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

Purpose: Osteochondral transplantation is one of the useful treatments for articular cartilage defect. However, the histologic change of the implanted cartilage has not been reported in detail. We investigated the histology of exact-fit osteochondral transplants used to repair articular cartilage defects in an animal model. Type of Study: This was a nonrandomized control study using an animal model. Methods: Sixteen skeletally mature female Japanese white rabbits were used in the study. The region of the femoral groove was selected as the site for the osteochondral defect. A full-thickness cylindrical defect (7 mm in diameter and 7 mm in depth) through the articular cartilage and into the subchondral bone was made using the Osteochondral Autograft Transfer System (Arthrex, Naples, FL). The entire osteochondral fragment was removed and then returned to its original site in the femoral condyle precisely. Thus, the defect was repaired with an autogenous osteochondral transplantation of exactly the same size and configuration as the defect. Specimens were obtained 2, 4, 12, and 24 weeks postoperatively and were analyzed both macroscopically and histologically. Results: Macroscopically, there was smooth continuity of the articular surface and the integration of the graft to the normal host cartilage. However, histologic examination showed that the layer of the grafted cartilage was thicker than that of the normal host cartilage and the extracellular matrix of the implanted cartilage exhibited a stronger staining pattern with safranin-O fast green than the normal cartilage. Cell density was higher in the grafted cartilage, particularly in the middle and the deep zones. Round and polygonal hypertrophic clusters of chondrocytes were observed in the middle and deep zones of the grafted cartilage. Conclusions: The histologic properties of the exact-fit implanted cartilage were different from that of normal articular cartilage. Further investigation of mechanical and structural properties of grafted cartilage is necessary to verify the long-term effects of osteochondral transplantation.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 7 (September), 2001: pp 747–751     

关节镜自体骨软骨移植治疗膝关节软骨损伤

目的观察自体骨软骨移植治疗膝关节软骨缺损的效果。方法对7例膝关节股骨髁负重部位软骨损伤患者行膝关节镜清理术。摘除关节腔游离软骨碎块2例，半月板部分切除3例，髌上滑膜内侧皱襞切除3例。在股骨内侧髁部取自体骨软骨柱3～5枚，移植到股骨内侧髁软骨损伤部位。结果7例患者手术后伤口Ⅰ期愈合。随访期内6例患者疼痛症状消失。关节肿胀、假性交锁症状均消失。X线片显示移植骨软骨位置良好。结论自体软骨移植能缓解关节软骨损伤后出现疼痛、交锁症状，修复后的软骨为透明软骨。     

Autologous chondrocyte implantation and osteochondral cylinder transplantation in cartilage repair of the knee joint. A prospective,comparative trial

BACKGROUND: Current methods used to restore the joint surface in patients with localized articular cartilage defects include transplantation of an autologous osteochondral cylinder and implantation of autologous chondrocytes. The purpose of this study was to evaluate the clinical and histological outcomes of these two techniques. METHODS: We performed a prospective clinical study to investigate the two-year outcomes in forty patients with an articular cartilage lesion of the femoral condyle who had been randomly treated with either transplantation of an autologous osteochondral cylinder or implantation of autologous chondrocytes. Biopsy specimens from representative patients of both groups were evaluated with histological staining, immunohistochemistry, and scanning electron microscopy. RESULTS: According to the postoperative Lysholm score, the recovery after autologous chondrocyte implantation was slower than that after osteochondral transplantation at six months (p < or = 0.015), twelve months (p < or = 0.001), and twenty-four months (p < or = 0.012). On the basis of the Meyers score and the Tegner activity score, the results were equally good with the two methods two years after treatment. Histomorphological evaluation of biopsy specimens within two years after autologous chondrocyte implantation demonstrated a complete, mechanically stable resurfacing of the defect in all patients. The tissue consisted mainly of fibrocartilage, while localized areas of hyaline-like regenerative cartilage could be detected close to the subchondral bone. Although a gap remained at the site of the transplantation in all five biopsy specimens examined as long as two years after osteochondral cylinder transplantation, histomorphological analysis and scanning electron microscopy revealed no differences between the osteochondral transplants and the surrounding original cartilage. CONCLUSIONS: Both treatments resulted in a decrease in symptoms. However, the improvement provided by the autologous chondrocyte implantation lagged behind that provided by the osteochondral cylinder transplantation. Histologically, the defects treated with autologous chondrocyte implantation were primarily filled with fibrocartilage, whereas the osteochondral cylinder transplants retained their hyaline character, although there was a persistent interface between the transplant and the surrounding original cartilage. Limitations of our study included the small number of patients, the relatively short (two-year) follow-up, and the absence of a control group.     

