Meniscal Transplantation

Courtesy Dr Frank Noyes, Dr Ashok Shyam, Ortho TV

Introduction

• Meniscus transplantation is a surgical option for selected patients who have significant symptoms following loss of the meniscus.
• The procedure is mainly considered in younger individuals who develop persistent knee pain after meniscectomy.
• Multiple graft preservation methods have been used, including cryopreserved meniscus grafts.
• Clinical studies have evaluated outcomes with long-term follow-up, including cases with additional procedures such as anterior cruciate ligament reconstruction or osteochondral grafting.

Goals of Meniscus Transplantation

• Reduction of knee pain caused by meniscal deficiency.
• Improvement in activity level and functional capacity.
• Restoration of joint stability.
• Possible protection of articular cartilage in the early postoperative period.

Clinical Observations

• Some patients who lose the meniscus develop severe joint pain, especially younger individuals.
• In contrast, certain older or highly active individuals may tolerate meniscal loss without significant symptoms.
• In symptomatic young patients, meniscus transplantation may help relieve pain and restore knee function.

Role of the Meniscus in Knee Stability

• The meniscus contributes to knee joint stability.
• It acts as a secondary restraint against anterior translation of the tibia.
• Loss of the meniscus can lead to:
  • Increased instability during clinical stability tests.
  • Changes in tibial slope mechanics.
  • Increased contact stress within the knee joint.

Indications for Meniscus Transplantation

Patients are considered suitable candidates when the following criteria are present:

• Age generally below fifty years.
• Persistent tibiofemoral joint pain after meniscectomy.
• Early cartilage degeneration may be present but without complete bone exposure.
• Normal limb alignment.
• Normal body mass index.
• Stable knee joint or correctable ligament deficiency.

In some situations, meniscus transplantation may be combined with:

• Osteochondral autograft transplantation procedures.
• Matrix-induced cartilage repair techniques.
• Reconstruction of the anterior cruciate ligament.

Contraindications

Meniscus transplantation is generally avoided in the presence of:

• Advanced osteoarthritis.
• Severe malalignment of the lower limb.
• Large areas of exposed subchondral bone.
• Instability that cannot be corrected.
• Obesity.
• Severe joint fibrosis or stiffness.

Surgical Techniques

Lateral Meniscus Transplantation

• The keyhole technique is commonly used.
• This method preserves the native attachment of the meniscal roots.
• A bone bridge containing both roots is inserted into a prepared slot in the tibia.
• The graft is then secured with sutures similar to a bucket-handle meniscus repair.

Medial Meniscus Transplantation

• Often performed using two bone plug fixation techniques.
• In selected cases, a slot technique may be used.
• Care is required because the surgical field is close to the anterior cruciate ligament.

Importance of Accurate Graft Placement

• Correct measurement of the graft using templates is essential.
• Improper placement may result in meniscal extrusion, where the graft shifts outward from the joint.
• Extrusion of more than three to four millimetres significantly reduces graft effectiveness.
• Careful surgical technique and suturing are necessary to minimize this complication.

Imaging Assessment

• Magnetic resonance imaging is frequently used to evaluate graft positioning and integrity.
• Standing magnetic resonance imaging can provide additional information regarding graft extrusion under load.
• Imaging helps assess healing and detect early graft degeneration.

Clinical Outcomes

Pain Relief

• Most patients experience significant improvement in tibiofemoral joint pain after transplantation.
• Many individuals with severe preoperative pain report only mild discomfort after surgery.

Functional Improvement

• A large proportion of patients return to recreational activities.
• Light sports participation is often possible following rehabilitation.

Return to Activity

• Studies show that approximately seventy to ninety percent of patients resume light recreational sports.
• High-level competitive sports participation is generally not recommended.

Imaging Findings After Surgery

Magnetic resonance imaging may reveal structural changes in the transplanted meniscus over time:

• Around half of grafts may appear relatively normal on imaging.
• Some grafts demonstrate:
  • Loss of height
  • Flattening
  • Partial extrusion
• A proportion of grafts eventually fail or degenerate.

Biological Limitations

• The transplanted meniscus has limited biological activity.
• Bone attachments and peripheral tissue may heal successfully.
• However, the central portion of the graft remains relatively inert.
• Over time, the graft may be gradually replaced by scar tissue.
• This replacement reduces the ability of the meniscus to distribute load across the joint.

Long-Term Outcomes

• Clinical follow-up studies extending beyond ten years have shown that:
  • Approximately sixty percent of patients remain clinically satisfied.
  • Imaging studies may demonstrate functional graft survival in about half of cases.
• Gradual deterioration of the graft may occur after ten years.

Revision Procedures

• In selected young patients, revision meniscus transplantation may be considered if symptoms recur.
• These procedures are usually performed in individuals with persistent symptoms and otherwise healthy knee joints.

Timing of Surgery

• Meniscus transplantation is not intended as a preventive procedure.
• However, performing the surgery before severe joint degeneration develops may improve outcomes.
• Early intervention in symptomatic patients may help delay joint deterioration.

Important Considerations for Surgical Planning

• Proper patient selection is essential.
• Limb alignment must be corrected when abnormal.
• Secure fixation of the meniscal roots is critical.
• Magnetic resonance imaging should be used to monitor graft healing and position.

Summary

• Meniscus transplantation is a valuable treatment for symptomatic meniscal deficiency in selected patients.
• The procedure can reduce knee pain, improve activity level, and temporarily enhance joint stability.
• Benefits are generally most noticeable in the short to medium term.
• Gradual degeneration of the graft may occur over time, particularly beyond ten years.
• Careful surgical technique and appropriate patient selection remain key factors in achieving successful outcomes.