Comparison of fresh osteochondral autografts and allografts: a canine model

BACKGROUND

Osteochondral autografts and allografts have been widely used in the treatment of isolated grade IV articular cartilage lesions of the knee. However, the authors are not aware of any study that has prospectively compared fresh osteochondral autografts to fresh allografts with regard to imaging, biomechanical testing, and histology.

HYPOTHESIS

The imaging, biomechanical properties, and histologic appearance of fresh osteochondral autograft and fresh allograft are similar with respect to bony incorporation into host bone, articular cartilage composition, and biomechanical properties.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eighteen adult dogs underwent bilateral knee osteochondral graft implantation after creation of an Outerbridge grade IV cartilage defect. One knee received an autograft, and the contralateral knee received a fresh allograft. Nine dogs were sacrificed at 3 months, and 9 dogs were sacrificed at 6 months. Graft analysis included gross examination, radiographs, magnetic resonance imaging, biomechanical testing, and histology.

RESULTS

Magnetic resonance imaging demonstrated excellent bony incorporation of both autografts and allografts. Biomechanical testing demonstrated no significant difference between autografts versus allografts versus control at 3 or 6 months (P = .36-.91). A post hoc calculation showed 80% power to detect a 30% difference between allograft and control. Histologic examination showed normal cartilage structure for both autografts and allografts.

CONCLUSION

Fresh osteochondral autograft and fresh allograft tissues are not statistically different with respect to bony incorporation, articular cartilage composition, or biomechanical properties up to 6 months after implantation.

CLINICAL RELEVANCE

The use of fresh allograft tissue to treat osteochondral defects eliminates morbidity associated with harvesting autograft tissue without compromising the results of the surgical procedure.

Clinical outcomes following osteochondral autologous transplantation (OATS)

This study evaluated the clinical outcome in 21 patients (22 knees) undergoing osteochondral autologous transplantation (OATS) in the knee over a 5-year period. Sixteen knees in 15 patients were available for follow-up at an average of 40 months after the procedure. The clinical outcome was analyzed using the IKDC and Knee and Osteoarthritis Outcome Score (KOOS) evaluation forms, a subjective questionnaire, and a clinical examination. At final follow-up, the average KOOS result for pain was 80.6 (range: 56-94), symptoms 53.6 (range: 25-71), function of activities of daily living 93.4 (range: 79-100), function of sports and recreational activities 65.3 (range: 20-100), and quality of life 51.0 (range: 6-88). The average IKDC score was 68.2. On our subjective questionnaire, the average preoperative grade given was 3.1 (range: 1-7) with an improvement at the most recent follow-up to a grade of 8.0 (range: 5-10) (P < .00001). Thirteen (86%) patients reported that they would have the surgery again if they had to make the decision a second time. Age did not correlate with subjective results on the IKDC evaluation (P = .7048) or score difference on our questionnaire (P = .9175). This procedure provides an option for articular resurfacing of the femoral condyles for focal areas of chondral defects with promising results regarding subjective improvement.

Osteochondral autograft transplantation in the porcine knee

BACKGROUND

Knee articular cartilage defects are not an uncommon problem. Because articular cartilage is limited in its ability to heal, these defects are difficult to manage.

HYPOTHESIS

Osteochondral autografts will provide less of a cavitary defect and more viable hyaline articular cartilage than will control knees.

STUDY DESIGN

Controlled laboratory study.

METHODS

Osteochondral autografts were grossly and microscopically evaluated in the porcine knee and compared with a control at 6 weeks, 3 months, and 6 months. In 18 porcine specimens, a 1-stage surgical procedure was performed to harvest an osteochondral graft from a nonweightbearing articular cartilage surface, and the graft was transplanted into a defect created in the weight-bearing region of the medial femoral condyle. In the opposite control knee, a similar defect was created in the medial femoral condyle; an osteochondral transplant was not performed. Six pigs each were sacrificed at 6 weeks, 3 months, and 6 months.

