Articular cartilage degeneration after frozen meniscus and achilles tendon allograft transplantation: experimental study in sheep

Purpose: The purpose of this study was to analyze cartilage degeneration in knees after total medial meniscectomy, transplantation of fresh-frozen meniscus allograft, and Achilles tendon allograft. Type of Study: Experimental study. Methods: We have studied the articular cartilage in the medial compartment of the left knees in 32 sheep aged 5 to 6 months, with 8 animals in each group. The study was performed after meniscectomy (group I), transplantation of fresh-frozen meniscus allograft (group II), use of fresh-frozen Achilles tendon allograft (group III), and in a control group (group IV). For the histologic study, all samples were stained with Masson’s trichrome and Safranine-O. Mankin’s score was applied to grade the histologic damage to the articular cartilage. Results: The group with the greatest number of degenerative changes was group III, followed by groups I and II. The percentage of thickness of cartilage detected by Safranine-O stain was found to be significantly different in both tibia and femur between the control group and the other 3 groups, but not among groups I, II, and III. The immunoreactivity of the articular surfaces in tibia and femur showed notable differences in all the groups. Collagen X was present in the degenerative hypertrophic chondrocytes in the damaged articular surfaces. Conclusions: Meniscal replacement with meniscal and Achilles tendon allografts provides partial protection against articular damage after a meniscectomy.     

Scintigraphic assessment of rabbit knee joints after meniscal allograft transplantation

Purpose: It has been shown that meniscal allografts show capsular ingrowth in meniscectomized knees. However, it remains to be established whether a transplanted meniscus can prevent degenerative changes in the long term. In the present study, scintigraphy was used to evaluate degenerative changes in rabbit knees after meniscectomy only and after meniscectomy followed by immediate or delayed meniscus transplantation. Type of Study: Experimental study. Methods: Twenty-eight rabbits were divided into 4 groups. Three rabbits developed infective arthritis and were excluded from the study. In group A (6 animals), 2 rabbits underwent medial meniscectomy, 3 rabbits underwent transplantation with a freshly harvested medial meniscal allograft immediately after meniscectomy, and 1 rabbit underwent a sham operation. In group B (6 rabbits) medial meniscectomy was performed. Group C (6 rabbits) underwent meniscal transplantation immediately after meniscectomy. Group D (7 rabbits) underwent delayed allograft transplantation at 6 weeks after meniscectomy. The animals in group A underwent scintigraphy at 6 weeks after surgery. In the other groups, scintigraphy was performed at 1-year follow-up. Contour changes of the knee joints and uptake of radiolabeled diphosphonate in the subchondral bone were evaluated. Results: No animals in group A showed any abnormalities scintigraphically. Medial compartment changes in group B were more pronounced than in group C, but this difference was not statistically significant. A significant increase in contour changes of the femoral condyle was seen in group D. Conclusions: Immediate meniscal allograft transplantation did not result in a significant protecting effect on articular cartilage against osteoarthritic degeneration on a long-term basis. Delayed meniscal transplantation revealed even more degenerative changes of articular cartilage than meniscectomy without transplantation.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 19, No 5 (May-June), 2003: pp 506–510     

Immediate versus delayed meniscal allograft transplantation in sheep

The aim of the current study was to assess the effect of immediate and delayed transplantation on articular cartilage. Icelandic sheep had surgery on the medial menisci in both knees. The knees were divided into four groups; 16 control knees had sham surgery, 15 knees had meniscectomy, 14 knees had immediate allograft transplantation, and 14 knees had delayed transplantation 3 months after meniscectomy. The two horns of the fresh allograft were fixed with suture anchors through bone tunnels. The sheep had autopsies 6 months after surgery. An additional six knees were examined 3 months after meniscectomy to examine the cartilage before the delayed implantation. Four standardized samples were taken from the medial compartment of the knee for histologic evaluation according to a modification of Mankin's system, where degenerative changes to the articular cartilage were scored semiquantitatively for structure, proteoglycan content, cellularity, and cell cloning. Knees that had meniscectomy and delayed transplantation showed equally high scores in articular cartilage degeneration, and both scored higher than knees that had immediate transplantation, which again scored higher than the control knees. In short-term observations, immediate medial meniscal allograft transplantation reduced but did not prevent degeneration of the articular cartilage. Immediate transplantation was superior to delayed transplantation in preventing cartilage degeneration.     

