Return to Play and Pattern of Injury After ACL Rupture in a Consecutive Series of Elite UEFA Soccer Players.

Background: Anterior cruciate ligament rupture represents a career-threatening injury for professional soccer players. Purpose: To analyze the pattern of injury, return to play (RTP), and performance of a consecutive series of elite professional soccer players after anterior cruciate ligament reconstruction (ACLR). Study Design: Case series; Level of evidence, 4. Methods: We evaluated the medical records of 40 consecutive elite soccer players who underwent ACLR by a single surgeon between September 2018 and May 2022. Patient age, height, weight, body mass index, position, injury history, affected side, RTP time, minutes played per season (MPS), and MPS as a percentage of playable minutes before and after ACLR were retrieved from medical records and from publicly available media-based platforms. Results: Included were 27 male patients (mean ± SD age at surgery, 23.2 ± 4.3 years; range, 18-34 years). The injury occurred during matches in 24 players (88.9%), with a noncontact mechanism in 22 (91.7%). Meniscal pathology was found in 21 patients (77.8%). Lateral meniscectomy and meniscal repair were performed in 2 (7.4%) and 14 (51.9%) patients, respectively, and medial meniscectomy and meniscal repair were performed in 3 (11.1%) and 13 (48.1%) patients, respectively. A total of 17 players (63.0%) underwent ACLR with bone-patellar tendon-bone autograft and 10 (37.0%) with soft tissue quadriceps tendon. Lateral extra-articular tenodesis was added in 5 patients (18.5%). The overall RTP rate was 92.6% (25 of 27). Two athletes moved to a lower league after surgery. The mean MPS% during the last preinjury season was 56.69% ± 21.71%; this decreased significantly to 29.18% ± 20.6% (P < .001) in the first postoperative season and then increased to 57.76% ± 22.89% and 55.89% ± 25.8% in the second and third postoperative seasons. Two (7.4%) reruptures and 2 (7.4%) failed meniscal repairs were reported. Conclusion: ACLR in elite UEFA soccer players was associated with a 92.6% rate of RTP and 7.4% rate of reinjury within 6 months after primary surgery. Moreover, 7.4% of soccer players moved to a lower league during the first season after surgery. Age, graft selection, concomitant treatments, and lateral extra-articular tenodesis were not significantly associated with prolonged RTP.

Video analysis of Achilles tendon ruptures in professional male football (soccer) reveals underlying injury patterns and provides strategies for injury prevention.

PURPOSE: In professional football (soccer), Achilles tendon ruptures are severe injuries. Video analysis promotes a better understanding of the underlying situational and biomechanical patterns, and provides a roadmap for future research to improve the management and prevention of Achilles tendon ruptures. The purpose of this study was to identify injury patterns contributing to acute Achilles tendon ruptures in professional male football players. METHODS: Professional male football players with an acute Achilles tendon rupture were identified using an online database. For every in-competition injury, the corresponding football match was detected. Video footage of the injury was accessed using Wyscout.com or publicly available video databases. Situational patterns and injury biomechanics of the injury frame were independently analysed by two reviewers using a standardised checklist and a motion analysis software. Finally, consensus was reached to describe the main injury patterns of Achilles tendon ruptures in professional male football players. RESULTS: The search identified video footage of 80 Achilles tendon ruptures in 78 players. Most injuries (94%) occurred through indirect or non-contact mechanisms. The kinematic analysis revealed characteristic joint positions at the time of injury consisting of hip extension, knee extension, ankle dorsiflexion, foot abduction, and foot pronation in most cases. The underlying direction of movement was from flexion to extension (knee) and from plantarflexion to dorsiflexion (ankle). Player actions identified as main injury patterns were stepping back (26%), landing (20%), running/sprinting (18%), jumping (13%), and starting (10%). CONCLUSION: Most Achilles tendon ruptures in professional male football players are closed-chain indirect or non-contact injuries. Sudden loading to the plantarflexor musculotendinous unit remains to be the main component for most cases. By achieving a better understanding of underlying injury mechanisms, this study provides new strategies for the prevention of Achilles tendon ruptures. LEVEL OF EVIDENCE: Level IV.

Risk factors for hamstring muscle injury in male elite football: medical expert experience and conclusions from 15 European Champions League clubs.

