. FFP Type III lesions need open reduction and internal fixation, whereas FFP Type IV lesions require bilateral fixation. The respective advantages and limitations of dorsal (sacroiliac screw fixation, sacroplasty, bridging plate fixation, transsacral positioning bar placement, angular stable plate) and anterior (external fixation, angular stable plate fixation, retrograde transpubic screw fixation) pelvic fixations are described.Journal of Orthopaedic Science 10/2014; · 1.01 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Purpose. Comparison of monoaxial and polyaxial screws with the use of subcutaneous anterior pelvic fixation. Methods. Four different groups each having 5 constructs were tested in distraction within the elastic range. Once that was completed, 3 components were tested in torsion within the elastic range, 2 to torsional failure and 3 in distraction until failure. Results. The pedicle screw systems showed higher stiffness (4.008 ± 0.113 Nmm monoaxial, 3.638 ± 0.108 Nmm Click-x; 3.634 ± 0.147 Nmm Pangea) than the exfix system (2.882 ± 0.054 Nmm) in distraction. In failure testing, monoaxial pedicle screw system was stronger (360 N) than exfixes (160 N) and polyaxial devices which failed if distracted greater than 4 cm (157 N Click-x or 138 N Pangea). The exfix had higher peak torque and torsional stiffness than all pedicle systems. In torsion, the yield strengths were the same for all constructs. Conclusion. The infix device constructed with polyaxial or monoaxial pedicle screws is stiffer than the 2 pin external fixator in distraction testing. In extreme cases, the use of reinforcement or monoaxial systems which do not fail even at 360 N is a better option. In torsional testing, the 2 pin external fixator is stiffer than the pedicle screw systems.Advances in orthopedics. 01/2013; 2013:683120.
- [Show abstract] [Hide abstract]
ABSTRACT: Pelvic fractures in the geriatric population are increasing in incidence. Those resulting from high-energy trauma result in increased mortality rates and can be challenging to manage due to polypharmacy and multiple patient comorbidities. Low energy pelvic fractures can be difficult to diagnose and exceptionally painful for patients. Injury to the posterior pelvis guides management. All patients with fragility fractures should be evaluated for osteoporosis and managed according to established guidelines.Current Geriatrics Reports. 06/2014; 3(2):101-108.
SYMPOSIUM: DISRUPTIONS OF THE PELVIC RING: AN UPDATE
Complications of Anterior Subcutaneous Internal Fixation
for Unstable Pelvis Fractures: A Multicenter Study
Rahul Vaidya MD, Erik N. Kubiak MD, Patrick F. Bergin MD,
Derek G. Dombroski MD, Ren J. Critchlow MD,
Anil Sethi MD, Adam J. Starr MD
Published online: 5 January 2012
? The Association of Bone and Joint Surgeons1 2012
accomplished with an anterior external fixator. These
devices are uncomfortable for patients and are at risk for
infection and loosening, especially in obese patients. As an
alternative, we recently developed an anterior subcutane-
ous pelvic internal fixation technique (ASPIF).
Stabilization after a pelvic fracture can be
definitive anterior pelvic stabilization of unstable pelvic
injuries; (2) is well tolerated by patients for mobility and
comfort; and (3) has an acceptable complication rate.
We retrospectively reviewed 91 patients who
incurred an unstable pelvic injury treated with an anterior
internal fixator and posterior fixation at four Level I trauma
centers. We assessed (1) healing by callous formation on
radiographs and the ability to weightbear comfortably;
and how well they tolerated the implants; and (3) compli-
was 6 months (mean, 15 months; range, 6–40 months).
All 91 patients were able to sit, stand, and lie on
their sides. Injuries healed without loss of reduction in 89
of 91 patients. Complications included six early revisions
resulting from technical error and three infections. Irrita-
tion of the lateral femoral cutaneous nerve was reported in
27 of 91 patients and resolved in all but one. Heterotopic
ossification around the implants, which was asymptomatic
in all cases, occurred in 32 of 91 patients.
The anterior internal fixator provided high
rates of union for the anterior injury in unstable pelvic
fractures. Patients were able to sit, stand and ambulate
We asked if the ASPIF (1) allows for
One of the authors (RV) is a consultant for Stryker Corporation to
develop a commercial product related to the topic of this article.
