Biomechanical considerations are crucial for the success of tendon and meniscus allograft integration—a systematic review

Abstract

Purpose This systematic review intends to give an overview of the current knowledge on how allografts used for the reconstruction of cruciate ligaments and menisci are integrated and specifically perform regarding their biomechanical function. Methods Two reviewers reviewed the PubMed and Central Cochrane library with focus on the biomechanical integration of tendon ligament and meniscus allografts. The literature search was conducted in accordance with the PRISMA statement for reporting systematic reviews and meta‐analyses. Results The analysed literature on tendon allografts shows that they are more vulnerable to overstretching in the phase of degradation compared to autografts as the revascularization process starts later and takes longer. Therefore, to avoid excessive graft loads, allografts for cruciate ligament replacement should be selected that exhibit much higher failure loads than the native ligaments to counteract the detrimental effect of degradation. Further, placement techniques should be considered that result in a minimum of strain differences during knee joint motion, which is best achieved by near‐isometric placement. The most important biomechanical parameters for meniscus allograft transplantation are secure fixation and proper graft sizing. Allograft attachment by bone plugs or by a bone block is superior to circumferential suturing and enables the allograft to restore the chondroprotective biomechanical function. Graft sizing is also of major relevance, because too small grafts are not able to compensate the knee joint incongruity and too large grafts may fail due to extrusion. Only adequate sizing and fixation together can lead to a biomechanically functioning allograft. The objective assessment of the biomechanical quality of allografts in a clinical setting is challenging, but would be highly desirable for monitoring the remodelling and incorporation process. Conclusions Currently, indicators like ap‐stability after ACL reconstruction or meniscal extrusion represent only indirect measures for biomechanical graft integration. These parameters are at best clinical indicators of allograft function, but the overall integration properties comprising e.g. fixation and graft stiffness remain unknown. Therefore, future research should e.g. focus on advanced imaging techniques or other non‐invasive methods allowing for in vivo assessment of biomechanical allograft properties.

Biomechanical Comparison of Meniscal Allograft Root Fixation Techniques: Anterograde Interference Bone Plug Fixation Yields Favorable Results Compared to Transosseous Suture Fixation Alone

“…7,8,21,22 Displacement of the meniscus was recorded at the actuator of the tensile testing machine at the conclusion of cycles 1, 100, 500, and 1000, similar to previous studies evaluating displacement in meniscus tissue. 7,8 On completion of the cyclic loading protocol, the menisci were pulled to failure at a rate of 0.5 mm/s. 22 Mode of failure was recorded as suture breakage, bone block failure, bone block slippage, or meniscal tissue failure.…”

An Up-to-Date Review of the Meniscus Literature: A Systematic Summary of Systematic Reviews and Meta-analyses

“…Seitz and Durselen 120 found that the most important biomechanical properties for MAT were secure fixation and proper graft sizing. Bone plugs or bone blocks for allograft attachment were superior to circumferential suturing and were associated with chondroprotective effects.…”

Comparison of meniscal allograft transplantation techniques using a preclinical canine model

“…In addition, this technique addresses key sizing and fixation factors that have been reported to directly affect meniscal function, chondroprotection, and transplant survival. [45][46][47] Finally assessments, which is thought to be related to the less invasive nature of meniscus-only techniques. However, at the 6-month study endpoint when healing and graft integration had occurred, the menisco-tibial MAT group was associated with superior outcomes, most likely due to preserved meniscal integrity and function, treatment of tibial articular cartilage pathology, and avoidance of shrinkage, extrusion, failure, or progression of joint pathology.…”

“…Fresh meniscal‐osteochondral allograft transplantation with menisco‐tibial ligament preservation allowed for resurfacing of affected tibial cartilage with intact hyaline cartilage. In addition, this technique addresses key sizing and fixation factors that have been reported to directly affect meniscal function, chondroprotection, and transplant survival 45‐47 . Finally, by replacing the damaged tibial plateau in conjunction with MAT, whole‐joint pathology is more completely addressed, which in turn mitigates the progression of cartilage damage, degradation and loss, and the associated failure of MAT.…”