Histologic analysis of the implanted cartilage in an exact-fit osteochondral transplantation model

Enhancement of cartilage repair through the addition of growth plate chondrocytes in an immature skeleton animal model

Background

The treatment of articular cartilage damage is a major clinical problem. More often, this clinical issue affects children, which forces doctors to find the best treatment method.

Methods

The aim of this experimental study on 2-month-old Landrace pigs was to compare the results of two cartilage defect treatments: (1) filling the cartilage defect with a scaffold incubated with bone marrow aspirate supplemented with growth plate chondrocytes (the CELLS group) and (2) filling the cartilage defect with an empty scaffold implanted after drilling the subchondral bone (the CTRL group). The treatment outcomes were assessed macroscopically and microscopically.

Results

Based on the macroscopic evaluation, all animals showed a nearly normal morphology, with an average of 9.66/12 points (CTRL) and 10.44/12 points (CELLS). Based on the microscopic evaluation, 1 very good result and 8 good results were obtained in the CTRL group, with an average of 70.44%, while 5 very good results and 4 good results were obtained in the CELLS group, with an average of 79.61%.

Conclusions

(1) Growth plate chondrocytes have high chondrogenic potential and thus offer new possibilities for cartilage cell therapy. (2) The implantation of a scaffold loaded with bone marrow-derived MSCs (mesenchymal stem cells) and growth plate chondrocytes into a cartilage defect is a good therapeutic method in immature patients. (3) Cartilage repair based on a scaffold with bone marrow aspirate-derived cells supplemented with autologous growth plate chondrocytes achieves better results than repair with marrow stimulation and a hyaluronic acid-based scaffold (overall microscopic rating). (4) Chondrocyte clustering is a manifestation of the cartilage repair process but requires further observation.

Electronic supplementary material

The online version of this article (10.1186/s13018-019-1302-y) contains supplementary material, which is available to authorized users.

Costal Osteochondral Autograft for Advanced Osteochondritis Dissecans of the Humeral Capitellum in Adolescent and Young Adult Athletes: Clinical Outcomes with a Mean Follow-up of 4.8 Years

BACKGROUND

Costal osteochondral grafting is a technique to achieve anatomical and biological repair of articular defects. Some small series of clinical applications of this procedure for advanced osteochondritis dissecans of the humeral capitellum, with short-term follow-up, have been reported; however, longer-term outcomes remain unclear. The purpose of this study was to clarify longer-term clinical outcomes of costal osteochondral autografts in the treatment of advanced osteochondritis dissecans of the humeral capitellum.

METHODS

Seventy-two patients with an osteochondral defect of the humeral capitellum were treated with costal osteochondral autograft and followed for a minimum of 3 years (mean follow-up, 57 months; range, 36 to 147 months). The mean patient age was 14.3 years. Clinical outcomes, including elbow range of motion, Timmerman and Andrews clinical rating score, donor-site morbidity, responses to a questionnaire regarding a return to sporting activities, and radiographic findings, were evaluated.

RESULTS

The mean elbow range of extension/flexion increased significantly, from -21°/122° preoperatively to -4°/136° postoperatively (p < 0.001). The mean clinical rating score improved significantly, from 101 to 190 by the latest follow-up (p < 0.001). The overall clinical score-based assessment was excellent for 60 patients, good for 9, and fair for 3. Seventy of the 72 patients returned to their original sport. The remaining 2 patients had changed sporting activities before surgery and did not return to baseball, despite satisfactory clinical results.

CONCLUSIONS

Costal osteochondral autograft successfully achieved anatomical and biological reconstruction in the treatment of advanced osteochondritis dissecans of the humeral capitellum.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Fresh Osteochondral Allograft Versus Autograft: Twelve-Month Results in Isolated Canine Knee Defects

BACKGROUND

Osteochondral autografts and allografts have been widely used in the treatment of isolated grade 4 articular cartilage lesions of the knee. However, there is a paucity of literature regarding the basic science investigating the direct comparison between fresh osteochondral allografts to autografts.

HYPOTHESIS

At 12 months, fresh osteochondral allografts are equal to autografts with respect to function, bony incorporation into host bone, and chondrocyte viability.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eight adult mongrel dogs underwent bilateral hindlimb osteochondral graft implantation in the knee after creation of an acute Outerbridge grade 4 cartilage defect. One hindlimb of each dog knee received an autograft, and the contralateral knee received an allograft. All dogs were sacrificed at 12 months. Graft analysis included gross examination, radiographs, magnetic resonance imaging (MRI), biomechanical testing, and histology.

RESULTS

MRI demonstrated excellent bony incorporation of both autografts and allografts, except for 1 allograft that revealed partial incorporation. Histologic examination of cartilage showed intact hyaline appearance for both autografts and allografts, with fibrocartilage at the host-graft interface of both. Biomechanical testing demonstrated no significant difference between allografts and autografts (P = .76). Furthermore, no significant difference was observed between allografts and the native cartilage with biomechanical testing (P = .84).

CONCLUSION

After 12 months from time of implantation, fresh osteochondral allograft tissue and autograft tissue in this study were not statistically different with respect to biomechanical properties, gross morphology, bony incorporation, or overall histologic characteristics. When compared with the previously reported 6-month incorporation rates, there was improved allograft and autograft incorporation at 12 months.

CLINICAL RELEVANCE

With no significant differences in gross examination, radiographs, MRI, biomechanical testing, or histology in the canine model, the use of allograft tissue to treat osteochondral defects may eliminate the morbidity associated with autograft harvest.

Temporal in vivo assessment of fresh osteochondral allograft transplants to the distal aspect of the femur by dGEMRIC (delayed gadolinium-enhanced MRI of cartilage) and zonal T2 mapping MRI

BACKGROUND

Zonal T2 mapping and dGEMRIC (delayed gadolinium-enhanced magnetic resonance imaging of cartilage) are diagnostic quantitative techniques to evaluate the biochemical health of articular cartilage. We adapted these techniques to investigate the results of osteochondral allograft transplantation and correlated the findings with patient-reported outcomes.

METHODS

Nine patients with contained ICRS (International Cartilage Repair Society) grade-4 defects of the articular portion of a femoral condyle were treated with fresh osteochondral allografts and were evaluated prospectively with dGEMRIC and T2 mapping before and after gadolinium administration. The KOOS (Knee Injury Osteoarthritis Outcome Score) and IKDC (International Knee Documentation Committee) subjective scores were obtained at baseline and at one and two years postoperatively. For quantitative T2 mapping, regions of interest were drawn in the deep and superficial layers of allograft and control cartilage. For dGEMRIC analyses, the relaxation rate, post-gadolinium change in relaxation rate, and ratio between changes in the allograft and control regions of interest were calculated from T1 values.

RESULTS

The mean ratio between the post-gadolinium changes in the allograft and control cartilage was 1.13 at one year and 1.55 at two years, and the ratio increased in eight of nine patients from one to two years. There was no difference between the mean T2 values in the deep zone of the allograft and control cartilage at one or two years (p > 0.05), but mean T2 values were higher in the superficial zone of the allograft cartilage at one (p < 0.0001) and two (p < 0.028) years. The mean improvement from baseline was significant at one and two years for the IKDC and all five KOOS subdomains (p < 0.05). All or nearly all patients showed improvements in all clinical outcomes scores at one year.

