Midterm Clinical and Radiological Outcomes of Revision Lateral Meniscal Allograft Transplantation.

Background: It is unknown whether the outcomes achieved in the early period after revision lateral meniscal allograft transplantation (RLMAT) are maintained through the midterm period. Purpose: To evaluate the midterm clinical and radiological results of patients who underwent RLMAT. Study Design: Case series; Level of evidence, 4. Methods: We reviewed the outcomes of 19 RLMATs in 18 patients with at least 5 years of follow-up data. The mean follow-up period was 6 ± 1.1 years (range, 5-8.5 years). Clinical outcomes were assessed using the modified Lysholm score, the International Knee Documentation Committee (IKDC) subjective score, and the Tegner activity level. Radiographic progression of arthritis was measured by the absolute and relative joint space widths on 45° of knee flexion posteroanterior radiographs preoperatively, 1 year postoperatively, and at the latest follow-up.Failure was defined as meniscocapsular separation, removal, or tear of more than half of the meniscal allograft on postoperative magnetic resonance imaging (MRI) or conversion to total knee arthroplasty. Of the 18 patients, 3 underwent ≥2 RLMATs. The survival rate was evaluated according to the number of revision surgeries. Results: For knees with an intact meniscus transplant at the final follow-up, the modified Lysholm and IKDC scores were significantly improved compared with preoperatively, but the Tegner activity level was unchanged. No significant differences were found in the absolute and relative joint space widths postoperatively. There were 6 failures within 3 years after RLMAT; the overall 5-year survival rate was 68.4% (13/19 knees). All failed knees showed bucket-handle tear patterns on MRI due to meniscocapsular healing failure. The survival rate decreased as the number of RLMATs increased-73.3% for a first RLMAT (n = 15 knees), 66.7% for a second RLMAT (n = 3 knees), and 0% for a third RLMAT (n = 1 knee). Midterm MRIs of 8 well-healed RLMATs showed evidence of meniscal degeneration; nonetheless, this did not affect clinical outcomes. Conclusion: The midterm results of RLMATs demonstrated a 5-year survival rate of 68.4% and positive clinical and radiological outcomes for failed MATs despite unimproved activity levels. Inadequate meniscocapsular healing was the leading cause of failure, and it needs to be carefully considered when performing RLMATs.

Association of Medial Meniscal Volume With Decreased Joint Space Width After Medial Opening-Wedge High Tibial Osteotomy.

Background: Medial opening-wedge high tibial osteotomy (MOWHTO) reduces contact stress by altering the weightbearing axis from the medial to the lateral compartment, relieves knee pain, and slows the progression of osteoarthritis. Purpose/Hypothesis: To evaluate whether the volume of the medial meniscus affects outcomes after MOWHTO. It was hypothesized that reduced medial meniscal volume would be associated with worse midterm clinical and radiographic outcomes. Study Design: Cohort study; Level of evidence, 3. Methods: Included were 59 patients who underwent MOWHTO and had ≥4 years of follow-up data. The mean follow-up period was 66.5 ± 15.1 months (range, 48-110 months). The cohort was classified into 3 groups according to the status of the medial meniscus on arthroscopic examination before osteotomy: no meniscal tear, degenerative tear leading to partial meniscectomy, and degenerative tear leading to subtotal meniscectomy. The Hospital for Special Surgery score and Knee Society objective and functional scores were compared among the groups at 2 time points (preoperative and latest follow-up), and the medial joint space width (JSW) was compared among the groups at 3 time points (preoperative, 1 year postoperative, and latest follow-up). Results: Overall, 9 patients had no meniscal tear, 20 patients underwent partial meniscectomy, and 30 patients underwent subtotal meniscectomy. The clinical scores improved significantly from preoperatively to the latest follow-up (P ≤ .001 for all), with no significant difference among the groups. Post hoc analysis indicated that at the latest follow-up, JSW was significantly lower in the subtotal meniscectomy group compared with the no-tear group on both 45° of flexion posterior-anterior (2.5 ± 1.3 vs 3.9 ± 1.8 mm; P = .004) and anterior-posterior (3.4 ± 1.1 vs 4.5 ± 0.9 mm; P = .011) radiographs. Conclusion: Subtotal meniscectomy of the medial meniscus performed during arthroscopic examination with MOWHTO was associated with decreased JSW at midterm follow-up. Efforts should be made to preserve the medial meniscus as much as possible during MOWHTO.

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.

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.

Flexion contracture can be relieved by concurrent notchplasty in medial open wedge high tibial osteotomy.

