CRISPR screens identify genes essential for in vivo virulence among proteins of hyperLOPIT-unassigned subcellular localization in Toxoplasma.

The research field to identify and characterize genes essential for in vivo virulence in Toxoplasma gondii has been dramatically advanced by a series of in vivo clustered regularly interspaced short palindromic repeats (CRISPR) screens. Although subcellular localizations of thousands of proteins were predicted by the spatial proteomic method called hyperLOPIT, those of more than 1,000 proteins remained unassigned, and their essentiality in virulence was also unknown. In this study, we generated two small-scale gRNA libraries targeting approximately 600 hyperLOPIT-unassigned proteins and performed in vivo CRISPR screens. As a result, we identified several genes essential for in vivo virulence that were previously unreported. We further characterized two candidates, TgGTPase and TgRimM, which are localized in the cytoplasm and the apicoplast, respectively. Both genes are essential for parasite virulence and widely conserved in the phylum Apicomplexa. Collectively, our current study provides a resource for estimating the in vivo essentiality of Toxoplasma proteins with previously unknown localizations.IMPORTANCEToxoplasma gondii is a protozoan parasite that causes severe infection in immunocompromised patients or newborns. Toxoplasma possesses more than 8,000 genes; however, the genes essential for in vivo virulence were not fully identified. The apicomplexan parasites, including Toxoplasma, developed unique organelles that do not exist in other model organisms; thus, determining the subcellular location of parasite proteins is important for understanding their functions. Here, we used in vivo genetic screens that enabled us to investigate hundreds of genes in Toxoplasma during mouse infection. We screened approximately 600 parasite proteins with previously unknown subcellular localizations. We identified many novel genes that confer parasite virulence in mice. Among the top hits, we characterized two genes essential for in vivo virulence, TgGTPase and TgRimM, which are widely conserved in the phylum Apicomplexa. Our findings will contribute to understanding how apicomplexans adapt to the host environment and cause disease.

Association of Stability and Size of Unhealed Area With Failure After Internal Fixation for Osteochondritis Dissecans Lesions of the Knee: Radiological Evaluation Using Computed Tomography.

BACKGROUND: Open reduction and internal fixation (ORIF) has been widely performed because the osteochondral component of the osteochondritis dissecans (OCD) lesion is the most suitable for reconstructing the joint structure. PURPOSE: To evaluate radiological healing in terms of reconstructed bony structure after ORIF with bone graft by computed tomography (CT), to identify preoperative prognostic factors for failure, and to determine the cutoff value of radiological healing for risk of failure. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: A retrospective cohort study of 42 patients (44 knees) who underwent internal fixation with bone graft for OCD lesions of the knee from 2004 to 2018 was conducted. All patients were evaluated 6 months postoperatively, and if not healed 6 months after surgery, they were evaluated by CT periodically thereafter. Radiological healing was judged according to the following 3 criteria: (1) reossification of the OCD lesion, (2) bony continuity between the OCD lesion and basal floor, and (3) reconstructed bony surface of the femoral condyle reconstructed to match the normal joint. Then, the percentage of the radiological healing area was calculated as the ratio of the healing length to the total lesion length. The nonhealing area was calculated by multiplying the sum of the total nonhealing length. Clinical failure was defined as any definitive reoperation for the same OCD lesion, such as fragment excision, or a cartilage restoration procedure. After 6 months, all eligible patients underwent arthroscopy to check for protrusion of the absorbable pin into the joint; the removal of an absorbable pin protruding into the joint was not considered a failure. RESULTS: Clinical failure was recorded for 4 cases (9.1%). The mean overall percentage of the radiological healing area of OCD 6 months after ORIF with bone graft was 79.5% ± 24.4%, and the mean overall nonhealing area at 6 months was 87.8 ± 107.9 mm2. The percentages of radiological healing area of stable (International Cartilage Regeneration & Joint Preservation Society OCD II) lesions and femoral condylar (lateral femoral condyle + medial femoral condyle) lesions were significantly lower than unstable lesions and femoral groove lesions, respectively (P = .01 and P = .03, respectively). On receiver operating characteristic curve analysis, the cutoff points for predicting a significantly increased risk of failure were 33.9% (sensitivity, 100%; specificity, 100%; area under the curve, 1) for the percentage of radiological healing area and 222.9 mm2 (sensitivity, 95%; specificity, 100%; area under the curve, 0.956) for the nonhealing area 6 months postoperatively. CONCLUSION: A stable lesion and a femoral condylar lesion were the predictors of poor radiological healing on CT images 6 months after ORIF with bone graft. The risk of failure was increased significantly in cases with only approximately one-third of the lesion healed or in cases with large nonhealing areas at 6 months postoperatively.

