Meniscus repair and transplantation: a comprehensive update

Advances in meniscus tissue engineering: Towards bridging the gaps from bench to bedside

Meniscus is vital for maintaining the anatomical and functional integrity of knee. Injuries to meniscus, commonly caused by trauma or degenerative processes, can result in knee joint dysfunction and secondary osteoarthritis, while current conservative and surgical interventions for meniscus injuries bear suboptimal outcomes. In the past decade, there has been a significant focus on advancing meniscus tissue engineering, encompassing isolated scaffold strategies, biological augmentation, physical stimulus, and meniscus organoids, to improve the prognosis of meniscus injuries. Despite noteworthy promising preclinical results, translational gaps and inconsistencies in the therapeutic efficiency between preclinical and clinical studies exist. This review comprehensively outlines the developments in meniscus tissue engineering over the past decade (Scheme 1). Reasons for the discordant results between preclinical and clinical trials, as well as potential strategies to expedite the translation of bench-to-bedside approaches are analyzed and discussed.

Radial and longitudinal meniscus tears show different gapping patterns under stance phase conditions

Meniscal tearing can increase the contact pressure between the tibia and femur by causing gapping of torn meniscus tissue. The aim of this study was to quantify gapping behavior of radial and longitudinal tears and their impact on peak contact pressure and mean contact area. Twelve porcine knee joints underwent unicondylar, convertible osteotomy for exact tear application and consecutive suturing. Six tantalum marker beads were positioned along meniscus tears. The joints were preloaded with sinusoidal loading cycles ranging between 0 N and 350 N. Peak load was held constant and two synchronized Roentgen stereophotogrammetric analysis x-ray images were obtained to evaluate gapping, peak contact pressure and mean contact area in the native, torn and repaired states. There was no change in gapping or peak contact pressure in longitudinal tear. By contrast, the radial tear led to a significant gapping when compared to the native state, while the inside-out suture was able to restore gapping in parts of the meniscus. An increase in contact pressure after radial tear was detected, which was again normalized after suturing. The most important finding of the study is that longitudinal tears did not gap under pure axial loading, whereas radial tears tended to separate the tear interfaces.

Usefulness of Probing Sensor Device for Evaluating Meniscal Suture and Scaffold Implantation

Appropriate suture tension is a key factor in successful meniscal repair. This study aimed to clarify the appropriate value of meniscal stabilization with suture repair based on a probing procedure for healthy porcine menisci and a novel meniscal scaffold. After evaluating the reliability of the probing sensor, meniscal vertical tear and partial meniscectomy models were developed, in which suture repair and meniscal scaffold implantation were performed at suture intervals ranging between 20 and 2.5 mm. The residence forces at each interval were evaluated using a probing sensor. Moreover, a tensile test was conducted to evaluate the displacement and presence or absence of gaps. We found that normal and meniscal scaffolds should be fixed within 5 mm of suture interval. The probing residence forces required were at least 1.0 N for vertical tears and 3.0 N for meniscal scaffolds. These findings may be taken into consideration to reduce suture failure following meniscal tear repair and stabilizing meniscal scaffold fixation.

Thickness and width of the menisci of adult knee joint: a descriptive cross-sectional observational study in cadavers

Background

The goal was to determine the thickness and width of the knee joint meniscus at their different regions. The objective was to compare the dimensions at these regions and over the right- and left-sided specimens.

Methods

The present study included 50 adult cadaveric knee joints, and 100 menisci (50 medial menisci and 50 lateral menisci) were studied. The meniscus was distributed into anterior, middle and posterior parts. Thickness and width at the mid-point of these three parts were determined by using the Vernier caliper.

Results

The breadth of the medial meniscus was 8.38 ± 1.64 mm, 7.68 ± 1.92 mm and 13.93 ± 2.69 mm at the anterior, middle and posterior one-third regions. Same measurements for the lateral menisci at these regions were 9.84 ± 1.78 mm, 8.82 ± 2.01 mm and 10.18 ± 2.23 mm, respectively. The thickness of the medial meniscus was 4.49 ± 0.78 mm, 4.07 ± 0.81 mm and 4.79 ± 0.93 mm at these regions. The lateral meniscus thickness was 3.82 ± 0.69 mm, 4.43 ± 0.98 mm and 4.36 ± 0.8 mm, respectively.

Conclusion

It is believed that this data is enlightening to the arthroscopic surgeon during the meniscus transplantation either by using synthetic material or allograft as the proper sizing of the meniscus is important to prevent complications due to inaccurate sizing.

Meniscus Allograft Transplantation With Bone Plugs Using Knotless All-Suture Anchors and Cortical Button Suspensory Fixation

Meniscus allograft transplantation can be successful for treatment of meniscal deficiency using a number of transplant techniques. In this Technical Note, we describe a double bone plug medial meniscus allograft transplantation technique that uses knotless all-suture anchors with cortical-button suspensory fixation. This technique maintains the reported advantages for bone-plug fixation while mitigating the risk for meniscal root damage, facilitating easier bone plug insertion and seating, expanding tensioning capabilities, and preventing soft-tissue irritation from suture knot stacks.

Rehabilitation after Repair of Medial Meniscus Posterior Root Tears: A Systematic Review of the Literature

Background

There is no consensus established on postoperative rehabilitation after medial meniscus posterior root tear (MMPRT) repair, including when and how physicians can apply range of motion (ROM) exercise, weight-bearing (WB), brace use, and return to sports (RTS). The purpose of this study was to systematically review the literature on postoperative rehabilitation characteristics of MMPRT repair regarding ROM, WB, brace use, and RTS.

Methods

A literature search was performed using the Medline/PubMed, Cochrane Central Register of Controlled Trials, and Embase databases. The inclusion criteria were English language, human clinical studies, and studies describing rehabilitation protocols after MMPRT repair such as ROM, WB, brace use, and RTS. Abstracts, case reports, cohort studies, controlled laboratory studies, human cadaveric or animal studies, systematic reviews, and meta-analyses were excluded.

Results

Thirteen studies were included. Of the 12 ROM studies, ROM was started immediately within 1 or 2 days after operation in 6 studies and after 2 to 3 weeks of knee immobilization in the rest. Of the 13 WB studies, partial weight-bearing was initiated 1 to 4 weeks after operation in 8 studies and 6 weeks in the rest. Of the 9 brace studies, patients were immobilized by a splint for 2 weeks in 3 studies, and in the rest, a brace with full extension was applied for 3 to 6 weeks after several days of splint application. Of the 7 RTS studies, RTS was allowed at 6 months in 6 studies and 5 to 7 months in 1 study.

Conclusions

This systematic review revealed conservative rehabilitation protocols were more widely adapted as ROM and WB were restricted at certain degrees during postoperative periods in most protocols analyzed. However, it is impossible to identify a consensus on rehabilitation protocols as the protocols analyzed in this review were distinct each other and heterogeneous. In the future, a well-designed comparative study among different rehabilitation protocols is essential to establish a consensus.

Strength-Based Rehabilitation on Clinical Outcomes in Patients Postpartial Meniscectomy: A Systematic Review and Meta-analysis

OBJECTIVE

The aim of the study is to determine the effect of strength-based rehabilitation programs on patients who underwent partial meniscectomy procedures.

DESIGN

Three databases MEDLINE, PubMed, and Embase were searched from inception to May 9, 2022. Data on functional outcomes such as quadriceps and hamstring strengths, as well as patient-reported outcomes such as Knee Osteoarthritis and Outcome Score and visual analog scale were recorded.

