The role of patient characteristics and the effects of angiogenic therapies on the microvasculature of the meniscus: A systematic review

Blood Flow in the Meniscus Can Be Visualized Arthroscopically Using an Intravenous Indocyanine Green Solution Diluted 10× in a Pig Model

Purpose

To determine the optimal indocyanine green (ICG) dose required for assessing vascularity in the meniscus using ICG fluorescence-guided knee arthroscopy in a pig model.

Methods

A 3-month-old Japanese esculent female pig was used in this study. Intravenous injections of ICG (25 mg) were administered with 2.0 mL of 5×, 10×, 100×, and 1,000× diluted solutions. An additional experiment was conducted to assess the microvasculature within the meniscus considering the results of the optimal dilution setting. A radial tear was purposely induced in the middle-to-posterior section of the medial meniscus to observe vascularity in the cross-sectioned meniscus; the optimal ICG dilution was administered.

Results

No fluorescence was detected in the meniscus with solutions diluted by 1,000× and 100×. Fluorescence was visualized at the anterior portion of the synovium and the anterior cruciate ligament using ICG diluted by 10×. Diluting ICG by 5×, contrast enhancement was too intense for observation. Therefore, the 10× diluted solution was considered the optimal setting for knee arthroscopy and observation of the radial tear. No fluorescence was observed in the cross section of the medial meniscus. Arterial hemorrhage was observed by stimulating the fluorescence-dyed synovium adjacent to the tear site. Through the additional waiting time after stimulating the tear site, the hemorrhage inside the meniscus became more intense.

Conclusions

The optimal dilution and dose setting of ICG for knee arthroscopy was 10× in a 2.0-mL intravenous injection. The meniscus showed no active blood flow, even in the red-red zone. This finding might support the notion that blood flow cannot be initiated, without synovial stimulation, even in vascular areas.

Clinical Relevance

This study could determine an ICG solution suitable for ICG fluorescence-guided knee arthroscopy. This finding could be valuable in future research focusing on case-specific meniscal vascularization under arthroscopy, particularly applying these findings to human meniscal treatment.

Increased Age, Operative Time, American Society of Anesthesiologists Classification, Functional Dependency, and Comorbidity Burden Are Risk Factors for Adverse Events After Meniscectomy and Meniscus Repair: 10-Year Analysis of 64,223 Patients

PURPOSE

To use the National Surgical Quality Improvement Program (NSQIP) database to identify risk factors for 30-day adverse events and hospital readmission following isolated and unilateral meniscectomy or meniscus repair.

METHODS

A retrospective review of the NSQIP database from the years 2012 to 2021 identified all patients undergoing isolated, unilateral meniscectomy or meniscus repair. Multivariable analyses were performed for each procedure to identify patient characteristics associated with any adverse event (AAE) or unplanned hospital readmission within 30 days of surgery.

RESULTS

From 2012 to 2021, 59,450 (93%) patients underwent meniscectomy, and 4,773 (7%) patients underwent meniscus repair. Overall adverse event rate was 0.95% after meniscectomy and 1.40% after repair. Risk factors for AAE after meniscectomy included increased age (odds ratio [OR] = 1.010; P = .009), increased operative time (OR = 1.003; P = 0.011), American Society of Anesthesiologists (ASA) class IV (OR = 2.048; P = .045), functional dependency (OR = 3.527; P = .001), and current smoking (OR = 1.308; P = .018). Risk factors for AAE after meniscus repair included age (OR = 1.024; P = .016), operative time (OR = 1.004; P = .038), and bleeding disorders (OR = 7.000; P = .014). ASA class III increased risk of hospital readmission after both procedures (OR = 1.906; P = .008; OR = 4.101; P = .038), and medical comorbidities of heart failure (OR = 3.924; P = .016), hypertension (OR = 1.412; P = .011), and chronic obstructive pulmonary disease (OR = 2.350; P < .001) increased readmission risk after meniscectomy only.

