Expression of Chondrogenic Potential Markers in Cultured Chondrocytes from the Human Knee Joint.

OBJECTIVES: While substantial progress has been made in engineering cartilaginous constructs for animal models, further research is needed to translate these methodologies for human applications. Evidence suggests that cultured autologous chondrocytes undergo changes in phenotype and gene expression, thereby affecting their proliferation and differentiation capacity. This study was designed to evaluate the expression of chondrogenic markers in cultured human articular chondrocytes from passages 3 (P3) and 7 (P7), beyond the current clinical recommendation of P3. METHODS: Cultured autologous chondrocytes were passaged from P3 up to P7, and quantitative polymerase chain reaction (qPCR) was used to assess mRNA expression of chondrogenic markers, including collagen type I (COLI), collagen type II (COLII), aggrecan (AGG), bone morphogenetic protein 4 (BMP4), transcription factor SOX-9 (SOX9), proteoglycan 4 (PGR4), and transformation-related protein 53 (p53), between P3 and P7. RESULTS: Except for AGG, no significant differences were found in the expression of markers between passages, suggesting the maintenance of chondrogenic potential in cultured chondrocytes. Differential expression identified between SOX9 and PGR4, as well as between COLI and SOX9, indicates that differences in chondrogenic markers are present between age groups and sexes, respectively. CONCLUSIONS: Overall, expression profiles of younger and male chondrocytes exhibit conversion of mature cartilage characteristics compared to their counterparts, with signs of dedifferentiation and loss of phenotype within-group passaging. These results may have implications in guiding the use of higher passaged chondrocytes for engineering constructs and provide a foundation for clinical recommendations surrounding the repair and treatment of articular cartilage pathology in both sexes.

Anterior Cruciate Ligament Reconstruction Plus Lateral Extra-articular Tenodesis Has a Similar Return-to-Sport Rate to Anterior Cruciate Ligament Reconstruction Alone but a Lower Failure Rate.

PURPOSE: To determine whether the addition of lateral extra-articular tenodesis (LET) to anterior cruciate ligament reconstruction (ACLR) would improve return-to-sport (RTS) rates in young, active patients who play high-risk sports. METHODS: This multicenter randomized controlled trial compared standard hamstring tendon ACLR with combined ACLR and LET using a strip of the iliotibial band (modified Lemaire technique). Patients aged 25 years or younger with an anterior cruciate ligament-deficient knee were included. Patients also had to meet 2 of the following criteria: (1) pivot-shift grade 2 or greater, (2) participation in a high-risk or pivoting sport, and (3) generalized ligamentous laxity. Time to return and level of RTS were determined via administration of a questionnaire at 24 months postoperatively. RESULTS: We randomized 618 patients in this study, 553 of whom played high-risk sports preoperatively. The proportion of patients who did not RTS was similar between the ACLR (11%) and ACLR-LET (14%) groups; however, the graft rupture rate was significantly different (11.2% in ACLR group vs 4.1% in ACLR-LET group, P = .004). The most cited reason for no RTS was lack of confidence and/or fear of reinjury. A stable knee was associated with nearly 2 times greater odds of returning to a high-level high-risk sport postoperatively (odds ratio, 1.92; 95% confidence interval, 1.11-3.35; P = .02). There were no significant differences in patient-reported functional outcomes or hop test results between groups (P > .05). Patients who returned to high-risk sports had better hamstring symmetry than those who did not RTS (P = .001). CONCLUSIONS: At 24 months postoperatively, patients who underwent ACLR plus LET had a similar RTS rate to those who underwent ACLR alone. Although the subgroup analysis did not show a statistically significant increase in RTS with the addition of LET, on returning, the addition of LET kept subjects playing longer by reducing graft failure rates. LEVEL OF EVIDENCE: Level I, randomized controlled trial.

Predictors of Graft Failure in Young Active Patients Undergoing Hamstring Autograft Anterior Cruciate Ligament Reconstruction With or Without a Lateral Extra-articular Tenodesis: The Stability Experience.

