MENISCAL RECONSTRUCTION –

SUBSTITUTES

DR.RAJAT JANGIRLigament and Joints Clinic

JAIPUR

• Human meniscus is a highly complex tissue with very specific biological and biomechanical properties, most of which are still not well understood

REPLACE

• Natural tissues as meniscus allografts, quadriceps tendon, Hoffa fat pad

• Tissue engineering scaffolds, cells, growth factors, or combination

• Prosthetic devices

Substitution

• By a meniscus allograft has been accepted as a viable therapeutic option for (sub)total meniscectomized knee

• For partial defects is an ongoing field of research and has attracted greater interest in recent years.

APPROACHES

• Acellular scaffolds- scaffolds allow the human body to regrow tissue

• Accelerate healing, cells and/or growth factors or a combination of these could be added to the acellular scaffold (biomimetic properties)

• Possible primary cell sources are bone marrow-derived mesenchymal stem cells (BMSC), local progenitor cells or differentiated meniscus and cartilage cells.

• Autologous growth factors in the form of a platelet-rich plasma

• Isolated recombinant growth factors is still highly controversial and faced with regulatory constraints

• TGF-b1, PDGF bb, IGF-I, FGF2, BMP-6

PROSTHETIC MENISCUS DEVICE

• Advantage it bypasses the intrinsic variability and time consumption of the biological approach, i.e., the patient does not need to heal but receives a prosthetic implant with specific biomechanical properties

• Difficulties in designing and manufacturing such implants is the biomechanical behaviour of the meniscus and its fixation to the capsule and bone.

• Fixation mode that ensures the stability of the meniscus.

Menaflex (TM) Collagen Meniscus Implant

• Tissue engineering techniques and collagen matrix technology

• Supports ingrowth of new tissue and eventual regeneration of the lost meniscus

Hypothesis

• Meniscus has the intrinsic ability to regenerate, provided that the biological environment is suitable for regeneration

• Tissue-engineered extracellular matrix scaffold can be used to support and guide meniscus regeneration

7 Months-solid structure due to the new tissue formation

18 Months: new collagen fibrils are

smaller and more uniform than those in the

original implant

5 years: Compact and Dense

EVIDANCE

• Animal-Human Studies• Reconstruct irreparable or lost meniscus tissue

in patients with a meniscus injury and improve the functional outcomes of its recipients

• Rodkey WG, et al (2008)-Comparison of the collagen meniscus implant to partial meniscectomy: a prospective RCT. JBJS Am 90:1413–1426 LEVEL 1

• Steadman JR, Rodkey WG (2005) Tissue-engineered colla- gen meniscus implants: 5- to 6-year feasibility study results. Arthroscopy 21:515–525

• Zaffagnini S, Giordano G, Vascellari A et al (2007) Arthroscopic collagen meniscus implant results at 6 to 8 years follow up. Knee Surg Sports Traumatol Arthrosc 15:175–183

Technique

Fixation

CMI

• Newly formed meniscus was observed in over two thirds of cases.

• Selecting the suitable candidate stable and well-alignedTechnically, a secure intraarticular attachment

is probably the most critical factor (FIXATION)

ActifitPolyurethane Meniscus Implant

• Highly interconnected porous synthetic material enabling tissue ingrowth

• Aliphatic polyurethane,

• transformation into meniscus-like tissue takes place as the implant slowly degrades

two configurations, medial and lateral

• Two components, polyester (soft) and polyurethane (stiff)

• Soft segment 80% is a biodegradable polyester

• Semidegradable, stiff segments 20% are of uniform size and provide mechanical strength.

• Degradation of SOFT segments is expected to take 4–6 years.

PREREQUISITES

• Intact meniscal rim and sufficient tissue present both in the anterior and the posterior horns to allow for secure fixation.

• Well-aligned stable knee, • BMI) below 35 • Free from systemic disease or infection • Cartilage damage (ICRS)<Grade 3

• Importantly, no safety issues related to the scaffold, including cartilage damage or inflammatory reactions

• Performance data showed successful tissue ingrowth. • In conclusion, the 12-month clinical results are

comparable to those reported following partial meniscectomy; however, the ActifitTM scaffold has the added benefit of promoting meniscal tissue regeneration.

EVIDANCE• Welsing RT, (2008) Effect on tissue dif- ferentiation and

articular cartilage degradation of a polymer meniscus implant: a 2-year follow-up study in dogs. AJSM 36:1978–1989

• Tienen TG, Heijkants RG, de Groot JH et al (2006) Replacement of the knee meniscus by a porous polymer implant: a study in dogs. AJSM 34:64–71

CONCLUSION,

• Different approaches currently under investigation.

• The potential patient- specific variability and time consumption are a major challenge for the biological tissue engineer,

• While for the prosthetic approach the perfect material still has to be developed.

• Maybe a combination of a prosthetic core with a bioactive surface would be the ideal implant