A Decline in Overutilization of Transfusion after Total Knee Arthroplasty Using Pharmacological Agents for Patient Blood Management in South Korea: An Analysis Based on the Korean National Health Insurance Claims Database from 2008 to 2019.

Background: This study aimed to evaluate the annual trends of transfusion rates and utilization of blood management agents in total knee arthroplasty (TKA) based on the operation type and to analyze the risk factors of transfusion after TKA. Methods: Using the Korean National Insurance claims database of 797,106 primary and revision TKAs between January 2008 and October 2019, data on the patients' characteristics, comorbidities, utilization of transfusion, and blood management agents were collected. The patients were categorized into three groups based on the operation type: primary, revision, and simultaneous bilateral TKA. The transfusion rate and utilization of blood management agents (intraoperative tranexamic acid [TXA] and preoperative iron supplements) were compared, and the risk factors for transfusion were evaluated. Results: After excluding the inaccurate data, 730,554 arthroplasties (636,292 primary, 10,540 revision, and 41,861 simultaneous bilateral TKAs) were identified. The transfusion rates of primary, revision, and simultaneous bilateral TKAs in 2019 were 64.0%, 67.7%, and 68.9%, respectively, which were significantly decreased compared with 83.2%, 88.0%, and 92.5% in 2008, respectively (p < 0.001). Conversely, the utilization of intraoperative TXA and preoperative iron supplements was significantly increased from 4.6% and 13.8%, respectively, in 2008 to 52.4% and 27.0%, respectively, in 2019 (p < 0.001). The utilization of intraoperative TXA and preoperative iron supplements significantly lowered the risk of transfusion after TKA (odds ratio [OR], 0.20; p < 0.001 and OR, 0.71; p < 0.001). Conclusions: The transfusion rate after TKA decreased gradually from 83.5% to 64.5% between 2008 and 2019 in South Korea corresponding with the increased utilization of blood management agents. Therefore, consistent attention to patient blood management should be emphasized to reduce the transfusion rate after TKA.

Functional improvement of unicompartmental knee arthroplasty compared with total knee arthroplasty for subchondral insufficiency fracture of the knee.

Subchondral insufficiency fracture of the knee (SIFK) causes acute knee pain in adults and often requires surgical management. Unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) are the two most common surgical treatments for SIFK. While both UKA and TKA have their advantages, there is no consensus for SIFK localized on the medial compartment. We hypothesized that patients with SIFK treated with UKA would show superior patient-reported outcomes compared to those who underwent TKA. A total of 90 patients with SIFK located medially were included in the TKA (n = 45) and UKA (n = 45) groups. Size of SIFK lesions were measured on MR images. Patient reported outcomes in the form of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Hospital Special Surgery (HSS) scores, and Knee Society Scores (KSS) were assessed preoperatively, postoperative 6, 12 months, and at the final follow-up. There were no differences in the size of the SIFK lesion between two groups. At 6 months, WOMAC score was better in the UKA group than the TKA group (p < .01). Both groups had a significant improvement in WOMAC, HSS, and KSS scores at the final follow-up compared to preoperative scores. The UKA group had better range of motion of the knee preoperatively and postoperatively than the TKA group (p < .01 and p < .01). UKA group showed a higher relative risk than the TKA group in terms of complications (RR = 3.0) but with no statistical significance (P = 0.31). Unicompartmental arthroplasty and total joint arthroplasty can produce successful outcomes in patients with SIFK with proper patient selection, regardless of the size of SIFK lesion.

Age alone does not affect the joint survivorship after arthroscopic partial meniscectomy for degenerative medial meniscus tears: a propensity-score matched survival analysis.

PURPOSE: To evaluate the effect of age itself on the joint survivorship after arthroscopic partial meniscectomy (APM) for degenerative medial meniscus tears (DMTs). METHODS: Patients undergoing APM for DMTs during 1999-2010 were retrospectively reviewed. The inclusion criteria were as follows: (1) DMTs identified on preoperative MRI scans, (2) no definite history of trauma, and (3) follow-up duration more than 5 years. In evaluation of the joint survivorship, the endpoint was defined as conversion to arthroplasty (or realignment osteotomy) or progression to Kellgren-Lawrence grade 4. The study population was divided into older and younger groups by a cutoff age at which the difference in the joint survival rates was maximized, using a time-dependent receiver operating characteristic (ROC) curve. The two groups were then matched based on propensity scores. The joint survival rates were compared between the groups using Kaplan-Meier analysis, before and after propensity score matching (PSM). RESULTS: A total of 633 knees were included. The cutoff age was calculated as 60 years. Before PSM, 239 knees were allocated to the older group (≥ 60 years) and 394 knees to the younger group (< 60 years). A significant difference in the joint survival rates was noted between the groups (log-rank test, p < 0.001). After PSM, 183 knees remained in each group. The difference in the survival rates was no more statistically significant (n.s.). The latest Lysholm scores of the older and the younger groups before PSM were 72.2 ± 20.8 and 79.9 ± 19.6, respectively (p < 0.001); however, the scores after PSM were 73.2 ± 20.3 and 77.4 ± 20.5, respectively (n.s.). CONCLUSIONS: Joint survivorship after APM was affected by other factors associated with the aging process, such as cartilage status and meniscal tear pattern, rather than age itself. Advanced age should not be the only reason for precluding APM in treatment of DMTs. APM is a viable option when treating DMTs in elderly patients if adopted with caution. According to this study, a surgeon should assess the age-related factors when he considers APM in elderly patients. LEVEL OF EVIDENCE: III.

