Osteochondral autograft transplantation in the porcine knee

BACKGROUND: Knee articular cartilage defects are not an uncommon problem. Because articular cartilage is limited in its ability to heal, these defects are difficult to manage. HYPOTHESIS: Osteochondral autografts will provide less of a cavitary defect and more viable hyaline articular cartilage than will control knees. STUDY DESIGN: Controlled laboratory study. METHODS: Osteochondral autografts were grossly and microscopically evaluated in the porcine knee and compared with a control at 6 weeks, 3 months, and 6 months. In 18 porcine specimens, a 1-stage surgical procedure was performed to harvest an osteochondral graft from a nonweightbearing articular cartilage surface, and the graft was transplanted into a defect created in the weight-bearing region of the medial femoral condyle. In the opposite control knee, a similar defect was created in the medial femoral condyle; an osteochondral transplant was not performed. Six pigs each were sacrificed at 6 weeks, 3 months, and 6 months. RESULTS: Gross inspection of the control knees showed a cavitary defect. The defect grossly decreased in size with fibrous ingrowth seen on microscopic analysis. An increasing amount of fibrous tissue and fibrocartilage was present at the 3 time periods. Gross inspection of the graft knee showed a healed osteochondral plug with no obvious displacement, cavitary defects, or surrounding necrotic tissue at each time interval. Microscopic analysis revealed the graft knee contained viable hyaline cartilage and healed viable subchondral bone. At all time intervals, 75% to 100% of the hyaline cartilage was viable in all specimens. In 6-month specimens, bridging cartilage at the autograft-host junction was incomplete in 50%, partial in 33%, and complete in 17%. CONCLUSION: Osteochondral autografts in the porcine knee resulted in viable hyaline cartilage for up to 6 months; there was inconsistent bridging hyaline cartilage at the periphery. Grafts appeared to heal into existing subchondral bone without displacement or evidence of necrosis. CLINICAL RELEVANCE: This type of osteochondral transplant can be used as a reliable reconstructive alternative for osteochondral defects.     

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

BACKGROUND: The use of osteochondral autograft plugs can be restricted because of limited amount of donor material. HYPOTHESIS: A small osteochondral autograft plug placed in the center of a large defect in a sheep femoral condyle will yield results superior to either an untreated or a bone-grafted defect. STUDY DESIGN: Controlled laboratory study. METHODS: Twelve adult sheep underwent bilateral hindlimb surgery. On 1 limb, a 6-mm circular osteochondral autograft plug was placed in the center of a 10-mm circular defect in the medial femoral condyle. The gap between the plug and the condyle was filled with bone graft. On the contralateral side, the defect was either left untreated or filled with bone graft (control specimens). Animals were studied at 6 and 12 months under gross examination, high-resolution radiography, and histologic evaluation. RESULTS: At 6 months, 4 of 6 plugs healed and showed good maintenance of the joint surface and cartilage viability in the plugs. One plug fractured and resorbed, and 1 plug settled but healed. At 1 year, all 5 plugs healed, 1 having settled slightly (1 animal died earlier). The plug specimens showed better maintenance of the condyle contour at both times, and the central plug had hyaline-appearing cartilage. The control specimens were more irregular, had a fibrocartilage fill, and appeared flatter, although no gross cavitation or collapse was indicated. Composite cartilage scores on histologic evaluation were significantly higher for the plug specimens after 6 months (P = .02) and 1 year (P = .036) compared with controls. CONCLUSION: At 6 months and 1 year, a 6-mm osteochondral plug placed in a 10-mm defect better preserved the articular surface and contour of the condyle compared to untreated or bone-grafted defects. CLINICAL RELEVANCE: Osteochondral autograft plugs may be able to treat larger articular lesions without complete fill of the defect.     

