bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selling Bonus Actions in Video Games
Authors: Sheng Lifei , Zhao Xuying , Thomas Ryan Christopher 
Published: June 2024

In the mobile video games industry, a common in-app purchase is for additional “moves” or “time” in single-player puzzle games. We call these in-app purchases bonus actions. In some games, bonus actions can only be purchased in advance of attempting a level of the game (pure advance sales (PAS)), yet in other games, bonus actions can only be purchased in a “spot” market that appears when an initial attempt to pass the level fails (pure spot sales). Some games offer both advance and spot purchases (hybrid advance sales). This paper studies these selling strategies for bonus actions in video games. Such a question is novel to in-app tools selling in video games, and it cannot be answered by previous advance selling studies focusing on end goods. We model the selling of bonus actions as a stochastic extensive form game. We show how the distribution of skill among players (i.e., their inherent ability to pass the level) and the inherent randomness of the game influence selling strategies. For casual games, where low-skill players have a sufficiently high probability of success in each attempt, if the proportion of high-skill players is either sufficiently large or sufficiently small, firms should adopt PAS and shut down the “spot” market. Furthermore, the player welfare-maximizing selling strategy is to sell only in the spot market. Hence, no “win-win” strategy exists for casual games. However, PAS can be a win-win for hardcore games, where low-skill players have a sufficiently low success probability for each attempt. This paper was accepted by Hemant Bhargava, information systems. Funding: C. T. Ryan received funding from NSERC Discovery [Grant RGPIN-2020-06488]. Supplemental Material: The online appendix is available at https://doi.org/10.1287/mnsc.2022.02348 .
How to Design a Stable Serial Knockout Competition
Authors: Lambers Roel , Pendavingh Rudi , Spieksma Frits 
Published: June 2024

We investigate a new tournament format that consists of a series of individual knockout tournaments; we call this new format a serial knockout competition (SKC). This format has recently been adopted by the Professional Darts Corporation. Depending on the seedings of the players used for each of the knockout tournaments, players can meet in the various rounds (e.g., first round, second round … semifinal, final) of the knockout tournaments. Following a fairness principle of treating all players equal, we identify an attractive property of an SKCl each pair of players should potentially meet equally often in each of the rounds of the SKC. If the seedings are such that this property is indeed present, we call the resulting SKC stable. In this note, we formalize this notion, and we address the following question. Do there exist seedings for each of the knockout tournaments such that the resulting SKC is stable? We show using a connection to the Fano plane that the answer is yes for eight players, and we prove that the resulting SKC is unique up to permutations of the players. We further prove that stable SKCs exist for any numbers of players that are a power of two, and we provide stable schedules for competitions on 16 and 32 players. Funding: The research of F. Spieksma was partly funded by the Nederlandse Organisatie voor Wetenschappelijk Onderzoek [Grant 024.002.003].
INCIDENCE, DEMOGRAPHICS, CHARACTERISTICS, AND MANAGEMENT OF ACUTE ACHILLES TENDON RUPTURE
Authors: Briggs-Price S. , O'Neill S. , Houchen-Wolloff L. , Modha G. , Fitzpatrick E. , Faizi M. , Shepherd J. , Mangwani J. 
Published: June 2024

IntroductionAchilles tendon rupture (ATR) account for 10.7% of all tendon and ligament injuries and causes lasting muscular deficits and have a profound impact on patients’ quality of life1,2. The incidence, characteristics and management of ATR in the United Kingdom is poorly understood.MethodData was collected prospectively from University Hospitals of Leicester Emergency Department (ED) between January 2016 and December 2020 and analysed retrospectively. The medical records were reviewed to determine management protocols (surgical/non-surgical) and limited mobilisation (VACOped™ boot) duration. Leicestershire population data was taken from Leicestershire County Council demography report.Findings277 individuals were diagnosed with an ATR during the 4-year period. The mean (SD) annual incidence was 56 (±6) ATR. An incidence rate of 8.02 per 100,000 people per annum. The average characteristics of those experiencing an ATR is male (78.3%), 46.8yrs old (±14.4), body mass index 29.1 (±6.3). Median (IQR) number of comorbidities 1 (2) and duration to present to ED was 0 days (1). The main mechanism of rupture was sporting activity (62.1%).97.4% were non-surgically managed using a limited mobilisation boot (VACOped). The boot was worn for an average of 62.6 days (±8.9). 94 participants provided pre-ATR Achilles symptoms data. 16% (n=15/94) of participants reported a previous contralateral ATR. 7.4% reported a re-rupture (n=7/94). 15.4% (n=14/91) reported an Achilles tendinopathy on the ipsilateral side prior to ATR. 7.7% (n=7/91) reported bilateral Achilles tendinopathy and 1.1% (n=1/91) reported contralateral Achilles tendinopathy prior to ATR.ConclusionThe incidence of ATR is 8.02 cases per 100,000 people per annum. This is the first UK data on ATR incidence. Most ATR were managed non-surgically in this cohort. The majority of ruptures occurred during sporting activity. Those that had previous Achilles symptoms (24.2%) indicate tendons are not always asymptomatic prior to ATR.
EFFECT OF FIBULA SHORTENING ON MEDIAL CLEAR SPACE AND LATERAL TRANSLATION OF THE TALUS: AN ANATOMICAL CADAVERIC STUDY
Authors: Gomaa A. , Heeran N. , Roper L. , Airey G. , Gangadharan R. , Mason L. , Bond A. 
Published: June 2024

