CASE REPORT
Failure of Femoral Neck System Fixation Due to Suboptimal Reduction in a Young Adult With a Garden Type IV Subcapital Fracture:
Conversion to Total Hip Arthroplasty. A Case Report
Humbert C. Kelsey Gary,* Nelson Vidal
Chang,** Natalia A. Gómez Palencia,* Cristian D. Tinoco Cervantes, *
José D. Alonso Cogollo#
*School of Medicine,
Universidad Simón Bolívar,
Barranquilla, Colombia
**Orthopedics and Traumatology Department, Clínica
General del Norte,
Barranquilla, Colombia
#School of Medicine, Universidad Metropolitana, Barranquilla, Colombia
ABSTRACT
We report the case of a 38-year-old nonsmoking man with a body mass index of 31.1 kg/m² who sustained a low-energy Garden type IV subcapital fracture
after a ground-level fall. Radiographs showed
a Garden type IV fracture
and a neck-shaft angle of 119°.
Internal fixation with the Femoral Neck System was
performed 12 days after injury.
Postoperative radiographs revealed
suboptimal reduction and off-center screw placement. At 8 months,
mechanical failure, loss of fixation,
nonunion, and avascular
necrosis were documented. Conversion to total hip arthroplasty was performed at 18 months.
One month later,
the Harris Hip Score
was 82/100, and the
patient had resumed daily activities without complications. Conclusions: Suboptimal
reduction and off-center implant placement, in the setting of delayed surgery,
contributed to implant failure. Even
with modern implants, the quality of anatomical reduction remains
the most important determinant of successful femoral head preservation in young adults.
Conversion to total
hip arthroplasty is an effective salvage strategy when internal fixation
fails.
Keywords: Femoral neck fracture; Femoral Neck System; suboptimal reduction; total hip arthroplasty; young adult.
Level
of Evidence: IV
Fallo de la osteosíntesis con un FNS por reducción subóptima en un adulto joven con una fractura subcapital tipo IV de Garden: conversión a artroplastia total de cadera.
Presentación de un caso
RESUMEN
Se presenta
el caso de un hombre de 38 años, no fumador, con un índice de masa corporal de 31,1 kg/m² que sufrió una fractura subcapital
tipo IV de Garden de baja energía tras una caída de propia altura. En las radiografías, se observó una
fractura tipo IV de Garden y un ángulo cervicodiafisario de 119°. Se realizó
una osteosíntesis con el Femoral Neck System a los 12 días. Las
radiografías posoperatorias revelaron una reducción subóptima y una posición no
central del tornillo. A los 8 meses,
se documentaron fallo mecánico,
desanclaje, seudoartrosis y necrosis avascular. A los 18 meses, se realizó la conversión a
artroplastia total de cadera.
Al mes, el Harris Hip Score
era de 82/100
y el paciente se reintegró a las actividades diarias sin complicaciones. Conclusiones: La reducción subóptima y la posición
no central del implante, en un contexto
de retraso quirúrgico, condicionaron el fallo del implante. Incluso con implantes modernos, la calidad de la reducción
anatómica es el determinante más importante del éxito de la preservación cefálica
en el adulto joven. La conversión a artroplastia total
de cadera es una estrategia de rescate efectiva
cuando la fijación interna fracasa.
Palabras clave: Fractura de cuello femoral; Femoral Neck System; reducción subóptima; artroplastia total de cadera; adulto joven.
Nivel de Evidencia: IV
INTRODUCTION
Coxa vara is defined as a femoral neck–shaft angle below 120°
(normal range, 125°–135°).1 This
morphology redistributes forces across the femoral neck and increases the shear
component.1,2
In
young adults, subcapital fractures following a fall
from standing height are uncommon. The patient described here had a neck–shaft
angle of 119°, a borderline value interpreted radiographically as apparent coxa vara morphology.1,3
Femoral
neck fractures are classified according to the orientation of the fracture line
using the Pauwels classification. Pauwels type III fractures have a vertical
fracture line (>50°), with predominantly shear forces that increase the risk
of instability, nonunion, and fixation failure.4,5
In young
patients with Garden type III–IV fractures, the primary goal is to preserve the
femoral head through internal fixation, provided that anatomical reduction can
be achieved. Reduction is considered suboptimal when there is residual femoral
neck shortening >5 mm, rotation
of the femoral head fragment,
or noncentral positioning of the implant’s head element.6
The Femoral Neck System (FNS) has been proposed
as a fixed-angle option that provides rotational stability.4,6,7 Its success,
however, depends critically on reduction quality and implant positioning. Some
multicenter series report a 10% early failure rate in Garden type III–IV
fractures with suboptimal reduction.5,6,8 Rates of nonunion, avascular necrosis, and
fixation failure are not consistently lower than those reported with cannulated
screws.9
Avascular necrosis of the femoral head results from disruption of the retinacular vessels. The main risk factors
are initial displacement (Garden types III–IV), delayed fixation, and
inadequate reduction.10,11 These factors increase the risk of varus
collapse, cut-out, nonunion, and avascular necrosis, potentially requiring
conversion to total hip arthroplasty.10,11
We present
a case of a low-energy Garden type IV subcapital fracture in a young
adult with a borderline neck–shaft angle of 119°. Suboptimal
reduction and implant malposition led to FNS failure, followed by nonunion and avascular necrosis requiring
conversion to arthroplasty. This case illustrates how severe initial
displacement, inadequate reduction, and poor implant
positioning can lead to internal
fixation failure, emphasizing the importance of not
accepting a nonanatomical reduction.
