Effect of joint-line obliquity on long-term survivorship of total knee arthroplasty: A postoperative phenotype analysis.

PURPOSE: Whether the longevity of total knee arthroplasty (TKA) differs between postoperative phenotypes has not been investigated. This study aims to examine which phenotype has a worse long-term survival rate than the reference phenotype (neutral alignment-parallel joint line), and whether joint-line obliquity (JLO) affects the survivorship of TKA. METHODS: A total of 945 knees that underwent primary TKAs for primary osteoarthritis from January 2000 to January 2009 were included. These were classified into nine postoperative phenotypes based on the combined assessment of the hip-knee-ankle (HKA) angle and JLO, measured on standing radiographs. The 5-, 10- and 15-year survival rates were analysed using Kaplan-Meier methods and log-rank tests. The long-term survival rates of each phenotype were compared with the reference phenotype. RESULTS: There were 55 aseptic mechanical failures within a period of 10.4 ± 5.0 years. The most frequently observed phenotypes were the reference phenotype (n = 527), neutral alignment-lateral joint-line inclination (n = 162), varus alignment-lateral joint-line inclination (n = 104) and varus alignment-parallel joint line (n = 101). The overall failure rate for each phenotype was 3.6%, 3.7%, 18.3% and 7.9%, respectively. Only the 10- and 15-year survival rates of the varus alignment-lateral joint-line inclination phenotype were significantly different from those of the reference phenotype (97%-93% vs. 90%-69%; p = 0.017, <0.001). CONCLUSION: The lateral joint-line inclination phenotype had an inferior long-term survival rate after varus-aligned TKA. This suggested that alignment and JLO affected the long-term survival rate of patients who underwent TKA. LEVEL OF EVIDENCE: Level III, Retrospective cohort study.

Preoperative phenotype has no significant impact on the clinical outcomes and long-term survival of mechanically aligned total knee arthroplasty in Asian patients with osteoarthritis.

Aims: The aim of this study was to investigate the distribution of phenotypes in Asian patients with end-stage osteoarthritis (OA) and assess whether the phenotype affected the clinical outcome and survival of mechanically aligned total knee arthroplasty (TKA). We also compared the survival of the group in which the phenotype unintentionally remained unchanged with those in which it was corrected to neutral. Methods: The study involved 945 TKAs, which were performed in 641 patients with primary OA, between January 2000 and January 2009. These were classified into 12 phenotypes based on the combined assessment of four categories of the arithmetic hip-knee-ankle angle and three categories of actual joint line obliquity. The rates of survival were analyzed using Kaplan-Meier methods and the log-rank test. The Hospital for Special Surgery score and survival of each phenotype were compared with those of the reference phenotype with neutral alignment and a parallel joint line. We also compared long-term survival between the unchanged phenotype group and the corrected to neutral alignment-parallel joint line group in patients with Type IV-b (mild to moderate varus alignment-parallel joint line) phenotype. Results: The most common phenotype was Type I-b (mild to moderate varus alignment-medial joint line; 27.1% (n = 256)), followed by Type IV-b (23.2%; n = 219). There was no significant difference in the clinical outcomes and long-term survival between the groups. In Type IV-b phenotypes, the neutrally corrected group showed higher 15-year survival compared with the unchanged-phenotype group (94.9% (95% confidence interval (CI) 92.0 to 97.8) vs 74.2% (95% CI 98.0 to 100); p = 0.020). Conclusion: Constitutional varus was confirmed in more than half of these patients. Mechanically aligned TKA can achieve consistent clinical outcomes and long-term survival, regardless of the patient's phenotype. The neutrally corrected group had better long-term survival compared with the unchanged phenotype group.

Risk Factor for Clinical Failure of Medial Meniscal Allograft Transplant: Early vs Late Graft Tear.

