Release or transection of superficial medial collateral ligament during open-wedge high tibial osteotomy demonstrated similar clinical outcomes and valgus laxity.

PURPOSE: To analyse whether valgus laxity and clinical outcomes differ depending on whether the superficial medial collateral ligament (sMCL) is released or transected during medial open-wedge high tibial osteotomy (MOWHTO). METHODS: Consecutive patients who underwent MOWHTO and subsequent radiological follow-up for at least 2 years were retrospectively evaluated. The patients were divided into release and transection groups, according to the sMCL manipulation technique. Each patient was assessed for the following variables on valgus stress radiographs taken before surgery and at the 12- and 24-month follow-ups: the absolute value of valgus (ABV) and side-to-side difference (SSD) between the affected and normal sides. The differences between preoperative SSD and those at 12 and 24 months were respectively calculated and defined as delta SSD (ΔSSD). The Visual Analogue Scale, Lysholm knee, International Knee Documentation Committee subjective, and Knee Injury and Osteoarthritis Outcome scores were used to evaluate patient-reported outcomes. RESULTS: Eighty-five patients were included in the study. Forty-two patients (49.6%) underwent sMCL release, and the remaining 43 patients (50.4%) underwent sMCL transection. No significant differences were observed in the ABV and SSD of valgus laxity at the different time points between the two groups (n.s.). Furthermore, no significant differences were observed in the ΔSSD at the 12- and 24-month follow-ups between the two groups (n.s.). Significant improvement from preoperative values was observed in all patient-reported outcomes (p < 0.001), with no significant differences between the two groups at any time point (n.s.). CONCLUSION: Significant improvements in clinical outcomes were observed, regardless of the technique used. Postoperative valgus laxity did not occur with either technique. The transection technique, which can be performed more simply and quickly, demonstrated similar clinical outcomes and valgus laxity to the release technique. LEVEL OF EVIDENCE: Level III.

Preoperative joint line obliquity, a newly identified factor for overcorrection, can be incorporated into a novel preoperative planning method to optimise alignment in high tibial osteotomy.

PURPOSE: The aim of this study was to analyse the factors associated with additional postoperative alignment changes after accurate bony correction by selecting only patients with well-performed bony correction as planned and develop a method of incorporating significant factors into preoperative planning. METHODS: Among 104 consecutive patients who underwent medial open wedge high tibial osteotomy (MOWHTO) between October 2019 and July 2022, 61 with well-performed bony corrections were retrospectively reviewed. The major criterion for well-performed bony correction was a difference of <1° between the simulated medial proximal tibial angle (MPTA) and the actual postoperative MPTA as measured in three dimensions. Radiographic parameters, such as the joint line convergence angle (JLCA) and joint line obliquity (JLO), were measured preoperatively and postoperatively, utilising standing and supine whole lower extremity anteroposterior, valgus and varus stress radiographs. Multiple linear regression analysis identified the factors affecting alignment changes, and a prediction model was developed. A method for applying this prediction model to preoperative planning was proposed. RESULTS: Preoperative JLCA on standing (preJLCAstd ), preoperative JLCA on 0° valgus stress radiograph (vgJLCA0 ), and preoperative JLO (preJLO) were significantly correlated with JLCA change (∆JLCA) (p < 0.001, p < 0.001, p = 0.006). The prediction model was estimated as ∆JLCA = 0.493 × (vgJLCA0 ) - 0.727 × (preJLCAstd ) + 0.189 × (preJLO) - 1.587 in. (R = 0.815, modified R2 = 0.646, p < 0.001). The proposed method resulted in a reduced overcorrection rate (p = 0.003) and an improved proportion of acceptable alignments (p = 0.013). CONCLUSION: PreJLCAstd , vgJLCA0  and preJLO can be used to estimate ∆JLCA. PreJLO was recently identified as a significant factor associated with additional alignment changes. Utilising the proposed preoperative planning and a prediction model with these factors shows promise in calibrating postoperative alignment after MOWHTO. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

Implantation of hUCB-MSCs generates greater hyaline-type cartilage than microdrilling combined with high tibial osteotomy.

