Treatment of cartilage defects in the patellofemoral joint with matrix-associated autologous chondrocyte implantation effectively improves pain, function, and radiological outcomes after 5-7 years.

INTRODUCTION: The aim of the present study was to evaluate midterm outcomes 5-7 years after matrix-associated autologous chondrocyte implantation (MACI) in the patellofemoral joint. MATERIALS AND METHODS: Twenty-six patients who had undergone MACI using the Novocart® 3D scaffold were prospectively evaluated. Clinical outcomes were determined by measuring the 36-Item Short-Form Health Survey (SF-36) and International Knee Documentation Committee (IKDC) scores and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) values preoperatively and 3, 6, and 12 months, and a mean of 6 years postoperatively. At the final follow-up, the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score was evaluated. RESULTS: Twenty-two patients with 23 focal cartilage defects (19 patella and four trochlea) were available for the final follow-up. The mean defect size was 4.0 ± 1.9 cm2 (range 2.4-9.4 cm2). All clinical outcome scores improved significantly until 5-7 years after MACI (SF-36 score, 61.2 ± 19.6 to 83.2 ± 11.6; P = 0.001; IKDC score, 47.5 ± 20.6 to 74.7 ± 15.5; P < 0.001; and WOMAC, 29.8 ± 15.7 to 8.2 ± 10.3; P < 0.001). The mean MOCART score was 76.0 ± 11.0 at the final follow-up. Nineteen of the 22 patients (86.4%) were satisfied with the outcomes after 5-7 years and responded that they would undergo the procedure again. CONCLUSION: MACI in the patellofemoral joint demonstrated good midterm clinical results with a significant reduction in pain, improvement in function, and high patient satisfaction. These clinical findings are supported by radiological evidence from MOCART scores. LEVEL OF EVIDENCE: IV-case series.

Microresonator-based solitons for massively parallel coherent optical communications.

Solitons are waveforms that preserve their shape while propagating, as a result of a balance of dispersion and nonlinearity. Soliton-based data transmission schemes were investigated in the 1980s and showed promise as a way of overcoming the limitations imposed by dispersion of optical fibres. However, these approaches were later abandoned in favour of wavelength-division multiplexing schemes, which are easier to implement and offer improved scalability to higher data rates. Here we show that solitons could make a comeback in optical communications, not as a competitor but as a key element of massively parallel wavelength-division multiplexing. Instead of encoding data on the soliton pulse train itself, we use continuous-wave tones of the associated frequency comb as carriers for communication. Dissipative Kerr solitons (DKSs) (solitons that rely on a double balance of parametric gain and cavity loss, as well as dispersion and nonlinearity) are generated as continuously circulating pulses in an integrated silicon nitride microresonator via four-photon interactions mediated by the Kerr nonlinearity, leading to low-noise, spectrally smooth, broadband optical frequency combs. We use two interleaved DKS frequency combs to transmit a data stream of more than 50 terabits per second on 179 individual optical carriers that span the entire telecommunication C and L bands (centred around infrared telecommunication wavelengths of 1.55 micrometres). We also demonstrate coherent detection of a wavelength-division multiplexing data stream by using a pair of DKS frequency combs-one as a multi-wavelength light source at the transmitter and the other as the corresponding local oscillator at the receiver. This approach exploits the scalability of microresonator-based DKS frequency comb sources for massively parallel optical communications at both the transmitter and the receiver. Our results demonstrate the potential of these sources to replace the arrays of continuous-wave lasers that are currently used in high-speed communications. In combination with advanced spatial multiplexing schemes and highly integrated silicon photonic circuits, DKS frequency combs could bring chip-scale petabit-per-second transceivers into reach.

Failure rates of common grafts used in ACL reconstructions: a systematic review of studies published in the last decade.

INTRODUCTION: In this review paper, graft failure rates of different graft types (hamstring tendon autografts, bone-patellar tendon-bone autografts, quadriceps tendon autografts and diverse allografts) that are used for surgical reconstruction of the anterior cruciate ligament are compared and statistically analysed. METHODS: Literature search was conducted in PubMed according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) criteria. A total of 194 studies, which reported graft failure rates of at least one of the anterior cruciate ligament reconstruction methods mentioned above, were included in this systematic review. To be able to compare studies with different follow-up periods, a yearly graft failure rate for each reconstruction group was calculated and then investigated for significant differences by using the Kruskal-Wallis test. RESULTS: Overall, a total of 152,548 patients treated with an anterior cruciate ligament reconstruction were included in the calculations. Comparison of graft types showed that hamstring tendon autografts had a yearly graft failure rate of 1.70%, whereas the bone-patellar tendon-bone autograft group had 1.16%, the quadriceps tendon autograft group 0.72%, and the allografts 1.76%. CONCLUSION: The findings of this meta-data study indicate that reconstructing the anterior cruciate ligament using quadriceps tendon autografts, hamstring tendon autografts, patellar tendon autografts or allografts does not show significant differences in terms of graft failure rates.