BACKGROUND: Anterior cruciate ligament (ACL) reconstruction (ACLR) has higher failure rates in young active patients returning to sports as compared with older, less active individuals. Augmentation of ACLR with an anterolateral procedure has been shown to reduce failure rates; however, indications for this procedure have yet to be clearly defined. PURPOSE/HYPOTHESIS: The purpose of this study was to identify predictors of ACL graft failure in high-risk patients and determine key indications for when hamstring ACLR should be augmented by a lateral extra-articular tenodesis (LET). We hypothesized that different preoperative characteristics and surgical variables may be associated with graft failure characterized by asymmetric pivot shift and graft rupture. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: Data were obtained from the Stability 1 Study, a multicenter randomized controlled trial of young active patients undergoing autologous hamstring ACLR with or without a LET. We performed 2 multivariable logistic regression analyses, with asymmetric pivot shift and graft rupture as the dependent variables. The following were included as predictors: LET, age, sex, graft diameter, tear chronicity, preoperative high-grade knee laxity, preoperative hyperextension on the contralateral side, medial meniscal repair/excision, lateral meniscal repair/excision, posterior tibial slope angle, and return-to-sports exposure time and level. RESULTS: Of the 618 patients in the Stability 1 Study, 568 with a mean age of 18.8 years (292 female; 51.4%) were included in this analysis. Asymmetric pivot shift occurred in 152 (26.8%) and graft rupture in 43 (7.6%). The addition of a LET (odds ratio [OR], 0.56; 95% CI, 0.37-0.83) and increased graft diameter (OR, 0.62; 95% CI, 0.44-0.87) were significantly associated with lower odds of asymmetric pivot shift. The addition of a LET (OR, 0.40; 95% CI, 0.18-0.91) and older age (OR, 0.83; 95% CI, 0.72-0.96) significantly reduced the odds of graft rupture, while greater tibial slope (OR, 1.15; 95% CI, 1.01-1.32), preoperative high-grade knee laxity (OR, 3.27; 95% CI, 1.45-7.41), and greater exposure time to sport (ie, earlier return to sport) (OR, 1.18; 95% CI, 1.08-1.29) were significantly associated with greater odds of rupture. CONCLUSION: The addition of a LET and larger graft diameter were significantly associated with reduced odds of asymmetric pivot shift. Adding a LET was protective of graft rupture, while younger age, greater posterior tibial slope, high-grade knee laxity, and earlier return to sport were associated with increased odds of graft rupture. Orthopaedic surgeons should consider supplementing hamstring autograft ACLR with a LET in young active patients with morphological characteristics that make them at high risk of reinjury.

Effect of nutrient metabolism on cartilaginous tissue formation.

A major shortcoming in cartilage tissue engineering is the low biosynthetic response of chondrocytes. While different strategies have been investigated, a novel approach may be to control nutrient metabolism. Although known for their anaerobic metabolism, chondrocytes are more synthetically active under conditions that elicit mixed aerobic-anaerobic metabolism. Here, we postulate this metabolic switch induces HIF-1α signaling resulting in improved growth. Transition to different metabolic states can result in the pooling of metabolites, several of which can stabilize HIF-1α by interfering with PHD2. Chondrocytes cultured under increased media availability accelerated tissue deposition with the greatest effect occurring at 2 ml/106 cells. Under higher media availability, metabolism switched from anaerobic to mixed aerobic-anaerobic. Around this transition, maximal changes in PHD2 activity, HIF-1α expression, and HIF-1 target gene expression were observed. Loss-of-function studies using YC-1 confirmed the involvement of HIF-1. Lastly, targeted metabolomic studies revealed that intracellular lactate and succinate correlated with PHD2 activity. This study demonstrates that cartilaginous tissue formation can be regulated by nutrient metabolism and that this response is mediated through changes in HIF-1α signaling. By harnessing this newly identified metabolic switch, engineered cartilage implants may be developed without the need for sophisticated methods which could aid translation to the clinic.

Association of Ligamentous Laxity, Male Sex, Chronicity, Meniscal Injury, and Posterior Tibial Slope With a High-Grade Preoperative Pivot Shift: A Post Hoc Analysis of the STABILITY Study.