PURPOSE: To compare the outcomes of treating large cartilage defects in knee osteoarthritis using human allogeneic umbilical cord blood-derived mesenchymal stem cell (hUCB-MSC) implantation or arthroscopic microdrilling as a supplementary cartilage regenerative procedure combined with high tibial osteotomy (HTO). METHODS: This 1-year prospective comparative study included 25 patients with large, near full-thickness cartilage defects (International Cartilage Repair Society grade ≥ IIIB) in the medial femoral condyles and varus malalignment. Defects were treated with hUCB-MSC implantation or arthroscopic microdrilling combined with HTO. The primary outcomes were pain visual analogue scale and International Knee Documentation Committee subjective scores at 12, 24 and 48 weeks. Secondary outcomes included arthroscopic, histological and magnetic resonance imaging assessments at 1 year. RESULTS: Fifteen and 10 patients were treated via hUCB-MSC implantation and microdrilling, respectively. Baseline demographics, limb alignment and clinical outcomes did not significantly differ between the groups. Cartilage defects and total restored areas were significantly larger in the hUCB-MSC group (7.2 ± 1.9 vs. 5.2 ± 2.1 cm2, p = 0.023; 4.5 ± 1.4 vs. 3.0 ± 1.6 cm2, p = 0.035). The proportion of moderate-to-strong positive type II collagen staining was significantly higher in the hUCB-MSC group compared to that in the microdrilled group (93.3% vs. 60%, respectively). Rigidity upon probing resembled that of normal cartilage tissue more in the hUCB-MSC group (86.7% vs. 50.0%, p = 0.075). Histological findings revealed a higher proportion of hyaline cartilage in the group with implanted hUCB-MSC (p = 0.041). CONCLUSION: hUCB-MSC implantation showed comparable clinical outcomes to those of microdrilling as supplementary cartilage procedures combined with HTO in the short term, despite the significantly larger cartilage defect in the hUCB-MSC group. The repaired cartilage after hUCB-MSC implantation showed greater hyaline-type cartilage with rigidity than that after microdrilling. LEVEL OF EVIDENCE: Level II, Prospective Comparative Cohort Study.

Marrow stimulation procedures for high-grade cartilage lesions during surgical repair of medial meniscus root tear yielded suboptimal outcomes, whilst small lesions showed surgical eligibility.

PURPOSE: To investigate the surgical outcomes of arthroscopic pull-out repair for medial meniscus root tear (MMRT) combined with the marrow stimulation procedures (MSP) for accompanying high-grade cartilage lesions. METHODS: Patients who underwent arthroscopic pull-out repair for MMRT between 2010 and 2019 were retrospectively reviewed. Patients who had at least 3 years of follow-up were included and classified into two groups according to whether MSP (microfracture or microdrilling) were performed on cartilage lesions in the medial tibiofemoral joint (group 1, patients with International Cartilage Repair Society [ICRS] grade 0-3a lesions and did not undergo MSP; group 2, patients with ICRS grade 3b-3d lesions and underwent MSP). Comparative analyses, including non-inferiority trials, were conducted between groups for subjective and objective outcomes. In addition, group 2 was further divided into two subgroups according to cartilage lesion size and compared with group 1 (group S, ≤ 2.0 cm2; group L, > 2.0 cm2). RESULTS: A total of 94 patients were included (group 1, 68 patients; group 2, 26 patients). There were no significant differences in clinical scores at postoperative 3 years and final follow-up between groups 1 and 2, but group 2 failed to satisfy the non-inferiority criteria compared to group 1 overall. In objective outcomes, group 2 did not meet the non-inferiority criteria for the rate of osteoarthritis progression compared to group 1, and it also showed a significantly higher proportion of high-grade osteoarthritis at final follow-up (P = 0.044) and a higher degree of osteoarthritis progression than group 1 (P = 0.03 for pre- to postoperative 3 years, and P = 0.006 for pre- to final follow-up). In additional evaluations comparing the subgroups of group 2 and group 1, group S showed relatively favourable results compared to group L in objective outcomes at final follow-up. CONCLUSION: Patients who underwent arthroscopic pull-out repair for MMRT combined with MSP for accompanying high-grade cartilage lesions showed suboptimal outcomes compared to those with no or low-grade lesions at mid-term follow-up. High-grade cartilage lesions ≤ 2.0 cm2 may be candidates for the surgical repair of MMRT if MSP are performed, but those with larger lesions may require alternative treatment strategies. LEVEL OF EVIDENCE: III.

Outpatient-based diagnostic criteria for partial ACL injury: clinical outcomes of non-operative treatment and radiographic predictor.

INTRODUCTION: This study aimed to (1) evaluate the short-term clinical outcomes of patients who underwent non-operative treatment for partial anterior cruciate ligament (ACL) tears diagnosed using the outpatient-based diagnostic criteria and (2) investigate the radiographic predictors distinguishing patients at risk of non-operative treatment failure. METHODS: From 2010 to 2019, patients diagnosed with partial ACL tears and treated with non-operative treatment were reviewed retrospectively. Patients were then classified into two groups: those who successfully responded to non-operative treatment (group S) and those who failed to respond to non-operative treatment and required surgical reconstruction within 6 months after injury (group F). ACL laxity, patient-reported outcomes (PROs), and several radiographic parameters were analyzed. To identify radiographic predictors related to clinical outcomes, radiographic parameters were compared between the groups, which were statistically matched for potential confounders (age and activity level) using inverse probability of treatment weighting. RESULTS: A total of 44 patients were analyzed (mean age, 28.7 ± 8.7 years; 31 men), and classified into two groups (group S, 23 patients; group F, 21 patients). There were no significant differences in ACL laxity and PROs between the groups at 1 year after either non-operative treatment or surgical reconstruction. A comparison of radiographic parameters between the groups revealed significant differences in several parameters related to secondary signs of ACL injury. Subsequent regression analyses revealed that anterior tibial translation and extent of bone bruises were radiographic predictors related to clinical outcomes. CONCLUSION: Non-operative treatment for partial ACL tears diagnosed using the outpatient-based diagnostic criteria can provide successful short-term clinical outcomes in selective patients. Secondary signs of ACL injuries, particularly the amount of anterior tibial translation and the extent of bone bruises, are radiographic predictors that could differentiate patients at risk of non-operative treatment failure. LEVEL OF EVIDENCE: Retrospective cohort study, III.

