Inside-Out Versus All-Inside Repair of Isolated Meniscal Tears: An Updated Systematic Review

Comparison of Subsequent Surgery After Repair in Bucket-Handle Meniscal Tears and Meniscectomy Analysis of a Large, Contained Cohort Study

Background

Bucket-handle meniscal tears are large longitudinal vertical meniscal tears that have an attached fragment flipped into the intercondylar notch. Meniscal repair attempts to restore the function of the meniscus and aims to preserve joint mechanics. Alternatively, meniscectomy results in quicker recovery but may lead to future degeneration.

Purposes

To evaluate the long-term risk of subsequent ipsilateral knee surgery in patients who underwent a bucket-handle meniscal repair (BHMR) versus meniscectomy/bucket-handle meniscal debridement (BHMD) and assess risk factors associated with subsequent knee surgical intervention.

Study Design

Cohort study; Level of evidence, 3.

Methods

An electronic health records search for all patients who underwent arthroscopic knee meniscal surgery (repair and meniscectomy) between 2011 and 2018 was performed. Natural language processing was used to search for terms of interest in the long operative notes to determine whether these surgeries were performed for bucket-handle meniscal tears. These patients comprised our initial cohort. Study patients were followed for at least 1 year and for up to 5 years (until December 31, 2019), with censoring at death or membership disenrollment. Baseline patient characteristics and outcomes were evaluated via a database review. The primary outcome was subsequent ipsilateral knee surgeries and secondary outcomes included contralateral knee surgeries, deep surgical site infections, and venous thrombotic events. Multivariable logistic regression analyses were used to model for subsequent surgical treatment of the ipsilateral knee. A subset analysis for patients aged 30 to 50 years was then performed.

Results

The median follow-up time was 52.4 months (interquartile range [IQR], 33.5-60 months). A total of 1359 patients underwent BHMR and 1537 patients underwent BHMD. The median age was 24 years (IQR, 17-34 years) for the BHMR versus 38 years (IQR, 27-47 years) for the BHMD group (P < .001). Body mass index (BMI) was significantly lower in the BHMR group compared with the BHMD group (P < .001). BHMR was significantly more likely to be performed during a concomitant ipsilateral anterior cruciate ligament reconstruction (ACLR) than a BHMD (44.2% vs 30.1%, P < .001). During the follow-up period, a total of 656 subsequent ipsilateral procedures were performed in 393 (13.6%) patients. Patients who underwent initial BHMR were at a significantly higher risk of undergoing subsequent meniscal repair (4.3% vs 1%, P < .001), meniscectomy (12.1% vs 3.3%, P < .001), and ACLR (7.4% vs 2.9%, P < .001) compared with those who underwent BHMD. Multivariable analysis showed that BHMR, younger age, and lower BMI were risk factors for subsequent ipsilateral surgery. After adjusting for patient demographic and clinical characteristics, subset analysis showed that for patients aged 30 to 50 years, undergoing a BHMR versus a BHMD led to a 2.3-fold higher risk of subsequent surgery, a 5.3-fold higher risk of subsequent meniscal repair and a 3.2-fold higher risk of subsequent meniscectomy.

Conclusion

BHMR was more often performed in younger patients with a lower BMI, especially during a concomitant ACLR. Patients treated with BHMR were more likely to undergo subsequent surgeries, with the likelihood decreasing with increasing age. Subset analyses showed increasing risk for subsequent surgeries with BHMR versus BHMD in the cohort consisting of patients aged 30 to 50 years.

Survey Results Concerning Current Trends in Meniscus Repair Indications and Preferences from Members of the Pediatric Research in Sports Medicine (PRiSM) Society

Meniscus repair has increased in frequency, especially among surgeons who focus on youth sports injuries. The aim of this study was to determine current trends in meniscus repair among a specific subset of meniscus repair surgeons. A cross-sectional survey utilizing several clinical vignettes was administered to orthopaedic surgeon members of the Pediatric Research in Sports Medicine (PRiSM) Society to investigate surgeon experience and training, number of meniscus repair procedures performed, and surgical and rehabilitation preferences. A statistical analysis of the responses was performed to determine associations between years in practice or type of fellowship training and the number of meniscus repair procedures performed, surgical indications, and rehabilitation preferences. The response rate to various questions ranged from 61.5 (59/96) to 63.5% (61/96). In all vignettes, a majority favored repair as well as some degree of weight-bearing and range-of-motion restrictions. Surgeons who had been in practice for 6 to 10 years performed significantly more meniscus repairs per year than those who had been in practice for greater than 20 years (p = 0.009) and those who had been in practice for 0 to 5 years (p = 0.05). Surgeons who had been in practice for greater than 20 years performed a significantly higher percentage of meniscectomies relative to meniscus repairs, compared with those in practice for 0 to 5 years (p = 0.002) or 6 to 10 years (p = 0.0003). When surgeons were grouped into those with less than 10 years of experience and those with greater than 10 years of experience, the former group performed a significantly higher number of meniscus repairs relative to meniscectomies than the latter group of surgeons (p < 0.0001). Less experienced surgeons are more likely to perform meniscus repair than meniscectomy, but all surgeons surveyed had a general preference for repair in all clinical vignettes. Repair technique preferences as well as rehabilitation protocols varied widely among surgeons.

Meniscus Tears in Elite Athletes: Treatment Considerations, Clinical Outcomes, and Return to Play

PURPOSE OF REVIEW

Management of meniscal injuries in the elite athlete is a difficult problem secondary to the high demands of athletic competition, the need for a timely return to sport, and the desire to maximize performance over time. The purpose of this review is to provide an up-to-date summary on the current literature and trends regarding the management of meniscus injuries with a special consideration for elite athletes.

RECENT FINDINGS

Historically, partial meniscectomy has been the primary treatment option for meniscus injuries. However, in recent years there has been an increased emphasis on meniscus preservation due to the increased risk of cartilage degeneration over time. Moreover, while partial meniscectomy still provides a quicker return to sport (RTS), recent literature has demonstrated similar rates of RTS and return to pre-injury levels between partial meniscectomy and meniscus repair. In the setting of symptomatic meniscal deficiency, meniscus allograft transplantation has become an increasingly utilized salvage procedure with promising yet variable outcomes on the ability to withstand elite competition. Currently, there is no uniform approach to treating meniscal injuries in elite athletes. Therefore, an individualized approach is required with consideration of the meniscus tear type, location, concomitant injuries, athlete expectations, rehabilitation timeline, and desire to prevent or delay knee osteoarthritis. In athletes with anatomically repairable tears, meniscus repair should be performed given the ability to restore native anatomy, provide high rates of RTS, and mitigate long-term chondral damage. However, partial meniscectomy can be indicated for unrepairable tears.

Editorial Commentary: Various Meniscal Repair Techniques Show Similar Biomechanical and Clinical Outcomes, and Horizontal Suture Orientation Is Best Avoided

Knee meniscal repair shows favorable outcomes, especially if associated with anterior cruciate ligament reconstruction. However, a favorable clinical outcome does not mean that the meniscus has healed. There is no difference in clinical outcomes between all-inside and inside-out meniscal repair techniques. The all-inside technique is faster and associated with a lower incidence of neurovascular injuries. In terms of biomechanical studies, protocols vary, and no meniscal repair technique (all-inside, inside-out, or outside-in) is clearly superior to any other technique regarding tensile load, tissue failure rate, or restoration of contact mechanics. That said, a vertically oriented meniscal suture captures circumferential collagen bundles and is superior in strength to any horizontal meniscal stitch. A horizontal meniscal stitch orientation should be avoided.

Neither All-Inside, nor Inside-Out, nor Outside-In Repair Demonstrates Superior Biomechanical Properties for Vertical Meniscal Tears: A Systematic Review of Human Cadaveric Studies

PURPOSE

To systematically review the literature regarding the biomechanical properties of different repair techniques and fixation methods for vertically oriented meniscal tears.

METHODS

Human cadaveric studies evaluating the biomechanical properties of different repair techniques for vertically oriented meniscal tears were identified using the PubMed, EMBASE, and Cumulative Index to Nursing & Allied Health databases. Primary outcomes included load to failure, displacement, stiffness, peak contact pressure, and contact area of repaired menisci. Repair techniques from included studies were reclassified into a total of 19 distinct all-inside (AI), inside-out (IO), or outside-in (OI) techniques.

RESULTS

Sixteen studies were included (420 total menisci). Contact pressure and area were restored to intact-state values across all 5 compressive load studies at low knee flexion angles but not at greater knee flexion angles (i.e., >60°). There were no significant differences in contact pressure or area between AI, IO, and OI techniques across all studies. Some studies demonstrated statistically significant advantages in tensile properties with IO techniques when compared with AI techniques, whereas others found AI techniques to be superior. No studies directly compared tensile properties of OI techniques with those of AI or IO techniques. Vertical mattress suture configurations resulted in significantly greater load to failure and decreased displacement compared with horizontal mattress configurations in 67% of studies comparing the 2 techniques. There was no difference in the rate of tissue failure in AI (66.97%), IO (60.38%), or OI (66.67%, χ2 = 0.83, P = .66) techniques.

CONCLUSIONS

Contact mechanics are reliably restored after repair of vertical meniscal tears at low flexion angles but inconsistently restored at greater flexion angles, regardless of technique. Vertical mattress configurations outperformed horizontal mattress configurations under tensile load. There are conflicting data regarding the comparison of tensile properties between AI and IO techniques. Ultimately, neither AI, IO, nor OI repair demonstrated superior biomechanical properties in the present literature.

CLINICAL RELEVANCE

Several repair techniques demonstrate favorable biomechanical properties for vertical meniscal tears under tensile and compressive loads. Neither AI, IO, nor OI repair techniques demonstrate superior biomechanical properties at this time.

Biomechanical Characteristics of All-Suture Meniscal Repair Devices Compared With PEEK-Anchored Devices and Inside-Out Suture for Meniscal Repair: A Porcine Study

Background

Recently, all-suture, all-inside meniscal repair devices-including devices containing flat sutures or tapes-have been introduced. Similar to those in suture anchors, these modifications may have different performance characteristics than conventional sutures and polyether ether ketone (PEEK)-anchored devices.

