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ScienceDirect www.sciencedirect.com Chirurgie de la main 34 (2015) 151–153

Letter to the editor Fracture of the index sesamoid. A case report Fracture du se´samoı¨de de l’index. A` propos d’un cas Keywords: Index; Sesamoid bone; Fracture Mots cle´s : Index ; Os se´samoı¨de ; Fracture

We would like to focus on fractures of the sesamoid bone of the index finger, which are a rare condition. A sesamoid bone is said to be present in the index finger of 40–60% of the general population [1]. It is about 3.5 mm wide by 4.7 mm long and 2.5 mm thick. Despite its small size, it cannot be ignored by hand surgeons. We wanted to share the details of one clinical case. A 38year-old female flight attendant presented with acute pain at the base of the left index finger over the metacarpophalangeal (MCP) joint. This pain started after unscrewing a cap from a bottle. She was initially treated with non-steroidal antiinflammatory drugs (NSAIDs) and pain-relieving immobilization for 10 days, which led to significant but temporary improvement in her condition. The pain came back when her treatment and immobilization period ended. The initial local examination found edema with pain upon palpation of the volar side of the MCP joint, but no locking sensation in the index finger. The initial standard A/P and lateral radiographs of the hand were interpreted as normal. No abnormal findings of the index flexor mechanism were apparent on ultrasound assessment. At this point, additional digital A/P radiographs of the left index finger and oblique views with magnification were taken; these revealed a fracture line in the sesamoid, while the MCP joint was normal (Fig. 1). A bone scan focused on the hand showed increased uptake at sesamoid bone of the index finger, suggestive of trauma to the sesamoid bone (Fig. 2). Conservative treatment consisted of MCP immobilization in 908 flexion in a custom heat-molded brace with syndactyly with the middle finger; this allowed mobilization of the proximal interphalangeal (PIP) joints for two weeks, followed by rehabilitation. When this conservative treatment failed, we decided to carry out sesamoidectomy and a pathology evaluation. Under regional anesthesia, a tourniquet was placed at the base of the arm. A Bruner-type longitudinal skin incision was made and the tissues dissected meticulously. The sesamoid was split into two fragments, both of which were resected. The volar plate

http://dx.doi.org/10.1016/j.main.2015.01.009 1297-3203/# 2015 Elsevier Masson SAS. All rights reserved.

was then carefully closed. Gross examination of the surgical material found two 5-mm bone fragments. Microscopic examination of the decalcified fragments over multiple levels found normal appearing bone and cartilage tissue, with no evidence of bone necrosis or inflammation other than the presence of fibrous tissue and synovial fluid exudate. The sesamoidectomy was followed by 10 days of immobilization to relieve pain. At the last follow-up after six months, the patient was satisfied, her pain was completely gone and she had normal hand mobility. The QuickDASH went from 51 before the procedure to 13 afterward, a 38 point improvement. The patient was able to return to her occupation without encumbrance. The diagnosis of trauma-induced damage to the sesamoid bone of the index finger can be difficult to make, limited to the diagnosis of an MCP sprain, which can explain the delayed diagnosis following an injury to this bone. It generally presents as insidious pain over the MCP joint, but in some cases sudden pain occurs with signs of acute inflammation due to direct trauma, as in the case described here, which resembles the clinical picture of an index MCP joint sprain [2,3]. In this case, the fracture occurred when the patient unscrewed the cap from a bottle. We believe that the sesamoid’s radial location in the index exposes it to fracture during forceful thumb-index tip or power grip maneuvers. The differential diagnosis is fracture of diseased bone; this would more likely correspond to fragmentation of the sesamoid secondary due to repeated microtrauma. Fragmentation occurs in necrotic bone [2]. In taking the patient’s history, we found no risk factors for osteonecrosis, such as corticosteroid therapy. The patient also had no pain before the injury event. Pathology examination of the excised pieces was able to confirm a fresh fracture of the sesamoid bone by the presence of bone formation activity and was able to eliminate the possibility of fracture due to preexisting osteonecrosis. An in-depth literature search was performed of the Medline, Pub Med and electronic databases related to hand surgery, along with orthopedics and trauma journals up to March 2014. We reviewed keywords, titles and abstracts related to our research question. As a result, a few publications describing fracture of the sesamoid bone of the index finger were identified [2–4]. Standard A/P and 3/4 views of the hand are the primary evaluation method when a hand fracture is suspected. But these views are not sufficient to eliminate the possibility of sesamoid

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Letter to the editor / Chirurgie de la main 34 (2015) 151–153

Fig. 1. Standard radiographs of the index finger: oblique view with magnification showing the fracture line in the sesamoid.

