Relative Percentage Of Extrusion Research Articles

Medial meniscus extrusion as a predictor for a poor prognosis in patients with spontaneous osteonecrosis of the knee

BackgroundRisk factors for the progression of spontaneous osteonecrosis of the knee (SONK) remain unclear. The purpose of this study was to investigate the association between magnetic resonance imaging (MRI) findings of the meniscus and the prognosis of SONK. MethodsA total of 78 consecutive patients (female 85%; mean age 75.6 ± 7.2 years old) diagnosed with SONK were included. Of these, 30 patients did not receive surgery within 1 year from the onset of SONK (conservative group), while the remaining 48 patients underwent unicompartmental knee arthroplasty due to worsening of symptoms (UKA group). Using MRI findings obtained within 3 months of the onset, we compared the types of meniscus tear and medial meniscus extrusion between the conservative group and UKA group. We performed a receiver operating characteristics (ROC) analysis to estimate the cut-off value. ResultsPatients in the UKA group showed greater medial meniscus extrusion (absolute value, 4.2 mm ± 1.9 vs. 2.8 mm ± 1.2, P = 0.001; relative percentage of extrusion (RPE), 45.7% ± 21.5 vs. 30.7% ± 12.9, P = 0.001) and a higher prevalence of radial tear (P = 0.021) than those in the conservative group. In the multivariate analysis, RPE remained a relevant independent factor (P = 0.035) for future UKA. An ROC analysis found that the cut-off point of RPE was 33% (sensitivity, 81.2%; specificity, 63.3%). ConclusionRPE was a predictor of the prognosis of patients who underwent UKA within 1 year after the onset of SONK. Our results suggest that patients with RPE ≥ 33% are at high risk for progression.

Can an injured discoid lateral meniscus be returned to the correct anatomic position and size of the native lateral meniscus after surgery?

BackgroundNo previous studies have compared the position and size of the remaining discoid lateral meniscus (DLM) with that of a normal lateral meniscus. This study aimed to evaluate the postoperative position and size of DLM compared with that of normal controls using magnetic resonance imaging (MRI). MethodsThis retrospective study involved 52 symptomatic complete type DLMs (discoid group) who underwent arthroscopic surgery and 50 normal controls (control group). Pre- and postoperative MRI evaluations, height, width, and relative percentage of extrusion (RPE) were assessed. Sagittal position parameters, including distances from articular cartilage center to anterior meniscus (CAMD) and from anterior articular cartilage margin to anterior horn (ACMD), were also assessed. Logistic regression analysis was performed to find factors with extrusion of remaining DLM. ResultsThe height of the discoid group was significantly lower than that of the control group (P = 0.000). RPE in the discoid group was significantly larger than in the control group (P = 0.005). Only CAMD and ACMD in the discoid group were different (positioned more anteriorly) from the control group (P = 0.000). Preoperative meniscal shift (odds ratio (OR): 12.448; P = 0.003) and operative technique, especially partial meniscectomy with repair (OR: 19.125; P = 0.000), were the major factors associated with extrusion. ConclusionThe width of remaining DLM was comparable to that of normal controls, but the position was found to be more anterior and lateral than that of normal controls. Preoperative meniscal shift and combined meniscus repair were the major factors for smaller width and greater extrusion; thus, surgeons should address and counsel these factors before surgery.

Correlation analysis of potential factors influencing graft maturity based on MRI after lateral meniscal allograft transplantation

The aim of this respective study was to assess the graft signal/noise quotient (SNQ) value and associated factors based on magnetic resonance imaging (MRI) after lateral meniscal allograft transplantation (LMAT). Patients with LMAT were included. The SNQ, width of the anterior horn (WAH), width of the midbody (WMB), width of the posterior horn (WPH) of each lateral meniscus, coronal graft extrusion (CGE), the anterior cartilage meniscus distance (ACMD) and the posterior cartilage meniscus distance (PCMD) were measured using MRI and tested by multivariate stepwise regression analysis. The relative percentage of extrusion (PRE) was calculated. Seventy-one male patients were examined, and 7 patients were lost to follow-up. The SNQ of the meniscus increased from immediately after surgery to 6 months postoperatively, decreased from 6 to 12 months, increased from 12 to 24 months, and increased from 24 to 36 months. The mean SNQ had a significant negative association with the WPH and CGE at 6 months (p < 0.05), the WPH at 1 year (p < 0.05), the PRE of CGE (CPRE) at 2 years (p < 0.05), and the PCMD, CPRE, and PRE of the PCMD (PPRE) at 3 years (p < 0.01) postoperatively. Multivariate stepwise regression analysis showed that the WPH at 6 months, WPH at 1 year, WMD and PCMD at 2 years, and WMD, ACMD and CGE at 3 years were significant independent factors correlated with the mean SNQ of grafts in different periods. Maturation of meniscal grafts fluctuated with time. The maturation process occupied the main role before 1 year postoperatively, but after the maturation process, tearing of the meniscal allograft played the leading role. Changes in an allograft’s location had an obvious association with the SNQ. The WPH influenced the graft SNQ value at 6 months and 1 year postoperatively, but after the maturation process, the WMB and graft extrusion played the same roles.

