Meniscectomy

Patients with Mood Disorders Have Higher Rates of Healthcare Utilization, Medical Complications, Opioid Prescriptions, and Subsequent Knee Surgery after Arthroscopic Partial Meniscectomy

PURPOSE

To compare rates of post-operative complications, healthcare utilization, opioid prescribing patterns, and secondary knee surgery in patients with versus without a preexisting anxiety or depressive disorder (ADD) undergoing isolated primary arthroscopic partial meniscectomy (APM).

METHODS

The TriNetX database was queried from inception to compare patients over 18-years-old who underwent isolated primary APM with versus without a pre-existing ADD. Patients were matched in a 1:1 ratio based on demographic factors and comorbidities, including diabetes and hypertension. The following outcomes were collected: 1) post-operative complications and healthcare utilization within ninety days, 2) proportion of patients prescribed an opioid within one year, and 3) subsequent knee surgery within two years, specifically ipsilateral or contralateral meniscus surgery or total knee arthroplasty. Two subgroup analyses were conducted. Opioid naive patients with and without an ADD were compared based on the proportion of patients prescribed an opioid within one year of APM. Rates of revision meniscus surgery on the ipsilateral knee were also compared within two years of APM.

RESULTS

Within 90 days, patients with a pre-existing ADD (n=26,507), compared to those without (n=26,507), had higher rates of healthcare utilization, including readmission (p<0.001), and medical complications, like cerebrovascular accident (p=0.002). A greater proportion of patients with an ADD were prescribed opioids at all chosen time points within one year of APM. Similarly, a greater proportion of opioid naive patients with an ADD were prescribed opioids within six months (p<0.001) and one year (p<0.001). Patients with an ADD also had higher rates of total knee arthroplasty (p=0.001) and ipsilateral revision meniscus surgery (left knee: p=0.020; right knee: p=0.019) within two years.

CONCLUSION

Patients with an anxiety or depressive disorder have higher rates of healthcare utilization, medical complications, opioid prescriptions, and subsequent knee surgery after isolated primary arthroscopic partial meniscectomy.

LEVEL OF EVIDENCE

III, retrospective cohort study.

Application of adhesives in the treatment of cartilage repair

From degeneration causing intervertebral disc issues to trauma‐induced meniscus tears, diverse factors can injure the different types of cartilage. This review highlights adhesives as a promising and rapidly implemented repair strategy. Compared to traditional techniques such as sutures and wires, adhesives offer several advantages. Importantly, they seamlessly connect with the injured tissue, deliver bioactive substances directly to the repair site, and potentially alleviate secondary problems like inflammation or degeneration. This review delves into the cutting‐edge advancements in adhesive technology, specifically focusing on their effectiveness in cartilage injury treatment and their underlying mechanisms. We begin by exploring the material characteristics of adhesives used in cartilage tissue, focusing on essential aspects like adhesion, biocompatibility, and degradability. Subsequently, we investigate the various types of adhesives currently employed in this context. Our discussion then moves to the unique role adhesives play in addressing different cartilage injuries. Finally, we acknowledge the challenges currently faced by this promising technology.

Novel Meniscus Transfer Technique: A Case Report

The meniscus is an essential component of the knee joint, acting as a shock absorber as well as assisting in the transmission of forces. Due to the meniscus importance of the knee, much of the current literature focuses on treatment techniques that can spare and repair the meniscus when it is torn. The unique vasculature of the meniscus often makes repair difficult or, in many cases, impossible. A current focus within orthopedics has been on meniscal allograft transplantation to fill this gap. The lack of a universal surgical technique for graft fixation, along with the current failure rates, demonstrates the need for further improvements. The senior author proposes a novel technique for meniscal allograft transplantation that has shown decreased blood loss and surgical time, while also reducing intra-operative trauma to the knee. This case reports a 16-year-old patient who underwent a right lateral meniscal allograft transplant following a large segmental defect tear of the lateral meniscus. The patient initially underwent arthroscopy and meniscectomy with screw fixation of the lateral femoral condyle lesion. After physical therapy, the patient experienced increased pain and swelling, with magnetic resonance imaging (MRI) demonstrating a meniscal defect unamenable to repair. The patient met indications for meniscal allograft transplantation given the failed meniscectomy, absence of cartilage loss and significant osteoarthritis, and the patient's age of less than 50 years old.

Improved Outcomes After Reinforced Radial Meniscus Repair Augmented With Bone Marrow Aspirate Concentrate

Purpose

To assess clinical outcomes of patients who have undergone surgical repair of radial meniscal tears with reinforced suture bar (rebar) technique augmented with bone marrow aspirate concentrate.

Methods

This is a retrospective study of a single fellowship-trained sports medicine surgeon's experience on all patients who underwent a reinforced repair (rebar) of a radial meniscus tear from November 2016 to 2018, with a minimum of 12-month follow-up. Lysholm scores, IKDC (International Knee Documentation Committee) Subjective Knee Form scores, and Tegner scale were collected postoperatively at periods for at least 1 year and retrospectively studied.

Results

Patients were followed for an average of 36.3 ± 25.0 months [range: 12.0-69.0 months]. Pain scores improved from 6.1 ± 2.1 to 0.4 ± 1.4 at 1 year (P < .001). IKDC Subjective Knee Form scores improved from 63 ± 26 to 90 ± 13 (P = .021). Lysholm scores improved from 64 ± 28 to 94 ± 9 (P = .025). Based on a calculated minimal clinical important difference (MCID) of 1.5, 100% of patients had improvement above the MCID. In addition, 88% of patients had a 1-year IKDC Subjective Knee Form score above the patient acceptable symptomatic state. Preoperative Tegner activity scale improved from 3 ± 1.5 to 8 ± 2.6 (P = .007). Patients returned to their preinjury activity with little difference in the Tegner activity scale when we compared preinjury and 1-year postoperative (8.1 ± 1.3 vs 8.0 ± 2.6 respectively, P = .317).

Conclusions

The rebar repair technique for radial meniscus tears, with bone marrow aspirate concentrate augmentation, showed improved outcomes in both pain and function at minimum follow-up of 12 months. Patients were able to return to a high preinjury activity level by 1 year, and 100% of patients had improvement above the MCID and 88% met patient acceptable symptomatic state.

Level of Evidence

Level IV, therapeutic case series.

