Time-Resolved Quantification of Patellofemoral Cartilage Deformation in Response to Loading and Unloading via Dynamic MRI With Prospective Motion Correction.

BACKGROUND: In vivo cartilage deformation has been studied by static magnetic resonance imaging (MRI) with in situ loading, but knowledge about strain dynamics after load onset and release is scarce. PURPOSE: To measure the dynamics of patellofemoral cartilage deformation and recovery in response to in situ loading and unloading by using MRI with prospective motion correction. STUDY TYPE: Prospective. SUBJECTS: Ten healthy male volunteers (age: [31.4 ± 3.2] years). FIELD STRENGTH/SEQUENCE: T1-weighted RF-spoiled 2D gradient-echo sequence with a golden angle radial acquisition scheme, augmented with prospective motion correction, at 3 T. ASSESSMENT: In situ knee loading was realized with a flexion angle of approximately 40° using an MR-compatible pneumatic loading device. The loading paradigm consisted of 2 minutes of unloaded baseline followed by a 5-minute loading bout with 50% body weight and an unloading period of 38 minutes. The cartilage strain was assessed as the mean distance between patellar and femoral bone-cartilage interfaces as a percentage of the initial (pre-load) distance. STATISTICAL TESTS: Wilcoxon signed-rank tests (significance level: P < 0.05), Pearson correlation coefficient (r). RESULTS: The cartilage compression and recovery behavior was characterized by a viscoelastic response. The elastic compression ([-12.5 ± 3.1]%) was significantly larger than the viscous compression ([-7.6 ± 1.5]%) and the elastic recovery ([10.5 ± 2.1]%) was significantly larger than the viscous recovery ([6.1 ± 1.8]%). There was a significant residual offset strain ([-3.6 ± 2.3]%) across the cohort. A significant negative correlation between elastic compression and elastic recovery was observed (r = -0.75). DATA CONCLUSION: The in vivo cartilage compression and recovery time course in response to loading was successfully measured via dynamic MRI with prospective motion correction. The clinical relevance of the strain characteristics needs to be assessed in larger subject and patient cohorts. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 1.

Interobserver reliability is higher for assessments with 3D software-generated models than with conventional MRI images in the classification of trochlear dysplasia.

PURPOSE: Trochlear dysplasia is a significant risk factor for patellofemoral instability. The severity of trochlear dysplasia is commonly evaluated based on the Dejour classification in axial MRI slices. However, this often leads to heterogeneous assessments. A software to generate MRI-based 3D models of the knee was developed to ensure more standardized visualization of knee structures. The purpose of this study was to assess the intra- and interobserver agreements of 2D axial MRI slices and an MRI-based 3D software generated model in classification of trochlear dysplasia as described by Dejour. METHODS: Four investigators independently assessed 38 axial MRI scans for trochlear dysplasia. Analysis was made according to Dejour's 4 grade classification as well as differentiating between 2 grades: low-grade (types A + B) and high-grade trochlear dysplasia (types C + D). Assessments were repeated following a one-week interval. The inter- and intraobserver agreement was determined using Cohen's kappa (κ) and Fleiss kappa statistic (κ). In addition, the proportion of observed agreement (po) was calculated for assessment of intraobserver agreement. RESULTS: The assessment of the intraobserver reliability with regard to the Dejour-classification showed moderate agreement values both in the 2D (κ = 0.59 ± 0.08 SD) and in the 3D analysis (κ = 0.57 ± 0.08 SD). Considering the 2-grade classification, the 2D (κ = 0.62 ± 0.12 SD) and 3D analysis (κ = 0.61 ± 0.19 SD) each showed good intraobserver matches. The analysis of the interobserver reliability also showed moderate agreement values with differences in the subgroups (2D vs. 3D). The 2D evaluation showed correspondences of κ = 0.48 (Dejour) and κ = 0.46 (high / low). In the assessment based on the 3D models, correspondence values of κ = 0.53 (Dejour) and κ = 0.59 (high / low) were documented. CONCLUSION: Overall, moderate-to-good agreement values were found in all groups. The analysis of the intraobserver reliability showed no relevant differences between 2 and 3D representation, but better agreement values were found in the 2-degree classification. In the analysis of interobserver reliability, better agreement values were found in the 3D compared to the 2D representation. The clinical relevance of this study lies in the superiority of the 3D representation in the assessment of trochlear dysplasia, which is relevant for future analytical procedures as well as surgical planning. LEVEL OF EVIDENCE: Level II.