RESULTS

A total of nine studies comprising 417 patients were included in this review. There were no significant differences in quadriceps or hamstring strength measures between preinterventation and postintervention for both groups. Knee Osteoarthritis and Outcome Scores significantly increased from preintervention and postintervention in both control and exercise groups. Visual analog scale scores changed from 5.0 to 1.4 cm in the exercise arm and 3.1 to 1.9 cm in the control arm.

CONCLUSIONS

Strength-based exercise programs for patients postpartial meniscectomy did not result in significantly different improvements in quadriceps or hamstring strength compared with control programs. However, strength-based exercise programs resulted in significantly higher Knee Osteoarthritis and Outcome Scores and a greater decrease in visual analog scale scores. Further studies, specifically well-designed systematic randomized controlled trials, are necessary to elucidate the specifics behind what type of exercises to use in addition to load progression and frequency of training.

Meniscus Allograft Transplantation Augmented With Autologous Bone Marrow Aspirate Concentrate

Meniscus allograft transplantation (MAT) has been shown to be a feasible surgical option for younger patients, below 50 years of age who have meniscal insufficiency and have failed conservative treatment measures. In this technical note, we describe a procedure of harvesting and injecting bone marrow aspirate concentrate in a meniscus allograft during a MAT procedure, which may allow for longer lasting transplants and improve patient outcomes. In this technical note, bone marrow aspirate concentrate is harvested arthroscopically from the intercondylar notch at the surgical site, which prevents additional donor site morbidity, as seen with harvesting from other locations, such as the iliac crest. This also reduces operating time, since harvesting from the iliac crest requires different patient positioning and usually additional anesthesia. The authors of this surgical technique believe that biological augmentation during MATs will assist surgeons in maximizing graft survivorship and, ultimately, lead to better patient outcomes.

Effects of Aquatic Training and Bicycling Training on Leg Function and Range of Motion in Amateur Athletes with Meniscal Allograft Transplantation during Intermediate-Stage Rehabilitation

Meniscal allograft transplantation (MAT) is a treatment modality for restoring knee function in patients with irreversible meniscal injury. Strengthening programs to promote functional recovery are treated with caution during the intermediate rehabilitation phase following MAT. This study analyzed the effects of aquatic training (AQT) and bicycling training (BCT) during the intermediate stage of rehabilitation in amateur athletes that underwent MAT. Participants (n = 60) were divided into AQT (n = 30) and BCT (n = 30) groups. Both groups performed training three times per week from 6 to 24 weeks following surgery. International Knee Documentation Committee Subjective Knee Evaluation Form (IKDC) score, knee joint range of motion (ROM), isokinetic knee strength, and Y-balance test (YBT) performance were evaluated. All measured variables for the AQT and BCT groups improved significantly after training compared with pre-training values. The IKDC score and YBT were significantly higher for AQT than for BCT. The knee flexion ROM and isokinetic muscle strength were significantly improved in the BCT group compared to those in the AQT group. The AQT group exhibited greater improvement in dynamic balance, whereas BCT provided greater improvement in isokinetic muscle strength. AQT and BCT were effective in reducing discomfort and improving knee symptoms and functions during intermediate-stage rehabilitation following MAT in amateur athletes.

Evidence-based rationale for treatment of meniscal lesions in athletes

Meniscal injuries in elite athletes are a common cause of missed game time and even have the potential to be career shortening. In this patient group, care must be paid not only to the pathology, but also to a player's contract status, time in the season, specific demands of his/her sport and position on the field, and future consequences. Successful treatment requires the clinician to understand the player's goals and needs, communicate effectively between all stakeholders, and a have knowledge of the challenges posed by the different types of meniscal tear seen in this population. Paramount is the distinction between injuries to the medial and lateral meniscus. Deficiency of the lateral meniscus, as a result of a tear or a meniscectomy, leads to frequent early problems and inexorably to chondral degeneration thereby affecting an athlete's ability to perform. Therefore, it is strongly recommended to repair the majority of lateral meniscal tears. Medial meniscal tears pose a more challenging treatment dilemma, as the success of partial meniscectomy in achieving reproducible, early return to play must be balanced against the long-term degenerative consequences. Many meniscal tears are correctly treated non-operatively.Level of evidence V.

Arthroscopic Treatment of a “Bucket-Handle Like Tear” Lesion of the Medial Meniscus

Menisci are involved in providing shock absorption, knee stability, and load transfer. Age, tear pattern, location, size and extent, repair time and technique, and patient habits are among various factors that affect meniscal healing. Meniscus repair has become the procedure of choice for the treatment of meniscal tears. However, treatment of meniscal tears in patients over 40 years of age is still debatable. Rare patterns of lesions have been described in the literature. We report a zone 2, partial thickness, “bucket-handle like tear” medial meniscal lesion with two attached ends in a 48-year-old male patient with persistent symptoms after six months of conservative treatment. Arthroscopic excision and debridement were performed. At a six-month follow-up, the patient regained 90% of his functional capacity.

Advances in electrospun scaffolds for meniscus tissue engineering and regeneration

The meniscus plays a critical role in maintaining the homeostasis, biomechanics, and structural stability of the knee joint. Unfortunately, it is predisposed to damages either from sports-related trauma or age-related degeneration. The meniscus has an inherently limited capacity for tissue regeneration. Self-healing of injured adult menisci only occurs in the peripheral vascularized portion, while the spontaneous repair of the inner avascular region seems never happens. Repair, replacement, and regeneration of menisci through tissue engineering strategies are promising to address this problem. Recently, many scaffolds for meniscus tissue engineering have been proposed for both experimental and preclinical investigations. Electrospinning is a feasible and versatile technique to produce nano- to micro-scale fibers that mimic the microarchitecture of native extracellular matrix and is an effective approach to prepare nanofibrous scaffolds for constructing engineered meniscus. Electrospun scaffolds are reported to be capable of inducing colonization of meniscus cells by modulating local extracellular density and stimulating endogenous regeneration by driving reprogramming of meniscus wound microenvironment. Electrospun nanofibrous scaffolds with tunable mechanical properties, controllable anisotropy, and various porosities have shown promises for meniscus repair and regeneration and will undoubtedly inspire more efforts in exploring effective therapeutic approaches towards clinical applications. In this article, we review the current advances in the use of electrospun nanofibrous scaffolds for meniscus tissue engineering and repair and discuss prospects for future studies.

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.

Rehabilitation and Return to Play Following Meniscus Repair

Injuries to the meniscus, particularly tears, can have significant negative impacts on pain, function, and quality of life. Preservation of the meniscus is favorable, especially in the athletic and active populations. While first line treatment is often nonoperative in nature, recalcitrant, and more complex tears, typically require surgery. Meniscus repair rates have increased significantly during the last 2 decades as surgical techniques and postoperative outcomes have improved. Longer postoperative timeframes are to be expected when compared with menisectomy, however, accelerated programs have demonstrated favorable outcomes. Rehabilitation and return to play guidelines should reflect the intricacies of the tear type and repair procedure. Close communication with the surgeon is a vital component to optimize patient outcomes. Further, the patient's goals and expected level of return to function, or sport, must be taken into account for a rehabilitation program to be fully successful.

Avaliação das propriedades histológicas de enxertos meniscais humanos armazenados em banco de tecido

Objectives  The present paper aims to evaluate and compare the histological features of fresh and frozen menisci stored in a tissue bank for 1 month and for 5 years.

Methods  The meniscal grafts were subjected to a histological study. A total of 10 menisci were evaluated; 2 were frozen for 5 years, 4 were frozen for 1 month, and 4 were fresh, recently harvested specimens. Histological properties were evaluated in sections stained with hematoxylin and eosin and Masson trichrome methods.

