The effect of peroneus brevis tendon anatomy on the stability of fractures at the fifth metatarsal base.

BACKGROUND: Nonunion of classic Jones fractures has typically been attributed to the precarious vascular anatomy of the proximal fifth metatarsal. Despite this theory, the operative treatment of these fractures utilizes biomechanical solutions. The purpose of the present study was to evaluate the influence of the peroneus brevis (PB) tendon on the stability of fractures of the proximal fifth metatarsal. METHODS: We utilized 5 matched pairs (10 specimens) of fresh-frozen cadaveric specimens. We used 2 loading conditions: (1) a simulated fracture distal to the PB insertion (Jones equivalent) and (2) a simulated fracture within the footprint of the PB insertion (avulsion equivalent). Following the creation of the fracture, each lower extremity was statically loaded through the Achilles and PB tendons. Our primary outcome measure was the degree of fracture diastasis with loading of the PB. Anteroposterior images with and without loading were obtained to evaluate fracture separation. We utilized a paired Student t test and the intraclass correlation coefficient (ICC) for all statistical analyses. RESULTS: The average length of the PB footprint was 15.2 mm. The simulated Jones fractures demonstrated greater fracture widening following loading of the PB tendon compared to the simulated avulsion fractures. The simulated avulsion fractures widened 0.4 mm on loading compared to 1.1 mm of widening in the simulated Jones fractures (P = .02). Intraobserver reliability for all radiographic measurements showed substantial agreement (ICC = 0.91). CONCLUSION: The PB exerted a deforming force on the proximal fragment of simulated Jones fractures. This deforming force was less pronounced in the simulated avulsion fractures. The principal findings of this study were that proximal fifth metatarsal fractures distal to the PB insertion were significantly more unstable than more proximal fractures. CLINICAL RELEVANCE: Our findings help support the notion that a mechanical component may contribute to the poor healing potential of Jones fractures secondary to deformation exerted by the PB tendon.

A Simple Radiographic Sign of Vertical Anterior Cruciate Ligament Tunnel Placement.

The purpose of this study is to describe a novel radiographic sign indicative of vertical tunnel placement following anterior cruciate ligament (ACL) reconstruction. We reviewed 190 consecutive ACL reconstructions. Operative records, patient charts, arthroscopic images, and preoperative and postoperative orthogonal plain radiographic images were reviewed. We made special note of the operative technique. Note was made of tunnel position and whether the posterior (proximal) aspect of Blumensaat line was violated on standard lateral knee radiographic images. Of 190 patients, 17 patients did not have postoperative imaging and were excluded. Of the 173 remaining knees, 163 were primary ACL reconstructions and 10 were revision ACL reconstructions. We found that no anatomically placed ACL femoral tunnel violated Blumensaat line. In all revision cases exhibiting violation of Blumensaat line, a new femoral tunnel was able to be drilled while completely avoiding the previously placed, nonanatomic ACL femoral tunnel. The principal findings of our study demonstrate that violation of Blumensaat line following ACL reconstruction is an indicator of vertical, nonanatomic femoral tunnel placement. Furthermore, presence of this radiographic sign indicates that an anatomically placed femoral tunnel may be drilled while completely avoiding the existing femoral tunnel during cases of revision ACL reconstruction.

Ewing's sarcoma/primitive neuroectodermal tumor of the proximal humeral epiphysis.

Ewing's sarcoma/primitive neuroectodermal tumor (ES/PNET) of bone is a rare childhood tumor most commonly located in the metadiaphysis. In skeletally immature patients, lesions of the epiphysis are rarely malignant, with the most common diagnosis being chondroblastoma. This article presents a case of ES/PNET of the proximal humeral epiphysis in a 12-year-old boy. To the authors' knowledge, this is the first reported case of epiphyseal ES/PNET confirmed with molecular testing. Radiographs of the patient's painful shoulder showed a well-defined lytic lesion within the humeral epiphysis. Magnetic resonance imaging suggested a chondroid tumor with surrounding edema. Based on the imaging characteristics, the patient's age, and the lesion's location, a preliminary diagnosis of chondroblastoma was made. A trochar biopsy of the lesion demonstrated a small, round, blue cell tumor on frozen section. Subsequently, immunohistochemical staining was uniformly positive in a membrane pattern for CD99, and molecular diagnostic testing demonstrated a EWSR1/FLI1 fusion transcript, confirming the pathologic diagnosis of ES/PNET. Although metadiaphyseal locations for ES/PNET are most common, this case adds to previously reported cases of epiphyseal ES/PNET, suggesting that the diagnosis be considered for pediatric epiphyseal tumors. This case also demonstrates why following rigorous oncologic treatment algorithms by obtaining a limited trochar biopsy, even in the case of a confident radiographic diagnosis, is critically important; the biopsy results can lead to a major change in treatment and avoid contamination of a larger area of soft tissue and bone.