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Meniscal tears are common injuries, and while partial meniscectomy is a frequent treatment option, general meniscus loss is a risk factor for the development of osteoarthritis. The goal of this study was to measure the in vivo tibiofemoral cartilage contact patterns in patients with meniscus tears in relation to biomarkers of cartilage catabolism in the synovial fluid of these joints. A combination of magnetic resonance imaging and biplanar fluoroscopy was used to determine the in vivo motion and cartilage contact mechanics of the knee. Subjects with isolated medial meniscus tears were analyzed while performing a quasi-static lunge, and the contralateral uninjured knee was used as a control. Synovial fluid was collected from the injured knee and matrix metalloproteinase (MMP) activity, sulfated glycosaminoglycan, cartilage oligomeric matrix protein, prostaglandin E2, and the collagen type II cleavage biomarker C2C were measured. Contact strain in the medial compartment increased significantly in the injured knees compared to contralateral control knees. In the lateral compartment, the contact strain in the injured knee was significantly increased only at the maximum flexion angle (105°). The average cartilage strain at maximum flexion positively correlated with total MMP activity in the synovial fluid. These findings show that meniscal injury leads to loss of normal joint function and increased strain of the articular cartilage, which correlated to elevated total MMP activity in the synovial fluid. The increased strain and total MMP activity may reflect, or potentially contribute to, the early development of osteoarthritis that is observed following meniscal injury.

Altered cartilage loading is believed to be associated with osteoarthritis development. However, there are limited data regarding the influence of normal gait, an essential daily loading activity, on cartilage strains. In this study, 8 healthy subjects with no history of knee surgery or injury underwent magnetic resonance imaging of a single knee prior to and following a 20-min walking activity at approximately 1.1m/s. Bone and cartilage surfaces were segmented from these images and compiled into 3-dimensional models of the tibia, femur, and associated cartilage. Thickness changes were measured across a grid of evenly spaced points spanning the models of the articular surfaces. Averaged compartmental strains and local strains were then calculated. Overall compartmental strains after the walking activity were found to be significantly different from zero in all four tibiofemoral compartments, with tibial cartilage strain being significantly larger than femoral cartilage strain. These results provide baseline data regarding the normal tibiofemoral cartilage strain response to gait. Additionally, the technique employed in this study has potential to be used as a “stress test” to understand how factors including age, weight, and injury influence tibiofemoral cartilage strain response, essential information in the development of potential treatment strategies for the prevention of osteoarthritis.

Background: There is an association between throwing activity and glenohumeral internal rotation deficit (GIRD). An 18° to 20° deficit has been adopted as the standard definition of pathological GIRD, but specific findings as to how GIRD relates to an injury are inconsistent. Purpose: To systematically review the literature to clarify the definition of GIRD diagnosis for adolescent and adult overhead athletes and to examine the association between GIRD and an increased risk of injuries in these athletes. Study Design: Systematic review; Level of evidence, 4. Methods: A systematic review of the literature was performed. Observational studies comparing glenohumeral internal rotation range of motion (ROM) in injured and uninjured overhead athletes were included for the meta-analysis. Studies of adolescent and adult athletes were analyzed separately. ROM was compared for the injured and uninjured groups, and a weighted mean GIRD was estimated. To account for potential heterogeneity across studies, both fixed- and random-effects models were used to calculate a standardized mean difference (SMD). Results: Nine studies of level 3 or 4 evidence were included. From these, 12 study groups (4 adolescent, 8 adult) comprising 819 overhead athletes (226 injured, 593 uninjured) were included in the meta-analysis. The estimated SMD in GIRD between the injured and uninjured groups was 0.46 (95% CI, 0.15-0.77; P < .01) for the overall sample. The between-group effect was larger for adults (SMD, 0.60 [95% CI, 0.18 to 1.02]; P < .01) than adolescents (SMD, 0.20 [95% CI, –0.24 to 0.63]; P = .13). The weighted mean GIRD for the injured and uninjured groups was 13.8° ± 5.6° and 9.6° ± 3.0°, respectively, which also differed by age group. Moderate study heterogeneity was observed (I 2 = 69.0%). Conclusion: Based on this systematic review, the current definition of pathological GIRD may be too conservative, and a distinct definition may be required for adolescent and adult athletes. While the results indicate a link between internal rotation deficits and upper extremity injuries in the overhead athlete, higher quality prospective research is needed to clarify the role that GIRD plays in future injuries to overhead athletes of various ages.