RESULTS

Gross inspection of the control knees showed a cavitary defect. The defect grossly decreased in size with fibrous ingrowth seen on microscopic analysis. An increasing amount of fibrous tissue and fibrocartilage was present at the 3 time periods. Gross inspection of the graft knee showed a healed osteochondral plug with no obvious displacement, cavitary defects, or surrounding necrotic tissue at each time interval. Microscopic analysis revealed the graft knee contained viable hyaline cartilage and healed viable subchondral bone. At all time intervals, 75% to 100% of the hyaline cartilage was viable in all specimens. In 6-month specimens, bridging cartilage at the autograft-host junction was incomplete in 50%, partial in 33%, and complete in 17%.

CONCLUSION

Osteochondral autografts in the porcine knee resulted in viable hyaline cartilage for up to 6 months; there was inconsistent bridging hyaline cartilage at the periphery. Grafts appeared to heal into existing subchondral bone without displacement or evidence of necrosis.

CLINICAL RELEVANCE

This type of osteochondral transplant can be used as a reliable reconstructive alternative for osteochondral defects.

Minced cartilage without cell culture serves as an effective intraoperative cell source for cartilage repair

Traumatic articular cartilage injuries heal poorly and may predispose patients to the early onset of osteoarthritis. One current treatment relies on surgical delivery of autologous chondrocytes that are prepared, prior to implantation, through ex vivo cell expansion of cartilage biopsy cells. The requirement for cell expansion, however, is both complex and expensive and has proven to be a major hurdle in achieving a widespread adoption of the treatment. This study presents evidence that autologous chondrocyte implantation can be delivered without requiring ex vivo cell expansion. The proposed improvement relies on mechanical fragmentation of cartilage tissue sufficient to mobilize embedded chondrocytes via increased tissue surface area. Our outgrowth study, which was used to demonstrate chondrocyte migration and growth, indicated that fragmented cartilage tissue is a rich source for chondrocyte redistribution. The chondrocytes outgrown into 3-D scaffolds also formed cartilage-like tissue when implanted in SCID mice. Direct treatment of full-thickness chondral defects in goats using cartilage fragments on a resorbable scaffold produced hyaline-like repair tissue at 6 months. Thus, delivery of chondrocytes in the form of cartilage tissue fragments in conjunction with appropriate polymeric scaffolds provides a novel intraoperative approach for cell-based cartilage repair.

[Autologous osteochondral transplantation under arthroscope to treat cartilage defect]

OBJECTIVE

To explore the methods of repairing cartilage defects and to introduce the clinical experience with the autologous osteochondral transplantation.

METHODS

Twenty-five patients with chondral and osteochondral defects of the weight-bearing surfaces were treated by the autologous osteochondral transplantation for the repair of the chondral and osteochondral defects of the unweight-bearing surfaces under arthroscope. According to the shape of the defects, the different dimensions of the osteochondral autograft were selected. All the patients began the training of the continuous passive motion after operation. Six weeks after operation, the patients began to walk in the weight-bearing habitus. However, in the control group, another 25 patients were retrospectively analyzed, who had chondral and osteochondral defects of the weight-bearing surfaces but were treated only by the cleaning and drilling procedures. The scores evaluated by the Brittberg-Peterson scoring scale of the 2 group were 98. 65 +/- 9.87 and 96.98 +/- 8.94 respectively.

RESULTS

The follow-up for 3-24 months after operation revealed that the treated knee joint had a good motion extent. The pain was obviously alleviated. Based on the longitudinal study with the three-dimensional spoiled magnetic resonance imaging (MRI), the signal intensity of the repaired tissues approached to the normal condition. The scores evaluated by the Brittberg-Peterson scoring scale were almost zero 3 months after operation in the experimental group, and the scores were 58.48 +/- 6.98 in the control group. There were significant differences between the experimental group and the control group (P < 0.01).

CONCLUSION

Autologous osteochondral transplantation under arthroscope is a good curative method for the cartilage defects, with advantages of minimal invasiveness and avoidance of rejections resulting from allografts. However, its long-term effect needs to be further studied. The conventional therapies including cleaning and drilling are useful in alleviating the symptoms.

