Appropriate Area for Operative Procedures Near Tibialis Anterior Tendon Insertion: A Cadaveric Study

Abstract

Background:

The tibialis anterior tendon has its insertion sites on both the medial and plantar surfaces of the medial cuneiform and the base of the first metatarsal. Operative procedures near those areas, especially at the first metatarsocuneiform joint, may disturb tendon insertions and cause irritation or functional impairment of the tendon.

Methods:

Tibialis anterior tendons and their insertion sites were dissected and examined from 46 cadaveric feet (19 female and 27 male cadavers, aged between 33 and 86 years, with a mean of 68.5 ± 14.3 years). The greatest lengths and widths of the tendon attachments on the bony surface of the medial cuneiform and base of the first metatarsal, on both the medial and plantar surfaces, were measured and analyzed. The measurement reliability was evaluated by using the intraclass correlation coefficient.

Results:

Most of the tibialis anterior tendon insertions were found to be longer at the medial cuneiform than at the base of the first metatarsal (mean, 8.3 and 5.4 mm; P < .001), but the widths were almost similar (mean, 11.0 and 10.4 mm; P = .079). When focusing on each bone, the widths of the tendon attachments on the medial and plantar surfaces of the medial cuneiform were equivalent (mean, 5.4 and 5.6 mm; P = .584). At the base of the first metatarsal, the tendon attachment on the plantar surface was found to be wider than on the medial surface (mean, 7.0 and 3.4 mm; P < .001).

Conclusion:

The widths of the tibialis anterior tendon insertions on the medial and plantar surfaces of the medial cuneiform were equal, as were the total widths of insertions on the medial cuneiform and on the base of the first metatarsal. However, the width of insertions on the medial surface of the first metatarsal was significantly smaller than on the plantar surface, and the total length of insertions at the medial cuneiform was longer than at the first metatarsal.

Clinical Relevance:

This study provides information about characteristics of the tibialis anterior tendon insertions, particularly details of the dimensions on each surface of the bones. This knowledge enables surgeons to minimize the risk of irritation or tendon injuries during operations near the base of the first metatarsal and medial cuneiform area.

Keywords

tibialis anterior tendon medial cuneiform first metatarsal cadaveric study foot surgery

The tibialis anterior muscle plays a major role in foot dorsiflexion,²⁰ with approximately 80% of the total force being provided by this muscle.¹ The remaining function is foot inversion by rotating the dorsal surface of the first ray outwardly.⁹ The origin of the muscle is from the lateral tibial condyle and from the proximal half to the proximal two-thirds of the tibia.¹⁴ The muscle descends vertically and becomes a musculotendinous junction at the anterior surface of the lower one-third of the leg. The tibialis anterior tendon passes through the medial compartment of the superior and inferior extensor retinacula and runs toward the medial border of the foot.⁹ Brenner identified 2 bundles of tibialis anterior tendon fibers at the insertion site, the distal-superficial and the proximal-deep fibers, which are attached to both the medial and plantar surfaces of the medial cuneiform and to the base of the first metatarsal.⁴

Tibialis anterior tendon ruptures are rare^1,6,8,22 but are claimed to be the third most common tendon rupture in the lower extremity, after Achilles and patellar tendon ruptures.^3,5,7 Impairment of the tendon may lead to persistent foot drop, claw toes, and progressive flattening of the arch.⁵ Patients may suffer from gait problems, especially a slapping of the foot because of insufficient foot dorsiflexion and inversion.^1,14 Generally, the main causes of the tendon ruptures are open injuries with direct trauma, closed injuries with indirect trauma, and spontaneous ruptures.¹ Nevertheless, operative procedures near the tibialis anterior tendon insertion, especially around the first metatarsocuneiform joint, face a potential risk of iatrogenic tendon injury and rupture.¹¹ The purpose of this study was to evaluate and compare the characteristics of the insertion sites of the tibialis anterior tendon at both the medial cuneiform and the base of the first metatarsal, both on the medial and the plantar aspects, in a cadaveric model. Understanding the characteristics of the tendon attachments is important prior to performing operative procedures around this area to minimize the risk of further tendon injuries.

