Case Report
Supernumerary Intermediate Cuneiform with Bifid First Metatarsal: A Case Report
Joel Ang1, Jamey Allen1, Priya Anand1 and Michael Theodoulou2*
1Department of Podiatric Suregry, Cambridge Health Alliance, Cambridge, MA, USA
2Department of Podiatric Suregry, Cambridge Health Alliance, Harvard Medical School, Cambridge, MA, USA
*Corresponding author: Michael H Theodoulou, Department of Podiatric Suregry, Cambridge Health Alliance, Harvard Medical School, Cambridge, MA, USA
Published: 23 May, 2017
Cite this article as: Ang J, Allen J, Anand P, Theodoulou M.
Supernumerary Intermediate Cuneiform
with Bifid First Metatarsal: A Case
Report. Clin Surg. 2017; 2: 1494.
Abstract
Anatomic anomalies of the cuneiform bones are a relatively rare finding in the lower extremity. Congenital abnormalities of the middle and lateral cuneiform specifically are not often documented in literature. We present a case of a patient with an additional osseous structure distal to the intermediate cuneiform which articulates with a bifid base of the first metatarsal. We hypothesize this to be a supernumerary intermediate cuneiform
Introduction
Anatomic anomalies of the cuneiform bones are a relatively rare finding in the lower extremity.
The most recognized congenital entity is the bipartite medial cuneiform, which has been reported
in a number of archeological studies and case reports [1-3]. The bipartite medial cuneiform is split
in the transverse plane, generally resulting in a smaller dorsal and a larger plantar segment [4]. The
incidence of a bipartite medial cuneiform in the general population is believed to range between
0.1%-0.3%, with a higher rate in males [4,5]. The bipartite medial cuneiform is often of little clinical
significance, and is usually an incidental finding of routinely obtained radiographic imaging.
Nevertheless, there are some patients with symptomatic presentations secondary to bipartite medial
cuneiforms that have required either conservative care or surgical intervention [6,7].
Congenital abnormalities of the middle and lateral cuneiform, in contrast, are rarely reported in
literature. The os intercuneiform - an accessory ossicle between the medial and middle cuneiform
just distal to the navicular - is one of the few entities described. To our knowledge only one case
report has been published regarding a true supernumerary cuneiform, which was located between
the base of the second metatarsal and the anterior aspect of the middle cuneiform [4].
We present a case of a patient with an additional osseous structure distal to the intermediate
cuneiform which articulates with a bifid base of the first metatarsal. We hypothesize this to be a
supernumerary intermediate cuneiform.
Case Presentation
A 61 year old female presented to our clinic with chief complaint of bilateral foot pain, left
greater than right, for the past three months. The patient denied any acute traumatic incident, but
does relate a recent increase in daily walking. The only relevant past medical history was a multilevel
lumbar fusion for spinal stenosis eighteen months prior to her clinical visit.
On physical examination, tenderness to palpation was appreciated at the insertion of the
Achilles tendon on the left foot. No edema, erythema or ecchymosis was noted, and no palpable
nodules were appreciated within the tendon. Tenderness was elicited at the plantar aspect of the left
second metatarsophalangeal joint, with associated medial deviation of the second digit. No frank
vertical instability was found at the second digit. A pes planus foot type was observed bilaterally.
Dorsoplantar, lateral, oblique and axial sesamoid radiographs were obtained of both feet, which
revealed surprising congenital tarsometatarsal abnormalities. On the right foot a bifid first metatarsal
base is present, articulating with the medial cuneiform as well as a supernumerary intermediate
cuneiform. This additional cuneiform bone notably has a partial osseous bridging with the base
of the second metatarsal as well as a proximal osseous structure presumed to be the intermediate
cuneiform. The intermediate cuneiform is noted to have partial osseous bridging with the second
and third metatarsal bases (Figure 1 and 2). Interestingly imaging of the contralateral foot revealed a
similar presentation with exception of what is suspected to be a complete osseous union between the supernumerary intermediate cuneiform and intermediate cuneiform (Figure 3 and 4).
Despite the patient’s congenital radiographic abnormalities, her
primary complaints were found to be unrelated to these abnormalities.
As a result, no additional imaging was warranted.
Figure 1
Figure 2
Figure 2
Oblique radiograph of the right foot with supernumerary intermediate
cuneiform as well as multiple coalitions across the tarsometatarsal joint
complex.
Discussion
There is limited literature available regarding accessory
intermediate cuneiform bones. In the only other case published by
Brooks-Fazakerley et al. [4] the accessory intermediate cuneiform
was associated with a shortening of the second metatarsal. The
patient experienced persistent midfoot pain secondary to significant
osteoarthritis at the level of the tarsometatarsal joints, and eventually
underwent surgical fusion of the joints. In our patient, no metatarsal
shortening was noted. However, two findings are of significant interest.
First, there is the presence of a bifid first metatarsal base bilaterally.
The first metatarsal base normally forms a reniform articulating
surface solely with the medial cuneiform. In this case, an additional
articulating surface is noted with the supernumerary cuneiform on
the right foot and the intermediate cuneiform on the left foot, which
is an unusual abnormality. This finding is especially notable given
that most accessory ossicles do not form articulating joint surfaces
[4]. Second, there are a significant number of coalitions noted across
the tarsometatarsal joint level bilaterally. While functional movement
across the LisFranc joint level is minimal in comparison to other
joints in the foot, one would expect some arthritis in adjacent joints
in a 61 year old patient due to compensation. However, our patient
displays no significant radiographic evidence of osteoarthritis and
was also noted to be asymptomatic at the tarsometatarsal joint level.
Fortunately for our patient, her congenital abnormalities have not
caused any pathology thus far.
Based on our patient’s radiographic presentation, we suspect
that the supernumerary cuneiform on the right foot is a result of an
incomplete osseous union to the intermediate cuneiform. Complete
union would have resulted in a presentation similar to that found in
the left foot. This will be important to consider in the future should
the patient suffer a traumatic injury on the right foot, disrupt the
partial bridging and experience pain. Naturally, in the context of
trauma clinicians should determine whether a fracture fragment
or a true supernumerary bone is present, especially with new onset
of pain. Chang et al. [5] describe a case where a bipartite medial
cuneiform that was discovered after the patient sustained a Lisfranc
injury. This case noted two separate attachments of the Lisfranc
ligament complex, and highlights how treatment considerations may
change in situations of anatomical anomalies in comparison to acute
fracture fragments. Should our patient warrant further treatment, a
CT scan would allow for better visualization of the tarsometatarsal
complex. The range of treatment options for pain resulting from
congenital abnormalities at the level of the cuneiforms range from
accommodative shoe gear to oral anti-inflammatories to ultrasound
or fluoroscopic guided cortisone injections [7]. Surgical options may
include excision or primary fusion.
Figure 3
Figure 3
Dorsal-plantar radiograph of the left foot with congenitally abnormal
intermediate cuneiform.
Figure 4
Figure 4
Oblique radiograph of the left foot with multiple coalitions across
the tarsometatarsal joint complex.
Conclusion
We report a clinically unique finding of a bifid first metatarsal base with a supernumerary intermediate cuneiform that has not been described in the literature to this date.
References
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