Effects of small incongruities in a sheep model of osteochondral autografting

BACKGROUND: Exact reconstruction of an osteochondral defect by autogenous transplantation (mosaicplasty) is difficult given the variation in joint surface contour. Clinical and experimental studies do not show the extent to which incongruity can be tolerated in autografting. HYPOTHESIS: Grafted articular cartilage will hypertrophy to correct the incongruity created by recession of the transplanted surface. STUDY DESIGN: Controlled laboratory study. METHODS: To test the response of grafts to incongruities, osteochondral autografts were transplanted from the trochlea to the femoral condyle in adult male sheep stifle joints. In groups of 6 animals, graft surfaces were placed flush, countersunk 1 mm or countersunk 2 mm, then histologically analyzed 6 weeks after surgery. Cartilage thickness, condition of the articular surfaces, and preservation of hyaline characteristics were the primary features compared. RESULTS: Bony union, vascularization, and new bone formation were present in all grafts. Cartilage-to-cartilage healing did not occur. In flush specimens, cartilage changed minimally in thickness and histologic architecture. The specimens countersunk 1 mm demonstrated significant cartilage thickening (54.7% increase, P <.05). Chondrocyte hyperplasia, tidemark advancement, and vascular invasion occurred at the chondroosseous junction, and the surface remained smooth. Cartilage necrosis and fibrous overgrowth were observed in all grafts countersunk 2 mm. CONCLUSIONS: Minimally countersunk autografts possess a capacity for remodeling that can correct initial incongruities while preserving hyaline characteristics. Grafts placed deeper do not restore the contour or composition of the original articular surface. CLINICAL RELEVANCE: If preservation of normal hyaline cartilage is the objective, thin grafted articular cartilage can remodel, but the tolerance for incongruity is limited and probably less than that reported for an intra-articular fracture.     

Large osteochondral defects of the femoral condyle: press-fit transplantation of the posterior femoral condyle (MEGA-OATS)

BACKGROUND AND AIMS: Large osteochondral defects in the weight-bearing zone of the knee remain a challenging therapeutic problem. Surgical options include drilling, microfracturing, and transplantation of osteochondral plugs but are often insufficient for the treatment of large defects of the femoral condyle. PATIENTS AND METHODS: Large osteochondral defects of the femoral condyle (mean defect size 7.2 cm(2) range 3-20) were treated by transplantation of the autologous posterior femoral condyle. Between 1984 and 2000, 29 patients were operated on: in 22 the medial, in 6 the lateral femoral condyle, and in one the trochlear groove was grafted. Thirteen patients underwent simultaneous high tibial valgus osteotomy. In the first series (1984-1999) the graft was temporarily fixed with a screw ( n=12), but from 1999 we used a newly developed press-fit technique ( n=17) avoiding screw fixation of the graft. The operative technique comprising graft harvest, defect preparation, transplantation, and fixation is described. Patients were clinically evaluated using the Lysholm score, and magnetic resonance imaging with intravenous contrast was performed 6 and 12 weeks after surgery (mean follow-up 17.7 months (range 3-46). RESULTS: Pain and swelling were reduced in 26 patients. Three patients of the first series reported persistent problems and were subjectively not satisfied. The mean Lysholm score rose from preoperatively 52 to 77 points after 3 months, 74 after 6, 88 after 12, and 95 after 18. Magnetic resonance imaging showed good graft viability in all cases. We saw one arthrofibrosis after 6 months but noted no problems related to the loss of the missing posterior condyle. CONCLUSION: Large osteochondral defects of the femoral condyle can be treated by transplantation of the autologous posterior femoral condyle. The use of only one osteochondral piece renders better approximation of the femoral cartilage curvature and thus joint congruence than in mosaic plasty. However, whether loss of the posterior condyle has a long-term negative impact on the knee joint remains to be elucidated.     

