Varus alignment increases medial meniscus extrusion and peak contact pressure: a biomechanical study

Steeper Slope of the Medial Tibial Plateau, Greater Varus Alignment, and Narrower Intercondylar Distance and Notch Width Increase Risk for Medial Meniscus Posterior Root Tears: A Systematic Review

PURPOSE

To evaluate the available literature on the relationship between knee bony morphology and medial meniscus posterior root tears (MMPRTs) to determine which underlying tibiofemoral morphologic risk factors may predispose the development of MMPRTs.

METHODS

Embase, MEDLINE, and PubMed databases were searched to identify all relevant human clinical studies investigating knee morphologic features and MMPRTs. Shape features were compared between control groups and patients with MMPRTs. The methodological index for non-randomized studies (MINORS) instrument was utilized to assess the methodological quality of included studies.

RESULTS

Thirteen level III evidence studies and one level IV evidence study were included in this review (n=2,181), with 895 patients in the MMPRT group and 1,286 in the control group. Tibial morphology features associated with an increased risk for MMPRTs included an increased medial tibial slope (six studies), increased tibial torsion (one study), increased medial meniscal slope (one study), and shallower medial tibial plateau concavity (one study). Varus mechanical alignment was found to increase the risk for MMPRTs (four studies). Femoral morphology features associated with an increased risk for MMPRTs included an A-type intercondylar notch (one study), increased medial femoral condyle (MFC) angle (one study), narrower intercondylar distance (one study), narrower intercondylar notch width (one study), shorter MFC distal offset distance (one study), increased MFC width (one study), increased MFC to medial tibial condyle width ratio (one study), greater distance between the medial tibial eminence and MFC (one study), and smaller femoral offset ratios of both the medial and lateral condyles (one study).

CONCLUSION

Multiple tibiofemoral shape features, including a steeper slope of the medial tibial plateau, greater varus alignment, and a narrower intercondylar distance and notch width, were found to be predictive factors for MMPRTs.

LEVEL OF EVIDENCE

Level IV (Systematic review of Level III and IV studies).

Around-the-knee osteotomies part 1: definitions, rationale and planning-state of the art

Knee osteotomies are essential orthopedic procedures with the ability to preserve the joint and correct ligament instabilities. Literature supports the correlation between lower limb malalignment and outcomes after knee ligament reconstruction and cartilage procedures. Concepts such as joint line obliquity, posterior tibial slope angle, and intra-articular deformity correction are integral components of both preoperative planning and postoperative evaluations. The concept of preserving and/or restoring joint line congruence during simultaneous correction of varus or valgus deformity can be achieved through several different approaches. With advancements in osteotomy research and surgical planning technology, the surgical decision-making has increased in complexity. Based upon a patient's specific deformity, decisions need to be made whether to perform a single-level (proximal tibia or distal femur) versus double-level (both proximal tibia and distal femur) osteotomy, and whether to correct deformity in a single plane (coronal or sagittal) or perform a biplanar osteotomy, correcting two of the malalignments in either coronal, sagittal, or axial planes. Osteotomy procedures prioritize safety, reproducibility, precision, and meticulous planning. Equally important is the proactive management of possible complications and the implementation of preventive strategies for complications such as hinge fractures and unintentional changes to alignment in other planes. This review navigates the intricate landscape of lower limb alignment, commencing with foundational definitions and rationale for performing osteotomies, progressing through the planning phase, and addressing the critical aspect of complication prevention, all while looking ahead to anticipate future advancements in this field. However, rotational osteotomies and tibial tubercle osteotomies in isolation or as an adjunct procedure are beyond the scope of this review.

Preoperative Medial Meniscus Extrusion on Magnetic Resonance Imaging Is Associated With a Tendency Toward Varus Shifting of Open-Wedge High Tibial Osteotomy: A Minimum 5-Year Follow-Up Study

PURPOSE

To investigate serial changes in postoperative alignment over 5 years after open-wedge high tibial osteotomy (OWHTO) and to identify risk factors associated with alterations in the postoperative weightbearing line (WBL) ratio.

METHODS

Patients who underwent OWHTO during 2011-2017 were retrospectively reviewed. The inclusion criteria were (1) follow-up duration ≥5 years and (2) serial postoperative longstanding hip-to-ankle radiographs to evaluate alignment alterations. The WBL ratio was measured preoperatively and at 3 months, 6 months, 1 year, and 5 years postoperatively to evaluate serial changes. Alterations in the WBL ratio were analyzed using a linear mixed model, considering potential risk factors including International Cartilage Repair Society grades of each compartment and medial meniscus extrusion (≥3 mm). Clinical outcomes were assessed using the Knee Society objective and functional scores, and the correlations between clinical outcomes and alignment alteration were examined.

RESULTS

A total of 78 knees were investigated. During the study period, the overall WBL ratio decreased by 5.5% ± 7.2%, signifying varus shifting, from 58.6% ± 11.5% at 3 months postsurgery to 51.5% ± 12.7% at 5 years postsurgery. Based on univariate regression analyses, International Cartilage Repair Society grades of the medial compartment and medial meniscus extrusion were included in a linear mixed model regarding alignment alteration. The model identified medial meniscus extrusion as a significant risk factor after adjusting for time (P < .001). Medial meniscus extrusion also had a significant interaction with time (P < .001), indicating greater alignment alteration in cases of medial meniscus extrusion. The extrusion was noted in 68 of 78 knees.

CONCLUSIONS

In the midterm following OWHTO, the overall alignment had a tendency toward varus shifting. A linear mixed model found that preoperative medial meniscus extrusion on magnetic resonance imaging is associated with the tendency.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

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.

Signal intensity of repaired posterior roots after transtibial pullout repair for medial meniscus posterior root tears in stable knees: Magnetic resonance imaging evaluations at 3 years postoperatively

BACKGROUND

Only a few studies have assessed signal intensity after pullout repair for medial meniscus posterior root (MMPR) tears (MMPRTs) based on mid-term magnetic resonance imaging (MRI) evaluations. Therefore, this study aimed to assess the quantitative signal intensity of repaired posterior roots over time, up to 3 years postoperatively, and the related factors.

METHODS

This study included 36 patients who underwent pullout repair for MMPRTs and MRI examinations using the same MRI system. The signal intensity of the repaired posterior roots was quantitatively evaluated using the signal-to-noise quotient (SNQ). Medial meniscus extrusion (MME), the SNQ for MMPR, and clinical scores were assessed over 3 years postoperatively.

RESULTS

MME progressed over time until 3 years postoperatively, and its progression during this period was 1.61 ± 1.44 mm. The SNQ for MMPR decreased over time until 3 years postoperatively, and the change in the SNQ from 3 months to 3 years postoperatively (ΔSNQ) was 2.69 ± 1.69. All clinical scores significantly improved (p < 0.001). ΔSNQ was significantly correlated with body weight (correlation coefficient = -0.424, p = 0.010) and body mass index (correlation coefficient = -0.330, p = 0.050). However, ΔSNQ was not significantly correlated with preoperative or postoperative clinical scores.