Influence of the anterior notch in mobile-bearing UKA on patellofemoral radiotracer uptake and clinical outcome.

BACKGROUND: Previous studies reported that in partial knee arthroplasty smooth transitions to the remaining native parts of the knee are important. However, in mobile-bearing unicondylar knee arthroplasty (UKA) it is mandatory to create an anterior osteochondral notch adjacent to the femoral component to get clearance for the anterior lip of the bearing in full knee extension. This notch is, however, part of the femoral trochlea. It was the aim of the study to test for a potential association between a) an obligatory anterior notch in mobile-bearing UKA located at the margin of the medial aspect of the femoral trochlea and b) postoperative patellofemoral joint (PFJ) bone remodelling and discomfort. METHODS: In patients who underwent routine mobile-bearing UKA (11 male, 13 female; 64.5 years / IQR 14) the following parameters were prospectively determined i) size of the surgically created anterior notch, ii) knee score sensitive to PFJ disorders, iii) bone remodelling in the PFJ (radiotracer uptake in SPECT-CT). RESULTS: Notch size was not correlated with radiotracer uptake at the PFJ. Similarly, no significant correlations were observed between radiotracer uptake (patella or trochleocondylar junction) and knee scores (KOOS or Kujala Score). Significant positive correlations were found between notch size and knee scores. CONCLUSIONS: From the findings made in our study it is concluded that a larger size of the anterior notch in mobile-bearing medial Oxford UKA is not associated with increased osteochondral remodelling processes at the patella or the trochleocondylar junction. Neither is a larger sized notch associated with worse clinical PFJ outcome. Surprisingly, a larger notch was even associated with superior clinical outcome. The exact mechanism for this contraintuitive finding remains unclear but may be the basis for future research. TRIAL REGISTRATION: The study is registered in a public trials registry. Link: (9/12/2017) ClinicalTrials.gov. NCT01407042 ; Date of registration: July, 26, 2011.

Changes in articular cartilage following arthroscopic partial medial meniscectomy.

PURPOSE: To examine degenerative changes in all cartilage surfaces of the knee following arthroscopic partial medial meniscectomy. METHODS: For this prospective cohort study, 14 patients (five female) with a mean age of 47.9 ± 12.9 years who had undergone isolated arthroscopic partial medial meniscectomy were evaluated. Cartilage-sensitive magnetic resonance imaging (MRI) scans were acquired from the operated knees before the index operations, as well as at 6, 12, and 24 months after surgery. The MRI scans were assessed for the prevalence, severity, and size of cartilage degenerations. The clinical outcome was assessed using the SF-36 physical and mental component score and the International Knee Documentation Committee Knee Evaluation Form and was correlated with radiological findings. RESULTS: There was a significant increase in the severity of cartilage lesions in the medial tibial plateau (P = 0.019), as well as a trend towards an increase in the lateral tibial plateau. The size of the cartilage lesions increased significantly in the medial femoral condyle (P = 0.005) and lateral femoral condyle (P = 0.029), as well as in the patella (P = 0.019). Functional outcome scores improved significantly throughout the follow-up period. There was no correlation between cartilage wear and functional outcome. CONCLUSIONS: Arthroscopic partial medial meniscectomy is associated with adverse effects on articular cartilage and may lead to an increase in the severity and size of cartilage lesions. Post-operative cartilage wear predominantly affected the medial compartment and also affected the other compartments of the knee. Strategies to reduce subsequent osteoarthritic changes need to involve all compartments of the knee. LEVEL OF EVIDENCE: IV.

Treatment of osteochondral fractures of the knee: a meta-analysis of available scientific evidence.