Risk Factors for Increase in Posterior Slope After Medial Open-Wedge High Tibial Osteotomy.

Background: Whether lateral hinge fracture (LHF) after open-wedge high tibial osteotomy (OWHTO) is associated with the change in tibial posterior slope (PS) has not been determined. Risk factors for PS increase are still unknown. Hypothesis: There will be no difference in patient characteristics and radiographic factors when stratified by change in tibial PS (ΔPS). Study Design: Cohort study; Level of evidence, 3. Methods: We reviewed the records of 148 patients who underwent OWHTO with locking-plate fixation from 2010 to 2016. Included were those with a minimum 2-year follow-up and true lateral radiographs before and at 1 year after surgery. ΔPS was defined as a difference between preoperative and 1-year postoperative PS, with positive values indicating PS increase. ΔPS was classified into <3°, 3° to <6°, and ≥6°. Any LHFs were grouped by Takeuchi classification as stable (type 1) or unstable (types 2 and 3). Risk factors for PS increase were evaluated using ordinal logistic regression analyses. Clinical outcomes according to ΔPS were evaluated using the Hospital for Special Surgery score. Results: There were 79 (53.4%) patients with ΔPS <3°, 44 (29.7%) with 3° ≤ ΔPS < 6°, and 25 (16.9%) with ΔPS ≥6°. LHFs were observed in 41 (27.7%) patients: 32 with type 1 and 7 and 2 with types 2 and 3, respectively. Results of the multivariate ordinal logistic regression analysis indicated that ΔPS was associated with unstable LHF (P = .005, exp[ß] = 6.34), preoperative PS (P = .028, exp[ß] = 0.90), and correction angle (P = .037, exp[ß] = 1.09). ΔPS ≥6° was seen in 4 of 9 (44.4%) patients with unstable LHF, 9 of 32 (28.1%) with stable LHF, and 12 of 107 (11.2%) with no LHF (P = .017). The mean correction angle was 11.3° ± 3.6° in patients with ΔPS ≥6°, 9.4° ± 4.6° in cases of 3° ≤ ΔPS < 6°, and 8.8° ± 3.6° in cases of ΔPS <3° (P = .019). Hospital for Special Surgery scores did not differ according to ΔPS. Conclusion: LHF type and correction angle were associated with ΔPS after OWHTO, and unstable LHF and large correction angle were risk factors for PS increase. There was no significant difference in clinical outcomes according to ΔPS.

Anatomy of the anterolateral ligament of the knee joint.

Despite remarkable improvements in clinical outcomes after anterior cruciate ligament reconstruction, the residual rotational instability of knee joints remains a major concern. The anterolateral ligament (ALL) has recently gained attention as a distinct ligamentous structure on the anterolateral aspect of the knee joint. Numerous studies investigated the anatomy, function, and biomechanics of ALL to establish its potential role as a stabilizer for anterolateral rotational instability. However, controversies regarding its existence, prevalence, and femoral and tibial insertions need to be addressed. According to a recent consensus, ALL exists as a distinct ligamentous structure on the anterolateral aspect of the knee joint, with some anatomic variations. The aim of this article was to review the updated anatomy of ALL and present the most accepted findings among the existing controversies. Generally, ALL originates slightly proximal and posterior to the lateral epicondyle of the distal femur and has an anteroinferior course toward the tibial insertion between the tip of the fibular head and Gerdy's tubercle below the lateral tibial plateau.

Anatomy, Biomechanics, and Reconstruction of the Anterolateral Ligament of the Knee Joint.

Despite remarkable advances in the clinical outcomes after anterior cruciate ligament reconstructions (ACLRs), residual rotational instability of the knee joint remains a major concern. Since the anterolateral ligament (ALL) on the knee joint has been "rediscovered", the role of anterolateral structures, including ALL and deep iliotibial band, as secondary stabilizers of anterolateral rotatory instability has gained interest. This interest has led to the resurgence of anterolateral procedures combined with ACLRs to restore rotational stability in patients with anterior cruciate ligament (ACL) deficiencies. However, the difference in concepts between anterolateral ligament reconstructions (ALLRs) as anatomical reconstruction and lateral extra-articular tenodesis (LETs) as non-anatomical reinforcement has been conflicting in present literature. This study aimed to review the anatomy and biomechanics of anterolateral structures, surgical techniques, and the clinical outcomes of anterolateral procedures, including LET and ALLR, in patients with ACL deficiencies.