BACKGROUND: A spectrum of anterolateral rotatory laxity exists in anterior cruciate ligament (ACL)-injured knees. Understanding of the factors contributing to a high-grade pivot shift continues to be refined. PURPOSE: To investigate factors associated with a high-grade preoperative pivot shift and to evaluate the relationship between this condition and baseline patient-reported outcome measures (PROMs). STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A post hoc analysis was performed of 618 patients with ACL deficiency deemed high risk for reinjury. A binary logistic regression model was developed, with high-grade pivot shift as the dependent variable. Age, sex, Beighton score, chronicity of the ACL injury, posterior third medial or lateral meniscal injury, and tibial slope were selected as independent variables. The importance of knee hyperextension as a component of the Beighton score was assessed using receiver operator characteristic curves. Baseline PROMs were compared between patients with and without a high-grade pivot. RESULTS: Six factors were associated with a high-grade pivot shift: Beighton score (each additional point; odds ratio [OR], 1.17; 95% CI, 1.06-1.30; P = .002), male sex (OR, 2.30; 95% CI, 1.28-4.13; P = .005), presence of a posterior third medial (OR, 2.55; 95% CI, 1.11-5.84; P = .03) or lateral (OR, 1.76; 95% CI, 1.01-3.08; P = .048) meniscal injury, tibial slope >9° (OR, 2.35; 95% CI, 1.09-5.07; P = .03), and chronicity >6 months (OR, 1.70; 95% CI, 1.00-2.88; P = .049). The presence of knee hyperextension improved the diagnostic utility of the Beighton score as a predictor of a high-grade pivot shift. Tibial slope <9° was associated with only a high-grade pivot in the presence of a posterior third medial meniscal injury. Patients with a high-grade pivot shift had higher baseline 4-Item Pain Intensity Measure scores than did those without a high-grade pivot shift (mean ± SD, 11 ± 13 vs 8 ± 14; P = .04); however, there was no difference between groups in baseline International Knee Documentation Committee, ACL Quality of Life, Knee injury and Osteoarthritis Outcome Score, or Knee injury and Osteoarthritis Outcome Score subscale scores. CONCLUSION: Ligamentous laxity, male sex, posterior third medial or lateral meniscal injury, increased posterior tibial slope, and chronicity were associated with a high-grade pivot shift in this population deemed high risk for repeat ACL injury. The effect of tibial slope may be accentuated by the presence of meniscal injury, supporting the need for meniscal preservation. Baseline PROMs were similar between patients with and without a high-grade pivot shift.

Lateral Extra-articular Tenodesis Reduces Failure of Hamstring Tendon Autograft Anterior Cruciate Ligament Reconstruction: 2-Year Outcomes From the STABILITY Study Randomized Clinical Trial.

BACKGROUND: Persistent anterolateral rotatory laxity after anterior cruciate ligament (ACL) reconstruction (ACLR) has been correlated with poor clinical outcomes and graft failure. HYPOTHESIS: We hypothesized that a single-bundle, hamstring ACLR in combination with a lateral extra-articular tenodesis (LET) would reduce the risk of ACLR failure in young, active individuals. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: This is a multicenter, prospective, randomized clinical trial comparing a single-bundle, hamstring tendon ACLR with or without LET performed using a strip of iliotibial band. Patients 25 years or younger with an ACL-deficient knee were included and also had to meet at least 2 of the following 3 criteria: (1) grade 2 pivot shift or greater, (2) a desire to return to high-risk/pivoting sports, (3) and generalized ligamentous laxity (GLL). The primary outcome was ACLR clinical failure, a composite measure of rotatory laxity or a graft rupture. Secondary outcome measures included the P4 pain scale, Marx Activity Rating Scale, Knee injury Osteoarthritis and Outcome Score (KOOS), International Knee Documentation Committee score, and ACL Quality of Life Questionnaire. Patients were reviewed at 3, 6, 12, and 24 months postoperatively. RESULTS: A total of 618 patients (297 males; 48%) with a mean age of 18.9 years (range, 14-25 years) were randomized. A total of 436 (87.9%) patients presented preoperatively with high-grade rotatory laxity (grade 2 pivot shift or greater), and 215 (42.1%) were diagnosed as having GLL. There were 18 patients lost to follow-up and 11 who withdrew (~5%). In the ACLR group, 120/298 (40%) patients sustained the primary outcome of clinical failure, compared with 72/291 (25%) in the ACLR+LET group (relative risk reduction [RRR], 0.38; 95% CI, 0.21-0.52; P < .0001). A total of 45 patients experienced graft rupture, 34/298 (11%) in the ACLR group compared with 11/291 (4%) in the ACL+LET group (RRR, 0.67; 95% CI, 0.36-0.83; P < .001). The number needed to treat with LET to prevent 1 patient from graft rupture was 14.3 over the first 2 postoperative years. At 3 months, patients in the ACLR group had less pain as measured by the P4 (P = .003) and KOOS (P = .007), with KOOS pain persisting in favor of the ACLR group to 6 months (P = .02). No clinically important differences in patient-reported outcome measures were found between groups at other time points. The level of sports activity was similar between groups at 2 years after surgery, as measured by the Marx Activity Rating Scale (P = .11). CONCLUSION: The addition of LET to a single-bundle hamstring tendon autograft ACLR in young patients at high risk of failure results in a statistically significant, clinically relevant reduction in graft rupture and persistent rotatory laxity at 2 years after surgery. REGISTRATION: NCT02018354 ( ClinicalTrials.gov identifier).