Objectives: To describe the perceived importance of suggested hamstring injury risk factors according to chief medical officers (CMOs) of European male professional football clubs. A secondary objective was to compare if these perceptions differed between teams with a lower-than-average hamstring injury burden and teams with a higher than average hamstring injury burden. Methods: First, CMOs of 15 European professional male football clubs were asked to suggest risk factors for hamstring injury in their club. The perceived importance of the suggested risk factors was then rated by all participants on a 5-graded Likert scale. Participating teams were divided in two groups depending on their hamstring injury burden during the 2019/2020 and 2020/2021 seasons. The LOW group consisted of seven teams that had a lower than average hamstring injury burden. The HIGH group consisted of eight teams that had a higher-than-average hamstring injury burden. Results: Twenty-one risk factors were suggested. The majority were extrinsic in nature, associated with coaching staff, team or club rather than players themselves. 'Lack of communication between medical staff and coaching staff' had the highest average importance (weighted average=3.7) followed by 'Lack of regular exposure to high-speed football during training sessions' (weighted average=3.6). The HIGH group perceived the player factors fatigue and wellness as more important than the LOW group. Conclusion: According to CMOs recruited in this study, most risk factors for hamstring injuries are extrinsic and associated with the club and coaching staff, and not the players themselves.

[Musculoskeletal laboratory diagnostics in competitive sport]. / Muskuloskelettale Labordiagnostik im Leistungssport.

BACKGROUND: Laboratory diagnostics represent a valuable tool for the optimization and assessment of the performance and regeneration ability in professional athletes. Blood parameters play an important role in the prevention, diagnosis and rehabilitation of injuries and physical overload. OBJECTIVES: The aim of this article is to present an overview of musculoskeletal laboratory parameters and to provide relevant information for the medical care of competitive athletes. METHODS: Literature search and narrative review. RESULTS: The laboratory assessment of bone metabolism includes vitamin D, calcium and bone turnover and aims to provide a preventive benefit with respect to skeletal complications (e.g., to minimize the risk of bone stress injuries). In addition, muscular serum markers, such as lactate dehydrogenase (LDH), creatine kinase (CK), myoglobin and aspartate aminotransferase (AST) can be used to monitor metabolic adaptation to physical exercise and to obtain information about the muscular workload and potential damage. The energy availability can be estimated and optimized by appropriate balancing and laboratory determination of macro- and micronutrients. CONCLUSIONS: Laboratory diagnostics have a clinical relevance across different sport disciplines. They are intended to support athletes and medical staff on their way to the highest possible performance and help to ensure the optimal prevention of bone and muscle injuries. Parameters with deficiency results (e.g., vitamin D) should be adequately compensated. A periodization of the laboratory tests, with at least two tests per year, and the establishment of individual variability and reference ranges can improve the assessment.

Bilateral Looser zones or pseudofractures in the anteromedial tibia as a component of medial tibial stress syndrome in athletes.

PURPOSE: Medial tibial stress syndrome (MTSS) represents a common diagnosis in individuals exposed to repetitive high-stress loads affecting the lower limb, e.g., high-performance athletes. However, the diagnostic approach and therapeutic regimens are not well established. METHODS: Nine patients, diagnosed as MTSS, were analyzed by a comprehensive skeletal analysis including laboratory bone turnover parameters, dual-energy X-Ray absorptiometry (DXA), and high-resolution peripheral quantitative computed tomography (HR-pQCT). RESULTS: In 4/9 patients, bilateral pseudofractures were detected in the mid-shaft tibia. These patients had significantly lower levels of 25-hydroxycholecalciferol compared to patients with MTSS but similar levels of bone turnover parameters. Interestingly, the skeletal assessment revealed significantly higher bone mineral density (BMD) Z-scores at the hip (1.3 ± 0.6 vs. - 0.7 ± 0.5, p = 0.013) in patients with pseudofractures and a trend towards higher bone microarchitecture parameters measured by HR-pQCT at the distal tibia. Vitamin D supplementation restored the calcium-homeostasis in all patients. Combined with weight-bearing as tolerated, pseudofractures healed in all patients and return to competition was achieved. CONCLUSION: In conclusion, deficient vitamin D levels may lead to pseudofractures due to localized deterioration of mineralization, representing a pivotal component of MTSS in athletes with increased repetitive mechanical loading of the lower limbs. Moreover, the manifestation of pseudofractures is not a consequence of an altered BMD nor microarchitecture but appears in patients with exercise-induced BMD increase in combination with reduced 25-OH-D levels. The screening of MTSS patients for pseudofractures is crucial for the initiation of an appropriate treatment such as vitamin D supplementation to prevent a prolonged course of healing or recurrence. LEVEL OF EVIDENCE: III.