Arthroscopic Bankart repair with an individualized capsular shift restores physiological capsular volume in patients with anterior shoulder instability.

PURPOSE: Capsular volume reduction in the context of anterior arthroscopic shoulder stabilization represents an important but uncontrolled parameter. The aim of this study was to analyse capsular volume reduction by arthroscopic Bankart repair with an individualized capsular shift in patients with and without ligamentous hyperlaxity compared to a control group. METHODS: In the context of a prospective controlled study, intraoperative capsular volume measurements were performed in 32 patients with anterior shoulder instability before and after arthroscopic Bankart repair with an individualized capsular shift. The results were compared to those of a control group of 50 patients without instability. Physiological shoulder joint volumes were calculated and correlated with biometric parameters (sex, age, height, weight and BMI). RESULTS: Patients with anterior shoulder instability showed a mean preinterventional capsular volume of 35.6 ± 10.6 mL, which was found to be significantly reduced to 19.3 ± 5.4 mL following arthroscopic Bankart repair with an individualized capsular shift (relative capsular volume reduction: 45.9 ± 21.9%; P < 0.01). Pre-interventional volumes were significantly greater in hyperlax than in non-hyperlax patients, while post-interventional volumes did not differ significantly. The average shoulder joint volume of the control group was 21.1 ± 7.0 mL, which was significantly correlated with sex, height and weight (P < 0.01). Postinterventional capsular volumes did not significantly differ from those of the controls (n.s.). CONCLUSION: Arthroscopic Bankart repair with an individualized capsular shift enabled the restoration of physiological capsular volume conditions in hyperlax and non-hyperlax patients with anterior shoulder instability. Current findings allow for individual adjustment and intraoperative control of capsular volume reduction to avoid over- or under correction of the shoulder joint volume. Future clinical studies should evaluate, whether individualized approaches to arthroscopic shoulder stabilization are associated with superior clinical outcome.

Increased external tibial torsion is an infratuberositary deformity and is not correlated with a lateralized position of the tibial tuberosity.

PURPOSE: To perform a segmental analysis of tibial torsion in patients, with normal and increased external tibial torsion, suffering from chronic patellofemoral instability (PFI) and to investigate a possible correlation between tibial torsion and the position of the tibial tuberosity. METHODS: Patients with chronic PFI who underwent torsional analysis of the lower limb using a standardized hip-knee-ankle MRI between 2016 and 2018 were included. For segmental analysis of tibial torsion, three axial levels were defined which divided the tibia into two segments: a distal, infratuberositary segment and a proximal, supratuberositary segment. Torsion was measured for the entire tibia (total tibial torsion, TTT), the proximal segment (proximal tibial torsion, PTT), and the distal segment (distal tibial torsion, DTT). Based on TTT, patients were assigned to one of two groups: Normal TTT (< 35°) or increased external TTT (> 35°). Position of the tibial tuberosity was assessed on conventional MRI scans by measuring the tibial tuberosity-trochlea groove (TT-TG) and the tibial tuberosity-posterior cruciate ligament (TT-PCL) distances. RESULTS: Ninety-one patients (24 ± 6 years; 78% female) were included. Mean external TTT was 29.6° ± 9.1° and 24 patients (26%) had increased external TTT. Compared to patients with normal TTT, patients with increased external TTT demonstrated significantly higher values for DTT (38° ± 8° vs. 52° ± 9°; p < 0.001), whereas no difference was found for PTT ( - 13° ± 6° vs. - 12° ± 6°; n.s.). Furthermore, a significant correlation was found between TTT and DTT (p < 0.001), whereas no correlation was found between TTT and PTT (n.s). With regard to TT-TG and TT-PCL distances, no significant differences were observed between the two groups (TT-TG: 15 ± 6 vs. 14 ± 4 mm, n.s.; TT-PCL: 22 ± 4 vs. 21 ± 5 mm, n.s.) and no correlation was found with TTT, DTT, or PTT (n.s.). CONCLUSION: In patients with chronic PFI, increased external TTT of greater than 35° is an infratuberositary deformity and does not correlate with a lateralized position of the tibial tuberosity. LEVEL OF EVIDENCE: Level III.

[Cartilage repair procedures for early osteoarthritis]. / Stellenwert der chirurgischen Knorpeltherapie bei Früharthrose.

