A Novel Muscle Atrophy Mechanism: Myocyte Degeneration Due to Intracellular Iron Deprivation.

Muscle atrophy is defined as the progressive degeneration or shrinkage of myocytes and is triggered by factors such as aging, cancer, injury, inflammation, and immobilization. Considering the total amount of body iron stores and its crucial role in skeletal muscle, myocytes may have their own iron regulation mechanism. Although the detrimental effects of iron overload or iron deficiency on muscle function have been studied, the molecular mechanism of iron-dependent muscle atrophy has not been elucidated. Using human muscle tissues and in the mouse rotator cuff tear model, we confirmed an association between injury-induced iron depletion in myocytes and muscle atrophy. In differentiated C2C12 myotubes, the effects of iron deficiency on myocytes and the molecular mechanism of muscle atrophy by iron deficiency were evaluated. Our study revealed that the lower iron concentration in injured muscle was associated with the upregulation of ferroportin, an iron exporter that transports iron out of cells. Ferroportin expression was increased by hypoxia-inducible factor 1α (HIF1α), which is activated by muscle injury, and its expression is controlled by HIF1 inhibitor treatment. Iron deprivation caused myocyte loss and a marked depletion of mitochondrial membrane potential leading to muscle atrophy, together with increased levels of myostatin, the upstream regulator of atrogin1 and muscle RING-finger protein-1 (MuRF1). Myostatin expression under iron deficiency was mediated by an orphan nuclear receptor, dosage-sensitive sex reversal-adrenal hypoplasia congenita critical region on the X chromosome (DAX1).

Remnant preservation with tensioning can improve the clinical outcome after anterior cruciate ligament reconstruction.

BACKGROUND: Many studies exist about remnant preservation in anterior cruciate ligament (ACL) reconstruction. However, concern remains for development of a cyclops lesion during remnant preservation. To prevent this, a tensioning method has been suggested. Current study evaluated the clinical and radiologic results of remnant preservation in ACL reconstruction with tensioning compared to classical ACL reconstruction. METHODS: From January 2016 to June 2017, ACL reconstruction patients who underwent magnetic resonance imaging (MRI) 2 years postoperatively were enrolled. For comparison, all participants were divided in two groups: remnant preservation with tensioning (group R) and controls (group C). Clinically, Hospital for Special Surgery (HSS), International Knee Documentation Committee (IKDC), Lysholm scores, and incidence of symptomatic cyclops lesions were evaluated. Radiologically, signal-to-noise quotient (SNQ) and size of the synovium on MRI as well as anterior instability in Telos stress radiographs were evaluated. RESULTS: A total of 64 patients were enrolled (42 in group R and 22 in group C). The IKDC score in group R (70) was better than that in group C (62; p < 0.05). One patient in group R had a cyclops lesion with clinical symptoms and arthroscopic excision was recommended. Radiologically, the SNQ, synovium area, and anterior instability on Telos radiography showed no difference between the two groups. CONCLUSION: Remnant preservation with tensioning is a good option for ACL reconstruction without the development of a cyclops lesion.

Biplane Medial Opening-Wedge High Tibial Osteotomy Increases Posterior Tibial Slope more than Uniplane Osteotomy.

Few clinical studies have compared uniplane high tibial osteotomy (HTO) with biplane HTO. The study aim was to compare the radiological and clinical results of uniplane HTO and biplane HTO, especially in terms of the increase in the posterior tibial slope (PTS). Medial opening-wedge HTO patients' medical records and radiological results from a single institution were retrospectively reviewed. Pre- and postoperative serial radiographs, including the Rosenberg, lateral view, and standing anteroposterior view of the whole lower extremity, magnetic resonance imaging at postoperative day 2, and the Western Ontario and McMaster Universities Arthritis Index (WOMAC) score at postoperative 2 years were reviewed to evaluate radiological and clinical results, including the change in PTS. A total of 61 knees, including 34 for uniplane and 27 for biplane HTOs, were enrolled. There were no significant differences in the pre- and postoperative mechanical angles or incidences of the lateral hinge fractures, and all patients showed complete union at postoperative 2 years. The PTS was increased more in the biplane group than in the uniplane group (3.1 ± 2.6 in biplane vs. 0.8 ± 1.7 in uniplane, p < 0.05). The WOMAC scores were 72 ± 9.3 in the uniplane and 75 ± 5.8 in the biplane group (not significant). The increase in PTS was lower in uniplane medial opening HTO than in biplane HTO.

