Experimental repair mechanism after Mosaicplasty and Principles of Mosaicplasty

Laszlo Hangody M.D., Ph.D.

Uzsoki Hospital, Orthopaedic and Trauma Department

Budapest, Hungary

Corresponding address:

Laszlo Hangody M.D., Ph.D.

Uzsoki Hospital, Orthopaedic and Trauma Department

MexikÛi str. 62

1145 Budapest, Hungary

Fax: 36 1 394 31 36

E-mail:hangody@matavnet.hu

According to several authors, autologous hyaline cartilage survives the process of transplantation allowing a hyaline cartilage surface to be produced at the site of the defect (1, 2, 3, 4, 5). The major overall advantages of this technique are

the hyaline cartilage is transplanted as unit with its subchondral bone base, thus preserving the very important hyaline cartilage-bone interface;

the graft is, by its very nature, protected from immunological reaction;

it does not carry the risk of viral transmission.

Campanacci et al.(1), Fabricciani et al.(2), Outerbridge et al.(4) and Yamashita et al. (5) have had good medium and long-term experiences by transplantation of single block osteochondral autografts. Their publications reported long term survival of transplanted hyaline cartilage. Lindholm et al. (3) emphasized the importance of graft congruity, since in its absence the grafts will degenerate. Graft procurement represents a problematic point of this technique. It is difficult to find suitable donor sites for defects larger than 10 mm in diameter without violating the weight-bearing articular surfaces. Summarizing, it seems that lack of suitable donor site and possible incongruency represent the two major problems at transplantation of autologous osteochondral grafts.

To eliminate the donor site and congruency problems transplantation of multiple small sized grafts could provide advantages comparing to one block transfer. The first successful transplantation of multiple cylindrical osteochondral grafts was reported by Matsusue in 1993 (6). He reported a case of an autogenous osteochondral transplantation of 3 cylinders 9 mm long and 5 mm in diameter into a defect on the medial femoral condyle associated of an ACL deficient knee. His 37-year-old male patient had no complaint at 3-year follow up examination. Slight subchondral sclerosis at the recipient site. on the X-rays was reported

The autologous osteochondral mosaicplasty ñ as a special form of the osteochondral autograft transfer - was developed in Hungary in 1991. Conceptually, the technique specifically addressed problems of congruency at the recipient site by the implantation of small sized grafted sequentially arrayed in a mosaic-like pattern (7). Inherent to the technique design has been the procurement of these small grafts from less weight bearing surfaces, thus reducing the potential of donor site morbidity. Following several series of animal trials on German Shepherd dogs and horses, cadaver research and the development of special instrumentation, this technique was introduced into clinical practice in 1992 (7, 8, 9, 10, 11, 12, 13, 14).

As previously has been mentioned, the concept of the autologous osteochondral transplantation is not new, but the mosaicplasty technique tried to provide a successful clinical application for the osteochondral transfer. The aim of this procedure is to create a composite cartilage surface at the site of the defect. This composite cartilage layer consists, on an average, of 70-80% transplanted hyaline cartilage, and 20-30% integrated fibrocartilage. Mathematically, the use of same sized contacting rings results in a theoretical 78.5% filling (15, 16). But, filling the dead spaces with smaller sizes can improve the coverage of the defect. The special design of the instrumentation can accommodate a 100% filling rate but, naturally, such transplantation requires more graft harvesting. Later, long term experience has taught that an 80% filling rate correlates with good a clinical outcome (8, 13).