Medial Meniscus Posterior Root Tear: How Far Have We Come and What Remains?

Medial meniscus posterior root tears (MMRTs), defined as tears or avulsions that occur within 1 cm of the tibial attachment of the medial meniscus posterior root, lead to biomechanically detrimental knee conditions by creating a functionally meniscal-deficient status. Given their biomechanical significance, MMRTs have recently been gaining increasing interest. Accordingly, numerous studies have been conducted on the anatomy, biomechanics, clinical features, diagnosis, and treatment of MMRTs, and extensive knowledge has been accumulated. Although a consensus has not yet been reached on several issues, such as surgical indications, surgical techniques, and rehabilitation protocols, this article aimed to comprehensively review the current knowledge on MMRTs and to introduce the author's treatment strategies.

The orientation of the ALL femoral tunnel to minimize collision with the ACL tunnel depends on the need or not of far-cortex drilling.

PURPOSE: To (1) evaluate the optimal drill orientation of the anterolateral ligament (ALL) femoral tunnel to minimize collision with the anterior cruciate ligament (ACL) femoral tunnel during anatomical ACL reconstruction according to the need for far-cortex drilling and (2) investigate the geometric factors that affect tunnel collision secondary to drill orientation of the ALL femoral tunnel. METHODS: A three-dimensional femoral model of patients who underwent anatomical single-bundle ACL reconstruction between 2015 and 2016 was constructed, and the geometric factors were evaluated. Virtual ALL femoral tunnels were created to simulate 45 drilling conditions. For each condition, whether the virtual ALL femoral tunnel and its trajectory violated the femoral cortex and the minimum distance between tunnels was investigated. RESULTS: Thirty-nine subjects were included. Overall violation rates of the femoral cortex by the ALL tunnels and its trajectories were 11.1% (195 of 1755 conditions) and 40.7% (714 of 1755 conditions), respectively. A drilling angle of axial 0° and coronal - 40° showed the longest minimum distance between tunnels without femoral cortex violation by the ALL tunnel (6.3 ± 4.0 mm; collision rate 2.6% [1 of 39 subjects]). With simultaneous consideration of the ALL tunnel's trajectory representing far-cortex drilling, a drill angle of axial 40° and coronal 10° showed the longest minimum distance between tunnels without femoral cortex violation (0.6 ± 3.9 mm; collision rate 38.5% [15 of 39 subjects]). For surgical techniques requiring far-cortex drilling, regression analyses were performed on geometric factors that could affect tunnel collision, which revealed that the sagittal inclination angle of the ACL and the distance between the ACL femoral tunnel's outlet and ALL's femoral attachment were associated with tunnel collision. CONCLUSION: The optimal drill orientations of the ALL femoral tunnel to minimize collision with the ACL femoral tunnel were axial 0° and coronal - 40° for surgical techniques not requiring far-cortex drilling and axial 40° and coronal 10° for techniques requiring far-cortex drilling. For techniques requiring far-cortex drilling, additional adjustment for orientation of the ACL femoral tunnel is required to reduce the risk of tunnel collision. Therefore, an individualized surgical strategy should be applied according to the graft fixation method of the ALL femoral tunnel.

Graft isometry during anatomical ACL reconstruction has little effect on surgical outcomes.

PURPOSE: To investigate the surgical outcomes of anatomical anterior cruciate ligament (ACL) reconstruction according to the graft isometry measured during surgery. METHODS: Electrical medical records of patients who underwent an arthroscopic ACL reconstruction through the transportal technique using hamstring tendon autograft between 2012 and 2016 were retrospectively reviewed. The patients were classified into two groups based on the graft length change throughout the knee range of motion measured just before graft fixation (Group 1, graft length change ≤ 2 mm; Group 2, graft length change > 2 mm). Comparative analyses, including a non-inferiority trial, were performed regarding the clinical scores, knee laxity, and radiographic parameters between the groups. RESULTS: A total of 67 patients were included in the study. The total change in the length of ACL graft throughout the knee range of motion was 1.4 ± 0.4 mm in Group 1 (range, 0.2-2.0 mm), and 3.0 ± 0.7 mm in Group 2 (range, 2.2-5.0 mm). Group 1 showed a relatively high (proximal) femoral tunnel and shallow (anterior) tibial tunnel compared to Group 2 (P < 0.001 and P = 0.028, respectively), but there were no apparent differences in the macroscopic view. There were no statistically significant differences in the clinical outcomes between groups at 2 years after surgery, which satisfied the non-inferiority criterion of Group 1 in terms of clinical scores and knee laxity compared to Group 2. CONCLUSION: The surgical outcomes of anatomical ACL reconstruction in patients with non-isometric ACL graft were not inferior in terms of clinical scores and knee laxity, compared to those with nearly-isometric ACL graft. The graft tunnel placement in the isometric position during anatomical ACL reconstruction, which is technically challenging in the clinical setting, is not a crucial factor in terms of clinical outcomes. LEVEL OF EVIDENCE: Level IV.

