Multilayer scaffolds in orthopaedic tissue engineering.

PURPOSE: The purpose of this study was to summarize the recent developments in the field of tissue engineering as they relate to multilayer scaffold designs in musculoskeletal regeneration. METHODS: Clinical and basic research studies that highlight the current knowledge and potential future applications of the multilayer scaffolds in orthopaedic tissue engineering were evaluated and the best evidence collected. Studies were divided into three main categories based on tissue types and interfaces for which multilayer scaffolds were used to regenerate: bone, osteochondral junction and tendon-to-bone interfaces. RESULTS: In vitro and in vivo studies indicate that the use of stratified scaffolds composed of multiple layers with distinct compositions for regeneration of distinct tissue types within the same scaffold and anatomic location is feasible. This emerging tissue engineering approach has potential applications in regeneration of bone defects, osteochondral lesions and tendon-to-bone interfaces with successful basic research findings that encourage clinical applications. CONCLUSIONS: Present data supporting the advantages of the use of multilayer scaffolds as an emerging strategy in musculoskeletal tissue engineering are promising, however, still limited. Positive impacts of the use of next generation scaffolds in orthopaedic tissue engineering can be expected in terms of decreasing the invasiveness of current grafting techniques used for reconstruction of bone and osteochondral defects, and tendon-to-bone interfaces in near future.

Lipoma arborescens of the knee.

PURPOSE: Lipoma arborescens (LA) is a benign lesion described as replacement of mature fat cells with sub-synovial tissue, which causes the formation of villous projections. Underlying inflammatory conditions might predispose LA. This study demonstrates the treatment, post-operative survey and MRI demonstrations of this rare entity. METHODS: Five patients (6 knees) diagnosed and treated with arthroscopic (5/6) and open (1/6) synovectomy were reviewed retrospectively. An additional mini-transquadricipital incision is used for excision of the extensive suprapatellar lesions. The patients had post-operative follow-ups at first and sixth months and then yearly. Radiographs and MRI of the affected knees were taken at the final follow-up. RESULTS: The median follow-up was 59 (4-105) months. Major symptom was painless swelling of the joint. The presenting age was under 18 years in four patients. Recurrent lesions were detected in MRI scan of three patients with JRA, ARF and Tbc. Two out of three were located adjacent to the posterior capsule. The median of the Kujala questionnaire scores was 88 (74-95), and the median of the Knee Society Clinical Rating System scores was 95 (80-100) at the final follow-up. CONCLUSIONS: Lipoma arborescens should be considered in the differential diagnosis of paediatric patients who have painless swelling of the knee joint. The lesion is totally curable. However, underlying persistent disease might aggravate the inflammatory process and might cause recurrent lesions. Although resecting the lesion adjacent to the posterior capsule of the knee joint is technically demanding, arthroscopic treatment is an effective procedure and transquadricipital approach may help resection of the extensive lesions in suprapatellar pouch. LEVEL OF EVIDENCE: Case series, Level IV.

Development of the femoral trochlear groove in rabbits with patellar malposition.

PURPOSE: The geometry of the trochlear groove is considered to be an important determinant in the pathogenesis of the patellofemoral joint disorders. However, the effect of patellar position during the development of the femoral trochlear groove is unclear. This animal study aimed to investigate the relationship between the position of the patella and development of the femoral trochlear groove in growing rabbits. METHODS: Thirty-two knees from 16 rabbits were included in this study and were divided into two groups. First group consisted of the left knees and was used as a control group with no surgical interventions. The second group involved the right knees on which patellar tendon Z-plasty lengthening was performed to cause patellar malposition (patella alta) before 1 month of age. Computed tomographic (CT) evaluations of both knees were obtained when the animals were 1 month age before the surgical intervention and also at 6 months after the surgical intervention. Angle and depth measurements were acquired from the proximal, middle, and distal reference points along the femoral trochlear groove. After the CT scan acquisition at 6 months following the surgical procedures, rabbits were killed and additional measurements of the trochlear groove angles were performed manually. RESULTS: The mean middle and distal trochlear groove angles for the experiment group with patella alta were significantly higher compared to that of control group (p < 0.017). The increase in mean trochlear depth for the animals in the control group was found to be significantly higher compared to experiment group at the distal zone (p < 0.017). CONCLUSION: Distal femoral groove with an inadequately positioned patella becomes more flattened and this may be a predisposing factor for patellar instability. LEVEL OF EVIDENCE: Controlled laboratory study, Level II.