BACKGROUND: Graft tears are common postoperative findings in meniscal allograft transplant (MAT). Graft tear in medial MAT may be different from that of lateral MAT, considering the difference between medial meniscal tears and lateral meniscal tears. Moreover, medial MAT is frequently accompanied by ligament reconstruction, which is associated with graft tear. The effect of graft tear on the long-term survivorship of medial MAT has not been investigated. HYPOTHESIS: Graft tear would adversely affect the survivorship of medial MAT and the effect would be different according to the timing of graft tear. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 55 patients undergoing medial MAT between June 2019 and March 2000 were retrospectively reviewed. Postoperative magnetic resonance imaging (MRI) scans were reviewed to identify graft tears, and the timing of their occurrence was investigated. Postoperative MRI was performed routinely during the first postoperative year and every 2 years thereafter. The patients were classified into a no graft tear (NT) group, early graft tear (occurring within 1 year; ET) group, and late graft tear (occurring 1 year after surgery; LT) group. The survival rate of medial MAT was estimated according to graft tear, with a failure being defined as (1) reoperations including arthroplasty, realignment osteotomy, revision MAT, and meniscectomy (>50% of the graft or to the zone of the meniscocapsular junction) or (2) Lysholm score <65. Clinical scores were compared between the groups. RESULTS: The mean follow-up duration was 8.6 ± 5.3 years. During that period, clinical failures occurred in 6 (10.9%) patients. The overall survival rate at 5 years was 94.0% (95% CI, 90.6%-97.4%). Graft tears were seen in 18 patients: 6 patients in the ET group and 12 patients in the LT group. The median time when the graft tear was noted on MRI scans was 5.5 months (range, 1-11 months) postoperatively in the ET group and 99.5 months (range, 19-264 months) postoperatively in the LT group. Five patients in the ET group had root tears, whereas 9 patients in the LT group had complex or horizontal tears. The 5-year survival rate of the ET group was 62.5% (95% CI, 41.2%-83.8%), which was significantly lower than that of the NT group (96.8%; 95% CI, 93.6%-99.9%) and the LT group (85.7%; 95% CI, 72.5%-98.9%; P = .002). The mean postoperative Lysholm scores were 85.6 ± 17.9 in the NT group, 93.0 ± 2.8 in the ET group, and 79.3 ± 11.6 in the LT group, showing no significant difference between the groups (Kruskal-Wallis test, P = .058). CONCLUSION: Clinical relevance of graft tear that occurred after medial MAT was dependent upon its timing. ET was a risk factor for clinical failure, whereas LT did not adversely affect graft survivorship. Lysholm scores did not differ according to graft tear.

Lateral Distance From the Osteotomy Hinge Point to the Tibial Cortex Is Associated With Lateral Hinge Fracture Type and Fracture Occurrence Time After Medial Open-Wedge High Tibial Osteotomy.

PURPOSE: To verify whether the distance from the hinge point to the tibial cortex affects the occurrence time and characteristics of the lateral hinge fracture (LHF) in medial open-wedge high tibial osteotomy. METHODS: We retrospectively reviewed 171 knees in 171 patients (121 women, 50 men; mean age, 53.9 years; range, 36-67 years) who had undergone medial open-wedge high tibial osteotomy with locking plate fixation between January 2011 and December 2020. Osteotomy hinge point and LHFs were identified on intraoperative fluoroscopy and immediate postoperative radiographs. LHF type was classified as suggested by Takeuchi et al. Acute fracture was defined as a fracture that occurred during surgery, and delayed fracture was defined as a fracture observed after 1 month postoperatively. The nearest distances from osteotomy hinge point to lateral, distal, and proximal cortex were measured on postoperative radiographs. We compared the distance between the different types and between acute and delayed LHFs. RESULTS: There were 55 LHFs (32%) (type I, 40 knees; type II, 14 knees; type III, 1 knee) that occurred acutely in 41 knees and were found as delayed fractures in 14 knees. The patient demographics were not significantly different between non-LHFs and each type of LHFs. Proximal and distal distances were not statistically different among fracture types and between occurrence times. However, lateral distances were significantly shorter in type I LHFs (6.2 ± 1.8 mm) and longer in type II LHFs (9.3 ± 2.3 mm) than in non-LHFs (7.1 ± 2.7 mm) (P = .020 and .004, respectively). The lateral cortical distances were also different between acute LHFs (6.4 ± 1.9 mm) and delayed LHF (9.0 ± 2.7 mm) (P < .001). In the case of fracture type, the frequency of type I decreases with increase in the lateral distance, whereas that of type II increases with increase in the lateral cortical distance. In acute fracture, type I was dominant (85.4%), whereas in delayed fracture, type II was dominant (57.2%). CONCLUSIONS: The lateral cortical distance from the hinge point was significantly associated with LHF occurrence. Shorter distance increased the risk for acute type I LHF, whereas longer distance increased the risk for delayed type II LHFs. LEVEL OF EVIDENCE: Level III, retrospective comparative prognostic trial.

Limb length change after total knee arthroplasty for valgus deformity does not affect the clinical score and is not affected by fixed flexion deformity.