All ICMJE Conflict of Interest Forms for authors and Clinical
Orthopaedics and Related Research editors and board members are
on file with the publication and can be viewed on request.
Each author certifies that his or her institution approved the human
protocol for this investigation, that all investigations were conducted
in conformity with ethical principles of research, and that informed
consent for participation in the study was obtained.
Clinical Orthopaedics and Related Research neither advocates nor
endorses the use of any treatment, drug, or device. Readers are
encouraged to always seek additional information, including
FDA-approval status, of any drug or device prior to clinical use.
This work was performed at the Detroit Medical Center, Wayne State
University, Detroit Receiving Hospital, Detroit, MI, USA; University
of Utah, Salt Lake City, UT, USA; Parkland Memorial Hospital,
Dallas, TX, USA; and Ortho Indy Methodist Hospital, Indianapolis,
R. Vaidya (&), A. Sethi
Detroit Medical Center, Wayne State University,
4D-4 University Health Center, Detroit Receiving Hospital,
4201 St Antoine Boulevard, Detroit, MI 48201, USA
E. N. Kubiak
University of Utah, Salt Lake City, UT, USA
P. F. Bergin
Department of Orthopaedic Surgery and Rehabilitation,
University of Mississippi Medical Center, Jackson, MS, USA
D. G. Dombroski
Parkland Memorial Hospital, Dallas, TX, USA
R. J. Critchlow
Ortho Indy Methodist Hospital, Indianapolis, IN, USA
A. J. Starr
Department of Orthopaedic Surgery, UT Southwestern
Medical Center, Dallas, TX, USA
Clin Orthop Relat Res (2012) 470:2124–2131
and Related Research®
A Publication of The Association of Bone and Joint Surgeons®
without difficulty. Infections and aseptic loosening were
reduced but heterotopic ossification and irritation of the
LFCN are common.
Level of Evidence
Level IV, therapeutic study. See
Guidelines for Authors for a complete description of levels
Anterior external fixation is common for initial stabilization
and also for definitive treatment in combination with pos-
terior fixation for unstable pelvic fractures. Several groups
report its use for treating vertically stable AP compression
The complications associated with external pelvic frames
include pin tract infection in 2.5% to 50% of patients [1, 2, 4,
11–17, 19, 21], osteomyelitis in 0% to 7% [1, 2, 11, 13, 16,
19], aseptic loosening in 0% to 19% [11, 13, 16, 17, 19], and
loss of reduction in 0% to 33% [2, 4, 11] of rotationally
unstable injuries treated with a standalone anterior external
treated with an isolated anterior external fixator is reported as
high as 95% [11, 12, 18] and as low as 0% to 8% when
combined with posterior fixation [4, 13, 16]. Compression of
the skin and subcutaneous tissues against the fixator frame
has been documented in up to 8%  and nerve damage in
0% to 7% [2, 4, 11, 16] of these patients. An anterior pelvic
external fixator limits patient mobility, especially when sit-
ting and when being rolled from side to side. In obese
patients, external fixation is particularly difficult because the
distance from the pelvis to the bar clamp can be 10 to 15 cm,
which decreases the stability of the construct and makes
large, gaping pin tracts . The external fixator is convenient
for the surgeon  but is unsightly and cumbersome for the
patient. Several articles have advocated constructs with a
single pin in the dense supraacetabular region of each ilium
[2, 3, 6]. One biomechanical study suggests these antero-
inferior pins produce more stable constructs than conven-
tional anterosuperior or iliac pins in rotationally and
vertically unstable fracture patterns . The pins are then
connected to an external bar or a femoral distracter, which
can help reduce the anterior pelvic injury .
With the aim of improving patient comfort and mini-
mizing the complications associated with an external fixator,
we developed a technique using the established principles of
anterior external fixation but with internal implants. The
technique consists of single supraacetabular pedicle screws
placed in each ilium connected with a subcutaneous rod,
which we describe as an anterior subcutaneous pelvic inter-
nal fixator (ASPIF) .
With a multicenter group who have been engaged in the
use of this technique, we asked if this technique (1) allows
for definitive anterior pelvic stabilization of unstable
fractures resulting in healing; (2) is well tolerated by
patients allowing them mobility and comfort; and (3) has a
complication rate comparable to a historical rate with
anterior external fixation.