Knorpeldefekte am Kniegelenk und autogene osteochondrale Zylindertransplantation

Objective Complete, lasting coverage of chondral defects of femoral condyles with hyaline cartilage. Indications Pain, disturbance of function due to chondral defects of weight-bearing joint sections grade III and IV according to Outerbridge and osteochondritis dissecans stage 4 and 5 according to Rodegerdts &; Gleissner. Contraindications Arthritis, infection, preexisting and persisting instability, axial malalignment. Surgical Technique Anteromedial or anterolateral arthrotomy to evaluate the size of the chondral defect, removal of the cartilage defect by cutting out cartilage-bone cylinders with the Twin Diamond Transplantation Technique (TDTT). Harvesting of appropriately sized cartilage-bone cylinders with healthy hyaline cartilage from non-weight-bearing areas of the posterior or anterior articular surface with the TDTT. Transplantation of the cartilage-bone cylinder “press-fit” into the prepared defect without further fixation. Refilling of the defects caused by harvesting with corresponding periosteum-covered bone cylinders from the iliac crest or with bone substitute materials. Results In 1996 and 1997, 20 patients with cartilage damage of a femoral condyle were treated by osteochondral cylinder transplantation. All 20 patients were questioned as to their subjective assessment of the outcome and reexamined 6, 12, and 24 months postoperatively. The evaluation of the results was performed using Meyers and Lysholm scores and the Tegner activity scale 3, 6, 12, and 24 months postoperatively. Five women and 15 men had cartilage defects measuring from 3.22 to 4.25 cm². 24 months postoperatively, 17 patients felt significant and three patients slight improvement. According to the evaluation criteria of the Meyers score, results in five patients were considered excellent, in 13 good, and in two moderate. According to the Lysholm score, 15 patients were judged as being excellent and five as being good, and according to the Tegner activity scale, nine were considered excellent, nine good, and two moderate. Reasons for the two moderate results were remaining activity-related pain and knee flexion limited to 120°. In both patients an additional osteochondral cylinder had been harvested from the posterior aspect of a femoral condyle.     

Autologous osteochondral transplantation

The surface of diarthrodial joints is covered by hyaline cartilage whose regeneration capacity is extremely limited. Conventional surgical techniques enable repair of full-thickness articular cartilage defects only by fibrous cartilage having poor mechanical properties. Recently, new techniques have been developed to provide hyaline or hyaline-like repair tissue in the treatment of full-thickness cartilage defects. Autologous osteochondral transplantation involves press-fit implantation of both bone and cartilage obtained from healthy articular surface. The principal indication for this technique is unifocal full-thickness chondral or osteochondral defects measuring 1 to 4 square centimeters. This surgical procedure can be performed openly or arthroscopically. The graft should be placed vertically and evenly to the joint surface. Although short-term and mid-term results are satisfactory, several problems have been reported including donor site morbidity, damage to cartilage, and incongruity and incorporation of the graft. Autologous osteochondral transplantation provides viable osteochondral units at a single stage and eliminates the need for culturing chondrocytes which is quite expensive. Currently, no surgical technique or medical treatment provide complete healing of articular cartilage defects. Autologous osteochondral transplantation is an important stage worthy of improvement in this respect.     

