Clinical outcome of simple surgicalexcision of accessory navicular bone in patients with failed conservativetreatment ABSTRACTObjective: To report theclinical results of surgical management of accessory navicular bone with simplesurgical excision.Methods: This prospectively observational study reviewed theresults of 16 consecutive patients (17 feet) who underwent surgical treatmentfor symptomatic accessory navicular.
The patients ranged in age from 16 to 25years (average,20.5 years; mean, 16.8 years) at the time of surgery. Allpatients had a type II accessory navicular.
The study was conducted fromJanuary 2015 to February 2017.Pain intensity using VAS system was determinedboth preoperatively and postoperatively of the 17 feet included in the study.Results: The average preoperative VAS score was (range 6.24+0.83).
The averagepostoperativeVAS score was (range 0.94+0.83)). At last follow-up, 16 of 17feet were without any pain, no patient had activity limitations,only 1 footrequired re do surgery. Postoperatively, no patient had a clinically notablechange in their preoperative midfoot longitudinal arch alignment.Conclusion:Surgical management gives promising results in patients whohave failed conservative treatment initially. Overall, the procedure(simplesurgical excision) provides reliable pain relief and patient satisfaction. Inthe current study, the clinical status of each patient improved significantlypostoperatively.
Key words: accessorynavicular,surgical excision,kidner procedure IntroductionAccessory navicular bone causes pain, tenderness and discomfort. InitiallyBauhin used the term accessory navicular in 16051,2 ,later Von lushka described it as ‘jointlike” after finding itin a young patient bilaterally;he also described its relation with posteriortibial tendon for the first time3. The study kept evolving and in the early literature accessorynavicular 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 theopinion that simple surgical excision is enough to relieve the symptoms.lateron,Kidner hypothesized that accessory navicular causes medial displacement ofposterior tibial tendon and recommended more complex procedure that includedexcision 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 excisionare being used for the treatment but still simple excision is the most commonsurgical procedure and effectively relieves the pain.
The foot and ankle have numerous accessory ossification centres,butthe most common is accessory navicular bone occurring between 4-14% ofpopulation in adolesence,in children the incidence is 4-21%.Accessory navicularhas three characteristic types, type I is a well-defined,round shape that iscompletely separate from the true navicular bone.It is embedded in posteriortibial tendon and is 30% of all the accessory navicularis.Type II accessorynavicularis are joined by 1-3mm synchondrosis to the navicular bone.
Type II isthe most common form(50-60%).Type III accessory navicularis are joined by abony connection to the navicular bone having the least occurance (10-20%).5,7Presence of Pain and tenderness are the main complaints ofaccessory navicular. The symptoms can be addressed conservatively by shoemodification, physiotherapy,local and oral antinflammatory agents. Whenconservative measures fail, surgical treatment is recommended. Materials and MethodsThis prospective descriptive study was conducted in Department ofOrthopaedic Surgery and Traumatology, Unit-II of Mayo Hospital from January2015 to February 2017.All the cases presented to outdoor department with accessorynavicular bone after failed conservative management for more than 3 months withphysical therapy and analgesics were included in this study. The patient havingage ranging from 15-25 years of age.
All the cases with previous history oftrauma or surgery performed on the foot with accessory navicular bone wereexcluded from the study. Preoperative anteroposterior, lateral and obliquex-rays were performed. Preoperative baseline pain according to visual analoguescale (Fig.
1) were calculated. All these cases were inducted in the study onlyafter the ethical approval from institutional review board and availability ofconsent from the participant. Studywas conducted on 16 patients having symptomatic accessory navicular bone. Allsurgeries were performed under general anesthesia or spinal anaesthesia in supine position and pneumatic tourniquetwas used in all cases Operative technique Afterpalpating the accessory navicular bone, a skin crease transverse incision of2-3 cm was used. After exposing the bone and retracting the posterior tibialistendon, the accessory navicular was shaved off carefully from the navicularbone with a sharp osteotome. Wound was closed using prolene 2/0 after checkingthe posterior tibialis tendon.
Post operatively X rays were taken and patientadvised to have partial weight bearing till two weeks.Meanfollow-up period was 6 months. VAS score was used to quantify painpre-operatively and post-operatively.