Fig. 2. Bone scan showing increased uptake in the sesamoid, suggestive of a crack in the sesamoid bone.

fracture in the index finger [5]. These fractures can go unnoticed because of superimposition of neighboring bone structures; special views may be needed to clearly see the sesamoid bones [1]. Digital lateral views centered over the index and oblique views with magnification will help to detect fractures of the sesamoid bone of the index finger. Ultrasonography of the index can be performed to look for sesamoid fracture but the results are highly operator-dependent. Nevertheless, it can reveal fissures that are hard to identify using standard radiographs of the index. This imaging modality can also be used to eliminate other diseases in the soft tissues of the index. When radiographs suggest a fracture but a discrepancy exists between the symptoms and radiology findings, other

imaging modalities such as CT and MRI can be used. Like others [2], we believe that a CT scan centered over the sesamoid is the examination of choice, as this makes it possible to confirm the diagnosis of fracture of the sesamoid bone, namely a break in the cortex of the sesamoid bone that is not detected on standard radiographs. On MRI, the fractures are characterized by hyposignal on T1 and linear hypersignal on T2-weighted images. The main advantage of MRI is that it can show areas of necrotic bone in the sesamoid. A bone scan provides a functional and metabolic exploration of the sesamoid bone and can detect hidden fractures of the bone without a confirmed fracture diagnosis. Concerning treatment, as with our case, once conservative treatment has failed, surgical excision of the sesamoid is indicated while being careful to not completely detach the volar plate. The traditional approach is a Bruner-type volar incision centered over the sesamoid being excised; synovectomy is often performed in combination, and can be tendinous, articular or both. Baek et al. [4] described a fracture of the sesamoid of the index in the context of an accident with hyperextension of the MCP joint, which was treated by simple immobilization. Immobilization, NSAIDs and corticosteroid injections, which have been used to treat sesamoid injuries in locations other than the index, can be used. If the pain persists and becomes disabling despite symptomatic treatment, surgical excision of the sesamoid is a viable treatment alternative. Sesamoidectomy appears to be an effective treatment after failed conservative treatment, and it also provides material for pathology evaluation to obtain an accurate diagnosis. Hand surgeons must not forget about the potential presence of a sesamoid bone in the index finger. Although this bone is small in size, it can fracture. Thus, sesamoid fracture must be considered as a possible diagnosis. The treatment is initially conservative, but surgical excision of the bone is an effective solution in cases of failure. Disclosure of interest The authors declare that they have no conflicts of interest concerning this article. References [1] Wood VE. The sesamoid bones of the hand and their pathology. J Hand Surg Br 1984;9:261–4. [2] Moreel P, Nanhekhan LV, Le Viet D. Pathologie par fragmentation du sésamoïde de l’index dans le cadre de microtraumatismes répétés : à propos d’un cas et revue de la littérature. Chir Main 2005;24:254–7. [3] Capo JA, Kuremsky MA, Gaston RG. Fractures of the lesser sesamoids: case series. J Hand Surg Am 2013;38:1941–4. [4] Baek GH, Chung MS, Kwon BC, Ahn BW. Fracture of the index sesamoid – a case report. Acta Orthop Scand 2002;73:715–6. [5] Van Asch Y, Vreugde M, Brabants K. Atraumatic avascular necrosis of an index sesamoid. Chir Main 2005;24:251–3.

Letter to the editor / Chirurgie de la main 34 (2015) 151–153

a

H. Boussakria*b, F. Dusserrea, J.-L. Rouxa Institut Montpelliérain de la main, clinique Clémentville, 34000 Montpellier, France b Service de chirurgie ostéo-articulaire (B4), CHU Hassan II, 30000 Fès, Morocco

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Corresponding author E-mail address: [email protected] (H. Boussakri). Received 15 November Revised 21 January Accepted 27 January Available online 29 April

2014 2015 2015 2015

Fracture of the index sesamoid. A case report.

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