CONCLUSIONS

Functional MRI techniques can be applied to noninvasively assess the biochemical health of cartilage after osteochondral allograft transplantation. The MRI findings correlated with certain patient-reported outcomes in the early postoperative period. Relative glycosaminoglycan content and the collagen structure of allograft cartilage may undergo time-dependent degeneration. A patient's perception of clinical outcome and quality of life is likely multifactorial and is impacted by more than the health of the allograft cartilage.

Incongruity affecting osteochondral repair by mosaicplasty technique in an animal model

OBJECTIVE

To compare the influence of the different osteochondral incongruity grades on the osteochondral repair by the mosaicplasty technique in a goat model.

METHODS

The acute defects were created in the weight-bearing area of the medial femoral condyle of the goats. Mosaicplasty was done to repair the defects. While implanting the cylindrical osteochondral grafts, different osteochondral sunk, or elevated incongruities were created. The goats were killed 12 weeks after operation to receive gross and histology observation, which was evaluated by the histological grading scale of O'Driscoll et al. The specimens were also taken for transmission electron microscope examination. Two factors analysis of variance and Student-Newman-Kewls test were used to compare the specimen.

RESULTS

Minimal steps, which were less than the thickness of cartilage, possess a capacity for remodeling that can correct initial incongruities while preserving hyaline characteristics. However, the step more than the thickness of cartilage could not be repaired satisfactorily.

CONCLUSIONS

The incongruity could have an influence on the repair by the mosaicplasty technique in a goat model. The limited incongruity could be repaired by a vigorous remodeling process.

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.

Nanotechnology and mesenchymal stem cells with chondrocytes in prevention of partial growth plate arrest in pigs

INTRODUCTION

This study describes the results achieved using a combination of allogeneic mesenchymal stem cells (MSCs) with chondrocytes (CHC) and a new scaffold consisting of type-I collagen and chitosan nanofibers in the prevention of partial growth plate arrest after iatrogenic injury in pigs.

MATERIAL AND METHODS

The miniature pig was selected as an experimental model to compare the results in the left femoral bones (MSCs and CHC in scaffold transplantation into the iatrogenic partial distal growth plate defect) and right femoral bones (scaffold alone transplantation). The experimental group consisted of 10 animals. Bone marrow from os ilium as the source of MSCs was used. A porous cylinder consisting of 0.5% by weight type-I collagen and 30% by weight chitosan, was the optimal choice. The length of the bone and angular deformity of distal femur after the healing period was measured and the quality and structure of the newly formed cartilage was histologically examined.

RESULTS

Transplantation of the composite scaffold in combination with MSCs and chondrocytes led to the prevention of growth disorder and angular deformity in the distal epiphysis of the left femur. Compared to the right (control) femur, tissue similar to hyaline cartilage with signs of columnar organization typical of the growth plate occurred in most cases.

CONCLUSIONS

The promising results of this study reveal the new and effective means for the prevention of bone bridge formation after growth plate injury.

A study on repair of porcine articular cartilage defects with tissue-engineered cartilage constructed in vivo by composite scaffold materials

The study was performed to find out a promising injectable composite scaffold for cartilage tissue engineering. By using a composite of allogenous cartilage microparticle acellular tissue matrix (CMACTM) and fibrin glue (Fg) as injectable scaffold materials, tissue-engineered cartilage was constructed in vivo, and the effects of which on the repair of porcine articular cartilage defects were observed. CMACTM was obtained from domestic pigs. The chondrocytes were prepared from experimental mini-type pigs and expanded in vitro. Fg was used as a scaffold material. The composite of CMACTM, second-passage chondrocytes, and Fg was replanted to the articular cartilage defective regions in autologous mini-type pig by injection. At 12 weeks after replantation, samples were collected and analyzed by general observation and histologic staining.The constructed tissue-engineered cartilage exhibited a good efficiency in the repair of articular cartilage defects. Cells in the constructed tissue-engineered cartilage grew well and were able to secrete cartilaginous matrix. The tissue-engineered cartilage showed a better biologic performance than the control. A composite of allogenous CMACTM and Fg was a promising injectable scaffold for cartilage tissue engineering, which could be used to repair articular cartilage defects by a minimally invasive procedure.

A comparison of open versus arthroscopic harvesting of osteochondral autografts

Osteochondral autograft transfer is a technique for treatment of traumatic and degenerative cartilage lesions. A graft in which the cartilage cap is oriented perpendicular to the long axis of the graft is ideal because it can both restore the cartilage tidemark and minimize articular step-off at the recipient site. This study determines if osteochondral harvest technique (arthroscopic versus mini-open) or donor site location affects suitable graft harvest. One hundred and twenty eight osteochondral grafts were harvested in 16 cadaver knees utilizing a 7 mm OATS chisel from four donor sites: lateral supracondylar ridge, lateral femoral condyle, lateral intercondylar notch and medial femoral condyle. Mini-open and arthroscopic harvesting techniques were equally employed. Radiographic methods were used to analyze graft perpendicularity. Statistical analysis comparing graft suitability based on technique and donor site location was performed. There were no statistically significant differences (p>0.05) in graft suitability regardless of the technique used or donor site location. 69% of arthroscopic and 56% of mini-open graft harvest were considered suitable, possessing a cartilage cap and graft axis angle that would create less than 1 mm of articular incongruity. Incongruity results when the angle between the subchondral bone plug long axis and cartilage interface is greater than 74 degrees . There is no difference in the quality of osteochondral grafts harvested from the knee regardless of technique or donor site used. Osteochondral graft diameter should be kept at or less than 7 mm because of the high percentage of unacceptable grafts with increasing chisel sizes.

Mechanical effects of surgical procedures on osteochondral grafts elucidated by osmotic loading and real-time ultrasound

Introduction

Osteochondral grafts have become popular for treating small, isolated and full-thickness cartilage lesions. It is recommended that a slightly oversized, rather than an exact-sized, osteochondral plug is transplanted to achieve a tight fit. Consequently, impacting forces are required to insert the osteochondral plug into the recipient site. However, it remains controversial whether these impacting forces affect the biomechanical condition of the grafted articular cartilage. The present study aimed to investigate the mechanical effects of osteochondral plug implantation using osmotic loading and real-time ultrasound.

Methods

A full-thickness cylindrical osteochondral defect (diameter, 3.5 mm; depth, 5 mm) was created in the lateral lower quarter of the patella. Using graft-harvesting instruments, an osteochondral plug (diameter, 3.5 mm as exact-size or 4.5 mm as oversize; depth, 5 mm) was harvested from the lateral upper quarter of the patella and transplanted into the defect. Intact patella was used as a control. The samples were monitored by real-time ultrasound during sequential changes of the bathing solution from 0.15 M to 2 M saline (shrinkage phase) and back to 0.15 M saline (swelling phase). For cartilage sample assessment, three indices were selected, namely the change in amplitude from the cartilage surface (amplitude recovery rate: ARR) and the maximum echo shifts from the cartilage surface and the cartilage-bone interface.