[Impact of Vitamin D in Sports: Does Vitamin D Insufficiency Compromise Athletic Performance?] / Bedeutung von Vitamin D im Sport: Reduziert ein Mangel die Leistungsfähigkeit?

Introduction Vitamin D is essential for calcium homeostasis and regulates the expression of over 900 genes. It thereby influences musculoskeletal health and function. Additionally, multiple other effects were observed through the detection of vitamin D receptors (VDR) in numerous tissues of the human body. Material and Methods We reviewed the literature regarding evidence of the impact of vitamin D on musculoskeletal health and peak athletic performance. Results and Discussion It is well known that there is a high prevalence of vitamin D deficiency in the average European population. This article confirmed the same for athletes in different disciplines. Therefore, vitamin D deficiency and its effects are relevant for competitive sports. The surprisingly high prevalence of inadequate vitamin D levels depends on the geographic location, the time of day and year, local climate conditions, and sports disciplines (indoor vs. outdoor). Based on the analysed literature, we found several correlations between 25-OH-D3 serum levels and different aspects of competitive sports. A serum level ≥ 30 ng/ml provides sufficient mineralisation of non-mineralised bone matrix and is therefore crucial for skeletal health. Furthermore, this concentration was positively correlated with an accelerated regeneration of muscular force. Levels above 40 ng/ml provided a protective effect on the development of stress fractures. Researchers suspect that levels above 50 ng/ml are required for athletes to achieve maximal physical performance. While there is an ongoing discussion amongst researchers regarding beneficial effects of such high levels, it is well known that blood levels lower than 30 ng/ml lead to mineralisation defects in bone (rickets, osteomalacia) and muscular function (reversible myopathy). Conclusion This review suggests that athletes should have an evaluation of vitamin D-dependent calcium homeostasis based on laboratory tests of 25-OH-D3, calcium, creatinine, and parathyroid hormone. In case of vitamin D insufficiency, normal blood levels of ≥ 30 ng/ml may be restored by optimising the athlete's lifestyle and, if appropriate, oral substitution of cholecalciferol. This concentration is associated with a protective effect and enhancement of physical performance. Consequently, it is a requirement for restoring and maintaining musculoskeletal health and athletic performance.

Treatment of muscle injuries in football.

Muscle injuries are frequent and represent one of the most substantial medical problems in professional football. They can have both traumatic and overuse causes with direct practical consequence due to differences in terms of the post-primary care regimen and prognosis. An accurate diagnosis is the first step towards a specific treatment and usually allows to predict return to play (RTP). Current treatment principles have no firm scientific basis; they are practiced largely as empirical medicine due to a lack of prospective randomised studies. Immediate treatment usually follows the PRICE-principle (protection, rest, ice, compression, elevation). Depending on the type of the muscle injury, specific physical and physiotherapeutical procedures as well as rehabilitative exercises and gradual training therapy are used to recondition the injured structure, to restore coordination and proprioception, and to normalise movement patterns. Injection therapy with various substances is frequently used, with positive results empirically, but evidence in form of prospective randomised studies is lacking. A precise rehabilitation plan should be developed for every muscle injury, including recommendations for sport-specific training with increasing intensity. Since there are no guidelines regarding safe RTP, regular follow-up examinations on the current muscle status are crucial to evaluate the progress made in terms of healing and to determine when the injured muscle can be exposed to the next step of load. This narrative review describes the various factors that a medical team should consider during assessment, treatment and rehabilitation of a muscle injury with particular focus on professional football.

Intra-articular osteoid osteoma as a differential diagnosis of diffuse mono-articular joint pain.

BACKGROUND: The aim of this retrospective study was to investigate the frequency of intra-articular osteoid osteoma (iaOO) in a large study cohort and to demonstrate its clinical relevance as an important differential diagnosis of non-specific mono-articular joint pain. METHODS: We searched the registry for bone tumours of the University Medical Centre Hamburg-Eppendorf for osteoid osteomas in the last 42 years. Herein, we present three selected iaOO which were detected in the three major weight-bearing joints. Computed tomography (CT) or magnetic resonance imaging (MRI) scans were performed for initial diagnosis. RESULTS: Out of a total of 367 osteoid osteomas, 19 (5.2 %) tumours were localized intra-articularly. In all three presented tumours, a history of severe mono-articular pain was reported; however, the mean time to correct diagnosis was delayed to 20.7 months. Clearly, the nidus seen in CT and MRI images in combination with inconsistent salicylate-responsive nocturnal pain led to the diagnosis of iaOO. CONCLUSIONS: Rarely, osteoid osteoma can occur in an intra-articular location. In cases of diffuse mono-articular pain, iaOO should be considered both in large and smaller joints to avoid delays in diagnosis and therapy of this benign bone tumour.