The Graft Insertion Length in the Femoral Tunnel During Anterior Cruciate Ligament Reconstruction With Suspensory Fixation and Tibialis Anterior Allograft Does Not Affect Surgical Outcomes but Is Negatively Correlated With Tunnel Widening.

PURPOSE: To investigate the surgical outcomes of anterior cruciate ligament (ACL) reconstruction using a low-dose irradiated tibialis anterior allograft with a fixed-loop cortical suspension device for the femur based on the graft insertion length (GIL) in the femoral tunnel. METHODS: Between January 2010 and January 2018, the medical records of consecutive patients who underwent arthroscopic ACL reconstruction with a tibialis anterior allograft fixed with the EndoButton CL for the femur and who had at least 2 years of follow-up were retrospectively evaluated. Patients were classified into 3 groups based on the GIL in the femoral tunnel (group 1, GIL < 15 mm; group 2, GIL of 15-20 mm; and group 3, GIL > 20 mm), and their functional scores, knee laxity, and radiographic parameters were evaluated. RESULTS: A total of 91 patients were analyzed. There were no statistically significant differences in the functional scores and knee laxity between the 3 groups at 2 years postoperatively. However, significant differences were observed in tunnel widening at 1 year postoperatively in the femur (P = .045 for absolute value and P = .004 for relative value) and the tibia (P = .014 for absolute value and P = .012 for relative value), revealing that both the femoral and tibial tunnels widened as the GIL decreased. Additional linear regression analyses were performed to identify whether the GIL independently affects tunnel widening. Consequently, the femoral tunnel depth, tunnel diameter, and GIL were found to independently influence femoral tunnel widening (P = .008, P = .019, and P < .001, respectively), whereas the tunnel diameter and GIL affected tibial tunnel widening (P < .001 and P = .004, respectively). CONCLUSIONS: The GIL in the femoral tunnel during ACL reconstruction using a tibialis anterior allograft with a fixed-loop cortical suspension device for the femur has no significant association with the postoperative functional outcomes and knee laxity, but it has a negative correlation with tunnel widening in the femur and the tibia. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

An Increase in Medial Joint Space Width After Medial Open-Wedge High Tibial Osteotomy Is Associated With an Increase in the Postoperative Weight-Bearing Line Ratio Rather Than With Cartilage Regeneration: Comparative Analysis of Patients Who Underwent Second-Look Arthroscopic Assessment.

PURPOSE: To investigate relevant factors influencing increases in medial joint space width (JSW) after medial open-wedge high tibial osteotomy (MOWHTO). METHODS: Between January 2010 and December 2018, the electronic medical records of consecutive patients who underwent MOWHTO and subsequent second-look arthroscopic assessment at least 12 months after MOWHTO were retrospectively evaluated. The patients were classified into 2 groups according to changes in the medial JSW of the knee at the time of the second-look operation compared with that at baseline before the initial surgical procedure. Various radiographic parameters, arthroscopic findings, and clinical scores were compared between the groups, and regression analysis was performed to identify factors related to increases in medial JSW. RESULTS: A total of 114 patients were analyzed. In a bivariate analysis, patients who experienced an increase in medial JSW showed a significantly higher postoperative weight-bearing line ratio (WBLR) (P = .008) and a greater proportion of severe preoperative cartilage lesions in the medial compartment of the knee compared with patients with a maintained or reduced medial JSW (P = .035). In terms of clinical scores, patients with an increased medial JSW showed relatively favorable clinical outcomes at the time of the second-look operation. Regression analysis indicated only postoperative WBLR as a relevant factor associated with an increase in medial JSW after MOWHTO (odds ratio, 1.057; P = .01). Additional analysis with patients reclassified according to the postoperative WBLR showed that as the postoperative WBLR increased, the medial JSW increased, without a significant change in the lateral JSW. CONCLUSIONS: An increase in the medial JSW of the knee joint after MOWHTO appears to be associated with an increase in the postoperative WBLR, not with cartilage regeneration. Obtaining adequate correction so that the postoperative WBLR is within 60% to 70% would be desirable in terms of postoperative changes in the medial JSW, as well as clinical outcomes. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

The effect of knee joint rotation in the sagittal and axial plane on the measurement accuracy of coronal alignment of the lower limb.