Results

The ARR is closely related to the cartilage surface integrity, while the echo shifts from the cartilage surface and the cartilage-bone interface are closely related to tissue deformation and NaCl diffusion, respectively. The ARR values of the oversized plugs were significantly lower than those of the control and exact-sized plugs. Regarding the maximum echo shifts from the cartilage surface and the cartilage-bone interface, no significant differences were observed among the three groups.

Conclusions

These findings demonstrated that osmotic loading and real-time ultrasound were able to assess the mechanical condition of cartilage plugs after osteochondral grafting. In particular, the ARR was able to detect damage to the superficial collagen network in a non-destructive manner. Therefore, osmotic loading and real-time ultrasound are promising as minimally invasive methods for evaluating cartilage damage in the superficial zone after trauma or impact loading for osteochondral grafting.

Chondrocyte death and cartilage degradation after autologous osteochondral transplantation surgery in a rabbit model

BACKGROUND

Autologous osteochondral transplantation surgery requires an impact force on the graft that may cause chondrocyte death and matrix degradation. This study attempted to determine the degree to which this occurs in a rabbit model shortly after the procedure.

HYPOTHESIS

Impaction of a press-fit autologous osteochondral graft in vivo results in chondrocyte necrosis, apoptosis, and matrix degradation at early time points.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twenty New Zealand White rabbits underwent unilateral osteochondral transplantation (OT) surgeries, and 10, bilateral sham surgeries. Fifteen animals were sacrificed at time zero (10 sham-0 limbs, 10 OT-0 limbs), and 15, 4 days after surgery (10 sham-4 limbs, 10 OT-4 limbs). Chondrocyte viability/necrosis was determined with cell vital staining. Chondrocyte apoptosis was determined by TUNEL, Bcl-2, and M30 assays. Cartilage matrix degradation was determined by routine light and polarized light microscopy and COL2-3/4C(short) immunohistochemistry. Statistical analysis was performed with a 2-way analysis of variance (P < .05).

RESULTS

There were significantly fewer viable cells in OT-4 than in sham-4. A similar difference in cell viability was found in OT-0 versus sham-0. There were more TUNEL-positive cells in OT-4 as compared with OT-0, sham-0, and sham-4; however, there was little or no staining of Bcl-2 and M30. Mankin scores were higher in both OT groups versus both sham groups at time zero and day 4. The OT-4 group had positive staining for COL2-3/4C(short) that corresponded with a loss of collagen birefringence at the superficial zone.

CONCLUSION

Osteochondral transplantation procedures performed by tamping a press-fit graft induce chondrocyte necrosis and matrix metalloproteinase-mediated cartilage matrix degradation. However, apoptosis was not found to a major contributor to cell death in this model.

CLINICAL RELEVANCE

Results of osteochondral transplantation procedures may be improved by atraumatic insertion and fixation techniques or by pharmacologic agents that can block these degradative processes.

Preclinical animal models in single site cartilage defect testing: a systematic review

OBJECTIVE

Review the literature for single site cartilage defect research and evaluate the respective strengths and weaknesses of different preclinical animal models.

METHOD

A literature search for animal models evaluating single site cartilage defects was performed. Variables tabulated and analyzed included animal species, age and number, defect depth and diameter and study duration. Cluster analyses were then used to separate animals with only distal femoral defects into similar groups based on defect dimensions. Representative human studies were included allowing comparison of common clinical lesions to animal models. The suitability of each species for single site cartilage defect research and its relevance to clinical human practice is then discussed.

RESULTS

One hundred thirteen studies relating to single site cartilage defects were reviewed. Cluster analysis included 101 studies and placed the murine, laprine, ovine, canine, porcine and caprine models in group 1. Group 2 contained ovine, canine, porcine, caprine and equine models. Group 3 contained only equine models and humans. Species in each group are similar with regard to defect dimensions. Some species occur in multiple groups reflecting utilization of a variety defect sizes. We report and discuss factors to be considered when selecting a preclinical animal model for single site cartilage defect research.

DISCUSSION

Standardization of study design and outcome parameters would help to compare different studies evaluating various novel therapeutic concepts. Comparison to the human clinical counterpart during study design may help increase the predictive value of preclinical research using animal models and improve the process of developing efficacious therapies.

Osteochondral autologous transplantation for the treatment of full-thickness cartilage defects of the shoulder

We describe the outcome at a mean follow-up of 8.75 years (7.6 to 9.8) of seven patients who had undergone osteochondral autologous transplantation for full-thickness cartilage defects of the shoulder between 1998 and 2000. These patients have been described previously at a mean of 32.6 months when eight were included. One patient has been lost to follow-up. The outcome was assessed by the Constant shoulder score and the Lysholm knee score to assess any donor-site morbidity. Standard radiographs and MR scores were obtained and compared with the pre-operative findings and the results from the previous review.

No patient required any further surgery on the shoulder. The mean Constant score improved significantly until the final follow-up (p = 0.018). The Lysholm score remained excellent throughout. There was a significant progression of osteoarthritic changes from the initial surgery to the first and final follow-up but this did not appear to be related to the size of the defect, the number of cylinders required or the Constant score (p = 0.016). MRI showed that all except one patient had a congruent joint surface at the defect with full bony integration of all osteochondral cylinders.

The results have remained satisfactory over a longer period with very good objective and subjective findings.

[Autologous osteochondral transplants]

Osteochondral transplantation is a treatment option for restoring lesions of the cartilage surface and the underlying subchondral bone. For this technique, osteochondral cylinders are taken from less loaded regions of the knee joint and brought into the defect. It is based on press-fit implantation of osteochondral cylinders that are harvested from the mediocranial or laterocranial aspect of the patellofemoral joint with subsequent stable bony integration of the transplant. Indications for osteochondral transplantation must consider clinical, radiological, and magnetic resonance aspects, and concomitant pathologies of the joint should be eliminated. Isolated grade III and IV cartilage lesions in the load-bearing area of the medial or lateral femoral condyle are considered to be ideal indications for osteochondral transplantations. Further indications are retropatellar defects and lesions of the medial aspect of the talus. The technique is established for defects from 1 cm2 to 3 cm2. At this time, osteochondral transplantation is the only surgical method to achieve long-term coverage of the defect with hyaline cartilage. Donor site morbidity at the patellofemoral joint needs to be discussed because, particularly after the harvest of several cylinders, pain syndromes can develop. Therefore, the technique should be limited to two cylinders with a maximum diameter of 12 mm and one further cylinder with a smaller diameter.

The fate of osteochondral grafts after autologous osteochondral transplantation: a one-year follow-up study in a minipig model

INTRODUCTION

Because articular cartilage shows little intrinsic capacity of spontaneous regeneration, a variety of treatment options are currently at use to repair cartilage damage. One of these is the autologous osteochondral transplantation (AOT). The aim of the present work was to study the histological changes during the progress of 1 year after AOT in the knee joint.

MATERIALS AND METHODS

Twelve Minipigs underwent an AOT on the medial femoral condyles of both knees using cooled diamond studded trephines with a diameter of the grafts of 4.6 mm. Three animals were sacrificed at each 2, 8, 26 and 52 weeks after the operation. The condyles were analyzed histologically and immunohistologically for collagen types I and II.

