Learning the moves: the effect of familiarity and facial motion on person recognition across large changes in viewing format.

Familiarity with a face or person can support recognition in tasks that require generalization to novel viewing contexts. Using naturalistic viewing conditions requiring recognition of people from face or whole body gait stimuli, we investigated the effects of familiarity, facial motion, and direction of learning/test transfer on person recognition. Participants were familiarized with previously unknown people from gait videos and were tested on faces (experiment 1a) or were familiarized with faces and were tested with gait videos (experiment 1b). Recognition was more accurate when learning from the face and testing with the gait videos, than when learning from the gait videos and testing with the face. The repetition of a single stimulus, either the face or gait, produced strong recognition gains across transfer conditions. Also, the presentation of moving faces resulted in better performance than that of static faces. In experiment 2, we investigated the role of facial motion further by testing recognition with static profile images. Motion provided no benefit for recognition, indicating that structure-from-motion is an unlikely source of the motion advantage found in the first set of experiments.

Periacetabular osteotomy in the treatment of severe acetabular dysplasia. Surgical technique.

BACKGROUND: The optimal treatment of severe acetabular dysplasia with subluxation of the femoral head or the presence of a secondary acetabulum remains controversial. The purpose of this study was to analyze the extent of surgical correction and the early clinical results obtained with the Bernese periacetabular osteotomy for the treatment of severely dysplastic hips in adolescent and young adult patients. METHODS: Sixteen hips in thirteen patients with an average age of 17.6 years (range, 13.0 to 31.8 years) were classified as having severe acetabular dysplasia (Group IV or V according to the Severin classification). Eight hips were classified as subluxated, and eight had a secondary acetabulum. Preoperatively, all patients had hip pain and sufficient hip joint congruency on radiographs to be considered candidates for the osteotomy. All sixteen hips underwent a Bernese periacetabular osteotomy, and six of them underwent a concomitant proximal femoral osteotomy. Postoperatively, the hips were assessed radiographically to evaluate correction of deformity, healing of the osteotomy site, and progression of osteoarthritis. Clinical results and hip function were measured with the Harris hip score at an average of 4.2 years postoperatively. RESULTS: Comparison of preoperative and follow-up radiographs demonstrated an average improvement of 44.6 degrees (from -20.5 degrees to 24.1 degrees) in the lateral center-edge angle of Wiberg, an average improvement of 51.0 degrees (from -25.4 degrees to 25.6 degrees) in the anterior center-edge angle of Lequesne and de Seze, and an average improvement of 25.9 degrees (from 37.3 degrees to 11.4 degrees) in acetabular roof obliquity. The hip center was translated medially an average of 10 mm (range, 0 to 31 mm). All iliac osteotomy sites healed. The average Harris hip score improved from 73.4 points preoperatively to 91.3 points at the time of the latest follow-up. Eleven of the thirteen patients (fourteen of the sixteen hips) were satisfied with the result of the surgery, and fourteen hips had a good or excellent clinical result. Major complications included loss of acetabular fixation, which required an additional surgical procedure, in one patient and overcorrection of the acetabulum and an associated ischial nonunion in another patient. Both patients had a good clinical result at the time of the latest follow-up. There were no major neurovascular injuries or intra-articular fractures. CONCLUSIONS: The periacetabular osteotomy is an effective technique for surgical correction of a severely dysplastic acetabulum in adolescents and young adults. In this series, the early clinical results were very good at an average of 4.2 years postoperatively; the two major complications did not compromise the good clinical results.

Periacetabular osteotomy for the treatment of severe acetabular dysplasia.

BACKGROUND: The optimal treatment of severe acetabular dysplasia with subluxation of the femoral head or the presence of a secondary acetabulum remains controversial. The purpose of this study was to analyze the extent of surgical correction and the early clinical results obtained with the Bernese periacetabular osteotomy for the treatment of severely dysplastic hips in adolescent and young adult patients. METHODS: Sixteen hips in thirteen patients with an average age of 17.6 years (range, 13.0 to 31.8 years) were classified as having severe acetabular dysplasia (Group IV or V according to the Severin classification). Eight hips were classified as subluxated, and eight had a secondary acetabulum. Preoperatively, all patients had hip pain and sufficient hip joint congruency on radiographs to be considered candidates for the osteotomy. All sixteen hips underwent a Bernese periacetabular osteotomy, and six of them underwent a concomitant proximal femoral osteotomy. Postoperatively, the hips were assessed radiographically to evaluate correction of deformity, healing of the osteotomy site, and progression of osteoarthritis. Clinical results and hip function were measured with the Harris hip score at an average of 4.2 years postoperatively. RESULTS: Comparison of preoperative and follow-up radiographs demonstrated an average improvement of 44.6 degrees (from -20.5 degrees to 24.1 degrees ) in the lateral center-edge angle of Wiberg, an average improvement of 51.0 degrees (from -25.4 degrees to 25.6 degrees ) in the anterior center-edge angle of Lequesne and de Seze, and an average improvement of 25.9 degrees (from 37.3 degrees to 11.4 degrees ) in acetabular roof obliquity. The hip center was translated medially an average of 10 mm (range, 0 to 31 mm). All iliac osteotomy sites healed. The average Harris hip score improved from 73.4 points preoperatively to 91.3 points at the time of the latest follow-up. Eleven of the thirteen patients (fourteen of the sixteen hips) were satisfied with the result of the surgery, and fourteen hips had a good or excellent clinical result. Major complications included loss of acetabular fixation, which required an additional surgical procedure, in one patient and overcorrection of the acetabulum and an associated ischial nonunion in another patient. Both patients had a good clinical result at the time of the latest follow-up. There were no major neurovascular injuries or intra-articular fractures. CONCLUSIONS: The periacetabular osteotomy is an effective technique for surgical correction of a severely dysplastic acetabulum in adolescents and young adults. In this series, the early clinical results were very good at an average of 4.2 years postoperatively; the two major complications did not compromise the good clinical results.