Association of Preoperative Tibial Varus Deformity With Joint Line Orientation and Clinical Outcome After Open-Wedge High Tibial Osteotomy for Medial Compartment Osteoarthritis: A Propensity Score-Matched Analysis.

BACKGROUND: The correction of lower limb deformity should be performed at the site of deformity to maintain knee joint orientation. However, the effectiveness of open-wedge high tibial osteotomy (OWHTO) for treatment of medial osteoarthritis in varus malalignment without definite tibial varus deformity has not been confirmed. PURPOSE/HYPOTHESIS: This study aimed to compare the clinical and radiologic outcomes after OWHTO in patients without tibial varus deformity versus patients with tibial varus deformity after matching for confounding factors. We hypothesized that these outcomes would be inferior in patients without tibial varus deformity. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: The outcomes of 133 OWHTO operations for medial osteoarthritis in 107 patients were retrospectively reviewed after follow-up for >2 years. The patients were divided into group 1 (tibia with varus deformity, preoperative medial proximal tibial angle [MPTA] <85°) and group 2 (tibia without varus deformity, preoperative MPTA ≥85°). The confounding factors, including patient characteristics, preoperative limb alignment, degree of osteoarthritis, and correction angle, were matched using propensity score matching. The radiologic parameters, including MPTA and joint line obliquity, were evaluated preoperatively, between 6 and 12 months postoperatively, and at the last follow-up. The radiologic outcomes were assessed using the medial joint space width and mechanical hip-knee-ankle angle. The clinical outcomes were evaluated by the Hospital for Special Surgery knee score, Knee Society Score (KSS), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score. The clinical and radiologic outcomes were compared between the groups. The proportions of patients achieving improvement in the clinical outcome beyond the minimal clinically important difference (MCID) or minimally important change were compared between the groups. RESULTS: After propensity score matching, 32 patients were selected for each group. The mechanical hip-knee-ankle angle was corrected without significant difference from a mean ± SD varus angle of 8.0°± 3.3° to valgus angle of -3.2°± 2.5° in group 1 and from varus 8.0°± 3.6° to valgus -3.9°± 1.7° in group 2. The preoperative joint line obliquity was greater in group 2 as compared with group 1 (2.2°± 2.2° vs -0.4°± 1.8°, P < .001). With a similar 10° correction angle, the postoperative MPTA and joint line obliquity were 96.6°± 2.5° and 5.3°± 2.3°, respectively, in group 2, which were greater than 94.0°± 2.6° and 3.5°± 1.8°, respectively, in group 1 (both P < .001). The changes in joint space width and mechanical hip-knee-ankle angle were not significantly different between the groups over the follow-up period. At the last follow-up, the postoperative KSS objective score and WOMAC pain score in terms of symptom improvement were not significantly different between groups (P = .092 and .068). However, the postoperative KSS and WOMAC functional scores were significantly worse in group 2 than in group 1 (77.3 ± 14.1 vs 84.4 ± 11.6, P = .044; 10.3 ± 9.2 vs 5.6 ± 7.2, P = .001). In group 1, 96.9% and 100% of patients showed improvements of >10 points in the KSS functional score and 15 points in the WOMAC functional score based on MCID or minimally important change. Meanwhile, 65.6% and 81.3% of patients in group 2, which were significantly lower than those of group 1, were improved beyond the MCID or minimally important change (P = .001 and .024, respectively). CONCLUSION: In varus malalignment, the knee joint line was more oblique in patients without tibial varus deformity after OWHTO pre- and postoperatively. The clinical outcomes in terms of functional scores were inferior in patients without tibial varus deformity. However, the radiologic outcomes and symptomatic improvement after OWHTO were comparable regardless of the preoperative tibial varus deformity on midterm follow-up.

Increased MRI Signal Intensity of Allografts in the Midterm Period After Meniscal Allograft Transplant: An Evaluation of Clinical Significance According to Location and Morphology.