PURPOSE: Although traumatic osteochondral fractures of the knee represent a common pathology of the knee joint, there is no general agreement concerning specific treatment of this entity. This meta-analysis was initiated in order to evaluate scientific evidence on different treatment options for acute osteochondral fractures of the knee. METHODS: For this purpose an OVID-based systematic literature search was performed including the following databases: MEDLINE, MEDLINE preprints, Embase, CINAHL, Life Science Citations, British National Library of Health and Cochrane Central Register of Controlled Trials. The literature search period was from 1946 to January 2012, which led to the identification of 1,226 articles. After applying study-specific inclusion criteria a total of 19 studies with clinical follow-up of 638 patients were included. The methodology of these studies was systematically analysed by means of the Coleman Methodology Score. Outcome and success rates were evaluated depending on treatment applied. RESULTS: All studies (n = 19) identified represent case series (evidence-based medicine level IV) and included a total of 638 patients. The average post-operative follow-up was 46 ± 27 months (range 3.75-108). The mean number of study subjects per study was 33 ± 44 patients (range 4-169). The average Coleman Methodology Score was 29 ± 17 points (range 5-72). Six different scoring systems were used for clinical assessment. The overall clinical success rate was 83% and varied between 45 and 100%. CONCLUSIONS: This meta-analysis reveals a significant lack of scientific evidence for treatment of osteochondral fractures of the knee. No valid conclusion can be drawn from this study concerning the recommendation of a specific treatment algorithm. Nevertheless, the overall failure rate of 17% underlines that an acute osteochondral fracture of the knee represents an important pathology which is not a self-limiting injury and needs further investigation.

Volumetric analysis of corticocancellous bones using CT data.

OBJECTIVE: To present a method for an automated volumetric analysis of corticocancellous bones such as the superior pubic ramus using CT data and to assess the reliability of this method. MATERIALS AND METHODS: Computed tomography scans of a consecutive series of 250 patients were analyzed. A Hounsfield unit (HU) thresholding-based reconstruction technique ("Vessel Tracking," GE Healthcare) was used. A contiguous space of cancellous bone with similar HU values between the starting and end points was automatically identified as the region of interest. The identification was based upon the density gradient to the adjacent cortical bone. The starting point was defined as the middle of the parasymphyseal corticocancellous transition zone on the axial slice showing the parasymphyseal superior pubic ramus in its maximum anteroposterior width. The end point was defined as the middle of the periarticular corticocancellous transition zone on the axial slice showing the quadrilateral plate as a thin cortical plate. The following parameters were automatically obtained on both sides: length of the center line, volume of the superior pubic ramus between the starting point and end point, minimum, maximum and mean diameter perpendicular to the center line, and mean cross-sectional area perpendicular to the center line. RESULTS: An automated analysis without manual adjustments was successful in 207 patients (82.8%). The center line showed a significantly greater length in female patients (67.6 mm vs 65.0 mm). The volume was greater in male patients (21.8 cm(3) vs 19.4 cm(3)). The intersite reliability was high with a mean difference between the left and right sides of between 0.1% (cross-sectional area) and 2.3% (volume). CONCLUSIONS: The method presented allows for an automated volumetric analysis of a corticocancellous bone using CT data. The method is intended to provide preoperative information for the use of intramedullary devices in fracture fixation and percutaneous cement augmentation techniques.

Autologous chondrocyte implantation for joint preservation in patients with early osteoarthritis.

UNLABELLED: Young patients with early osteoarthritis wishing to remain functionally active have limited treatment options. Existing studies examining the use of autologous chondrocyte implantation (ACI) have included patients with early degenerative changes; however, none specifically investigated the outcome of ACI with this challenging problem. We prospectively followed 153 patients (155 knees) for up to 11 years after treatment with ACI for early-stage osteoarthritis. Patient pain and function was assessed using WOMAC, modified Cincinnati, SF-36, Knee Society score, and a satisfaction questionnaire. Mean patient age was 38.3 years. On average, 2.1 defects were treated per knee; the mean defect size was 4.9 cm2 and total area per knee was 10.4 cm2. Eight percent of joints were considered treatment failures that went on to arthroplasty and the remaining patients experienced 50% to 75% improvement in WOMAC subscales. Our data suggest that ACI in patients with early osteoarthritis results in clinically relevant reductions in pain and improvement in function. At 5 years postoperatively, 92% of patients were functioning well and were able to delay the need for joint replacement. Given the limited number of treatment options for this subset of patients, autologous chondrocyte implantation may offer improved quality of life for young osteoarthritic patients. LEVEL OF EVIDENCE: Level IV, case series. See Guidelines for Authors for a complete description of levels of evidence.

Accuracy of minimally invasive navigated acetabular and iliosacral fracture stabilization using a targeting and noninvasive registration device.

