Clinical status of each patient improved significantly postoperatively.

Clinical outcome of simple surgical
excision of accessory navicular bone in patients with failed conservative
treatment

 

 

 

 

 

ABSTRACT

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Objective: To report the
clinical results of surgical management of accessory navicular bone with simple
surgical excision.

Methods: This prospectively observational study reviewed the
results of 16 consecutive patients (17 feet) who underwent surgical treatment
for symptomatic accessory navicular.The patients ranged in age from 16 to 25
years (average,20.5 years; mean, 16.8 years) at the time of surgery. All
patients had a type II accessory navicular. The study was conducted from
January 2015 to February 2017.Pain intensity using VAS system was determined
both preoperatively and postoperatively of the 17 feet included in the study.

Results: The average preoperative VAS score was    (range 6.24+0.83). The average
postoperative
VAS score was  (range 0.94+0.83)). At last follow-up, 16 of 17
feet were without any pain, no patient had activity limitations,only 1 foot
required re do surgery. Postoperatively, no patient had a clinically notable
change in their preoperative midfoot longitudinal arch alignment.

Conclusion:
Surgical management gives promising results in patients who
have failed conservative treatment initially. Overall, the procedure(simple
surgical excision) provides reliable pain relief and patient satisfaction. In
the current study, the clinical status of each patient improved significantly
postoperatively.

 

 

Key words: accessory
navicular,surgical excision,kidner procedure

 

 

Introduction

Accessory navicular bone causes pain, tenderness and discomfort. Initially
Bauhin used the term accessory navicular in 16051,2 ,later Von lushka described it as ‘jointlike” after finding it
in a young patient bilaterally;he also described its relation with posterior
tibial tendon for the first time3. The study kept evolving and in the early literature accessory
navicular was being described as sesamoid bone, accessory scaphoid, prehallux,
os tibiale externum,,os naviculare secundarium, and navicular secundum.
Froleich in 1909 said that accessory navicular produces flatfoot,he was of the
opinion that simple surgical excision is enough to relieve the symptoms.later
on,Kidner hypothesized that accessory navicular causes medial displacement of
posterior tibial tendon and recommended more complex procedure that included
excision of navicular bone as well as re insertion of tendon to the bone,2,3,5.

Both the surgical procedures ;Kidner as well as simple excision
are being used for the treatment but still simple excision is the most common
surgical procedure and effectively relieves the pain.

The foot and ankle have numerous accessory ossification centres,but
the most common is accessory navicular bone occurring between 4-14% of
population in adolesence,in children the incidence is 4-21%.Accessory navicular
has three characteristic types, type I is a well-defined,round shape that is
completely separate from the true navicular bone.It is embedded in posterior
tibial tendon and is 30% of all the accessory navicularis.Type II accessory
navicularis are joined by 1-3mm synchondrosis to the navicular bone.Type II is
the most common form(50-60%).Type III accessory navicularis are joined by a
bony connection to the navicular bone having the least occurance (10-20%).5,7

Presence of Pain and tenderness are the main complaints of
accessory navicular. The symptoms can be addressed conservatively by shoe
modification, physiotherapy,local and oral antinflammatory agents. When
conservative measures fail, surgical treatment is recommended.

 

 

 

 

 

 

Materials and Methods

This prospective descriptive study was conducted in Department of
Orthopaedic Surgery and Traumatology, Unit-II of Mayo Hospital from January
2015 to February 2017.

All the cases presented to outdoor department with accessory
navicular bone after failed conservative management for more than 3 months with
physical therapy and analgesics were included in this study. The patient having
age ranging from 15-25 years of age. All the cases with previous history of
trauma or surgery performed on the foot with accessory navicular bone were
excluded from the study. Preoperative anteroposterior, lateral and oblique
x-rays were performed. Preoperative baseline pain according to visual analogue
scale (Fig.1) were calculated. All these cases were inducted in the study only
after the ethical approval from institutional review board and availability of
consent from the participant.

 

Study
was conducted on 16 patients having symptomatic accessory navicular bone. All
surgeries were performed under general anesthesia or spinal anaesthesia  in supine position and pneumatic tourniquet
was used in all cases

 

Operative technique

 

After
palpating the accessory navicular bone, a skin crease transverse incision of
2-3 cm was used. After exposing the bone and retracting the posterior tibialis
tendon, the accessory navicular was shaved off carefully from the navicular
bone with a sharp osteotome. Wound was closed using prolene 2/0 after checking
the posterior tibialis tendon. Post operatively X rays were taken and patient
advised to have partial weight bearing till two weeks.

