Anatomic Characteristics of Tissues Attached to the Fifth Metatarsal Bone

Anatomical variations of peroneus tertius and its clinical implications: case report with systematic literature review

PURPOSE

Peroneus tertius (PT) or Fibularis tertius, a muscle of the anterior compartment of the leg is very distinctive to the Homo sapiens. This is because of the evolutionary acquisition of bipedal gait along with the eversion of the foot, which are unique to humans. It is considered as the fifth tendon of the extensor digitorum longus. Variations in the attachments of PT can cause stress fractures like the Jones fracture. PT has been extensively used in tendoplasty, tendon transfer and resection of the foot. The study aims to transpose the knowledge in variations of the morphology of PT from bench to bedside.

METHODS

Routine dissection of a 64-year-old male cadaver revealed bilateral variations in the insertion of PT. This was documented photographically. The findings prompted a systematic literature review on the morphological variations of PT. An exhaustive search was undertaken through PubMed and Google Scholar databases to identify the published literature related to variations in the morphology of PT. Related anatomical studies of the variations in peroneus tertius were identified and a review of the literature was performed.

RESULTS

Variations in the insertion of PT were observed bilaterally in the cadaver dissected by us. Statistical analysis revealed the absence of PT in 7.03% of lower limbs. 10% of studies showed accessory and duplicated PT each. Out of 20 articles reviewed, 51 lower limbs showed variation in origin, 230 lower limbs showed variations in insertion and 161 lower limbs showed other variations.

CONCLUSION

PT muscle flap and tendon grafts are used in correcting the laxity of the ankle joint and foot drop. Absence of PT plays a crucial role in altering the mechanics of stress fractures of the 5th metatarsal. Thus, knowledge of the morphology of PT is crucial for plastic surgeons and orthopedic surgeons.

Peroneus tertius revisited: The morphological variability of the bifurcated peroneus tertius insertion - An anatomical study

BACKGROUND

The peroneus tertius muscle (PT) is one of the extensor muscles of the lower leg, often described as a variable separation from the extensor digitorum longus muscle (EDL). According to literature it has six different types of insertion, one of them (Olewnik Type IV) having two tendons inserting to the fifth metatarsal bone (FMTB). Morphometric data about this type of insertion is sparse, especially the relation between the two tendons, albeit the PT is suspected to contribute to stress fractures of the FMTB. Therefore, we examined this type of insertion to give detailed information on the tendons, the insertion points and the respective relations.

METHODS

We examined 27 lower extremities of embalmed human bodies (12 paired, 15 single sided; 12 right and 15 left) with a distinguishable PT with two tendons inserting to the FMTB (Olewnik IV). The specimens were obtained of an undergrad dissection program, which in turn obtained them from a body donation program. After dissection of the PT and photo documentation in situ, resection and measurement of morphological properties of the tendons were performed with the PT attached to the fifth metatarsal bone.

RESULTS

Results of the respective measurements yielded a wide range of variation, especially in the insertion point of the anterior tendon on the fifth metatarsal and the relation between the two tendons, but with no significant difference between sides or sex, except for the length of the posterior tendon between sex. The distance between the base of the FMTB and posterior tendon varies from 0 to 9 mm, with one outlier at 24 mm (mean = 3.9 ± 4.8 mm), the distance between the insertions from 0 to 15 mm (mean = 4.7 ± 4.7 mm), resulting in how far of the FMTB the anterior tendon reaches varying from 17 to 60 mm (mean = 39.6 ± 11.5 mm) or 22-98% (mean = 64 ± 19%).

CONCLUSION

Our findings give a detailed overview of the morphological features the PTT can have, when attached with two tendons to the FMTB. Especially the varying relationship between those two insertions and varying point of the anterior insertion are of interest, as they might support its complex role in the occurrence of fractures of the fifth metatarsal by providing different amounts of torsional stress and its tendons can be used as tendon-grafts.

