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.

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.

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.

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.

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.

Reproducibility of isokinetic knee eccentric and concentric strength indices in asymptomatic young adults.

OBJECTIVE: To assess the reproducibility of isokinetic eccentric and concentric knee extension and flexion strength indices obtained at two different angular velocities. DESIGN: Cohort study. SETTING: University human performance laboratory. PARTICIPANTS: 45 healthy physically active young adults (25 males). MAIN OUTCOME MEASURES: A non reciprocal protocol of concentric and eccentric contractions of the knee extensors and flexors was performed at 30 and 120°/s. Strength indices evaluated included peak moment; dynamic control ratios; and the difference between eccentric and concentric ratio at the two angular velocities. RESULTS: No evidence for inter-test bias in any of the strength indices was noted. Measurement precision for peak moment, as quantified using ratio limits of agreement, suggest that scores may be expected to vary up to 15% for the knee extensors in both eccentric and concentric contraction modes. An error of up to 19% was calculated for the peak moment scores of the knee flexors. Intraclass correlation coefficients revealed fairly robust preservation of participants' rank order for the majority of strength indices (>0.85). CONCLUSION: Isokinetic-related indices of knee muscles performance enable an acceptable level of detection of expected changes in muscular strength parameters as a result of planned interventions.

Computer-assisted mosaic arthroplasty using patient-specific instrument guides.

PURPOSE: Success of mosaic arthroplasty requires that the transplanted plugs be positioned to reconstruct the curvature and height of the original articular surface. This case report demonstrates how to achieve correct plug positioning using patient-specific instrument guides manufactured on a 3D printer. METHODS: Using a 3D computer model of bone and cartilage, the harvesting of plugs and their placement at the defect site was planned on the computer. Instrument guides were manufactured in thermoplastic on a 3D printer; the bottom surface of the guides fit to the contour of the knee and the top surface contained holes to precisely position the surgical instruments. The instrument guides were used on a young female patient to repair a large articular cartilage defect in the left knee. RESULTS: The patient showed an increased range of motion in the knee and also a decrease in pain and discomfort at her 2-year follow-up. A CT arthrogram at 2 years postoperative showed a smooth and appropriate contour of the reconstructed cartilage over the defect. CONCLUSIONS: Image-based preoperative planning and the use of patient-specific instrument guides can yield a good patient outcome without requiring optically tracked intraoperative guidance.

Discriminating between maximal and feigned isokinetic knee musculature performance using waveform similarity measures.

BACKGROUND: Muscle strength test outcomes may aid in determination of impairment or disability rating following injury. In such settings, verification of participant effort during testing is imperative. This investigation explored the utilization of within-set moment waveform similarity measures, namely cross correlation and percent root mean square difference scores, to develop decision rules for discriminating between maximal and feigned efforts during isokinetic testing of the knee joint musculature. METHODS: A mixed-gender sample of 46 participants performed non-reciprocal sets of maximal or feigned knee extension and flexion concentric and eccentric efforts at testing velocities of 30°s(-1) and 120°s(-1). Logistic regression and Monte Carlo simulations were used to derive decision rules for differentiating between the two effort types. FINDINGS: Employing cutoff scores corresponding to 100% specificity; sensitivities of the knee extensor's velocity-specific decision rules were 92.4% and 84.8%, respectively. The velocity-specific knee flexor's test sensitivities were 56.5% and 46.7%. INTERPRETATION: Utilizing the proposed decision rules, substantiating maximal effort performance of the knee extensors may be possible using this specific testing protocol. However, the proposed methods are limited in their ability to verify performance of maximal knee flexor efforts.

Augmented virtuality for arthroscopic knee surgery.

This paper describes a computer system to visualize the location and alignment of an arthroscope using augmented virtuality. A 3D computer model of the patient's joint (from CT) is shown, along with a model of the tracked arthroscopic probe and the projection of the camera image onto the virtual joint. A user study, using plastic bones instead of live patients, was made to determine the effectiveness of this navigated display; the study showed that the navigated display improves target localization in novice residents.

Differentiating between types and levels of isokinetic knee musculature efforts.