RESULTS

A successful bony incorporation was observed in all specimens. The transplant demonstrated an increasingly stable integration of the chondral matrix into the cartilage of the surrounding femoral condyle. At 52 weeks after the operations 5 of 6 condyles showed a chondral integration at least at one side of the graft. Immunohistologically all specimens showed physiological staining characteristics up to 52 weeks after operation. The quality of the chondral part of the graft showed a wide range of variations, ranging from vital tissue resembling native cartilage after 52 weeks, to severe degenerative signs beginning 2 weeks after operation and ending at 52 weeks with deep fissures fragmenting the cartilage and the complete loss of vital cells.

CONCLUSION

The press-fit technique allows a stable bony incorporation. A chondral integration of the graft seems to occur, provided that a close contact between the interfaces can be achieved. Present results demonstrate a vital cartilagenous transplant for up to 52 weeks. However, some specimens showed in part severe degenerative signs. A possible explanation is an insufficient cooling of the trephines in relation to the small diameter of the grafts used in the minipig model. The collagen network seems not to be affected for up to 52 weeks.

Transduction of anti-cell death protein FNK suppresses graft degeneration after autologous cylindrical osteochondral transplantation

This study shows that artificial super antiapoptotic FNK protein fused with a protein transduction domain (PTD-FNK) maintains the quality of osteochondral transplant by preventing chondrocyte death. Cylindrical osteochondral grafts were obtained from enhanced green fluorescent protein (EGFP)-expressing transgenic rats, in which living chondrocytes express green fluorescence, and submerged into medium containing PTD-FNK, followed by transplantation into cartilage defects of wild-type rats by impact insertion simulating autologous transplantation. The tissues were histologically evaluated by hematoxylin-eosin and Safranin-O staining. At 1 week, chondrocyte alignment was normal in the PTD-FNK treatment group, whereas all grafts without PTD-FNK treatment showed mixed cluster cell distribution. At 4 weeks, all grafts with PTD-FNK treatment showed almost normal matrix, whereas two grafts without PTD-FNK treatment showed fibrocartilage. Notably, all grafts with PTD-FNK retained high intensity of Safranin-O staining, but all grafts without PTD-FNK largely lost Safranin-O staining. PTD-FNK significantly suppressed a decrease in the survival rate and the density of EGFP-positive cells at 1 and 2 weeks, and this tendency continued at 4 weeks. The results of terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP)-nick end-labeling staining showed that PTD-FNK inhibited cell death, indicating that PTD-FNK protects chondrocyte death and suppresses graft degeneration.

The effect of low-intensity pulsed ultrasound on autologous osteochondral plugs in a canine model

BACKGROUND

Low-intensity pulsed ultrasound promotes the enchondral portion of fracture healing, which has a direct stimulatory effect on cartilage formation and maturation.

HYPOTHESIS

Daily ultrasound treatment positively affects the repair and incorporation of modified autologous osteochondral plugs in a canine model.

STUDY DESIGN

Controlled laboratory study.

METHODS

In 18 dogs, 2 autologous plugs separated from host cartilage by a 1.5-mm gap were created on the medial femoral condyle in both knees of each dog. One knee was treated daily with a clinically available ultrasound bone stimulator. Animals were sacrificed after 6 and 12 weeks of therapy and the articular surfaces evaluated grossly and histologically.

RESULTS

Ultrasound-treated sites had significantly improved gross appearance at 6 weeks and histologic appearance at 6 and 12 weeks. The interface repair tissue of ultrasound-treated sites had a more normal translucent appearance than control sites. Ultrasound treatment improved the cell morphologic characteristics of the interface repair tissue and increased subchondral bone regeneration. Bonding of the interface repair tissue between plug and adjacent cartilage was significantly improved compared with control sites.

CONCLUSION

Low-intensity pulsed ultrasound improved interface cartilage repair of autologous osteochondral plugs compared with controls in a canine model.

CLINICAL RELEVANCE

Improvements in the quality and rate of repair of autologous osteochondral plugs may reduce postoperative recovery time and improve functional outcome.

Costal osteochondral grafts for osteochondritis dissecans of the capitulum humeri

The objective of the treatment for osteochondritis dissecans of the humeral capitulum is to prevent the occurrence of osteoarthritis and to allow the patients to return to throwing activities. In repairing osteochondral defects in advanced osteochondritis dissecans of the humeral capitulum after free body removal, we have performed block-shaped costal osteochondral grafting in 18 elbows since 1997. A block-shaped graft harvested from the transitional area between the rib and its associated cartilage was implanted to the osteochondral defect. This method allows the osteochondral defect to be repaired with uniform hyaline cartilaginous articular surface without any effect to other joints. Donor site no longer causes pain at 2 or 3 days after surgery. The purpose of this study is to describe the history, indications, and the surgical techniques of costal osteochondral grafting for advanced osteochondritis dissecans of the capitulum.

Clinical outcome and histologic findings of costal osteochondral grafts for cartilage defects in finger joints

PURPOSE

For the purpose of achieving anatomical reduction as precisely as possible, we performed osteochondral grafting from the costo-osteochondral junction in 16 patients (17 joints) with posttraumatic articular cartilage injury or avascular necrosis in finger joints. The purpose of this study was to review our series of costal osteochondral grafts in order to determine the practicality, effectiveness, and functionality of this grafting technique in a clinical setting.

METHODS

Patients were followed for at least 18 months postoperatively (18-57 months; average, 28 months). The injured joints included 3 metacarpophalangeal, 9 proximal interphalangeal, 3 distal interphalangeal, and 2 thumb interphalangeal joints. The defect accounted for 50% to 100% of the articular surface (average, 63%).

RESULTS

The average time until bone union of the graft was 58 days. The mean arc of motion was 13 degrees before surgery versus 58 degrees after surgery, with a mean increase of 45 degrees . In 7 patients (8 joints), an extremely small portion (approximately 1 x 1 mm in size and thinner than 0.1 mm) of the implanted cartilage was obtained via biopsy using a scalpel with the consent of the patient at the time of screw removal and was used to prepare histologic specimens, which revealed scattered chondrocytes within the matrix without differences from normal hyaline cartilage in any. The chondrocytes in the grafts appeared viable, and the reconstruction of the joint surface could be confirmed histologically.

CONCLUSIONS

Osteochondral grafting from the costo-osteochondral junction achieves excellent reconstruction of the injured joint without affecting other joints. This technique is particularly beneficial in cases where it is difficult to obtain allograft donors, as is often the case in Japan. Despite these encouraging findings in this small series, we believe that it is necessary to conduct further studies of this method over a longer period.

Arthroscopic debridement for knee osteoarthritis

BACKGROUND

Knee osteoarthritis (OA) is a progressive disease that initially affects the articular cartilage. Observational studies have shown benefits for arthroscopic debridement (AD) on the osteoarthritic knee, but other recent studies have yielded conflicting results that suggest AD may not be effective.

OBJECTIVES

To identify the effectiveness of AD in knee OA on pain and function.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 2, 2006); MEDLINE (1966 to August, 2006); CINAHL (1982 to 2006); EMBASE (1988 to 2006) and Web of Science (1900 to 2006) and screened the bibliographies, reference lists and cited web sites of papers.