Purpose

To compare the biomechanical characteristics of all-suture meniscal repair devices with those of a conventional PEEK-anchored device and an inside-out meniscal suture construct.

Study Design

Controlled laboratory study.

Methods

A total of 48 adult porcine menisci with simulated bucket-handle tears were included. Single-device repairs were performed with the SuperBall Meniscal Repair System, FiberStitch, and FAST-FIX 360 with 2 PEEK anchors, and a vertical mattress inside-out suture repair was performed using a Ti-Cron No. 2-0 braided polyethylene terephthalate suture. All specimens were preloaded (10 N) and cycled 200 times (between 10 and 50 N). Specimens surviving cyclic loading were then destructively tested. Endpoints included maximum failure load, stiffness, cyclic displacement, and failure mode. The goal was 12 successful tests in each group. Metrics between groups were compared using analysis of variance with post hoc tests to control for multiple comparisons.

Results

The SuperBall (108.9 N) was significantly stronger than the FAST-FIX 360 (67.3 N) and Ti-Cron (75.2 N), and the FiberStitch (102.8 N) was significantly stronger than the FAST-FIX 360 (P≤ .01 for all). Cyclic stiffness increased during cyclic loading for all constructs (P < .001). The Ti-Cron was significantly stiffer than the SuperBall during 5 to 200 cycles (P < .001). Cyclic displacement significantly increased in all constructs during cycling (P < .001) but did not differ between devices. Failure mode varied by device: the Ti-Cron repairs failed because of suture breakage, the SuperBall and FAST-FIX 360 failed at the anchor, and the FiberStitch showed both failure modes.

Conclusion

The all-suture, all-inside meniscal repair devices demonstrated superior strength to the PEEK-anchored device and the classic inside-out suture meniscal repair but no statistically significant difference in cyclic displacement.

More Is Not Merrier: Increasing Numbers of All-Inside Implants Do Not Correlate with Higher Odds of Revision Surgery

The purpose of this study was to evaluate the relationship between the number of all-inside meniscal repair implants placed and the risk of repair failure. We hypothesized that the use of higher numbers of all-inside meniscus repair implants would be associated with increased failure risk. A retrospective chart review identified 351 patients who underwent all-inside meniscus repair between 2006 and 2013 by a sports medicine fellowship-trained orthopaedic surgeon at a single institution. Patient demographics (age, body mass index [BMI], sex) and surgical data (number of implants used, concomitant anterior cruciate ligament reconstruction [cACLR], and tear type/size/location) were recorded. Patients who received repairs in both menisci or who had follow-up < 1-year postoperatively were excluded. Repair failure was identified through chart review or patient interviews defined as a revision surgery on the index knee such as partial meniscectomy, total knee arthroplasty, meniscus transplant, or repeat repair. Logistic regression modeling was utilized to evaluate the relationship between the number of implants used and repair failure. A total of 227 all-inside meniscus repairs were included with a mean follow-up of 5.0 ± 3.0 years following surgery. Repair failure was noted in 68 knees (30.3%)-in 28.1% of knees with fewer than four implants and in 35.8% of knees with four or more implants (p = 0.31). No significant increase in failure was observed with increasing number of all-inside medial (odds ratio [OR]: 1.15; 95% confidence interval [CI]: 0.79-1.7; p = 0.46) or lateral (OR: 0.86; 95% CI: 0.47-1.57; p = 0.63) implants after controlling for patient age, BMI, cACLR, tear type, or size. Tears of the lateral meniscus located in the red-white and white-white zones had lower odds of failure (OR: 0.14; 95% CI: 0.02-0.88; p = 0.036) than tears within the red-red zone, and patients with cACLR had lower odds of repair failure (OR: 0.40; 95% CI: 0.18-0.86, p = 0.024) than those without. The number of all-inside implants placed during meniscus tear repair did not affect the likelihood of repair failure leading to reoperation after controlling for BMI, age, tear type, size, location, and cACLR. LEVEL OF EVIDENCE:  III.

Biomechanical Comparison of All-Suture, All-Inside Meniscus Repair Devices in a Human Cadaveric Meniscus Model

OBJECTIVE

Newer all-suture, all-inside meniscus repair devices utilize soft suture anchors. The purpose of this study was to compare the biomechanical performance of 4 meniscus repair devices in human cadaver menisci: the JuggerStitch (all-suture, all-inside), the FiberStitch (all-suture, all-inside), a polyether ether ketone (PEEK) all-inside, and an inside-out device.

DESIGN

Forty human cadaver menisci were tested after creating 20 mm longitudinal tears in the posterior meniscus. Each knee was randomized to 1 of 4 meniscus repair groups: JuggerStitch (all-suture, all-inside), FiberStitch (all-suture, all-inside), FAST-FIX 360 (PEEK-based anchor all-inside), and inside-out (with BroadbandTM tape meniscus needles). For each meniscus, 2 devices were used to prepare vertical mattress repair construct. The specimens were tested by pre-conditioning 20 cycles between 5 N and 30 N and then the tear diastasis was measured, followed by distraction to failure phase after imposing a displacement at a rate of 0.5 mm/s.

RESULTS

Ten menisci were tested in each of the 4 groups. After pre-conditioning, there was no significant difference in the gap formation among groups (P = 0.212). The average failure load for the JuggerStitch, FiberStitch, PEEK all-inside, and inside-out was 384 N, 311 N, 207 N, and 261 N, respectively, with a significant difference between groups (P = 0.034). Post hoc analysis showed the JuggerStitch failure load was higher than the PEEK all-inside and inside-out (P = 0.005, and P = 0.045, respectively). There was no significant difference between the failure load of the JuggerStitch and FiberStitch (P = 0.225).

CONCLUSION

The JuggerStitch all-suture device, FiberStitch all-suture device, PEEK all-inside, and inside-out devices have similar biomechanical properties for gapping and stiffness. The JuggerStitch all-suture, all-inside device has superior failure load compared with the PEEK all-inside and inside-out repair for longitudinal meniscus tear repair.

What Do Patients Encounter When Searching Online About Meniscal Surgery? An Analysis of Internet Trends

Background

Many patients use the internet to learn about their orthopaedic conditions and find answers to their common questions. However, the sources and quality of information available to patients regarding meniscal surgery have not been fully evaluated.

Purpose

To determine the most frequently searched questions associated with meniscal surgery based on question type and topic, as well as to assess the website source type and quality.

Study Design

Cross-sectional study.

Methods

The following search terms were entered into a web search (www.google.com) using a clean-install browser: "meniscal tear,""meniscus repair,""meniscectomy,""knee scope,""meniscus surgery," and "knee arthroscopy." The Rothwell classification system was used to categorize questions and sort them into 1 of 13 topics relevant to meniscal surgery. Websites were also categorized by source into groups. The Journal of the American Medical Association (JAMA) benchmark criteria (medians and interquartile ranges [IQRs]) were used to measure website quality.

Results

A total of 337 unique questions associated with 234 websites were extracted and categorized. The most popular questions were "What is the fastest way to recover from meniscus surgery?" and "What happens if a meniscus tear is left untreated?" Academic websites were associated more commonly with diagnosis questions (41.9%, P < .01). Commercial websites were associated more commonly with cost (71.4%, P = .03) and management (47.6%, P = .02). Government websites addressed a higher proportion of questions regarding timeline of recovery (22.2%, P < .01). Websites associated with medical practices were associated more commonly with risks/complications (43.8%, P = .01) while websites associated with single surgeons were associated more commonly with pain (19.4%, P = .03). Commercial and academic websites had the highest median JAMA benchmark scores (4 [IQR, 3-4] and 3 [IQR, 2-4], respectively) while websites associated with a single surgeon or categorized as "other" had the lowest scores (1 [IQR 1-2] and 1 [IQR 1-1.5], respectively).

Conclusion

Our study found that the most common questions regarding meniscal surgery were associated with diagnosis of meniscal injury, followed by activities and restrictions after meniscal surgery. Academic websites were associated significantly with diagnosis questions. The highest quality websites were commercial and academic websites.

Surgical Management of Traumatic Meniscus Injuries

The menisci increase the contact area of load bearing in the knee and thus disperse the mechanical stress via their circumferential tensile fibers. Traumatic meniscus injuries cause mechanical symptoms in the knee, and are more prevalent amongst younger, more active patients, compared to degenerative tears amongst the elderly population. Traumatic meniscus tears typically result from the load-and-shear mechanism in the knee joint. The treatment depends on the size, location, and pattern of the tear. For non-repairable tears, partial or total meniscal resection decreases its tensile stress and increases joint contact stress, thus potentiating the risk of arthritis. A longitudinal vertical tear pattern at the peripheral third red-red zone leads to higher healing potential after repair. The postoperative rehabilitation protocols after repair range from immediate weight-bearing with no range of motion restrictions to non-weight bearing and delayed mobilization for weeks. Pediatric and adolescent patients may require special considerations due to their activity levels, or distinct pathologies such as a discoid meniscus. Further biomechanical and biologic evidence is needed to guide surgical management, postoperative rehabilitation protocols, and future technology applications for traumatic meniscus injuries.

Meniscectomy is associated with a higher rate of osteoarthritis compared to meniscal repair following acute tears: a meta-analysis

PURPOSE

Meniscal tears are common and may impair knee function and biomechanics. This meta-analysis compared meniscal repair versus resection in patients with symptomatic meniscal tears in terms of patient-reported outcomes measures (PROMs), joint width, surgical failure, and rate of progression to osteoarthritis (OA) at conventional radiography.

METHODS

This study was conducted according to the 2020 PRISMA statement. In August 2023, the following databases were accessed: PubMed, Web of Science, Google Scholar, and Embase. Two reviewers independently performed the analysis and a methodological quality assessment of the included studies. All the clinical investigations which compared repair versus resection of meniscal tears were accessed.