BACKGROUND: The limb length change (LLC) after total knee arthroplasty (TKA) is especially significant in valgus deformity. The higher LLC could cause higher incidences of lower limb length discrepancy (LLD) and low clinical score. However, studies about LLC after TKA for valgus deformity are limited, and there are none on the relationship between LLC and fixed flexion deformity (FFD) in valgus deformity. HYPOTHESIS: (1) The amount of LLC would affect the postoperative LLD, (2) the improvement of fixed flexion deformity (FFD) would affect the amount of LLC, (3) The amount of LLC would affect the improvement in the clinical score after TKA for valgus deformity. PATIENTS AND METHODS: Fifty knees of 50 patients who underwent primary unilateral TKA for valgus-type osteoarthritis between January 2000 and October 2021 were included. A radiological and clinical assessment were performed the day before the operation and at 12 months post-operatively. Full-length standing anteroposterior radiographs were used to measure HKA and LLC. FFD and Hospital for Special Surgery (HSS) score were measured in the outpatient department. RESULTS: The incidence of lengthening was 92.0% and the mean LLC was 18.85mm (SD, 19.60mm). Postoperative LLD over 10mm occurred in 26% and the mean of postoperative LLD was 4.21mm (SD, 7.96mm). The LLC was correlated with postoperative LLD (rs=0.357, p=0.011) and the HKA change (rs=0.375, p=0.007), but not with the FFD improvement (rs=0.164, p=0.255) and HSS improvement (rs=0.076, p=0.613) or postoperative HSS (rs=0.094, p=0.528). CONCLUSION: LLC was affected by HKA improvement but not by FFD improvement after TKA for patients with valgus deformity. Additionally, LLC did not affect the clinical score. LEVEL OF EVIDENCE: III; retrospective cohort study.

Early Graft Tear As a Major Risk Factor for the Clinical Failure of Lateral Meniscal Allograft Transplantation.

BACKGROUND: Graft tears are often observed on magnetic resonance imaging after lateral meniscal allograft transplantation (MAT). Their characteristics, such as the location and configuration, are likely to be different depending on the timing of the injury. However, the clinical relevance of early and late graft tears has not been investigated. HYPOTHESIS: (1) Both early and late graft tears would be associated with the clinical failure of lateral MAT, and (2) an early graft tear (ET) would lead to worse outcomes than a late graft tear (LT) or an intact graft. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 261 patients who had undergone lateral MAT between March 2000 and June 2019 were retrospectively reviewed. The graft tear was investigated using magnetic resonance imaging, which was performed routinely during the first postoperative year and every 2 years thereafter. The patients were classified according to the timing of the graft tear: no graft tear (NT) group, ET (≤1 year after surgery) group, and LT (>1 year after surgery) group. Clinical failure was defined as (1) reoperations including arthroplasty, realignment osteotomy, revision MAT, and meniscectomy (>50% of the graft or to the zone of the meniscocapsular junction) or (2) a Lysholm score of <65. Risk factors for a low survival rate were investigated using Cox regression analysis. A comparison of the Lysholm scores for each group was also performed. RESULTS: There were 24 (9.2%) patients who had clinical failure at a mean follow-up of 7.5 ± 4.3 years. The overall survival rate at 5 years was 92.8% (95% CI, 91.1%-94.5%). A graft tear was noted in 80 patients: 23 patients in the ET group and 57 patients in the LT group. The most common tear pattern was a meniscocapsular tear in the ET group and a complex tear in the LT group. The hazard ratios for clinical failure in the ET and LT groups were 30.7 (95% CI, 9.4-76.4; P < .001) and 4.0 (95% CI, 1.3-12.9; P = .013), respectively. The Lysholm score of the ET group (82.7 ± 14.8) was significantly lower than that of the other 2 groups (NT: 87.6 ± 11.7; LT: 90.7 ± 9.0; P = .024). CONCLUSION: An ET was a major risk factor for the clinical failure of lateral MAT. An LT was associated with a lower survival rate. An ET was also associated with worse clinical outcomes.

Lateral Meniscal Allograft Transplantation Shows a Long-Term Chondroprotective Effect on Quantitative MRI T2 Mapping at 7 Years' Minimum Follow-Up.