SELECTION CRITERIA

We included randomised controlled trials (RCT) or controlled clinical trials (CCT) assessing effectiveness of AD compared to another surgical procedure, including sham or placebo surgery and other non-surgical interventions, in patients with a diagnosis of primary or secondary OA of the knees, who did not have other joint involvement or conditions requiring long term use of non-steroidal anti-inflammatory drugs (NSAIDs). The main outcomes were pain relief and improved function of the knee.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion, assessed trial quality and extracted the data. Results are presented using weighted mean difference (WMD) for continuous data and relative risk (RR) for dichotomous data, and the number needed to treat to benefit (NNTB) or harm (NNTH).

MAIN RESULTS

Three RCTs were included with a total of 271 patients. They had different comparison groups and a moderate risk of bias. One study compared AD with lavage and with sham surgery. Compared to lavage the study found no significant difference. Compared to sham surgery placebo, the study found worse outcomes for AD at two weeks (WMD for pain 8.7, 95% CI 1.7 to 15.8, and function 7.7, 95% CI 1.1 to 14.3; NNTH=5) and no significant difference at two years. The second trial, at higher risk of bias, compared AD and arthroscopic washout, and found that AD significantly reduced knee pain compared to washout at five years (RR 5.5, 95% CI 1.7 to 15.5; NNTB=3). The third trial, also at higher risk of bias, compared AD to closed-needle lavage, and found no significant difference.

AUTHORS' CONCLUSIONS

There is 'gold' level evidence that AD has no benefit for undiscriminated OA (mechanical or inflammatory causes).

The Regenerative Effects of Platelet-Rich Plasma on Meniscal CellsIn Vitroand ItsIn VivoApplication with Biodegradable Gelatin Hydrogel

The objective of the study was to test the hypothesis that platelet-rich plasma (PRP) enhances meniscal tissue regeneration in vitro and in vivo. In the in vitro study, monolayer meniscal cell cultures were prepared, and 3-(4,5-dimethylthiazol-2yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt assay and 5-bromo-2'-deoxyuridine assay were performed to assess proliferative behavior in the presence of PRP. Alcian blue assay was performed to assess extracellular matrix (ECM) synthesis. To detect the fibrocartilage-related messenger ribonucleic acid (mRNA) expressions, real-time polymerase chain reaction was performed. In the in vivo study, 1.5-mm-diameter full-thickness defects were created in the avascular region of rabbit meniscus. Gelatin hydrogel (GH) was used as the drug delivery system for PRP growth factors. The defects were filled as follows: Group A, GH with PRP; Group B, GH with platelet-poor plasma; Group C, GH only. Each group was evaluated histologically at 4, 8, and 12 weeks after surgery. PRP stimulated deoxyribonucleic acid synthesis and ECM synthesis (p<0.05). Meniscal cells cultured with PRP showed greater mRNA expression of biglycan and decorin (p<0.05). Histological findings showed that remnants of gelatin hydrogels existed at 4 weeks, indicating that the hydrogels could control release for approximately 4 weeks. Histological scoring of the defect sites at 12 weeks revealed significantly better meniscal repair in animals that received PRP with GH than in the other two groups. These findings suggest that PRP enhances the healing of meniscal defects.

Autologous osteochondral mosaicplasty grafting

Successful management of chondral and osteochondral defects of the weight-bearing joint surfaces has always been a challenge for orthopedic surgeons and rehabilitation specialists. Autologous osteochondral mosaic transplantation technique is one of the recently evolved methods to create hyaline or hyaline-like repair tissue in the pathologic area. Clinical evaluation, various imaging techniques, arthroscopy (second look), histological examination of biopsy samples, and measurements of cartilage mechanical properties are used to evaluate the merits of outcomes and quality of the transplanted cartilage. According to our investigations, good to excellent results were achieved in more than 92% of patients treated with femoral condylar implantations, 87% of those treated with tibial resurfacing, 79% of those treated with patellar and/or trochlear mosaicplasties, and 94% of those treated with talar procedures. Long-term donor-site discrepancies, assessed with use of the Bandi Score, showed that patients had 3% morbidity after mosaicplasty. Sixty-nine of 89 patients who were followed up with a second-look arthroscopy showed congruent gliding surfaces, histological evidence of the survival of the transplanted hyaline cartilage, and fibrocartilage filling of the donor sites. In a series of 831 consecutive patients, very few complications have been observed. These included 4 deep infections and 36 painful postoperative intra-articular bleedings. On the basis of these results and those of other similar studies, autologous osteochondral mosaicplasty appears to be a promising alternative for the treatment of small- and medium-sized focal chondral and osteochondral defects of the weight-bearing surfaces of the knee and other weight-bearing synovial joints.

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.

The Repair Response to Osteochondral Implant Types in a Rabbit Model

Current treatments for damaged articular cartilage (i.e., shaving the articular surface, perforation or abrasion of the subchondral bone, and resurfacing with periosteal and perichondrial resurfacing) often produce fibrocartilage, or hyaline-appearing repair that is not sustained over time (Henche 1967, Ligament and Articular Cartilage Injuries. Springer-Verlag, New York, NY, pp. 157-164; Insall 1974, Clin. Orthop. 101: 61-67; Mitchell and Shepard 1976, J. Bone Joint Surg. [Am.] 58: 230-233; O'Driscoll et al. 1986, J. Bone Joint Surg. [Am.] 68: 1017-1035; 1989, Trans. Orthop. Res. Soc. 14: 145; Kim et al. 1991, J. Bone Joint Surg. [Am.] 73: 1301-1315). Autologous chondrocyte transplantation, although promising, requires two surgeries, has site-dependent and patient age limitations, and has unknown long-term donor site morbidity (Brittberg et al. 1994, N Engl. J. Med. 331: 889-895; Minas 2003, Orthopedics 26: 945-947; Peterson et al. 2003, J. Bone Joint Surg. Am. 85-A(Suppl. 2): S17-S24). Osteochondral allografts remain a widely used method of articular resurfacing to delay arthritic progression. The present study compared the histological response to four types of osteochondral implants in a rabbit model: autograft, frozen, freeze-dried, and fresh implants. Specimens implanted in the femoral groove were harvested at 6 and 12 weeks. Results showed similar restoration of the joint surface regardless of implant type, with a trend toward better repair at the later timepoint. As has been observed in other studies (Frenkel et al. 1997, J. Bone Joint Surg. 79B: 281-286; Toolan et al. 1998, J. Biomed. Mater. Res. 41: 244-250), each group in this study had at least one specimen in which a healthy-appearing surface on the implant was not well-integrated with host tissues. Although the differences were not statistically significant, freeze-dried implants at both timepoints had the best histological scores. The osteochondral grafts tested successfully restored the gross joint surface and congruity. At 12 weeks, no significant differences were observed between the various allografts and autologous osteochondral grafts.

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.

Arthroscopic chondral osseous autograft transplantation (COR procedure) for femoral defects

PURPOSE

Localized, full-thickness articular cartilage defects of the femoral condyle are often found unexpectedly. An arthroscopic repair technique that transplants chondral osseous replacement plugs to fill the defect (the COR technique; Mitek Products, Westwood, MA) offers an immediate solution for these lesions. The purpose of this study was to review the clinical and radiographic results of femoral chondral osseous replacement for full-thickness articular cartilage lesions between 2.5 and 1.0 cm in diameter.

