Os subfibulare. Investigation of an accessory bone

Outcomes of ossicle resection and anatomic reconstruction of lateral ligaments for chronic ankle instability with large malleolar accessory ossicles

BACKGROUND

Malleolar accessory ossicles can be found in patients with chronic lateral ankle instability (CLAI). Ossicle resection combined with the modified Broström procedure is the most commonly used surgical method. However, an unrepairable gap after ossicle resection often occurs in patients with large ossicles.

PURPOSE

This study analysed the clinical outcomes of ossicle resection and anatomic ligament reconstruction (ALR) for CLAI with large malleolar accessory ossicles.

METHODS

This study was a retrospective case series. Since 2014, we have adopted ALR for patients with difficulties using the modified Broström procedure after ossicle resection. Sixteen patients with chronic ankle instability and malleolar accessory ossicles were treated with this method between December 2014 and February 2018. The average age of the patients at the time of surgery was 28.9 (range, 16-65) years. They were followed up for an average time of 26.9 (range, 12-47) months. The clinical outcomes were evaluated using the Visual Analogue Scale, Karlsson-Peterson ankle scoring system, subjective satisfaction of patients, and radiographic parameters.

RESULTS

All unrepairable cases occurred in patients with ossicles larger than or equal to 10 mm. The VAS score improved from 3.5 ± 1.6 preoperatively to 1.4 ± 1.0 at the final follow-up (p < 0.05), and the Karlsson-Peterson score improved significantly from 52.7 ± 15.1 to 86.4 ± 8.2 (p < 0.05). There was also an obvious change in the varus talar tilt angle (15.4 ± 2.0° vs 6.2 ± 1.6°, p < 0.05) and anterior talar displacement (14.3 ± 2.1 mm vs 6.3 ± 1.4 mm, p < 0.05). Fourteen patients (87.5%) were satisfied (excellent or good) with their clinical outcomes.

CONCLUSION

If modified Broström procedure is difficult to accomplish effectively after ossicle resection for chronic ankle instability with large malleolar accessory ossicles, ALR is a viable option with satisfactory clinical results.

Type VII All-epiphyseal Fractures of the Lateral Malleolus and the Origin of Subfibular Ossicles

BACKGROUND

A subfibular ossicle (SO), also known as an os subfibulare, is present in ∼1% of the general population. Two theories have been proposed to explain the origin of SOs: (1) as a failure of fusion of a secondary center of ossification; (2) as a posttraumatic sequela. This report offers prospective, longitudinal radiographic evidence for the formation of SOs as a posttraumatic sequela of type VII transepiphyseal fractures of the lateral malleolus in children.

METHODS

This Institutional Review Board-approved study was performed at a tertiary care pediatric hospital from March 2012 to April 2019. The study group included 37 children with a type VII fracture of the lateral malleolus and a minimum follow-up of 6 months.

RESULTS

Twenty-one children (57%) healed their fracture. Sixteen children (43%) went on to form SOs. The most common location for the fractures was the distal third of the epiphysis, and the most common fracture type forming SOs was a sleeve avulsion fracture. Four of the children forming SOs have had surgery to address pain and recurrent sprains.

CONCLUSIONS

Overall, 43% of children who sustained a type VII fracture of the lateral malleolus went on to form SOs, giving support to the posttraumatic theory of origin. Sleeve avulsion fractures have the greatest chance of forming SOs. So far, 4 of the 16 children forming SOs have undergone surgery for ankle pain and recurrent sprains.

LEVEL OF EVIDENCE

Level II.

Presence of Subfibular Ossicle Does Not Affect the Outcome of Arthroscopic Modified Broström Procedure for Chronic Lateral Ankle Instability

PURPOSE

To evaluate the clinical and radiological outcomes of the all-inside, arthroscopic, modified Broström procedure (MBP) used to treat chronic lateral ankle instability (CLAI) according to subfibular ossicle (SFO) status.

METHODS

Between January 2013 and September 2016, we retrospectively analyzed CLAI patients who underwent the arthroscopic MBP. When performing the arthroscopic MBP, SFO was removed with all inside technique regardless of size. Patients who were not followed for more than a minimum of 12 months after surgery were excluded. The patients were divided into 2 groups: ankles with SFOs were assigned to the SFO group and the others to the non-SFO (NSFO) group. The evaluation tools used included the American Orthopedic Foot and Ankle Society (AOFAS) ankle-hind foot score, a pain visual analog scale, and the talar tilt angle.