BACKGROUND: Commonly used cartilage repair procedures have been established for focal cartilage lesions; however, degenerative lesions with accompanying changes of other intraarticular structures are much more common in clinical practice. This stage, in which classic radiological signs of osteoarthritis are absent, is called early osteoarthritis and is characterized by impaired joint homeostasis with biomechanical and biochemical changes that can have a negative effect on regenerative cartilage therapy procedures. INDICATION: Cartilage repair procedures are indicated for symptomatic focal early osteoarthritis, defined as cartilage degeneration ICRS grades I or II around a focal cartilage defect ICRS grades III or IV. In more advanced osteoarthritis with significant narrowing of the joint space, cartilage repair procedures are generally contraindicated. THERAPY: The most studied cartilage repair procedure for early osteoarthritis is autologous chondrocyte implantation, which has shown acceptable results in case series, although higher failure rates are to be expected compared to focal, traumatic cartilage lesions. The use of bone marrow-stimulating techniques seems to be limited in early osteoarthritis and should only be used in cases of lesion < 2 cm2 and very little surrounding cartilage degeneration. Concomitant surgical procedures, especially unloading osteotomies, are very important.

[Current treatment standard for patella fractures in Germany]. / Aktueller Versorgungsstandard von Patellafrakturen in Deutschland.

BACKGROUND: The treatment of patella fractures is technically demanding. Although the radiological results are mostly satisfactory, this often does not correspond to the subjective assessment of the patients. The classical treatment with tension band wiring with K­wires has several complications. Fixed-angle plate osteosynthesis seems to be biomechanically advantageous. OBJECTIVE: Who is treating patella fractures in Germany? What is the current standard of treatment? Have modern forms of osteosynthesis become established? What are the most important complications? MATERIAL AND METHODS: The members of the German Society for Orthopedics and Trauma Surgery and the German Knee Society were asked to participate in an online survey. RESULTS: A total of 511 completed questionnaires were evaluated. Most of the respondents are specialized in trauma surgery (51.5%), have many years of professional experience and work in trauma centers. Of the surgeons 50% treat ≤5 patella fractures annually. In almost 40% of the cases preoperative imaging is supplemented by computed tomography. The classical tension band wiring with K­wires is still the preferred form of osteosynthesis for all types of fractures (transverse fractures 52%, comminuted fractures 40%). In the case of comminuted fractures 30% of the surgeons choose fixed-angle plate osteosynthesis. If the inferior pole is involved a McLaughlin cerclage is used for additional protection in 60% of the cases. DISCUSSION: The standard of care for patella fractures in Germany largely corresponds to the updated S2e guidelines. Tension band wiring is still the treatment of choice. Further (long-term) clinical studies are needed to verify the advantages of fixed-angle plates.

The acromioclavicular ligament shows an early and dynamic healing response following acute traumatic rupture.

PURPOSE: Symptomatic horizontal instability is clinically relevant following acute acromioclavicular joint dislocations. However, the intrinsic healing response is poorly understood. The present study sought to investigate time-dependent healing responses of the human acromioclavicular ligament following acute traumatic rupture. METHODS: Biopsies of the acromioclavicular ligament were obtained from patients undergoing surgical treatment for acute acromioclavicular joint dislocations. Specimens were stratified by time between trauma and surgery: group 1, 0-7 days (n = 5); group 2, 8-14 days (n = 6); and group 3, 15-21 days (n = 4). Time-dependent changes in cellularity, collagen (type 1 and 3) concentration, and histomorphological appearance were evaluated for the rupture and intact zone of the acromioclavicular ligament. RESULTS: Group 1 was characterized by cellular activation and early inflammatory response. The rupture zone exhibited a significantly higher count of CD68-positive cells than the intact zone (15.2 vs 7.4; P ≤ 0.05). Consistently, synovialization of the rupture end was observed. Within the second week, the rupture zone was subject to proliferation showing more fibroblast-like cells than the intact zone (66.8 vs 43.8; P ≤ 0.05) and a peak of collagen type 3 expression (group 1: 2.2 ± 0.38, group 2: 3.2 ± 0.18, group 3: 2.8 ± 0.57; P ≤ 0.05). Signs of consolidation and early remodeling were seen in the third week. CONCLUSIONS: The acromioclavicular ligament exhibits early and dynamic healing responses following acute traumatic rupture. Our histological findings suggest that surgical treatment of acute ACJ dislocations should be performed as early as possible within a timeframe of 1 week after trauma to exploit the utmost biological healing potential. Prospective clinical studies are warranted to investigate whether early surgical treatment of ACJ dislocations translates into clinical benefits.