Results  The menisci frozen for 1 month showed partially preserved collagen fiber structure and no significant hydropic tissue degeneration. The menisci frozen for 5 years presented an evident dissociation of collagen fibers and multiple foci of hydropic degeneration.

Discussion  Degeneration was much more significant in menisci stored for 5 years, indicating that a long freezing period results in substantial progression of tissue deterioration. This may suggest that the 5-year period, considered the maximum time for graft storage before transplant, is too long.

Conclusion  Grafts stored for 1 month showed a slight degenerative change in collagen fibers, whereas menisci frozen for 5 years presented significant tissue degeneration.

Radiographic Methods Are as Accurate as Magnetic Resonance Imaging for Graft Sizing Before Lateral Meniscal Transplantation

BACKGROUND

Accurate allograft matching is deemed critical for meniscal transplantation; thus, precise measurements are essential to correctly calculate meniscal size. Several methods for meniscal sizing have been described, but there remains a discussion on which is the most accurate for the lateral meniscus.

PURPOSE

To compare the accuracy of radiographic, anthropometric, and magnetic resonance imaging (MRI) methods of determining width and length of the lateral meniscus with actual dimensions after anatomic dissection.

STUDY DESIGN

Controlled laboratory study.

METHODS

Ten fresh-frozen human cadaveric knees without any evidence of meniscal or ligamentous injury were primarily imaged using radiography and MRI and subsequently underwent dissection to assess the anatomic size of each meniscus. Four methods were used to predict the size of the lateral menisci: anthropometric, radiographic (Pollard and Yoon), and MRI. Absolute differences in length and width between actual and predicted sizes were determined.

RESULTS

The anatomic lateral meniscal width and length were 33.01 ± 4.25 mm (mean ± SD; range, 24.84-40.18 mm) and 31.41 ± 5.06 mm (range, 25.2-40.05 mm), respectively. Regarding width, the anthropometric method demonstrated an absolute difference from anatomic measurement significantly greater when compared with the Pollard technique and MRI (P = .002). Regarding length, the Pollard method presented an absolute difference significantly greater than all other techniques (P = .003). In terms of the ability to measure width and length, MRI accurately predicted meniscal size within 10% of the anatomic size in 65% of measurements, the Yoon method in 54%, and the Pollard method in 20% (P = .01). Radiographs tended to overestimate the true size of the lateral meniscus, while the anthropometric technique overestimated width in all specimens.

CONCLUSION

This study demonstrated that MRI and the Yoon radiographic method are comparable in terms of accuracy for graft sizing before lateral meniscal transplantation. While MRI is useful, a contralateral MRI is required, which makes the Yoon radiographic method recommended given the ease and cost advantage. The original Pollard technique and the anthropometric method are not recommended.

CLINICAL RELEVANCE

Over- and undersizing of meniscal transplants has been implicated in graft failure. Therefore, increasing the reliability of preoperative meniscal measurements is deemed important for the success of meniscal allograft transplantation.

Outcomes of arthroscopic repair using the all-inside inter-leaf vertical suture technique for horizontal meniscal tears sustained in sports

The aim of the study was to evaluate the outcomes of arthroscopic repair using the all-inside inter-leaf vertical suture arthroscopic technique for sports-related horizontal meniscal tears.The inter-leaf vertical suture procedure was performed to repair sports-related horizontal tears in the middle and posterior segments of the medial (11 cases) and lateral (2 cases) menisci in 13 patients (mean age: 30 ± 14 years). Pre- and post-operative Barrett criteria, Lysholm scores, and patient ability to resume sports were assessed. Magnetic resonance imaging (MRI) grades and signal intensity changes near the joint capsule were evaluated in the 9 cases among which pre- and post-operative MRI images were available.All Barrett criteria items were negative following surgery; Lysholm scores increased from 70.2 ± 13.1 before surgery to 98.9 ± 2.64 after surgery (P < .01). All patients were able to resume their sport. Preoperative MRI grade of tears was 3 for all patients; postoperative MRI grades were 1 in 3 cases, 2 in 4 cases, and 3 in 2 cases (P < .05). Importantly, MRI signal intensity at the repaired menisci near the joint capsule was reduced in 8 of these 9 cases postoperatively.The inter-leaf vertical suture procedure is associated with good outcomes for horizontal tears in the middle and posterior segments of the medial and lateral menisci. The procedure is useful and convenient.

Early Functional Rehabilitation after Meniscus Surgery: Are Currently Used Orthopedic Rehabilitation Standards Up to Date?

Meniscus therapy is a challenging process. Besides the respective surgical procedure such as partial meniscectomy, meniscus repair, or meniscus replacement, early postoperative rehabilitation is important for meniscus regeneration and return to sport and work as well as long-term outcome. Various recommendations are available. However, the current literature lacks information concerning the actual early rehabilitation in daily routine recommended by orthopedic surgeons. Thus, the purpose of this study was to investigate currently used standard early rehabilitation protocols in the daily routine of orthopedic surgeons. This study investigated the recommendations and concepts for early rehabilitation after meniscus therapy given by German, Austrian, and Swiss orthopedic institutions. Standardized criteria such as weight bearing, range of motion, use of an orthosis, and rehabilitation training were analyzed according to the conducted surgical procedure: partial meniscectomy, meniscus repair, or meniscus replacement. The analysis of standard rehabilitation concepts for partial meniscectomy (n = 15), meniscus repair (n = 54), and meniscus replacement (n = 7) showed significantly earlier functional rehabilitation in all criteria after partial meniscectomy in contrast to meniscus repair techniques (p < 0.001). In addition, significant restrictions were found in full weight bearing, full range of motion, and the use of braces. In summary, a wide range of recommendations for weight bearing, ROM, brace therapy, and mobilization is available, particularly after meniscus repair and meniscus replacement. Most concepts are in accordance with those described in the current literature. Further research is necessary to enhance the scientific evidence on currently used early rehabilitation concepts after meniscus therapy.

Secondary Meniscal Tears in Patients With Anterior Cruciate Ligament Injury: Relationship Among Operative Management, Osteoarthritis, and Arthroplasty at 18-Year Mean Follow-up

BACKGROUND

Anterior cruciate ligament (ACL) injury is one of the most frequent orthopaedic injuries and reasons for time loss in sports and carries significant implications, including posttraumatic osteoarthritis (OA). Instability associated with ACL injury has been linked to the development of secondary meniscal tears (defined as tears that develop after the initial ACL injury). To date, no study has examined secondary meniscal tears after ACL injury and their effect on OA and arthroplasty risk.

PURPOSE

To describe the rates and natural history of secondary meniscal tears after ACL injury and to determine the effect of meniscal tear treatment on the development of OA and conversion to total knee arthroplasty (TKA).

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A geographic database of >500,000 patients was reviewed to identify patients with primary ACL injuries between January 1, 1990, and December 31, 2005. Information was collected with regard to ACL injury treatment, rates/characteristics of the secondary meniscal tears, and outcomes, including development of OA and conversion to TKA. Kaplan-Meier and adjusted multivariate survival analyses were performed to test for the effect of meniscal treatment on survivorship free of OA and TKA.

RESULTS

Of 1398 primary ACL injuries, the overall rate of secondary meniscal tears was 16%. Significantly lower rates of secondary meniscal tears were noted among patients undergoing acute ACL reconstruction within 6 months (7%) as compared with patients with delayed ACL reconstruction (33%, P < .01) and nonoperative ACL management (19%, P < .01). Of the 235 secondary meniscal tears identified (196 patients), 11.5% underwent repair, 73% partial meniscectomy, and 16% were treated nonoperatively. Tears were most often medial in location (77%) and complex in morphology (56% of medial tears, 54% of lateral tears). At the time of final follow-up, no patient undergoing repair of a secondary meniscal tear (0%) underwent TKA, as opposed to 10.9% undergoing meniscectomy and 6.1% receiving nonoperative treatment ( P = .28).