Evaluation of small intestinal submucosa grafts for meniscal regeneration in a clinically relevant posterior meniscectomy model in dogs

Large meniscal defects are a common problem for which treatment options are limited. Successful meniscal regeneration has been achieved by using grafts of small intestinal submucosa in posterior, vascular meniscal defects in a dog model. This study investigates the long-term effects of a tibial tunnel fixation technique and a clinically based meniscectomy defect on meniscal regeneration using this model. Eight mongrel dogs underwent medial arthrotomy and partial meniscectomy. The dogs were divided into groups based on defect treatment: small intestinal submucosa (n = 4) or meniscectomy (n = 4). Dogs were scored for lameness by subjective scoring postoperatively, sacrificed at 6 months, and assessed for articular cartilage damage, gross and histologic appearance of the operated meniscus, amount of new tissue in the defect, and relative compressive stiffness of articular cartilage. Dogs in the meniscectomy group were significantly (P = .002) more lame than dogs treated with small intestinal submucosa. Small intestinal submucosa-treated joints had significantly (P = .01) less articular cartilage damage than meniscectomy joints. Small intestinal submucosa meniscal implants resulted in production of meniscal-like replacement tissue, which was consistently superior to meniscectomy in amount, type, and integration of new tissue, chondroprotection, and limb function during the study period. Small intestinal submucosa implants may be useful for treatment of large posterior vascular meniscal defects in humans. The tibial tunnel technique used for fixation may have clinical advantages and therefore warrants further investigation.     

Meniscal replacement using a cryopreserved allograft. An experimental study in the dog

The medial menisci of 14 adult dogs were replaced using a cryopreserved meniscal allograft. The morphology and metabolic activity of the transplanted allografts were then evaluated using routine histology, a vascular-injection (Spalteholz) technique, and autoroentgenography (Na2(35)SO4 incorporation) at various intervals, from two weeks to six months postoperatively. After transplantation, the allografts retained their normal gross appearance and healed to the capsular tissues of the host by fibrovascular scar tissue. Histologically, the grafts demonstrated a decrease in the number of metabolically active cells after transplantation but had a normal cellular distribution and Na2(35)SO4 uptake by three months. The allografts appeared to function normally after transplantation. Although some degenerative changes were noted in the tibial articular cartilage not covered by the meniscus, the cartilage beneath the allograft appeared normal.     

Architectural remodeling of fresh meniscal allograft transplantation in a rabbit joint: Its long-term protective effect on articular cartilage

This study assessed a fresh medial meniscal allograft transplantation model in the rabbit knee. Biological characterization included assessment of collagen remodeling of the allograft and the potential protection against cartilage degeneration. Allograft transplantation was performed on the left knee, and total meniscectomy on the right knee. Forty-seven rabbits were operated on and assessed at 9, 12, and 26 weeks. Fresh medial meniscal allografts showed collagen remodeling that paralleled the revascularization and cellular proliferation of the allografts. Revascularization was shown as early as 9 weeks from the periphery, extending to the inner one-third of the allograft by 26 weeks. Viability assessment of the meniscal allograft cells showed live cells at the periphery of the allograft at 9 and 12 weeks. At time 0, i.e., the time of the transplant, few viable cells were observed within the donor tissues. Biochemically, collagen remodeling, in terms of increased reducible collagen crosslinks, i.e., dihydroxylysinonorleucine, and the percentage of collagen present, was seen throughout the 26-week observation period. At 26 weeks, the meniscal allografts inhibited degenerative changes of the femoral and tibial cartialage compared to results with total meniscectomy.     

Chondrocyte viability in press-fit cryopreserved osteochondral allografts.