[Engineering 3D cartilage grafts]

The engineering ex vivo of cartilage tissue of predefined size and shape starting from autologous cells has the potential to provide orthopaedic surgeons with functional grafts for the repair of joint injuries. Despite the progress made in the generation and validation of engineered cartilage starting from animal cells, serveral challenges remain to be faced to extend these results to human chondrocytes. This review highlights the need for a highly interdisciplinary approach to effectively introduce engineered cartilage grafts in the routine clinical practice. Issues to be addressed include those related to the biology of chondrocytes, the properties of porous 3D scaffolds, the application of physical stimuli, and the development of economically viable manufacturing systems.

Ingrowth of osteochondral grafts under the influence of growth factors: 6-month results of an animal study

INTRODUCTION

In the age of growth factors and gene therapy, the induction of cartilage healing remains an unsolved problem. Even in autologous grafting, one of the preferred methods of treatment for focal osteochondral lesions, chondral integration remains difficult. This study aims to define a possible positive influence of growth factor augmentation on the ingrowth of these transplants.

MATERIALS AND METHODS

In an ovine model, questions regarding the healing of osteochondral transplants under the influence of two different growth factors were to be addressed. Two osteochondral autologous transplantations (OAT), one in the weight-bearing surface of each femoral condyle, were performed on the ovine knee using the standard operative protocol. One of the grafts was bathed in augmented PBS containing 50 microg bFGF or bone morphogenetic protein (BMP)-2 directly prior to implantation, while the other condyle served as the control. Two groups, consisting of eight sheep each, were evaluated for each growth factor after 6 months.

RESULTS

During the evaluation of all the specimens, neither osteophytes nor synovial changes were observed. The mechanical consistency of the cartilaginous tissue began to reach a level equivalent to the surrounding tissue at 6 months, independent of the use of growth factor. Macroscopically, the superficial border of the transplanted osteochondral plug could easily be outlined in all groups, while the cartilage interface of the bFGF specimens was determined to be less demarcated than the BMP augmented plugs or the controls. Radiographically, a solid osteointegration of the graft could be documented at 6 months in the native and augmented groups. In contrast, integration of the chondral surface of the OAT was not seen macro- or microscopically in any specimen, even though cartilage surfaces remained viable. A firm physical interdigitation of the reconstructed joint surface could not be demonstrated in either of the two augmented groups or the control population. The augmentation with bFGF and BMP-2 stimulated the osseous ingrowth and seems to expedite the remodelling process, but was not able to improve chondral healing.

CONCLUSION

The lack of integration of the cartilaginous portion of the transplanted plugs into the reconstructed joint surface, even following the augmentation with bFGF and BMP-2, does not bode well for the long-term survival of the joint itself.

Meniscus allograft survival in patients with moderate to severe unicompartmental arthritis: a 2- to 7-year follow-up

PURPOSE

We present meniscus allograft survival data at least 2 years from surgery for 45 patients (47 allografts) with significant arthrosis to determine if the meniscus can survive in an arthritic joint.

TYPE OF STUDY

Prospective, longitudinal survival study.

METHODS

Data were collected for 31 men and 14 women, mean age 48 years (range, 14 to 69 years), with preoperative evidence of significant arthrosis and an Outerbridge classification greater than II. Failure is established by previous studies as allograft removal. No patient was lost to follow-up.

RESULTS

The success rate was 42 of 47 allografts (89.4%) with a mean failure time of 4.4 years as assessed by Kaplan-Meier survival analysis. Statistical power is greater than 0.9, with alpha = 0.05 and N = 47. There was significant mean improvement in preoperative versus postoperative self-reported measures of pain, activity, and functioning, with P = .001, P = .004, and P = .001, respectively, as assessed by a Wilcoxon rank-sum test with P = .05.

CONCLUSIONS

Meniscus allografts can survive in a joint with arthrosis, challenging the contraindications of age and arthrosis severity. These results compare favorably with those in previous reports of meniscus allograft survival in patients without arthrosis.

LEVEL OF EVIDENCE

Level IV.