CONCLUSION

Secondary meniscal tears after ACL injury are most common among patients undergoing delayed surgical or nonoperative treatment of their primary ACL injuries. Secondary tears often present as complex tears of the medial meniscus and result in high rates of partial meniscectomy.

Peripheral fixation of meniscal allograft does not reduce coronal extrusion under physiological load

PURPOSE

Meniscal graft extrusion is a concern following meniscal allograft transplantation (MAT). MAT surgical techniques continue to evolve in an effort to reduce extrusion; however, improvements remain difficult to measure in vivo. A novel MRI-compatible in vitro loading device capable of applying physiologically relevant loads has been developed, allowing for the measurement of extrusion under a variety of controllable conditions. The objective of this study was to compare maximal medial MAT extrusion (1) with and (2) without an additional peripheral third point of fixation on the tibial plateau.

METHODS

Twelve human cadaveric knees underwent medial MAT, utilizing soft tissue anterior and posterior root fixation via transosseous suture, with a third transosseous suture tied over a button providing peripheral fixation on the tibial plateau. The joint was positioned at 5 degrees of flexion and loaded to 1 × body weight (647.7 ± 159.0 N) during MR image acquisition, with and without peripheral fixation. The joint was then positioned at 30 degrees of flexion and the process was repeated. Maximal coronal extrusion was measured.

RESULTS

An increase in maximal coronal meniscal extrusion was noted between the unloaded and loaded states. At 30 degrees of flexion, with the addition of a peripheral fixation point, a statistically significant difference in absolute extrusion (p = 0.02) and relative percent extrusion (p = 0.04) between the unloaded and loaded state was found. The addition of a peripheral fixation suture resulted in an overall mean percent difference of - 2.49% (SD 14.1; 95% CI - 11.95, 6.97; n.s.) in extrusion at 5 degrees of flexion and a mean percent difference of - 0.95% (SD 7.3; 95% CI - 5.62, 3.71; n.s.) in extrusion at 30 degrees of flexion. These differences were not statistically significant.

CONCLUSION

These results suggest that the addition of a peripheral anchor in medial MAT does not reduce the amount of maximal coronal extrusion and, therefore, may not confer any clinical benefit. Surgical techniques utilized to reduce MAT extrusion need further investigation to understand if the added technical difficulty and potential expense is warranted.

Evaluation of Midterm Clinical and Radiographic Outcomes of Arthroscopically Repaired Vertical Longitudinal and Bucket-Handle Lateral Meniscal Tears

Background:

Lateral meniscal tears in the stable knee are rare. There are few comparative studies evaluating functional and radiological outcomes of vertical longitudinal and bucket-handle lateral meniscal tears.

Purpose:

To evaluate the midterm clinical and radiological outcomes of arthroscopically repaired traumatic vertical longitudinal and bucket-handle lateral meniscal tears.

Study Design:

Case series; Level of evidence, 4.

Methods:

A total of 43 full-thickness lateral meniscal repairs, including 22 (51.2%) for vertical longitudinal tears and 21 (48.8%) for bucket-handle tears, were evaluated. A clinical assessment was performed according to the Barrett criteria, and patient outcomes were measured with the Lysholm knee score, Tegner activity scale, and overall satisfaction scale. Magnetic resonance imaging was used as the radiological re-examination method preoperatively and at final follow-up. A subgroup analysis examining isolated repair versus repair with concurrent anterior cruciate ligament (ACL) reconstruction was performed.

Results:

The mean follow-up period was 63.2 months (range, 24-86 months). Based on clinical and radiological outcomes, 38 of the 43 repairs (88.3%) were successful, and the remaining 5 (11.6%) cases were considered to be failures. Overall, the combined results for both groups demonstrated an improvement in the Lysholm score, Tegner score, and patient satisfaction. There was no significant difference in the postoperative Lysholm score (91.4 vs 87.0, respectively; P = .223), Tegner score (5.4 vs 5.5, respectively; P = .872), or patient satisfaction (7.2 vs 7.4, respectively; P = .624) between bucket-handle repair and vertical longitudinal repair. The subgroup analysis demonstrated no difference in outcome scores for isolated repair versus repair with concurrent ACL reconstruction. Smoking was identified as a risk factor for repair failure.

Conclusion:

Comparable clinical and radiological outcomes were obtained after vertical longitudinal and bucket-handle lateral meniscal repairs using the all-inside or hybrid suture technique with different suture configurations, regardless of whether ACL reconstruction was performed. Smoking was identified as a risk factor for failure.

Modeling-Based Assessment of 3D Printing-Enabled Meniscus Transplantation

3D printing technology is able to produce personalized artificial substitutes for patients with damaged menisci. However, there is a lack of thorough understanding of 3D printing-enabled (3DP-enabled) meniscus transplantation and its long-term advantages over traditional transplantation. To help health care stakeholders and patients assess the value of 3DP-enabled meniscus transplantation, this study compares the long-term cost and risk of this new paradigm with traditional transplantation by simulation. Pathway models are developed to simulate patients' treatment process during a 20-year period, and a Markov process is used to model the state transitions of patients after transplantation. A sensitivity analysis is also conducted to show the effect of quality of 3D-printed meniscus on model outputs. The simulation results suggest that the performance of 3DP-enabled meniscus transplantation depends on quality of 3D-printed meniscus. The conclusion of this study is that 3DP-enabled meniscus transplantation has many advantages over traditional meniscus transplantation, including a minimal waiting time, perfect size and shape match, and potentially lower cost and risk in the long term.

One-Third of Meniscal Tears Are Repairable: An Epidemiological Study Evaluating Meniscal Tear Patterns in Stable and Unstable Knees

PURPOSE

To analyze, in a long series of patients with knee injuries, the meniscal tear patterns in both stable and unstable knees to ascertain the exact proportion of such injuries that could have been repaired.

METHODS

A descriptive cross-sectional study was undertaken by reviewing the clinical reports of arthroscopic knee operations carried out in 1 hospital. A total of 2,066 consecutive patients were included in the study. An analysis of clinical and anatomical data of knee lesions, including the shape of the meniscal tears and the surrounding injuries, was performed.

RESULTS

Out of all meniscal tears, 34.9% were found to be repairable, a figure that rose to 55.6% in those tears accompanied by anterior cruciate ligament injuries; 37% of meniscal tears in male patients were repairable, and 28% in their female counterparts; 38.2% of medial meniscal tears were repairable and 30.6% in their lateral counterparts. The most frequently encountered injury was the complex tear (46.9%).

CONCLUSIONS

Our study concludes that, according to current standard indications, 34.9% of all meniscal injuries offer the potential for repair. Where the injury is also accompanied by anterior cruciate ligament damage, the proportion of repairable tears rises to 55.6%. This information should increase the interest for meniscal preservation in the future.

LEVEL OF EVIDENCE

Level IV, case series.

Editorial Commentary: Meniscal Allograft Transplantation: Still Effective With Poor Cartilage, But Much Better With Good Cartilage-Better Done Earlier

Meniscal allograft transplantation (MAT) is an established treatment for a symptomatic, meniscus-deficient knee. It is well known that MAT is effective in patients with good cartilage even in the early era of this procedure. The role of MAT in arthritic knees is getting more and more clear with increasing evidence over the last decade. Now we are able to expand our surgical indication to arthritic patients and provide them with individualized explanation for outcome and survival.