CONCLUSIONS

Per analysis of the American College of Surgeons (ACS)-NSQIP database, surgical treatment of meniscal tears in the knee has been performed frequently over the past 10 years, with meniscectomies comprising over 90% of cases. Increased age and operative time were associated with a modest risk of adverse events after both meniscectomy and meniscus repair. Increased comorbidity burden, evidenced by ASA class, dependent functional status, current smoking, and systemic medical conditions, such as heart failure, hypertension, chronic obstructive pulmonary disease, and bleeding disorders, greatly increased rates of unfavorable outcomes within 30 days of meniscus surgery.

LEVEL OF EVIDENCE

Level III, retrospective prognostic comparative investigation.

Indocyanine Green Fluorescence-Guided Knee Arthroscopy: A Technical Note for Investigating the Microvasculature Around the Meniscus

Vascularity of the meniscus is the most important key to meniscal tear healing. However, blood supply to the meniscus is limited to approximately the outer 10% to 25% of the meniscus, known as the "red-red zone." The cyanine dye indocyanine green (ICG) is commonly used as a contrast imaging agent for visualizing vascularity in several medical fields. Moreover, ICG fluorescence-guided surgery is a modern trend in the field of laparoscopic surgery in which the characteristic of fluorescence enhancement under a near-infrared light is used. However, ICG fluorescence-guided knee arthroscopy findings remain unknown. In this Technical Note, the author applied ICG fluorescence-guided surgery to knee arthroscopy to evaluate blood supply to the meniscus and intra-articular apparatus. Additionally, the arthroscopic findings of ICG fluorescence-guided knee arthroscopy for degenerative tears of the medial meniscus before and after meniscal repair are presented. Through the intravenous injection of ICG solution, real-time detection of fluorescence may contribute to investigating case-specific vascularization of the meniscus during arthroscopy in the next generation.

Tough gel adhesive is an effective method for meniscal repair in a bovine cadaveric study

PURPOSE

To test tough gel adhesives to repair meniscus tears under relevant loading conditions and determine if they have adequate biomechanical properties to repair meniscus tears in a bovine cadaveric study.

METHODS

Cyclic compression tests on 24 dissected bovine knees were performed. The tough gel adhesive was used either as an adhesive patch or as a coating bonded onto commercially available surgical sutures. Forty-eight menisci were tested in this study; 24 complete radial tears and 24 bucket-handle tears. After preconditioning, the specimens underwent 100 cycles of compression, (800 N/0.5 Hz) on an Instron© machine and the size of the gaps measured. One third of the menisci were repaired with pristine sutures, one third with adhesive patches, and one third with sutures coated in adhesive gel. The size of the gaps was compared after 100 and 500 cycles of compression.

RESULTS

The mean gap measured at the tear site without treatment was 6.46 mm (± 1.41 mm) for radial tears and 1.92 mm (± 0.65 mm) for bucket-handle tears. After treatment and 500 cycles of compression, the mean gap was 1.63 mm (± 1.41 mm) for pristine sutures, 1.50 mm (± 1.16 mm) for adhesive sutures and 2.06 mm (± 1.53 mm) for adhesive gel patches. There was no significant difference between treatments regardless of the type of tear. Also, the gaps for radial tears increased significantly with the number of compression cycles applied (p > 0.001).

CONCLUSION

From a biomechanical standpoint, the tough adhesive gel patch is as effective as suturing. In addition, it would allow the repair of non-suturable tears and thus broaden the indications for meniscus repair.

LEVEL OF EVIDENCE

Controlled laboratory study.

Outside-in repair technique is effective in traumatic tears of the meniscus in active adults: a systematic review

PURPOSE

Meniscal injuries are common. Outside-in meniscal repair is one of the techniques advocated for the management of traumatic meniscal tears. This systematic review investigated the outcomes of the outside-in repair technique for the management of traumatic tears of the menisci. The outcomes of interest were to investigate whether PROMs improved and to evaluate the rate of complications.