Deterioration of teeth and alveolar bone loss due to chronic environmental high-level fluoride and low calcium exposure.

OBJECTIVES: Health risks due to chronic exposure to highly fluoridated groundwater could be underestimated because fluoride might not only influence the teeth in an aesthetic manner but also seems to led to dentoalveolar structure changes. Therefore, we studied the tooth and alveolar bone structures of Dorper sheep chronically exposed to very highly fluoridated and low calcium groundwater in the Kalahari Desert in comparison to controls consuming groundwater with low fluoride and normal calcium levels within the World Health Organization (WHO) recommended range. MATERIALS AND METHODS: Two flocks of Dorper ewes in Namibia were studied. Chemical analyses of water, blood and urine were performed. Mineralized tissue investigations included radiography, HR-pQCT analyses, histomorphometry, energy-dispersive X-ray spectroscopy and X-ray diffraction-analyses. RESULTS: Fluoride levels were significantly elevated in water, blood and urine samples in the Kalahari group compared to the low fluoride control samples. In addition to high fluoride, low calcium levels were detected in the Kalahari water. Tooth height and mandibular bone quality were significantly decreased in sheep, exposed to very high levels of fluoride and low levels of calcium in drinking water. Particularly, bone volume and cortical thickness of the mandibular bone were significantly reduced in these sheep. CONCLUSIONS: The current study suggests that chronic environmental fluoride exposure with levels above the recommended limits in combination with low calcium uptake can cause significant attrition of teeth and a significant impaired mandibular bone quality. CLINICAL RELEVANCE: In the presence of high fluoride and low calcium-associated dental changes, deterioration of the mandibular bone and a potential alveolar bone loss needs to be considered regardless whether other signs of systemic skeletal fluorosis are observed or not.

Nonoperative treatment and return to play after complete proximal adductor avulsion in high-performance athletes.

PURPOSE: To assess the outcome of nonoperative treatment after complete avulsion of the proximal adductor longus tendon in high-performance athletes. METHODS: Six consecutive athletes were included. Treatment was conservative following a strict rehabilitation plan. Following parameters were analysed: basic data, mechanism of injury, classification, tendon retraction, size of defect in MRI and return to play (RTP). RESULTS: Mean age at injury was 28 ± 5 (range 20-32) years. Overstretch (83 %) and kicking (50 %) were the most frequent injury mechanisms, and the dominant leg was involved in 83 %. Average retraction of the avulsed tendon amounted 21 ± 5 mm. Follow-up MRIs demonstrated a gradual reattachment of the tendon in all cases. All athletes returned to full sportive activity on preinjury level within 88.7 ± 12.8 (range 75-110) days with no functional deficiencies. Manual muscle strength was equal to the contralateral side. CONCLUSION: Nonoperative treatment with a healing phase and a strict rehabilitation plan results in a functional, efficient reattachment of the tendon and allows unrestricted RTP. Since these injuries are rare, present study may help sports physicians when dealing with this type of injuries in professional athletes. Return to sports can be expected at approximately 13 weeks after injury, but can take even longer. LEVEL OF EVIDENCE: Case series, Level IV.

Epidemiological and clinical outcome comparison of indirect ('strain') versus direct ('contusion') anterior and posterior thigh muscle injuries in male elite football players: UEFA Elite League study of 2287 thigh injuries (2001-2013).