CONCLUSION

After pullout repair for MMPRTs, MME progressed to 3 years postoperatively. However, the signal intensity of the repaired posterior roots decreased, and clinical scores improved over time until 3 years postoperatively. Patient weight and body mass index were significantly correlated with the reduced signal intensity of the repaired posterior roots, suggesting that weight assessment in patients with MMPRTs is crucial.

LEVEL OF EVIDENCE

IV.

Clinical Outcomes of Medial Meniscal Allograft Transplantation With or Without High Tibial Osteotomy: A Case-Control Study Up to 8 Years of Follow-up

BACKGROUND

Satisfactory clinical results of meniscal allograft transplantation (MAT) have been reported in recent years. However, it remains unclear whether the clinical outcomes of MAT when combined with an osteotomy are inferior to those of isolated MAT.

PURPOSE

To compare the survival rates and clinical outcomes of patients who received isolated medial MAT with those of patients undergoing medial MAT combined with high tibial osteotomy (HTO).

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 55 patients underwent arthroscopic medial MAT using the soft tissue technique and HTO (mean age, 41.3 ± 10.4 years; 9 female); after fuzzy case-control matching on demographics, 55 controls who underwent isolated medial MAT were also included. Survival analyses were performed using the Kaplan-Meier method with surgical failure, clinical failure (Lysholm score, <65), and reoperation as endpoints. Subjective clinical scores were collected preoperatively and at the final follow-up.

RESULTS

The mean follow-up time was 5.4 years, up to 8 years. All outcomes significantly improved at the last follow-up (P < .001). No differences were identified between MAT and MAT + HTO groups preoperatively and at the last follow-up (P > .05). At the final follow-up, 8 of 55 (14.5%) of the MAT + HTO patients and 9 of 55 (16.4%) of the MAT patients had a Lysholm score <65 (P = .885). Overall, 90% of the patients declared they would repeat the surgery regardless of the combined procedure. Surgical failure was identified in 6 of 110 (5.5%) patients: 5 of 55 (9.1%) in the MAT + HTO group and 1 of 55 (1.8%) in the MAT group (P = .093). Clinical failure was identified in 19 of 110 (17.3%) patients: 11 of 55 (20%) in the MAT + HTO group and 8 of 55 (14.5%) in the MAT group (P = .447). A significantly lower survivorship from surgical failure was identified in the MAT + HTO group (hazard ratio, 5.1; P = .049), while no differences in survivorship from reoperation and clinical failure were identified (P > .05).

CONCLUSION

Patients undergoing medial MAT + HTO showed similar clinical results to patients undergoing isolated medial MAT at midterm follow-up, and thus a surgically addressed malalignment does not represent a contraindication for medial MAT. However, the need for a concomitant HTO is associated with a slightly higher failure rate over time.

Subchondral insufficiency fractures of the medial tibial condyle are associated with medial meniscus extrusion: A retrospective observational study

BACKGROUND

To the best of our knowledge, no prior studies have identified any risk factors for subchondral insufficiency fractures of the medial tibial condyle. This study aimed to explain relationships between subchondral insufficiency fractures of the medial tibial condyle and the meniscus status, lower extremity alignment, or osteoporosis.

METHODS

This retrospective study included 325 consecutive patients whose chief complaint is knee joint pain and who had visited one institution between April 2016 and March 2021, of which 70 patients (8 men and 62 women) who had suspected subchondral insufficiency fractures of the medial tibial condyle had undergone magnetic resonance imaging and radiographic examination. These patients were divided into two groups based on the results of their magnetic resonance imaging: the insufficiency fracture group included 46 patients who had subchondral insufficiency fractures of the medial tibial condyle and the nonfracture group included 24 patients without fractures. The meniscus injury and medial meniscus extrusion (MME) were evaluated by using magnetic resonance imaging. The Kellgren-Lawrence grade, the femorotibial angle, and the percent mechanical axis (%MA) were evaluated with the use of knee radiographs. T-scores were also measured by using dual-energy X-ray absorptiometry with a bone densitometer.

RESULTS

MME were significantly larger and the %MA was significantly smaller in the insufficiency fracture group than that in the nonfracture group. The prevalence of medial meniscus injuries and pathological MME were higher in the insufficiency fracture group than those in the nonfracture group. The prevalence of varus knee and osteoporosis did not vary remarkably different between the two groups.

CONCLUSION

The patients who had insufficiency fractures of the medial tibial condyle tended to have medial meniscus extrusion.

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.

Temporary meniscus extrusion is caused by cumulative stress from uphill and downhill tasks in healthy volunteers

Purpose

Excessive mechanical stress accumulates and causes knee injury. Meniscal extrusion is a key factor in detecting the reaction to cumulative mechanical stress. The accumulation of stress strongly depends on environmental conditions such as flat ground or uphill/downhill, and accumulates in knee compartments; only a few studies have reported the effects of different environments on lateral and medial meniscus extrusion. This study aimed to investigate the effects of cumulative uphill/downhill stress on the meniscal extrusion in each compartment.

Methods

A total of 30 healthy volunteers with 30 affected knees were involved in this cohort study (mean age, 22.0 ± 1.1 years; men, n = 14). The participants were divided into flat-walking, uphill/downhill-walking, and uphill/downhill-jogging groups and their numbers of steps taken were recorded during the effort. Moreover, medial and lateral meniscal extrusions during walking were evaluated using ultrasound three times, before and after efforts (T1) and (T2), and one day after efforts (T3), respectively.

Results

In the flat-walking group, no significant differences were observed between the follow-up periods. Conversely, in the uphill/downhill-walking and jogging groups, the medial meniscus extrusion at T2 was significantly higher than that at T1. Conversely, the medial meniscus extrusion at T3 was significantly lower than that at T2. By contrast, the lateral meniscus did not show any difference between the follow-up periods in any group.

Conclusion

Temporary extrusion of the meniscus occurred after uphill/downhill tasks in healthy volunteers, and its reaction was observed only in the medial meniscus.

Arthroscopic pullout repair versus suture anchor repair for medial meniscus posterior root tear combined with high tibial osteotomy

BACKGROUND

The aim of this study was to compare the outcomes of pullout repair with a metal button and suture anchor repair for medial meniscus posterior root tears in patients undergoing high tibial osteotomy with varus alignment.

METHODS

Patients who underwent arthroscopic pullout repair (P group) and suture anchor repair (SA group) in combination with open-wedge high tibial osteotomy between 2018 and 2021 were retrospectively examined. Patients who received second-look arthroscopy at 1 year and at least 2 years of follow up were included. Structural healing (complete/partial or failed healing) and chondral lesions at the initial surgery and the second-look arthroscopy, radiographic parameters around the knee, Lysholm score, and Tegner activity scale (before and 2 years after surgery) were compared.

RESULTS

A total of 88 patients (68 women/20 men, mean age 61.1 ± 7.9 years old) were included in the analysis. Of these, 51 patients underwent pullout repair, while the other 37 underwent suture anchor repair. The SA group showed a significantly higher rate of complete healing (64.9%) than the P group (21.6%, P < 0.001). The Lysholm score significantly improved after surgery in both treatment groups. At the final follow up, the SA group had a significantly higher Lysholm score (89.6 ± 10.7) than the P group (80.9 ± 17.4, P = 0.011).