Fluoroscopic guided tunnel placement during medial patellofemoral ligament reconstruction is not accurate in patients with severe trochlear dysplasia.

PURPOSE: Accurate femoral tunnel placement is of great importance during medial patellofemoral ligament (MPFL) reconstruction. Purpose of the present study was to investigate the influence of trochlear dysplasia on the accuracy of fluoroscopic guided femoral tunnel placement. METHODS: CT-Scans of 30 knees (five with regular shaped trochlea, 10 with a Type A and five each with a Type B, C, or D trochlear dysplasia) were imported into the image analysis platform MeVisLab. A 3D Bone Volume Rendering (VR) and a virtual lateral radiograph was created. The anatomic femoral MPFL insertion was identified on the 3D VR. On virtual lateral radiographs, the MPFL insertion was identified based on landmarks described by Schöttle et al. using three different perspectives: Best possible overlap of the femoral condyles (BC) and a tangent along posterior border of the posterior femoral cortex (pBC); a tangent along the anterior border of the posterior cortex (aBC); and best possible overlap of the distal part of the posterior femoral cortex (BF). Distances between the anatomic attachment and radiographically obtained insertions were measured on the 3D VR and compared according to the type of trochlear dysplasia. RESULTS: Significantly lower accuracy of fluoroscopy guided tunnel placement in MPFL reconstruction was found in knees with Type C and D dysplasia. This effect was observed irrespectively from the radiologic perspective (pBC, aBC, and FC). In the pBC view (highest accuracy), the mean distance from the centre of the anatomic MPFL attachment to the radiographically defined location was 4.3 mm in knees without trochlear dysplasia and increased to 4.8 mm in knees with Type A dysplasia, 3.8 mm in knees with Type B dysplasia, 6.7 mm (p < 0.001) in knees with Type C dysplasia, and 7.3 mm (p < 0.001) in knees with Type D dysplasia. CONCLUSION: Radiographic landmark-based femoral tunnel placement in the pBC view provides highest accuracy in knees with a normal shaped trochlea or low grade trochlear dysplasia. In patients with severe dysplasia, fluoroscopy guided tunnel placement has a low accuracy, exceeding a critical threshold of 5 mm distance to the anatomic MPFL insertion irrespective of the radiographic perspective. In these patients, utilization of anatomic landmarks may be beneficial. LEVEL OF EVIDENCE: IV.

Quantification of patellofemoral cartilage deformation and contact area changes in response to static loading via high-resolution MRI with prospective motion correction.

BACKGROUND: Higher-resolution MRI of the patellofemoral cartilage under loading is hampered by subject motion since knee flexion is required during the scan. PURPOSE: To demonstrate robust quantification of cartilage compression and contact area changes in response to in situ loading by means of MRI with prospective motion correction and regularized image postprocessing. STUDY TYPE: Cohort study. SUBJECTS: Fifteen healthy male subjects. FIELD STRENGTH: 3 T. SEQUENCE: Spoiled 3D gradient-echo sequence augmented with prospective motion correction based on optical tracking. Measurements were performed with three different loads (0/200/400 N). ASSESSMENT: Bone and cartilage segmentation was performed manually and regularized with a deep-learning approach. Average patellar and femoral cartilage thickness and contact area were calculated for the three loading situations. Reproducibility was assessed via repeated measurements in one subject. STATISTICAL TESTS: Comparison of the three loading situations was performed by Wilcoxon signed-rank tests. RESULTS: Regularization using a deep convolutional neural network reduced the variance of the quantified relative load-induced changes of cartilage thickness and contact area compared to purely manual segmentation (average reduction of standard deviation by ∼50%) and repeated measurements performed on the same subject demonstrated high reproducibility of the method. For the three loading situations (0/200/400 N), the patellofemoral cartilage contact area as well as the mean patellar and femoral cartilage thickness were significantly different from each other (P < 0.05). While the patellofemoral cartilage contact area increased under loading (by 14.5/19.0% for loads of 200/400 N), patellar and femoral cartilage thickness exhibited a load-dependent thickness decrease (patella: -4.4/-7.4%, femur: -3.4/-7.1% for loads of 200/400 N). DATA CONCLUSION: MRI with prospective motion correction enables quantitative evaluation of patellofemoral cartilage deformation and contact area changes in response to in situ loading. Regularizing the manual segmentations using a neural network enables robust quantification of the load-induced changes. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:1561-1570.

