Ultrasonographic diagnosis of medial meniscus posterior root tear in early knee osteoarthritis: a comparative study.

INTRODUCTION: This study aimed to detect medial meniscal posterior root tear (MMPRT) diagnostic methods with high sensitivity and specificity using dynamic ultrasonographic evaluation in patients with early knee osteoarthritis (OA) and demonstrate the usefulness of dynamic ultrasonographic medial meniscal extrusion (MME) evaluation in MMPRT diagnosis using a cutoff value. MATERIALS AND METHODS: Between 2018 and 2020, a total of 120 patients were diagnosed with early knee OA using clinical and radiographic findings. Dynamic ultrasonographic evaluations and magnetic resonance imaging were performed in all patients, and 47 patients who had and 73 patients who did not have MMPRT were classified into the MMPRT and non-MMPRT groups, respectively. Age, sex, femorotibial angle, MME of knee extension and flexion, and MME at weight-bearing were compared between the two groups. Additionally, the sensitivity and specificity of significant ultrasonographic findings were calculated using a receiver operating characteristic (ROC) curve. RESULTS: The MMEs under knee extension-flexion and weight-loading in the MMPRT group were significantly larger than those in the non-MMPRT group. ROC curve analysis for each ultrasonographic evaluation condition to diagnose MMPRT indicated that the sensitivity was 72-88% and the specificity was 66-85% when the cutoff values of MME under knee flexion at 0°, 90°, and weight-loading were set at 2.55 mm, 2.00 mm, and 3.55 mm, respectively. The highest sensitivity (88%) and specificity (85%) were exhibited upon > 2 mm MME at a knee flexion of 90° and were the most useful indicators for MME diagnosis. CONCLUSIONS: Ultrasonographic MME evaluations for MMPRT diagnosis showed relatively high sensitivity and specificity in patients with early knee OA. Dynamic ultrasonographic MME evaluation may lead to appropriate additional examinations, early diagnosis, and intervention for MMPRT in patients with early knee OA.

Extrusion of the medial meniscus under a weight-loading condition in early knee osteoarthritis: an investigation using special upright magnetic resonance imaging.

BACKGROUND: Whether the medial meniscus morphology and movement occur under upright loading conditions in early knee osteoarthritis (OA) or medial meniscus posterior root tear (MMPRT) remains unknown. This study aimed to evaluate the medial and anteroposterior extrusion of the medial meniscus under unloaded and upright-loaded conditions in patients with early knee OA. METHODS: Twelve patients with early knee OA and 18 healthy adult volunteers participated in this study. Magnetic resonance imaging using special equipment was performed with the participants in the unloaded and upright-loaded conditions. Medial, anterior, and posterior extrusions of the medial meniscus against the tibial edge were evaluated and compared between the early knee OA and healthy adult control groups. Additionally, 12 patients in the early knee OA group were divided into 2 subgroups based on whether MMPRT was observed, and the extrusion of the medial meniscus was compared. RESULTS: The amount of medial extrusion of the medial meniscus in both the unloaded and upright-loaded conditions was significantly greater in the early knee OA group than in the control group (unloaded: 2.6 ± 1.0 mm vs 0.7 ± 0.5 mm; upright-loaded: 3.7 ± 0.9 mm vs 1.8 ± 0.8 mm). Similarly, the anterior and posterior extrusion of the medial meniscus in the upright-loaded condition was significantly larger in the early knee OA group (anterior: 4.6 ± 1.0 mm vs 3.7 ± 1.1 mm; posterior: -3.4 ± 1.1 mm vs -4.6 ± 1.6 mm). However, no difference was observed in meniscal extrusion between unloaded and upright-loaded conditions. The posterior extrusion of the medial meniscus in the upright-loaded condition was significantly greater in MMPRT cases than in non-MMPRT cases in the early knee OA group (MMPRT: -2.7 ± 1.1 mm; non-MMPRT -4.1 ± 1.5 mm). CONCLUSIONS: In early knee OA, significantly large meniscal extrusions of the medial meniscus in both unloaded and upright-loaded conditions were found compared with healthy adults. Among patients with early knee OA, those with MMPRT showed a large posterior extrusion of the medial meniscus in the upright-loaded condition compared with those without MMPRT. LEVEL OF EVIDENCE: Level IV.

