Results of ultra-fresh osteochondral allograft transplantation for large cartilage defects in the knee joint.

OBJECTIVES: This study aims to investigate whether ultra-fresh osteochondral allograft (OCA) transplantation was a good therapeutic alternative for the treatment of otherwise challenging, massive osteochondral defects in the knee joint. PATIENTS AND METHODS: Between April 2011 and July 2022, a total of 16 ultra-fresh knee transplantations (9 males, 7 females; median age: 30.2 years; range, 14 to 62 years) having large osteochondral defects on femoral condyles were included. The operations were performed by two surgeons. The condition of the patients were evaluated based on regular follow-up physical examinations, imaging studies and by recording and evaluating clinical scores (modified Cincinnati scores, and 2000 International Knee Documentation Committee [IKDC] scores). RESULTS: The median follow-up was 65±48 (range, 6 months to 12 years). At two years after transplantation, there was a significant improvement in the modified Cincinnati scores (preoperative score of 35.75 increased to 83.75; p<0.001) and also to the IKDC scores (preoperative score of 28.7 increased to 76.3; p<0.001). One patient developed an early septic complication, and another three patients underwent reoperation after the OCA transplantations for non-septic reasons. CONCLUSION: Ultra-fresh OCA transplantation is a good therapeutic alternative for the treatment of otherwise challenging, massive osteochondral defects in the knee joint. Such a shortening of the transplantation time and its positive effect on the better long-term survival of transplanted chondrocytes has not yet been proven; however, the minimizing of transplantation time may create the conditions necessary for successful OCA transplantations many years after the implantation.

A comparison of SanatMetal Sanat Swing and Zimmer NexGen® total knee implants: 10-year postoperative follow-up results.

OBJECTIVES: In this study, we present our 10-year postoperative follow-up results of Sanat Swing® and NexGen® total knee implants. PATIENTS AND METHODS: A total of 189 patients (93 males, 96 females; mean age: 68 years; range, 48 to 86 years) who underwent total knee replacement between January 2008 and September 2010 were retrospectively analyzed. A total of 105 patients (Group A) were implanted a cemented Sanat Swing knee prosthesis and 84 patients (Group B) were implanted a cemented NexGen knee prosthesis. Operation time, range of motion (ROM), pain level, Knee Society Score (KSS), distance of painless walking, and the ability to climb stairs were evaluated between the groups. RESULTS: The mean follow-up was 10.8 (range, 9.8 to 12.3) years. No significant difference was observed in the survival of the prostheses, ROM, pain level, KSS, walking distance, and in the ability to climb stairs between the two groups at 10 years. With an experienced team, the operation time was about 4 to 5 min shorter in the Sanat Swing implantation group. In selected cases, Sanat Swing was superior to the NexGen system; however, there was no statistically significant difference. Complication rates were also low and comparable between both groups. CONCLUSION: Based on the 10 years of follow-up evaluation, Sanat Swing total knee replacement system seems to yield comparable clinical results with the NexGen. Experiences with the operative technique and comparative evaluation, the Sanat Swing system is a safe and reliable alternative for total knee replacement, providing a user-friendly operative technique and shorter operation time.

Isolated Femoral Shaft Fracture in Wakeboarding and Review of the Literature.