RESULTS

Data from 20 studies (31,783 patients) were collected. The mean BMI was 28.28 ± 3.2 kg/m2, and the mean age was 37.6 ± 14.0 years. The mean time elapsed from injury to surgery was 12.1 ± 10.2 months and the mean medial joint width was 4.9 ± 0.8 mm. Between studies comparability at baseline was found in age, women, BMI, time from injury to surgery and length of the follow-up, PROMs, medial joint width, and stage of OA. The resection group demonstrated a greater Lysholm score (P = 0.02). No difference was found in the International Knee Documentation Committee (P = 0.2). Nine studies reported data on the rate of failures at a mean of 63.00 ± 24.7 months. No difference was found between the two groups in terms of persistent meniscal symptoms (P = 0.8). Six studies reported data on the rate of progression to total knee arthroplasty at a mean of 48.0 ± 14.7 months follow-up. The repair group evidenced a lower rate of progression to knee arthroplasty (P = 0.0001). Six studies reported data on the rate of advanced knee OA at a mean of 48.0 ± 14.7 months of follow-up. The repair group evidenced a lower rate of advanced knee OA (P = 0.0001). No difference was found in the mean joint space width (P = 0.09).

CONCLUSION

Meniscal repair is associated with a lower progression to knee osteoarthritis at approximately six years of follow-up compared to partial meniscectomy. No difference in PROMs, medial joint width, and failures were evidenced.

LEVEL OF EVIDENCE

Level III, meta-analysis.

Failure rate, return-to-sports and magnetic resonance imaging after meniscal repair: 119 patients with 7 years mean follow up

BACKGROUND

One of the most important factors to consider in relation to meniscal repair is the high failure rate reported in the existing literature.

AIM

To evaluate failure rates, return to sports (RTS) rate, clinical outcomes and magnetic resonance image (MRI) evaluation after meniscus suture repair for longitudinal tears at a minimum 2-year-follow-up.

METHODS

We conducted a retrospective review of meniscal repairs between January 2004 and December 2018. All patients treated for longitudinal tears associated or not with an anterior cruciate ligament reconstruction (ACL-R) were included. Meniscal ramp lesions, radial and root tears, associated with multiligament injuries, tibial fracture and meniscal allograft transplants were excluded. Surgical details and failure rate, defined as symptomatic patients who underwent a revision surgery, were analyzed. As isolated bucket handle tears (BHTs) were usually associated with higher failure rates, we compared BHTs and not BHTs associated or not with an ACL-R. Since 2014, the inside-out technique using cannulas and suture needles with 2-0 Tycron began to predominate. In addition, the number of stitches per repair was increased. In view of differences in surgical technique, we compared two different cohorts: before and after 2014. We recorded the RTS according to the level achieved and the time to RTS. Lysholm and IKDC scores were recorded. Patients were studied with x-rays and MRI as standard postoperative control.

RESULTS

One hundred and nineteen patients were included with a mean follow up of 7 years (SD: 4.08). Overall failure rate was 20.3% at a mean 20.1 mo. No statistically significant differences were found when comparing failure for medial and lateral meniscal repair (22.7% and 15.3%, P = 0.36), BHTs and not BHTs (26% and 17.6%, P = 0.27), isolated or associated with an ACL-R (22.9% and 18%, P = 0.47), or when comparing only BHTs associated with an ACL-R (23% and 27.7%, P = 0.9) or not. When comparing cohorts before and after 2014, we found a significant decrease in the overall failure rate from 26% to 11% (P < 0.03). Isolated lesions presented a decrease from 28% to 6.6% (P = 0.02), BHTs from 34% to 8% (P = 0.09) and those associated with an ACL-R from 25% to 10% (P = 0.09). Mean RTS time was 6.5 mo in isolated lesions and 8.64 mo when associated with an ACL-R. Overall, 56% of patients returned to the same sport activity level. Mean pre and postoperative Lysholm scores were 64 and 85 (P = 0.02), and IKDC 58 and 70 (P = 0.03). Out of 84 asymptomatic patients evaluated with MRI, 39% were classified as "not healed" and 61% as "healed".

CONCLUSION

Even though the overall failure rate of our series was 20.3%, we found a statistically significant decrease from 26% to 11%, not only for isolated lesions, but also for BHT's and those associated with an ACL-R when comparing our series in two different cohorts, most probably due to improvements in surgical technique.

Horizontal Cleavage Meniscus Tears: Biomechanics, Indications, Techniques, and Outcomes

» Accounting for up to 24% of all meniscus tears, horizontal cleavage tears (HCTs) are a common pathology orthopaedic practitioners should be comfortable managing.» Historically, HCTs were treated with partial meniscectomy; however, recent studies have demonstrated that these procedures have an adverse biomechanical effect, while HCT repairs restore the knee's natural biomechanics.» Indications for the surgical repair of HCTs remain disputed, but surgery is generally considered for young, active patients and older patients without significant concomitant osteoarthritis.» Early clinical findings surrounding HCT repair are promising. They suggest that this treatment adequately restores meniscus mechanics, leads to good knee functional outcomes, and results in a high likelihood of return to preinjury activity levels.

Using a Combined All-Inside, Inside-Out, and Outside-In Technique to Repair Bucket-Handle Medial Meniscal Tears Without a Safety Incision

We describe a combined all-inside, inside-out, and outside-in technique for the repair of unstable bucket-handle medial meniscal tears. Notably, a greater incidence of neurovascular complications has been associated with meniscal repair techniques that employ an accessory skin incision, especially when damage involves the body of the medial meniscus. However, with the operative knee in relative extension, passing inside-out needles anteromedial to the posterior horn and posterior to the semitendinosus tendon and saphenous nerve allows for the needles to exit the posteromedial knee through a "safe zone." Therefore, we reduce iatrogenic damage by avoiding the necessity of a large safety incision while still maintaining suture placement versatility and meniscal fragment stabilization. Thus, the objective of this Technical Note is to outline an efficient technique for treating bucket-handle medial meniscal tears that yields a strong, durable repair while avoiding damage to adjacent neurovascular structures and eliminating the need for a posteromedial safety incision.

Sustained-Drug-Release, Strong, and Anti-Swelling Water-Lipid Biphasic Hydrogels Prepared via Digital Light Processing 3D Printing for Protection against Osteoarthritis: Demonstration in a Porcine Model

Osteoarthritis is a serious disease affecting joint cartilage. Owing to poor blood supply, the meniscus and acetabular labrum of joints heal poorly after injury. However, the development of artificial alternatives to these components that have similar mechanical properties and cartilage-protection ability is challenging. In this study, a strong hydrogel with a biomimetic microstructure is prepared with an emulsion-type photosensitive resin, where both hydrophilic and hydrophobic monomers, photo-initiator, and drugs can be adopted. In this system, the hydrophobic monomer forms uniformly dispersed aggregates after curing, improving the mechanical properties of the hydrogel significantly. Furthermore, the coordination bonds between nontoxic Zr4+ cations and sulfonic acid groups prevent hydrogel swelling. In addition, the water-oil biphasic hydrogel ink enables the loading of water- and lipid-soluble drugs, yielding hydrogel scaffolds with sustained dual-drug release ability. Crucially, hydrogel scaffolds having excellent mechanical properties, low swelling, and sustained biphasic drug release ability can be prepared using digital light processing 3D printing technology, owing to the high curing rate of the hydrophobic photo-initiator. These hydrogel scaffolds are applied as meniscal and labral replacements in a porcine model and show great promise for the prevention of secondary osteoarthritis, demonstrating the broad potential clinical applications of this material.

Arthroscopic Meniscus Repair Using an All-Inside, All-Suture, Knotless Device

With an increased appreciation of the importance an intact meniscus has on normal knee kinematics and function, more meniscal tears are being treated with a repair rather than partial meniscectomy. There are several techniques for repairing torn meniscal tissue, including the outside-in, inside-out, and all-inside repairs. Each technique comes with its advantages and drawbacks. The inside-out and outside-in techniques allow for greater control of the repair using knots outside the joint capsule; however, they pose a risk for neurovascular injury and require additional incisions. Arthroscopic all-inside repairs have seen increasing popularity, but with current techniques, fixation is achieved either with intra-articular knots or extra-articular implants, leading to variable outcomes and the potential for postoperative complications. This technical note describes the use of SuperBall, an all-inside meniscus repair device that provides an all-arthroscopic approach, no intraarticular knots or implants, and surgeon-guided tensioning of the meniscus repair.

A Comparison of All-inside and Inside-out Meniscal Repair in Elite Athletes

BACKGROUND

The popularization of all-inside (AI) meniscal repair devices has led to a shift away from the historical gold standard of inside-out (IO) meniscal repair without comparative studies to support the change.

PURPOSE

To compare the failure rate and time to failure of AI and IO meniscal repair performed in elite athletes.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A retrospective review was performed of all professional and national- and international-level amateur athletes who underwent meniscal repair, with a minimum of 2-year follow-up between January 2013 and September 2019. Meniscal repair was classified as AI or IO depending on the surgical technique performed. Treatment failure was defined as patients having to undergo subsequent surgery to address a persistent meniscal tear after repair. Cox proportional hazards modeling was used to determine if meniscal repair failure rates differed by the location and technique of meniscal repair. Models were controlled for known risk factors such as age, sex, sport, and concurrent cruciate ligament reconstruction.

RESULTS

A total of 192 (135 lateral and 57 medial) meniscal repairs were performed in elite athletes during the study period. Overall, 41 (21%) meniscal repairs met the criteria for failure. Medial meniscal tears repaired with the AI technique failed at a significantly higher rate (18/31 [58%]) than medial meniscal tears repaired with the IO technique (6/26 [23%]) or lateral meniscal tears repaired with the AI (9/76 [12%]) or IO (8/59 [14%]) technique (P < .001). Cox proportional hazards modeling revealed that a medial meniscal tear repaired with the AI technique had an almost 8 times greater hazard of failure than a lateral meniscal tear repaired with the AI technique (P < .001). At 1 year postoperatively, 8% of lateral meniscal repairs had failed (regardless of technique), while medial meniscal tears failed at a rate of 16% with the IO technique and 42% with the AI technique. By 2 years, 53% of medial meniscal tears repaired with the AI technique had failed, and by 5 years, 63% had failed.

CONCLUSION

AI repair of medial meniscal tears led to a higher rate of failure than IO repair of medial or lateral meniscal tears in elite athletes. Medial meniscal repair failed at a higher rate than lateral meniscal repair.