Clinical outcomes after repair of an isolated radial tear in the middle segment of the lateral meniscus - All-inside suture repair vs trans-capsular suture repair.

Background/objective: For radial tears, all-inside suture (AIS) repair was clearly biomechanically superior, compared to conventional trans-capsular suture (TCS) repairs. However, clinical comparative studies of these two repairs techniques have not to be performed. Therefore, the aim of this study was to compare the clinical outcomes after AIS repair and TCS repairs for isolated radial tear at middle segment of lateral meniscus (RTMLM) in stable knees of young athletes. Methods: Twenty-six athletes (mean age, 19.1 years) underwent AIS repair with the double horizontal suture technique, using SutureLasso™ (Arthrex, Naples, FL) for isolated RTMLM (AIS group), and 20 athletes (mean age, 19.0 years) underwent inside-out repair, one of TCS repairs, with tie-grip suture technique (TCS group). All athletes were assessed for preoperative and two-year postoperative Knee injury and Osteoarthritis Outcome Score (KOOS). At six-month after repair, the lateral meniscal extrusion on mid-coronal plane on MRI and healing status on second-look arthroscopy were also evaluated in all patients. Results: In both groups, KOOS improved to either good or excellent postoperatively, while complete healing was found in only 23 and 25% at second-look arthroscopy. We identified no group-dependent differences in KOOS or healing status on arthroscopy. However, a close examination of failure rates revealed significant lower rates in AIS group relative to that of TCS group (p = 0.048). Moreover, the change from preoperative to postoperative lateral meniscal extrusion in AIS group was significantly smaller than that in TCS group (p = 0.038). Conclusions: AIS and TCS repairs for RTMLM were comparable in providing satisfactory clinical results with low rates of complete healing on arthroscopy. However, AIS repair could have lower failure rate of healing on arthroscopy and minimize postoperative lateral meniscal extrusion more effectively than TCS repair on MRI.

Host genetics highlights IFN-γ-dependent Toxoplasma genes encoding secreted and non-secreted virulence factors in in vivo CRISPR screens.

Secreted virulence factors of Toxoplasma to survive in immune-competent hosts have been extensively explored by classical genetics and in vivo CRISPR screen methods, whereas their requirements in immune-deficient hosts are incompletely understood. Those of non-secreted virulence factors are further enigmatic. Here we develop an in vivo CRISPR screen system to enrich not only secreted but also non-secreted virulence factors in virulent Toxoplasma-infected C57BL/6 mice. Notably, combined usage of immune-deficient Ifngr1-/- mice highlights genes encoding various non-secreted proteins as well as well-known effectors such as ROP5, ROP18, GRA12, and GRA45 as interferon-γ (IFN-γ)-dependent virulence genes. The screen results suggest a role of GRA72 for normal GRA17/GRA23 localization and the IFN-γ-dependent role of UFMylation-related genes. Collectively, our study demonstrates that host genetics can complement in vivo CRISPR screens to highlight genes encoding IFN-γ-dependent secreted and non-secreted virulence factors in Toxoplasma.

Rectangular bone-patellar tendon bone grafts reduce early graft failure in chronic ACL-Deficient knees.

BACKGROUND: The aim of this study was to assess early graft failure after anterior cruciate ligament (ACL) reconstruction according to chronicity of ACL deficiency (ACLD) and clarify predisposing factors. METHODS: A total of 731 patients who underwent anatomic ACL reconstruction were divided into 3 groups based on chronicity of ACLD: <6 months (Group 1), 6 months to 2 years (Group 2), and >2 years (Group 3). Types of ACL grafts used included single-bundle hamstring tendon (HT), multiple-bundle HT, and rectangular bone-patellar tendon-bone (BTB) grafts. Preoperatively and immediately postoperatively, lateral radiographs in full extension were taken to examine anterior tibial subluxation (ATS). All ACL grafts were evaluated by MRI at 6 months to identify graft failure. The group with the highest failure rate was further examined to compare possible risk factors between the intact and failure subgroups, followed by multivariate logistic regression analysis to identify predisposing factors. RESULTS: Early graft failure on MRI without any episode of postoperative trauma was observed in 7 (1.4%), 2 (1.8%), and 11 (9.2%) patients in Groups 1, 2, and 3, respectively, with a significantly higher rate in Group 3 (P < 0.001). Of the 119 patients in Group 3, significant differences were observed between intact and failure subgroups with regard to surgical procedure (P = 0.03), chondral lesions (P < 0.01), and preoperative ATS (P < 0.01). Multivariate logistic regression analysis revealed that surgical procedures (odds ratio, 3.8; 95%CI, 1.16-12.59) and preoperative ATS (odd ratio, 2.4; 95%CI, 1.26-4.38) were predisposing factors of early graft failure. CONCLUSION: Patients with ACLD for >2 years experienced early graft failure with an incidence rate of 9.2%. Predisposing factors of early graft failure in these patients included the use of single-bundle HT grafts and preoperative ATS. The use of rectangular BTB grafts resulted in a lower graft failure rate. STUDY DESIGN: Case Series.