Fibrocartilage results from the natural healing process of the re-freshened bony base of the defect. According to experimental data this fibrocartilage not only fills the space between the transplanted grafts but also eliminates the minimal incongruities of the surface (10). Shapiro et al. (17), Desjardins et al. (18), in separate experimental studies, have reported that newly formed or transplanted hyaline cartilage are not well integrated with the surrounding host cartilage. In contrast, German Shepherd dog and horse mosaicplasty trials have demonstrated that deep matrix integration is possible between transplanted and surrounding hyaline cartilage, as well as hyaline cartilage and reparative fibrocartilage (10). Histological evaluations of these interfaces of animal and human biopsies showed that such integration were the rule, but in some sections gaps remained between the two types of tissues (12, 13, 14). According to quantitative evaluations of the success rate of the deep matrix integration it seems that an adequate rehabilitation protocolñ appropriate sequence and duration of non weight bearing, partial loading and weight bearing periods ñ has also essential role in this matter. Further studies have been planned to investigate bioactive materials and factors, which may trigger a better integration process.

The natural healing mechanism determines the response of the donor holes. Mesenchymal stem cells and other cellular elements of the invading blood serve a spontaneous regenerative process. The donor site behavior is similar to that prevailing after Pridie drilling. The holes fill by cancellous bone during the first 4 postoperative weeks.. Its surface will be covered by early regenerative tissue at 6 weeks and final coverage will be finished by a central fibrocartilage cap and peripheral hyaline cartilage at 8th-10th weeks. This partially non hyaline coverage of the donor holes separated by host articular cartilage appears to be adequate surface for the biomechanical requirements of the less weight bearing area (12, 13, 14). Donor site selection still represents a subject of debate among autologous osteochondral investigators. Hangody et al. prefer the less weight bearing peripheries of the medial and lateral femoral condyles at the level of the patellofemoral joint (7, 8). Bobic (19) also harvest grafts from the notch area, while Johnson et al. (20) reported graft harvest from the proximal tibiofibular joint. Several studies have been published to investigate the possible donor site morbidity (21, 22, 23). According to St‰ubli et al. (22) dynamic analyses of opposing articular cartilage contact zones of the patellofemoral joint autografts harvesting from the superolateral aspect of the lateral part of the femoral trochlea should be avoided.

As any other surgical procedure, mosaicplasty also has indications and limitations. This technique has been developed to treat small or medium sized focal chondral and osteochondral defects. Till this time collected experiences suggest that between 1.0 and 4.0 squarecentimeter defect size the procedure has the best clinical outcome. Defects over 4.0 squarecentimeter require other surgical solution ñ for example chondrocyte transplantation or periosteal flapping ñ as extended graftharvest can cause higher early and long term donor site morbidity. On the other hand it is very important to consider that hyaline cartilage is a very sensitive tissue, and a successful transplantation requires the best conditions. Osteoarthritis represents an altered biochemical environment and therefore disadvantageous for the survival of the transplanted chondral tissue. Advanced degenerative joint disease, rheumatoid background and tumoral lesions are contraindications of the mosaicplasty. Usually 50 year is the superior age limit, but in selected cases we have already performed mosaicplasties over this limitation (8, 13).

It is always important to emphasize at the indication, that the treatment of full thickness cartilage defects represents a complex problem. We have to treat the underlying causes paralel with the cartilage repair. ACL reconstruction, realignment osteotomies, corrections of the patellofemoral disbalance and meniscus surgery are the most often performed concomitant procedures (8, 13, 14).

During the procedure, edges of the defect are excised back to healthy hyaline cartilage. Then the base of the lesion is abraded to viable subchondral cortical bone to re-freshen the bony base and to remove the sequester layer. The number and size of the grafts for the ideal covering of the defect are determined by special instrumentation (Mosaicplasty"! Complete System, Smith and Nephew Endoscopy Inc., Andover, MA). The next step is taking small sized osteochondral cylinders from the edges of the medial or lateral femoral condyles. These grafts are harvested from the less weight bearing supracondylar ridge of the patellofemoral joint by compressive tubular chisels. The last step is a mosaic-like implantation of the osteochondral transplants by press fit technique into drilled holes of recipient area (8). Specially designed instrumentation serves the same operative technique for open procedures and arthroscopic implantations.