BACKGROUND: Although the measurement of coronal alignment of the lower limb on conventional full-length weight-bearing anteroposterior (FLWAP) radiographs was reported to be influenced by the knee joint rotation, no comparative analysis was performed considering the effects of knee joint rotation on the sagittal and axial planes simultaneously using the three-dimensional images while taking into account the actual weight-bearing conditions. The aim of this study was to investigate the effect of knee joint rotation on the measurement accuracy of coronal alignment of the lower limb on the FLWAP radiograph. METHODS: Radiographic images of 90 consecutive patients (180 lower limbs) who took both the FLWAP radiograph and the EOS image were retrospectively reviewed. The relationship among delta values of mechanical tibiofemoral angle (mTFA) between the FLWAP radiographs and the EOS images (ΔmTFA), knee flexion/extension angle (sagittal plane rotation) on the EOS images, and patellar rotation (axial plane rotation) on the FLWAP radiographs were analyzed. Further, subgroup analysis according to each direction of knee joint rotation was performed. RESULTS: There was a significant correlation between ΔmTFA and sagittal plane rotation (r = 0.368, P <  0.001), whereas axial plane rotation was not correlated. In the analysis according to the direction, statistically significant correlation was observed only in the knee flexion group (r = 0.399, P <  0.001). The regression analysis showed a significant linear relationship between ΔmTFA and sagittal plane rotation (r2 = 0.136, P <  0.001). Additional subgroup analysis in patients with the patellar rotation greater than 3% showed a similar result of a linear relationship between ΔmTFA and sagittal plane rotation (r2 = 0.257, P <  0.001), whereas no statistically significant relationship was found in patients with the patellar rotation less than 3%. CONCLUSION: The measurement accuracy of coronal alignment of the lower limb on the FLWAP radiographs would be influenced by knee flexion, specifically when there is any subtle rotation of the knee joint in the axial plane. A strict patellar forward position without axial plane rotation of the knee could provide accurate results of the measurement even if there is a fixed flexion contracture of the knee.

Adequate protection rather than knee flexion prevents popliteal vascular injury during high tibial osteotomy: analysis of three-dimensional knee models in relation to knee flexion and osteotomy techniques.

PURPOSE: (1) To analyse popliteal artery (PA) movement in a three-dimensional (3D) coordinate system in relation to knee flexion and high tibial osteotomy (HTO) techniques (lateral closed wedge HTO [LCHTO], uniplane medial open wedge HTO [UP-MOHTO], biplane medial open wedge HTO [BP-MOHTO]) and (2) to identify safe zones of the PA in each osteotomy plane. METHODS: Sixteen knees of patients who underwent magnetic resonance imaging with extension and 90° flexion were used to develop subject-specific 3D knee flexion models. Displacement of the PA during knee flexion was measured along the X- and Y-axis, as was the distance between the posterior tibial cortex and PA parallel to the Y-axis (d-PCA). Frontal plane safety index (FPSI) and maximal axial safe angles (MASA) of osteotomy, which represented safe zones for the osteotomy from the PA injury, were analysed. All measurements were performed along virtual osteotomy planes. Differences among the three osteotomy methods were analysed for each flexion angle using a linear mixed model. RESULTS: The average increments in d-PCA during knee flexion were 1.3 ± 2.3 mm in LCHTO (n.s.), 1.4 ± 1.2 mm in UP-MOHTO (P < 0.0001), and 1.7 ± 2.0 mm in BP-MOHTO (P = 0.015). The mean FPSIs in knee extension were 37.6 ± 5.9%, 46.4 ± 5.8%, and 45.1 ± 8.1% for LCHTO, UP-MOHTO, and BP-MOHTO, respectively. The mean MASA values in knee extension were 45.8° ± 4.4°, 37.3° ± 6.1°, and 38.9° ± 6.5° for LCHTO, UP-MOHTO, and BP-MOHTO, respectively. CONCLUSION: Although the PA moved posteriorly during knee flexion, the small (1.7 mm) increment thereof and inconsistent movements in subjects would not be of clinical relevance to PA safety during HTO. LEVEL OF EVIDENCE: Diagnostic study, Level II.

Arthroscopic gel-type autologous chondrocyte implantation presents histologic evidence of regenerating hyaline-like cartilage in the knee with articular cartilage defect.

PURPOSE: To investigate the clinical, radiological, and histological results of arthroscopic gel-type autologous chondrocyte implantation (GACI) in treating chondral defects of the knee. METHODS: This study prospectively examined five males and five females with a mean age of 40.3 ± 10.3 years who underwent arthroscopic GACI between March 2012 and February 2013. The gel comprised a mixture of 1 ml of fibrinogen plus 0.1-0.2 ml of thrombin. The mean size of chondral defect was 2.9 ± 1.2 cm2 (range 1.2-5.4 cm2). International knee documentation committee (IKDC) subjective score, knee injury and osteoarthritis outcome score (KOOS), knee society score, and visual analog scale (VAS) for pain were assessed preoperatively and during regular follow-up examinations performed for up to 5 years postoperatively. Serial magnetic resonance imaging was performed for up to 2 years after the surgery to observe healing, using the modified magnetic resonance observation of cartilage repair tissue (MOCART) score. In eight patients, second-look arthroscopy was performed at 1 year after the implantation to assess the status of treated cartilage, and a portion of regenerated cartilage was harvested for histologic evaluation. RESULTS: The mean VAS score (p = 0.045), IKDC subjective score (p = 0.041), KOOS pain (p = 0.025), KOOS activities of daily living (p = 0.048), and KOOS quality of life (p = 0.029) showed significant improvement at 5 years after the surgery. The modified MOCART evaluation showed that the scores were 59.5 ± 29.4 and 85.0 ± 8.0 at 12 weeks and 2 years after the operation, respectively. Histologic examination demonstrated a mean regenerated cartilage thickness of 3.5 ± 0.8 mm and a mean Oswestry score of 8.2 ± 1.8. Immunohistochemistry analysis showed that the expression of collagen type II was more evident and more evenly distributed than collagen type I in regenerated cartilage. There was a significant correlation between Oswestry score and change in VAS scale from postoperative 2-5 years. CONCLUSIONS: Arthroscopic GACI produces satisfactory clinical and radiologic outcomes, and histologic evaluation confirms sufficient regeneration of hyaline-like cartilage that correlates with improved symptoms. Therefore, it is an acceptable, minimally invasive, and technically simple option for the restoration of cartilage defects of the knee. LEVEL OF EVIDENCE: IV.

