Distal Metatarsal Articular Angle in Hallux Valgus Deformity. Fact or Fiction? A 3-Dimensional Weightbearing CT Assessment

Background The Distal Metatarsal Articular Angle (DMAA) was previously described as an increase in valgus deformity of the distal articular surface of the first metatarsal (M1) in hallux valgus (HV). Several studies have reported poor reliability of this measurement. Some authors have even called into question its existence and consider it to be the consequence of M1 pronation resulting in projection of the round-shaped lateral edge of M1 head. Our study aimed to compare the DMAA in HV and control populations, before and after computer correction of M1 pronation and plantarflexion with a dedicated weightbearing CT (WBCT) software. We hypothesized that after computerized correction, DMAA will not be increased in HV compared to controls. Methods: We performed a retrospective case-control study including 36 HV and 20 control feet. In both groups, DMAA was measured as initially described on conventional radiographs (XR-DMAA) and WBCT by measuring the angle between the distal articular surface and the longitudinal axis of M1. Then, the DMAA was measured after computerized correction of M1 plantarflexion and coronal plane rotation using the α angle (3d-DMAA). Results: The XR-DMAA and the 3d-DMAA showed higher significant mean values in HV group compared to controls (respectively 25.9 ± 7.3 vs 7.6 ± 4.2 degrees, P < .001, and 11.9 ± 4.9 vs 3.3 ± 2.9 degrees, P < .001). Comparing a small subset of precorrected juvenile HV (n=8) and nonjuvenile HV (n=28) demonstrated no significant difference in the measure DMAA values. On the other hand, the α angle was significantly higher in the juvenile HV group (21.6 ± 9.9 and 11.4 ± 3.7 degrees; P = .0046). Conclusion: Although the valgus deformity of M1 distal articular surface in HV is overestimated on conventional radiographs, comparing to controls showed that an 8.6 degrees increase remained after confounding factors’ correction. Clinical Relevance: After pronation computerized correction, an increase in valgus of M1 distal articular surface was still present in HV compared to controls. Level of Evidence: Level III, retrospective case-control study.

Operative Fixation of Pediatric Forearm Fractures: Does the Fracture Location Matter?

Background. Flexible intramedullary nails (FNs) are successfully used to treat pediatric forearm fractures, especially midshaft fractures. Distal forearm fractures have been described as “difficult to manage” with FN insertion. The purpose of this study was to report the clinical and radiographic outcomes of using flexible nails in pediatric forearm fractures and the impact of fracture location on the outcome of the procedure. Methods. This is a retrospective review of pediatric patients who presented with forearm fractures that were surgically treated with flexible nails between 2009 and 2018. Patient demographics, fracture location, and classification were reported. Intraoperative and postoperative complications were reported. The primary outcomes were fracture radiographic union, intraop and postop complications, and the need for additional surgical procedures. Results. Fifty-nine patients were included, with a mean age of 11 years. All fractures healed with patients regaining full range of motion. The authors were able to use flexible nails successfully in 48/59 (81%) patients. In eleven cases (19%), FN fixation was not able to provide adequate fixation to maintain reduction. The method of fixation was changed from FN insertion to another method in nine cases. In two cases, FN fixation was augmented with another fixation method. Fractures within 3 inches of the distal articular surface were at a higher risk of intraoperative change/augmentation of the fixation method (29%) compared with fractures that occurred more than 3 inches from the distal articular surface (11%). Conclusion. The majority of pediatric forearm fractures can be treated successfully with flexible nails. Surgeons involved in treating these fractures should pay attention to distal third fractures. Stabilizing the distally located fractures using FN fixation can be challenging. Surgeons should be prepared to use an alternative fixation method when needed.