A Novel Arthroscopic Classification of Degenerative Medial Meniscus Posterior Root Tears Based on the Tear Gap.

Background:Degenerative medial meniscus posterior root tears (MMPRTs) are reportedly associated with medial compartment osteoarthritis and meniscal extrusion with a displaced gap from the root insertion. However, degenerative MMPRTs have not yet been clearly classified according to arthroscopic findings.Purpose:To classify degenerative MMPRTs according to the tear gap and to investigate how the classification could reflect the joint condition properly.Study Design:Cohort study; Level of evidence, 3.Methods:Patients who underwent arthroscopic surgery, performed by a single orthopaedic surgeon, for degenerative MMPRTs between August 2006 and February 2017 were included. MMPRTs were classified according to tear patterns observed during arthroscopic surgery (type 1, incomplete root tear; types 2-5, complete root tears), with each type further divided by the size of the tear gap, defined as the degree of tear displacement from the root (type 2, no gap or overlapped; type 3, gap of 1-3 mm; type 4, gap of 4-6 mm; type 5, gap of ≥7 mm). We compared preoperative factors, including the Kellgren-Lawrence (K-L) grade, absolute extrusion, relative percentage of extrusion (RPE), tear gap on magnetic resonance imaging (MRI), and mechanical alignment, as well as intraoperative factors, including chondral wear at surgery, between each MMPRT type.Results:A total of 116 root tears were categorized according to this classification: type 1, 16.4% (19 knees); type 2, 9.5% (11 knees); type 3, 40.5% (47 knees); type 4, 25.0% (29 knees); and type 5, 8.6% (10 knees). Chondral wear of the medial femoral condyle (MFC) (P = .001), K-L grade (P = .001), meniscal extrusion (P = .001), and tear gap on MRI (P = .001) showed a tendency to increase with a higher tear type. Chondral wear (ρ for MFC = 0.388; ρ for MTP = 0.311), K-L grade (ρ = 0.390), and meniscal extrusion (ρ for absolute extrusion = 0.500; ρ for RPE = 0.451) showed a moderate correlation with tear type, whereas tear gap on MRI (ρ = 0.907) showed a strong correlation with tear type.Conclusion:Our study introduces a new classification based on the tear gap that can concisely describe a degenerative MMPRT. The classification system demonstrated that a higher tear type (increasing displacement of the tear gap in arthroscopic surgery) is associated with higher meniscal extrusion, severe chondral wear, and greater severity of arthritis.

Medial meniscal extrusion and spontaneous osteonecrosis of the knee

PurposeCauses of spontaneous osteonecrosis of the knee (SONK) have not been clearly elucidated. This study investigated the relationship between medial meniscal extrusion and SONK. MethodsWe reviewed 108 SONK knees and determined their Aglietti stage. Meniscal extrusion is defined when it extends beyond the medial margin of tibial plateau and osteophytes are excluded for determining the margin. Both absolute extrusion (AE) and relative percentage of extrusion (RPE) were measured, and meniscal tear patterns were evaluated in the early stages of SONK (I and II). ResultsAll knees had meniscal extrusion. Stage I was detected in 39 knees; II, in 23; III, in 16; IV, in 18; and V, in 12. The mean AE and RPE were 4.2 mm and 42% in stage I, 5.0 mm and 52% in stage II, 6.8 mm and 71% in stage III, 7.0 mm and 69% in stage IV, and 7.8 mm and 80% in stage V, respectively. The knees in the early stages showed less AE and RPE than those in late stages IV (p < 0.05) and V (p < 0.01). Additionally, the level of AE (ρ = 0.63, p < 0.0001) and RPE (ρ = 0.58, p < 0.0001) correlated with the SONK stage. Of knees with early-stage SONK, 12 knees had no tear, 26 had horizontal tears, 1 had longitudinal tear, 6 had degenerative tears, 2 had radial tears, 1 had complex tear, and 14 had root tears. Neither AE nor RPE differed significantly among tear patterns. ConclusionsMeniscal extrusion was recognized even in early stages, with a significant correlation between the SONK stage and extrusion. Although the most frequent tear pattern in early-stage SONK was horizontal tear, 12 knees had meniscal extrusion with no tears. Therefore, meniscal extrusion, which indicates meniscal dysfunction, may be a cause of SONK and be related with the developmental stage of SONK.

Midbody of the medial meniscus as a reference of preservation in partial meniscectomy for complete discoid lateral meniscus.