CONCLUSION

Arthroscopic suture anchor repair had superior healing status and Lysholm Score in comparison with pullout repair with a metal button, as it achieved better tension adjustment. This result is meaningful particularly when medial meniscus root repair and high tibial osteotomy are performed simultaneously.

Assessment of Radiological Outcomes of Medial Meniscus Posterior Root Tears Associated With Meniscal Extrusions After Open Wedge High Tibial Osteotomy

Objective The aim of this study is to compare preoperative and postoperative radiological results in knees with medial meniscus posterior root tears (MMPRT) and varus alignment, with a particular emphasis on medial meniscal extrusion (MME), following high tibial osteotomy (HTO) without root repair. Method Patients who underwent open wedge HTO for medial compartment osteoarthritis between January 2015 and December 2020 were retrospectively reviewed. The inclusion criteria were defined as patients with preoperative and postoperative magnetic resonance imaging (MRI) and weight-bearing radiographs including radiological images of the entire lower extremity. After conducting data screenings, patients diagnosed with a preoperative MMPRT were included in the study. Patients underwent measurements of medial proximal tibial angle (MPTA), mechanical lateral distal femoral angle (mLDFA), and mechanical axis deviation (MAD) on anteroposterior radiographs encompassing the entire lower extremity during the preoperative and postoperative first year. In order to determine the degree of arthritis, The Kellgren-Lawrence (KL) grading system was employed on preoperative and the most recent anteroposterior knee radiographs of the patients. MME, the distance (in millimeters) between the peripheral border of the meniscus body (meniscocapsular junction) and the medial border of the tibial plateau, was measured and calculated on coronal MRI. Preoperative and postoperative measurements of MPTA, MAD, MME, and KL staging were compared. Results The study included a total of 21 patients, comprising 7 males and 14 females. Among these, 6 were left-sided and 15 were right-sided cases, with an average age of 52.2 (±6.1) years. The mean follow-up duration for the patients was 5.4 (±2.3) years, with an average time of 2.2 (±1.6) years from surgery to the MRI. While significant differences were observed between preoperative and postoperative measurements for MAD and MPTA (p <0.01), no significant difference was found in MME measurement (p: 0.507). Pearson correlation analysis was employed to determine the correlation between preoperative and postoperative values of MME, MPTA, and MAD. A significant negative correlation was observed between preoperative MME and MPTA (r: -0.464, p:0.034). No significant correlation was found between postoperative MME and MAD or MPTA. Comparisons based on KL staging between the preoperative and postoperative periods did not reveal any significant differences (p: 0.525). Conclusion In knees with both MMPRT and varus alignment, our study demonstrated that postoperative MME and radiological progression of arthritis did not increase after HTO without MMPRT repair. These findings suggest that HTO treatment performed without MMPRT repair may prevent an increase in MME and the progression of arthritis. According to the results of our study, we observed a negative correlation between MME and MPTA during the preoperative period, which supports the relationship between varus deformity and MME.

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.

[Periarticular knee osteotomies for pre-arthritic deformities in the frontal plane : Indications and surgical techniques]

BACKGROUND

Currently, periarticular knee joint osteotomies are an integral part of the treatment of early arthritic deformities in the knee joint.

DIAGNOSTICS

Analysis of the deformity is performed with a standardized full-leg standing x‑ray of both legs, as well as a lateral x‑ray of the knee joint that includes 2/3 of the proximal tibial shaft. An MRI examination of the knee joint is obtained to assess the articular cartilage, the ligaments and menisci. Torsion angle measurements with the CT/MRT supplement the diagnostics if necessary. Knowledge of normal physiological values and their standard deviations of the mechanical leg axis and the joint angles around the knee is obligatory.

THERAPY

The osteotomy is performed as close as possible to the femoral and/or tibial deformity. Postsurgical deformities including pathological patella position or a significant difference in leg length must be prevented. A description of proximal tibia opening or closing wedge osteotomies based on the nomenclature of the joint angles by Paley is presented. The indications for the various osteotomy techniques in the coronary plane are discussed in detail.

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.

Management after acute rupture of the anterior cruciate ligament (ACL). Part 1: ACL reconstruction has a protective effect on secondary meniscus and cartilage lesions

PURPOSE

The aim of this consensus project was to validate which endogenous and exogenous factors contribute to the development of post-traumatic osteoarthritis and to what extent ACL (anterior cruciate ligament) reconstruction can prevent secondary damage to the knee joint. Based on these findings, an algorithm for the management after ACL rupture should be established.

METHODS

The consensus project was initiated by the Ligament Injuries Committee of the German Knee Society (Deutsche Kniegesellschaft, DKG). A modified Delphi process was used to answer scientific questions. This process was based on key topic complexes previously formed during an initial face-to-face meeting of the steering group with the expert group. For each key topic, a comprehensive review of available literature was performed by the steering group. The results of the literature review were sent to the rating group with the option to give anonymous comments until a final consensus voting was performed. Consensus was defined a-priori as eighty percent agreement.

RESULTS

Of the 17 final statements, 15 achieved consensus, and 2 have not reached consensus. Results of the consensus were summarized in an algorithm for the management after ACL rupture (infographic/Fig. 2).

CONCLUSION

This consensus process has shown that the development of post-traumatic osteoarthritis is a complex multifactorial process. Exogenous (primary and secondary meniscus lesions) and endogenous factors (varus deformity) play a decisive role. Due to the complex interplay of these factors, an ACL reconstruction cannot always halt post-traumatic osteoarthritis of the knee. However, there is evidence that ACL reconstruction can prevent secondary joint damage such as meniscus lesions and that the success of meniscus repair is higher with simultaneous ACL reconstruction. Therefore, we recommend ACL reconstruction in case of a combined injury of the ACL and a meniscus lesion which is suitable for repair.

LEVEL OF EVIDENCE

Level V.

Association between bone marrow lesions and bone mineral density of the proximal tibia in end-stage osteoarthritic knees

This retrospective cross-sectional study investigated the association between bone marrow lesions (BMLs) and bone mineral density (BMD) in the proximal tibia of end-stage osteoarthritic knees from a large patient sample. Overall, 1308 end-stage osteoarthritic knees were enrolled before total knee arthroplasty. The preoperative range of motion was recorded. Bone mineral density in the medial tibial plateau (MTP), lateral tibial plateau (LTP), and metaphysis were measured using dual-energy X-ray absorptiometry. The MTP/LTP, MTP/metaphysis, and LTP/metaphysis ratios were calculated. BMLs were scored using a whole-organ magnetic resonance imaging scoring system. The relationship between BMD and BML scores was investigated using linear regression analysis. The highest BMD was 0.787 ± 0.176 g/cm² at the MTP, followed by 0.676 ± 0.180 g/cm² and 0.572 ± 0.145 g/cm² at the metaphysis and LTP, respectively. The prevalence of BMLs was 90.4% and 24.2% in the MTP and LTP, respectively. In women, higher BML scores at the MTP were positively correlated with the BMD of the MTP (p < 0.001, r = 0.278), MTP/LTP (p < 0.001, r = 0.267), and MTP/metaphysis ratios (p < 0.001, r = 0.243). Regression analysis showed that higher BML scores in the MTP were correlated with higher BMD in the MTP (p < 0.001) and lower BMD in the LTP (p < 0.001). High BML scores in the MTP were positively associated with high BMD in the MTP, which also induced the medial to lateral imbalance of BMD in the proximal tibia.