Meniscal Suture Influence on Driving Ability 6 Weeks after Anterior Cruciate Ligament Reconstruction with Hamstring Autograft

The purpose of this study was to determine if driving ability 6 weeks after anterior cruciate ligament (ACL) reconstruction is affected by the addition of a meniscal suture. It was also hypothesized that no differences in the driving performance would be found between right or left knee surgery subgroups. A total of 82 people participated in this prospective cohort study: 36 healthy controls, 26 patients undergoing isolated ACL (iACL) reconstruction with hamstring autograft, and 20 patients undergoing ACL and meniscal suture (ACL-MS) reconstruction. ACL-MS group followed a weight-bearing and movement restriction protocol during the first 2 postoperative weeks, whereas patients undergoing iACL could start range-of-motion exercises and full weight-bearing ambulation on the first postoperative day. A driving simulator that reproduced real-life driving conditions was used to evaluate driving ability. The software analyzed multiple driving and braking variables. Driving performance in the sixth postoperative week was compared with that of a healthy control group. Subgroup analysis considering additional procedures (iACL, ACL-MS) and the side of the operated knee (right, left) was also performed. No statistically significant differences were found in the demographic characteristics nor in the driving performance (collisions, p = 0.897; sidewalk invasions, p = 0.749; pedestrian impact, p = 0.983) between iACL, ACL-MS, and control groups. No statistically significant differences were found in right-left subgroup analysis. The results of the present study show that patients in their sixth postoperative week after right or left ACL reconstruction showed similar driving performance as compared with a healthy control group, regardless of associating or not a meniscal suture, suggesting it is safe to resume driving 6 weeks after the mentioned surgeries.

Arthroscopic Meniscal Repair With Second-Generation Platelet-Rich Fibrin Clot Augmentation

Meniscal tears are among the most common injuries in the knee, and partial as well as total meniscectomy has been advocated as the treatment for meniscal injury. Over the years, the role of the meniscus as a shock absorber, load transmitter, and secondary anterior stabilizer, along with its proprioceptive and lubrication role, has been well established, and meniscal repair is recommended, especially in younger individuals. Factors such as tear location, pattern, chronicity, size, and extent; repair technique; and patient age and habits can influence meniscal repair, and to enhance meniscal healing, a variety of augmentation techniques have been introduced. These include needling, trephination, synovial abrasion, and the use of adjuvants such as platelet-rich plasma, platelet clots, fibrin clots, bone marrow clots, and stem cells. A second-generation platelet derivative called "platelet-rich fibrin" (PRF) has predictable platelet, growth factor, and cell mediator concentrations without using any anticoagulants. We describe a reproducible and simple way to harvest PRF and create and use a PRF clot, along with detailed instructions on how to integrate the clot with a meniscal repair arthroscopically.

Effects of low-intensity pulsed ultrasound stimulation on cell seeded 3D hybrid scaffold as a novel strategy for meniscus regeneration: An in vitro study

Menisci are fibrocartilaginous structures in the knee joint with an inadequate regenerative capacity, which causes low healing potential and further leads to osteoarthritis. Recently, three-dimensional (3D) printing techniques and ultrasound treatment have gained plenty of attention for meniscus tissue engineering. The present study investigates the effectiveness of low-intensity pulsed ultrasound stimulations (LIPUS) on the proliferation, viability, morphology, and gene expression of the chondrocytes seeded on 3D printed polyurethane scaffolds dip-coated with gellan gum, hyaluronic acid, and glucosamine. LIPUS stimulation was performed at 100, 200, and 300 mW/cm² intensities for 20 min/day. A faster gap closure (78.08 ± 2.56%) in the migration scratch assay was observed in the 200 mW/cm² group after 24 h. Also, inverted microscopic and scanning electron microscopic images showed no cell morphology changes during LIPUS exposure at different intensities. The 3D cultured chondrocytes under LIPUS treatment revealed a promotion in cell proliferation rate and viability as the intensity doses increased. Additionally, LIPUS could stimulate chondrocytes to overexpress the aggrecan and collagen II genes and improve their chondrogenic phenotype. This study recommends that the combination of LIPUS treatment and 3D hybrid scaffolds can be considered as a valuable treatment for meniscus regeneration based on our in vitro data.

Efficacy of Electromyographic Biofeedback in Muscle Recovery after Meniscectomy in Soccer Players

Electromyographic biofeedback (EMG-BF) is a therapeutic technique that has been used successfully in the rehabilitation of injuries. Although it has been applied to athletes, its use in this field is not very widespread. The objective of this study is to analyze its effectiveness in the recovery of electromyographic activity of the quadriceps after meniscectomy, evaluated through isometric contraction of the vastus lateralis. The sample comprised ten professional footballers in the Spanish League (2nd Division A) who had previously suffered a meniscus injury in their knee and had undergone a meniscectomy. The intervention consisted of EMG-BF treatment lasting between 6 and 10 sessions. The electromyographic signal was recorded using a Thought Technology ProComp Infiniti 8-channel biofeedback unit with a sampling rate of 2048 samples/second. For each session, a within-subject ABA design of 6 or 10 trials per session was used, with three pre- and three post-measures, which determined the gain for each session. The results indicated (1) improvements in all cases, (2) EMG-BF was effective, (3) the working model was statistically significant with an explained variance of between 67% and 75%, and (4) the generalizability analysis showed that the results are reliable and generalizable. The results indicate that EMG-BF is effective in neuromuscular rehabilitation after this type of intervention.

Shock Response of Porcine Meniscus along with Axial and Radial Directions

The meniscus is a multifunctional fibrocartilage tissue in the knee joint which stables joint movement, bears load and absorbs impact. Improper collisions will cause damage to meniscus tissue and lose its original functionality. However, it is difficult to fully evaluate the mechanical properties of the meniscus based on static test results alone. In this study, Split Hopkinson Pressure Bar (SHPB) and hydraulic material testing system (MTS) were utilized to examine the quasi-static and dynamic properties of the porcine meniscus along with two different orientations. The results showed that the meniscus is a strain rate sensitive material and its mechanical properties mainly depend on the orientation of collagen fiber bundles in the peripheral direction. The meniscus tissue did not show obvious yield characteristics under quasi-static test conditions. However, the meniscus showed clear yield behavior under dynamic loading. When the strain rate increased, the elastic modulus of the radial meniscus remained around 35 MPa while the elastic modulus of the axial meniscus increased from 30 MPa to 80 MPa. This study demonstrates that the meniscus is sensitive to strain rate at both dynamic and quasi-static conditions, and the meniscus is an anisotropic biological tissue.