PURPOSE: The purpose of this study was to assess the long-term chondroprotective effect of lateral meniscal allograft transplantation (MAT) using quantitative magnetic resonance imaging (MRI) T2 mapping. METHODS: In patients who underwent isolated lateral MAT, quantitative MRI T2 mapping was conducted preoperatively and postoperatively with at minimum follow-up of 7 years to assess the articular cartilage status. On the sagittal section image bisecting the lateral femoral condyle, the weight-bearing portions of the femoral and tibial articular cartilage were divided into 3 segments each-6 segments in total-based on the meniscal coverage area. The regions of interest analysis were performed on the 6 segments to measure the mean T2 value. Then, the whole layer was divided into deep and superficial layers for further zonal analysis. The longitudinal change in T2 values was statistically analyzed using paired t-tests. Clinical outcome was evaluated using the Lysholm score. RESULTS: A total of 31 patients were included in the study, with the MRI follow-up period of a minimum follow-up of 7 years (mean: 8.9 ± 1.3 years; range: 7.0-11.2 years). The mean T2 value of the whole layer showed significant improvement in all segments of the femoral cartilage and the posterior segment of tibial cartilage. In the zonal analysis, the mean T2 value of the tibial cartilage showed significant improvement in the superficial layer of the mid to posterior portion, while the deep layer remained stable. In contrast, the mean T2 value of the femoral cartilage showed significant improvement in the superficial and deep layers in all segments. The mean Lysholm score significantly improved from 62.6 ± 12.8 to 90.9 ± 10.5 (P < .001). CONCLUSION: This study suggests that MAT appears to have a long-term chondroprotective effect on the articular cartilage as judged by quantitative T2 mapping. LEVEL OF EVIDENCE: Level Ⅳ, case series.

Tear patterns and locations are different between lateral and medial compartments in patients with early anatomical failure after meniscal allograft transplantation.

PURPOSE: To investigate the characteristics of anatomically failed grafts within 1 year after meniscal allograft transplantation (MAT) and compare the differences between lateral and medial MATs. METHODS: The records of consecutive patients with anatomically failed grafts within 1 year after primary MAT between 2005 and 2018 were reviewed. Anatomical failure was defined as a tear covering > 50% of the allograft or an unstable peripheral rim. The pattern and location of the graft tears were analyzed using magnetic resonance imaging or arthroscopy. RESULTS: A total of 21 patients were included. All 21 patients had anatomical failure with tears involving > 50% of the allograft, whereas 15 had an unstable peripheral rim of the allograft. The mean failure time was 6.6 ± 3.6 months in all patients (lateral MAT, n = 15; medial MAT, n = 6). In the lateral MAT group, meniscocapsular separation was the most common pattern (n = 10, 66.7%), followed by complex (n = 3, 20.0%), radial (n = 1, 6.7%), and longitudinal (n = 1, 6.7%) tear. In the medial MAT group, a root tear was the most common pattern (n = 5, 83.3%), followed by a complex tear (n = 1, 16.7%). Meanwhile, in the lateral MAT, the midbody was the most frequently affected location (n = 9, 60.0%), followed by the posterior (n = 5, 33.3%) and anterior (n = 1, 6.7%) areas; in the medial MAT group, the posterior (n = 5, 83.3%) was the most frequently affected location, followed by the anterior area (n = 1, 16.7%). Significant differences in the pattern (P = 0.002) and location (P = 0.043) of the graft tears were found between lateral and medial MATs. CONCLUSION: In patients with early failure after MAT, meniscocapsular separation in the midbody of the lateral compartment and root tears in the posterior area of the medial compartment were the most common. Thus, surgeons are encouraged to pay extra attention to these vulnerable areas during the early period after MAT. LEVEL OF EVIDENCE: IV.

Twenty-year survivorship cohort study of total knee arthroplasty in Asian patient using a single posterior-stabilized implant performed by a single surgeon.

INTRODUCTION: As life expectancy has improved, the potential number of revision candidates is also expected to increase among patients who have undergone a total knee arthroplasty (TKA). The longevity of modern posterior stabilized knee prostheses after 20 years of use has not been well documented, especially in Asian populations that require a deeper flexion range due to a floor-based lifestyle. HYPOTHESIS: Firstly, the implant longevity regarding mechanical failures such as aseptic loosening and polyethylene (PE) wear would vary over a longer follow-up depending on the age groups; and secondly there would be unique risk factors for revision surgery in an Asian TKA cohort. MATERIAL AND METHODS: We conducted this age-stratified survival analysis in a consecutive series of 368 NexGen Legacy Posterior Stabilized (LPS) TKAs performed by a single surgeon. These cases were divided into four age groups (< 60 years, early 60s, late 60s, and ≥ 70 years). The implant longevity against aseptic mechanical failures was calculated using the Kaplan-Meier method. The revision surgery risk was evaluated using postoperative factors including a deep flexion capability (> 135̊), and postoperative mechanical alignments. RESULTS: Overall survivorship was significantly lower in the youngest groups than other groups (Log-rank test, p=0.001). The cumulative 20-year implant longevity was more than 95% in the two oldest groups, but less than 60% in the youngest group. It was notable that the post-TKA implant longevity was not apparent up to 10 years between the age groups (p=0.073∼0.458). Aseptic loosening was observed with an earlier onset (3.1 to 18.9 years) trend than PE wear (9.8∼17.9 years), with most cases arising in the youngest groups. Flexion limitation and varus alignment were significant risks to aseptic loosening and PE wear (Cox proportional hazard regression: p=0.001 and 0.045, respectively). DISCUSSION: A younger age (< 60 years), inability of postoperative deep flexion, and varus alignment were significant risk factors for aseptic loosening and PE wear after modern PS design in this Asian cohort. The difference in postoperative longevity affected by these factors was not obvious during the first 10 years but emerged over a second decade. LEVEL OF PROOF: III; retrospective cohort study.