Rabbit articular cartilage defects treated by allogenic chondrocyte transplantation

Articular cartilage defects have a poor capacity for repair. Most of the current treatment options result in the formation of fibro-cartilage, which is functionally inferior to normal hyaline articular cartilage. We studied the effectiveness of allogenic chondrocyte transplantation for focal articular cartilage defects in rabbits. Chondrocytes were cultured in vitro from cartilage harvested from the knee joints of a New Zealand White rabbit. A 3 mm defect was created in the articular cartilage of both knees in other rabbits. The cultured allogenic chondrocytes were transplanted into the defect in the right knees and closed with a periosteal flap, while the defects in the left knees served as controls and were closed with a periosteal flap alone, without chondrocytes. Healing of the defects was assessed at 12 weeks by histological studies. Allogenic chondrocyte transplantation significantly increased the amount of newly formed repair tissue (P=0.04) compared with that found in the control knees. The histological quality score of the repair tissue was significantly better (P=0.05), with more hyaline characteristics in the knees treated with allogenic chondrocytes than in the control knees. Articular cartilage defects treated with allogenic chondrocyte transplantation result in better repair tissue formation with hyaline characteristics than those in control knees.

Who is the ideal candidate for autologous chondrocyte implantation?

We investigated the prognostic indicators for collagen-covered autologous chondrocyte implantation (ACI-C) performed for symptomatic osteochondral defects of the knee. We analysed prospectively 199 patients for up to four years after surgery using the modified Cincinnati score. Arthroscopic assessment and biopsy of the neocartilage was also performed whenever possible. The favourable factors for ACI-C include younger patients with higher pre-operative modified Cincinnati scores, a less than two-year history of symptoms, a single defect, a defect on the trochlea or lateral femoral condyle and patients with fewer than two previous procedures on the index knee. Revision ACI-C in patients with previous ACI and mosaicplasties which had failed produced significantly inferior clinical results. Gender (p = 0.20) and the size of the defect (p = 0.97) did not significantly influence the outcome.

Does subchondral bone affect the fate of osteochondral allografts during storage?

BACKGROUND

Osteochondral allografts currently are hypothermically stored for a minimum of 14 days to a maximum of 28 days before surgical implantation, making storage conditions increasingly important. Previous studies have suggested that graft deterioration during storage may result from degradative factors and residual marrow elements in the subchondral bone.

HYPOTHESIS

Allografts stored with large bone-to-cartilage ratios will be compromised after prolonged storage compared with grafts with minimal bone.

STUDY DESIGN

Controlled laboratory study.

METHODS

Osteochondral plugs were harvested from 16 fresh human femoral condyles and randomly assigned to 1 of 3 groups based on bone-to-cartilage ratios: 1:1, 5:1, or 10:1. These ratios were considered on the basis that the 1:1 ratio is the minimum bone necessary to press-fit an allograft and 10:1 is the present ratio used by tissue banks for allograft storage. After 14 and 28 days of storage at 4 degrees C, the specimens were assessed for viability and viable cell density using confocal microscopy, proteoglycan synthesis by (35)SO4 incorporation, and glycosaminoglycan content.

RESULTS

All grafts underwent a significant decline in viable cell density, proteoglycan synthesis, and chondrocyte viability (particularly in the superficial region) after 14 days of storage, but no differences were observed between the 1:1, 5:1, or 10:1 ratio groups at either day 14 or day 28. In addition, no significant difference was noted in the glycosaminoglycan content in any of the groups.

CONCLUSION

Osteochondral allografts stored with a 10:1 bone-to-cartilage ratio, similar to tissue-banking ratios, performed no worse than allografts stored with minimal bone, suggesting that the bone-to-cartilage ratio plays little to no role in the degradation of allografts during prolonged storage.

CLINICAL RELEVANCE

As the practice of osteochondral allograft resurfacing becomes more commonplace, it is important that surgeons understand the factors that affect graft quality.

Primary stability of osteochondral grafts used in mosaicplasty

PURPOSE

The goal of our experiments was to determine the primary stability of osteochondral grafts used in mosaicplasty. The effect of graft diameter and dilation, as well as multiple grafting, were studied in a porcine model.

METHODS

Single osteochondral grafts, 4.5 and 6.5 mm in diameter, and multiple grafts were transplanted from the trochlea of porcine femurs to the weight-bearing area of the lateral femoral condyle. In the multiple grafting series, 3 grafts 4.5 mm in diameter were transplanted either in a row or in circular fashion. The grafts were first pushed in level with the surrounding cartilage surface, then they were pushed 3 mm below cartilage level. The push-in forces were measured. The effect of graft diameter and the extent of dilation on primary stability were studied as well as the influence of multiple grafting.