Regeneration Using Adipose-Derived Stem Cell Sheets in a Rabbit Meniscal Defect Model Improves Tensile Strength and Load Distribution Function of the Meniscus at 12 Weeks.

PURPOSE: The purpose of this study was to evaluate the mechanical properties, such as the tensile strength and load distribution function, of the meniscus tissue regenerated using adipose-derived stem cell (ADSC) sheets in a rabbit meniscal defect model. METHODS: ADSC sheets were prepared from adipose tissue of rabbits. The anterior half of the medial meniscus was removed from both knees. One knee was transplanted with an ADSC sheet; the contralateral knee was closed without transplantation. Mechanical tests were performed at 4 and 12 weeks posttransplantation. In the tensile test, tensile force was applied to the entire medial meniscus, including the normal area (n = 10/group). Compression tests were performed on the entire knee, with soft tissues other than the ligament removed. A pressure-sensitive film was inserted under the medial meniscus and a 40-N load was applied (n = 5/group). RESULTS: In the tensile test, the elastic modulus in ADSC-treated knees was higher at 12 weeks (ADSC: 70.30 ± 18.50 MPa, control: 43.71 ± 7.11 MPa, P = .009). The ultimate tensile strength (UTS) in ADSC-treated knees at 12 weeks was also higher (ADSC: 22.69 ± 5.87 N, control: 15.45 ± 4.08 N, P = .038). In the compression test, the contact area was larger in the ADSC group at 4 weeks (ADSC: 31.60 ± 8.17 mm2, control: 20.33 ± 2.86 mm2, P = .024) and 12 weeks (ADSC: 41.07 ± 6.09 mm2, control: 30.53 ± 5.47 mm2, P = .04). Peak pressure was significantly lower in ADSC-treated knees at 12 weeks (ADSC: 11.91 ± 1.03 MPa, control: 15.53 ± 2.3 MPa, P = .002). CONCLUSIONS: The regenerated meniscus tissue, 12 weeks after transplantation of the ADSC sheets into the meniscal defect area, had high elastic modulus and UTS. In the meniscus-tibia compartment, the contact area was large and the peak pressure was low. CLINICAL RELEVANCE: ADSC sheets promoted regeneration of meniscus. ADSC sheet transplantation for meniscal defects could be an effective regenerative therapy.

Clinical study of anatomical ACL reconstruction using a rounded rectangular dilator.

BACKGROUND: The aim of this study was that to compare clinical results between the rounded rectangular femoral tunnel ACL reconstruction (RFTR) and the conventional round femoral tunnel ACL reconstruction using a hamstring tendon. The hypothesis was that ACL reconstruction performed using the rounded rectangular dilator technique was better than that performed using the conventional round femoral tunnel technique in terms of clinical results and bone tunnel enlargement. METHODS: We conducted retrospective study. After exclusions, 40 patients were included in the conventional anatomical single-bundle ACL reconstruction (ASBR) group and 40 patients were included in the RFTR group. The evaluation items were knee stability, Lysholm knee score, IKDC subjective score at 2 years after surgery and bone tunnel enlargement. RESULTS: The RFTR group had a larger femoral tunnel area (average area, 53.1 ± 4.0 mm2 vs. 46.1 ± 7.0 mm2; P < 0.01), better anteroposterior stability, and higher Lysholm scores than the ASBR group (average side-to-side difference for anterior tibial translation, 0.6 ± 0.8 mm vs. 1.6 ± 1.4 mm; P < 0.01; average Lysholm score, 98.5 ± 2.1 vs. 97.5 ± 3.5; P < 0.01). Further, bone tunnel enlargement ratio was significantly lower in the RFTR group (73 ± 38% vs. 107 ± 41%; P < 0.01). CONCLUSIONS: We designed and developed an original rounded rectangular dilator to perform a novel ACL surgery. This technique can create a larger bone tunnel and improve clinical results than the conventional round anatomical single-bundle ACL reconstruction.

Usefulness of lateral femoral cutaneous nerve block in combination with femoral nerve block for anterior cruciate ligament reconstruction: a prospective trial.