The effect of fibroblast growth factor-2 on autologous osteochondral transplantation

In this study, we performed a mechanical analysis of the effect of fibroblast growth factor-2 (FGF-2) on autologous osteochondral transplantation in a rabbit model. A full-thickness cartilage defect (diameter: 5 mm; depth: 5 mm) made in the right femoral condyle was treated with osteochondral transplantation using an osteochondral plug (diameter: 6 mm; depth: 5 mm) taken from the left femoral condyle. The animals were divided into three groups: Group I, the defect was filled with 0.1 ml of gelatin hydrogel containing 1 microg of FGF-2; Group II, the defect was filled with 0.1 ml of gelatin hydrogel only; Group III, the defect was left untreated. Thereafter, osteochondral plugs were transplanted and the transplanted osteochondral grafts were evaluated mechanically and histologically at postoperative weeks 1, 3, 8 and 12. The structural property of the osteochondral graft was significantly greater in Group I than in Groups II and III at postoperative week 3. Histological analysis at 3 weeks revealed a tendency towards increased subchondral bone trabeculae in Group I compared with the other groups. Autologous osteochondral grafts transplanted with gelatin hydrogel containing FGF-2 acquired adequate stiffness at an early postoperative phase.     

Minimum 5-year results of focal articular prosthetic resurfacing for the treatment of full-thickness articular cartilage defects in the knee

Introduction  

The purpose of this study was to evaluate the results of a contoured focal articular femoral condyle resurfacing prosthetic in the treatment of full-thickness cartilage and osteochondral defects at the medial femoral condyle of the knee beyond 5 years.     

A morphologic,biochemical, and biomechanical assessment of short-term effects of osteochondral autograft plug transfer in an animal model

Purpose: The objective of this study was to assess the short-term changes that occur after an osteochondral autograft plug transfer from the femoral trochlea to the medial femoral condyle in a goat model. Type of Study: Articular cartilage repair animal study. Methods: Six adult male goats were used in this study. Two 4.5-mm osteochondral plugs were transferred from the superolateral femoral trochlea to 2 recipient sites in the central portion of the medial femoral condyle for a survival period of 12 weeks. Postmortem, the global effects of the procedure were assessed by gross morphologic inspection and by analyzing the synovial DNA for inflammatory response. The recipient sites were also evaluated histologically and biomechanically. Metabolic activity was determined by ³⁵SO₄ uptake, and viability was assessed using a live/dead stain and by confocal laser microscopy. Results: There was no evidence of significant gross morphologic or histologic changes in the operative knee as a result of the osteochondral donor or recipient sites. The patella, tibial plateau, and medial meniscus did not show any increased degenerative changes as a result of articulating against the donor or recipient sites of the osteochondral autografts. Analysis of synovial DNA revealed no inflammatory response. Biomechanically, 6- to 7-fold greater stiffness was noted in the cartilage of the transferred plugs compared with the control medial femoral condyle. Furthermore, on histologic examination, the healing subchondral bone interface at the recipient site had increased density. Glycosaminoglycan synthesis as determined by ³⁵SO₄ uptake was upregulated in the transplanted cartilage plug relative to the contralateral control, showing a repair response at the site of implantation. And finally, confocal microscopy showed 95% viability of the transferred plugs in the medial femoral condyle region. Conclusions: Our findings demonstrate the ability to successfully transfer an osteochondral autograft plug with maintenance of chondrocyte cellular viability. The transferred cartilage is stiffer than the control medial femoral condyle cartilage, and there is concern regarding the increased trabecular mass in the healing subchondral plate, but these do not result in increased degenerative changes of the opposing articular surfaces in the short term.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 8 (October), 2001: pp 856–863     

Transplantation of free tibial periosteal grafts for the repair of articular cartilage defect: An experimental study

Background:

Articular chondrocytes have got a long lifespan but rarely divides after maturity. Thus, an articular cartilage has a limited capacity for repair. Periosteal grafts have chondrogenic potential and have been used to repair defects in the articular cartilage. The purpose of the present study is to investigate the differentiation of free periosteal grafts in the patellofemoral joint where the cambium layer faces the subchondral bone and to investigate the applicability of periosteal grafts in the reconstruction of articular surfaces.