High-energy trauma patients with pelvic fractures: Management trends in Ontario, Canada.

INTRODUCTION: Although fractures of the pelvic ring account for only 2-3% of all fractures, they are present in approximately 7-20% of patients with high-energy polytrauma. High-energy pelvic fractures are life-threatening injuries, with mortality estimates ranging from 6 to 35%. The purpose of this study was to examine trends in the incidence, diagnosis, treatment, and mortality rates of high-energy pelvic fractures in Ontario, Canada over a 10-year period. METHODS: A cohort of 3915 patients who sustained a high-energy pelvic fracture in Ontario between 01 April 2005 and 31 March 2015 was identified using the Ontario Trauma Registry and administrative healthcare data linked by the Institute for Clinical Evaluative Science (ICES). Severely injured patients (defined as having an Injury Severity Score (ISS) of ≥16) with pelvic fractures following high-velocity mechanisms of injury were identified using applicable ICD-10 codes. Trends were assessed statistically using the Poisson and the Cochrane-Armitage tests for trend. Modified Poisson regression was used to model the adjusted risk ratio of mortality by pelvic fracture treatment. RESULTS: The incidence of pelvic fracture remained constant at approximately 4.6 cases per 100,000 population annually between 2005 and 2011. From 2012, there was a decrease in patients with ISS ≥ 16 due to changes in the calculation of the ISS. The proportion of patients presenting with ISS > 50 increased from 8.2% to 14.1% (p = 0.008) over the study period. Automobile collisions or pedestrians struck by vehicles accounted for over half of injuries. Approximately 6% of patients underwent angioembolisation. Treatment with external fixation (15.5%-20.2%) or no surgical intervention (46.2%-61.3%) increased from 2005 to 2015. Mortality remained constant (11% at 30 days), and laparotomy was the only major intervention not associated with decreased risk of death. CONCLUSIONS: Stable mortality despite increasing injury severity suggests that the quality of care provided to patients with high-energy pelvic fractures has improved over time. However, unchanged incidence suggests the need for ongoing efforts aimed towards injury prevention. ISS at presentation was the most significant predictor of mortality in this patient population.

Virtual Reality Compared with Bench-Top Simulation in the Acquisition of Arthroscopic Skill: A Randomized Controlled Trial.

BACKGROUND: Work-hour restrictions as set forth by the Accreditation Council for Graduate Medical Education (ACGME) and other governing bodies have forced training programs to seek out new learning tools to accelerate acquisition of both medical skills and knowledge. As a result, competency-based training has become an important part of residency training. The purpose of this study was to directly compare arthroscopic skill acquisition in both high-fidelity and low-fidelity simulator models and to assess skill transfer from either modality to a cadaveric specimen, simulating intraoperative conditions. METHODS: Forty surgical novices (pre-clerkship-level medical students) voluntarily participated in this trial. Baseline demographic data, as well as data on arthroscopic knowledge and skill, were collected prior to training. Subjects were randomized to 5-week independent training sessions on a high-fidelity virtual reality arthroscopic simulator or on a bench-top arthroscopic setup, or to an untrained control group. Post-training, subjects were asked to perform a diagnostic arthroscopy on both simulators and in a simulated intraoperative environment on a cadaveric knee. A more difficult surprise task was also incorporated to evaluate skill transfer. Subjects were evaluated using the Global Rating Scale (GRS), the 14-point arthroscopic checklist, and a timer to determine procedural efficiency (time per task). Secondary outcomes focused on objective measures of virtual reality simulator motion analysis. RESULTS: Trainees on both simulators demonstrated a significant improvement (p < 0.05) in arthroscopic skills compared with baseline scores and untrained controls, both in and ex vivo. The virtual reality simulation group consistently outperformed the bench-top model group in the diagnostic arthroscopy crossover tests and in the simulated cadaveric setup. Furthermore, the virtual reality group demonstrated superior skill transfer in the surprise skill transfer task. CONCLUSIONS: Both high-fidelity and low-fidelity simulation trainings were effective in arthroscopic skill acquisition. High-fidelity virtual reality simulation was superior to bench-top simulation in the acquisition of arthroscopic skills, both in the laboratory and in vivo. Further clinical investigation is needed to interpret the importance of these results.

