[Results of polyurethane implant for persistent knee pain after partial meniscectomy with a minimum of two years follow-up]

Meniscal substitution, a developing and long-awaited demand

The menisci represent indispensable intraarticular components of a well-functioning knee joint. Sports activities, traumatic incidents, or simply degenerative conditions can cause meniscal injuries, which often require surgical intervention. Efforts in biomechanical and clinical research have led to the recommendation of a meniscus-preserving rather than a meniscus-resecting treatment approach. Nevertheless, partial or even total meniscal resection is sometimes inevitable. In such circumstances, techniques of meniscal substitution are required. Autologous, allogenic, and artificial meniscal substitutes are available which have evolved in recent years. Basic anatomical and biomechanical knowledge, clinical application, radiological and clinical outcomes as well as future perspectives of meniscal substitutes are presented in this article. A comprehensive knowledge of the different approaches to meniscal substitution is required in order to integrate these evolving techniques in daily clinical practice to prevent the devastating effects of lost meniscal tissue.

Polyurethane meniscal scaffolds lead to better clinical outcomes but worse articular cartilage status and greater absolute meniscal extrusion

PURPOSE

Implantation of polyurethane (PU) meniscal scaffolds has become a popular procedure to provide a scaffold for vessel ingrowth and meniscal tissue regeneration in patients with partial meniscal defects. However, it is unclear whether PU meniscal scaffolds lead to better clinical and magnetic resonance imaging (MRI) outcomes post-operatively. This meta-analysis compared the clinical and MRI outcomes in patients with partial meniscal defects treated with PU meniscal scaffolds.

METHODS

This meta-analysis reviewed all studies that assessed Lysholm score, International Knee Documentation Committee (IKDC) score, visual analogue scale (VAS) for pain, Tegner score, Knee Injury and Osteoarthritis Outcomes Score (KOOS), articular cartilage (AC), absolute meniscal extrusion (AME), morphology and size (MS), signal intensity (SI) of meniscal implant, and interface of the implant-residual meniscus complex (IIRMC) in patients with partial meniscal defects treated with PU meniscal scaffolds.

RESULTS

Eighteen studies were included in the meta-analysis. The proportion of patients who evaluated MS (OR 0.71, 95% CI 0.38-1.33; n.s.), SI (OR 1.07, 95% CI 0.53-2.18; n.s.), and IIRMC (OR 1.00, 95% CI 0.33-3.06; n.s.) did not differ significantly between baseline and final follow-up. However, AC (OR 0.31, 95% CI 0.11-0.84; P = 0.02) and AME (OR 0.05, 95% CI 0.01-0.18; P < 0.00001) worsened between baseline and final follow-up. Conversely, Lysholm score (95% CI -1.87 to -1.07; P < 0.00001), IKDC score (95% CI -2.19 to -1.08; P < 0.00001), VAS for pain (95% CI -2.29 to -1.07; P < 0.00001), Tegner score (95% CI -0.76 to -0.15; P = 0.003), and overall KOOS (95% CI -29.48 to -23.17; P < 0.00001) were significantly greater at final follow-up when compared to baseline.

CONCLUSION

This meta-analysis found no significant differences in the tested MRI parameters, including MS, SI, and IIRMC. However, AC and AME worsened between baseline and final follow-up. Conversely, patients treated with PU meniscal scaffolds showed significant functional improvement and pain relief when compared with baseline scores. Thus, PU meniscal scaffolds appear to be a viable alternative for patients with partial meniscal defects, although further studies are needed to determine whether worsened AC and AME are clinically relevant. In particular, precise measurement of PU meniscal scaffolds in combination with thorough investigation of the baseline articular cartilage status and meniscal defect size may be effective for pain relief or functional improvement in patients with PU meniscal scaffold implantation.

LEVEL OF EVIDENCE

III.

Similar clinical outcomes following collagen or polyurethane meniscal scaffold implantation: a systematic review

PURPOSE

The purpose of this systematic review is to evaluate the current literature in an effort to assess specific clinical outcomes following meniscal scaffold implantation using the two available scaffolds: Collagen Meniscal Implant (CMI) and the Actifit polyurethane meniscal scaffold.

METHODS

A systematic review was performed by searching PubMed, Embase, and Cochrane Library to find studies evaluating clinical outcomes of patients undergoing meniscal scaffold implantation. Search terms used were "meniscus", "meniscal", "scaffold", and "implant". Studies were evaluated based on scaffold type, treatment failure rates, patient-reported outcome scores, concomitant procedures, and radiological findings. Radiological findings were recorded using the Genovese scale to assess morphology and signal intensity and the Yulish score to assess articular cartilage.

RESULTS

Nineteen studies (1 level I, 1 level II, 17 level IV evidence) were identified that met inclusion criteria, including a total of 658 patients (347 Actifit, 311 CMI). The overall average follow-up was 45 months. Treatment failure occurred in 9.9% of patients receiving the Actifit scaffold at a mean follow-up of 40 months and 6.7% of patients receiving CMI at a mean follow-up of 44 months (n.s.). However, the rate of failure ranged from 0 to 31.8% amongst the included studies with a variable definition of failure. Additionally, overlapping patients and presence of concomitant surgeries such as anterior cruciate ligament reconstruction (ACLR) and high tibial osteotomy (HTO) may have a significant influence on these results. Outcomes for the Visual Analog Scale (VAS) for pain, Lysholm knee score, and Tegner activity score improved from preoperatively to latest follow-up in both groups, while the Knee Injury and Osteoarthritis Outcome Score and International Knee Documentation Committee scores improved from preoperatively to latest follow-up for Actifit scaffold patients. Overall, patients receiving CMI scaffolds had higher grades for Genovese morphology and signal intensity when compared to Actifit scaffold patients.

CONCLUSION

Patients undergoing meniscal scaffold implantation with either CMI or Actifit scaffold can both be expected to experience improvement in clinical outcomes when used in association with concomitant procedures such as ACLR and HTO.

LEVEL OF EVIDENCE

IV, systematic review.

Meniscus tear surgery and meniscus replacement

OBJECTIVE

the menisci are easily injured and difficult to repair. The aim of this study was to analyze the current state of meniscal surgery aimed at preserving morphology and conserving the biomechanics of the knee to prevent joint degeneration.

METHODOLOGY

a search of the electronic medical literature database Medline was conducted, from http://www.ncbi.nlm.nih.gov/pubmed. The search was not limited by language. Candidate articles were identified by searching for those that included the keywords meniscus, surgery, suture, implant, allograft. The limits were included for clinical research and clinical trials. Basic research was not included. The studies selected were evaluated and classified in three different categories: basic science, reconstruction (suture and meniscectomy) and implants (scaffolds and allograft).

RESULTS

the consequences of meniscectomy performed at a young age can lead to a joint cartilage degeneration twenty years later. There are few surgical options for the repair of meniscal injuries in order both to preserve the meniscus and to ensure the long term survival of the knee joint, meniscectomy, repair, suturing the tear, or reconstruction, when a meniscal allograft or synthetic substitute is used to replace the meniscus, but the biomechanical properties of the native meniscus are not reproduced entirely by the scaffolds that exist today.

CONCLUSION

therapies that successfully repair or replace the meniscus are therefore likely to prevent or delay osteoarthritis progression.