The efficacy of intraarticular viscosupplementation after arthroscopic partial meniscectomy: a randomized controlled trial

BACKGROUND

This study aimed to evaluate the efficacy of viscosupplementation after arthroscopic partial meniscectomy.

METHOD

A randomized controlled trial of 47 patients who underwent arthroscopic partial meniscectomy was conducted between March 2020 and March 2021. Patients were randomized into two groups: a viscosupplementation group (n = 23) and a control group (n = 24). A single-dose intraarticular hyaluronic acid injection was used as viscosupplementation. The 100 mm visual analogue scale (VAS) for pain assessment was measured at baseline and at 1 day, 2 weeks, 6 weeks, and 3 months post-surgery. The International Knee Documentation Committee (IKDC), Tegner, Lysholm, and Western Ontario and McMaster University Osteoarthritis Index (WOMAC) scores and range of motion (ROM) of the knee were measured at baseline, 2 weeks, 6 weeks, and 3 months.

RESULTS

The 100 mm VAS score for pain was significantly lower in the viscosupplementation group at 2 weeks post-surgery (27.5 mm vs. 40.7 mm, P = 0.047). ROM was significantly greater in the viscosupplementation group than in the control group at 2 weeks (131.5° vs. 121.0°, P = 0.044) post-surgery. No significant differences were observed in the IKDC or in the Tegner, Lysholm, and WOMAC scores between the two groups.

CONCLUSIONS

Viscosupplementation after arthroscopic partial meniscectomy significantly reduced pain at 2 weeks post-surgery and improved ROM of the knee at 2 weeks post-surgery. There might be some benefits in terms of pain and functional recovery of viscosupplementation after arthroscopic surgery.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

TRIAL REGISTRATION

This randomized controlled trial was registered at cris.nih.go.kr # KCT0004921 .

Meniscal Injuries: Mechanism and Classification

Meniscal tears may be managed through conservative physical therapy and nonsteroidal anti-inflammatory medications or operative intervention. Meniscal repair is superior to partial meniscectomy with better functional outcomes and less severe degenerative changes over time. Surgical advances in operative techniques, modern instrumentation and biological enhancements collectively improve healing rates of meniscal repair. However, failed repair is not without consequences and can negative impact patient outcomes. Therefore, it is imperative for surgeons to have a thorough understanding of the vascular zones and biomechanical classifications of meniscal tears in order to best determine the most appropriate treatment.

Outcomes at 20 years after meniscectomy in young patients

AIM

To define arthroscopic meniscectomy (AM) outcomes in young patients at 20 years follow up in terms of predictors of poor clinical results, rate and timing of conversion to total knee replacement (TKR).

METHODS

The following data were collected for 225 patients aged between 18 and 50 years with meniscal tear (MT) who underwent AM: age at surgery, gender, injured meniscus, knee alignment, associated lesions, amount of meniscal resection. At 20 years follow up, rate and timing of TKR conversion and clinical outcomes with Knee injury and Osteoarthritis Outcome Score (KOOS) score were reviewed.

RESULTS

Ten patients (4.4%) required TKR in the follow up period. The mean time from AM to TKR was 7.0 years (standard deviation 3.87). Age between 40 and 50 years at AM (P < 0.01), malalignment (P < 0.01), lateral meniscectomy (any size, P = 0.01), advanced chondral lesion (Outerbridge > 2, P < 0.01) and total meniscectomy (P < 0.01) were significantly related to subsequent TKR. Negative predicting factors to obtaining equal or superior to age/sex-adjusted KOOS score were age between 40 and 50 years old at time of AM (P < 0.01), female sex (P < 0.01), malalignment (P = 0.04), and advanced chondral lesion (Outerbridge > 2, P = 0.02).

CONCLUSIONS

Twenty years conversion rate to TKR after AM for MT is 4.4% and TKR was performed after a mean time of 7 years. Significant association between TKR surgery and advanced chondral lesion (Outerbridge > 2), total meniscectomy, lateral meniscectomy, age at surgery between 40 and 50 years old, and malalignment were found. Age between 40 and 50 years at time of AM, female, malalignment, advanced chondral lesion were all factors significantly related to poor clinical results.

Osteochondral Autograft Transplant as a Potential Salvage Procedure for Articular Cartilage Defects of the Lateral Compartment in Lateral Meniscus-Deficient Knees: Results From a Country With Limited Availability of Meniscal Transplant

Background:

The treatment of a meniscus-deficient knee is challenging, especially when patients are young and active and are not favorable candidates for prosthetic joint replacement.

Hypothesis:

We hypothesized that osteochondral autologous transplant (OAT) alone can be considered a salvage treatment for patients with cartilage damage of the lateral compartment of the knee, even with lateral meniscal deficiency, if the knee alignment is close to neutral.

Study Design:

Case series; Level of evidence, 4.

Methods:

Patients with lateral meniscal deficiency, whose femorotibial angle was 170° to 180° and who underwent OAT on the lateral compartment of the knee without concomitant realignment osteotomy, were retrospectively included in this study. The International Knee Documentation Committee (IKDC) subjective score and the Japanese Orthopaedic Association score for knee osteoarthritis (JOA knee score) were recorded. The International Cartilage Repair Society (ICRS) cartilage repair assessment was used to evaluate the repaired cartilage at second-look arthroscopy.

Results:

The study included 10 patients (mean ± SD age, 31.7 ± 19.7 years; 3 men and 7 women) who had ICRS grade 4 cartilage lesions (mean size, 3.5 ± 1.7 cm²); the mean follow-up was 73.8 ± 42.5 months. From preoperative assessment to final follow-up, the mean IKDC subjective score improved significantly from 53.5 ± 10.0 to 85.4 ± 10.1, and the mean JOA knee score improved significantly from 81.0 ± 8.4 to 95.6 ± 5.3 (P = .004 for both). One patient with a femorotibial angle of 170° underwent revision distal femoral osteotomy owing to prolonged symptoms and progression of the valgus deformity, and 2 other patients with femorotibial angles of 170° and 171° also exhibited progression of valgus malalignment or low clinical scores postoperatively. Patients with a favorable femorotibial angle (174°-178°) exhibited relieved symptoms and preservation of femorotibial angle alignment within 1° of change at follow-up. At second-look arthroscopy (n = 8 patients), 6 patients had an ICRS score of nearly normal or normal.

