A conservation palaeobiological perspective on Chesapeake Bay oysters.

The eastern oyster plays a vital role in estuarine habitats, acting as an ecosystem engineer and improving water quality. Populations of Chesapeake Bay oysters have declined precipitously in recent decades. The fossil record, which preserves 500 000 years of once-thriving reefs, provides a unique opportunity to study pristine reefs to establish a possible baseline for mitigation. For this study, over 900 fossil oysters were examined from three Pleistocene localities in the Chesapeake region. Data on oyster shell lengths, lifespans and population density were assessed. Comparisons to modern Crassostrea virginica, sampled from monitoring surveys of similar environments, reveal that fossil oysters were significantly larger, longer-lived and more abundant than modern oysters from polyhaline salinity zones. This pattern results from the preferential harvesting of larger, reproductively more active females from the modern population. These fossil data, combined with modern estimates of age-based fecundity and mortality, make it possible to estimate ecosystem services in these long-dead reefs, including filtering capacity, which was an order of magnitude greater in the past than today. Conservation palaeobiology can provide us with a picture of not just what the Chesapeake Bay looked like, but how it functioned, before humans. This article is part of a discussion meeting issue 'The past is a foreign country: how much can the fossil record actually inform conservation?'

Scandinavian Total Ankle Replacement: 15-Year Follow-up.

BACKGROUND: Over the past decade, total ankle arthroplasty (TAA) has become a mainstay in the treatment of end-stage ankle arthritis. Currently in its fourth generation, the Scandanavian Total Ankle Replacement (STAR) is the only 3-piece mobile bearing ankle prosthesis available in the United States. Our current study reports implant survivorship at 15 years and patient outcomes for a subset of these survivors available for study. METHODS: Eighty-four TAAs were performed between 1998 and 2000. Metal component survivorship at 15 years was calculated with a Kaplan-Meier curve. Twenty-four (29%) of 84 patients were available for participation with a minimum 15-year follow-up. Any radiographic changes were documented. All additional procedures and complications were recorded. Clinical findings, self-reported performance and pain evaluations, and AOFAS ankle/hindfoot scores were noted. RESULTS: Metal implant survival was 73% at 15 years. Of the 24 patients available for clinical evaluation, 18 of 24 patients (70.7%) had no change in prosthetic alignment from the immediate postoperative radiograph. Only 1 subtalar fusion was required for symptomatic adjacent joint arthritis. Three patients sustained a broken polyethylene component. AOFAS scores improved from an average of 39.6 points preoperatively, to an average of 71.6. More than half (52.4%) of patients with retained implants required an additional surgical procedure; 3 required 2 additional procedures. The average time to subsequent procedure was 10.2 years. CONCLUSION: Our small cohort demonstrated STAR ankles with retention at 9 years were highly likely to survive to 15 years, and patients continued to have significant improvement in pain relief and minimal decrease in function. At 15 years from TAA, metal survivorship was 73%. As with all ankle replacements, supplementary procedures were common. LEVEL OF EVIDENCE: Level IV, case series.

Redox reactions and weak buffering capacity lead to acidification in the Chesapeake Bay.

The combined effects of anthropogenic and biological CO2 inputs may lead to more rapid acidification in coastal waters compared to the open ocean. It is less clear, however, how redox reactions would contribute to acidification. Here we report estuarine acidification dynamics based on oxygen, hydrogen sulfide (H2S), pH, dissolved inorganic carbon and total alkalinity data from the Chesapeake Bay, where anthropogenic nutrient inputs have led to eutrophication, hypoxia and anoxia, and low pH. We show that a pH minimum occurs in mid-depths where acids are generated as a result of H2S oxidation in waters mixed upward from the anoxic depths. Our analyses also suggest a large synergistic effect from river-ocean mixing, global and local atmospheric CO2 uptake, and CO2 and acid production from respiration and other redox reactions. Together they lead to a poor acid buffering capacity, severe acidification and increased carbonate mineral dissolution in the USA's largest estuary.The potential contribution of redox reactions to acidification in coastal waters is unclear. Here, using measurements from the Chesapeake Bay, the authors show that pH minimum occurs at mid-depths where acids are produced via hydrogen sulfide oxidation in waters mixed upward from anoxic depths.