Posterior Ankle Impingement Caused by Hyaline-Like Cartilage Generation in Ballet Dancers-A Report of 2 Cases.

Posterior ankle impingement syndrome is mainly seen in ballet dancers and frequently associated with specific movements in ballet such as pointe and demi pointe in which the whole-body weight is applied to the maximally plantar flexed ankle. We performed arthroscopic debridement for 2 dedicated ballet dancers on the intervening soft tissue causing posterior ankle impingement syndrome (PAIS). In both cases, T2-weighted magnetic resonance imaging (MRI) revealed low-signal intensity of meniscus-like soft tissue without abnormal osseous findings, connecting from the posterior side of the talus to Kager's fat pad. To examine the intervening soft tissue in detail, we performed histological evaluation by hematoxylin and eosin staining, Safranin O fast green staining, and immunohistochemistry for type I collagen and type II collagen. Hematoxylin and eosin staining showed that there was cartilage-like tissue including chondrocyte-like cells in contact with fibrous tissue. The extracellular matrix in the cartilage zone was consistently stained by Safranin O staining and type II collagen without any staining with type I collagen. These findings suggested that the meniscus-like soft tissue appearing as low-signal intensity on MRI at the posterior side of talus included hyaline-like cartilage. To the extent of our knowledge, these were rare cases of hyaline-like cartilage generation causing PAIS in ballet dancers, which might be associated with ballet specific movements resulting in chondrogenesis.

Tibiofemoral Relationship 3 Weeks After Anatomic Triple-Bundle Anterior Cruciate Ligament Reconstruction With 10 N of Initial Tension Is Closer to Normal Knee Versus That With 20 N of Initial Tension.

PURPOSE: This study aimed to clarify the effect of initial graft tension on the ensuing tibiofemoral relationship and on 2-year clinical outcomes after anatomic triple-bundle anterior cruciate ligament (ACL) reconstruction. METHODS: A total of 31 patients with primary unilateral ACL rupture (mean age, 25.1 years) were enrolled. Anatomic triple-bundle ACL reconstruction was performed using semitendinosus tendon autografts, and patients were grouped according to the total initial tension at graft fixation: 20 N for 16 patients between January 2012 and December 2012 and 10 N for 15 patients between January 2013 and December 2013. Three-dimensional computed tomography scans were performed preoperatively and at 3 weeks and 6 months postoperatively. The side-to-side difference of the 3-dimensional tibial position relative to the femur was compared at each time point. The side-to-side difference in anterior laxity was sequentially compared preoperatively, immediately after surgery, and at 6 months and 2 years postoperatively. Clinical outcomes at 2 years were likewise compared. RESULTS: One patient in each group was excluded because of secondary ACL injury. At 3 weeks postoperatively, 2.5 ± 1.3 and 1.0 ± 1.3 mm of posterior tibial displacement and 3.8° ± 2.4° and 2.0° ± 1.7° of external rotation were observed in the 20- and 10-N initial tension groups, respectively, with significant differences (P = .006 and .033). At 6 months postoperatively, anterior displacement was 0.1/0.1 mm and external rotation was 0.8°/0.4° in both groups, without any significant differences. The 2-year clinical outcomes were satisfactory, including mean side-to-side difference in anterior knee laxity of 0.5 mm in both groups. CONCLUSION: The tibiofemoral relationship 3 weeks after anatomic triple-bundle ACL reconstruction with 10 N of initial tension is less constrained than that with 20 N. Six-month tibiofemoral relationship and 2-year clinical outcomes are satisfactory in both groups. LEVEL OF EVIDENCE: III, retrospective comparative trial.

Second-look arthroscopy after double-bundle posterior cruciate ligament reconstruction: Effect of patient age.