During rehabilitation, a full range of motion and non weight-bearing period for 2-3 weeks and partial loading (30-40 kg) for 2 weeks are advised in accordance with site and extent of the defect. Full weight bearing after 4 or 5 weeks and normal daily activity from 6-8 weeks is allowed, but sport activity is not recommended during the first post operative 4-6 months. The use of CPM (6 hours per day) in the first 7-10 days can promote the rehabilitation (13).

Follow up examinations and control arthroscopies over the last seven years have demonstrated good preliminary clinical results confirming the data from preclinical animal trials. The latest summary of the clinical results involves more than 600 cases. Femoral and tibial condylar implantation demonstrated 92% good and excellent results using modified HSS and modified Cinncinatti activity scores, while patellofemoral implantation gave only 84% good to excellent outcome (13, 14). Unfortunately the distribution of the good and excellent cases is also less favourable in the patellofemoral group as in the femorotibial joint. Efficacy of concomitant procedure may have some influence on this difference.

Refinement of the technique by miniarthrotomy and arthroscopic application combined with reproducibility has resulted in a world-wide popularity of the mosaicplasty as an effective, inexpensive, one-step resurfacing technique (9, 12, 14). Possible donor site morbidity, as controlled by the Bandi score, has been less than 3%. This morbidity has been uniform: patellofemoral complaints with strenuous physical activity. Other failures have been 4 deep septic complications and 37 painful postoperative hemarthroses. Most of these bleedings have been treated by a single or repeated aspiration, while the remaining cases, and the septic failures needed open or arthroscopic debridement (13, 14). Separate evaluations in different subgroups ñ such as osteochondral resurfacements (12); 3-7 years follow up (13); mosaicplasties among athletes (14)ñ also gave near to 90% success rate.

Beside femoral and patellar use tibial ñ Hangody et al. (13); talar - Jakob et al. (23), Imhoff et al. (24), Hangody et al. (11); capitulum humeri ñ Hangody et al. (14) and femoral head transplants ñ Jakob et al. (23), Gautier et al. (25, 26) have been published as further successful applications. Talar implantations have medium-term results. Two to six years follow up of 31 mosaicplasties for osteochondral lesions gave 95% good and excellent results according to the Hannover scoring system. Five cases have had minor donor site complaints up to the end of the first postop. year. The second looks arthroscopies demonstrated talar recipient site surfaces which appeared and palpated as normal as well as being congruent with the their environs. The biopsy specimens were analyzed histologically using various stains (HE, picrosirius red, toluidin blue, orcein, etc.) and polarization, collagen typing and enzymhistochemistry. These slides show staining specific for type II collagen and articular proteoglycans lending histological evidence to our other observations that the hyaline cartilage survives intact and bonds to the talus.

MRI controls have documented good integration of the implanted grafts to the surrounding tissue. At various postoperative intervals, 3 open procedures after a previous mosaicplasty, 63 control arthroscopies, recipient and donor site biopsies and, in some cases, indentometric measurements have connoted the hyaline like character of the replaced area and the fibrocartilage covering of the donor area (10, 12, 13, 14). Cartilage stiffness measurements (by indentometry) at the recipient site have produced matching values for graft and surrounding healthy hyaline cartilage. Several independent, multicentric studies have also supported the results of Hangody, K·rp·ti, Kish et al. (21, 27). Christel et al. (21) in a french multicenter study have found similar success rate as Hangody et al..

Beside the mosaicplasty technique, similar multiple cylindrical grafting options have also been developed. Bobic (19), Jakob (23), Chow and Barber (28) and others (24, 29) have produced similar promising results. Increasing number of successful transplantations by these techniques support the theoretical considerations of multiple autologous osteochondral transfer. Disadvantages, both projected and practical, such as early and long term donor site morbidity (22, 27), incomplete healing of transplanted tissue to the host cartilage (14, 21), and technical difficulties (19, 23, 24) compromise the procedure. Addressing these issues must be the subject of further investigation to reduce the morbidity rate and validate the long term results.