Comparison of fresh osteochondral autografts and allografts: a canine model

BACKGROUND: Osteochondral autografts and allografts have been widely used in the treatment of isolated grade IV articular cartilage lesions of the knee. However, the authors are not aware of any study that has prospectively compared fresh osteochondral autografts to fresh allografts with regard to imaging, biomechanical testing, and histology. HYPOTHESIS: The imaging, biomechanical properties, and histologic appearance of fresh osteochondral autograft and fresh allograft are similar with respect to bony incorporation into host bone, articular cartilage composition, and biomechanical properties. STUDY DESIGN: Controlled laboratory study. METHODS: Eighteen adult dogs underwent bilateral knee osteochondral graft implantation after creation of an Outerbridge grade IV cartilage defect. One knee received an autograft, and the contralateral knee received a fresh allograft. Nine dogs were sacrificed at 3 months, and 9 dogs were sacrificed at 6 months. Graft analysis included gross examination, radiographs, magnetic resonance imaging, biomechanical testing, and histology. RESULTS: Magnetic resonance imaging demonstrated excellent bony incorporation of both autografts and allografts. Biomechanical testing demonstrated no significant difference between autografts versus allografts versus control at 3 or 6 months (P = .36-.91). A post hoc calculation showed 80% power to detect a 30% difference between allograft and control. Histologic examination showed normal cartilage structure for both autografts and allografts. CONCLUSION: Fresh osteochondral autograft and fresh allograft tissues are not statistically different with respect to bony incorporation, articular cartilage composition, or biomechanical properties up to 6 months after implantation. CLINICAL RELEVANCE: The use of fresh allograft tissue to treat osteochondral defects eliminates morbidity associated with harvesting autograft tissue without compromising the results of the surgical procedure.     

Modified autologous matrix-induced chondrogenesis (AMIC) for the treatment of a large osteochondral defect in a varus knee: a case report

This paper presents a case report of a 27-year-old male patient affected by a large osteochondral defect of the medial femoral condyle (6 cm²) in a varus knee. He was treated with a combined approach consisting of high tibial osteotomy and autologous matrix-induced chondrogenesis technique enhanced by a bone marrow-enriched bone graft. Twelve months after surgery, the patient reported considerable reduction in pain and significant increase in his quality of life. A hyaline-like cartilage completely covered the defect and was congruent with the surrounding condyle cartilage as revealed by MRI and by a second-look arthroscopy. Level of evidence IV.     

Weightbearing ovine osteochondral defects heal with inadequate subchondral bone plate restoration: implications regarding osteochondral autograft harvesting

Purpose

It is unknown what causes donor site morbidity following the osteochondral autograft transfer procedure or how donor sites heal. Contact pressure and edge loading at donor sites may play a role in the healing process. It was hypothesized that an artificially created osteochondral defect in a weightbearing area of an ovine femoral condyle will cause osseous bridging of the defect from the upper edges, resulting in incomplete and irregular repair of the subchondral bone plate.

Methods

To simulate edge loading, large osteochondral defects were created in the most unfavourable weightbearing area of 24 ovine femoral condyles. After killing at 3 and 6?months, osteochondral defects were histologically and histomorphometrically evaluated with specific attention to subchondral bone healing and subchondral bone plate restoration.

Results

Osteochondral defect healing showed progressive osseous defect bridging by sclerotic circumferential bone apposition. Unfilled area decreased significantly from 3 to 6 months (P?=?0.004), whereas bone content increased (n.s.). Complete but irregular subchondral bone plate restoration occurred in ten animals. In fourteen animals, an incomplete subchondral bone plate was found. Further common findings included cavitary lesion formation, degenerative cartilage changes and cartilage and subchondral bone collapse.

Conclusions

Osteochondral defect healing starts with subchondral bone plate restoration. However, after 6 months, incomplete or irregular subchondral bone plate restoration and subsequent failure of osteochondral defect closure is common. Graft harvesting in the osteochondral autograft transfer procedure must be viewed critically, as similar changes are also present in humans.

Level of evidence

Prognostic study, Level III.     

Osteochondral lesion located at the lateral femoral condyle reconstructed by the transplantation of tissue-engineered cartilage in combination with a periosteum with bone block: a case report

We report herein the successful treatment of a patient with an osteochondral defect extending to the edge of the lateral femoral condyle by transplantation of tissue-engineered cartilage made ex vivo using atelocollagen gel covered by periosteum with a bone block to reconstruct the normal contour of the femoral condyle.     