Differential regulation of the water channel protein aquaporins in chondrocytes of human knee articular cartilage by aging.

Knee cartilage is in an aqueous environment filled with synovial fluid consisting of water, various nutrients, and ions to maintain chondrocyte homeostasis. Aquaporins (AQPs) are water channel proteins that play an important role in water exchange in cells, and AQP1, -3, and -4 are known to be expressed predominantly in cartilage. We evaluated the changes in AQP expression in chondrocytes from human knee articular cartilage in patients of different ages and identified the key factor(s) that mediate age-induced alteration in AQP expression. The mRNA and protein expression of AQP1, -3 and -4 were significantly decreased in fibrocartilage compared to hyaline cartilage and in articular cartilage from older osteoarthritis patients compared to that from young patients. Gene and protein expression of AQP1, -3 and -4 were altered during the chondrogenic differentiation of C3H10T1/2 cells. The causative factors for age-associated decrease in AQP included H2O2, TNFα, and HMGB1 for AQP1, -3, and -4, respectively. In particular, the protective effect of AQP4 reduction following HMGB1 neutralization was noteworthy. The identification of other potent molecules that regulate AQP expression represents a promising therapeutic approach to suppress cartilage degeneration during aging.

Human umbilical cord-blood-derived mesenchymal stem cell can improve the clinical outcome and Joint space width after high tibial osteotomy.

BACKGROUND: There is limited study about the human umbilical cord-blood derived mesenchymal stem cell (hUCB-MSC) cartilage regeneration procedures combined with high tibial osteotomy (HTO). We compared the clinical and radiological results of hUCB-MSC cartilage regeneration procedures combined with HTO to those of microfracture with HTO. METHODS: From August 2017 to December 2018, HTO patients with International Cartilage Regeneration and Joint Preservation Society (ICRS) grade IV cartilage defects over 200 mm2 on medial femoral condyle (MFC) were enrolled. For comparison, all participants were divided into two groups: those who had undergone an hUCB-MSC induced cartilage regeneration procedure (group MSC) and those with microfractures only (group C, controls). Clinically, Hospital for Special Surgery (HSS), International Knee Documentation Committee (IKDC), and Lysholm scores were evaluated post-operatively at 18 months. Radiologically, mechanical axis (MA) and joint space width (JSW) were evaluated. RESULTS: A total of 100 knees were enrolled (43 in group MSC, 57 in group C). The IKDC score in group MSC (69) was better than that in group C (62; P < 0.05). The JSW increment in the MSC group (0.6 mm) was more than that in group C (0.1 mm; P < 0.05). No patient developed nonunion, correction loss, or arthroplasty conversion. CONCLUSION: hUCB-MSCs can improve clinical outcome and JSW better than microfracture only in HTO patients.

Simple Medial Meniscus Posterior Horn Root Repair Using an All-Inside Meniscal Repair Device Combined with High Tibial Osteotomy to Maintain Joint-Space Width in a Patient with a Repairable Tear.

PURPOSE: To compare the radiological and clinical outcomes using simple medial meniscus posterior horn (MMPH) root repair using an all-inside meniscal repair device combined with high tibial osteotomy (HTO) and HTO alone. METHODS: Between November 2013 and December 2016, patients treated for MMPH root tear along with HTO were enrolled. Based on the tear gap, the participants were divided into repairable (< 2 mm) and unrepairable (> 2 mm) categories. The participants in each group were divided into those amenable to simple MMPH root repair using an all-inside meniscal repair device and those that required no procedure for meniscus. Radiological parameters including mechanical femorotibial alignment (MA), posterior tibial slope (PTS) and medial joint-space width (JSW) were evaluated preoperatively and postoperatively at 2 years. For clinical evaluation, the WOMAC score was determined at the 2-year visit postoperatively. RESULTS: A total of 81 knees including 48 repairable (group R) and 33 unrepairable (group I) knees were enrolled. A total of 43 knees underwent simple MMPH root repair using an all-inside meniscal repair device (subgroup r), whereas the other 38 knees did not (subgroup n). The MA, PTS, and their postoperative changes as well as the WOMAC scores showed no differences. However, the JSW in group Rr increased from 3.1 to 3.6 mm, but decreased from 3.7 to 3.4 in group Rn, which was a statistically significant difference. CONCLUSION: Simple MMPH root repair using an all-inside meniscal repair device combined with HTO was more effective for the maintenance of JSW compared with HTO without a meniscal procedure in patients with repairable MMPH root tear and varus alignment. However, other options are needed for unrepairable MMPH root tear.

