In Vitro Evaluation of Vancomycin-Induced Toxicity in Human Primary Knee Chondrocytes.

Septic arthritis as a complication of orthopaedic joint surgery can have catastrophic outcomes for patients. To minimise infection risk associated with elective orthopaedics, topical vancomycin during surgery has become increasingly common. Evidence suggests that high concentrations of vancomycin, following direct application of the drug to the joint, are toxic towards various local cell types in the joint, including chondrocytes. However, the mechanism of this vancomycin tissue toxicity is yet to be determined. The aim of this study was to evaluate the toxicity of vancomycin on chondrocytes and the mechanisms of cell death involved. Human primary knee chondrocytes were exposed to vancomycin (1.25-10 mg/mL) for 24 h and their viability assessed using the resazurin reduction assay in vitro. Specific cell death mechanisms and their contributors, including reactive oxygen species (ROS) production and apoptosis, were measured. This study showed that high concentrations of vancomycin (5 and 10 mg/mL) were toxic towards human primary knee chondrocyte cells, while lower concentrations (1.25 and 2.5 mg/mL) were not. Cell death studies found that this occurred through an apoptotic pathway. This study provides additional support that vancomycin in high doses is toxic towards chondrocytes and preliminary evidence that this toxicity occurs via apoptotic cell death mechanisms.

Stratification of Outpatient Physical Therapy Following Total Knee Arthroplasty: Knee Arthroplasty Physical Therapy Pathways (KAPPA) Nonrandomized Controlled Trial.

BACKGROUND: Outpatient physical therapy following total knee arthroplasty (TKA) is often considered crucial for an effective recovery. However, recent evidence suggests that a self-directed pathway may yield similar benefits to supervised care. Despite this, there appear to be no established criteria to determine who can successfully self-direct their rehabilitation versus those who would benefit from outpatient physical therapy. This study aimed to determine if early postoperative criteria can stratify TKA patients into a self-directed or supervised physical therapy pathway without compromising outcomes. METHODS: Overall, 60 TKA patients were initially allocated to a self-directed, unsupervised protocol for their postoperative rehabilitation. Baseline demographics, along with functional and self-reported outcomes, were assessed preoperatively and at 2 weeks, 6 weeks, and 4 months following surgery. Patients were referred to supervised outpatient physical therapy if they met any of the following Knee Arthroplasty Physical Therapy Pathways (KAPPA) criteria: (1) knee flexion range of motion <90 degrees; (2) knee extension range of motion lacking >10 degrees; or (3) dissatisfaction with the progress of their rehabilitation. RESULTS: At 2 weeks post-TKA, 28 participants met the KAPPA criteria for supervised physical therapy for reasons of knee flexion <90 degrees (61%), a lack of knee extension >10 degrees (36%), or not being satisfied with the progress of their recovery (3%). The remaining 32 participants continued with a self-directed rehabilitation pathway. All outcomes assessed favored the self-directed group at 2 weeks, however, after an average of 4 supervised physical therapy sessions at 4 months there were no longer any differences between the 2 groups. CONCLUSIONS: Over half of the included participants could self-direct their rehabilitation following TKA without supervised physical therapy while also maintaining excellent clinical outcomes. For those who met KAPPA criteria at 2 weeks post-TKA, 4 supervised physical therapy sessions appeared to be beneficial when outcomes were reassessed at 4 months.

Morphology of proximal and distal human semitendinosus compartments and the effects of distal tendon harvesting for anterior cruciate ligament reconstruction.