PURPOSE: Second-look arthroscopy is invasive but still one of the most useful postoperative evaluation methods since graft morphology including graft tension, graft tear, and synovial coverage can be directly evaluated. However, only a few studies have evaluated transplanted posterior cruciate ligament (PCL) grafts. This study aimed to clarify the PCL graft morphology and chondral damages at second-look arthroscopy after double-bundle PCL reconstruction (PCLR) and to investigate the effects of patient age on these arthroscopic findings. METHODS: This study retrospectively included 26 patients who underwent second-look arthroscopy at the time of hardware removal 14 months after double-bundle PCLR for isolated PCL injury from January 2007 to December 2020. The patients were divided into two groups: group A, 39 years or younger (n = 14); and group B, 40 years or older (n = 12). At second-look arthroscopy, the grafts were evaluated based on tension (taut, graft tension as tense as a normal PCL; lax, graft tension looser than a normal PCL, unclassified, completely torn graft), tear (one or more tendon strands torn), and synovial coverage (good, synovial coverage greater than 80% around the graft; fair, synovial coverage greater than 50%; and poor, synovial coverage less than 50%). The chondral damages were evaluated using the Outerbridge classification system. Radiographic posterior tibial translation with gravity sag view as well as clinical outcomes were also evaluated. RESULTS: Anterolateral (AL) graft tension was lax in 8% of the patients, whereas posteromedial (PM) graft tension was lax or unclassified in 24% (p = 0.043). Graft tear was observed only in the PM graft of 19% patients (p = 0.022). Synovial coverage of AL grafts was good or fair in all cases, whereas that of PM grafts was poor in 28% cases (p < 0.001). Regarding the effect of patient age, the synovial coverage of PM grafts was significantly poorer in group B (p = 0.033), but no statistical difference in graft tension or tear was found. The chondral damages were significantly advanced in group B (p ≤ 0.01), except for the trochlear groove and lateral femoral condyle. No patients had residual subjective posterior instability, knee swelling, or loss of extension exceeding 5° or flexion exceeding 10°. All patients had improved from grade II or III preoperatively to grade I or grade II in the posterior drawer test. The posterior tibial translation significantly improved from 10.0 ± 3.6 mm preoperatively to 3.6 ± 2.1 mm at second-look arthroscopy. No significant differences in the postoperative clinical outcomes were observed between the two groups. CONCLUSION: The morphology of the PM grafts at second-look arthroscopy after double-bundle PCLR was poorer than that of the AL grafts. Patient age negatively affected the postoperative graft synovial coverage and chondral status but did not affect the clinical outcomes.

Isolated peripheral longitudinal tears in the anterior-middle segment of medial meniscus among young soccer players: A case series.

INTRODUCTION: There was little information about the isolated medial meniscal tears in the anterior-middle segment. This study aimed to report the infrequent cases of the isolated medial meniscal tears in the anterior-middle segment related to kicking motion among young soccer players with a short-term postoperative outcome. PRESENTATION OF CASE: In the retrospective review of the surgical records from 2000 to 2018, there were 15 cases with the corresponding tear. They were all young male soccer players with a mean age of 16.7 years (range: 10-23 years). The cause of injury was kicking motion during playing soccer in all the patients. The most frequent symptom was locking in 80% of the cases. In the arthroscopic evaluation, all the cases presented with a longitudinal (bucket-handle) tear in the anterior-middle segment in the peripheral zone with a length of 25 to 30 mm, while the posterior segment and the cruciate ligaments were intact. Meniscal repair was performed for all the cases. At one year, all the patients could return to play soccer with a pre-injury level without any symptoms. In the second-look arthroscopy at six months among four cases, all meniscal tears healed completely. DISCUSSION AND CONCLUSION: Clinicians should be aware of the possibility of isolated peripheral longitudinal tear in the anterior-middle segment of the medial meniscus, which is related to the kicking motion among young soccer players and mainly causes locking.

Sequential Changes in Posterior Tibial Translation After Posterior Cruciate Ligament Reconstruction: Risk Factors for Residual Posterior Sagging.

BACKGROUND: Residual posterior sagging may occur after posterior cruciate ligament (PCL) reconstruction (PCLR), yet when it mainly occurs is not fully understood. PURPOSE: To elucidate sequential changes in radiographic posterior tibial translation (PTT) after PCLR. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: The authors retrospectively investigated the radiographic findings from 22 patients who underwent bisocket double-bundle PCLR for isolated PCL injury with at least 2 years of follow-up (mean, 4.5 years; range, 2-10 years). Injury severity was assessed using PTT on lateral radiographs with gravity sag views and was stratified according to side-to-side difference in the tibial-femoral stepoff: grade 1 (<5 mm), grade 2 (5 to <10 mm), or grade 3 (≥10 mm). Measurements were taken preoperatively and then immediately, 3 months, 6 months, 1 year, and ≥2 years postoperatively. The authors also investigated the risk factors for residual posterior sagging, indicated when PTT was ≥5 mm (grade ≥2) at the minimum 2-year follow-up. RESULTS: Preoperatively, 13 patients had a grade 2 injury, and 9 had grade 3 injury. The PTT, restored immediately after PCLR, significantly increased at 3 months (P < .001) but remained unchanged thereafter ≥2 years. There were 7 cases of postoperative PTT ≥5 mm on radiographs. Patients with residual posterior sagging had significantly larger mean PTT than did those without residual posterior sagging at all time points except for immediately postoperatively (preoperatively, 9.1 ± 1.6 vs 12.2 ± 2.3 mm; 3-month follow-up, 2.7 ± 1.6 vs 7.0 ± 1.8 mm; ≥2-year follow-up, 3.4 ± 1.0 vs 6.5 ± 1.4 mm; P < .001 for all). Multivariate logistic regression analysis showed that preoperative grade 3 injury was independently associated with residual posterior sagging (OR, 26.809; 95% CI, 1.257-571.963; P < .001). CONCLUSION: The initially reduced postoperative PTT significantly increased within 3 months using conventional rehabilitation protocols, but no progression was observed up to 4.5 years after PCLR. Preoperative grade 3 injury was independently associated with residual posterior sagging.