To evaluate the postoperative size of discoid lateral meniscus using magnetic resonance imaging (MRI) after partial meniscectomy relative to the size of medial meniscus midbody. This study included 48 patients who underwent arthroscopic partial meniscectomy with or without repair for symptomatic complete discoid meniscus. The intraoperative size of midbody of medial meniscus was used as a reference for partial meniscectomy. MRIs were performed pre- and postoperatively. Quantitative evaluations of the height, width, extrusion of the meniscus, and relative percentage of extrusion in the coronal and sagittal planes were completed. Demographic data, preoperative shift, type of shift, and operative technique were analyzed while considering the remaining meniscus. Logistic regression analyses were used. The mean remaining discoid meniscal width in the coronal plane of MRI was not significantly different from the width of midbody of medial meniscus (9.1 ± 4.2mm vs. 9.4 ± 1.4mm, n.s.) Absolute meniscal extrusion and relative percentage of extrusion in the coronal plane and the ratio of t meniscus in sagittal plane of the final MRI were significantly increased as compared with the preoperative MRI. Preoperative shift was a risk factor for the reduction of remaining meniscal width (odds ratio 11.997, p = 0.016, 95% CI 1.586-90.737). The size of midbody of medial meniscus could be a reference for partial meniscectomy in symptomatic complete discoid meniscus. Preoperative shift represents a risk factor for decreased remaining meniscal width. These findings could be helpful in ensuring appropriate surgical planning and explaining poor prognostic factors. Prospective cohort study, Level II.

L’arthrose du compartiment fémoral tibial médial précède la lésion de la racine méniscale médiale exprimée par un épisode douloureux soudain

BackgroundAn event of painful popping is a highly predictive clinical sign of medial meniscal posterior root tears (MMPRTs) in middle-aged to older patients. There are lack of studies about the prevalence of a painful popping event and the condition of the medial compartment at the time of popping event in MMPRTs. HypothesisWe hypothesized that most of MMPRTs with a single painful popping event would show pre-existed pathologic medial meniscal extrusion (MME) and articular cartilage degeneration, and larger contact area of medial femoral condyle to medial tibial plateau could affect the MME. In addition, MME would be correlated with knee osteoarthritis. Patients and MethodsThirty-eight patients (mean age 58.5±10.5) who had painful popping within 3 weeks were included. On MRIs, absolute MME, relative percentage of extrusion (RPE), MME-medial femoral condyle (MFC)/medial tibial condyle (MTC) at 0̊ ratio, and medial compartments’ Modified Outerbridge Scale (MOS) were evaluated. Kellgren-Lawrence (K-L) grade was also assessed. ResultsThe MME parameters including absolute MME, RPE, and the ratio between MME and MFC/MTC at 0̊ were 2.9±1.2mm, 22.0±10.3%, and 3.2±1.3. Patients with MOS and K-L grade≥2 were 33 (86.8%) and 32 (84.2%). Patients were divided into MME ≥3mm (group G, n=20) and MME<3mm (group L, n=18). The MME parameters were significantly greater in group G than group L (all, p<0.001). The group G had worse osteoarthritis progression in terms of MOS and K-L grade than the group L (p=0.035 and 0.077, respectively) MME≥3mm showed significantly association with MOS≥3 (p=0.045). DiscussionMore than 80% of MMPRT patients with an event of painful popping within 3 weeks showed that medial compartment degeneration preceded the event of popping. Therefore, identification of MME and articular cartilage degeneration at the time of painful popping in MMPRTs could be helpful when the surgeon determines the most appropriate treatment. Level of EvidenceIV, Case-series.

Medial knee osteoarthritis precedes medial meniscal posterior root tear with an event of painful popping

BackgroundAn event of painful popping is a highly predictive clinical sign of medial meniscal posterior root tears (MMPRTs) in middle-aged to older patients. There are lacks of studies about the prevalence of a painful popping event and the condition of the medial compartment at the time of popping event in MMPRTs. HypothesisWe hypothesized that most of MMPRTs with a single painful popping event would show pre-existed pathologic medial meniscal extrusion (MME) and articular cartilage degeneration, and larger contact area of medial femoral condyle to medial tibial plateau could affect the MME. In addition, MME would be correlated with knee osteoarthritis. Patients and methodsThirty-eight patients (mean age 58.5±10.5) who had painful popping within 3 weeks were included. On MRIs, absolute MME, relative percentage of extrusion (RPE), MME-medial femoral condyle (MFC)/medial tibial condyle (MTC) at 0° ratio, and medial compartments’ Modified Outerbridge Scale (MOS) were evaluated. Kellgren-Lawrence (K-L) grade was also assessed. ResultsThe MME parameters including absolute MME, RPE, and the ratio between MME and MFC/MTC at 0° were 2.9±1.2mm, 22.0±10.3%, and 3.2±1.3. Patients who with MOS and K-L grade≥2 were 33 (86.8%) and 32 (84.2%). Patients were divided into MME≥3mm (group G, n=20) and MME<3mm (groupL, n=18). The MME parameters were significantly greater in group G than group L (all, p<0.001). The group G had worse osteoarthritis progression in terms of MOS and K-L grade than the group L (p=0.035 and 0.077, respectively) MME≥3mm showed significantly association with MOS≥3 (p=0.045). DiscussionMore than 80% of MMPRT patients with an event of painful popping within 3 weeks showed that medial compartment degeneration preceded the event of popping. Therefore, identification of MME and articular cartilage degeneration at the time of painful popping in MMPRTs could be helpful when the surgeon determines the most appropriate treatment. Level of evidenceIV, Case-series.

