Allografts in articular cartilage repair

Revision osteochondral allograft transplantations: do they work?

BACKGROUND

Primary fresh osteochondral allograft transplantation is a useful treatment option for osteochondral lesions in the knee. Clinical failure of primary osteochondral allograft transplantation may require further surgery, including revision osteochondral allograft transplantation.

PURPOSE

To evaluate outcomes of patients who have undergone revision osteochondral allograft transplantation of the knee.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This series included 33 patients (33 knees) who underwent revision osteochondral allograft transplantation between 1983 and 2012, were at least 2 years out from surgery, and had a minimum 2-year follow-up. Clinical evaluations included the International Knee Documentation Committee pain, function, and total scores; Knee Society function score; and modified Merle d'Aubigné and Postel scale. Failure of the revision allograft was defined as conversion to partial or total knee arthroplasty.

RESULTS

The mean follow-up after revision osteochondral allograft transplantation was 10 years, with 75% of patients having more than 5 years' follow-up. Thirteen patients (39%) had failed results after revision osteochondral allograft transplantation, with a mean time to failure of 5.5 years. The remaining 20 patients (61%) had surviving revision allografts, with a mean graft survival of 10 years. Mean pain and function scores at the last follow-up were improved. Survivorship of the revision allograft was 61% at 10 years.

CONCLUSION

Revision osteochondral allograft transplantation of the knee demonstrated acceptable clinical outcomes, although they were inferior to primary allograft transplantation procedures. Revision osteochondral allograft transplantation may be considered an option for patients with a failed primary osteochondral allograft.

The use of allograft in joint-preserving surgery for ankle osteochondral lesions and osteoarthritis

The surgical management of young patients with large osteochondral lesions of the talus or end-stage osteoarthritis of the ankle joint presents a challenge to the orthopedic surgeon because these are well-recognized sources of pain and dysfunction. Procedures designed to address these disorders either have a limited role because of poor success rates or have significant implications, such as with the total ankle arthroplasty. Fresh osteochondral allografts allow defective tissue to be anatomically matched and reconstructed through transplantation. This article presents an overview of fresh osteochondral allografts, as well as potential concerns with their use, and summarizes the current literature.

Technique: Osteochondral Grafting of Capitate Chondrosis in PRC

Background Proximal row carpectomy (PRC) is a useful treatment option for wrist arthritis, but the operation is contraindicated when there is arthritis of the capitate head. We describe a technique that involves resurfacing of a capitate that has focal chondrosis, using an osteochondral graft harvested from the resected carpal bones. Materials and Methods PRC patients who had a focal area of capitate chondrosis underwent osteochondral grafting of the capitate. Pre- and postoperative pain level, employment status, motion, grip strength, and Modified Mayo Wrist Scores (MMWS) were assessed. Postoperative Disability of the Arm, Shoulder, and Hand (DASH) scores were also calculated. Description of Technique The articular surface of the capitate is assessed for need for grafting. The proximal row is resected with the lunate removed intact. The arthritic area is prepared. The graft is taken from the lunate and placed in the prepared site of the capitate. Results Eight patients (average age of 53 years) were followed for 18 months. Pain: Preoperatively, moderate to severe in 7 patients; postoperatively, mild to no pain in 7 patients. Motion: Preoperative, 84° (74% of the contralateral side); postoperative 75° (66%). Grip Strength: Preoperative, 29 kg (62%); postoperative, 34 kg (71%). Mayo Wrist Score: Preoperative, 51 (poor); postoperative, 68 (fair). Average postoperative DASH score was 19.5. Follow-up radiographs showed that 75% of patients had mild to no degeneration. Conclusions Osteochondral grafting in PRC offers satisfactory results in terms of pain relief, return to work, motion, and grip strength. Level of Evidence Therapeutic IV, Case series.

Bipolar fresh osteochondral allografting of the tibiotalar joint

BACKGROUND

Tibiotalar arthritis in the young, active patient is a debilitating condition with limited treatment options. Bipolar tibiotalar fresh osteochondral allograft transplantation was conceived as a possible alternative to arthrodesis and arthroplasty. We reported our experience with bipolar ankle osteochondral allografts for the treatment of tibiotalar joint arthritis.

METHODS

Between 1999 and 2008, we performed bipolar ankle allografts in eighty-eight ankles (eighty-four patients). Eighty-six ankles (eighty-two patients) had a minimum follow-up duration of two years. The mean patient age was forty-four years and 52% of the patients were male. Evaluation included frequency and type of reoperations, the Olerud-Molander Ankle Score, pain, function, and patient satisfaction. Radiographs were evaluated for graft healing, joint space narrowing, and graft collapse.