An emerging cell-based strategy in orthopaedics: endothelial progenitor cells.

PURPOSE: The purpose of this article was to analyze the results of studies in the literature, which evaluated the use of endothelial progenitor cells (EPCs) as a cell-based tissue engineering strategy. METHODS: EPCs have been successfully used in regenerative medicine to augment neovascularization in patients after myocardial infarction and limb ischemia. EPCs' important role as vasculogenic progenitors presents them as a potential source for cell-based therapies to promote bone healing. RESULTS: EPCs have been shown to have prominent effects in promoting bone regeneration in several animal models. Evidence indicates that EPCs promote bone regeneration by stimulating both angiogenesis and osteogenesis through a differentiation process toward endothelial cell lineage and formation of osteoblasts. Moreover, EPCs increase vascularization and osteogenesis by increased secretion of growth factors and cytokines through paracrine mechanisms. CONCLUSION: EPCs offer the potential to emerge as a new strategy among other cell-based therapies to promote bone regeneration. Further investigations and human trials are required to address current questions with regard to biology and mechanisms of action of EPCs in bone tissue engineering.

Arthroscopy-assisted fracture fixation.

PURPOSE: the purpose of this article was to systematically analyze the results of published studies in the literature which evaluated the use of arthroscopically assisted techniques in intra-articular fracture fixation. METHODS: published investigations to date were analyzed by classifying them according to joints that were involved with intra-articular fractures including: knee, ankle, hip, shoulder, elbow, and wrist joints. The results were studied to assess the feasibility, efficiency, and outcomes of arthroscopy-assisted fracture fixation. RESULTS: arthroscopy-assisted techniques have been used successfully for the treatment of fractures of the tibial plateau, tibial eminence, malleoli, pilon, calcaneus, femoral head, glenoid, greater tuberosity, distal clavicle, radial head, coronoid, distal radius, and scaphoid. The major advantages of arthroscopic fracture fixation over open methods are direct visualization of the intra-articular space, decreased invasiveness, and the possibility for multitask interventions through which fixation of the fracture, and repair of the soft tissues and the cartilage can be performed simultaneously. The time-consuming and technically demanding nature of the procedures with a prolonged learning curve and limited fixation alternatives are the main disadvantages of this technique. CONCLUSION: arthroscopic fixation is increasingly utilized for certain intra-articular fracture types due to the minimally invasive nature of the procedures and high accuracy. Randomized controlled trials are needed to justify wider use of arthroscopy-assisted techniques for treatment of intra-articular fractures.

Symptomatic bipartite patella: treatment alternatives.

Bipartite patella is usually an asymptomatic, incidental finding. However, in adolescents, it may be a cause of anterior knee pain following trauma or a result of overuse or strenuous sports activity. Most patients improve with nonsurgical treatment. Surgery is considered when nonsurgical treatment fails. Excision of the fragment is the most popular surgical option, with good results. However, when the fragment is large and has an articular surface, excision may lead to patellofemoral incongruity. Lateral retinacular release and detachment of the vastus lateralis muscle insertion are other surgical options and are reported to produce good pain relief and union in some patients. These procedures reduce the traction force of the vastus lateralis on the loose fragment. Internal fixation of the separated fragment has limited support in the literature. Understanding the possible consequences of different treatment approaches to painful bipartite patella is necessary to preserve quadriceps muscle strength and patellofemoral joint function.

Management of discoid lateral meniscus tears: observations in 34 knees.

