Alignment factors affecting the medial meniscus extrusion increases the risk of osteoarthritis development

Current Rehabilitation Principles Following Meniscus Repairs

PURPOSE OF REVIEW

The purpose of this review is to synthesize current science on meniscus anatomy and biomechanics and repair techniques to create an empirical foundation for postoperative rehabilitation precautions and guidelines, including timelines, clinical and performance-based criteria for return to activity, to maximize both meniscal healing potential and patient recovery.

RECENT FINDINGS

Recent literature has focused on meniscus repair rather than debridement, and rehabilitation protocols should be designed to optimize healing. Complex, unstable tears, like root and radial tears, disrupt hoop stress and warrant a more conservative protocol including 6 weeks of non-weightbearing; however, more stable tears, like ramp and vertical tears, can often weight bear immediately after surgery. All protocols should emphasize early protected joint motion. Return to activity guidelines remain ill-defined but this review explores evidence-based recommendations for timelines, strength and performance testing. Patients typically should wait ≥ 4 months for a return to activity and the presence of joint line tenderness or effusion could be a sign of delayed/failed healing. It is essential for therapists to know the size, type, and location of a meniscus repair to optimize patient outcomes. Guidelines for weight bearing, range of motion, strength training, and return to activity should vary per tear type and repair technique and recovery should be both time- and criteria-based. Return to activity should align with healing time, objective clinical and performance testing, and clinical and imaging exam findings. Future research should aim to optimize repair techniques and rehabilitation protocols, specifically further study on the timing to initiate weightbearing, early motion, and return to activity.

High Tibial Osteotomy Alone Does Not Decrease Medial Meniscus Extrusion in the Setting of Medial Meniscus Posterior Root Tear: A Cadaveric Study

PURPOSE

To investigate whether inducing valgus alignment and shifting the load laterally through high tibial osteotomy (HTO) alone decreases the extent of medial meniscus extrusion (MME) in the setting of medial meniscus posterior root tear (MMPRT) using ultrasound evaluation.

METHODS

Eight fresh-frozen human cadaveric knee specimens were tested using a 6-degree-of-freedom robotic testing system and ultrasound. Each specimen was tested in 5 conditions: (1) intact, (2) MMPRT, (3) medial meniscus repair (MMR), (4) combined medial open-wedge HTO + MMR, and (5) HTO + MMPRT. Measurements were obtained over the medial collateral ligament (central image) and posterior to the medial collateral ligament (posterior image) with a 250-N axial load at 0°, 30°, and 90° of knee flexion. Statistical analysis was performed using a 2-factor repeated-measures analysis of variance.

RESULTS

MME was significantly greater in HTO + MMPRT (0°: 2.44 ± 0.41 mm, 30°: 2.47 ± 0.37 mm, 90°: 2.41 ± 0.28 mm) than HTO + MMR in central images (mean difference +0.83 mm, P < .001). No significant difference was found between HTO + MMPRT and MMPRT in MME. MMR had significantly less MME than MMPRT (mean difference -0.58 mm, P < .001, posterior image at 0° and central image at 90°, P = .002). HTO + MMR showed significantly less MME than MMR alone at 30° and 90° of knee flexion in the central image (30°: -0.38 ± 0.05 mm, 90°: -0.45 ± 0.06 mm, P < .001) and 90° of knee flexion in the posterior image (-0.38 ± 0.08 mm, P = .004).

CONCLUSIONS

HTO alone did not decrease MME in the setting of MMPRT, while MMR alone decreased MME after MMPRT. Additionally, HTO + MMR decreased MME after MMPRT compared to MMR alone, although the clinical significance was uncertain.

CLINICAL RELEVANCE

The findings of this study provide clinicians with valuable insights for improving MME. HTO alone does not decrease MME in cases of MMPRT.

Influence of preoperative medial meniscus extrusion and subchondral bone marrow edema on outcomes after medial opening wedge high tibial osteotomy

OBJECTIVE

No studies have assessed the correlation between preoperative medial meniscus extrusion (MME) and subchondral bone marrow edema (BME) or which factor influences the outcomes after medial opening wedge high tibial osteotomy (MOWHTO). The present study aimed to determine the influence of preoperative MME and BME on outcomes after MOWHTO.

METHODS

This study included 151 patients between January 2019 and January 2022 with a mean follow-up of 3.2 years. MME was classified into 2 groups according to the presence of pathologic MME (≥ 3 mm). BME was graded into 4 groups according to the lesion volume based on the MRI Osteoarthritis Knee Score (MOAKS) criteria. Clinical outcomes were assessed with the Hospital for Special Surgery (HSS) score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Knee Society Score (KSS).

RESULTS

The mean ± standard deviation preoperative MME for all patients was 3.6 ± 1.9 mm. A total of 103 patients (68.2%) had pathologic MME. MME significantly increased with increasing BME grade. Those with pathologic MME showed significantly worse outcomes in terms of the WOMAC and KSS for pain and function and HSS score than those without pathologic MME at 1 and 2 years postoperatively (all p < 0.05). A total of 122 patients (80.8%) had BME. Among the 151 patients, 29 (19.2%), 61 (40.4%), 42 (27.8%), and 19 (12.6%) were classified as having an MOAKS of 0, 1, 2, and 3, respectively, with significant differences in the preoperative WOMAC and KSS for pain and function and HSS score among these 4 groups (all P < 0.001). However, there were no significant differences in these indices at 1 or 2 years postoperatively (all P > 0.05). Only MME correlated with worse clinical outcomes in univariate (p < 0.001) and multivariate (p < 0.001) analyses.

CONCLUSIONS

Short-term clinical outcomes were worse for patients with preoperative MME greater than 3 mm than for those with preoperative MME less than 3 mm. There were no correlations between preoperative subchondral BME severity and postoperative outcomes.

Medial meniscus injury changed plantar pressure distributions and decreased posture stability especially in those with varus alignment: a cross-sectional study based on a wearable smart plantar pressure system

BACKGROUND

Medial meniscus (MM) injuries are common and often contribute to knee osteoarthritis (KOA). While studies focus on joint degeneration, the role of extrinsic factors such as postural control remains underexplored. This study investigated how MM injuries affected postural control, particularly plantar pressure distribution, with an emphasis on lower limb alignment.

METHODS

83 participants were recruited: 29 healthy subjects, 29 MM patients with neutral alignment (-3°< hip-knee-ankle angle (HKA) ≤ 3°), and 25 MM patients with varus alignment (HKA > 3°). Plantar pressure was measured using a shoe-integrated detection system. Normalized peak force, center-of-pressure (COP), and time-to-boundary (TTB) were measured during walking and single-leg stance (SLS).

RESULTS

During walking, compared to the healthy group, the varus alignment group showed lower peak force for the posterior heel (P = 0.012), lateral midfoot (P = 0.024) and hallux (P = 0.009). When the two sides were compared, the varus group exhibited a lower peak force in the anterior heel (P = 0.004) and hallux (P = 0.017) of the affected sides, the neutral (P = 0.043) and varus (P = 0.045) groups all showed higher medio-lateral COP of the unaffected sides, indicating the COP shifting laterally. In SLS test, the two MM groups demonstrated increased peak force of the third (P = 0.037) and fifth (P = 0.040) metatarsals compared to the healthy group, the peak force of the posterior heel were lower in the varus alignment group compared to the healthy group (P = 0.007) and the neutral alignment group (P = 0.008). And the TTB absolute value of medial-lateral direction of the two MM groups were lower than healthy controls (P = 0.029). The area under the receiver operating characteristic curve (AUC = 0.698, P = 0.016) suggested that peak force of posterior heel had good performance to discriminate varus alignment group from neutral alignment group.

CONCLUSION

MM injuries, especially with varus alignment, lead to significant changes in plantar pressure distribution and postural stability. These insights are clinically significant for designing early, biomechanically-informed rehabilitative strategies to optimize recovery and prevent further joint degeneration following MM injuries.

Association Between Joint Line Convergence Angle and Patient-Reported Outcomes of Opening-Wedge High Tibial Osteotomy

BACKGROUND

A larger joint line convergence angle (JLCA) increases the stress load on the medial compartment. Few reports, however, have discussed the effect of the JLCA on the cartilage status and clinical outcomes after opening-wedge high tibial osteotomy (OWHTO).

PURPOSE/HYPOTHESIS

To reveal the effect of the JLCA on clinical results after OWHTO. We hypothesized that a smaller JLCA improves cartilage status and clinical outcomes by reducing mechanical stress in the medial compartment.

STUDY DESIGN

Cohort study: Level of evidence, 3.

METHODS

This retrospective study included 106 knees that underwent OWHTO and second-look arthroscopy during implant removal 1 year after OWHTO. The mean follow-up period was 5.5 (SD, 2.9) years. The pre- and postoperative JLCAs were measured radiographically. The International Cartilage Repair Society (ICRS) grades of the medial femoral condyle (MFC) and the medial tibial plateau (MTP) were evaluated during the initial and second-look arthroscopy. The relationship between the JLCA and cartilage status, and the Knee injury and Osteoarthritis Outcome Score (KOOS) at the final follow-up were evaluated.

RESULTS

Preoperative JLCA was related to improvements in the ICRS grade of the MFC and the MTP, with cutoff values of 2.6° (sensitivity, 0.700; specificity, 0.561; P = .016) and 2.4° (sensitivity, 0.704; specificity, 0.595; P = .028), respectively. In addition, the preoperative JLCA was related to KOOS Pain (P = .037), Symptoms (P < .001), Activities of Daily Living (P = .005), Sports Activities (P = .005), and Quality of Life (P = .006) subscales using multivariable linear regression analysis. The postoperative JLCA was not related to the improvement in the ICRS grade of the MFC but was related to the improvement in the ICRS grade of the MTP, with a cutoff value of 1.6° (sensitivity, 0.704; specificity, 0.603; P = .015). Furthermore, postoperative JLCA was related to the KOOS Pain (P = .004), Symptoms (P = .002), Activities of Daily Living (P = .031), Sports Activities (P < .001), and Quality of Life (P = .015) subscales.