RESULTS

The mean duration of follow-up was 5.3 years (range, two to eleven years). Thirty-six (42%) of the eighty-six ankles that had undergone allograft had further surgery since implantation. Of the eighty-six ankles, twenty-five ankles (29%) had undergone graft-related reoperations and were considered clinical failures (ten underwent revision allografts, seven underwent arthrodeses, six underwent conversions to total ankle arthroplasty, and two underwent below-the-knee amputations) and eleven ankles (13%) had had reoperations that were not necessarily related to the graft (e.g., implant removal, debridement, synovectomy, or distraction). Survivorship of the osteochondral allograft was 76% at five years and 44% at ten years. The mean Olerud-Molander Ankle Score was 61 points at the time of the latest follow-up. The majority of patients reported satisfaction (92%) with osteochondral allograft transplantation and less pain (85%) and improved function (83%) after the procedure.

CONCLUSIONS

Transplantation of a fresh bipolar ankle osteochondral allograft for the treatment of tibiotalar arthritis resulted in acceptable outcomes in this difficult population, with most patients having improved objective and subjective outcome measures. Subjective satisfaction was high in spite of the 29% clinical failure rate. Osteochondral allograft failure did not limit further surgical options. We concluded that transplantation of a bipolar ankle allograft is a useful alternative in carefully selected patients with advanced tibiotalar arthritis.

Do fresh osteochondral allografts successfully treat femoral condyle lesions?

BACKGROUND

Fresh osteochondral allograft transplantation is an increasingly common treatment option for chondral and osteochondral lesions in the knee, but the long-term outcome is unknown.

QUESTIONS/PURPOSES

We determined (1) pain and function, (2) frequency and types of reoperations, (3) survivorship at a median of 13.5 years, and (4) predictors of osteochondral allograft failure in the distal femur.

METHODS

We evaluated 122 patients (129 knees) who underwent osteochondral allograft transplantation of the femoral condyle. Mean age was 33 years and 53% were male. Clinical evaluation included the modified Merle d'Aubigné-Postel (18-point), IKDC, and Knee Society function (KS-F) scores. We defined graft failure as revision osteochondral allografting or conversion to arthroplasty. We determined whether patient characteristics or attributes of the graft influenced failure. Minimum followup was 2.4 years (median, 13.5 years); 91% had more than 10 years of followup.

RESULTS

Mean modified Merle d'Aubigné-Postel score improved from 12.1 to 16, mean IKDC pain score from 7.0 to 3.8, mean IKDC function score from 3.4 to 7.2, and mean KS-F score from 65.6 to 82.5. Sixty-one knees (47%) underwent reoperations. Thirty-one knees (24%) failed at a mean of 7.2 years. Survivorship was 82% at 10 years, 74% at 15 years, and 66% at 20 years. Age of more than 30 years at time of surgery and having two or more previous surgeries for the operated knee were associated with allograft failure.

CONCLUSIONS

Followup of femoral condyle osteochondral allografting demonstrated durable improvement in pain and function, with graft survivorship of 82% at 10 years.

A primer in cartilage repair

Hyaline articular cartilage has been known to be a troublesome tissue to repair once damaged. Since the introduction of autologous chondrocyte implantation (ACI) in 1994, a renewed interest in the field of cartilage repair with new repair techniques and the hope for products that are regenerative have blossomed. This article reviews the basic science structure and function of articular cartilage, and techniques that are presently available to effect repair and their expected outcomes.

The present state of treatments for articular cartilage defects in the knee

INTRODUCTION

Chondral and osteochondral lesions of the knee are notoriously difficult to treat due to the poor healing capacity of articular cartilage and the hostile environment of moving joints, ultimately causing disabling pain and early osteoarthritis. There are many different reconstructive techniques used currently but few are proven to be of value. However, some have been shown to produce a better repair with hyaline-like cartilage rather than fibrocartilage.

METHODS

A systematic search of all available online databases including PubMed, MEDLINE(®) and Embase™ was undertaken using several keywords. All the multiple treatment options and methods available were considered. These were summarised, and the evidence for and against them was scrutinised.

RESULTS

A total of 460 articles were identified after cross-referencing the database searches using the keywords. These revealed that autologous and matrix assisted chondrocyte implantation demonstrated both 'good to excellent' histological results and significant improvement in clinical outcomes.

CONCLUSIONS

Autologous and matrix assisted chondrocyte implantation have been shown to treat symptomatic lesions successfully with significant histological and clinical improvement. There is, however, still a need for further randomised clinical trials, perfecting the type of scaffold and the use of adjuncts such as growth factors. A list of recommendations for treatment and the potential future trends of managing these lesions are given.

The use of osteochondral allografts in the management of cartilage defects

Large symptomatic osteochondral defects in a young active population represent a therapeutic challenge for orthopedic surgeons, since standard interventions such as debridement, microfracture and autologous osteochondral transfer are not suitable for the treatment of these larger lesions. Fresh osteochondral allograft transplantation provides a surgical option for these challenging defects, both as a primary procedure and for salvage of prior failed treatment attempts. This article reviews the basic science, indications, technique, and evidence for osteochondral allograft transplantation in the knee.