BACKGROUND: Magnetic resonance imaging (MRI) is an effective tool for objective evaluation after meniscal allograft transplant (MAT). Little is known about the association between MRI features of allograft and clinical outcomes. PURPOSE/HYPOTHESIS: To assess the degree and location of signal intensity (SI) as well as the morphology of allografts on MRI after MAT and evaluate the association between clinical outcomes and MRI features in the midterm period. It was hypothesized that a high SI accompanied by a deformed allograft in specific locations on MRI would be associated with inferior clinical outcomes. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Included were patients who underwent MAT with fresh-frozen allografts and had >3 years of follow-up with 3.0-T MRI scans. Allograft status was assessed by SI on MRI as grade 0 (normal), grade 1 (globular increased SI not adjacent to the articular surface), grade 2 (linear SI within the meniscus), or grade 3 (increased SI extended to the articular surface). Allograft morphology was assessed by the presence of distorted contours. Clinical outcomes were evaluated using the Lysholm score. The association between clinical outcomes and MRI findings was assessed by multiple linear regression analysis. RESULTS: A total of 138 patients (156 MAT procedures: 132 lateral, 24 medial) with a mean follow-up period of 55.4 ± 19.9 months (range, 36-110 months) were enrolled in this study. Grade 3 SI was observed in the posterior meniscus root and posterior third of the allograft in 39 (25%) and 62 (39.7%) MATs, respectively. Among the 62 MATs with grade 3 SI in the posterior third of the allograft, 34 (54.8%) were accompanied by distorted allograft contour. The presence of grade 3 SI with distorted contour in the posterior third of the allograft was significantly associated with inferior outcomes (ß = -6.5 [95% CI, -12.5 to -0.5]; P < .035), as was the presence of grade 3 SI in the posterior meniscus root (ß = -5.5 [95% CI, -10.5 to -0.4]; P < .034). CONCLUSION: On MRI evaluation in the midterm period after MAT, grade 3 SIs of the meniscal allograft were observed in about a third of the cases, and the association with clinical outcomes was dependent on the specific location and morphology of the allograft on MRI.

Using the Lower Limb Adduction Angle to Predict Postoperative Knee Joint-Line Obliquity After Open-Wedge High Tibial Osteotomy.

BACKGROUND: Knee joint-line orientation is altered after open-wedge high tibial osteotomy (OWHTO), and excessive joint-line obliquity (JLO) can adversely affect outcomes. Little is known regarding preoperative prediction of postoperative knee JLO. PURPOSE/HYPOTHESIS: The purpose of this study was to assess the correlation between the amount of lower limb adduction and changes in knee JLO after OWHTO. The hypothesis was that postoperative knee JLO could be predicted using the amount of lower limb adduction after OWHTO. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: The records of 67 patients (77 knees) who underwent OWHTO for medial compartment osteoarthritis were retrospectively reviewed. The mechanical hip-knee-ankle (HKA) axis, lateral distal femoral angle, medial proximal tibial angle (MPTA), knee JLO, ankle JLO, and joint-line convergence angle were measured on standing whole-leg plain radiographs preoperatively and at 1 year postoperatively. The limb adduction angle was defined as the angle between the native weightbearing line (WBL) and the planned WBL on preoperative standing whole-leg plain radiographs. The predicted knee JLO was calculated as the sum of the preoperative knee JLO and the limb adduction angle. Multivariable linear regression analysis was used to identify the preoperative radiologic factors associated with the postoperative knee JLO. The agreement between postoperative and predicted values was determined using intraclass correlation coefficients (ICCs). RESULTS: The estimated limb adduction angle was 4.2° ± 1.3°, and the predicted knee JLO was 4.9° ± 3.0°. The actual postoperative knee JLO was 4.5° ± 2.4°, which was a significant increase from 0.7° ± 2.4° preoperatively (P < .001). Excellent agreement was found between the predicted knee JLO and postoperative knee JLO (ICC = 0.928; P < .001). Limb adduction angle and changes in preoperative MPTA were significantly associated with changes in knee JLO (P < .001). On multivariable linear regression analysis, preoperative knee JLO and limb adduction angle were significantly associated with postoperative knee JLO (P < .001; R 2 = 0.83). CONCLUSION: Changes in knee JLO after OWHTO were associated with adduction of the lower limb after OWHTO. During preoperative planning, postoperative knee JLO can be predicted as the sum of the preoperative knee JLO and the limb adduction angle between the preoperative WBL and planned WBL.

Meniscal Deficiency Period and High Body Mass Index Are Preoperative Risk Factors for Joint Space Narrowing After Meniscal Allograft Transplantation.

BACKGROUND: Several studies have reported further reduction in joint space width (JSW) after meniscal allograft transplantation; some contributing postoperative factors are known, although preoperative factors remain unclear. This study is the first to analyze the preoperative risk factors for reduced JSW in patients after lateral meniscal allograft transplantation (LMAT). HYPOTHESIS: Poor cartilage status and high preoperative body mass index (BMI) influence the postoperative progression of joint space narrowing. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: We retrospectively studied 79 patients after LMAT who were observed for at least 5 years. JSWs on weightbearing flexion posteroanterior radiographs were measured preoperatively and at the 5-year mark. Differences in JSW were divided into more progression and less progression groups. The modified Outerbridge cartilage grades based on magnetic resonance imaging assessments were compared at subtotal/total meniscectomy and at LMAT to determine the difference between time points. Preoperative between-group differences in sex, age, surgical side, follow-up period, weight, height, BMI, and meniscal deficiency period were analyzed. Clinical outcomes were evaluated using the Lysholm score. Data were examined using univariate and multivariate logistic regressions. RESULTS: Radiographically, the overall change in JSW from preoperative to follow-up was 0.58 mm (range, -0.23 to 1.83 mm). Reductions in JSW in the more progression and less progression groups were 0.94 ± 0.32 and 0.22 ± 0.21 mm (mean ± SD), respectively. There was no difference in cartilage status between the groups at meniscectomy or LMAT; however, changes between time points were significant on the lateral femoral condyle and lateral tibial plateau. Clinically, there were significant differences in weight, BMI, and meniscal deficiency period between the 2 groups. Postoperative Lysholm scores increased as compared with the preoperative scores, but there was no difference among the postoperative time points. In the univariate logistic regression risk analysis, weight, BMI, meniscal deficiency period, and the difference in cartilage status between time points for the lateral femoral condyle and lateral tibial plateau were identified as significant. In the subsequent multivariate logistic regression, BMI (odds ratio, 1.45; P = .016) and meniscal deficiency period (odds ratio, 1.21; P = .037) were the statistically significant factors. CONCLUSION: BMI and meniscal deficiency period were preoperative risk factors for JSW narrowing after LMAT. This suggests that the meniscal deficiency period from meniscectomy to LMAT may be shortened and that proper weight management can lead to successful LMAT.