Conclusion:

In the study patients, for which a meniscal allograft was unavailable, the OAT procedure was able to relieve the symptoms associated with cartilage lesions, even with lateral meniscal deficiency, when the femorotibial angle alignment was close to neutral.

Three-dimensional and 3-Tesla MRI morphometry of knee meniscus in normal and pathologic state

INTRODUCTION

To conduct a morphometric analysis of intact and torn menisci using isotropic meniscus plane three-dimensional (3D) reconstructions on 3-Tesla MRI and compare 2D versus 3D MRI for meniscus tear characterization.

MATERIALS AND METHODS

One hundred thirty three normal menisci from 92 patients (39 male, 53 female), and 38 arthroscopy-proven torn menisci from 36 patients (23 male, 13 female) were evaluated using 3D isotropic multi-planar MRI reconstructions and 2D MRI. Two observers measured the tibial plateau height and area, meniscal height, axial plane cross-sectional areas, and extrusion of intact menisci. Two observers also measured the meniscal tear length, tear area, and residual area of pathological menisci on 2D and 3D MRI. Intraclass correlation coefficients (ICC) were obtained. Institutional Review Board approval was obtained, and the informed consent was waived.

RESULTS

Medial meniscus (MM) and lateral meniscus (LM) areas were 503.6 ± 85.1 mm² and 396.6 ± 72.0 mm² for Observer 1, and 515.8 ± 82.1 mm² and 408.0 ± 68.3 mm² for Observer 2 (ICC:0.86, 0.87). In torn menisci, average tear length, area, and residual area were 36.3 ± 13.6 mm, 182.6 ± 139.3 mm² , and 235.4 ± 140.3 mm² , respectively for Observer 1, and 38.9 ± 14.7 mm, 181.2 ± 135.6 mm² , 238.2 ± 140.5 mm² for Observer 2. In the MM and LM, bucket-handle and complex tears were largest in areas, respectively. ICCs were excellent (0.91-1.0) on 3D MRI and moderate-good (0.57-0.81) on 2D MRI.

CONCLUSION

Meniscus morphometry on 3D MRI shows moderate to excellent inter-observer reliability and meniscus tear extent is more reliably defined on 3D MRI than 2D MRI. Residual meniscus-area calculation can be performed on 3D MRI.

Mechanical alterations in the avascular region of the meniscus following partial meniscectomy: A cadaveric porcine longitudinal meniscal tear model

BACKGROUND

Although partial meniscectomy is a common treatment for the tears in the avascular region of the meniscus, mechanical alterations following meniscectomy are known to initiate mechanically-induced osteoarthritis. We aimed to measure the articular cartilage contact pressure distributions in the knees with surgically repaired and partially resected menisci in the avascular region.

METHODS

A pneumatic loading device was developed to apply a 1000 N compressive load on the cadaveric porcine knee samples at the flexion angles of 20, 35, 50, and 65°. We simulated longitudinal meniscal tears in the avascular inner 1/3 portion and the well-vascularized middle 1/3 portion of the meniscus. Articular cartilage contact pressures for the knees with intact, torn, repaired, and resected menisci were compared.

FINDINGS

For the tears in well-vascularized regions, meniscal repairs restored articular cartilage contact pressures to the levels in intact joints. However, partial meniscectomy significantly increases the maximum contact pressures and the average contact pressures in highly compressed areas. However, partial meniscectomy in the avascular region did not alter the maximum articular cartilage contact pressures and the average contact pressures in highly compressed areas. Stabilities in knee samples were not significantly altered following partial meniscectomy in both inner and middle regions.

INTERPRETATION

Although repair surgeries are beneficial for the tears in well-vascularized areas because the articular cartilage contact mechanics are reconstructed, partial meniscectomy may be a viable alternative treatment for the tears in avascular regions without introducing significant mechanical alterations.

Early Functional Rehabilitation after Meniscus Surgery: Are Currently Used Orthopedic Rehabilitation Standards Up to Date?

Meniscus therapy is a challenging process. Besides the respective surgical procedure such as partial meniscectomy, meniscus repair, or meniscus replacement, early postoperative rehabilitation is important for meniscus regeneration and return to sport and work as well as long-term outcome. Various recommendations are available. However, the current literature lacks information concerning the actual early rehabilitation in daily routine recommended by orthopedic surgeons. Thus, the purpose of this study was to investigate currently used standard early rehabilitation protocols in the daily routine of orthopedic surgeons. This study investigated the recommendations and concepts for early rehabilitation after meniscus therapy given by German, Austrian, and Swiss orthopedic institutions. Standardized criteria such as weight bearing, range of motion, use of an orthosis, and rehabilitation training were analyzed according to the conducted surgical procedure: partial meniscectomy, meniscus repair, or meniscus replacement. The analysis of standard rehabilitation concepts for partial meniscectomy (n = 15), meniscus repair (n = 54), and meniscus replacement (n = 7) showed significantly earlier functional rehabilitation in all criteria after partial meniscectomy in contrast to meniscus repair techniques (p < 0.001). In addition, significant restrictions were found in full weight bearing, full range of motion, and the use of braces. In summary, a wide range of recommendations for weight bearing, ROM, brace therapy, and mobilization is available, particularly after meniscus repair and meniscus replacement. Most concepts are in accordance with those described in the current literature. Further research is necessary to enhance the scientific evidence on currently used early rehabilitation concepts after meniscus therapy.

Comparison of High-Hydrostatic-Pressure Decellularized Versus Freeze-Thawed Porcine Menisci

The meniscus functions as a load distributor and secondary stabilizer in the knee, and the loss of the meniscus increases the risk of osteoarthritis. Freeze-thawed menisci are used in clinical practice to replace defective menisci; however, the disadvantages of freeze-thawed tissues include disease transmission and immune rejection. In this study, we decellularized menisci using high hydrostatic pressure (HHP) and compared the decellularized menisci with freeze-thawed menisci. Porcine menisci were either pressurized at 1,000 MPa for 10 min and then washed with DNase solution or frozen at -80°C for 2 days and thawed. These menisci then underwent in vitro histological, biochemical, and biomechanical comparisons with native menisci. The HHP-treated and freeze-thawed menisci were also subcutaneously implanted in a pig, and later harvested for histological analysis. The numbers of histologically detected cells were significantly lower and the amount of biochemically detected DNA was approximately 100-fold lower in HHP-treated than in native and freeze-thawed menisci. The compression strength of the HHP-decellularized menisci was decreased after 1 and 50 cycles at 20% strain but was unchanged in the freeze-thawed menisci. After implantation, the numbers of multinucleated giant cells were significantly lower around the HHP-treated menisci than around the freeze-thawed menisci. Recellularization of the HHP-decellularized menisci was confirmed. Thus, although the HHP-decellularized menisci were mechanically inferior to the freeze-thawed meniscus in vitro, they were immunologically superior. Our study is the first to demonstrate the use of HHP for decellularization of the meniscus. © 2019 The Authors. Journal of Orthopaedic Research^® published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 37:2466-2475, 2019.