CONCLUSION

A smaller pre- and postoperative JLCA was related to improvements in the ICRS grade and favorable clinical outcomes, with a mean 5.5-year follow-up after OWHTO.

Comparison of clinical outcomes among patients treated with high tibial osteotomy and meniscal repair of degenerative medial meniscal tear with mild varus deformity

INTRODUCTION

The clinical benefits of high tibial osteotomy (HTO) in patients with mild varus deformity with degenerative medial meniscal tear (DMMT) remain unclear. This study aimed to compare clinical outcomes among middle-aged patients with mild varus deformity who underwent arthroscopic meniscal repair and HTO for DMMT.

MATERIALS AND METHODS

In this retrospective study, patients who underwent isolated arthroscopic meniscal repair via the inside-out technique and those who underwent medial opening-wedge HTO were assigned to group M and H, respectively. The inclusion criteria were: an age of 40-65 years; percentage of mechanical axis of 30-50% measured using full-length weight-bearing anteroposterior radiographs; Kellgren-Lawrence grade ≤ 2; minimum postoperative two-year follow-up; and HTO correction angle < 10°. Clinical outcomes were assessed using the Knee Injury and Osteoarthritis Outcome Score (KOOS) and minimal clinically important difference achievement rate for the KOOS subscales preoperatively and at the final follow-up.

RESULTS

Group M and H included 21 and 41 patients, respectively. The median ages were 53 and 58 years in groups M and H, respectively. In group H, 24 cases underwent meniscal repair. No significant differences in all KOOS subscales were found preoperatively. However, the median KOOS symptoms subscale in group H (89.3) was significantly better than that in group M (80.4) at the final follow-up (p = 0.04).

CONCLUSION

The main finding of the study indicated that KOOS symptoms after HTO were superior to those after isolated arthroscopic meniscal repair for DMMT. HTO might be a potentially useful treatment for DMMT in middle-aged patients with mild varus deformity, even with a small correction angle.

LEVEL OF EVIDENCE

Retrospective comparative study, Level III.

Differences Between Traumatic and Degenerative Medial Meniscus Posterior Root Tears: A Systematic Review

BACKGROUND

Intact meniscus roots are a prerequisite for normal meniscal function, including even distribution of compressive forces across the knee joint. An injury to the root disrupts the hoop strength of the meniscus and may lead to its extrusion and the development of osteoarthritis. A medial meniscus posterior root tear (MMPRT) is often thought to have a primary degenerative pathogenesis. However, there is mention of some cases of MMPRTs where the patients have a solely traumatic injury to a previously healthy meniscus.

PURPOSE

To describe a subpopulation of patients with traumatic MMPRT.

STUDY DESIGN

Systematic review; Level of evidence, 5.

METHODS

The Web of Science database (www.webofscience.com) was queried using the Medical Subject Headings term "medial root tear." Articles were reviewed, and those evaluated for MMPRTs in a degenerative meniscus were excluded. A total of 25 articles describing cases of acute traumatic causes were included in this study. For these articles, the patient characteristics, injury mechanisms, and concomitant injuries evaluated were recorded and pooled.

RESULTS

The search revealed 660 articles, and 25 were selected for inclusion. A total of 113 patients with a traumatic MMPRT were identified and included in this review. The study population had a mean age of 27.1 years and a high share of men (64%). Also, this review displays how most patients with traumatic MMPRTs also suffer concomitant injuries (68%).

CONCLUSION

The findings in this review support our hypothesis that there is a unique subgroup with acute traumatic MMPRTs that have unique patient characteristics, injury mechanisms, and combined injuries, compared with previously published reviews on MMPRTs.

Meniscal extrusion: Proposal for a novel qualitative classification

Meniscal extrusion (ME), defined as the radial displacement of the meniscal body outside the margins of the tibial plateau, has been seen as an independent and relevant predictor of intra-articular knee degeneration. Nonetheless, available classifications for ME are exclusively quantitative assessments not considering the context in which extrusion is identified. Indeed, ME can be the result of several different conditions spanning from acute tears to chronic degeneration and its definition cannot be only dependent on the numeric calculation of the radial displacement of the meniscal body. Furthermore, growing evidence supports the existence of a paraphysiological ME resulting from joint loading, limb malalignment, anatomical abnormalities of the meniscal attachments to the femur and tibia or a nonpathological finding after meniscal allograft transplantation. It is therefore clear that an exclusively quantitative assessment of ME cannot be sufficient since this condition can develop in such different clinical scenarios. For this reason, a novel qualitative classification for ME is proposed, differentiating between three distinct conditions: a paraphysiological ME, a pathological ME and ME related to degenerative conditions. Furthermore, a comprehensive review of the present literature has been conducted to report the most relevant and updated evidence on the topic highlighting the difference in the clinical management of each different category.

Level of Evidence

Not applicable.

Relationship Between the Sagittal and Coronary Alignment of the Tibiofemoral Joint and the Medial Meniscus Extrusion in Knee Osteoarthritis

Background/Objectives: This study aims to clarify the reproducibility, validity, and accuracy of tibial external-rotation alignment evaluation using ultrasound imaging and to investigate the relationship between medial meniscus extrusion (MME) and tibiofemoral alignment in both the sagittal and coronal planes in knee osteoarthritis (OA). Methods: Study 1 included 10 healthy participants. The tibial external-rotation angle was calculated using MRI. In the ultrasound imaging evaluation, the differences in the distance from the most posterior points of the tibial and femoral condyles to the skin were calculated as the medial and lateral condyle gaps, respectively. The mediolateral (ML) gap was calculated by subtracting the lateral condyle gap from the medial condyle gap. Study 2 included 63 patients with unilateral OA and 16 healthy controls. MME was compared according to the severity of OA, the degree of tibial rotation, and the presence or absence of a tibial posterior shift. Results: Ultrasound imaging examinations showed high intra- and inter-rater reliabilities (0.786-0.979). The ML gap significantly affected the tibial external-rotation angle, determined using MRI. The ML gap of ultrasound imaging was significantly correlated with the ML gap of MRI. MME was significantly higher in the Early OA group than in the Control group. There was no significant difference in MME based on the tibial rotation degree. The group with a tibial posterior shift exhibited significantly more MME than that without a posterior shift. Conclusions: Ultrasound imaging is useful for evaluating knee alignment. MME was found to be associated with the tibial posterior shift.

Predictive factors for coronal and sagittal graft extrusion length after using tendon autograft for medial meniscus reconstruction

BACKGROUND

Meniscus extrusion occurs in most elderly individuals and most patients after meniscus allograft transplantation. The risk factors and correlative factors of meniscus extrusion have been extensively studied. However, for using tendon autograft for meniscus reconstruction, both graft type and surgical method are different from those in previous studies on meniscus extrusion.

AIM

To identify predictive factors for coronal and sagittal graft extrusion length after using tendon autograft for medial meniscus reconstruction.

METHODS

Ten patients who underwent medial meniscus reconstruction with tendon autograft were selected for this retrospective observational study. The graft extrusions and potential factors were measured and correlation and regression analyses were performed to analyze their relationships.

RESULTS

The medial graft extrusion correlated with the preoperative bilateral hip-knee-ankle angle difference, preoperative Kellgren-Lawrence grade, preoperative relative joint space width, and preoperative bilateral medial edge incline angle difference. The anterior graft correlated with the anterior tunnel edge distance at 1 week after operation. The posterior graft extrusion correlated with the preoperative bilateral hip-knee-ankle angle difference, preoperative relative joint space width, and posterior tunnel edge distance at 1 week after operation. The mean graft extrusion correlated with the preoperative bilateral hip-knee-ankle angle difference and preoperative relative joint space width. The preoperative joint space width and anterior and posterior tunnel edge distance at 1 week can be used to predict the medial, anterior, posterior, and mean graft extrusion length.

CONCLUSION

The preoperative joint space width and tunnel position can be used to predict the coronal and sagittal graft extrusion length after using tendon autograft for medial meniscus reconstruction.

Correlation of lower limb alignment with medial mensical extrusion in knee osteoarthritis

BACKGROUND

This study aims to explore the relationship between Lower limb alignment parameters and the degree of Medial Meniscal Extrusion (MME) in patients with Knee Osteoarthritis (KOA), in hopes of providing new reference data for the prevention and treatment of KOA.

METHODS

A retrospective study design was employed, analyzing 623 KOA patients treated at our hospital from 2022 to 2023, with 307 patients' information collected according to inclusion and exclusion criteria. Patients were divided into mild and severe groups based on the degree of MME, and differences in Lower limb alignment parameters between the two groups were compared. Univariate analysis, Pearson correlation analysis, and multivariate stepwise regression analysis were used, along with Receiver operating characteristic(ROC) curve assessment to evaluate the predictive value of Lower limb alignment parameters on the degree of MME.

RESULTS

Univariate analysis showed significant correlations between Anatomic Mechanical Axis (AMA), Joint Line Convergence Angle (JLCA), mechanical Lateral Distal Femur Angle (mLDFA), Medial Proximal Tibia Angle (MPTA), and the degree of MME (P < 0.05). Pearson correlation analysis further confirmed the positive correlations between these parameters and the degree of MME. Multivariate stepwise regression analysis indicated that AMA, JLCA, and mLDFA are significant independent predictors of the severity of MME. ROC analysis suggested that the combination of AMA, JLCA, and mLDFA could better predict severe MME.

CONCLUSION

AMA, JLCA, and mLDFA are closely related to the degree of MME in KOA patients and can serve as important parameters for assessing the severity of MME, holding significant implications for the early prevention and treatment of KOA.

Effect of lateral wedge insole on medial meniscus extrusion and its association with knee osteoarthritis progression

BACKGROUND

Medial meniscus extrusion (MME) is associated with knee osteoarthritis (OA) progression because of increased loading stress in the medial compartment of the knee. Using a lateral wedge insole (LWI) decreases loading stress and immediately reduces MME.