INTRODUCTION: Wakeboarding is an extreme sport that has shown increasing popularity in recent years, with an estimated 2.9 million participants in 2017. Due to this trend, injuries related to this sport are likely to become more common. Isolated femoral shaft are rare; however, they occur much more frequently in youth as a result of high velocity events, such as dashboard-related injuries. Few studies have addressed injuries related to wakeboarding, and of those that have, most have reported on muscle injuries, ligament ruptures, and sprains. Due to the dearth in literature, we want to present two cases of isolated noncontact femoral shaft fractures that resulted from wakeboarding. Case Presentation. Two 28-year-old, otherwise healthy, wakeboarders-patient A, male, and patient B, female-presented to our Department of Orthopaedics and Sports Medicine with isolated femoral shaft fractures. Both were admitted due to wakeboard-related noncontact injuries, where patient A fell while performing a sit-down start during cable wakeboarding and patient B after attempting a wake-jump. Both patients were being pulled by motorboats at roughly 40 km/h. After clinical examination and radiography, left spiral (AO classification: 32-A1.2) (patient A) and right-sided bending, wedge (AO classification 32-B2.2) (patient B) isolated femoral shaft fractures were diagnosed. No concomitant injuries were reported. For treatment, long reamed locked nails were applied, while the patients were under spinal anaesthesia. Physiotherapy was prescribed postoperatively. Patient A returned to wakeboarding 155 days after the surgery, and patient B returned after approximately half a year. CONCLUSION: This case series shows that even in noncontact sports such as wakeboarding, high-energy forces applied to the femur can cause isolated femoral shaft fractures. Despite multiple reports in various sports of stress fractures of the femur, there are few publications of direct trauma.

Synergistic Benefits of Group Search in Rats.

Locating unpredictable but essential resources is a task that all mobile animals have to perform in order to survive and reproduce. Research on search strategies has focused largely on independent individuals [1-3], but many organisms display collective behaviors, including during group search and foraging [4-6]. One classical experimental search task, informing studies of navigation, memory, and learning, is the location of a reward in a confined, complex maze setting [7, 8]. Rats (Rattus norvegicus) have been paradigmatic in psychological and biological studies [9, 10], but despite rats being highly social [11, 12], their group search behavior has not been investigated. Here, we explore the decision making of rats searching individually, or in groups, for a reward in a complex maze environment. Using automated video tracking, we find that rats exhibit-even when alone-a partially systematic search, leading to a continuous increase in their chance of finding the reward because of increased attraction to unexplored regions. When searching together, however, synergistic group advantages arise through integration of individual exploratory and social behavior. The superior search performances result from a strategy that represents a hierarchy of influential preferences in response to social and asocial cues. Furthermore, we present a computational model to compare the essential factors that influence how collective search operates and to validate that the collective search strategy increases the search efficiency of individuals in groups. This strategy can serve as direct inspiration for designing computational search algorithms and systems, such as autonomous robot groups, to explore areas inaccessible to humans. VIDEO ABSTRACT.

Adaptive leadership overcomes persistence-responsivity trade-off in flocking.

The living world is full of cohesive collectives that have evolved to move together with high efficiency. Schools of fish or flocks of birds maintain their global direction despite significant noise perturbing the individuals, yet they are capable of performing abrupt collective turns when relevant agitation alters the state of a few members. Ruling local fluctuations out of global movement leads to persistence and requires overdamped interaction dynamics, while propagating swift turns throughout the group leads to responsivity and requires underdamped interaction dynamics. In this paper we show a way to avoid this conflict by introducing a time-dependent leadership hierarchy that adapts locally to will: agents' intention of changing direction. Integrating our new concept of will-based inter-agent behaviour highly enhances the responsivity of standard collective motion models, thus enables breaking out of their former limit, the persistence-responsivity trade-off. We also show that the increased responsivity to environmental cues scales well with growing flock size. Our solution relies on active communication or advanced cognition for the perception of will. The incorporation of these into collective motion is a plausible hypothesis in higher order species, while it is a realizable feature for artificial robots, as demonstrated by our swarm of 52 drones.

Evaluation of clinical outcomes of cemented vs uncemented knee prostheses covered with titanium plasma spray and hydroxyapatite: A minimum two years follow-up.

