Tibiofemoral contact mechanics following a horizontal cleavage lesion in the posterior horn of the medial meniscus

Instructive cartilage regeneration modalities with advanced therapeutic implantations under abnormal conditions

The development of interdisciplinary biomedical engineering brings significant breakthroughs to the field of cartilage regeneration. However, cartilage defects are considerably more complicated in clinical conditions, especially when injuries occur at specific sites (e.g., osteochondral tissue, growth plate, and weight-bearing area) or under inflammatory microenvironments (e.g., osteoarthritis and rheumatoid arthritis). Therapeutic implantations, including advanced scaffolds, developed growth factors, and various cells alone or in combination currently used to treat cartilage lesions, address cartilage regeneration under abnormal conditions. This review summarizes the strategies for cartilage regeneration at particular sites and pathological microenvironment regulation and discusses the challenges and opportunities for clinical transformation.

Short-term outcomes of Oxford unicompartmental knee arthroplasty with coronal subluxation of the knee: a retrospective case–control study

Background

The goal of this study was to assess short-term outcomes in single compartment osteoarthritis patients associated with the coronal tibiofemoral subluxation (CTFS) of the knee joint after Oxford unicompartmental knee arthroplasty (OUKA), and to establish the potential impact of the degree of CTFS on operative outcomes.

Methods

Data pertaining to 183 patients with medial compartment osteoarthritis that underwent OUKA treatment between February 2016 and June 2019 were retrospectively analyzed. The presence and degree of severity of CTFS were assessed using preoperative weight-bearing anteroposterior X-ray images of the knee. Patients were stratified into three subgroups based upon the observed degree of subluxation: a normal group, a mild subluxation group (CTFS < 0.5 cm), and a severe subluxation group (CTFS ≥ 0.5 cm). Anterior and posterior X-ray examination of the knee was conducted at the time of most recent follow-up for each patient to assess the degree of CTFS correction following OUKA. Clinical function was assessed using Oxford knee score (OKS) and Hospital for Special Surgery score (HSS) values, while pain was rated using visual-analog scale (VAS) scores. The mechanical femoral tibial angle (mFTA), range of motion (ROM), and complication rates in these three groups were additionally compared.

Results

The average follow-up duration for patients in this study was 24.1 months (range: 17–32 months). There were no significant differences in patient age, sex, body mass index (BMI), follow-up duration, mFTA, ROM, OKS, HSS, or VAS scores among these three groups (P > 0.05). After surgery, OKS and HSS scores declined significantly, but no differences in these scores were observed among groups (P > 0.05). Of these patients, 135 (73.8%) were satisfied with the operation, of whom 80 (43.7%) were very satisfied. There were no significant differences in ROM or VAS scores among groups (P > 0.05). The degree of CTFS for patients in the mild and severe subluxation groups was significantly improved following OUKA relative to preoperative values such that the degree of postoperative CTFS did not differ significantly among these groups (P > 0.05). Postoperative mFTA was also significantly improved in these three patient subgroups (P < 0.05). No patients experienced operative complications over the follow-up period.

Conclusions

OUKA can successfully improve clinical symptoms in patients with single compartmental osteoarthritis. Moreover, OUKA can effectively correct CTFS of the knee in these patients, and the degree of preoperative CTFS has no impact on surgical efficacy.

Level of evidence

III.

Experimental and Finite Element Investigations on the Biomechanical Effects of Meniscal Tears in the Knee Joint: A Review

The knowledge of the complex biomechanical behaviour of the injured knee joints is of paramount importance in various clinical situations. A review of the biomechanical effects of meniscal tears based on experimental and finite element analysis has not been reported in the literature. The objective of this study is to present a review of experimental and finite element investigations on the consequences of meniscal tears such as longitudinal, radial, horizontal cleavage and root tears in the medial and lateral menisci. It is found that larger longitudinal tear in the medial meniscus has a significant impact on the magnitude of strain in the meniscus associated with a dramatic increase in CP in the tibial cartilage. Also, the untreated fragment of the torn meniscus leads to a significant rise in contact pressure in the cartilage resulting in the progressive degeneration of the cartilage surface. The radial tears in the lateral meniscus of more than 66% width and those in the medial meniscus of more than 75% width result in a substantial increase in the contact pressure in the cartilage compared to that in the intact knee joint. The root tears in the menisci demonstrate a significant influence on the biomechanical response of the knee joint. The results of finite element analysis studies are compared with experimental findings. Finally, some recommendations for future work are proposed to predict the realistic biomechanical response of the knee joints with meniscal tears. The results of this study present a rationale that could help surgeons in making clinical decisions when managing patients with meniscal tears.