The effects of graft shrinkage and extrusion on early clinical outcomes after meniscal allograft transplantation

BackgroundGraft shrinkage or radial extrusion is a reported complication after meniscus allograft transplantation (MAT). Whether shrinkage or extrusion progress after surgery and whether they are associated with the clinical outcome of MAT remain debatable. In this study, graft shrinkage and extrusion were measured in the coronal and sagittal planes using serial postoperative magnetic resonance imaging (MRI). The purpose of this study was to evaluate if graft shrinkage or extrusion is correlated to the clinical outcome of MAT.MethodsMRIs acquired at 3 and 12 months postoperatively in 30 patients (21 men and 9 women) who underwent MAT (6 medial and 24 lateral menisci) from 2010 to 2016 were analyzed. Two orthopedic surgeons and two musculoskeletal specialized radiologists each performed the MRI measurements. Allograft shrinkage was measured by the width and thickness of the graft at the coronal and sagittal planes. To determine the graft extrusion, distances between the proximal tibia cartilage margin and the extruded graft margin were measured in both coronal (either lateral or medial) and sagittal (both anterior and posterior) plane and relative percentage of extrusion (RPE) were calculated. Subjective International Knee Documentation Committee (IKDC) scores at 12 months were evaluated as a clinical outcome measurement, and correlations between shrinkage or extrusion of allograft and IKDC score were analyzed.ResultsIn the coronal plane, radial RPE averaged 43.6% at postoperative 3 months, but there was no significant progression of extrusion at 12 months (average 42.0%) (P = 0.728). In the sagittal plane, there were no significant progressions of anterior and posterior RPE (P = 0.487 and 0.166, respectively) between postoperative 3 and 12 months. Shrinkage was calculated by multiplying the width and height of the three sections and summing these values. There was no significant progression of shrinkage between postoperative 3 and 12 months (P = 0.150). RPE in the radial (R = 0.147, P = 0.525), anterior (R = 0.249, P = 0.264), and posterior (R = 0.230, P = 0.315) directions and shrinkage (R = 0.176, P = 0.435) were not correlated to IKDC score at postoperative 12 months.ConclusionsIn the coronal and sagittal planes, extrusion and shrinkage did not progress from 3 months to 1 year. Extrusion and shrinkage had no correlation with early clinical outcomes. This finding suggests that graft extrusion or shrinkage may be not a great concern especially in early postoperative period of MAT, and multiple, serial MRI may be not necessary.

Delayed Rehabilitation After Lateral Meniscal Allograft Transplantation Can Reduce Graft Extrusion Compared With Standard Rehabilitation

Background: Meniscal extrusion prevention would be important for restoring normal knee kinematics, even though the effect of graft extrusion after meniscal allograft transplantation (MAT) has not been clearly identified. Hypothesis: When compared with standard rehabilitation protocols, delayed rehabilitation after lateral MAT could reduce graft extrusion. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 53 patients who underwent lateral MAT with the keyhole technique from June 2011 to March 2015 were included. Graft extrusion and lateral compartment articular cartilage loss on magnetic resonance imaging, joint space width (JSW) on weightbearing radiographs, and clinical outcomes (including subjective scores and functional tests) of 25 patients who underwent standard rehabilitation (group S) after lateral MAT were compared with those of 28 patients who underwent delayed rehabilitation (group D), which included immobilization during the first 3 weeks and use of unloading braces for 9 weeks. Results: Mean ± SD follow-up times for groups S and D were 25.7 ± 6.4 and 24.5 ± 7.1 months, respectively. Although the postoperative clinical outcomes did not differ between the groups, graft extrusion (3.2 ± 1.5 mm vs 1.8 ± 1.6 mm) and relative percentage of extrusion (32.2% ± 14.6% vs 17.3% ± 16.6%) were greater in group S than in group D (P < .001 for both). The percentage of patients with graft extrusion (≥3 mm) was 52% in group S and 21.4% in group D. JSWs on Rosenberg view decreased by 0.1 mm in group S but increased by 0.3 mm in group D (P = .035). Kellgren-Lawrence grade and modified Outerbridge grade progressed by 44% and 44% among patients in group S and by 17.9% and 21.4% among patients in group D, respectively. There were significant correlations between the coronal graft extrusion and postoperative JSWs on full extension (–0.452) and Rosenberg (–0.410) views, Kellgren-Lawrence grade (0.727), and modified Outerbridge grade (0.732) on magnetic resonance imaging (P < .001 for all). Conclusion: Compared with standard rehabilitation, delayed rehabilitation showed less coronal graft extrusion and joint space narrowing on weightbearing and reduced the progression of arthrosis, although the rehabilitation protocols showed no differences in clinical outcomes.