OBJECTIVES: In this study, we introduce the SanatSwing cementless total knee prosthesis coated with a combination of titanium plasma spray and hydroxyapatite porous coating and compared its early results to the SanatSwing cemented knee prosthesis. PATIENTS AND METHODS: We compared 278 patients, who underwent total knee replacement between September 2012 and February 2017. A total of 142 patients (Group A; 78 male, 64 female, mean age 69±14) were implanted a cemented SanatSwing and 136 patients (Group B; 83 male, 53 female, mean age 59±10), a cementless SanatSwing knee prosthesis was implanted. Implant position and periprosthetic bone conditions were investigated over time on radiographs after a mean follow-up period of two years. Range of motion, pain level, distance of painless walk, and the ability to climb stairs were evaluated. RESULTS: Significant improvement was observed in both the cemented and uncemented groups when the preoperative scores were compared to the scores of their final visit, but we did not find any difference in measured scores between the cemented and uncemented group. Complication rates were low and almost similar in both groups without any significant difference. CONCLUSION: We used the combination of titanium plasma spray and the hydroxyapatite porous coating technique in cementless prostheses. Our results showed us that the novel SanatSwing cementless total knee prosthesis could be a great alternative to cemented total knee arthroplasty.

Intraarticular Injection of a Cross-Linked Sodium Hyaluronate Combined with Triamcinolone Hexacetonide (Cingal) to Provide Symptomatic Relief of Osteoarthritis of the Knee: A Randomized, Double-Blind, Placebo-Controlled Multicenter Clinical Trial.

OBJECTIVE: To evaluate the efficacy and safety of an intraarticular injection of Cingal (Anika Therapeutics, Inc., Bedford, MA) compared with Monovisc (Anika Therapeutics, Inc., Bedford, MA) or saline for the treatment of knee osteoarthritis. DESIGN: This multicenter, double-blind, saline-controlled clinical trial randomized subjects with knee osteoarthritis (Kellgren-Lawrence grades I-III) to a single injection of Cingal (4 mL, 88 mg hyaluronic acid [HA] plus 18 mg triamcinolone hexacetonide [TH]), Monovisc (4 mL, 88 mg HA), or saline (4 mL, 0.9%). The primary efficacy outcome was change in WOMAC (Western Ontario and McMaster Universities Arthritis Index) Pain Score through 12 weeks with Cingal versus saline. Secondary outcomes included Patient and Evaluator Global Assessments, OMERACT-OARSI Responder index, and WOMAC Total, Stiffness, and Physical Function scores through 26 weeks. RESULTS: A total of 368 patients were treated (Cingal, n = 149; Monovisc, n = 150; saline, n = 69). Cingal improvement from baseline was significantly greater than saline through 12 weeks ( P = 0.0099) and 26 weeks ( P = 0.0072). WOMAC Pain was reduced by 70% at 12 weeks and by 72% at 26 weeks with Cingal. Significant improvements were found in most secondary endpoints for pain and function at most time points through 26 weeks. At 1 and 3 weeks, Cingal was significantly better than Monovisc for most endpoints; Cingal and Monovisc were similar from 6 weeks through 26 weeks. A low incidence of related adverse events was reported. CONCLUSIONS: Cingal provides immediate and long-term relief of osteoarthritis-related pain, stiffness, and function, significant through 26 weeks compared to saline. Cingal had similar immediate advantages compared with HA alone, while showing benefit comparable to HA at 6 weeks and beyond.

Optimized flocking of autonomous drones in confined environments.

We address a fundamental issue of collective motion of aerial robots: how to ensure that large flocks of autonomous drones seamlessly navigate in confined spaces. The numerous existing flocking models are rarely tested on actual hardware because they typically neglect some crucial aspects of multirobot systems. Constrained motion and communication capabilities, delays, perturbations, or the presence of barriers should be modeled and treated explicitly because they have large effects on collective behavior during the cooperation of real agents. Handling these issues properly results in additional model complexity and a natural increase in the number of tunable parameters, which calls for appropriate optimization methods to be coupled tightly to model development. In this paper, we propose such a flocking model for real drones incorporating an evolutionary optimization framework with carefully chosen order parameters and fitness functions. We numerically demonstrated that the induced swarm behavior remained stable under realistic conditions for large flock sizes and notably for large velocities. We showed that coherent and realistic collective motion patterns persisted even around perturbing obstacles. Furthermore, we validated our model on real hardware, carrying out field experiments with a self-organized swarm of 30 drones. This is the largest of such aerial outdoor systems without central control reported to date exhibiting flocking with collective collision and object avoidance. The results confirmed the adequacy of our approach. Successfully controlling dozens of quadcopters will enable substantially more efficient task management in various contexts involving drones.

