Meniscal transplantation: procedures, outcomes, and rehabilitation

A decellularized and sterilized human meniscus allograft for off-the-shelf meniscus replacement

PURPOSE

Meniscus tears are one of the most frequent orthopedic knee injuries, which are currently often treated performing meniscectomy. Clinical concerns comprise progressive degeneration of the meniscus tissue, a change in knee biomechanics, and an early onset of osteoarthritis. To overcome these problems, meniscal transplant surgery can be performed. However, adequate meniscal replacements remain to be a great challenge. In this research, we propose the use of a decellularized and sterilized human meniscus allograft as meniscal replacement.

METHODS

Human menisci were subjected to a decellularization protocol combined with sterilization using supercritical carbon dioxide (scCO₂). The decellularization efficiency of human meniscus tissue was evaluated via DNA quantification and Hematoxylin & Eosin (H&E) and DAPI staining. The mechanical properties of native, decellularized, and decellularized + sterilized meniscus tissue were evaluated, and its composition was determined via collagen and glycosaminoglycan (GAG) quantification, and a collagen and GAG stain. Additionally, cytocompatibility was determined in vitro.

RESULTS

Human menisci were decellularized to DNA levels of ~ 20 ng/mg of tissue dry weight. The mechanical properties and composition of human meniscus were not significantly affected by decellularization and sterilization. Histologically, the decellularized and sterilized meniscus tissue had maintained its collagen and glycosaminoglycan structure and distribution. Besides, the processed tissues were not cytotoxic to seeded human dermal fibroblasts in vitro.

CONCLUSIONS

Human meniscus tissue was successfully decellularized, while maintaining biomechanical, structural, and compositional properties, without signs of in vitro cytotoxicity. The ease at which human meniscus tissue can be efficiently decellularized, while maintaining its native properties, paves the way towards clinical use.

Autologous semitendinosus tendon graft could function as a meniscal transplant

PURPOSE

Meniscectomy results in poor knee function and increased risk for osteoarthritis. Meniscal allograft transplantation is not widely used due to costs and availability. The semitendinosus tendon (ST) has the potential to remodel and revascularize in an intraarticular environment, such as ACL reconstruction. The objective for this pilot study was to investigate whether the ST graft could function as a meniscal transplant.

METHODS

The ST was doubled and sutured with running sutures and pull-out sutures in each end. Bone tunnels were used for root anchorage and the graft was sutured with allinside, inside-out and outside-in technique. The pull-out sutures were fixed over a button. Partial weight bearing was allowed with limited range of motion in a brace for the first 6 weeks. Evaluation was assessed using clinical examination, radiology and patient reported outcome.

RESULTS

A total of seven patients have been included between January 2018 and June 2020. Six medial transplants and one lateral transplant were performed. Mean age was 29 years. Four patients had completed the 12-month follow-up. Improvements were noted for IKDC Global Score, KOOS pain subscale and Lysholm. MRI indicated that the transplant become more wedge-like with visible roots and minor protrusion.

CONCLUSIONS

Even though this is primarily a technical report the follow-up data indicate that the transplant survives and adapts in shape and capabilities to an original meniscus. There were no adverse events and the patients seem to improve in terms of pain and quality of life.

Effects of Compliance With Procedure-Specific Postoperative Rehabilitation Protocols on Initial Outcomes After Osteochondral and Meniscal Allograft Transplantation in the Knee

Background:

Osteochondral and meniscal allograft transplantation have been performed in the knee for more than 40 years, with the number of patients treated each year growing as allograft quantity and quality increase. To date, the effects of postoperative management on outcomes after these procedures have received relatively little focus in the peer-reviewed literature.

Hypothesis:

Compliance with the recommended postoperative management protocol will be associated with significantly higher initial success and significantly lower revision and failure rates for patients undergoing osteochondral and/or meniscal allograft transplantation in the knee.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Patients were prospectively enrolled into a dedicated registry designed to follow outcomes after osteochondral and/or meniscal allograft transplantation. Patients were included when at least 1 year of follow-up data were available, including data on complications and reoperations, patient-reported outcome measures, compliance with rehabilitation, revisions, or failures, based on the electronic medical record and communication logs with patients’ outpatient physical therapists.

Results:

For patients meeting the inclusion criteria (N = 162), compliance with the prescribed procedure-specific postoperative management protocol was associated with significantly higher 1- to 3-year success and significantly lower revision and failure rates. Specifically, patients who were compliant were 6.3 times less likely to need allograft revision or total knee arthroplasty and 7.5 times more likely to have a successful outcome at 1 to 3 years after osteochondral and/or meniscal allograft transplantation. In addition to noncompliance, older patient age and higher body mass index were associated with inferior short-term outcomes in this cohort.

Conclusion:

These data suggest that compliance with procedure-specific postoperative rehabilitation protocols is associated with higher success, lower revision, and lower failure rates for patients undergoing osteochondral and meniscal allograft transplantation. Given these results showing the importance of these modifiable risk factors, our center has devoted resources to preoperative patient assessment and communication to provide education, set appropriate expectations, identify and address modifiable risk factors, impediments, and noncompliance, and monitor and adjust postoperative care as indicated.

The biomechanical role of meniscal allograft transplantation and preliminary in-vivo kinematic evaluation

Background

Meniscus allograft transplantation (MAT) is a surgical procedure performed in patients complaining post-meniscectomy syndrome. Although the effectiveness of MAT on knee stability has been already demonstrated in cadaveric studies, its biomechanical role has been poorly evaluated in-vivo.

Methods

A narrative review of the biomechanical effect of meniscectomy and MAT was performed. Furthermore, two cases were presented, of one patient who underwent Medial MAT and Anterior Cruciate Ligament (ACL) reconstruction, and one who underwent Lateral MAT. During the surgery, knee laxity was evaluated using a surgical navigation system.

Results

AP laxity and IE rotation were reduced of 25% to 50% at both 30° and 90° of knee flexion after MAT transplantation.

Discussion

In both cases, almost all the tests performed showed a reduction of knee laxity after meniscus transplant, when compared with pre-operative knee laxity. This assessment confirms the insights of previous in-vitro studies and underline a crucial role of MAT in knee biomechanics.