Clinical and radiologic outcomes after a modified bone plug technique with anatomical meniscal root reinsertion for meniscal allograft transplantation and a minimum 18-month follow-up

ObjectiveTo evaluate the clinical and radiologic outcomes of meniscal allograft transplantation (MAT) using a modified bone plug technique.MethodsWe conducted a retrospective single-center study of 73 patients who underwent MAT between January 2007 and December 2013. The International Knee Documentation Committee (IKDC) score, Lysholm score, Tegner score, visual analogue scale (VAS), and physical examinations were retrospectively reviewed to measure clinical outcomes after MAT, and questionnaires regarding activity and factors were analyzed. Magnetic resonance imaging (MRI) was used to assess the cartilage status and meniscal extrusion.ResultsThe mean follow-up was 37 months for 61 patients (65 knees), and 12 patients were lost to follow-up. The mean meniscal extrusion was 3.39 ± 0.90 mm, the relative percentage of extrusion (RPE) was 34.82% ± 12.71%, and arthrosis progression was observed in 8 of 61 cases (13.1%). The mean results for VAS, IKDC, and Lysholm scores were significantly improved after MAT (P < 0.05), but there were no significant differences in the range of motion or Tegner score (P > 0.05). Thirty-eight (62.3%) patients were able to return to their previous level of activity, and 23 (37.7%) patients reached a mean 76.7% of the previous level of activity. Of the 23 patients reporting a decrease in activity, 10 reported a fear of reinjury as the primary factor limiting activity. The patient satisfaction rate in the study was 78.7%.ConclusionOur modified bone plug method with anatomical meniscal root reinsertion was an effective surgical method, and the majority of active patients with meniscal disorders returned to preinjury levels of activity.

Incidence and Extent of Graft Extrusion following Meniscus Allograft Transplantation.

Background The incidence and extent of graft extrusion after meniscus allograft transplantation (MAT) may differ in patients undergoing medial and lateral meniscus transplantation due to the use of different surgical techniques. This meta-analysis was therefore designed to quantify the extent and incidence of graft extrusion after meniscus allograft transplantation. Methods Following preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines, all studies reporting absolute extrusion, relative percentage of extrusion (RPE), or frequency of major extrusions (>3 mm) on magnetic resonance imaging in patients undergoing medial or lateral MAT were included. Results The pooled mean absolute extrusion following all MATs was 3.15 mm but was significantly greater following medial than lateral MAT (3.26 versus 3.01 mm; p = 0.001). The pooled mean RPE following all MATs was 32.79% and was significantly greater after medial than lateral MAT (32.69% versus 28.81%; p < 0.001). The pooled mean proportion of knees with major (>3 mm) extrusion was 53% (95% CI: 49% to 58%) and was significantly greater after medial than lateral MAT (61% versus 39%; p < 0.001). Conclusion Mean graft extrusion after arthroscopic assisted MAT using bony fixation was 3.2 mm, with major graft extrusion > 3 mm occurring in about 50% of transplanted menisci. Graft extrusion was significantly greater after medial than lateral MAT.

Meniscal Extrusion Does Not Progress During the Midterm Follow-up Period After Lateral Meniscal Transplantation

Background: Meniscal extrusion is related to degeneration of the native knee joint. However, the clinical effect of the phenomenon after meniscal allograft transplantation (MAT) has not been clearly identified. Purpose/Hypothesis: The purpose of this study was to evaluate the change in meniscal extrusion in both the coronal and sagittal planes after lateral MAT through the midterm follow-up period. We hypothesized that meniscal extrusion does not progress during the midterm follow-up period. Study Design: Case series; Level of evidence, 4. Methods: A total of 46 patients with a mean follow-up of 51.1 ± 7.1 months were included in the study. The patients underwent lateral MAT using the keyhole technique. Postoperative magnetic resonance imaging (MRI) was performed at 6-week, 1-year, and midterm (3- to 5-year) follow-up. In the coronal plane, the absolute value of meniscal subluxation and the relative percentage of extrusion (RPE) were measured. In the sagittal plane, meniscal subluxation was measured as the absolute and relative anterior cartilage meniscal distance (ACMD) and posterior cartilage meniscal distance (PCMD). The joint-space width (JSW) on weightbearing radiographs with 2 different knee positions was measured preoperatively and at 1-year and midterm follow-up. The Lysholm score was assessed at the same time points. Results: In the coronal plane, the mean absolute meniscal extrusion at 6-week, 1-year, and final follow-up was 2.90 ± 0.94, 2.85 ± 0.97, and 2.83 ± 0.89 mm, respectively, and the mean RPE was 27.0% ± 9.4%, 27.1% ± 10.1%, and 27.8% ± 9.7%, respectively. There were no statistically significant differences in absolute and relative coronal extrusion among the 3 time periods (P > .05). The percentage of patients with meniscal extrusion (≥3 mm) was 37.0% at 6-week follow-up and 34.8% at 1-year and final follow-up. In the sagittal plane, the mean absolute ACMD was 2.59 ± 1.75, 2.58 ± 1.85, and 2.37 ± 1.60 mm, respectively, and the mean relative ACMD was 20.7% ± 13.1%, 20.6% ± 13.8%, and 19.0% ± 12.2%, respectively, at the 3 follow-up time points. The mean absolute PCMD was −1.23 ± 3.34, −1.28 ± 3.08, and −1.42 ± 2.77 mm, respectively, and the mean relative PCMD was −10.3% ± 25.9%, −11.0% ± 24.6%, and −12.2% ± 23.2%, respectively, at the same time points. Sagittal extrusion was not significantly different between the time points (P > .05). The mean JSW at 2 days preoperatively, 1 year postoperatively, and midterm follow-up was 5.40 ± 1.07, 5.44 ± 1.04, and 5.43 ± 0.98 mm, respectively, on anterior-posterior radiographs with full extension, and it was 4.90 ± 0.94, 4.94 ± 0.98, and 4.89 ± 0.96 mm, respectively, on posterior-anterior radiographs with 45° of flexion. The mean JSW values were not significantly different between the 3 different time points (P > .05). The mean preoperative Lysholm score was 58. 9 ± 8.3; the score increased to 90.4 ± 9.7 at 1 year postoperatively and 90.5 ± 10.1 at final follow-up, which is a significant improvement compared with the preoperative status (P < .05). There was no statistically significant difference between the scores at the 2 postoperative time points (P > .05). Conclusion: This study demonstrated that extrusion of the meniscal allograft did not significantly progress either in the coronal or sagittal plane after lateral MAT during the midterm follow-up period.