TYPE OF STUDY

Case series.

METHODS

A retrospective review of a consecutive series of patients from 2 centers treated for full-thickness femoral articular cartilage lesions using a chondral osseous autograft transplantation technique was performed. All knees were evaluated both preoperatively and postoperatively by physical examination, radiographs, and Lysholm and Tegner knee scores. Inclusion criteria were full-thickness femoral condyle defects greater than 1 cm and less than 2.5 cm in diameter, and a minimum 24-month follow-up. Exclusion criteria were associated tibial defects, patellar defects, or generalized arthritic change. Grafts harvested from the superior, lateral femoral notch were press-fit into drilled holes to fill the femoral defects.

RESULTS

Thirty-six patients met the inclusion criteria with an average follow-up of 48 months (range, 24 to 89 months). Their average age was 43 years and there were 20 men and 16 women. The medial femoral condyle was involved in 27 cases and the lateral femoral condyle in 9. The average Lysholm score increased from 44 preoperatively to 84 at follow-up. The average Tegner score at follow-up was 5. Repeat arthroscopy was performed in 14 patients and showed good incorporation of the grafts in all cases. Radiographic examinations revealed no arthritic changes at follow-up.

CONCLUSIONS

This technique successfully transplants chondral osseous grafts within the knee that remain viable. No radiographic arthritic changes were observed and the midterm clinical result was favorable for these patients. Further investigation of the long-term results is required.

LEVEL OF EVIDENCE

Level 4, no or historical control.

The autologous osteochondral transplantation of the knee: clinical results, radiographic findings and histological aspects

INTRODUCTION

The osteochondral transplantation (OCT) is a well accepted treatment option for focal cartilage lesions in the knee joint, whereas the fate of the transplanted cartilage is still unclear and the clinical outcome is variable. The purpose of this study was to evaluate the histological character of autologous transplanted cartilage and to correlate technical aspects and the patients' history with the clinical outcome.

MATERIAL AND METHODS

The OCT was performed in 27 patients (median age of 32 (22-43) years) with a focal chondral lesion at the medial femoral condyle. We investigated the clinical outcome after a median follow-up of 13.5 (5-28) months using the Lysholm-score and the integration of the transplanted plugs using an MRI-scoring system. Biopsy specimens from representative patients (n = 8) were evaluated with histological staining and immunohistochemistry.

RESULTS

The median Lysholm-score was 80 (range 45-98). The wide range of the Lysholm-score in clinical outcome did not show significant differences in: follow-up, concomitant injuries, defect size or genesis. The MRI analysis revealed in all cases a regular osseous integration of the subchondral bone, but a failed chondral integration. The congruency of the plugs to the joint surface was often incorrect, however a correlation between the MRI-score and the clinical outcome could not be shown. Histology of the transplanted cartilage revealed small changes in immunohistochemistry after a relatively short-term follow-up, whereas the cartilage has still the typical hyaline character. Often, the surrounding cartilage consists of fibrous and granulation tissue.

CONCLUSION

The congruency of the joint surface can not be restored to the original status, particularly in larger defects with irregular shapes. However, we did not find any aspects which affected the function of the knee joint following OCT. It can be assumed that remaining lesions at the surrounding cartilage could maintain the inflammatory process and therefore maintain the pain and a low knee function. Further investigations are needed to specify the effects of the OCT on the transplanted cartilage and its influence on the later clinical outcome.

Arthroscopic osteochondral autografting

Arthroscopic osteochondral autografting is indicated for unipolar, full thickness articular cartilage lesions between 1 and 2.5 cm in diameter. A stable properly aligned knee is important to a good outcome. This procedure should not be performed in the presence of generalized osteoarthritis. Arthroscopic osteochondral autografting allows the restoration of hyaline articular cartilage with zonal matching of the graft. It is cost-effective, can be performed on an outpatient basis, and results in durable resurfacing with excellent long-term results.

Effects of small incongruities in a sheep model of osteochondral autografting

BACKGROUND

Exact reconstruction of an osteochondral defect by autogenous transplantation (mosaicplasty) is difficult given the variation in joint surface contour. Clinical and experimental studies do not show the extent to which incongruity can be tolerated in autografting.

HYPOTHESIS

Grafted articular cartilage will hypertrophy to correct the incongruity created by recession of the transplanted surface.

STUDY DESIGN

Controlled laboratory study.

METHODS

To test the response of grafts to incongruities, osteochondral autografts were transplanted from the trochlea to the femoral condyle in adult male sheep stifle joints. In groups of 6 animals, graft surfaces were placed flush, countersunk 1 mm or countersunk 2 mm, then histologically analyzed 6 weeks after surgery. Cartilage thickness, condition of the articular surfaces, and preservation of hyaline characteristics were the primary features compared.

RESULTS

Bony union, vascularization, and new bone formation were present in all grafts. Cartilage-to-cartilage healing did not occur. In flush specimens, cartilage changed minimally in thickness and histologic architecture. The specimens countersunk 1 mm demonstrated significant cartilage thickening (54.7% increase, P <.05). Chondrocyte hyperplasia, tidemark advancement, and vascular invasion occurred at the chondroosseous junction, and the surface remained smooth. Cartilage necrosis and fibrous overgrowth were observed in all grafts countersunk 2 mm.

CONCLUSIONS

Minimally countersunk autografts possess a capacity for remodeling that can correct initial incongruities while preserving hyaline characteristics. Grafts placed deeper do not restore the contour or composition of the original articular surface.

CLINICAL RELEVANCE

If preservation of normal hyaline cartilage is the objective, thin grafted articular cartilage can remodel, but the tolerance for incongruity is limited and probably less than that reported for an intra-articular fracture.

Osteogenic protein-1 in knee arthritis and arthroplasty

The use of graft materials to restore bone stock and promote healing and implant stabilization is a crucial part of total knee arthroplasty, especially in revision surgery. Recent research has centered on the use of osteoinductive materials to promote bone formation. Osteogenic proteins are members of a superfamily of proteins called transforming growth factor-beta that, either alone or in combination with other regulatory molecules, induce new bone formation. The cloning and genetic expression of recombinant human osteogenic proteins has led to production of quantities sufficient for their clinical use. Recombinant human osteogenic protein-1 has been combined with bone-derived Type I collagen for delivery to an implant site. Preclinical studies have shown that the osteoinductive capacity of autograft and allograft bone and bone graft substitute materials can be notably improved with the addition of osteogenic protein-1. The use of this protein consistently improved the amount and rate of new bone formation compared with graft alone, resulting in earlier graft incorporation and consolidation. In addition, because osteogenic proteins are chondrogenic, they also may have a role in the treatment of cartilage injury and degeneration. Osteogenic protein-1 has been shown to induce hyalinelike cartilage repair of full thickness osteochondral defects in animal models with no degradation of the tissue with time. Although no detailed clinical studies in knee surgery have been reported with the use of osteogenic protein-1, in anecdotal cases its use alone and with bone graft materials indicate results consistent with those obtained in preclinical studies.