The human semitendinosus muscle is characterized by a tendinous inscription separating proximal and distal neuromuscular compartments. As each compartment is innervated by separate nerve branches, potential exists for independent operation and control of compartments. However, the morphology and function of each compartment have not been thoroughly examined in an adult human population. Further, the distal semitendinosus tendon is typically harvested for use in anterior cruciate ligament reconstruction surgery, which induces long-term morphological changes to the semitendinosus muscle-tendon unit. It remains unknown if muscle morphological alterations following anterior cruciate ligament reconstruction are uniform between proximal and distal semitendinosus compartments. Here, we performed magnetic resonance imaging on 10 individuals who had undergone anterior cruciate ligament reconstruction involving an ipsilateral distal semitendinosus tendon graft 14 ± 4 months prior, extracting morphological parameters of the whole semitendinosus muscle and each individual compartment from both the (non-injured) contralateral and surgical legs. In the contralateral leg, volume and length of the proximal compartment were smaller than the distal compartment. No between-compartment differences in volume or length were found for anterior cruciate ligament reconstructed legs, likely due to greater shortening of the distal compared to the proximal compartment after anterior cruciate ligament reconstruction. The maximal anatomical cross-sectional area of both compartments was substantially smaller on the anterior cruciate ligament reconstructed leg but did not differ between compartments on either leg. The absolute and relative between-leg differences in proximal compartment morphology on the anterior cruciate ligament reconstructed leg were strongly correlated with the corresponding between-leg differences in distal compartment morphological parameters. Specifically, greater between-leg morphological differences in one compartment were highly correlated with large between-leg differences in the other compartment, and vice versa for smaller differences. These relationships indicate that despite the heterogeneity in compartment length and volume, compartment atrophy is not independent or random. Further, the tendinous inscription endpoints were generally positioned at the same proximodistal level as the compartment maximal anatomical cross-sectional areas, providing a wide area over which the tendinous inscription could mechanically interact with compartments. Overall, results suggest the two human semitendinosus compartments are not mechanically independent.

Cost of septic and aseptic revision total knee arthroplasty: a systematic review.

BACKGROUND: The increasing incidence of primary total knee arthroplasty (TKA) has led to an increase in both the incidence and the cost burden of revision TKA procedures. This study aimed to review the literature on the cost of revision TKA for septic and aseptic causes and to identify the major cost components contributing to the cost burden. METHODS: We searched MEDLINE (OvidSp), Embase, Web of Science, Cochrane Library, EconLit, and Google Scholar to identify relevant studies. Selection, data extraction and assessment of the risk of bias and cost transparency within the studies were conducted by two independent reviewers, after which the cost data were analysed narratively for 1- or 2-stage septic revision without re-revision; 2-stage septic revision with re-revision; and aseptic revision with and without re-revision, respectively. The major cost components identified in the respective studies were also reported. RESULTS: The direct medical cost from the healthcare provider perspective for high-income countries for 2-stage septic revision with re-revision ranged from US$66,629 to US$81,938, which can be about 2.5 times the cost of 1- or 2-stage septic revision without re-revision, (range: US$24,027 - US$38,109), which can be about double the cost of aseptic revision without re-revision (range: US$13,910 - US$29,213). The major cost components were the perioperative cost (33%), prosthesis cost (28%), and hospital ward stay cost (22%). CONCLUSIONS: Septic TKA revision with re-revision for periprosthetic joint infection (PJI) increases the cost burden of revision TKA by 4 times when compared to aseptic single-stage revision and by 2.5 times when compared to septic TKA revision that does not undergo re-revision. Cost reductions can be achieved by reducing the number of primary TKA that develop PJI, avoidance of re-revisions for PJI, and reduction in the length of stay after revision. TRIAL REGISTRATION: PROSPERO; CRD42020171988 .

Patellar cartilage increase following ACL reconstruction with and without meniscal pathology: a two-year prospective MRI morphological study.