Favorable Reoperation Rate at 2 Years Following Repair of Horizontal Cleavage Tears Using an All Suture-Based Technique: A Prospective, Multicenter Trial

Purpose

This prospective, multicenter trial evaluates the clinical success (as measured by reoperation rates and improvements in patient-reported outcome measures) of using circumferential compression stitches with all-suture techniques for horizontal cleavage tears (HCTs) of the meniscus.

Methods

Investigators enrolled 30 patients (mean age, 38.2 years; standard deviation, 11.1 years) aged 18 to 60 years with HCTs in the symptomatic compartment at 8 centers in the United States who underwent HCT repair with all-suture circumferential stitches using a self-retrieving all-inside suture passing device. Postoperative follow-up visits were conducted at 6 months, 1 year, and 2 years. Study outcomes included freedom from reoperation of the index meniscus repair site; knee pain and function, as measured by International Knee Documentation Committee Knee evaluation (IKDC), Knee injury and Osteoarthritis Outcome Score, Lysholm Knee Scale, and Tegner Activity Scale; and serious complications observed during the study. Minimal clinically important difference at 1 year was assessed for IKDC and Lysholm.

Results

Twenty-three patients had 2-year follow-up data available. Freedom from reoperation was 96.0% at 6 months (26/27, 91.7% at 1 year [23/25], and 82.6% at 2 years [19/23]). Significant improvement was observed in over baseline at 2 years for IKDC (36.7-82.5; P < .001), Knee injury and Osteoarthritis Outcome Score (52.2-89.3; P < .001), Lysholm (50.2-87.4; P < .001), and Tegner scores (3.3-5.3; P = .007). Minimal clinically important difference was met or exceeded for IKDC and Lysholm scores at 1 year 69.2% and 65.4% of patients, respectively. Four patients (6.7%) experienced serious complications, of which 2 were assessed as being related to the procedure.

Conclusions

Repair of HCTs using all-suture circumferential stitches placed with a self-retrieving all-inside suture passing device leads to a favorable reoperation rate (17.4%), significant improvements in clinical outcomes, and an acceptable rate of serious complications (6.7%) at 2 years, supporting the viability of this treatment approach in this indication.

Level of Evidence

Level IV, therapeutic case series.

Patient Outcomes After Horizontal Cleavage Tear Repair: A Systematic Review

PURPOSE

To analyze the clinical outcomes and survivorship of meniscal horizontal cleavage tear (HCT) repairs with hopes of guiding future treatment decisions.

METHODS

Standard systematic review methodology was used. A comprehensive search of PubMed was conducted on June 1, 2019. The inclusion criteria were articles that were published in English, involved human subjects, and reported on at least 1 outcome after repair of HCTs. The exclusion criteria included technique guides and reviews, studies without full text available, and studies with HCT outcomes not separated from other repair groups. Effect heterogeneity was determined using the I² measure. Forest plots were created in addition to a random-effects model to show the results.

RESULTS

The systematic review yielded 19 studies evaluating 289 knees in a total of 273 patients. At most recent follow-up, there was a high probability of return to sport (93.1% [67 of 72]). Overall, 74% of patients (67 of 90) were symptom free at last follow-up, and 80% expressed satisfaction with their overall result (80 of 100). The most frequently reported subjective outcome was the Lysholm score, which improved from a preoperative study range of 48 to 79 (I² = 20.7%, P = .283) to a postoperative study range of 56 to 99 (I² = 49%, P = .081). The next most commonly reported was the International Knee Documentation Committee subjective score, which improved from a preoperative study range of 16 to 49 (I² = 47.7%, P = .125) to a postoperative study range of 72 to 95 (I² = 0%, P = .660). An overall 11.7% reported risk of reoperation was found, with most cases involving revision meniscectomy. Rates of complications beyond fixation failure were overall very low, with infrequent reports of septic arthritis and transitory dysesthesia.

CONCLUSIONS

The short- to intermediate-term results of repair of HCTs are comparable to prior studies. Survivorship is comparable to repairs of other types of meniscal tears with high rates of return to sport and low complication rates.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I-IV studies.

Pathogenesis and clinical management of obesity-related knee osteoarthritis: Impact of mechanical loading

Obesity-related osteoarthritis (OA) is a complex, multifactorial condition that can cause significant impact on patients’ quality of life. Whilst chronic inflammation, adipocytokines and metabolic factors are considered to be important pathogenic factors in obesity related OA, there has been limited investigation into the biomechanical impact of obesity on OA development. This review aims to demonstrate that mechanical factors are the major pathological cause of obesity-related OA. The effect of obesity on pathological changes to the osteochondral unit and surrounding connective tissues in OA is summarized, as well as the impact of obesity-related excessive and abnormal joint loading, concomitant joint malalignment and muscle weakness. An integrated therapeutic strategy based on this multi-factorial presentation is presented, to assist in the management of obesity related OA.