Purpose Instability of the proximal tibiofibular joint (PTFJ) can be treated with bicortical suspension (BCS) fixation. However, the ideal location, orientation, and configuration to apply one or two BCS devices are not clear. Methods A finite-element model of the PTFJ was created from a female adult’s CT dataset. Anterior and posterior ligaments at the PTFJ were modeled and suppressed to simulate stable and unstable joints. Fifty-six models simulated 56 device placements along guiding tunnel lines that connect eight entry locations on the fibular head to seven exit points on the anteromedial tibia. Doubling device stiffness created 56 more models. Combing any two placements created 1176 double-device configurations which were categorized to be crossed, divergent or parallel. Displacement of the fibular head relative to the fixed tibia under 100 N anterolateral and posteromedial forces was assessed. Results Different placements had 2.1–27.9 mm translation with 0.7–8.9° internal rotation under anterolateral loading, and 1.8–5.2 mm translation with 6.1–7.9° external rotation under posteromedial loading. More transverse and superior orientations were associated with smaller anterolateral translation; more posterior and superior entry locations were associated with smaller internal rotation. The median (IQR) reductions in anterolateral translation by doubling device stiffness and by adding a second device were 0.8 (IQR 0.5–1.0) and 0.8 (IQR 0–6.1) mm, respectively. The type of double-device configurations had no significant effect on fibular motion. Conclusion Surgeons should drill the guiding tunnel superiorly and transversely to ensure the optimal restoration of the PTFJ anterolateral stability.

Purpose To perform a systematic review aimed to determine (1) if the postural stability deficit represents a risk factor for ankle sprains; (2) the most effective postural stability evaluation to predict ankle sprains and (3) eventual confounding factors that could influence postural stability and ankle sprain risk. Methods A systematic electronic search was performed in MEDLINE, EMBASE and CINAHL using the search terms (balance) OR (postural stability) matched with (lower limb) OR (ankle) OR (foot) and (sprain) OR (injury) on October 2 2017. All prospective studies that evaluated postural stability as risk factor for ankle sprains were included. The PRISMA Checklist guided the reporting and data abstraction. Methodological quality of all included papers was carefully assessed. Results Fifteen studies were included, evaluating 2860 individuals. Various assessment tools or instruments were used to assess postural stability. The injury incidence ranged from 10 to 34%. Postural stability deficit was recognized as risk factor for ankle sprain (OR = 1.22–10.2) in 9 cases [3 out of 3 with Star Excursion Balance Test (SEBT)]. Among the six studies that measured the center-of-gravity sway, five were able to detect worse postural stability in athletes that sustained an ankle sprain. In nine cases, the measurement of postural stability did not show any statistical relationship with ankle sprains (four out of five with examiner evaluation). In the studies that excluded patients with history of ankle sprain, postural stability was reported to be a significant risk factor in five out of six studies. Conclusions The ultimate role of postural stability as risk factor for ankle sprains was not defined, due to the high heterogeneity of results, patient’s populations, sports and methods of postural stability evaluation. Regarding assessment instruments, measurement of center-of-gravity sway could detect athletes at risk, however, standardized tools and protocols are needed to confirm this finding. The SEBT could be considered a promising tool that needs further investigation in wider samples. History of ankle sprains is an important confounding factor, since it was itself a source of postural stability impairment and a risk factor for ankle sprains. These information could guide clinicians in developing screening programs and design further prospective cohort studies comparing different evaluation tools. Level of evidence I (systematic review of prospective prognostic studies).

Hamstring muscle strain injury is one of the most commonly seen injuries in sports such as track and field, soccer, football, and rugby. The purpose of this study was to advance our understanding of the mechanisms of hamstring muscle strain injuries during over ground sprinting by investigating hamstring muscle–tendon kinematics and muscle activation. Three-dimensional videographic and electromyographic (EMG) data were collected for 20 male runners, soccer or lacrosse players performing overground sprinting at their maximum effort. Hamstring muscle–tendon lengths, elongation velocities, and linear envelop EMG data were analyzed for a running gait cycle of the dominant leg. Hamstring muscles exhibited eccentric contractions during the late stance phase as well as during the late swing phase of overground sprinting. The peak eccentric contraction speeds of the hamstring muscles were significantly greater during the late swing phase than during the late stance phase ( p=0.001) while the hamstring muscle–tendon lengths at the peak eccentric contraction speeds were significantly greater during the late stance phase than during the late swing phase ( p=0.001). No significant differences existed in the maximum hamstring muscle–tendon lengths between the two eccentric contractions. The potential for hamstring muscle strain injury exists during the late stance phase as well as during the late swing phases of overground sprinting.