Uniplane medial opening wedge high tibial osteotomy relative to a biplane osteotomy can reduce the incidence of lateral-hinge fracture.

PURPOSE: With surgical modifications reflecting plate design differences of the specific rigid locking plate adding a metal wedge, uniplane high tibial osteotomy (HTO) has fewer lateral-hinge fractures and fewer plate irritations than biplane HTO. METHODS: Uniplane HTO with a rigid locking plate adding a metal wedge was compared with biplane HTO with a rigid locking plate including a proximal D-hole. For comparison, the HTO patients' medical records and radiological results in a single institution were retrospectively reviewed. The Oxford knee score 2 years post-operation, CT scan at post-operative day 2 and serial standing long-bone scanography were reviewed to evaluate clinical outcome and radiological results, including the incidence of lateral-hinge fracture, plate irritation and correction loss to varus alignment. RESULTS: A total of 103 knees, including 59 uniplane HTO and 44 biplane HTO, were enrolled. The Oxford scores were 38.1 ± 7.8 in the uniplane group and 35.9 ± 8.3 in the biplane group (ns). On CT scans, more lateral-hinge fractures developed in the biplane group, and seven knees (12%) of the uniplane group and 12 knees (27%) of the biplane group had Takeuchi type I stable hinge fracture (p < 0.05); unstable fracture was not noted in either group. Plate irritation occurred in nine knees (19%) of the uniplane group and in 14 knees (32%) of the biplane group, and the difference was statistically significant (p < 0.05). CONCLUSION: In clinical situations including the use of surgical modifications reflecting plate design differences, fewer lateral-hinge fractures developed after uniplane medial opening-wedge HTO compared with biplane HTO. Uniplane HTO potentially represents a better option than biplane HTO for the prevention of lateral-hinge fracture. LEVEL OF EVIDENCE: IV.

Evaluation of Healing After Medial Meniscal Root Repair Using Second-Look Arthroscopy, Clinical, and Radiological Criteria.

BACKGROUND: Previous studies have reported various healing rates (0%-100%) as evaluated by second-look arthroscopy after repair of medial meniscal root tears (MMRTs). Such variable results might provoke suspicion of the necessity for repair. Furthermore, the effect of meniscal healing on the clinical outcomes has not been reported. PURPOSE: To more precisely determine the healing rate of MMRTs repaired through the transseptal portal, which could provide objective visualization of the healed meniscus, and to identify the effect of meniscal healing on the clinical and radiological outcomes. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Between June 2010 and April 2015, 56 patients underwent pullout suture for MMRT. Lysholm score, Hospital for Special Surgery score, International Knee Documentation Committee subjective score, medial joint space height, and Kellgren-Lawrence (K-L) grade were evaluated. Thirty-three patients underwent second-look arthroscopy and were divided into a "stable healed group" and "unhealed group" according to their healing status, as evaluated through the transseptal portal. The intraoperative, clinical, and radiological outcomes of the 2 groups were compared. RESULTS: All other clinical outcomes improved. However, medial joint space became significantly narrower ( P < .001), and 23 patients (41%) showed K-L grade progression. On the basis of second-look arthroscopy, 23 patients (69.7%) were classified into a stable healed group and 10 (30.3%) into a unhealed group. The stable healed group showed a higher Hospital for Special Surgery score ( P = .023), International Knee Documentation Committee subjective score ( P = .031), and successful microfracture rate ( P = .023), with less progression of medial joint space narrowing ( P < .001) and K-L grade ( P < .001). CONCLUSION: Despite degenerative change progression, clinical outcomes were improved. The successful healing rate was 69.7% after repair of MMRTs. Compared with the unhealed group, the stable healed group showed better clinical outcomes and less degenerative change progression.

