Impact insertion of osteochondral grafts: Interference fit and central graft reduction affect biomechanics and cartilage damage

An osteochondral graft (OCG) is an effective treatment for articular cartilage and osteochondral defects. Impact of an OCG during insertion into the osteochondral recipient site (OCR) can cause chondrocyte death and matrix damage. The aim of the present study was to analyze the effects of graft‐host interference fit and a modified OCG geometry on OCG insertion biomechanics and cartilage damage. The effects of interference fit (radius of OCG ‐ radius of OCR), loose (0.00 mm), moderate (0.05 mm), tight (0.10 mm), and of a tight fit with OCG geometry modification (central region of decreased radius), were analyzed for OCG cylinders and OCR blocks from adult bovine knee joints with an instrumented drop tower apparatus. An increasingly tight (OCG ‐ OCR) interference fit led to increased taps for insertion, peak axial force, graft cartilage axial compression, cumulative and total energy delivery to cartilage, lower time of peak axial force, lesser graft advancement during each tap, higher total crack length in the cartilage surface, and lower chondrocyte viability. The modified OCG, with reduction of diameter in the central area, altered the biomechanical insertion variables and biological consequences to be similar to those of the moderate interference fit scenario. Micro‐computed tomography confirmed structural interference between the OCR bone and both the proximal and distal bone segments of the OCGs, with the central regions being slightly separated for the modified OCGs. These results clarify OCG insertion biomechanics and mechanobiology, and introduce a simple modification of OCGs that facilitates insertion with reduced energy while maintaining a structural interference fit. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:377–386, 2018.     

Enhancing integration of articular cartilage grafts via photochemical bonding

The integration of osteochondral grafts to native articular cartilage is critical as the lack of graft integration may lead to continued tissue degradation, poor load transfer and inadequate nutrient transport. Photochemical bonding promotes graft integration by activating a photosensitizer at the interface via a light source and avoids negative effects associated with other bonding techniques. We hypothesized that the bond strength depends on photosensitizer type and concentration in addition to light exposure. Photochemical bonding was evaluated using methylene blue (MB), a cationic phenothiazine photosensitizer, and two phthalocyanine photosensitizers, Al(III) phthalocyanine chloride tetrasulfonic acid (CASPc) and aluminum phthalocyanine chloride (AlPc). Exposure was altered by varying irradiation time for a fixed irradiance or by varying irradiance with a fixed irradiation time. MB was ineffective at producing bonding at the range of concentrations tested while CASPc produced a peak twofold bond strength increase over controls. AlPc produced substantial bonding at all concentrations with a peak 3.9‐fold bond strength increase over controls. Parametric tests revealed that bond strength depended primarily on the total energy delivered to the bonding site rather than the rate of light delivery or light irradiance. Bond strength persisted for 1 week of in‐vitro culture, which warrants further exploration for clinical applications. These studies indicate that photochemical bonding is a viable strategy for enhancing articular cartilage graft integration. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2406–2415, 2018.

     

Fresh Osteochondral Allograft Resurfacing of the Ankle

Many basic scientific and clinical studies support the utility of small fragment allografting in addressing an extensive spectrum of osteoarticular pathology, with its use in the tibiotalar joint still an evolving application. The operative procedure in the ankle is technically straightforward but demands precision to achieve reproducible results and to minimize early graft failures related to surgical technique. Fresh osteochondral allografting of the tibiotalar joint is best understood as a management strategy in the patient that presents with a symptomatic OLT, or advanced ankle arthropathy at an age or activity level not optimally suited for total joint replacement or arthrodesis. The treatment goal of joint-sparing biologic reconstruction is to relieve pain and maintain function to delay the need for ankle fusion or total replacement indefinitely, while at the same time not restricting future treatment options. The emergence of fresh osteochondral allografting for the ankle has demonstrated encouraging results, but its remaining shortcomings are also testament to the lack of viable treatment options in this challenging patient population.     

Fresh Osteochondral Allograft Transplantation for Treatment of Large Cartilage Defects of the Femoral Head: A Minimum Two-Year Follow-Up Study of Twenty-Two Patients

Background

Controversy remains over the surgical management of large osteochondral lesions of the femoral head in young, active patients. The purpose of this study is to assess midterm clinical and radiographic outcomes after fresh osteochondral allograft transplantation (OAT) for large femoral head lesions at minimum 2-year follow-up.