BACKGROUND: Anterior cruciate ligament reconstruction (ACLR) together with concomitant meniscal injury are risk factors for the development of tibiofemoral (TF) osteoarthritis (OA), but the potential effect on the patellofemoral (PF) joint is unclear. The aim of this study was to: (i) investigate change in patellar cartilage morphology in individuals 2.5 to 4.5 years after ACLR with or without concomitant meniscal pathology and in healthy controls, and (ii) examine the association between baseline patellar cartilage defects and patellar cartilage volume change. METHODS: Thirty two isolated ACLR participants, 25 ACLR participants with combined meniscal pathology and nine healthy controls underwent knee magnetic resonance imaging (MRI) with 2-year intervals (baseline = 2.5 years post-ACLR). Patellar cartilage volume and cartilage defects were assessed from MRI using validated methods. RESULTS: Both ACLR groups showed patellar cartilage volume increased over 2 years (p < 0.05), and isolated ACLR group had greater annual percentage cartilage volume increase compared with controls (mean difference 3.6, 95% confidence interval (CI) 1.0, 6.3%, p = 0.008) and combined ACLR group (mean difference 2.2, 95% CI 0.2, 4.2%, p = 0.028). Patellar cartilage defects regressed in the isolated ACLR group over 2 years (p = 0.02; Z = - 2.33; r = 0.3). Baseline patellar cartilage defect score was positively associated with annual percentage cartilage volume increase (Regression coefficient B = 0.014; 95% CI 0.001, 0.027; p = 0.03) in the pooled ACLR participants. CONCLUSIONS: Hypertrophic response was evident in the patellar cartilage of ACLR participants with and without meniscal pathology. Surprisingly, the increase in patellar cartilage volume was more pronounced in those with isolated ACLR. Although cartilage defects stabilised in the majority of ACLR participants, the severity of patellar cartilage defects at baseline influenced the magnitude of the cartilage hypertrophic response over the subsequent ~ 2 years.

Editorial Commentary: Is It Time for the Vancomycin Wrap to Become a Universal Recommendation for the Prevention of Septic Arthritis Following Anterior Cruciate Ligament Reconstruction?

Septic arthritis is a devastating complication of anterior cruciate ligament (ACL) reconstruction, which can still occur in approximately 1% of patients despite appropriate intravenous antibiotic prophylaxis and other recommended preventative measures being undertaken. The infection is most likely secondary to the autograft becoming contaminated during harvest and preparation, introducing bacteria into the joint on insertion. Presoaking ACL grafts in 5 mg/mL vancomycin is a novel method developed to eradicate this bacterial contamination and is supported by compelling Level III evidence from multiple observational trials showing a dramatic reduction in infection rates without any evidence of increased graft failure. As such, it is time for this technique to become a universal recommendation? That said, as observational studies using a historical cohort as a comparator are at risk of various biases, Level I evidence is ultimately required for infection prophylaxis methods to be recognized as a universal recommendation in infection control guidelines. Consequently, future research endeavors on the "vancomycin wrap" should focus on randomized controlled trials, possibly nested within ACL registries.

Intrinsic patient factors predictive of inpatient rehabilitation facility discharge following primary total knee arthroplasty: a systematic review and meta-analysis.

BACKGROUND: Total Knee Arthroplasty (TKA) reduces pain and improves function in those suffering from severe osteoarthritis. A significant cost of TKA is post-acute care, however, current evidence suggests that discharge to an Inpatient Rehabilitation Facility (IRF) has inferior outcomes to home discharge, with no greater benefit in physical function. Only individual studies have investigated TKA patient characteristics predictive of discharge destination, therefore, the aim is to systematically review the literature and meta-analyse intrinsic patient factors predictive of IRF discharge. If predictive factors are known, then early discharge planning and intervention strategies could be implemented. METHODS: Databases PubMed, CINAHL, Embase, Cochrane, and Pedro were searched up to October 2019 for all studies investigating pre-operative intrinsic patient factors predictive of IRF discharge. For assessing the methodological quality of included studies, the Quality In Prognosis Studies (QUIPS) tool was used. Statistical analysis and graphical reporting were conducted in R statistical software. To assess the effect of predictors of discharge destination, odds ratios with the corresponding 95%CI were extracted from the results of univariate and multivariable analyses. RESULTS: A total of 9 articles published between 2011 to 2018 with 218,151 TKA patients were included. Of the 13 intrinsic patient factors reported, 6 met the criteria for synthesised review: age, obesity, comorbidity, gender, SF-12/VR-12 survey, and smoking. Due to the heterogeneity of statistical analysis and reporting 2 variables could undergo meta-analysis, gender and smoking. Female gender increased the likelihood of IRF discharge by 78% (OR = 1.78; 95%CI = 1.43-2.20; I2 = 33.3%), however, the relationship between smoking status and discharge destination was less certain (OR = 0.80; 95%CI = 0.42-1.50; I2 = 68.5%). CONCLUSION: In this systematic literature review and meta-analysis female gender was shown to be predictive of IRF discharge after total knee arthroplasty. There was also a trend for those of older age and increased comorbidity, as measured by the Charlson Comorbidity Index, or the severely obese to have an increased likelihood of IRF discharge. The marked heterogeneity of statistical methods and reporting in existing literature made pooled analysis challenging for intrinsic patient factors predictive of IRF discharge after TKA. Further, high quality studies of prospective design on predictive factors are warranted, to enable early discharge planning and optimise resource allocation on post-acute care following TKA. TRIAL REGISTRATION: This review was registered with PROSPERO ( CRD42019134422 ).

