Aims. Social determinants of health (SDOHs) may contribute to the total cost of care (TCOC) for patients undergoing total knee arthroplasty (TKA). The aim of this study was to investigate the association between demographic data, health status, and SDOHs on 30-day length of stay (LOS) and TCOC after this procedure. Methods. Patients who underwent TKA between 1 January 2018 and 31 December 2019 were identified. A total of 234 patients with complete SDOH data were included. Data were drawn from the Chesapeake Regional Information System, the Centers for Disease Control social vulnerability index (SVI), the US Department of Agriculture, and institutional electronic medical records. The SVI identifies areas vulnerable to catastrophic events with four themed scores: socioeconomic status; household composition and disability; minority status and language; and housing and transportation. Food deserts were defined as neighbourhoods located one or ten miles from a grocery store in urban and rural areas, respectively. Multiple regression analyses were performed to determine associations with LOS and costs after controlling for various demographic parameters. Results. Divorced status was significantly associated with an increased LOS (p = 0.043). Comorbidities significantly associated with an increased LOS included chronic obstructive pulmonary disease/asthma and congestive heart failure (p = 0.043 and p = 0.001, respectively). Communities with a higher density of tobacco stores were significantly associated with an increased LOS (p = 0.017). Comorbidities significantly associated with an increased TCOC included chronic obstructive pulmonary disease (p = 0.004), dementia (p = 0.048), and heart failure (p = 0.007). Increased TCOCs were significantly associated with patients who lived in food deserts (p = 0.001) and in areas with an increased density of tobacco stores (p = 0.023). Conclusion. Divorced marital status was significantly associated with an increased LOS following TKA. Living in food deserts and in communities with more tobacco stores were significant risk factors for increased LOS and TCOC. Food access and ease of acquiring tobacco may both prove to be prognostic of outcome after TKA and an opportunity for intervention. Cite this article: Bone Joint J 2021;103-B(6 Supple A):113–118

Aims. The aim of this study was to perform the first population-based description of the epidemiological and health economic burden of fracture-related infection (FRI). Methods. This is a retrospective cohort study of operatively managed orthopaedic trauma patients from 1 January 2007 to 31 December 2016, performed in Queensland, Australia. Record linkage was used to develop a person-centric, population-based dataset incorporating routinely collected administrative, clinical, and health economic information. The FRI group consisted of patients with International Classification of Disease 10th Revision diagnosis codes for deep infection associated with an implanted device within two years following surgery, while all others were deemed not infected. Demographic and clinical variables, as well as healthcare utilization costs, were compared. Results. There were 111,402 patients operatively managed for orthopaedic trauma, with 2,775 of these (2.5%) complicated by FRI. The development of FRI had a statistically significant association with older age, male sex, residing in rural/remote areas, Aboriginal or Torres Strait Islander background, lower socioeconomic status, road traffic accident, work-related injuries, open fractures, anatomical region (lower limb, spine, pelvis), high injury severity, requiring soft-tissue coverage, and medical comorbidities (univariate analysis). Patients with FRI had an eight-times longer median inpatient length of stay (24 days vs 3 days), and a 2.8-times higher mean estimated inpatient hospitalization cost (AU$56,565 vs AU$19,773) compared with uninfected patients. The total estimated inpatient cost of the FRI cohort to the healthcare system was AU$156.9 million over the ten-year period. Conclusion. The results of this study advocate for improvements in trauma care and infection management, address social determinants of health, and highlight the upside potential to improve prevention and treatment strategies. Cite this article: Bone Joint J 2024;106-B(1):77–85