Anatomical Triple Bundle Anterior Cruciate Ligament Reconstructions With Hamstring Tendon Autografts: Tunnel Locations and 2-Year Clinical Outcomes.

PURPOSE: To anatomically clarify the location of the tunnel apertures created using the bony landmark strategy and to elucidate clinical outcomes after anatomic triple-bundle (ATB) anterior cruciate ligament (ACL) reconstruction. METHODS: Thirty-two patients with unilateral ACL injury who had consented to undergo computed tomography (CT) at 3 weeks, as well as 2-year follow-up evaluation, were enrolled. At the time of surgery, remnant tissues were thoroughly cleared to create 2 femoral and 3 tibial tunnels inside the ACL attachment areas bordered by the bony landmarks. Two double-looped semitendinosus tendon autografts were prepared and fixed on the femur with two EndoButton-CLs and secured to the tibia with pullout sutures and plates with 10-20N of tension. The location of the tunnel aperture areas was assessed using 3-dimensional CT images, and 2-year postoperative clinical outcomes were evaluated. RESULTS: The CT evaluation showed 100% of the femoral tunnel aperture area and at least 79% of the tibial tunnel aperture area were located inside the anatomic attachment areas. Thirty patients were available for clinical evaluation. The International Knee Documentation Committee subjective assessment showed all of the patients were classified as "normal" or "nearly normal." Lachman and pivot-shift tests were negative in 100% and 93%, respectively. The mean side-to-side difference of anterior laxity at the maximum manual force with a KT-1000 Knee Arthrometer was 0.7 ± 0.7 mm, ranging from 0 to 2 mm. CONCLUSION: In ATB ACL reconstructions with hamstring tendon grafts, the tunnels can be created in proper locations using the arthroscopically-identifiable bony landmarks. Moreover, ATB ACL reconstruction with hamstring tendon grafts via the proper tunnels result in consistently satisfactory clinical outcomes. LEVEL OF EVIDENCE: Level IV, case series.

Tunnel Enlargement Correlates With Postoperative Posterior Laxity After Double-Bundle Posterior Cruciate Ligament Reconstruction.

BACKGROUND: There exists little information in the relevant literature regarding tunnel enlargement after posterior cruciate ligament (PCL) reconstruction (PCLR). PURPOSE: To sequentially evaluate tunnel enlargement and radiographic posterior laxity through double-bundle PCLR using autologous hamstring tendon grafts. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: We prospectively analyzed 13 patients who underwent double-bundle PCLR for an isolated PCL injury. Three-dimensional computed tomography images were obtained at 3 weeks, 6 months, and 1 year postoperatively, and the tunnel enlargement was calculated by sequentially comparing the cross-sectional areas of the bone tunnels. We also sequentially measured radiographic posterior laxity. The correlation between the tunnel enlargement ratio and the postoperative increase in posterior laxity was evaluated. RESULTS: The cross-sectional area at the aperture in each tunnel significantly increased from 3 weeks to 6 months (P < .003), but it did not continue doing so thereafter. The 6-month tunnel enlargement ratios of the femoral anterolateral tunnel, the femoral posteromedial tunnel, the tibial anterolateral tunnel, and the tibial posteromedial tunnel were 31.6% ± 23.5%, 90.3% ± 54.7%, 30.5% ± 26.8%, and 49.6% ± 37.0%, respectively, while the corresponding ratios at 1 year were 28.1% ± 19.8%, 83.1% ± 56.9%, 26.8% ± 32.8%, and 47.6% ± 39.0%, respectively. The posterior laxity was 9.0 ± 4.0 mm, -1.5 ± 2.3 mm, 3.4 ± 2.0 mm, and 3.9 ± 1.9 mm, preoperatively, immediately after surgery, 6 months and 1 year postoperatively, respectively. From the immediate postoperative period, the posterior laxity significantly increased at 6 months postoperatively (P < .001), but it did not thereafter. The postoperative increase in posterior laxity had a significant positive correlation with the anterolateral tunnel enlargement ratio in both femoral and tibial tunnels at 6 months (ρ = 0.571-0.699; P = .011-.041) and 1 year (ρ = 0.582-0.615; P = .033-.037). CONCLUSION: Tunnel enlargement after PCLR mainly occurred within 6 months, with no progression thereafter. The anterolateral tunnel enlargement positively correlated with postoperative increase in posterior laxity.