Development of decellularized meniscus using closed sonication treatment system: potential scaffolds for orthopedics tissue engineering applications

PURPOSE

Meniscus is a fibrocartilagenous tissue that cannot effectively heal due to its complex structure and presence of avascular zone. Thus, tissue engineering and regenerative medicine offer an alternative for the regeneration of meniscus tissues using bioscaffolds as a replacement for the damaged one. The aim of this study was to prepare an ideal meniscus bioscaffold with minimal adverse effect on extracellular matrix components (ECMs) using a sonication treatment system.

METHODS

The decellularization was achieved using a developed closed sonication treatment system for 10 hrs, and continued with a washing process for 5 days. For the control, a simple immersion treatment was set as a benchmark to compare the decellularization efficiency. Histological and biochemical assays were conducted to investigate the cell removal and retention of the vital extracellular matrix. Surface ultrastructure of the prepared scaffolds was evaluated using scanning electron microscope at 5,000× magnification viewed from cross and longitudinal sections. In addition, the biomechanical properties were investigated through ball indentation testing to study the stiffness, residual forces and compression characteristics. Statistical significance between the samples was determined with p-value =0.05.

RESULTS

Histological and biochemical assays confirmed the elimination of antigenic cellular components with the retention of the vital extracellular matrix within the sonicated scaffolds. However, there was a significant removal of sulfated glycosaminoglycans. The surface histoarchitecture portrayed the preserved collagen fibril orientation and arrangement. However, there were minor disruptions on the structure, with few empty micropores formed which represented cell lacunae. The biomechanical properties of bioscaffolds showed the retention of viscoelastic behavior of the scaffolds which mimic native tissues. After immersion treatment, those scaffolds had poor results compared to the sonicated scaffolds due to the inefficiency of the treatment.

CONCLUSION

In conclusion, this study reported that the closed sonication treatment system had high capabilities to prepare ideal bioscaffolds with excellent removal of cellular components, and retained extracellular matrix and biomechanical properties.

Magnetic Resonance Imaging and Functional Outcomes After a Polyurethane Meniscal Scaffold Implantation: Minimum 5-Year Follow-up

PURPOSE

To report the magnetic resonance imaging (MRI) and clinical outcomes at a minimum 5-year follow-up in a series of patients with postmeniscectomy syndrome and treated with a polyurethane scaffold.

METHODS

All consecutive patients operated on from September 2008 to February 2011 for either persistent medial or lateral joint line compartmental pain receiving a polyurethane scaffold due to a previous partial meniscus resection with a minimum 5-year follow-up were included. Functional scores (Knee Injury and Osteoarthritis Outcomes Score, International Knee Documentation Committee, Lysholm, and Tegner) were assessed preoperatively and at the last follow-up. The state of the scaffold as well as postoperative scaffold extrusion and the total remaining meniscal volume was also evaluated in MRI.

RESULTS

Thirty-two patients were included. The mean follow-up was 70.8 ± 7.5 months. The functionality of the knees improved in all the scores used (P < .001) except for the Tegner score that stayed steady. Most of meniscal implants showed extrusion of 2.4 mm (95% confidence interval [CI], 1.1-3.7) were smaller and a hyperintensity signal was seen in the MRI. Three scaffolds were resorbed at the last follow-up. The meniscal volume, determined by MRI, was 1.14 cm³ (95% CI, 0.96-1.31) preoperatively and 1.61 cm³ (95% CI, 1.43-1.7) at the last follow-up. No differences were presented.

CONCLUSIONS

The use of a polyurethane meniscal scaffold in patients with a symptomatic meniscus deficit had a good functional outcome at 5 years after surgery. However, the implanted scaffolds did not present normal meniscal tissue with MRI, and the implant volume was considerably less than expected. The fact that most of patients included received different concomitant procedures during scaffold implantation introduces a degree of performance bias into the results.

LEVEL OF EVIDENCE

Level IV, case series.

In Vivo Tibial Cartilage Strains in Regions of Cartilage-to-Cartilage Contact and Cartilage-to-Meniscus Contact in Response to Walking

BACKGROUND

There are currently limited human in vivo data characterizing the role of the meniscus in load distribution within the tibiofemoral joint. Purpose/Hypothesis: The purpose was to compare the strains experienced in regions of articular cartilage covered by the meniscus to regions of cartilage not covered by the meniscus. It was hypothesized that in response to walking, tibial cartilage covered by the meniscus would experience lower strains than uncovered tibial cartilage.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Magnetic resonance imaging (MRI) of the knees of 8 healthy volunteers was performed before and after walking on a treadmill. Using MRI-generated 3-dimensional models of the tibia, cartilage, and menisci, cartilage thickness was measured in 4 different regions based on meniscal coverage and compartment: covered medial, uncovered medial, covered lateral, and uncovered lateral. Strain was defined as the normalized change in cartilage thickness before and after activity.

RESULTS

Within each compartment, covered cartilage before activity was significantly thinner than uncovered cartilage before activity ( P < .001). After 20 minutes of walking, all 4 regions experienced significant cartilage thickness decreases ( P < .01). The covered medial region experienced significantly less strain than the uncovered medial region ( P = .04). No difference in strain was detected between the covered and uncovered regions in the lateral compartment ( P = .40).

CONCLUSION

In response to walking, cartilage that is covered by the meniscus experiences lower strains than uncovered cartilage in the medial compartment. These findings provide important baseline information on the relationship between in vivo tibial compressive strain responses and meniscal coverage, which is critical to understanding normal meniscal function.