The translational potential of this article

Despite the high prevalence of obesity-related OA, there is no specific guideline available for obesity-related OA management. In this review, we demonstrated the pathological changes of obesity-related OA and summarized the impact of biomechanical factors by proposing a hypothetical model of obesity-related OA change. Therapeutic strategies based on adjusting abnormal mechanical effects are presented to assist in the management of obesity-related OA.

Functional Outcomes of Arthroscopic Combined Anterior Cruciate Ligament Reconstruction and Meniscal Repair: A Retrospective Analysis

Purpose

To evaluate the outcomes of arthroscopic meniscal repair performed in combination with anterior cruciate ligament (ACL) repair.

Methods

This study presents a case series of 34 patients who underwent repair of meniscal tears along with ACL reconstruction from 2014 to 2016. Cases of discoid meniscal lesions and combined or ligament injuries other than ACL injuries were excluded. Patients were followed up periodically, at 3, 6, 9, 12, and 24 months. Preoperative and postoperative functional evaluations were performed using visual analog scale, International Knee Documentation Committee, and Lysholm knee scores.

Results

The mean age of the patients was 29.1 years (range, 17-44 years). The mean follow-up period was 18 ± 7.8 months (range, 6-24 months). Among the 34 individual knees, 1 patient (3%) underwent both medial and lateral meniscal repairs. Medial meniscal repair was performed in 20 knees (59%), whereas the lateral meniscus was repaired in 13 knees (38%). A longitudinal tear was the most common type of tear pattern, followed by radial (6 patients) and complex (3 patients) tear patterns. The radial and complex tears were treated with an additional partial meniscectomy. The mean International Knee Documentation Committee score was 38.46 preoperatively and improved to 80.30 at final postoperative follow-up (statistically significant difference, P < .01). The mean Lysholm score was 50.30 preoperatively and improved to 91.40 at final postoperative follow-up (statistically significant difference, P < .01). According to the Lysholm knee score, 31 patients (89%) had excellent or good results. The mean visual analog scale score decreased from 7.3 preoperatively to 2 postoperatively. The clinical success rate of the repairs was 89%. Of 35 repairs, 4 (11%) had retears.

Conclusions

Arthroscopic meniscal repair along with ACL reconstruction provided predictable high rates of meniscal healing and yielded favorable functional and clinical results. Patient selection remains one of the most important prognostic factors.

Level of Evidence

Level IV, therapeutic case series.

Effects of focal metallic implants on opposing cartilage - an in-vitro study with an abrasion test machine

Background

For focal cartilage defects, biological repair might be ineffective in patients over 45 years. A focal metallic implant (FMI) (Hemi-CAP Arthrosurface Inc., Franklin, MA, USA) was designed to reduce symptoms. The aim of this study was to evaluate the effects of a FMI on the opposing tibial cartilage in a biomechanical set-up. It is hypothesized that a FMI would not damage the opposing cartilage under physiological loading conditions.

Methods

An abrasion machine was used to test the effects of cyclic loading on osteochondral plugs. The machine applied a compressive load of 33 N and sheared the samples 10 mm in the anteroposterior direction by 1 Hz. Tibial osteochondral plugs from porcine knees were placed in opposition to a FMI and cycled for 1 or 6 h. After testing each plug was fixed, stained and evaluated for cartilage damage.

Results

After 1 h of loading (n = 6), none of the osteochondral plugs showed histologic signs of degradation. After 6 h of loading (n = 6) three samples had histologic signs of injury in the tangential zone (grade 1) and one had signs of injury in the transitional and deep zones (grade 2). Exploration for 6 h resulted in significant more cartilage damage compared to the shorter exploration time (p = 0.06). However, no significant difference between saline and hyaluronic acid was evident (p = 0.55).

Conclusion

Under physiologic loading conditions, contact with a FMI leads to cartilage damage in the opposing articular cartilage in six hours. In clinical practice, a thorough analysis of pre-existing defects on the opposing cartilage is recommended when FMI is considered.

Varus alignment aggravates tibiofemoral contact pressure rise after sequential medial meniscus resection

PURPOSE

Arthroscopic partial meniscectomy of medial meniscus tears and varus alignment are considered independent risk factors for increased medial compartment load, thus contributing to the development of medial osteoarthritis. The purpose of this biomechanical study was to investigate the effect of lower limb alignment on contact pressure and contact area in the knee joint following sequential medial meniscus resection. It was hypothesized that a meniscal resection of 50% would lead to a significant overload of the medial compartment in varus alignment.

METHODS

Eight fresh-frozen human cadaveric knees were axially loaded with a 750 N compressive force in full extension with the mechanical axis rotated to intersect the tibia plateau at 30%, 40%, 50%, 60% and 70% of its width. Tibiofemoral mean contact pressure (MCP), peak contact pressure (PCP), and contact area (CA) of the medial and lateral compartment were measured separately using pressure-sensitive films (K-Scan 4000, Tekscan) in four different meniscal conditions, respectively, intact, 50% resection, 75% resection, and total meniscectomy.