The viability of chondrocytes in press-fit glycerol-preserved osteochondral allografts was compared to that in fresh autografts, after transplantation into load-bearing and non-load-bearing sites in mature sheep stifle joints. We used macroscopic grading, tonometer pen indentation testing, histology, sulfate uptake and viability as determined by confocal-microscopy to assess cartilage condition. Despite there being no statistical differences between macroscopic appearance and tonometer testing of all grafts, confocal microscopy and histology demonstrated a positive effect of load-bearing placement on cryopreserved osteochondral allografts. Allografts transplanted into load-bearing sites demonstrated superior confocal microscopy-measured chondrocyte viability (77%+/-17%SD) than those transplanted into non-load-bearing sites (25%+/-2%). Load-bearing effect was not seen in autografts (78%+/-15%), and was comparable in adjacent cartilage (83%+/-9%). Similarly, load-bearing allografts demonstrated histological scoring closer to that of autografts and adjacent cartilage, all of which fared significantly better than non-load-bearing allografts. Load-bearing allografts had a greater amount of fibrocartilage than autografts or adjacent cartilage but less fibrocartilage than non-load-bearing allografts. Both autografts and allografts had non-significant increases in metabolism compared to adjacent cartilage as measured by sulfate-uptake. Load-bearing placement improved chondrocyte viability of glycerol cryopreserved osteochondral allograft following a press-fit implantation.     

Performance of a Sterile Meniscal Allograft in an Ovine Model

Meniscus transplantation is indicated for persistent pain in a meniscectomized knee. Currently, grafts are prepared aseptically, which provides limited protection against donor-derived infection. The performance of a novel, sterilized meniscus was compared with an aseptically prepared one in an experimental model. Twenty-two sheep were divided into three groups: aseptic meniscal allograft, sterile meniscal allograft, and medial meniscectomy. Animals were euthanized 2 and 4 months after surgery. Meniscal assessments included cell viability, histology, and biomechanical testing. Articular cartilage was evaluated through histology and Outerbridge scoring. Aseptic and sterile allografts had cell viabilities of 59.7% and 58.7%, respectively, at 4 months, which was less than native controls. Grafts had decreased compressive strength at 4 months compared with their preimplantation moduli and were weaker than native menisci. In operated knees, the tibial plateau had more severe degenerative changes, although Outerbridge scores were similar between operated groups. Overall, the allografts were similar in their cellularity and biomechanical properties but were inferior to the native tissue at these end points. The severity of chondral damage in the allograft knees could not be distinguished from meniscectomized joints. The sterilization process does not appear to compromise tissue integrity and provides additional allograft safety. One or more of the authors (VMW, BJC, JMW) has received funding from RTI-Biologics (Alachua, FL). Each author certifies that his or her institution has approved the animal protocol for this investigation and that all investigations were conducted in conformity with ethical principles of research.     

The fate of articular cartilage after transplantation of fresh and cryopreserved tissue-antigen-matched and mismatched osteochondral allografts in dogs

The long-term success of massive osteochondral allografts depends not only on the incorporation of the transplanted articular cartilage. Osteochondral allografts are immunogenic, and, once an immune response is stimulated by exposure to donor cellular antigens, the cartilage becomes vulnerable to direct injury by cytotoxic antibodies or by lymphocytes, or to indirect injury by inflammatory mediators and enzymes induced by the immune response. To clarify the role of histocompatibility antigen-matching on the health of transplanted articular cartilage, we orthotopically implanted canine leukocyte antigen-matched and mismatched proximal osteochondral allografts of the radius, both fresh and cryopreserved, in beagles. Four groups of dogs received: (1) canine leukocyte antigen-mismatched frozen allografts, (2) canine leukocyte antigen-mismatched fresh allografts, (3) canine leukocyte antigen-matched fresh allografts, or (4) canine leukocyte antigen-matched frozen allografts. In twelve of the dogs, the contralateral leg was subjected to a sham operation, and in ten of the dogs, the proximal part of the radius was removed and replaced as an autogenous graft control. All animals were followed for eleven months after the operation and then were killed. The cartilage of the grafts was evaluated grossly, histologically, and biochemically. The biochemical analysis consisted of measurement of dry weight, content of glycosaminoglycan and hydroxyproline, and galactosamine-to-glucosamine ratios. Analyses of variance were used to study the effect of tissue antigen-matching and freezing on degradation of cartilage. During the study, no dog had grossly obvious clinical abnormalities, all host-graft interfaces healed, and no joints dislocated. The gross appearance of the cartilage was normal for both the joints that had an autogenous graft and those that were subjected to the sham operation. The cartilage of all allografts was thinned, dull, and roughened. The synovial membrane of all of the joints that had been operated on was mildly fibrotic and hyperplastic, but only that of the dogs that had an allograft was severely fibrotic and hyperplastic and demonstrated an inflammatory response. The inflammatory response was most severe in joints that had received a fresh canine leukocyte antigen-mismatched allograft. Invasive pannus was more frequent in joints that had received a fresh graft, particularly those that had received a canine leukocyte antigen-mismatched allograft, and cartilage was sometimes eroded to subchondral bone. Freezing was harmful to the cartilage. Very few cells survived the freezing procedure, and frozen grafts received s significantly worse histological scores had significantly less glycosaminoglycans and had a lower ratio of galactosamine to glucosamine than fresh grafts.     