Which Patient Factors Best Predict Discharge Destination After Primary Total Knee Arthroplasty? The ARISE Trial.

BACKGROUND: The role of inpatient rehabilitation after total knee arthroplasty (TKA) remains uncertain, with evidence suggesting no better functional outcomes for those who discharge to rehabilitation to those who discharge home. The aim of this study is to develop and implement a pre-operative predictive tool, ARISE (Arthroplasty Rehabilitation Initial Screening Evaluation), that incorporated psychological, functional, and socio-demographic factors to determine discharge destination. METHODS: One week prior to TKA, the ARISE tool was administered to 100 patients, in addition to an EQ-5D-5L survey and other demographic data being recorded. The primary outcome was discharge destination. An enhanced recovery pathway, which included an anesthetic protocol designed to optimize early mobilization, was utilized. Univariable and multivariable logistic regression analysis was performed to determine the likelihood of discharge destination. RESULTS: Patients in the rehabilitation group were, on average, 4.5 years older than the home group (P = .036). After multivariable regression, ARISE questions were predictive of discharge destination related to beliefs around the superiority of inpatient rehabilitation (odds ratio = 9.9 [2.6-37.9]) and post-discharge level of support (odds ratio = 6.3 [1.5-26.8]). No question around self-reported physical function was predictive. CONCLUSION: Pre-operative patient beliefs regarding rehabilitation and future home support are highly predictive of discharge destination after primary TKA. Pre-operative patient-reported functional status and demographic variables, with the exception of increasing age, were not shown to be predictive. Predicting those that are most likely to discharge to rehabilitation allows for early, targeted interventions to optimize resources and increase likelihood of home discharge.

Similar Risk of Revision After Kinematically Aligned, Patient-Specific Instrumented Total Knee Arthroplasty, and All Other Total Knee Arthroplasty: Combined Results From the Australian and New Zealand Joint Replacement Registries.

BACKGROUND: Kinematic alignment (KA) in total knee arthroplasty (TKA) replicates individual knee joint line orientation and physiological soft tissue balance. There are limited data on the effect of KA on survivorship compared with other methods of implanting a TKA. The aim of this study was to compare the survivorship of the same design of TKA implanted with either patient-specific instrument (PSI) KA or with computer-assisted surgery and conventionally instrumented. METHODS: We performed an observational study of data from 2 national joint registries on all patients who underwent a TKA with a Triathlon cruciate-retaining TKA (Stryker, Mahwah, NJ) from January 2011 to December 31, 2013. The outcomes of knees performed with unrestricted KA using patient-specific instrument were compared with computer-assisted surgery and conventionally instrumented Triathlon cruciate-retaining TKA. The principal outcome measure was time to first revision using Kaplan-Meier estimates of survivorship. Cox proportional hazard ratios, adjusted for age and gender, were used to compare the 2 groups. RESULTS: There were 20,512 TKA procedures recorded, of which 416 were performed using KA-PSI. The KA-PSI group was younger (66.8 ± 8.2 vs 68.3 ± 9.2, P = .001), with an identical gender distribution. The cumulative revision rate at 7 years was 3.1% for the KA-PSI Triathlon cohort and 3.0% for the other Triathlon TKA cohort (P = .89). The most common reasons for revision in the KA-PSI group were maltracking, patella erosion, and arthrofibrosis. CONCLUSION: Kinematically aligned Triathlon TKA using PSI has similar revision rate as all other Triathlon TKA.