IntroductionFibula shortening with an intact anterior tibiofibular ligament (ATFL) and medial ligament instability causes lateral translation of the talus. Our hypothesis was that the interaction of the AITFL tubercle of the fibular with the tibial incisura would propagate lateral translation due to the size differential.AimTo assess what degree of shortening of the fibular would cause the lateral translation of the talus.MethodologyTwelve cadaveric ankle specimens were dissected removing all soft tissue except for ligaments. They were fixed on a specially-designed platform within an augmented ankle cage allowing tibial fixation and free movement of the talus. The fibula was progressively shortened in 5mm increments until complete ankle dislocation. The medial clear space was measured with each increment of shortening.ResultsThe larger AITFL tubercle interaction with the smaller tibial incisura caused a significant increase in lateral translation of the talus. This occurred in most ankles between 5–10mm of fibular shortening. The medial clear space widened following 5mm of shortening in 5 specimens (mean=2.0725, SD=±2.5338). All 12 specimens experienced widening by 10mm fibula shortening (Mean=7.2133mm, SD=±2.2061). All specimens reached complete dislocation by 35mm fibula shortening. Results of ANOVA analysis found the data statistically significant (p<0.0001).ConclusionThis study shows that shortening of the fibula causes a significant lateral translation of the talus provided the ATFL remains intact. Furthermore, the interaction of the fibula notch with the ATFL tubercle of the tibia appears to cause a disproportionate widening of the medial clear space due to its differential in size. Knowledge of the extent of fibula shortening can guide further intervention when presented with a patient experiencing medial clear space widening following treatment of an ankle fracture.
THE ACUTE MANAGEMENT OF PILON FRACTURES (ENFORCE) STUDY: A TRAINEE-LED NATIONAL COLLABORATIVE EVALUATION OF PRACTICE
Authors: Hill D. , Davis J. 
Published: June 2024

IntroductionTibial Pilon fractures are potentially limb threatening, yet standards of care are lacking from BOFAS and the BOA. The mantra of “span, scan, plan” describes staged management with external fixation to allow soft tissue resuscitation, followed by a planning CT-scan. Our aim was to evaluate how Tibial Pilon fractures are acutely managed.MethodsENFORCE was a multi-centre retrospective observational study of the acute management of partial and complete articular Tibial Pilon fractures over a three-year period. Mechanism, imaging, fracture classification, time to fracture reduction and cast, and soft tissue damage control details were determined.Results656 patients (670 fractures) across 27 centres were reported. AO fracture classifications were: partial articular (n=294) and complete articular (n=376). Initial diagnostic imaging mobilities were: plain radiographs (n=602) and CT-scan (n=54), with all but 38 cases having a planning CT-scan. 526 fractures had a cast applied in the Emergency Department (91 before radiological diagnosis), with the times taken to obtain post cast imaging being: mean 2.7 hours, median 2.3 hours, range 28 mins – 14 hours). 35% (102/294) of partial articular and 57% (216/376) of complete articular (length unstable) fractures had an external fixator applied, all of which underwent a planning CT-scan. Definitive management consisted of: open reduction internal fixation (n=495), fine wire frame (n=86), spanning external fixator (n=25), intramedullary nail (n=25), other (n=18).ConclusionThe management of Tibial Pilon fractures is variable, with prolonged delays in obtaining post cast reduction radiographs, and just over half of length unstable complete articular fractures being managed with the gold standard “span, scan, plan” staged soft tissue resuscitation. A BOFAS endorsed BOAST (British Orthopaedic Association Standard for Trauma) for Tibial Pilon fractures is suggested for standardisation of the acute management of these potentially limb threatening injuries, together with setting them apart from more straightforward ankle fractures.
WHAT DO BOFAS MEMBERS PERCEIVE TO BE THE BARRIERS AND FACILITATORS OF DAY-CASE SURGERY FOR MAJOR FOOT AND ANKLE PROCEDURES? A SCOPING SURVEY OF SURGEONS
Authors: Houchen-Wolloff L. , Berry A. , Crane N. , Townsend D. , Clayton R. , Mangwani J. 
Published: June 2024