Risk Factors Associated With Knee Joint Degeneration After Arthroscopic Reshaping for Juvenile Discoid Lateral Meniscus

Background: Although arthroscopic meniscal reshaping for discoid lateral meniscus (DLM) has better outcomes than total or subtotal meniscectomy, degenerative changes on radiographs are still seen in some patients with meniscal reshaping. Purpose: To assess the risk factors associated with knee joint degeneration after reshaping surgery for juvenile DLM. Study Design: Case-control study; Level of evidence, 3. Methods: Forty patients (45 knees) with a mean age of 12.0 years who underwent arthroscopic meniscal reshaping for DLM were enrolled at a mean of 39.6 months after surgery. For all patients, meniscal saucerization was performed first. Then, if the residual meniscus was unstable, stabilization was provided with suture fixation. At final follow-up, we obtained radiographs to assess degenerative changes to the knee joint using the classification by Tapper and Hoover. Residual meniscal width and meniscal extrusion (defined as a relative percentage of extrusion [RPE]) were measured with magnetic resonance imaging (MRI). Then, the correlation between radiographic evidence of degenerative changes (Tapper and Hoover grade), residual meniscal width, and RPE were assessed with Pearson and Spearman correlation analyses. Logistic regression analysis was used to examine whether preoperative characteristics correlated with degeneration and residual meniscal width. Results: The mean residual meniscal width was 4.6 mm (range, 3.8-6.0 mm), and the mean ± SD RPE was 25.5% ± 21.8% at the final follow-up. There were 28 knees with Tapper and Hoover grade 0, 10 knees with grade 1, and 7 knees with grade 2. The residual meniscal width and RPE were significantly correlated with Tapper and Hoover grade (ρ = −0.489, P = .0007; ρ = 0.414, P = .005, respectively). The residual meniscal width was also significantly correlated with RPE (r = −0.416, P = .004). The receiver operating characteristic curve showed that a 5.0-mm residual meniscal width was the cutoff value leading to evidence of degeneration. Multiple logistic regression analysis showed that an anterocentral shift on preoperative MRI was a risk factor for degeneration (odds ratio, 27.2; 95% CI, 1.1-360.5; P = .012) and residual meniscal width less than 5.0 mm (odds ratio, 20.9; 95% CI, 1.5-281; P = .022). Conclusion: Smaller meniscal width and greater severity of meniscal extrusion correlated with knee joint degeneration. An anterocentral shift on preoperative MRI was a risk factor for degenerative changes and smaller residual meniscal width.

Risk Factors for Radiographic Progression of Osteoarthritis After Meniscus Allograft Transplantation

To identify risk factors that predict radiographic progression of osteoarthritis after meniscus allograft transplantation (MAT) using multivariate logistic regression. Inclusion criteria were consecutive patients who underwent medial or lateral MATs from January 2005 to September 2012 by one surgeon. Exclusion criteria were lack of postoperative magnetic resonance image, loss to follow-up for a minimum of 3years, and simultaneous surgery on articular cartilage or the anterior cruciate ligament. According to the change of Kellgren-Lawrence (KL) grade at the mean final follow-up of 56.2months, the enrolled MATs were sorted into the no progression of osteoarthritis (NOA) and progression of osteoarthritis (POA) groups. Multivariate logistic regression was used to analyze risk factors, including age, sex, body mass index, time from previous meniscectomy to MAT, extent of previous meniscectomy, previous anterior cruciate ligament reconstruction, knee alignment angle, KL grade, side of transplanted meniscus, Outerbridge grade, posterior repair technique, and relative percentage of extrusion. In comparison between the NOA (n= 38) and the POA (n= 31) groups, a significant risk factor for radiographic progression of osteoarthritis after MAT was medial MAT compared with lateral MAT. Medial MAT compared with lateral MAT was also a significant risk factor (adjusted odds ratio, 3.763; 95% confidence interval, 1.212-11.683). Patients need to be counseled about the increased risk of osteoarthritis progression after MAT over time, particularly for medial MAT. Level III, retrospective case control study.

Various factors contribute to graft extrusion in lateral meniscus allograft transplantation.