Introduction and Objective. Scaphoid waist fractures (SWF) are notable in upper limb trauma and predominantly occur in young men. Morbidities associated with SWF include fracture non-union, premature arthritis and humpback deformity. Delayed treatment and non-adherence to fracture immobilisation increases likelihood of these complications. There is evidence that men engage in negative health behaviours such as delayed help-seeking. The Scaphoid Waist Internal Fixation for Fractures Trial (SWIFFT) conducted interviews in individuals who had sustained a SWF. Although SWIFFT showed multiple social determinants for the overall injury and healing experience, a key factor this novel study considers is age and sex. This study aimed to analyse interview data from young male participants in SWIFFT to help distinguish the experience of SWF in young men, through exploring the influence of masculinity. Materials and Methods. A purposive sample of 12 young male participants were selected from SWIFFT. These participants were enrolled from a possibility of 13 different centres across Britain. There were 17 semi-structured interviews produced from these participants, and this was thought to be sufficient for data saturation. These interviews were evaluated through deductive thematic analysis with an open-coding approach, with respondents’ experiences being compared against themes documented in men's health literature. The “Braun and Clarke (2006) Six Phases of Thematic Analysis” methodology was adopted to perform this. Results. There were three thematic models developed in the data set, which then were further divided into subthemes. Model 1: Negative Health Behaviour Prior to Treatment, model 2: Feeling Frail and model 3: Need for Speed. Model 1 corroborated that participants were inclined to sustain the injury as a result of risk-taking and would subsequently hesitate to seek treatment. Model 2 indicated that as a result of the injury, respondents were unable to engage in physical activities and activities of daily living. Respondents exercised caution to varying extents after sustaining a SWF. Model 3 highlighted that interviewees were prone to non-adherence with fracture immobilisation and in hindsight resumed employment prematurely. Conclusions. The findings of this study demonstrate that masculinity is significantly influential on the experience of SWF in young men. This was indicated through the results of thematic analysis strongly corresponding with behaviours established in men's health literature. Educational interventions could be of value in addressing behaviours observed in this population group, such as delayed help-seeking and non-compliance with fracture immobilisation. Further work in patient education and concordance with treatment after sustaining a SWF may be beneficial to longer term outcomes. In turn, this may reduce complications associated with SWF in young men

Introduction. Social determinants of health (SDOH) may contribute markedly to the total cost of care (COC) for patients undergoing elective total knee arthroplasty (TKA). This study investigated the association between demographics, health status, and SDOH on lengths of stay (LOS) and 30-day COC. Methods. Patients who underwent TKA between January 2018 and December 2019 were identified. Those who had complete SDOH data were utilized, leaving 234 patients. Data elements were drawn from the Chesapeake Regional Information System, the Center for Disease Control social vulnerability index (SVI), the Food Access Research Atlas (FARA). The SVI identifies areas vulnerable to catastrophic events, with 4 themed scores including: (1) socioeconomic status; (2) household composition and disability; (3) minority status and language; and (4) housing and transportation. Food deserts were defined as neighborhoods located 1 or 10 miles from a grocery store in urban and rural areas, respectively. Multiple regression analyses were performed to determine an association with LOS and cost, after controlling for demographics. Results. Increased 30-day COC associated with SVI theme 3, (3.074 days; p=0.001) and patients who lived in a food desert ($53,205; p=0.001), as well as those who had anemia ($16,112; P = 0.038), chronic obstructive pulmonary disease ($32,570, P = 0.001), congestive heart failure ($30,927, P = 0.003), and dementia ($33,456, P = 0.008). Longer hospital lengths of stay were associated with SVI theme 3. In addition, patients who had anemia and congestive heart failure were at risk for longer hospital lengths of stay (P < 0.001, P = 0.001, respectively). Conclusion. Higher SVI theme 3 scores and living in food deserts were risk factors for increased LOS and costs, respectively. Identifying social factors including a patient's transportation options, living situation and access to healthy foods may prove to be both prognostic of outcomes and an opportunity for intervention

Background. Inpatient dislocation after total hip arthroplasty (THA) is considered a non-reimbursable “never event” by the Centers for Medicare and Medicaid Services. There is extensive evidence that technical procedural factors affect dislocation risk, but less is known about the influence of non-technical factors. We evaluated inpatient dislocation trends following elective primary THA, and identified patient and hospital characteristics associated with the occurrence of dislocation. Methods. We used discharge records from the Nationwide Inpatient Sample (2002–2011). Temporal trends were assessed and multivariable logistic regression modeling was used to identify factors associated with dislocation. Results. The in-hospital dislocation rate increased from 0.025% in 2002 to 0.15% in 2011, despite a downward trend in length of stay (P<0.001). Patient characteristics associated with the occurrence of dislocation were black or Hispanic race/ethnicity, lower household income, and Medicaid insurance. Comorbidities associated with dislocation included hemiparesis/hemiplegia, drug use disorder, chronic renal failure, psychosis, and obesity. Dislocations were less likely to occur at teaching hospitals and in the South. Conclusion. The in-hospital dislocation rate following elective primary THA is increasing, in spite of shorter stays and surgical advances over time. Given the sociodemographic disparities in dislocation risk documented herein, interventions to address social determinants of health might do as much or more to reduce the occurrence of dislocation than technical improvements