Fifth Distal Phalanx Avulsion Fracture in a High-Level Marathon Runner

Fifth metatarsal fractures are common foot injuries that involve the long bone on the outer side of the foot, and avulsion fractures involving the short bone and the fifth distal phalanx of the foot have never been reported. A 25-year-old female marathon runner sustained an avulsion fracture of the distal lateral phalanges of the fifth metatarsal. The patient's high functional demands necessitated a conservative approach to minimize complications and facilitate efficient fracture healing. The patient underwent a comprehensive chiropractic rehabilitation program that focused on progressive weight-bearing exercises, range-of-motion activities, strengthening exercises, instrument-assisted soft tissue mobilization (IASTM), therapeutic ultrasound, and laser therapy to stimulate the speed of healing. The patient's progression was closely monitored throughout the rehabilitation process. Because of the nonoperative management and chiropractic rehabilitation, the patient successfully returned to her running activities within a six-week duration. This case demonstrates the effectiveness of nonoperative management and chiropractic rehabilitation in promoting the healing of avulsion fractures of the fifth metatarsal in high-level athletes. This conservative approach can facilitate a safe and efficient return to running activities while minimizing complications and reinjury risks.

Classification of avulsion fractures of the fifth metatarsal base using three-dimensional CT mapping and anatomical assessment: a retrospective case series study

Background

To clarify the injury mechanism of the avulsion fracture of the fifth metatarsal combining 3-dimensional (3D) fracture mapping with anatomical measurements.

Methods

Two hundred twenty-two patients with the avulsion fractures of the fifth metatarsal base, who were admitted to our hospital from August 2015 to August 2020. The computed tomography (CT) scans were used to generate the 3-D images of all mapped fracture lines for the avulsion fractures of the fifth metatarsal base were compiled in an overall 3D image. The fifth metatarsal base of 8 unpaired lower limbs of adult Asian frozen cadaveric specimens were also dissected to observe and measure the specific locations of the attachment points of the peroneus brevis, lateral band of the plantar fascia, and peroneus tertius to the fifth metatarsal base.

Results

Based on the type of fracture line produced and the specific locations of the attachment points of the tendons or fascia, the avulsion fractures of the fifth metatarsal base can be classified into three types: type I predominantly involves the action of the lateral band of the plantar fascia; type II predominantly involves the action of the peroneus brevis; type IIIA involves the joint action of the peroneus brevis and lateral band of the plantar fascia with one fracture line, and type IIIB involves the joint action of the peroneus brevis and lateral band of the plantar fascia with two fracture lines.

Conclusion

The lateral band of the plantar fascia and peroneus brevis play a major role, either separately or together, in avulsion fractures of the fifth metatarsal base. With this knowledge, we propose a novel classification based on the injury mechanism, which can serve as a reference for clinical treatment and diagnosis.

Level of evidence

Level III, retrospective case series.

Fractures of the Base of the Fifth Metatarsal Bone: A Critical Analysis Review

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Fractures of the proximal fifth metatarsal (PFMT) are one of the most common foot injuries, accounting for 61% to 78% of all foot fractures, but full consensus on their classification, diagnosis, and treatment has not yet been reached.

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The most commonly accepted classification is that of Lawrence and Botte, who divided the location of PFMT fractures into 3 zones with respect to their healing potential.

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Avulsion fractures of the tuberosity of the base (zone 1) generally heal well, and nonoperative treatment is commonly recommended.

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Internal fixation may be considered for displaced fractures that extend into the fourth-fifth intermetatarsal joint (zone 2) as well as for nondisplaced fractures in athletes or high-demand patients, with the aims of reducing the healing time and expediting return to sport or work.

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Stress fractures of the proximal diaphysis (zone 3) are preferably treated operatively, particularly in the presence of signs of delayed union. With nonoperative treatment, supportive measures such as ultrasonography or external/extracorporeal shockwave therapy have been demonstrated to have limited potential for the enhancement of fracture-healing.