BACKGROUND: To assess the feasibility and accuracy of guide pin (GP) placement using a combined noninvasive patient immobilization and stereotactic targeting system in computer-assisted percutaneous pelvic fracture stabilization. METHODS: A total of 12 patients with negligible dislocated unstable pelvic fractures were enrolled in this study, performed between February 2002 and October 2005. Our original plans included 13 GP placements in the iliosacral area (SF) and 8 in the acetabular (AF) area. Patients were bedded on a noninvasive dual-vacuum immobilization device. Interventions were planned on a navigation system using intraoperatively acquired CT data. Radiodense markers glued to the skin and the immobilization device provided synchronization between virtual data set and real anatomical situation. A stereotactic targeting device was used for stabilization of GP tracking. GP positions were verified intraoperatively by CT, followed by fracture stabilization with cannulated screws. RESULTS: Mean GP placement accuracy according to plan: (1) SF-cohort: 2.8 mm (SD 2.0 mm, range 0.5-9.0 mm) at the bony entry point and 3.8 mm (SD 2.3 mm, range 0.6-9.5 mm) at the target point. (2) AF-cohort: 3.0 mm (SD 0.9 mm, range 1.6-4.9 mm) at the bony entry point and 3.9 mm (SD 1.9 mm, range 1.6-7.5 mm) at the target point. GP placement succeeded optimally in 11 out of 13 cases in the SF-cohort, and 6 out of 8 cases in the AF-cohort. The individual average dose-length product (DLP) per successful finished procedure was 1,576 mGy x cm (SD 812 mGy x cm, range 561-2,739 mGy x cm). CONCLUSION: Our findings substantiate application of the noninvasive patient immobilization and stereotactic targeting system as effective in computer-assited percutaneous stabilization of sacral bone fractures/SI joint disruptions and coronally oriented acetabular dome fractures. We recommend according to the ALARA (as low as reasonable achievable) principle: first, the kV and mAs values have to be reduced. Second, the scanned volume has to be strictly limited to the area of interest. Third, the number of control CTs have to be minimized. Also, the IsoC might be a better choice for implant tracking below 12 cm to reduce the radiation dose to the minimum. We believe that for all high-precise GP placements in the acetabular column area, further improvements in GP guidance (inhibiting pin tip slipping and detecting intraosseous GP deflection) are necessary.

Two-dimensional fluoroscopic navigation in posterior cruciate ligament reconstruction: a preclinical cadaver study.

OBJECTIVES: To assess the feasibility and accuracy of frameless stereotactic two-dimensional fluoroscopy-assisted guide pin (GP) placement in posterior cruciate ligament (PCL) reconstruction in human cadavers. MATERIALS AND METHODS: A total of 13 pins were placed in 7 cadaver specimens, using a fluoroscopic-based navigation technique. The knees were fixed noninvasively on a carbon baseplate. Interventions were planned on intraoperatively acquired perpendicular fluoroscopic images. A stereotactic aiming device was mounted to the carbon baseplate and adjusted according to the planned trajectories. GPs were advanced through the aiming device to the precalculated depth. GP positions were verified by image fusion of the fluoroscopic planning and control data, respectively. Measurements were scored on three occasions by one independent observer. In order to assess interobserver reliability, measurements were scored by two further independent observers on one occasion. RESULTS: The femoral cohort included seven GP placements in seven cadavers. Mean GP placement accuracy according to plan was 1.3 mm (SD 0.9 mm, range 0.3-3.8 mm) at the target point. The recorded femoral angular misalignment of GPs was 1.1 degrees (SD 0.9 degrees , range 0.2 degrees -3.3 degrees ). The tibial cohort included six GP placements in six cadavers. Mean GP placement accuracy according to the plan was 1.8 mm (SD 2.1 mm, range 0.3-9.5 mm). The recorded tibial angular misalignment of GPs was 1.4 degrees (SD 1.1 degrees , range 0.1 degrees -5 degrees ). Navigated GP implantation, as planned, was optimal in six out of seven cases in the femoral cohort and in four out of six cases in the tibial cohort. CONCLUSION: Our preliminary cadaver study suggests that the use of fluoroscopic-based navigation combined with a stereotactic targeting device may be a helpful tool to improve PCL reconstruction. In addition, this method may also be used for other minimal invasive skeletal interventions.

Minimally invasive transiliac plate osteosynthesis for type C injuries of the pelvic ring: a clinical and radiological follow-up.

