Skeletal Radiol https://doi.org/10.1007/s00256-017-2790-7 CASE REPORT Stener-like lesion of the lateral collateral ligament of the first metatarsophalangeal joint S. Braspenningx 1 & W. Rezaie 2 & P. Simons 3 Received: 3 September 2017 / Revised: 2 October 2017 / Accepted: 4 October 2017 # ISS 2017 Abstract Displaced ulnar collateral ligament injuries of the metacarpophalangeal joint of the thumb, also known as Stener lesions, are a well-recognized clinical entity, requiring surgical intervention because of the trapped location of the torn lateral collateral ligament superficial to the adductor aponeurosis of the thumb. We report a similar lesion located at the first metatarsophalangeal joint, to our knowledge the first ever described in the literature. In our patient, magnetic resonance imaging showed a full-thickness tear of the lateral collateral ligament of the first metatarsophalangeal joint, as well as a full-thickness tear of the extensor hood, with dislocation of the proximal part of the ruptured lateral collateral ligament to a position superficial to the extensor hood. Analogous to true Stener lesions, we are convinced these patients also need early surgical repair. Therefore, we would like to raise awareness about their existence to ensure adequate management of these lesions, in order to prevent possible long-term complications like chronic pain, instability, and joint degeneration. Keywords MRI . First metatarsophalangeal joint . Lateral collateral ligament . Stener-like lesion . Surgical repair * S. Braspenningx firstname.lastname@example.org 1 Department of Radiology, Antwerp University Hospital & University of Antwerp, Wilrijkstraat 10, 2650 Edegem, Belgium 2 Department of Orthopaedic Surgery, Onze-Lieve-Vrouwziekenhuis Aalst, Moorselbaan 164, 9300 Aalst, Belgium 3 Department of Radiology, Onze-Lieve-Vrouwziekenhuis Aalst, Moorselbaan 164, 9300 Aalst, Belgium Introduction Ulnar collateral ligament (UCL) injury of the metacarpophalangeal (MCP) joint of the thumb, often referred to as gamekeeper’s thumb, was originally described in 1955 by Campbell et al. as an occupational injury of Scottish gamekeepers . It is very important to distinguish a non-displaced ulnar collateral ligament tear from a displaced tear or Stener lesion. The surgical indication of the latter has well been established meanwhile, while non-displaced tears are treated conservatively. The mechanism of injury in a Stener lesion is described in Fig. 1 . Similar lesions have been described in the UCL of the proximal interphalangeal joint of the ring finger , the radial collateral ligament of the MCP joint of the thumb , the radial collateral ligament of the MCP joint of the fifth finger [5–7], the radial collateral ligament of the MCP joint of the third finger , the radial collateral ligament of the MCP joint of both the third and fourth fingers , and the medial collateral ligament of the knee [9, 10]. Ishizuki et al.  described five distally avulsed collateral ligaments, in which the torn end was trapped by the open window of the injured sagittal band (Fig. 2), as well as one proximally avulsed collateral ligament, in which the torn end was trapped by the sagittal band. Stener-like lesions located at the level of the foot, and more specifically the metatarsophalangeal (MTP) joint, have never been described before. However, we as radiologists, as well as our orthopedic surgeons, are convinced early operative treatment is also mandatory in these cases. Therefore, we would like to raise awareness about their existence to ensure optimal clinical management of these injuries. Skeletal Radiol Fig. 1 Mechanism of Stener lesion . a Normal situation: the UCL (ulnar collateral ligament proper and ulnar accessory collateral ligament) is completely covered by the adductor aponeurosis. b, c Simultaneous abduction, supination, and flexion forces causing the UCL to rupture (almost always at its distal attachment), the torn end of the UCL passes the proximal edge of the adductor aponeurosis. d The phalanx has returned to its original position and the ligament gets caught by the aponeurosis and folded over to point proximally. The interposed adductor aponeurosis prevents conservative healing Case report A 14-year-old girl presented to the emergency department with a hyperextension, abduction, and inversion trauma of the left hallux 1 day before at her taekwondo class. Right away she noticed severe soft tissue swelling. The ability of weight bearing was clearly limited. At clinical examination, the first metatarsophalangeal joint was very tender and mobility was greatly reduced. Mainly dorsiflexion against resistance was Fig. 2 Mechanism of Stener-like lesion . a Normal situation: the LCL is completely covered by the extensor