Materials and Methods:

The study was carried out over a period of 1 year on 25 adult, male Indian rabbits after obtaining permission from the institutional animal ethical committee. A full-thickness osteochondral defect was created by shaving off the whole articular cartilage of the patella of the left knee. The defect thus created was grafted with free periosteal graft. The patella of the right knee was taken as a control where no grafting was done after shaving off the articular cartilage. The first animal was used to study the normal histology of the patellar articular cartilage and periosteum obtained from the medial surface of tibial condyle. Rest 24 animals were subjected to patellectomy, 4 each at serial intervals of 2, 4, 8, 16, 32 and 48 weeks and the patellar articular surfaces were examined macroscopically and histologically.

Results:

The grafts got adherent to the underlying patellar articular surface at the end of 4 weeks. Microscopically, graft incorporation could be appreciated at 4 weeks. Mesenchymal cells of the cambium layer were seen differentiating into chondrocytes by the end of 4 weeks in four grafts (100%) and they were arranged in a haphazard manner. Till the end of 8 weeks, the cellular arrangement was mostly wooly. At 16 weeks, one graft (25%) had wooly arrangement of chondrocytes and three grafts (75%) had columnar formation of cells. Same percentage was maintained at 32 weeks. Four grafts (100%) at 48 weeks showed columnar orientation. The control side showed no changes over the shaved off articular surface in all the rabbits. One rabbit at 4 weeks had a dislocation of the patella on the control side. None of the rabbits developed any infection or wound dehiscence.

Conclusion:

Autologous periosteal graft transplantation can be a promising substitute for articular cartilaginous defects.     

Repair of articular cartilage defects with cultured chondrocytes on polysulphonic membrane: experimental studies in rabbits

INTRODUCTION: Autologous osteochondral transplantation is one method that can be used to create hyaline or hyaline-like repair in a defect area. The purpose of the present study was to repair full-thickness articular cartilage defects in 9 rabbit knee joints with autologous cultured chondrocytes. METHODS: An articular cartilage defect was created on the patellar groove of the femur. The defect was filled with chondrocytes cultured in vitro and placed into the knee on a polysulphonic membrane. At 8 weeks after the operation, the reparative tissue was analyzed macroscopically and histologically. RESULTS: At 8 weeks after the operation, the surfaces of the reparative tissue were smooth, and the defects were filled with mature hyaline cartilage in 5 cases. In 2 cases, the reparative hyaline cartilage was immature and there was worse integration of grafted tissue into the adjacent normal cartilage. In 2 cases, the surface of the grafted area was irregular, and the reparative tissue was disintegrated and incompletely differentiated. CONCLUSION: The results suggest that transplantation of autologous chondrocytes cultured in vitro and placed into the knee on polysulphonic membrane is effective in repairing an articular cartilage defect.     