Extrusions do not affect degenerative morphologic changes in lateral meniscus allografts during midterm follow-ups.

PURPOSE: To investigate degenerative morphological changes in meniscus allograft after lateral meniscus allograft transplantation (MAT) based on extrusions. METHODS: Ninety-one patients who underwent lateral MAT were divided into extruded and non-extruded groups. Serial magnetic resonance imaging scans obtained 6 weeks, 1 year, and at the last follow-up (midterm, 3-7 years) post-surgery were evaluated retrospectively. Degenerative morphological changes at each time point in each group were compared using the postoperative meniscal width, thickness, and intrameniscal signal intensity (IMSI) at the anterior horn, mid-body, and posterior horn. The Lysholm scores and meniscal tears based on graft extrusion were also investigated. RESULTS: The mean age was 33.7 ± 11.1 years (64 men and 27 women). Fifty-three (58%) and 38 knees (42%) were classified into the non-extruded and extruded groups, respectively. The overall meniscal width of the mid-body decreased from 9.6 ± 1.3 to 6.5 ± 1.2 mm (p < 0.01), and IMSI of mid-body was increased from 1.2 ± 0.1 to 1.7 ± 0.1 (p < 0.01) during midterm follow-ups. No significant differences were observed between the meniscal width, thickness, and IMSI at the anterior horn (n.s.), mid-body (n.s.), and posterior horn (n.s.) of the two groups during the midterm follow-ups. The incidence of meniscus tears and Lysholm scores did not differ significantly between the groups during midterm follow-ups. CONCLUSION: The overall meniscus width of mid-body decreased while the relative IMSI of mid-body increased during midterm follow-ups after lateral MAT. Meniscal allograft extrusions did not influence postoperative changes in meniscus width, thickness, and relative intrameniscal signal intensity. LEVEL OF EVIDENCE: Level III.

Large chondral defect not covered by meniscal allograft is associated with inferior graft survivorship after lateral meniscal allograft transplantation.

PURPOSE: This study aimed to evaluate graft survivorship according to the size and location of chondral defects and its effect on clinical outcomes after meniscal allograft transplantation (MAT). It was hypothesized that large chondral defects would be associated with inferior outcomes. METHODS: Patients who underwent lateral MAT with fresh-frozen allografts between 2007 and 2016 were retrospectively reviewed. The inclusion criteria were patients with femoral or tibial chondral defects (International Cartilage Repair Society grade 4) who were followed up more than 2 years with 3.0-T magnetic resonance imaging (MRI) scans. Maximal lesion diameter and location were assessed on MRI. The patients were divided into two groups, with chondral defects of < 3 and ≥ 3 cm2 on the tibial side. Graft survivorship was compared between the two groups. Graft failure was defined as revisional MAT, meniscal tear or meniscectomy greater than one-third of the allograft on MRI. Clinical outcomes were evaluated using the modified Lysholm score. RESULTS: Twenty-eight knees in 26 patients (mean age 37.4 ± 10.3 years) with a mean follow-up of 3.6 ± 1.0 (range 2.0-5.4) years were identified. Nineteen knees in 17 patients had both femoral and tibial chondral defects, 7 knees in 7 patients had only femoral chondral defects, and 2 knees in 2 patients had only tibial chondral defects. The mean preoperative femoral and tibial chondral defect sizes were 1.7 ± 1.2 and 3.0 ± 1.4 cm2, respectively. Among the seven graft failures, no graft failure occurred in the cases with tibial chondral defects of < 3 cm2. Tibial chondral defects of ≥ 3 cm2 were significantly associated with graft failure (P = 0.004; odds ratio 28.3; 95% confidence interval 2.5-4006.7). Defects of < 3 cm2 were located primarily in the posterior aspect of the lateral tibial plateau, and most lesions were covered by allograft (7/9, 77.8%). The modified Lysholm scores significantly improved irrespective of chondral defects size (P < 0.001). CONCLUSIONS: Larger chondral defects, more than 3 cm2 on the tibial side, were associated with inferior graft survivorship but did not influence the clinical outcomes after MAT at the 3.6-year follow-up. Chondral defect location was associated with defect size. LEVEL OF EVIDENCE: IV.