Anatomical Evaluation of the Proximity of Neurovascular Structures During Arthroscopically Assisted Acromioclavicular Joint Reconstruction: A Cadaveric Pilot Study.

PURPOSE: The purpose of this study was to examine the safety of an arthroscopic technique for acromioclavicular joint (ACJ) reconstruction by investigating its proximity to important neurovascular structures. METHODS: Six shoulders from 4 cadaveric specimens were used for ACJ reconstruction in this study. The procedure consists of performing an arthroscopic acromioclavicular (AC) reduction with a double button construct, followed by coracoclavicular ligament reconstruction without drilling clavicular tunnels. Shoulders were subsequently dissected in order to identify and measure distances to adjacent neurovascular structures. RESULTS: The suprascapular artery and nerve were the closest neurovascular structures to implanted materials. The mean distances were 8.2 (standard deviation [SD] = 3.6) mm to the suprascapular nerve and 5.6 (SD = 4.2) mm to the suprascapular artery. The mean distance of the suprascapular nerve from implants was found to be greater than 5 mm (P = .040), while the distance to the suprascapular artery was not (P > .5). Neither difference was statistically significant (P = .80 for artery; P = .08 for nerve). CONCLUSIONS: Mini-open, arthroscopically assisted ACJ reconstruction safely avoids the surrounding nerves, with no observed damage to any neurovascular structures including the suprascapular nerve and artery, and may be a viable alternative to open techniques. However, surgeons must remain cognizant of possible close proximity to the suprascapular artery. CLINICAL RELEVANCE: This study represents an evaluation of the safety and feasibility of a minimally invasive ACJ reconstruction as it relates to the proximity of neurovascular structures.

Using an accelerometer and the step-up-and-over test to evaluate the knee function of patients with anterior cruciate ligament reconstruction.

BACKGROUND: Evaluating the dynamic knee function of patients after anterior cruciate ligament reconstruction is a challenge. A variety of objective tests have been developed but for various reasons few are regularly used in the clinic. It may be practical to perform the step-up-and-over test with an accelerometer. METHODS: A control group (N=26) and an experimental group with a reconstructed anterior cruciate ligament (N=25) completed questionnaires quantifying subjective knee function and fear of re-injury and then completed the step-up-and-over test. FINDINGS: Results showed that the experimental group performed differently than the control group for the step-up-and-over test's Lift Symmetry and Impact Symmetry (P<0.05) and performance on these measures was related to the participant's subjective knee function (ρ=-0.46, P<0.01; ρ=-0.33, P<0.05, respectively). Supplemental results for individual leg performance and the patient's fear of re-injury are also reported and discussed. INTERPRETATION: Performance on the step-up-and-over test is different for participants with anterior cruciate ligament reconstruction than for those with intact anterior cruciate ligaments, and that performance is related to one's opinion of their knee's function.

Consistency of strength curves for determining maximal effort production during isokinetic knee testing of anterior cruciate ligament-deficient patients.

The purpose of this investigation was to attempt to establish decision rules for determining maximal effort production during isokinetic strength testing of unilateral anterior cruciate ligament-deficient patients based on the degree of strength curve consistency within a set. Thirty-three participants performed six bilateral knee extension and flexion exertions at maximal effort and at 80% of perceived maximum at testing velocities of 60 and 180°s(-1). Within-set consistency was quantified by computation of the variance ratio across strength curves. Tolerance interval-based cutoff scores covering 99% of the population were calculated for declaring efforts as being maximal or not at confidence levels of 90%, 95%, and 99%. The sensitivity percentages attained for the injured knee for both testing velocities ranged between 9.1% and 27.2%, while specificity percentages ranged between 84.8% and 100%. For the non-injured knee, sensitivity values for both testing velocities ranged between 21.2% and 45.0%, while specificity percentages ranged between 97.0% and 100%. The developed decision rules do not effectively discriminate on an individual patient basis between maximal and non-maximal isokinetic knee musculature efforts. Further research is needed for development of methods that would enable to ascertain maximal effort production in this patient population during knee muscle strength testing.

Global Rating Scales and Motion Analysis Are Valid Proficiency Metrics in Virtual and Benchtop Knee Arthroscopy Simulators.