Mean
follow-up period was 6 months. VAS score was used to quantify pain
pre-operatively and post-operatively.

 

 

 

 

 

 

 

Fig. 1 Visual Analogue Scale (VAS)

 

 

 

 

Results

 

We had 16 patients with 17 feet with one of them
having bilateral accessory navicular bone.

There were 10 (62.5%) female and 6 (37.5%) male
patients. All of them had chief complaint of pain over the medial border of
navicular bone specially while wearing closed shoes. The mean duration of pain
in patient with type I accessory navicular bone was 4.25± 1.71 years while that
in type II and III was 3.56± 1.81 years and 4.00± 1.55 years respectively.

The preoperative x-ray revealed four (23.5%) type I,
9 (52.9%) type II and 4 (23.5%) type III accessory navicular bone.

Mean preoperative pain according to visual analogue
scale (VAS) was 6.25± 0.96, 6.22± 0.83 and 6.25±0.96 in type I, II and III
accessory navicular bone respectively. The overall mean preoperative VAS was
6.24± 0.83 (5-7).

The mean postoperative VAS was 2.00 ± 0.82, 0.89±
0.33 and 0 in patient with type I, II and III accessory navicular bone
respectively. The overall postoperative VAS was 0.94± 0.83.

There was statistically extremely significant
improvement in VAS postoperatively with p-value being less than 0.0001.

There were two cases of postoperative superficial
infections that were managed with dressing and oral antibiotic according to
culture and sensitivity.

Table 1 demonstrates the demographic data of the
patients included in this study.

 

 

Table No.1
Demographic data of the patients in study

 

SN

Types of
Accessory Navicular Bone

Number of Patient
N (%)

Gender
distribution

Age (Years)
Mean± SD

Preoperative VAS
Mean± SD

Postoperative VAS
Mean± SD

Male

Female

1

Type I

4(23.5%)

3

1

16.00 ± 1.41

6.25± 0.96

2.00 ± 0.82

2

Type II

8(23.5%)

0

8

19.00  ± 3.02

6.22± 0.83

0.89± 0.33

3

Type III

4(23.5%)

3

1

21.00 ± 1.83

6.25±0.96

0

 

 

Discussion

 

Despite
the incidence of accessory navicular of about 10-14% in normal population 5,
only 1% of the patients undergo surgical excision. 5,14.

Types
of accessory navicular have been described depending on its relation to the
navicular bone.in type I it is embedded in posterior tibialis tendon occurring
in the form of ossicle.type II is the most common and it occurs in the form of
synchondrosis having a fibrocartilagenous connection with the navicular bone.in
type III bony connection with the navicular bone is present8,9 11

The
relationship of flexible flat foot and accessory navicular is now considered
accidental,13,14,15,though it was considered an established fact in
the past.

At
initial presentation conservative treatment by using nonsteroidal
anti-inflammatory (Oral and local applicant), immobilization in cast, orthoses,
local steroid injection, and physical therapy is advised.

After
failure of conservative modalities surgical treatment is treatment choice that
is being practiced for years. There are different
surgical techniques proposed for accessory navicular. These include simple
excision of aceesory navicular bone or another procedure that was described by
Kidner and was named after him Kidner
procedure,it include excision of accessory navicular and re-routing the tibialis posterior tendon in more
plantar position5-6,9.Percutaneous
technique for accessory navicular excision has also evolved over past few years.
Due to simple procedure and comparable results simple excision of navicular
bone is still the choice of surgeons in many countries. The procedure has  minor complications and effectively reduces
pain14.

Barbara Jasiewicz et al5 have conducted a randomized
clinical trial of 22 patients having accessory navicular bone. Total 34 feet
were treated with simple surgical excision. The patients were followed-up to 20
weeks. Mean VAS results pre
operative and post operative were 5.9 and 1.7. Complications were present in
two patients (6.1%). Patients were returned to daily normal activities with
good results.

Franz J et al2
in a study of 13 patients (14 feet)
,average follow-up was
103.4 months. The preoperative and
postoperative AOFAS Midfoot Scale5 was calculated for each patient. All the
patients had satisfactory recovery and returned to daily activities, only one patient
had post operative occasional pain that was relieved by analgesia.

In
the current study,VAS was used to report the clinical outcomes of 16 patients (17
feet) who were surgically managed for symptomatic accessory navicular with
simple excision of the accessory navicular. Return to normal activities without
pain was our goal of treatment. The pain improved in VAS scale from a
preoperative score of (6.24+0.83) postoperative score of (0.94+0.83)    (p

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