Aims. Fracture-Related Infection (FRI) is a severe complication caused by microbial infection of bone. It is imperative to gain more insight into the potentials and limitations of Debridement, Antibiotics and Implant Retention (DAIR) to improve future FRI treatment. The aims of this study were to: 1) determine how time to surgery affects the success rate of DAIR procedures of the lower leg performed within 12 weeks after the initial fracture fixation operation and 2) evaluate whether appropriate systemic antimicrobial therapy affects the success rate of a DAIR procedure. Methods. This multinational retrospective cohort study included patients of at least 18-years of age who developed an FRI of the lower leg within 12 weeks after the initial fracture fixation operation, between January 1st 2015 to July 1st 2020. DAIR success was defined by the absence of recurrence of infection, preservation of the affected limb and retention of implants during the initial treatment. The antimicrobial regimen was considered appropriate if the pathogen(s) was susceptible to the given treatment at the correct dose as per guideline. Logistic regression modelling was used to assess factors that could contribute to the DAIR success rate. Results. A total of 120 patients were included, of whom 70 DAIR patients and 50 non-DAIR patients. Within a median follow-up of 35.5 months, 21.4% of DAIR patients developed a recurrent FRI compared to 12.0% of non-DAIR patients. The DAIR procedure was successful in 45 patients (64.3%). According to the Willenegger and Roth classification, DAIR success was achieved in 66.7% (n=16/24) of patients with an early infection (<2 weeks), 64.4% (n=29/45) of patients with a delayed infection (2–10 weeks) and 0.0% (0/1) of patients with a late infection (>10 weeks). Univariate analysis showed that the duration of infection was not associated with DAIR success in this cohort (p=0.136; OR: 0.977; 95%CI: [0.947–1.007]). However, an appropriate antimicrobial regimen was associated with success of DAIR (p=0.029; OR: 3.231; 95%CI: [1.138–9.506]). Conclusions. Although the results should be interpreted with caution, an increased duration of infection was not associated with a decreased success rate of a DAIR procedure in patients with FRI of the lower leg. The results of this study highlight the multifactorial contribution to the success of a DAIR procedure and emphasize the importance of adequate antimicrobial treatment. Therefore, time to surgery should not be the only key-factor when considering a DAIR procedure to treat FRI

Compartment pressures have not previously been studied in healthy children. We compared the pressures in the four lower leg compartments of healthy children with those of healthy adults. We included patients aged between two months and six years, and measured the pressures in 80 compartments of 20 healthy children using simple needle manometry. Measurements were repeated in a control group of 20 healthy adults. The mean compartment pressure in the lower leg in children was significantly higher than in adults (p < 0.001). On average, pressures in the four compartments varied between 13.3 mmHg and 16.6 mmHg in the children and between 5.2 mmHg and 9.7 mmHg in the adults. The latter is in accordance with those recorded in the literature. The mean arterial pressure did not relate to age or to pressure in the compartment. The findings of this study that the normal compartment pressure of the lower leg in healthy children is significantly higher than that in adults may be of considerable significance in clinical decision-making in children of this age

Reimplantation is a well-established procedure in reconstructive surgery. This is especially so after amputation of the upper limb since prostheses provide limited function. In unilateral amputation of the lower leg orthotopic reimplantation is the treatment of choice. With bilateral amputation, in which orthotopic reimplantation is not possible because of the complexity of the trauma, heterotopic reimplantation is an option. We report five patients who received orthotopic and two who received heterotopic reimplantations of the lower leg. We assessed the functional outcome with reference to cutaneous sensation, mobility, pain, and the cosmetic result. The functional outcome was good, as was the patients’ satisfaction. Their mobility, stability, and psychological state were satisfactory. Patients with heterotopic reimplantations preferred the reimplanted leg to a prosthesis. Although reimplantation of the lower leg requires prolonged hospitalisation, delayed mobilisation and secondary operations, we conclude that there is an indication for this operation in order to improve the patient’s quality of life