Failure Rates of Repaired Bucket-Handle Tears of the Medial Meniscus Concomitant With Anterior Cruciate Ligament Reconstruction: A Cohort Study of 253 Patients From the SANTI Study Group With a Mean Follow-up of 94 Months

BACKGROUND

Failure rates of repaired bucket-handle medial meniscal tears (BHMMTs) concomitant with anterior cruciate ligament reconstruction (ACLR) are as high as 20%. The outcomes of posteromedial portal suture hook repair have not been compared with all-inside repair techniques for this subtype of meniscal lesion.

PURPOSE/HYPOTHESIS

The aim of this study was to evaluate the outcomes and failure rates of patients who underwent BHMMT repair concomitant with ACLR using an all-inside technique, suture hook + all-inside technique, or suture hook + outside-in technique. It was hypothesized that no significant differences in failure rates would be found between the groups.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A retrospective analysis was performed on patients diagnosed with a BHMMT who underwent meniscal repair during primary ACLR and had a minimum follow-up of 2 years. Patients were grouped based on the meniscal repair technique used: all-inside repair, suture hook + all-inside repair, or suture hook + outside-in repair. At the end of the study period, secondary medial meniscectomy rates were determined.

RESULTS

The study population comprised 253 patients who underwent repair of a BHMMT with concomitant ACLR with a mean follow-up of 94.0 ± 47.6 months. A total of 114 patients (45.1%) underwent all-inside repair, 61 patients (24.1%) underwent suture hook + all-inside repair, and 78 patients (30.8%) underwent suture hook + outside-in repair. Overall, there were 36 failures. The failure rates were 20.2%, 14.8%, and 5.1%, respectively (P = .0135). All-inside repairs were >4 times more likely to fail than suture hook + outside-in repairs (hazard ratio [HR], 4.103; 95% CI, 1.369-12.296; P = .0117). Failure was also 3 times higher (HR, 2.943; 95% CI, 1.224-7.075; P = .0159) for patients <30 years of age compared with those aged ≥30 years. An additional anterolateral ligament reconstruction (ALLR) was also found to reduce the failure rate of repaired BHMMTs concomitant with ACLR.

CONCLUSION

Combined suture hook + outside-in repair of BHMMTs resulted in significantly fewer failures than all other techniques. Furthermore, age <30 years and no additional ALLR were associated with higher failure rates.

Smaller Iatrogenic Defects Created by Inside-Out Compared With All-Inside Meniscus Repair Devices in Human Cadaveric Model

PURPOSE

(1) To investigate the pattern and diameter of the iatrogenic defect that meniscal repair devices impose on meniscal tissue and (2) to determine whether repair-induced defect patterns or diameters differ across devices.

METHODS

Sixty-one fresh frozen human cadaveric menisci were used (n = 9; eliminated). All-inside devices (n = 9) included ULTRA FAST-FIX, FAST-FIX 360, Depuy Mitek 0° and 12° TRUESPAN, ConMed Sequent, Zimmer Biomet JuggerStitch, Stryker IvyAIR, Arthrex FiberStitch and Meniscal Cinch II. Inside-out needles (n = 4) included ConMed HiFi, Depuy Mitek ORTHOCORD, Arthrex-2-0 FiberWire, and Stryker SharpShooter. Following India Ink staining, implant devices were inserted into cadaveric menisci. Samples were fixed in formalin solution and imaged with a high-resolution camera. Defects were classified by qualitative evaluation. Defect and needle diameter were quantified with software assistance. Statistical analysis was performed using analysis of variance testing.

RESULTS

We analyzed 644 iatrogenic defects with mean defect diameter of 1.96 mm (standard deviation 0.86). For all-inside devices, defect patterns (n = 436) were 15.6% linear, 38.1% semilunar, 46.3% stellate, while inside-out devices (n = 208) were 95.7% stellate, 4.3% linear, and 0.0% semilunar. All-inside devices had mean defect diameter of 2.46 mm, while inside-out meniscus needles had mean 0.90 mm defect diameter (P < .001). FasT-FIX 360, ULTRA-FAST-FIX, and Arthrex Meniscal Cinch II induced smaller diameter defects than other all-inside devices (F = 20.2, P < .05). Strong positive correlation was found comparing outer needle diameter and mean defect diameters across all devices (R² = 0.9447).

CONCLUSIONS

Needles utilized in meniscal implant systems produce the following basic defect patterns: stellate (62.3%), semilunar (25.8%), and linear (11.9%). A strong positive correlation was found between mean defect size and outer needle diameter across all devices. Inside-out double-armed flexible needles produced significantly smaller defects than all-inside devices. Of the all-inside devices, ULTRA FAST-FIX, FAST-FIX 360, and Arthrex Meniscal Cinch II produced smaller defects on average.

CLINICAL RELEVANCE

While the true clinical impact of these findings cannot be drawn from the present study, this investigation provides necessary context to better understand reported similarities and differences in healing rates and outcomes between inside-out and all-inside repair techniques.

All-Inside Meniscal Repair: A Historical View

Background:

All-inside meniscal repair first became popularized in the early 2000s. Since that time, there has been a wide variety of all-inside implants on the market with rapid changes and developments in recent years.

Indications:

Small, peripheral, longitudinal tears are best suited for all-inside repair, but this technique may even be used for large bucket handle tears especially when hybridized with an inside-out repair.

Technique Description:

A percutaneous release of the medial collateral ligament (MCL) with an 18-g spinal needle is frequently performed when working in the medial compartment to improve visualization and decrease risk of iatrogenic chondral injury. Close familiarity with the characteristics of the chosen all-inside device including device angle, modifiability of device angle, modifiability of needle depth, deployment method, and tensioning technique is important for obtaining reproducible results. Typically, obtaining a vertical mattress stitch configuration is optimal as it captures more circumferential collagen fibers in the repair.

Results:

Factors to consider when selecting an all-inside meniscal repair device include the ergonomics of the device, implant cost, availability, rigid versus suture-based anchor, core needle diameter, device flexibility, and percent of misfires.

Discussion:

Complications from use of all-inside meniscus repair devices include device failure, soft tissue entrapment, cyst formation, and injury to the popliteal artery. Outcomes, however, with current devices are good and comparable to inside-out meniscus repair with about a 90% return to sports rate at 12 months postoperatively. The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Comparison of Cases with Anterior Cruciate Ligament Reconstruction Accompanied by Simultaneous Medial Meniscus Bucket Handle Tear Repair and Isolated Medial Meniscus Bucket Handle Tear Repair

The aim of this study was to evaluate the success of the all-inside repair technique for medial bucket-handle meniscus tear (BHMT) and the factors affecting healing. A total of 36 patients with BHMT who were operated between 2012 and 2018 and completed final follow-up examinations were included in the study. Functional evaluation was made with the International Knee Documentation Committee (IKDC) score, Lysholm score, and Tegner score. Healing was evaluated on magnetic resonance imaging (MRI) slices. The patients were evaluated with respect to the effect on healing of factors such as demographic data, body mass index (BMI), smoking status, anterior cruciate ligament tear reconstruction (ACLTR) applied at the same time as BHMT repair, and the tear being chronic or acute. The mean age of the patients was 28.6 ± 8.6 years (range,18-46 years), the mean follow-up period was 25.8 ± 13.9 months (range, 13-59 months), and BMI was mean 25.6 ± 3.5 kg/m² (range, 20.1-30.5 kg/m²). The meniscus tears were acute in 16 (44.4%) patients and chronic in 20 (55.6%). ACLTR was applied together with BHMT repair in 25 patients. The hybrid technique, as the outside-in technique in addition to the all-inside technique, was applied to 12 (33.3%) patients, where there was seen to be extension to the anterior horn. The failure rate was determined as 27.8% according to the postoperative MRI evaluation and the Barrett criteria. No positive or negative statistically significant effect on healing was determined of chronic BHMT or of simultaneous application of ACLTR (p = 1.00 and 0.457, respectively). Cigarette smoking and high BMI were determined to have a statistically significant negative effect on healing (p = 0.026 and 0.007, respectively). In conclusion, it can be seen that the success of the all-inside technique for BHMT remains controversial. Due to the features of the application, it can be used in meniscus tears of the posterior horn only. In the current study, with the success rate of 72.2% of the all-inside technique in meniscus body tears, it was seen that a high success rate could not be achieved.

Primary Fixation and Cyclic Performance of Single-Stitch All-Inside and Inside-Out Meniscal Devices for Repairing Vertical Longitudinal Meniscal Tears

BACKGROUND

Primary device fixation and the resistance against gap formation during repetitive loading influence the quality of meniscal repair. There are limited biomechanical data comparing primary tensioning and cyclic behavior of all-inside versus inside-out repair.

HYPOTHESIS

All-inside devices provide higher initial load on the meniscal repair than inside-out fixation, and stiffer constructs show higher resistance against gap formation during cyclic loading.

STUDY DESIGN

Controlled laboratory study.

METHODS

In total, 60 longitudinal bucket-handle tears in human cadaveric menisci were created and repaired with a single stitch and randomly assigned to 4 all-inside groups (TrueSpan, FastFix 360, Stryker AIR, FiberStich) and 2 inside-out groups (suture repair [IO-S], suture tape [IO-ST]). Residual load after repair tensioning (50 N) and relief displacement were measured. Constructs underwent cyclic loading between 2 and 20 N over 500 cycles (0.75 Hz) with cyclic stiffness, gap formation, and final peak elongation measured. Ultimate load and stiffness were analyzed during pull to failure (3.15 mm/s).