Lateral Meniscus Allograft Transplantation: The Bone Plug Technique

Lateral meniscus tears are commonly encountered by orthopaedic surgeons. Despite efforts to repair and preserve the meniscus, meniscectomy is occasionally required to treat irreparable tears. The resulting lateral meniscus deficiency leads to increased tibiofemoral contact pressures and ultimately early osteoarthritic changes in the knee. Lateral meniscal allograft transplant (LMAT) has been proposed as a way to restore the lateral meniscus-deficient knee to its native form. Although several techniques for LMAT have been proposed, osseous fixation has demonstrated increased stability, improved outcomes, and improved long-term survival. This article presents a technique for LMAT using bone plugs and standard arthroscopic portals.

Long-term Survival Analysis of Meniscus Allograft Transplantation With Bone Fixation

PURPOSE

To investigate the long-term clinical results and clinical survival rate of meniscus allograft transplantation (MAT) with bone fixation.

METHODS

The inclusion criteria of this study were previous MAT with bone fixation technique in our institution and minimum follow-up duration of 8 years. Potential subjects were identified using the medical records and database that was prospectively collected from December 1996 to December 2005. The exclusion criteria were diffuse International Cartilage Repair Society grade IV articular cartilage degeneration that was not treated with a concomitant or staged cartilage repair procedure. Surgical indication for MAT was previous total or subtotal meniscectomy followed by persistent swelling and pain in involved compartment. Recommendations to return to contact sports or strenuous activities were not made. Clinical outcomes were evaluated using the modified Lysholm score, and comparison between preoperative and final Lysholm score was done using Student t-test. During the follow-up period, failure was defined as (1) subtotal resection of the allograft, (2) conversion to total knee arthroplasty, or (3) a modified Lysholm score less than 65 or that of the preoperative status. Survival analysis was performed using the Kaplan-Meier method.

RESULTS

During the study period, 52 knees underwent MAT in our institution and 49 knees were eligible for this study. Three knees were excluded because they had diffuse grade IV cartilage degeneration in the respective compartment. Among the 49 knees enrolled, 34 underwent lateral and 15 underwent medial MAT. Two patients had bilateral lateral MAT. Of those 47 patients, 37 were male and 10 were female. Mean patient age at the time of the MAT was 30.4 ± 8.6 years. The median follow-up period was 11.5 years (8 to 17 years). The preoperative mean modified Lysholm score was 73.2 ± 10.6, which significantly increased to 89.4 ± 13.2 at the time of the final follow-up (P < .001). There were 2 failures noted at 6 months and 11.3 years, respectively, after MAT. All of the other allografts were surviving at the time of the latest follow-up. The 10-year survival rate was 98.0% (95% confidence interval [CI], 94.1%-100%), and the 15-year survival rate was 93.3% (95% CI, 83.7%-100%) according to the Kaplan-Meier analysis.

CONCLUSIONS

MAT using the bone fixation techniques demonstrated a high clinical survival rate according to the long-term observation.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

An Overview of Scaffold Design and Fabrication Technology for Engineered Knee Meniscus

Current surgical treatments for meniscal tears suffer from subsequent degeneration of knee joints, limited donor organs and inconsistent post-treatment results. Three clinical scaffolds (Menaflex CMI, Actifit® scaffold and NUsurface® Meniscus Implant) are available on the market, but additional data are needed to properly evaluate their safety and effectiveness. Thus, many scaffold-based research activities have been done to develop new materials, structures and fabrication technologies to mimic native meniscus for cell attachment and subsequent tissue development, and restore functionalities of injured meniscus for long-term effects. This study begins with a synopsis of relevant structural features of meniscus and goes on to describe the critical considerations. Promising advances made in the field of meniscal scaffolding technology, in terms of biocompatible materials, fabrication methods, structure design and their impact on mechanical and biological properties are discussed in detail. Among all the scaffolding technologies, additive manufacturing (AM) is very promising because of its ability to precisely control fiber diameter, orientation, and pore network micro-architecture to mimic the native meniscus microenvironment.

Anterolateral Meniscofemoral Ligament of the Lateral Meniscus

Anatomical variations of the meniscus are a common anomaly that knee surgeons frequently encounter. However, anomalies of the anterior horn of the lateral meniscus (AHLM) are extremely rare. In this report, we present a newly discovered anomaly of the AHML: an anterolateral meniscofemoral ligament is described with clinical features and radiographic and arthroscopic findings.

Changes in articular cartilage following arthroscopic partial medial meniscectomy

PURPOSE

To examine degenerative changes in all cartilage surfaces of the knee following arthroscopic partial medial meniscectomy.

METHODS

For this prospective cohort study, 14 patients (five female) with a mean age of 47.9 ± 12.9 years who had undergone isolated arthroscopic partial medial meniscectomy were evaluated. Cartilage-sensitive magnetic resonance imaging (MRI) scans were acquired from the operated knees before the index operations, as well as at 6, 12, and 24 months after surgery. The MRI scans were assessed for the prevalence, severity, and size of cartilage degenerations. The clinical outcome was assessed using the SF-36 physical and mental component score and the International Knee Documentation Committee Knee Evaluation Form and was correlated with radiological findings.

RESULTS

There was a significant increase in the severity of cartilage lesions in the medial tibial plateau (P = 0.019), as well as a trend towards an increase in the lateral tibial plateau. The size of the cartilage lesions increased significantly in the medial femoral condyle (P = 0.005) and lateral femoral condyle (P = 0.029), as well as in the patella (P = 0.019). Functional outcome scores improved significantly throughout the follow-up period. There was no correlation between cartilage wear and functional outcome.

CONCLUSIONS

Arthroscopic partial medial meniscectomy is associated with adverse effects on articular cartilage and may lead to an increase in the severity and size of cartilage lesions. Post-operative cartilage wear predominantly affected the medial compartment and also affected the other compartments of the knee. Strategies to reduce subsequent osteoarthritic changes need to involve all compartments of the knee.

LEVEL OF EVIDENCE

IV.

The magnetic resonance aspect of a polyurethane meniscal scaffold is worse in advanced cartilage defects without deterioration of clinical outcomes after a minimum two-year follow-up

BACKGROUND

Meniscal scaffolding is thought to provide functional improvement and to prevent cartilage degeneration. Advanced chondral injuries might damage the scaffold structural properties.

OBJECTIVE

To evaluate the influence of different degrees of articular chondral injuries on the imaging aspect of a polyurethane meniscal scaffold (Actifit®).