Evaluation of the bone tunnel position and state of healing on second-look arthroscopy after pullout repair of medial meniscus posterior root tear during open-wedge high tibial osteotomy

BACKGROUND

The aim of the present study was to evaluate the outcome of pullout repair of medial meniscus posterior root tear during open-wedge high tibial osteotomy, including the bone tunnel position and the state of healing on second-look arthroscopy.

METHODS

The cohort comprised 22 patients (six men, 16 women) who underwent arthroscopic root fixation by the transtibial pullout technique for medial meniscus posterior root tear during open-wedge high tibial osteotomy. The mean patient age was 63.7 years. The location of the tibial tunnel was assessed using a percentage-dependent method, and the location of a critical point was determined by two coordinates on CT. We defined the distance between the tibial tunnel center and the medial meniscal posterior root anatomic center as the TC-AC distance. The healing state was classified as complete, partial, or failed on second-look arthroscopy. Patients were categorized into those with complete or partial healing (group H) and those with failed healing (group F). The differences in the outcomes and characteristics of groups H and F were evaluated.

RESULTS

Twelve and 10 knees were classified into groups H and F, respectively. The bone tunnel position was significantly more posterior in group H than in group F. The TC-AC distance was significantly shorter in group H than in group F.

CONCLUSIONS

In pullout repair of medial meniscus posterior root tear during open-wedge high tibial osteotomy, it was considered important to create a bone tunnel position more posterior to increase the healing rate on second-look arthroscopy.

LEVEL OF EVIDENCE

Level Ⅳ.

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.

High-grade preoperative osteoarthritis of the index compartment is a major predictor of meniscal allograft failure

INTRODUCTION

Preoperatively available predictors of meniscal allograft failure would help in patient counseling and surgical indication for meniscal allograft transplantation (MAT). It was hypothesized that young patient age, high posterior tibial slope (PTS), and high-grade osteoarthritis (OA) are predictors of meniscal allograft failure.

MATERIALS AND METHODS

Patients undergoing MAT with a minimum follow-up of 2 years were included in this retrospective study. Demographic and surgical data, and causes of meniscal allograft failure were collected. PTS and degree of OA (low-grade: Kellgren-Lawrence 0, 1, and 2; high-grade: Kellgren-Lawrence 3 and 4) of the index and opposite tibiofemoral compartments were determined on preoperative radiographs.

RESULTS

This study included 77 patients with a mean age of 25.7 ± 10.1 years at the time of MAT. After a mean follow-up of 7.6 ± 5.6 years, meniscal allograft failure was observed in 26 patients (34%). The median time from MAT to meniscal allograft failure was 1.3 years (inter-quartile range, 2.5 years). Meniscal allograft tears (88%) were the primary cause of graft failure, followed by high-grade OA (12%). Patients experiencing meniscal allograft failure were an average of 2.7 years (95% CI [2.2, 7.5], p = 0.202) older at the time of MAT than patients without failure. PTS was not found to be a predictor of meniscal allograft failure (odds ratio, 0.884 (95% CI [0.727, 1.073], p = 0.212)). Patients with high-grade preoperative OA of the index compartment had 28 times higher odds of experiencing meniscal allograft failure than patients with low-grade preoperative OA (p = 0.008).

CONCLUSIONS

High-grade preoperative OA of the index compartment was found to be a significant and clinically relevant predictor of meniscal allograft failure. Surgeons should be aware of the impact of OA on meniscal allograft survival, which needs to be considered in patient counseling and surgical indication for MAT in patients.

Increasing the posterior tibial slope lowers in situ forces in the native ACL primarily at deep flexion angles

High tibial osteotomy is becoming increasingly popular but can be associated with unintentional posterior tibial slope (PTS) increase and subsequent anterior cruciate ligament (ACL) degeneration. This study quantified the effect of increasing PTS on knee kinematics and in situ forces in the native ACL. A robotic testing system was used to apply external loads from full extension to 90° flexion to seven human cadaveric knees: (1) 200 N axial compressive load, (2) 5 Nm internal tibial + 10 Nm valgus torque, and (3) 5 Nm external tibial + 10 Nm varus torque. Kinematics and in situ forces in the ACL were acquired for the native and increased PTS state. Increasing PTS resulted in increased anterior tibial translation at 30° (1.8 mm), 60° (1.7 mm), and 90° (0.9 mm) flexion and reduced in situ force in the ACL at 30° (57.6%), 60° (69.8%), and 90° (75.0%) flexion in response to 200 N axial compressive load. In response to 5 Nm internal tibial + 10 Nm valgus torque, there was significantly less (39.0%) in situ force in the ACL at 90° flexion in the increased compared with the native PTS state. Significantly less in situ force in the ACL at 60° (62.8%) and 90° (67.0%) flexion was observed in the increased compared with the native PTS state in response to 5 Nm external tibial + 10 Nm varus torque. Increasing PTS affects knee kinematics and results in a reduction of in situ forces in the native ACL during compressive and rotatory loads at flexion angles exceeding 30°. In a controlled laboratory setting PTS increase unloads the ACL, affecting its natural function.

Internal tibial torsion is associated with medial meniscus posterior horn tears

PURPOSE

Risk factors for meniscal tears play a decisive role in deciding on treatment and rehabilitation. The purpose of this study was to investigate the effect of tibial rotation on medial meniscus posterior horn tears (MMPHTs).

METHODS

This study is a retrospective case-control study. Fifty patients with meniscal tears and 57 knees with intact meniscus were compared. Tibial rotation, femoral version, tibial slope and knee varus were measured in each participant. Knee osteoarthritis was classified according to the Kellgren-Lawrence classification. Demographic characteristics were noted.

RESULTS

There were significant differences in the mean tibial torsion angles and mean mechanical axes between the groups. The mean tibial rotation and mean mechanical axis were 26.3° ± 6.7 and 3.7° ± 2.7 in the MMPHT group and 30.3° ± 8.4 and 2.05° ± 2.7 in the control group, respectively (p = 0.008, p = 0.002).

CONCLUSION

The current retrospective study has shown that tibial rotation is markedly reduced in patients with MMPHTs. Although the actual mechanism is not clear, the internal torsion of the tibia causes a decrease in the foot progression angle and increases the knee adduction moment, which in turn increases the medial tibial contact pressure. Internal torsion of the tibia, such as knee varus, may play a role in the aetiology of MMPHTs by this way. Whilst there was a significant difference in the mean varus and tibial torsion between the groups, there was no significant difference in the mean femoral version or tibial slope.

LEVEL OF EVIDENCE

III.

Increased medial meniscus extrusion led to worse clinical outcomes after medial opening-wedge high tibial osteotomy

PURPOSE

Given that no studies have assessed the correlation between improvements in medial meniscus extrusion (MME) and clinical outcomes after medial opening-wedge high tibial osteotomy (MOWHTO), the present study aimed to measure the improvement in MME after MOWHTO and to investigate the correlation between the remaining postoperative MME and MOWHTO clinical outcomes by subgroup analysis.