Knee Meniscus Injuries: Common Problems and Solutions

The rates of arthroscopic meniscus repair continue to increase with excellent reported outcomes. Complications, sometimes catastrophic, following meniscus repair may occur. The rate of postoperative complications may be reduced by adequate diagnosis, appropriate patient selection, meniscus repair selection, surgical techniques, and postoperative management. When complications occur, the provider must identify and take steps to rectify as well as prevent further complications from occurring. The purpose of this article is to detail the common diagnostic, technical, and postoperative pitfalls that may result in poor patient outcomes.

Cryopreservation versus fresh frozen meniscal allograft: A biomechanical comparative analysis

Meniscal allograft transplantation may be a better alternative for the treatment of irreparable meniscal injury compared to other forms of treatment. However, it remains to be seen whether the use fresh frozen allograft is better than cryopreserved allograft in treating this type of injury. We hypothesized that cryopreserved meniscal allograft would work better in maintaining the original biomechanical properties compared to fresh frozen ones, due to the lower amount of damage it incurs during the storage process. We examined young and healthy human menisci obtained from orthopedic oncology patients who underwent resection surgeries around the knee. The menisci obtained were preserved via cryopreservation and deep-freezing process. Traction tests were carried out on the menisci after 6 weeks of preservation. Twelve pairs ( N = 24) of menisci were divided equally into two groups, cryopreservation and deep frozen. There were six males and six female menisci donors for this study. The age range was between 15 and 35 years old (24.9 ± 8.6 years). Cryopreserved specimens had a higher ultimate tensile strength (UTS; 8.2 ± 1.3 Mpa vs. 13.3 ± 1.7 Mpa: p < 0.05) and elastic modulus (61.7 ± 27.6 Mpa vs. 87.0 ± 44.10 Mpa: p < 0.05) compared to the fresh frozen specimens. There was a significant difference in UTS ( p < 0.05) between the two groups but no significant difference in their elastic modulus ( p > 0.05). The elastic modulus of the preserved meniscus was similar to fresh normal menisci taken from other studies (60-120 Mpa; cryopreserved (87.0 ± 44.1) and fresh frozen (61.7 ± 27.5)). Cryopreserved menisci had a higher elastic modulus and point of rupture (UTS) compared to fresh frozen menisci. Cryopreservation proved to be a significantly better method of preservation, among the two methods of preservation in this study.

A novel arthroscopic all-inside suture technique using the Fast-Fix 360 system for repairing horizontal meniscal tears in young athletes: 3 case reports

RATIONALE

Considering the risk of osteoarthritis following resection of a horizontally torn meniscus of the knee, repairing and preserving the meniscus as much as possible is preferred. We report 3 cases of restoration of horizontally torn menisci using a novel arthroscopic method we have called "all-inside interleaf vertical suture" that afforded preservation.

PATIENT CONCERNS

The 3 patients (aged 14, 17, and 21 years) had knee pain through sports activity.

DIAGNOSES

All patients had horizontal tears in the posteromedial part of the meniscus.

INTERVENTIONS

The method uses Fast-Fix, whereby a first anchor is inserted from the tibial surface of the tear's superior leaflet and a second anchor is inserted from the femoral surface of the tear's inferior leaflet, and the 2 leaflets are closed using vertical suture. In all cases, the suture knots were embedded between the superior leaflet and inferior leaflet, avoiding contact with the articular cartilage, and superior leaflet and inferior leaflet crimping was good.

OUTCOMES

All 3 were able to resume competing in sport and ≥ 1 year after surgery they had no pain and their postoperative mean Lysholm scores were 99.7. There were no complications or recurrence. On magnetic resonance imaging, the signal intensity of all the horizontal tears was high before surgery but low after surgery, suggesting that the repaired tear was healing.

LESSONS

The all-inside interleaf vertical suture procedure is a new surgical technique that can repair posteromedial horizontal meniscal tears of the knee of young people by easy crimping of the superior and inferior leaflets without the suture knots causing complications.

Should the meniscal height be considered for preoperative sizing in meniscal transplantation?

PURPOSE AND HYPOTHESIS

In preoperative sizing for meniscal transplantation, most authors take into consideration the length and width of the original meniscus, but not its height. This study aimed at evaluating (1) whether the meniscal height is associated with the meniscal length and width, (2) whether the heights of the meniscal segments are associated with the individual's anthropometric data, (3) whether the heights of the meniscal segments are associated with each other in the same meniscus, and (4) the degree of symmetry of the meniscal dimensions between the right and left knees.

METHODS

In this cross-sectional, observational study, two independent radiologists measured the meniscal length, width and height in knee magnetic resonance imaging scans obtained from 25 patients with patello-femoral pain syndrome. Reproducibility of measurements was calculated with intraclass correlation coefficients. Associations between the anthropometric data and the meniscal measurements, the meniscal length and width versus height, and the heights of the meniscal segments in the same meniscus were examined with Pearson's correlation.

RESULTS

Inter-observer reliability was excellent (>0.8) for length and height and good (0.6-0.8) for width measurements. There was also excellent agreement (>0.8) for the length and width of the menisci in the right and left knees. The heights of the horns of the lateral meniscus showed good agreement (0.6-0.8), while the heights of the other meniscal segments had excellent agreement between the sides (>0.8). There were significant associations with generally low (r < 0.5) correlation between the heights of the meniscal segments and the lengths and widths of the menisci, between the meniscal height and anthropometric data, and between the heights of the meniscal segments in the same meniscus. Correlations between anthropometric data and meniscal length and width were generally high (r > 0.7).

CONCLUSIONS

There was excellent agreement between the meniscal dimensions of the right and left knees, and a weak association between the meniscal height with the meniscal width and length, between the height of the menisci with anthropometric data and between the heights of the segments in the same meniscus. The height of the meniscal segments may be a new variable in preoperative meniscal measurement.

Factors Affecting the Outcomes of Arthroscopically Repaired Traumatic Vertical Longitudinal Medial Meniscal Tears

BACKGROUND

Although numerous studies have assessed arthroscopic medial meniscal repairs, few studies have focused on factors affecting outcomes of vertical longitudinal and bucket-handle repairs.

PURPOSE

To evaluate the factors affecting clinical outcomes of arthroscopically repaired traumatic vertical longitudinal and bucket-handle medial meniscal tears.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 223 patients underwent arthroscopic repair for medial meniscal tears between 2007 and 2012; 140 patients had isolated tears or concurrent anterior cruciate ligament (ACL) reconstruction, and 80 patients (76 men, 4 women; mean age, 29.1 years; range, 18-49 years) had vertical longitudinal tears and were included in the study. Pre- and postoperative functional status was assessed using physical examinations with Lysholm and International Knee Documentation Committee (IKDC) scores. Barrett criteria were used for clinical assessment of meniscal healing, and magnetic resonance imaging (MRI) was used as the radiologic assessment method. The effects of tear location, length, chronicity, and type; suturing technique; concurrent ACL reconstruction; and patient age, sex, and smoking habits were also investigated.

RESULTS

The mean follow-up period was 51.2 ± 9.4 months (range, 34-85 months). The mean Lysholm and IKDC scores improved at final follow-up (both Ps <.001). According to clinical scores, Barrett criteria, and MRI, failure was noted in 12 patients (15%). There were no significant differences in age, tear length, tear type, concurrent ACL rupture, suturing technique, or location of the meniscal repair between the success and failure groups. Failure rates were higher for red-white zone tears than for red-red zone tears (10/30, 33.3% vs 2/50, 4%; P = .004). Tear chronicity significantly affected failure rates. Early repairs had higher healing rates than late repairs (100% vs 73.4%; P = .008). Failure rates were higher for smokers than for nonsmokers (9/24, 37.5% vs 3/56, 5.3%; P = .008).