Materials and Methods

Forty-six cadaveric legs and feet were included in this study, and the protocol was approved by the institutional review board. Nineteen female (41.3%) and 27 male (58.7%) cadavers were included, with ages ranging from 33 to 86 years (mean, 68.5 ± 14.3). Twenty-five of the evaluated feet were right feet (54.3%), and the remaining 21 were left feet (45.7%). The height of the cadaveric study subjects ranged from 135 to 182 cm (mean, 159.5 ± 10.8). The demographic data are shown in Table 1.

Table 1.

Cadaveric Study Subject Demographics.

Demographic Data		P Value^a
Age, y, mean ± SD	68.5 ± 14.3
Height, cm, mean ± SD	159.5 ± 10.8
Sex, n (%)
Female	19 (41.3)	.302
Male	27 (58.7)
Side, n (%)
Left	21 (45.7)	.658
Right	25 (54.3)

P < .05 indicates statistical significance.

A longitudinal skin incision was made at the anterior part of the distal one-third of the leg, and then the tibialis anterior tendon was identified. The skin incision was extended continually along the tendon and ended at its insertion sites at the medial cuneiform and the base of the first metatarsal (Figure 1). The soft tissue around the tendon and the first metatarsocuneiform joint was dissected and removed. The tendon was then reflected and reattached at its insertion site, and the boundary of the tendon attachment on the bony surface was then identified. The demographic data (gender, age, side, and height) of the cadavers were collected, and the greatest length and width of the tendon attachments at the medial cuneiform and the base of the first metatarsal, both on the medial and the plantar aspects of the bone, were measured. The medial and plantar surfaces were divided by a horizontal anatomical ridge, which was clearly seen on both bones (Figure 2). The data collection and measurements were performed on all cadavers by one investigator. The data were presented as mean ± standard deviation (SD) for continuous variables and as percentage (%) for categorical variables. A descriptive analysis was performed and displayed for the demographic data and for the average length and width of the tendon attachment. The comparison of the sizes of the tendon attachments at the medial cuneiform and the base of the first metatarsal, as well as on the bony aspect of each bone (the medial and plantar surfaces), was performed with a paired-samples t test, and a P value < .05 was regarded as statistically significant. We categorized the cadaveric study subjects into groups based on the size of the tendon attachments, for which we defined the different margins of measurement as 1 mm. Two sets of measurements were obtained by an investigator and an assistant over an interval of 4 weeks. The reliability of the measurements was assessed by examining the intraobserver and interobserver reliabilities with the intraclass correlation coefficient. The data were analyzed using SPSS Statistics version 18 (SPSS, Inc, Chicago, IL).

Results

The length and width of the tibialis anterior tendon attachments on the surface of the medial cuneiform and the base of the first metatarsal bone are described in Figure 3. The average length of the tendon attachment at the medial cuneiform was significantly greater than at the base of the first metatarsal (medial cuneiform, 8.3 ± 1.5 mm; range, 5–12; and base of the first metatarsal, 5.4 ± 1.5 mm; range, 3–10; P < .001; (Table 2). The length of the tendon attachment was longer at the medial cuneiform in 36 cadavers (78.3%) but longer at the base of the first metatarsal in 2 cadavers (4.3%); however, the lengths to the 2 bones were similar in the case of 8 cadavers (17.4%; Table 3). The average width of the tendon insertion at the medial cuneiform was nearly equivalent to the base of the first metatarsal (medial cuneiform, 11.0 ± 2 mm; range, 7.5–17; and base of the first metatarsal, 10.4 ± 1.9 mm; range, 6–14; P = .079; Table 2). The widths of the tendon attachments at the 2 bones were similar for 26 cadavers (56.5%); however, they were larger at the medial cuneiform in 11 cadavers (23.9%) but larger at the base of the first metatarsal in the case of 9 cadavers (19.6%; Table 3).