Trends in Meniscal Allograft Transplant in the Republic of Korea, 2010-2018: An Analysis Based on the Korean National Health Insurance Claims Database.

BACKGROUND: Analyzing the current trends in meniscal allograft transplant (MAT) is important. However, no recent descriptive epidemiological study based on a national registry database has been reported. PURPOSE: To assess serial trends in the incidence of MAT in the Republic of Korea between 2010 and 2018, stratified by age and sex. STUDY DESIGN: Descriptive epidemiology study. METHODS: The number of MAT procedures between 2010 and 2018 was assessed using the Korean National Health Insurance claims database. We used code N0825 for isolated MAT and code N0820 for MAT combined with other procedures, such as ligament reconstruction, realignment surgery, and cartilage procedures. The incidence of MAT was calculated using the general population data of the Republic of Korea, and Poisson log-linear regression analysis was used to assess statistical serial trends. RESULTS: A total of 369 patients underwent MAT in 2010 and 774 in 2018, with an increase of 47.6%. The incidence of MAT per 100,000 person-years in the Republic of Korea increased significantly during the period studied, from 0.75 in 2010 to 1.50 in 2018 (annual relative risk = 1.09; 95% CI, 1.08-1.10; P < .001), whereas the rate of MAT combined with other procedures increased from 5.1% in 2014 to 16.0% in 2018. MAT was mostly performed in men in their early 20s. Most MAT procedures were performed in the summer and winter, with distinct seasonal variances. CONCLUSION: In the Republic of Korea, the incidence of MAT in 2018 was 1.50 per 100,000 person-years, with an average annual increase of 10% since 2010. MAT was mostly performed in men in their early 20s, and the rate of MAT combined with other procedures has increased since 2014.

Intrasubstance degeneration of medial meniscus horizontal cleavage tear in young patients is associated with increased joint line obliquity in the coronal plane of the knee.

PURPOSE: To evaluate the effect of joint line obliquity of the knee on intrasubstance degeneration of isolated medial meniscus horizontal cleavage tear (HCT) in young patients. METHODS: Sixty knees of 50 patients aged < 40 years (mean age, 33.3 ± 5.5 years old), who underwent arthroscopic partial meniscectomy (APM) for HCT, were retrospectively reviewed. The radiologic parameters of alignment, including mechanical hip-knee-ankle (mHKA) angle, posterior tibial slope, and joint line obliquity, were measured on preoperative long-standing whole-leg radiographs. The patients were classified into two groups, simple horizontal type (type 1) and complicated type (type 2), according to the presence of diffuse intrasubstance degeneration of the meniscus on preoperative magnetic resonance imaging. The risk factors for intrasubstance degeneration of HCT were analyzed using multiple logistic regression analysis. Medial joint space width (JSW) on weight-bearing 45° flexion posteroanterior radiographs and the mHKA were measured to evaluate the radiographic outcomes. The clinical outcomes were evaluated using the modified Lysholm score. Among patients followed-up for > 5 years, the clinical and radiologic outcomes were compared between the two groups. RESULTS: The joint line obliquity was significantly greater in the type 2 group than in the type 1 group (2.9 ± 1.3 vs. 0.9 ± 1.4, P < 0.001), and a significant risk factor for diffuse intrasubstance degeneration (P < 0.001; odds ratio, 2.88; 95% confidence interval, 1.27-6.54). The relative changes in the JSW in the type 2 group were greater than those in the type 1 group during the mean follow-up period of 7.9 ± 2.5 years (26% vs 10%, P = 0.045). The modified Lysholm score was not significantly different between the two groups (n.s). CONCLUSION: The diffuse intrasubstance degeneration of medial meniscus HCTs in young patients is associated with increased joint line obliquity of the knee joints. The radiologic outcomes after APM were inferior in the patients with diffuse intrasubstance degeneration. However, the clinical outcomes were not different during the mid-term follow-up. LEVEL OF EVIDENCE: Level III.

Medial and Lateral Meniscus Allograft Transplantation Showed No Difference With Respect to Graft Survivorship and Clinical Outcomes: A Comparative Analysis With a Minimum 2-Year Follow-Up.