Chronological changes in cross-sectional area of the bone-patellar tendon-bone autograft after anatomic rectangular tunnel ACL reconstruction.

PURPOSE: The purpose of this study was to evaluate the change in cross-sectional area (CSA) of bone-patellar tendon-bone (BTB) autografts up to 5 years after the anatomic rectangular tunnel (ART) anterior cruciate ligament reconstruction (ACLR). The changing pattern in CSA might be a potential indicator of the graft remodeling process. METHODS: Ninety-six (62 males, 34 females, mean age 27.0 years) patients were enrolled in this study with a total of 220 MRI scans after ART BTB ACLR to evaluate the CSA of the ACL autografts. The patients with first time unilateral ACLR that consented to undergo MRI evaluations at postoperative periods were included in this study. Intraoperatively, the CSA of the graft was measured directly using a custom-made area micrometer at the midpoint of the graft. Postoperatively, using an oblique axial slice MRI that was perpendicular to the long axis of the graft, the CSA of the graft was measured with digital radiology viewing program "SYNAPSE" at the midpoint of the graft. The postoperative MRI scans were classified into seven groups according to the period from ACLR to MRI evaluation: Group 0-2 months (m.), Group 3-6 m., Group 7-12 m., Group 1-2 years (y.), Group 2-3 y., Group 3-4 y., and Group 4 y.-. The percent increase of the CSA was calculated by dividing the postoperative CSA by the intraoperative CSA. RESULTS: The postoperative CSA was significantly larger than the intraoperative CSA in each group, with the exception of Group 0-2 m. The mean percent increase of the CSA in Group 0-2 m., 3-6 m., 7-12 m., 1-2 y., 2-3 y., 3-4 y., 4 y.- was 101.8 ± 18.2, 188.9 ± 27.4, 190.9 ± 43.7, 183.3 ± 28.9, 175.2 ± 27.9, 163.9 ± 19.8, 164.5 ± 25.4% respectively. The percent increase in Group 3-6 m., 7-12 m., 1-2 y., 2-3 y., 3-4 y., and 4 y.- was significantly greater than that in Group 0-2 m. CONCLUSIONS: The CSA of the BTB autografts after the ART BTB ACLR increases rapidly by 3-6 months after ACLR, reached a maximum value of 190% at around 1 year, decreases gradually after that, and reaches a plateau at around 3 years. The current study might help clinicians to estimate an individual BTB autograft's remodeling stages when considering returning patients to sports. LEVEL OF EVIDENCE: IV.

Different effects of the lateral meniscus complete radial tear on the load distribution and transmission functions depending on the tear site.

PURPOSE: To compare the effect of the lateral meniscus (LM) complete radial tear at different tear sites on the load distribution and transmission functions. METHODS: A compressive load of 300 N was applied to the intact porcine knees (n = 30) at 15°, 30°, 60°, 90°, and 120° of flexion. The LM complete radial tears were created at the middle portion (group M), the posterior portion (group P), or the posterior root (group R) (n = 10, each group), and the same loading procedure was followed. Finally, the recorded three-dimensional paths were reproduced on the LM-removed knees. The peak contact pressure (contact area) in the lateral compartment and the calculated in situ force of the LM under the principle of superposition were compared among the four groups (intact, group M, group P, and group R). RESULTS: At all the flexion angles, the peak contact pressure (contact area) was significantly higher (lower) after creating the LM complete radial tear as compared to that in the intact state (p < 0.01). At 120° of flexion, group R represented the highest peak contact pressure (lowest contact area), followed by group P and group M (p < 0.05). The results of the in situ force carried by the LM were similar to those of the tibiofemoral contact mechanics. CONCLUSION: The detrimental effect of the LM complete radial tear on the load distribution and transmission functions was greatest in the posterior root tear, followed by the posterior portion tear and the middle portion tear in the deep-flexed position. Complete radial tars of the meniscus, especially at the posterior root, should be repaired to restore the biomechanical function.

Anterior tibial loading on the calf enhances anterior tibial translation in the anterior cruciate ligament deficient knee in the anterior gravity radiographic view.