Introduction. Total Knee Arthroplasty (TKA) is a proven successful and cost-effective method to relieve pain and improve joint function and quality of life in patients with advanced knee arthritis. However, after a TKA, only 75 to 89% of patients are satisfied. Since patient satisfaction is one of the main objectives of elective orthopaedic surgery, it is important to investigate the reasons for dissatisfaction and develop remedial strategies. Objectives. The aims of the current project are to investigate patient satisfaction after TKA and establish physical, mental and social determinants of patient satisfaction and overall socio-economic costs associated with unsatisfactory outcome. The global objective is to identify patients most likely to benefit from primary TKA, establish optimal evidence-based indications and timing for TKA, and address the necessity to educate patients preoperatively towards realistic expectations or propose alternative therapies. Based on the results, a composite score for patient selection will be developed using objective and subjective parameters. Cut-off values for acceptable indications for TKA will be proposed. Methods. General determinants of patient satisfaction are first investigated in a retrospective and prospective survey of TKA. Expectations regarding the global benefit of TKA, postoperative pain and difficulties are evaluated. Psychological tests assessing the ability of patients to cope with pain are performed. Objective clinical and radiographic parameters, patient reported outcomes and satisfaction are compared between subgroups based on (1) patient intrinsic factors such as gender and age, BMI, co-morbidities, general physical and mental health, activity, level of education and socio-economic situation, (2) implant factors, (3) surgery and surgical experience related factors. Subsequently, a randomized controlled trial of 330 consecutive primary TKAs using 3 contemporary implants of different design concepts will be carried out. Evaluation will be double-blinded (immediately preoperative randomisation, patient blinded, postoperative observer blinded). In addition, a surgeon's assessment of subjective technical difficulty will be performed. A university/teaching hospital setting will be compared with a private hospital and the influence of the surgeon on the level of patient satisfaction will be assessed. Results. Intermediate evaluation of the study revealed extensive logistic difficulties in setting up such a large scale trial and in motivating patients, nursing and medical staff to participate and sustain the necessary commitment and discipline to collect all necessary data at all follow-up intervals. Patients often felt overwhelmed by a multitude of clinical scores and technical assessments leading to a decrease in study compliance and rapid loss to follow-up. Motivation proved easier in a smaller private hospital environment. At the university hospital, patient involvement was enhanced by a personalized approach with information sessions in small groups. The introduction of a new software system with direct patient input via touch screens or remote online completion of scores reduced the data input burden. Scores are examined for simultaneous digital answering of overlapping questions. Conclusions. A large scale trial to investigate longer term patient satisfaction after TKA and establish its determinants involves continuous motivation and sustained discipline of patients and staff. A personalized approach and digital patient reported outcomes prove to maximize data acquisition