Evaluation of biomarkers following autologous osteochondral transplantation in the equine stifle joint - An experimental study.

The purpose of this study was to evaluate changes in biomarker and synovial parameters following autologous osteochondral transplantation (AOT) in the equine stifle joint, to test the hypothesis whether synovial parameters would show significant differences at selected time points following the surgery (at days 3, 14, 60 and 180) compared to baseline level (at day 0). Surgical intervention was performed in both stifles of nine horses (n = 18). The joints were randomly assigned to operated and sham-operated groups. Grafts 8.5 mm in diameter were harvested from the femoropatellar (FP) joint under arthroscopic control and the medial femorotibial (MFT) joints had AOT using mosaicplasty (MP) instrumentation, while the sham FP and sham MFT joints underwent arthroscopy and miniarthrotomy without transplantation, respectively. Synovial fluid (SF) parameters were evaluated at days 4, 14, 60 and 180. Data were analysed by two-way repeated- measures analysis of variance (ANOVA), and P < 0.05 was considered significant. During the first 10-14 days after surgery, lameness of degree 2-3/5 [American Association of Equine Practitioners (AAEP) scores] was present, which disappeared after 60 days. Joints with transplantation showed significant increases in synovial white blood cell count (WBC), total protein (TP), substance P, C1,2C and CS846 epitope concentration at day 3 compared to baseline and shamoperated joints (P < 0.05). These parameters returned to the baseline values by two months after surgery and remained within normal levels at 6 months postoperatively.

Coordinated Behaviour in Pigeon Flocks.

We analysed pigeon flock flights using GPS trajectory data to reveal the most important kinematic aspects of flocking behaviour. We quantitatively investigated the internal motion of the flock based on pairwise statistics and found the following general relationships in all datasets: i) the temporal order of decisions characterised by the delay between directional changes is strictly related to the spatial order characterised by the longitudinal relative position within the flock; ii) during circling motion, pigeons use a mixture of two idealised and fundamentally different turning strategies, namely, parallel-path and equal-radius type turning. While pigeons tend to maintain their relative position within the flock on average, as in the parallel-path approximation, those who turn later also get behind as in the equal-radius case. Equal-radius type turning also tends to be expressed more during smaller radius turns.

Flocking algorithm for autonomous flying robots.

Animal swarms displaying a variety of typical flocking patterns would not exist without the underlying safe, optimal and stable dynamics of the individuals. The emergence of these universal patterns can be efficiently reconstructed with agent-based models. If we want to reproduce these patterns with artificial systems, such as autonomous aerial robots, agent-based models can also be used in their control algorithms. However, finding the proper algorithms and thus understanding the essential characteristics of the emergent collective behaviour requires thorough and realistic modeling of the robot and also the environment. In this paper, we first present an abstract mathematical model of an autonomous flying robot. The model takes into account several realistic features, such as time delay and locality of communication, inaccuracy of the on-board sensors and inertial effects. We present two decentralized control algorithms. One is based on a simple self-propelled flocking model of animal collective motion, the other is a collective target tracking algorithm. Both algorithms contain a viscous friction-like term, which aligns the velocities of neighbouring agents parallel to each other. We show that this term can be essential for reducing the inherent instabilities of such a noisy and delayed realistic system. We discuss simulation results on the stability of the control algorithms, and perform real experiments to show the applicability of the algorithms on a group of autonomous quadcopters. In our case, bio-inspiration works in two ways. On the one hand, the whole idea of trying to build and control a swarm of robots comes from the observation that birds tend to flock to optimize their behaviour as a group. On the other hand, by using a realistic simulation framework and studying the group behaviour of autonomous robots we can learn about the major factors influencing the flight of bird flocks.