Simulated weightbearing computed tomography for verification of radiographic staging of varus ankle osteoarthritis: a cross-sectional study

Background Varus ankle osteoarthritis is classified using only weightbearing anteroposterior ankle radiographs; however, sagittal ankle alignment may also affect the position and extent of joint space obliteration. We hypothesized that the sagittal alignment of the ankle may also affect the position and extent of joint space obliteration visible on the coronal section; therefore, we identified the sites of joint space obliteration in patients with stage 3 varus ankle osteoarthritis for comparison with the sites observed on simulated weightbearing computed tomography and investigated the effects of anterior and posterior ankle subluxation. Methods Simulated weightbearing computed tomography scans of 83 ft with varus ankle osteoarthritis (26 stage 3a, 57 stage 3b) were performed to check for joint space obliteration in the ankle. Further classification as exhibiting either anterior, posterior, or no subluxation on weightbearing lateral radiographs was performed. Results Anterior, posterior, and no subluxation was seen in 5, 9, and 12 ankles among the 26 classified as stage 3a, respectively, and in 22, 12, and 23 ankles among the 57 classified as stage 3b, respectively. The mean tibial lateral surface angle on weightbearing lateral radiographs in stage 3a ankles was 75.6, 83.3, and 80.3 degrees in the anterior, posterior, and no subluxation groups, respectively; and 75.5, 86.6, and 82.7 degrees in stage 3b ankles (p < .05). In stage 3b ankles, widespread joint space obliteration was observed at the anterior distal articular surface of the tibia in all 22 ankles with anterior subluxation and at the posterior distal articular surface of the tibia in all 12 ankles with posterior subluxation. Conclusions Simulated weightbearing computed tomography revealed joint space obliteration at the anterior distal articular surface of the tibia in stage 3b ankles with anterior subluxation and at the posterior side in stage 3a and 3b ankles with posterior subluxation. In some patients with stage 3 varus ankle osteoarthritis, the obliteration of the joint space is difficult to evaluate accurately using only weightbearing anteroposterior radiographs; weightbearing lateral radiographs should also be performed.

The Effect of Lunate Morphology in Carpal Disorders: Review of the Literature

Variation in lunate morphology can exist based on the absence (Type I) or presence (Type II) of medial facet on the distal articular surface of the lunate that contacts the proximal pole of the hamate. This additional lunatohamate articulation can affect load transmission across the radiocarpal joint and exert an influence on carpal kinematics. A Type II lunate is protective against carpal instability patterns associated with scaphoid nonunions and scapholunate dissociations. It may also play a role in the progression of carpal collapse that occurs in Kienböck disease. This review summarizes the effect of lunate morphology in the outcomes of non-operative and operative treatment of carpal disorders.

Surgical Anatomy of the Medial Cuneiform (Cotton) Osteotomy

Background: The Cotton osteotomy, or dorsal-opening wedge osteotomy of the medial cuneiform (MC), is used to address medial column alignment to restore the static-triangle of support. There are many described techniques regarding the incision and osteotomy. Successful completion of the osteotomy requires knowledge of the anatomy, particularly the location of the medial dorsal cutaneous nerve (MDCN). This study describes the relationship between MDCN, tibialis anterior, extensor-hallucis-longus tendon, and ligamentous attachments to the MC. A technique to determine a safe location for the osteotomy is also described. Methods: Twelve fresh-frozen adult foot specimens were used for this study (7 male and 5 female). The MDCN and its branches were dissected and its relationship with the MC was documented. Osteotomy tilt angle and relationship to structures around the MC were measured. Results: MDCN traveled medially and distally over the dorsum of the MC, and a small branch to the MC was observed. The tilt angle was 80.1 ±1.4 degrees. There was no significant difference between the distance from the distal-articular surface to the midline of the cuneiform and to the interosseous ligament ( P = .69), or between the distance from the distal-articular surface to the second tarsometatarsal joint and to the origin of the Lisfranc ligament ( P = .12). Conclusions: The dorsal-medial-oblique incision effectively protected MDCN and the MC. We believe the osteotomy should be performed in the safe zone to maintain the stability of the opening wedge. Clinical relevance: The dorsal-medial-oblique incision could reduce the risk of injury to the MDCN and the tibialis-anterior tendon.