Results of arthroscopic fixation of osteochondritis dissecans lesion of the knee with cylindrical autogenous osteochondral plugs

BACKGROUND: In situ fixation of unstable lesions of osteochondral dissecans of the knees with cylindrical osteochondral autograft transplantation has been reported to provide excellent results with healing of the osteochondral dissecans fragment. PURPOSE: To evaluate the clinical results and magnetic resonance imaging findings of the osteochondral dissecans of knees treated with in situ fixation of the osteochondral fragments with osteochondral autograft transplantation. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Twelve knees (12 patients; mean age, 16.0 years) with osteochondral dissecans lesions were treated with in situ fixation with autogenous osteochondral plugs. The mean lesion size was 2.4 cm(2) (range, 1.0-4.9 cm(2)). The osteochondral dissecans lesions were located on the medial femoral condyle in 10 patients and on the lateral femoral condyle in 2 patients. Seven lesions were located in the weightbearing area. The International Cartilage Repair Society classification in arthroscopic findings was grade II in 1 patient, grade III in 8 patients, and grade IV in 3 patients. All patients were evaluated with the Hughston Rating Scale form with the mean follow-up at 4.5 years (range, 2.8-5.9 years). The interface between the osteochondral fragment and subchondral bone and changes in donor site of the osteochondral graft were evaluated with T2-weighted magnetic resonance image up to 12 months postoperatively. RESULTS: The Hughston Rating Scale scored 8 knees as excellent, 3 as good, and 1 as fair. The interface between the osteochondral fragment and subchondral bone had disappeared on magnetic resonance image by 3 months postoperatively in all cases. No complications arising from the donor site area were observed. Signal intensity of donor site changed from high signal preoperatively to homogeneous surrounding cancellous bone by 1 year postoperatively. CONCLUSION: Biological fixation of the osteochondral dissecans lesion with cylindrical osteochondral autograft provided healing of the osteochondral fragments.     

The use of carbon fiber pads inchondral injury and early osteoarthritis

Articular cartilage damage in young active individuals is a cause of pain and disability and may lead to earlyosteoarthritis. Methods proposed for treatment include intact cartilage grafting, osteochondral grafting, and isolated chondrocyte autografts. However, in some joints it is possible to repair the surface by stimulating the patient's repair mechanisms with techniques such as drilling and abrasion arthroplasty The repair tissue produced by such procedures, however, is usually of inferior quality with regard to the collagen (type I and III) and the proteoglycans. The use of carbon fiber pads as a support for such repair material has proved successful, particularly for the medial femoral condyle of the knee over a period of 5.8 years. The concept of supporting the matrix of the repair material which is formed from the subchondral bone by the use of a carbon fiber matrix is valuable and may be developed by the use of other biodegradable matrices in the future.     

Fresh osteochondral allografting

The treatment of articular cartilage defects in the knee is a difficult challenge. Fresh, small-fragment osteochondralallografting is a technique involving the transplantation of articular (hyaline) cartilage into the defective joint surface. The graft, a composite of living cartilage and a thin layer of underlying subchondral bone, provides a mature matrix with viable chondrocytes along with an osseous component that provides a surface for fixation and integration with the host. Fresh allografting is particularly useful in larger lesions (greater than 2 cms) or when associated osseous defects are present. Clinical experience with fresh osteochondral allografts now extends over 2 decades. Up to 90% of individuals treated for femoral condyle lesions are improved. The allograft tissue appears well tolerated by the host, with documented long-termsurvival of chondrocytes and intact matrix. Successful clinical outcomes have established fresh osteochondrall allografting as an appropriate alternative in the treatment of chondral and osteochondral lesions of the knee.     