Lateral meniscus allograft transplantation (LMAT) is a feasible surgical option for young meniscus-deficient patients. Although several studies have explored the factors that contribute to graft extrusion, they have not been fully elucidated. The aim of this study was to determine the various factors that contribute to graft extrusion. Patients with knees that had received LMAT using a keyhole technique (n=87 knees in 82 patients) were reviewed. The median age of these patients was 22years (range 19-54years), and the median postprocedural follow-up interval was 5days (range 1-136days). Twelve magnetic resonance imaging (MRI) measurement parameters (axial and coronal location of the bone block) that could potentially influence graft extrusion were evaluated, along with absolute graft extrusion and relative percentage of extrusion (RPE). A significant correlation was found between 8 of the 12 MRI measurement parameters and both the absolute extrusion and RPE (r=0.241-0.438, p<0.05). The absolute middle distance and depth of the bone block were independent predictors of the absolute extrusion (β=0.30 and 0.15, respectively; p<0.05), and the relative middle distance and relative bone-block elevation were found to be predictors of RPE (β=2.29 and 1.44, respectively; p<0.05). The rate of graft extrusions after LMAT was high in this study. Both the coronal and axial locations of the bone block were found to influence graft extrusion in LMAT. Therefore, correct positioning of the bone block, including in both the axial and coronal planes, is essential to minimize graft extrusion. Future studies need to investigate the long-term clinical outcome and longevity of extruded menisci after transplantation. Therapeutic case series, Level IV.

An Osteophyte in the Tibial Plateau Is a Risk Factor for Allograft Extrusion After Meniscus Allograft Transplantation

Background: Osteophytes can be observed on the tibial plateau during meniscus allograft transplantation (MAT). However, no studies to date have evaluated the effect of these osteophytes on meniscus allograft extrusion. Hypothesis: Osteophyte excision in the tibial plateau could reduce extrusion of the transplanted meniscus and improve short-term clinical outcomes with meniscus allograft transplantation. Study Design: Cohort study; Level of evidence, 3. Methods: Between October 2004 and July 2012, a total of 323 patients underwent MAT at a single institution. Of these, 88 patients had a peripheral osteophyte in their tibial plateau, and they were enrolled in the study retrospectively. The mean age of the patients was 35.3 years (range, 15-56 years); there were 57 male and 31 female patients. Forty-four patients underwent osteophyte excision concomitantly with MAT and 44 patients underwent MAT only. The 2 groups showed no difference in terms of age, body mass index, time after meniscectomy, and preoperative knee scores. A medial meniscus allograft was transplanted in 13 cases (15%) and a lateral meniscus in 75 (85%). The absolute extrusion and relative percentage of extrusion were measured to evaluate allograft extrusion 12 months after MAT. The modified Lysholm scoring system and the Hospital for Special Surgery score at 2 years after MAT were used to evaluate clinical outcomes. Results: The mean absolute extrusions at 1 year postoperatively in the excision and nonexcision groups were 3.5 ± 1.5 and 5.5 ± 1.6 mm, respectively. The mean relative percentages of extrusion were 34.1% ± 15.9% and 54.7% ± 20.7%, respectively. The rates of allograft extrusion (>3 mm) were 28 of 44 (63.6%) and 41 of 44 (93.2%) in the excision and nonexcision groups, respectively. The intergroup differences in absolute extrusion, relative percentage of extrusion, and rate of allograft extrusion were statistically significant (P < .001 for all 3 parameters). There were no significant differences in the clinical outcomes (modified Lysholm or Hospital of Special Surgery scores) at 2-year follow-up (P < .762 and < .298, respectively). Conclusion: The excision of a peripheral osteophyte larger than 2 mm in the proximal tibial plateau was associated with less allograft extrusion after MAT.

A systematic review of the incidence and clinical significance of postoperative meniscus transplant extrusion.

To determine the incidence and clinical significance of postoperative meniscus transplant extrusion. A systematic search was performed using PubMed and Cochrane online databases. Inclusionary criteria were English language, clinical trials of meniscus transplantation published from 1984 to 2014, and meniscus extrusion measured on magnetic resonance imaging (MRI). Twenty-three studies were included, in which 814 menisci were implanted into 803 patients. MRIs were obtained from 2 days to 10 years postoperatively. Eighteen studies used fresh-frozen meniscus transplants implanted with bone (n = 612) or suture fixation (n = 116); four studies, cryopreserved transplants; and one, irradiated transplants. Three measurements assessed extrusion: absolute millimeters of extrusion (0-8.8 mm), relative percentage of extrusion (0-100%), and the percent of transplants that were extruded (0-100 %). Relationships between transplant extrusion and clinical rating scales, joint space narrowing on standing radiographs, and arthrosis progression were inconclusive. Non-anatomic placement of lateral meniscus transplants and suture fixation of medial and lateral transplants were associated with greater extrusion in two studies. Inconsistencies among studies prevent conclusions regarding the incidence and clinical significance of meniscus transplant extrusion. Even so, the short- to mid-term results were encouraging for knee function with daily activities and low rates of failure requiring transplant removal. A postoperative MRI showing more than 3-mm extrusion occurring in some studies suggested technique and/or implant sizing problems that required correction. Future studies should report absolute transplant extrusion, relative percent of extrusion, percent of transplant within the tibiofemoral compartment, and the percent of transplants that are extruded. IV.