RESULTS

Medial MCP was significantly increased when comparing the intact meniscus to each meniscal resection in all tested alignments (p < 0.05). Following meniscal resection of 50%, MCP was significantly higher with greater varus alignment compared to valgus alignment (p < 0.05). Similarly, medial PCP was higher at varus alignment compared to valgus alignment (p < 0.05). Further resection to 75% and 100% of the meniscus resulted in a significantly higher medial PCP at 30% of tibia plateau width compared to all other alignments (p < 0.05). Medial CA of the intact meniscus decreased significantly after 50%, 75% and 100% meniscal resection in all alignments (p < 0.05). Lateral joint pressure was not significantly increased by greater valgus alignment.

CONCLUSION

Lower limb alignment and the extent of medial meniscal resection significantly affect tibiofemoral contact pressure. Combined varus alignment and medial meniscal resection increased MCP and PCP within the medial compartment, whereas valgus alignment prevented medial overload. As a clinical consequence, lower limb alignment should be considered in the treatment of patients undergoing arthroscopic partial meniscectomy with concomitant varus alignment. In patients presenting with ongoing medial joint tenderness and effusion, realignment osteotomy can be a surgical technique to unload the medial compartment.

Biomechanical Consequences of Meniscal Tear, Partial Meniscectomy, and Meniscal Repair in the Knee

UPDATE

This article was updated on April 26, 2018, because of a previous error. On pages 1 and 14, the author name that had read "Alan Z. Zhang, MD" now reads "Alan L. Zhang, MD."

Patterns of cartilage degeneration in knees with medial tibiofemoral offset

OBJECTIVE

To determine if radiographic medial tibiofemoral offset (MTFO) is associated with: (1) magnetic resonance imaging (MRI) pathology of cartilage, meniscus, and ligament; and (2) a distinct pattern of lateral cartilage degeneration on MRI.

MATERIALS AND METHODS

Three hundred consecutive adult knee MRIs with anteroposterior (AP) radiographs were retrospectively reviewed, and 145 studies were included. MTFO was defined as a medial extension of the medial femoral condyle beyond the articular surface of the medial tibial plateau on weight-bearing AP radiographs. The patients were then divided into the MTFO (n = 61) or no-offset (n = 84) groups. On MRI data obtained on a 1.5-Tesla system, articular cartilage of the femoral condyle and tibial plateau were graded using a modified Outerbridge classification (36 sub-regions similar to whole-organ MRI Score (WORMS) system). In addition, MR pathology of the ACL, MCL, LCL, medial and lateral menisci, were determined.

RESULTS

Significantly increased (ANOVA p < 0.007) MR grade of the ligaments, menisci, and cartilage in the MTFO group (ranging from 0.3 to 2.5) compared to the control group (0.2 to 1.1). Color maps of the cartilage grades suggested a marked difference in both severity of degeneration and regional variations between the groups. MTFO group exhibited focally increased cartilage grades in the central, non-weight regions of lateral compartment (region p = 0.07 to 0.12, interaction p = 0.05 to 0.1).

CONCLUSIONS

MTFO is associated with overall degeneration of the knee and features a distinct lateral cartilage degeneration pattern, which may reflect non-physiologic contact of the cartilage between the lateral tibial eminence and lateral central femoral condyle.

Effect of Lower Limb Alignment in Medial Meniscus-Deficient Knees on Tibiofemoral Contact Pressure

Background:

Degenerative medial meniscal tears and subsequent partial meniscal resection compromise meniscal function and lead to an overload of the medial compartment. In addition, lower limb alignment plays a key role in load distribution between the medial and lateral knee compartments, and varus alignment is a potential risk factor for medial osteoarthritis.

Purpose/Hypothesis:

The purpose of this biomechanical study was to investigate the effect of valgus and varus alignment on peak pressure and contact area in knees with concomitant horizontal medial meniscal tears and subsequent leaflet resection. It was hypothesized that varus alignment in combination with meniscal loss leads to the highest peak pressure within the medial compartment.

Study Design:

Controlled laboratory study.

Methods:

Six fresh-frozen human cadaveric knees were axially loaded using a 1000-N compressive load in full extension with the mechanical axis rotated to intersect the tibial plateau at 40%, 45%, 50%, 55%, and 60% of its width (TPW) to simulate varus and valgus alignment. Tibiofemoral peak contact pressure and contact area of the medial and lateral compartments were determined using pressure-sensitive foils in each of 4 different meniscal conditions: intact, 15-mm horizontal tear of the posterior horn, inferior leaflet resection, and resection of both leaflets.