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

PURPOSE: For the purpose of achieving anatomical reduction as precisely as possible, we performed osteochondral grafting from the costo-osteochondral junction in 16 patients (17 joints) with posttraumatic articular cartilage injury or avascular necrosis in finger joints. The purpose of this study was to review our series of costal osteochondral grafts in order to determine the practicality, effectiveness, and functionality of this grafting technique in a clinical setting. METHODS: Patients were followed for at least 18 months postoperatively (18-57 months; average, 28 months). The injured joints included 3 metacarpophalangeal, 9 proximal interphalangeal, 3 distal interphalangeal, and 2 thumb interphalangeal joints. The defect accounted for 50% to 100% of the articular surface (average, 63%). RESULTS: The average time until bone union of the graft was 58 days. The mean arc of motion was 13 degrees before surgery versus 58 degrees after surgery, with a mean increase of 45 degrees . In 7 patients (8 joints), an extremely small portion (approximately 1 x 1 mm in size and thinner than 0.1 mm) of the implanted cartilage was obtained via biopsy using a scalpel with the consent of the patient at the time of screw removal and was used to prepare histologic specimens, which revealed scattered chondrocytes within the matrix without differences from normal hyaline cartilage in any. The chondrocytes in the grafts appeared viable, and the reconstruction of the joint surface could be confirmed histologically. CONCLUSIONS: Osteochondral grafting from the costo-osteochondral junction achieves excellent reconstruction of the injured joint without affecting other joints. This technique is particularly beneficial in cases where it is difficult to obtain allograft donors, as is often the case in Japan. Despite these encouraging findings in this small series, we believe that it is necessary to conduct further studies of this method over a longer period.     

人异体骨软骨移植物保存方法研究

[目的]探讨六种保存方法对人关节软骨组织结构和细胞活性的影响,寻求一种保存效果较好的方法,为临床提供一种有活性的异体骨软骨移植物.[方法]自捐献新鲜尸体膝关节利用专用手术器械获取4.5 mm ×4.5 mm大小的人骨软骨块,分别采用梯度降温法、Co60射线照射+梯度降温法、玻璃化法、连续降温法、直接液氮法和酒精浸泡法对软骨块进行保存处理,分别于保存第8、15、30、60d时,采用蕃红-O组织染色、扫描电镜、软骨细胞胎盼蓝染色、MTT法等,观察并比较以上6种方法保存后关节软骨细胞存活率及其代谢功能变化.[结果]除了酒精保存方法外,其余保存方法随着时间延长软骨组织的细胞成活率和细胞代谢活性逐渐降低;保存60d时,采用玻璃化法保存软骨组织的细胞存活率为62.47％,软骨基质成分丢失较少,胶原纤维断裂不明显;采用慢速梯度降温法保存软骨组织的细胞存活率为59.75％,软骨基质成分丢失较多,胶原纤维断裂明显;其他保存方法软骨细胞存活率不足40％,软骨基质成分大量丢失,胶原纤维杂乱.[结论]六种保存方法中,玻璃化保存法能够较好的保存关节软骨,活性最好,其次是梯度降温保存法,两者均具有一定临床价值.Co60射线照射对软骨细胞有一定的损伤作用;酒精浸泡不能保存软骨细胞活性.     

Prevalence of articular cartilage degeneration in the ankle and knee joints of human organ donors

The prevalence of osteoarthritis (OA) is higher in some joints than in others. Fibrillation and full-thickness cartilage defects in the knee have been considered to be evidence of developing OA (pre-OA). While similar changes have been reported in the ankle (talocrural joint), the frequency of these changes is much higher than expected if the degeneration represents pre-OA. These observations suggest that in the ankle degenerative changes do not proceed to OA. The current study was to determine the prevalence of articular cartilage degeneration in ankles in a population of 470 bone donors with no history of joint disease. Knees from 50 donors were also available. Our data suggest that degeneration in the ankle cartilage does not appear to be a normal part of aging, was more frequent in men than women, increased with age, and occurred most often in both limbs with the same severity. In those donors with degeneration in the ankle, the knee also showed degenerative changes with an equal or higher grade. These data suggest that factors (such as altered mechanics) responsible for degeneration in one limb also cause changes in the contralateral limb and that factors affecting the ankle joints also appear to influence the knee joints. Received for publication on Dec. 2, 1998; accepted on April 22, 1999     