BACKGROUND: Data regarding direct athletic muscle injuries (caused by a direct blunt or sharp external force) compared to indirect ones (without the influence of a direct external trauma) are missing in the current literature--this distinction has clinical implications. AIM: To compare incidence, duration of absence and characteristics of indirect and direct anterior (quadriceps) and posterior thigh (hamstring) muscle injuries. METHODS: 30 football teams and 1981 players were followed prospectively from 2001 until 2013. The team medical staff recorded individual player exposure and time-loss injuries. Muscle injuries were defined as indirect or direct according to their injury mechanism. RESULTS: In total, 2287 thigh muscle injuries were found, representing 25% of all injuries. Two thousand and three were valid for further analysis, of which 88% were indirect and 12% direct. The incidence was eight times higher for indirect injuries (1.48/1000 h) compared to direct muscle injuries (0.19/1000 h) (p<0.01). Indirect muscle injuries caused 19% of total absence, and direct injuries 1%. The mean lay-off time for indirect injuries amounted to 18.5 days and differed significantly from direct injuries which accounted for 7 days (p<0.001). 60% of indirect injuries and 76% of direct injuries occurred in match situations. Foul play was involved in 7% of all thigh muscle injuries, as well as in 2% of indirect injuries and 42% of direct injuries. SUMMARY: Muscle anterior and posterior thigh injuries in elite football are more frequent than have been previously described. Direct injuries causing time loss are less frequent than indirect ones, and players can usually return to full activity in under half the average time for an indirect injury. Foul play is involved in 7.5% of all thigh muscle injuries.

Suture anchor repair of proximal rectus femoris avulsions in elite football players.

PURPOSE: To report the results of suture anchor repair of proximal rectus femoris avulsions in elite football players. METHODS: Four professional football players (first-team regulars of European first division football clubs) underwent suture anchor repair of complete proximal rectus femoris avulsions with significant tendon retraction. The following parameters were analysed: demographic data, mechanism of injury, type of injury, classification according to the Munich consensus statement, time between injury and surgery, time between surgery and full participation in training and availability for match and/or competition selection (return to play/RTP), and time between surgery and the comeback to the first official league match (return to competition/RTC). Radiographic evaluation was performed by magnetic resonance imaging (MRI) obtained pre-operatively and at 6 and 12 weeks post-operatively. All players were followed for at least 24 months after return to play to exclude recurrence. RESULTS: Mean age at surgery was 30 ± 2 years. All injuries occurred while kicking a ball, with the dominant leg affected in all patients. The injury was considered acute in three cases and chronic in one case. According to the Munich classification, all injures were type 4. Mean time to surgery was 60 ± 88 days (range, 8-191), mean time to RTP was 111 ± 15 days (range, 100-134), and mean time to RTC was 140 ± 23 days (range, 114-166). Follow-up MRIs demonstrated anatomically reinserted tendons with decreasing signal intensity over time in all cases. After a mean follow-up of 35 ± 6 months, all players were still competing at the same level as before the injury without re-injury. CONCLUSION: Suture anchor repair of proximal rectus femoris avulsions allows unrestricted return to play in professional elite football players. Return to play can be expected at approximately 16 weeks post-operatively.

Intravenous bisphosphonates and vitamin D in the treatment of bone marrow oedema in professional athletes.

INTRODUCTION: The goal of this retrospective study was to evaluate the safety and efficacy of ibandronate for bone marrow oedema (BMO) syndrome and stress fracture cases, and to demonstrate an additional field of therapeutic importance-the high-performance athlete. PATIENTS AND METHODS: This retrospective study included twenty-five high-performance athletes. Sixty per cent of the athletes were European soccer players and 40.0% other high-class international athletes (3 women and 22 men with an average age of 25.0±4.2), with BMO of the lower trunk or extremity diagnosed by magnetic resonance imaging (MRI). The treatment regimen consisted of high-dose vitamin D supplementation and intravenous ibandronate therapy. RESULTS: The time between the onset of pain and proper diagnosis of BMO was 106.3±104.1 days. Excellent pain reduction (pain at rest and under strain) and improved mobility was reported within the first two weeks after the first ibandronate administration by sixteen patients (64%). The time from first treatment until return to competition (RTC) was on average 102.6±65.2 days in total. If the time from onset of pain until diagnosis was within 40 days, the RTC was significantly reduced (p≤0.05) to almost 50% (63.8±48.1 days) when compared to the athletes with later diagnosis (124.4±63.2 days). CONCLUSIONS: The here-applied therapy regimen of intravenous BPs application and vitamin D supplementation in BMO syndrome has a beneficial effect for high-performance athletes. An early diagnosis and rapid treatment start can reduce the RTC significantly. An optimal bone metabolism with sufficient daily calcium and vitamin D intake is crucial and should not only be strived for the professional but also for the recreational athlete.

Terminology and classification of muscle injuries in sport: the Munich consensus statement.