IntroductionRecent advances in minimally invasive surgery and improved post-operative pain management make it possible to perform major foot/ankle operations as day-case. This could have significant impact on length of stay, saving resources and is in keeping with government policy. However, there are theoretical concerns about complications and low patient satisfaction due to pain.MethodsThe survey was developed following review of the literature and was approved for distribution by the BOFAS (British Orthopaedic Foot & Ankle Society) scientific committee. An online survey (19 questions) was sent to UK foot and ankle surgeons via the BOFAS membership list. Major foot/ ankle procedures were defined as surgery that is usually performed as an inpatient in majority of centres and day-case as same day discharge, with day surgery as the intended pathway.ResultsA total of 132 surgeons responded, 80% from Acute NHS Trusts. The majority (78%) thought that more procedures could be performed as day-case at their centre. Currently 45% of respondents perform less than 100 day-case surgeries per year for these procedures. Despite post-operative pain and patient satisfaction being theoretical concerns for day-case surgery in this population; these outcomes were only measured by 34% and 10% of respondents respectively. The top perceived barriers to performing more major foot and ankle procedures as day-case were: Lack of physiotherapy input pre/post-operatively (23%), Lack of out of hours support (21%).ConclusionsThere is consensus among surgeons to do more major foot/ ankle procedures as day-case. Despite theoretical concerns about post-operative pain and satisfaction this was only measured by a third of those surveyed. Out of hours support and physiotherapy input pre/ post-op were perceived as the main barriers. There is a need to scope the provision of physiotherapy pre/post-operatively and out of hours support at sites where this is a perceived barrier.
TOWARDS UNDERSTANDING MÜLLER-WEISS DISEASE: A UNIVERSAL PLATFORM
Authors: Wong-Chung J. , McKenna R. , Lynch-Wong M. , Walls A. , Wilson A. 
Published: June 2024

BackgroundThe only existing classification of Müller-Weiss Disease (MWD), based solely on Méary's angle, serves neither as guide for prognosis nor treatment. This accounts for lack of gold standard in its management.MethodsNavicular compression, medial extrusion, Kite's angle and metatarsal lengths were measured on all radiographs of 95 feet with MWD. Joints involved, presence and location of navicular fracture were recorded.ResultsWe identified three distinct groups. Group 1 comprises 11 “early-onset” MWD feet, aged 9 to 29 years. These had the greatest compression and medial extrusion, and lowest Kite's angles. All except 1 were index minus and had a lateral navicular fracture. None has required surgery to date. Only 1 has moderate talonavicular joint (TNJ) degeneration.Group 2 comprises 23 “Müller-Weissoid” feet with radiologically normal navicular in their fifties and developing MWD, on average, 4.5 years later. These had the lowest compression and extrusion, and highest Kite's angles. None had complete fracture. All had TNJ arthritis, with early changes at lateral naviculocuneiform joint (NCJ) in 43%. Group 3 “late-onset” MWD, presenting in the sixth decade, is subdivided into 3 sub-groups. Only TNJ is involved in group 3A (16). Group 3B denotes affection of TNJ more than NCJ (20). In group 3C “reverse Müller-Weiss disease”, which affects NCJ more than TNJ (25), second metatarsal overlength is highest of all groups. No difference in age, compression, extrusion and Kite's angle exists among the 3 subgroups. No fracture occurred in group 3A compared to 65% and 32% in groups 3B and 3C, respectively.ConclusionsWith a need to compare like-for-like pathology, the proposed classification provides a common platform for reporting outcomes of different treatment modalities, operative or nonoperative. We theorize pathogenetic pathways in the different groups and propose systematic surgical approaches for each category.
OUTCOMES OF TENOSYNOVIAL GIANT CELL TUMOUR OF THE FOOT AND ANKLE
Authors: Barnett J. , Rudran B. , Patel S. , Aston W. , Welck M. , Cullen N. 
Published: June 2024