METHODS

Fifty-four patients operated on with an Actifit® were studied. The status of the articular cartilage in the involved compartment was classified according to ICRS. The characteristics of the implant were evaluated in MRI with the Genovese score. Functional scores included WOMET, IKDC and Kujala scores. The Genovese score was correlated with the degree of chondral injury and functional results.

RESULTS

The mean follow-up was 39 months (range 25-63). Additional procedures were performed in 69.5%. There were 19 patients without chondral injuries and 14 with grade 1, 10 with grade 3 and eight with grade 4 chondral lesions. The morphology and size of the implant on MRI scanning were worse with a higher degree of chondral injury (p=0.023). WOMET, IKDC and Kujala improved from 36.2SD ±7.6, 32.3SD ±13.5 and 39.2SD ±8.1 to 75.8SD ±12.9 (p=0.02), 75.5SD ±15.4 (p=0.03) and 85.6SD ±13.4 (0.042), respectively. There was no relationship between the severity of chondral injury and functional scores.

CONCLUSIONS

Patients without chondral injuries showed a better MRI aspect of the polyurethane scaffold in terms of size and morphology. By optimizing biomechanics, in particular the implantation of a meniscal substitute, significant pain relief and functional improvement were observed after a minimum two-year follow-up.

LEVEL OF EVIDENCE

Therapeutic case series; level 4.

Short-term effects of partial meniscectomy on the clinical results of anterior cruciate ligament reconstruction

PURPOSE

This study aims to analyse the short-term effects of partial meniscectomy on the clinical results of anterior cruciate ligament reconstruction surgery.

METHODS

Clinical outcomes of 19 patients who had partial medial meniscectomy and anterior cruciate ligament reconstruction during the same surgery (Group 1) were compared with the outcomes of 25 patients who had also reconstruction but did not have any meniscal lesion (Group 2). Median follow-up time was 29 months (range 12-67 months) in Group 1 and 27 months (range 12-70 months) in Group 2. Feeling of apprehension in sports activities, International Knee Documentation Committee (IKDC) score, KT-2000 Arthrometer(®) measurements and post-operative time to return to sports activity were the criteria for data analysis.

RESULTS

Eight patients (42%) in Group 1 and 5 patients (20%) in Group 2 stated feeling of apprehension in sports activities. IKDC score improved to A in 11 patients (58%) from Group 1, and 18 patients (72%) from Group 2. Mean anterior translation according to KT-2000 arthrometer measurements was 5.2 ± 1.3 mm in Group 1, and 4.6 ± 1.3 mm in Group 2. Post-operative time to return to sports activity was 8.5 ± 3.0 months in Group 1, and 6.5 ± 2.2 months in Group 2.

CONCLUSION

Partial meniscectomy for irreparable medial meniscal tears, applied during the same surgery with anterior cruciate ligament reconstruction, negatively affects the clinical outcomes in the short-term follow-up. This study may be a reference for long-term clinical trials and also future investigations of new methods in the treatment of similar cases.

LEVEL OF EVIDENCE

IV.

Role of mesenchymal stem cells in meniscal repair

Meniscus integrity is the key for joint health of the knee. Therefore, the main goal of every meniscus treatment should be the maintenance of as much meniscus tissue as possible.

Repair of meniscus tears can be achieved by meniscus suture. However, in a recently published meta-analysis, the long-term outcome of meniscus repair showed a mean failure rate of 24%.

In a preclinical trial, locally applied mesenchymal stem cells produced differentiated meniscus-like tissue in meniscus tears indicating that mesenchymal-based cells, harvested from the bone marrow, enhance meniscus healing in critical-size meniscus tears.

Symptomatic meniscus defects offer the option for meniscus transplantation with porous cell free biomaterials, when a complete meniscus rim is available. Cell-free biomaterials, which are actually in clinical application, reveal variable outcome in mid-term results from complete failure to regeneration with meniscus-like tissue.

In several preclinical studies with different critical-size defects in the meniscus, the application of mesenchymal stem cells could significantly enhance meniscus regeneration compared to empty defects or to cell-free biomaterials.

Regenerative treatment of meniscus with mesenchymal stem cells seems to be a promising approach to treat meniscal tears and defects. However it is still not clear, whether the stem cell effect is a direct action of the mesenchymal-based cells or is rather mediated by secretion of certain stimulating factors. The missing knowledge of the underlying mechanism is one of the reasons for regulatory burdens to permit these stem cell-based strategies in clinical practice. Other limitations are the necessity to expand cells prior to transplantation resulting in high treatment costs. Alternative treatment modalities, which use growth factors concentrated from peripheral blood aspirates or mononucleated cells concentrated from bone marrow aspirates, are currently in development in order to allow an attractive one-step procedure without the need for cell expansion in cultures and thus lower efforts and costs.

In summary, Tissue Engineering of meniscus with mesenchymal based cells seems to be a promising approach to treat meniscal tears and defects in order to restore native meniscus tissue. However, advances of the technology are necessary to allow clinical application of this modern regenerative therapy.

Return to Play After Partial Lateral Meniscectomy in National Football League Athletes

BACKGROUND

Lateral meniscal injury is a common and possibly career-threatening injury among players in the National Football League (NFL). The rate of return to play (RTP) and factors that affect RTP after lateral meniscal injury in NFL players are currently not defined.

PURPOSE

The aims of this study were to determine the rate of RTP to regular-season NFL game play of NFL players after arthroscopic partial lateral meniscectomy and to identify factors that can predict the ability to return to play.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Seventy-two patients undergoing 77 arthroscopic lateral partial meniscectomies were followed to determine the rate of RTP (defined as successful RTP in at least 1 regular-season NFL game after meniscectomy) and factors predicting players' ability to return to play. Perioperative variables were recorded using retrospective chart review. Players' heights and weights, dates of return, draft rounds, and counts of games, starts, and seasons both before and after meniscectomy were all collected from statistical databases maintained by the NFL. Chi-square and Student t tests were performed to assess differences among covariates with respect to an athlete's ability to return to play, and odds ratios were calculated as appropriate. All percentages were calculated as percent of total procedures performed (n = 77).