METHODS

This study included 79 patients (80 knees) who underwent MOWHTO with a minimum follow-up of 2 years. MME was measured pre- and postoperatively through magnetic resonance imaging after an average of 19.8 months following MOWHTO surgery. Clinical outcomes were evaluated according to the Knee Injury and Osteoarthritis Outcome Score (KOOS), the Tegner Activity Scale, and the Short-Form 36 questionnaire. In subgroup analysis, postoperative MME was classified into non-pathologic (≤ 3 mm) and pathologic (> 3 mm) groups. The clinical outcomes of the two groups were compared using Mann-Whitney U tests. A regression analysis was performed to determine the preoperative and postoperative characteristics associated with the improvement of MME.

RESULTS

The mean (± standard deviation) values for pre- and postoperative MME were 3.6 (± 1.8) mm and 2.8 (± 1.5) mm, respectively (p < 0.001). In the subgroup analysis of postoperative MME, the non-pathologic group showed better improvement of KOOS than the pathologic group. Preoperative hip-knee-ankle angle was correlated with the improvement of medial meniscal extrusion in both univariate (p = 0.049) and multivariate (p = 0.015) analyses.

CONCLUSION

The MME improved after MOWHTO, and the clinical outcomes were better for patients with a postoperative MME of less than 3 mm than for those with more than 3 mm. MME improvement after MOWHTO was correlated with preoperative varus alignment of the lower extremities.

LEVEL OF EVIDENCE

III (Retrospective cohort study).

High tibial osteotomy for medial meniscus posterior root tears in knees with moderate varus alignment can achieve favorable clinical outcomes

Purpose

Favorable clinical results have been reported following high tibial osteotomy (HTO) for medial meniscus posterior root tear (MMPRT) in knees with varus alignment. However, the effect on the preoperative neutral alignment of the knee is not known. This study sought to evaluate the clinical outcomes of medial open-wedge HTO for MMPRT with neutral alignment.

Methods

We retrospectively reviewed 119 medial open-wedge HTOs and analyzed 22 knees with MMPRT. The knees were divided according to the preoperative hip-knee-ankle angle into a moderate varus alignment group (≤4° of varus alignment) and a varus alignment group (> 4° of varus alignment). The Knee Injury and Osteoarthritis Outcome Score (KOOS) and Forgotten Joint Score-12 (FJS-12) values were evaluated preoperatively and at the latest follow-up. The healing status of MMPRT at the time of second-look arthroscopy, performed at a mean of 15.4 ± 4.2 months, was compared with that after the primary HTO.

Results

There were 11 knees in the moderate varus alignment group and 11 in the varus alignment group. In terms of perioperative patient-reported outcome measures, there was no significant difference in the preoperative or postoperative KOOS subscale score or FJS-12 score between the moderate varus and varus alignment groups. The healing rate was significantly higher in the moderate varus alignment group.

Conclusion

Favorable clinical results were obtained by medial open-wedge HTO in knees with MMPRT and moderate varus alignment in the short term. Surgeons should consider the indications for medial open-wedge HTO, even with moderate varus alignment, when planning treatment for MMPRT with persistent knee pain.

Level of evidence

IV

Supplementary Information

The online version contains supplementary material available at 10.1186/s40634-022-00504-9.

Repairing Complete Radial Tears of the Lateral Meniscus: Arthroscopic All-Inside Double Vertical Cross-Suture Technique Is Effective and Safe With 2-Year Minimum Follow-Up

PURPOSE

To assess the failure rate and clinical outcomes of the all-inside, double-vertical, cross-suture technique in repairing complete radial tears of the lateral meniscus.

METHOD

We retrospectively reviewed records of patients with this injury on whom the present technique was employed at our institution between 2011 and 2018, with at least 24 months of follow-up. Six months postoperatively, the meniscus healing and extrusion status were evaluated through magnetic resonance imaging. Preoperative and postoperative knee function, measured through IKDC, Lysholm knee, and Tegner activity scale scores, were compared.

RESULTS

In total, 27 patients underwent the procedure. The preoperative mean (standard deviation) IKDC score, Lysholm knee score, and Tegner activity scale scores were 53.4 ± 5.3, 63.2 ± 9.3, and 4 ± .7, respectively. At the last follow-up (≥24 months postoperatively), these scores increased to 92.1 ± 2.6, 90.8 ± 4.2, and 6.1 ± 1.3, respectively (all P < .05). Complete healing of the meniscus was observed in 23 patients, and 4 patients had meniscus retear or nonhealing. The overall retear or nonhealing rate was 14.8%. Healing rates between those with isolated radial tears (87.5%) and those with combined anterior cruciate ligament rupture (84.2%; P = .826) were comparable. No difference was observed in the progression of coronal and sagittal meniscus extrusion (P = .133 and .797, respectively).

CONCLUSION

In patients with complete radial tears of the lateral meniscus, the arthroscopic all-inside double vertical cross-suture repair technique resulted in an 85.2% healing rate, improvements in functional outcomes and activity levels, and no identifiable progression of meniscus extrusion. The all-inside double vertical cross-suture technique is effective and safe for the repair of radial tears of the meniscus.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Treatment of Malalignment and Cartilage Injury: High Tibial Osteotomy With a Concomitant Osteochondral Allograft to the Medial Femoral Condyle and Lateral and Medial Partial Meniscectomy

In patients with full-thickness focal cartilage defects, osteochondral allograft is a technique for restoration of hyaline cartilage; however, in patients with genu varum, the diseased compartment of the knee is generally offloaded as well. A high tibial osteotomy presents a biomechanical solution to malalignment of the knee and offloading of the diseased compartment of the knee. The purpose of this Technical Note is to present our preferred technique to treat focal cartilage damage in a varus misaligned knee coupling a high tibial osteotomy with an osteochondral allograft to the medial femoral condyle, along with partial medial and lateral meniscectomy.

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.

Meniscal Extrusion: A Narrative Review

Background:

Meniscal extrusion, referred to as an external displacement of the meniscus, is a commonly encountered but often overlooked magnetic resonance imaging finding in the knee joint. Meniscal extrusion alters the biomechanical properties of the meniscus, leading to accelerated cartilage degeneration and early osteoarthritic changes. The literature contains discrepancies about meniscal extrusion on topics ranging from definition to diagnosis. This narrative review outlines the pathogenesis, natural history, diagnosis, and treatment of meniscal extrusion.

Purpose:

To review the current literature on meniscal extrusion, from pathogenesis to treatment, and to provide recommendations for future research.

Study Design:

Narrative review.

Methods:

A computer-based search of the PubMed, Ovid Medline, and Cochrane Library databases was used to perform a comprehensive literature review on meniscal extrusion. A total of 81 studies was ultimately included in the review.

Results:

The literature review highlighted the current ambiguity in definition, difficulty in clinical diagnosis, and low level of awareness of this condition. This review covers all aspects related to meniscal extrusion and identifies many of its lesser known aspects.

Conclusion:

In the current literature, meniscal extrusion remains a lesser known albeit common condition because of its relatively silent nature along with lack of knowledge among orthopaedic surgeons. Further studies are warranted to provide better understanding and management of this condition.