Modified Lemaire extra-articular stabilisation of the knee for the treatment of anterolateral instability combined with diffuse pigmented villonodular synovitis: a case report.

BACKGROUND: Diffuse pigmented villonodular synovitis (PVNS) of the knee is a rare proliferative joint disease associated with high recurrence rates following surgical treatment. Intra-articular joint instability in conjunction with PVNS implies complex reconstructive strategies due to the destructive nature of the disease. CASE PRESENTATION: Here, we present the case of a young patient with refractory PVNS and a chronic ipsilateral anterior cruciate ligament (ACL) rupture. Clinically, the patient presented with a grade 3 pivot shift phenomenon, indicating anterolateral rotational instability. Usually, PVNS implies a contraindication for ACL reconstruction due to the degenerative and pro-inflammatory joint microenvironment that is induced and maintained by PVNS. Therefore, we have performed a modified Lemaire extra-articular stabilization resulting in significant clinical improvement and subjective joint stability. In the latest follow-up examination at 12 months, the patient reported subjective joint stability and no swelling. In the clinical examination, the patient showed dynamic joint stability during walking. Additionally, the patient presented with grade 0 in pivot-shifting compared to the contralateral knee. The Lachman test exhibited no increased side-to-side difference and a firm endpoint. CONCLUSIONS: Extra-articular anterolateral stabilisation of the knee in patients having anterolateral knee instability combined with PVNS is a safe and efficient surgical treatment option yielding significant clinical improvement as well as subjective joint stability.

Isolated revision meniscal repair - failure rates, clinical outcome, and patient satisfaction.

BACKGROUND: Failure of isolated primary meniscal repair must be expected in approximately 10-25% of cases. Patients requiring revision surgery may benefit from revision meniscal repair, however, the results of this procedure remain underreported. The purpose of this study was therefore to evaluate the outcome and failure rates of isolated revision meniscal repair in patients with re-tears or failed healing after previous meniscal repair in stable knee joints. METHODS: A chart review was performed to identify all patients undergoing revision meniscal repair between 08/2010 and 02/2016. Only patients without concomitant procedures, without ligamentous insufficiency, and a minimum follow-up of 24 months were included. The records of all patients were reviewed to collect patient demographics, injury patterns of the meniscus, and details about primary and revision surgery. Follow-up evaluation included failure rates, clinical outcome scores (Lysholm Score, KOOS Score), sporting activity (Tegner scale), and patient satisfaction. RESULTS: A total of 12 patients with a mean age of 22 ± 5 years were included. The mean time between primary repair and revision repair was 27 ± 21 months. Reasons for failed primary repairs were traumatic re-tears in 10 patients (83%) and failed healing in two patients (17%). The mean follow-up period after revision meniscal repair was 43 (± 23.4) months. Failure of revision meniscal repair occurred in 3 patients (25%). In two of these patients, successful re-revision repair was performed. At final follow-up, the mean Lysholm Score was 95.2 (± 4.2) with a range of 90-100, representing a good to excellent result in all patients. The final assessment of the KOOS subscores also showed good to excellent results. The mean Tegner scale was 6.8 ± 1.8, indicating a relatively high level of sports participation. Ten patients (83%) were either satisfied or very satisfied with the outcome. CONCLUSION: In patients with re-tears or failed healing after previous isolated meniscal repair, revision meniscal repair results in good to excellent knee function, high level of sports participation, and high patient satisfaction. The failure rate is slightly higher compared to isolated primary meniscal repair, but still acceptable. Therefore, revision meniscal repair is worthwhile in selected cases in order to save as much meniscal tissue as possible.

Focal metallic inlay resurfacing prosthesis for the treatment of localized cartilage defects of the femoral condyles: a systematic review of clinical studies.