This investigation assessed whether a measure of moment curve shape similarity, and a measure quantifying curve magnitude differences, enables differentiation between types (sincere vs. feigned) and levels (maximal vs. submaximal) of effort exerted during isokinetic testing of the knee. Healthy participants (n=37) performed four sets of six concentric knee extension-flexion repetitions on two occasions. The sets consisted of: (1) maximal effort; (2) self-perceived 75% of maximal effort; (3) self-perceived 50% of maximal effort; and (4) a set attempting to feign injury. Average cross-correlation and percent root mean square difference values were computed between moment curves in each direction. Logistic regression was used to derive decision rules for differentiating between maximal and submaximal effort levels; and between sincere and feigned effort types. Using a cutoff criteria corresponding to 100% specificity, maximal effort production could be ascertained with 96% sensitivity within the sample. Feigned efforts, however, could be ascertained with only 31% sensitivity due to overlap with sincere submaximal effort. Using the proposed models, clinicians may be able to ascertain whether maximal efforts were produced during isokinetic knee musculature testing. Additionally, evidence regarding participant's intentions with regard to influencing test results may be gauged, although to a lesser extent.

The effect of suture anchor design and orientation on suture abrasion: An in vitro study.

PURPOSE: To evaluate the effects of suture anchor design and orientation on suture abrasion in a cyclic model. TYPE OF STUDY: In vitro. METHODS: Biomechanical studies have shown suture breakage to be a predominant mode of failure in a suture anchor repair construct. It is possible that suture abrasion during knot tying or in vivo cyclic loading may contribute to early failure. This study specifically investigates suture abrasion caused by 17 commonly used suture anchors and demonstrates the effects of suture anchor angulation and rotation on suture abrasion. To eliminate target tissue as a source of failure, all anchors were implanted into a solid block of sawbones material and tested with No. 2 Ethibond Excel sutures (Ethicon, Somerville, NJ). The testing model focused on 3 variables: suture anchor type, suture pull angle (SA) and angle of anchor rotation (RA). Abrasion testing was then performed on a servohydraulic materials testing system by continually cycling the suture back and forth through each anchor with an excursion of 4 cm at a rate of 0.5 Hz under a load of 10 N until suture failure occurred. RESULTS: Sutures performed significantly better when cycled in line with the anchor at 0 degrees SA with 0 degrees RA than they did at 45 degrees SA with 0 degrees RA or 45 degrees SA with 90 degrees RA. We found no significant difference between anchors tested at 45 degrees SA with 0 degrees RA and 45 degrees SA with 90 degrees RA. For tests performed using metallic suture anchors, all constructs failed by fraying of the suture. Constructs using biopolymer anchors and nonabsorbable polymeric anchors experienced a mixture of suture and anchor eyelet failures. CONCLUSIONS: In addition to the statistically significant detrimental effects of suture anchor angulation and rotation on suture abrasion, suture anchor eyelet design may also influence suture abrasion. Surgeons should be aware of the effects of anchor angulation, suture position in the eyelet, and design and composition of the eyelet to maximize the durability of the construct.

Meniscal injury: I. Basic science and evaluation.

The patient with meniscal injury may present with pain, swelling, or mechanical symptoms and often requires surgical intervention for symptom resolution. Treatment of such injuries relies on understanding the gross and microanatomic features of the meniscus that are important in maintaining meniscal function. The ability of the meniscus to participate in load bearing, shock absorption, joint lubrication, and joint stability depends on the maintenance of its structural integrity. The diagnosis of meniscal injury often can be made by clinical evaluation utilizing the history, physical examination, and plain radiographs. Magnetic resonance imaging can be useful in confirming the diagnosis when clinical findings are inconclusive. Treatment depends on tear pattern, vascularity, and an assessment of tissue quality. Surgical decision making for the treatment of meniscal injury is based on patient factors and understanding of the meniscal structure, function, and pathology.

Meniscal injury: II. Management.

Meniscal repair is a viable alternative to resection in many clinical situations. Repair techniques traditionally have utilized a variety of suture methods, including inside-out and outside-in techniques. Bioabsorbable implants permit all-inside arthroscopic repairs. The success of meniscal repair depends on appropriate meniscal bed preparation and surgical technique and is also influenced by biologic factors such as tear rim width and associated ligamentous injury. Successful repair in >80% of cases has been reported in conjunction with anterior cruciate ligament reconstruction. Success rates are lower for isolated repairs. Complications related to repair include neurologic injury, postoperative loss of motion, recurrence of the tear, and infection. Meniscal allograft transplantation may provide a treatment option when meniscus salvage is not possible or when a previous total meniscectomy has been done.