Injury and repair of articular cartilage: Related scientific issues

Articular cartilage (AC) is the soft tissue lining the ends of bones in diarthrodial joints. It is responsible for providinglubrication and compressive stiffness to the joint during articulation while responding viscoelastically to mechanical loading. Injury of the tissue caused by trauma or disease can be devastating to joint function as these mechanisms fail. Because of this, it is essential to review the basic science underlying the mechanical roles AC plays while healthy, the biomechanical and biological perspectives of the injury and repair processes, and the current repair techniques available for injured AC. This is done in an effort to further our understanding of the healing capacity of AC and facilitate new efforts into AC repair.     

Arthroscopic Treatment of Osteochondral Lesions of the Talus Using Juvenile Articular Cartilage Allograft and Autologous Bone Marrow Aspirate Concentration

Juvenile allogenic chondrocyte implantation (JACI; DeNovo NT Natural Tissue Graft^®; Zimmer, Warsaw, IN) with autologous bone marrow aspirate concentrate (BMAC) is a relatively new all-arthroscopic procedure for treating critical-size osteochondral lesions (OCLs) of the talus. Few studies have investigated the clinical and radiographic outcomes of this procedure. We collected the clinical and radiographic outcomes of patients who had undergone JACI-BMAC for talar OCLs to assess treatment efficacy and cartilage repair tissue quality using magnetic resonance imaging (MRI). Forty-six patients with critical-size OCLs (≥6?mm widest diameter) received JACI-BMAC from 2012 to 2014. We performed a retrospective medical record review and assessed the functional outcomes pre- and postoperatively using the Foot and Ankle Outcome Score (FAOS) and Short-Form 12-item general health questionnaire. MRI was performed preoperatively and at 12 and 24 months postoperatively. Cartilage morphology was evaluated on postoperative MRI scans using the magnetic resonance observation of cartilage tissue (MOCART) score. The pre- to postoperative changes and relationships between outcomes and lesion size, bone grafting, lesion location, instability, hypertrophy, and MOCART scores were analyzed. Overall, the mean questionnaire scores improved significantly, with almost every FAOS subscale showing significant improvement postoperatively. Concurrent instability resulted in more changes that were statistically significant. The use of bone grafting and the presence of hypertrophy did not result in statistically significant changes in the outcomes. Factors associated with outcomes were lesion size and hypertrophy. Increasing lesion size was associated with decreased FAOS quality of life subscale and hypertrophy correlating with changes in the pain subscale. Of the 46 patients, 22 had undergone postoperative MRI scans that were scored. The average MOCART score was 46.8. Most patients demonstrated a persistent bone marrow edema pattern and hypertrophy of the reparative cartilage. Juvenile articular cartilage implantation of the DeNovo NT allograft and BMAC resulted in improved functional outcome scores; however, the reparative tissue still exhibited fibrocartilage composition radiographically. Further studies are needed to investigate the long-term outcomes and determine the superiority of the arthroscopic DeNovo procedure compared with microfracture and other cartilage resurfacing procedures.     

The Biochemical Response of Rabbit Articular Cartilage Matrix to an Induced Talcum Synovitis

Transient synovitis is a commonly occurring affliction in the hips of young children. The results of an experimental model of this condition produced in the immature rabbit's hip showed that there is a significant response in the articular cartilage. Thus, the cartilage rapidly thickens, becomes more hydrated and reveals an initial decrease in glycosaminoglycan concentration. Three weeks following the induction of synovitis, the concentrations of water, glycosaminoglycan and collagen are similar to the control side. The increase of articular cartilage mass is due, not only to an increased hydration, but also to increased matrix production under the stimulus of the synovitis. A similar response by the immature cartilage might be expected following a transient synovitis in a child's hip.     