BACKGROUND: Given that medial open wedge high tibial osteotomy (OWHTO) not only delays the progression of osteoarthritis but also alleviates the resulting pain, surgical outcomes would be improved if limited ROM can also be managed. In this regard, the effect of concurrent notchplasty on flexion contracture has not been evaluated. HYPOTHESIS: (1) Concurrent notchplasty in OWHTO would relieve flexion contracture regardless of the severity of osteoarthritis and this effect would be maintained over time, and (2) concurrent notchplasty would not cause any added complications compared to the same procedure without notchplasty. PATIENTS AND METHODS: In total, 107 patients who underwent OWHTO between 2011 and 2017 with a mean follow-up period of 46.6months (range: 24-102months) were reviewed. ROM was measured at three time points as follows: before surgery, at 6-12months postoperatively, and at the latest follow-up. The measurements were analyzed using a linear mixed model in terms of notchplasty and other factors, including age, sex, body mass index, preoperative hip-knee-ankle angle, lateral distal femoral angle, medial proximal tibial angle, correction angle, concurrent meniscectomy, postoperative posterior slope, and Kellgren-Lawrence grade. Then, ROMs at the three time points were compared between the notchplasty and non-notchplasty groups. RESULTS: Of the 107 patients, 47 underwent concurrent notchplasty. The linear mixed model regarding flexion contracture showed a significant notchplasty-by-time interaction (p<0.001). When comparing preoperative flexion contractures between the two groups, a significant difference was found (p<0.001). At 6-12months postoperatively, flexion contractures were relieved regardless of notchplasty; however, the difference between the groups was decreased (p=0.026). At the latest follow-up, flexion contractures were partly aggravated in both groups, but no significant difference was found between the groups (p=0.461). Comparison of flexion contracture between before surgery and at the latest follow-up in each group revealed a significant difference only in the notchplasty group (p<0.001, with notchplasty; p=0.197, without notchplasty). The linear mixed model regarding maximal flexion did not show any factor having a significant interaction with time. There were no surgical complications such as infection, thromboembolic events, and hemarthrosis, in both notchplasty and non-notchplasty groups. CONCLUSION: The preoperative difference in flexion contracture was overcome by adding notchplasty to OWHTO, and this improvement was maintained over time. No added complications were noted in the notchplasty group. The results should be interpreted with caution, considering measurement error of ROM. However, concurrent notchplasty in OWHTO deserves further study to validate its efficacy. LEVEL OF EVIDENCE: III, retrospective cohort study. IRB INFORMATION: Project No. S2020-0081, AMC IRB SOP.

Learning Curve For Lateral Meniscal Allograft Transplantation: Preventing Meniscal Extrusion.

PURPOSE: This study analyzes the large number of lateral meniscal allograft transplantation (LMAT) procedures conducted by a single surgeon over 23 years to determine whether the absolute amount of graft subluxation and the incidence of extrusion are different at the present time compared to the early MAT era. METHODS: We reviewed 320 cases of LMAT performed by a single surgeon between 1996 and 2019. This cohort was chronologically divided into 8 groups (of 40 subjects). The absolute amount of subluxation was measured by the coronal sections of magnetic resonance images taken 1 year after operation. Subluxation by more than 3 mm was considered as extrusion. The graft extrusion learning curve was plotted in each series using the learning curve cumulative summation test (LC-CUSUM). RESULTS: Extrusion incidence was 41.6%, and the mean absolute amount of graft subluxation was 3.4 ± 2.2 mm for all subjects. There were significant between-group differences in extrusion incidence and absolute amount of graft subluxation (extrusion incidence, P < .001; absolute amount of graft subluxation, P < .001), and the extension incidence and graft subluxation decreased from Group I (72.5%, 4.6 ± 1.7) to Group VIII (27.5%, 2.5 ± 2.1). LC-CUSUM analysis signaled that the surgeon had achieved predefined acceptable outcomes in avoiding extrusion after 128 cases. CONCLUSION: The incidence of extrusion and absolute amount of graft subluxation decreased significantly over a period of 23 years, and the surgeon achieved a certain level of proficiency after 128 cases. LEVEL OF EVIDENCE: Level IV, Case series.

Patellar Fracture After Total Knee Arthroplasty With Retention: A Retrospective Analysis of 2954 Consecutive Cases.

BACKGROUND: To the best of our knowledge, there have been no large case studies on patellar fracture after total knee arthroplasty (TKA) with patella retention. METHODS: From 2005 to 2019, 2954 consecutive TKAs with patella retention were retrospectively reviewed. The incidence of patellar fracture was confirmed. Perioperative demographic factors associated with patellar fracture were compared between the nonpatellar fracture control (randomly selected after age and sex matching) and patellar fracture patient groups. To confirm the prognosis of identified patellar fractures, Hospital for Special Surgery knee score, union rates, and complications after treatment were evaluated. Treatment outcomes were compared as per the treatment method, and fracture type was classified by shape. RESULTS: For primary TKAs with patella retention, patellar fracture occurred in 32 of 2883 cases (incidence 1.11%). When comparing the preoperative demographic factors between the patellar fracture and control groups, there was a significant difference in knee flexion of the affected limb. Twenty-three cases were treated nonoperatively, and nine cases were treated operatively. Of the 32 patellar fractures, 28 had confirmed union, and the HSS score at the latest follow-up increased significantly from the preoperative score. The only complication noted after treatment was nonunion in three cases. We found no significant differences in treatment results as per the treatment method and fracture type. CONCLUSION: Patellar fracture after TKA with retained patella is infrequent, with relatively improved clinicoradiological results over those of patellar fracture after TKA with resurfaced patella reported in the literature. The improved results did not differ as per the treatment method and fracture type.