RESULTS

Following the inclusion criteria, we included 125 patients (125 ankles) in this study. The SFO group consisted of 26 patients and the NSFO group consisted of 99 patients. The preoperative scores in the 2 groups shows no significant difference except for AOFAS scores. The final AOFAS scores in both groups improved compared with the preoperative scores (18.4 ± 16.3 and 22.1 ± 21.6 for the SFO and NSFO groups, respectively). The final follow-up visual analog scale scores also improved in both groups (5.0 ± 1.7 and 5.2 ± 1.4, respectively). The mean ± standard deviation talar tilt improved from 8.7 ± 5.0° preoperatively to 4.6 ± 3.6° at the final follow-up in the SFO group, and from 7.3 ± 4.4° preoperatively to 3.2 ± 3.0° at the final follow-up in the NSFO group. Neither the preoperative nor final talar tilt angle differed between the 2 groups (P = .300 and P = .072, respectively).

CONCLUSIONS

All-inside arthroscopic MBP after SFO resection was as successful as the same surgery without SFO resection. The clinical outcomes of the SFO and NSFO groups did not differ. Both groups achieved successful radiological outcomes at the last follow-up. All-inside arthroscopic MBP is a reliable treatment for CLAI patients regardless of SFO status.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Avulsion fracture of anterior talofibular ligament from talus: A case report

Anterior talofibular ligament (ATFL) injuries can occur in three different distinct patterns; rupture of the ligament as a pure soft tissue injury, an avulsion fracture at the ATFL's attachment to either the fibula or the talus. Although fibular avulsion fractures are common, avulsion fracture of ATFL from talus is extremely rare with a single previously reported case in the current literature. A 34-year-old female with ATFL talar avulsion fracture associated with medial malleolar fracture was presented to the emergency department. Fixation of the fragment resulted with excellent functional outcome without a residual instability. Besides more common injury patterns such as mid-substance ATFL rupture and ATFL fibular avulsion fracture, talar avulsion fracture pattern should also be kept in mind in a patient presented with lateral ankle sprain. When a fragment is seen on the ankle radiographs at the tip of fibula, previously described special oblique views should be performed to reveal the correct origin of the fragment.

Transepiphyseal (Type VII) Ankle Fracture Versus Os Subfibulare in Pediatric Ankle Injuries

BACKGROUND

Pediatric ankle injuries are common, giving rise to ∼17% of all physeal injuries. An os subfibulare in a child with an ankle sprain may be confused with a type VII transepiphyseal fracture. Here, we evaluate the clinical and radiographic features of type VII transepiphyseal fractures to those of os subfibulare presenting with acute ankle trauma with the hypothesis that radiographs are necessary for final diagnosis and neither clinical history nor examination would be diagnostic.

METHODS

We performed an internal review board-approved, retrospective chart review of patients identified with a traumatic os subfibulare or type VII ankle fracture over an 18-month period. Charts were reviewed for demographics, mechanism, and clinical findings on initial presentation. Radiographic measurements of the distal fibular fragment as well as epiphysis were made on presenting ankle series radiographs.

RESULTS

A total of 23 patients were identified. Eleven patients had a traumatic type VII ankle fracture and 12 had trauma associated with an os subfibulare on initial radiographs. The history and clinical presentations were similar and were nondiagnostic. The ratio of the width of the fibula at its largest point on the anterior posterior view to the width of the fibular fragment was significantly larger in the type VII ankle fractures (P=0.05). All os subfibulare were located within the inferior third of the epiphysis, whereas all type VII fractures were either at the equator or within the middle third of the fibular epiphysis.

CONCLUSIONS

Radiographs, not clinical presentation, can differentiate an os subfibulare from a type VII transepiphyseal fracture. Children with type VII fractures have a long, irregular fracture line within the middle third of the distal fibular epiphysis. Those with an ankle sprain and os subfibulare have a smooth-edged ossicle of relatively short length located within the inferior pole of the epiphysis. Furthermore, the radiographic width of the fragment in the type VII fractures is significantly larger in width than the os subfibulare.

LEVEL OF EVIDENCE

Level II.

Posttraumatic Subfibular Ossicle Formation in Children: Experience in a Single Primary Care Unit

BACKGROUND

Although subfibular ossicles have been linked to various clinical problems, whether its origin is congenital or traumatic remains unclear. The objectives of this study were to determine the incidence of subfibular ossicle formation after ankle inversion in children.

METHODS

Among 896 pediatric patients who visited a single primary care unit after foot and ankle trauma, 593 patients sustaining ankle inversion injury were included in this study. For each pediatric patient, physical examination and radiographic examination were performed. The incidence of subfibular ossicle was evaluated based on initial radiographic examination. To analyze the incidence of unprecedented subfibular ossicle formation after ankle inversion injury, radiographs of 188 patients who were followed up for >6 months were evaluated according to the grade of initial injury.