[Posterior meniscus root tears]

Meniscus root tears are radial tears in the region of the posterior insertion zones. Medial root injuries usually occur in individuals > 50 years of age without adequate trauma and are associated with obesity and varus deformities. The root lesion leads to a loss of ring tension, which results in extrusion of the meniscus and a strong increase in joint pressure that is biomechanically equivalent to a complete meniscectomy. When indicating arthroscopic transosseous refixation of the medial root lesion, factors such as accompanying cartilage damage, osteoarthritis, obesity and varus deformity must be taken into account. Injuries to the root of the lateral meniscus are mostly observed in younger patients in combination with a rupture of the anterior cruciate ligament. Arthroscopic transosseous refixation in combination with cruciate ligament surgery is therefore also recommended for type I and type II lesions. In summary, both the medial and the lateral root lesions of the menisci are injuries with high biomechanical relevance.

Effects of and Response to Mechanical Loading on the Knee

Mechanical loading to the knee joint results in a differential response based on the local capacity of the tissues (ligament, tendon, meniscus, cartilage, and bone) and how those tissues subsequently adapt to that load at the molecular and cellular level. Participation in cutting, pivoting, and jumping sports predisposes the knee to the risk of injury. In this narrative review, we describe different mechanisms of loading that can result in excessive loads to the knee, leading to ligamentous, musculotendinous, meniscal, and chondral injuries or maladaptations. Following injury (or surgery) to structures around the knee, the primary goal of rehabilitation is to maximize the patient's response to exercise at the current level of function, while minimizing the risk of re-injury to the healing tissue. Clinicians should have a clear understanding of the specific injured tissue(s), and rehabilitation should be driven by knowledge of tissue-healing constraints, knee complex and lower extremity biomechanics, neuromuscular physiology, task-specific activities involving weight-bearing and non-weight-bearing conditions, and training principles. We provide a practical application for prescribing loading progressions of exercises, functional activities, and mobility tasks based on their mechanical load profile to knee-specific structures during the rehabilitation process. Various loading interventions can be used by clinicians to produce physical stress to address body function, physical impairments, activity limitations, and participation restrictions. By modifying the mechanical load elements, clinicians can alter the tissue adaptations, facilitate motor learning, and resolve corresponding physical impairments. Providing different loads that create variable tensile, compressive, and shear deformation on the tissue through mechanotransduction and specificity can promote the appropriate stress adaptations to increase tissue capacity and injury tolerance. Tools for monitoring rehabilitation training loads to the knee are proposed to assess the reactivity of the knee joint to mechanical loading to monitor excessive mechanical loads and facilitate optimal rehabilitation.

The Natural History of Medial Meniscal Root Tears: A Biomechanical and Clinical Case Perspective

Posterior medial meniscus root tears (PMMRTs) make up a relatively notable proportion of all meniscus pathology and have been definitively linked to the progression of osteoarthritis (OA). While known risk factors for development of OA in the knee include abnormal tibial coronal alignment, obesity and female gender, PMMRTs have emerged in recent years as another significant driver of degenerative disease. These injuries lead to an increase in average contact pressure in the medial compartment, along with increases in peak contact pressure and a decrease in contact area relative to the intact state. Loss of the root attachment impairs the function of the entire meniscus and leads to meniscal extrusion, thus impairing the force-dissipating role of the meniscus. Anatomic meniscus root repairs with a transtibial pullout technique have been shown biomechanically to restore mean and peak contact pressures in the medial compartment. However, nonanatomic root repairs have been reported to be ineffective at restoring joint pressures back to normal. Meniscal extrusion is often a consequence of nonanatomic repair and is correlated with progression of OA. In this study, the authors will describe the biomechanical basis of the natural history of medial meniscal root tears and will support the biomechanical studies with a case series including patients that either underwent non-operative treatment (5 patients) or non-anatomic repair of their medial meniscal root tears (6 patients). Using measurements derived from axial MRI, the authors will detail the distance from native root attachment center of the non-anatomic tunnels and discuss the ongoing symptoms of those patients. Imaging and OA progression among patients who were treated nonoperatively before presentation to the authors will be discussed as well. The case series thus presented will illustrate the natural history of meniscal root tears, the consequences of non-anatomic repair, and the findings of symptomatic meniscal extrusion associated with a non-anatomic repair position of the meniscus.

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.

High Tibial Osteotomy for Varus Deformity of the Knee

High tibial osteotomy is a powerful technique to treat symptomatic varus deformity of the knee and is successful when properly indicated and performed. Indications include varus deformity with medial compartment osteoarthritis, cartilage or meniscus pathology. Several techniques exist to correct symptomatic varus malalignment along with concomitant procedures to restore cartilage or meniscus injuries. Evidence supporting high tibial osteotomy for symptomatic medial compartment pathology exists, which provides a durable solution for joint preservation. This review will discuss the indications, techniques, and outcomes for high tibial osteotomies used in the treatment of symptomatic varus deformity of the knee.

[The influence of axial deformities and their correction on the development and progression of osteoarthritis]

Die Beachtung der Beinachse und die Möglichkeiten zur deren Korrektur stellen beim jungen Patienten mit Arthrose ein Grundpfeiler der Therapie dar. Die Kombination einer Gelenksverletzung und einer Achsdeviation führt unweigerlich, je nach Ausmaß und Komorbiditäten, schon nach wenigen Jahren zur fortschreitenden Gonarthrose. Neben der genauen Deformitätenanalyse zur Osteotomieplanung, gilt es, Normbereiche der entsprechenden Winkel zu kennen und eine Zielgröße zur Achskorrektur festzulegen. Aus dem Repertoire der verschiedenen kniegelenksnahen Osteotomien sind dann die Nebeneffekte in Bezug auf patellofemorales Maltracking, ligamentäres Balancing und die Beinlänge abzuschätzen. Gerade im Hinblick auf mögliche (und wahrscheinliche) Folgeoperationen beim jungen Patienten müssen neue knöcherne Deformitäten oder ligamentäre Insuffizienzen, welche potenziell bei Überkorrektur entstehen, unbedingt vermieden werden.

Remodified Mason-Allen suture technique concomitant with high tibial osteotomy for medial meniscus posterior root tears improved the healing of the repaired root and suppressed osteoarthritis progression

PURPOSE

To evaluate the results of the remodified Mason-Allen suture technique concomitant with high tibial osteotomy (HTO) for medial meniscal posterior root tears (MMPRTs). The hypothesis was that this procedure would improve clinical results, prevent progression of knee osteoarthritis and increase the healing rate of the repaired root.

METHODS

Total 17 patients of mean 51.5 ± 4.4 years who were underwent this combined procedure for MMPRT completed this study. Lysholm and Hospital for Special Surgery (HSS) scores, Kellgren-Lawrence (KL) grade reflecting osteoarthritis progression were evaluated preoperatively and at the last follow-up. Medial meniscus extrusion (MME) was measured on magnetic resonance imaging preoperatively and at mean 26.1 ± 2.3 months postoperatively. Second-look arthroscopy was performed at mean 25.1 ± 5.3 months postoperatively. The healing status of the repaired root was classified as complete, partial and failed healing. The Outerbridge (OB) grade of the medial femoral condyle (MFC) was compared between index surgery and second-look arthroscopy.