OBJECTIVE: To provide a clear terminology and classification of muscle injuries in order to facilitate effective communication among medical practitioners and development of systematic treatment strategies. METHODS: Thirty native English-speaking scientists and team doctors of national and first division professional sports teams were asked to complete a questionnaire on muscle injuries to evaluate the currently used terminology of athletic muscle injury. In addition, a consensus meeting of international sports medicine experts was established to develop practical and scientific definitions of muscle injuries as well as a new and comprehensive classification system. RESULTS: The response rate of the survey was 63%. The responses confirmed the marked variability in the use of the terminology relating to muscle injury, with the most obvious inconsistencies for the term strain. In the consensus meeting, practical and systematic terms were defined and established. In addition, a new comprehensive classification system was developed, which differentiates between four types: functional muscle disorders (type 1: overexertion-related and type 2: neuromuscular muscle disorders) describing disorders without macroscopic evidence of fibre tear and structural muscle injuries (type 3: partial tears and type 4: (sub)total tears/tendinous avulsions) with macroscopic evidence of fibre tear, that is, structural damage. Subclassifications are presented for each type. CONCLUSIONS: A consistent English terminology as well as a comprehensive classification system for athletic muscle injuries which is proven in the daily practice are presented. This will help to improve clarity of communication for diagnostic and therapeutic purposes and can serve as the basis for future comparative studies to address the continued lack of systematic information on muscle injuries in the literature. WHAT ARE THE NEW THINGS: Consensus definitions of the terminology which is used in the field of muscle injuries as well as a new comprehensive classification system which clearly defines types of athletic muscle injuries. LEVEL OF EVIDENCE: Expert opinion, Level V.

The influence of the stable expression of BMP2 in fibrin clots on the remodelling and repair of osteochondral defects.

Growth factors like BMP2 have been tested for osteochondral repair, but transfer methods used until now were insufficient. Therefore, the aim of this study was to analyse if stable BMP2 expression after retroviral vector (Bullet) transduction is able to regenerate osteochondral defects in rabbits. Fibrin clots colonized by control or BMP2-transduced chondrocytes were generated for in vitro experiments and implantation into standardized corresponding osteochondral defects (n=32) in the rabbit trochlea. After 4 and 12 weeks repair tissue was analysed by histology (HE, alcian-blue, toluidine-blue), immunohistochemistry (Col1, Col2, aggrecan, aggrecan-link protein), ELISA (BMP2), and quantitative RT-PCR (BMP2, Col1, Col2, Col10, Cbfa1, Sox9). In vitro clots were also analysed by BMP2-ELISA, histology (alcian-blue), quantitative RT-PCR and in addition by electron microscopy. BMP2 increased Col2 expression, proteoglycan production and cell size in vitro. BMP2 transduction by Bullet was efficient and gene expression was stable in vivo over at least 12 weeks. Proteoglycan content and ICRS-score of repair tissue were improved by BMP2 after 4 and 12 weeks and Col2 expression after 4 weeks compared to controls. However, in spite of stable BMP2 expression, a complete repair of osteochondral defects could not be demonstrated. Therefore, BMP2 is not suitable to regenerate osteochondral lesions completely.

A fibrin glue composition as carrier for nucleic acid vectors.