BACKGROUND: Work-hour restrictions and fatigue management strategies in surgical training programs continue to evolve in an effort to improve the learning environment and promote safer patient care. In response, training programs must reevaluate how various teaching modalities such as simulation can augment the development of surgical competence in trainees. For surgical simulators to be most useful, it is important to determine whether surgical proficiency can be reliably differentiated using them. To our knowledge, performance on both virtual and benchtop arthroscopy simulators has not been concurrently assessed in the same subjects. QUESTIONS/PURPOSES: (1) Do global rating scales and procedure time differentiate arthroscopic expertise in virtual and benchtop knee models? (2) Can commercially available built-in motion analysis metrics differentiate arthroscopic expertise? (3) How well are performance measures on virtual and benchtop simulators correlated? (4) Are these metrics sensitive enough to differentiate by year of training? METHODS: A cross-sectional study of 19 subjects (four medical students, 12 residents, and three staff) were recruited and divided into 11 novice arthroscopists (student to Postgraduate Year [PGY] 3) and eight proficient arthroscopists (PGY 4 to staff) who completed a diagnostic arthroscopy and loose-body retrieval in both virtual and benchtop knee models. Global rating scales (GRS), procedure times, and motion analysis metrics were used to evaluate performance. RESULTS: The proficient group scored higher on virtual (14 ± 6 [95% confidence interval {CI}, 10-18] versus 36 ± 5 [95% CI, 32-40], p < 0.001) and benchtop (16 ± 8 [95% CI, 11-21] versus 36 ± 5 [95% CI, 31-40], p < 0.001) GRS scales. The proficient subjects completed nearly all tasks faster than novice subjects, including the virtual scope (579 ±169 [95% CI, 466-692] versus 358 ± 178 [95% CI, 210-507] seconds, p = 0.02) and benchtop knee scope + probe (480 ± 160 [95% CI, 373-588] versus 277 ± 64 [95% CI, 224-330] seconds, p = 0.002). The built-in motion analysis metrics also distinguished novices from proficient arthroscopists using the self-generated virtual loose body retrieval task scores (4 ± 1 [95% CI, 3-5] versus 6 ± 1 [95% CI, 5-7], p = 0.001). GRS scores between virtual and benchtop models were very strongly correlated (ρ = 0.93, p < 0.001). There was strong correlation between year of training and virtual GRS (ρ = 0.8, p < 0.001) and benchtop GRS (ρ = 0.87, p < 0.001) scores. CONCLUSIONS: To our knowledge, this is the first study to evaluate performance on both virtual and benchtop knee simulators. We have shown that subjective GRS scores and objective motion analysis metrics and procedure time are valid measures to distinguish arthroscopic skill on both virtual and benchtop modalities. Performance on both modalities is well correlated. We believe that training on artificial models allows acquisition of skills in a safe environment. Future work should compare different modalities in the efficiency of skill acquisition, retention, and transferability to the operating room.

Structured simulation improves learning of the Fundamental Use of Surgical Energy™ curriculum: a multicenter randomized controlled trial.

BACKGROUND: Energy devices can result in devastating complications to patients. Yet, they remain poorly understood by trainees and surgeons. A single-institution pilot study suggested that structured simulation improves knowledge of the safe use of electrosurgery (ES) among trainees (Madani et al. in Surg Endosc 28(10):2772-2782, 2014). The purpose of this study was to estimate the extent to which the addition of this structured bench-top simulation improves ES knowledge across multiple surgical training programs. METHODS: Trainees from 11 residency programs in Canada, the USA and UK participated in a 1-h didactic ES course, based on SAGES' Fundamental Use of Surgical Energy™ (FUSE) curriculum. They were then randomized to one of two groups: an unstructured hands-on session where trainees used ES devices (control group) or a goal-directed hands-on training session (Sim group). Pre- and post-curriculum (immediately and 3 months after) knowledge of the safe use of ES was assessed using separate examinations. Data are expressed as mean (SD) and N (%), *p < 0.05. RESULTS: A total of 289 (145 control; 144 Sim) trainees participated, with 186 (96 control; 90 Sim) completing the 3-month assessment. Baseline characteristics were similar between the two groups. Total score on the examination improved from 46% (10) to 84% (10)* for the entire cohort, with higher post-curriculum scores in the Sim group compared with controls [86% (9) vs. 83% (10)*]. All scores declined after 3 months, but remained higher in the Sim group [72% (18) vs. 64% (15)*]. Independent predictors of 3-month score included pre-curriculum score and participation in a goal-directed simulation. CONCLUSIONS: This multi-institutional study confirms that a 2-h curriculum based on the FUSE program improves surgical trainees' knowledge in the safe use of ES devices across training programs with various geographic locations and resident volumes. The addition of a structured interactive bench-top simulation component further improved learning.