Chondral and osteochondral injuries: mechanisms of injury and repair responses

Acute and repetitive impact and torsional loading of joints can damage the articular surface, causing pain, joint dysfunction and effusions, and in some instances, progressive joint degeneration. These injuries often remain undetected and their incidence, pathogenesis, natural history, and optimal treatment remain poorly understood. Advances in arthroscopy and joint imaging have improved the ability of physicians to identify articular surface injuries, and reports of new methods of promoting restoration of articular surfaces have increased interest in their treatment. Three classes of chondral and osteochondral injuries can be identified based on the type of tissue damage and the repair response: (1) damage to the joint surface that does not cause visible mechanical disruption of the articular surface but does cause chondral damage and may cause subchondral bone injury, (2) mechanical disruption of the articular surface limited to articular cartilage, and (3) mechanical disruption of articular cartilage and subchondral bone. In most instances joints can repair damage that does not disrupt the articular surface if they are protected from further injury. Mechanical disruption of articular cartilage stimulates chondrocyte synthetic activity, but it rarely results in repair of the injury. Disruption of subchondral bone stimulates chondral and bony repair, but it rarely restores an articular surface that duplicates the biological and mechanical properties of normal articular cartilage. The extent and effectiveness of the chondral and osseous repair responses vary with age: in general younger individuals, especially skeletally immature people, have more effective repair of articular surface injuries. To be of value to patients a treatment of an articular surface injury must produce better short- and long-term results than the natural repair response. Thus, before selecting a treatment for a patient with a chondral or osteochondral injury the surgeon should define the type of injury and understand its likely natural history.     

在体阻断软骨下营养对关节软骨影响的实验研究

背景：关节软骨无血管分布,其营养来自关节液和软骨下骨,哪条营养通路对关节软骨更为重要是学者们争论的焦点。目的：研究软骨下营养对关节软骨的影响,并探讨软骨下营养与骨关节炎的关系。方法：45只5个月龄雄性新西兰大白兔,建立股骨滑车骨软骨缺损的动物模型,并随机分为3组：自体骨软骨块移植组（Control组,n=15）;假手术组（Sham组,n=15）,用环钻在股骨滑车钻取骨软骨块,将其置入管状PVC内,原位回植;阻断软骨下营养组（DNBM组,n=15）,取出骨软骨后,将其置入帽状PVC内,原位回植。术后4周、8周、12周,每组5只（10膝）,取出膝关节进行大体评分、组织学评分、软骨厚度测量、凋亡染色（TUNEL染色）。结果：与Control组相比,大体评分结果提示,DNBM组软骨无明显退变;组织学评分结果提示,术后12周时DNBM组软骨明显退变（P〈0.005）;软骨厚度测量结果提示,术后8周、12周时DNBM组软骨厚度明显变小（P=0.00）;TUNEL染色结果提示,术后8周、12周时DNBM组关节软骨细胞凋亡明显增加（P〈0.01）。结论：软骨下营养是软骨的重要营养来源,失去软骨下营养,软骨会逐渐发生退变。     

Electrostatic interactions enable rapid penetration,enhanced uptake and retention of intra‐articular injected avidin in rat knee joints

Intra‐articular (i.a.) drug delivery for local treatment of osteoarthritis remains inadequate due to rapid clearance by the vasculature or lymphatics. Local therapy targeting articular cartilage is further complicated by its dense meshwork of collagen and negatively charged proteoglycans, which can prevent even nano‐sized solutes from entering. In a previous in vitro study, we showed that Avidin, due to its size (7 nm diameter) and high positive charge (pI 10.5), penetrated the full thickness of bovine cartilage and was retained for 15 days. With the goal of using Avidin as a nano‐carrier for cartilage drug delivery, we investigated its transport properties within rat knee joints. Avidin penetrated the full thickness of articular cartilage within 6 h, with a half‐life of 29 h, and stayed inside the joint for 7 days after i.a. injection. The highest concentration of Avidin was found in cartilage, the least in patellar tendon and none in the femoral bone; in contrast, negligible Neutravidin (neutral counterpart of Avidin) was present in cartilage after 24 h. A positive correlation between tissue sGAG content and Avidin uptake (R² = 0.83) confirmed the effects of electrostatic interactions. Avidin doses up to at least 1 µM did not affect bovine cartilage explant cell viability, matrix catabolism or biosynthesis. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:1044–1051, 2014.     