Survivorship After Lateral Meniscal Allograft Transplantation Plus Concurrent Cartilage Procedure in Patients With Poor Cartilage Status: A Comparative Study.

BACKGROUND: The effect of a concurrent cartilage procedure in lateral meniscal allograft transplantation (MAT) in patients with bipolar cartilage lesions (high-grade lesions on both the femoral and the tibial side) is not well studied. An objective evaluation of graft status after MAT and a concurrent cartilage procedure has not been reported. PURPOSE: To investigate the effect of concurrent cartilage procedures and lateral MAT on objective and clinical outcomes, including survival, in patients with bipolar cartilage lesions. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 149 patients with high-grade (International Cartilage Regeneration & Joint Preservation Society grade 3 or 4) cartilage lesions were enrolled and assigned to 1 of 3 groups based on the cartilage procedure and cartilage status at the time of MAT. Femoral cartilage procedures (microfracture, n = 18; osteochondral autograft transfer, n = 13) and lateral MAT were performed in 31 patients with bipolar cartilage lesions (cartilage procedure group). Another 70 patients with bipolar lesions underwent only lateral MAT without cartilage procedure (bipolar lesion group). The remaining 48 patients, who had high-grade lesions only on the tibial side and underwent lateral MAT without a cartilage procedure, were selected as a control group (unipolar lesion group). Anatomic survival was objectively assessed by follow-up magnetic resonance imaging and second-look arthroscopy. Clinical survivorship was determined with a Lysholm score <65 or need for additional surgery, such as revision MAT. RESULTS: The mean Lysholm score improved from 67.2 ± 15.9 preoperatively to 86.7 ± 11.1 with a mean follow-up of 78.0 ± 51.2 months (P < .001). The postoperative scores were not significantly different between the 3 groups. The estimated 5-year anatomic survival rate in the cartilage procedure group (86.7%) was higher than that in the bipolar lesion group (65.0%; P = .043) but comparable with that in the unipolar lesion group (90.2%; P = .572). The estimated 5-year clinical survival rates were not significantly different between the groups (P = .187). CONCLUSION: A concurrent femoral cartilage procedure improved the anatomic survival rate in patients with bipolar chondral lesions who underwent lateral MAT. This finding suggests that the cartilage procedure is an effective treatment choice and may improve the status of an allograft after lateral MAT for patients with bipolar cartilage lesions.

Effect of High Body Mass Index on Survivorship After Lateral Meniscal Allograft Transplantation: A Propensity Score Matching Analysis.

BACKGROUND: Preoperative body mass index (BMI) is one of the correctable factors before surgery. Few studies have investigated the effect of BMI on the survivorship of lateral meniscal allograft transplantation (MAT). HYPOTHESIS: Patients with a high BMI have inferior survivorship after lateral MAT when compared with those with a normal BMI. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Overall, 306 consecutive patients who underwent lateral MAT were retrospectively reviewed. According to the classification criteria of the World Health Organization, patients were split into 2 groups: normal weight (BMI <25.0) and overweight (BMI ≥25.0). There were 104 patients (34.0%) allocated into the overweight group. Given the demographic heterogeneity between the groups, propensity score matching was performed. Before and after propensity score matching, the anatomic and clinical survival rates of the 2 groups were compared by Kaplan-Meier survival analysis. Anatomic failure was defined as a tear covering >50% of the allograft or unstable peripheral rim on follow-up magnetic resonance imaging and second-look arthroscopy. Clinical failure was defined as a Lysholm score <65 or need for additional surgery, such as revision MAT. RESULTS: For all patients, the mean ± SD follow-up period was 6.9 ± 4.2 years. The mean BMI of the overweight and normal weight groups was 27.8 ± 2.6 and 22.0 ± 1.9, respectively. The mean Lysholm scores at the last follow-up were not significantly different between the groups. However, the anatomic survival rate in the overweight group (77.9%) was significantly lower than that in the normal weight group (90.1%) (P < .001). The clinical survival rate (82.7%) in the overweight group was significantly lower than that in the normal weight group (95.0%) (P < .001). After propensity score matching for patient characteristics, which left 87 patients per group, the anatomic and clinical survival rates were significantly lower in the overweight group. CONCLUSION: Preoperative high BMI was associated with inferior anatomic and clinical survival rates. The results of the current study suggest that weight loss before lateral MAT may be required in overweight patients for the improvement of anatomic and clinical survival rates.