Transplantation of osteochondral allografts after cold storage

BACKGROUND: Transplantation of fresh osteochondral allografts stored at hypothermia into knee cartilage defects is a common procedure; however, the length of time that allografts can be stored prior to transplantation is controversial and has been determined, in part, by the results of vital stain uptake by chondrocytes. This study was performed to further define the limits of allograft storage. METHODS: Articular cartilage from six cadavers was stored for up to fifty-one days in tissue-culture media, and histologic sections were evaluated histomorphometrically to quantify the loss of chondrocytes. Samples of the cartilage were also placed into tissue culture to assess cell growth. Animal studies were performed in parallel on sixteen adult baboons with osteochondral allografts transplanted into the medial femoral condyle. Prior to transplantation, all allografts were stored in RPMI-1640 with 10% fetal calf serum at 4 degrees to 6 degrees C for up to eighty-five days. The transplants were graded on their gross and histological appearance, as well as their histochemical properties. RESULTS: Many of the human samples stored at hypothermia in culture media for up to forty days retained some recognizable chondrocytes, but morphometry showed a gradual, significant decrease in the number of chondrocytes after nine days (p = 0.001). In addition, the cell outgrowth occurred from all specimens stored for up to fifteen days but not in samples stored for longer than thirty-four days. In animal studies, transplanted allograft cartilage that had been stored for less than eighteen days looked smooth and glistening, but grafts stored for over twenty-one days were pale, pitted, fragmented, or yellow, and chondrocytes were absent. CONCLUSIONS: Time-dependent loss of chondrocytes in articular cartilage stored at hypothermia, especially in specimens stored for longer than fifteen to twenty days, was observed in this study. Cartilage allografts transplanted into nonhuman primates after twenty-one days of storage underwent more severe degenerative changes than allografts that had been stored for less than twenty-one days. These findings suggest caution when transplanting cartilage stored at hypothermia for over twenty days.     

An investigation of 2 techniques for optimizing joint surface congruency using multiple cylindrical osteochondral autografts

Purpose: To compare 2 techniques for optimizing joint congruency for miniature osteochondral autografting in the knee: intrinsic postoperative forces acting on overdrilled autografts protruding from the femur versus alignment by a surgeon at the time of grafting. Type of Study: Controlled animal model experiment. Methods: A full-thickness cartilage defect was created on the weight-bearing surface of the medial femoral condyle of 13 mature sheep. Three 4.5 × 10 mm cylindrical autografts were inserted into 14-mm deep recipient holes such that the grafts were held in place by side-wall friction alone. One treatment group received grafts that were delivered flush with the surrounding cartilage and the second group received grafts that were left 2-mm proud of the joint surface. Results: Three months postoperatively, the proud grafts had been repositioned by weight bearing but perigraft fissuring and fibroplasia, and subchondral cavitations were serious complications. It is suspected that these complications were caused by excessive motion between the graft and recipient site in the proud grafts. Conclusions: Grafts should be delivered flush with the joint surface when performing osteochondral transfers to avoid graft micromotion and the consequent interference with graft integration and function.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 1 (January), 2001: pp 50–55     

Osteochondritis dissecans of the lateral femoral condyle following total resection of the discoid lateral meniscus

Purpose: The purpose of this study was to describe the clinical presentation of 6 athletically active children with symptomatic osteochondritis dissecans (OCD) of the lateral femoral condyle following total resection for a torn discoid lateral meniscus and to discuss its cause. Type of Study: Case series. Methods: Six patients in whom OCD affecting the lateral femoral condyle developed after total resection of the discoid lateral meniscus participated in a detailed clinical, radiologic, and arthroscopic review. The average age at the time of meniscectomy was 9 years (range, 6 to 12 years). At a mean of 50 months (range, 36 to 65 months) after surgery they developed recurrent pain in the treated knee; all had radiologic abnormalities at the lateral femoral condyle consistent with OCD. Before the recurrence of pain, all patients had been continuously engaged in sports activity. Radiologic and arthroscopic findings of the OCD lesions were assessed. Clinical outcomes of surgical treatment for OCD were also documented. Results: The radiographic evaluation showed all lesions to be in the central portion of the lateral femoral condyle on the anteroposterior views and posteriorly next to a line extending distally from the posterior femoral cortex on the lateral views. Arthroscopic evaluation revealed softening in 2 knees, a separated fragment in 2 knees, and a completely loose fragment in 2 knees. All lesions were treated surgically, including 2 drillings of the lesion, 2 fixations of separated fragment, and 2 excisions of loose bodies with drilling. At an average follow-up period of 51 months (range, 22 to 77 months), all patients but 1 were asymptomatic. Conclusions: Repeated impaction in sports activities on the immature osteochondral structures under altered mechanical force transmission after total resection of the discoid meniscus might be a predisposing factor in the development of OCD in the lateral femoral condyle.Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 17, No 6 (July-August), 2001: pp 608–612     