CASE REPORT
A
38-year-old male motorcycle taxi driver with a body mass index of 31.1 kg/m²
and no smoking history presented with left hip pain and loss of function
lasting 3 days after a ground-level fall. The patient provided informed consent
for publication of the case and images.
Clinical examination revealed limb shortening, external rotation, and pain on movement, with no neurovascular deficit.
Radiographs
showed a Garden type IV subcapital fracture with a
neck–shaft angle of 119°, a borderline value interpreted as radiographically apparent
coxa vara morphology (Figure 1). The fracture
line was vertical
(Pauwels type III) (Figure 2).
Internal fixation
with the FNS was performed 12 days after the injury under spinal anesthesia. The implant was selected for its fixed-angle design
and rotational stability in fractures subjected predominantly to shear forces. Closed reduction was performed under
fluoroscopic guidance in two planes. Shortening and rotation persisted,
preventing an optimal reduction. Nevertheless, the reduction obtained was
accepted and fixation was completed. Postoperative radiographs confirmed
suboptimal reduction, with residual femoral neck shortening >5 mm, rotation of the femoral head fragment,
and noncentral positioning of the main screw (Figures 3 and 4).
At 8
months, mechanical failure of the FNS was documented, with cut-out, nonunion
(absence of union and sclerosis of the fracture margins), and avascular
necrosis (loss of femoral head sphericity and
subchondral collapse) (Figures 5 and 6).
At 18
months, conversion to a complex primary total hip arthroplasty was performed
through a posterolateral (Gibson) approach. A 52-mm uncemented acetabular cup
with two screws, an 11-mm uncemented stem, and a 36-mm ceramic head were
implanted without intraoperative complications. Radiographs confirmed
satisfactory component positioning (Figures 7 and 8).
One
month after arthroplasty, limb length had been restored, the Harris Hip Score
was 82/100, and the patient had resumed his daily activities without
complications.
DISCUSSION
A low-energy subcapital fracture
in a young adult is uncommon. This patient had a borderline neck–shaft angle of
119°, a radiographic finding consistent with apparent coxa vara
morphology.1,3
In
young patients with completely displaced intracapsular fractures (Garden type
IV), the primary goal is to preserve the femoral head through internal
fixation, provided that anatomical reduction and stable fixation can be achieved.10,11 Success depends critically on several concurrent
factors: time to surgery, reduction quality, and implant positioning.6,9
Surgery
was performed 12 days after the initial injury. Although the evidence on the precise effect of delayed surgery
on avascular necrosis is not entirely consistent, most series agree that
displaced femoral neck fractures in young
adults should be treated urgently, ideally within the first 24 hours, to minimize the risk of nonunion and avascular necrosis.12,13 A 12-day
delay falls well outside this recommended window and represents an additional
risk factor.12
The FNS offers theoretical biomechanical advantages over cannulated screws,
including rotational stability
and a fixed-angle design.4,5 However, recent publications indicate that these
advantages do not consistently translate into fewer serious complications when
reduction is nonanatomical. A comparative meta-analysis concluded that, although the FNS
may be associated with shorter time to union and less femoral neck shortening,
rates of non-union, avascular necrosis, and fixation failure are similar to
those reported with cannulated screws.8,9 Multicenter series have identified initial
displacement (Garden types III–IV), suboptimal reduction, a large tip–apex distance, and excessive device sliding as
the main predictors of early FNS failure.5,6,8
In this case, immediate postoperative radiographs showed
nonanatomical
reduction, with residual
femoral neck shortening and
rotation of the femoral head fragment, together with noncentral positioning of
the main FNS screw. These technical findings, combined with the 12-day surgical
delay and initial Garden type IV displacement, provide a multifactorial explanation
for the mechanical failure, cut-out, nonunion, and avascular necrosis
documented at 8 months.5-9
When
internal fixation fails and femoral head viability is lost in a young patient,
conversion to total hip arthroplasty offers a predictable and effective salvage
strategy. Available series report high rates of reoperation and conversion to arthroplasty after
failed internal fixation
in young adults.
They also show that arthroplasty provides better medium-term functional outcomes than repeated
attempts at internal fixation in this setting.10,11,14
This
case is noteworthy because several unusual factors occurred in a single
patient: a low-energy Garden type IV subcapital fracture in a young nonsmoking adult with a
borderline neck–shaft angle, delayed treatment
at 12 days using a modern fixed-angle implant (FNS), suboptimal
reduction, and noncentral positioning of the implant’s head element. This
combination led to mechanical failure and the need for conversion to total hip
arthroplasty 18 months after the initial injury.
The
main lesson from this case is that, even with advanced fixation devices such as
the FNS, anatomical reduction and correct implant positioning remain the most
important technical determinants of successful femoral head preservation in
young patients. Suboptimal reduction should not be accepted. Surgical delay may
increase biomechanical risk, but failure is primarily explained
by the reduction and fixation
technique. When these factors
coexist and avascular necrosis or nonunion develops, conversion to total
hip arthroplasty is a valid
salvage option with good
short-term functional outcomes.
CONCLUSIONS
A
low-energy Garden type IV subcapital fracture in a
young adult carries a high risk of complications. FNS failure occurred in the
setting of delayed surgery, suboptimal reduction, and noncentral implant
positioning. The latter two were
identified as the main technical factors.
Successful
femoral head preservation depends primarily on
anatomical reduction and correct fixation. When fixation fails and femoral head viability is lost, conversion to total hip arthroplasty is an effective salvage strategy.
This
case reinforces that reduction quality remains the most important technical
determinant of success, even with modern fixed-angle implants.