RESULTS

At initial visit, 1.0% of examined ankles (12 from 1186 ankles) showed well-corticated subfibular ossicle not related to initial injuries. Overall incidence of subfibular ossicle at final follow-up after ankle inversion injury was 39.4% (74/188). Incidence of subfibular ossicle at final follow-up was associated with initial injury grade. As for the morphology of ossicle, 93.2% (55/59) of cases with wafer bone fragment at the time of initial injury became oval or round-shaped subfibular ossicle at final radiograph.

CONCLUSIONS

The chance of ossicle formation after ankle inversion injury was substantially high in pediatric population. On the basis of the findings of our study, we carefully suggest that majority, if not all, of subfibular ossicles would be posttraumatic in pediatric period.

LEVEL OF EVIDENCE

Level IV-case series.

Surgical Treatment of Subfibular Ossicle in Children: A Retrospective Study of 36 Patients with Functional Instability

BACKGROUNDS

To evaluate the surgical management of a symptomatic subfibular ossicle after severe ankle sprain with functional instability and pain sequelae in children.

METHODS

We analyzed 36 patients complaining of functional instability without laxity, 1 year after an ankle inversion trauma associated with the observation of a subfibular ossicle. We systematically suggested the open excision of the residual ossicles, followed by 6 weeks of immobilization and proprioceptive physiotherapy. Seventeen of them, constituting the "resection" group accepted this surgical approach. The remaining 19 patients, the "control" group, received only rehabilitative care. The American Orthopaedic Foot and Ankle Society ankle pain and function score was evaluated in both groups.

RESULTS

The mean latest follow-up was 4 years and 4 months (range, 1 y 8 mo to 14 y 7 mo). A significant improvement of the American Orthopaedic Foot and Ankle Society score was observed and was significantly higher in the resection group with a mean gain of 31 points (SD=31.8), versus 7 points (SD=7) in the control group (P<0.001).

CONCLUSIONS

We conclude that in the absence of objective laxity, excision of the os subfibulare appears as a simple and effective technique in the treatment of posttraumatic functional instability and ankle pain.

LEVEL OF EVIDENCE

Level IV-retrospective case-control study.

Accessory Ossicles of the Foot and Ankle: Disorders and a Review of the Literature

Accessory ossicles of the foot and ankle are normal variants of bone development that usually remain asymptomatic. However, they may be involved in various disorders and become a source of pain such as in fractures, dislocations, degenerative changes, osteonecrosis, osteoarthritis, osteochondral lesions, avascular necrosis, and irritation or impingement of adjacent soft tissues. Hence, during the assessment of the situations above, knowledge about these little-known ossicles could be very important to reach the correct diagnosis. Recent studies in the literature have mostly focused on the most frequent 9-12 accessory bones. In this review, 24 types of accessory ossicle are described. These ossicles are accessory navicular bone, os peroneum, os trigonum, os intermetatarseum, os vesalianum. os subfibulare, os subtibiale, os calcaneus secundarius, os calcanei accessorium, os supratalare, os sustentaculi, os talotibiale, os tali accessorium, talus secundarius, os subcalcis, os cuboideum secundarium, os supranaviculare, os infranaviculare, os paracuneiforme, os intercuneiforme, os cuneometatarsale I tibiale, os cuneometatarsale plantare, os cuneo–I metatarsale-II dorsale, and os aponeurosis plantaris. The clinical importance of these bones should be known thoroughly to reduce unnecessary orthopedic consultations and misdiagnosis. This article describes the clinical importance of the accessory ossicles and their possible pathological conditions. Understanding the possible disorders of the accessory ossicles of the foot and ankle can provide a more accurate diagnostic process.

Comparison of the Modified Broström Procedure for Chronic Lateral Ankle Instability With and Without Subfibular Ossicle

BACKGROUND

Subfibular ossicles are frequently found in patients with chronic lateral ankle instability (CLAI). However, there is a lack of consensus about the optimal surgical treatment for CLAI with subfibular ossicle.

PURPOSE

To evaluate the clinical and radiographic outcomes of the modified Broström procedure with subfibular ossicle excision compared with the same procedure for CLAI without subfibular ossicle.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Ninety-six patients (96 ankles) treated with the modified Broström procedure using bone tunnel and suture anchor techniques for CLAI constituted the study cohort. The 96 ankles were divided into 2 groups with and without subfibular ossicles. The ossicle group (42 ankles) and nonossicle group (54 ankles) consisted of patients with a mean age of 26.6 and 30.3 years, respectively, at the time of surgery with a mean follow-up duration of 63.7 and 62.1 months, respectively. Subfibular ossicles were excised in the ossicle group.