Atelocollagen-associated autologous chondrocyte implantation for the repair of chondral defects of the knee: a prospective multicenter clinical trial in Japan

Background

New tissue-engineering technology was developed to create a cartilage-like tissue in a three-dimensional culture using atelocollagen gel. The minimum 2-year followup outcome of transplanting autologous chondrocytes cultured in atelocollagen gel for the treatment of full-thickness defects of cartilage in knees was reported from the single institution. The present multicenter study was conducted to determine clinical and arthroscopic outcomes in patients who underwent atelocollagen-associated autologous chondrocyte implantation for the repair of chondral defects of the knees.

Methods

At six medical institutes in Japan, we prospectively evaluated the clinical and arthroscopic outcomes of transplanting autologous chondrocytes cultured in atelocollagen gel for the treatment of full-thickness defects of cartilage in 27 patients (27 knees) with cartilage lesions on a femoral condyle or on a patellar facet over 24 months.

Results

The Lysholm score significantly increased from 60.0 ± 13.7 points to 89.8 ± 9.5 points (P = 0.001). Concerning the ICRS grade for arthroscopic appearance, 6 knees (24%) were assessed as grade I (normal) and 17 knees (68%) as grade II (nearly normal). There were few adverse features, except for detachment of the graft in two cases.

Conclusions

We concluded that transplanting chondrocytes in a newly formed matrix of atelocollagen gel can promote restoration of the articular cartilage of the knee.     

Hyaline cartilage degenerates after autologous osteochondral transplantation.

OBJECTIVES: Autologous osteochondral grafting is a well-established clinical procedure to treat focal cartilage defects in patients, although basic research on this topic remains sparse. The aim of the current study was to evaluate (1) histological changes of transplanted hyaline cartilage of osteochondral grafts and (2) the tissue that connects the transplanted cartilage with the adjacent cartilage in a sheep model. METHOD: Both knee joints of four sheep were opened surgically and osteochondral grafts were harvested and simultaneously transplanted to the contralateral femoral condyle. The animals were sacrificed after three months and the received knee joints were evaluated histologically. RESULTS: Histological evaluation showed a complete ingrowth of the osseous part of the osteochondral grafts. A healing or ingrowth at the level of the cartilage could not be observed. Histological evaluation of the transplanted grafts according to Mankin revealed significantly more and more severe signs of degeneration than the adjacent cartilage, such as cloning of chondrocytes and irregularities of the articular surface. CONCLUSION: We found no connecting tissue between the transplanted and the adjacent cartilage and histological signs of degeneration of the transplanted hyaline cartilage. In the light of these findings, long-term results of autologous osteochondral grafts in human beings have to be followed critically.     

Autologous osteochondral transplantation using the diamond bone-cutting system (DBCS): 6–12 years’ follow-up of 35 patients with osteochondral defects at the knee joint

Thirty-five patients with severe osteochondral defects were treated by autologous osteochondral transplantation between 1986 and 1992. The majority of patients (27) suffered from osteochondrosis dissecans, while 8 patients presented with posttraumatic osteochondral defects. The grafts were harvested with a diamond bone cutter from the posterior part of the medial or lateral femoral condyle. In 29 patients the lesion was located at the lateral part of the medial femoral condyle, in 3 it was at the lateral femoral condyle, and in 3 at the patella. Twenty-nine patients could be examined at the follow-up between 6 and 12 years later (mean follow up 8.1 years). Using the standard cartilage evaluation form, the transplanted knees of 12 patients were graded as normal (grade I), 14 knees were nearly normal (grade II), while 3 patients presented with an abnormal result (grade III). All 3 of them had a varus malalignment and refused a high tibial correction osteotomy against our advice. No patient was assessed as severely abnormal (grade IV). The majority of patients improved their activity level and the functional status of the joint. Twelve patients developed new radiological signs of osteoarthrosis with a decrease in the radiological score of Kellgren and Lawrence by about one stage. We conclude that autologous osteochondral transplantation with the diamond bone-cutting system is an effective method in the treatment of severe osteochondral defects. Received: 17 April 2000     