INTRODUCTION: The study aimed to compare the combination of femoral nerve block (FNB) with interspace between the popliteal artery and the capsule of posterior knee (IPACK) block (IPACK group) with the combination of FNB with lateral femoral cutaneous nerve (LFCN) block (LFCN group) for postoperative pain control in patients undergoing anterior cruciate ligament (ACL) reconstruction. We hypothesized that the lower pain scores and decreased suppository use would be noted in patients administered a combination of FNB and IPACK block. MATERIALS AND METHODS: A non-randomized prospective controlled clinical trial was conducted. The IPACK and LFCN groups included 40 patients each. The patients received IPACK block and LFCN block alternately. Thirty minutes prior to the surgery and after administration of general anesthesia, patients received an ultrasound-guided FNB and IPACK block or LFCN block. After ACL reconstruction, the visual analog scale pain scores were recorded at 30 min, 4 h, 8 h, 12 h, 24 h, 48 h, and 72 h after the surgery. The administration and use of analgesic suppositories were assessed. These measures were compared among the treatment types at each time-point using the Welch's t-test. RESULTS: Suppository use was significantly less in the LFCN group than in the IPACK group. The pain scores were significantly lower in the LFCN group at 30 min, 4 h, 48 h, and 72 h after the surgery. CONCLUSION: The combination of FNB with LFCN block during ACL reconstruction significantly reduces pain in the early postoperative period compared to a combination of FNB with IPACK block. LEVEL OF EVIDENCE: Prospective control trial, Level II.

Autologous Adipose-Derived Stem Cell Sheet Has Meniscus Regeneration-Promoting Effects in a Rabbit Model.

PURPOSE: This study investigated meniscal regeneration-promoting effects of adipose-derived stem cell (ADSC) sheets in a rabbit meniscal defect models. METHODS: ADSCs were extracted from the interscapular fat pad adipose tissue of 42 mature female Japanese white rabbits. Once cells reached confluence at the third passage, the culture medium was supplemented with ascorbic acid. Within a week, the cells in culture formed removable sheets, which were used as ADSC sheets. Cell death (CD) sheets were created by killing ADSCs by freezing to investigate the need for viable ADSCs in ADSC sheets. The anterior half of the medial meniscus from the anterior root to the posterior edge of the medial collateral ligament was removed from both limbs. An autologous ADSC or CD sheet was transplanted to one knee (ADSC sheet or CD sheet group). The contralateral limb was closed without transplantation following meniscal removal (control group). Rabbits were euthanized 4 and 12 weeks after transplantation to harvest the entire medial menisci. The meniscal tissue area, transverse diameter on the inside of the medial collateral ligament, and histologic score were compared between the 3 groups. RESULTS: The area and transverse diameter of regenerated tissues were larger in the ADSC sheet group than in the control group at 4 and 12 weeks. Further, the histologic score in the ADSC sheet group (8) was significantly greater than that in the control group (4.5) at 4 weeks (P = .02) and greater than that in the CD sheet group (9) (ADSC = 12.5, P = .009) and control group (6) (ADSC = 12.5, P = .0003) at 12 weeks. CONCLUSIONS: Transplantation of the ADSC sheet into the meniscal defect increased the volume and improved the histologic score of the regenerated meniscal tissue. ADSC sheets may have meniscal regeneration-promoting effects in a rabbit model with meniscal defects. CLINICAL RELEVANCE: ADSC sheets do not require a scaffold for implantation in the rabbit model, and this evidence suggests that some tissue regeneration occurs at the site of a surgically created meniscal defect.

Partial lateral meniscus anterior root injuries during anatomical single-bundle anterior cruciate ligament reconstruction are likely to occur in women with small skeletons.