RESULTS

Mean follow-up duration was 66.4 ± 6.5 months. Mean Lysholm and HSS mean scores improved significantly from preoperatively to the last follow-up: Lysholm: 56.9 ± 5.4 to 83.5 ± 6.0 (P < 0.001); HSS: 56.1 ± 6.0 to 81.7 ± 7.7 (P < 0.001). The mean mechanical alignment of the lower extremity was corrected from varus to the neutral range at the last follow-up. The preoperative KL grade was not significantly different from the KL grade at the last follow-up (P = 0.071). On MRI, mean MME increased from 3.0 ± 0.7 mm to 3.1 ± 0.7 mm (P = 0.046). Second-look arthroscopy showed 64.7% complete, 29.4% partial and 5.9% failed healing of the repaired root. The initial OB grade of the MFC showed no progression (P = 0.103).

CONCLUSIONS

The remodified Mason-Allen suture technique concomitant with HTO for MMPRTs significantly improved clinical outcomes and suppressed OA progression at 66.4 months. However, this procedure produced limited complete healing of the repaired roots in 64.7% of patients.

LEVEL OF EVIDENCE

IV.

Hip-to-calcaneus alignment differs from hip-to-talus alignment in patients with genu varum deformity

PURPOSE

To (1) compare the weight-bearing line (WBL) ratios of the knee joints measured using the conventional (hip-to-talus radiographs, HTRs) and novel (hip-to-calcaneus radiographs, HCRs) orthoradiograms, (2) compare the hip-knee-ankle (HKA) angle between cases with < 5% and > 5% differences in WBL ratios between two orthoradiograms, and (3) investigate the optimal cutoff value (COV) of the HKA angle causing inconsistency in the orthoradiograms.

METHODS

Sixty limbs of 31 patients with HTR and HCR records were retrospectively reviewed. After drawing the mechanical axis on each radiograph, the WBL ratios of the knees were calculated and compared between the conventional and novel orthoradiograms. In subgroup analysis, cases with < 5% and > 5% differences in WBL ratios between two orthoradiograms were classified as consistent and inconsistent groups, respectively. Receiver operating characteristic curve based on the HKA angles of the lower limbs was used to identify the COV causing the inconsistency between the orthoradiograms.

RESULTS

Inter- and intra-rater reliabilities of all radiologic measurements were > 0.75. The WBL ratios showed no significant difference between the two orthoradiograms. However, the HKA angle was significantly larger in the inconsistent group than in the consistent group (7.0° ± 1.8° vs. 4.4° ± 2.5°; P < 0.001). The COV of the HKA angle that caused inconsistency in the two orthoradiograms was 4.0° (area under the curve, 0.774).

CONCLUSION

The hip-to-calcaneus alignment differed significantly from the hip-to-talus alignment in patients with genu varum deformity. HCR measurement can be a complementary method for planning corrective osteotomy for patients with genu varum deformity.

LEVEL OF EVIDENCE

IV.

Mild to Moderate Varus Alignment in Relation to Surgical Repair of a Medial Meniscus Root Tear: A Matched-Cohort Controlled Study With 2 Years of Follow-up

BACKGROUND

Increased varus alignment of the lower extremity is known to be a poor prognostic factor for the surgical repair for a medial meniscus root tear (MMRT). However, given the concept of constitutional varus, which is present in a substantial portion of the normal population, the generally accepted surgical indication for MMRT concerning a varus alignment of 5° may be unnecessarily narrow.

PURPOSE

To compare the surgical outcomes of arthroscopic transtibial pullout repair of MMRT according to the degree of varus alignment of the lower extremity.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Patients who underwent isolated arthroscopic transtibial pullout repair of MMRT between January 2010 and July 2017 at one institution and had a minimum follow-up of 2 years were included in this study. Patients were classified into 1 of 2 groups: the experimental group (n = 22) included patients with a preoperative hip-knee-ankle angle between 5° and 10° varus (mild to moderate varus alignment) and the control group (n = 51) included those with a preoperative hip-knee-ankle angle <5° varus (neutral alignment). Clinical scores and radiographic parameters were compared between the groups to assess surgical outcomes, which were statistically matched for potential confounders (age, body mass index, the severity of cartilage lesion) by use of the inverse probability of treatment weighting. A noninferiority trial was performed comparing the experimental and control groups in terms of subjective outcomes (International Knee Documentation Committee subjective and Lysholm scores) and objective outcomes (postoperative medial meniscal extrusion and the rate of osteoarthritis progression).

RESULTS

There were no statistically significant differences in surgical outcomes between the groups in subjective and objective aspects, which were consistent before and after inverse probability of treatment weighting. Apart from the clinical improvement observed in both groups, overall degenerative changes in the knee were found, although progression rates did not differ between the groups. In terms of the noninferiority trial, the overall surgical outcomes in the experimental group were not inferior to those in the control group.

CONCLUSION

The short-term surgical outcomes of arthroscopic transtibial pullout repair for MMRT of patients with mild to moderate varus alignment were not inferior to but rather comparable with those with neutral alignment in terms of subjective and objective aspects. Therefore, it would be inappropriate to exclude patients with a diagnosis of MMRT from being indicated for the surgery simply because of mild to moderate varus alignment.

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.

Sonographic evaluation of lateral meniscal extrusion: implementation and validation

INTRODUCTION

Meniscal extrusion (ME) is an important indicator of and prognostic factor for various knee pathologies. To date, no standardized protocol for the ultrasound-based examination of lateral ME exists. The purpose of the present study was to test the reliability and validity of lateral ME measurements using a standardized ultrasound-based examination protocol.

MATERIALS AND METHODS

A group consisting of 11 healthy volunteers (Group I, male and female, 18-45 years) as well as a group of 10 consecutive patients who had undergone all-inside lateral meniscal radial tear repair were included (Group II, male and female, 23-43 years). Lateral ME, the main outcome parameter, was measured by ultrasound (US; both groups) and magnetic resonance imaging (MRI; Group II only). Both knees of all subjects were examined in an unloaded state and under axial compression of the knee (50% of body weight). Repeated measurements obtained in Group I by 2 observers were used for reliability testing, and the validity of US was assessed through comparison with MRI data (Group II).

RESULTS

A total of 66 US images of Group I, obtained by each observer, were analyzed for reliability testing. Forty US and MR images of Group II were assessed for validation. Results showed good interrater (ICC = 0.904) and excellent intrarater (ICC = 0.942) reliability of US-based measurements of lateral ME. Agreement with MRI results was poor (ICC = 0.439), with US systematically overestimating results by 1.1 mm on average.

CONCLUSIONS

Ultrasound is a reliable, quick and cost-effective technique for lateral ME measurement, but results are not readily comparable with MRI.

TRIAL REGISTRATION

The study was registered in the European Union Clinical Trials Register (EudraCT-Number: 2017-005037-24).

Arthroscopic Centralization of the Extruded Medial Meniscus

Tears of the posterior medial meniscus root commonly result in extrusion of the meniscus and disruption of tibiofemoral contact mechanics. Transtibial pull-through repair of the root often results in healing of the tear, but postoperative extrusion may persist. In this scenario, the meniscus is unlikely to be chondroprotective. Therefore, an additional centralization procedure is necessary to improve the extrusion. Biomechanical studies have demonstrated that centralization can improve meniscus mechanics and potentially reduce the risk of osteoarthritis. This Technical Note describes an arthroscopic technique for medial meniscus posterior root repair that combines transtibial pullout and centralization sutures.