Table 2.

Characteristics of Tibialis Anterior Tendon Insertion.

Parameter	Size of Tendon Insertion at Medial Cuneiform, mm^a	Size of Tendon Insertion at Base of First Metatarsal, mm^a	Difference, mm^a	P Value^b
Total length	8.3 ± 1.5	5.4 ± 1.5	3.0 ± 2.0	<.001
Total width	11.0 ± 2.0	10.4 ± 1.9	0.6 ± 2.1	.079
Width on medial surface	5.4 ± 1.2	3.4 ± 1.0	2.0 ± 1.6	<.001
Width on plantar surface	5.6 ± 1.5	7.0 ± 1.7	1.5 ± 1.5	<.001
Parameter	Size of Tendon Insertion at Medial Surface, mm^a	Size of Tendon Insertion at Plantar Surface, mm^a	Difference, mm^a	P Value^b
Width at medial cuneiform	5.4 ± 1.2	5.6 ± 1.5	0.2 ± 1.9	.584
Width at base of first metatarsal	3.4 ± 1.0	7.0 ± 1.7	3.6 ± 2.1	<.001

Data are presented as mean ± standard deviation.

P value <.05 indicates statistical significance.

Table 3.

Number of Cadaveric Study Subjects, Categorized and Compared by Size of Tibialis Anterior Tendon Insertion.

Parameter	Insertion Area A	Insertion Area B	Insertion Area A > B, n (%)^a	Insertion Area A = B, n (%)^a	Insertion Area A < B, n (%)^a
Total length	Medial cuneiform	Base of first metatarsal	36 (78.3)	8 (17.4)	2 (4.3)
Total width	Medial cuneiform	Base of first metatarsal	11 (23.9)	26 (56.5)	9 (19.6)
Width at medial cuneiform	Medial surface	Plantar surface	11 (23.9)	26 (56.5)	9 (19.6)
Width at base of first metatarsal	Medial surface	Plantar surface	1 (2.2)	4 (8.7)	41 (89.1)
Width on medial surface	Medial cuneiform	Base of first metatarsal	26 (56.5)	20 (43.5)	0 (0)
Width on plantar surface	Medial cuneiform	Base of first metatarsal	1 (2.2)	17 (36.9)	28 (60.9)

The different margin of measurement is 1 mm.

When focusing on each bone, the average widths of the tendon attachments on both the plantar and the medial surfaces of the medial cuneiform were comparable (plantar surface, 5.6 ± 1.5 mm; range, 3–9; and medial surface, 5.4 ± 1.2 mm; range, 3.5–9; P = .584; Table 2). There were 26 cadavers (26.5%) with a similarly-sized tendon attachment on both the plantar and the medial surfaces of the medial cuneiform. In 11 cadavers (23.9%), the attachment was larger on the medial surface, whereas for another 9 cadavers (19.6%), it was larger on the plantar surface (Table 3). In addition, the average width of the tendon insertion on the plantar surface of the base of the first metatarsal was larger than on the medial surface (plantar surface, 7.0 ± 1.7 mm; range, 2–10; and medial surface, 3.4 ± 1 mm; range: 1–6; P < .001; Table 2). The width of the tendon attachment was found to be larger on the plantar surface of the base of the first metatarsal in 41 cadavers (89.1%), on the medial surface in only 1 cadaver (2.2%), but similar on both surfaces in the case of 4 cadavers (8.7%; Table 3).