Image-guided techniques improve accuracy of mosaic arthroplasty.

PURPOSE: Mosaic arthroplasty is a surgical technique in which a set of cylindrical osteochondral grafts is transplanted from non-load-bearing areas of the joint to repair damaged articular cartilage. Incongruity between the graft surface and the adjacent cartilage at the repair site results in inferior clinical outcomes. This paper compares technical outcome using three mosaic arthroplasty techniques (conventional, optoelectronic, and patient-specific template) on femur models. METHODS: Three distinct sets of femur models with defects were created. Preoperatively, the harvest and delivery sites were planned using custom software. Five orthopedic surgeons were recruited; each surgeon performed each of the three surgical techniques on each of the three bone models with defect. During the optoelectronic trials, the instrument position and orientation were tracked and superimposed onto the surgical plan. For the patient-specific template trials, plastic templates were manufactured to fit over the defects with cylindrical holes to guide the surgical tools according to the plan. Postoperatively, the femur models were computer tomography and laser scanned. Several measures were made to compare surgical techniques: operative time; surface congruency; defect coverage; graft surface area that is proud or recessed; air volume below the grafts; and distance and angle of the grafts from the surgical plan. RESULTS: The patient-specific template and optoelectronic techniques resulted in improved surface congruency, defect surface coverage, and below-graft air gap volume in comparison with the conventional technique. However, the conventional technique had a shorter operative time. CONCLUSIONS: Image-guided techniques can improve the accuracy of mosaic arthroplasty, which could result in better clinical outcomes.

Implantation of scaffold-free engineered cartilage constructs in a rabbit model for chondral resurfacing.

Joint resurfacing techniques offer an attractive treatment for damaged or diseased cartilage, as this tissue characteristically displays a limited capacity for self-repair. While tissue-engineered cartilage constructs have shown efficacy in repairing focal cartilage defects in animal models, a substantial number of cells are required to generate sufficient quantities of tissue for the repair of larger defects. In a previous study, we developed a novel approach to generate large, scaffold-free cartilaginous constructs from a small number of donor cells (20 000 cells to generate a 3-cm(2) tissue construct). As comparable thicknesses to native cartilage could be achieved, the purpose of the present study was to assess the ability of these constructs to survive implantation as well as their potential for the repair of critical-sized chondral defects in a rabbit model. Evaluated up to 6 months post-implantation, allogenic constructs survived weight bearing without a loss of implant fixation. Implanted constructs appeared to integrate near-seamlessly with the surrounding native cartilage and also to extensively remodel with increasing time in vivo. By 6 months post-implantation, constructs appeared to adopt both a stratified (zonal) appearance and a biochemical composition similar to native articular cartilage. In addition, constructs that expressed superficial zone markers displayed higher histological scores, suggesting that transcriptional prescreening of constructs prior to implantation may serve as an approach to achieve superior and/or more consistent reparative outcomes. As the results of this initial animal study were encouraging, future studies will be directed toward the repair of chondral defects in more mechanically demanding anatomical locations.

Ascertaining maximal voluntary effort production during isokinetic knee strength testing of anterior cruciate ligament-reconstructed patients.

OBJECTIVE: The aim of this study was to assess the performance of prediction rules meant for declaration of efforts as being maximal or not during isokinetic strength testing in a cohort that underwent anterior cruciate ligament reconstruction. DESIGN: Thirty-six individuals performed four sets of six reciprocal concentric knee extension/flexion repetitions at a testing speed of 60 degrees per second through a 60-degree range of motion. The sets consisted of a maximal voluntary effort, two nonmaximal sincere efforts at 50% and 75% of self-perceived maximum, and a set attempting to feign or exaggerate thigh muscle strength deficiencies. Strength curve derived set internal consistency measures, namely, cross-correlation and percent root mean square difference scores, were inputted into the prediction rules, whose performance is reported as specificity and sensitivity percentages. RESULTS: Dependent on the prediction rule used and when expressed on an individual participant basis, the corresponding specificity and sensitivity values ranged from 66.6% to 97.2% and 97.2% to 94.4%, respectively. CONCLUSIONS: Using the prediction rules presented in this investigation, clinicians may be able to ascertain maximal effort production during isokinetic testing in those who have undergone surgical reconstruction of their anterior cruciate ligament.