Osteochondral allograft transplantation from a living donor

Treatment of extended and massive osteochondral defects is a real challenge for an orthopaedic practice. Osteochondral allograft transplantation is a possible solution for such lesions. Transplantation of osteochondral allografts has undergone extensive experimental and limited clinical study during recent decades. Graft availability, sizing, technical issues, and viral transmission represent the most problematic points. Because interest in this technique is gaining, more and more countries face the problem of a lack of tissue banks where fresh osteochondral allografts are available. We investigated the advantages of the so-called living donor transplantation of the grafts under programmed surgical conditions. We demonstrate a technique that allows the transplantation of osteochondral allografts without the need for a tissue bank. The radiologic and histologic results regarding the quality of the transplanted cartilage are presented.

Vitrification of intact human articular cartilage

Articular cartilage injuries do not heal and large defects result in osteoarthritis with major personal and socioeconomic costs. Osteochondral transplantation is an effective treatment for large joint defects but its use is limited by the inability to store cartilage for long periods of time. Cryopreservation/vitrification is one method to enable banking of this tissue but decades of research have been unable to successfully preserve the tissue while maintaining cartilage on its bone base - a requirement for transplantation. To address this limitation, human knee articular cartilage from total knee arthroplasty patients and deceased donors was exposed to specified concentrations of 4 different cryoprotective agents for mathematically determined periods of time at lowering temperatures. After complete exposure, the cartilage was immersed in liquid nitrogen for up to 3 months. Cell viability was 75.4 ± 12.1% determined by membrane integrity stains and confirmed with a mitochondrial assay and pellet culture documented production of sulfated glycosaminoglycans and collagen II similar to controls. This report documents successful vitrification of intact human articular cartilage on its bone base making it possible to bank this tissue indefinitely.

Autologous chondrocyte implantation for osteochondral lesions in the knee using a bilayer collagen membrane and bone graft: a two- to eight-year follow-up study

Matrix-induced autologous chondrocyte implantation (MACI) is an established technique used to treat osteochondral lesions in the knee. For larger osteochondral lesions (> 5 cm(2)) deeper than approximately 8 mm we have combined the use of two MACI membranes with impaction grafting of the subchondral bone. We report our results of 14 patients who underwent the 'bilayer collagen membrane' technique (BCMT) with a mean follow-up of 5.2 years (2 to 8). There were 12 men and two women with a mean age of 23.6 years (16 to 40). The mean size of the defect was 7.2 cm(2) (5.2 to 12 cm(2)) and were located on the medial (ten) or lateral (four) femoral condyles. The mean modified Cincinnati knee score improved from 45.1 (22 to 70) pre-operatively to 82.8 (34 to 98) at the most recent review (p < 0.05). The visual analogue pain score improved from 7.3 (4 to 10) to 1.7 (0 to 6) (p < 0.05). Twelve patients were considered to have a good or excellent clinical outcome. One graft failed at six years. The BCMT resulted in excellent functional results and durable repair of large and deep osteochondral lesions without a high incidence of graft-related complications.

Surgical treatment for early osteoarthritis. Part I: cartilage repair procedures

Young patients with early osteoarthritis (OA) represent a challenging population due to a combination of high functional demands and limited treatment options. Conservative measures such as injection and physical therapy can provide short-term pain relief but are only palliative in nature. Joint replacement, a successful procedure in the older population, is controversial in younger patients, who are less satisfied and experience higher failure rates. Therefore, while traditionally not indicated for the treatment of OA, cartilage repair has become a focus of increased interest due to its potential to provide pain relief and alter the progression of degenerative disease, with the hope of delaying or obviating the need for joint replacement. This review of cartilage repair techniques will discuss currently available procedures, specifically pertaining to experiences in the setting of early OA. Level of evidence IV.

Osteochondral and Meniscal Allograft Transplantation in the Football (Soccer) Player

Knee injuries are common in football, frequently involving damage to the meniscus and articular cartilage. These injuries can cause significant disability, result in loss of playing time, and predispose players to osteoarthritis. Osteochondral allografting is an increasingly popular treatment option for osteoarticular lesions in athletes. Osteochondral allografts provide mature, orthotopic hyaline cartilage on an osseous scaffold that serves as an attachment vehicle, which is rapidly replaced via creeping substitution, leading to reliable graft integration that allows for simplified rehabilitation and accelerated return to sport. The indications for meniscal replacement in football players are currently still evolving. Meniscus allografts offer potential functional, analgesic, and chondroprotective benefits in the meniscectomized knee. In the player at the end of his or her professional/competitive career, meniscal allografts can play a role in averting progression of chondropenia and facilitating knee function and an active lifestyle. This article is intended to present a concise overview of the limited published results for osteochondral and meniscal allografting in the athletic population and to provide a practical treatment algorithm that is of relevance to the clinician as well as the patient/football player, based on current consensus of opinion.