Mosaic arthroplasty of the medial femoral condyle in horses - An experimental study.

One Arabian and 5 Hungarian half-bred horses were used to study the macroscopic and microscopic survival of autologous osteochondral grafts in the weight-bearing surface of the medial femoral condyle (MFC). Grafts were harvested from the cranial surface of the medial femoral trochlea (MFT) under arthroscopic control. Three of them were transplanted into the weight-bearing surface of the contralateral MFC using an arthrotomy approach. Three months later this transplantation procedure was repeated on the opposite stifle joints in the same animals, but at that time transplantation was performed arthroscopically. Follow-up arthroscopy was carried out 12 months after the first operations, and biopsies were taken from both the recipient and the donor sites for histological examination. During follow-up arthroscopy, the transplanted areas looked congruent and smooth. Microscopically, the characteristics of hyaline cartilage were present in 5 out of the 10 biopsies examined; however, in the other half of biopsies glycosaminoglycan (GAG) loss and change in the architecture of the transplanted cartilage was observed. In a 16-year-old horse, all grafts broke during harvesting, and thus transplantation was not performed. No radiological signs of osteoarthritic changes were detected 9 to 12 months after the operations in the donor and recipient joints. Clinically, no lameness or effusion was present three months after the transplantations.

Identification of behaviour in freely moving dogs (Canis familiaris) using inertial sensors.

Monitoring and describing the physical movements and body postures of animals is one of the most fundamental tasks of ethology. The more precise the observations are the more sophisticated the interpretations can be about the biology of a certain individual or species. Animal-borne data loggers have recently contributed much to the collection of motion-data from individuals, however, the problem of translating these measurements to distinct behavioural categories to create an ethogram is not overcome yet. The objective of the present study was to develop a "behaviour tracker": a system composed of a multiple sensor data-logger device (with a tri-axial accelerometer and a tri-axial gyroscope) and a supervised learning algorithm as means of automated identification of the behaviour of freely moving dogs. We collected parallel sensor measurements and video recordings of each of our subjects (Belgian Malinois, N=12; Labrador Retrievers, N=12) that were guided through a predetermined series of standard activities. Seven behavioural categories (lay, sit, stand, walk, trot, gallop, canter) were pre-defined and each video recording was tagged accordingly. Evaluation of the measurements was performed by support vector machine (SVM) classification. During the analysis we used different combinations of independent measurements for training and validation (belonging to the same or different individuals or using different training data size) to determine the robustness of the application. We reached an overall accuracy of above 90% perfect identification of all the defined seven categories of behaviour when both training and validation data belonged to the same individual, and over 80% perfect recognition rate using a generalized training data set of multiple subjects. Our results indicate that the present method provides a good model for an easily applicable, fast, automatic behaviour classification system that can be trained with arbitrary motion patterns and potentially be applied to a wide range of species and situations.

Context-dependent hierarchies in pigeons.

Hierarchical organization is widespread in the societies of humans and other animals, both in social structure and in decision-making contexts. In the case of collective motion, the majority of case studies report that dominant individuals lead group movements, in agreement with the common conflation of the terms "dominance" and "leadership." From a theoretical perspective, if social relationships influence interactions during collective motion, then social structure could also affect leadership in large, swarm-like groups, such as fish shoals and bird flocks. Here we use computer-vision-based methods and miniature GPS tracking to study, respectively, social dominance and in-flight leader-follower relations in pigeons. In both types of behavior we find hierarchically structured networks of directed interactions. However, instead of being conflated, dominance and leadership hierarchies are completely independent of each other. Although dominance is an important aspect of variation among pigeons, correlated with aggression and access to food, our results imply that the stable leadership hierarchies in the air must be based on a different set of individual competences. In addition to confirming the existence of independent and context-specific hierarchies in pigeons, we succeed in setting out a robust, scalable method for the automated analysis of dominance relationships, and thus of social structure, applicable to many species. Our results, as well as our methods, will help to incorporate the broader context of animal social organization into the study of collective behavior.