The COVID-19 pandemic has led to unprecedented times worldwide. From lockdowns to masks now being part of our everyday routine, to the halting of elective surgeries, the virus has touched everyone and every part of our personal and professional lives. Perhaps, now more than ever, our ability to adapt, change and persevere is critical to our survival. This year's closed meeting of The Knee Society demonstrated exactly those characteristics. When it became evident that an in-person meeting would not be feasible, The Knee Society leadership, under the direction of President John Callaghan, MD and Program Chair Craig Della Valle, MD created a unique and engaging meeting held on September 10–12, 2020. Special recognition should be given to Olga Foley and Cynthia Garcia at The Knee Society for their flexibility and creativeness in putting together a world-class flawless virtual program. The Bone & Joint Journal is very pleased to partner with The Knee Society to once again publish the proceedings of the closed meeting of the Knee Society. The Knee Society is a United States based society of highly selected members who have shown leadership in education and research in knee surgery. It invites up to 15% international members; this includes some of the key opinion leaders in knee surgery from outside the USA. Each year, the top research papers from The Knee Society meeting will be published and made available to the wider orthopaedic community in The Bone & Joint Journal. The first such proceedings were published in BJJ in 2019. International dissemination should help to fulfil the mission and vision of the Knee Society of advancing the care of patients with knee disorders through leadership, education and research. The quality of dissemination that The Bone & Joint Journal provides should enhance the profile of this work and allow a larger body of surgeons, associated healthcare professionals and patients to benefit from the expertise of the members of The Knee Society. The meeting is one of the highlights of the annual academic calendar for knee surgeons. With nearly every member in attendance virtually throughout the 3 days, the top research papers from the membership were presented and discussed in a virtual format that allowed for lively interaction and discussion. There are 75 abstracts presented. More selective proceedings with full papers will be available after a robust peer review process in 2021, both online and in The Bone & Joint Journal. The meeting commenced with the first group of scientific papers focused on Periprosthetic Joint Infection. Dr Berry and colleagues from the Mayo Clinic further help to clarify the issue of serology and aspirate results to diagnose TKA PJI in the acute postoperative setting. 177 TKA's had an aspiration within 12 weeks and 22 were proven to have PJI. Their results demonstrated that acute PJI after TKA should be suspected within 6 weeks if CRP is ≥81 mg/L, synovial WBCs are ≥8500 cells/μL, and/or synovial neutrophils≥86%. Between 6– 12 weeks, concerning thresholds include a CRP ≥ 32 mg/L, synovial WBC ≥7450, and synovial neutrophils ≥ 84%. While historically the results of a DAIR procedure for PJI have been variable, Tom Fehring's study showed promise with the local delivery of vancomycin through the Intraosseous route improved early results. New member Simon Young contrasted the efficacy of the DAIR procedure when comparing early infections to late acute hematogenous PJI. DAIR failed in 63% of late hematogenous PJIs (implant age>1 year) compared to 36% of early (<1year) PJIs. Dr Masri demonstrated in a small group of patients that those with well-functioning articulating spacers can retain their spacers for over 12 months with no difference in infection from those that had a formal two stage exchange. The mental toll of PJI was demonstrated in a longitudinal study by Doug Dennis, where patient being treated with 2 stage exchange had 4x higher rates of depression compared to patient undergoing aseptic revision. The second session focused on both postoperative issues with regards to anticoagulation and manipulation. Steven Haas demonstrated high complication rates with utilization of anticoagulation for treatment of postoperative pulmonary embolism with modern therapeutic anticoagulation (warfarin, enoxaparin, Xa inhibitors) with the Xa inhibitors demonstrating lower complication rates. Two papers focused on the topic of manipulation. Mark Pagnano presented data on timing of manipulation under anesthesia up to even past 12 months. While gains were modest, a subset of patients did achieve substantial gains in ROM > 20degrees even after 3 months post op. Dr Westrich's study demonstrated no difference in MUA outcomes with either IV sedation or neuraxial anesthesia although the length of stay was shorter in the IV sedation group. Several studies in Session II focused on kinematics and femoral component position. Dr Li's in vivo kinematic study during weightbearing flexion and gait demonstrated that several knees rotated with a lateral pivot motion and not all knees can be described with a single motion character. Dr Mayman and his group utilized a computational knee model to demonstrate that additional distal femoral resection results in increasing levels of mid -flexion instability and cautioned against the use of additional bony resection as the first line for flexion contractures. Using computer navigation, Dr Huddleston's study nicely outlined the variability in femoral component rotation to achieve a rectangular flexion gap utilizing a gap balanced method. The third session opened the meeting on Friday morning. The focus was on unicompartmental knee arthroplasty and the increasing utilization of robotic assisted total knee arthroplasty. David Murray showed using registry data that for patient with higher comorbidities (ASA >3), UKA was safer and more cost effective than TKA while Dr Della Valle's group demonstrated overall lower average healthcare costs in UKA patients compared to TKA in the first 10 years after surgery. Dr Geller assessed UKA survivorship among 3 international registries. While survivorship varied by nation and designs, certain designs consistently had better overall performance. Dr Nunley and his group showed robotic navigation UKA significantly reduced outliers in alignment and overhang compared to manual UKA. Dr Catani's data demonstrated that full thickness cartilage loss should still be considered a requirement for UKA success even with robotic assistance. Despite a high dislocation rate of 4%, Mr Dodd demonstrated high survivorship for lateral UKA despite historical contraindications. The growing evidence for robotics TKA was demonstrated in two studies. Professor Haddad showed less soft tissue injury, reduced bone trauma and improved accuracy or rTKA compared to manual TKA while Dr Gustke single surgeon study showed his rTKA had improved forgotten joint scores and less ligament releasing required for balancing. Despite these finding, Dr Lee's study demonstrated that a robotic TKA could not guarantee excellent pain relief and other factors such a patient expectations and psychological factors play a role. Our fourth session was devoted to machine learning and smart tools and modeling. Dr Meneghini used machine learning algorithms to identify optimal alignment outcomes that correlated with patient outcomes. Several parameters such as native tibial slope, femoral sagittal position and coronal limb alignment correlated with outcomes. Along the same lines, Bozic and coauthors demonstrated that using AI algorithms incorporated with PROM's improved levels of shared decision