MR imaging assessment of articular cartilage repair procedures

Because articular cartilage is avascular and has no intrinsic capacity to heal itself, physical damage to cartilage poses a serious clinical problem for orthopedic surgeons and rheumatologists. No medication exists to treat or reconstitute physical defects in articular cartilage, and pharmacotherapy is limited to pain control. Developments in the field of articular cartilage repair include microfracture, osteochondral autografting, osteochondral allografting, repair with synthetic resorbable plugs, and autologous chondrocyte implantation. MR imaging techniques have the potential to allow in vivo monitoring of the collagen and proteoglycan content of cartilage repair tissue and may provide useful additional metrics of cartilage repair tissue quality.

Scanty integration of osteochondral allografts cryopreserved at low temperatures with dimethyl sulfoxide

PURPOSE

To compare the integration of osteochondral allografts cryopreserved at different temperatures and different concentrations of dimethyl sulfoxide in an in vivo sheep animal model.

METHODS

Thirty-six adult sheep were randomly allocated to 6 groups of allograft osteochondral transplantation. Six osteochondral cylinders were stored for 6 weeks at -80°C; 6 at -80°C with 10% dimethyl sulfoxide (DMSO); 6 at -80°C with 10% DMSO for 90 min; 6 at -186°C; 6 at -186°C with 10% DMSO; 6 at -186°C for 90 min. After transplantation, all animals were euthanized at 6 months. Harvested specimens underwent gross morphologic and histologic evaluation.

RESULTS

We found no statistically significant differences when comparing the gross cartilage morphology and histopathologic scores of each group. The Mankin and OARSI scores and the modified Wakitani and OARSI scores showed a good correlation grade. The Mankin and modified Wakitani scores showed a fair correlation grade.

CONCLUSION

The cryopreservation protocols adopted in the present study provided scanty integration in an in vivo sheep model of osteochondral allograft transplantation. Therefore, their use in the clinical practice is discouraged.

Penetrating Blast Injury to the Knee of a United States Soldier Treated with Allograft Mosaicplasty

OBJECTIVE

This is the first report of successful allograft mosaicplasty treatment of a large osteochondral lesion of the knee caused by a blast fragment sustained during combat operations. The patient was able to return to active duty following rehabilitation.

METHODS

An active-duty infantryman sustained an osteochondral lesion of the medial femoral condyle caused by a metallic fragment of an explosively formed projectile. Initial treatment consisted of removal of the foreign body and primary closure. The patient continued to experience pain, mechanical symptoms, and repeated effusions after initial nonoperative treatment. Allograft mosaicplasty of the lesion utilizing two 18-mm-diameter fresh allograft osteochondral plugs was performed at 6 months post-injury.

RESULTS

At 2-year follow-up, the patient remains on active duty with marked improvement in symptoms. Two years postoperatively, his outcome scores are 72 of 100 on the Western Ontario and McMaster University osteoarthritis scoring index (WOMAC) and 60 of 100 on the Knee Injury and Osteoarthritis Outcome Score (KOOS). His follow-up x-rays and MRI demonstrate intact articular cartilage and subchondral bone incorporation.

CONCLUSION

Penetrating injuries to joints are commonplace in the battlefield environment. Combat injuries to the knee are frequently associated with articular cartilage injury. While numerous cartilage restoration techniques have been used with success for the treatment of osteochondral injuries to the femoral condyles, no published reports describe the use of allograft mosaicplasty in this location for open, penetrating injuries with focal cartilage loss. This is the first documented use of allograft mosaicplasty for a traumatic osteochondral defect of the medial femoral condyle caused by a metallic projectile. The patient was able to return to active duty following rehabilitation. We demonstrate a high level of functioning is possible following allograft mosaicplasty of a large osteochondral lesion caused by penetrating ballistic trauma.

Skeletal tissue regeneration: current approaches, challenges, and novel reconstructive strategies for an aging population

Loss of skeletal tissue as a consequence of trauma, injury, or disease is a significant cause of morbidity with often wide-ranging socioeconomic impacts. Current approaches to replace or restore significant quantities of lost bone come with substantial limitations and inherent disadvantages that may in themselves cause further disability. In addition, the spontaneous repair capacity of articular cartilage is limited; thus, investigation into new cartilage replacement and regeneration techniques are warranted. Along with the challenges of an increasingly aging demographic, changing clinical scenarios and rising functional expectations provide the imperative for new, more reliable skeletal regeneration strategies. The science of tissue engineering has expanded dramatically in recent years, notably in orthopedic applications, and it is clear that new approaches for de novo skeletal tissue formation offer exciting opportunities to improve the quality of life for many, particularly in the face of increasing patient expectations. However, significant scientific, financial, industrial, and regulatory challenges should be overcome before the successful development of an emergent tissue engineering strategy can be realized. We outline current practice for replacement of lost skeletal tissue and the innovative approaches in tissue regeneration that have so far been translated to clinical use, along with a discussion of the significant hurdles that are presented in the process of translating research strategies to the clinic.