Patients and Methods
An Institutional Review Board-approved retrospective
review was performed at four Level I trauma centers in the
United States. The sites were Detroit Receiving Hospital,
University of Utah, Parkland Hospital, and Ortho Indy
Methodist Hospital. We retrospectively reviewed 96 patients
who underwent ASPIF (Fig. 1) from November 2007 to
December 2010 after an unstable fracture of the pelvis. The
indication for surgery was an unstable pelvic fracture in
which the surgeon believed there was a need for anterior
fixation (same as external fixation). The contraindications
were: hemodynamically unstable patients, patients with
soft tissue defects that prevented coverage of the ASPIF,
and patients with fractures through the insertion points of
supraacetabular screws. There were 56 males and 40
females with an average age of 39.2 years (range, 16–
71 years). Five patients were lost to followup before
6 months, which left 91 patients who were studied. No
patients were recalled specifically for this study; all data
were obtained from medical records and radiographs. The
minimum followup was 6 months (mean, 15 months;
range, 6–40 months); 69 of the 96 patients (72%) had
followup greater than 12 months.
All patients had preoperative AP pelvis, inlet and outlet
radiographs, pelvic CT scans and were classified according
to the Young and Burgess classification of pelvic fractures
 that is based on the mechanism of injury. It includes
lateral compression (LC), AP compression (APC), vertical
shear (VS), and a combined mechanism (CM). Lateral
compression and APC injuries are further subdivided into
three subtypes (Table 1).
In addition, there were some associated conditions that
we believed benefitted from the ASPIF at each site. These
conditions included a combination injury of a pelvic
fracture and an acetabular fracture (10 patients; Fig. 2), an
open pelvic fracture (three patients), a pathologic pelvic
fracture (three patients), treatment after failed fixation
with other means (three patients), and after a nonhealing
osteoporotic fracture (one patient). The ASPIF was used
for five cases that were classified as LC1. These were
cases that were not able to sit up and be mobile after
several days to several weeks. The ASPIF was placed and
allowed the patients to sit and get out of bed. It is an
unusual indication and we do not recommend this
Volume 470, Number 8, August 2012 Anterior Internal Fixator in Pelvic Fractures2125
All patients had the appropriate Advanced Trauma Life
Support care from trauma surgeons and were brought to the
operating room in stable condition. If posterior instability
existed, it was addressed first using the standard techniques
of reduction and iliosacral screw placement or posterior
plating. Two surgeons participating in this study (AJS,
DGD) routinely used the Starr Frame to reduce the fracture
before fixation . The ASPIF consisted of custom
polyaxial pedicle screws used in spinal surgery and a
connecting rod. The screws were 7 to 8.5 mm in diameter
and 70 to 110 mm in length depending on the size of the
patient. These are not normally a part of spinal instru-
mentation sets so they needed to be specifically requested.
The technique for ASPIF insertion, which we used in this
group of patients, has been previously described .
In the case of APC or VS injuries, the construct is
compressed with the standard compression tools found in
all spine sets. In the case of LC injuries, the ASPIF was
placed without compression or with some distraction if
necessary . In the case of a windswept pelvis (LC3), the
open posterior injury was fixed first with iliosacral screws
to close the posterior component. The ASPIF was applied
and the LC component of the injury distracted to reestab-
lish the configuration of the pelvis. Suitable reduction and
implant position was confirmed on fluoroscopic AP, inlet,
and outlet views.
Fig. 1A–C (A) An initial AP radiograph showing a patient with an
APC3 pelvic injury. (B) The immediate postoperative radiograph
after reduction, posterior fixation, and ASPIF. (C) This is a 3-month
followup radiograph after removal of the ASPIF, which shows healing
and a small amount of heterotopic bone.
Table 1. Indications for use of anterior subcutaneous pelvic internal
fixation in 91 patients
LC3 61-B3.2, 61-C215
LC = lateral compression; APC = AP compression; VS = vertical
shear; CM = combined mechanism.
2126 Vaidya et al. Clinical Orthopaedics and Related Research1
Postoperative recommendations were toe-touch weight-
bearing on the side of the posterior injury and weight-
bearing as tolerated on the side without a posterior injury.