OBJECTIVE

To investigate whether the wearing duration of LWI affects the midterm response to MME and is associated with knee OA progression.

STUDY DESIGN

Cohort study.

METHODS

Twenty-three patients with knee OA who were conservatively treated with LWI were classified according to the duration of the LWI wear per day: less than 5 h (short-duration group) or over 5 h (long-duration group). MME was evaluated in the single-leg standing position by ultrasound. Knee OA progression and limb alignment were evaluated radiographically. These evaluations were performed thrice: at the initial office visit as a baseline without LWI (time 0), with LWI (LWI-time 0), and 1 year after intervention with LWI (LWI-1 year).

RESULTS

In both groups, the MMEs at LWI time 0 were significantly decreased compared with those at time 0. In the long-duration group, this reduction in MME was maintained 1 year after the intervention compared with time 0 (time 0: 3.9 ± 0.9, LWI-1 year: 2.6 ± 1.1), but this improvement was not observed in the short-duration group (time 0: 3.8 ± 1.7, LWI-1 year: 3.6 ± 1.7). In addition, three of four patients demonstrated OA progression, and varus alignment had significantly progressed compared with that at time 0 in the short-duration group. However, the long-duration group showed OA progression only in one patient and maintained limb alignment.

CONCLUSIONS

The duration of wearing LWI affects the midterm reduction of MME and knee OA progression while maintaining limb alignment.

Mid-Term Clinical and Radiological Changes in the Ankle Joint in Varus Knee Osteoarthritis Following Total Knee Arthroplasty

Background/Objectives: In patients with varus knee osteoarthritis, compensatory changes occur in the foot and ankle joints to compensate for the varus deformity of the knee. The aim of the study was to investigate the changes in the ankle of patients whose knee alignment was corrected with total knee arthroplasty (TKA) and to explore the clinical implications of these findings. Methods: In this retrospective observational study, we analyzed 204 knees of 179 patients who had regular follow-ups out of 431 patients who underwent TKA for varus knee osteoarthritis between January 2019 and July 2021. Patient demographics, body mass index, follow-up time, and radiographs were studied. The hip-knee-ankle (HKA) angle, joint line convergence angle (JLCA), talar tilt (TT) angle, ground talar dome (GT) angle, ground tibia plafond (GP) angle, and the American Orthopaedic Foot & Ankle Society (AOFAS) score were assessed preoperatively and at the last follow-up. Results: A total of 204 knees of 179 patients with a mean follow-up time of 32.50 ± 6.68 months were evaluated. It was found that the change in the HKA had a positive effect on the AOFAS score and a negative effect on the TT, GT, and GP angles. While the clinical score improved in 82 patients, it worsened in 8 patients. The age difference between the groups whose AOFAS score improved and worsened was statistically significant. Conclusions: The correction of the varus malalignment in the knee was shown to also improve the compensatory valgus in the foot and ankle over the mid-term, with a statistically significant improvement in the patients' clinical ankle scores.

The Relationship Between Medial Meniscal Extrusion and Outcome Measures for Knee Osteoarthritis: A Systematic Review

Background

Medial meniscal extrusion (MME) has been associated with knee osteoarthritis (OA). However, there is no standardized method to measure MME.

Purpose/Hypothesis

The purpose of this study was to investigate the relationship between MME and outcome measures related to knee OA and discuss different magnetic resonance imaging (MRI) methods of measuring MME. It was hypothesized that MME would be associated with outcome measures of OA and that the distance extruded over the tibial plateau would be the most common MRI method to measure MME.

Study Design

Systematic review; Level of evidence, 3.

Methods

The MEDLINE, Embase, Cochrane Library, Scopus, Web of Science Core Collection, Global Index Medicus, and ClinicalTrials.gov databases were systematically searched. The inclusion criteria were studies that (1) measured MME on nonoperated knees using MRI; (2) evaluated knee OA with at least 1 knee OA grading scale, outcome measure, or direct characterization of cartilage or bone; (3) statistically evaluated the association between MME and knee OA outcome measure; (4) were randomized controlled trials, nonrandomized controlled trials, cohort studies, or case series; and (5) reported original results.

Results

A total of 19 studies were included, of which 14 reported MME as the distance extruded over the tibial plateau, 7 reported MME as the volume extruded over the tibial plateau, and 1 reported MME as the percentage of the tibial plateau covered by the meniscus. All studies reported that MME was significantly associated with at least 1 OA outcome measure-including increased Kellgren-Lawrence grade, osteophytes, cartilage damage, varus alignment, knee pain, bone marrow lesions, and progression to arthroplasty. Eight studies found that MME was associated with worse OA outcomes over time (range, 2-10 years).

Conclusion

All 19 reviewed studies reported that MME was associated with at least 1 knee OA outcome measure reflective of worsening arthritis, suggesting a strong association between OA and MME. Future research is needed to investigate this relationship and standardize the methods of measuring MME.

Impact of lower limb alignment abnormality (physiologic knee valgus) on the functional recovery outcome of athletes with meniscal injuries

OBJECTIVE

This study aimed to investigate the impact of lower limb alignment abnormalities, specifically physiological knee valgus, on the functional recovery outcomes of athletes with meniscal injuries. It also examined the factors influencing these abnormalities to provide scientific evidence for treatment and rehabilitation of related sports injuries.

METHODS

We conducted a retrospective study of 118 athletes from Guizhou Normal University, who were divided into two groups based on the presence or absence of lower limb alignment abnormalities. The Simple group comprised athletes with isolated meniscal injuries, while the Combined group included athletes with meniscal injuries and concurrent lower limb alignment abnormalities. We assessed the functional status of both groups and analyzed factors influencing lower limb alignment abnormalities.

RESULTS

Of the 118 athletes, 46 (38.98%) exhibited lower limb alignment abnormalities, and 72 (61.02%) did not. No significant differences in general characteristics were found between the groups (all P > 0.05). The Combined group displayed higher Visual Analog Scale (VAS) scores and Functional Performance Test (FPT) results (coordinated contraction, shuttle run, CarioCa) compared to the Simple group (P < 0.05). Conversely, joint range of motion (ROM), knee muscle strength (flexors), and International Knee Documentation Committee (IKDC) scores were lower in the Combined group (all P < 0.05). Multivariate logistic regression analysis identified active ROM < 105.32°, passive ROM < 101.66°, and knee muscle strength (flexors) < 84.41 N as risk factors for lower limb alignment abnormalities (P < 0.05), while FPT acted as a protective factor (P < 0.05). The combined testing model demonstrated higher predictive efficacy (AUC = 0.903, 95% CI: 0.852-0.955, P < 0.001).

CONCLUSION

Lower limb alignment abnormalities significantly affect the functional recovery outcomes of athletes with meniscal injuries. Factors such as ROM, knee muscle strength, and IKDC score may pose risks for these abnormalities, whereas FPT can provide protective benefits. Timely detection and correction of lower limb alignment abnormalities during the rehabilitation process from meniscal injuries are crucial to enhance recovery and improve prognosis.

Joint line convergence angle is the most associated alignment factor with the severity of medial knee osteoarthritis

Purpose

The purpose of this study was to evaluate the relationship between the joint line convergence angle (JLCA) and the severity of medial knee osteoarthritis (OA). We hypothesise that JLCA is the most associated factor with the severity of medial knee OA.

Methods

This retrospective study included a total of 202 knees that underwent either high tibial osteotomy or medial meniscus repair/partial resection. Kellgren-Lawrence grade and hip-knee-ankle angle (HKAA), mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA) and JLCA were assessed from preoperative radiographs. Medial meniscus extrusion (MME) was measured using preoperative magnetic resonance imaging. The International Cartilage Research Society (ICRS) grade on the medial femoral condyle and medial tibial plateau were also assessed. The relationships between JLCA and Kellgren-Lawrence grades and MME and ICRS grades were analysed using Spearman's correlation test and regression analysis.

Results

The JLCA was correlated with the Kellgren-Lawrence grade (R = 0.765, p < 0.001), MME (R = 0.638, p < 0.001), ICRS grade on the MFC (R = 0.586, p < 0.001) and the MTP (R = 0.586, p < 0.001). Regression analysis showed that age (p = 0.002) and JLCA (p < 0.001) were associated with Kellgren-Lawrence grade. Furthermore, JLCA was related to ICRS grade on the MFC (p < 0.001) and MTP (p < 0.001).

Conclusion

The JLCA, reflecting radiological severity, meniscus status, and cartilage lesion, was the most associated alignment parameter in the severity of medial knee OA. The JLCA may be beneficial for quantitative assessment of medial knee OA.

Level of Evidence

Level III, retrospective cohort study.

The influence of the weight-bearing state on three-dimensional (3D) planning in lower extremity realignment - analysis of novel vs. state-of-the-art planning approaches

BACKGROUND

The use of 3D planning to guide corrective osteotomies of the lower extremity is increasing in clinical practice. The use of computer-tomography (CT) data acquired in supine position neglects the weight-bearing (WB) state and the gold standard in 3D planning involves the manual adaption of the surgical plan after considering the WB state in long-leg radiographs (LLR). However, this process is subjective and dependent on the surgeons experience. A more standardized and automated method could reduce variability and decrease costs.

PURPOSE

The aim of the study was (1) to compare three different three-dimensional (3D) planning modalities for medial open-wedge high tibial osteotomy (MOWHTO) and (2) to describe the current practice of adapting NWB CT data after considering the WB state in LLR. The purpose of this study is to validate a new, standardized approach to include the WB state into the 3D planning and to compare this method against the current gold standard of 3D planning. Our hypothesis is that the correction is comparable to the gold standard, but shows less variability due compared to the more subjective hybrid approach.