Acoustic stiffness and change in plug cartilage over time after autologous osteochondral grafting: correlation between ultrasound signal intensity and histological score in a rabbit model

We investigated quantitative changes over time in ultrasound signal intensity (an index of stiffness), signal duration (an index of surface irregularity), and interval between signals (an index of thickness) of plug cartilage in an animal model of autologous osteochondral grafting. A full-thickness osteochondral plug was surgically removed and replaced in male Japanese white rabbits (n = 22). Specimens obtained at day 0 and weeks 2, 4, 8, 12 and 24 postoperatively were assessed using an ultrasound system and by macroscopic and histological evaluation (modified Mankin's score). Histology revealed that the plug sank until 2 weeks postoperatively, and that newly formed cartilage-like tissue covered the plug, but at 24 weeks the tissue detached. The plug itself survived well throughout the period of observation. Although the signal intensity at the plug site was same as that in the sham operated contralateral knee at day 0, from 2 to 24 weeks postoperatively it was less than that in the sham knee. At 8 weeks, this difference was significant (P < 0.05). Modified Mankin's score revealed early degenerative changes at the site, but macroscopic examination did not. Signal intensity correlated significantly with score (both at day 0 and at the five postoperative time points [P < 0.05, r = -0.91] and as a whole [P < 0.05, r = -0.36]). Signal intensity also significantly correlated with the individual subscores for 'cartilage structure' (P < 0.05, r = -0.32) and 'cartilage cells' (P < 0.05, r = -0.30) from the modified Mankin's score, but not significantly with subscores for 'staining' and 'tidemark'. Signal duration correlated significantly with total score (as a whole [P < 0.05, r = 0.34]), but not significantly with the score for cartilage structure (P = 0.0557, r = 0.29). The interval between signals reflected well the actual thickness of the plug site. The significant relationships between ultrasound signal intensity and scores suggest that early degenerative changes in plug cartilage and cartilage-like tissue, especially in the superficial layer, are detectable by high-frequency ultrasound assessment.

Split-line pattern and histologic analysis of a human osteochondral plug graft

The split-line pattern of collagen fibers in articular cartilage is oriented according to weight-bearing stresses. The importance of aligning the split-line pattern of articular cartilage in human osteochondral plug grafts relative to the surrounding cartilage has been proposed but not evaluated clinically. The purpose of this case report is to compare the articular split-line pattern with the histologic analysis of a specimen obtained from a patient who underwent an osteochondral plug transfer procedure with subsequent conversion to joint arthroplasty. The fresh osteochondral section obtained at total knee arthroplasty, including the area treated 18 months earlier with an osteochondral plug transfer, was fixed in formalin. Split-lines were demonstrated on the surface using a needle dipped in India ink. After decalcification and paraffin embedding, the specimen was sectioned and stained with Safranin O and fast green for histologic analysis. The split-line pattern of the anterior portion of the graft was oriented parallel to the resident cartilage; however, collagen orientation was divergent (approximately 30 degrees oblique) to the surrounding cartilage near the posterior portion of the graft. It was at this margin that further resident articular degeneration was noted despite the plug articular surface remaining relatively intact. Although bony incorporation of the plug occurred, there was a residual chondral cleft at the graft-host interface. Our report suggests that an osteochondral plug transfer can survive despite a slightly divergent collagen split-line pattern of plug relative to the resident articular bed. Perhaps more important to the clinical outcome is the selection of true focal, traumatic lesions rather than lesions degenerative in etiology, no matter how focal they appear.

Mechanical effects of autogenous osteochondral surgical grafting procedures and instrumentation on grafts of articular cartilage

PURPOSE

To analyze the mechanical effects of autogenous osteochondral grafting procedures on articular cartilage.

METHODS

The intensity, duration, and interval (indexes of stiffness, surface irregularity, and thickness) of the cartilage were assessed in a porcine model using an ultrasonic measurement system. In 7 of 12 knees, 6-mm-diameter plugs were harvested from the donor knees and grafted into 5-mm recipient holes at 3 different points per knee (21 plugs). In the remaining 5 knees, 5-mm plugs were harvested and returned to their original position (28 plugs).

RESULTS

No significant differences in the intensity, duration, and interval of the cartilage were observed with the plugs before harvesting and after grafting by the paired t test. The 3 indexes of the 6- and 5-mm plugs that were grafted correlated significantly with those before they were.

CONCLUSIONS

These results suggest that osteochondral graft surgery does not affect the stiffness, surface irregularity, and thickness of the cartilage of the plugs at time zero.

The use of photooxidized, mushroom-structured osteochondral grafts for cartilage resurfacing--a comparison to photooxidized cylindrical grafts in an experimental study in sheep

OBJECTIVE

This article addresses the problem of structural design with osteochondral grafts used for cartilage resurfacing.

METHODS

Photooxidized cylindrical or mushroom-shaped grafts were surgically implanted in the weight bearing area of the medial and lateral femoral condyles of eight sheep (condyles: N=8/group). Both types of photooxidized grafts contained no viable chondrocytes at the time of implantation. Results were evaluated at 2 and 6 months after surgical implantation of the grafts. Qualitative and quantitative evaluation of the subchondral bone area was performed using plastic embedded sections of non-decalcified bone and cartilage specimens and placing emphasis on graft anchorage, cyst-like lesions at the base of the cartilage junction and at the base of the graft in the subchondral bone region. Cartilage morphology was studied qualitatively focusing on viability of the graft and adjacent host cartilage, while a score system was developed for semi-quantitative evaluation of the overall articular cartilage performance. The semiquantitative scores and histomorphometrical measurements were subjected to statistical analysis using a factorial analysis of variance (ANOVA-test).

RESULTS

The photooxidized mushroom-shaped grafts developed less fibrous tissue and cyst-like lesions in the subchondral bone area at 2 and 6 months compared to the cylindrical grafts. Areas of endochondral ossification and bone remodeling were noticeable in the mushroom structured grafts at 2 months, and also bone remodeling was more complete at 6 months than with the cylindrical grafts. Increased numbers of cells were seen in the basal remodeling zones of both graft types increased from the 2 months to the 6 months specimens, but mushroom structured grafts showed better results. In both graft types, however, the midzone of the cartilage matrix was still acellular at 6 months. Cells from the subchondral bone area started to penetrate the calcified cartilage zone and tide mark at 2 months and repopulated the old photooxidized cartilage matrix already at 6 months after implantation. Cartilage repopulation was dependent on a stable subchondral bone area in both types of grafts. Matrix degradation of the adjacent host cartilage was minimal at 2 and 6 months. At 6 months a junction between host and graft cartilage was already noticed in some of the mushroom-shaped grafts.

CONCLUSION

This study confirmed the importance of the subchondral bone area for osteochondral graft survival. In addition it demonstrated that the structure of the graft influences considerably the architecture of the subchondral bone, and with this the possibility for the repopulation of the old cartilage matrix including the junction between the host and graft cartilage matrix.

Biomechanical and histological evaluation of osteochondral transplantation in a rabbit model

BACKGROUND

Biomechanical and histological properties of osteochondral transplantation have not been extensively examined.

HYPOTHESIS

Osteochondral grafts have properties similar to native articular cartilage.