Efficacy of Tranexamic Acid for Hemostasis in Patients Undergoing High Tibial Osteotomy.

Extensive bone bleeding and an uncomfortable hematoma can develop due to the opening gap and space during a medial open high tibial osteotomy (HTO). Tranexamic acid (TXA) has been used in various orthopaedic surgeries to reduce bleeding and wound complications. However, no study has investigated the effect of TXA during HTO. Therefore, the purpose of this study is to evaluate the efficacy of TXA in reducing postoperative blood loss in patients undergoing HTO. The hypothesis is that topical TXA administration will reduce postoperative bleeding in patients undergoing medial opening HTO. Topical TXA (2 g in 20 mL saline) was administered at the osteotomy site in patients (n = 15) who underwent medial open HTO from November 2015 to March 2016. Patients (n = 15) who underwent medial open wedge HTO by the same surgeon from October 2014 to October 2015 were enrolled as a control group for comparison. Drainage volumes on postoperative days (PODs) 1, 2, and 3 as well as hemoglobin (Hb) level on PODs 1, 6, and 13 were measured and compared. Mean total postoperative drainage volume was 246 mL in the TXA group and 377 mL in the control group. Mean drainage volume on POD 1 was 138 mL in the TXA group and 277 mL in the control group (p < 0.05). No differences in drainage volume were detected between the groups on POD 2 or 3. Preoperative Hb levels were 13.0 g/dL in the TXA group and 12.9 g/dL in the control group, which decreased to 11.9 g/dL in the TXA group and 11.2 g/dL in the control group on POD 1. These postoperative Hb differences were significant (p < 0.05). Also, Hb levels were 11.7 and 12.0 g/dL in the TXA group and 11.4 and 11.6 g/dL in the control group on PODs 6 and 13, respectively (p > 0.05). An extensive hematoma requiring additional surgery developed in one case in the control group. No wound complications were detected in the TXA group. Topical TXA was effective for reducing postoperative bleeding after medial open HTO. The level of evidence of the study is Level 3.

Tunnel widening prevention with the allo-Achilles tendon graft in anterior cruciate ligament reconstruction: Surgical tips and short term followup.

BACKGROUND: Tunnel widening (TW) after anterior cruciate ligament (ACL) reconstruction can be a serious complication, and there is controversy over how to prevent it. This study aimed to suggest surgical approaches to prevent TW using an allo-Achilles tendon graft, and then to evaluate TW after these surgical tips were applied. MATERIALS AND METHODS: Sixty two patients underwent ACL reconstruction with an allo-Achilles tendon graft. Four surgical approaches were used: Making a tibial tunnel by bone impaction, intraarticular reamer application, bone portion application for the femoral tunnel, and an additional bone plug application for the tibial tunnel. After more than 1-year, followup radiographs including anteroposterior and lateral views were taken in 29 patients encompassing thirty knees. The diameter of the tunnels at postoperation day 1 (POD1) and at followup was measured and compared. RESULTS: In 18 knees (60%), there were no visible femoral tunnel margins on the radiographs at POD1 or followup. In the other 12 cases, which had visible femoral tunnel margins on followup radiographs, the mean femoral tunnel diameter was 8.6 mm. In the tibial tunnel, the mean diameters did not increase on all three levels (proximal, middle, and distal), and there was no statistically significant difference between the diameters at POD1 and followup. CONCLUSION: The suggested tips for surgery involving an allo-Achilles tendon graft can effectively prevent TW after ACL reconstruction according to this case series. These surgical tips can prevent TW.

Intravenous iron supplementation with intra-articular administration of tranexamic acid reduces the rate of allogeneic transfusions after simultaneous bilateral total knee arthroplasty.