METHODS

Three surgical planning modalities were retrospectively analyzed in 43 legs scheduled for MOWHTO between 2015 and 2019. The planning modalities included: (1) 3D hybrid (3D non-weight-bearing (NWB) CT models after manual adaption of the opening angle considering the WB state in LLR, (2) 3D NWB (3D NWB CT models) and (3) 3D WB (2D/3D registration of 3D NWB CT models onto LLR to simulate the WB state). The pre- and postoperative hip-knee-ankle angle (HKA) and the planned opening angle (°) were assessed and differences among modalities reported. The relationship between the reported differences and BMI, preoperative HKA (LLR), medial meniscus extrusion, Outerbridge osteoarthritis grade and joint line convergence angle (JLCA) was analyzed.

RESULTS

The mean (std) planned opening angle of 3D hybrid did not differ between 3D hybrid and 3D WB (0.4 ± 2.1°) (n.s.) but was higher in 3D hybrid compared to 3D NWB (1.1° ± 1.1°) (p = 0.039). 3D WB demonstrated increased preoperative varus deformity compared to 3D NWB: 6.7 ± 3.8° vs. 5.6 ± 2.7° (p = 0.029). Patients with an increased varus deformity in 3D WB compared to 3D NWB (> 2 °) demonstrated more extensive varus alignment in LLR (p = 0.009) and a higher JLCA (p = 0.013).

CONCLUSION

Small intermodal differences between the current practice of the reported 3D hybrid planning modality and a 3D WB approach using a 2D/3D registration algorithm were reported. In contrast, neglecting the WB state underestimates preoperative varus deformity and results in a smaller planned opening angle. This leads to potential under correction in MOWHTO, especially in patients with extensive varus deformities or JLCA.

CLINICAL RELEVANCE

Incorporating the WB state in 3D planning modalities has the potential to increase accuracy and lead to a more consistent and reliable planning in MOWHTO. The inclusion of the WB state in automatized surgical planning algorithms has the potential to reduce costs and time in the future.

Medial meniscus extrusion during gait is associated with decrease in knee rotation in early-stage knee osteoarthritis

BACKGROUND

In patients with medial knee osteoarthritis (OA), medial meniscus extrusion during gait is aggravated by mechanical stress, such as knee adduction moment (KAM). Conversely, the decrease in the range of knee rotation during stance phase is also one of the important issues in early knee OA, whereas the correlation between medial meniscus extrusion and knee rotation during gait are unclear.

RESEARCH QUESTION

To investigate the correlation between increase in medial meniscus extrusion and range of knee rotation during gait in patients with early- and late-stage of knee OA.

METHODS

Forty patients with medial knee OA were enrolled and divided into early- and late-OA group by Kellgren-Lawrence grading scale. During gait tasks, the extent of medial meniscus extrusion was measured using ultrasonography and kinetic/kinematic data were measured using three-dimensional motion analysis system. The correlation between medial meniscus extrusion and the range of knee rotation or KAM were evaluated in the overall, early-, and late- OA groups.

RESULTS

A significant negative correlation was observed between an increase in medial meniscus extrusion and range of knee rotation angle in early-OA group only. However, an increase in medial meniscus extrusion significantly correlated with the second KAM peak in the overall and early-OA groups.

SIGNIFICANCE

The decrease in range of knee rotation during stance phase may be associated with the increase in medial meniscus extrusion during gait in patients with early knee OA.

Effect of inside-out meniscal repair on meniscal dimension in meniscal tear patients

Background

It remains controversial whether meniscal repair causes meniscal extrusion. This study aimed to investigate the effect of inside-out meniscal repair on meniscal dimensions in patients with meniscal tear of the mid-body-posterior horn.

Methods

This retrospective study included 75 patients who underwent meniscal repair followed by MRI within 2 weeks after surgery between 2020 and 2022. Patients with a discoid lateral meniscus, pull-out repair, concomitant osteotomy, all-inside repair only, and revision surgery were excluded. Thirty-three meniscal tear treated using an inside-out arthroscopic repair technique were included in the lateral meniscus (LM, n = 19) and medial meniscus (MM, n = 14) tear groups. Thirty-six participants with intact meniscus were included as controls. Meniscal extrusion and posterior shift were measured on coronal and sagittal MRI pre-operatively and within 2 weeks postoperatively.

Results

Preoperative coronal extrusion was significantly greater in the LM tear group than in the control group (P = 0.001). Coronal extrusion and posterior shift were significantly smaller postoperatively than preoperatively in the LM tear group (P < 0.001 and, P = 0.008, respectively). Pre- and postoperative coronal extrusion in the MM tear group were not significantly different (P = 0.291). Postoperative coronal extrusion in both LM and MM tear groups were not significantly correlated with the number of sutures required for repair (LM: P = 0.765, R = -0.076, MM: P = 0.1, R = 0.497).

Conclusions

The torn meniscus of the mid-body - posterior horn before surgery was extruded and shifted posteriorly in both LM and MM tears, and repair using an inside-out arthroscopic technique was effective in reducing meniscal extrusion and posteriors shift in the LM tear immediately after surgery.

Preoperative valgus-corrected hip-knee-ankle angle and medial meniscal extrusion are useful for evaluating postoperative alignment in mobile-bearing UKA

Purpose

The purposes of the study were to analyze the correlation between preoperative variables (valgus corrected hip-knee-ankle angle (vcHKA), medial osteophyte areas of the tibia and femur, and medial meniscus extrusion (MME)) and the postoperative alignment in mobile-bearing unicompartmental knee arthroplasty (UKA).

Methods

This study enrolled 109 patients (118 knees) who underwent mobile-bearing UKA between January 1, 2019 and January 1, 2023, retrospectively. Radiographic parameters, including the HKA, hip-knee-shaft angle (HKS), and valgus-corrected femorotibial angle (vcFTA), were measured using preoperative radiographs. The vcHKA was calculated as vcFTA - HKS. The medial osteophyte areas of the tibia and femur and MME were measured using knee magnetic resonance imaging (MRI). Simple and multiple linear regression analyses, univariate and multivariate logistic regression analyses, and receiver operating characteristic (ROC) curves were performed.

Results

In total, 109 patients (118 knees) were enrolled in this study. In the multiple linear regression analysis, vcHKA (β = 0.732, 95 % confidence interval (95%CI) = 0.582 to 0.881; p < 0.001) and MME (β = 0.203, 95%CI = 0.001 to 0.405; p = 0.049) were positively correlated with postoperative HKA, and postoperative HKA was modeled according to the following equation: 45.420 + (0.732° * vcHKA) + (0.203 mm × MME). In the multivariate logistic regression analysis, vcHKA (odds ratio (OR) = 2.007, 95 % CI = 1.433 to 2.810, p < 0.001) was associated with postoperative valgus malalignment independently. In the ROC curve, vcHKA (cutoff value: 180°) was predictive of postoperative valgus malalignment, with an accuracy (95%CI) of 0.862 (0.780-0.944).

Conclusion

Overcorrection of a varus knee under valgus stress radiograph (VSR) and excessive MME on preoperative MRI increase the possibility of overcorrection of postoperative alignment in mobile-bearing UKA.

Stem Design in Total Hip Arthroplasty Influences Ipsilateral Knee Valgus: A Retrospective Comparative Analysis of 2953 Cases

BACKGROUND

Total hip arthroplasty (THA) affects the biomechanics of the hip and the patient gait. The stem design influences femoral lever ratios and tissue trauma. Biomechanical changes such as these have the potential to induce knee arthritis. A varus or valgus configuration of knee arthritis is formed by asymmetric loadings. The aim of this study was to evaluate the impact of stem design in THA on knee valgus by comparing a standard implant with an implant with a short stem.

METHODS

A total of 2953 patients who underwent primary total knee arthroplasty for end-stage osteoarthritis between 2015 and 2021 were included in this retrospective data analysis. Patients were divided into three groups, depending on hip status (straight stem, short stem, and native joint). Leg alignment was distinguished as varus or valgus, and the degree of axial deviation was measured. Descriptive and explorative statistical analyses were performed, with a p value < 0.05 set as significant.

RESULTS

Ipsilateral knee valgus occurred significantly more often in patients with straight stems (57.2%) than in those with short stems (29%) and native joints (25.8%) (p < 0.001). Additionally, mean valgus deviation was significantly increased in patients with straight stems (8.9°) compared to those with short stems (6.4°) or native hip joints (6.7°). Both findings were accentuated in women.

CONCLUSIONS

Previous ipsilateral straight-stem THA is associated with knee valgus deformity, especially in women. Short-stem THA seems to be better suited to restoring physiological biomechanics and preventing the development of valgus osteoarthritis of the ipsilateral knee.

Effect of limb alignment correction on medial meniscus extrusion under loading condition in high tibial osteotomy

Background

This study aimed to investigate the effect of high tibial osteotomy (HTO) on medial meniscus extrusion (MME) and the association between the changes in limb alignment and MME under weight-bearing (WB) conditions after HTO.

Methods

We included 17 patients with knee osteoarthritis (OA) who underwent HTO. MME was evaluated using ultrasonography in supine and unipedal standing positions. Knee alignment was evaluated radiographically using WB, whole-leg radiographs with the hip-knee-ankle angle (HKAA), percentage of the mechanical axis (%MA), medial proximal tibial angle (MPTA), and joint line convergence angle (JLCA). All measurements were performed serially at four time points: preoperative and 3, 6, and 12 months postoperative. Clinical outcomes were assessed by knee injury and osteoarthrosis outcome score (KOOS) and visual analogue scale (VAS) value for pain.

Results

Mean MME in the WB position was significantly greater than that in the supine position in the preoperative condition; however, MME in both supine and WB positions was significantly lowered postoperatively. The ΔMME, difference of MME between supine and WB positions, was significantly lowered postoperatively and maintained for up to 1 year. MME change in the WB position between preop and postoperative conditions was significantly correlated with change in HKAA and %MA at 1 year postoperative. KOOS and VAS score were significantly improved after HTO.

Conclusions

HTO correcting varus alignment can decrease MME in WB position and minimise the change in MME between supine and WB positions. The changes in MME after HTO were correlated with changes in the mechanical alignments.