Millennial-scale sustainability of the Chesapeake Bay Native American oyster fishery.

Estuaries around the world are in a state of decline following decades or more of overfishing, pollution, and climate change. Oysters (Ostreidae), ecosystem engineers in many estuaries, influence water quality, construct habitat, and provide food for humans and wildlife. In North America's Chesapeake Bay, once-thriving eastern oyster (Crassostrea virginica) populations have declined dramatically, making their restoration and conservation extremely challenging. Here we present data on oyster size and human harvest from Chesapeake Bay archaeological sites spanning ∼3,500 y of Native American, colonial, and historical occupation. We compare oysters from archaeological sites with Pleistocene oyster reefs that existed before human harvest, modern oyster reefs, and other records of human oyster harvest from around the world. Native American fisheries were focused on nearshore oysters and were likely harvested at a rate that was sustainable over centuries to millennia, despite changing Holocene climatic conditions and sea-level rise. These data document resilience in oyster populations under long-term Native American harvest, sea-level rise, and climate change; provide context for managing modern oyster fisheries in the Chesapeake Bay and elsewhere around the world; and demonstrate an interdisciplinary approach that can be applied broadly to other fisheries.

Correction of moderate to severe coronal plane deformity with the STAR ankle prosthesis.

BACKGROUND: Prior studies have demonstrated a correlation between the degree of preoperative coronal plane deformity and failure following ankle replacement. We reviewed all of our patients who underwent ankle replacement utilizing the STAR prosthesis from 2000 to 2009 to evaluate the outcome of those with moderate (10 to 19 degrees) and severe (20 degrees or greater) coronal plane deformity. MATERIALS AND METHODS: Out of 130 consecutive patients, 43 patients had at least 10 degrees of preoperative coronal plane deformity. Twenty-five ankles had 10 to 19 degrees degrees of deformity and 18 ankles had 20 degrees or greater deformity. Average age was 66 years. Average length of followup was 41 (range, 12 to 98) months. RESULTS: Average talar preoperative deformity was 17.9 (range, 10 to 29) degrees, while average initial talar postoperative deformity was 3.5 (range, 0 to 12) degrees. Average final talar postoperative deformity was 4.7 (range, 0 to 14) degrees. Preoperative and final correction of deformity was statistically significant (p < 0.01), but there was no significant difference between initial and final postoperative correction. Overall, recurrence of the preoperative coronal plane deformity occurred in six of 43 patients (14%). All three patients who had deformities over 25 degrees developed recurrences. Correction of the coronal plane deformities was achieved by using intraoperative soft-tissue balancing, including deltoid ligament release in 12 patients and lateral ligament reconstruction in one patient. Deltoid ligament release was found to be necessary for all patients with greater than 18 degrees of varus plane deformity. CONCLUSION: Correction of moderate to severe coronal plane deformity with the STAR prosthesis was achievable with only soft-tissue balancing procedures with predictable results especially for deformities less than 25 degrees.

STAR™ ankle: long-term results.

BACKGROUND: There has been a resurgence of interest in total ankle replacement (TAR) due to improved results with newer prostheses. However, long-term survivorship data has been limited. The STAR™ Ankle prosthesis is the first three-part prosthesis approved for use in the United States. MATERIALS AND METHODS: Eighty-four total ankle replacements were performed in 80 patients using the STAR™ Ankle prosthesis and followed prospectively. Postoperatively, patients were evaluated with the AOFAS score for pain and function, and serial radiographs were evaluated for stability and alignment of the prosthesis. Implant failure, secondary procedures, and complications were recorded. RESULTS: Ninety-one percent of prostheses remain implanted at an average followup of 9.1 years. The probability of implant survival was 96% at 5 years and 90% at 10 years. An average 39-point improvement in the AOFAS ankle-hindfoot score was noted, from a mean of 43 to a mean of 82 points. We noted a statistically significant increase in both average pain and function sub-scores. Postoperative range of motion averaged 4.5 degrees of dorsiflexion and 35 degrees of plantarflexion. Ninety-two percent of the patients were satisfied with their outcome. Ten patients (13%) developed concerning osteolytic lesions. Change in prosthetic alignment and adjacent joint arthritis were similar to previous reports. We report 21 complications, which included 14 additional surgical procedures. CONCLUSION: The first U.S. prospective long-term survivorship data with the STAR™ Ankle prosthesis found it to be an excellent long-term option for the treatment of ankle arthritis.