Approximations to the Tibial Distal Anatomical Axis in the Sagittal Plane

Objective The aim of this study was to compare approximations to the tibial distal anatomical axis (DAA) with regression lines for the symmetric axis of the tibia, and to identify an optimal approximation for surgical planning of osteotomies for the management of canine cruciate ligament deficiency. Study Design Prospective radiographic study of 20 canine tibiae. Using curve-fitting and the symmetric axis technique, the true anatomical axis was identified for each tibia. Regression lines were calculated for the distal 67% and distal 50% subsections of this axis. Angular deviations between these lines and DAA approximations were calculated and compared with to find the closest approximations. Results The DAA approximations based on the distal 50% rather than the distal 67% of the tibia had smaller maximal deviations from the true axis. Landmarks at 50% and 75% of tibial length exhibited greater deviations than those at 50% and 95% or 100%. Conclusion The DAA landmarks should be restricted to the distal half of the tibia. Use of a distal landmark either just proximal to the distal metaphyseal flare of the tibia or at the mid-point of the distal articular surface is to be preferred. In this way, the DAA will better reflect the true anatomical axis of the distal tibia.

Radiographic Assessment of First Tarsometatarsal Joint Shape and Orientation

Background: Hypermobility within the first tarsometatarsal (TMT) joint is a predisposing factor for hallux valgus. The purpose of this study was to assess whether the shape and angulation of the first TMT joint are affected by the positioning of the foot in radiographs. Methods: Ten adult above-knee fresh-frozen cadaveric specimens were placed into a radiolucent apparatus that allowed controlled angulation of each foot at 0, 5, 10, 15, and 20 degrees in dorsiflexion, plantarflexion, inversion, and eversion. For each specimen, the first TMT joint angle (1TMTJA), shape of the distal articular surface of the medial cuneiform (flat or curved), and image quality of the first TMT joint were measured. Results: The mean value for 1TMTJA was 22.9 degrees (95% confidence interval [CI] 21.9-24). Individual anatomical variations of the specimens as well as the different angulations due to foot positioning significantly influenced the 1TMTJA (both P < .001). Joints that were found to have a flat configuration showed significantly increased 1TMTJA on average when compared to the ones with curved articular surface, 25.9 (95% CI 24.4-27.4) and 20.8 degrees (95% CI 19.5-22.0) ( P < .001), respectively. Image quality for visualization of the first TMT joint was progressively better for increased angles of dorsiflexion and inversion. Conclusion: The shape and angulation of the first TMT joint on radiographic evaluation are affected by the positioning of the foot. Clinical Relevance: Clinical usefulness of these radiographic characteristics is limited and should not influence operative planning in patients with possible instability of the first TMT joint.

The real Bigfoot: a pes from Wyoming, USA is the largest sauropod pes ever reported and the northern-most occurrence of brachiosaurids in the Upper Jurassic Morrison Formation

A set of associated left pedal elements of a sauropod dinosaur from the Upper Jurassic Morrison Formation in Weston County, Wyoming, is described here. Several camarasaurids, a nearly complete small brachiosaur, and a small diplodocid have been found at this locality, but none match the exceptionally large size of the pedal elements. Next to the associated pedal elements, an isolated astragalus, phalanx and ungual were found, which match the large metatarsals in size. The elements cannot be ascribed to diplodocids due to the lack of a ventral process of metatarsal I. Moreover, the morphology of metatarsal V has a broad proximal end, with a long and narrow distal shaft, which differs fromCamarasaurus. The size of the material and a medially beveled distal articular surface of metatarsal IV imply an identification as a brachiosaurid. This is the largest pes ever reported from a sauropod dinosaur and represents the first confirmed pedal brachiosaur elements from the Late Jurassic of North America. Furthermore, this brachiosaur material (the pes and the small nearly complete specimen) is the northernmost occurrence of brachiosaurids in the Morrison Formation.