RESULTS

In the case of 4.5-mm grafts, the mean level push-in force was 43.5 N, and pushing 3 mm below cartilage level required a mean of 92.5 N (n = 13). In the case of 6.5-mm grafts, level push-in required a mean of 76.2 N, and for pushing 3 mm below cartilage level a mean of 122.2 N force had to be used (n = 14). The length of the drill hole and the dilation were both 20 mm in each setting. When using 20-mm long drill holes and 15-mm dilation length, the values above were found to be 36.6 N and 122.5 N in the case of 4.5-mm grafts (n = 12). Mean level push-in force in the first (row) multiple series was 31.8 N, and pushing 3 mm below cartilage level required a mean of 52.17 N (n = 7). In the second series (circle), level push-in required a mean of 30.44 N, and for pushing 3-mm below cartilage level a mean of 54.33 N force had to be used (n = 9). In the control series (1 single graft) the mean level push-in force was 38.7 N, and pushing 3 mm deeper required a mean of 86.8 N (n = 9).

CONCLUSIONS

These results suggest that grafts of greater diameter are more stable in absolute values and stability may be increased by shorter dilation length, whereas level push-in forces do not increase significantly. There is no difference in primary stability between grafts implanted in a row or in circular fashion, and multiple grafts may not be as stable as single grafts in the initial period after transplantation.

CLINICAL RELEVANCE

This is a randomized, controlled in vitro animal trial that helps us to better understand the primary stability of osteochondral grafts and to refine surgical techniques as well as postoperative protocols.

Transplantation of osteochondral allografts after cold storage

BACKGROUND

Transplantation of fresh osteochondral allografts stored at hypothermia into knee cartilage defects is a common procedure; however, the length of time that allografts can be stored prior to transplantation is controversial and has been determined, in part, by the results of vital stain uptake by chondrocytes. This study was performed to further define the limits of allograft storage.

METHODS

Articular cartilage from six cadavers was stored for up to fifty-one days in tissue-culture media, and histologic sections were evaluated histomorphometrically to quantify the loss of chondrocytes. Samples of the cartilage were also placed into tissue culture to assess cell growth. Animal studies were performed in parallel on sixteen adult baboons with osteochondral allografts transplanted into the medial femoral condyle. Prior to transplantation, all allografts were stored in RPMI-1640 with 10% fetal calf serum at 4 degrees to 6 degrees C for up to eighty-five days. The transplants were graded on their gross and histological appearance, as well as their histochemical properties.

RESULTS

Many of the human samples stored at hypothermia in culture media for up to forty days retained some recognizable chondrocytes, but morphometry showed a gradual, significant decrease in the number of chondrocytes after nine days (p = 0.001). In addition, the cell outgrowth occurred from all specimens stored for up to fifteen days but not in samples stored for longer than thirty-four days. In animal studies, transplanted allograft cartilage that had been stored for less than eighteen days looked smooth and glistening, but grafts stored for over twenty-one days were pale, pitted, fragmented, or yellow, and chondrocytes were absent.

CONCLUSIONS

Time-dependent loss of chondrocytes in articular cartilage stored at hypothermia, especially in specimens stored for longer than fifteen to twenty days, was observed in this study. Cartilage allografts transplanted into nonhuman primates after twenty-one days of storage underwent more severe degenerative changes than allografts that had been stored for less than twenty-one days. These findings suggest caution when transplanting cartilage stored at hypothermia for over twenty days.

The structural properties of an osteochondral cylinder graft-recipient construct on autologous osteochondral transplantation

PURPOSE

The purpose of this study was to investigate the changes in structural properties of an osteochondral cylinder graft-recipient construct after autologous osteochondral transplantation.