PURPOSE: This study aimed to investigate the occurrence and characteristics of lateral meniscus anterior root injuries during anatomical single-bundle anterior cruciate ligament (ACL) reconstruction. METHODS: Between 2011 and 2018, 70 women who had ACL injuries without lateral meniscal tears underwent anatomical single-bundle ACL reconstruction. Using computed tomography, the anatomical relationship between the predicted lateral meniscus anterior root insertion and the tibial tunnel was retrospectively assessed, and the patients were divided into partial lateral meniscus anterior root injury and intact groups. The demographic characteristics, the distances between bony landmarks, the tibial tunnel sizes, and lateral meniscal extrusion assessed by magnetic resonance imaging were compared between the two groups. RESULTS: Thirteen of the 70 patients had suspected partial lateral meniscus anterior root injuries. Patient height was significantly shorter in the injury group than in the intact group (157.7 ± 6.4 vs. 161.4 ± 5.4 cm: p = 0.03); the distance from the apex to the bottom of the slope of the medial intercondylar ridge was significantly shorter in the injury group than in the intact group (15.1 ± 1.9 vs. 16.7 ± 1.4 mm: p = 0.001). CONCLUSIONS: Partial lateral meniscus anterior root injury during anatomical single-bundle ACL reconstruction was suspected in 18% of cases. Patient height and the distance between bony landmarks were significantly shorter in the injury group than in the intact group. Surgeons should understand that even a slight deviation of the tibial tunnel position can lead to partial lateral meniscus anterior root injury in patients with small skeletons. LEVEL OF EVIDENCE: IV.

Lateral meniscus posterior root tear in anterior cruciate ligament injury can be detected using MRI-specific signs in combination but not individually.

PURPOSE: The purpose of this study was to evaluate (1) the diagnostic value of using single and multiple magnetic resonance imaging (MRI) findings for lateral meniscus posterior root tear (LMPRT) detection in anterior cruciate ligament (ACL) injury and (2) the influence of time from ACL injury to MRI assessment on LMPRT detection. Finally, we investigated the relationship between LMPRT and bone bruising. METHODS: In all, 231 knees with ACL injury, 32 with LMPRT, were retrospectively assessed. Cases were evaluated for LMPRT based on the cleft, ghost, and truncated triangle signs, used individually or in combination. To assess the influence of the timing of the MRI assessment on LMPRT detection, we also evaluated the overall sensitivity, specificity, and accuracy in cases in which MRI was performed within 2 weeks of injury. The number of condyles with bone bruising was assessed and then compared between patients with and without LMPRT. RESULTS: Although the sensitivity and specificity of the three signs individually were 34.4-65.6% and 94.0-97.0%, when at least one of these signs was positive, the sensitivity and specificity were 84.4% and 90.5%, respectively. However, the diagnostic value of each sign when MRI was performed within 2 weeks of injury was lower than the overall value. There was a significant difference in the number of condyles with bone bruising between the LMPRT (3 ± 1) and non-LMPRT (2 ± 2) groups. CONCLUSIONS: Although the sensitivity of each sign for LMPRT was low, LMPRT could be detected adequately if these signs were used in combination. Therefore, surgeons should detect LMPRT using these three signs in combination, not individually. LEVEL OF EVIDENCE: IV.

Incidence of injury in young handball players during national competition: A 6-year survey.

BACKGROUND: An updated injury surveillance of young handball players is needed because of the increased risk of injury in recent handball games with increased intensity. This study examined acute injuries in young handball players during games. METHODS: We retrospectively assessed the injuries occurring during 6 national competitions, including 550 games from 2013 to 2018, held in March of each year. All players were 13 or 14 years old. RESULTS: In total, 169 injuries were reported. The number of match injuries per 1000 player hours was 26.5. The injury incidence in boys was higher than that in girls (p = 0.001). No significant differences were found in injury incidence according to the position and date during the tournament (p = 0.108 and 0.483, respectively). Of all injuries, 43.2% were in the lower extremities and 20.7% affected the upper extremities. Most injuries occurred in the head/face (n = 53, 31.4%), followed by the ankle/foot (n = 41, 24.3%), knee (n = 23, 13.6%), and wrist/hand (n = 22, 13%). The most common injury type was sprain (n = 64, 37.9%), followed by contusion (n = 50, 30.0%) and wound (n = 35, 20.7%). In field players, ankle sprain was the most frequent diagnosis, followed by head/face wound and contusion. In contrast, contusion was the main cause of injury in goalkeepers, followed by wound on the head/face. CONCLUSIONS: Preventive measures focussing on sprains in the lower extremity and improved skill in ball-handling technique should be considered to prevent head/face and wrist/hand injuries, especially in boys. STUDY DESIGN: Retrospective cohort study.