BACKGROUND: Lateral radiograph in the prone position with the knee flexed at 15° (anterior gravity view (AGV)) is useful as a screening for anterior cruciate ligament (ACL) injuries, while it is sometimes difficult to find the side-to-side difference (SSD) in anterior tibial translation. Thus, we applied a weight (three kilograms) around the lower leg to increase anterior tibial translation. We aimed to determine whether weight load confers an advantage in visualizing anterior knee laxity in ACL injuries. METHODS: Fifty-eight patients with confirmed unilateral ACL tears from February 2012 to April 2014 had consented to participate in this study. Lateral radiographs for both knees were taken in AGV and in AGV with a three-kilogram weight load applied to the proximal lower leg. Then, the SSD of tibial position related to the femur was measured in these radiographs. RESULTS: The SSD with the weight was significantly greater than that without the weight (5.9 ± 2.1 and 3.5 ± 1.6 mm, respectively, p < 0.01). The ratio of patients with SSD of three millimeters or more in AGV with the weight was also significantly larger than that without the weight (p < 0.01). CONCLUSIONS: The anterior laxity in AGV with the three-kilogram weight is larger than that without the weight. Thus, the AGV with the weight could be one of the helpful radiographic technique for auxiliary diagnosis of ACL injury. Level of evidence Cohort study, Level IV.

Preoperative quadriceps strength as a predictor of return to sports after anterior cruciate ligament reconstruction in competitive athletes.

OBJECTIVES: To determine whether preoperative quadriceps strength predicts the likelihood of return to sports (RTS) following anterior cruciate ligament reconstruction (ACLR) in competitive athletes. DESIGN: Case-control study. SETTING: Single-center. PARTICIPANTS: A total of 221 competitive athletes who underwent primary ACLR were followed and divided into RTS (n = 177) and non-RTS (n = 44) groups based on self-reported sports activities at one year postoperatively. MAIN OUTCOME MEASURES: Isokinetic quadriceps strength tests were performed preoperatively and at six months and one year postoperatively, and the quadriceps index (QI) was calculated. Functional performance was evaluated by the single-leg hop (SLH) test at six months postoperatively. RESULTS: Preoperative QI significantly predicted the likelihood of RTS (odds ratio, 1.68 per 10-unit increase; P < 0.001), with a preoperative QI cut-off of 66% (AUC: 0.74; sensitivity: 68.9%; specificity: 77.3%). Subjects with a preoperative QI < 66% had a significantly lower postoperative QI, SLH, and rates of RTS compared to those with a higher preoperative QI (P < 0.01). CONCLUSIONS: Preoperative quadriceps strength could predict the likelihood of RTS following ACLR, and a preoperative QI < 66% was associated with a greater risk of unsuccessful RTS at one year postoperatively. Preoperative QI should be evaluated as a predictor of RTS.

Reduction of in situ force through the meniscus with phased inner resection of medial meniscus: an experimental study in a porcine model.

PURPOSE: Partial meniscectomy can cause osteoarthritic changes in knees, as inner portion as well as peripheral portion of meniscus is important. The hypothesis of this study was that the amount of the inner resection of medial meniscus affected the in situ forces through the meniscus and the tibial varus and external rotation under axial load. METHODS: Fourteen intact porcine knees were investigated with a six-degree of freedom robotic system and force/moment, and the three-dimensional path of intact knees were recorded by universal force sensor when an axial load of 300-N was applied at four different flexion angles (30°, 60°, 90°, and 120°). The same examination was performed on three phased inner resections (30%, 60%, and 90% width) of the medial meniscus. Finally, all paths were reproduced after total medial meniscectomy, and in situ forces of the medial meniscus were calculated based on the superposition principle. Changes in tibiofemoral varus/valgus and internal/external rotation alignment during an axial load were also calculated. RESULTS: In situ forces of the medial meniscus decreased according to the amount of meniscal resection at all flexion angles. The reduction was significant in knees with inner resections of > 60% width at all flexion angles and even of 30% width at a flexion angle of 120° (p < .05). Incremental changes in the tibiofemoral varus alignment increased depending on the inner resection width at all flexion angles (p < .05). CONCLUSION: The amount of inner resection of the medial meniscus was related to reduction of its in situ forces and increment of the tibial varus rotation under axial load.

On-lay grafting of a calcium hydroxyapatite bone substitute: A preliminary animal experimental study.