Fig. 1 Visual Analogue Scale (VAS) Results We had 16 patients with 17 feet with one of themhaving bilateral accessory navicular bone. There were 10 (62.5%) female and 6 (37.5%) malepatients. All of them had chief complaint of pain over the medial border ofnavicular bone specially while wearing closed shoes.
The mean duration of painin patient with type I accessory navicular bone was 4.25± 1.71 years while thatin 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 analoguescale (VAS) was 6.
25± 0.96, 6.22± 0.
83 and 6.25±0.96 in type I, II and IIIaccessory navicular bone respectively. The overall mean preoperative VAS was6.24± 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 bonerespectively. The overall postoperative VAS was 0.
94± 0.83. There was statistically extremely significantimprovement in VAS postoperatively with p-value being less than 0.0001.There were two cases of postoperative superficialinfections that were managed with dressing and oral antibiotic according toculture and sensitivity.Table 1 demonstrates the demographic data of thepatients included in this study. Table No.
1Demographic 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 Despitethe incidence of accessory navicular of about 10-14% in normal population 5,only 1% of the patients undergo surgical excision. 5,14. Typesof accessory navicular have been described depending on its relation to thenavicular bone.in type I it is embedded in posterior tibialis tendon occurringin the form of ossicle.
type II is the most common and it occurs in the form ofsynchondrosis having a fibrocartilagenous connection with the navicular bone.intype III bony connection with the navicular bone is present8,9 11Therelationship of flexible flat foot and accessory navicular is now consideredaccidental,13,14,15,though it was considered an established fact inthe past.Atinitial presentation conservative treatment by using nonsteroidalanti-inflammatory (Oral and local applicant), immobilization in cast, orthoses,local steroid injection, and physical therapy is advised.Afterfailure of conservative modalities surgical treatment is treatment choice thatis being practiced for years. There are differentsurgical techniques proposed for accessory navicular. These include simpleexcision of aceesory navicular bone or another procedure that was described byKidner and was named after him Kidnerprocedure,it include excision of accessory navicular and re-routing the tibialis posterior tendon in moreplantar position5-6,9.Percutaneoustechnique for accessory navicular excision has also evolved over past few years.
Due to simple procedure and comparable results simple excision of navicularbone is still the choice of surgeons in many countries. The procedure has minor complications and effectively reducespain14.Barbara Jasiewicz et al5 have conducted a randomizedclinical trial of 22 patients having accessory navicular bone. Total 34 feetwere treated with simple surgical excision.
The patients were followed-up to 20weeks. Mean VAS results preoperative and post operative were 5.9 and 1.7. Complications were present intwo patients (6.1%).
Patients were returned to daily normal activities withgood results. Franz J et al2in a study of 13 patients (14 feet),average follow-up was103.4 months. The preoperative andpostoperative AOFAS Midfoot Scale5 was calculated for each patient.
All thepatients had satisfactory recovery and returned to daily activities, only one patienthad post operative occasional pain that was relieved by analgesia.Inthe current study,VAS was used to report the clinical outcomes of 16 patients (17feet) who were surgically managed for symptomatic accessory navicular withsimple excision of the accessory navicular. Return to normal activities withoutpain was our goal of treatment. The pain improved in VAS scale from apreoperative score of (6.24+0.83) postoperative score of (0.94+0.
83) (p< 0.5). All 17 feet had an improvement in pain, 16 feet had no pain atall postoperatively. Only one of 17 feet required re operation.over all. Allpatients reported pain relief and satisfaction with the surgery results. Themain drawback of our study was lack of a control and/or comparative group, smallsample size and short follow-up period.
Largersample size with longer follow-up is required. Conclusion Treatmentof symptomatic accessory navicular after failed conservative treatment withsimple surgical excision givessatisfactory outcome in terms of pain relief and Kidner procedure doesn’tconfer any significant results over simple excision. A longer follow-up withgreat number of sample will help establish the efficacy of this procedure andthus further study is required. References 1Coughlin MJ. Sesamoids and accessory bones of the foot. In: Coughlin MJ, MannRA, editors.
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