Graft Extrusion of 3 Millimeters Is Acceptable at a Minimum of 5-Year Outcomes for Lateral Meniscal Allograft Transplantation.

PURPOSE: To determine the acceptable amount of graft extrusion based on long-term radiographic outcomes in lateral meniscal allograft transplantation (MAT). METHODS: 94 lateral MAT patients with a minimum 5-year follow-up period were reviewed. Graft extrusion was measured on MRI scans taken 1 year after surgery, and the study population was divided according to the amount of extrusion: group A, extrusion <3 mm; group B, 3 mm ≤ extrusion <5 mm; and group C, extrusion ≥5 mm. For radiographic evaluation, the bilateral lateral joint space widths (JSWs) were measured on a standing 45° flexion posteroanterior radiograph. To standardize the measurements, the affected JSW was divided by the contralateral JSW. The change in the standardized JSW (ΔJSWstd) between the preoperative and latest follow-up assessments was analyzed according to the three groups. Multiple regression analysis was performed to control other related factors, such as lower limb alignment and cartilage status at the time of MAT. The acceptable amount of graft extrusion was calculated using a receiver operating characteristic (ROC) curve for the third quartile of ΔJSWstd. Clinical outcomes were evaluated using the Lysholm score and were compared among the groups. RESULTS: The mean follow-up duration was 8.3 ± 3.1 years. There were 54, 25, and 15 patients in group A, group B, and group C, respectively. In multiple regression analysis, both group B and group C had significant associations with ΔJSWstd and their beta coefficients were comparable (group B, P < .001, ß = .642; group C, P < .001, ß = 0.613). No significant difference in ΔJSWstd was found between group B and group C (P = .494). On the basis of the ROC curve, the acceptable amount of graft extrusion was 3.74 mm (sensitivity, 81.8%; specificity, 77.8%). There were no differences in the Lysholm scores among the three groups (P = .329). CONCLUSIONS: ΔJSWstd differed between graft extrusion <3 mm (group A) and graft extrusion ≥3 mm (group B and group C). However, there was no significant difference in ΔJSWstd between group B and group C. No significant difference in clinical outcomes was found according to graft extrusion. This study gave supporting evidence for the currently recognized acceptable amount of graft extrusion (3 mm). LEVEL OF EVIDENCE: Level III, retrospective cohort study.

Signal intensity of lateral meniscal allografts deteriorates over time: a longitudinal MRI analysis during a minimum follow-up of 8 years.

PURPOSE: To evaluate the serial change of magnetic resonance imaging (MRI) signal intensity (SI) of lateral meniscal allografts in a long-term period of > 8 years and to determine whether the SI change adversely affected clinical outcomes. METHODS: Thirty-three lateral meniscal allograft transplantation (LMAT) patients with MRI taken > 8 years after surgery were included. The allograft was assessed using MRI at five serial time points (1, 2-4, 4-6, 6-8, and > 8 years after surgery), based on the following grading system: grade 1, globular increased SI not adjacent to the articular surface; grade 2, linear SI within the meniscus; and grade 3, increased SI extended to the articular surface. MRI evaluation was performed for three locations of the allograft (anterior horn, mid-body, and posterior horn), and the serial changes of allograft SI at each location were analyzed using the generalized estimating equation (GEE) with cumulative logit link function. The patients were classified according to SI change at each location (stationary group and deterioration group), and the two groups were compared in terms of clinical outcomes using the Lysholm score. RESULTS: The mean follow-up duration was 9.2 ± 1.2 years. During that period, SI of the allograft deteriorated over time, regardless of the location (anterior horn, p = 0.034; mid-body, p = 0.002; posterior horn, p < 0.001). The amount of SI deterioration at each location of the graft differed with a borderline significance (p = 0.050, GEE), and the proportion of grade 3 SI was higher at the posterior horn (36.4%) than at the other locations at the last follow-up (p < 0.001, chi-square test). However, no significant differences in the Lysholm scores were found between the stationary group and the deterioration group at all locations. CONCLUSION: SI of the meniscal allograft deteriorated over time at all locations during the long-term follow-up. Deterioration of the graft was more prominent at the posterior horn than at the other locations. SI deterioration did not adversely affect the clinical outcomes, which should be interpreted with caution, considering the small sample size of this study. In the prognosis of lateral MAT, SI deterioration at the posterior horn is a more determining factor than that at the other part of the allograft. Therefore, SI at the posterior horn needs to be examined with special concern. LEVEL OF EVIDENCE: III.