A clinical feasibility study to evaluate the safety and efficacy of PEOT/PBT implants for human donor site filling during mosaicplasty.

UNLABELLED: Mosaicplasty has become a well-accepted treatment modality for articular cartilage lesions in the knee. Postoperative bleeding remains potentially concerning. This study evaluates the porous poly(ethylene oxide)terephthalate/poly(butylene terephthalate) (PEOT/PBT) implants used for donor site filling. Empty donor sites were the controls. After 9 months, MRI, macroscopical and histological analysis were carried out. Treated defects did not cause postoperative bleeding. No adverse events or inflammatory response was observed. PEOT/PBT implants were well integrated. Empty controls occasionally showed protrusion of repair tissue at the defect margins. Surface stiffness was minimally improved compared to controls. Existing polymer fragments indicated considerable biodegradation. Histological evaluation of the filled donor sites revealed congruent fibrocartilaginous surface repair with proteoglycan-rich domains and subchondral cancellous bone formation with interspersed fibrous tissue in all implanted sites. The PEOT/PBT implants successfully reduce donor site morbidity and postoperative bleeding after mosaicplasty. LEVEL OF EVIDENCE: II.

Osteochondral allograft transplantation from a living donor.

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

A computer-assisted microscopic analysis of bone tissue developed inside a polyactive polymer implanted into an equine articular surface.

One of the most promising applications for the restoration of small or moderately sized focal articular lesions is mosaicplasty (MP). Although recurrent hemarthrosis is a rare complication after MP, recently, various strategies have been designed to find an effective filling material to prevent postoperative bleeding from the donor site. The porous biodegradable polymer Polyactive (PA; a polyethylene glycol terephthalate - polybutylene terephthalate copolymer) represents a promising solution in this respect. A histological evaluation of the longterm PA-filled donor sites obtained from 10 experimental horses was performed. In this study, attention was primarily focused on the bone tissue developed in the plug. A computer-assisted image analysis and quantitative polarized light microscopic measurements of decalcified, longitudinally sectioned, dimethylmethylene blue (DMMB)- and picrosirius red (PS) stained sections revealed that the coverage area of the bone trabecules in the PA-filled donor tunnels was substantially (25%) enlarged compared to the neighboring cancellous bone. For this quantification, identical ROIs (regions of interest) were used and compared. The birefringence retardation values were also measured with a polarized light microscope using monochromatic light. Identical retardation values could be recorded from the bone trabeculae developed in the PA and in the neighboring bone, which indicates that the collagen orientation pattern does not differ significantly among these bone trabecules. Based on our new data, we speculate that PA promotes bone formation, and some of the currently identified degradation products of PA may enhance osteo-conduction and osteoinduction inside the donor canal.

Osteochondral Autograft and Mosaicplasty in the Football (Soccer) Athlete.

OBJECTIVE: To evaluate the clinical outcomes of mosaicplasty in the treatment of focal chondral and osteochondral defects of joints among elite football players. METHODS: Case series; Level of evidence, 4. The results of mosaicplasty were prospectively evaluated with 1-year intervals with patient-reported outcome measures, radiographs, and sports participation. RESULTS: Sixty-one patients who received mosaicplasty in the knee joint were followed from 2 to 17 years (average, 9.6 years). The International Cartilage Repair Society (ICRS) score showed 89% good and excellent results. Sixty-seven percent of all players returned to the same level of sport, with 89% of the elite players and 62% of the competitive players. The average time to return to competitions was 4.5 months (range, 3.5-6.1 months). Players who had better clinical outcomes were significantly younger and had smaller lesions. The results of the medial and lateral condyles were significantly better than those in the patella or trochlea. Concomitant adjuvant procedures improved clinical outcomes. Despite a higher rate of preoperative osteoarthritic changes, clinical outcomes demonstrated a success rate similar to that of less athletic patients. CONCLUSION: Autologous osteochondral mosaicplasty in competitive football players is a good alternative procedure to repair cartilage damage.