Medial translation of the hip joint center associated with the Bernese periacetabular osteotomy.

This study assessed medial translation of the hip joint achieved by the Bernese periacetabular osteotomy (PAO) in correcting residual acetabular dysplasia deformities. 86 hips in 75 patients with an average age of 25 years (range, 12-50) were treated for symptomatic acetabular dysplasia with a periacetabular osteotomy. Radiographic analysis was performed to assess correction of the acetabular deformity with specific attention to the horizontal position of the hip joint center. All hips were followed until bony union of the iliac osteotomy and the average follow-up was 28 months. The lateral center edge angle improved an average 31.6 degrees (-0.4 degrees preoperative, 31.2 degrees at follow-up). The anterior center edge angle improved 39.3 degrees (-4.5 degrees to 34.8 degrees). The acetabular roof obliquity improved an average 21.8 degrees (25.1 degrees to 3.3 degrees). Preoperatively, the average distance from the medial aspect of the femoral head to the ilioischial line was 17.6 mm. This distance was decreased to an average 7.8 mm postoperatively. This change resulted in an average medial translation of the hip joint center of 9.8 mm, (range -6 to 31mm). Overall, some degree of medial translation of the hip joint center was obtained in 79 (92%) of the hips. Four (5%) were maintained in the same horizontal position, and 3 (3%) had slight lateral repositioning. For the hips translated medially, the average change was 10.0 mm, and 72% of all hips had an optimal correction with the distance between the medial aspect of the femoral head and the ilioischial line being between 0 and 10 mm. This study demonstrates that in addition to optimizing femoral head coverage, a major and distinct advantage of the periacetabular osteotomy is reproducible and consistent medial translation of the hip joint center.

A protocol for treatment of unstable ankle fractures using transarticular fixation in patients with diabetes mellitus and loss of protective sensibility.

BACKGROUND: Surgical treatment of ankle fractures in patients with diabetes mellitus is associated with a high complication rate. Diabetic patients with peripheral neuropathy are a particularly difficult group to treat because of their inability to sense deep infection, repeat trauma, and wound complications. The purpose of this study was to evaluate a protocol that included transarticular fixation and prolonged, protected weightbearing in the treatment of unstable ankle fractures in diabetic patients with peripheral neuropathy and loss of protective sensibility. METHODS: The authors retrospectively reviewed the records of 15 patients with diabetes mellitus, unstable ankle fractures (AO classification 44B), and loss of protective sensibility confirmed via testing with a 5.07 Semmes-Weinstein monofilament. Retrograde transcalcaneal-talar-tibial fixation using large Steinmann pins or screws in conjunction with standard techniques of open reduction and internal fixation was used. The postoperative treatment protocol included: 1) short leg, total contact casting and nonweightbearing status for 12 weeks; 2) removal of the intramedullary implants between 12 and 16 weeks; 3) application of a walker boot or short leg cast with partial weightbearing for an additional 12 weeks; and 4) transition to a custom-molded ankle-foot orthosis (AFO) or custom total-contact inserts in appropriate diabetic footwear. RESULTS: The major complication rate for all fractures was 25% (4/16) and for closed fractures was 23% (3/13). These are lower than previously reported rates between 30% (3/10) and 43% (9/21) for diabetic patients with and without neuropathy. The amputation rate for all fractures was 13% (2/16) and for closed fractures alone was 8% (1/13). These are similar to previously reported rates of 10% (2/10) to 20% (2/21). There were no deaths or Charcot malunions in this series. The combination of transarticular fixation and prolonged, protected weightbearing provided 13 of 15 patients with a stable ankle for weightbearing. CONCLUSION: Although these fractures remain a treatment challenge, this study presents a successful, multidisciplinary protocol for treatment of unstable ankle fractures in the most challenging group of diabetic patients - those with loss of protective sensibility.

Psychological and neural perspectives on the role of motion in face recognition.

In the real world, faces are in constant motion. Recently, researchers have begun to consider how facial motion affects memory for faces. The authors offer a theoretical framework that synthesizes psychological findings on memory for moving faces. Three hypotheses about the possible roles of facial motion in memory are evaluated. In general, although facial motion is helpful for recognizing familiar/famous faces, its benefits are less certain with unfamiliar faces. Importantly, the implicit social signals provided by a moving face (e.g., gaze changes, expression, and facial speech) may mediate the effects of facial motion on recognition. Insights from the developmental literature, which highlight the significance of attention in the processing of social information from faces, are also discussed. Finally, a neural systems framework that considers both the processing of socially relevant motion information and static feature-based information is presented. This neural systems model provides a useful framework for understanding the divergent psychological findings.