Background and Objectives. There are various classifications to assess the degree of open fracture and each has it’s own advantages and disadvantages. We proposed a new system since we couldn’t find any which was simple, objective, reliable, reproducible and applicable in an emergency setting. We set five variables namely, skin break, bone damage, muscle injury, neurovascular impairment and the degree of contamination to make scoring. We needed to know if the proposed classification had a better reliability, was simple, objective and applicable. Design and Setting. A proposed diagnostic testing was set to better classifying the degree and severity open fractures. Every patient with open lower leg fracture was classified with the proposed Sardjito Scoring System. The residents on duty, medical students and nurse staffs were then asked to classify them with the proposed scoring Gustilo system . The debridement reports were used to be the standard as a comparison of the classification made by the residents, medical student and nurse staffs. Main Outcome Measurements. The classifications made by the residents, medical students and nurses were compared with the finding during the debridement to measure their reliability with kappa coefficient, sensitivity, specivity and accuracy. Results. We had 40 patients with open lower leg fracture. We found exelent reliability among the residents, medical students, and nurses (k: 0.86 p: 0.000). Conclusion. The proposed Sardjito Scoring system of the open lower leg fracture was so far reliable, making it reproducible and applicable

Aim. Soft tissue defects of the lower leg can be closed - following the reconstructive ladder - with a pediculated fasciocutaneous suralis flap, but a free flap is gold standard in most of the cases. Aim of the study was to evaluate complications, risk factors for failure and the reasonableness of this procedure. Method. 91 patients (92 flaps, 70 males, 21 females) with a mean Age of 55 years (16 to 87) were included in the study. The patients had mean four surgical procedures before the flap, the follow-up was mean 407 days. 70 patients were classified ASA I or ASA II. Results. There were many complications, mostly wound healing Problems or hematoma. Only 40% of the patients received no Revision surgery, 71% of the flaps reached healing with Maximum two revisions (22% with one, 9% with two revisions, respectively). Necrectomy and new meshgraft were main reasons for Revision. Long term complications were swelling or disturbance of sensitivity. We lost seven flaps, eight free flaps were necessary. Three amputations were performed, but only one because of the lost flap. Conclusions. All patients with lost flaps showed relevant comorbidities. 71% of the flaps healed with Maximum two revisions and the overall flap loss rate was 6%. The Advantages of this flap are short surgery time without the need of a microvascular anastomosis and a relatively simple surgical technique. The flap loss rate of 6% seems to be acceptable and, however, the flap is a good Option and an important step of the reconstructive ladder for soft tissue defect closure of the lower leg

Introduction. Lower limb immobilisation with full casts is commonly used to manage fractures. There may be the need to split casts in an emergency, such as compartment syndrome, with no current consensus as to which technique is most effective in reducing pressure quickly. Our study aims to compare the reduction in pressure across lower leg compartments using three different cast splitting techniques. Methods. This study was done on a volunteer doctor. Pressure sensors were positioned at the anterior, posterior and lateral compartments. A single plaster technician applied below knee full casts with sequential layering and were allowed to dry as per manufacture instructions. Cast were split utilising three splitting methods; bivalve, tramline and single split and measurements taken when each layer was split. We compared results of ten repetitions for each splitting technique. Results. When the cast was initially cut there were significant reduction in pressure with the bivalve split (20.6 ± 0.76 N) when compared to both the single split (26.8 ± 1.13 N, P < 0.001) and tramline split (26.4 ± 0.90 N, P < 0.001). When the cast was spread there were significant reduction in pressure with the bivalve split (10.7 ± 0.83 units) when compared to both the single split (14.6 ± 0.85 N, P < 0.001) and tramline split (16.6 ± 0.77 N, P < 0.001). When the final layer of wool was released the pressure remained lower (statistically significant) in the bivalve split compared to both single split and tramline split. Conclusion. Our study demonstrates that bivalve cast splitting provided a more rapid reduction in pressure compared to other techniques across all three compartments. Our data shows that once down to skin, bivalve splitting continues to provide the lowest pressure compared to the other techniques. We recommend utilising bivalve when splitting a cast in an emergency