BACKGROUND: Peri-operative intravenous administration of iron supplementation seems a good option to reduce allogeneic blood transfusion in major orthopaedic surgery. However, its efficacy in simultaneous bilateral total knee arthroplasty has not been studied. MATERIALS AND METHODS: From December 2014 to May 2015, a total of 72 consecutive patients underwent simultaneous bilateral total knee arthroplasty and received peri-operative intravenous iron supplementation (iron isomaltoside 1000: 600 mg pre-operatively and 400 mg 1 week post-operatively) and intra-articular tranexamic acid (2 g in 20 mL saline at the end of surgery), and were managed with a restrictive transfusion trigger (haemoglobin <7 g/dL). Post-operatively, we observed patients closely for symptoms of anaemia and checked their haemoglobin levels on days 1, 6 and 13 after surgery. RESULTS: The mean baseline haemoglobin level was 13.1 g/dL. The levels remained above 7.0 g/dL on post-operative days 1, 6 and 13 (mean, 11.4 g/dL, 9.9 g/dL and 10.4 g/dL, respectively) in all but one patient who experienced melaena and required allogeneic blood transfusion. DISCUSSION: Intravenous iron supplementation combined with intra-articular administration of tranexamic acid seems to be an effective strategy for reducing the rate of allogeneic blood transfusion in patients undergoing simultaneous bilateral total knee arthroplasty managed with a restrictive transfusion trigger.

Disparity between Clinical and Ultrasound Examinations in Neonatal Hip Screening.

BACKGROUND: For early detection of developmental dysplasia of the hip (DDH), neonatal hip screening using clinical examination and/or ultrasound has been recommended. Although there have been many studies on the reliability of both screening techniques, there is still controversy in the screening strategies; clinical vs. selective or universal ultrasound screening. To determine the screening strategy, we assessed the agreement among the methods; clinical examination by an experienced pediatric orthopedic surgeon, sonographic morphology, and sonographic stability. METHODS: From January 2004 to June 2009, a single experienced pediatric orthopedic surgeon performed clinical hip screenings for 2,686 infants in the neonatal unit and 43 infants who were referred due to impressions of hip dysplasia before 3 months of age. Among them, 156 clinically unstable or high-risk babies selectively received bilateral hip ultrasound examinations performed by the same surgeon using the modified Graf method. The results were analyzed statistically to detect any correlations between the clinical and sonographic findings. RESULTS: Although a single experienced orthopedic surgeon conducted all examinations, we detected only a limited relationship between the results of clinical and ultrasound examinations. Ninety-three percent of the clinically subluxatable hips were normal or immature based on static ultrasound examination, and 74% of dislocating hips and 67% of limited abduction hips presented with the morphology below Graf IIa. A total of 80% of clinically subluxatable, 42% of dislocating and 67% of limited abduction hips appeared stable or exhibited minor instability on dynamic ultrasound examination. About 7% of clinically normal hips were abnormal upon ultrasound examination; 5% showed major instability and 3% showed dysplasia above Graf IIc. Clinical stability had small coefficients between ultrasound examinations; 0.39 for sonographic stability and 0.37 for sonographic morphology. Between sonographic stability and morphology, although 71% of hips with major instability showed normal or immature morphology according to static ultrasound examination, the coefficient was as high as 0.64. CONCLUSIONS: Discrepancies between clinical and ultrasound examinations were present even if almost all of the exams were performed by a single experienced pediatric orthopedic surgeon. In relation to screening for DDH, it is recommended that both sonographic morphology and stability be checked in addition to clinical examination.

Dynamic Three-Dimensional Analysis of Lachman Test for Anterior Cruciate Ligament Insufficiency: Analysis of Anteroposterior Motion of the Medial and Lateral Femoral Epicondyles.