Does Knee Flexion Influence the Relationship between the Femoral Tunnel and the Lateral Anatomic Structures During ACL Reconstruction?

BACKGROUND: In ACL reconstruction, the relationship of the femoral tunnel outlet to the anatomy of the lateral knee is clinically important, but whether that relationship is influenced by knee flexion using a transportal technique is unclear. QUESTIONS/PURPOSES: The purposes of this study were to (1) to describe the relationship between the outlet of the femoral tunnel and the lateral anatomic structures of the femur, including the lateral epicondyle, lateral collateral ligament, popliteus tendon, and lateral head of the gastrocnemius, as a function of knee flexion angle when the tunnel was created; and (2) to determine the knee flexion range of angles that best limits the risk of damage to these structures as the femoral tunnel is created during anatomic single-bundle ACL reconstruction using the transportal technique. METHODS: Between January 2017 and June 2018, 113 patients underwent ACL reconstruction, of which 62 (55%) who had a primary single-bundle ACL reconstruction with transportal technique using autogenous quadruple hamstring graft were included. Patients who were treated with grafts other than autogenous quadruple hamstring tendon, and had concomitant ligamentous injury, revisional ACL reconstruction, previous operative history of the affected knee, osseous deformity and osteoarthritis were excluded. Included patients were divided into three groups according to their knee flexion angles as the femoral tunnel was created. The femoral tunnel was created with rigid straight reamer with the knee flexed as much as possible in figure-of-four position and the flexion angle was measured with a sterile 12-inch goniometer intraoperatively for all patients. Fourteen patients (23%) had the femoral tunnel created with the knee in < 120° of flexion, 23 (37%) had the tunnel created in 120° to 129° of flexion, and 25 (40%) had the tunnel created in ≥ 130° of flexion. The femoral tunnel's outlet and the lateral anatomic structures of the femur, including the femoral origins of the lateral epicondyle, lateral collateral ligament, popliteus tendon, and lateral head of the gastrocnemius, were identified on a three-dimensional model that was reconstructed using CT images taken on postoperative day 1. The shortest distances from the femoral tunnel's outlet to these lateral anatomic structures were measured by two observers and interobserver reliability was high (intraclass correlation coefficient > 0.75). The distances were compared among the groups, and a correlation analysis of the measured distances regarding the knee flexion angle during creation of the femoral tunnel was performed. The safe distance was set as 12 mm between the centers of the femoral tunnel's outlet and the lateral structures considering the footprint of the lateral structures, diameter of the femoral tunnel, and femoral tunnel widening. Any anatomic structures that were closer to the femoral tunnel than the safe distance were noted, and the cutoff point of knee flexion for injury to the lateral anatomic structures was determined with a receiver operating characteristic curve. RESULTS: As knee flexion angle increased, the distance from the femoral tunnel to the lateral head of the gastrocnemius increased (r = 0.657, p < 0.001), and the distance to the lateral epicondyle decreased (r = -0.627, p < 0.001), as did the distance of the tunnel to the lateral collateral ligament (r = -0.443, p < 0.001) and the popliteus tendon (r = -0.653, p < 0.001). The cutoff point of the knee flexion angle associated with structural injury was 131° (sensitivity, 70%; specificity, 73%) for the lateral collateral ligament and 121° (sensitivity, 86%; specificity, 67%) for the lateral head of the gastrocnemius. CONCLUSIONS: As knee flexion increased, the femoral tunnel's outlet tended to move more anteriorly and distally. Consequently, the safe distance to the lateral head of the gastrocnemius increased and the distances to the lateral epicondyle, lateral collateral ligament, and popliteus tendon decreased with increased knee flexion. To avoid possible damage to the lateral anatomic structures and obtain stable fixation in ACL reconstruction using the transportal technique, we recommend creating a femoral tunnel within 121° and 131° of knee flexion. LEVEL OF EVIDENCE: Level III, therapeutic study.

The effect of medial open wedge high tibial osteotomy on the patellofemoral joint: comparative analysis according to the preexisting cartilage status.