Aims: Our purpose was to evaluate þnal results of the fasciotomy of the lower leg in athletes, who were treated surgically for their chronic compartment syndromes. Methods: 339 consecutive patients were operated during years 1985 Ð 2000. A total number of 631 fasciotomies were done. In the retrospective patient series the results were analyzed by athletes´ ability to train and compete maximally. When maximal performances were possible without any pain the result was good, if they had some pain and light difþculties with maximal trainng, the result was moderate, and if they were not able to train normally or had pains during it the result was poor. The adequate end result (from 6 months to 12 years) was obtained from 91% of the patients. Results: The athletes represented following sports:endurance sports (endurance and middle distance running, orienteering, cross country skiing, triathlon, walking) 73%, sprinting, hurdling and jumping 18%, ball sports 4%, power and contact sports 3% and other sports 2%. The overall results of fasciotomy were good in 72%, moderate in 23%, and poor in 5% of the operated cases. Best results were obtained with anterior and posterior compartment syndromes. Complications were seen in 44 fasciotomies. One third of them affected with the end result. Reoperation due to the failure of the þrst fasciotomy or due to recurrent new compartment syndrome at the same compartment was performed in 39 cases. Conclusions: Chronic lower leg pains require sometimes fasciotomy. The operation gives usually good or moderate results. Athletes, who before the surgery were not able to train normally, could increase their training level to maximal or near to it

Aim. Since surgical site infections (SSIs) remain among the most common complications of orthopedic (trauma) surgery, there has been unwavering attention for potential predictors of a SSI. Specifically in surgical fields with a high complication rate, such as foot/ankle surgery, risk factor identification is of great importance. Recently, some studies have suggested environmental factors such as season to be of influence on the number of SSI. Specifically patients operated on in the summer are reported to have a higher incidence of SSIs, compared to other seasons. The aim of this study is to identify if “seasonality” is a significant predictor for SSI in a cohort of (trauma) surgical foot and ankle procedures. Method. This retrospective cohort study included all patients undergoing trauma related surgery (fracture fixation, arthrodesis, implant removal and tendon repair) of the lower leg, ankle and foot. Procedures were performed at a single Level 1 Trauma Center in the Netherlands between September 2015 until February 2019. Potential risk factors/ confounders for SSI were identified using univariate analysis (Chi-Square/Mann-Whitney U). Procedures were divided in two groups: 1) performed in summer (June, July or August), 2) not performed in summer (September-May). The number of SSIs was compared between the 2 groups, correcting for confounders, using multivariate regression. Results. A total of 605 procedures were included, largely fracture fixation (371, 61.2%). Patients were on average 46 y/o and the majority was male (369, 60.9%). The total number of SSIs was 34 (5.6%). Age, American Society of Anesthesiologists (ASA) classification (1–2 or 3–4) and open fractures were identified as possible predicting factors of SSI. No difference in SSIs was found between summer and other seasons, neither in univariate analysis (4 (3.2%) vs 30 (6.3%), p=0.271), nor when corrected for confounders. Moreover, in multivariate analysis only an ASA of >2 and an open fracture remained as independent predictors of SSI. Conclusions. No seasonality could be identified in the rate of SSI after trauma surgery of the lower leg, ankle and foot in this cohort. A possible explanation for this lack of effect could be the temperate oceanic climate of the Netherlands. Larger temperature and precipitation differences may also influence the incidence of SSIs. However, previous studies suggesting seasonality in SSIs might also be purely based on coincidence, especially when uncorrected for confounders

Ulceration of the lower leg is considered to be a ‘hard’ clinical endpoint of venous thrombosis. Total knee replacement (TKR) is a significant risk factor for venous thrombosis of the leg and therefore potentially for ulceration. We sent a postal questionnaire to 244 patients at a minimum of five years after TKR enquiring about the development of ulceration since their TKR. The overall incidence of ulceration, both active and healed, was 8.67% which is similar to that in the age-matched general population (9.6% to 12.6%), as was the prevalence of active ulceration. We also identified no clear association between venographically-confirmed postoperative deep-venous thrombosis (DVT) and the incidence and prevalence of ulcers at five years. We suggest that after TKR DVT is not a significant risk factor for ulceration of the leg and that perioperative chemical thromboprophylaxis may not be justified on these grounds

The aetiology of pain in the lower leg during exercise has been studied in 110 athletes by monitoring intracompartmental pressure during exercise and by technetium bone scans. Patients were assigned to three diagnostic groups: chronic compartment syndrome, medial tibial syndrome and those with non-specific findings. Our results indicate that subcutaneous fasciotomy of the affected compartment(s) is the treatment of choice for chronic compartment syndrome. The treatment of patients with medial tibial syndrome, either by operation or conservatively, has been unsuccessful; non-specific symptoms have been treated conservatively with success