PURPOSE: The goal of this study was to evaluate arthroscopic partial resection of discoid lateral meniscus tears with an emphasis on radiographic evidence of degenerative changes after this procedure. TYPE OF STUDY: Retrospective clinical study. METHODS: Of 41 patients with an arthroscopic diagnosis of discoid meniscus over an 8-year period, 34 symptomatic lateral discoid meniscus tears in 33 patients were analyzed at an average follow-up of 5.6 years. The average age at operation was 19.8 years and most patients had vague and intermittent symptoms that caused delay in clinical diagnosis. RESULTS: Eight patients were lost to follow-up and were excluded from the study. Magnetic resonance imaging, performed in 12 cases, and arthroscopy in all of these patients provided the precise diagnosis. All of the knees with symptomatic torn discoid menisci underwent arthroscopic partial meniscectomy. Only 1 Watanabe Wrisberg ligament type of discoid meniscus with posterior instability was totally meniscected. Based on Ikeuchi's grading, 39% of the knees had an excellent result, 46% had a good result, and 15% had a fair result; none of the results was poor. CONCLUSIONS: At an average 5-year follow-up, partial meniscectomy in patients with a Watanabe complete or incomplete discoid meniscus showed 85% good or excellent clinical results. However, a significant percentage of patients show femoral condyle flattening on radiography.

Augmentation of tendon-to-bone healing.

Tendon-to-bone healing is vital to the ultimate success of the various surgical procedures performed to repair injured tendons. Achieving tendon-to-bone healing that is functionally and biologically similar to native anatomy can be challenging because of the limited regeneration capacity of the tendon-bone interface. Orthopaedic basic-science research strategies aiming to augment tendon-to-bone healing include the use of osteoinductive growth factors, platelet-rich plasma, gene therapy, enveloping the grafts with periosteum, osteoconductive materials, cell-based therapies, biodegradable scaffolds, and biomimetic patches. Low-intensity pulsed ultrasound and extracorporeal shockwave treatment may affect tendon-to-bone healing by means of mechanical forces that stimulate biological cascades at the insertion site. Application of various loading methods and immobilization times influence the stress forces acting on the recently repaired tendon-to-bone attachment, which eventually may change the biological dynamics of the interface. Other approaches, such as the use of coated sutures and interference screws, aim to deliver biological factors while achieving mechanical stability by means of various fixators. Controlled Level-I human trials are required to confirm the promising results from in vitro or animal research studies elucidating the mechanisms underlying tendon-to-bone healing and to translate these results into clinical practice.

Bilateral lipoma arborescens of the knee in a child: a case report.

We report a case of childhood lipoma arborescens of both knee joints who had been erroneously diagnosed to have initially acute rheumatic fever and subsequently oligoarticular juvenile rheumatoid arthritis. She had taken anti-inflammatory medication for 8 years without remission of the effusion. Magnetic resonance imaging (MRI) and synovectomy revealed the diagnosis of lipoma arborescens. Lipoma arborescens should be kept in mind in the differential diagnosis of refractory chronic joint effusion and synovial hypertrophy in the childhood period, and MRI yields the correct diagnosis in this setting.

Age-related changes in human PCLs: a light and electron microscopic study.

No studies have previously compared ultrastructural differences in human posterior cruciate ligaments in different age groups, but such differences may be of importance in the reconstruction of this ligament. We used light and transmission electron microscopy to compare ultrastructural differences in the posterior cruciate ligaments of 36 patients by age and sex. We found no differences between the sexes or in the groups aged between 30 and 59 years. However, collagen fibers with variable diameters were observed in those aged 10-19 years, with many oxytalan fibers between the collagen fibers. We also found a decrease in collagen fiber diameter and increase in collagen fibril concentration with aging, with a maximum increase in collagen fibril concentration in those aged 60-69 years.

Anterior labroligamentous periosteal sleeve avulsion lesion at the superior glenoid labrum.