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.

Lateral Meniscal Allograft Transplantation Provides a Chondroprotective Effect on Articular Cartilage: Quantitative 3-T Magnetic Resonance Imaging T2 Mapping.

PURPOSE: This study aimed to assess the cartilage status in patients who underwent isolated lateral meniscus allograft transplantation (MAT) using preoperative and postoperative quantitative 3-T magnetic resonance imaging T2 mapping at midterm follow-up period. METHODS: Patients who underwent lateral MAT without cartilage treatment procedures between 2010 and 2019 were assessed by quantitative magnetic resonance imaging preoperatively and postoperatively. On the sagittal section image following the center of the lateral femoral condyle, the weight-bearing area of the articular cartilage was divided into 6 segments based on the meniscal coverage area from anterior to posterior direction. The mean T2 values of each of the 6 segments were measured for 3 regions of interest: overall, deep, and superficial layers. The change in T2 values was statistically analyzed by paired t-tests. The Lysholm score was used to evaluate clinical function. RESULTS: A total of 105 patients were included in the study. The mean follow-up period was 3.2 years (range 2.0-5.4 years). Among the 6 segments, the mean T2 value showed significant improvement in the overall layer of F2 (the middle weight-bearing area of femoral condyle) and TP3 (the posterior weight-bearing area of tibia condyle) segments (P = .013 and .021, respectively) and the superficial layer of the F3 (the posterior weight-bearing area of femoral condyle) segments (P = .028). The mean T2 value of all the other segments did not show a statistically significant change. The mean Lysholm score significantly improved from 66.5 ± 15.8 to 89.3 ± 10.0 (P < .001). Overall, 73.3% and 96.2% of the patients met the minimal clinically important difference and patient acceptable symptomatic state, respectively. CONCLUSIONS: The mean T2 value of the articular cartilage of the weight-bearing area was either maintained or showed statistically significant improvement depending on the location following isolated lateral MAT. Thus, the transplanted meniscus seems to have a chondroprotective effect on the weight-bearing cartilage. LEVEL OF EVIDENCE: Level IV, retrospective therapeutic case series.

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.

Effect of ICRS Lesion Grade on Graft Survival After Medial Meniscal Allograft Transplantation: MRI-Based Objective Evaluation.

BACKGROUND: Data are lacking regarding the survival rate after medial meniscal allograft transplantation (MAT) alone. Furthermore, little information is available about prognostic factors for graft survival that affect the outcomes of medial MAT. PURPOSE: To investigate the prognostic factors and survival rate of allograft after medial MAT. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: The records of 78 consecutive patients who underwent primary medial MAT between 1996 and 2018 were reviewed. Kaplan-Meier survival analysis was performed to analyze the anatomic and clinical survival rates. Anatomic failure was defined as a tear covering >50% of the allograft or unstable peripheral rim. Clinical failure was considered Lysholm score <65 or need for additional surgery such as meniscal repair, revision MAT, realignment osteotomy, and meniscectomy for >50% of the allograft. Patient factors affecting anatomic and clinical failure were analyzed. RESULTS: The mean follow-up period was 6.9 ± 5.3 years (range, 2-21 years). Anatomic failure was noted in 19 patients (24.4%), and none of these patients had a persistent poor Lysholm score of <65; of these, 2 patients who underwent meniscal repair also had clinical failure. Clinical failure was noted in 7 patients (9.0%); 4 patients had Lysholm score <65, 2 patients underwent meniscal repair, and 1 patient underwent realignment osteotomy. The estimated 10-year anatomic and clinical survival rates were 73.89% and 87.90%, respectively. Anatomic survival was significantly associated with only high-grade International Cartilage Regeneration & Joint Preservation (ICRS) lesion (ICRS grade 3 or 4) (hazard ratio, 3.171; 95% CI, 1.124-8.944; P = .029). However, the clinical survival rate was not significantly associated with any factors. Patients with low-grade ICRS lesion (ICRS grade 0, 1, or 2) showed a higher estimated 10-year anatomic survival rate compared with patients with high-grade ICRS lesions (87.6% vs 63.3%, respectively; P = .022). CONCLUSION: Low-grade ICRS lesion was associated with higher anatomic survival rate after medial MAT. In patients with high-grade ICRS lesions, the clinical outcome might be good; however, the status of an allograft might be poor. The surgeon should be aware of this and explain to the patient that close observation is necessary.