Patients with bilateral posterior pelvic injuries remain
nonweightbearing. Weightbearing was started at 8 to
12 weeks postinjury depending on radiographs, patient
comfort, and surgeon preference and was advanced as
tolerated. All sites removed the implant between 3 and
6 months after surgery.
Patients were seen at 2 weeks, 6 weeks, 3 months,
6 months, 1 year, and at latest followup. The patients were
asked about their ability to sit, if they had trouble with
ambulation because of the implant, if the screw heads
bothered them, if the rod bothered them, and if they could
lie on their sides. Complications evaluated included loss of
fixation or reduction, if the rod was too tight on the
abdomen, infection, heterotopic ossification, and lateral
femoral cutaneous nerve irritation. Lateral femoral nerve
numbness, or pain that disappeared) or injury (paresthesias,
numbness, or pain that was persistent).
The radiographic images at each followup visit included
an AP pelvis and inlet and outlet views. These were
evaluated by independent observers at three of the four
sites (DRH, Parkland, Ortho Indy) and by the surgeon at
one site (Utah). Healing was determined by a progression
of callus formation until radiographic union and the ability
to weightbear without pain. Loss of reduction was deter-
mined by failure of the implants to hold the reduction
obtained, and failure of fixation was assessed by implant
breakage, uncoupling of the ASPIF components, or loos-
ening at the screw-bone interface.
All patients were able to weightbear as tolerated and
attained radiographic union. No patient had nonunion at
All the patients were able to sit and stand with the
device in place (91 of 91). Seventy-one of 77 patients who
were asked could lie on their sides. Although patients could
feel the implants, it did not interfere with their ability to
ambulate in any patient (91 of 91).
Early revision surgery was required in a total of six of
the 91 patients (7%). Three of these six patients lost
reduction (Table 2); in two of these three patients (both
APC2), this was attributed to unfamiliarity with the pedicle
screw caps. Revision was performed the next day. We
believed the caps had been cross-threaded and then had
come loose resulting in the loss of fixation. The rod was
reinserted on the same screw heads and new caps were
Fig. 2A–D (A) A radiograph of a
patient with an acetabular frac-
ture associated with an APC2
pelvic injury. (B) The immediate
reduction and internal fixation of
the posterior injury, the acetabular
fracture, and the ASPIF. (C) This
is a 3-month postoperative fol-
lowup film. (D) This is a 10.5-
month postoperative film showing
Volume 470, Number 8, August 2012 Anterior Internal Fixator in Pelvic Fractures2127
placed and were tensioned appropriately. This happened on
two occasions and resulted in a successful outcome and
maintenance of reduction. In one patient (VS), there was
loss of anterior and posterior fixation. A revision was
performed of the ASPIF and a second iliosacral screw (S2
screw) was placed after which the reduction was stable. In
the other three patients, all of whom were obese, the rod
was placed too deep (Fig. 3) leading to patient discomfort,
trouble sitting, and a depressed crease in their skin. The
patients were brought back to the operating room to place
longer and larger diameter screws so that the rod sat much
higher above the sartorius muscle and its fascia and they
improved. Patients at all four sites noted irritation of the
lateral femoral cutaneous nerve: 27 of the 91 patients
(30%) had irritation of the nerve, which occurred at the
time of insertion of the ASPIF and resolved spontaneously.
In one patient, this occurred at the time of removal; the
nerve was injured and the patient did not recover.
Heterotopic ossification occurred in 32 of the 91 patients
(35%) around the implants but did not interfere with
function or cause any symptoms. It occurred over the
screws, screw caps, and rods in some cases. All hardware
was removed between 3 and 6 months in this study pop-
ulation. There were no problems with implant removal at
any site. Heterotopic ossification also did not cause any
trouble with removal. Three patients sustained infections.
One infection was treated by suppressing the infection for
3 months before removing the ASPIF. This patient was
also the one with loss reduction, which was revised with
revision of the ASPIF and a second iliosacral screw (S2
screw). In two other patients, the infection occurred
4 weeks after fixation. These patients were treated with
irrigation, de ´bridement, and removal of the ASPIF. A stress
examination was stable so no other fixation was placed.
After 6 weeks of antibiotics, the patients held their
reduction and did not develop a deep infection (Table 3).
The role of external fixation in improving outcomes of
pelvic fractures has been demonstrated in several studies.
