Os Intermetatarseum: An important consideration in chronic foot pain

dc.creatorPatel, Kavitaen_US
dc.creatorJafferji, Fatemaen_US
dc.description.abstractBackground: The os intermetatarseum is the rarest accessory bone of the foot. It was first described by Gruber in 1856 but well documented cases have been infrequently reported throughout literature. This accessory bone is located on the dorsal aspect of the foot in between the base of the first and second metatarsals. It varies in shape and size and usually presents bilaterally. Chronic dorsal mid foot pain following impingement of the deep peroneal nerve by the os intermetatarseum is common in symptomatic patients and an important consideration in this case. Case Presentation: A 70 year old Caucasian female with a past medical history of depression, thyroid disease, and neuropathy presents with chronic left foot pain rated 10/10, starting 4 years ago. She describes it as a burning and aching pain that comes and goes. The pain, described as burning and aching, occurs on the left anterior ankle, lateral ankle, and forefoot, aggravated by walking, prolonged standing, and toe extension. Alleviated by leg elevation, rest, and sitting. She has been seen by 2 podiatrists and was given a steroid injection by both. The first injection did not help and the 2nd injection lasted for one year. Physical examination revealed pain upon palpation of the peroneal tendon as it courses posterior to the lateral malleolus and at the tip of the fibula. Both peroneus longus and brevis were intact with manual testing. No pain upon palpation of the 1st metatarsal joint, but pain upon palpation of the left 3rd and 4th metatarsal shaft. The dorsalis pedis pulse was 2/4 bilaterally and the posterior tibial pulse was 2/4 bilaterally. Neurological assessment of positive sensation and light touch were intact bilaterally. There were no significant dermatologic lesions present. Bilateral foot assessment showed adequate skin tone, texture, and turgor with a normal temperature gradient. After the initial visit, the patient was instructed to modify her activity and shoe wear to incorporate more fitted supportive tennis-type shoe. On the one-week follow-up visit to discuss MRI findings, the patient reported her pain level decreased to a 4/10. MRI reveals a marked longitudinal arch, moderate hallux valgus, longitudinal split tear of peroneus brevis retromalleolar to inframalleolar distribution, and short segmental split tear of peroneus longus proximal to cuboid tunnel. There was no convincing evidence of an occult fracture or stress injury. A small intermetatarseum was noted between the bases of the first and second metatarsals dorsally that likely articulates with the 1st metatarsal base. Due to the presence of segmental tears involving the peroneus brevis and longus, the podiatrist catered his treatment plan to address tenosynovitis. After discussing the diagnosis and potential treatment plans the patient opted to undergo surgery. Conclusion: Refractory foot pain aggravated by physical activity and symptoms of deep peroneal nerve compression should prompt consideration of a painful os intermetatarseum. Initially, conservative measures like NSAIDs, shoe adjustments, and rest should be employed to address this potential diagnosis, reserving surgical interventions as a final option.en_US
dc.titleOs Intermetatarseum: An important consideration in chronic foot painen_US