BACKGROUND: Bone substitutes are widely accepted for various clinical applications. However, the usage is predominantly intraosseous implantation, whereas extraosseous on-lay grafting is rare and lacks scientific evidence. The purpose of this study is to elucidate whether osteoconduction occurs in on-lay grafted bone substitute. METHODS: Custom-made interconnected porous calcium hydroxyapatite ceramic (IPCHA) was on-lay grafted with screw or anchor fixation (S- and A-groups, respectively) at the anterior aspect of the femur of skeletally mature Japanese white rabbits. At 3, 6 and 12 weeks postoperatively, 4 samples for each time point and each group were evaluated by microfocus computed tomography (micro-CT) and histology. RESULTS: Volume-rendered three-dimensional micro-CT images showed a high-density calcified area infiltrating IPCHA from the femoral cortex as of 6 weeks. When quantified, the calcified volume per unit volume first showed no difference between the two groups at 3 weeks but increased over time, and became significantly greater in the S-group than in the A-group (p = 0.012 and 0.004 at 6 and 12 weeks, respectively). Histologically, IPCHA pores were first occupied by fibrous tissue at 3 weeks; then, the pores adjacent to the femoral cortex were gradually replaced by bony tissue as of 6 weeks for both fixations. CONCLUSIONS: IPCHA allowed new bone formation inside the material even though it was implanted in an on-lay fashion on the cortical bone. Our results suggested that on-lay grafted IPCHA exerted its osteoconductivity well, with more new bone forming in screw-fixated samples than in anchor-fixated samples.

Residual graft tension after graft fixation in anterior cruciate ligament reconstruction: Manual vs tensioning boot techniques.

BACKGROUND: Graft fixation at quantitative tension using a manual tensioner was advocated in ACL reconstruction, while the measured tension that is based on the surgeon's hand with the tensioner decreases after graft fixation. Therefore, our purpose is to elucidate how effectively the pre-determined graft tension maintained after final fixation of the graft to the tibia using a tensioning boot system fixed to the calf with a bandage, while monitoring the graft tension based on tibia. METHODS: Eight cadaveric legs (mean age: 83; 3 males and 5 females) underwent an anatomic double-bundle anterior cruciate ligament (ACL) reconstruction with hamstring tendon grafts. Two tension-adjustable force gauges were installed on the lateral femoral cortex beside the femoral tunnel. Then #5 strong suture wires through the loop end of grafts were tied to the force gauges using Endo-Buttons. After manual maximum load was repeatedly applied to each graft for 3 min, the grafts were fixed to the tibia with 10 N or 20 N at 20 degree of flexion with the following tensioning techniques using double spike plate system: (1) Manually tensioning technique (MT); (2) Tensioning boot technique with flexion-extension motion (TB-FE); and (3) Tensioning boot technique with repetitive pull (TB-RP). The residual tension at 20 was measured 3 min after grafts fixation, and also after 10 and 50 times of repeated flexion-extension motion. One-way repeated measures ANOVA was used for statistical analysis among the three techniques. RESULTS: There were significant differences among three techniques fixing grafts with 10/20 N of initial tension in the residual tension 3 min after graft fixation and after 10 and 50 times of repeated flexion-extension motion. Among them, the residual tension in TB-RP was the greatest in most conditions. CONCLUSION: TB-RP is the most secure procedure to maintain the graft tension closer to the intended initial tension in ACL reconstruction.

Importance of functional performance and psychological readiness for return to preinjury level of sports 1 year after ACL reconstruction in competitive athletes.

PURPOSE: This study aimed to identify independent predictive factors for return to sports (RTS) after anterior cruciate ligament (ACL) reconstruction in competitive-level athletes and to determine optimal cut-off values for these factors at 6 months after surgery. METHODS: A total of 124 competitive athletes (50 males and 74 females; mean age, 17.0 years; preinjury Tegner activity scale > 7) who underwent primary ACL reconstruction were enrolled. Assessments at 6 months after surgery consisted of knee functional tests [quadriceps index, hamstrings index, and single-leg hop for distance (SLH)] and 2 self-report questionnaires [IKDC subjective score and ACL-Return to Sport after Injury scale (ACL-RSI)]. At 1 year after surgery, athletes were classified into the RTS group (n = 101) or non-RTS group (n = 23) based on self-reported sports activities. After screening possible predictive factors of RTS, multivariate logistic regression and receiver operating characteristic curve analyses were performed to identify independent factors. RESULTS: Multivariate logistic regression analysis identified SLH (odds ratio, 2.861 per 10 unit increase; P < 0.001) and ACL-RSI (odds ratio, 1.810 per 10 unit increase; P = 0.001) at 6 months as independent predictors of RTS at 1 year after surgery. Optimal cut-off values of SLH and ACL-RSI were 81.3% (sensitivity = 0.891; specificity = 0.609) and 55 points (sensitivity = 0.693; specificity = 0.826), respectively. CONCLUSION: In competitive athletes, SLH < 81% and ACL-RSI < 55 points at 6 months after surgery were associated with a greater risk of unsuccessful RTS at 1 year after surgery. SLH and ACL-RSI at 6 months could serve as screening tools to identify athletes who have difficulties with returning to sports after ACL reconstruction. LEVEL OF EVIDENCE: III.