OBJECTIVE: To evaluate radiological and functional outcome in patients treated with minimally invasive transiliac plate osteosynthesis for unstable pelvic injuries. DESIGN: Retrospective analysis of a prospective treatment protocol in a consecutive patient series. SETTING: Level 1 trauma center. PATIENTS: Between January 1998 and December 2005, 31 patients with type C injuries of the pelvic ring were treated with minimally invasive transiliac plate osteosynthesis. According to the AO classification, 16 patients had a C1-injury, 9 had a C2 fracture, and 6 patients sustained a C3 injury of the pelvic ring. Anterior-posterior, inlet, and outlet radiographs were obtained preoperatively, immediately postoperatively, and during follow-up. Clinical outcome was determined according to the Hannover pelvic outcome score. INTERVENTION: Posterior plate osteosynthesis for type C injuries of the pelvic ring. MAIN OUTCOME MEASUREMENT: Preoperative and postoperative dislocation of the posterior pelvic ring, loss of reduction, implant failure, implant removal, clinical results of the pelvic injury and general limitations following the trauma. RESULTS: Maximum average dislocation of the posterior pelvic ring was 16.1 mm preoperatively; postoperatively, it was 6.1 mm. A total of 23 patients (74.2%) could be followed up after an average of 20 months (range 7-57 months). Seven patients underwent follow-up treatment at other hospitals closer to their respective residences, whereas 1 patient passed away in the early postoperative phase due to multiorgan failure. Loss of reduction occurred in 2 cases. The clinical outcome regarding the pelvis was very good in 8 cases, good in 9 cases, fair in 4 cases, and poor in 2 cases. Social reintegration according to the Hannover pelvic outcome score was complete in 9 cases, poor in 10 cases, and incomplete in 10 cases. CONCLUSION: Posterior plate osteosynthesis is a sufficiently stable method for the treatment of unstable pelvic ring injuries with a low risk of iatrogenic nervous tissue and vascular lesions. The disadvantages are limited reduction possibilities, the necessity of bilateral bridging of the sacroiliac joint in a unilateral injury, as well as a higher rate of symptomatic hardware.

Stabilization of the posterior pelvic ring with a slide-insertion plate.

OBJECTIVE: Minimally invasive stabilization of the posterior pelvic ring in type C injuries. INDICATIONS: Unstable type C injuries of the pelvic ring, uni- or bilateral. - Transsymphyseal-transsacral instability. - Transpubic-transsacral instability. - Transsymphyseal-transsacroiliac instability. - Transpubic-transsacroiliac instability. CONTRAINDICATIONS: Fractures in childhood. Comminuted fractures of the ilium. Patients with skin and soft tissues in a poor condition and/or local infection. Sacral fractures with a neurologic deficit are not a contraindication because they can be decompressed by distraction and stabilized in a neutral position by plate fixation. SURGICAL TECHNIQUE: Nut-shaped osteotomy of the posterior superior iliac spine bilaterally through two short, vertical skin incisions. Tunneling through the muscles of the back to the opposite side. Length measurement for a 4.5-mm pelvic reconstruction plate. The plate is bent by about 70 degrees over the fourth lateral hole. Slide-insertion of the plate and bending of the free plate end for close fit. Cancellous bone screws are inserted into the plate holes. Refixation of the osteotomized bone fragments over the plate with small-fragment, cancellous bone screws. RESULTS: 34 patients with an average age of 42.6 years were treated according to the described method from 1998 to 2005; 18 were polytraumatized. The anterior pelvic ring was also stabilized by surgery in 28 patients for eleven of whom it was the first intervention in a two-stage procedure. 25 patients were available for clinical and radiologic follow-up at 17 months, on average. The plain radiographs after 1 year showed a very good outcome in 16 patients (maximal displacement of the posterior pelvic ring < 5 mm) and a good outcome in eight patients (displacement of 5-10 mm). In two patients there was loss of reduction in the 1st postoperative year despite a very good reduction result immediately postoperatively (dislocation < 5 mm), whereby the dislocation for one patient was < 10 mm on the final radiograph and 19 mm for the other. One patient presented with a late infection 11 weeks postoperatively that healed after implant removal and wound debridement. In two other patients, prominent screw heads, which were used for refixation of the osteotomized posterior superior iliac spine, had to be removed under local anesthesia in the 10th postoperative week. The further course for these two patients was uneventful. In one patient the implants were retrieved in the 5th postoperative month because the patient complained of internal hot and cold sensations although the soft tissue was not irritated. The plates were removed in six other cases after the fracture/instability had healed, i. e., after 9-12 months, on average; in all other cases the implants were left in situ.

Computer-assisted minimally invasive treatment of osteochondrosis dissecans of the talus.