RESULTS

All-inside repair demonstrated significantly higher primary fixation strength than inside-out repair. The significantly highest load (mean ± SD; 20.1 ± 0.9 N; P < .037) and relief displacement (-2.40 ± 0.32 mm; P < .03) were for the knotless soft anchoring FiberStich group. The lowest initial load (9.0 ± 1.5 N; P < .001) and relief displacement (-1.39 ± 0.26 mm; P < .045) were for the IO-S repair group. The final gap formation (500th cycle) of FiberStich (0.75 ± 0.37 mm; P < .02) was significantly smaller than others and that of the IO-S (1.47 ± 0.33 mm; P < .045) significantly larger. The construct stiffness of the FiberStich and IO-ST groups was significantly greater at the end of cyclic testing (16.7 ± 0.80 and 15.5 ± 1.42 N/mm; P < .042, respectively) and ultimate failure testing (23.4 ± 3.6 and 20.6 ± 2.3 N/mm; P < .005). The FastFix 360 (86.4 ± 4.8 N) and Stryker AIR (84.4 ± 4.6 N) groups failed at a significantly lower load than the IO-S group (P < .02) with loss of anchor support. The FiberStich (146.8 ± 23.4 N), TrueSpan (142.0 ± 17.8 N), and IO-ST (139.4 ± 7.3 N) groups failed at significantly higher loads (P < .02) due to suture tearing.

CONCLUSION

Overall, primary fixation strength of inside-out meniscal repair was significantly lower than all-inside repair in this cadaveric tissue model. Although absolute differences among groups were small, meniscal repairs with higher construct stiffness (IO-ST, FiberStich) demonstrated increased resistance against gap formation and failure load.

CLINICAL RELEVANCE

Knotless single-stitch all-inside meniscal repair with a soft anchor resulted in less gapping, but the overall clinical significance on healing rates remains unclear.

Pulsed Electromagnetic Field Enhances Healing of a Meniscal Tear and Mitigates Posttraumatic Osteoarthritis in a Rat Model

BACKGROUND

Meniscal tears in the avascular region are thought to rarely heal and are a considerable challenge to treat. Although the therapeutic effects of a pulsed electromagnetic field (PEMF) have been extensively studied in a variety of orthopaedic disorders, the effect of a PEMF on meniscal healing has not been reported.

HYPOTHESIS

PEMF treatment would promote meniscal healing and prevent osteoarthritis progression.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 72 twelve-week-old male Sprague-Dawley rats with full-thickness longitudinal medial meniscal tears in the avascular region were divided into 3 groups: control (G_con), treatment with a classic signal PEMF (G_classic), and treatment with a high-slew rate signal PEMF (G_HSR). Macroscopic observation and histological analysis of the meniscus and articular cartilage were performed to evaluate the meniscal healing and progression of osteoarthritis. The synovium was harvested for histological and immunofluorescent analysis to evaluate the intra-articular inflammation. Meniscal healing, articular cartilage degeneration, and synovitis were quantitatively evaluated according to their scoring systems.

RESULTS

Dramatic degenerative changes of the meniscus and articular cartilage were noticed during gross observation and histological evaluation in G_con at 8 weeks. However, the menisci in the 2 treatment groups were restored to normal morphology, with a smooth surface and shiny white color. Particularly, the HSR signal remarkably enhanced the fibrochondrogenesis and accelerated the remodeling process of the regenerated tissue. The meniscal healing scores of the PEMF treatment groups were significantly higher than those in G_con at 8 weeks. Specifically, the HSR signal showed a significantly higher meniscal repair score than did the classic signal at week 8 (P < .01). Additionally, the HSR signal significantly downregulated the secretion levels of interleukin 1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α) in the meniscus and synovium as compared with the control group. When compared with the 2 treatment groups, G_con had significantly higher degeneration scores (G_con vs G_classic, P < .0001; G_con vs G_HSR, P < .0001). The HSR signal also exhibited significantly lower synovitis scores compared with the other two groups (G_con vs G_classic, P < .0001; G_classic vs G_HSR, P = .0002).

CONCLUSION

A PEMF promoted the healing of meniscal tears in the avascular region and restored the injured meniscus to its structural integrity in a rat model. As compared with the classic signal, the HSR signal showed increased capability to promote fibrocartilaginous tissue formation and modulate the inflammatory environment, therefore protecting the knee joint from posttraumatic osteoarthritis development.

CLINICAL RELEVANCE

Adjuvant PEMF therapy may offer a new approach for the treatment of meniscal tears attributed to the enhanced meniscal repair and ameliorated osteoarthritis progression.

Meniscal Repair Outcomes at Greater Than 5 Years: A Systematic Review and Meta-Analysis

BACKGROUND

The utilization of meniscal repair techniques continues to evolve in an effort to maximize the rate of healing. Meniscal repair outcomes at a minimum of 5 years postoperatively appear to better represent the true failure rates. Thus, a systematic review and meta-analysis of the current literature was conducted to assess the rate of failure at a minimum of 5 years after meniscal repair.

METHODS

We performed a systematic review of studies reporting the outcomes of meniscal repair at a minimum of 5 years postoperatively. A standardized search and review strategy was utilized. Failure was defined as recurrent clinical symptoms or a meniscal reintervention to repair or resect the meniscus in any capacity, as defined by the study. When reported, outcomes were assessed relative to anterior cruciate ligament (ACL) status, sex, age, and postoperative rehabilitation protocol. Meta-analyses were performed with a random-effects model.

RESULTS

A total of 27 studies of 1,612 patients and 1,630 meniscal repairs were included in this review and meta-analysis. The pooled overall failure rate was 22.6%, while the failure rate of modern repairs (excluding early-generation all-inside devices) was 19.5%. Medial repairs were significantly more likely to fail compared with lateral repairs (23.9% versus 12.6%, p = 0.04). Failure rates were similar for inside-out (14.2%) and modern all-inside repairs (15.8%). Early-generation all-inside devices had a significantly higher failure rate (30.2%) compared with modern all-inside devices (15.8%, p = 0.01). There was no significant difference in meniscal failure rate between repairs with concomitant ACL reconstruction (21.2%) and repairs in ACL-intact knees (23.3%, p = 0.54).

CONCLUSIONS

Modern meniscal repair had an overall failure rate of 19.5% at a minimum of 5 years postoperatively. Modern all-inside techniques appear to have improved the success rate of meniscal repair compared with use of early-generation all-inside devices. Lateral repairs were significantly more likely to be successful compared with medial repairs, while no difference was seen between patients undergoing meniscal repair with and without concomitant ACL reconstruction.

LEVEL OF EVIDENCE

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

Meniscus Repair Part 2: Technical Aspects, Biologic Augmentation, Rehabilitation, and Outcomes

Multiple meniscal repair techniques exist, and successful healing and excellent patient outcomes have been reported with a variety of all-inside and open techniques. Increased awareness and recognition of root tears and meniscocapsular separations are topics of recent interest. The ideal treatment of these injuries remains uncertain, and definitive recommendations regarding their treatment are lacking. Postoperative protocols regarding weight bearing and range of motion are controversial and require future study. The role of biologics in the augmentation of meniscal repair remains unclear but promising. An evidence-based individualized approach for meniscal repair focusing on clinical outcomes and value is essential.

The lateral meniscal extrusion after repair with concomitant anterior cruciate ligament reconstruction at a mean follow-up of 3.5 years

BACKGROUND

A meniscal repair is often performed on radial/flap or longitudinal tears of the lateral meniscus (LM) combined with anterior cruciate ligament reconstruction (ACLR). However, it is unknown if meniscal extrusion changes over time after repair. This study evaluated whether meniscal extrusion of the LM is maintained after repair or progresses with time using magnetic resonance imaging (MRI).

METHODS

Among 574 patients who underwent primary anatomic ACLR, 123 patients followed up for more than 2 years were retrospectively analyzed. Forty patients with concomitant radial/flap tears of the LM (group R), 43 with longitudinal LM tears (group L), and 40 with intact LM (group C, matched-control group) were included. Clinical findings (pain, range of motion, swelling, and anterior laxity), lateral joint space on radiograph, and meniscal extrusion on MRI were assessed. Lateral/posterior meniscal extrusions were examined preoperatively, within 3 weeks after surgery, and at the final follow-up, and the absolute values and relative values (the preoperative values as baseline) were assessed respectively.

RESULTS

There were no significant differences in the clinical and roentgenographic findings among the groups. No difference was observed in the relative values within 3 weeks after surgery among three groups, although the absolute values were larger in the repaired groups than in group C. At the final follow-up, however, the lateral extrusion in group L had progressed significantly, compared with that in group C (P = 0.033), while no significant difference was detected in the lateral extrusion between groups R and C (P = 0.177). The posterior extrusion in groups R and L had progressed significantly compared with that in group C (P < 0.001).

CONCLUSIONS

LM extrusion could not be improved even immediately after meniscal repair, and it progressed laterally and posteriorly for more than 2 years after surgery.

Meniscus Repair Part 1: Biology, Function, Tear Morphology, and Special Considerations

Knowledge of anatomy and physiology of the meniscus is essential for appropriate treatment. The unique anatomy of the medial and lateral meniscus and blood supply play an important role in decision making. Controversy exists regarding the optimal treatment of meniscal tears including débridement, repair, root repair, and transplantation. The unique tear location and morphology thus plays an essential role in determination of appropriate treatment. Repair is generally advised in tear types with healing potential to preserve meniscal function and joint health.

All-Inside Meniscus Repair

PURPOSE OF REVIEW

The indications for partial meniscectomy are becoming increasingly limited, and recent evidence suggests that the meniscus should be preserved whenever possible. Because of its many proposed advantages, all-inside meniscus repairs are becoming increasingly common. This review discusses the indications, advantages, disadvantages, and biomechanical and clinical outcomes of all-inside meniscus repair.

RECENT FINDINGS

All-inside meniscus repair demonstrates equal functional outcomes, healing rates, and complications compared to inside-out repair of vertical longitudinal and bucket-handle tears with the advantages of decreased surgical time and faster post-operative recovery. In addition, return-to-sport and activity levels are high following all-inside repair regardless of whether concomitant anterior cruciate ligament reconstruction is performed. Biomechanical studies have demonstrated advantages of all-inside meniscal based repairs on radial and horizontal tears. All-inside meniscus repair compares favorably to inside-out repair of vertical longitudinal and bucket-handle tears and continues to increase in popularity. Both capsular based and meniscal based repairs can be used to repair a variety of tear patterns. While biomechanical results are encouraging, further research on the clinical outcomes of meniscal based repairs is needed to elucidate the role of these techniques in the future.