METHODS

Following the 2020 PRISMA statement, in May 2023, PubMed, Web of Science, Google Scholar, and Embase were accessed with no time constraints. All the clinical investigations which reported data on meniscal repair using the outside-in technique were considered for inclusion. Only studies which reported data on acute traumatic meniscal tears in adults were considered. Only studies which reported a minimum of 24 months of follow-up were eligible.

RESULTS

Data from 458 patients were extracted. 34% (155 of 458) were women. 65% (297 of 458) of tears involved the medial meniscus. The mean operative time was 52.9 ± 13.6 min. Patients returned to their normal activities at 4.8 ± 0.8 months. At a mean of 67-month follow-up, all PROMs of interest improved: Tegner scale (P = 0.003), Lysholm score (P < 0.0001), International Knee Documentation Committee (P < 0.0001). 5.9% (27 of 458) of repairs were considered failures. Four of 186 (2.2%) patients experienced a re-injury, and 5 of 458 (1.1%) patients required re-operation.

CONCLUSION

Meniscal repair using the outside-in technique can be effectively performed to improve the quality of life and the activity level of patients with acute meniscal tears.

LEVEL OF EVIDENCE

Level IV.

Modification of the properties of a suture thread with a tough gel coating: A baseline ex-vivo study

The mechanical properties of sutures are important for wound closure and meniscus repair. A tough gel coating technology has been developed to modify and functionalize sutures, but its effects on suture degradation remain unexplored. Our aim is to investigate how a tough gel coating mediates the properties of the suture. The Polyglactin910 (Vicryl) suture was chosen because it is widely used, strong, easy to handle, and degradable. This study compared six pristine Vicryl sutures and six coated Vicryl sutures at 0, 2, 4, and 6 weeks. All the sutures were soaked in phosphate-buffered saline (PBS), to mimic degradation in physiological conditions, and tensile strength was tested at each time point. The pH of the soaking mediums was measured weekly and compared at 4, 5, and 6 weeks. No significant difference (p = 0.059 and p = 0.576) was found between the absolute and normalized breaking force of coated and pristine Vicryl sutures at 0, 2, 4, and 6 weeks. After 4 weeks of immersion, the soaking medium became more acidic for both suture types. The decrease in pH was less significant for coated Vicryl sutures than for pristine ones (p < 0.001) at 4, 5, and 6 weeks of immersion. Although coating does not affect the strength of Vicryl sutures soaked in PBS, it can effectively act as a buffer to the acidic environment caused by suture degradation, which could help reduce inflammation. Hydrogel coating is a promising technology to modify suture characteristics.

Knee MRI: Meniscus Roots, Ramps, Repairs, and Repercussions

Menisci play an essential role in maintaining normal pain-free function of the knee. While there are decades of MRI literature on the tears involving the meniscus body and horns, there is now a surge in knowledge regarding injuries at the meniscus roots and periphery. The authors briefly highlight new insights into meniscus anatomy and then summarize recent developments in the understanding of meniscus injuries that matter, emphasizing meniscus injuries at the root and peripheral (eg, ramp) regions that may be missed easily at MRI and arthroscopy. Root and ramp tears are important to diagnose because they may be amenable to repair. However, if these tears are left untreated, ongoing pain and accelerated cartilage degeneration may ensue. The posterior roots of the medial and lateral menisci are most commonly affected by injury, and each of these injuries is associated with distinctive clinical profiles, MRI findings, and tear patterns. Specific diagnostic pitfalls can make the roots challenging to evaluate, including MRI artifacts and anatomic variations. As with root tears, MRI interpretation and orthopedic treatment have important differences for injuries at the medial versus lateral meniscus (LM) periphery (located at or near the meniscocapsular junction). Medially, ramp lesions typically occur in the setting of an anterior cruciate ligament rupture and are generally classified into five patterns. Laterally, the meniscocapsular junction may be injured in association with tibial plateau fractures, but disruption of the popliteomeniscal fascicles may also result in a hypermobile LM. Updated knowledge of the meniscus root and ramp tears is crucial in optimizing diagnostic imaging before repair and understanding the clinical repercussions. ©RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available in the Online Learning Center.