making and patient satisfaction. Dr Lombardi demonstrated that a mobile patient engagement platform that provided smart phone-based exercise and education was comparable to traditional methods. Dr Mahfouz demonstrated the accuracy of using ultrasound to produce 3D models of the bone compared to conventional CT based strategies and Dr Mahoney showed the valued of a preop 3D model in reproducing more normal knee kinematics. The last two talks of the session focused on some of the positives of the COVID-19 pandemic, namely the embracing of telemedicine by patients and surgeons as demonstrated by Dr Slover and the increasing and far reaching educational opportunities made available to residents and fellows during the pandemic. Session five focused on risk stratification and optimization prior to TKA. Dr O'Connor demonstrated that that the implementation of an optimization program preoperatively reduced length of stay and ED visits, and Charles Nelson's study showed that risk stratification tool can lower complication rates in obese patients undergoing TKA comparable to those that are nonobese. Dr Markel's study demonstrated that those who have preoperative depression and anxiety are at higher risk of complications and readmissions after surgery and these issues should be addressed preoperatively. Interestingly, a study by Dr Callaghan demonstrated that care improvement pathways have not lowered the gap in complications for morbidly obese patients undergoing TKA, Dr Barsoum argued that the overall complication rates were low and this patient cohort had significant gains in PROMS after TKA that would not be experienced if arbitrary cutoff for limited surgery were established. The final session on Friday, Session six, had several well done and interesting studies. There continues to be mounting evidence that liposomal bupivacaine has little effect on managing post-operative pain to warrant its increased use. Bill Macaulay and colleagues showed no change in pain scores, opioid consumption and functional scores when liposomal bupivacaine was discontinued at a large academic medical center. Dr Bugbee importantly demonstrated that a supervised ambulation program reduced falls in the early postoperative period. Several paper on healthcare economics were presented. Rich Iorio showed that stratifying complexity of total joint cases between hospitals with a system can be efficient and cost savings while Dr Jiranek demonstrated in his study that complex TKAs can be identified preoperatively and are associated with prolonged operative time and cost of care and consideration should be given in future reimbursement models to a complexity modifier. Dr Springer, in their evaluation of Medicare bundled payment models, demonstrated that providers and hospitals in historical bundled models that became efficient were penalized in the new model, forcing many groups to drop out and return to a fee for service model. Ron Delanois important work showed that social determinants can have a major negative impact on outcomes following TKA. Our final day on Saturday opened with Session seven, and several interesting paper on metal ions/debris in TKA. Dr Whitesides simulator study showed the absence of scratches and material loss in a ceramic TKA compared with Co-Cr TKA and suggested an advantage to this material in patients with metal sensitivity. Conversely, in a histological study of failed TKA, perivascular lymphocytic infiltration was not associated with worse clinical outcomes or differences in revision in a series of 617 aseptic revisions, 19% of which had PVLI found on histology. The Mayo group and Dr Trousdale however, noted that serum metal ion levels can be helpful in identifying implant failure in a group of revision TKAs, especially those with metallic junctions. Dr Dalury demonstrated nicely that use of maximally conforming inserts did not have a negative effect on implant loosening in a series of 76 revision TKA's at an average follow up of 7 years, while Kevin Garvin and his group showed no difference in end of stem pain between cemented and cementless stems in revision TKA. The final two studies in the session by Bolognesi and Peters respectively showed that metaphyseal cones continue to demonstrate excelled survivorship in rTKA setting despite extensive bone loss. Session eight was highlighted by a large series of revision reported by new member Dr Schwarzkopf, who showed that revision TKA done by high volume surgeons demonstrated better outcomes and lower revision rates compared to surgeon who did less than 18 rTKA's per year. Dr Maniar importantly showed that preoperatively, patients with high activity level and low pain and indicated by a high preop forgotten joint score did poorly following TKA while David Ayers nicely demonstrated that KOOS scores that assess specific postoperative outcomes can predict patient dissatisfaction after TKA. The final paper in this session by Max Courtney showed that the majority of surgical cancellations are due to medical issues, yet a minority of these undergo any intervention specifically for that condition, but they resulted in a delay of 5 months. The first two studies of Session nine focused on polyethylene thickness. Dr Backstein demonstrated no difference in KSS scores, change in ROM and aseptic revision rates based on polyethylene thickness in a series of 195 TKA's. An interesting lab study by Dr Tim Wright showed a surprising consistency in liner thickness choice among varying levels of surgeon experience that did not correlate with applied forces or gap stability estimates. Two studies looked specifically at the issue of tibial loosening and implant design. Nam and colleagues were not able to demonstrate concerning findings for increasing tibial loosening in a tibial baseplate with a shortened tibial keel at short term follow up, while Lachiewicz demonstrated a 19% revision or revision pending rate in 223 cemented fixed bearing ATTUNE TKA at a mean of 30 months. Our final session of the meeting, began with encouraging news, that despite only currently capturing about 40% of TJA's done in the US, the American Joint Replacement Registry data is representative of data in other representative US databases. An interesting study presented by Robert Barrack looked at bone remodeling in the proximal tibia after cemented and cementless TKA of two different designs. No significant difference was noted among the groups with the exception of the cemented thicker cobalt chrome tray which demonstrated significantly more bone mineral density loss. Along the same lines, a study out of Dr Bostrom's lab demonstrated treatment of a murine tibial model with iPTH prevents fibrous tissue formation and enhances bone formation in cementless implants. New Member Jamie Howard showed no difference in implant migration and kinematics of a single radius cementless design using either a measured resection or gap balancing technique and Dr Cushner show no difference in blood loss with cemented or cementless TKA with the use of TKA. The final two studies looked at staging and bilateral TKA's. Peter Sharkey showed that simultaneous TKA's were associated with higher complication compared to staged TKA and that staged TKA with less than a 90-day interval was not associated with higher risk. However, Mark Figgie showed that patients undergoing simultaneous TKA compared to staged TKA, missed 17 fewer days of work. In spite of the virtual nature of the meeting, there were some outstanding scientific interactions and the material presented will continue to generate debate and to guide the direction of knee arthroplasty as we move forwards