When comparing each surface, the width of the tendon attachment on the medial surface of the medial cuneiform tended to be significantly larger than that at the base of the first metatarsal (P < .001; Table 2). Twenty-six cases (56.5%) were larger at the medial cuneiform, whereas 20 (43.5%) were equal in width on both the medial cuneiform and the base of the first metatarsal. However, no specimen had a larger insertion at the medial surface of the base of the first metatarsal than at the medial cuneiform (Table 3). In contrast to the plantar surface, the width of the tendon attachment at the base of the first metatarsal was significantly larger than at the medial cuneiform (P < .001; Table 2). There were 28 cadavers (60.9%) with a larger tendon attachment on the plantar surface of the base of the first metatarsal, while there were 17 cadavers (36.9%) with a similar width of tendon attachment at the medial cuneiform and the base of the first metatarsal. Only 1 cadaver (2.2%) had a larger tendon attachment on the plantar surface of the medial cuneiform (Table 3). The intraclass correlation coefficients for the intraobserver and interobserver reliability were 0.951 and 0.920, respectively.

Discussion

This study was conducted to discover the appropriate area for operative approaches around the first metatarsocuneiform joint without any—or with the least—damage or irritation to the tibialis anterior tendon, which attaches near the joint. The authors measured the greatest length and width of the tendon attachments at the medial cuneiform and the base of the first metatarsal, both on the medial and the plantar surfaces of the bone. The least bony area of the tendon attachments might be the safest zone to perform an operative approach. In 1963, Musial¹⁶ classified the tibialis anterior tendon insertion into 4 subtypes: type 1, the insertion was equally spread on both the medial cuneiform and the first metatarsal; type 2, which is the most common type, a wide insertion was found at the medial cuneiform, and a narrow insertion was found at the first metatarsal; type 3, a principal insertion was inserted into the medial cuneiform, and some accessory slips were inserted into the first metatarsal; and type 4, a wide insertion was attached to the first metatarsal, and a narrow insertion was attached to the medial cuneiform bone. Arthornthurasook and Gaew Im² also reported variations of the tibialis anterior tendon insertion in 3 styles. The most common insertion was a division of the tendon into 2 bands at the first cuneiform and at the base of the first metatarasal and of equal width (56.8%). Another was a larger slip inserted into the first cuneiform, with a small slip inserted into the base of the first metatarsal (27.3%), while the least-common type was a single slip inserted into the first cuneiform only (15.9%). Furthermore, Brenner⁴ described the 2 fibers at the terminal part of the tibialis anterior tendon: the distal-superficial fiber and the proximal-deep fiber on the medial and plantar surfaces of both the medial cuneiform and the base of the first metatarsal bone. In line with research by Arthornthurasook and Gaew Im,² our study found that in most cases (56.5%), the width of the tibialis anterior tendon insertion was the same at the medial cuneiform as at the base of the first metatarsal. In another 23.9% of cadavers, there was a larger insertion at the medial cuneiform, with a smaller area of insertion at the base of the first metatarsal. However, our study did not find any cadavers with an insertion only at the medial cuneiform. Compared with previous literature, our study provided more details of the dimensions of the tibialis anterior tendon insertions, particularly the characteristics of the medial and plantar surfaces of both the medial cuneiform and the base of the first metatarsal.