PURPOSE: To evaluate dynamic three-dimensional (3D) kinematic properties of the anterior cruciate ligament (ACL)-insufficient knees and healthy contralateral knees in awake patients during the Lachman test using biplane fluoroscopy. MATERIALS AND METHODS: Ten patients with unilateral ACL-insufficient knees and healthy contralateral knees were enrolled in this study. Each patient underwent the Lachman test three times in the awake state. The knee joint motions were captured using biplane fluoroscopy. After manual registration of 3D surface data from 3D-computed tomography to biplane images, dynamic 3D kinematic data were analyzed. RESULTS: The average anteroposterior (AP) translation of the medial femoral epicondyle of the ACL-insufficient knees (11.5±4.2 mm) was significantly greater than that of the contralateral knees (7.7±3.5 mm) (p<0.05). However, there was no statistically significant side-to-side difference in the average AP translation of the lateral femoral epicondyle. During the Lachman test, the distal femur was more externally rotated than the proximal tibia, which showed significant difference between both sides. CONCLUSIONS: During the Lachman test, the medial femoral epicondyle of the ACL-insufficient knee exhibited greater AP motion than that of the contralateral knee, whereas there was no significant side-to-side difference with regard to the AP motion of the lateral femoral epicondyle.

High Axial Loads While Walking Increase Anterior Tibial Translation in Intact and Anterior Cruciate Ligament-Deficient Knees.

PURPOSE: To evaluate the effect of high axial loading (AL) on anterior tibial translation (ATT) according to the increase in knee flexion and the effect of valgus stress (VS) and internal rotation (IR) combined with high AL in intact and anterior cruciate ligament (ACL)-deficient knees according to the increase in knee flexion. METHODS: We used 10 fresh-frozen, human cadaveric knees. Different loading conditions (134-N anterior drawer, 1,000-N AL, 10-Nm VS, and 5-Nm IR) were sequentially combined, and ATT was measured at 0°, 15°, 30°, 45°, and 60° of flexion in the intact and ACL-deficient knees. RESULTS: ATT increased significantly by adding high AL in intact knees (P = .001) and ACL-deficient knees (P < .0001) according to the change in flexion angle (P < .0001). Under high AL, ATT in the ACL-deficient knees was significantly larger than that in the intact knees for all loading conditions, and it also increased gradually according to the increase in knee flexion (P = .0001). ATT increased significantly after adding IR or VS with high AL in intact knees (VS, P = .002; VS/IR, P = .03) and ACL-deficient knees (VS, P = .0004) at some of the flexion angles. CONCLUSIONS: The added high AL increased ATT in intact and ACL-deficient knees from 0° to 60° of flexion. The effect of high AL on ATT became greater in ACL-deficient knees than in intact knees, and ATT also gradually increased according to the increase in knee flexion from 0° to 60°. In both the intact and ACL-deficient knees, ATT increased significantly after valgus stress or IR from 0° to 60°. CLINICAL RELEVANCE: ATT during weight bearing increases stress to the ACL, which worsens with valgus stress and/or IR forces. This finding should be considered when one is studying ACL injury mechanisms, as well as prescribing rehabilitation after ACL surgery.

Arthroscopic repair of bucket-handle tears of the lateral meniscus.

PURPOSE: This study was undertaken to document the clinical results of arthroscopic meniscus repair for treatment of displaced bucket-handle tears of the lateral meniscus. METHODS: From 2002 to 2010, 13 patients with symptomatic displaced bucket-handle tears of the lateral meniscus treated by arthroscopic meniscus repair were included in this study. Inclusion criteria were (1) displaced bucket-handle tear of the lateral meniscus demonstrated on magnetic resonance imaging, (2) non-discoid lateral meniscus, (3) stable knee, and (4) tears involving the red-white or red-red zone. Median age at operation was 20 years (range 14-54 years), and the median follow-up period was 4.0 years (range 2-10.7 years). All tears were repaired with either a modified all-inside suture technique only or a combination of the modified all-inside suture and modified outside-in techniques. Clinical results were evaluated preoperatively and at the final follow-up using Tegner activity level, Lysholm knee, and Hospital for Special Surgery (HSS) scores. RESULTS: All patients returned to their prior life activities with little or no limitations, and no reoperations were required during the follow-up period. On the final follow-up, all knees achieved full range of motion, except two knees with limited function during squatting and jumping due to pain. No patient had recurrence of a knee-locking episode. The median Tegner activity level improved significantly from 3 (2-6) to 7 (4-9) (p < 0.0001), mean Lysholm knee score improved from 78.5 ± 10.7 preoperatively to 94.6 ± 5.4 (p < 0.0001), and mean preoperative HSS score improved from 80.3 ± 8.5 to 95.9 ± 4.2 (p < 0.0001) during the follow-up period. CONCLUSION: Arthroscopic meniscus repair using the modified all-inside suture and modified outside-in techniques showed excellent clinical outcomes for treatment of symptomatic displaced bucket-handle tears of the lateral meniscus and were free of any complications or episodes of recurrence. LEVEL OF EVIDENCE: Case series, Level IV.