Reconstructing early 17th century estuarine drought conditions from Jamestown oysters.

Oysters (Crassostrea virginica) were a central component of the Chesapeake Bay ecosystem in 1607 when European settlers established Jamestown, VA, the first permanent English settlement in North America. These estuarine bivalves were an important food resource during the early years of the James Fort (Jamestown) settlement while the colonists were struggling to survive in the face of inadequate supplies and a severe regional drought. Although oyster shells were discarded as trash after the oysters were eaten, the environmental and ecological data recorded in the bivalve geochemistry during shell deposition remain intact over centuries, thereby providing a unique window into conditions during the earliest Jamestown years. We compare oxygen isotope data from these 17th century oyster shells with modern shells to quantify and contrast estuarine salinity, season of oyster collection, and shell provenance during Jamestown colonization (1609-1616) and the 21st century. Data show that oysters were collected during an extended drought between fall 1611 and summer 1612. The drought shifted the 14 psu isohaline above Jamestown Island, facilitating individual oyster growth and extension of oyster habitat upriver toward the colony, thereby enhancing local oyster food resources. Data from distinct well layers suggest that the colonists also obtained oysters from reefs near Chesapeake Bay to augment oyster resources near Jamestown Island. The oyster shell season of harvest reconstructions suggest that these data come from either a 1611 well with a very short useful period or an undocumented older well abandoned by late 1611.

Prospective controlled trial of STAR total ankle replacement versus ankle fusion: initial results.

BACKGROUND: Mobile-bearing ankle replacements have become popular outside of the United States over the past two decades. The goal of the present study was to perform a prospective evaluation of the safety and efficacy of a mobile-bearing prosthesis to treat end stage ankle arthritis. We report the results of three separate cohorts of patients: a group of Scandanavian Total Ankle Replacement (STAR) patients and a control group of ankle fusion patients (the Pivotal Study Groups) and another group of STAR total ankle patients (Continued Access Group) whose surgery was performed following the completion of enrollment in the Pivotal Study. MATERIALS AND METHODS: The Pivotal Study design was a non-inferiority study using ankle fusion as the control. A non-randomized multi-centered design with concurrent fusion controls was used. We report the initial perioperative findings up to 24 months following surgery. For an individual patient to be considered an overall success, all of the following criteria needed to be met: a) a 40-point improvement in total Buechel-Pappas ankle score, b) no device failures, revisions, or removals, c) radiographic success, and d) no major complications. In the Pivotal Study (9/00 to 12/01), 158 ankle replacement and 66 arthrodesis procedures were performed; in the Continued Access Study (4/02 to 10/06), 448 ankle replacements were performed, of which 416 were at minimum 24 months post-surgery at time of the database closure. RESULTS: Major complications and need for secondary surgical intervention were more common in the Pivotal Study arthroplasty group than the Pivotal Study ankle fusion group. In the Continued Access Group, secondary procedures performed on these arthroplasty patients decreased by half when compared with the Pivotal Arthroplasty Group. When the Pivotal Groups were compared, treatment efficacy was higher for the ankle replacement group due to improvement in functional scores. Pain relief was equivalent between fusion and replacement patients. The hypothesis of non-inferiority of ankle replacement was met for overall patient success. CONCLUSION: By 24 months, ankles treated with STAR ankle replacement (in both the Pivotal and Continued Access Groups) had better function and equivalent pain relief as ankles treated with fusion.

Osteoarthritis of the ankle: the role of arthroplasty.