What is the evidence to support early supervised exercise therapy after primary total knee replacement? A systematic review and meta-analysis.

BACKGROUND: Total knee replacement (TKR) patients participate in early supervised exercise therapy programs, despite a lack of evidence for such programs or the optimal type, duration or frequency to provide the best clinical outcomes. As hospital stay rates decrease worldwide, the first days after joint replacement surgery are of increasing clinical importance. The purpose of this study was to investigate any reported effects of published early exercise therapy following TKR surgery. METHODS: Databases PubMed, CINAHL, Embase, Cochrane, and Pedro were searched up to August 2018 for trials which investigated an early supervised exercise therapy, commencing within 48 h of surgery. Risk of bias was evaluated using a Modified Downs and Black Checklist and meta-analysis of results was conducted using Review Manager (RevMan). Standardised Mean Differences (SMD) or Mean Differences (MD) and 95% confidence intervals were calculated and combined in meta-analyses. RESULTS: Four studies (323 patients) that used four different interventions were identified, including Modified Quadriceps Setting, Flexion Splinting, Passive Flexion Ranging and a Drop and Dangle Flexion regime. Patients receiving the Drop and Dangle flexion protocol had superior flexion in the first 2 days after TKR and at discharge, the Flexion Splint patients were discharged earlier and had greater flexion at 6-weeks postoperatively, and the Modified Quadriceps Setting group showed greater hamstring and gluteal muscle strength. Results of the methodological quality assessment showed included studies were of moderate quality. The meta-analysis included 3 of the 4 trials and found no significant differences between groups in maximum knee flexion (MD = 1.34; 95% CI, - 5.55-8.24) or knee society scores (MD = - 1.17; 95% CI, - 4.32-1.98) assessed at 6 weeks post-operatively. CONCLUSION: The paucity and heterogeneity of existing studies that examine early supervised exercise therapy following TKR surgery makes it challenging for clinicians to deliver high-quality evidence-based exercise programs in the early postoperative period. Although superior knee flexion range was found across differing regimes, the meta-analysis showed no significant difference in this outcome between groups at 6 weeks. The results of this review show high quality randomized clinical trials are urgently needed to evaluate the impact of early exercise following TKR surgery. TRIAL REGISTRATION: This review was registered with PROSPERO ( CRD42017081016 ).

Tibiofemoral joint structural change from 2.5 to 4.5 years following ACL reconstruction with and without combined meniscal pathology.

BACKGROUND: People who have had anterior cruciate ligament reconstruction (ACLR) are at a high risk of developing tibiofemoral joint (TFJ) osteoarthritis (OA), with concomitant meniscal injury elevating this risk. This study aimed to investigate OA-related morphological change over 2 years in the TFJ among individuals who have undergone ACLR with or without concomitant meniscal pathology and in healthy controls. A secondary aim was to examine associations of baseline TFJ cartilage defects and bone marrow lesions (BML) scores with tibial cartilage volume change in ACLR groups. METHODS: Fifty seven ACLR participants aged 18-40 years (32 isolated ACLR, 25 combined meniscal pathology) underwent knee magnetic resonance imaging (MRI) 2.5 and 4.5 years post-surgery. Nine healthy controls underwent knee MRI at the ~ 2-year intervals. Tibial cartilage volume, TFJ cartilage defects and BMLs were assessed from MRI. RESULTS: For both ACLR groups, medial and lateral tibial cartilage volume increased over 2 years (P <  0.05). Isolated ACLR group had greater annual percentage increase in lateral tibial cartilage volume compared with controls and with the combined group (P = 0.03). Cartilage defects remained unchanged across groups. Both ACLR groups showed more lateral tibia BML regression compared with controls (P = 0.04). Baseline cartilage defects score was positively associated with cartilage volume increase at lateral tibia (P = 0.002) while baseline BMLs score was inversely related to medial tibia cartilage volume increase (P = 0.001) in the pooled ACLR group. CONCLUSIONS: Tibial cartilage hypertrophy was apparent in ACLR knees from 2.5 to 4.5 years post-surgery and was partly dependent upon meniscal status together with the nature and location of the underlying pathology at baseline. Magnitude and direction of change in joint pathologies (i.e., cartilage defects, BMLs) were less predictable and either remained stable or improved over follow-up.