According to the follow up results, autologous osteochondral mosaicplasty seems to be as an efficacious alternative in the treatment of the focal chondral and osteochondral defects. Naturally, as at every other modern resurfacing technique, long term results and prospective, multicentric, comparative studies are required to determine the final role of this technique in prevention of osteoarthritis.

FIGURES:

Fig.1.)

Histological view of a 26 weeks old donor site (picrosirius red at polarized light, 20x) ñ complete cancellous bone filling and fibrocartilage coverage of the donor tunnel

Fig.2.)

Arthroscopic mosaicplasty on the medial femoral condyle because of a Grade IV. chondral lesion

Fig.3.)

Open mosaicplasty on the capitulum humeri because of an OCD lesion

Fig.4.)

Open talar mosaicplasty on the lateral talar dome

Fig.5.)

Cartilage stiffness indentometry on a 5 years old MP

REFERENCES:

Campanacci, M.- Cervellati, C.- Dontiti U. : Autogenous patella as replacement for a resected femoral or tibial condyle. A report of 19 cases. J. Bone Joint Surg. 67B: 557-563, 1985

Fabbricciani, C.-Schiavone Panni, A.-Delcogliano, A. et al.: Osteochondral autograft in the treatment of osteochondritis dissecans of the knee. AOSSM Annual Meeting, Orlando, FL, 1991

Lindholm, T., S.-Osterman, K.-Kinnunen, P.-Lindholm, T.,C.-Osterman, H., K.: Reconstruction of the joint surface using osteochondral fragments. Scand. J. Rheumatol. (Suppl. ) 44: 5-12, 1982

Outerbridge, H., K.- Outerbridge, A., R.- Outerbridge, R., E.: The use of a lateral patellar autogenous graft for the repair of a large osteochondral defect in the knee. J. Bone Joint Surg. 77-A: 65-72, 1995

Yamashita, F.- Sakakida, K.- Suzu, F.- Takai, S.: The transplantation of an autogenic osteochondral fragment for osteochondritis dissecans of the knee. Clin Orthop. 210: 43-50, 1985

Matsusue, Y.- Yamamuro, T.- Hama, M.: Arthroscopic multiple osteochondral transplantation to the chondral defect in the knee associated with anterior cruciate ligament disruption: case report. Arthroscopy 9: 318-321, 1993

Hangody, L.- K·rp·ti, Z.: A new surgical treatment of localised cartilaginous defects of the knee. Hung. J. Orthop. Traumat. 37: 237-243, 1994

Hangody, L. ñ Kish, G. ñ K·rp·ti, Z. ñ Eberhardt, R.: Osteochondral plugs: Autogenous osteochondral mosaicplasty for the treatment of focal chondral and osteochondral articular defects. Operative Tech. Orthop. 7: 312-322, 1997

Hangody, L.- Kish G.- K·rp·ti, Z. et al.: Arthroscopic autogenous osteochondral mosaicplasty for the treatment of femoral condylar articular defects. Knee Surg. Sports Traumatol. Arthrosc. 5: 262-270, 1997

Hangody, L.- Kish, G.- K·rp·ti, Z et al.: Autogenous osteochondral graft technique for replacing knee cartilage defects in dogs. Orthopaedics International Edition 5: 175-181, 1997

Hangody, L. - Kish, G. - K·rp·ti, Z. et al.: Treatment of osteochondritis dissecans of the talus: The use of the mosaicplasty technique - preliminary report. Foot and Ankle International 18: 628-634, 1997

Hangody, L. ñ Kish, G. ñ K·rp·ti, Z.: Mosaicplasty for the treatment of osteochondritis dissecans of the knee. Journal of Sports Traumatology and Related Research, 20:126-132, 1998

Hangody, L. - Kish, G. - K·rp·ti, Z. et al.: Mosaicplasty for the treatment of articular cartilage defects: application in clinical practice. Orthopaedics, 21:751, 1998