An arthroscopic device to assess articular cartilage defects and treatment with a hydrogel

The hydraulic resistance R across osteochondral tissue, especially articular cartilage, decreases with degeneration and erosion. Clinically useful measures to quantify and diagnose the extent of cartilage degeneration and efficacy of repair strategies, especially with regard to pressure maintenance, are still developing. The hypothesis of this study was that hydraulic resistance provides a quantitative measure of osteochondral tissue that could be used to evaluate the state of cartilage damage and repair. The aims were to (1) develop a device to measure R in an arthroscopic setting, (2) determine whether the device could detect differences in R for cartilage, an osteochondral defect, and cartilage treated using a hydrogel ex vivo, and (3) determine how quickly such differences could be discerned. The apparent hydraulic resistance of defect samples was ~35% less than intact cartilage controls, while the resistance of hydrogel-filled groups was not statistically different than controls, suggesting some restoration of fluid pressurization in the defect region by the hydrogel. Differences in hydraulic resistance between control and defect groups were apparent after 4 s. The results indicate that the measurement of R is feasible for rapid and quantitative functional assessment of the extent of osteochondral defects and repair. The arthroscopic compatibility of the device demonstrates the potential for this measurement to be made in a clinical setting.

Translation of science to surgery

Orthopaedic surgery is in an exciting transitional period as modern surgical interventions, implants and scientific developments are providing new therapeutic options. As advances in basic science and technology improve our understanding of the pathology and repair of musculoskeletal tissue, traditional operations may be replaced by newer, less invasive procedures which are more appropriately targeted at the underlying pathophysiology. However, evidence-based practice will remain a basic requirement of care. Orthopaedic surgeons can and should remain at the forefront of the development of novel therapeutic interventions and their application. Progression of the potential of bench research into an improved array of orthopaedic treatments in an effective yet safe manner will require the development of a subgroup of specialists with extended training in research to play an important role in bridging the gap between laboratory science and clinical practice. International regulations regarding the introduction of new biological treatments will place an additional burden on the mechanisms of this translational process, and orthopaedic surgeons who are trained in science, surgery and the regulatory environment will be essential. Training and supporting individuals with these skills requires special consideration and discussion by the orthopaedic community.

In this paper we review some traditional approaches to the integration of orthopaedic science and surgery, the therapeutic potential of current regenerative biomedical science for cartilage repair and ways in which we may develop surgeons with the skills required to translate scientific discovery into effective and properly assessed orthopaedic treatments.

Fresh osteochondral allografting for steroid-associated osteonecrosis of the femoral condyles

BACKGROUND

Osteonecrosis is a complication of corticosteroid therapy with limited treatment options in young, active patients. These options include debridement, core decompression, osteotomy, allografting, and partial or total knee replacement. Few studies exist regarding the use of osteochondral allografts for treatment of steroid-associated osteonecrosis.

QUESTIONS/PURPOSES

We asked if fresh osteochondral allografts would (1) heal to host bone in the presence of osteonecrosis, (2) provide a clinically meaningful decrease in pain and improvement in function, and (3) prevent or postpone the need for prosthetic arthroplasty.

PATIENTS AND METHODS

Twenty-two patients (28 knees) who underwent osteochondral allografting for high-grade, corticosteroid-associated osteonecrosis were evaluated. Their average age was 24.3 years (range, 16-44 years). The mean graft surface area was 10.8 cm(2) (range, 5.0-19.0 cm(2)). Evaluation included a modified (for the knee) D'Aubigné and Postel (18-point) score, International Knee Documentation Committee (IKDC), and Knee Society function scores. The minimum followup was 25 months (mean, 67 months; range, 25-235 months).

RESULTS

Five knees failed. The graft survival rate was 89% (25 of 28). The mean D'Aubigné and Postel score improved from 11.3 to 15.8; 19 of 25 (76%) had a score greater than 15. The mean IKDC pain score improved from 7.1 to 2.0, mean IKDC function score from 3.5 to 8.3, and mean Knee Society function score from 60.0 to 85.7.

CONCLUSIONS

Our data suggest osteochondral allografting is a reasonable salvage option for osteonecrosis of the femoral condyles. TKA was avoided in 27 of the 28 of knees at last followup.

LEVEL OF EVIDENCE

Level IV, case series. See Guidelines for Authors for a complete description of levels of evidence.