Performance and Return to Sport After Meniscal Repair in Professional Baseball Players

Background:

Meniscal repair is an effective treatment option for certain meniscal injuries to preserve meniscal function and limit the progression of knee osteoarthritis. Outcomes after meniscal repair in professional baseball players are not well documented.

Purposes/Hypothesis:

The purposes of this study were to determine performance and return to sport (RTS) in professional baseball players after meniscal repair and compare the results of medial versus lateral meniscal repair. It was hypothesized that there would be a high RTS rate, with no difference in the rate or timing of RTS between players who underwent medial versus lateral meniscal repair.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

All professional baseball players who underwent meniscal repair between 2010 and 2017 were identified using the Major League Baseball Health and Injury Tracking System database. Descriptive information and performance data (before and after injury) for each player were recorded. The rate and timing of RTS were then compared between players who underwent medial versus lateral meniscal repair.

Results:

Included were 31 patients (mean age, 24 ± 3 years). There were 6 players (19%) who had failed repair, underwent subsequent meniscectomy within 2 years of meniscal repair, and were thus excluded from the performance analysis. Of the remaining 31 players, 68% returned to the same or a higher level of play, and 6% of players returned to a lower level of play. Most repair procedures (60%) were performed using the all-inside technique, and 72% of players underwent lateral meniscal repair. The mean time missed was 187 ± 67 days, and the mean time to RTS at full competitive play was 209 ± 84 days. There were no significant differences in the rate or timing of RTS between players who underwent medial versus lateral meniscal repair (P ≥ .999 and P = .574, respectively). Pitchers saw a decrease in usage but no change in performance after meniscal repair. For batters, most metrics were unchanged, but there was a significant decrease in base stealing and on-base percentage after surgery.

Conclusion:

The RTS rate after meniscal repair in Major League Baseball players was 74% at a mean of 209 days; 19% of players had failed repair and underwent subsequent meniscectomy within 2 years of repair. No difference in the rate or timing of RTS was observed between players who underwent medial versus lateral meniscal repair.

Higher healing rate after meniscal repair with concomitant ACL reconstruction for tears located in vascular zone 1 compared to zone 2: a systematic review and meta-analysis

PURPOSE

The purpose of this study was to determine and compare the percentage of completely healed meniscal tears after arthroscopic repair combined with anterior cruciate ligament reconstruction (ACLR) for the different vascular zones of the meniscus.

METHODS

PubMed, Embase, Web of Science, Cochrane library and Emcare were searched on 19 May 2020 for articles reporting healing rates after arthroscopic meniscal repair with concomitant ACLR for the different meniscal vascular zones as assessed by second-look arthroscopy. Data on meniscal tears were extracted as located in zones 1, 2 or 3, according to the Cooper classification. Studies were graded in quality using a modified Newcastle-Ottawa Scale. Pooled analyses were performed utilizing a random-effects model. Meta-analyses were performed using R version 3.6.2 and SPSS statistical software version 25.0. The study was registered with PROSPERO (ID:CRD42020176175).

RESULTS

Ten observational cohort studies met the inclusion criteria, accounting for 758 meniscal tear repairs in total. The pooled overall proportion of healing was 78% (95% CI 72-84%). The mean weighted proportion of healing was 83% (95% CI 76-90%) for studies (n = 10) reporting zone 1 tears and 69% (95% CI 59-79%) for studies (n = 9) reporting zone 2 tears. No study reported healing rates for zone 3 tears. The pooled overall odds ratio was 2.5 (95% CI 1.00-6.02), indicating zone 1 tears as 2.5 times more likely to heal than zone 2 tears.

CONCLUSION

This study demonstrates that meniscal tears localized in vascular zone 1 were more likely to heal than those in zone 2.

LEVEL OF EVIDENCE

IV.

Sutura meniscal microinvasiva com agulha descartável

The first meniscal suture was performed in 1885 and took about a century to become popular. Currently, all-inside meniscal repair devices are widely used. However, this technique presents the disadvantage of being a method dependent on specific devices, presenting a higher cost than other techniques. This high cost limits the use of such a technique in many locations. The objective of the present technical note is to describe a microinvasive meniscal suture technique as a modification of the all-inside technique, using a disposable 40 × 12 mm procedure needle. The authors believe that the proposed modification to the technique can make it more popular, enabling the use of the microinvasive technique in places with limited resources.

What Is the Failure Rate After Arthroscopic Repair of Bucket-Handle Meniscal Tears? A Systematic Review and Meta-analysis

BACKGROUND

Meniscal repair has become the treatment of choice for meniscal tears, especially in the subset of bucket-handle meniscal tears (BHMTs). However, a comprehensive estimate of the corresponding failure rate is not available, thus maintaining doubts about the healing potential of these tears. Furthermore, a wide range of factors to predict high failure rates have been reported but with conflicting evidence.

PURPOSE

To determine the failure rate after arthroscopic repair of BHMTs as reported in the literature, compare this with the failure rate of simple meniscal tears extracted from the same studies, and analyze the influence of factors previously reported to be predictive of meniscal repair failure.

STUDY DESIGN

Systematic review and meta-analysis; Level of evidence, 4.

METHODS

A systematic search was conducted by 2 independent reviewers using principal bibliographic databases (PubMed, Scopus, Cochrane Library, and EMBASE). After a stepwise exclusion process, 38 articles met the inclusion criteria. Failure rate data were analyzed with a random-effects proportional meta-analysis (weighted for individual study size), and forest plots were constructed to determine any statistically significant differences between BHMTs versus simple tears (longitudinal, radial, or horizontal), medial versus lateral BHMTs, isolated procedures versus repairs with concomitant anterior cruciate ligament reconstruction, and tears in red-red versus red-white zones. Moreover, a meta-regression analysis was conducted to evaluate the effect of patient age and sex, suture technique (in-out or all-inside), time from injury to surgery, mean number of stitches, and length of follow-up on failure rates.

RESULTS

The pooled failure rate was 14.8% (95% CI, 11.3%-18.3%; I² = 77.2%). A total of 17 studies provided failure rates of both BHMT repairs (46/311 repairs) and simple tear repairs (54/546 repairs), demonstrating a significantly higher failure rate for BHMT repairs (risk ratio [RR] = 1.50; 95% CI, 1.05-2.15; I² = 0%; P = .03). Medial BHMT repairs (RR = 1.94; 95% CI, 1.25-3.01; I² = 0%; P = .003) and isolated repairs (RR = 1.77; 95% CI, 1.15-2.72; I² = 0%; P = .009) had statistically higher risk of failure, but no statistically significant difference was found between tears in red-red versus red-white zones. Among the other factors evaluated with meta-regression, only the mean number of stitches showed a statistically significant effect on failure rates.

CONCLUSION

Based on the currently available literature, this systematic review provides a reasonably comprehensive analysis of failure rate after arthroscopic BHMT repair; failure is estimated to occur in 14.8% of cases. Medial tears and isolated repairs were the 2 major predictors of failure.

Inside-Out Approach to Meniscus Repair: Still the Gold Standard?

PURPOSE OF REVIEW

The purpose of this review is to provide an up-to-date summary on the current literature and trends regarding use of the inside-out approach to meniscus repair. Additionally, the paper describes the authors preferred techniques for inside-out meniscus repair utilizing posteromedial and posterolateral exposures.

RECENT FINDINGS

There has been a substantial increase in recent publications regarding meniscus repair. However, comparisons regarding the optimal repair technique have not been conclusive. Despite the recent increase in use of all-inside devices, multiple investigations with short-to-mid-term follow-up have demonstrated similar rates of meniscus healing between inside-out and all-inside repair techniques. Similarly, current literature describes comparable failure rates of around 20%. There are variations in the profile of complications, with all-inside devices having more implant-related complications and inside-out techniques with higher neurovascular injuries. Inside-out meniscus repair is a versatile, cost-effective technique that remains the gold standard for management of most meniscus tear patterns. Through a thoughtful approach, efficient suture retrieval and repair can be performed while protecting critical neurovascular structures. All-inside meniscus repair devices have increased in popularity and surgeon access, but this technique is not without limitations and comparisons to inside-out meniscus repair demonstrates equivocal outcomes.

Outcomes and failure rates after revision meniscal repair: a systematic review and meta-analysis

PURPOSE

The purpose of this meta-analysis is to determine the outcomes and failure rates for revision meniscus repairs in patients with re-tears after primary repair failure.

METHODS

A literature search was conducted using PubMed and Embase with the terms "Meniscus," "Meniscal," "Revised," and "Revision." The search strategy was based on the PRISMA (Preferred Reporting Items for Systematic Meta-Analyses) protocol and included four articles (79 patients). The search criteria were limited to studies reporting outcomes and failure rates. The exclusion criteria included languages other than English, biomechanical studies, letters to editors, non-full text, review articles, meta-analysis, and case reports.

RESULTS

Four comparative studies with 79 patients (53 males, 26 females) with a mean age of 23.9 ± 6.4 years treated with a revision meniscus repair were included in the final analysis. Within this analysis, we found a failure rate of 25.3% (20 of 79 patients). Of these failed repairs, 30.95% (13 of 42) were of the medial meniscus, and 18.9% (7 of 37) were of the lateral meniscus. In the four articles, the postoperative Tegner sports activity score was found to be 6.1 ± 1.6 (range, 2 to 10). The post-operative Lysholm score was reported in three articles (45 patients). At a mean follow-up of 58.3 ± 23.9 months, the mean post-operative Lysholm score was 89.1 ± 7.6 (range, 38 to 100). The Coleman score for the included articles ranged between 52 and 59.

CONCLUSION

This analysis found that revision meniscus repairs in patients with re-tears after primary repair failure result in clinical outcomes similar to that of primary repairs.

Performance and Return to Sports After Meniscectomy in Professional Baseball Players

BACKGROUND

Meniscal injuries are common in athletes across many sports. How professional baseball players respond to partial meniscectomy is not well documented.