Toe-out gait inhibits medial meniscus extrusion associated with the second peak of knee adduction moment during gait in patients with knee osteoarthritis

Background

A medial meniscus extrusion (MME) gradually expands during activities of daily living according to the mechanical stress on the medial compartment of the knee. Increase in MME occurs during the stance phase of the gait cycle, which is key for its expand. The knee adduction moment (KAM) represents the mechanical stress on the medial compartment; however, the relationship between the increase in MME and KAM is still unknown. Therefore, the present study aimed to investigate the relationship between MME during gait and KAM.

Methods

Twenty-one patients with medial knee osteoarthritis and 11 healthy middle-aged adults were recruited. Three-dimensional motion analysis system and ultrasonography were used to measure the KAM and MME in the stance phase. The increase in MME was identified as the difference in MME between the maximum and minimum (ΔMME). Patients with knee osteoarthritis performed two conditions as normal and toe-out gait. The difference in KAM and ΔMME between conditions were evaluated.

Results

ΔMME was correlated with the KAM second peak in normal gait of knee osteoarthritis patients (r = 0.51, p < 0.05). Toe-out gait reduced the KAM second peak and the ΔMME, and these reductions were correlated (r = 0.50, p < 0.05).

Conclusions

Toe-out gait immediately inhibited the expansion of MME associated with the KAM second peak.

Meniscal Extrusion: Diagnosis, Etiology, and Treatment Options

PURPOSE OF REVIEW

The concept of meniscal extrusion has recently been recognized as a hallmark of meniscus dysfunction. This review examines contemporary literature regarding the pathophysiology, classification, diagnosis, treatment, and future directions for investigation regarding meniscus extrusion.

RECENT FINDINGS

Meniscus extrusion, defined as >3 mm of radial displacement of the meniscus, leads to altered knee biomechanics and accelerated knee joint degeneration. Meniscus extrusion has been associated with degenerative joint disease, posterior root and radial meniscal tears, and acute trauma. Meniscus centralization and meniscotibial ligament repair have been proposed as techniques to address meniscal extrusion with promising biomechanical, animal model, and early clinical reports. Further studies on the epidemiology of meniscus extrusion and associated long-term nonoperative outcomes will help to elucidate its role in meniscus dysfunction and resultant arthritic development. Understanding and appreciation for the anatomic attachments of the meniscus will help to inform future repair techniques. Long-term reporting on the clinical outcomes of meniscus centralization techniques will yield insights into the clinical significance of meniscus extrusion correction.

Dynamic ultrasound reveals the specific behavior of the medial meniscus extrusion in patients with knee osteoarthritis

BACKGROUND

In the dynamic condition, knee osteoarthritis (OA) usually presents with pain. In the weight-bearing condition, a medial meniscus extrusion (MME) may cause severe symptoms and pathological progression. However, the correlation between a dynamic MME and pain has not been elucidated. Now, an MME can be evaluated under dynamic conditions and reflect the characteristics of symptomatic knee OA. This study investigated MMEs during walking and their correlation with knee pain.

METHODS

Thirty-two symptomatic patients with knee OA (mean age, 60.5 ± 9.9 years) were enrolled in this study. The medial meniscus was evaluated using ultrasonograms during walking, and in the static supine and unipedal standing positions, as dynamic and static conditions, respectively. The ΔMME (the difference between the maximum and minimum MMEs) was obtained in each condition. The intensity of the knee pain during walking was measured by the visual analog scale (VAS).

RESULTS

The ΔMME in the dynamic condition was significantly higher than that in the static condition (P < 0.01). There was a significant correlation between VAS and ΔMME only in the dynamic condition.

CONCLUSIONS

The dynamic evaluation is a valid tool for understanding the mechanisms of knee pain and the behavior of the medial meniscus in symptomatic knee OA.

Medial Meniscal Extrusion in Patients With Medial Meniscus Root Tears: A Systematic Review and Meta-analysis

Background

Medial meniscal extrusion (MME) has received significant interest because of its correlation with medial meniscus root tears (MMRTs), its potential as a diagnostic tool, and its significance in the progression of knee osteoarthritis (OA).

Purpose

To (1) evaluate if MMRTs significantly increase MME compared with nonroot tears (NRTs) and no tears and (2) determine the clinical outcomes of increased MME.

Study Design

Systematic review; Level of evidence, 4.

Methods

Electronic database searches of PubMed, Embase, Scopus, Web of Science, and Cochrane Central Register of Controlled Trials were conducted on June 6, 2022, in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 checklist criteria. The searches were conducted using the keywords "meniscus tear" and "extrusion." No restrictions were placed on the date of publication. Quality and sensitivity assessments were conducted on included studies. Major MME was defined as an extrusion ≥3 mm.

Results

Twenty-two studies involving 7882 knees were included. Compared with patients with NRTs, those with MMRTs had a 1.12-mm greater mean absolute meniscal extrusion (AME) and were 3.45 times more likely to have major MME (P < .001 for both). Compared with patients with no tears, those with MMRTs had a 2.13-mm greater AME (P < .001). Within patients with MMRT, those with widely displaced MMRT had a 1.01-mm greater AME compared with nondisplaced MMRT (P < .001). Patients with OA had a 0.73-mm greater AME and were 3.86 times more likely to have major MME compared with patients without OA (P < .001 for both). Within patients who were not stratified according to MMRT, NRT, or no tears, those who eventually developed OA had a 0.79-mm greater AME than those who did not have OA (P = .02).

Conclusion

Patients with MMRTs had higher MME values compared with those with other types of meniscal tears and those without any meniscal tears. Patients with knee OA were more likely to have higher MME compared with those without OA.

Reliability and validity of OpenPose for measuring hip-knee-ankle angle in patients with knee osteoarthritis

We aimed to assess the reliability and validity of OpenPose, a posture estimation algorithm, for measuring hip-knee-ankle (HKA) angle in patients with knee osteoarthritis, by comparing it with radiography. In this prospective study, we analysed 60 knees (30 patients) with knee osteoarthritis. We measured HKA angle using OpenPose and radiography before or after total knee arthroplasty and assessed the test-retest reliability of each method with intraclass correlation coefficient (1, 1). We evaluated the ability to estimate the radiographic measurement values from the OpenPose values using linear regression analysis and used intraclass correlation coefficients (2, 1) and Bland-Altman analyses to evaluate the agreement and error between OpenPose and radiographic measurements. OpenPose had excellent test-retest reliability (intraclass correlation coefficient (1, 1) = 1.000) and excellent agreement with radiography (intraclass correlation coefficient (2, 1) = 0.915), with regression analysis indicating a large correlation (R² = 0.865). OpenPose also had a 1.1° fixed error and no systematic error when compared with radiography. This is the first study to validate the use of OpenPose for the estimation of HKA angle in patients with knee osteoarthritis. OpenPose is a reliable and valid tool for measuring HKA angle in patients with knee osteoarthritis. OpenPose, which enables non-invasive and simple measurements, may be a useful tool to assess changes in HKA angle and monitor the progression and post-operative course of knee osteoarthritis. Furthermore, this validated tool can be used not only in clinics and hospitals, but also at home and in training gyms; thus, its use could potentially be expanded to include self-assessment/monitoring.

Femoral morphology affects postoperative alignment of the lower extremities in hybrid closed-wedge high tibial osteotomy

INTRODUCTION

This study aimed to determine correction error predictors of lower extremitiy alignment after hybrid closed-wedge high tibial osteotomy (HCWHTO).

MATERIALS AND METHODS

From 2011 to 2015, 102 knees in 75 patients with medial compartment knee osteoarthritis of the knee and varus knee deformities who underwent HCWHTO were evaluated in this retrospective study with a minimum 2-year follow-up. Preoperative radiological parameters including weight-bearing line ratio (WBL ratio), mechanical leg axis angle, mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), joint line convergence angle (JLCA), and JLCA under varus or valgus stress were measured. The knees were divided into the following three groups based on the WBL ratio on average 54 months after procedure: acceptable (WBL crossing the tibial plateau between 50 and 70%), under-correction (< 50%), and overcorrection (> 70%). A multiple regression analysis was performed to evaluate predictors that could influence postoperative WBL ratio and cut-off values of predictive preoperative factors was analysed.

RESULTS

Significant differences in pre- and postoperative WBL ratios and mechanical leg axis angles were found. Preoperative mLDFA in the under-correction group (89.4° ± 2.1°) was significantly higher than that in the overcorrection group (87.4° ± 2.2°) (p = 0.015), while other preoperative parameters revealed no significant differences. The postoperative MPTA in the under-correction group (92.1° ± 3.7°) was significantly lower than that in the other two groups (p = 0.005 and p = 0.0001, respectively), while there was no significant change between the acceptable (94.6° ± 3.4°) and the overcorrection (96.7° ± 3.2°) groups. Multiple regression analysis revealed that mLDFA (β =  - 0.316; p = 0.010) had a significant impact on postoperative WBLR. The cut-off value for under-correction of mLDFA was 89.5°and sensitivity and specificity were 53.6 and 71.6%, respectively (p = 0.014).

CONCLUSIONS

Preoperative mLDFA is significantly associated with postoperative alignment in HCWHTO. While postoperative MPTA is important, disregarding the preoperative mLDFA may bears a high risk of malcorrection. Varus alignment of the knee with larger mLDFA may be an indication for not only HCWHTO, but also for distal femoral osteotomy.

Clinical significance and management of meniscal extrusion in different knee pathologies: a comprehensive review of the literature and treatment algorithm

The menisci are crescent-shaped, fibrocartilaginous structures that play a crucial role in the load transition and distribution of the contact forces along the tibiofemoral articulation. Meniscal extrusion (ME) is a radiological finding, especially in magnetic resonance imaging (MRI) scans, for which there has been growing interest in recent years. ME, in the coronary plane, is defined as the maximum distance of the most distal end of the meniscus from the border of the tibial plateau, where the tibial eminences are the most prominent, without taking into account the osteophytes. Although there is still controversy in the literature in respect of the optimal cutoff value, a threshold of 3 mm is considered significant. ME has no specific clinical finding or sign and it is encountered in many knee pathologies. It is associated with either rapidly progressive knee osteoarthritis or early onset of knee osteoarthritis and increased morbidity. In this review, we delineate the clinical significance of ME in various knee pathologies, as well as when, why and how it should be managed. To the best of our knowledge, this is the first study to elaborate on these topics.