OBJECTIVE: Revascularization of areas of necrosis in the talus and stimulation of bone regeneration whilst protecting the talar hyaline cartilage using computer-assisted minimally invasive drilling or retrograde cancellous bone relining of the osteochondrotic zone. INDICATIONS: Osteochondrosis dissecans of the talus, Berndt & Harty stages I-III. CONTRAINDICATIONS: Osteochondrosis dissecans of the talus, Berndt & Harty stage IV. General contraindications such as poor skin and soft-tissue conditions or poor general condition. SURGICAL TECHNIQUE: Before the operation: fitting a removable cast for the ankle (ankle fixation cast), then computed tomography of the ankle with the ankle fixation cast fitted. Planning the site of the central Kirschner wire in the talus using a navigation system in the laboratory. Adjusting and locking the aiming device. Intraoperative procedures: fitting the sterilized ankle fixation cast. Retrograde placement of the 2.4-mm Kirschner wire through the locked aiming device. Check on the position of the Kirschner wire using an image intensifier. Arthroscopy of the ankle; further parallel holes may then be drilled depending on the findings or retrograde cancellous bone grafting may be performed by harvesting cancellous bone from the calcaneus. POSTOPERATIVE MANAGEMENT: For retrograde drilling/parallel drilling: 1 week of partial weight bearing at 30 kg. For retrograde cancellous bone grafting: 4 weeks of partial weight bearing at 15 kg, then 2 more weeks of partial weight bearing at 30 kg. Physiotherapy. RESULTS: From December 1999 to January 2005, 41 patients with osteochondrosis dissecans of the talus were selected for computer-assisted treatment by retrograde drilling or retrograde cancellous bone grafting. In 39 of the 41 patients, the osteochondral lesion-as verified by postoperative magnetic resonance imaging (MRI)-was accessed, i.e., the drilled hole led to the lesion. In two cases, irreparable flaws in the materials were discovered intraoperatively, so that the above method was only performed on 39 patients. The 1-year results for the first 15 patients treated with retrograde drilling/parallel drilling and concomitant ankle arthroscopy without retrograde cancellous bone graft are presented here based on the follow-up MRI (position of drill hole, assessment of vitality of the area of osteochondritis) and a clinical score. The four women and eleven men were, on average, 34.1 years old (14-55 years). In the radiologic comparison of the pre- and postoperative stages of the osteochondritis dissecans, 46.7% of patients showed an improvement in the Berndt & Harty stage. 40.0% showed the same osteochondrosis dissecans stage in the postoperative MRI, and in 13.3% it deteriorated by one grade. In the clinical follow-up examination, the AOFAS Score averaged 88.9 points.

Practical execution of defect preparation prior to surgical cartilage intervention: results from a representative meeting survey among experts.

During a specialised orthopedic meeting held on 'the state of the art in cartilage defect repair', all previously fully-registered participants were requested to participate in an electronic survey by the use of a moderator-presented "Power Point Presentation-based" 9-item questionnaire. The aim of this survey was to assess indication, approach, and treatment execution of cartilage defect debridement prior to planned microfracture (MFX) or autologous chondrocyte implantation (ACI). All participants completed the questionnaire (n = 146) resulting in a return rate of 100 %. An uncertainty exists as to whether the removal of the calcifying layer prior to cartilage repair must be carried out or not. The same was true for the acceptability of subchondral bleeding prior to microfracturing and its handling prior to autologous chondrocyte implantation. There is a degree of unanimity among experts regarding the management of osteophytes and bone marrow edema. In a homogenous society collective of consultants that frequently deal with cartilage defective pathologies, there still remain a significant heterogeneity in selected topics of defect debridement.

Increased failure rate of autologous chondrocyte implantation after previous treatment with marrow stimulation techniques.

BACKGROUND: Marrow stimulation techniques such as drilling or microfracture are first-line treatment options for symptomatic cartilage defects. Common knowledge holds that these treatments do not compromise subsequent cartilage repair procedures with autologous chondrocyte implantation. HYPOTHESIS: Cartilage defects pretreated with marrow stimulation techniques will have an increased failure rate. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: The first 321 consecutive patients treated at one institution with autologous chondrocyte implantation for full-thickness cartilage defects that reached more than 2 years of follow-up were evaluated by prospectively collected data. Patients were grouped based on whether they had undergone prior treatment with a marrow stimulation technique. Outcomes were classified as complete failure if more than 25% of a grafted defect area had to be removed in later procedures because of persistent symptoms. RESULTS: There were 522 defects in 321 patients (325 joints) treated with autologous chondrocyte implantation. On average, there were 1.7 lesions per patient. Of these joints, 111 had previously undergone surgery that penetrated the subchondral bone; 214 joints had no prior treatment that affected the subchondral bone and served as controls. Within the marrow stimulation group, there were 29 (26%) failures, compared with 17 (8%) failures in the control group. CONCLUSION: Defects that had prior treatment affecting the subchondral bone failed at a rate 3 times that of nontreated defects. The failure rates for drilling (28%), abrasion arthroplasty (27%), and microfracture (20%) were not significantly different, possibly because of the lower number of microfracture patients in this cohort (25 of 110 marrow-stimulation procedures). The data demonstrate that marrow stimulation techniques have a strong negative effect on subsequent cartilage repair with autologous chondrocyte implantation and therefore should be used judiciously in larger cartilage defects that could require future treatment with autologous chondrocyte implantation.