hood. b, c Simultaneous abduction, supination, and hyperextension forces causing the LCL and extensor hood to rupture, the torn end of the LCL passes the proximal edge of the ruptured extensor hood. d The phalanx has returned to its original position and the ligament gets caught by the ruptured extensor hood, which prevents conservative healing very painful. Conventional radiography (Fig. 3) was performed, but did not show any abnormalities. Because of these reassuring findings, the patient was discharged with adequate analgesic therapy and the advice of rest, ice application, and elevation. However, 1 month later the patient still complained of pain and swelling of first MTP joint, mainly during exercise. Physical examination demonstrated lateral collateral ligament (LCL) instability of the first MTP joint by varus stress testing. A 3-T MRI of the foot was performed. With the use of Skeletal Radiol superficially located torn end of the LCL and the extensor hood. These adhesions had to be released. Subsequently, the LCL was reinserted to the footprint of ligament by a mini Mitek anchor (Mini Quickanchor, DePuy). Afterwards, the extensor hood was sutured. Postoperative treatment consisted of weight-bearing with hallux brace. Gradual return to sports activity was managed by physiotherapy and full functional recovery was obtained after 6 weeks. Discussion Fig. 3 Conventional AP radiographic view of the foot is unremarkable with no evidence of fracture or first MTP joint space widening a 3.0-T HD 8Ch foot/ankle coil, long-axis (TR/TE, 3216/56,35), short-axis (TR/TE, 3775/41,29) and sagittal (TR/TE, 4038/58,41) proton density-weighted images with fat saturation were obtained, as well as axial T1-weighted (TR/TE, 406/10,83) images. The short- and long-axis proton density-weighted images showed a full-thickness tear of the extensor hood (Fig. 4a–c). A dislocation of the proximal part of the ruptured LCL to a position superficial to the extensor hood was noted on the short- and long-axis proton densityweighted images (Fig. 4a and c). There were no associated lesions of the plantar plate. Subsequent stress radiography (Fig. 5) revealed a lateral diastasis of the first metatarsophalangeal joint under valgus stress, as expected. Because of the locked position of the ruptured LCL superficial to the extensor hood, quite similar to a Stener lesion, the patient was admitted for surgical repair. Intraoperative findings confirmed the ruptured extensor hood, as well as the superficial position of the ruptured LCL in relation to it (Figs. 6b and 7). Due to the time delay between traumatic event and surgery, scar tissue had already been formed, and there were already some adhesions between the Lesions of the first MTP joint like acute traumatic hallux valgus deformity (due to a medial collateral ligament tear), turf toe (hyperdorsiflexion injury to the first MTP capsuloligamentous complex), and sand toe (hyperplantarflexion injury) are well known. We describe a unique lesion of the LCL, to our knowledge the first of its kind described in the literature. This lesion shows strong resemblance to a Stener lesion of the thumb and presents in an analogous way, as will be discussed later on. Stener lesions of the thumb occur due to combined abduction, supination, and hyperextension forces. In our patient, a similar lesion arose from a hyperextension, abduction, and inversion trauma of the hallux. In Stener lesions, the intact adductor aponeurosis is interposed between the torn end of the UCL and the site of its phalangeal attachment. According to Ishizuki et al. , in Stener-like lesions of the little finger, the sagittal band ruptures at the same level of the joint. The torn end of the UCL then becomes trapped by the open window of the ruptured sagittal band (Fig. 2), and prevents spontaneous healing. We believe the mechanism of the lesion we describe, in which the LCL of the first MTP joint becomes trapped by the ruptured extensor hood, is very similar to the one of these other lesions. In general, Stener or Stener-like lesions present with local pain, swelling, and difficulties in movement of the affected phalanx. If untreated, they may lead to chronic instability. Stress tests are helpful in differentiating partial from fullthickness collateral ligament tears . It has been described that palpation of a tender mass at the base of the phalanx can be a strong indication of a displaced ruptured collateral ligament . At the level of the metatarsophalangeal joint, this tumor might not be palpated as easy as at the first metacarpophalangeal joints, which would make the role of imaging in these cases more important. Radiographs are often obtained after these kinds of traumatic events, and may show bony avulsion fractures. Thirkannad