PURPOSE/HYPOTHESIS

The purpose was to determine the performance and return-to-sports (RTS) rate in professional baseball players after arthroscopic partial knee meniscectomy and compare the results of partial medial meniscectomy versus partial lateral meniscectomy. The hypothesis was that there would be a high RTS rate in professional baseball players after partial meniscectomy with no difference in the RTS rate or timing of RTS between players who underwent partial medial meniscectomy versus partial lateral meniscectomy.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

All professional baseball players who underwent arthroscopic partial meniscectomy between 2010 and 2017 were identified using the Major League Baseball Health and Injury Tracking System database. Demographic and performance data (before and after injury) for each player were recorded. The RTS rate and timing of RTS were then compared between players who underwent partial medial meniscectomy versus partial lateral meniscectomy.

RESULTS

A total of 168 knees (168 players) underwent arthroscopic partial meniscectomy (mean age, 25 ± 5 years; 46% medial meniscectomy, 45% lateral meniscectomy, and 9% both medial and lateral meniscectomy). The most common mechanism of injury was fielding in the infield on natural grass. Injuries were spread evenly across positions: 18% catchers, 24% infielders, 20% outfielders, and 38% pitchers. The overall RTS rate was 80% (76% returned to the same or a higher level, and 4% returned to a lower level). For performance, pitchers saw significant decreases in usage but significant improvements in performance using the advanced statistics of fielding independent pitching (P < .001) and wins above replacement (P = .011). Hitters saw significant decreases in usage but increases in efficiency as seen by improvements in wins above replacement (P = .003). Of the 79 athletes who returned during the same season, the median time to return to play was 42 days.

CONCLUSION

The RTS rate after meniscectomy in professional baseball players was 80%. Player efficiency improved after surgery in pitchers and position players. No difference in the RTS rate or timing of RTS existed between players who underwent partial medial meniscectomy versus partial lateral meniscectomy.

Failure and Complication Rates in Common Sports and Arthroscopic Procedures: Reality Check

Expectations following sports medicine and arthroscopic procedures have been elevated because of captivating modern-day media coverage of high-profile athletic injuries, surgery, and rapid return to sports. Unfortunately, this general perception may be misleading, and orthopedic sports medicine physicians must be aware of the harsh reality of the trials and tribulations associated with the subspecialty. The purpose of this review article is to provide an updated brief overview of the complications and failure rates associated with common arthroscopic procedures including rotator cuff repair, biceps tenodesis, Bankart procedure, Latarjet procedure, anterior cruciate ligament reconstruction, anterior cruciate ligament repair, meniscal repair, tibial tubercle osteotomy, and medial patellofemoral ligament reconstruction. Highlighting the complications is the first step toward early recognition, enhancing preventative measures, and successful management.

Survival and Risk Factor Analysis of Arthroscopic Ramp Lesion Repair During Anterior Cruciate Ligament Reconstruction

BACKGROUND

There is a lack of research on the management of ramp lesions associated with anterior cruciate ligament (ACL) injuries. Furthermore, there has been no report of the risk factors for failure of ramp lesion sutures, linked to either the technique used (all-inside suture implant vs suture hook through a posteromedial portal) or the type of lesion (location in the red zone or meniscocapsular junction, longitudinal extension, partial- or full-thickness tear).

PURPOSE

To evaluate the results of arthroscopic repair of ramp lesions and determine the risk factors associated with ramp lesion repair failure, with special focus on their subtype and the suture technique.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

All patients who underwent arthroscopic ramp lesion repair in association with ACL reconstruction between November 2015 and January 2018 were evaluated retrospectively. The following parameters were studied: demographics; clinical history; clinical findings including International Knee Documentation Committee score, complications, time from injury to surgery, side-to-side laxity, and pivot shift; and surgical findings including subtype, surgical management, and type and number of sutures. Failure of the ramp lesion repair was defined at secondary arthroscopy.

RESULTS

Among the 248 lesions analyzed, 18 (7.3%) failures were documented. The failures occurred in 21.1% of repairs managed with the all-inside device versus 4.3% of sutures managed with the suture hook (P = .003). Among the 6 factors included in the Cox model, the only one identified as a risk factor for failure was the type of repair (P = .003), with a risk for the all-inside device that was >5-fold higher than that for the suture hook repair (corresponding hazard ratio, 5.1 [95% CI, 1.8-14.5]). No other complications involving the surgical technique or device were registered.

CONCLUSION

An arthroscopic all-inside technique of meniscal repair of ramp lesions appeared to be safe and effective. It provided excellent healing of the repaired meniscus, with an overall failure rate of 7.3%. The type of suture was associated with failure of the ramp lesion repair, with a significantly higher risk with the all-inside device than with suture hook repair sutures.

Pneumatospinning Biomimetic Scaffolds for Meniscus Tissue Engineering

Nanofibrous scaffolds fabricated via electrospinning have been proposed for meniscus tissue regeneration. However, the electrospinning process is slow, and can only generate scaffolds of limited thickness with densely packed fibers, which limits cell distribution within the scaffold. In this study, we explored whether pneumatospinning could produce thicker collagen type I fibrous scaffolds with higher porosity, that can support cell infiltration and neo-fibrocartilage tissue formation for meniscus tissue engineering. We pneumatospun scaffolds with solutions of collagen type I with thicknesses of approximately 1 mm in 2 h. Scanning electron microscopy revealed a mix of fiber sizes with diameters ranging from 1 to 30 µm. The collagen scaffold porosity was approximately 48% with pores ranging from 7.4 to 100.7 µm. The elastic modulus of glutaraldehyde crosslinked collagen scaffolds was approximately 45 MPa, when dry, which reduced after hydration to 0.1 MPa. Mesenchymal stem cells obtained from the infrapatellar fat pad were seeded in the scaffold with high viability (>70%). Scaffolds seeded with adipose-derived stem cells and cultured for 3 weeks exhibited a fibrocartilage meniscus-like phenotype (expressing COL1A1, COL2A1 and COMP). Ex vivo implantation in healthy bovine and arthritic human meniscal explants resulted in the development of fibrocartilage-like neotissues that integrated with the host tissue with deposition of glycosaminoglycans and collagens type I and II. Our proof-of-concept study indicates that pneumatospinning is a promising approach to produce thicker biomimetic scaffolds more efficiently that electrospinning, and with a porosity that supports cell growth and neo-tissue formation using a clinically relevant cell source.

Biochemical Characteristics and Clinical Result of Bone Marrow-Derived Fibrin Clot for Repair of Isolated Meniscal Injury in the Avascular Zone

PURPOSE

To characterize bone marrow aspirate-derived fibrin clot (BMA clot) and evaluate the clinical result of meniscal repair with a BMA clot for isolated meniscal injury in the avascular zone.

METHODS

Blood counts of total leukocytes, platelets, and concentrations of basic fibroblast growth factor (bFGF), transforming growth factor β (TGF-β), and stromal cell-derived factor 1 (SDF-1) were analyzed with BMA, peripheral blood (PB), BMA clot, and PB clot from 5 patients treated for meniscal repair. In addition, a retrospective analysis of 30 patients with isolated avascular meniscal injuries who underwent repair with a BMA clot was performed to assess rate failure. Avascular meniscal injury was identified as horizontal tear, radial tear, and flap tear. Clinical failure was defined as the presence of 1 or more of Barrett's criteria. Anatomic failure was defined as the existence of equivalent signal intensity to intra-articular fluid along the repair area on follow-up magnetic resonance imaging (MRI). Patients' demographic and clinical data were compared between the overall failure group and the success group.

RESULTS

The bFGF, TGF-β, and SDF-1 levels of BMA clots were more highly concentrated compared with PB clots. The Lysholm scores and meniscal status evaluated by MRI were significantly improved from preoperatively to postoperatively (both P < .001). The Kellgren-Lawrence grading of knee radiographs did not significantly differ pre- and postoperatively (P = .140). Rates of clinical failure, anatomic failure, and retear were 10%, 6.7%, and 3.3%, respectively. The demographic characteristics and surgical and postoperative status did not significantly differ between the overall failure group and the success group.

CONCLUSIONS

BMA clots had increased levels of cytokines compared to PB clots. The retrospective analysis revealed that the rates of clinical failure and anatomic failure after meniscal repair with a BMA clot for isolated avascular meniscal injury were 10% and 6.7%, respectively.

LEVEL OF EVIDENCE

Level IV, case series.

Satisfactory patient-reported outcomes at 5 years following primary repair with suture tape augmentation for proximal anterior cruciate ligament tears

PURPOSE

An enhanced understanding of anterior cruciate ligament (ACL) healing and advancements in arthroscopic instrumentation has resulted in a renewed interest in ACL repair. Augmentation of a ligament repair with suture tape reinforces the ligament and acts as a secondary stabilizer. This study assesses the 5-year patient-reported outcomes of primary repair with suture tape augmentation for proximal ACL tears.

METHODS

Thirty-seven consecutive patients undergoing ACL repair with suture tape augmentation for an acute proximal rupture were prospectively followed up for a minimum of 5 years. Patients with midsubstance and distal ruptures, poor ACL tissue quality, retracted ACL remnants and multiligament injuries were excluded. Patient-reported outcome measures were collated using the Knee Injury and Osteoarthritis Outcomes Score (KOOS), Visual Analogue Pain Scale (VAS-pain), Veterans RAND 12-Item Health Survey (VR-12) and the Marx Activity Scale. Patients with a re-rupture were identified.

RESULTS

Three patients were lost to follow-up leaving 34 patients in the final analysis (91.9%). The mean KOOS at 5 years was 88.5 (SD 13.8) which improved significantly from 48.7 (SD 18.3) preoperatively (p < 0.01). The VAS score improved from 2.3 (SD 1.7) to 1.0 (SD 1.5) and the VR-12 score improved from 35.9 (SD 10.3) to 52.4 (SD 5.9) at 5 years (p < 0.01). However, the Marx activity scale decreased from 12.4 (SD 3.4) pre-injury to 7.3 (SD 5.2) at 5 years (p = 0.02). Six patients had a re-rupture (17.6%) and have since undergone a conventional ACL reconstruction for their revision surgery with no issues since then. These patients were found to be younger and have higher initial Marx activity scores than the rest of the cohort (p < 0.05).

CONCLUSION

Primary repair with suture tape augmentation for proximal ACL tears demonstrates satisfactory outcomes in 28 patients (82.4%) at 5-year follow-up. Six patients sustained a re-rupture and have no ongoing problems following treatment with a conventional ACL reconstruction. These patients were significantly younger and had higher initial Marx activity scores.