Aspects of Magnetic Resonance in the surgical treatment of osteochondral lesions of the knee

AIM: To assess the magnetic resonance (MR) appearance of knee cartilage chondroplasty procedures and their evolution in order to evaluate the usefulness of the method in monitoring postoperative rehabilitation. MATERIALS AND METHODS: Sixty-two patients treated with knee chondroplasty for high-grade cartilage injuries (Noyes' stages II and III) were examined with MR. Forty patients were treated with abrasion chondroplasty, fifteen with osteochondral graft in the injury site and seven with the matrix-induced autologous chondrocyte transplant technique. All patients were operated on by the same orthopaedic team and examined with the same MR protocol. The MR follow-up was performed six months and one year after surgery in the patients treated with abrasion chondroplasty and osteochondral graft, and one week, three months and one year after surgery in the patients treated with cartilage transplant. In the patients treated with abrasion chondroplasty we assessed the fibrocartilage repair and the subchondral bone features, in the patients treated with osteochondral graft we examined the cartilage, the subchondral bone and the graft borders, while in the patients treated with cartilage transplant we evaluated the features and the evolution of the transplant and the subchondral bone. Arthrosynovitis was assessed in all patients. In seven patients a cartilage repair biopsy was performed in arthroscopy. RESULTS: In all the patients MR imaging proved useful in monitoring the chondroplasty. In the patients treated with abrasion chondroplasty the cartilage repair appeared as a hypointense non-homogeneous irregular strip of tissue that replaced the articular surface. The subchondral bone was sclerotic with some geodes. In the later examination the repair was unchanged. In the patients treated with osteochondral graft the articular cartilage was similar to the adjacent hyaline cartilage, although more non-homogeneous. The subchondral bone was sclerotic and in three cases oedematous. In four cases the graft extended beyond the articular border. In the cartilage transplant the matrix appeared as a hypointense stripe after a week due to hydration and it had thinned with signal reduction in the later follow-ups. In the cases with unfavourable clinical evolution the subchondral bone was oedematous and sclerotic in the later examinations. In the cases with unfavourable clinical evolution there was moderate arthrosynovitis, regardless of the chondroplasty technique performed. CONCLUSIONS: MR imaging is useful for monitoring the maturation and the integration of knee chondroplasty and can be proposed as a replacement of arthroscopy for the assessment of postoperative rehabilitation.     

Disease-specific clinical problems associated with the subchondral bone

The subchondral bone is involved in a variety of diseases affecting both the articular cartilage and bone. Osteochondral defects in distinct locations and of variable sizes are the final results of different etiologies. These include traumatic osteochondral defects, osteochondritis dissecans, osteonecrosis, and osteoarthritis. Traumatic osteochondral defects are caused by osteochondral fractures, separating an osteochondral fragment that includes articular cartilage and both subchondral and trabecular bone from the joint surface. In osteochondritis dissecans, the disease originates in the subchondral bone and secondarily affects the articular cartilage. Location, stage, size, and depth of osteochondral lesions play a role in the treatment of traumatic osteochondral defects and osteochondritis dissecans. Surgical options include fragment refixation, transplantation of osteochondral autografts, or bone restoration by impacted cancellous bone grafts combined with autologous chondrocyte transplantation. An insufficiency fracture of the subchondral bone may be the initiating factor of what was formerly believed to be a spontaneous osteonecrosis of the knee (SPONK). Recent histopathological studies suggest that each stage of SPONK reflects different types of bone repair reactions following a fracture of the subchondral bone plate. Osteoarthritis is a disease that does affect not only the articular cartilage, but also the subchondral bone. Reconstructive surgical techniques aim at preserving joint function, inducing fibrocartilaginous repair, and at correcting malalignment. This review summarizes the current status of the clinical treatment of traumatic osteochondral defects, osteochondritis dissecans, osteonecrosis, and osteoarthritis as they affect the subchondral bone region and its adjacent structures.     