Results:

The effect of alignment on peak pressure (normalized to the neutral axis) within the medial compartment in cases of an intact meniscus was measured as follows: varus shift resulted in a mean increase in peak pressure of 18.5% at 45% of the TPW and 37.4% at 40% of the TPW, whereas valgus shift led to a mean decrease in peak pressure of 8.7% at 55% of the TPW and 23.1% at 60% of the TPW. Peak pressure changes between the intact meniscus and resection within the medial compartment was less in valgus-aligned knees (0.21 MPa at 60% TPW, 0.59 MPa at 50% TPW, and 0.76 MPa at 40% TPW). Contact area was significantly reduced after partial meniscal resection in the neutral axis (intact, 553.5 ± 87.6 mm²; resection of both leaflets, 323.3 ± 84.2 mm²; P < .001). This finding was consistent in any alignment.

Conclusion:

Both partial medial meniscal resection and varus alignment led to an increase in medial compartment peak pressure. Valgus alignment prevented medial overloading by decreasing contact pressure even after partial meniscal resection. A horizontal meniscal tear did not influence peak pressure and contact area even in varus alignment.

Clinical Relevance:

As a clinical consequence, partial meniscal resection should be avoided to maintain the original biomechanical behavior, and the mechanical axis should be taken into account if partial meniscectomy is necessary.

Meniscal repair associated with a partial meniscectomy for treating complex horizontal cleavage tears in young patients may lead to excellent long-term outcomes

INTRODUCTION

While open repair of horizontal meniscal tears in young active patients has shown good results at mid- and long-term follow-up, complex horizontal tears (cleavage associated with meniscal flaps) are often treated by arthroscopic subtotal meniscectomy. The aim of this study was to evaluate long-term outcomes after arthroscopic removal of meniscal flaps associated with an open meniscal repair for treating complex lesions in young active patients. The hypothesis was that this salvage procedure would be efficient in such rare cases.

METHODS

Fourteen patients underwent an arthroscopic partial meniscectomy associated with an open meniscal repair to treat a painful complex horizontal meniscal cleavage between 2005 and 2010. There were two females and 12 males with a median age of 28.4 years (range 15-48 years). Patients were assessed by KOOS and IKDC scores, return to sport and the need for a secondary meniscectomy.

RESULTS

Thirty patients were evaluated at a median follow-up of 8.5 years (range 7-12 years). One patient required revision of a partial meniscectomy and one other a meniscal replacement (15% failure rate). All other patients showed improvement with regard to their symptoms and returned to sports, ten (91%) of them at the same level. The mean IKDC subjective score was 86.1 (± 10.9). The mean KOOS scores were: pain 91.4 (± 7.5), symptoms 91.4 (± 10.2), daily activity 97.1 (± 4), sports 84.4 (± 20.7) and quality of life 84 (± 14.2). For six patients, scores at median follow-up of 2.6 years were available and compared to newly obtained data. IKDC score at 8.6 years follow-up was not significantly different. KOOS scores for daily activity and sports were maintained.

CONCLUSIONS

Even in the presence of a complex lesion, horizontal cleavage can be repaired in young patients with good subjective and objective outcomes and a low rate of long-term failure as with other meniscal lesions in young active patients.

LEVEL OF EVIDENCE

IV.

Seventeen-Year Follow-up After Meniscal Repair With Concomitant Anterior Cruciate Ligament Reconstruction in a Pediatric and Adolescent Population

BACKGROUND

Studies have shown good and excellent clinical and radiographic results after meniscal repair. Limited published information exists on the long-term outcomes, however, especially in a pediatric and adolescent population.

PURPOSE

To determine long-term results of meniscal repair and concomitant anterior cruciate ligament (ACL) reconstruction in a pediatric and adolescent population. Specifically, the aims were to determine the clinical success rate of meniscal repair with concomitant ACL reconstruction, compare results with midterm outcomes, and analyze risk factors for failure.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Cases of meniscal repair with concomitant ACL reconstruction between 1990 and 2005 were reviewed among patients aged ≤18 years. Patient demographics, injury history, and surgical details were recorded, and risk factors for failure were analyzed. Physical examination findings and clinical outcomes at latest available follow-up were collected. Subjective knee outcomes were compared with midterm results. Descriptive statistics and univariate analysis were used to evaluate the available data.

RESULTS

Forty-seven patients (30 females, 17 males) with a mean age of 16 years (SD, 1.37) and a mean follow-up of 16.6 years (SD, 3.57) were included in this study. Overall, 13 patients (28%) failed meniscal repair and required repeat surgery at the time of final follow-up. Of the 13 failures, 9 underwent a subsequent meniscectomy; 2, meniscectomy and revision ACL reconstruction; 1, meniscal repair and revision ACL reconstruction; and 1, meniscal repair and subsequent meniscectomy. Mean International Knee Documentation Committee scores improved from 47.9 preoperatively to 87.7 postoperatively ( P < .01), and the mean score at long-term follow-up (87.7) did not significantly differ from that at the midterm follow-up (88.5) at a mean 7.4 years ( P = .97). Mean Tegner Activity Scale scores improved from 1.9 preoperatively to 6.3 postoperatively ( P < .01) and decreased from 8.3 at preinjury to 6.3 at final long-term follow-up ( P < .01).