PURPOSE: Gene delivery from biomaterials has become an important tool in tissue engineering. The purpose of this study was to generate a gene vector-doted fibrin glue as a versatile injectable implant to be used in gene therapy supported tissue regeneration. METHODS: Copolymer-protected polyethylenimine(PEI)-DNA vectors (COPROGs), naked DNA and PEI-DNA were formulated with the fibrinogen component of the fibrin glue TISSUCOL and lyophilized. Clotting parameters upon rehydration and thrombin addition were measured, vector release from fibrin clots was determined. Structural characterizations were carried out by electron microscopy. Reporter and growth factor gene delivery to primary keratinocytes and chondrocytes in vitro was examined. Finally,chondrocyte colonized clots were tested for their potency in cartilage regeneration in a osteochondral defect model. RESULTS: The optimized glue is based on the fibrinogen component of TISSUCOL, a fibrin glue widely used in the clinics, co-lyophilized with copolymer-protected polyethylenimine(PEI)- DNA vectors (COPROGs). This material, when rehydrated, forms vector-containing clots in situ upon thrombin addition and is suitable to mediate growth factor gene delivery to primary keratinocytes and primary chondrocytes admixed before clotting. Unprotected PEI-DNA in the same setup was comparatively unsuitable for clot formation while naked DNA was ineffective in transfection. Naked DNA was released rapidly from fibrin clots (>70% within the first seven days) in contrast to COPROGs which remained tightly immobilized over extended periods of time (0.29% release per day). Electron microscopy of chondrocytecolonized COPROG-clots revealed avid endocytotic vector uptake. In situ BMP-2 gene transfection and subsequent expression in chondrocytes grown in COPROG clots resulted in the upregulation of alkaline phosphatase expression and increased extracellular matrix formation in vitro. COPROG-fibrinogen preparations with admixed autologous chondrocytes when clotted in situ in osteochondral defects in the patellar grooves of rabbit femura gave rise to luciferase reporter gene expression detectable for two weeks (n=3 animals per group). However, no significant improvement in cartilage formation in osteochondral defects filled with autologous chondrocytes in BMP-2-COPROG clots was achieved in comparison to controls (n=8 animals per group). CONCLUSIONS: COPROGs co-lyophilized with fibrinogen are a simple basis for an injectable fibrin gluebased gene-activated matrix. The preparation can be used is complete analogy to fibrin glue preparations that are used in the clinics. However, further improvements in transgene expression levels and persistence are required to yield cartilage regeneration in the osteochondral defect model chosen in this study.

Efficient and stable gene transfer of growth factors into chondrogenic cells and primary articular chondrocytes using a VSV.G pseudotyped retroviral vector.

Since efficient transfer of foreign genes into primary articular chondrocytes (CC) is difficult, a VSV.G pseudotyped retroviral vector (Bullet) was developed for marker and growth factor gene transfer. Transduction efficiency was analysed by FACS. BMP2 production was determined by specific hBMP2-ELISA. BMP2 effect on cells regarding proteoglycan production was measured by alcian blue staining and dye quantification. Alkaline phosphatase activity was determined by enzymatic reaction with p-nitrophenyl phosphate at OD 405nm and proliferation rate was analysed by MTT-assay. ATDC5 cells (98.3+/-0.6%SD) were transduced to express the reporter gene eGFP. After 52 weeks 94.7+/-0.6%SD of cells were positive. Retroviral transduction efficiency for nlslacZ exceeded 92.3+/-6.1%SD in rabbit CC and expression remained high after 15 weeks (75.7+/-14.2%SD). ATDC5 cells and CC expressed the growth factor gene hBMP2 after retroviral transduction at different time-points. BMP2 led to an increase in proteoglycan and alkaline phosphatase production. Initially, the proliferation rate detected by MTT-assay increased in both the cell types; afterwards the proliferation rate was similar to controls. The described retroviral vector system achieved high initial transduction rates in ATDC5 cells and CC. Gene transfer was very stable over the time period analysed, rendering it a useful tool for future in vitro and in vivo studies on cartilage remodelling.

The fate of osteochondral grafts after autologous osteochondral transplantation: a one-year follow-up study in a minipig model.

INTRODUCTION: Because articular cartilage shows little intrinsic capacity of spontaneous regeneration, a variety of treatment options are currently at use to repair cartilage damage. One of these is the autologous osteochondral transplantation (AOT). The aim of the present work was to study the histological changes during the progress of 1 year after AOT in the knee joint. MATERIALS AND METHODS: Twelve Minipigs underwent an AOT on the medial femoral condyles of both knees using cooled diamond studded trephines with a diameter of the grafts of 4.6 mm. Three animals were sacrificed at each 2, 8, 26 and 52 weeks after the operation. The condyles were analyzed histologically and immunohistologically for collagen types I and II. RESULTS: A successful bony incorporation was observed in all specimens. The transplant demonstrated an increasingly stable integration of the chondral matrix into the cartilage of the surrounding femoral condyle. At 52 weeks after the operations 5 of 6 condyles showed a chondral integration at least at one side of the graft. Immunohistologically all specimens showed physiological staining characteristics up to 52 weeks after operation. The quality of the chondral part of the graft showed a wide range of variations, ranging from vital tissue resembling native cartilage after 52 weeks, to severe degenerative signs beginning 2 weeks after operation and ending at 52 weeks with deep fissures fragmenting the cartilage and the complete loss of vital cells. CONCLUSION: The press-fit technique allows a stable bony incorporation. A chondral integration of the graft seems to occur, provided that a close contact between the interfaces can be achieved. Present results demonstrate a vital cartilagenous transplant for up to 52 weeks. However, some specimens showed in part severe degenerative signs. A possible explanation is an insufficient cooling of the trephines in relation to the small diameter of the grafts used in the minipig model. The collagen network seems not to be affected for up to 52 weeks.