MR imaging of osteochondral grafts and autologous chondrocyte implantation

Surgical articular cartilage repair therapies for cartilage defects such as osteochondral autograft transfer, autologous chondrocyte implantation (ACI) or matrix associated autologous chondrocyte transplantation (MACT) are becoming more common. MRI has become the method of choice for non-invasive follow-up of patients after cartilage repair surgery. It should be performed with cartilage sensitive sequences, including fat-suppressed proton density-weighted T2 fast spin-echo (PD/T2-FSE) and three-dimensional gradient-echo (3D GRE) sequences, which provide good signal-to-noise and contrast-to-noise ratios. A thorough magnetic resonance (MR)-based assessment of cartilage repair tissue includes evaluations of defect filling, the surface and structure of repair tissue, the signal intensity of repair tissue and the subchondral bone status. Furthermore, in osteochondral autografts surface congruity, osseous incorporation and the donor site should be assessed. High spatial resolution is mandatory and can be achieved either by using a surface coil with a 1.5-T scanner or with a knee coil at 3 T; it is particularly important for assessing graft morphology and integration. Moreover, MR imaging facilitates assessment of complications including periosteal hypertrophy, delamination, adhesions, surface incongruence and reactive changes such as effusions and synovitis. Ongoing developments include isotropic 3D sequences, for improved morphological analysis, and in vivo biochemical imaging such as dGEMRIC, T2 mapping and diffusion-weighted imaging, which make functional analysis of cartilage possible.     

In vivo MRI of fresh stored osteochondral allograft transplantation with delayed gadolinium‐enhanced MRI of cartilage: Protocol considerations and recommendations

The protocol for delayed gadolinium‐enhanced MRI of cartilage (dGEMRIC) was adapted for the evaluation of transplanted osteochondral allograft cartilage. Eight patients with focal grade 4 cartilage defects of the femoral condyle were treated with single cylindrical osteochondral allografts. At 1 and 2 years, dGEMRIC image sequences were acquired and regions of interest (ROIs) were drawn in repair and native control cartilage. Mean T₁ values of region of interest were used to calculate established dGEMRIC metrics. The correlation was measured between the ΔR₁ and R₁‐Post metrics for repair and native cartilage. T₁ times were measured in deep and superficial zones of cartilage. A strong correlation was identified between full‐thickness, deep, and superficial ΔR₁ and R₁‐Post values for native cartilage and repair cartilage for all years (range: 0.893–1.0). The mean T₁ times and ΔR₁ rate between deep and superficial regions of articular cartilage were statistically different for all regions of the distal femora analyzed at 1 year and 2 years after osteochondral allograft transplantation (P < 0.05). The dGEMRIC pre‐Gadolinium scan is unnecessary when evaluating transplanted osteochondral allograft cartilage. The observation of stratified T₁ and ΔR₁ values indicates a need to re‐evaluate the methodology behind the placement of region of interest in dGEMRIC. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.     

Prospective evaluation of prolonged fresh osteochondral allograft transplantation of the femoral condyle: minimum 2-year follow-up

BACKGROUND: Focal articular cartilage lesions of the knee in young patients present a therapeutic challenge. Little information is available pertaining to the results after implantation of prolonged fresh grafts. HYPOTHESIS: Prolonged fresh osteochondral allografts present a viable option for treating large full-thickness articular cartilage lesions. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: This study presents the results of 25 consecutive patients who underwent prolonged fresh osteochondral allograft transplantation for defects in the femoral condyle. The average patient age was 35 years (range, 17-49 years). The average length of follow-up was 35 months (range, 24-67 months). Prospective data were collected using several subjective scoring systems, as well as objective and radiographic assessments. RESULTS: Statistically significant improvements (P < .05) were seen for the Lysholm (39 to 67), International Knee Documentation Committee scores (29 to 58), all 5 components of the Knee injury and Osteoarthritis Outcome Score (Pain, 43 to 73; Other Disease-Specific Symptoms, 46 to 64; Activities of Daily Living Function, 56 to 83; Sport and Recreation Function, 18 to 46; Knee-Related Quality of Life, 22 to 50), and the Short Form-12 physical component score (36 to 40). Overall, patients reported 84% (range, 25% to 100%) satisfaction with their results and believed that the knee functioned at 79% (range, 35% to 100%) of their unaffected knee. Radiographically, 22 of the grafts (88%) were incorporated into host bone. CONCLUSION: Fresh osteochondral allograft transplantation is an acceptable intermediate procedure for treatment of localized osteochondral defects of the femur. At 2-year follow-up, it is well incorporated and offered consistent improvements in pain and function. CLINICAL RELEVANCE: Prolonged fresh allograft transplantation is a safe and effective technique for addressing symptomatic osteoarticular lesions in the knees of young patients.     