Variation of mesenchymal cells in polylactic acid scaffold in an osteochondral repair model

OBJECTIVE

To achieve osteochondral regeneration utilizing transplantation of cartilage-lineage cells and adequate scaffolds, it is essential to characterize the behavior of transplanted cells in the repair process. The objectives of this study were to elucidate the survival of mesenchymal cells (MCs). In a polylactic acid (PLA) scaffold and assess the possibility of MC/PLA constructs for osteochondral repair.

DESIGN

Bone marrow from mature male rabbits was cultured for 2 weeks, and fibroblast-like MCs, which contain mesenchymal stem cells (MSCs), were obtained. A cell/scaffold construct was prepared with one million MCs and a biodegradable PLA core using a rotator device. One week after culturing, the construct was transplanted into an osteochondral defect in the medial femoral condyle of female rabbits and the healing process examined histologically. To examine the survivability of transplanted MCs, the male-derived sex-determining region Y (SRY) gene was assessed as a marker of MCs in the defect by polymerase chain reaction (PCR).

RESULTS

In the groups of defects without any treatment, and the transplantation of PLA without cells, the defects were not repaired with hyaline cartilage. The cartilaginous matrix by safranin O staining and type II collagen by immunohistochemical staining were recognized, however the PLA matrix was still present in the defects at 24 weeks after transplantation of the construct. During the time passage, transplanted MCs numbers decreased from 7.8 x 105 at 1 week, to 3.5 x 105 at 4 weeks, and to 3.8 x 104 at 12 weeks. Transplanted MCs were not detectable at 24 weeks.

CONCLUSIONS

MCs contribute to the osteochondral repair expressing the cartilaginous matrix, however the number of MCs were decreasing with time (i.e. 24 weeks). These results could be essential for achieving cartilage regeneration by cell transplantation strategies with growth factors and/or gene therapy.

Assessment of strategies to increase chondrocyte viability in cryopreserved human osteochondral allografts: evaluation of the glycosylated hydroquinone, arbutin

OBJECTIVE

Allogeneic cartilage is used to repair damaged areas of articular cartilage, requiring the presence of living chondrocytes. So far, no preservation method can effectively meet that purpose. Identification of more effective cryoprotective agents (CPAs) can contribute to this goal. The aim of this study was to determine whether the glycosylated hydroquinone, arbutin, alone or in combination with low concentrations of other CPAs, has cryoprotective properties towards human articular cartilage.

MATERIAL AND METHODS

Human tibial plateaus were procured from multi-organ donors, with the approval of the Ethics Committee of the University Hospital of Coimbra. The tibial plateaus were treated with or without arbutin (50 or 100mM), alone or in combination with various concentrations of dimethyl sulfoxide (DMSO) and glycerol, for 0.5-1.5h/37 degrees C, then frozen at -20 degrees C and 24h later transferred to a biofreezer at -80 degrees C. Two to 3 months later, thawing was achieved by immersion in cell culture medium at 37 degrees C/1h. Chondrocyte viability was assessed before and after freeze-thawing using a colorimetric assay based on the cell's metabolic activity and fluorescent dyes to evaluate cell membrane integrity.

RESULTS

Before freezing, chondrocyte metabolic activity was identical in all the conditions tested. After freeze-thawing, the highest activity, corresponding to 34.2+/-2.1% of that in the Fresh Control, was achieved in tibial plateaus incubated in 50mM arbutin for 1h whereas in those left untreated it was 11.1+/-4.7. Addition of DMSO and glycerol to arbutin did not increase chondrocyte viability any further. Fluorescence microscopy confirmed these results and showed that living chondrocytes were mainly restricted to the superficial cartilage layers.

CONCLUSION

Arbutin seems to be an effective cryoprotective agent for osteochondral allografts with potential benefits over DMSO and glycerol.

Osteochondral integration of multiply incised pure cartilage allograft: repair method of focal chondral defects in a porcine model

BACKGROUND

A focal cartilage lesion has limited capacity to heal, and the repair modalities used at present are still unable to provide a universal solution. Pure cartilage graft implantation appears to be a simple option, but it has not been applied widely as cartilage will not reattach easily to the subchondral bone.

HYPOTHESIS

We used a multiple-incision technique (processed chondrograft) to increase cartilage graft surface. We hypothesized that pure cartilage graft with augmented osteochondral fusion capacity may be used for cartilage repair and we compared this method with other repair techniques.

STUDY DESIGN

Controlled laboratory study.

METHODS

Full-thickness focal cartilage defects were created on the medial femoral condyle of 9-month-old pigs; defects were repaired using various methods including bone marrow stimulation, autologous chondrocyte implantation, and processed chondrograft. After the repair, at weeks 6 and 24, macroscopic and histologic evaluation was carried out.