CONCLUSION

Peripheral tears and early repairs have better outcomes and patient satisfaction. Smoking adversely affects meniscal healing.

Joint Preservation Techniques in Orthopaedic Surgery

CONTEXT

With increasing life expectancy, there is growing demand for preservation of native articular cartilage to delay joint arthroplasties, especially in younger, active patients. Damage to the hyaline cartilage of a joint has a limited intrinsic capacity to heal. This can lead to accelerated degeneration of the joint and early-onset osteoarthritis. Treatment in the past was limited, however, and surgical treatment options continue to evolve that may allow restoration of the natural biology of the articular cartilage. This article reviews the most current literature with regard to indications, techniques, and outcomes of these restorative procedures.

EVIDENCE ACQUISITION

MEDLINE and PubMed searches relevant to the topic were performed for articles published between 1995 and 2016. Older articles were used for historical reference. This paper places emphasis on evidence published within the past 5 years.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 4.

RESULTS

Autologous chondrocyte implantation and osteochondral allografts (OCAs) for the treatment of articular cartilage injury allow restoration of hyaline cartilage to the joint surface, which is advantageous over options such as microfracture, which heal with less favorable fibrocartilage. Studies show that these techniques are useful for larger chondral defects where there is no alternative. Additionally, meniscal transplantation can be a valuable isolated or adjunctive procedure to prolong the health of the articular surface.

CONCLUSION

Newer techniques such as autologous chondrocyte implantation and OCAs may safely produce encouraging outcomes in joint preservation.

Meniscal transplantation: procedures, outcomes, and rehabilitation

Meniscal allograft transplantation (MAT) is a possible treatment option for patients with joint pain after meniscectomy. It is necessary that the joint be aligned and stable. Current evidence shows that MAT improves pain and mechanical function in the mid to long term with patients reporting significantly improved outcomes at up to 15 years following surgery. Studies on survivorship showed up to 76% graft survival at 10 years. Recent studies have suggested a chondroprotective effect, but there is, at present, no evidence to support MAT in the prevention of osteoarthritis. This review article reported the current evidence for MAT showing support for fresh frozen, nonirradiated allografts. However, further research is required to determine the ideal indications for MAT, the optimal graft fixation method, and the safest rehabilitation protocol.

Knee Menisci

The menisci of the knees are semicircular fibrocartilaginous structures consisting of a hydrophilic extracellular matrix containing a network of collagen fibers, glycoproteins, and proteoglycans maintained by a cellular component. The menisci are responsible for more than 50% of load transmission across the knee and increase joint congruity thereby also aiding in fluid film lubrication of the joint. In the United Kingdom, meniscal tears are the most common form of intra-articular knee injury and one of the commonest indications for orthopedic intervention. The management of these injuries is dependent on the location within the meniscus (relative to peripheral blood supply) and the pattern of tear. Removal of meniscus is known to place the knee at increased risk of osteoarthritis; therefore repair of meniscal tears is preferable. However, a significant proportion of tears are irreparable and can only be treated by partial or even complete meniscectomy. More recent studies have shown encouraging results with meniscal replacement in this situation, though further work is required in this area.

Which Are the Most Reliable Methods of Predicting the Meniscal Size for Transplantation?

BACKGROUND

Although the size of the meniscal allograft is crucial during meniscal transplantation, the accuracy of meniscal measurement methods is still under debate. A number of methods based on radiographic and magnetic resonance imaging (MRI) data as well as on anthropometric data have been proposed, but their reproducibility and reliability are still unclear.

PURPOSE

To compare meniscal length and width as measured by different techniques (anthropometric and plain radiographic) to establish which of these 2 methods is more reliable and cost-effective for determining the meniscal size in comparison to MRI.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 2.

METHODS

The MRI scans and plain radiographic films of 22 patients (44 knees) from a single institution were studied. The width and length of the medial and lateral menisci were measured using specific techniques. Data on sex, age, body weight, and height were used to develop a regression formula for meniscal measurements (comparing both imaging methods) to establish meniscal dimensions. Data validation was achieved using the Pearson correlation, the intraclass correlation coefficient, and the Wilcoxon nonparametric test for all variables, with a significance level established at 95%. Accuracy was established as a 10% measure discrepancy from the gold standard (MRI) and was considered an average between the right and left knees.

RESULTS

No statistically significant difference was observed between the right and left knees on radiographic and MRI measurements. The Pollard technique of radiographic measurement overestimated the width of the lateral meniscus when compared with anthropometric measurements (P < .001), considering MRI as the gold standard. The same was observed for MRI measurements of the length of the lateral meniscus in which not only anthropometric but also plain radiographic measurements using the Yoon technique were significantly smaller than those values found with the Pollard technique (P < .001). The anthropometric method underestimated the width and length of the medial meniscus with an accuracy of 68.2% and 63.6%, respectively. The radiographic method was comparable with MRI in establishing all medial meniscal measurements with an accuracy of 93.2% for length and 77.3% for width.

CONCLUSION

Some viable alternatives to MRI have been suggested. For the lateral meniscus, anthropometric data are an alternative for width, and the Yoon method can be used to assess length. For the medial meniscus, the Pollard method is considered a satisfactory alternative. This study emphasized the importance of measuring the width and length of the meniscus independently during preoperative sizing for a meniscal allograft transplantation procedure. Using MRI as a gold standard, the study also proposed other less costly and satisfactory methods of obtaining such measurements.

Long-term Survivorship and Function of Meniscus Transplantation

BACKGROUND

Clinical outcomes and survivorship of meniscus transplants remain unclear, especially when magnetic resonance imaging (MRI) and weightbearing radiographic findings are included as endpoints. Many studies calculate survivorship based only on subsequent operative procedures.

PURPOSE

We prospectively determined long-term survivorship and functional outcomes of 72 consecutive meniscus transplants. The effects of articular cartilage damage, concurrent osteochondral autograft transfer (20 knees), patient age, and tibiofemoral compartment were evaluated.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

The long-term function and survival rates of 69 of 72 consecutive medial and lateral bone-meniscus-bone transplants (96% follow-up) were determined. Survival endpoints of reoperations, MRI failure (grade 3 signal intensity, extrusion >50% of meniscal width), meniscal tear on examination, and radiographic loss of joint space provided a worst-case outcome. Long-term functional analysis was performed in 58 transplants a mean of 11.9 ± 3.2 years postoperatively. The Cincinnati and International Knee Documentation Committee rating systems were used to evaluate outcomes.

RESULTS

For all transplants, the estimated probability of survival was 85% at 2 years, 77% at 5 years, 69% at 7 years, 45% at 10 years, and 19% at 15 years. There were significant improvements for pain, swelling, walking, stair climbing, and patient knee rating (P < .05). Further surgery was performed in 37 cases. Knees that had concurrent osteochondral autograft transfer had significantly lower survival rates beginning at the seventh postoperative year; however, there was no significant difference in the long-term symptom, function, and patient perception scores between these knees and the rest of the cohort. The factors of articular cartilage damage (grade 2B/3 vs none), patient age (<30 years vs 30-49 years), and tibiofemoral compartment (medial vs lateral) had no significant effect on the survival, symptom, or functional analyses.