Aims: Only gangrene of the entire foot and life-threatening sepsis with severe infection require a high amputation. Method: Between 1984 and 1999, 188 amputations in the area of the lower extremity were carried out at Bad Düben specialist hospital for orthopaedics. In 31 cases, partial amputation (so-called amputation of border zones) was required in the area of the foot owing to diabetic foot syndrome. The medical records were analysed and the patients who were still living underwent a follow-up examination; 8 patients had died. Results: Of the 31 patients, 20 were men and 11 were women. From 1982 to 1987 there were 4 partial amputations of the foot, from 1988 to 1993 there were 12 and from 1994 to 1999 there were 11. The average age was 69.1 years. In 11 cases, amputation of the lower leg as a subsequent operation was necessary. Here the average age was 71,8 years. It was noted that from 1994 to 2001 subsequent amputation of the lower leg had only been required twice (eight times from 1984 to 1993). The patients who underwent a follow-up examination were satisfied after partial amputation of the foot. Conclusions: For diabetic feet with neuropathy and infection, partial amputation of the foot can be regarded as the treatment of choice. Prompt referral to hospital is necessary to ensure optimum glucose adjustment and any treatment required for accompanying diseases. With interdisciplinary management between the physician, vascular surgeon and orthopaedist, and with treatment in a team with the orthopaedic shoemaker, in addition to surgical measures, we the necessary local can prevent gangrene of the entire foot and life-threatening sepsis from leading to a high amputation

Purpose of the study: Locked centromedullary nailing has proven efficacy for the treament of tibial shaft fractures but its use remains controversial for the most distal fractures. The purpose of this work was to assess clinical and radiological outcome of nailing procedures used to treat fractures of the lower quarter of the leg.

Material and methods: Fifty-eight fractures of the lower quarter of the leg were treated by locked centromedul-lary nailing between 1999 and 2002. All patients were included in the analysis. Twenty-four patients aged 44 years on average (range 18–68 years) were reviewed by an independent operator at mean 43.2 months follow-up (range 18–70). Four types of nail were used, on an orthopedic table for 47 procedures and with a hanging leg for 11. The fibula was not fixed.

Results: Early complications were: compartment syndrome (n=2) and infection (n=3). Postoperative alignment was anatomic or good in 86%. Mean time to weight bearing was 66 days (range 0–180). Nonunion occurred in six patients who required revision. Secondary displacement was noted in ten patients. Knee motion was normal in all patients and ankle motion was normal in 80%. Mean time to resumed occupational activity was 5.7 months (range 1–18). At last follow-up, bone healing had been achieved in all patients.

Discussion: As compared with data in the literature, we found that locked centromedullary nailing allows early weight bearing with less risk of infection for radiological results comparable with those obtained with plate fixation. The secondary displacements resulted from defective locking of inappropriately adapted materials (holes insufficiently distal).

Conclusion: Locked centromedullary nailing is a treatment of choice for fractures of the distal quarter of the leg. Use of new nails with more distal holes should improve outcome by allowing distal locking with at least two screws in all cases.

Aims

Complex joint fractures of the lower extremity are often accompanied by soft-tissue swelling and are associated with prolonged hospitalization and soft-tissue complications. The aim of the study was to evaluate the effect of vascular impulse technology (VIT) on soft-tissue conditioning in comparison with conventional elevation.

Aims

The aim of this study was to evaluate the functional outcome in patients undergoing implant removal (IR) after fracture fixation below the level of the knee.

Vacuum orthoses are being applied in the care of patients with foot and lower leg conditions, as ankle fractures or sprains. The lower leg is protected and immobilized, which increases mobility. Due to the design, the orthoses lead to a difference in leg length, i.e. the side with the orthosis becomes longer, which changes the gait kinematics. To prevent or mitigate the unfavourable effects of altered gait kinematics, leg length-evening devices (shoe lifts) are offered that are worn under the shoe on the healthy side. Our aim was to evaluate the effect of such a device on the normality of gait kinematics. Gait analysis was conducted with 63 adult, healthy volunteers having signed an informed consent form that were asked to walk on a treadmill at a speed of 4.5km/h in three different conditions:. barefoot - as reference for establishing the normality score baseline. with a vacuum orthosis (VACOPed, OPED GmbH, Germany) and a sport shoe. with a vacuum orthosis and a shoe lift (EVENup, OPED GmbH, Germany). Data was sampled using the gait analysis system MCU 200 (LaiTronic GmbH, Austria). The positions of the joint markers were exported from the software and evaluated for the joint angles during the gait cycle using custom software (implemented in DIAdem 2017, National Instruments). A normality score using a modification of the Gait Profile Score (GPS) was calculated in every 1%-interval of the gait cycle and evaluated with a Wilcoxon signed rank test. The GPS value was reduced by 0.33° (0.66°) (median and IQR) while wearing the shoe lift. The effect was statistically significant, and very large (W = 1535.00, p < .001; r (rank biserial) = 0.52, 95% CI [0.29, 0.70]). The significant reduction of the GPS value indicates a more normal gait kinematics while using the leg length-evening device on the contralateral shoe. This rather simple and inexpensive device thus might improve patient comfort and balance while using the vacuum orthoses