RESULTS

Compared with other methods, processed chondrograft was found to be similarly effective in cartilage repair. Defects without repair and defects treated with bone marrow stimulation appeared slightly irregular with fibrocartilage filling. Autologous chondrocyte implantation produced hyalinelike cartilage, although its cellular organization was distinguishable from the surrounding articular cartilage. Processed chondrograft demonstrated good osteochondral integration, and the resulting tissue appeared to be hyaline cartilage.

CONCLUSION

The applied cartilage surface processing method allows acceptable osteochondral integration, and the repair tissue appears to have good macroscopic and histologic characteristics.

CLINICAL RELEVANCE

If further studies confirm its efficacy, this technique could be considered for human application in the future.

Chondrocyte viability is higher after prolonged storage at 37 degrees C than at 4 degrees C for osteochondral grafts

BACKGROUND

Osteochondral allografts are currently stored at 4 degrees C for 2 to 6 weeks before implantation. At 4 degrees C, chondrocyte viability, especially in the superficial zone, deteriorates starting at 2 weeks. Alternative storage conditions could maintain chondrocyte viability beyond 2 weeks, and thereby facilitate increased graft availability and enhanced graft quality.

PURPOSE

The objective of the study was to determine the effects of prolonged 37 degrees C storage compared with traditional 4 degrees C storage on chondrocyte viability and cartilage matrix content.

STUDY DESIGN

Controlled laboratory study.

METHODS

Osteochondral samples from humeral heads of adult goats were analyzed (i) fresh, or after storage in medium for (ii) 14 days at 4 degrees C including 10% fetal bovine serum, (iii) 28 days at 4 degrees C including 10% fetal bovine serum, (iv) 28 days at 37 degrees C without fetal bovine serum, (v) 28 days at 37 degrees C including 2% fetal bovine serum, or (vi) 28 days at 37 degrees C including 10% fetal bovine serum. Portions of samples were analyzed by microscopy after LIVE/DEAD staining to determine chondrocyte viability and density, both en face (to visualize the articular surface) and vertically (overall and in superficial, middle, and deep zones). The remaining cartilage was analyzed for sulfated glycosaminoglycan and collagen.

RESULTS

The 37 degrees C storage maintained high chondrocyte viability compared with 4 degrees C storage. Viability of samples after 28 days at 37 degrees C was approximately 80% at the cartilage surface en face, approximately 65% in the superficial zone, and approximately 70% in the middle zone, which was much higher than approximately 45%, approximately 20%, and approximately 35%, respectively, in 4 degrees C samples after 28 days, and slightly decreased from approximately 100%, approximately 85%, and approximately 95%, respectively, in fresh controls. Cartilage thickness, glycosaminoglycan content, and collagen content were maintained for 37 degrees C and 4 degrees C samples compared with fresh controls.

CONCLUSION

The 37 degrees C storage of osteochondral grafts supports long-term chondrocyte viability, especially at the vulnerable surface and superficial zone of cartilage.

CLINICAL RELEVANCE

Storage of allografts at a physiologic temperature of 37 degrees C may prolong storage duration, improve graft availability, and improve treatment outcomes.

Success rates and immunologic responses of autogenic, allogenic, and xenogenic treatments to repair articular cartilage defects

This review examines current approaches available for articular cartilage repair, not only in terms of their regeneration potential, but also as a function of immunologic response. Autogenic repair techniques, including osteochondral plug transplantation, chondrocyte implantation, and microfracture, are the most widely accepted clinical treatment options due to the lack of immunogenic reactions, but only moderate graft success rates have been reported. Although suspended allogenic chondrocytes are shown to evoke an immune response upon implantation, allogenic osteochondral plugs and tissue-engineered grafts using allogenic chondrocytes exhibit a tolerable immunogenic response. Additionally, these repair techniques produce neotissue with success rates approaching those of currently available autogenic repair techniques, while simultaneously obviating their major hindrance of donor tissue scarcity. To date, limited research has been performed with xenogenic tissue, although several studies demonstrate the potential for its long-term success. This article focuses on the various treatment options for cartilage repair and their associated success rates and immunologic responses.

Articular cartilage tissue engineering

Articular cartilage repair remains a challenge to surgeons and basic scientists. The field of tissue engineering allows the simultaneous use of material scaffolds, cells and signalling molecules to attempt to modulate the regenerative tissue. This review summarises the research that has been undertaken to date using this approach, with a particular emphasis on those techniques that have been introduced into clinical practice, via in vitro and preclinical studies.

MRI evaluation of a new scaffold-based allogenic chondrocyte implantation for cartilage repair

AIM

The present study was designed to evaluate the implantation of alginate beads containing human mature allogenic chondrocytes for the treatment of symptomatic cartilage defects of the knee. MRI was used for the morphological analysis of cartilage repair. The correlation between MRI findings and clinical outcome was also studied.