Chondral lesions at the medial femoral condyle, meniscal degeneration, anterior cruciate ligament insufficiency, and lateral meniscal tears impair the middle-term results after arthroscopic partial meniscectomy

PURPOSE

The aim of the present study was to analyse which clinical, radiological and arthroscopic findings are able to predict the postoperative outcome after arthroscopic partial meniscectomy. Furthermore, the present study aimed to investigate the postoperative outcome after partial meniscectomy in patients with degenerative meniscal lesions.

METHODS

A total of 91 patients with a follow-up period of 34.7 ± 11.4 months after arthroscopic partial meniscectomy were included in this retrospective study. Clinical, radiological, and arthroscopic data were analysed at the time of follow-up. The multivariable linear regression analysis for postoperative outcome, based on the Western Ontario Meniscal Evaluation Tool (WOMET), included age, gender, body mass index, physical activity, presence of cartilage lesions, leg alignment, grade of radiographic osteoarthritis, location of meniscal lesions, meniscal extrusion, meniscal degeneration, presence of an anterior cruciate ligament tears as well as bone marrow lesions.

RESULTS

WOMET and WOMAC scores showed a significant improvement of 45.0 ± 48.1 points (CI 34.9-55.1; p ≤ 0.0001) and 75.1 ± 69.3 points (CI 60.6-89.6; p = 0.001) within the follow-up period. Multivariable linear regression analysis showed that poor preoperative WOMET scores (p = 0.001), presence of cartilage lesions at the medial femoral condylus (p = 0.001), meniscal degeneration (p = 0.008), the presence of an anterior cruciate ligament lesion (p = 0.005), and lateral meniscal tears (p = 0.039) were associated with worse postoperative outcomes. Patients with femoral bone marrow lesions had better outcome (p = 0.038).

CONCLUSION

Poor preoperative WOMET scores, presence of cartilage lesions at the medial femoral condylus, meniscal degeneration, concomitant anterior cruciate ligament lesions as well as lateral meniscal tears are correlated with worse postoperative outcomes after arthroscopic partial meniscectomy. Patients with femoral bone marrow lesions femoral are more likely to gain benefit from arthroscopic partial meniscectomy in the middle term. Despite justified recent restrictions in indication, arthroscopic partial meniscectomy seems to effectively reduce pain and alleviate symptoms in carefully selected patients with degenerative meniscal tears.

LEVEL OF EVIDENCE

III.

Criterion validity of ultrasound in the identification of calcium pyrophosphate crystal deposits at the knee: an OMERACT ultrasound study

OBJECTIVE

To evaluate the discriminatory ability of ultrasound in calcium pyrophosphate deposition disease (CPPD), using microscopic analysis of menisci and knee hyaline cartilage (HC) as reference standard.

METHODS

Consecutive patients scheduled for knee replacement surgery, due to osteoarthritis (OA), were enrolled. Each patient underwent ultrasound examination of the menisci and HC of the knee, scoring each site for presence/absence of CPPD. Ultrasound signs of inflammation (effusion, synovial proliferation and power Doppler) were assessed semiquantitatively (0-3). The menisci and condyles, retrieved during surgery, were examined microscopically by optical light microscopy and by compensated polarised microscopy. CPPs were scored as present/absent in six different samples from the surface and from the internal part of menisci and cartilage. Ultrasound and microscopic analysis were performed by different operators, blinded to each other's findings.

RESULTS

11 researchers from seven countries participated in the study. Of 101 enrolled patients, 68 were included in the analysis. In 38 patients, the surgical specimens were insufficient. The overall diagnostic accuracy of ultrasound for CPPD was of 75%-sensitivity of 91% (range 71%-87% in single sites) and specificity of 59% (range 68%-92%). The best sensitivity and specificity were obtained by assessing in combination by ultrasound the medial meniscus and the medial condyle HC (88% and 76%, respectively). No differences were found between patients with and without CPPD regarding ultrasound signs of inflammation.

CONCLUSION

Ultrasound demonstrated to be an accurate tool for discriminating CPPD. No differences were found between patents with OA alone and CPPD plus OA regarding inflammation.

Preoperative Medial Meniscal Extrusion Is Associated With Patient-Reported Outcomes After Medial Opening Wedge High Tibial Osteotomy

BACKGROUND

Although the medial compartment continues to sustain some loading after medial opening wedge high tibial osteotomy (MOWHTO) in varus-deformed knees, no studies have examined the relationship between medial meniscal extrusion (MME) and patient-reported outcome measures after MOWHTO.

PURPOSE

To examine whether compartmental baseline MME was associated with patient-reported outcome measures after MOWHTO.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

This retrospective study was composed of 149 MOWHTOs in 147 patients with clinical and radiological assessments. Patients were grouped according to severity of MME in the medial compartment at the time of surgery. MME was categorized into 4 groups according to MOAKS (MRI [magnetic resonance imaging] Osteoarthritis Knee Score) criteria and relative value of MME. We compared preoperative characteristics, including Kellgren-Lawrence (KL) grading scale, meniscal tear pattern, and postoperative Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) subscores. Associations between extent of MME and WOMAC subscores at postoperative 1 and 2 years were assessed with generalized linear models.

RESULTS

Pattern of meniscal tear (P < .05) and KL grade (P < .05) were associated with MME. Patients with KL grades 3 and 4 at the time of surgery had significantly greater MME than those with KL grade 2 (P < .05). When patients were divided into 4 groups according to MOAKS criteria at the time of surgery, there were significant differences in WOMAC pain scores among groups at 1 and 2 years after the operation (all P < .05). The WOMAC function score also differed among groups at postoperative 1 year (P < .05) but not postoperative 2 years (P > .05). When patients were divided into 4 groups according to relative MME at the time surgery, the WOMAC pain score differed significantly among groups at postoperative 1 and 2 years (all P < .05). Analysis of WOMAC pain score as the dependent variable in multivariate analyses revealed that severity of absolute and relative MME and KL grade were independent predictors of worse WOMAC pain score at postoperative 1 and 2 years (all P < .05).

CONCLUSION

Greater preoperative MME at the time of surgery was associated with inferior patient-reported outcomes, especially pain, in patients with MOWHTO at 1 and 2 years after surgery.

Meniscal substitution, a developing and long-awaited demand

The menisci represent indispensable intraarticular components of a well-functioning knee joint. Sports activities, traumatic incidents, or simply degenerative conditions can cause meniscal injuries, which often require surgical intervention. Efforts in biomechanical and clinical research have led to the recommendation of a meniscus-preserving rather than a meniscus-resecting treatment approach. Nevertheless, partial or even total meniscal resection is sometimes inevitable. In such circumstances, techniques of meniscal substitution are required. Autologous, allogenic, and artificial meniscal substitutes are available which have evolved in recent years. Basic anatomical and biomechanical knowledge, clinical application, radiological and clinical outcomes as well as future perspectives of meniscal substitutes are presented in this article. A comprehensive knowledge of the different approaches to meniscal substitution is required in order to integrate these evolving techniques in daily clinical practice to prevent the devastating effects of lost meniscal tissue.

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.