Investigation of extrusion of the medial meniscus under full weight-loading conditions using upright weight-loading magnetic resonance imaging and ultrasonography.

BACKGROUND: Meniscal morphology under full weight-loading conditions is currently unknown. This study aimed to evaluate extrusion in the medial meniscus between unloaded and upright-loaded conditions in healthy adults using upright magnetic resonance imaging (MRI) and ultrasonography and to investigate the relationship between MRI and ultrasonography in upright-loaded conditions. METHODS: Eighteen healthy adult volunteers (13 men and 5 women) participated in the study. MRI and ultrasonography were performed with patients in the supine, double-leg upright (DLU), and single-leg upright (SLU) positions. Medial, anterior, and posterior extrusions of the medial meniscus against the tibial edge were evaluated and compared across the three positions. Medial extrusion correlations between MRI and ultrasonography were examined. Demographic data and hip-knee-ankle (HKA) angles were measured and correlated with changes in the medial extrusion. The medial meniscal extrusions detected via MRI and ultrasonography were compared across the three positions. Correlations were examined using Pearson's correlation coefficients. RESULTS: Negative correlations were found between the change in medial extrusion of the medial meniscus and HKA angle (MRI: r = -0.52, ultrasonography: r = -0.51). Although no significant differences among the three conditions were observed for the anterior and posterior extrusions of the medial meniscus, the medial extrusion of the medial meniscus was significantly greater in DLU and SLU positions than that in the supine position for MRI and ultrasonography (P < 0.05). Positive correlations for the medial extrusion of the medial meniscus were found between MRI and ultrasonography in all three positions (supine: r = 0.74, DLU; r = 0.71, SLU; r = 0.61). CONCLUSIONS: Although no significant differences in anterior and posterior extrusions of the medial meniscus were seen across the studied positions, the medial meniscus was found to undergo significant medial extrusion during upright weight-loading conditions. The strong correlation between MRI and ultrasonography highlighted the usefulness of ultrasonography. LEVEL OF EVIDENCE: Level IV.

Partial resection of the infrapatellar fat pad during anterior cruciate ligament reconstruction has no effect on clinical outcomes including anterior knee pain.

BACKGROUND: Anterior knee pain (AKP) is a major complication that occurs after anterior cruciate ligament reconstruction (ACLR), even when hamstring tendon (HT) grafts are used. Damage to the infrapatellar fat pad (IPFP) during arthroscopy can cause AKP. The purpose of this study was to evaluate the influence of IPFP preservation on clinical outcomes, including AKP, in patients who underwent ACLR with HT autografts using the inside-out technique. METHODS: Forty-two patients who underwent primary ACLR with HT autografts were prospectively assessed for 2 years after surgery. They were randomly selected to undergo treatment with as much intercondylar IPFP preservation as possible or with intercondylar IPFP resection to confirm the ACL origin on the femoral and tibial sides, especially the femoral footprint in deep flexion of the knee joint. The total IPFP volume was calculated using sagittal MR images before and 6 months after surgery. The patients completed a subjective knee score questionnaire and were assessed for patellar tendon tenderness and pain with the half-squat test or single-leg hop test at 6 months and 2 years postoperatively. RESULTS: There were no differences in the patient characteristics, including age, sex, BMI, time from injury to surgery, and meniscus tear. The difference in the total size of the IPFP preserved was significant (P = 0.004). However, there were no significant differences in the subjective knee scores. Moreover, there were no differences in the clinical assessment parameters between the IPFP preservation and resection groups. CONCLUSIONS: The size of the IPFP decreased more in the resection group than in the preservation group at 6 months after surgery. However, partial IPFP resection, which was used to better visualize the origin of the ACL, had no effect on the clinical outcomes, including AKP. LEVEL OF EVIDENCE: Level II.

No superiority of dextrose injections over placebo injections for Osgood-Schlatter disease: a prospective randomized double-blind study.