Dynamic response of medial meniscus extrusion to the lateral wedge insole is correlated with immediate pain reduction in knee osteoarthritis patients: real-time ultrasonographic study

PURPOSE

To investigate the effect of lateral wedge insole (LWI) on medial meniscus extrusion (MME) observed during dynamic evaluation with ultrasound and its correlation with the alteration in knee pain in patients with knee osteoarthritis (OA).

METHODS

This cohort study included 25 participants with knee OA. The medial meniscus was imaged during walking in video mode using ultrasonography. The degree of increase in MME (ΔMME) was calculated as the difference in the value of the maximum and minimum MME. The intensity of knee pain was evaluated immediately after the walking trial using the visual analogue scale (VAS). These measurements were performed with and without the LWI. The participants were categorised into the responder group, which was identified by the constant reduction in the VAS, and the non-responder group.

RESULTS

MME, ΔMME, and knee pain during walking were significantly lower with the LWI than without the LWI (p < 0.01). The reduction in ΔMME with the LWI in the responder group was significantly higher than that in the non-responder group (p < 0.01).

CONCLUSIONS

Our findings showed that MME and knee pain during walking decreased with LWI use, especially in patients whose reduction in knee pain was characterised by inhibition in the increase in MME observed during dynamic evaluation with ultrasound.

Meniscal Extrusion: A Critical Analysis Review

➢

Pathologic meniscal extrusion can compromise meniscal function, leading to increased contact forces in the tibiofemoral compartment and the acceleration of osteoarthritic changes.

➢

Extrusion is typically defined as radial displacement of ≥3 mm outside the tibial border and is best diagnosed via magnetic resonance imaging, although ultrasonography has also demonstrated encouraging diagnostic utility.

➢

Surgical management of meniscal extrusion is based on the underlying etiology, the patient's symptom profile, the preexisting health of the articular surface, and the risk of future chondral injury and osteoarthritis.

Medial meniscus extrusion and varus tilt of joint line convergence angle increase stress in the medial compartment of the knee joint in the knee extension position -finite element analysis

PURPOSE

Although it has been recognized that the medial meniscus extrusion (MME) leads to progressive cartilage loss and osteoarthritis (OA), about 20% of cases with MME had minor symptoms and poor progression of knee OA. However, it is still unclear which patients will have minimal symptoms or will not progress to degeneration. The purpose of this study is to compare the effect of the relationship between the MME and Joint line convergence angle (JLCA) on knee stress with the finite element (FE) analysis method.

METHODS

The 65 year-old female was taken computer tomography (CT) from thigh to ankle. A 3-dimentional nonlinear FE model was constructed from the patient's DICOM data. We made the six models, which was different from JLCA and MME. Contact stresses on the surfaces between femoral and tibial cartilages and both side of meniscus are analyzed.

RESULTS

As the JLCA or MME increased, the stress load on the medial compartment increased. The effect of MME was stronger on the femoral side, while the effect of JLCA was stronger for the tibia and meniscus. If the JLCA was tilted valgus, the stress in the medial compartment did not increase even in the presence of MME.

CONCLUSIONS

This study revealed that the MME is associated with increased a stress loading on medial compartment structures. Furthermore, this change was enhanced by the varus tilt of the JLCA. In the case of valgus alignment, the contact pressure of the medial compartment did not increase so much even if with the MME.

LEVEL OF EVIDENCE

Level V.

Large medial meniscus extrusion and varus are poor prognostic factors of arthroscopic partial meniscectomy for degenerative medial meniscus lesions

BACKGROUND

The indications and efficacy after arthroscopic partial meniscectomy (APM) for degenerative medial meniscus lesions (DMMLs) have been controversial. The purpose of this study was to identify predictors of unfavorable clinical and radiologic outcomes after APM for DMMLs and to choose appropriate indications and improve treatment efficacy.

METHODS

A total of 86 patients with DMMLs undergoing APM were retrospectively reviewed. The mean follow-up time was 32.1 months. Clinical outcomes (including Lysholm score) and radiographic results (including Kellgren-Lawrence grade (K-L grade: 0/1/2/3/4) were evaluated at preoperative and final follow-up. Preoperative prognostic factors, including gender, age, Body Mass Index (BMI), Hip-Knee-Ankle (HKA), Medial Posterior Tibial Slope (MPTS), Medial Meniscus Extrusion (MME), K-L grade, occupational kneeling, and cartilaginous condition (Outerbridge grade ≤ 2, VS ≥ 3), for relatively unfavorable (fair or poor grade) Lysholm and progression of K-L grade, were investigated by multivariate logistic regression analysis. Receiver operating characteristic curve was used to identify a cutoff point for the extent of medial meniscal extrusion that was associated with the final Lysholm score.

RESULTS

A significantly improved postoperative Lysholm score (84.5 ± 9.7) compared with the preoperative score (63.8 ± 9.3) (P < 0.001), but a progression of K-L grade (20/36/30/0/0-15/27/25/19/0) (P < 0.001). The adverse prognostic factor of Lysholm score was the advancing age (OR 1.109, P = 0.05) and HKA (OR 0.255, P < 0.001). The adverse prognostic factor of K-L grade progression was MME (OR 10.327, P < 0.001). The cutoff point for the relative value of preoperative medial meniscal extrusion associated with relatively unfavorable Lysholm scores was 2.05 mm (Area = 0.8668, P value < 0.0001, Sensitivity = 62.16%, Specificity = 93.88%).

CONCLUSIONS

Clinically, varus alignment, large MME, and older age were found to predict a poor prognosis after APM for DMMLs. The preoperative extent of MME can be used as a predictive factor for osteoarthritis in APM. Patients with varus and MME should avoid APM. High tibial osteotomy may be an effective treatment strategy.

Three-dimensional MRI shows cartilage defect extension with no separation from the meniscus in women in their 70 s with knee osteoarthritis

The positional relationship between cartilage defects and the meniscus is poorly understood for osteoarthritis of the knee. Our purpose was to clarify how cartilage defects extend and their association with the meniscus location during osteoarthritis progression. The subjects were women in their 70 s who were registered in the Kanagawa Knee Study. We obtained 3D MRI images of the tibial surfaces with menisci in subjects with cartilage area ratios < 0.95 and examined the morphological association between cartilage defects and the medial meniscus (MM) by viewing the defects according to the cartilage area ratio at the medial tibial region. Of the 561 Kanagawa Knee Study subjects, 45 were included in the analyses, and 11 had a cartilage area ratio < 0.95 at the medial tibia. Significant differences were observed in the localization of cartilage defects among 9 subregions, with cartilage defects occurring predominantly in the middle external subregion. The inner margin of the MM contacted the cartilage defect in 7 knees and crossed the cartilage defect in 4 knees but was never found separated from the cartilage defect. The cartilage defects occurred from the middle external subregion and extended to the surrounding area without separating from the inner margin of the MM.Trial registration UMIN, UMIN000032826; 1 September 2018.

Serial Improvement of Medial Meniscus Extrusion Following Medial Open-Wedge High Tibial Osteotomy Does Not Correlate With Clinical Outcomes and Arthroscopic Articular Cartilage Improvement

PURPOSE

To assess serial change up to 2 years in medial meniscus extrusion (MME) following medial open-wedge high tibial osteotomy (MOWHTO) and to determine whether postoperative changes in MME correlated with clinical outcomes and arthroscopic articular cartilage status.

METHODS

This study included 26 patients from December 2016 to March 2018 who underwent MOWHTO for primary medial osteoarthritis with varus malalignment. Second-look arthroscopy with plate removal was performed at postoperative 2 years. MME was consecutively measured using coronal magnetic resonance imaging at preoperative and postoperative 3 months, 6 months, 1.5 years, and 2 years. We also assessed which preoperative parameters could reflect the postoperative changes in MME and evaluated whether postoperative clinical outcomes and arthroscopic articular cartilage improvement would be influenced by the MME changes.

RESULTS

Regarding the postoperative serial changes in MME values, significant improvement in MME was noted from postoperative 6 months (P = .003), and thereafter, mean MME was further improved with time until postoperative 2 years (P < .001). Regarding the correlation between preoperative parameters and MME changes, preoperative medial proximal tibial angle (MPTA) showed significant correlations in univariate and multivariate analysis (P = .004 and P = .004, respectively). Meanwhile, changes in MME were not correlated with postoperative clinical outcomes or arthroscopic articular cartilage improvement.

CONCLUSION

After MOWHTO, MME improved with time and was significantly correlated with preoperative MPTA. However, the changes in MME after MOWHTO did not reflect postoperative clinical and arthroscopic articular cartilage improvement.

LEVEL OF EVIDENCE

IV, case series.

Extent of Preoperative Medial Meniscal Extrusion Influences Intermediate-Term Outcomes After Medial Opening-Wedge High Tibial Osteotomy

BACKGROUND

The purpose of the present study was to determine the relationship between preoperative medial meniscal extrusion, as classified according to magnetic resonance imaging (MRI), and medial opening-wedge high tibial osteotomy outcomes at intermediate-term follow-up.

METHODS

We reviewed the records for 212 patients who had undergone medial opening-wedge high tibial osteotomy for the treatment of medial compartment osteoarthritis between January 2009 and September 2014, with a minimum duration of follow-up of 5 years. Patients were divided into 2 groups according to the presence of pathologic medial meniscal extrusion (>3 mm). Moreover, patients were divided into 4 groups according to MRI Osteoarthritis Knee Score (MOAKS) criteria and relative medial meniscal extrusion values. Associations between the extent of preoperative medial meniscal extrusion and clinical outcomes over a mean duration of follow-up of 8.1 years were evaluated with use of Spearman rank correlation analysis. Regression analyses were performed to determine preoperative characteristics relevant to medial meniscal extrusion. Clinical outcomes were assessed with use of the Knee Injury and Osteoarthritis Outcome Score (KOOS) and the Tegner activity scale score.