Autologous osteochondral grafting--technique and long-term results.

BACKGROUND: Efficacious treatment of chondral and osteochondral defects of weightbearing articular surfaces is a daily challenge in musculoskeletal care. Autogenous osteochondral transplantation represents a possible solution for creating hyaline or hyaline-like repair in the affected area that has a noninflammatory pathoorigin. This paper discusses the experimental background and over 15 years of clinical experience with autologous osteochondral mosaicplasty. METHODS: Several series of animal studies and subsequent clinical practice of over 1,000 mosaicplasty patients were assessed to confirm the survival of transplanted hyaline cartilage and fibrocartilage filling of donor sites located on relatively less weightbearing surfaces, as well as donor-site disturbances and morbidity. Histological evaluations of dog and horse implantations as well as several series of clinical evaluations in the human material are summarized in this paper. Clinical scores, different types of imaging techniques, second-look arthroscopies, histological examination of biopsy samples, and cartilage stiffness measurements were used to evaluate the clinical outcomes and quality of the transplanted cartilage. RESULTS: Analysis of clinical scores has shown good to excellent results in 92% of patients with femoral condylar implantations, 87% of tibial resurfacements, 74% of patellar and/or trochlear mosaicplasties and 93% of talar procedures. Longterm donor-site complaints measured by the Bandi score were minor and present only in 3% of patients. 81 out of the 98 control arthroscopies represented congruent and good gliding surfaces and histologically proven survival of the transplanted hyaline cartilage as well as fibrocartilage covering of the donor sites. Complications in the entire patient group were four deep infections and four deep venous thromboses. In nearly 8% of the cases excessive intraarticular bleeding was observed in the early postoperative period, as a minor complication of the procedure. Multicentric, comparative, prospective evaluation of 413 arthroscopic resurfacing procedures (mosaicplasty, Pridie drilling, abrasion arthroplasty and microfracture cases in homogenised subgroups) demonstrated that mosaicplasty resulted in favourable clinical outcome in the long-term follow-up compared to other three techniques. Durability of the early results was confirmed in long-term evaluations both of the femoral condylar implantations and talar mosaicplasties. CONCLUSIONS: According to our encouraging results in this increasingly large series, supported by similar findings from other centres, it seems that autologous osteochondral mosaicplasty may be an alternative for small and medium-sized focal chondral and osteochondral defects of weightbearing surfaces of the knee and other weightbearing synovial joints.

Autologous osteochondral mosaicplasty. Surgical technique.

BACKGROUND: The successful treatment of chondral and osteochondral defects of the weight-bearing surfaces is a challenge for orthopaedic surgeons. Autologous osteochondral transplantation is one method that can be used to create hyaline or hyaline-like repair in the defect area. This paper describes the results after ten years of clinical experience with autologous osteochondral mosaicplasty. METHODS: Clinical scores, imaging techniques, arthroscopy, histological examination of biopsy samples, and cartilage stiffness measurements were used to evaluate the clinical outcomes and quality of the transplanted cartilage in 831 patients undergoing mosaicplasty. RESULTS: According to these investigations, good-to-excellent results were achieved in 92% of the patients treated with femoral condylar implantations, 87% of those treated with tibial resurfacing, 79% of those treated with patellar and/or trochlear mosaicplasties, and 94% of those treated with talar procedures. Long-term donor-site disturbances, assessed with use of the Bandi score, showed that patients had 3% morbidity after mosaicplasty. Sixty-nine of eighty-three patients who were followed arthroscopically showed congruent gliding surfaces, histological evidence of the survival of the transplanted hyaline cartilage, and fibrocartilage filling of the donor sites. Complications of the surgery included four deep infections and thirty-six painful postoperative hemarthroses. CONCLUSIONS: On the basis of these promising results and those of other similar studies, autologous osteochondral mosaicplasty appears to be an alternative for the treatment of small and medium-sized focal chondral and osteochondral defects of the weight-bearing surfaces of the knee and other weight-bearing synovial joints.