Osteochondral transplantation to treat osteochondral lesions in the elbow.

BACKGROUND: Effective treatment of osteochondral lesions in the elbow remains challenging. Arthroscopic débridement and microfracture or retrograde drilling techniques are often insufficient and provide only temporary symptomatic relief. The purpose of this study was to evaluate the treatment of these lesions with osteochondral autografts. METHODS: From 1999 to 2002, seven patients with osteochondral lesions of the capitellum humeri (five patients), trochlea (one patient), or radial head (one patient) were treated with cylindrical osteochondral grafts, which were harvested from the non-weight-bearing area of the proximal aspect of the lateral femoral condyle. The patients (three female and four male patients with an average age of seventeen years) were evaluated preoperatively and postoperatively, with an average follow-up of fifty-nine months. The Broberg and Morrey score was chosen for functional evaluation of the elbow (with regard to motion, pain, strength, activities of daily living, and stability), and the American Shoulder and Elbow Surgeons score was used for the analysis of pain. All patients had imaging studies done preoperatively to evaluate the defect and postoperatively to assess the ingrowth and viability of the graft. The ipsilateral knee was examined for donor-site morbidity. RESULTS: The Broberg and Morrey score improved from a mean (and standard deviation) of 76.3 +/- 13.2 preoperatively to 97.6 +/- 2.7 postoperatively, and pain scores were significantly reduced (p < 0.05). The mean elbow extension lag of 4.7 degrees +/- 5.8 degrees was reduced to 0 degrees postoperatively. Compared with the contralateral side, there was a mean preoperative flexion lag of 12.9 degrees +/- 13.8 degrees . At the time of the final follow-up, flexion was free and was equal bilaterally in all patients. None of the plain radiographs made at the time of follow-up showed any degenerative changes or signs of osteoarthritis. The postoperative magnetic resonance imaging scans showed graft viability and a congruent chondral surface in all seven patients. No donor-site morbidity was noted at one year postoperatively. CONCLUSIONS: The osteochondral autograft procedure described in the present study provides the opportunity to retain viable hyaline cartilage for the repair of osteochondral lesions in the elbow while restoring joint congruity and function and perhaps reducing the risk of osteoarthritis. These medium-term results suggest that the risks of a two-joint procedure are modest and justifiable. In addition, the described technique provides an option for revision surgery after the failure of other surgical procedures.

In vitro analysis of an allogenic scaffold for tissue-engineered meniscus replacement.

Scaffolds play a key role in the field of tissue engineering. Particularly for meniscus replacement, optimal scaffold properties are critical. The aim of our study was to develop a novel scaffold for replacement of meniscal tissue by means of tissue engineering. Emphasis was put on biomechanical properties comparable to native meniscus, nonimmunogenecity, and the possibility of seeding cells into and cultivating them within the scaffold (nontoxicity). For this purpose, native ovine menisci were treated in vitro in a self-developed enzymatic process. Complete cell removal was achieved and shown both histologically and electron microscopically (n = 15). Immunohistochemical reaction (MHC 1/MHC 2) was positive for native ovine meniscus and negative for the scaffold. Compared to native meniscus (25.8 N/mm) stiffness of the scaffold was significantly increased (30.2 N/mm, p < 0.05, n = 10). We determined the compression (%) of the native meniscus and the scaffold under a load of 7 N. The compression was 23% for native meniscus and 29% for the scaffold (p < 0.05, n = 10). Residual force of the scaffold was significantly lower (5.2 N vs. 4.9 N, p < 0.05, n = 10). Autologous fibrochondrocytes were needle injected and successfully cultivated within the scaffolds over a period of 4 weeks (n = 10). To our knowledge, this study is the first to remove cells and immunogenetic proteins (MHC 1/MHC 2) completely out of native meniscus and preserve important biomechanical properties. Also, injected cells could be successfully cultivated within the scaffold. Further in vitro and in vivo animal studies are necessary to establish optimal cell sources, sterilization, and seeding techniques. Cell differentiation, matrix production, in vivo remodeling of the construct, and possible immunological reactions after implantation are subject of further studies.