An optimum prosthesis combination of low-risk total knee arthroplasty options in all five primary categories of design results in a 60% reduction in revision risk: a registry analysis of 482,373 prostheses.

PURPOSE: Decades of innovations in total knee arthroplasty (TKA) design have led to large number of possible prosthesis combinations in regards fixation, posterior stability, bearing mobility, bearing surface, and patella resurfacing, each of which can alter the revision risk. The accumulative effect when the lowest risk combination in each design category, or "Optimum Prosthesis Combination" (OPC) is utilized remains unknown. The purpose of this analysis was to first, identify the OPC and second, to compare the revision risk of a cohort who received the OPC to a cohort who received an Alternative Prosthesis Combination (APC). METHODS: National registry revision risk data for primary TKA for osteoarthritis were obtained from September 1999 to December 2015 for two patient cohorts, those receiving an OPC and those receiving an APC. OPC was defined as TKA with the lowest revision risk option for five primary TKA design categories; fixation, posterior stability, bearing mobility, bearing surface, and patella resurfacing, while APC had one or more higher risk options. RESULTS: Of the 482,373 included TKA, 42,008 (8.7%) were in the OPC cohort, who received a minimally stabilized, fixed bearing TKA with cross-linked polyethylene with patella resurfacing. Both cohorts had similar demographics. At 10 years, the OPC cohort had a Cumulative Percent Revision of 2.4% (95% CI 2.1, 2.8) compared to 5.5% (95% CI 5.4, 5.6) for the APC cohort. For all patients, revision risk of the APC cohort was higher at all times [151% greater at ≥ 3 years (p < 0.001)]. Loosening/lysis was the most common cause of revision in the ACP cohort (1.1%), while it was the second most common cause in the OPC cohort (0.3%). The increased risk was apparent in all age and gender subgroups, with the highest risk increase seen in males ≥ 65 years. CONCLUSIONS: Patients receiving the lowest risk prosthesis design combination or Optimum Prosthesis Combination TKA had a 60% lower revision risk, with similar demographics to the Alternative Prosthesis Combination TKA. LEVEL OF EVIDENCE: III.

Greater magnitude tibiofemoral contact forces are associated with reduced prevalence of osteochondral pathologies 2-3 years following anterior cruciate ligament reconstruction.

