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Abstract
Background: This study was done to
evaluate the operative results of posterior wall fractures of
the acetabulum.
Methods: This retrospective study included 45 patients
who had undergone open reduction and internal fixation for
posterior wall fractures of the acetabulum .Their functional
outcome, at minimum of five years follow-up was evaluated.
Results: The post-operative reduction was graded as
excellent in 35%, good in 40%, fair in16% and poor in 9% cases.
87.9% of patients operated within first five days had good or
excellent reduction which was significantly more than those
operated beyond this percentage.
Conclusion: There is a positive relationship between quality
of reduction and functional outcome. The quality of reduction is
significantly affected by surgical lag. Though certain amount of
degenerative changes is inbuilt in the mechanism of injury the
main aim should be to avoid unnecessary delay and always
strive to achieve anatomical reduction for the best possible
functional outcomes for the patient.
J.Orthopaedics 2007;4(1)e17
Introduction:
Acetabular fractures are one of those
injuries in which even the best efforts of the treating surgeon
may not bring back the patient to his pre injury level [11]. The
main complication that may arise following a fracture acetabulum
is post-traumatic osteoarthrosis [5]. This leads to significant
discomfort, pain and loss of mobility. According to Judet and
Letournel operative treatment offers the best chance of
reducing post traumatic osteoarthritis for all displaced
acetabular fractures [5]. A study by Olson et al, has revealed
that there occurs marked alteration in the mechanics of load
transmission across the hip after fracture of the posterior wall
of the acetabulum [14]. These findings are consistent with the
clinical observations of Rowe and Lowell that conservative
management of large fractures of the posterior wall of the
acetabulum predisposes to hip osteoarthrosis [5]. This
retrospective study was done to assess the results of the
operative management of fractures of the posterior wall of the
acetabulum.
Materials and methods:
Between July 1995 and April 2000, 53 patients
with posterior wall fractures of the acetabulum were treated by
open reduction and internal fixation at the department of
Orthopedics, Dayanand Medical College and Hospital, Ludhiana.
Patient’s whose five year follow-up was
available were taken into the study group. Out of the 53
patients treated, follow-up of 45 patients was available. The
study group consisted of 38 male and seven female patients.
Right hip was involved in 26 cases and 19 cases had left sided
involvement. The most common mechanism of injury was motor
vehicle accident (40 patients). Three patients had motor vehicle
pedestrian accident and two had fractured acetabulum after fall
from height. Associated injuries were present in 30 patients.
Twenty three of these had fractures other than fracture
acetabulum, six had abdominal injuries, four had associated head
injury and an equal number of patients had chest injury. There
were two patients with sciatic nerve palsy.
All patients were evaluated pre- operatively
with three standard plain radiographs (one AP and two oblique
Judet views) and a two dimensional computed tomography scan.
Kocher and Langenbeck’s approach was used in 31 patients and an
extensile triradiate approach was used in the remaining 14. A
triradiate approach was preferred when visualization of the
fracture was impaired because of obesity or musculature of the
patient. When the triradiate approach was used, a desired
anterior limb dissection was done along with greater trochanter
osteotomy.
Prophylactic antibiotic (cephalosporin and
aminoglycoside) treatment was used in the peri-operative period
and were stopped on the 3rd post operative day. Ankle pump,
static quadriceps and static glutei exercises were started on
day one. Touch-down ambulation with support was started on 3rd
to 4th day after surgery and full weight bearing was
individualized. Before the patient was discharged from the
hospital, three standard radiographs of the pelvis were
obtained. For each of these radiographs the maximum displacement
seen, at any of the radiographic lines of the acetabulum or the
innominate bone, was recorded in millimeters. The highest of the
three values were used to grade reduction, according to the
categories given in table 1.
At each follow up three standard radiographs
of the pelvis were taken. These radiographs were graded for
changes according to the criteria described by Matta as shown in
table II.
At five years, the patient’s functional
outcome was evaluated using the clinical grading system
developed by Merle-d-Aubigne and Postel and subsequently
modified by Matta [6]. This system has been generally accepted
as the clinical grading system to evaluate results of acetabular
fractures [11]. At follow up the AP radiographs were assessed
for heterotrophic ossification and graded as per the Brooker et
al classification [1].
Observation and
results:
The post operative
radiographs were assessed for adequacy of reduction. It was
graded as excellent in 16 hips (35%), good in 18 hips (40%),
fair in seven hips (16%) and poor in four (9%) hips. Twenty-nine
out of thirty-three (87.9%) patients operated within five days
had good or excellent reduction, whereas only 41.7% operated
beyond five days had the same result. From table III it can be
seen that there are significantly more chances of obtaining good
or excellent reduction if patient is operated upon in first five
days after injury.The final functional outcome as assessed by
Merle-de-Aubigne and Postel’s modified criteria, was excellent
in 13 (29%), good in 17(38%), fair in seven (16%) and poor in
eight (18%). As evident in table IV, 80% of the patients who had
achieved good or excellent reduction post-operatively, had good
or excellent functional outcome at five years follow-up. On the
other hand only 13.3% of patients with fair or poor
post-operative reduction could achieve a good functional
outcome. This difference is statistically significant. Thus, the
final functional outcome is strongly affected by post operative
reduction achieved.
There were seven cases of
osteoarthrosis. Two of these patients had severe joint space
narrowing, osteophyte formation and required total hip
replacement. The other five had minimal joint space narrowing
and sclerosis, out of which three had good and two had fair
functional outcome. There were four cases of osteonecrosis out
of which two were grade IV and required total hip replacement.