Biochemical, biomechanical and histological properties of osteoarthritic porcine knee cartilage: implications for osteochondral transplantation.

INTRODUCTION: Cartilage lesions of the knee joint are frequently observed during arthroscopy and when surgical intervention is required, osteochondral autograft procedures are an established method of treatment. Frequently lesions are located on the medial femoral condyle (MFC), and typical donor locations for osteochondral grafts include the medial and lateral patellar groove. This technique provides good results, even when the quality of cartilage transplanted from an osteoarthritic joint is doubtful. This study characterizes biological, biomechanical and histological properties of cartilage explants from the patellar groove harvested from osteoarthritic joints. MATERIALS AND METHODS: Cylindrical cartilage explants were harvested from the arthritic areas of the MFC as well as normal appearing regions of the medial and lateral patellar groove from porcine joints revealing various grades of osteoarthritis. Matrix synthesis rates were determined, and explants were investigated by mechanical testing and histology. RESULTS: Articular cartilage obtained from the typical donor areas of the medial and lateral patellar groove provided constant enhanced material properties, matrix synthesis rates and histological appearance compared to samples from the arthritic lesions of the MFC, even in joints with end-stage osteoarthritis of the MFC. No significant difference was found between patellar groove cartilage samples harvested from joints with different stages of osteoarthritis. CONCLUSION: Our findings demonstrate that healthy appearing cartilage from the patellar groove does not undergo significant alterations in material properties due to the arthritic milieu present in osteoarthritic joints. Accordingly these locations provide a source of functional tissue for transplant procedures even in joints with end-stage osteoarthritis.

Repair of large chondral defects of the knee with autologous chondrocyte implantation in patients 45 years or older.

BACKGROUND: Autologous chondrocyte implantation (ACI) has become an accepted option for the treatment of chondral defects in carefully selected patients. Current recommendations limit this procedure to younger patients, as insufficient data are available to conclusively evaluate outcomes in patients older than 45 years. HYPOTHESIS: Cartilage repair with ACI in patients older than 45 years results in substantially different outcomes than those previously reported for younger age groups. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: This prospective cohort study reviewed patients > or =45 years of age at the time of treatment with ACI. The clinical evaluation included a patient satisfaction questionnaire and four validated rating scales: Short Form-36, Modified Cincinnati Rating Scale, WOMAC (Western Ontario and McMaster Universities) Osteoarthritis Index, and the Knee Society Score. RESULTS: A total of 56 patients > or =45 years of age were treated with ACI. The average patient age at index surgery was 48.6 years (range, 45-60 years). The minimum follow-up was 2 years (range, 2-11 years; mean, 4.7 years). The cohort included 36 men and 20 women. The mean transplant size was 4.7 cm(2) per defect (range, 1-15.0 cm(2)) and 9.8 cm(2) per knee (range, 2.5-31.6 cm(2)). Twenty-eight patients (50%) underwent concomitant osteotomies to address malalignment. There were 8 failures (14%): 6 of 15 (40%) in patients receiving workers' compensation (WC) and 2 of 41 (4.9%) in non-WC patients. Additional arthroscopic surgical procedures were required in 24 patients (43%) for periosteal-related problems and adhesions; 88% of these patients experienced lasting improvement. At their latest available follow-up, 72% of patients rated themselves as good or excellent, 78% felt improved, and 81% would again choose ACI as a treatment option. CONCLUSION: Our results showed a failure rate of ACI in older patients that is comparable with rates reported in younger patient groups. The procedure is associated with a substantial rate of reoperations, mostly for the arthroscopic treatment of graft hypertrophy, similar to that in younger patients.

Improved accuracy of component alignment with the implementation of image-free navigation in total knee arthroplasty.