PURPOSE: Osgood-Schlatter disease (OSD) is a traction apophysitis of the tibial tuberosity. Patellar tendinopathy and deep infrapatellar bursitis have recently been shown to contribute to pain in patients with OSD. We compared the effects of dextrose injection and saline injection. METHODS: We performed a clinical trial from April 2012 to January 2016 and included 49 knees from 37 boys and 1 girl (mean age, 12.3 ± 1.1 years) for whom conventional conservative therapy for > 1 month was ineffective. They were randomly assigned to receive double-blind injections of 1% lidocaine (1 mL) with 20% dextrose (1 mL; dextrose group) or 1% lidocaine (1 mL) with saline (1 mL; saline group). Injections were administered monthly for 3 months by a single investigator. The Victorian Institute of Sport Assessment (VISA) score was used to evaluate anterior knee pain. RESULTS: Overall, 43 knees were included; 6 knees were lost to follow-up. The mean pre-injection VISA scores in the dextrose and saline groups were 58.7 ± 18.3 and 63.4 ± 16.4, respectively. No significant differences were found between the two groups at any time point. The mean VISA score before injections significantly increased at the 1-month follow-up in both groups (P < .01). The injection had no adverse effects. CONCLUSIONS: We were not able to show the efficacy of dextrose injections compared to that of saline. LEVEL OF EVIDENCE: Randomized controlled trial. Level I.

The characteristic findings of an inverted-type discoid lateral meniscus tear: a hidden tear pattern.

BACKGROUND: The purpose of this study was to reveal the clinical history and physical and magnetic resonance imaging (MRI) findings of patients with an inverted-type discoid lateral meniscus (DLM) tear compared with those with a symptomatic and torn discoid meniscus without inverted tear patterns. MATERIALS AND METHODS: Between 2014 and 2016, 12 patients underwent arthroscopic partial meniscectomy for an inverted-type DLM tear (inverted group). We age-matched these patients with 12 controls who were extracted from many normal DLM tear cases in the same period (non-inverted group). The assessment items were traumatic history with the onset of pain, the mean duration between the appearance of symptoms and surgery, preoperative knee range of motion (ROM), positive findings on the McMurray test, knee locking or catching, and characteristic MRI findings. These items were compared between the two groups using χ2 and Student's t-tests. RESULT: All patients in the inverted group had clear trauma with the onset of pain during sports or daily life activities, and 7 of the 12 patients with a non-inverted type of DLM tear had clear trauma. There was a significantly higher rate of traumatic history in the inverted group than in the non-inverted group (P = 0.03). The mean duration between the appearance of symptoms and surgery, preoperative knee ROM, positive findings on the McMurray test, and knee locking or catching were not significantly different between the inverted and non-inverted groups. On MRI, the diagnosis ratio of DLM was significantly higher in the non-inverted group (9/12 cases) than in the inverted group (3/12 cases, P = 0.04). Nine of the 12 inverted-type patients had the characteristic findings of an inverted-type DLM tear, including a duplicated or enlarged posterior horn and blunting of the inner rim, on the sagittal plane of an MRI. CONCLUSION: Patients with inverted-type DLM tears had clear trauma and infrequently had the characteristic MRI findings that are observed in patients with normal DLM tears. Physicians should suspect that an inverted-type DLM tear is present during diagnosis and focus on the posterior horn to find the inverted sign on the MRI sagittal plane. LEVEL OF EVIDENCE: Level III.

Relationship between the deep flexion of the knee joint and the dynamics of the infrapatellar fat pad after anterior cruciate ligament reconstruction via ultrasonography.

[Purpose] A sufficient flexion angle of the knee joint after knee surgery leads to higher quality of their life; therefore, here we investigated the relationship between the dynamics of the infrapatellar fat pad and seiza-style sitting via ultrasonography. [Participants and Methods] Twenty-eight patients were enrolled 3 months post-operatively after anterior cruciate reconstruction. They were divided into a "possible" group and "impossible" group, according to whether they could sit in the seiza style. The thickness of the superficial part of the infrapatellar fat pad was measured at 10° and 90° knee flexion on reconstructed knees in the sitting position via ultrasound evaluation. Images were taken to capture the patella apex and tibial tuberosity. The thickness of the superficial part of the infrapatellar fat pad was measured, and the thickness change ratio was calculated. The characteristics of each group were compared. [Results] The superficial part of the infrapatellar fat pad was significantly thinner in the possible group at a 10° knee flexion. The thickness change ratio of the infrapatellar fat pad was significantly greater in the possible group. [Conclusion] The thickness of the infrapatellar fat pad at a 10° knee flexion and the thickness change ratio of the infrapatellar fat pad could affect the possibility of sitting in the seiza style.