RESULTS

Postoperative KOOS pain scores were significantly different in the pathologic and non-pathologic medial meniscal extrusion groups (69.9 ± 18.0 versus 79.2 ± 11.4, respectively; p < 0.001). Additionally, the degree of preoperative medial meniscal extrusion based on both classification methods and the postoperative KOOS pain score were significantly correlated (r = -0.404 and -0.364; p < 0.001). Despite the inferior clinical outcomes associated with greater preoperative medial meniscal extrusion, medial opening-wedge high tibial osteotomy was associated with significant improvement in all outcome measures between the preoperative and latest follow-up assessments (p < 0.001). Preoperative meniscal patterns, including horizontal flap, complex, and root tears (p = 0.001), and increased Kellgren-Lawrence grade (p < 0.001) were related to the severity of medial meniscal extrusion. The survival rate was 94.8% at a mean of 8.1 years, and survival was not associated with the grade of medial meniscal extrusion as assessed with either classification scheme.

CONCLUSIONS

At intermediate-term follow-up, greater preoperative medial meniscal extrusion was related to inferior postoperative clinical outcomes, specifically pain, after medial opening-wedge high tibial osteotomy. Despite the inferior results associated with preoperative medial meniscal extrusion, medial opening-wedge high tibial osteotomy was associated with a satisfactory survival rate after a mean of 8.1 years, regardless of the extent of medial meniscal extrusion.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

The postoperative shorter meniscal width was the risk factor of lateral meniscal extrusion in the middle portion for juvenile and adolescent knees with discoid lateral meniscus

PURPOSE

The study aim was to clarify the risk factors for postoperative meniscal extrusion in a middle portion in juvenile and adolescent knees with DLM.

METHODS

Forty-six patients with symptomatic DLM who underwent surgery were retrospectively assessed. Inclusion criteria were set as follows: (1) aged ≤ 17 years with an open growth plate, (2) preoperative and postoperative follow-up MRI, and 3) reshaping surgeries comprising of saucerization alone or with meniscal repair. Average (95%CI) age during surgery, body mass index (BMI), and follow-up duration were 12 years (11-13), 19.9 kg/m² (18.7-21.0), and 26.4 months (19.5-33.3), respectively. Age, sex, sports activities, BMI, postoperative rehabilitation, preoperative shift of DLM by Ahn's classification, surgical procedures, postoperative meniscal width of all portions, and meniscal healing were analyzed.

RESULTS

Postoperatively, eight knees in the no-extrusion group and 38 knees in the extrusion group were observed. In the univariate logistic regression analysis, shorter meniscal width in a middle portion (OR = 1.580, p = 0.006), shorter minimum width of all portions (OR = 1.674, p = 0.024), and meniscal healing (OR = 0.160, p = 0.028) were the risk factors for meniscal extrusion in a middle portion. Multiple logistic regression analysis demonstrated that shorter meniscal width in a middle portion was the risk factor.

CONCLUSIONS

As the clinical relevance, to prevent postoperative meniscal extrusion of the middle portion with DLM, surgeons are necessary to pay attention to maintain the adequate meniscal width for juvenile and adolescent knees.

LEVEL OF EVIDENCE

III.

The Epidemiology of Meniscus Injury

Meniscus surgery is one of the most commonly performed orthopedic procedures worldwide. Modifiable risk factors for meniscus injury include body mass index, participation in athletics and occupation. Nonmodifiable risk factors include age, sex, lower extremity alignment, discoid meniscus, ligamentous laxity, and biconcave tibial plateau. Conditions commonly associated with meniscal injury are osteoarthritis, anterior cruciate ligament injury, and tibial plateau fractures. Tear type and location vary by patient age and functional status. Surgical management of meniscus injury is typically cost-effective in terms of quality-adjusted life years. The purpose of this review is to provide an overview of meniscal injury epidemiology by summarizing tear types and locations, associated conditions, and factors that increase the risk for meniscal injury. The economic burden of meniscus injury and strategies to prevent injury to the meniscus are also reviewed.

Short-term results and surgical technique of arthroscopic centralization as an augmentation for medial meniscus extrusion caused by medial meniscus posterior root tear

INTRODUCTION

The purpose of this study was to perform medial meniscus (MM) centralization for medial meniscus extrusion (MME) associated with medial meniscus posterior root tear (MMPRT) and to examine the short-term results. The hypothesis is that arthroscopic centralization as an augmentation of MMPRT repair improves clinical outcomes and the extrusion distance of MM in short-term results.

MATERIALS AND METHODS

Twenty-six patients (mean age 62.1 ± 6.0 years) who underwent arthroscopic centralization as an augmentation of MMPRT repair were included. Clinical evaluation was performed before and 2 years after surgery using Lysholm score and knee injury and osteoarthritis outcome score (KOOS). Image evaluation used MRI and plain X-ray images. The extrusion distance and MME ratio were compared on MRI images before and 2 years after surgery. The degree of osteoarthritis (OA) was evaluated using Kellgren-Lawrence classification. The degree of OA and hip-knee-ankle (HKA) angle were compared by plane X-ray images before and 2 years after surgery.

RESULTS

In clinical results, both Lysholm score and KOOS improved significantly after surgery. In image evaluation, the extrusion distance decreased significantly from 4.8 ± 0.7 mm before surgery to 2.7 ± 0.3 mm 2 years after surgery (p < 0.05). The MME ratio was significantly improved from 40.2 ± 7.0% before surgery to 22.6 ± 3.6% after surgery (p < 0.05). There was no significant difference in HKA angle at 2 years after surgery (p = 0.13).

CONCLUSIONS

The arthroscopic centralization for medial meniscal extrusion associated with MMPRT significantly improved clinical outcomes and the extrusion distance of MM. It is also one of the surgical techniques that can suppress medial meniscus extrusion.

LEVEL OF EVIDENCE

IV, therapeutic case series.

Morphological changes affecting ipsilateral and contralateral leg alignment after total hip arthroplasty

Background

It is still unclear whether morphological changes in hip disorders is a pathogenic or independent factor for the variations in leg alignment. The purpose of this study was to elucidate the characteristics of the change in leg alignment after total hip arthroplasty (THA) and the morphological factors affecting the ipsilateral and contralateral leg alignment.

Methods

Both pre-operative and post-operative bilateral whole-leg radiographs in the standing position were taken in 100 patients who underwent THA. Hip-knee-ankle angle (HKAA), joint line convergence angle (JLCA), height of the hip center, lateral width to the hip center, femoral offset, and leg length discrepancy were measured. After the pre-operative legs were divided into the varus, neutral, or valgus groups, correlations between the change in HKAA and each hip morphological parameter were assessed.

Results

The mean change in HKAA on the THA side was 0.8° in the varus direction, which was significantly correlated with JLCA change. On the leg ipsilateral to THA, if the pre-operative alignment was valgus, the medial shift of the hip center was significantly correlated with the varus change in HKAA. On the side contralateral to THA, the change in leg length discrepancy was a significant correlative factor to the varus change in HKAA, if the pre-operative alignment was valgus or neutral.

Conclusion

The significant morphological parameters affecting the ipsilateral and contralateral leg alignment after THA were medial shifting of the hip center and the change in leg length discrepancy, respectively.

Level of evidence

Level Ⅳ, Retrospective cohort study.

True Mechanical Alignment is Found Only on Full-Limb and not on Standard Anteroposterior Radiographs

Purpose

The purpose of this study was to compare alignment measured on standard anteroposterior (AP) radiographs versus full-length weight-bearing radiographs.

Methods

Patients were prospectively enrolled from June 2019 to August 2019 from a single orthopedic surgeon's practice if they were ≥ 18 years of age, obtained both AP and full-length alignment radiographs and were capable of full weight-bearing with appropriate positioning. Patients were excluded if they were < 18 years of age, had previous knee arthroplasty, previous knee or hip osteotomy, were unable to bear full weight on both limbs, and if the patient's body habitus precluded appropriate visualization of necessary landmarks on the radiographs. Tibiofemoral angles were measured on AP radiographs using 2 techniques (AP angles 1 and 2). Linear regression and paired t tests were used to compare measurements. The minimal clinically important difference was defined as < 2°.

Results

There were 120 patients (62 males, 58 females) with an average age of 45 ± 17 years who were enrolled. There were positive correlations between average alignment on full-length weight-bearing and AP radiographs for AP angle 1 (r = 0.72) and AP angle 2 (r = 0.76) measurement techniques (P < .001). There was a significant difference in mean alignment between full-length weight-bearing and AP measurements (AP angle 1: 2.5° difference; AP angle 2: 4.4° difference; P < .001). Frequency distributions for the minimal clinically important difference between true mechanical alignment and AP views demonstrated that 46.7% of patients had ≥ 2° difference for AP angle 1, and 78.3% of patients had ≥ 2° difference for AP angle 2.

Conclusion

The average absolute difference in alignment measured between standard AP radiograph and full-length weight-bearing radiograph views was significant, with 46.7% to 78.3% of patients having a greater than 2° absolute difference between these 2 views. In cases where precise objective alignment measurement is necessary, full-length weight-bearing radiographs are recommended over standard AP radiographs for presurgical planning so as to reduce potential error in over- or underestimation of the true mechanical alignment.

Study Design

Prospective case-comparison; Level of evidence, 1.

Isolated meniscus extrusion associated with meniscotibial ligament abnormality

PURPOSE

The purpose of this study was to describe meniscus extrusion, present imaging characteristics, and provide clinical correlations for patients with isolated meniscus extrusion.