Effect of axial loading during knee flexion on ACL end-to-end distance in healthy and ACL-deficient knees.

PURPOSE: The purpose of this study was to determine the effect of physiological axial loading during knee flexion on changes in anterior cruciate ligament (ACL) end-to-end distance for normal and ACL-deficient knees. METHODS: Biomechanical tests were conducted on ten cadaveric knees using an Instron machine. We gathered positional data of the tibia and femur at low to middle flexion angles (0°, 15°, 30°, 45° and 60°) with/without axial loading. First, no external load was applied to the specimens at each angle, and then, a 1000-N axial load was applied to the knees. The same test protocols were repeated after transection of the ACL. Using computer software (Geomagic Studio 10), we regenerated positional data and calculated the end-to-end distances of the anteromedial, posterolateral and the entire ACL bundle at each angle. RESULTS: Compared with ACL-intact knees without axial loading, knees under axial loading did not show significant increases in end-to-end distance. Under axial loading, we found no significant differences in end-to-end distances between bundles in ACL-intact knees according to the increase in knee flexion angle. After ACL transection, axial loading significantly increased end-to-end distances of all three bundles (P < 0.001), and the distances increased significantly with flexion angle (P < 0.05 at all angles in all bundles). CONCLUSION: The changing patterns of the ACL end-to-end distance in ACL-deficient knees were different from those in healthy knees after applying physiological axial loading, and the ACL end-to-end distances in ACL-deficient knees increased remarkably as knee flexion angles increased.

Are navigation systems accurate enough to predict the correction angle during high tibial osteotomy? Comparison of navigation systems with 3-dimensional computed tomography and standing radiographs.

BACKGROUND: Unpredicted overcorrection of the mechanical axis can occur during navigation-assisted high tibial osteotomy (HTO). It is not clear whether the erroneous overcorrection stems from the navigation system itself or from other causes. PURPOSE: To evaluate the accuracy of the navigation system in HTO by comparing the change in the femorotibial angle provided by the navigation system with the bony correction angle of the proximal tibia on 3-dimensional computed tomography (3D CT) and with the change in mechanical femorotibial alignment on standing whole-leg radiographs. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 2. METHODS: A total of 16 knees underwent navigation-assisted HTO, and their alignment data were obtained before and after correction. For comparison, preoperative and follow-up standing whole-leg anteroposterior radiographs, lateral knee radiographs, and preoperative and postoperative 3D CT scans were taken. The medial proximal tibial angle (MPTA), posterior tibial slope, and mechanical femorotibial angle (mFTA) were measured in these images, and the 3 coronal and 3 sagittal correction angles were compared with each other. RESULTS: In the coronal plane, the mean correction angle of the navigation system was 9.3° ± 2.0° valgus (range, 6°-13°), and the mean MPTA on 3D CT increased 9.7° ± 2.0° (range, 6.7°-13.8°) after correction. The mean correction angle of the mFTA on standing radiographs was 11.9° ± 3.2° valgus (range, 6.9°-16.5°). There was no statistical significance between the navigation system and 3D CT (P = .187), but there was a statistically significant difference between the navigation system and standing radiographs (P = .001). The results of the correction angle in the sagittal plane were similar to those in the coronal plane. CONCLUSION: The correction of the femorotibial angle by the navigation system was not different from the bony correction angle on 3D CT. There was a discrepancy between the correction angle of the navigation system and that of the standing radiograph. CLINICAL SIGNIFICANCE: Surgeons must be cautious about the tension of soft tissue, even when using the navigation system during HTO.

Anatomic double-bundle reconstruction techniques result in graft obliquities that closely mimic the native anterior cruciate ligament anatomy.