Greater body mass index and hip abduction muscle strength predict noncontact anterior cruciate ligament injury in female Japanese high school basketball players.

PURPOSE: This 3-year prospective study assessed risk factors for noncontact anterior cruciate ligament (ACL) injuries in female Japanese high school basketball players. Players suffering noncontact ACL injuries were assumed to demonstrate poorer hip abductor, knee flexor, and knee extensor muscle strength, as well as static balance, than those without injuries. METHODS: One hundred and ninety-five new female high school basketball players underwent baseline examinations for various parameters during their first year of high school. After the baseline data were collected, all ACL injuries occurring over the subsequent 3 years were recorded. The assessment parameters between the noncontact ACL injury group and the control group were compared. RESULTS: Of the 195 players, 24 were excluded due to pre-existing injuries present during the initial examination, quitting the basketball club during the follow-up period, or missing data. The remaining 171 players were observed for 3 years; unilateral noncontact ACL injuries were occurred in 12 players. Significantly lower general joint laxity and greater hip abductor strength were observed in the ACL injury group than in the control group. Body mass index (BMI) and hip abductor strength were significantly greater in the ACL injury group than in the control group, based on logistic regression analysis. CONCLUSIONS: Greater BMI and hip abductor muscle strength were independent risk factors for noncontact ACL injuries in female Japanese high school basketball players. Although performing complete screens may be difficult, attention should be given to ACL injuries, particularly in highly competitive players with strong muscles. LEVEL OF EVIDENCE: III.

Two-dimensional motion analysis of dynamic knee valgus identifies female high school athletes at risk of non-contact anterior cruciate ligament injury.

PURPOSE: Female athletes are at greater risk of non-contact ACL injury. Three-dimensional kinematic analyses have shown that at-risk female athletes have a greater knee valgus angle during drop jumping. The purpose of this study was to evaluate the relationship between knee valgus angle and non-contact ACL injury in young female athletes using coronal-plane two-dimensional (2D) kinematic analyses of single-leg landing. METHODS: Two hundred ninety-one female high school athletes newly enrolled in basketball and handball clubs were assessed. Dynamic knee valgus was analysed during single-leg drop jumps using 2D coronal images at hallux-ground contact and at maximal knee valgus. All subjects were followed up for 3 years for ACL injury. Twenty-eight (9.6%) of 291 athletes had ACL rupture, including 27 non-contact ACL injuries. The injured group of 27 knees with non-contact ACL injury was compared with a control group of 27 randomly selected uninjured knees. The relationship between initial 2D movement analysis results and subsequent ACL injury was investigated. RESULTS: Dynamic knee valgus was significantly greater in the injured group compared to the control group at hallux-ground contact (2.1 ± 2.4 vs. 0.4 ± 2.2 cm, P = 0.006) and at maximal knee valgus (8.3 ± 4.3 vs. 5.1 ± 4.1 cm, P = 0.007). CONCLUSION: The results of this study confirm that dynamic knee valgus is a potential risk factor for non-contact ACL injury in female high school athletes. Fully understanding the risk factors that increase dynamic knee valgus will help in designing more appropriate training and interventional strategies to prevent injuries in at-risk athletes. LEVEL OF EVIDENCE: Prognostic studies, Level II.

No difference in the graft shift between a round and a rounded rectangular femoral tunnel for anterior cruciate ligament reconstruction: an experimental study.