Kish, G. - MÛdis, L. - Hangody, L.: Osteochondral mosaicplasty for the treatment of focal chondral and osteochondral lesions of the knee and talus in the athlete. Clinics in Sports Medicine 18: 45-66, 1999

Maranas, C., D. - Floudas, C., A. - Pardalos, P., M.: New results in the packing of equal circles in a square. Discrete Mathematics 142, 287-293, 1995

Tarnai, T. and G·sp·r, Zs.: Packing of equal circles in a square. Acta Technica Acad. Sci. Hung. 107, 123-135, 1995-96

Shapiro, F. - Koide, S. - Glimcher, M., J.: Cell origin and differentiation in the repair of full-thickness defects of articular cartilage. J. Bone Joint Surg. 75A: 532-553, 1993

Desjardins, M., R. - Hurtig, M., B. - Palmer, N., C.: Heterotopic transfer of fresh and cryopreserved autogenous articular cartilage in the horse. Vet. Surg. 20: 434-445, 1991

Bobic, V.: Arthroscopic osteochondral autograft transplantation in anterior cruciate ligament reconstruction: a preliminary clinical study. Knee Surg. Sports Traumatol. Arthroscopy 3: 262-264, 1996

Johnson, L., L. ñ Martin, S., D. ñ Golden, D., B. et al.: Autogenous osteochondral grafts from the proximal tibiofibular joint: a novel donor site. Proceedings of 2nd Symposium of International Cartilage Repair Society, Boston, MA, November 16-18, 1998

Christel, P. - Versier G. - Landreau, Ph. - Djian, P.: Les greffes osteo-chondrales selon la technique de la mosaicplasty. Maitrise OrthopÈdique 76, 1-13, 1998

St‰ubli, H., U. ñ D¸rrenmatt, U. ñ Porcellini, B. ñ Rauschning, W.: Patellofemoral articular cartilage contact zones and potential trochlear cartilage harvesting sites. Proceedings of 2nd Symposium of International Cartilage Repair Society, Boston, MA, November 16-18, 1998

Jakob, R., P. ñ Mainil-Varlet, P. ñ Saager, C. ñ Gautier, E.: Mosaicplasty in cartilaginous lesions over 4 squarecm and indications outside the knee. Cartilage Repair ñ 2nd Fribourg International Symposium ñ Book of abstracts, 1997

Imhoff, A., B. ñ Oettl, G., M. ñ Burkart, A. ñ Traub, S.: Extended indication for osteochondral autografts in different joints. Proceedings of 2nd Symposium of International Cartilage Repair Society, Boston, MA, November 16-18, 1998

Gautier, E. - Ganz, K. - Kr¸gel, N. - Ganz, R.: Osteochondral autografts in the hip joint ñ anatomic considerations and surgical approaches. Proceedings of 2nd Symposium of International Cartilage Repair Society, Boston, MA, November 16-18, 1998

Gautier, E. and Jakob, R., P.: Osteochondral autografts for the treatment of avascular necrosis of the femoral head ñ short term results. Proceedings of 2nd Symposium of International Cartilage Repair Society, Boston, MA, November 16-18, 1998

Gambardella, R., A.: Osteochondral grafting: a multicenter review of clinical results. Proceedings of 2nd Symposium of International Cartilage Repair Society, Boston, MA, November 16-18, 1998

Chow, J., C.: Autologous Osteochondral transplantation by the COR system. 17th Annual Cherry Blossom Seminar, 16-18 April, 1998, Washington, DC ñ Book of abstracts, 1998

Paletta, G., A. Jr. ñ Hannafin, J. ñ Ibarra, C. et al.: Histologic, biomechanical and MR image evaluation of autogenous osteochondral plug transplantation in a dog model. Proceedings of 2nd Symposium of International Cartilage Repair Society, Boston, MA, November 16-18, 1998