Rib perichondrial grafts for the repair of full-thickness articular-cartilage defects. A morphological and biochemical study in rabbits

The purpose of this study was to investigate the use of perichondrial grafts in articular cartilage defects and to characterize the newly formed cartilage. In a rabbit model, rib perichondrium was used to repair full-thickness defects in the femoral condyle. The quality of repair was then evaluated histologically and biochemically at six and twelve weeks after grafting. Unacceptable results were obtained in 50 per cent of the rabbits. These failures were due to condylar fracture in 20 per cent, failure of graft attachment in 20 per cent, and infection in 10 per cent. The technique of grafting must be improved to increase the percentage of successful grafts in which neocartilage with a relatively normal chemical composition fills the articular cartilage defect. Successful grafts proliferate to fill the full-thickness defect with neocartilage, which has biochemical characteristics that are similar to those of hyaline cartilage.     

Osteochondral autologous transplantation in various joints

A chondral/osteochondral defect involving the articular surface of a joint is still a therapeutic problem. The goal of articular cartilage repair is restoration of cartilage congruity, accomplishing full painfree range of motion and elimination of cartilage detoriation. The use of autologous grafts was first reported by Wagner 1964. Now the use of cylindrical autograft plugs was described by Bobic 1996 and Hangody 1996. Operative management and early results of osteochondral cylindrical autograft plugs in the femoral condyle, patella, elbow and talar dome are presented. The arthroscopic/open use of autologous osteochondral grafts from the knee is indicated in osteochondral lesions in diameter from 1 to 3 cm, which can not be primarily refixed and in osteonecrosis at femoral condyle, patella, elbow, talar dome as well as shoulder.     

Chondral and osteochondral injuries associated with acute patellar dislocation

Purpose: The purpose of this study was to evaluate the frequency and precise pathology of articular cartilage injuries after acute patellar dislocation. Type of Study: Case series. Methods: In 39 consecutive knees with initial lateral patellar dislocation, the articular cartilage injuries were examined using arthroscopy or macroscopic observation. Results: Thirty-seven knees (95%) had articular cartilage injuries of the patellofemoral joint and 2 knees (5%) had no cartilage injury. In all 37 knees (95%), articular cartilage injuries were observed in the patella. The appearances were categorized into 3 groups: cracks alone (9 knees), cartilage defect caused by osteochondral or chondral fracture (7 knees), and cartilage defects caused by osteochondral or chondral fracture associated with cracks (21 knees). The main site of osteochondral fracture was the medial facet, and the main site of cracks was the central dome. Twelve knees (31%) had cartilage injury of the lateral femoral condyle. Conclusions: From this study, articular cartilage injuries, especially of the patella, seem to be common occurrences after acute patellar dislocation. Chondral and osteochondral injuries of the patella were classified into 3 groups.     

Autologe Chondrozytentransplantation

Untreated focal articular cartilage defects may lead to secondary osteoarthritis. Symptomatic full-thickness defects in young patients that are located in the medial or lateral femoral condyle, trochlea, or patella and range in size from 3 cm(2) to 10 cm(2) as well as defects of the ventral talus are indications for autologous chondrocyte transplantation (ACT). Another indication for ACT are cartilage defects for which previous operative measures have failed. Osteoarthritis and kissing lesions are contraindications. Axial malalignment and knee joint instability need to be corrected. Second-generation ACT procedures are based on three-dimensional biomaterials in which the articular chondrocytes are seeded prior to implantation. Randomized trials demonstrate clinical, radiographic, and histologic findings that are similar to marrow-stimulating techniques such as microfracture. Long-term studies are needed to determine the effect of ACT on the development of osteoarthritis.