RESULTS

Mean Karlsson scores improved from 55.2 to 95.3 in the ossicle group and from 56.4 to 94.8 in the nonossicle group at final follow-up. Mean American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot scores also improved from 63.3 to 95.9 in the ossicle group and from 62.8 to 95.1 in the nonossicle group at final follow-up. Mean talar tilt angles were 14.0° in the ossicle group and 12.2° in the nonossicle group preoperatively and 7.6° and 6.8° at the final follow-up, respectively. Mean anterior talar translations in the ossicle group and nonossicle groups improved from 9.3 and 9.4 mm preoperatively to 5.8 and 5.7 mm at final follow-up, respectively. No significant differences were found between the 2 groups in terms of Karlsson score, AOFAS score, talar tilt angle, and anterior talar translation at final follow-up (P > .05).

CONCLUSION

The modified Broström procedure with subfibular ossicle excision provided similarly good clinical and radiographic outcomes compared with the same procedure without subfibular ossicle excision. Accordingly, the study results suggest that these procedures appear to be effective and reliable method for the treatment of CLAI with subfibular ossicle.

Intraarticular Entrapment of Os Subfibulare Following a Severe Inversion Injury of the Ankle: A Case Report

INTRODUCTION

Anterior Talofibular Ligament (ATFL) rupture is the most commonly injured anatomic structure in lateral ankle sprain. In some cases, ATFL avulsion fracture from the lateral malleolus may occur instead of purely ligamentous injuries. The ATFL avulsion fracture is detected as a small ossicle at the tip of lateral malleolus on direct radiographs, which is called os subfibulare in chronic cases.

CASE PRESENTATION

Severe displacement of this ossicle to the tibiotalar joint space is an extremely rare injury. Herein, a case of intra-articular entrapment of os subfibulare following a severe inversion injury of the ankle, which caused a diagnostic challenge was presented.

CONCLUSIONS

To the best of our knowledge, this is the first case of entrapment of os subfibulare in the talotibial joint space. Fixation of the os subfibulare to lateral malleolus resulted in union and excellent functional results.

Operative Indications and Treatment for Chronic Symptomatic Os Subfibulare in Children

Introduction

When used for strict surgical indications, operative management of chronic symptomatic os subfibulare in children involving fragment excision and ligament repair can significantly improve visual analog scale pain scores and result in high Foot and Ankle Outcome Scores.

Step 1 Indications and Preoperative Planning

Operative indications are chronic pain at the distal part of the fibula, symptoms of instability at the anterior talofibular ligament and/or calcaneofibular ligament, and a radiographic finding of an os fibulare.

Step 2 Ossicle Excision

Perform an approach to the lateral malleolus and excise the fragment while preserving the anterior talofibular ligament and calcaneofibular ligament.

Step 3 Ankle Examination

Examine the ankle for loose bodies or other associated damage.

Step 4 Preparation for Ligament Repair

Repair the anterior talofibular ligament and calcaneofibular ligament to the debrided distal part of the fibula.

Step 5 Preparation for Modified Broström Procedure

Imbricate the lateral capsule to secondarily reconstruct and reinforce the ligaments, adding to the strength of the repair.

Step 6 Repair Reconstruction and Closure

Reduce the ankle joint and tie down the sutures.

Step 7 Casting

Patients wear a cast and remain non-weight-bearing for six weeks postoperatively.

Step 8 Postoperative Protocol

Patients advance to full weight-bearing in a CAM boot and start physical therapy at six weeks.

Results

We performed a retrospective case study of the first twenty-three patients treated with our procedure for symptomatic os subfibulare.IndicationsContraindicationsPitfalls & Challenges.

Chronic symptomatic os subfibulare in children

BACKGROUND

Some children have persistent pain and instability following inversion injuries of the ankle. Radiographs may reveal a small osseous fragment distal to the lateral malleolus, suggesting an avulsion injury of the anterior talofibular ligament and/or calcaneofibular ligament. The avulsion injury may involve an os subfibulare, causing ligamentous laxity and chronic pain resulting from nonunion. This situation must be differentiated from an asymptomatic os subfibulare, which is a normal anatomic variant in 1% of children. The purpose of this study was to evaluate the intraoperative findings and long-term outcomes of patients treated operatively for symptomatic avulsion injuries or a symptomatic os subfibulare.