However, the complication rates reported have ranged from
12% to 58% [1, 2, 4, 7, 11–17, 19, 21] (Table 3). We
devised an internal subcutaneous fixator (ASPIF) and
hypothesized that it would stabilize unstable pelvic frac-
tures resulting in healing with decreased complications.
Our aim was to corroborate our early results  in a larger
study with experienced pelvic surgeons and identify fea-
sibility issues for a future prospective study. Specifically
Table 2. Complications of anterior subcutaneous pelvic internal
Loss of reduction3
Screw bone interface loose0
Rod or screw breakage0
Rod too tight on the abdomen3
LFCN = lateral femoral cutaneous nerve.
Fig. 3A–B (A) This is a photo-
graph of a patient with ASPIF
placed with screws sunk too far
leading to compression on the
(B) The photograph after revision
with longer screws. (C) A photo-
graph of the new longer versus
the old shorter screws.
2128 Vaidya et al. Clinical Orthopaedics and Related Research1
we asked if ASPIF (1) allows for definitive anterior pelvic
stabilization of unstable fractures resulting in healing; (2) is
well tolerated by patients allowing them mobility and
comfort; and (3) has a comparable complication rate as that
historically reported with anterior external fixation.
There are a number of limitations in the present study.
First, this was a retrospective review and the number from
we found the approach easy to use and had similar outcomes
and similar complications. Second, the study lacked a con-
trol group and disallowed direct comparison of results. This
is the first study of its kind and serves to assess if ASPIF is a
useful technique and if we should pursue its use further.
Third, like with every new technique, there is a learning
curve and some of the complications in the study may be
surgeons at the learning curve level. However, every sur-
pelvic surgery and the findingsmightnotbe generalizable to
those who provide such treatment on an occasional basis.
Fourth, the ASPIF technique uses FDA-approved implants
for spinal fixation in an unapproved method in the pelvis. It
is thus an off-label use. All sites used tools and implants that
were available from spinal fixation sets but different
implants were used at each site. An FDA-approved implant
will take time in development. Finally, we had no rigorous
approach to assessing radiographic union (eg, strict defini-
tions, multiple blinded observers) and each surgeon
evaluated their own radiographs. However, at last followup
none of the patients had obvious nonunion.
We found the ASPIF in combination with posterior
fixation allowed stabilization of unstable pelvis fractures
resulting in predictable healing in all 91 patients. This is
not unusual because the healing of unstable pelvic injuries
with the use of external fixation has been reported to have
low rates of nonunion (0%–4%) [1, 2, 4, 11–17, 19, 21]
It is well known that external fixators are cumbersome
for patients as a result of their bulk, external location, and
pin tracts. This is more evident in external pelvic fixators
that tent across the abdomen. It makes it difficult for patient
mobility. In the present study, all sites evaluated patient
function by asking them to comment on their ability to sit,
stand, lie on their sides, and their ability to tolerate the
implants. It was clear from the responses that 91 of 91
patients had the ability to sit, stand, and ambulate with the
device in place. The patients did report feeling the subcu-
taneous rod and several patients could feel the screw heads
under their skin, but all patients tolerated the procedure
well and none had the ASPIF removed because of dis-
comfort or the inability to mobilize.
Revision surgeries occurred for six of 91 (7%) cases.