An unusual type of anterior labroligamentous periosteal sleeve avulsion (ALPSA) lesion in the superior, instead of the usual inferior, part of the anterior glenoid labrum is presented in a 33-year-old man who sustained a traumatic dislocation of his left shoulder. Magnetic resonance imaging raised the possibility of an ALPSA lesion and later arthroscopy confirmed the diagnosis. Arthroscopic repair of the lesion was performed after the labral avulsion was lateralized.

MR imaging of meniscal bucket-handle tears: a review of signs and their relation to arthroscopic classification.

Our objective was to review the MR imaging signs of meniscal bucket-handle tears and assess the relevance of these signs to the arthroscopic classification of displaced meniscal tears. Forty-five menisci in 42 patients who had a diagnosis of bucket-handle tear either on MR imaging or on subsequent arthroscopy (in which Dandy's classification of meniscal tears was used) were retrospectively analyzed for MR imaging findings of double posterior cruciate ligament (PCL), fragment within the intercondylar notch, absent bow tie, flipped meniscus, double-anterior horn, and disproportional posterior horn signs. Arthroscopy, which was considered as the gold standard, revealed 41 bucket-handle tears (either diagnosed or not diagnosed by MR imaging) in 38 patients (33 males, 5 females). There was a statistically significant male preponderance for the occurrence of meniscal bucket-handle tears. Overall, sensitivity and positive predictive value of MR imaging for the detection of meniscal bucket-handle tears were calculated as 90%. Common MR imaging signs of meniscal bucket-handle tears in arthroscopically proven cases of such tears were the fragment in the notch and absent bow tie signs (98% frequency for each). Double-PCL, flipped meniscus, double-anterior horn, and disproportional posterior horn signs, however, were less common (32, 29, 29, and 27%, respectively). An arthroscopically proven bucket-handle tear was found in all patients who displayed at least three of the six MR imaging signs of meniscal bucket-handle tears. The presence of three or more MR imaging signs of meniscal bucket-handle tears is highly suggestive of this condition.

MR imaging of the anterior intermeniscal ligament: classification according to insertion sites.

Our objective was to study the frequency of anterior intermeniscal ligament on MR imaging and to make a classification according to its insertion sites on MR images. Sagittal T1-weighted and thin-section transverse T2*-weighted MR images of the knee were prospectively evaluated in 229 subjects without significant synovial effusion or total rupture of the anterior cruciate ligament. By using thin-section transverse images, the ligament was classified into three types according to its insertion sites (type A: between anterior horns of medial and lateral menisci; type B: between anterior horn of medial meniscus and anterior margin of lateral meniscus; type C: between anterior margins of medial and lateral menisci). On sagittal images location of the ligament was determined with respect to a line drawn between anterior of the tibial epiphysis and posterior of the intercondylar notch to look for a relation between its type on transverse images and location on sagittal images. Separately, arthroscopy was made in 36 patients to verify the MR assessment of the presence of the ligament. Anterior intermeniscal ligament was found in 53% of the subjects. Type B was the most common group (58%). Magnetic resonance imaging has a sensitivity and a specificity of 67 and 100%, respectively, in the detection of the ligament. Types A and C had a statistically significant location posterior and anterior, respectively, to the master line on sagittal images. In arthroscopy, the ligament was either cord-like (67%) or flat (33%) in appearance. Routine sagittal MR images can help identify anterior intermeniscal ligament.

Symptomatic ring-shaped lateral meniscus: magnetic resonance imaging and arthroscopy.

A ring-shaped lateral meniscus is a very rare entity within the spectrum of abnormalities of lateral meniscus. We present the second case in the literature of a symptomatic ring-shaped lateral meniscus in combination with a meniscal cyst and in association with an osteochondritis dissecans lesion of the medial femoral condyle. A potential pitfall of magnetic resonance imaging (i.e., displaced meniscal tear) is addressed in the diagnosis of this entity, as well as the role of magnetic resonance imaging in revealing associated abnormalities.