CONCLUSION

A survival analysis that includes reoperations, MRI, radiographs, and a comprehensive examination provides a worst-case but realistic analysis of transplant function. Many patients experienced a short- and long-term benefit of reduced symptoms and improved function. However, meniscus transplants undergo a deleterious remodeling process and eventually fail. Patients should be advised that the procedure is not curative in the long term, and additional surgery will likely be required.

Advances in combining gene therapy with cell and tissue engineering-based approaches to enhance healing of the meniscus

Meniscal lesions are common problems in orthopaedic surgery and sports medicine, and injury or loss of the meniscus accelerates the onset of knee osteoarthritis (OA). Despite a variety of therapeutic options in the clinics, there is a critical need for improved treatments to enhance meniscal repair. In this regard, combining gene-, cell-, and tissue engineering-based approaches is an attractive strategy to generate novel, effective therapies to treat meniscal lesions. In the present work, we provide an overview of the tools currently available to improve meniscal repair and discuss the progress and remaining challenges for potential future translation in patients.

Societal and Economic Effect of Meniscus Scaffold Procedures for Irreparable Meniscus Injuries

BACKGROUND

Meniscus scaffolds are currently evaluated clinically for their efficacy in preventing the development of osteoarthritis as well as for their efficacy in treating patients with chronic symptoms. Procedural costs, therapeutic consequences, clinical efficacy, and future events should all be considered to maximize the monetary value of this intervention.

PURPOSE

To examine the socioeconomic effect of treating patients with irreparable medial meniscus injuries with a meniscus scaffold.

STUDY DESIGN

Economic and decision analysis; Level of evidence, 2.

METHODS

Two Markov simulation models for patients with an irreparable medial meniscus injury were developed. Model 1 was used to investigate the lifetime cost-effectiveness of a meniscus scaffold compared with standard partial meniscectomy by the possibility of preventing the development of osteoarthritis. Model 2 was used to investigate the short-term (5-year) cost-effectiveness of a meniscus scaffold compared with standard partial meniscectomy by alleviating clinical symptoms, specifically in chronic patients with previous meniscus surgery. For both models, probabilistic Monte Carlo simulations were applied. Treatment effectiveness was expressed as quality-adjusted life-years (QALYs), while costs (estimated in euros) were assessed from a societal perspective. We assumed €20,000 as a reference value for the willingness to pay per QALY. Next, comprehensive sensitivity analyses were performed to identify the most influential variables on the cost-effectiveness of meniscus scaffolds.

RESULTS

Model 1 demonstrated an incremental cost-effectiveness ratio of a meniscus scaffold treatment of €54,463 per QALY (€5991/0.112). A threshold analysis demonstrated that a meniscus scaffold should offer a relative risk reduction of at least 0.34 to become cost-effective, assuming a willingness to pay of €20,000. Decreasing the costs of the meniscus scaffold procedure by 33% (€10,160 instead of €15,233; an absolute change of €5073) resulted in an incremental cost-effectiveness ratio of €7876 per QALY. Model 2 demonstrated an incremental cost-effectiveness ratio of a meniscus scaffold treatment of €297,727 per QALY (€9825/0.033). On the basis of the current efficacy data, a meniscus scaffold provides a relative risk reduction of "limited benefit" postoperatively of 0.37 compared with standard treatment. A threshold analysis revealed that assuming a willingness to pay of €20,000, a meniscus scaffold would not be cost-effective within a period of 5 years. Most influential variables on the cost-effectiveness of meniscus scaffolds were the cost of the scaffold procedure, cost associated with osteoarthritis, and quality of life before and after the scaffold procedure.

CONCLUSION

Results of the current health technology assessment emphasize that the monetary value of meniscus scaffold procedures is very much dependent on a number of influential variables. Therefore, before implementing the technology in the health care system, it is important to critically assess these variables in a relevant context. The models can be improved as additional clinical data regarding the efficacy of the meniscus scaffold become available.

Return to play after all-inside meniscal repair in competitive football players: a minimum 5-year follow-up

PURPOSE

The purpose of this study was to report the mid-to-long-term return to sports after all-inside meniscal repair in competitive football players.

METHODS

All football players undergoing all-inside meniscal repair with a minimum Tegner activity score of 9 and minimum follow-up of 5 years were eligible for inclusion. Patients were excluded if: (a) they had ipsilateral or contralateral: meniscectomy, posterior cruciate ligament tear, multi-ligament knee injuries, osteotomies, or meniscal transplant (b) they had meniscal tears in the anterior horn, and (c) they had bucket-handle tears. All patients included were contacted by phone and asked for current sport status or Tegner score. Preoperative Tegner scores were collected from the medical charts.

RESULTS

All patients (n = 29) were men with a median (range) age of 27 (18-37) years and a follow-up of 6 (5-8) years. All meniscal injuries were complete and longitudinal tears. The median preinjury Tegner activity score was 9 (range 9-10). Two patients required revision arthroscopy (6.7 %) with partial meniscectomy before being able to return to competitive football due to suture failure. Twenty-six patients (89.6 %) returned to the same level of competition after recovering from surgery. At the last follow-up, 13 patients (45 %) were able to continue playing football at any level, and 8 (28 %) of them were able to return to the same pre-injury competitive level. The main reasons for the decreased level of activity (from competitive to recreational) or to give up football were job-related or changes in their personal life situation, but were not related to knee or meniscal disorders. Fourteen patients underwent meniscal repair alone, whereas 15 patients had an associated ACL reconstruction procedure. There were no significant differences in the collected variables between both subgroups.

CONCLUSIONS

All-inside meniscal repair allows for excellent results with regard to return-to-play rates in competitive football. However, only half of the patients are still playing football in the mid-to-long-term follow-up, although reasons to give up football are not related to knee or meniscal disorders.

LEVEL OF EVIDENCE

Case series, Level-IV.

Meniscal Allograft Transplantation in the Adolescent Population

PURPOSE

To report the results of meniscal allograft transplantation (MAT) with minimum 2-year follow-up in an active adolescent population.

METHODS

After institutional review board approval, all patients aged 16 years or younger who underwent MAT and had more than 2 years' clinical follow-up were identified from a prospectively collected database. Demographic data were collected and summary statistics calculated. Functional outcome scores were collected preoperatively and at 6 months, 1 year, 2 years, and final follow-up. Differences between scores at each time point were calculated using a mixed-model repeated-measures analysis of variance. All prior procedures and reoperations were documented.

RESULTS

Thirty-seven MAT procedures were performed in 36 children (84% lateral and 16% medial). For 32 of these procedures (86%), the patients met the inclusion criteria with minimum 2-year follow-up. The mean age was 15.4 ± 1.04 years (range, 13 to 16 years). All patients had undergone prior knee surgery. Of the 32 patients, 23 (72%) were girls and 9 (28%) were boys. Eleven patients had open physes. Forty-eight percent of patients underwent concomitant procedures, mainly for chondral defects. The mean length of clinical follow-up was 7.2 ± 3.2 years (range, 2 to 15 years). MAT resulted in significant improvements in the Knee Injury and Osteoarthritis Outcome Score, Lysholm score, International Knee Documentation Committee subjective score, Western Ontario and McMaster Universities Osteoarthritis Index pain score, Western Ontario and McMaster Universities Osteoarthritis Index function score, and Short Form 12 physical score. After MAT, 7 patients (22%) underwent 8 surgical procedures, most of which were for chondral disease. The meniscal reoperation rate was 6%. No revision MAT procedures were required. No angular deformities or limb-length inequalities were reported.