Assessment of donor cell and matrix survival in fresh articular cartilage allografts in a goat model

The long-term survival of allografts of articular cartilage has been proposed to be dependent on the survival of the cells that maintain the unique structural and material properties of the allograft. In this study, we assessed cell survival in 24 fresh articular cartilage allografts of the medial plateau in a Spanish-goat model. A DNA-probe technique was used to distinguish clearly between DNA from donor (allograft) and host cells. The intraarticular survival of viable allograft chondrocytes in the transplanted articular cartilage started to diminish as early as 3 weeks after transplantation; however, there was considerable variation in the amount of donor cell DNA detected in the allografts at 6 and 12 months following transplantation. This contrasts with our experience with fresh allografts of ligament, tendon, and meniscus, in which no donor DNA was detected 4 weeks after transplantation. DNA from host cells was present in all articular cartilage allografts, as evidenced by detectable unique host DNA patterns. Histological and histochemical assays showed that none of the transplants demonstrated normal structure and composition at 1 year after transplantation. The grafts in which large quantities of donor DNA were present appeared grossly superior to those with no or reduced remaining demonstrable donor DNA.     

Structural analysis of meniscal allografts after immediate and delayed transplantation in rabbits

Purpose: To compare long-term performance of meniscal allografts transplanted immediately after meniscectomy and allografts transplanted 6 weeks after meniscectomy. Type of Study: Experimental study. Methods: Twenty-one rabbits were subjected to meniscectomy and divided into 3 groups of 7 animals. Immediate meniscal transplantation was performed in group A (6-week follow-up) and group B (1-year follow-up). Group C underwent delayed transplantation 6 weeks after meniscectomy. One animal in group B developed infective arthritis and was not included. Six nonoperated knees served as controls. Four other knees were subjected to a sham procedure. Menisci were examined macroscopically and histologically at 6 weeks (group A and 2 sham- operated animals) and 1 year (group B, C, controls, and 2 sham-operated animals). Results: Capsular ingrowth was observed in all allografts. At 1 year, osteoarthritic changes in the delayed transplant group were more pronounced than in the immediate transplant group. Menisci in nonoperated controls and sham-operated knees appeared normal. No differences in shrinkage of allografts were observed between groups A and B. Group C showed significantly more shrinkage than allografts in both group A (P = .004) and group B (P = .005). Two allografts in group C were completely degenerated. Differences in architecture of the allografts were not found between groups A, B, and C. In both the peripheral and central areas of transplanted menisci, the number of cells was frequently increased because of repopulation even at 6-week follow-up. Conclusions: Delayed meniscal allograft transplantation causes distinct structural damage to menisci in comparison with immediate transplantation.     

Need Room to Operate? Partial and Intentional Release of the Knee Medial Collateral Ligament for Medial Meniscal Surgery

Cutting the medial collateral ligament (MCL), even in part, seems counterintuitive. However, medial meniscal surgery is not always easy, and iatrogenic articular cartilage damage can be a complication of partial meniscectomy, meniscus repair, and/or allograft transplantation in a tight knee. Fortunately, partial tears of the MCL tend to heal, and most patients do tolerate iatrogenic, partial MCL tearing without negative long-term sequelae. However, rather than accidentally tearing the MCL during medial meniscal surgery, if you need room to operate, partially release the MCL.     