PURPOSE: To compare the differences with respect to clinical and graft survivorship and patient-reported outcomes (PROs) between lateral (LMAT) and medial (MMAT) meniscus allograft transplantation. METHODS: Patients having a primary MAT between 1998 and 2016 were enrolled. The inclusion criteria were (1) patients who had a minimum 2-year follow-up and (2) patients who had magnetic resonance imaging (MRI) >2 years after surgery. Knees with localized grade 4 articular cartilage lesions >3 cm2 at the time of MAT were excluded. Clinical failure was defined as follows: modified Lysholm score <65, meniscectomy >50% of the graft, meniscectomy to the meniscocapsular junction zone, conversion to revision MAT, or realignment osteotomy or arthroplasty. Graft failure was defined as follows: tears involving >50% of the graft or unhealed peripheral rim observed on MRI. Kaplan-Meier survival analysis with log-rank test was used to compare survivorship between LMAT and MMAT. Patient-reported outcomes were compared based on the Hospital for Special Surgery, modified Lysholm, and International Knee Documentation Committee subjective scores collected preoperatively and at the final follow-up. RESULTS: A total of 299 knees (249 LMAT, 50 MMAT, mean age 33.0 ± 9.8 years) were included. Twenty clinical [2 MMAT (4.0%), 18 LMAT (7.2%)] and 24 graft [2 MMAT (4.0%), 22 LMAT (8.8%)] failures were identified. The mean clinical follow-up period was 63.1 ± 43.1 months (range 2 to 248), and MRI follow-up period was 62.6 ± 43.8 months (range 2 to 248). No significant differences in clinical and graft survivorship were found between the LMAT and MMAT groups (P = .481, P = .271, respectively). PROs preoperatively and at last follow-up also showed no significant difference between the groups. CONCLUSION: No significant differences in clinical survivorship, graft survivorship, and PROs were found between the LMAT and MMAT groups. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

There Is No Difference in Radiographic Outcomes After Average 9 Years After Arthroscopic Partial Medial Meniscectomy for Both Posterior Horn Tears and Posterior Horn Root Tears.

PURPOSE: To compare the serial changes in radiographic outcomes in terms of the mechanical axis (MA) angle and medial joint space width (JSW) between medial meniscus posterior root tear (MM PRT) and non-root tear (MM NRT) after arthroscopic partial meniscectomy (APM). METHODS: Patients who underwent APM for degenerative MM PRT or MM NRT from January 1999 to July 2012 were retrospectively reviewed. One hundred ten patients each in the MM PRT group and the MM NRT group, who were matched through propensity score matching (adjusting for confounding factors such as age, sex, body mass index, anatomic axis, cartilage state of the medial compartment, and follow-up period), were included in the study. The MA angle on weightbearing whole-leg radiographs and the medial JSW on weightbearing 45° flexion posteroanterior radiographs were measured to evaluate the radiographic outcomes. The serial changes were compared between radiographs taken before surgery, at postoperative 3 to 5 years, and at postoperative 5 years to the last follow-up. The linear mixed model was used to compare the changes in radiographic outcomes during the follow-up period between groups. RESULTS: The 2 groups were balanced with standardized mean differences of <0.2 after propensity score matching. Both the MM PRT and NRT groups showed increased varus alignment after surgery. However, there was no significant difference in the change in the MA angle during the follow-up period between groups (P = .182). The medial JSW also showed progression of joint space narrowing after surgery in both groups; however, there was no significant difference in the change in medial JSW during the follow-up period between groups (P = .270). CONCLUSION: The radiographic outcomes after partial meniscectomy in terms of the MA angle and medial JSW show comparable results between degenerative MM PRT and NRT after proper matching of confounding factors. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Postoperative alignment but not femoral coronal bowing is a significant longevity factor after total knee arthroplasty.

BACKGROUND: Femoral coronal bowing (FCB) has been reported to be a risk factor for mechanical malalignment after total knee arthroplasty (TKA). However, the effects of FCB on the long-term survivorship (when postoperative mechanical alignment (MA) is neutral after TKA) have not been determined. HYPOTHESIS: The effects of FCB on the cumulative survivorship after TKA may be significantly smaller compared with those of MA. PATIENTS AND METHODS: Consecutive 328 knees of 211 patients (10 males, 201 females) who underwent TKA between 1995 and 2009 (mean age of 64.2±6.7 years at the time of TKA, mean follow-up period of 11.9±2.5 years) were retrospectively evaluated. FCB and MA were evaluated using preoperative and immediate postoperative whole-leg anteroposterior radiographs, respectively. The patients were grouped according to FCB and postoperative MA, which included group A (FCB≤5°, MA≤3°), B (FCB>5°, MA≤3°), C (FCB>5°, MA>3°), and D (FCB≤5°, MA>3°). Primary end-point was defined as aseptic mechanical failures requiring revision TKA. Survivorship was assessed using the Kaplan-Meier method and compared using log-rank tests. Factors associated with the risk of aseptic mechanical failures were analyzed by Cox regression analysis. Preoperative and final follow-up clinical outcomes were assessed using Hospital for Special Surgery (HSS) scores. RESULTS: Group A, B, C, and D included 190, 73, 40, and 25 knees, respectively. The 10-year survivorship was similar between group A and B (96.3±1.4% vs. 98.6±1.4%; p=0.733) and group C and D (87.3±5.3 vs. 87.6±6.7%; p=0.974); however, it was significantly higher in group B than in group C (p=0.036) and in group A than in group D (p=0.005). Age (OR=0.991; 95% CI 0.906-1.085; p=0.002) and MA>3° (OR=3.645; 95% CI 1.744-7.604; p=0.001) were associated with the risk of aseptic mechanical failures. The mean preoperative and final HSS scores in the four groups were not significantly different. DISCUSSION: Marked FCB was not associated with long-term survivorship for knees with neutral alignment after TKA. However, non-neutral postoperative alignment reduced long-term survivorship for knees with marked FCB. LEVEL OF EVIDENCE: III, Retrospective comparative cohort study.