METHODS

A biodegradable, alginate-based biocompatible scaffold containing human mature allogenic chondrocytes was used for the treatment of symptomatic chondral and osteochondral lesions in the knee. Twenty-one patients were prospectively evaluated with use of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the Visual Analogue Scale (VAS) for pain preoperatively and at 3, 6, 9 and 12 months of follow-up. Of the 21 patients, 12 had consented to follow the postoperative MRI evaluation protocol. MRI data were analyzed based on the original MOCART (Magnetic Resonance Observation of Cartilage Repair Tissue) and modified MOCART scoring system. The correlation between the clinical outcome and MRI findings was evaluated.

RESULTS

A statistically significant clinical improvement became apparent after 6 months and patients continued to improve during the 12 months of follow-up. One of the two MRI scoring systems that were used, showed a statistically significant deterioration of the repair tissue at 1 year of follow-up. Twelve months after the operation complete filling or hypertrophy was found in 41.6%. Bone-marrow edema and effusion were seen in 41.7% and 25% of the study patients, respectively. We did not find a consistent correlation between the MRI criteria and the clinical results.

DISCUSSION

The present study confirmed the primary role of MRI in the evaluation of cartilage repair. Two MOCART-based scoring systems were used in a longitudinal fashion and allowed a practical and morphological evaluation of the repair tissue. However, the correlation between clinical outcome and MRI findings was poor. Further validation of these scoring systems is mandatory. The promising short-term clinical outcome of the allogenic chondrocytes/alginate beads implantation was not confirmed by the short-term MRI findings.

Osteochondral resurfacing (OCRPRC) for capitate chondrosis in proximal row carpectomy

PURPOSE

Proximal row carpectomy (PRC) can be an effective treatment option for arthritis of the wrist, but the operation is contraindicated when there is substantial arthritis of the capitate head. We describe a new technique that involves resurfacing of the capitate when there is chondrosis by using osteochondral grafts harvested from the resected carpal bones. The purpose of this study was to assess the outcomes of patients who had osteochondral resurfacing in the setting of PRC (OCRPRC) for capitate chondrosis and to determine how they compare with published results of conventional PRC.

METHODS

Patients having PRC who had grade II to IV (Modified Outerbridge Scale) capitate chondrosis underwent osteochondral resurfacing of the capitate. Preoperative and postoperative pain level, employment status, range of motion (ROM), grip strength, and Mayo wrist scores were assessed, and Student's t-test was used. Postoperative Disability of the Arm, Shoulder and Hand (DASH) scores were also calculated.

RESULTS

Eight patients with an average age of 53 years were followed up for 18 months. Preoperatively, 7 patients described their pain as moderate to severe; postoperatively, 7 patients described their pain as mild to no pain. Preoperative arc of motion was 84 degrees (74% of the contralateral side); postoperative arc of motion was 75 degrees (66% of the contralateral side). Preoperative grip strength was 29 kg, or 62% of the contralateral side; postoperative grip strength was 34 kg, or 71% of the contralateral side. Preoperative Mayo wrist score was 51 ("poor"); postoperative Mayo wrist score was 68 ("fair"). Average postoperative DASH score was 19.5. Follow-up radiographs showed that 75% of patients had mild to no degeneration. Magnetic resonance imaging at 21 months postoperatively showed graft incorporation. No complications were encountered.

CONCLUSIONS

Our results with osteochondral resurfacing compare favorably with the published results of conventional PRC in terms of pain relief, employment status, ROM, and grip strength.

No influence of collagenous proteins of Achilles tendon, skin and cartilage on the virus-inactivating efficacy of peracetic acid–ethanol

The risk of transmitting human pathogenic viruses via allogeneic musculoskeletal tissue transplants is a problem requiring effective inactivation procedures. Virus safety of bone transplants was achieved using peracetic acid (PAA)-ethanol sterilisation. Proteins are known to have an adverse effect on the virus-inactivating capacity of PAA. Therefore we investigated virus inactivation by PAA in collagenous tissues. Achilles tendon, skin and cartilage were cut into small pieces, lyophilised and contaminated with pseudorabies virus (PRV) or porcine parvovirus (PPV). The inactivating capacity of PAA-ethanol was investigated by determining virus titres in the supernatant or the tissue pellet at different time-points. In all virus-contaminated tissue samples treatment for 10 min with PAA-ethanol resulted in titre reductions by a factor of >10(3). PRV was rapidly inactivated below the detection limit (< or =2.8 x 10(1) TCID(50)/ml). After 240 min a reduction by a factor of >10(4) was obtained for PPV in all samples, but a residual infectivity remained. Collagenous proteins of Achilles tendon, skin and cartilage had no adverse effect on the virus-inactivating capacity of PAA. PAA-ethanol used in the production process at the Charité tissue bank can therefore be recommended for treatment of non-osseous musculoskeletal tissues.