BackgroundTenosynovial giant cell tumour (TGCT) is a benign proliferative disease affecting synovial membranes. There are two forms, localised and diffuse, which although histologically similar are managed differently. It is locally invasive and is treated in most cases by operative excision. The aim of this study was to assess outcomes from the largest single-centre experience to date in patients with this condition.MethodsA retrospective analysis of 123 cases was performed in patients treated between 2003 and 2019 with TGCT of the foot and/or ankle. Data was collected on age at presentation, radiological pattern of disease, location of disease, treatment provided and recurrence rates. The minimum follow-up was 2 years with a mean of 7.7 years.Results47 male and 76 female patients with a mean age at diagnosis of 39 (range, 11–76) years were identified. 85 (69.1%) cases were categorised as localised and 38 (30.9%) were diffuse. Half of the cases presented in the ankle (62/123, 50.4%). 89% (110) of patients underwent open operative excision of the lesion. Radiotherapy was used in 2 cases for recurrent disease. Pain was the most common postoperative symptom which developed in 20% (22/110) of cases). 13 cases were managed nonoperatively where symptoms were minimal, with one case requiring surgery at a later date. Disease recurrence was 3.5% (3/85) in localised disease and 36.8% (14/38) in diffuse disease giving an overall recurrence rate of 13.8% (17/123).ConclusionThe outcomes of TGCT management are dependent on the type of disease, the extent of preoperative erosive changes and the presence of pre-operative pain. We present a summary of recommended management based on the experience from this single tertiary centre.
THE IMPORTANCE OF ANATOMICAL CHARCOT RECONSTRUCTION UTILIZING STANDARDIZED OSTEOTOMIES TO IMPROVE SURGICAL OUTCOMES
Authors: Kosa P. , Ahluwalia R. , Reichert I. 
Published: June 2024

IntroductionCharcot neuroarthropathy is a debilitating condition that frequently leads to skeletal instability, and has an increased risk of ulceration leading to infection and amputation. However, surgical reconstruction may offer limb salvage and restauration of an ulcer-free, plantigrade stable foot for functional weight-bearing. We report on our case series according to a prospective protocol and analyse factors leading to a favourable outcome.MethodsWe report a prospective follow-up of 62 patients undergoing Charcot reconstruction, May 2014- Jan 2022, by two surgeons. Peripheral vascular disease was routinely assessed using Duplex scan and major arterial disease was treated before reconstruction. Utilising 3D modelling, pre-operative planning and standardised osteotomies, we performed anatomical correction with radiological evidence. Definitive fixation was undertaken with internal fixation to stabilise the hindfoot. Multivariant analysis was performed to assess risk factors for failure (P>0.05 statistical significance).Results59 feet were included, 3 patients did not progress to definitive surgery and 3 patients had bilateral surgery. 62.7% patients were male with an average age of 56, 88.13% had Type 2 diabetes, 56% were hypertensive, 14% were on dialysis. Twenty (54.1%) single stage reconstructions had pre-operative ulceration, 3 pts had ischaemic heart disease and 36 pts had evidence of peripheral arterial disease. 81% of patients achieved normalisation of the 3 out of 4 anatomical angles (P<0.05). Two patients (3.1%) required metalwork removal for infection and limb salvage, 11 (18.6%) had delayed wound healing. Survivorship was 97% at 3yrs, and 94% at 6yrs, however if pre-existing vascular disease was present, it was 94% at 3yrs 85.3% at 6yrs. All patients were mobile at a 3 years mean follow up.ConclusionCareful patient selection, multidisciplinary team and anatomic reconstruction led to predictable outcomes and functional limb salvage. Pre-operative vascular compromise led to a slight reduction in survivorship, but no major amputation.
CLINICAL OUTCOMES OF AUTOLOGOUS OSTEOCHONDRAL TRANSPLANTATION FOR OSTEOCHONDRAL LESIONS OF THE TALUS: AN AGE-BASED MULTIVARIABLE ANALYSIS
Authors: Azam M. , Colasanti C. , Butler J. , Weiss M. , Brodeur P. , Kennedy J. 
Published: June 2024