METHODS

Of the 3244 MRI reports identified as having meniscus extrusion, 20 patients were identified to have isolated meniscus extrusion (0.62%). Patients with moderate to severe chondromalacia, meniscus tears, intra-articular fractures, tumours, and ligament tears were excluded. Radiographs were reviewed and graded using Kellgren-Lawrence (K-L) scores. MRI's were reviewed for the extent of extrusion and whether or not the meniscotibial ligament was intact. Clinical presentation and management were recorded.

RESULTS

The study population consisted of 12 females and 8 males with a mean age of 40.5, diagnosed with meniscus extrusion and minimal concomitant knee pathology. 68% of patients were considered symptomatic as their knee pain correlated with the side of their meniscus extrusion and no other reason for pain was identified. The mean amount of meniscus extrusion was 2.5 mm (SD ± 1.1 mm) with 45% (9 of 20) having 3 + mm of extrusion. Meniscotibial ligament abnormality was identified in 65% of cases (13 of 20). Patients with 3 + mm of meniscus extrusion were much more likely to have associated meniscotibial ligament abnormality (100%, 9 of 9) compared to those with < 3 mm of extrusion (36%, 4 of 11) (RR 2.75, p = 0.048). The mean K-L grade obtained at the initial visit was 0.9 (95% CI 0.7-1.4) and the mean K-L grade obtained on final follow-up was 1.3 (95% CI 0.8-2.8) (n.s.) at a mean of 44.7 months. No correlation was found between K-L grade, gender, age, acute injury, and BMI in relation to meniscotibial ligament abnormality or amount of meniscal extrusion.

CONCLUSIONS

Meniscus extrusion often occurs in the presence of significant knee pathology, predominantly with meniscus tears or osteoarthritis. Isolated meniscus extrusion is a rare occurrence that may present clinically with knee pain, commonly to the side in which the extrusion occurs. In patients with three or more millimetres of meniscus extrusion, an intact meniscus and minimal knee pathology, meniscotibial ligament abnormality is likely. This may provide an opportunity to treat the meniscotibial ligament abnormality with meniscus centralisation technique and decrease the amount of meniscus extrusion.

Preoperative soft tissue laxity around knee was associated with less accurate alignment correction after hybrid closed-wedge high tibial osteotomy

PURPOSE

This study aimed to assess the effect of soft tissue correction due to knee joint laxity, which induces alignment error after hybrid closed-wedge high tibial osteotomy (CWHTO). In addition, to verify whether postoperative soft tissue correction can be predicted from preoperative radiographic parameters.

METHODS

A retrospective evaluation of data from patients treated by CWHTO in 2016-2019 was performed. Standing full-length anteroposterior radiograph measurement was performed pre- and post-surgery, and short anteroposterior radiographs of the knee under maximal manual varus and valgus stress were taken preoperatively. The weight-bearing line, hip-knee-ankle angle (HKA), medial proximal tibial angle (MPTA), and joint line convergence angle (JLCA) were measured, in addition to JLCA under varus or valgus conditions. Soft tissue correction was defined as ΔHKA minus ΔMPTA. Multiple regression analysis was performed to evaluate preoperative factors that could influence soft tissue correction.

RESULTS

Data from 49 knees were included in the analysis. The mean soft tissue correction was 3.2°, which indicates an over-correction. Multiple regression analysis revealed that JLCA (β = 0.642; p < 0.001) and valgus JLCA (β = - 0.422; p = 0.001) were significantly associated with postoperative soft tissue correction. The final model of the regression formula was described by the following equation: postoperative soft tissue correction = 0.691 × JLCA - 0.411 × valgus JLCA - 0.399.

CONCLUSION

Preoperative values for JLCA and JLCA under valgus stress are associated with soft tissue correction. Surgeons should, therefore, consider these measurements to achieve postoperative limb alignment.

Analysis of Risk Factors for Ramp Lesions Associated With Anterior Cruciate Ligament Injury

BACKGROUND

The incidence of meniscocapsular junction tears of the medial meniscus posterior horn, known as ramp lesions, is reported to be 9.3% to 23.9%. However, these lesions are not consistently diagnosed with routine arthroscopic exploration and magnetic resonance imaging (MRI).

PURPOSE

To determine risk factors associated with ramp lesions in anterior cruciate ligament-injured knees.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A total of 275 patients undergoing anterior cruciate ligament reconstruction between June 2011 and March 2019 were included in this study. Exclusion criteria were revisions, fracture histories, and multiple-ligament injuries other than medial collateral ligament injury. Patients were divided into 2 groups, those with and without ramp lesions according to arthroscopic diagnosis. Binary logistic regression was used to analyze risk factors: age, sex, body mass index, time from injury to surgery (<3 or ≥3 months), mechanism of injury (contact/noncontact), Segond fracture, side-to-side laxity, location of bone contusion, medial and lateral tibial/meniscal slope, and mechanical axis angle. Receiver operating characteristic curves and area under the curve were evaluated. A prediction model was developed by multivariable regression with generalized estimating equations.

RESULTS

Overall, 95 patients (34.5%) were confirmed as having a ramp lesion. The sensitivity of MRI for ramp lesions was 85.3%, and specificity was 78.3%. Significant risk factors for ramp lesion were as follows: posterior medial tibial plateau bone contusion on MRI (odds ratio [OR], 4.201; 95% CI, 2.081-8.482; P < .001), ≥3 months from injury (OR, 4.818; 95% CI, 2.158-10.757; P < .001), varus knee >3° (OR, 2.339; 95% CI, 1.048-5.217; P = .038), steeper medial tibial slope (OR, 1.289; 95% CI, 1.002-1.66; P = .049) and meniscal slope (OR, 1.464; 95% CI, 1.137-1.884; P = .003), and gradual lateral tibial slope (OR, 0.775; 95% CI, 0.657-0.914; P = .002). The area under the curve for the prediction model developed by logistic regression was 0.779 (sensitivity, 75.8%; specificity, 71.7%; P < .001) for ramp lesions.

CONCLUSION

Care should be taken with patients who have significant risk factors for ramp lesions, including bone contusion at the posterior medial tibial plateau, chronic injury, steeper medial tibial and meniscal slope, gradual lateral tibial slope, and varus knee >3°.

Reduction of in situ force through the meniscus with phased inner resection of medial meniscus: an experimental study in a porcine model

PURPOSE

Partial meniscectomy can cause osteoarthritic changes in knees, as inner portion as well as peripheral portion of meniscus is important. The hypothesis of this study was that the amount of the inner resection of medial meniscus affected the in situ forces through the meniscus and the tibial varus and external rotation under axial load.

METHODS

Fourteen intact porcine knees were investigated with a six-degree of freedom robotic system and force/moment, and the three-dimensional path of intact knees were recorded by universal force sensor when an axial load of 300-N was applied at four different flexion angles (30°, 60°, 90°, and 120°). The same examination was performed on three phased inner resections (30%, 60%, and 90% width) of the medial meniscus. Finally, all paths were reproduced after total medial meniscectomy, and in situ forces of the medial meniscus were calculated based on the superposition principle. Changes in tibiofemoral varus/valgus and internal/external rotation alignment during an axial load were also calculated.

RESULTS

In situ forces of the medial meniscus decreased according to the amount of meniscal resection at all flexion angles. The reduction was significant in knees with inner resections of > 60% width at all flexion angles and even of 30% width at a flexion angle of 120° (p < .05). Incremental changes in the tibiofemoral varus alignment increased depending on the inner resection width at all flexion angles (p < .05).

CONCLUSION

The amount of inner resection of the medial meniscus was related to reduction of its in situ forces and increment of the tibial varus rotation under axial load.

Tear gap and severity of osteoarthritis are associated with meniscal extrusion in degenerative medial meniscus posterior root tears

INTRODUCTION

Meniscal extrusion is a typical finding of medial meniscus posterior root tear, and it causes loss of the chondroprotective function of the meniscus as well as progression of osteoarthritis; it is therefore associated with poor clinical outcomes. The purpose of this study was to investigate factors associated with meniscal extrusion in degenerative medial meniscus posterior root tear. It was hypothesized that larger displacement from the posterior root insertion was associated with larger meniscal extrusion.

MATERIALS AND METHODS

One hundred and nine knees with degenerative medial meniscus posterior root tears were retrospectively reviewed. Multiple regression analysis was used to determine whether factors such as age, weight, body mass index, chondral wear at surgery, Kellgren-Lawrence (KL) grade, alignment, tibial slope, and tear gap on performing magnetic resonance imaging (MRI) were associated with meniscal extrusion. Subjects were divided based on the amount of displacement (displaced group: tear gap≥1mm, non-displaced group: tear gap<1mm) to compare meniscal extrusion, chondral wear, and severity of arthritis.

RESULTS

The mean age of the patients was 58.14±9.64years, the mean absolute extrusion was 4.02±1.22mm, the mean relative percentage of extrusion was 44.53±13.09%, and the mean tear gap was 2.39±2.42mm. Multiple regression analysis showed that absolute extrusion was only associated with tear gap on MRI (B=0.242, p=0.001) and that the relative percentage of extrusion was associated with tear gap (B=1.894, p=0.001) and the K-L grade (B=4.492, p=0.024). Absolute extrusion was significantly higher in the displaced group than in the non-displaced group (4.29±1.04mm vs. 3.01±1.35mm, p=0.001). Relative percentage of extrusion was also significantly higher in the displaced group than in the non-displaced group (47.70±11.44% vs. 36.17±13.65%, p=0.001). The proportion of chondral wear (Outerbridge grade III and IV) on the medial femoral condyle and K-L grade III and IV were significantly greater in the displaced group than in the non-displaced group (76% vs. 53.3%, p=0.023 and 13.9% vs. 0%, p=0.001, respectively).

DISCUSSION

Greater tear gap is significantly associated with increasing meniscal extrusion in medial meniscus posterior root tear. Additionally, severity of arthritis is significantly associated with increasing relative percentage of extrusion. Chondral wear and severity of arthritis tended to be significantly worse in the displaced group than in the non-displaced group.

LEVEL OF EVIDENCE

III, comparative retrospective study.