BACKGROUND: It has been reported previously that single-bundle anterior cruciate ligament (ACL) reconstruction with more accurate restoration of the footprint of the native ACL fails to restore the graft obliquity of the native ACL in the coronal plane. Whether double-bundle ACL reconstruction restores the graft obliquity of each bundle of the native ACL has not yet been determined. HYPOTHESIS: Anatomic double-bundle ACL reconstruction using transportal (TP) and outside-in (OI) techniques can restore the graft obliquities of both anteromedial (AM) and posterolateral (PL) bundles in the native ACL in both sagittal and coronal planes. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Seventy-six patients underwent anatomic double-bundle ACL reconstruction. Patients were randomized to 2 groups to undergo either TP or OI tibial tunnel-independent anatomic ACL reconstruction. All participants underwent postoperative magnetic resonance imaging of both knees, and the native ACL obliquity was determined using the participant's contralateral knee. Graft obliquities were determined by measuring the angles between the center line of the graft and the surface line of the tibial plateau, and the obliquities of paired knees were compared. Graft obliquities were analyzed in each group. RESULTS: In the sagittal plane, the mean AM graft obliquity was 54.2° on the operated side and 54.6° on the nonoperated side, and the difference between sides was not statistically significant (P = .352). The mean PL graft obliquity in the sagittal plane was 54.1° on the operated side and 53.0° on the nonoperated side, and the difference between sides was also not statistically significant (P = .228). In the coronal plane, the mean AM graft obliquity was 73.8° on the operated side and 73.4° on the nonoperated side, and the mean PL graft obliquity was 65.5° on the operated side and 66.4° on the nonoperated side. There were no statistically significant differences between sides (P = .418 for AM graft; P = .328 for PL graft). Differences in the paired graft obliquities in each group were also statistically insignificant between the TP and OI groups. CONCLUSION: Both TP and OI anatomic double-bundle reconstruction techniques can result in graft obliquities in both bundles that resemble the native ACL in both sagittal and coronal planes. CLINICAL RELEVANCE: Double-bundle ACL reconstruction techniques might more closely restore the normal kinematics of the native ACL by restoring the normal obliquity of both ACL bundles.

Factors affecting assessment of ulnar bowing in radiography.

BACKGROUND: The "ulnar bow sign" is a novel marker of plastic ulnar deformity with radial head dislocation. This sign is best assessed on true lateral radiographs. However, such radiographs are rarely obtained in routine clinical situations. Misdiagnosis can result from using suboptimum radiographs. The present study examined the clinical radiographs of normal forearms in children to identify factors that affect the assessment of ulnar bowing. METHODS: We retrospectively analyzed the lateral forearm radiographs of 175 normal children ranging in age from 2 to 12 years. Radiographs were classified according to humeral position. The size and direction of the maximum ulnar bow were evaluated. The effect of humeral position, age, sex, and arm side on ulnar bow assessment were analyzed. RESULTS: Of the 175 radiographs, 27 showed a concave dorsal ulnar border (15.4%), 90 showed a straight dorsal ulnar border (51.4%), and 58 showed a convex dorsal ulnar border (33.2%). Only 22 (12.6%) radiographs were found to be true lateral radiographs; the remainder showed evidence of humeral rotation and/or tilting. Humeral tilting was found to affect the assessment of ulnar bowing (P<0.05), whereas the other measured factors did not. CONCLUSIONS: The present study found that humeral tilting at the time of forearm radiography affected the assessment of ulnar bowing. Therefore, physicians should be cautious when assessing ulnar bow in the clinical setting. LEVEL OF EVIDENCE: Level IV.

Arthroscopic treatment of synovial chondromatosis at the knee posterior septum using a trans-septal approach: report of two cases.

Synovial chondromatosis of the knee joint rarely develops in the posterior septum. Such cases are difficult to treat arthroscopically since the posterior septum is not readily accessible via standard portals. We report two cases of localized synovial chondromatosis in the posterior septum. We used a posterior trans-septal portal to arthroscopically remove the loose bodies and perform a concomitant synovectomy. The two cases were followed-up for 24 and 16 months after surgery, respectively, and the patients were found to be pain-free, have a full range of knee motion and showed no evidence of recurrence. A posterior trans-septal portal may be essential in some cases for treatment of synovial chondromatosis at the posterior septum.