LEVEL OF EVIDENCE

Level IV.

All-Cause Failure Rates Increase With Time Following Meniscal Repair Despite Favorable Outcomes: A Systematic Review and Meta-analysis

PURPOSE

The purpose of this review is to perform a meta-analysis of studies reporting meniscus repair outcomes. Pooled analyses of such studies will provide an accurate estimate of the outcomes that can be expected following meniscal repair at various postoperative time points.

METHODS

A meta-analysis of meniscal repair failure (defined as persistent symptoms, lack of healing on magnetic resonance imaging or revision surgery) and other clinical outcomes was performed following meniscal repair. Patients included had traumatic, nondegenerative meniscal tears, were skeletally mature, and had specific time-points after surgery. Repairs included were performed either in isolation, or with concomitant ACL reconstruction. Because of the inherent heterogeneity of single-arm meta-analyses, pooled analyses were performed using a random-effects model.

RESULTS

Rates of all-cause meniscal repair failure was pooled to be 12% at 0-1 years (95% CI: .09-.16), 15% at 2-3 years (95% CI: .11-.20), and 19% at 4-6 years (95% CI: .13-.24). Sensitivity analysis for studies performing meniscal repair entirely on patients with concomitant ACL reconstruction (ACLR) showed comparable rates of failure at similar time intervals. Development of osteoarthritis, in patients with knees previously free from articular pathologies, was 4% at 2-3 years (95% CI: .02-.07), and 10% at 4-6 years (95% CI: .03-.25).

CONCLUSION

Meniscus repair for traumatic injuries have an all-cause failure rate that increases from 12% to 19% through a time period ranging from 1-6 years following surgery. The failure rates were comparable for patients with meniscal repairs performed with concomitant ACLRs.

LEVEL OF EVIDENCE

IV; Systematic Review of Level II-IV Studies.

Testing Hypoxia in Pig Meniscal Culture: Biological Role of the Vascular-Related Factors in the Differentiation and Viability of Neonatal Meniscus

Menisci play an essential role in shock absorption, joint stability, load resistance and its transmission thanks to their conformation. Adult menisci can be divided in three zones based on the vascularization: an avascular inner zone with no blood supply, a fully vascularized outer zone, and an intermediate zone. This organization, in addition to the incomplete knowledge about meniscal biology, composition, and gene expression, makes meniscal regeneration still one of the major challenges both in orthopedics and in tissue engineering. To overcome this issue, we aimed to investigate the role of hypoxia in the differentiation of the three anatomical areas of newborn piglet menisci (anterior horn (A), central body (C), and posterior horn (P)) and its effects on vascular factors. After sample collection, menisci were divided in A, C, P, and they were cultured in vitro under hypoxic (1% O₂) and normoxic (21% O₂) conditions at four different experimental time points (T0 = day of explant; T7 = day 7; T10 = day 10; T14 = day 14); samples were then evaluated through immune, histological, and molecular analyses, cell morpho-functional characteristics; with particular focus on matrix composition and expression of vascular factors. It was observed that hypoxia retained the initial phenotype of cells and induced extracellular matrix production resembling a mature tissue. Hypoxia also modulated the expression of angiogenic factors, especially in the early phase of the study. Thus, we observed that hypoxia contributes to the fibro-chondrogenic differentiation with the involvement of angiogenic factors, especially in the posterior horn, which corresponds to the predominant weight-bearing portion.

Advances in the Mechanisms Affecting Meniscal Avascular Zone Repair and Therapies

Injuries to menisci are the most common disease among knee joint-related morbidities and cover a widespread population ranging from children and the general population to the old and athletes. Repair of the injuries in the meniscal avascular zone remains a significant challenge due to the limited intrinsic healing capacity compared to the peripheral vascularized zone. The current surgical strategies for avascular zone injuries remain insufficient to prevent the development of cartilage degeneration and the ultimate emergence of osteoarthritis (OA). Due to the drawbacks of current surgical methods, the research interest has been transferred toward facilitating meniscal avascular zone repair, where it is expected to maintain meniscal tissue integrity, prevent secondary cartilage degeneration and improve knee joint function, which is consistent with the current prevailing management idea to maintain the integrity of meniscal tissue whenever possible. Biological augmentations have emerged as an alternative to current surgical methods for meniscal avascular zone repair. However, understanding the specific biological mechanisms that affect meniscal avascular zone repair is critical for the development of novel and comprehensive biological augmentations. For this reason, this review firstly summarized the current surgical techniques, including meniscectomies and meniscal substitution. We then discuss the state-of-the-art biological mechanisms, including vascularization, inflammation, extracellular matrix degradation and cellular component that were associated with meniscal avascular zone healing and the advances in therapeutic strategies. Finally, perspectives for the future biological augmentations for meniscal avascular zone injuries will be given.

Small lateral meniscus tears propagate over time in ACL intact and deficient knees

PURPOSE

To quantify propagation of small longitudinal tears in the lateral meniscus in ACL intact and deficient knees.

METHODS

Using a robotic testing system, 5-Nm of external tibial torque + 5-Nm of valgus torque + 250-N of axial compression was applied to 14 fresh-frozen cadaveric knees while the knees were flexed from 30° to 90°. Knees were divided into two groups: intact (N = 8) and ACL deficient (N = 6). Kinematic data was recorded for four knee states: intact or ACL deficient knee, after posterior arthrotomy, meniscus tear at baseline, and after 500 cycles of the applied loading condition.

RESULTS

Lateral meniscus tear length increased throughout the 500 cycles regardless of the ACL integrity (p < 0.001). Overall, an increase of 28.7% and 26.1% was observed in intact and ACL deficient knees, respectively. In intact knees, external tibial rotation increased with meniscus tear propagation at all flexion angles by up to 45.5% (p = 0.019). In contrast, knee kinematics in ACL deficient knees were not affected by meniscus tear propagation (n.s.). In ACL deficient knees, resultant forces in the lateral meniscus increased at all flexion angles by up to 116.5% (p = 0.012). No differences in forces were observed in the intact knees (n.s.).

CONCLUSION

The data of this study show that small longitudinal tears in the lateral meniscus propagate significantly regardless of the integrity of the ACL and even after only 100 cycles of knee loading. The propagation of such tears altered kinematics and forces in the knee. Therefore, small, longitudinal lateral meniscus tears that are untreated in current clinical practices may propagate when loaded.

A review of strategies for development of tissue engineered meniscal implants

The meniscus is a key stabilizing tissue of the knee that facilitates proper tracking and movement of the knee joint and absorbs stresses related to physical activity. This review article describes the biology, structure, and functions of the human knee meniscus, common tears and repair approaches, and current research and development approaches using modern methods to fabricate a scaffold or tissue engineered meniscal replacement. Meniscal tears are quite common, often resulting from sports or physical training, though injury can result without specific contact during normal physical activity such as bending or squatting. Meniscal injuries often require surgical intervention to repair, restore basic functionality and relieve pain, and severe damage may warrant reconstruction using allograft transplants or commercial implant devices. Ongoing research is attempting to develop alternative scaffold and tissue engineered devices using modern fabrication techniques including three-dimensional (3D) printing which can fabricate a patient-specific meniscus replacement. An ideal meniscal substitute should have mechanical properties that are close to that of natural human meniscus, and also be easily adapted for surgical procedures and fixation. A better understanding of the organization and structure of the meniscus as well as its potential points of failure will lead to improved design approaches to generate a suitable and functional replacement.

Meniscus Repair Techniques

The menisci play a vital role in maintaining knee function and protecting the chondral surfaces. Acute and chronic tears are common injuries among both young athletes and older patients with early degenerative changes. The progression of physiological derangement and chondral injury after meniscus injury and meniscectomy have prompted interest in expanding meniscus repair techniques. Recent literature encourages an attempt at repair in tear patterns previously declared irreparable if the tissue quality allows. The orthopedic surgeon should understand the multitude of techniques available to them and be prepared to combine techniques to optimize the quality of their repair construct. While biological augmentation may show some promising early results, the quality of the current data precludes strong recommendations in their favor.

All-Inside Double-Sided Suture Repair for Longitudinal Meniscal Tears

The current consensus in the literature is that the meniscus must be saved. Even though inside-out sutures are still considered as the gold standard, the need to alternate between intra- and extra-articular structures for every stitch makes it laborious. New generations of all-inside systems are now routinely used in operating rooms and enable easier, quicker, and safer techniques. However traditional all-inside repair with limited upper fixation does not provide uniform compression from top to down, essential precondition for satisfactory meniscal healing. This Technical Note describes a simple and accessible alternative technique that provides stable fixation and overall compression of vertical meniscal tears from top to down with standard all-inside instrumentation.

Meniscal Regenerative Scaffolds Based on Biopolymers and Polymers: Recent Status and Applications

Knee menisci are structurally complex components that preserve appropriate biomechanics of the knee. Meniscal tissue is susceptible to injury and cannot heal spontaneously from most pathologies, especially considering the limited regenerative capacity of the inner avascular region. Conventional clinical treatments span from conservative therapy to meniscus implantation, all with limitations. There have been advances in meniscal tissue engineering and regenerative medicine in terms of potential combinations of polymeric biomaterials, endogenous cells and stimuli, resulting in innovative strategies. Recently, polymeric scaffolds have provided researchers with a powerful instrument to rationally support the requirements for meniscal tissue regeneration, ranging from an ideal architecture to biocompatibility and bioactivity. However, multiple challenges involving the anisotropic structure, sophisticated regenerative process, and challenging healing environment of the meniscus still create barriers to clinical application. Advances in scaffold manufacturing technology, temporal regulation of molecular signaling and investigation of host immunoresponses to scaffolds in tissue engineering provide alternative strategies, and studies have shed light on this field. Accordingly, this review aims to summarize the current polymers used to fabricate meniscal scaffolds and their applications in vivo and in vitro to evaluate their potential utility in meniscal tissue engineering. Recent progress on combinations of two or more types of polymers is described, with a focus on advanced strategies associated with technologies and immune compatibility and tunability. Finally, we discuss the current challenges and future prospects for regenerating injured meniscal tissues.