METHODS

A full-thickness cylindrical osteochondral defect (5 mm in diameter and 3 mm in depth) was made on the femoral condyle of a mature female Japanese white rabbit using the Osteochondral Autograft Transfer System (OATS; Arthrex, Naples, FL). The defect was repaired with an osteochondral plug (6 mm in diameter and 3 mm in depth) taken from the contralateral femoral condyle using the OATS. The implanted osteochondral grafts were evaluated immediately after surgery and at postoperative weeks 1, 3, 8, and 12. The stiffness of articular cartilage was analyzed using a tactile sensor system (AXIOM, Fukushima, Japan), which measures stiffness based on changes in resonance frequency when a vibrating tactile sensor touches articular cartilage. The specimens were stained with hematoxylin and eosin and serial sections were examined microscopically.

RESULTS

The cartilage stiffness of the graft immediately after surgery was 107,695.1 N/m, which was not statistically different from the normal cartilage stiffness (100,027.5 N/m). The stiffness at postoperative weeks 1, 3, 8, and 12 was 95,386.8, 92,899.3, 95,969.8, and 104,683.7 N/m, respectively. The stiffness at postoperative weeks 1, 3, and 8 was significantly lower than the normal cartilage stiffness and the stiffness at postoperative week 12 was the same as normal cartilage. A new bone formation with an increase of bone trabeculae between the osteochondral cylinder graft and the recipient was observed at postoperative weeks 1, 3, and 8. Thereafter, at postoperative week 12, bone trabeculae decreased to the same level as observed in a normal model due to the progress of bone remodeling.

CONCLUSIONS

The stiffness of articular cartilage of the osteochondral graft was normal at the time the graft was initially placed and at postoperative week 12. However, the stiffness at postoperative weeks 1, 3, and 8 was lower than the normal cartilage stiffness.

CLINICAL RELEVANCE

Care should be taken when planning the rehabilitation program at an early phase after osteochondral transplantation.

Gene expression profiling of human articular cartilage grafts generated by tissue engineering

Cartilage tissue engineering is applied clinically to cover and regenerate articular cartilage defects. In this study autologous human cartilage tissue engineering grafts based on bioresorbable polyglactin/polydioxanone scaffolds were analyzed on the broad molecular level. RNA from freshly isolated, primary and expanded adult articular chondrocytes and from three-dimensional cartilage grafts were used for gene expression profiling using oligonucleotide microarrays. The capacity of cartilage grafts to form cartilage matrix was evaluated after subcutaneous transplantation into nude mice. Gene expression profiling showed reproducibly the regulation of 905 genes and documented that chondrocytes undergo fundamental changes during cartilage tissue engineering regarding chondrocyte metabolism, growth, and differentiation. Three-dimensional assembly of expanded, dedifferentiated chondrocytes initiated the re-differentiation of cells that was accompanied by the reversal of the expression profile of multiple players of the transforming growth factor (TGF) signaling pathway including growth and differentiation factor-5 and inhibitor of differentiation-1 as well as by the induction of typical cartilage-related matrix genes such as type II collagen and cartilage oligomeric matrix protein. Cartilage grafts formed a cartilaginous matrix after transplantation into nude mice. Three-dimensional tissue culture of expanded articular chondrocytes initiates chondrocyte re-differentiation in vitro and leads to the maturation of cartilage grafts towards hyaline cartilage in vivo.

The Postoperative Patellofemoral Joint: Expected Radiological Appearances and Complications

The following learning objectives will be covered in this article: (1) To briefly review the range of surgical options for patellofemoral joint disorders; and (2) to recognize the expected appearances and complications of the postoperative patellofemoral joint on conventional radiography and cross sectional imaging.