The important function of the tibialis anterior is foot dorsiflexion, which helps control the body’s balance during the gait cycle.²⁰ When walking or running, it also supports the medial longitudinal arch of the foot during toe-off.⁹ Tibialis anterior insufficiency may cause functional deficiencies and lead to slower walking with less efficiency.^15,20 True ruptured tendons are mostly related to trauma, sport injuries, or degenerative changes, and the mechanism of injury is a combination of sudden plantarflexion and eversion of a dorsiflexed ankle.^6,8,21 Nevertheless, there are many operative procedures that are undertaken near the first metatarsocuneiform joint or the first tarsometatarsal joint that risk possible injury to the tibialis anterior tendon and its insertion. Klos et al¹¹ reported a complication of tibialis anterior tendon rupture in patients undergoing Lapidus arthrodesis. The plantar osteosynthesis in Lapidus arthrodesis was proved to be significantly stiffer and stronger than dorsomedial, medial plate, and intramedullary screw fixation.^10,19 However, plate fixation showed an association with morbidity to the plantar structures, especially the tibialis anterior tendon and the tendon insertion. Plate-related impingement complications lead to tendon irritation, which causes postoperative pain, and plate placement over the tendon insertion may also weaken the tendon.¹⁸ Recent literature has shown that 15.2% of patients who had undergone a first tarsometatarsal arthrodesis needed hardware removal after having postoperative pain and irritation.¹⁷ From this study, instrumentation can be applied either on the medial or plantar aspect of the bones. Nonetheless, if medial instrumentation is used, the operative approach and the hardware should be applied on the base of the first metatarsal rather than the medial cuneiform. Conversely, if plantar instrumentation is used, the operation and the instrument should be applied on the medial cuneiform more than the base of the first metatarsal to minimize injury to the whole tendon footprint. A plantar closing wedge osteotomy of the medial cuneiform (Cotton osteotomy) for treatment of a tibialis posterior tendon dysfunction required a reflection of approximately 20% of the tibialis anterior insertion on the plantar side in order to perform the osteotomy.¹³ A biomechanics study demonstrated potential tendon healing in partial tendon injuries, but the injuries that occurred at the osteotendinous junction, a complex transitional area between the bone and the tendon, was the weakest area and required a long time to heal, which resulted in inferior mechanical properties.^12,23

Although this study had a high intraclass correlation coefficient for intraobserver and interobserver reliability of measurements, one limitation was the determination of the tendon attachment size. In this study, we measured the width and length of the tendon insertions on the bony surfaces. However, this might not have provided the most accurate calculations of the attachment areas because of variations in the sizes and the dimensions of the tendon attachment features on the bony surfaces. Taking photographs of each cadaveric study subject, with the attachment area calculations being performed by a computer program, may establish the need for additional studies. Furthermore, all cadavers had been preserved and kept at room temperature for at least 1 year prior to the start of this study, and tendon shrinkage might have resulted.

In conclusion, our study found that the tibialis anterior tendon of most cadaveric study subjects had a longer attachment at the medial cuneiform, with a similar width of the insertions at both the medial cuneiform and at the base of the first metatarsal. At the medial cuneiform, we found that the sizes of the tendon attachments at the medial and the plantar aspects were identical. However, the size of the tendon attachment at the plantar surface of the base of the first metatarsal was larger than that at the medial surface. When comparing each surface, the attachment at the medial surface of the medial cuneiform was wider than that at the first metatarsal, and the attachment at the plantar surface of the first metatarsal was wider than that at the medial cuneiform. The appropriate area for operative procedures near the tibialis anterior tendon insertion would be the least bony area of the tendon attachments. Understanding these characteristics of the tendon insertions enables surgeons to minimize the risk of tendon injuries during operations near the first metatarsocuneiform joint.

Footnotes

Acknowledgements

The authors gratefully acknowledge Mr. Suthipol Udompunthurak of the Division of Clinical Epidemiology, Department of Health Research and Development, Faculty of Medicine Siriraj Hospital, and Ms. Krabkaew Soparat of the Division of Research, Department of Orthopaedic Surgery, Faculty of Medicine Siriraj Hospital, for their assistance with the statistical analyses. We would like to thank Ms. Waraporn Chalermsuk and Ms. Kawitsara Eumbunnapong of the Division of Educational Technology, Department of Orthopaedic Surgery, Faculty of Medicine Siriraj Hospital, for the artwork, and Mr. David Park for the language review.

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.ICMJE forms for all authors are available online.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

Atthakorn Jarusriwanna, MD,

References

Anagnostakos

Bachelier

Fürst

Kelm

Rupture of the anterior tibial tendon: three clinical cases, anatomical study, and literature review. Foot Ankle Int. 2006;27(5):330-339.

Arthornthurasook

Gaew Im

. Anterior tibial tendon insertion: an anatomical study. J Med Assoc Thai. 1990;73(12):692-696.

Beischer

Beamond

Jowett

O’Sullivan

Distal tendinosis of the tibialis anterior tendon. Foot Ankle Int. 2009;30(11):1053-1059.