Accuracy of implant positioning and reconstruction of the mechanical leg axis are major requirements for achieving good long-term results in total knee arthroplasty (TKA). The purpose of the present study was to determine whether image-free computer navigation technology has the potential to improve the accuracy of component alignment in TKA cohorts of experienced surgeons immediately and constantly. One hundred patients with primary arthritis of the knee underwent the unilateral total knee arthroplasty. The cohort of 50 TKAs implanted with conventional instrumentation was directly followed by the cohort of the very first 50 computer-assisted TKAs. All surgeries were performed by two senior surgeons. All patients received the Zimmer NexGen total knee prosthesis (Zimmer Inc., Warsaw, IN, USA). There was no variability regarding surgeons or surgical technique, except for the use of the navigation system (StealthStation) Treon plus Medtronic Inc., Minnesota, MI, USA). Accuracy of implant positioning was measured on postoperative long-leg standing radiographs and standard lateral X-rays with regard to the valgus angle and the coronal and sagittal component angles. In addition, preoperative deformities of the mechanical leg axis, tourniquet time, age, and gender were correlated. Statistical analyses were performed using the SPSS 15.0 (SPSS Inc., Chicago, IL, USA) software package. Independent t-tests were used, with significance set at P < 0.05 (two-tailed) to compare differences in mean angular values and frontal mechanical alignment between the two cohorts. To compute the rate of optimally implanted prostheses between the two groups we used the chi(2) test. The average postoperative radiological frontal mechanical alignment was 1.88 degrees of varus (range 6.1 degrees of valgus-10.1 degrees of varus; SD 3.68 degrees ) in the conventional cohort and 0.28 degrees of varus (range 3.7 degrees -6.0 degrees of varus; SD 1.97 degrees ) in the navigated cohort. Including all criteria for optimal implant alignment, 16 cases (32%) in the conventional cohort and 31 cases (62%) in the navigated cohort have been implanted optimally. The average difference in tourniquet time was modest with additional 12.9 min in the navigated cohort compared to the conventional cohort. Our findings suggest that the experienced knee surgeons can improve immediately and constantly the accuracy of component orientation using an image-free computer-assisted navigation system in TKA. The computer-assisted technology has shown to be easy to use, safe, and efficient in routine knee replacement surgery. We believe that navigation is a key technology for various current and future surgical alignment topics and minimal-invasive lower limb surgery.

The immediate effect of navigation on implant accuracy in primary mini-invasive unicompartmental knee arthroplasty.

The success of unicompartmental knee arthroplasty (UKA) is highly dependent on the accuracy of the component alignment. Objective of the present study was to evaluate the immediate effect of image-free computer navigation technology on implant accuracy in primary mini-invasive UKA. This study reviews 40 patients with primary isolated arthritis of the medial compartment of the knee that underwent unicompartmental knee arthroplasty through a minimally invasive approach. A cohort of the 20 most recent consecutive UKA's implanted with standard instrumentation was followed by a cohort of the very first 20 consecutive cases after conversion to the navigated technique. There was no variability regarding implant (Oxford meniscal unicompartmental knee system--Biomet Orthopedics, Inc., Warsaw, Indiana 46580, USA), surgeons and surgical technique, except for the use of the navigation system (Treon plus--Medtronic Inc., Minnesota, MI, USA). The axis alignment and accuracy of implant positioning was measured on postoperative long-leg standing radiographs and standard lateral X-rays with regard to the valgus angle and the coronal and sagittal component angle. In addition, preoperative deformities of the mechanical leg axis, tourniquet time, age, gender, and body mass index were correlated. Statistical analyses were performed using the SPSS 14.0 (SPSS Inc., Chicago, IL, USA) software package. Optimal implant alignment including all measurements in the desired angular range was significantly (P=0.041) higher in the navigated cohort. Navigation eliminated outliers in the frontal mechanical alignment and coronal orientation of the femoral component totally and significantly (P<0.02). Furthermore, navigation narrowed the range of outliers in all other planes of component orientation. There were no statistically significant differences in the mean numerical values between the cohorts, except for the frontal mechanical alignment (P<0.009) and coronal tibial alignment (P<0.037). The average tourniquet time was increased by 10.95 min in the navigated cohort. Our results indicate that navigation immediately improves accuracy of bone cuts and reduces the number of outliers with implementation in UKA.

Stereotactic CT-guided percutaneous stabilization of posterior pelvic ring fractures: a preclinical cadaver study.

PURPOSE: To determine the accuracy of frameless stereotactic computed tomographic (CT)-guided wire placement for percutaneous fixation of posterior pelvic ring fractures in human cadavers. MATERIALS AND METHODS: Four intact human cadavers were fixated in a double-vacuum immobilization system. A 2.5-mm helical CT dataset was obtained and transferred to the three-dimensional (3D) navigation system. In every specimen, two paths on each side (total number, 16) were defined on multiplanar reconstructions of the 3D CT datasets, simulating fixation of the iliosacral joint. An aiming device was adjusted according to the plan, and a 2.5-mm pin was advanced through the aiming device to the precalculated target point. To determine the accuracy of pin placement, a control CT scan was co-registered to the planning CT scan (with the planned trajectories). The distance between the planned and achieved positions of the pins (3D accuracy) was calculated in millimeters. RESULTS: The mean 3D accuracy was 1.84 mm +/- 0.9 (standard deviation) at the bone entrance point and 2.5 mm +/- 1.2 at the target, as determined with image fusion between the planning CT scan and the control CT scan with the pins in place. CONCLUSIONS: The described technique enables accurate placement of pins in the pelvis and may be useful for percutaneous orthopedic procedures.