CONCLUSIONS

MAT resulted in predictable improvements in functional outcomes in the adolescent population. The meniscal reoperation rate was low (6%), no revision MAT procedures were required, and no growth complications were reported. Chondral disease remains the primary reason for reoperation after MAT.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Management of knee articular cartilage injuries in athletes: chondroprotection, chondrofacilitation, and resurfacing

Articular cartilage defects of the knee are common among athletes where the physical demands of sport result in significant stresses on joints. Chondral defects are associated with pain and functional impairment that limit sporting participation and may progress to joint degeneration and frank arthritis. Management of established chondral lesions aims to allow athletes to return to high-impact sports and can be considered in terms of protection of existing cartilage, chondrofacilitation, and resurfacing. Repaired and regenerated cartilage must closely resemble and function like normal hyaline cartilage, and this ability may be the most significant factor for the return to sport. Based on our experiences and the available literature, we outline how athletes can best protect their cartilage, how physicians can facilitate intrinsic repair of established lesions, and which methods of cartilage restoration or resurfacing should be used in different situations.

LEVEL OF EVIDENCE

IV.

Proper Cartilage Status for Meniscal Allograft Transplantation Cannot Be Accurately Determined by Patient Symptoms

BACKGROUND

Candidates for meniscal allograft transplantation (MAT) often already have a significant cartilage lesion when they present with a symptomatic knee. However, the level of symptoms required for MAT to be performed is poorly defined, leading to difficulties in selecting patients and the potential for further cartilage loss.

PURPOSE

To evaluate if various clinical evaluation scores reflect the articular cartilage status of the lateral compartment preoperatively in symptomatic, lateral meniscus-deficient knees.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 113 consecutive patients who underwent lateral MAT were reviewed. All patients were preoperatively assessed by the most common patient-reported outcome measures (PROMs), including the visual analog scale (VAS) for pain, Lysholm knee scale, International Knee Documentation Committee (IKDC) subjective form, and Tegner activity scale. The maximum grade from the International Cartilage Repair Society (ICRS) scale on either femoral or tibial articular cartilage was used for a correlation analysis between PROMs and ICRS grades and a comparison of PROMs between patients with low-grade (ICRS grade ≤2) and high-grade (ICRS grade 3 or 4) cartilage degeneration.

RESULTS

More than half of the patients had high-grade cartilage degeneration, even though their mean VAS pain score was low (3.1 ± 1.3). There were no significant relationships between ICRS grades and PROMs, except for the IKDC subjective score, which was weakly associated with the ICRS grade (Spearman ρ test, 2-sided, ρ = -.200, P = .034). When comparing patients with low-grade versus high-grade cartilage degeneration, there were no differences in PROMs except for the Lysholm score (67.8 ± 14.7 vs 62.3 ± 13.9, respectively; P = .044). Notably, 37 of 58 patients (63.8%) with high-grade chondral lesions only felt pain during severe exertion.

CONCLUSION

Mild or tolerable symptoms did not necessarily mean that articular cartilage was well preserved in patients undergoing MAT. The study findings suggest a need for close observation and greater caution concerning possible chondral damage in the treatment of meniscus-deficient knees.

The Meniscus-Deficient Knee: Biomechanics, Evaluation, and Treatment Options

Meniscal tears are the most common knee injury, and partial meniscectomies are the most common orthopaedic surgical procedure. The injured meniscus has an impaired ability to distribute load and resist tibial translation. Partial or complete loss of the meniscus promotes early development of chondromalacia and osteoarthritis. The primary goal of treatment for meniscus-deficient knees is to provide symptomatic relief, ideally to delay advanced joint space narrowing, and ultimately, joint replacement. Surgical treatments, including meniscal allograft transplantation (MAT), high tibial osteotomy (HTO), and distal femoral osteotomy (DFO), are options that attempt to decrease the loads on the articular cartilage of the meniscus-deficient compartment by replacing meniscal tissue or altering joint alignment. Clinical and biomechanical studies have reported promising outcomes for MAT, HTO, and DFO in the postmeniscectomized knee. These procedures can be performed alone or in conjunction with ligament reconstruction or chondral procedures (reparative, restorative, or reconstructive) to optimize stability and longevity of the knee. Complications can include fracture, nonunion, patella baja, compartment syndrome, infection, and deep venous thrombosis. MAT, HTO, and DFO are effective options for young patients suffering from pain and functional limitations secondary to meniscal deficiency.

Biological augmentation and tissue engineering approaches in meniscus surgery

PURPOSE

The purpose of this review was to evaluate the role of biological augmentation and tissue engineering strategies in meniscus surgery. Although clinical (human), preclinical (animal), and in vitro tissue engineering studies are included here, we have placed additional focus on addressing preclinical and clinical studies reported during the 5-year period used in this review in a systematic fashion while also providing a summary review of some important in vitro tissue engineering findings in the field over the past decade.

METHODS

A search was performed on PubMed for original works published from 2009 to March 31, 2014 using the term "meniscus" with all the following terms: "scaffolds," "constructs," "cells," "growth factors," "implant," "tissue engineering," and "regenerative medicine." Inclusion criteria were the following: English-language articles and original clinical, preclinical (in vivo), and in vitro studies of tissue engineering and regenerative medicine application in knee meniscus lesions published from 2009 to March 31, 2014.

RESULTS

Three clinical studies and 18 preclinical studies were identified along with 68 tissue engineering in vitro studies. These reports show the increasing promise of biological augmentation and tissue engineering strategies in meniscus surgery. The role of stem cell and growth factor therapy appears to be particularly useful. A review of in vitro tissue engineering studies found a large number of scaffold types to be of promise for meniscus replacement. Limitations include a relatively low number of clinical or preclinical in vivo studies, in addition to the fact there is as yet no report in the literature of a tissue-engineered meniscus construct used clinically. Neither does the literature provide clarity on the optimal meniscus scaffold type or biological augmentation with which meniscus repair or replacement would be best addressed in the future. There is increasing focus on the role of mechanobiology and biomechanical and biochemical cues in this process, however, and it is hoped that this may lead to improvements in this strategy.

CONCLUSIONS

There appears to be significant potential for biological augmentation and tissue engineering strategies in meniscus surgery to enhance options for repair and replacement. However, there are still relatively few clinical studies being reported in this regard. There is a strong need for improved translational activities and infrastructure to link the large amounts of in vitro and preclinical biological and tissue engineering data to clinical application.

LEVEL OF EVIDENCE

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

3D printing of an extremely tough hydrogel

A super tough hydrogel with tunable mechanical properties was 3D printed.

Egg shell membrane – a potential natural scaffold for human meniscal tissue engineering: an in vitro study

Enhanced human primary meniscal cell proliferation in autoclaved egg shell membrane.

Updates in biological therapies for knee injuries: menisci

The preservation of meniscal tissue is paramount for long-term joint function, especially in younger patients who are athletically active. Many studies have reported encouraging results following the repair of meniscus tears, including both simple longitudinal tears located in the periphery and complex multiplanar tears that extend into the central third avascular region. However, most types of meniscal lesions are managed with a partial meniscectomy. Options to restore the meniscus range from an allograft transplantation to the use of synthetic and biological technologies. Recent studies have demonstrated good long-term outcomes with meniscal allograft transplantation, although the indications and techniques continue to evolve, and the long-term chondroprotective potential of this approach has yet to be determined. Several synthetic implants, most of which are approved in the European market, have shown some promise for replacing part of or the entire meniscus, including collagen meniscal implants, hydrogels, and polymer scaffolds. Currently, there is no ideal implant generated by means of tissue engineering. However, meniscus tissue engineering is a fast developing field that promises to develop an implant that mimics the histologic and biomechanical properties of a native meniscus.