Total ankle arthroplasty was developed to reduce pain and retain motion of the ankle joint in patients with osteoarthritis. The ankle joint has unique, complex anatomic and biomechanical characteristics that must be considered in a successful total ankle arthroplasty prosthesis. Initial designs from the 1960s to the 1970s had many failures. Current designs use two or three components, and recent reports on total ankle arthroplasty show consistent good to excellent intermediate clinical results, with up to 90% decreased pain and high patient satisfaction. The follow-up time of these studies is limited, however, and long-term studies with 10- to 15-year follow-ups are needed. Also, a wide variety of complications has been reported, including osteomyelitis and osteolysis. To limit the number of complications and improve clinical outcome of total ankle arthroplasty, careful patient selection and surgeon experience are important.

Stress fracture as a complication of autogenous bone graft harvest from the distal tibia.

BACKGROUND: Autogenous bone graft from the distal tibia provides cancellous bone graft for foot and ankle operations, and it has osteogenic and osteoconductive properties. The site is in close proximity to the foot and ankle, and published retrospective studies show low morbidity from the procedure. METHODS: One-hundred autografts were obtained from the distal tibia between 2000 and 2003. In four cases the distal tibial bone graft harvest resulted in a stress fracture. There were three women and one man. RESULTS: The average time of diagnosis of the stress fracture from the operation was 1.8 months. All stress fractures healed with a short course (average 2.4 months) of cast immobilization. CONCLUSIONS: This study demonstrated that a stress fracture from the donor site of autogenous bone graft of the distal tibia occurs and can be successfully treated nonoperatively.

Subtalar joint arthrodesis using a single lag screw.

BACKGROUND: This study tested the hypotheses that fusing the subtalar joint with a single lag screw from the posteroinferior calcaneus to the anterior talar neck is an effective technique and that factors affecting the time to fusion can be identified. METHODS: Between October, 1995, and July, 2002, the senior author (RAM) performed 101 isolated subtalar arthrodeses using a technique of single lag-screw fixation from posteroinferior to anterosuperior across the posterior facet of the subtalar joint combined with the application of an autograft taken from the floor of the sinus tarsi and anterior process. The average patient age was 52 (range 17 to 82) years. There were 52 women (53 arthrodeses) and 48 men (48 arthrodeses). Eight of 101 (8%) arthrodeses were revisions. The indications included posttraumatic arthritis (45), posterior tibial tendon dysfunction (18), failed prior ankle joint fusion (14), idiopathic disorders (12), hindfoot coalition (7), rheumatoid arthritis (3), and Charcot-Marie-Tooth disease (2). Fifteen of 101 patients (15%) smoked an average of 0.9 +/- 0.5 pack of cigarettes per day. RESULTS: Two of 101 joints did not fuse, resulting in an overall fusion rate of 98%. The average time to fusion was 12.3 +/- 3.4 weeks. The presence of a prior ankle fusion significantly prolonged the time to fusion of the subtalar joint (11.9 +/- 2.3 vs. 14.9 +/- 7.0, p = .003). Other factors, including smoking, revision surgery, patient age, and patient sex, did not affect time to fusion. The fixation screw was removed in 13 of 101 (13%) joints at an average of 8.8 +/- 0.5 months. CONCLUSIONS: Using a single 7.0-mm lag screw across the posterior facet of the subtalar joint results in fusion of the subtalar joint in 98% of patients. A prior ankle arthrodesis delays the time to fusion of the subtalar joint by 3 weeks. This is a simple and reliable technique for achieving fusion of the subtalar joint.

Ankle arthroplasty with preoperative coronal plane deformity: short-term results.

The treatment of coronal plane deformity during total ankle arthroplasty is understood poorly. This study tests the hypotheses that preoperative coronal plane malalignment and incongruence of the ankle can be corrected and maintained for 2 years with total ankle replacement, and that factors can be identified that place ankles at risk of having progressive edge-loading develop. Of 86 consecutive patients who had total ankle replacement, 35 had preoperative coronal plane alignment > or =10 degrees. Lateral ligament reconstruction was done in seven patients and superficial deltoid release was done in four patients at the time of ankle replacement. Ankles with talar and tibial deformities improved talar and tibial alignment toward a neutral weightbearing axis postoperatively. Ankles with only a talar deformity improved the talar alignment toward a neutral weightbearing axis postoperatively. No changes in alignment were shown during the subsequent 2 years. Postoperative ankle articulations were congruent. Patients with preoperative incongruent joints are 10 times more likely to have progressive edge-loading develop than patients with congruent joints. Surgeons must be attentive to coronal plane alignment during and after ankle replacement. Longer followup is needed to assess the longevity of the correction and the impact of minor malalignment on implant wear.