CONCLUSION

In conclusion, the long-term overall clinical success rate (failure-free survival) was 72% for repair of pediatric and adolescent meniscal tears in the setting of concomitant ACL reconstruction. Patients reported excellent knee subjective outcome scores that remained favorable when compared with midterm follow-up.

Meniscus Repair and Replacement

The importance of preserving the function of the meniscus is seen with renewed interest. There has been an evolution of arthroscopic meniscus repair from inside-out, outside-in, meniscal fixators, to all-inside suturing techniques. Tear patterns once ignored or thought to be irreparable, such as root tears and horizontal cleavage tears, have recently been undergoing repair with promising results. Newer techniques have also recently allowed surgeons to address postmeniscectomy knee pain. Replacing lost tissue with scaffolds or replacing the meniscus with an allograft helps restore function and reduce degenerative changes.

Tibiofemoral Contact Mechanics With Horizontal Cleavage Tears and Treatment of the Lateral Meniscus in the Human Knee: An In Vitro Cadaver Study

BACKGROUND

Partial meniscectomy is one of the most commonly performed orthopaedic procedures for a meniscus tear. Decreased contact area and increased contact pressure have been seen in partial meniscectomies from treatment of various types of meniscal tears; however, the biomechanical effect of a horizontal cleavage tear in the lateral meniscus and subsequent treatment are unknown.

QUESTIONS/PURPOSES

This study asked whether a horizontal cleavage tear of the lateral meniscus, resecting the inferior leaf, and further resecting the superior leaf would (1) decrease contact area and (2) increase peak contact pressure.

METHODS

Eleven fresh-frozen human cadaveric knees were evaluated under five conditions of intact meniscus, horizontal cleavage tear, inferior leaf resection, and resection of the inferior and superior leaves of the lateral meniscus. Tibiofemoral contact area and pressure were measured at 0° and 60° knee flexion under an 800-N load, normalized to that at the intact condition of the corresponding knee flexion, and compared across the five previously described conditions.

RESULTS

At 0° knee flexion, normalized contact area with inferior leaf resection (65.4% ± 14.1%) was smaller than that at the intact condition (100% ± 0.0%, p < 0.001); smaller than horizontal cleavage tear (94.1% ± 5.8%, p = 0.001) contact area; and smaller than repaired horizontal tear (92.8% ± 8.2%, p = 0.001) contact area. Normalized contact area with further superior leaf resection (50.5% ± 7.3%) was smaller than that at the intact condition (100% ± 0.0%, p < 0.001); smaller than horizontal cleavage tear (94.1% ± 5.8%, p < 0.001) contact area; and smaller than repaired horizontal tear (92.8% ± 8.2%, p < 0.001) contact area. At 60° flexion, normalized contact area with inferior leaf resection (76.1% ± 14.8%) was smaller than that at the intact condition (100% ± 0.0%, p = 0.004); smaller than horizontal cleavage tear (101.8% ± 7.2%, p = 0.006) contact area; and smaller than repaired horizontal tear (104.0% ± 13.3%, p < 0.001) contact area. Normalized contact area with further superior leaf resection (52.1% ± 16.7%) was smaller than that at the intact condition (100% ± 0.0%, p < 0.001); smaller than horizontal cleavage tear (101.8% ± 7.2%, p < 0.001) contact area; and smaller than repaired horizontal tear (104.0% ± 13.3%, p < 0.001) contact area. At 60° flexion, contact area with both leaf resection (52.1% ± 16.7%) was smaller than that with inferior leaf resection (76.1% ± 14.8%, p = 0.039). At 0° knee flexion, peak pressure increased to 127.0% ± 22.1% with inferior leaf resection (p = 0.026) and to 138.6% ± 24.3% with further superior leaf resection (p = 0.002) compared with that at the intact condition (100% ± 0.0%). At 60° flexion, compared with that at the intact condition (100% ± 0.0%), peak pressure increased to 139% ± 33.6% with inferior leaf resection (p = 0.035) and to 155.5% ± 34.7% (p = 0.004) with further superior leaf resection.

CONCLUSIONS

Resection of the inferior leaf or both leaves of the lateral meniscus after a horizontal cleavage tear resulted in decreased contact area and increased peak contact pressure at 0° and 60° knee flexion.

CLINICAL RELEVANCE

In vitro resection of one or both leaves of a horizontal cleavage tear of the lateral meniscus causes increases in peak pressure, consistent with other types of partial meniscectomies associated in a clinical setting with excessive loading and damage to knee cartilage. Clinical outcomes in patients undergoing partial leaf meniscectomy could confirm this theory. Avoidance of resection may be relatively beneficial for long-term function. The findings of this in vitro study lend biomechanical support for nonoperative management.