Absolute Meniscal Extrusion After Lateral Meniscal Allograft Transplantation Does Not Progress During Long-term Follow-up: Average of 10.3 Years' Follow-up Longitudinal Magnetic Resonance Imaging Study.

BACKGROUND: Long-term outcomes after lateral meniscal allograft transplantation (MAT) are not completely understood. PURPOSE/HYPOTHESIS: We investigated changes in meniscal extrusion in the coronal and sagittal planes using magnetic resonance imaging (MRI) after lateral MAT through long-term follow-up. We hypothesized that meniscal extrusion would progress during follow-up. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Patients subjected to lateral MAT were followed up by MRI evaluation in both planes at 1, 4 to 6, and >8 years after MAT. Meniscal extrusion and entire meniscal widths in the coronal plane and anterior (ACMD) and posterior (PCMD) cartilage meniscal distances in the sagittal plane were measured, and values were compared at each time point. Clinical outcomes were evaluated using the Lysholm score. RESULTS: A total of 27 lateral MATs were included with a mean MRI follow-up period of 10.3 years (range, 8.1-15.3 years). The mean absolute meniscal extrusion (coronal plane) was not significantly different at each time point. However, the relative value differed (0.27 ± 0.04 at 1 year; 0.33 ± 0.06 at >8 years after MAT) owing to entire meniscal width reduction. There was no difference in the mean absolute value of the ACMD in the sagittal plane. However, relative values differed (0.21 ± 0.01 at 1 year; 0.27 ± 0.06 at >8 years) owing to entire meniscal width reduction. Absolute and relative values of the PCMD remained unaffected at each time point. The Lysholm score increased after surgery but did not differ postoperatively. CONCLUSION: During the long-term follow-up of extrusion after lateral MAT using MRI, absolute extrusion remained unchanged across all planes. Relative extrusion in the coronal plane and of the ACMD in the sagittal plane significantly increased, with no differences in the PCMD on follow-up. Clinical outcomes after surgery improved compared with those before surgery and were maintained throughout the long-term follow-up period.

Increased preoperative medial and lateral laxity is a predictor of overcorrection in open wedge high tibial osteotomy.

PURPOSE: This study aimed at determining whether overcorrection after open wedge high tibial osteotomy (OWHTO) would be predicted by the magnitude of preoperative medial and lateral coronal soft tissue laxity around the knee joint. METHODS: Overall, 68 knees of 62 patients who underwent OWHTO for primary medial osteoarthritis were retrospectively reviewed. The mechanical hip-knee-ankle (HKA) axis, weight-bearing line (WBL) ratio, medial proximal tibial angle (MPTA), joint line obliquity, coronal subluxation, and joint line convergence angle (JLCA) were measured on full-weight-bearing long-standing HKA radiographs preoperatively and at 1 year postoperatively. The varus valgus stress angle was measured on preoperative radiographs. The correction amount due to soft tissue factors was calculated as the difference between the WBL ratio on postoperative 1-year radiographs and that on virtually corrected preoperative radiographs with the same amount of MPTA at 1 year postoperatively. The patients were grouped according to the presence or absence of a ≥ 10% overcorrection of WBL ratio (overcorrection or expected correction). Multiple logistic regression analysis was performed to identify the preoperative risk factors of overcorrection. RESULTS: The average WBL ratio was corrected from 19.0 ± 13.5% preoperatively to 61.6 ± 9.1% postoperatively (P < 0.001). The average MPTA changed from 85.1 ± 1.7° preoperatively to 93.6 ± 2.6° postoperatively, resulting in an average tibia correction angle of 8.6 ± 3.1°. The average estimated correction from soft tissue factors was 5.8 ± 7.4% of the WBL ratio. Soft tissue correction of the WBL ratio > 10% was confirmed in 17 patients (28%). The preoperative JLCA and valgus stress angle were significantly greater in the overcorrection group than in the expected correction group: 5.0 ± 1.7° vs. 3.4 ± 1.9° (P = 0.003) and 2.4 ± 1.0° vs. 1.3 ± 1.2° (P = 0.002), respectively. Among the radiologic parameters, the presence of both ≥ 4° JLCA and ≥ 1.5° valgus stress angle was the only significant risk factor for overcorrection from soft tissue factors (P = 0.006; odds ratio, 30.2). CONCLUSIONS: The magnitude of both medial and lateral coronal soft tissue laxity was a predictor of overcorrection from soft tissue factors after OWHTO. Overcorrection was more likely to occur in cases with both ≥ 4° JLCA and ≥ 1.5° valgus stress angle. LEVEL OF EVIDENCE: III.