Functional evaluation of the Scandinavian Total Ankle Replacement.

The purpose of this study was to evaluate the function of the ankle joint during walking before and after Scandinavian Total Ankle Replacement (STAR). Nine patients (six males and three females) with an average age of 65 years, scheduled for unilateral total ankle replacement for osteoarthritis and rheumatoid arthritis, were evaluated both preoperatively and postoperatively in a gait analysis laboratory. Arthroplasty patients showed reduced range of motion at the ankle compared to normal controls. Postoperative arthroplasty subjects had significantly improved external ankle dorsiflexion moment, the moment that affects the plantarflexor muscles, when compared to their preoperative status. The moment in arthroplasty patients was increased, indicating improved function of the ankle joint.

Perioperative complication rate of total ankle replacement is reduced by surgeon experience.

BACKGROUND: Recent studies suggest the perioperative complication rate of total ankle arthroplasty decreases as a surgeon becomes familiar with the procedure. This study tests the hypothesis that the number of perioperative adverse events will decrease as surgeon experience with total ankle replacement increases. METHODS: Ten surgeons completed retrospective chart and radiographic reviews of their first 10 cases as well as 10 subsequent cases of the Scandinavian Total Ankle Replacement (STAR). Not all surgeons completed 10 cases within the allotted time periods, and two patients were excluded for less than 3-month follow-up, resulting in 187 cases for review. The surgeons performed an average of 12.8 (range, 0-61) STARs between these two time periods. Cases were divided into Early Group if they were among the first five STARs a surgeon performed and Late Group if they were after the first five. RESULTS: The average patient age was 60.4 +/- 12.8 years. The etiology of arthrosis included 96 (51%) of 187 posttraumatic, 49 (26%) idiopathic, and 33 (18%) rheumatoid. Patients in Early Group had a 3.1 times greater chance of having a perioperative adverse event (95% CI 1.6-6.1, p <.001), and a 3.2 times greater chance of having a perioperative wound problem (95% CI 1.5-6.8, p =.002) than patients in Late Group. Patients in Early Group took 1 week longer to heal their wounds than patients in Late Group (4.5 vs. 3.5 weeks, p =.046). CONCLUSIONS: This study shows a decrease in the perioperative adverse event rate commensurate with surgeon experience with STAR. In contrast to other reports, this study was unable to show a decrease in the number of perioperative fractures with increasing surgeon experience. This information is important for planning how best to train surgeons new to total ankle replacement and for patient counseling regarding the potential risks of the procedure.

Keratotic disorders of the plantar skin.

Keratotic lesions on the plantar aspect of the foot develop beneath an osseous prominence and can result in substantial disability. This occurs because, during normal gait, the metatarsal head area is subjected to more prolonged stress than any other area on the plantar aspect of the foot. In the treatment of this disorder, it is imperative to establish the etiology, among many possibilities, and then address the specific pathology accordingly.

The bunionette deformity.

The bunionette deformity results in pain about the lateral and/or the plantar aspect of the fifth metatarsal head. It is important to carefully assess the deformity anatomically in order to select the proper surgical procedure to correct this painful affliction. Knowledge of pathoanatomy and certain surgical procedures can be used to correct the deformity.

A review of rheumatoid arthritis affecting the foot and ankle.

Rheumatoid arthritis is a systemic disease that often affects the foot and ankle. Approximately 20% of patients with rheumatoid arthritis present initially with foot and ankle symptoms, and most patients will eventually develop foot and ankle symptoms. Although early intervention includes conservative measures, operative treatment often is needed to adequately treat rheumatoid patients. Treatment of foot and ankle problems in patients with rheumatoid arthritis is directed to maintaining ambulatory capacity. This article reviews the clinical presentation, evaluation, and treatment of rheumatoid arthritis affecting the foot and ankle.