BACKGROUND: Although it has been known that medial open wedge high tibial osteotomy (MOWHTO) would adversely affect the patellofemoral joint, no previous study examined the surgical outcome of MOWHTO according to the preexisting cartilage status of the patellofemoral joint. The aim of this study was to investigate the effect of MOWHTO on the patellofemoral joint with regard to objective and subjective aspects according to the preexisting cartilage status. METHODS: Ninety-two patients who underwent MOWHTO and a following second-look arthroscopic assessment were included in this study. The patients were divided into two groups according to the preexisting cartilage status of the patellofemoral joint: group 1 (International Cartilage Repair Society [ICRS] grade 2 or 3) and group 2 (ICRS grade 0 or 1). Comparative analysis was performed regarding clinical scores, radiographic parameters, and arthroscopic measurements between the two groups. RESULTS: Clinical outcomes showed overall improvement from baseline to the time of second-look operation, with no significant difference between the two groups at each time point. There were no significant differences in radiographic parameters between the two groups. Radiographic grade of patellofemoral osteoarthritis in both groups showed a tendency to progress, without statistical significance. In arthroscopic assessment, the size of the cartilage lesion on the patellofemoral joint increased with time in both groups (P = 0.003), but the degree of change over time between the two groups was not statistically significant. Consistently, there was no significant difference in the frequency of progression of cartilage lesion grade in the patellofemoral joint between the two groups. CONCLUSIONS: MOWHTO would contribute to osteoarthritis progression of the patellofemoral joint regardless of the preexisting cartilage status, without an association with clinical outcomes in short-term follow-up.

The Fate of the Contralateral Knee in Patients With a Lateral Discoid Meniscus.

PURPOSE: To analyze the survivorship of the lateral meniscus (LM) in the contralateral knee after surgery for symptomatic torn discoid lateral meniscus (DLM) and to determine its associated factors. METHODS: Two hundred ninety-six patients who underwent arthroscopic meniscectomy for torn symptomatic DLM were reviewed retrospectively. Patients were classified into subgroups based on demographic, clinical, and radiologic variables. The survivorship analysis of the LM on the contralateral knee was calculated using the Kaplan-Meier method, and comparison among the subgroups was conducted using the log-rank test. The predicted prognostic factors associated with survivorship were determined using Cox proportional hazard regression analysis. RESULTS: Of the 296 patients, 51 (17%) had arthroscopic surgery in the contralateral knee during the study period. The group ≥40 years old had significantly worse survival than the group <40 (log-rank test, P < .001). In terms of radiologic variables, the group with Kellgren-Lawrence grade 3 or 4 had significantly poorer survivorship than that with grade 1 or 2 (log-rank test, P = .045). Age ≥40 years was associated with poorer survivorship (hazard ratio, 3.235; 95% confidence interval, 1.782-5.875; P < .001). Kellgren-Lawrence grades 3 and 4 in the contralateral knee were associated with poorer survival (hazard ratio, 2.071; 95% confidence interval, 1.061-4.043; P = .033). The cumulative survival rate at 10 years of the LM in the contralateral knee after surgery for symptomatic torn DLM was 81%. CONCLUSIONS: Patients with a lateral discoid meniscus have a risk of a similar condition in the contralateral knee. Increased risks of symptomatology are associated with age and degenerative changes. LEVEL OF EVIDENCE: Level IV, retrospective uncontrolled case series.

Intra-articular injection of steroids in the early postoperative period does not have an adverse effect on the clinical outcomes and the re-tear rate after arthroscopic rotator cuff repair.

PURPOSE: The purpose of this study was to compare clinical outcomes and structural integrity following arthroscopic rotator cuff repair, either with intra-articular injection of corticosteroids in the early postoperative period using ultrasound guidance or without it. METHODS: This study included 318 patients who underwent arthroscopic repair for either a partial-thickness or small-to-medium-sized full-thickness rotator cuff tear from 2012 to 2015. Patients were divided into two groups based on the administration of an intra-articular corticosteroids injection at 3 months after the surgery: group A (with corticosteroid injection, n = 56) and group B (without corticosteroid injection, n = 262). Functional outcomes were evaluated using the visual analog scale (VAS) pain score, subjective shoulder value (SSV), American Shoulder and Elbow Surgeons (ASES) score, University of California Los Angeles (UCLA) shoulder score, and active range of motion (ROM). Postoperative magnetic resonance arthrography (MRA) was performed 6 months postoperatively to assess structural integrity. RESULTS: At the 2-year follow-up, both groups showed no significant differences in VAS pain score (group A/B, 1.1 ± 0.9/1.1 ± 1.1), functional scores including SSV (88.5 ± 10.8/88.3 ± 10.0), ASES (90.8 ± 6.6/90.4 ± 6.9), and UCLA scores (30.2 ± 5.6/30.7 ± 5.2), and active ROM including forward flexion (151° ± 8°/153° ± 7°), external rotation (54° ± 5°/55° ± 7°), and internal rotation (10 ± 1/10 ± 2). Follow-up MRA imaging collected 6 months after surgery showed no significant difference in the re-tear rate (n.s.) between group A and B (n = 10/56, 17.9% and 45/262, 17.2%, respectively). CONCLUSIONS: Intra-articular corticosteroids injection in the early postoperative period after arthroscopic rotator cuff repair provided satisfactory pain relief and ROM improvement without increasing the re-tear rate or deteriorating clinical outcomes at the 2-year follow-up. LEVEL OF EVIDENCE: III.

An intact subscapularis tendon and compensatory teres minor hypertrophy yield lower failure rates for non-operative treatment of irreparable, massive rotator cuff tears.