and Wolff  described the Btwo fleck sign^ in which two separate bony fragments are seen. The largest fragment can be seen at the suspected attachment of the UCL but was in fact not associated with it, and is part of the attachment of the adductor pollicis muscle. The more discrete second fragment is in fact the one attached to the torn and displaced Skeletal Radiol Fig. 4 Short- and long-axis proton density-weighted images (TR/ TE, 3775/41,29 and TR/TE, 3216/56,35 resp.) revealing a fullthickness tear of the extensor hood (white arrow in a, b, and c). Dislocation of the proximal part of the ruptured LCL to a position superficial to the extensor hood (arrowhead in a and c) as seen on the short- and long-axis proton density-weighted images distal end of the UCL. No bony avulsions could be detected in our patient. Faivre et al.  state that clinical examination and standard radiographs should be sufficient to provide a correct diagnosis and distinguish simple sprains from more serious lesions with important laxity. However, they cannot distinguish non-displaced from displaced ruptures of the collateral ligament. Some controversy exists about stress radiographs, because they might worsen the injury. Nevertheless, they clearly showed instability in this case. Ultrasound is a very accurate method for demonstrating lesions of the collateral ligament, but should be performed by an experienced sonographer . The exact sonographic approach has been described for lesions of the UCL of the thumb, but is beyond the scope of this case report and can Fig. 5 Conventional AP radiographic view under valgus stress demonstrating a lateral diastasis of the first metatarsophalangeal joint (white arrow) be found elsewhere [13, 14]. Potential pitfalls of ultrasound include shrinkage of the ligament and formation of scar tissue, starting as early as 1 week after the traumatic event . The accuracy of magnetic resonance imaging may also be affected by e.g., scar tissue in chronic lesions, but it is still considered the best method for evaluating collateral ligament injuries [16–18]. Magnetic resonance imaging is able to differentiate between non-displaced and displaced ruptures of the collateral ligament. It also visualizes surrounding structures and is therefore very useful for ruling out mimics of collateral Fig. 6 Schematic overview of intra-operative findings. a Normal anatomy showing an intact extensor hood. b Ruptured extensor hood and LCL, with the distal part of the LCL located superficial to the extensor hood. Some adhesions between them had already been formed Skeletal Radiol Informed consent Informed consent was obtained from all individual participants included in the study. References 1. 2. Fig. 7 Intra-operative findings. The torn end of the LCL (arrowhead) was found in a position superficial to the ruptured extensor hood (white arrow). Adhesions between both were already present and had to be released 3. ligament injury. Hergan et al.  state that magnetic resonance imaging should always be used to check a nondisplaced UCL tear diagnosed by ultrasound before conservative therapy is performed. In our case, magnetic resonance imaging was critical to guide therapy due to the complex nature of the lesion, as the extensor hood was also ruptured and granulation tissue was already present 1 month after the event. Displaced collateral ligaments are a surgical indication. Their repair should be performed at an early stage to avoid aberrant adhesion of the collateral ligament, a process that had already started in our patient, with the torn end of the LCL located superficial to the extensor hood. Both the primary and accessory parts of the collateral ligament need to be sutured to their original attachment . Like in our patients, suture anchors have become quite popular for this purpose. The ruptured extensor hood was also sutured in our patient, and adequate stability of the joint was achieved. In conclusion, we would like to stress the indication for early operative treatment in these kinds of displaced collateral ligament ruptures. Therefore, the main goal of this case report is to stress the importance of posttraumatic imaging of the ligaments of the toes and raise awareness about the existence of this Stener-like lesion of the lateral collateral ligament of the first metatarsophalangeal joint in order to ensure similar patients are treated adequately at an early stage, and to prevent possible long-term complications like chronic pain, instability, and joint degeneration. 5. 4. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. Compliance with ethical standards 16. Conflict of interest The authors declare that they have no conflicts of interest. 17. 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