Current applications of three-dimensional printing in urology

Three-dimensional (3D) printing or additive manufacturing is a new technology that has seen rapid development in recent years with decreasing costs. 3D printing allows the creation of customised, finely detailed constructs. Technological improvements, increased printer availability, decreasing costs, improved cell culture techniques, and biomaterials have enabled complex, novel and individualised medical treatments to be developed. Although the long-term goal of printing biocompatible organs has not yet been achieved, major advances have been made utilising 3D printing in biomedical engineering. In this literature review, we discuss the role of 3D printing in relation to urological surgery. We highlight the common printing methods employed and show examples of clinical urological uses. Currently, 3D printing can be used in urology for education of trainees and patients, surgical planning, creation of urological equipment, and bioprinting. In this review, we summarise the current applications of 3D-printing technology in these areas of urology.     

The Lateral Compartment in Knees With Isolated Medial and Patellofemoral Osteoarthritis : A Histologic Analysis of Articular Cartilage

The purpose of this study was to examine, at a histologic level, the articular cartilage of the radiographically normal lateral compartment in knees with isolated medial and possibly patellofemoral osteoarthritis. Twenty patients with radiographic evidence of medial compartment osteoarthritis and a radiographically osteoarthritis-free lateral compartment underwent a tricompartmental total knee arthroplasty. The resected lateral femoral condyle and lateral tibial plateau were evaluated by a fellowship-trained musculoskeletal pathologist for the presence, or lack thereof, of osteoarthritis at a microscopic level. Both the tibia and femur showed evidence of mild osteoarthritis at a microscopic level. This study shows that in patients with radiographic evidence of medial osteoarthritis and a radiographically normal lateral compartment, there is mild osteoarthritis in the lateral compartment.     

Reconstruction of Articular Cartilage Defects with Free Periosteal Grafts: An Experimental Study

The chondrogenic potential of free autogenous periosteal grafts was studied histologically in 6-month-old rabbits. The grafts were taken from the tibia and transplanted to 7 × 14 mm large artificial defects of the femoral articular cartilage. The results revealed that the defects were repaired and filled after 4 weeks with a hyaline-like cartilage which was histologically similar to the cartilage adjacent to the transplant. The tissue maintained this morphology after 1 year of observation. In control animals where no periosteum was transplanted to the defect, no real cartilage was found. The tissue which partially filled the defect was a variable mixture of fibrous tissue and fibrocartilage.     

Cartilage repair with osteochondral autografts in sheep: Effect of biophysical stimulation with pulsed electromagnetic fields

The effect of pulsed electromagnetic fields (PEMFs) on the integration of osteochondral autografts was evaluated in sheep. After osteochondral grafts were performed, the animals were treated with PEMFs for 6 h/day or sham‐treated. Six animals were sacrificed at 1 month. Fourteen animals were treated for 2 months and sacrificed at 6 months. At 1 month, the osteogenic activity at the transplant–host subchondral bone interface was increased in PEMF‐treated animals compared to controls. Articular cartilage was healthy in controls and stimulated animals. At 6 months, complete resorption was observed in four control grafts only. Cyst‐like resorption areas were more frequent within the graft of sham‐treated animals versus PEMF‐treated. The average volume of the cysts was not significantly different between the two groups; nevertheless, analysis of the variance of the volumes demonstrated a significant difference. The histological score showed no significant differences between controls and stimulated animals, but the percentage of surface covered by fibrous tissue was higher in the control group than in the stimulated one. Interleukin‐1 and tumor necrosis factor‐α concentration in the synovial fluid was significantly lower, and transforming growth factor‐β1 was significantly higher, in PEMF‐treated animals compared to controls. One month after osteochondral graft implantation, we observed larger bone formation in PEMF‐treated grafts which favors early graft stabilization. In the long term, PEMF exposure limited the bone resorption in subchondral bone; furthermore, the cytokine profile in the synovial fluid was indicative of a more favorable articular environment for the graft. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:631–642, 2008