Hi, I'm Crystal Perkins, and I'll be presenting on pediatric considerations and technical pearls in meniscus transplant. The meniscus serves a critical role in load sharing and knee stability, and meniscus deficiency results in reduced joint congruence, decreased intra-articular contact area, and increased loading pressures. There have been increasing rates of meniscal tears, which parallel the rise in adolescent ACL tears. Furthermore, isolated lateral meniscus injuries in adolescents are most commonly secondary to dysploids, and not all are salvageable. The indications for meniscus allograft transplant most commonly are functional meniscus deficiency in patients with unicompartmental pain who are under the age of 40 and have a stable or well-aligned joint. Contraindications include the asymptomatic patient, those with severe osteoarthritis, uncorrectable ligamentous instability or malalignment, inflammatory diseases, or inability to comply with recommended activity restrictions. Preoperative planning is very important, and we should never assume that meniscus deficiency occurs in an otherwise healthy knee. Long leg alignment radiographs are essential. You should consider realignment osteotomies when the weight-bearing axis passes within the affected compartment. For in-skeletally immature patients who are meniscal deficient, not to miss the window of opportunity, be looking at their alignment, as certainly guided growth with open physes is a much easier procedure than an osteotomy later. For those patients who are meniscal deficient and skeletally mature with malalignment, in the lateral compartment, you can trial a lateral compartment unloader brace, and if symptoms improve, then consider a lateral opening wedge distal femoral osteotomy. Likewise, in the medial compartment, trialing a medial unloader brace, and then if symptoms improve, a medial opening wedge high tibial osteotomy. A few osteotomy pearls, make sure these are templated from standing long alignment radiographs. You should plan to achieve correction of the mechanical axis to the base of the tibial spine in the unaffected compartment. So for a lateral meniscus transplant, that would be correcting it to the medial tibial spine. You want to maintain an intact medial distal femur cortical hinge for stability of the osteotomy, and then bone graft the osteotomy. It's important to recognize instability in the knee. This can occur as unrecognized posterolateral corner injuries, or another example would be the trans-tibial ACL reconstruction with a negative Lachlan, but poor rotational stability, and either of these should be corrected prior to placement of a lateral meniscus transplant. Traditional chondral injuries can be addressed well at the time of meniscal allograft transplant. This was a study looking at nearly 100 patients and with four-year follow-up, and they found no difference in outcome scores or clinical outcomes or reoperations between those patients treated with a meniscus transplant with or without treatment of a full thickness chondral defect. A little bit about the surgical techniques and pearls. So meniscus allografts are available in many preparations. Fresh frozen allografts are what are most commonly used as they have low cell viability, but maintained biomechanical properties and reduced immunogenicity. Their size match based on radiographs or MRI, where the lateral x-ray is used to measure the length of the meniscus and then the width based on the distance between the peak of the tibial spine to the metaphyseal margin, as you can see in these images. There's been no significant superiority of one technique over another for meniscus transplant, whether that be soft tissue with bone plugs or bone bridge. What's most important is to recreate the anatomic attachments of the meniscus to allow restoration of function. And so for the lateral meniscus with roots in close proximity, a trough technique is most commonly utilized. In contrast, the medial meniscus roots are further apart and so therefore bone plug or soft tissue fixation can be achieved. A knee arthroscopy is performed. Meniscus is debrided, although to leave a one to two millimeter rim of native meniscal tissue for repair to minimize the risk of extrusion. The meniscus graft is then prepared and then the trough or bone plugs are made within the knee and the medial side of the MCL can be released to facilitate medial meniscus graft passage. Guide sutures are placed in the posterior horn, which help to bring the meniscus into the knee. And an inside out repair is performed with the posterior horn and body while an outside in is performed with the anterior horn. These patients should plan for a 12 month total recovery where the first six weeks are non-weight bearing and then crutches are weaned, range of motion is gently advanced as tolerated, and ultimately low impact exercise should be encouraged. In terms of outcomes, overall outcomes in a systematic review show that survivorship of these at 10 and 15 years is about 75% and 60% respectively with mean times to failure of approximately eight years. Patients have significantly sustained functional improvements with low rates of complications. A study performed among adolescents undergoing meniscal transplant demonstrated similar outcomes at a seven year follow-up. The majority of these were meniscus transplants in the lateral compartment with an overall 22% reoperation, although only 6% for the meniscus itself. You can see all significant improvements in patient subjective scores. So in conclusion, meniscus transplant is an effective salvage procedure for symptomatic meniscal deficiency. You should never assume that meniscus deficiency is an isolated pathology in an otherwise healthy knee. And so look closely at their mechanical alignment, ligamentous stability, and chondral injuries. And at mid to long-term follow-up, meniscus transplant is associated with reliable improvements in function, pain, and swelling in carefully selected patients. Thank you.

Crystal Perkins

pediatric considerations

technical pearls

meniscus transplant

meniscus deficiency