RESULTS

Of the 77 partial lateral meniscectomies performed, 61% (n = 47) resulted in the athlete returning to play at his previous level of competition with an average length of time to RTP of 8.5 months; 19 (40%) of those who returned were still active in the NFL at the time of follow-up. Age at time of surgery, games and seasons played before surgery, and individual position were not significantly different between those who did and did not return to play. Undergoing a concomitant procedure did not affect an athlete's ability to return to play, nor did concurrent arthroscopic anterior cruciate ligament reconstruction affect a player's likelihood to return to play. Players drafted in the first 4 rounds of the NFL draft were 3.7 times more likely to return to play than players drafted after the fourth round, and players who started more than 46.2% of their games played (the mean value for this population) were 2.8 times more likely to return to play. Speed-position players (running backs, receivers, linebackers, and defensive backs) were 4.0 times less likely to return to play than non-speed position players (linemen and tight ends).

CONCLUSION

The majority of NFL players undergoing arthroscopic lateral meniscectomy are able to return to play. Players selected earlier in the NFL draft and who are listed as starters in more of their games are more likely to return to play, as are linemen and tight ends. It is significantly more difficult for running backs, receivers, linebackers, and defensive backs to return to play.

Treatment of meniscal tears: An evidence based approach

Treatment options for meniscal tears fall into three broad categories; non-operative, meniscectomy or meniscal repair. Selecting the most appropriate treatment for a given patient involves both patient factors (e.g., age, co-morbidities and compliance) and tear characteristics (e.g., location of tear/age/reducibility of tear). There is evidence suggesting that degenerative tears in older patients without mechanical symptoms can be effectively treated non-operatively with a structured physical therapy programme as a first line. Even if these patients later require meniscectomy they will still achieve similar functional outcomes than if they had initially been treated surgically. Partial meniscectomy is suitable for symptomatic tears not amenable to repair, and can still preserve meniscal function especially when the peripheral meniscal rim is intact. Meniscal repair shows 80% success at 2 years and is more suitable in younger patients with reducible tears that are peripheral (e.g., nearer the capsular attachment) and horizontal or longitudinal in nature. However, careful patient selection and repair technique is required with good compliance to post-operative rehabilitation, which often consists of bracing and non-weight bearing for 4-6 wk.

Trends in meniscus repair and meniscectomy in the United States, 2005-2011

BACKGROUND

Meniscus deficiency may lead to degenerative arthritis in the knee. There is a significant emphasis on meniscus preservation, particularly in the young patient, to reduce the risk of arthritis.

PURPOSE

To report on the incidence of meniscus repair and meniscectomy, with and without concomitant anterior cruciate ligament (ACL) reconstruction, in the United States (US) over the past 7 years.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

Patients who underwent arthroscopic meniscectomy (Current Procedural Terminology [CPT] codes 29880 and 29881), meniscus repair (CPT codes 29882 and 29883), and ACL reconstruction (CPT code 29888) for the years 2005 through 2011 were identified using the PearlDiver Patient Record Database. Age group and sex were collected for each patient. Patient groups included meniscectomy alone, meniscus repair alone, meniscus repair followed by meniscectomy, ACL reconstruction with concomitant meniscus repair, and ACL reconstruction with concomitant meniscus repair followed by meniscectomy. Linear regression and Student t tests were utilized for comparisons, with an α value of .05 set as significant.

RESULTS

The database represented approximately 9% of the US population under 65 years of age. There was no significant change in the number of patients in the covered population during the study time frame (P = .138). From 2005 to 2011, there were a total of 387,833 meniscectomies, 23,640 meniscus repairs, and 84,927 ACL reconstructions. There was a significant increase in the total number of isolated meniscus repairs performed (P = .001) and a doubling of the incidence of repairs from 2005 to 2011. There was no significant increase in the total number of meniscectomies performed (P = .712), while the incidence of meniscectomies increased only 14% from 2005 to 2011. There was no significant change in the number of meniscus repairs performed at the same time as ACL reconstruction during the study time frame. The total number and incidence of meniscectomies after repair with and without ACL reconstruction significantly decreased.

CONCLUSION

There has been an increased number of isolated meniscus repairs being performed in the US over the past 7 years without a concomitant increase in meniscectomies over the same time frame. These data suggest that meniscus repairs are preferentially being performed over meniscectomies.

Review of Meniscal Allograft Transplantation Focusing on Long-term Results and Evaluation Methods

With recognition of the biomechanical role of the meniscus, such as load distribution and joint stability in the knee joint, there has been a shift in the treatment of meniscal tears from open total meniscectomy to preservation of the meniscal functions as much as possible with symptomatic relief. Recently, technical development of meniscal surgery, with advanced arthroscopic equipment and instruments, enables biological reconstruction of load bearing functions in the meniscus deficient knee through allograft tissue transplantation as well as repair of torn menisci. Meniscal allograft transplantation (MAT) has been considered as one of the few viable treatment options for the young meniscectomized knees based on various animal experiments and clinical studies. Still, there is insufficient evidence for the long-term chondroprotective effect of human MAT. Some long-term follow-up studies showed that the technique resulted in graft degeneration, deformation, and tear, and structural changes in the remodeling process in early MAT cases, disrupting functional restoration of the original meniscus. Nevertheless, advanced outcomes are documented in some recent studies. The purpose of this article is to review the mid- and long-term follow-up results of MAT and to improve understanding of MAT with evaluation methods of meniscal transplants using magnetic resonance imaging or second-look arthroscopy.

Subject-specific analysis of joint contact mechanics: application to the study of osteoarthritis and surgical planning

Advances in computational mechanics, constitutive modeling, and techniques for subject-specific modeling have opened the door to patient-specific simulation of the relationships between joint mechanics and osteoarthritis (OA), as well as patient-specific preoperative planning. This article reviews the application of computational biomechanics to the simulation of joint contact mechanics as relevant to the study of OA. This review begins with background regarding OA and the mechanical causes of OA in the context of simulations of joint mechanics. The broad range of technical considerations in creating validated subject-specific whole joint models is discussed. The types of computational models available for the study of joint mechanics are reviewed. The types of constitutive models that are available for articular cartilage are reviewed, with special attention to choosing an appropriate constitutive model for the application at hand. Issues related to model generation are discussed, including acquisition of model geometry from volumetric image data and specific considerations for acquisition of computed tomography and magnetic resonance imaging data. Approaches to model validation are reviewed. The areas of parametric analysis, factorial design, and probabilistic analysis are reviewed in the context of simulations of joint contact mechanics. Following the review of technical considerations, the article details insights that have been obtained from computational models of joint mechanics for normal joints; patient populations; the study of specific aspects of joint mechanics relevant to OA, such as congruency and instability; and preoperative planning. Finally, future directions for research and application are summarized.