Loss of reduction occurred in three of 91 cases (4%). Two
were the result of unfamiliarity with the implants and
failure of both anterior and posterior fixation in a third
patient. We believe we could have avoided all three cases
because they were attributed to technical error, were sub-
sequently repaired, and led to good outcomes even in the
patient with anterior and posterior failure who also had an
infection. Loss of reduction has been reported in 7.5% to
Table 3. Clinical results of published studies on definitive external fixation of pelvic fractures
Scaglione et al. , 201037C + S 35%0 19%0 8%0
Solomon et al. , 200918S 20% 6%0 7% 6%0
Bellabarba et al. , 2006 14S 29%007%00
Ga ¨nsslen et al. , 200545C 5%00 2%
Mason et al. , 200552C 50% 4%10% 17%0
Arazi et al. , 200041C 19%12%000
Tucker et al. , 200040C 2.5% 7.5% 7.5%10%0
Lindahl et al. , 1999 110C 24%60% 2%2%0 58%5%
Hupel et al. , 199842C 0%17% 17%0
Riemer et al. , 1993 48C 12%0
Majeed , 1990 42C 34% 19%
Wild et al. , 198243C 23%28% 21%0
Mears and Fu , 198011C 18%0
Current study 91S 3% 2%0%30%/1% 6%030%
LFCN = lateral femoral cutaneous nerve; HO = heterotopic ossification; C = screws placed in the iliac crest; S = subcristal or supraacetabular
Volume 470, Number 8, August 2012Anterior Internal Fixator in Pelvic Fractures2129
60% of cases [7, 11, 19, 21] with anterior fixation as the
definitive treatment of the pelvic injury before 2000 but
with modern fixation techniques and supplemental poster-
ior fixation, it has fallen to 0% to 6% [4, 13, 16, 17]. Three
patients had the screw heads sunk too low resulting in the
rod compressing the pelvic muscle and fascia. They were
corrected with longer screws reinforcing the importance of
keeping the screws off the bone, above the level of the
fascia, but also at the level of the subcutaneous rod. In
obese patients, there can be up to 5 cm of fat between the
sartoris fascia and the skin, which provides a large space
for the rod. It is better to leave the screw heads more
prominent so the rod has little pressure on the fat and fascia
here. Infection of the ASPIF occurred in three instances
(4%) despite the device being internal. These infections
resolved with eventual removal and antibiotics. This is
certainly more troublesome than pin site infections occur-
ring in 4% to 50% of patients with external fixation [1, 2, 4,
11–17, 19, 21] but which often can be treated with local
care and antibiotics. Removal of definitive external fixation
frames in the treatment for pelvic fractures owing to
infection reportedly occurs in 0% to 12% of patients [1, 2,
4, 11, 13–17, 19, 21]. Aseptic loosening of the device was
not noted in this series and is likely the result of the larger
diameter screws that we use (7–8.5 mm) and the fact that
the rod to bone distance is decreased with having an
internal rod versus a rod that sits 5 to 10 cm above the skin
and another 3 to 5 cm from the skin-to-bone interface. The
literature reports an incidence of 0% to 19% [1, 2, 4, 11,
13–17, 19, 21] of this complication with several articles
attributing the loosening to loss of fixation.
Temporary irritation of the lateral femoral cutaneous
nerve was observed in 30% of patients, being transient in
all except one (one of 91). This was diagnosed with altered
sensation or pain in its distribution. It is possible to injure
the nerve during implantation and removal requiring
awareness of this complication. Prior studies using supra-
acetabular pins [2, 5, 6] have reported injury to the lateral
femoral cutaneous nerve in zero of 37 , one of 14 (7%)
, and three of 45 (7%)  patients, which is much lower.
These studies listed injured nerves and we listed irritation
and permanent injury. We postulated that technique may
have something to do with this, but it was present at all
sites and each surgeon is familiar with supraacetabular
placement of Schanz pins. Perhaps the placement and
existence of a subcutaneous rod may have had something
to do with this occurrence. We believe this requires further
study and patients should be warned about the possible
injury to the lateral femoral cutaneous nerve when doing
the procedure and that it is usually temporary.
Heterotopic ossification was a common finding in our
review and was noted in 32 of 91 patients (35%). Although
the incidence of this complication is high in the present
study, we have not noted any adverse effect of this
occurrence to this date and we continue to follow the
patients. Previous reports have recommended thorough
lavage of the surgical site for prevention of this compli-
cation. We believed it was more prominent in patients who
had the ASPIF left in longer; however, we were unable to
prove that with the current database.
The subcutaneous fixator is intended as a temporary
treatment with removal typically performed after 12 weeks.
Disruptions of the pelvic ring are complex injuries and
should be managed on a case-specific basis. The ASPIF
technique offers comfort and mobility for patients; it is not
difficult to use because it builds on the prior work on
external pelvic fixation [1, 2, 4, 7, 11–17, 19, 21], two pin
fixators [2, 4, 19], and subcristal pin location [2, 4, 17]. It
allows stable anterior fixation when combined with pos-
terior reduction and fixation where indicated. Several
complications, including technical errors, can be avoided
by adhering to a proper technique and being familiar with
the implants. Infection rates (3%) and aseptic loosening
(0%) are low but heterotopic ossification and irritation of
the lateral femoral cutaneous nerve are common and need
to be further evaluated.
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