Radial tears in the anterior third of the lateral meniscus are frequently combined with horizontal tears.

INTRODUCTION: Radial tears of the lateral meniscus are often located in the junction of the middle and posterior third or posterior tibial attachment. However, we observed that a few cases of radial tears occurred in the anterior third of the lateral meniscus, and in many cases, they were accompanied by horizontal tears. HYPOTHESIS: Radial tears are more frequently accompanied by horizontal tears in the anterior third of the lateral meniscus than in other regions. MATERIAL AND METHODS: From July 2006 to May 2019, patients who underwent arthroscopic surgery for radial tears of the lateral meniscus were included. Patients with radial tears in the anterior third of the lateral meniscus were classified into the anterior group and those with radial tears in the middle and posterior third were classified into the comparison group. Magnetic resonance imaging and arthroscopic findings were reviewed to evaluate whether radial tears were accompanied by other types of tears, especially horizontal tears. The incidence of complex tears between the two groups was compared. RESULTS: Eighty knees in 79 patients were included. The mean age at the time of surgery was 44.1±16.9 years. The anterior group included 30 knees, and 19 (63.3%) of those also had horizontal tears. In the anterior group, all complex tears were accompanied by horizontal tears, and no other types of accompanying tears were observed. The comparison group included 50 knees, and 16 (32%) of those also had other types of tears. Of the 16 complex tears, 14 had horizontal tears and 2 had longitudinal tears. The incidence of complex tear was significantly higher in the anterior group than in the comparison group (p<.001). CONCLUSION: Radial tears occurring at the anterior third of the lateral meniscus are frequently accompanied by a horizontal tear. It is important to be aware and predict the occurrence of such characteristic tears and to do proper surgical procedures. LEVEL OF PROOF: IV; Cross-sectional study.

Insufficient Correction and Preoperative Medial Tightness Increases the Risk of Varus Recurrence in Open-Wedge High Tibial Osteotomy.

PURPOSE: To assess serial changes of limb alignment after open wedge high tibial osteotomy (HTO) using the weightbearing line (WBL) ratio in the midterm, with a focus on varus recurrence. METHODS: Patients undergoing open wedge HTO from January 2010 to December 2016 were retrospectively reviewed. Those without serial postoperative weightbearing long-leg alignment films, those who showed remained varus alignment after osteotomy, and those who had <2 years of follow-up were excluded. In terms of immediate postoperative limb alignment (≤3 months) measured using WBL ratio, cases were categorized into 4 groups: <50%, undercorrection; 50% to 57%, insufficient correction; 57% to 67%, planned correction; and >67%, overcorrection. To determine risk factors for varus recurrence (WBL ratio <50%), immediate postoperative WBL ratio category and preoperative valgus and varus stress angles (which represent medial and lateral tightness of the joint, respectively) were investigated using logistic regression analysis, taking other related factors into account. Clinical outcomes according to varus recurrence were measured using Hospital for Special Surgery (HSS) scores. RESULTS: A total of 148 cases were included. Varus recurrence was noted in 40 cases (27.0%), with a mean follow-up of 49.7 ± 21.8 months (range 24 to 102 months). The incidence of varus recurrence was different according to WBL ratio category: 10/10 (100.0%) in undercorrection; 16/33 (48.5%) in insufficient correction; 13/58 (22.4%) in planned correction; and 1/47 (2.1%) in overcorrection. Based on logistic regression analysis, insufficient correction and preoperative valgus stress angle were found to be significant risk factors (P = .038, and .008, respectively). With valgus stress angle <2°, 7 of 10 insufficient correction cases showed varus recurrence (P = .005). However, HSS scores did not differ according to varus recurrence (P = .363). CONCLUSION: Insufficient correction and preoperative medial tightness increased the risk of varus recurrence. Especially in cases where preoperative valgus stress angle was <2°, insufficient correction was strongly associated with varus recurrence. However, no significant differences in clinical outcomes were observed according to varus recurrence in the midterm. LEVEL OF EVIDENCE: III, retrospective cohort study.