Introduction. Fully implantable distraction nails are frequently used for lengthening of the lower leg. What are the indications for humerus lengthening and which results can be expected?. Materials and Methods. The humerus as the best healing bone in the human body is suitable for lengthening with a nail as well but the indications are rare in comparison with the lower legs. Especially when driving a car or when working on a tablet length discrepancy of the arms of more than 4–5cm may cause severe hardening of the cervical muscles and induce chronical pain in the upper spine. Results. A distraction nail (FITBONE) was used in 5 cases for humerus lengthening. The nail was inserted in all cases from proximal. The mean age of the patients was 34 years. The mean lengthening amount was 58mm (55–100). In one case the system was exchanged to reach the desired length. There was no infection, no radial nerve irritation and no chronical shoulder pain. The system was removed in 4 cases in an average of 15 months the other nail will be removed soon as well. Conclusions. The preliminary results of our 5 cases demonstrate, that the FITBONE device is advantageous for lengthening the humerus, if the initial length is sufficient for implantation. In comparison with the use of external fixators the functional outcome, the comfort of treatment and the cosmetic result is amazing

Aim. Fracture-related infection (FRI) is a severe post-traumatic complication which can be accompanied with a soft-tissue defect or an avital soft-tissue envelope. In these cases, a thoroughly planned orthoplastic approach is imperative since a vital soft-tissue envelope is mandatory to achieve fracture union and infection eradication. The aim of our study was to analyse plastic surgical aspects in the management of FRIs, including the type and outcome of soft-tissue reconstruction (STR), and to investigate the long-term outcome of FRI after STR. Method. Patients with a lower leg FRI requiring STR that were treated from 2010 to 2018 at our center were included in this retrospective analysis. STR involved the use of local, pedicled and free flaps. The primary outcome was the success rate of STR, and the secondary outcome was long-term fracture consolidation and cure of infection. Results. Overall, 145 patients with lower leg FRI were identified, of whom 58 (40%) received STR. Muscle flaps were applied in 38, fascio-cutaneous flaps in 19 and a composite osteo-cutaneous flap in one case. All patients underwent successful STR (primary STR in 51/58 patients, 7/58 patients needed secondary STR). A high Charlson Comorbidity Index Score was a significant risk factor for flap failure (p=0.011). Patients with free-flap STR developed significantly more severe complications and needed more surgical interventions (Clavien-Dindo ≥IIIa; p=0.001). Out of the 43 patients that completed long-term follow-up (mean 24 months), fracture consolidation was achieved in 32 and infection eradication in 31. Polymicrobial infection was a significant risk factor for fracture non-union (p=0.002). American Society of Anesthesiologists (ASA) classification of 3 or higher (p=0.040) was a risk factor for persistence or recurrence of infection. Conclusions. In our population, 58/145 patients with FRI required STR. STR was successful in all patients eventually, in 7/58 patients secondary STR was necessary. Therefore, STR should be sought even if primary STR fails. Despite successful STR, the long-term composite outcome showed a high rate of failed fracture consolidation and failed eradication of infection, which was independent of primary STR failure