In vivo efficacy of fresh versus frozen osteochondral allografts in the goat at 6 months is associated with PRG4 secretion

The long‐term efficacy of osteochondral allografts is due to the presence of viable chondrocytes within graft cartilage. Chondrocytes in osteochondral allografts, especially those at the articular surface that normally produce the lubricant proteoglycan‐4 (PRG4), are susceptible to storage‐associated death. The hypothesis of this study was that the loss of chondrocytes within osteochondral grafts leads to decreased PRG4 secretion, after graft storage and subsequent implant. The objectives were to determine the effect of osteochondral allograft treatment (FROZEN vs. FRESH) on secretion of functional PRG4 after (i) storage, and (ii) 6 months in vivo in adult goats. FROZEN allograft storage reduced PRG4 secretion from cartilage by ～85% compared to FRESH allograft storage. After 6 months in vivo, the PRG4‐secreting function of osteochondral allografts was diminished with prior FROZEN storage by ～81% versus FRESH allografts and by ～84% versus non‐operated control cartilage. Concomitantly, cellularity at the articular surface in FROZEN allografts was ～96% lower than FRESH allografts and non‐operated cartilage. Thus, the PRG4‐secreting function of allografts appears to be maintained in vivo based on its state after storage. PRG4 secretion may be not only a useful marker of allograft performance, but also a biological process protecting the articular surface of grafts following cartilage repair. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 880–886, 2013     

同种异体肋软骨膜移植半月板再生的实验研究

目的：探究同种异体肋软骨膜游离移植再生半月板的能力及其预防关节退变的意义。材料及方法：选用成年家犬10只，双膝关节内侧半月板切除后随机选取一侧膝关节内侧间隙植入同种异体肋软骨膜（同种异体移植组），对侧膝关节植入自体肋软骨膜（自体移植组），以全部切除的正常半月板及正常膝关节作为对照（对照组）。分别于术后4、8、12周切取标本，进行大体、光镜（HE染色及Alcian-blue,Safranin 0复杂）、透射电镜观察，并对正常半月板及术后12周的移植物进行生物力学测试。结果：12周时所有移植物都衍化再生出接近正常半月板大小及形态的纤维软骨板。在整个实验过程中未见明显的免疫排斥反应。生物力学测试结果显示两移植组再生半月板的抗拉伸性能无显著性差异，均低于正常半月板。结论：同种异体肋软骨膜游离移植于半月板缺失的犬的膝关节中可以存活，并可再生出接近正常形态、结构的半月板，无免疫排斥反应。     

Meniscal Allograft Transplantation: Indications,Techniques, Outcomes

Meniscal allograft transplantation (MAT) has become an acceptable surgical treatment for select symptomatic and relatively young (<50 years of age) patients with a meniscal deficiency. MAT may also be considered in meniscal-deficient patients undergoing anterior cruciate ligament reconstruction and/or articular cartilage repair procedure in the ipsilateral compartment. Contraindications to MAT include asymptomatic patients, severe osteoarthritis, uncorrectable malalignment or instability, irreparable chondral damage, active infection, or inflammatory arthropathy. Most institutions prefer the use of fresh-frozen allografts, whereas the use of fresh-viable grafts is limited by their availability, and the use of cryopreserved and lyophilized grafts has gone out of favor. Donor allografts are size-matched to the recipient using x-rays or magnetic resonance imaging measurements. To date, no particular surgical technique has demonstrated superiority. Therefore, there are several used approaches (mini-open or arthroscopic), horns-fixation techniques (soft-tissue, bone-plugs, or bone-bridge), and peripheral suture techniques (inside-out or all-inside). Ipsilateral malalignment, instability, and/or chondral defects should be corrected or repaired if MAT is being performed. MAT survival rates are estimated at 73.5% at 10 years and 60.3% at 15 years. Mean time-to-failure is ∼8.2 and ∼7.6 years for a medial and lateral meniscus transplant, respectively. Significant improvement in patient-reported outcomes is expected following MAT, and 90% of patients will attest they will undergo the procedure again. Reoperation rates are estimated at 32%, with the most common complication being a tear of the meniscal allograft. Many studies reporting on outcomes of MAT are flawed because of low-quality, the use of non-fresh-frozen preservation techniques, and heterogeneity of patients and concomitant procedures. As our knowledge regarding patient selection, graft preparation, and techniques continue to develop, we expect MAT outcomes to improve much further.     