Fresh osteochondral allografts for patellofemoral arthritis: long-term followup

Treatment of patellofemoral osteoarthritis in young patients is a challenge for orthopaedic surgeons. Concern about loosening and wear in active young people render arthroplasty more suitable for older patients. Osteochondral allografts may be a good alternative, but reports of experience with such grafts in patellofemoral joints are limited. We retrospectively reviewed our results with fresh osteochondral allografts. Our hypothesis was that these grafts provide relief from osteoarthritis, improve knee function, and delay prosthetic knee replacement. From 1986 to 1999, 14 fresh patellofemoral or patellar allografts were implanted in knees of 11 patients younger than 55 years and diagnosed with advanced secondary osteoarthritis. At last followup (average, 10 years; range, 2.5-17.5 years), eight grafts were in place, four for more than 10 years and two for more than 5 years. Of the nonsurviving allografts, three survived more than 10 years. Radiographs of the knees with intact allografts showed mild or no degenerative changes. Average Knee Society scores improved (preoperative to last followup), with knee scores improving from 46 points (range, 38-60 points) to 82 points (range, 35-100 points) and functional scores from 30 points (range, 10-60 points) to 75 points (range, 20-100 points). Fresh osteochondral allografts can provide relief from the arthritic condition, improve knee function, and delay prosthetic knee replacement.

LEVEL OF EVIDENCE

Therapeutic study, Level IV (case series). See the Guidelines for Authors for a complete description of levels of evidence.

The use of a single osteochondral autograft plug in the treatment of a large osteochondral lesion in the femoral condyle: an experimental study in sheep

BACKGROUND

The use of osteochondral autograft plugs can be restricted because of limited amount of donor material.

HYPOTHESIS

A small osteochondral autograft plug placed in the center of a large defect in a sheep femoral condyle will yield results superior to either an untreated or a bone-grafted defect.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twelve adult sheep underwent bilateral hindlimb surgery. On 1 limb, a 6-mm circular osteochondral autograft plug was placed in the center of a 10-mm circular defect in the medial femoral condyle. The gap between the plug and the condyle was filled with bone graft. On the contralateral side, the defect was either left untreated or filled with bone graft (control specimens). Animals were studied at 6 and 12 months under gross examination, high-resolution radiography, and histologic evaluation.

RESULTS

At 6 months, 4 of 6 plugs healed and showed good maintenance of the joint surface and cartilage viability in the plugs. One plug fractured and resorbed, and 1 plug settled but healed. At 1 year, all 5 plugs healed, 1 having settled slightly (1 animal died earlier). The plug specimens showed better maintenance of the condyle contour at both times, and the central plug had hyaline-appearing cartilage. The control specimens were more irregular, had a fibrocartilage fill, and appeared flatter, although no gross cavitation or collapse was indicated. Composite cartilage scores on histologic evaluation were significantly higher for the plug specimens after 6 months (P = .02) and 1 year (P = .036) compared with controls.

CONCLUSION

At 6 months and 1 year, a 6-mm osteochondral plug placed in a 10-mm defect better preserved the articular surface and contour of the condyle compared to untreated or bone-grafted defects.

CLINICAL RELEVANCE

Osteochondral autograft plugs may be able to treat larger articular lesions without complete fill of the defect.

[Five-year results following autogenous osteochondral transplantation to the femoral head]

The rationale for autogenous osteochondral grafting into necrotic areas of the femoral head is to provide hyaline cartilage for areas of main articular contact pressure. The aim of this study was to present our results of autogenous osteochondral grafting to the femoral head in the treatment of avascular necrosis. The mean follow-up of the five patients was 57 months following autogenous osteochondral grafting to the femoral head using DBCS (diamond bone-cutting system). The number of transplanted cylinders varied between one and three, and the diameter of the cylindrical transplants between 9 and 13 mm. Results were unsatisfactory in four of five hips and these underwent total hip replacement a mean of 49 months following DBCS of the hip. In our hands, osteochondral grafting to the femoral head using DBCS had proven technically possible in restoring the articular surface of the femoral head; however, this operation was associated with unsatisfactory results in four of five cases.

Autologous osteochondral transplantation for the treatment of chondral defects of the knee