Biomechanical and histological evaluation of osteochondral transplantation in a rabbit model

BACKGROUND: Biomechanical and histological properties of osteochondral transplantation have not been extensively examined. HYPOTHESIS: Osteochondral grafts have properties similar to native articular cartilage. STUDY DESIGN: Controlled laboratory study. METHODS: A 2.7 mm (diameter) x 4.0 mm (depth) osteochondral defect was created in 17 New Zealand white rabbit knees. An osteochondral graft, harvested from the contralateral knee, was transplanted into the defect. Eight rabbits were sacrificed each at 6 and 8 weeks. RESULTS: The 12-week grafts (1213.6 +/- 309.0 N/mm) had significantly higher stiffness than the 6-week grafts (483.1 +/- 229.1 N/mm; P <.001) and of normal cartilage (774.8 +/- 117.1 N/mm; P <.003). Stiffness of the 6-week grafts was significantly lower than normal cartilage (P <.036). At all time points, full-thickness defects had significantly lower stiffness than normal cartilage (P <.001). Histologically, transplanted grafts scored significantly higher than the full-thickness defects (P <.001). The defects showed inconsistent, fibrocartilage healing. The grafts demonstrated cartilage viability, yet with a persistent cleft between the graft and host. CONCLUSIONS: Osteochondral transplants undergo increased stiffness in the short term, with evidence of structurally intact grafts. Clinical Relevance: Osteochondral transplantation may be a viable treatment option; however, long-term investigation on graft function is necessary.     

Influence of basal support and early loading on bone cartilage healing in press-fitted osteochondral autografts

Purpose

The influence of basal graft support combined to early loading following an osteochondral autograft procedure is unclear. It was hypothesized that bottomed grafts may allow for early mobilization by preventing graft subsidence and leading to better healing.

Methods

Osteochondral autografts were press fitted in the femoral condyles of 24 sheep (one graft per animal). In the unbottomed group (n = 12), a gap of 2 mm was created between graft and recipient bone base. In the bottomed group (n = 12), the graft firmly rested on recipient bone. Animals were allowed immediate postoperative weightbearing. Healing times were 3 and 6 months per group (n = 6 per subgroup). After killing, histological and histomorphometric analyses were performed.

Results

Unbottomed grafts at 3 months showed significantly more graft subsidence (P = 0.024), significantly less mineralized bone (P = 0.028) and significantly worse cartilage and subchondral bone plate healing (P = 0.034) when compared to bottomed grafts. At 6 months, no differences were seen. Compared to the native situation, unbottomed grafts showed significantly more graft subsidence (P = 0.024), whereas bottomed grafts did not. Cystic lesions were seen in both groups. Osteoclasts were closely related to the degree of bone remodelling.

Conclusion

In the animal model, in the case of early loading, bottomed osteochondral autografts have less chance of graft subsidence. Evident subsidence negatively influences the histological healing process. In the osteochondral autograft procedure, full graft support should be aimed for. This may allow for early mobilization, diminish graft subsidence and improve long-term integration.     

MRI of osteochondral defects of the lateral femoral condyle: incidence and pattern of injury after transient lateral dislocation of the patella

OBJECTIVE: The typical bone bruise pattern involving the anterolateral femoral condyle and inferomedial patella after transient lateral dislocation of the patella is a well-described MRI finding. In our study, however, we sought to determine the incidence and location of lateral femoral condyle osteochondral injuries after transient lateral dislocation of the patella. CONCLUSION: Osteochondral defects of the lateral femoral condyle are a common sequela after transient lateral patellar dislocation. A significant number of osteochondral injuries involve the midlateral weight-bearing portion of the lateral femoral condyle and are more posterior than would be expected after transient dislocation of the patella.