PURPOSE: External loading of osteoarthritic and healthy knees correlates with current and future osteochondral tissue state. These relationships have not been examined following anterior cruciate ligament reconstruction. We hypothesised greater magnitude tibiofemoral contact forces were related to increased prevalence of osteochondral pathologies, and these relationships were exacerbated by concomitant meniscal injury. METHODS: This was a cross-sectional study of 100 individuals (29.7 ± 6.5 years, 78.1 ± 14.4 kg) examined 2-3 years following hamstring tendon anterior cruciate ligament reconstruction. Thirty-eight participants had concurrent meniscal pathology (30.6 ± 6.6 years, 83.3 ± 14.3 kg), which included treated and untreated meniscal injury, and 62 participants (29.8 ± 6.4 years, 74.9 ± 13.3 kg) were free of meniscal pathology. Magnetic resonance imaging of reconstructed knees was used to assess prevalence of tibiofemoral osteochondral pathologies (i.e., cartilage defects and bone marrow lesions). A calibrated electromyogram-driven neuromusculoskeletal model was used to predict medial and lateral tibiofemoral compartment contact forces from gait analysis data. Relationships between contact forces and osteochondral pathology prevalence were assessed using logistic regression models. RESULTS: In patients with reconstructed knees free from meniscal pathology, greater medial contact forces were related to reduced prevalence of medial cartilage defects (odds ratio (OR) = 0.7, Wald χ2(2) = 7.9, 95% confidence interval (CI) = 0.50-95, p = 0.02) and medial bone marrow lesions (OR = 0.8, Wald χ2(2) = 4.2, 95% CI = 0.7-0.99, p = 0.04). No significant relationships were found in lateral compartments. In reconstructed knees with concurrent meniscal pathology, no relationships were found between contact forces and osteochondral pathologies. CONCLUSIONS: In patients with reconstructed knees free from meniscal pathology, increased contact forces were associated with fewer cartilage defects and bone marrow lesions in medial, but not, lateral tibiofemoral compartments. No significant relationships were found between contact forces and osteochondral pathologies in reconstructed knees with meniscal pathology for any tibiofemoral compartment. Future studies should focus on determining longitudinal effects of contact forces and changes in osteochondral pathologies. LEVEL OF EVIDENCE: IV.

Increasing rates of anterior cruciate ligament reconstruction in young Australians, 2000-2015.

OBJECTIVES: To investigate the incidence and demographic features of anterior cruciate ligament (ACL) reconstructions in Australia by age and sex, and to determine whether the incidence has changed during the past 15 years. DESIGN AND SETTING: Descriptive epidemiological analysis of longitudinal data on ACL reconstructions (July 2000 - June 2015) in the National Hospital Morbidity Database. MAIN OUTCOME MEASURES: Population ACL reconstruction rates, by age group and sex. RESULTS: 197 557 primary ACL reconstructions were performed during the study period; the annual incidence increased by 43% (from 54.0 to 77.4 per 100 000 population), and by 74% among those under 25 years of age (from 52.6 to 91.4 per 100 000 population). In males, the peak incidence in 2014-15 was for 20-24-year-olds (283 per 100 000 population); for females, it was for 15-19-year-olds (164 per 100 000 population). Annual growth in incidence was greatest in the 5-14-year-old age group (boys, 7.7%; girls, 8.8%). Direct hospital costs of ACL reconstruction surgery in 2014-15 were estimated to be $142 million. The annual incidence of revision ACL reconstructions increased from 2.49 (2000-01) to 5.65 per 100 000 population (2014-15), or by 5.6% per year; revisions as a proportion of all ACL reconstruction increased from 4.4% to 6.8%. CONCLUSIONS: The increasing incidence of ACL reconstructions in young Australians over 15 years is worrying. The individuals at greatest risk are men aged 20-24 years and women aged 15-19 years; the rate of reconstruction is increasing most rapidly among those aged 5-14 years. Revision rates are increasing more rapidly than those of primary reconstructions.

Comparison of four alternative national universal anterior cruciate ligament injury prevention programme implementation strategies to reduce secondary future medical costs.

BACKGROUND/AIM: Anterior cruciate ligament (ACL) injury is a common and devastating sporting injury. With or without ACL reconstruction, the risk of knee osteoarthritis (OA) and permanent disability later in life is markedly increased. While neuromuscular training programmes can prevent 50-80% of ACL injuries, no national implementation strategies exist in Australia. The aim of this study was to compare the ability of four alternative national universal ACL injury prevention programme implementation strategies to reduce future medical costs secondary to ACL injury. METHODS: A Markov economic decision model was constructed to estimate the value in lifetime future medical costs prevented by implementing a national ACL prevention programme among four hypothetical cohorts: high-risk sport participants (HR) aged 12-25 years; HR 18-25 years; HR 12-17 years; all youths (ALL) 12-17 years. RESULTS: Of the four programmes examined, the HR 12-25 programme provided the greatest value, averting US$693 of direct healthcare costs per person per lifetime or US$221 870 880 in total. Without training, 9.4% of this cohort will rupture their ACL and 16.8% will develop knee OA. Training prevents 3764 lifetime ACL ruptures per 100 000 individuals, a 40% reduction in ACL injuries. 842 lifetime cases of OA per 100 000 individuals and 584 TKRs per 100 000 are subsequently averted. Numbers needed to treat ranged from 27 for the HR 12-25 to 190 for the ALL 12-17. CONCLUSIONS: The HR 12-25 programme was the most effective implementation strategy. Estimation of the break-even cost of health expenditure savings will enable optimal future programme design, implementation and expenditure.

