Role of Biologicals in Meniscus Surgery

Authors: Sebastian Kopf Roland Becker

Publish Date: 2014

Volume: , Issue: , Pages: 1-19

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Abstract

Meniscus healing in the avascular central zone which includes more than twothirds of the meniscus from the central region to the periphery is strongly impaired mainly because of the diminished blood supply but due to intrinsic factors Over the last 30 years an increasing number of research studies have focused on the enhancement of meniscus healing utilizing biologicals such blood products growth factors and certain types of cells including progenitor cells or surgical techniques such as synovial and meniscus rasping needling and trephination aiming to enhance biologically healing The results varied significantly Furthermore most of these studies were in vitro or animal trials Thus far there has been no clear evidence to support the use of any of these biologicals However because of the ease of its usage and its low costs many surgeons perform meniscus needling as well as synovial and meniscus raspingMeniscus tears are known for their inferior healing potential To improve the healing capacity of meniscus tears several methods have been introduced including trephination or needling of the meniscus rasping of the synovial membrane and the meniscus surface opening of the medullary cavity to induce an intraarticular influx of progenitor cells as well as locally applying fibrin clots plateletrich plasma PrP growth factors or progenitor cells into the meniscus lesion The following chapter will introduce you to these methods presenting the literature and its clinical applicationMeniscus lesions are one of the most common sports injuries of the knee and meniscus surgery is one of the most common knee surgeries Burks 1997 In the USA about one million meniscus surgeries are performed per year Until the 1970s meniscal tears were commonly treated by complete meniscectomy Complete meniscectomy led to shortterm pain release but to a longterm degeneration of the knee and osteoarthritis AnderssonMolina 2002 Roos et al reported a sixfold increase of osteoarthritis after 21 years of followup of 107 patients after complete meniscectomy Roos 1998 However partial meniscectomy and untreated meniscus lesions lead even though slower as with total meniscectomy to a degeneration and finally osteoarthritis of the knee with all its consequences including pain immobility and finally knee arthroplasty Chatain 2001 Englund 2001 Bonneux 2002 Cicuttini 2002 VanTienen 2003 The amount of resected meniscal tissue is inversely correlated with the onset and the degree of osteoarthritis Englund 2001 Despite early reports of the healing potential of menisci it remained contentious for a long time Dieterich 1931 Webber 1985 Meniscus repair has been shown to be superior regarding onset of osteoarthritis and return to sports compared to partial meniscectomy Stein 2010 Meniscus repair should be performed when feasible with good prospects If partial meniscectomy is not avoidable as much as possible meniscus tissue should be preservedThe healing potential of the meniscus inner twothirds is low It is presumed that this is mainly because of insufficient blood supply Arnoczky 1983a Petersen 1995 Additionally there is also a discussion about a lower intrinsic healing potential of the avascular region compared to the vascular region Kobayashi 2004 Hennerbichler 2007Though meniscus repair is mainly performed in longitudinal vertical or radial lesions of the vascular meniscus region Meniscus repair is done to approximate the wound edges and provide a stable situation In humans a cutoff of 4 mm peripheral rim was found to be necessary for good healing chances of repairable meniscus lesions Tenuta 1994 The failure rate of meniscus repair including sutures and allinside devices has also been reported to be between 12 and 48 Konan 2010 Tengrootenhuysen 2010 and is often followed by partial meniscectomy Therefore there has been an effort to improve healing of meniscal lesions utilizing biological methods such as rasping of the synovial membrane and meniscus to stimulate growth factors creating vascular channels from the periphery to the lesion and applying local adjuncts including fibrin and blood clots plateletrich plasma PrP growth factors and different types of cells eg progenitor cells Arnoczky 1988a Fox 1993 Becker 2004 Ishida 2007 Kopf 2010a Dutton 2010 Tissue engineering of meniscus has been also an inspiring field of research over the last years and is extensively discussed in chapter “Human Meniscus From Biology to Tissue Engineering Strategies”To decrease the amount of injured meniscus tissue the usefulness of cannulas was evaluated to improve vascularity and therefore meniscus healing In a canine study longitudinal meniscus lesions were created in the avascular region Zhongnan 1988 In one group meniscus lesions were left untreated and one group meniscus lesions were trephined from the periphery to the lesion using cannulas with a diameter of 15 mm After 8 weeks all trephined menisci healed partially Around the trephination hole about 1–2 mm of the meniscus lesions was filled with collagen In the untreated group no meniscus healed Interestingly there was no further progress in healing from the 8th to the 24th week Zhongnan 1988 The authors of both studies Henning 1987 Zhongnan 1988 noticed that the creation of a sufficient canal by using a usual biopsy needles failed because the canal closes immediately after pulling out the needle Due to this fact they used cannulas with a larger diameter In a goat study comparing the healing effect of a meniscus repair and an additional trephination to only a meniscus repair trephined menisci healed better Zhang 1995 Repair was performed with one horizontal suture and one vascular channel was created using a 20 mm trephine in outsidein technique In contrast to the aforementioned results of Zhongnan et al Zhongnan 1988 healing continued from the 8th to the 25th week Zhang 1995 Despite the superiority of meniscus repair and trephination compared to meniscus repair the detailed results are worthwhile further interpretation Based on the authors’ own healing classification system in the suture plus trephination group four menisci healed completely and 16 healed partially In the suture group three menisci healed partially However as mentioned in the discussion of the paper if classic criteria of meniscus healing Henning 1990a based on the healing of the vertical height were applied 80 of the repairs failed because the mean healing length was 69 at 25 weeks Zhang 1995 Thus the shortterm results of this meniscus tissuedamaging technique without any knowledge about longterm degenerative consequences are not convincingThe next step was the development of a bioabsorbable conduit polyLlactic acid = PLLA Cook 2007 In a canine study a 5 mm longitudinal meniscus lesion was created in the avascular region In 21 lesions trephination was performed with a 18 mm pin from the lesion into the periphery and in 29 lesions the conduit with a diameter of 15 mm and a length of 4 mm was placed into the created vascular channel Additionally all lesions were sutured horizontally After 12 and 24 weeks four out five meniscus lesions treated with the conduit and a horizontal suture were healed in contrast to the trephination group trephination with a horizontal suture that showed no complete healing The biomechanical testing revealed significant stronger normal meniscus compared to the conduit and trephinations lesions Interestingly there was no significant difference between meniscus lesions with the conduit and with only the trephination In four lesions out of 29 the conduit displaced and despite the fact that no cartilage defect was seen in this study there are reports in the literature about bioresorbable meniscus anchors that showed chondral damage Sarimo 2005 Järvelä 2010 The disappointing results of the trephination group in this trial might be explained by the fact that a pin was used which just pushed the meniscus tissue aside by advancing from the lesion to the periphery in contrast to the cannulas =hollow needle that were used in the previous trials which cut meniscus tissue out and leave a tunnel after being pulled out of the meniscus

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