Vertical Lasso and Horizontal Lasso Sutures for Repair of Horizontal Cleavage and Horizontal Oblique Meniscal Tears: Surgical Technique and Indications

Horizontal cleavage and horizontal oblique meniscal tears have traditionally been treated with partial meniscectomy. Recent research has shown the deleterious long-term effects of meniscectomy in these patients regarding the development of osteoarthritis. Meniscal preservation is thus the preferred method of surgical treatment in patients with these tears. However, traditional repair techniques using inside-out sutures or suture anchor-based devices do not address the horizontally aligned nature of these particular tears and thus do not compress the meniscal tissue in the correct plane. The recent development of an arthroscopic suture-passing system now allows surgeons to place arthroscopic sutures in any pattern or direction. This allows surgeons to treat tears of any type with sutures ideally placed to repair the given tears. This Technical Note describes and demonstrates 2 all-suture, all-inside, arthroscopic meniscus repair techniques to treat these challenging horizontal tear types. The repair techniques are named the vertical lasso and horizontal lasso.

Changes in Contact Area in Meniscus Horizontal Cleavage Tears Subjected to Repair and Resection

PURPOSE

To assess the changes in tibiofemoral contact pressure and contact area in human knees with a horizontal cleavage tear before and after treatment.

METHODS

Ten human cadaveric knees were tested. Pressure sensors were placed under the medial meniscus and the knees were loaded at twice the body weight for 20 cycles at 0°, 10°, and 20° of flexion. Contact area and pressure were recorded for the intact meniscus, the meniscus with a horizontal cleavage tear, after meniscal repair, after partial meniscectomy (single leaflet), and after subtotal meniscectomy (double leaflet).

RESULTS

The presence of a horizontal cleavage tear significantly increased average peak contact pressure and reduced effective average tibiofemoral contact area at all flexion angles tested compared with the intact state (P < .03). There was approximately a 70% increase in contact pressure after creation of the horizontal cleavage tear. Repairing the horizontal cleavage tear restored peak contact pressures and areas to within 15% of baseline, statistically similar to the intact state at all angles tested (P < .05). Partial meniscectomy and subtotal meniscectomy significantly increased average peak contact pressure and reduced average contact area at all degrees of flexion compared with the intact state (P < .05).

CONCLUSIONS

The presence of a horizontal cleavage tear in the medial meniscus causes a significant reduction in contact area and a significant elevation in contact pressure. These changes may accelerate joint degeneration. A suture-based repair of these horizontal cleavage tears returns the contact area and contact pressure to nearly normal, whereas both partial and subtotal meniscectomy lead to significant reductions in contact area and significant elevations in contact pressure within the knee. Repairing horizontal cleavage tears may lead to improved clinical outcomes by preserving meniscal tissue and the meniscal function.

CLINICAL RELEVANCE

Understanding contact area and peak contact pressure resulting from differing strategies for treating horizontal cleavage tears will allow the surgeon to evaluate the best strategy for treating his or her patients who present with this meniscal pathology.

Tibiofemoral Contact Mechanics with Horizontal Cleavage Tear and Resection of the Medial Meniscus in the Human Knee

BACKGROUND

The meniscus is known to increase the contact area and decrease contact pressure in the tibiofemoral compartments of the knee. Radial tears of the meniscal root attachment along with partial resections of the torn meniscal tissue decrease the contact area and increase pressure; however, there is a lack of information on the effects of a horizontal cleavage tear (HCT) and partial leaf meniscectomy of such tears on tibiofemoral contact pressure and contact area.

METHODS

Twelve fresh-frozen human cadaveric knees were tested under 10 conditions: 5 serial conditions of posterior medial meniscectomy (intact meniscus, HCT, repaired HCT, inferior leaf resection, and resection of both inferior and superior leaves), each at 2 knee flexion angles (0° and 60°) under an 800-N axial load. Tekscan sensors (model 4000) were used to measure the contact pressure and contact area.

RESULTS

HCT and HCT repair resulted in small changes in the contact area and an increase in contact pressure compared with the intact condition. Resection of the inferior leaf resulted in significantly decreased contact area (to a mean 82.3% of the intact condition at 0° of flexion and 81.8% at 60° of flexion; p < 0.05) and increased peak contact pressure (a mean 36.3% increase at 0° flexion and 43.2% increase at 60° flexion; p < 0.05) in the medial compartment. Further resection of the remaining superior leaf resulted in additional significant decreases in contact area (to a mean 60.1% of the intact condition at 0° of flexion and 49.7% at 60° of flexion; p < 0.05) and increases in peak contact pressure (a mean 79.2% increase at 0° of flexion and 74.9% increase at 60° of flexion; p < 0.05).