Due to the biphasic viscoelastic nature of cartilage, joint loading may result in deformations that require times on the order of hours to fully recover. Thus, cartilaginous tissues may exhibit cumulative strain over the course of each day. The goal of this study was to assess the magnitude and spatial distribution of strain in the articular cartilage of the knee with daily activity. Magnetic resonance (MR) images of 10 asymptomatic subjects (six males and four females) with mean age of 29 years were obtained at 8:00 AM and 4:00 PM on the same day using a 3T magnet. These images were used to create 3D models of the femur, tibia, and patella from which cartilage thickness distributions were quantified. Cartilage thickness generally decreased from AM to PM in all areas except the patellofemoral groove and was associated with significant compressive strains in the medial condyle and tibial plateau. From AM to PM, cartilage of the medial tibial plateau exhibited a compressive strain of −5.1±1.0% (mean±SEM) averaged over all locations, while strains in the lateral plateau were slightly lower (−3.1±0.6%). Femoral cartilage showed an average strain of −1.9±0.6%. The findings of this study show that human knee cartilage undergoes diurnal changes in strain that vary with site in the joint. Since abnormal joint loading can be detrimental to cartilage homeostasis, these data provide a baseline for future studies investigating the effects of altered biomechanics on diurnal cartilage strains and cartilage physiology.

Purpose To investigate the influence of injury and treatment factors on clinical/functional outcomes in multiligament knee injuries (MLKI). Methods Thirty-nine consecutive patients with confirmed and surgically treated MLKI who met inclusion criteria were scheduled for a follow-up visit to obtain: SF-12 and subjective feeling of normalcy between the operated and healthy knee, and IKDC, active range of motion (ROM), and stability exam (Lachman test, posterior drawer, and dial test at 30°). A chart review was used to obtain data on injury and treatment factors. Results The postoperative mean (SD) outcomes were: IKDC score 62.7 (25.9), flexion–extension ROM 125° (29°), and percentage of normalcy 74% (20%). The postoperative normal/nearly normal stability exam was: Lachman test 36 (95%) patients, posterior drawer at 90° 38 (97%) patients, and dial test of 39 (100%) patients. There were 24 (61.5%) and 23 (59%) patients with complications and reoperations, respectively. The presence of bicruciate injuries was associated with worse Lachman ( p  = 0.03) and posterior drawer tests ( p  = 0.03). Presence of injury to meniscal structures was associated with worse Lachman test ( p  = 0.03), lower percentage of normalcy ( p  = 0.02) and extension lag ( p  = 0.04). Injury to cartilage structures was associated with worse IKDC scores ( p  = 0.04). IKDC was lower in cases of posterolateral corner reconstruction ( p  = 0.03) and use of allograft tendons for reconstruction ( p  = 0.02); ROM was lower in allograft reconstruction ( p  = 0.02) and need for meniscal repair (p = 0.01). Bicruciate reconstruction led to worst posterior drawer test ( p  = 0.006). Conclusions The outcomes of MLKI might be negatively influenced by bicruciate ligament, meniscal, and cartilage injuries; with regards to treatment characteristics, need for posterolateral corner or bicruciate ligament reconstruction, use of allografts, or need for meniscal repair may similarly diminish outcomes. While surgical treatment provides good overall function, ROM and stability, it rarely results in a “normal” knee and the chances of complications and reoperations are high. Level of evidence Cross-sectional comparative study, Level III

Anatomically placed grafts are believed to more closely restore the function of the ACL. This study measured the effect of femoral tunnel placement on graft orientation and length during weight-bearing flexion. Both knees of twelve patients where the graft was placed near the anteroproximal border of the ACL and ten where the graft was placed near the center of the ACL were imaged using MR. These images were used to create 3D models of the reconstructed and intact contralateral knees, including the attachment sites of the native ACL and graft. Next, patients were imaged using biplanar fluoroscopy while performing a quasi-static lunge. The models were registered to the fluoroscopic images to reproduce in vivo knee motion. From the relative motion of the attachment sites on the models, the length and orientation of the graft and native ACL were measured. Grafts placed anteroproximally on the femur were longer and more vertical than the native ACL in both the sagittal and coronal planes, while anatomically placed grafts more closely mimicked ACL motion. In full extension, the grafts placed anteroproximally were 12.3±5.2° (mean and 95%CI) more vertical than the native ACL in the sagittal plane, whereas the grafts placed anatomically were 2.9±3.7° less vertical. Grafts placed anteroproximally were up to 6±2 mm longer than the native ACL, while the anatomically placed grafts were a maximum of 2±2 mm longer. In conclusion, grafts placed anatomically more closely restored native ACL length and orientation. As a result, anatomic grafts are more likely to restore intact knee kinematics.