The effect of surgeon's preference for hybrid or cemented fixation on the long-term survivorship of total knee replacement.

Background and purpose - Recent direct comparative reports suggest that hybrid fixation may have a similar or superior outcome to cemented fixation in total knee replacement (TKR); however, a paucity of long-term data exists. To minimize the confounders of a direct comparison, we performed an instrumental variable analysis examining the revision rate of 2 cohorts of patients based on their surgeon's preference for cemented or hybrid fixation. Methods - Registry data were obtained from 1999 until 2015 for 2 cohorts of patients who received minimally stabilized TKR, defined as those treated by high-volume hybrid fixation preferring surgeons, designated routinely hybrid (RH), and those treated by high-volume cemented fixation preferring surgeons, designated routinely cemented (RC). Results - At 13 years, the cumulative percentage revision of the RC cohort was 4.8% (CI 4.1-5.7) compared with 5.5% (CI 3.5-8.7) for the RH cohort. The revision risk for each cohort was the same for all causes (HR =1.0 (CI (0.84-1.20)), non-infective causes, and for infection. This finding was irrespective of patient age or sex, patella resurfacing, and with non-cross-linked polyethylene (NXLPE). The RH cohort who received cross-linked polyethylene (XLPE) had a lower revision risk than the RC cohort with XLPE (HR =0.57 (0.37-0.88), p = 0.01). Interpretation - The risk of revision for the patients of surgeons who prefer cemented fixation in minimally stabilized TKR is the same as for the patients of surgeons who prefer hybrid fixation, except when used with XLPE, where hybrid fixation has a lower revision risk.

Can tape-screw fixation of a quadrupled semitendinosus graft in a full-length tibial tunnel provide superior fixation compared with a doubled semitendinosus-gracilis held with an interference screw? A matched-pair cadaveric biomechanical comparison.

BACKGROUND: In anterior cruciate ligament reconstruction, quadrupled semitendinosus (Quad ST) grafts have potential advantages over doubled semitendinosus-gracilis (ST/G) including larger diameter and gracilis preservation, however the ideal tibial fixation method of the resultant shorter Quad ST graft remains elusive if a fixed-loop suspensory fixation device is used on the femur. We investigated whether the tibial fixation biomechanical properties of a Quad ST fixed indirectly with polyethylene terephthalate tape tied over a screw in a full outside-in created tunnel was superior to a ST/G graft fixed with an interference screw. MATERIALS AND METHODS: In a controlled laboratory study, six cadaveric matched pairs of each construct were subjected to cyclic loading to mimic physiologic loading during rehabilitation. This included preconditioning cycling, cyclic loading to 220 N for 500 cycles, then cyclic loading to 500 N for 500 cycles. RESULTS: High standard deviations across the measured parameters occurred with no significant difference between measured parameters of elongation for the different constructs. Elongation of the Quad-ST construct was greater at 10 and 100 cycles, but not statistically different. Four of the six Quad-ST constructs failed below 100 cycles, compared with two failures below 100 cycles in the ST/G construct. There was a strong correlation between cycles to failure and bone mineral density for the Quad ST-tape constructs. CONCLUSIONS: Tibial fixation of Quad ST with a tied tape-screw construct in a full-length tunnel was not biomechanically superior to ST/G graft fixed with an interference screw, exhibited greater nonsignificant construct elongation with earlier failure, and was more reliant on bone mineral density. LEVEL OF EVIDENCE: In vitro laboratory study.