The aim of this study was to investigate the effect of different loading scenarios and foot positions on the configuration of the distal tibiofibular joint (DTFJ). Fourteen paired human cadaveric lower legs were mounted in a loading frame. Computed tomography scans were obtained in unloaded state (75 N) and single-leg loaded stand (700 N) of each specimen in five foot positions: neutral, 15° external rotation, 15° internal rotation, 20° dorsiflexion, and 20° plantarflexion. An automated three-dimensional measurement protocol was used to assess clear space (diastasis), translational angle (rotation), and vertical offset (fibular shortening) in each foot position and loading condition. Foot positions had a significant effect on the configuration of DTFJ. Largest effects were related to clear space increase by 0.46 mm (SD 0.21 mm) in loaded dorsal flexion and translation angle of 2.36° (SD 1.03°) in loaded external rotation, both versus loaded neutral position. Loading had no effect on clear space and vertical offset in any position. Translation angle was significantly influenced under loading by −0.81° (SD 0.69°) in internal rotation only. Foot positioning noticeably influences the measurement when evaluating the configuration of DTFJ. The influence of the weightbearing seems to have no relevant effect on native ankles in neutral position

Aims. Understanding of open fracture management is skewed due to reliance on small-number lower limb, specialist unit reports and large, unfocused registry data collections. To address this, we carried out the Open Fracture Patient Evaluation Nationwide (OPEN) study, and report the demographic details and the initial steps of care for patients admitted with open fractures in the UK. Methods. Any patient admitted to hospital with an open fracture between 1 June 2021 and 30 September 2021 was included, excluding phalanges and isolated hand injuries. Institutional information governance approval was obtained at the lead site and all data entered using Research Electronic Data Capture. Demographic details, injury, fracture classification, and patient dispersal were detailed. Results. In total, 1,175 patients (median age 47 years (interquartile range (IQR) 29 to 65), 61.0% male (n = 717)) were admitted across 51 sites. A total of 546 patients (47.1%) were employed, 5.4% (n = 63) were diabetic, and 28.8% (n = 335) were smokers. In total, 29.0% of patients (n = 341) had more than one injury and 4.8% (n = 56) had two or more open fractures, while 51.3% of fractures (n = 637) occurred in the lower leg. Fractures sustained in vehicle incidents and collisions are common (38.8%; n = 455) and typically seen in younger patients. A simple fall (35.0%; n = 410) is common in older people. Overall, 69.8% (n = 786) of patients were admitted directly to an orthoplastic centre, 23.0% (n = 259) were transferred to an orthoplastic centre after initial management elsewhere, and 7.2% were managed outwith specialist units (n = 81). Conclusion. This study describes the epidemiology of open fractures in the UK. For a decade, orthopaedic surgeons have been practicing in a guideline-driven, network system without understanding the patient features, injury characteristics, or dispersal processes of the wider population. This work will inform care pathways as the UK looks to the future of trauma networks and guidelines, and how to optimize care for patients with open fractures. Cite this article: Bone Jt Open 2022;3(10):746–752

Introduction. Tibiocalcaneal arthrodesis with a retrograde intramedullary nail is an established procedure considered as a salvage in case of severe arthritis and deformity of the ankle and subtalar joints [1]. Recently, a significant development in hindfoot arthrodesis with plates has been indicated. Therefore, the aim of this study was to compare a plate specifically developed for arthrodesis of the hindfoot with an already established nail system [2]. Method. Sixteen paired human cadaveric lower legs with removed forefoot and cut at mid-tibia were assigned to two groups for tibiocalcaneal arthrodesis using either a hindfoot arthrodesis nail or an arthrodesis plate. The specimens were tested under progressively increasing cyclic loading in dorsiflexion and plantar flexion to failure, with monitoring via motion tracking. Initial stiffness was calculated together with range of motion in dorsiflexion and plantar flexion after 200, 400, 600, 800, and 1000 cycles. Cycles to failure were evaluated based on 5° dorsiflexion failure criterion. Result. Initial stiffness in dorsiflexion, plantar flexion, varus, valgus, internal rotation and external rotation did not differ significantly between the two arthrodesis techniques (p ≥ 0.118). Range of motion in dorsiflexion and plantar flexion increased significantly between 200 and 1000 cycles (p < 0.001) and remained not significantly different between the groups (p ≥ 0.120). Cycles to failure did not differ significantly between the two techniques (p = 0.764). Conclusion. From biomechanical point of view, both tested techniques for tibiocalcaneal arthrodesis appear to be applicable. However, clinical trials and other factors, such as extent of the deformity, choice of the approach and preference of the surgeon play the main role for implant choice. Acknowledgements. This study was performed with the assistance of the AO Foundation