Clinical and Radiologic Outcomes After Meniscus Allograft Transplantation at 1-Year and 4-Year Follow-up

To assess the clinical and radiologic outcomes of meniscus allograft transplantation (MAT) with serial evaluation at 1 year and at 4 years. Among 151 patients who received MAT between March 2006 and June 2009, we prospectively recruited the patients who had undergone clinical and radiologic examinations at 1 year after the operation. The Lysholm score, International Knee Documentation Committee score, and Knee Society Score were determined. Plain radiography was used for evaluation of osteoarthritis, and magnetic resonance imaging (MRI) was used to assess the cartilage status and meniscal extrusion. Thirty-nine patients with a mean age of 40 ± 9 years were recruited. The first visit was conducted at a mean of 13.6 months (range, 11 to 17 months) postoperatively, and the last visit was conducted at a mean of 50.4 months (range, 48 to 72 months) postoperatively. Of the patients, 29 were men. The lateral side was involved in 27 patients. The Lysholm knee score increased to a median value of 89 (range, 75 to 100) at the first visit and 88 (range, 76 to 100) at the second visit from a preoperative median value of 79 (range, 37 to 99), which was statistically significant according to the Kruskal-Wallis test. According to the Kellgren-Lawrence grade based on anteroposterior radiographs, 21 patients (54%) showed no arthrosis progression and the overall status of arthrosis on anteroposterior radiographs was significantly changed (P < .001). On MRI, 25 patients (64%) showed no cartilage status change and the overall status was not changed significantly (P = .178). The meniscal extrusion extent was 4.2 ± 0.4 mm at the first visit and 4.2 ± 0.6 mm at the second visit (P = .678), and the relative percentage of extrusion was 0.44 ± 0.16 and 0.51 ± 0.21, respectively (P = .059). The subgroup in which arthrosis had progressed on MRI showed a larger amount of change in the relative percentage of extrusion (P = .023). No correlation was observed between meniscal extrusion and various outcomes. Repeat assessment at 4 years showed that MAT showed improvement in knee function, but it had decreased over time. Considerable meniscal extrusion was observed, but it did not increase during follow-up and did not show any correlation with other outcomes. Extrusion progression showed significant correlation with arthrosis progression. Level IV, therapeutic case series.

Comparative Study on Immediate Versus Delayed Meniscus Allograft Transplantation

Background: Meniscus allograft transplantation (MAT) is generally used for patients who sustain symptoms after meniscectomy, which could be called delayed MAT. Meniscus allograft transplantation for patients immediately after meniscectomy has not been reported. Hypothesis: Compared with the conventional delayed MAT, immediate MAT might provide better clinical results and reduce joint degeneration. Study Design: Cohort study; Level of evidence, 3. Methods: The study was performed with 18 transplanted menisci (6 medial, 12 lateral) from 16 patients. Eight menisci were transplanted immediately after meniscectomy (IM group); 10 menisci, from patients who complained of knee symptoms at a mean time of 35 months (range, 9-92 months) after total meniscectomy, underwent delayed transplantation (DE group). Fourteen patients undergoing meniscectomy during the same period were included as controls (ME group). Degenerative changes in knee joints were evaluated by plain radiographs and magnetic resonance imaging (MRI). Allograft extrusion and relative percentage of extrusion were measured on MRI. Other outcome assessments included preoperative and postoperative International Knee Documentation Committee (IKDC), Tegner, and Lysholm scores; visual analog scale (VAS) for pain; and range of motion and isokinetic muscle strength evaluation. Results: The mean length of follow-up was 50.8 months (range, 44-62 months) for the IM group, 72.0 months (range, 44-94 months) for the DE group, and 54.3 months (range, 45-62 months) for the ME group. A statistically significant difference in favor of the IM and ME groups was found on the VAS (0.4 [IM group] vs 1.1 [ME group] vs 2.5 [DE group]) and muscle strength (P < .05). The mean IKDC score in the IM group was significantly higher than that in the DE group (93 [range, 85-99] vs 74 [range, 38-95], respectively; P < .05). The IM group showed significantly less preoperative to postoperative cartilage degeneration changes on radiographs and MRI when compared with the DE and ME groups (Kellgren-Lawrence score changes: 0.25 [IM group] vs 1.0 [DE group] vs 1.7 [ME group]; Yulish score changes: 0.25 [IM group] vs 1.0 [DE group] vs 1.1 [ME group]; P < .05). Extrusion of the allograft was observed in the body of the menisci in all patients. No significant difference was found in terms of the Lysholm score, Tegner score, joint narrowing, or meniscus extrusion (P > .05). Conclusion: Compared with delayed MAT, immediate MAT led to more satisfactory subjective results, less joint degeneration, and less muscle strength deficits. The short-term results of delayed meniscus transplantation were close to those of meniscectomy.