INTRODUCTION: We developed a novel technique of creating a rounded rectangular femoral bone tunnel for anatomical, single-bundle, autologous hamstring tendon anterior cruciate ligament (ACL) reconstruction. Although this tunnel has many advantages, its non-circular shape has raised concerns regarding excessive graft shift within the bone tunnel. This study aimed to compare the graft shift between round and rounded rectangular tunnels using a graft diameter tester for simulating the femoral bone tunnel. MATERIALS AND METHODS: Seven semitendinosus tendon grafts harvested from fresh-frozen cadavers were prepared by removing all excess soft tissue. The two ends of a double-fold hamstring tendon were sutured using a baseball stitch and then looped over a TightRope (Arthrex Co., Ltd., Naples, Florida, USA) to make a fourfold graft. The diameter of the graft was standardized to 8 mm using a round graft diameter tester. A round and an original rounded rectangular graft diameter tester were used for simulating the respective femoral bone tunnels. The graft was inserted into the tunnel, with the TightRope positioned on the outside of the tunnel. The distal end of the graft was tensioned to 40 N at an angle of 75° to reproduce the most severe graft bending angle. Digital photographs of the tunnel aperture taken at each simulated tunnel and the range of graft shift in the simulated tunnel were analyzed by ImageJ software. Statistical analyses were performed using the Tukey test. P < 0.05 was considered to be significant. RESULTS: There were no significant differences between the round and the rounded rectangular tunnel groups (P > 0.05) in terms of graft shift, gap area, and graft shift ratio. CONCLUSION: In a simulated ACL reconstruction, there is no difference in the graft shift between a round and a rounded rectangular bone tunnel.

Non-use of intra-articular drain after anterior cruciate ligament reconstruction does not affect postoperative knee pain and muscle strength on early period.

Introduction: This study aimed to determine the effect of using an intra-articular drain after anterior cruciate ligament (ACL) reconstruction on early postoperative pain, range of motion (ROM), muscle strength, and complications. Materials and methods: Between 2017 and 2020, of the 200 consecutive patients who underwent anatomical single-bundle ACL reconstruction, 128 patients underwent primary ACL reconstruction with hamstring tendons and were evaluated for postoperative pain and muscle strength at 3 months postoperatively. Sixty-eight patients who received intra-articular drain before April 2019 were classified as group D and 60 patients without an intra-articular drain after ACL reconstruction after May 2019 were classified as group N. Patient background, operative time, postoperative pain, number of additional analgesics used, presence of intra-articular hematoma, ROM at 2, 4, and 12 weeks postoperatively, extensor and flexor muscle strength at 12 weeks postoperatively, and perioperative complications were compared between the two groups. Results: The postoperative pain at 4 h after surgery was significantly greater in group D than in group N although no significant difference was found in the pain felt in the immediate postoperative period and at 1 day and 2 days postoperatively and in the number of additional analgesics used. No significant difference in the postoperative ROM and muscle strength was noted between the two groups. Six patients with intra-articular hematomas in group D and four patients in group N needed puncture by 2 weeks postoperatively, and no significant difference was found between the two groups. Conclusion: Postoperative pain was greater at 4 h postoperatively in group D. Furthermore, the intra-articular drain did not affect muscle strength, ROM, and complications on the early postoperative period. The usefulness of intra-articular drain after ACL reconstruction was considered low. Level of Evidence: Level IV.

Effect of introducing ultrasonography in medical examinations for elbow injuries among young baseball players.

PURPOSE: This study investigated the usefulness of ultrasonography in medical examinations for detecting elbow injuries, especially capitellar osteochondritis dissecans, among young baseball players. METHODS: Players with current or previous elbow joint pain were enrolled. Medical examinations (range of motion, tenderness, and stress tests) were performed with (2012-2016) or without (2007-2011) ultrasonography. Players with abnormal examination results were advised to undergo additional examinations at a local orthopedic clinic. Differences in the rates of capitellar osteochondritis dissecans detection, secondary examination, and elbow injury prevalence were compared between players who did and did not undergo ultrasonography. RESULTS: We identified 1045 baseball players, aged 9-12 years, who required medical examinations for elbow injuries. Medical examinations without ultrasonography were performed in 346 players (group A), and examinations with ultrasonography were performed in 556 players (group B). Capitellar osteochondritis dissecans was present in 0.3% (1/346) of group A players and 3.0% (17/556) of group B players (p = 0.003). The secondary examination consultation rates were 51.2% (62/121) and 66.0% (270/409) in groups A and B, respectively (p = 0.004). CONCLUSION: Ultrasonography performed as a part of a medical examination can help detect elbow injuries, especially capitellar osteochondritis dissecans, in baseball players. Using ultrasonography in conjunction with medical examinations may contribute to a better understanding of elbow injuries in baseball players and improve consultation rates. Thus, ultrasonography is essential for the evaluation of elbow injuries in young baseball players.