PURPOSE: To investigate whether subscapularis integrity and compensatory teres, minor hypertrophy is associated with maintaining relatively good function and tolerable pain levels during non-operative treatment. METHODS: This study included 108 patients with irreparable, massive rotator cuff tears involving at least two tendons and stage III or IV muscle hypotrophy and fatty infiltration on oblique sagittal magnetic resonance imaging, in which even a partial repair does not seem feasible. All supraspinatus and infraspinatus muscles were grade IV; if the subscapularis was involved, only stage III or IV was included. Patients were divided into two groups: group A consisted of 67 patients with both an intact subscapularis and teres minor hypertrophy; group B consisted of 41 patients lacking either one or both. The Visual Analogue Scale pain score, the American Shoulder and Elbow Surgeons score, the University of California at Los Angeles shoulder score, and active range of motion (ROM) were assessed. RESULTS: During the follow-up period, failure of non-operative treatment was found in 29 (43%) patients in group A and 28 (68%) in group B (p = 0.012). Conversion to surgery was noted in 26 (39%) patients in group A and 27 (66%) in group B (p = 0.006). Among the remaining nonsurgical patients, there were no significant differences in clinical outcomes between the groups except ROM in internal rotation at final follow-up. CONCLUSIONS: Although conservative treatment was not always successful in patients with irreparable, massive cuff tears, patients with both an intact subscapularis tendon, and teres minor hypertrophy experienced significantly lower incidences of failure and conversion to surgery, since force couple is maintained in the setting of minimal arthritis. LEVEL OF EVIDENCE: III.

Attrition of rotator cuff without progression to tears during 2-5 years of conservative treatment for impingement syndrome.

PURPOSE: The purpose of this study was to investigate the natural history of intact rotator cuff in impingement syndrome patients with concomitant spur protruding from the undersurface of acromion. METHODS: This retrospective study included 119 patients with an intact rotator cuff who underwent conservative treatment for a spur protruding from the undersurface of the acromion. The protruded spur was defined as a trapezoid- or tetragon-shaped bony protrusion with a downward peak extending more than 3 mm in length from the baseline drawn along the acromial undersurface on the coronal view of magnetic resonance imaging (MRI) or computed tomography arthrography (CTA). Functional outcomes were evaluated by the visual analogue scale for pain, subjective shoulder value, American Shoulder and Elbow Surgeons score, University of California Los Angeles shoulder score, and active range of motion (ROM). To evaluate cuff integrity, follow-up MRI, CTA, or ultrasound were performed at least 2 years after the initial presentation. RESULTS: No new rotator cuff tears were noted in any patient during the follow-up imaging studies. However, 18 patients (15%) underwent arthroscopic acromioplasty during the study period. During the arthroscopic examinations, moderate to severe attrition of the cuff was identified, although no tears were seen. At the final follow-up, pain level and shoulder function, including ROM, showed satisfactory outcomes. CONCLUSION: Spurs protruding from the acromial undersurface did not lead to rotator cuff tears during 2-5 years of conservative treatment. However, attrition of the rotator cuff was found during arthroscopic acromioplasty, suggesting that the protruding spurs caused extrinsic impingement of the cuff. LEVEL OF EVIDENCE: Therapeutic case series Level IV.

Priming stem cells with protein kinase C activator enhances early stem cell-chondrocyte interaction by increasing adhesion molecules.

BACKGROUND: Osteoarthritis (OA) can be defined as degradation of articular cartilage of the joint, and is the most common degenerative disease. To regenerate the damaged cartilage, different experimental approaches including stem cell therapy have been tried. One of the major limitations of stem cell therapy is the poor post-transplantation survival of the stem cells. Anoikis, where insufficient matrix support and adhesion to extracellular matrix causes apoptotic cell death, is one of the main causes of the low post-transplantation survival rate of stem cells. Therefore, enhancing the initial interaction of the transplanted stem cells with chondrocytes could improve the therapeutic efficacy of stem cell therapy for OA. Previously, protein kinase C activator phorbol 12-myristate 13-acetate (PMA)-induced increase of mesenchymal stem cell adhesion via activation of focal adhesion kinase (FAK) has been reported. In the present study, we examine the effect PMA on the adipose-derived stem cells (ADSCs) adhesion and spreading to culture substrates, and further on the initial interaction between ADSC and chondrocytes. RESULTS: PMA treatment increased the initial adhesion of ADSC to culture substrate and cellular spreading with increased expression of adhesion molecules, such as FAK, vinculin, talin, and paxillin, at both RNA and protein level. Priming of ADSC with PMA increased the number of ADSCs attached to confluent layer of cultured chondrocytes compared to that of untreated ADSCs at early time point (4 h after seeding). CONCLUSION: Taken together, the results of this study suggest that priming ADSCs with PMA can increase the initial interaction with chondrocytes, and this proof of concept can be used to develop a non-invasive therapeutic approach for treating OA. It may also accelerate the regeneration process so that it can relieve the accompanied pain faster in OA patients. Further in vivo studies examining the therapeutic effect of PMA pretreatment of ADSCs for articular cartilage damage are required.