Full-thickness chondral defects of weight-bearing articular surfaces of the knee are a difficult condition to treat. Our aim is to evaluate the mid- and long-term functional outcome of the treatment of osteochondral defects of the knee with autologous osteochondral transplantation with the OATS technique. Thirty-six patients (37 procedures) were included in this study. Twenty-three patients were male and thirteen were female with a mean age of 31.9 years (range: 18-48 years). The cause of the defect was OCD in 10 cases, AVN in 2, lateral patellar maltracking in 7, while in the remaining 17 patients the defect was post-traumatic. The lesion was located on the femoral condyles in 26 cases and the patellofemoral joint in the remaining 11. The average area covered was 2.73 cm(2) (range: 0.8-12 cm(2)) and patients were followed for an average of 36.9 months (range: 18-73 months). The average score in their Tegner Activity Scale was 3.76 (range: 1-8), while their score in Activities of Daily Living Scale of the Knee Outcome Survey ranged from 18 to 98 with an average of 72.3. Thirty-two out of 37 patients (86.5%) reported improvement of their pre-operative symptoms. All but 5 patients returned to their previous occupation while 18 went back to sports. No correlation was found between patient age at operation, the size or site of the chondral lesion and the functional outcome. We believe that autologous osteochondral grafting with the OATS technique is a safe and successful treatment option for focal osteochondral defects of the knee. It offers a very satisfactory functional outcome and does not compromise the patient's future options.

Mosaicplasty with photooxidized, mushroom shaped, bovine, osteochondral xenografts in experimental sheep

The goal was to study the performance of mushroom shaped, photooxidized, osteochondral grafts in mosaicplasty focusing on graft stability and survival. Mushroom shaped, photooxidized grafts (6 mm for the cartilaginous head of the mushroom, 3 mm for the stem) were implanted in the medial femoral condyle of 10 sheep. Four transplants were inserted per condyle in an overlapping fashion using the pressfit technique (n=40 grafts in 10 condyles). The grafts were followed for 6 and 12 months. Semi-quantitative evaluation of graft performance was performed using a validated score system. All grafts were mechanically stable at 6 and 12 months with one exception, where the mushroom head broke off. The formation of cystic lesions in the subchondral bone area was minimal. Repopulation of the old photooxidized cartilage was noticed with cells invading the matrix from the subchondral bone area and also from the pannus on the surface. Fusion between host and graft cartilage was observed in some of the grafts at 12 months, while remodeling of the calcified cartilage zone and tidemark was noticed in all grafts. Results scored significantly better for the 6 months compared to the 12 months group if cartilage surface integrity was compared (p<0.05). In all other variables no significant differences were found between groups. Despite moderate graft recession in the 12 months group partial fusion of grafts and functional results were satisfactory. The photooxidized mushroom shaped osteochondral transplants may be a suitable type of graft for functional results in cartilage resurfacing if stable anchorage of the grafts can be achieved.

[Study of the revascularizing properties of the greater omentum for creating prefabricated complex autografts under experimantal conditions]

The revascularizing properties of the greater omentum used as a vascular pedicle for the prefabrication of skin, skin/cartilage or skin/ bone autografts, and their viability after rotation and recipient zone infection were studied in rat experiments. The experiment showed that complexity factor did not have a significant effect on the revascularizing properties of the greater omentum, and required only an insignificant prolongation of prefabrication period. Skin/omental, skin/cartilageous, and skin/bony autografts based on the greater omentum formed by day 7, 14, and 21, respectively. After these periods prefabricated autografts remained viable upon rotation. In case of infection, the survival rate of prefabricated skin/bone autografts, revascularized with two-layer greater omentum, is lower than that of skin/cartilage ones. The technique of prefabrication of autografts including skin, cartilage, and bone, is a promising method for closure of vast multicomponent defects in complicated clinical situations.

Lateral compartment osteoarthritis of the knee after meniscectomy treated by the transplantation of tissue-engineered cartilage and osteochondral plug

Management of osteoarthritis of the knee after meniscectomy has been challenging, especially for young patients, because articular cartilage has very poor healing capacity because of its lack of vessels, nerve supply, and isolation from systemic regulation. Osteoarthritic lesions often involve both femoral and tibial cartilage, requiring treatments for both lesions. We report the case of a 14-year-old girl with lateral compartment osteoarthritis of the knee after a total meniscectomy of the discoid meniscus, who was successfully treated by the transplantation of both tissue-engineered cartilage made ex vivo for a femoral lesion and an autologous osteochondral plug for a tibial lesion. We treated both femoral and tibial cartilage defects simultaneously with this procedure. We confirmed cartilaginous regeneration in both femoral and tibial lesions at second-look arthroscopy. This procedure is one option to prevent further development of osteoarthritis in young patients.