METHODS

Twenty-three patients presented with chronic ankle pain and instability, tenderness anterior and distal to the lateral malleolus, and imaging studies (magnetic resonance imaging and/or stress radiographs) suspicious for avulsion injury of the anterior talofibular ligament and/or calcaneofibular ligament. After unsuccessful nonoperative treatment, all patients underwent excision of the osseous fragments, anatomic reconstruction of the anterior talofibular ligament with use of drill holes through the lateral malleolus, and a modified Broström procedure.

RESULTS

The mean age of the patients was 10.4 years (range, eight to thirteen years) at the time of injury and 13.6 years (range, eight to seventeen years) at the time of surgery, representing a mean delay in diagnosis and treatment of 3.2 years. At a mean follow-up of 4.5 years (range, 2.1 to 13.2 years), the mean Foot and Ankle Outcome Score was 91.4 (range, 87 to 98) out of 100, with all but one patient returning to the preinjury recreational level. Only one patient had a long-term complication.

CONCLUSIONS

In children with chronic pain and instability associated with an os subfibulare, surgical excision of the os subfibulare combined with reconstruction of the anterior talofibular ligament and a modified Broström procedure was effective in restoring ankle stability, eliminating pain, and permitting return to the preinjury functional level.

The effect of ossicle resection in the lateral ligament repair for treatment of chronic lateral ankle instability

BACKGROUND

The management of an ossicle or avulsion fragment of the fibular tip in chronic lateral ankle instability is an open question. Some authors maintain the necessity of osteosynthesis for reconstruction of the lateral ligamentous structure if the fragment is large. We hypothesized that the modified Broström procedure with resection of the ossicle would result in good outcomes compared to that of the same procedure for chronic lateral instability patients without ossicle.

METHODS

Between December 2004 and December 2010, 102 patients underwent the modified Broström procedure for chronic lateral instability. Of these, 82 patients (86 ankles) were available for this study. Forty ankles had ossicles at the fibular tip (group O), 46 had no ossicle (group N). The average follow-up period was 33 months in group O and 37 months in group N. Irrespective of size, if there were ossicles we resected all fragments and performed the modified Broström procedure. To analyze the surgical outcome, American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot pain and function scales and Karlsson scores were compared between the 2 groups preoperatively and postoperatively.

RESULTS

Preoperative scores in the 2 groups showed no significant difference, except for AOFAS pain score. There was no significant difference in postoperative AOFAS pain and function score between the groups. Postoperative Karlsson score was significantly higher in group O than in group N (P = .001). Group O was divided into 2 subgroups by the largest diameter of the ossicle (< 10 mm and ≥ 10 mm); there was no significant difference in surgical outcomes.

CONCLUSIONS

In the treatment of chronic lateral instability of ankle, if there are ossicles on the fibular tip, osteosynthesis of the ossicles may not be necessary, even if the size is considerable. Modified Broström procedure after resection of the ossicle was successful.

LEVEL OF EVIDENCE

Level III, retrospective case series.

True submalleolar accessory ossicles causing impingement of the ankle

True ossicle in the distal portion of the malleolus is only sporadically observed, and related disease has been rarely reported. We present two cases of atypical ankle impingement resulting from an ankle sprain. Plain radiographs revealed true submalleolar ossicles. Conservative treatment failed, and arthroscopy was performed. Instability of the ossicle and surrounding fibrotic soft tissue was evident; a gap between the ossicle and the tip of the malleolus seen during plantar flexion of the ankle disappeared in dorsal flexion, resulting in compression of the surrounding soft tissue. Arthroscopic excision of the accessory ossicle relieved the symptoms and enabled both patients to return to full preinjury activities.

Removal of an unusual pedal ossicle in an elite distance runner: a case report

A 24-year-old female national champion 5000-meter runner presented with an approximately 1-year duration of left foot pain localized to the medial arch. She had received multiple diagnoses and had undergone many different treatments, all of which had failed to relieve her symptoms. Careful review of her radiographic studies revealed an unusual ossicle in the region of her symptoms. Surgical excision of the not previously described ossicle localized within the posterior tibial tendon distal to the navicular adjacent to the first cuneiform resulted in complete resolution of the patient's longstanding symptoms, and allowed her to return to competition at an elite level.

LEVEL OF CLINICAL EVIDENCE

4.

Assessment of acute ankle sprain with os subfibularein children

Children commonly present with acute inversion injuries of the ankle. Radiographs occasionally show small fragments under the tip of the lateral malleolus. The purpose of our study was to clarify their origin. A prospective standardized clinical examination and a magnetic resonance imaging were carried out. Among the 116 included patients, seven of them showed an os subfibulare. They presented more pains on the lateral ankle area than the other children. We found also more injuries on the anterior talofibular ligament. The os subfibulare could be secondary to an accessory ossification but the lateral area of the ankle would be likely to be injured.