Principal component modeling of isokinetic moment curves for discriminating between the injured and healthy knees of unilateral ACL deficient patients.

Bilateral knee strength evaluations of unilateral anterior cruciate ligament (ACL) deficient patients using isokinetic dynamometry are commonly performed in rehabilitation settings. The most frequently-used outcome measure is the peak moment value attained by the knee extensor and flexor muscle groups. However, other strength curve features may also be of clinical interest and utility. The purpose of this investigation was to identify, using Principal Component Analysis (PCA), strength curve features that explain the majority of variation between the injured and uninjured knee, and to assess the capabilities of these features to detect the presence of injury. A mixed gender cohort of 43 unilateral ACL deficient patients performed 6 continuous concentric knee extension and flexion repetitions bilaterally at 60°s(-1) and 180°s(-1) within a 90° range of motion. Moment waveforms were analyzed using PCA, and binary logistic regression was used to develop a discriminatory decision rule. For all directions and speeds, a statistically significant overall reduction in strength was noted for the involved knee in comparison to the uninvolved knee. The discriminatory decision rule yielded a specificity and sensitivity of 60.5% and 60.5%, respectively, corresponding to an accuracy of ∼62%. As such, the curve features extracted using PCA enabled only limited clinical usefulness in discerning between the ACL deficient and contra lateral, healthy knee. Improvement in discrimination capabilities may perhaps be achieved by consideration of different testing speeds and contraction modes, as well as utilization of other data analysis techniques.

Development of large engineered cartilage constructs from a small population of cells.

Confronted with articular cartilage's limited capacity for self-repair, joint resurfacing techniques offer an attractive treatment for damaged or diseased tissue. Although tissue engineered cartilage constructs can be created, a substantial number of cells are required to generate sufficient quantities of tissue for the repair of large defects. As routine cell expansion methods tend to elicit negative effects on chondrocyte function, we have developed an approach to generate phenotypically stable, large-sized engineered constructs (≥3 cm(2) ) directly from a small amount of donor tissue or cells (as little as 20,000 cells to generate a 3 cm(2) tissue construct). Using rabbit donor tissue, the bioreactor-cultivated constructs were hyaline-like in appearance and possessed a biochemical composition similar to native articular cartilage. Longer bioreactor cultivation times resulted in increased matrix deposition and improved mechanical properties determined over a 4 week period. Additionally, as the anatomy of the joint will need to be taken in account to effectively resurface large affected areas, we have also explored the possibility of generating constructs matched to the shape and surface geometry of a defect site through the use of rapid-prototyped defect tissue culture molds. Similar hyaline-like tissue constructs were developed that also possessed a high degree of shape correlation to the original defect mold. Future studies will be aimed at determining the effectiveness of this approach to the repair of cartilage defects in an animal model and the creation of large-sized osteochondral constructs.

Image-Guided Techniques Improve the Short-Term Outcome of Autologous Osteochondral Cartilage Repair Surgeries: An Animal Trial.

OBJECTIVE: Autologous osteochondral cartilage repair is a valuable reconstruction option for cartilage defects, but the accuracy to harvest and deliver osteochondral grafts remains problematic. We investigated whether image-guided methods (optically guided and template guided) can improve the outcome of these procedures. DESIGN: Fifteen sheep were operated to create traumatic chondral injuries in each knee. After 4 months, the chondral defect in one knee was repaired using (a) conventional approach, (b) optically guided method, or (c) template-guided method. For both image-guided groups, harvest and delivery sites were preoperatively planned using custom-made software. During optically guided surgery, instrument position and orientation were tracked and superimposed onto the surgical plan. For the template-guided group, plastic templates were manufactured to allow an exact fit between template and the joint anatomy. Cylindrical holes within the template guided surgical tools according to the plan. Three months postsurgery, both knees were harvested and computed tomography scans were used to compare the reconstructed versus the native pre-injury joint surfaces. For each repaired defect, macroscopic (International Cartilage Repair Society [ICRS]) and histological repair (ICRS II) scores were assessed. RESULTS: Three months after repair surgery, both image-guided surgical approaches resulted in significantly better histology scores compared with the conventional approach (improvement by 55%, P < 0.02). Interestingly, there were no significant differences found in cartilage surface reconstruction and macroscopic scores between the image-guided and the conventional surgeries.