The December 2023 Shoulder & Elbow Roundup³⁶⁰ looks at: Clavicle fractures: is the evidence changing practice?; Humeral shaft fractures, and another meta-analysis…let’s wait for the trials now!; Hemiarthroplasty or total elbow arthroplasty for distal humeral fractures…what does the registry say?; What to do with a first-time shoulder dislocation?; Deprivation indices and minimal clinically important difference for patient-reported outcomes after arthroscopic rotator cuff repair; Prospective randomized clinical trial of arthroscopic repair versus debridement for partial subscapularis tears; Long-term follow-up following closed reduction and early movement for simple dislocation of the elbow; Sternoclavicular joint reconstruction for traumatic acute and chronic anterior and posterior instability.

Aims

Perthes’ disease is an idiopathic avascular necrosis of the developing femoral head, often causing deformity that impairs physical function. Current treatments aim to optimize the joint reaction force across the hip by enhancing congruency between the acetabulum and femoral head. Despite a century of research, there is no consensus regarding the optimal treatment. The aim of this study was to describe the experiences of children, their families, and clinicians when considering the treatment of Perthes’ disease.

Aims

The aim of this study was to characterize the influence of social deprivation on the rate of complications, readmissions, and revisions following primary total shoulder arthroplasty (TSA), using the Social Deprivation Index (SDI). The SDI is a composite measurement, in percentages, of seven demographic characteristics: living in poverty, with < 12 years of education, single-parent households, living in rented or overcrowded housing, households without a car, and unemployed adults aged < 65 years.

Aims

The purpose of this study was to identify factors associated with limitations in function, measured by patient-reported outcome measures (PROMs), six to nine months after a proximal humeral fracture, from a range of demographic, injury, psychological, and social variables measured within a week and two to four weeks after injury.