Transplantation of viable meniscal allograft. Survivorship analysis and clinical outcome of one hundred cases

BACKGROUND: Few medium-term or long-term reports on meniscal allograft transplantations are available. In this study, we present the results of a survival analysis of the clinical outcomes of our first 100 procedures involving transplantation of viable medial and lateral meniscal allografts performed in ninety-six patients. METHODS: Thirty-nine medial and sixty-one lateral meniscal allografts were evaluated after a mean of 7.2 years. Survival analysis was based on specific clinical end points, with failure of the allograft defined as moderate occasional or persistent pain or as poor function. An additional survival analysis was performed to assess the results of the sixty-nine procedures that involved isolated use of a viable allograft (twenty of the thirty-nine medial allograft procedures and forty-nine of the sixty-one lateral allograft procedures) and of the thirteen viable medial meniscal allografts that were implanted in combination with a high tibial osteotomy in patients with initial varus malalignment of the lower limb. RESULTS: Overall, eleven (28%) of the thirty-nine medial allografts and ten (16%) of the sixty-one lateral allografts failed. The mean cumulative survival time (11.6 years) was identical for the medial and lateral allografts. The cumulative survival rates for the medial and lateral allografts at ten years were 74.2% and 69.8%, respectively. The mean cumulative survival time and the cumulative survival rate for the medial allografts used in combination with a high tibial osteotomy were 13.0 years and 83.3% at ten years, respectively. CONCLUSIONS: Transplantation of a viable meniscal allograft can significantly relieve pain and improve function of the knee joint. Survival analysis showed that this beneficial effect remained in approximately 70% of the patients at ten years. This study identified the need for a prospective study comparing patients with similar symptoms and clinical findings treated with and without a meniscal allograft and followed for a longer period with use of clinical evaluation as well as more objective documentation tools regarding the actual fate of the allograft itself and the articular cartilage.     

DNA analysis of a transplanted cryopreserved meniscal allograft.

SUMMARY: Meniscal transplantation is frequently performed in young patients with a single meniscal-deficient compartment as a result of previous total meniscectomy. Indications, operative techniques, and preservation of meniscal allografts have been studied extensively. In this study we compared the DNA profile of a meniscal allograft with that of the human recipient 1 year after transplantation. Applying techniques routinely used in forensic analysis, we were able to show that the DNA profile of the meniscal allograft was 95% identical to that of the human recipient. These findings indicate that 1 year after transplantation the meniscal allograft is nearly completely repopulated by host cells.     

同种异体半月板联合骨软骨移植的实验研究

目的:探讨新鲜同种异体半月板骨软骨联合移植治疗胫骨平台毁损伤后骨关节炎的疗效。方法:成年新西兰大白兔36只,随机分为A、B、C3组,各12只。A组行右膝内侧半月板连同胫骨平台骨软骨移植,克氏针交叉固定骨块。B组行右膝内侧半月板移植,左膝内侧半月板取出制备新鲜冷冻半月板。C组行左膝内侧新鲜冷冻半月板移植。术后4、8、12周分批取材行大体观察、组织学检查和胫骨平台软骨氨基己糖(GAG)测定。结果:12周时A组移植胫骨平台软骨与B、C组半月板移植术后的内侧胫骨平台软骨氨基己糖含量差异无统计学意义;A、B组移植的半月板纤维软骨细胞数差异无统计学意义;A组半月板移植的纤维软骨细胞数多于C组。结论:新鲜同种异体半月板骨软骨联合移植能修复胫骨平台毁损伤。