IntroductionThe purpose of this study was to examine trends in patient characteristics and clinical outcomes that occur with age as a statistical variable when performing autologous osteochondral transplantation (AOT) for the treatment of osteochondral lesions of the talus (OLT).MethodsA retrospective cohort study for AOT procedures on 78 patients from 2006 to 2019. was conducted Clinical outcomes were evaluated via FAOS scores. A multivariable linear regression was used to assess the independent factors predictive of the first post-operative FAOS after AOT. The independent variables included pre-operative FAOS, age, defect size, shoulder lesion, cystic lesion, prior traumatic injury, and history of microfracture surgery. A p-value <.05 was considered significant and 95% confidence limits (95% CL) for regression coefficient estimates (est.) were calculated.Results78 patients were included with a mean age of 35.5 ± 13.6years at a mean follow-up was 54.4 ± 18.9 months. The mean pre-operative FAOS was 54.3 ± 19.4 and the mean post-operative FAOS was 83.4 ± 13.6. The mean defect size was 109.3±62.4 mm2. The multivariable linear regression showed that the pre-operative FAOS was associated with a higher post-operative FAOS (est., 95% CL: 0.16, 0.012 – 0.307; p=0.034). Defect size (est., 95% CL: −0.05, −0.097 – −0.003; p=0.0358), having a shoulder lesion (est., 95% CL: −9.068, −15.448 – −2.688; p=0.006), or having a prior microfracture surgery (est., 95% CL: −7.07, −13.118 – −1.021; p=0.0226) were associated with a lower post-operative FAOS.ConclusionPatient age was not an independent risk factor for inferior clinical outcomes after AOT for OLT. Additionally, cystic lesions, or lesions with a traumatic aetiology were not significantly associated with post-operative FAOS. Having a shoulder lesion had the largest marginal effect on post-operative FAOS. These findings provide important information for providers when counseling and selecting patients for AOT procedure for treatment of OLT.
LONG-TERM FOLLOW-UP, REOPERATIONS, AND PATIENT-REPORTED OUTCOMES FOLLOWING REVISION SURGERY FOR FAILED TOTAL ANKLE ARTHROPLASTIES
Authors: Somanathan A. , Sharp B. , Saedi F. , Loizou C. , Brown R. , Kendal A. 
Published: June 2024

IntroductionPrimary ankle arthroplasty (TAR) is increasingly used to treat end-stage ankle arthritis. Reported revision rates of TAR vary from 8.5% to 11.1% at 9 years. Revision surgery remains technically challenging with options ranging from simple joint debridement to tibio-talar-calcaneal fusion. The efficacy of these procedures remains unclear and there is no consensus on optimal revision options.MethodsA retrospective cohort study was performed of all patients undergoing surgery for a failed primary TAR at the Nuffield Orthopaedic Centre (2004–2021). TAR failure was determined by clinical assessment, serial radiographs and CT scans. Primary outcome measures included type and time of index surgery post TAR. Secondary outcomes included frequency of re-operations, post-operative complications, patient reported outcomes and union rate (for revision arthrodesis procedures).Results70 failed TARs in 69 patients (35M:34F, mean 65.7 years, s.d.=11.6) underwent re-operation a mean of 6.24 years (range 1–30) post primary. In total, 107 operations were performed including revision fusion (n=50), revision arthroplasty (n=14), bearing exchange (n=9) and joint clearance (n=9). The overall revision fusion union rate was 73.5% over a mean of 12.5 months (s.d.=7.6). 16/23 (69.6%) Tibio-Talo-Calcaneal and 9/12 (75%) ankle fusions (previous subtalar/triple fusion) using a hindfoot nail united over a mean 11.4 months (s.d.=6.0) and 15 months (s.d.=9.48) respectively. Only 64% of ankle fusions using screws alone united (mean=10.6 months, s.d.=8.14). The average post-operative MOXFQ score was 28.3 (s.d.=19.3). 73% said the operation improved their function and would recommend it to a friend/family member.ConclusionDespite low post-operative MOXFQ scores, over 70% of patients were satisfied with re-operation for a failed TAR. Over 26% of all TAR revision fusions fail to unite with the highest non-union rates observed post ankle arthrodesis with screws alone (36.4%).