In the other two patients, we did core decompression and their
overall result was good. There were five cases of heterotrophic
ossification, one grade I, one grade II and three grade III. We
observed no correlation of development of heterotrophic
ossification with regards to surgical approach and timing of
operation.
There were no cases of
iatrogenic nerve palsy. Two patients had post traumatic sciatic
nerve palsy, both involving the peroneal component. One
recovered partially with slight hypoesthesia in the peroneal
distribution of nerve. The course of the other nerve palsy was
static and later required foot drop splint during mobilization.
There were three cases of wound infection, two acute and one
late. Acute infection was treated by wound wash, debridement and
closure over a suction drain. Antibiotics were given for a
period of six weeks. These patients responded to treatment and
the infection healed completely. One of the patients followed up
late, at nine months with a discharging sinus. Radiograph of
this patient showed chondrolysis and required excision
arthroplasty. There were four cases of proved deep venous
thrombosis and were treated by standard anticoagulant protocol.
Table I
Grading of reduction:-
Grade
Displacement
Excellent
0 - 1 mm
Good
< 2 mm
Fair
3 - 5 mm
Poor
> 5 mm
Table II
Relation between Surgical lag and the
reduction
|
Surgical Lag
|
Reduction |
|
Days |
Excellent |
Good |
Fair |
Poor |
|
0-3 |
8 |
8 |
1 |
0 |
|
4-5 |
6 |
7 |
2 |
1 |
|
6-7 |
2 |
2 |
3 |
0 |
|
8-10 |
0 |
1 |
1 |
0 |
|
> 10 day |
0 |
0 |
0 |
3 |
For statistical purpose, good
or excellent reduction and fair or poor reduction were clubbed
together and, number of days taken were 0-5 and > 6 days. The
value of p is <0.01 and thus statistically significant.
Table
III
Relation of functional outcome to the
quality of reduction
|
Reduction |
Functional
outcome |
|
|
Excellent |
Good |
Fair |
Poor |
|
Excellent |
6 |
7 |
1 |
2 |
|
Good |
7 |
8 |
2 |
1 |
|
Fair |
0 |
2 |
2 |
3 |
|
Poor |
0 |
0 |
2 |
2 |
For statistical purpose
good or excellent clinical results and fair or poor clinical
results are clubbed together. Similarly good or excellent
reduction and fair or poor reduction are clubbed together. P
value is<0.01 and thus statistically significant.
Discussion :
The most important factor responsible for successful long term
clinical outcome after surgical fixation of acetabular fracture
is the quality of reduction [2, 5, 16]. In our study, the
quality of reduction is significantly affected by surgical lag
beyond five days. Matta in his study of 262 acetabular
fractures concluded that a surgical lag beyond fourteen days
significantly affected the quality of reduction [6].
There are changes in the mechanisms of the hip joint after a
fracture and a failure of anatomical operative repair to restore
normal loading [14]. With the circumferential congruity of the
acetabulum disrupted, the femoral head makes superior contact
without the development of normal peripheral contact force.
Decreased peripheral contact also explains the increase in
contact force within the superior aspect of the acetabulum of
the fractured joint. Hadley et al observed that increased
pressure in the hip, when maintained for a period of years, was
prognostic for degenerative changes [3]. The occurrence of post
traumatic osteoarthritis is the greatest in patients with
articular surgical incongruity or residual subluxation of hip
joint. After a perfect reduction within 3 weeks of injury
Letournel noted osteoarthritis in only 10.2% of cases as
compared with 37.5% with imperfect reduction [5]. In our series,
four out of eleven (36.7%) patients with fair or poor reduction
developed osteoarthrosis, out of which two required total hip
replacement. There were three out of 34(8.9%) patients with
excellent or good reduction that developed osteoarthritis. In
none was osteoarthrosis severe enough to warrant second surgery.
The osteoarthrosis could be attributed to imperfect reduction
and damage to femoral head or joint cartilage at the time of
injury.
AVN can significantly affect post operative outcome [18]. The
incidence of AVN after operative treatment of acetabular
fracture has generally ranged from 3-9 % [5, 6, 7] with majority
identified between three and eighteen months after surgery [5].
In our series there were four(9%) cases of AVN out of which two
had grade IV AVN. Matta reported AVN in 8(3%) of 262 fractures
[6], whereas Letournel and Judetreported AVN in19 of 492(4%)
fractures [5]. Letournel has noted an increased incidence of AVN
of the femoral head in cases presenting after 3 weeks and those
associated with posterior fracture dislocation [5] .Higher rates
of osteonecrosis (23%) have been reported by Wright [17].
Out of the five patients with heterotrophic ossification three
patients were operated by triradiate approach. Out of these two
had grade III and one had grade II heterotrophic ossification.
In all three patients the final result was compromised because
of heterotrophic ossification. In other two patients operated by
Kocher and Langenbeck approach, one patient had grade I and
other grade III heterotrophic ossification. In patient with
grade III heterotrophic ossification, the result had
deteriorated from initial good result at six months to fair
result at final follow-up. Heterotrophic ossification results in
significant loss of hip motion in fewer than 5% of patients [4,
12, 13]. Our results are in concurrence with the same.
There is a strong relationship between quality of reduction and
clinical results [10]. Yet, certain amount of degenerative
changes is inbuilt in the mechanism of injury. In all
probability, the fate of femoral head is determined at the time
of injury [2, 8]. The overall results from this series validate
the efficacy of open reduction internal fixation as the
treatment of choice for displaced posterior wall fractures of
the acetabulum.
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