CONCLUSIONS

Resection of meniscal tissue forming the inferior leaf of an HCT resulted in substantially decreased contact area and increased contact pressure. Additional resection of the superior leaf resulted in a further significant decrease in contact area and increase in contact pressure in the medial compartment.

CLINICAL RELEVANCE

Repair or minimal resection of meniscal tissue of an HCT may be preferred to complete leaf resection to maintain knee tibiofemoral contact mechanics.

Arthroscopic Meniscectomy for Medial Meniscus Horizontal Cleavage Tears in Patients under Age 45

Purpose

The purpose of this study was to evaluate the demographics, clinical features, and outcomes of arthroscopic partial meniscectomy (APM) for isolated medial meniscus horizontal cleavage tears (MMHCTs) in patients under 45 years of age.

Materials and Methods

We retrospectively reviewed 98 patients (100 knees) under 45 years who underwent APM for MMHCTs. Clinical outcomes were assessed using International Knee Document Committee (IKDC) subjective core, Tegner activity scale, visual analog scale (VAS) pain score, and a question on the symptom relief.

Results

79% were male and 70% had no trauma. The mean symptom duration was 10 months. At arthroscopy, a flap tear was identified in 75%. At a mean of 19-month follow-up, the IKDC subjective score, Tegner activity scale, and VAS pain score were significantly improved compared to the preoperative values (p=0.025, p=0.043, and p=0.032, respectively). While 85% were free of symptoms, 15% had persistent pain. No significant differences in outcomes were observed based on the tear type and the presence of flap tears. No progression or development of radiographic degenerative changes was observed in all knees.

Conclusions

Demographics of MMHCTs under age 45 showed a male dominance and higher frequency of non-traumatic tears. APM was beneficial to symptomatic HCTs in this cohort during the short-term follow-up. Type of HCTs and combined flap tears did not affect clinical outcomes.

Patterns and Influencing Factors of Medial Meniscus Tears in Varus Knee Osteoarthritis

Purpose

To investigate the patterns of medial meniscus (MM) tears in patients with varus knee osteoarthritis who underwent total knee arthroplasty and analyze the factors that could affect MM tears.

Materials and Methods

The patients (365 knees, 268 patients) were classified into three groups; group I with MM posterior horn (PH) tear only; group II with MM root tear only; and group III with MMPH plus root tear. The following factors were evaluated: age, gender, body mass index, varus deviation of the mechanical axis, medial proximal tibial angle, posterior tibial slope (PTS), and anterior cruciate ligament (ACL) integrity (normal, degeneration, and tear or absence).

Results

MM tears were identified in all knees. The patterns of the combined MMPH tears in group III were less complex than those in group I. Varus deviation and PTS were significantly greater in group III than groups I and II. In group III, there were significantly more cases of ACL tear or absence than groups I and II. The others showed no differences among three groups.

Conclusions

Severe varus knee osteoarthritis was always accompanied by MM tears. Risk factors for MMPH plus root tears were severe varus deformity, great PTS, and ACL tear or absence.

Longitudinal change in quantitative meniscus measurements in knee osteoarthritis--data from the Osteoarthritis Initiative

OBJECTIVE

We aimed to apply 3D MRI-based measurement technology to studying 2-year change in quantitative measurements of meniscus size and position.

METHODS

Forty-seven knees from the Osteoarthritis Initiative with medial radiographic joint space narrowing had baseline and 2-year follow-up MRIs. Quantitative measures were obtained from manual segmentation of the menisci and tibia using coronal DESSwe images. The standardized response mean (SRM = mean/SD change) was used as measure of sensitivity to longitudinal change.

RESULTS

Medial tibial plateau coverage decreased from 34.8% to 29.9% (SRM -0.82; p < 0.001). Change in medial meniscus extrusion in a central image (SRM 0.18) and in the central five slices (SRM 0.22) did not reach significance, but change in extrusion across the entire meniscus (SRM 0.32; p = 0.03) and in the relative area of meniscus extrusion (SRM 0.56; p < 0.001) did. There was a reduction in medial meniscus volume (10%; p < 0.001), width (7%; p < 0.001), and height (2%; p = 0.08); meniscus substance loss was strongest in the posterior (SRM -0.51; p = 0.001) and weakest in the anterior horn (SRM -0.15; p = 0.31).

CONCLUSION

This pilot study reports, for the first time, longitudinal change in quantitative 3D meniscus measurements in knee osteoarthritis. It provides evidence of improved sensitivity to change of 3D measurements compared with single slice analysis.

KEY POINTS

• First longitudinal MRI-based measurements of change of meniscus position and size. • Quantitative longitudinal evaluation of meniscus change in knee osteoarthritis. • Improved sensitivity to change of 3D measurements compared with single slice analysis.