Brenner

Insertion of the tendon of the tibialis anterior muscle in feet with and without hallux valgus. Clin Anat. 2002;15(3):217-223.

Burton

Aydogan

Repair of chronic tibialis anterior tendon rupture with a major defect using gracilis allograft. Foot Ankle Spec. 2016;9(4):345-350.

Christman-Skieller

Merz

Tansey

JP.

A systematic review of tibialis anterior tendon rupture treatments and outcomes. Am J Orthop. 2015;44(4):E94-E99.

Cohen

Gordon

DH.

The long-term effects of an untreated tibialis anterior tendon rupture. J Am Podiatr Med Assoc. 1999;89(3):149-152.

Gwynne-Jones

Garneti

Wyatt

Closed tibialis anterior tendon rupture: a case series. Foot Ankle Int. 2009;30(8):758-762.

Ikiz

Üçerler

A previously unreported variation related to the insertion of the tibialis anterior muscle and the superficial fibular (peroneal) nerve. Anat Sci Int. 2005;80(3):172-175.

10.

Klos

Simons

Hajduk

et al . Plantar versus dorsomedial locked plating for Lapidus arthrodesis: a biomechanical comparison. Foot Ankle Int. 2011;32(11):1081-1085.

11.

Klos

Wilde

Lange

et al . Modified Lapidus arthrodesis with plantar plate and compression screw for treatment of hallux valgus with hypermobility of the first ray: a preliminary report. Foot Ankle Surg. 2013;19(4):239-244.

12.

Lin

Cardenas

Soslowsky

LJ.

Biomechanics of tendon injury and repair. J Biomech. 2004;37(6):865-877.

13.

Ling

Ross

Hannon

et al . A plantar closing wedge osteotomy of the medial cuneiform for residual forefoot supination in flatfoot reconstruction. Foot Ankle Int. 2013;34(9):1221-1226.

14.

Mengiardi

Pfirrmann

Vienne

et al . Anterior tibial tendon abnormalities: MR imaging findings. Radiology. 2005;235(3):977-984.

15.

Michels

Van

Bauwhede

Oosterlinck

Thomas

Guillo

Minimally invasive repair of the tibialis anterior tendon using a semitendinosus autograft. Foot Ankle Int. 2014;35(3):264-271.

16.

Musial

WW.

Variations of the terminal insertions of the anterior and posterior tibial muscles in man. Folia Morphologica. 1963;22:237-247.

17.

Peterson

McAlister

Hyer

Thompson

Symptomatic hardware removal after first tarsometatarsal arthrodesis. J Foot Ankle Surg. 2016;55(1):55-59.

18.

Plaass

Claassen

Daniilidis

et al . Placement of plantar plates for Lapidus arthrodesis: anatomical considerations. Foot Ankle Int. 2016;37(4):427-432.

19.

Roth

Peters

Schmidtmann

Maus

Stephan

Augat

Intraosseous fixation compared to plantar plate fixation for first metatarsocuneiform arthrodesis: a cadaveric biomechanical analysis. Foot Ankle Int. 2014;35(11):1209-1216.

20.

Ruiz Muñoz

González-Sánchez

Cuesta-Vargas

. Tibialis anterior analysis from functional and architectural perspective during isometric foot dorsiflexion: a cross-sectional study of repeated measures. J Foot Ankle Res. 2015;8:74.

21.

Sammarco

Henning

Chaim

Surgical repair of acute and chronic tibialis anterior tendon ruptures. J Bone Joint Surg Am. 2009;91(2):325-332.

22.

Van Acker

Pingen

Luitse

Goslings

. Rupture of the tibialis anterior tendon. Acta Orthop Belg. 2006;72(1):105-107.

23.

Wang

JH.

Mechanobiology of tendon. J Biomech. 2006;39(9):1563-1582.

Supplementary Material

Please find the following supplemental material available below.

For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.

For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.

0.00 MB

0.11 MB