STUDY DESIGN

Controlled laboratory study.

METHODS

A 2.7 mm (diameter) x 4.0 mm (depth) osteochondral defect was created in 17 New Zealand white rabbit knees. An osteochondral graft, harvested from the contralateral knee, was transplanted into the defect. Eight rabbits were sacrificed each at 6 and 8 weeks.

RESULTS

The 12-week grafts (1213.6 +/- 309.0 N/mm) had significantly higher stiffness than the 6-week grafts (483.1 +/- 229.1 N/mm; P <.001) and of normal cartilage (774.8 +/- 117.1 N/mm; P <.003). Stiffness of the 6-week grafts was significantly lower than normal cartilage (P <.036). At all time points, full-thickness defects had significantly lower stiffness than normal cartilage (P <.001). Histologically, transplanted grafts scored significantly higher than the full-thickness defects (P <.001). The defects showed inconsistent, fibrocartilage healing. The grafts demonstrated cartilage viability, yet with a persistent cleft between the graft and host.

CONCLUSIONS

Osteochondral transplants undergo increased stiffness in the short term, with evidence of structurally intact grafts.

CLINICAL RELEVANCE

Osteochondral transplantation may be a viable treatment option; however, long-term investigation on graft function is necessary.

Analysis of the thickness and curvature of articular cartilage of the femoral condyle

PURPOSE

To develop an optimal autologous osteochondral transplantation technique, we analyzed the thickness and curvature of the femoral condyle.

TYPE OF STUDY

Basic research for surgical technique, anatomic study.

METHODS

Eight cadaveric femoral condyles were sectioned sagittally into 8 slices. Photographs of each slice were digitized, and the thickness and curvature of the overlaying cartilage were analyzed using a National Institutes of Health image program.

RESULTS

The average thickness of the cartilage was 1.69 mm. The minimum and maximum values were measured at 0.22 mm and 3.65 mm, respectively, with the thinnest part seen in the sulcus terminalis (the groove for meniscus). The average curvature of the cartilage was 4.4 m(-1). The minimum and maximum values were measured at -20.0 m(-1) and 27.2 m(-1), respectively.

CONCLUSIONS

When the chondral lesion is assumed at the weight bearing area of the medial or lateral femoral condyle, the anterior portion of the sulcus terminalis (the groove for meniscus) in the middle section of the lateral condyle is considered to be the optimal donor site.

Repair of articular cartilage defects with osteogenic protein-1 (BMP-7) in dogs

BACKGROUND

Articular cartilage injury has a poor prognosis for repair. Mesenchymal cells, when exposed to osteogenic proteins and other cytokines, can differentiate into cells that behave phenotypically as chondrocytes. In this study, we examined the ability of recombinant human osteogenic protein-1 (rhOP-1 or rhBMP-7) to elicit the repair of osteochondral defects in dogs.

METHODS

Bilateral osteochondral defects that were 5 mm in diameter by 6 mm deep were surgically created in the medial femoral condyles of sixty-five adult dogs. rhOP-1-treated (100 mg of a 3.5-mg rhOP-1/g bovine bone-derived Type-I collagen device) and control defects (untreated or treated with 100 mg bovine bone-derived collagen implants) were evaluated grossly and histologically at six, twelve, sixteen, twenty-six, and fifty-two weeks postoperatively. The influence of protected initial weight-bearing and surgical placement of periosteal flaps was also evaluated.

RESULTS

Gross and histologic grading of the defect repair indicated improvement in the rhOP-1-treated defects compared with that in the controls. Grossly, the repair tissue in the rhOP-1-treated defects was continuous with the adjacent intact cartilage and appeared translucent. By comparison, the repair tissue in the control defects was discontinuous and opaque or inhomogeneous in nature. Histologically, maturing cartilage similar in appearance to the intact articular cartilage was present in the rhOP-1-treated defects. Cartilage at the defect interface was minimally degraded. The control defects were filled primarily with fibrous tissue and fibrocartilage. Significant differences based upon treatment type were observed at twelve weeks, sixteen weeks, and for all time-periods combined (p = 0.0385, p = 0.0070, and p = 0.0026, respectively).

CONCLUSION

rhOP-1 (rhBMP-7) induced hyaline cartilage-like repair of full-thickness osteochondral defects in a dog model. Differences in cartilage repair were maintained at fifty-two weeks postoperatively with no significant degradation of the rhOP-1-induced repair tissue.

Transforming growth factor-beta in calcium alginate beads for the treatment of articular cartilage defects in the rabbit

PURPOSE

Articular cartilage has only limited capability for intrinsic repair. The use of growth factors has been suggested to improve the repair of cartilage after injury. Reliable delivery systems for these agents are needed. In this study we tested calcium alginate for the delivery of TGF-beta in the treatment of osteochondral defects in the rabbit knee.

TYPE OF STUDY

Randomized trial animal study and basic science study.

METHODS

In vitro, to establish the kinetics of TGF-beta release from the alginate, 125I- labeled TGF-beta was suspended in 1.2% sodium alginate at concentrations of 1 microg/mL and 10 microg/mL. Beads were formed from 50 microL aliquots and placed into standard culture medium by immersion in calcium chloride solution and incubated at 37 degrees C. A gamma counter was used to measure the amount of TGF-beta that was released into the medium at various time points. In vivo, osteochondral defects were created in the trochlear grooves of 32 New Zealand White rabbits. Defects were treated with plain alginate or with alginate containing TGF-beta at 20 ng/mL or 2,000 ng/mL. Untreated defects served as a control. Animals were killed after 6 and 12 weeks. Knee joints were evaluated grossly with a 12-point grading scale. Histologic sections of the repair tissue were stained with Safranin O and evaluated using a 24-point grading scale by 2 independent blinded observers. Mean scores and standard deviations were calculated. P values were determined using the Student t test.

RESULTS

The TGF-beta was released at a surprisingly slow but steady rate. Release rates extrapolated from the gamma counter measurements were 0.25% per hour and 0.33% per hour, for the 1 microg/mL and 10 microg/mL beads, respectively. Gross analysis scores at 6 and 12 weeks resulted in higher scores for both TGF-beta groups without reaching statistical significance. The lower TGF-beta concentration reached the highest scores, whereas the higher concentration (2,000 ng/mL) resulted in increased osteophyte formation. Histologic analysis at 6 weeks resulted in average scores ranging from 14.5 for empty defects and 18.1 for alginate-treated defects, to 20.0 and 20.3 for the 2,000 ng/mL and 20 ng/mL TGF-beta groups, respectively (P <.05). At 12 weeks, histologic scores ranged from 14.9 for empty and 14.5 for alginate to 20.1 and 20.5 for the 2,000 ng/mL and 20 ng/mL TGF-beta groups, respectively (P <.05). These results indicate a significant improvement of the quality of the repair tissue at 6 and 12 weeks with TFG-beta treatment, especially at the lower concentration.

CONCLUSIONS

The use of alginate allows the controlled delivery of TGF-beta selectively to the site of injury, potentially avoiding systemic side effects. Furthermore, treatment with TGF-beta appears to improve the repair of articular cartilage defects. Longer-term studies are needed to assess whether the benefits of the TGF-beta treatment can be sustained.