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This study investigated the role of the material properties assumed for articular cartilage, meniscus and meniscal attachments on the fit of a finite element model (FEM) to experimental data for meniscal motion and deformation due to an anterior tibial loading of 45 N in the anterior cruciate ligament-deficient knee. Taguchi style L18 orthogonal arrays were used to identify the most significant factors for further examination. A central composite design was then employed to develop a mathematical model for predicting the fit of the FEM to the experimental data as a function of the material properties and to identify the material property selections that optimize the fit. The cartilage was modeled as isotropic elastic material, the meniscus was modeled as transversely isotropic elastic material, and meniscal horn and the peripheral attachments were modeled as noncompressive and nonlinear in tension spring elements. The ability of the FEM to reproduce the experimentally measured meniscal motion and deformation was most strongly dependent on the initial strain of the meniscal horn attachments (epsilon(1H)), the linear modulus of the meniscal peripheral attachments (E(P)) and the ratio of meniscal moduli in the circumferential and transverse directions (E(theta)E(R)). Our study also successfully identified values for these critical material properties (epsilon(1H) = -5%, E(P) = 5.6 MPa, E(theta)E(R) = 20) to minimize the error in the FEM analysis of experimental results. This study illustrates the most important material properties for future experimental studies, and suggests that modeling work of meniscus, while retaining transverse isotropy, should also focus on the potential influence of nonlinear properties and inhomogeneity.

The menisci are believed to play a stabilizing role in the ACL-deficient knee, and are known to be at risk for degradation in the chronically unstable knee. Much of our understanding of this behavior is based on ex vivo experiments or clinical studies in which we must infer the function of the menisci from external measures of knee motion. More recently, studies using magnetic resonance (MR) imaging have provided more clear visualization of the motion and deformation of the menisci within the tibio-femoral articulation. In this study, we used such images to generate a finite element model of the medial compartment of an ACL-deficient knee to reproduce the meniscal position under anterior loads of 45, 76, and 107 N. Comparisons of the model predictions to boundaries digitized from images acquired in the loaded states demonstrated general agreement, with errors localized to the anterior and posterior regions of the meniscus, areas in which large shear stresses were present. Our model results suggest that further attention is needed to characterize material properties of the peripheral and horn attachments. Although overall translation of the meniscus was predicted well, the changes in curvature and distortion of the meniscus in the posterior region were not captured by the model, suggesting the need for refinement of meniscal tissue properties.

To compare the clinical outcome of patients treated with and without platelet-rich plasma (PRP) injection while undergoing arthroscopic labral repair and femoral neck osteoplasty for femoral acetabular impingement. Patients were randomized at the time of surgery to receive either an intra-articular injection of 5 cc of PRP, or an equal volume of 0.9% normal saline. All patients underwent arthroscopic labral repair and osteoplasty of the femoral neck and, at the conclusion of the case, received the injection. One week following surgery, thigh circumference (measured 10 cm distal to the tip of the greater trochanter) and the presence of ecchymosis of the thigh were recorded. Clinical outcome scores, including Non-Arthritic Hip Score, Modified Harris Hip Score and Hip Outcome Score were collected prior to surgery at 1, 3, 6 and a minimum of 12 months post-operatively. Thirty-five patients were enrolled into this study. Twenty patients received a PRP injection and 15 received a saline injection. Thigh circumference was compared pre-operatively and 1 week post-operatively. There was no significant difference between the two groups. Ecchymosis was compared between the two groups at 1 week post-operatively. Four of the 20 patients in the PRP group and 10 of the 15 in the placebo group demonstrated bruising on the lateral thigh. This was compared with a Chi-Square test and found to be statistically significant (P = 0.005). There was no significant difference in any of the outcome scores between the two groups. An intra-articular injection of PRP after labral repair did not improve the clinical outcome up to 1 year post-operatively in patients undergoing arthroscopic labral repair and osteoplasty of the femoral neck. Level of evidence is level I study.

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Background: The rate of return to sport after surgical treatment of femoroacetabular impingement (FAI) syndrome (FAIS) has been studied in high-level athletes. However, few studies examining this rate have focused exclusively on National Collegiate Athletic Association (NCAA) Division I athletes. Purpose: To evaluate the return-to-sport rate after hip arthroscopy for FAIS and to examine the influence of sport type on the clinical presentation of FAIS in collegiate athletes. Study Design: Case series; Level of evidence, 4. Methods: Included in this study were NCAA Division I student-athletes who underwent hip arthroscopy for FAIS at our institution between 2010 and 2017. Exclusion criteria were history of previous hip pathology, pediatric hip disease, radiographic evidence of osteoarthritis (Tönnis grade >0), prior lower extremity procedure, history of chronic pain, osteoporosis, or history of systemic inflammatory disease. Athletes were categorized into 6 subgroups based on the type of sport (cutting, contact, endurance, impingement, asymmetric/overhead, and flexibility) by using a previously reported classification system. Patient characteristics and preoperative, intraoperative, and return-to-sport variables were compared among sport types. Results: A total of 49 hip arthroscopies for FAIS were performed in 39 collegiate athletes (10 females, 29 males; mean age, 19.5 ± 1.3 years). A total of 1 (2.6%) cutting athlete, 15 (38.5%) contact athletes, 8 (20.5%) impingement athletes, 6 (15.4%) asymmetric/overhead athletes, and 9 (23.1%) endurance athletes were included in the study. There were no differences among sports groups with respect to the FAI type. Endurance athletes had lower rates of femoral osteochondroplasty (45.5%) and labral debridement (0.0%) ( P < .0001). Contact sport athletes had higher rates of labral debridement (50.0%; P < .0001). Patients were evaluated for return to sport at an average of 1.96 ± 0.94 years. Overall, the return-to-sport rate was 89.7%. There were no differences in return-to-sport rates based on the sport type except for endurance athletes, who returned at a lower rate (66.6%; P < .001). No differences in return-to-sport rate ( P = .411), duration after return ( P = .265), or highest attempted level of sport resumed ( P = .625) were found between patients who underwent labral repair versus debridement. Conclusion: Collegiate-level athletes who underwent hip arthroscopy for FAIS returned to sport at high and predictable rates, with endurance athletes possibly returning to sport at lower rates than all other sport types. Surgical procedures may be influenced by sport type, but the rate of return to sport between athletes who underwent labral debridement versus labral repair was similar.

Osteoarthritis is the most common form of arthritis and can be a major source of disability. Many older patients continue to be active in sportsrelated activities. Therefore, treating an active patient with osteoarthritis is becoming more common. Physical therapy and weight loss continue to play a central role in the treatment of patients with osteoarthritis. Nonsteroidal anti-inflammatory drugs decrease inflammation and swelling, which makes physical therapy more effective. Intra-articular corticosteroids have been used for the treatment of osteoarthritis. However, no guidelines exist for the administration of corticosteroids and they can be associated with increased risk of tendon rupture and infection. Viscosupplementation has gained popularity in the treatment of osteoarthritis of the knee. Intra-articular injections of hyaluronic acid have been shown to decrease pain and improve functional outcomes.

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