PURPOSE: To systematically review the results of focal metallic inlay resurfacing prosthesis for the treatment of isolated cartilage defects of the femoral condyles. METHODS: A systematic electronic search of the PubMed database and the Cochrane Library was performed in April 2017 to identify studies that reported clinical or radiographic outcome of focal metallic inlay resurfacing prosthesis for the treatment of isolated cartilage defects of the femoral condyles. Included studies were abstracted regarding study characteristics, patient demographics, prosthetic device and location, indications and contraindications, and outcome measures. Outcome of interest included functional outcome scores, radiographic measures, complications, re-operations, and conversion to arthroplasty. The methodologic quality of the included studies was assessed with the Coleman Methodology Score. RESULTS: Six studies with a total of 186 patients met the inclusion criteria. Five studies were level IV evidence, and one was level III. The methodologic quality of the included studies was good, with a mean Coleman Methodology Score of 78. Two different implants were used: the HemiCAP® (five studies; 66% of study group) and UniCAP® (one study; 34%) implant. The mean age was 46-54 years, and the mean follow-up was 24 months to 7 years. Pre- and post-operative outcome scores were compared in all six studies, and five studies reported significant improvements at the final follow-up for all scores (objective und functional KSS, KOOS, WOMAC, Tegner, HSS Knee and Function score, SF-36 and SF-12 physical component score) except for the SF-36 and SF-12 mental component score. Progression of osteoarthritis was analysed using the Kellgren-Lawrence grading in three studies (30% of study group), with two studies reporting significant progression. The OARSI grading system was analysed in one study with no significant progression. The overall conversion rate to arthroplasty was 22% with considerable differences between the two implants: 9% for HemiCAP® and 47% for UniCAP®. CONCLUSIONS: Focal metallic inlay resurfacing prosthesis seems to be a viable option for a carefully selected group of patients. Significant improvement in knee function and pain was observed in most patients. Uncertainty remains with regard to progression of osteoarthritis because of conflicting results and inconsistent reporting. One out of five patients has to be converted to arthroplasty after an average of 4 years. However, compared to the UniCAP® implant, considerable lower conversion rates were reported for the smaller HemiCAP® implant. LEVEL OF EVIDENCE: Systematic review of level III and IV studies, Level IV.

Arthroscopic patellar release allows timely return to performance in professional and amateur athletes with chronic patellar tendinopathy.

PURPOSE: Return to sports rates in amateur and professional athletes with chronic patellar tendinopathy following arthroscopic patellar release are unpredictable. The present study aims to analyse the effectiveness of arthroscopic patellar release in professional compared to amateur athletes. METHODS: A total of 34 amateur and 20 professional athletes with chronic patellar tendinopathy, refractory to conservative treatment, were studied prospectively and underwent arthroscopic tendon release at the inferior patellar pole. Impact of grouped sports on clinical and functional outcome, subjective patient satisfaction and return to sports rates were assessed. Additionally, preoperative MRI-scans of the knee were evaluated and correlated with clinical outcome. RESULTS: In 40 patients (74.1%) arthroscopic patellar release resulted in complete recovery and return to preinjury exercise levels. Full return to sports was achieved after a median of 3.0 (range 0.5-12.0) months. Functional outcome measures VISA-P (Victorian Institute of sport assessment for patella) and modified Blazina scores improved significantly from pre- to postoperatively (VISA-P: 48.8 vs. 94.0 pts., respectively, p < 0.0001; Blazina: 4.47 vs. 0.5, respectively, p < 0.0001). CONCLUSION: As rapid recovery and timely return to sports are crucial for professional athletes, arthroscopic patellar release should be considered after failed conservative treatment. LEVEL OF EVIDENCE: IV.

Comparative T2 and T1ρ mapping of patellofemoral cartilage under in situ mechanical loading with prospective motion correction.

PURPOSE: To demonstrate improved T2 and T1ρ mapping of patellofemoral cartilage with in situ loading by means of prospective motion correction and to assess load-induced changes in healthy subjects. MATERIALS AND METHODS: Established T2 and T1ρ mapping sequences were augmented with prospective motion correction based on optical tracking. Protocols were optimized for robust imaging of the patellofemoral cartilage at a field strength of 3T. Subjects were positioned in the scanner with knee flexion and in situ loading of the patellofemoral joint was performed with a pneumatic loading device. In a pilot study on a cohort of 10 healthy subjects, load-induced T2 and T1ρ changes were evaluated through measurements with axial loads of 0/20/40 kg. RESULTS: With prospective motion correction and additional lipid saturation, motion artifacts in patellofemoral cartilage magnetic resonance imaging (MRI) with in situ loading could be notably decreased, as demonstrated for T2 mapping. The acquired relaxation maps suggested a T2 /T1ρ decrease in superficial cartilage and a T2 /T1ρ increase in deep cartilage under loading. However, in the quantitative group evaluation of the lateral patellar facet, only T1ρ in superficial cartilage was significantly changed by loading (P ≤ 0.05), while no significant T2 differences for the three loading conditions were observed (P ≥ 0.3). CONCLUSION: Prospective motion correction enables T2 and T1ρ mapping of patellofemoral cartilage with in situ loading and a comparison of the two contrasts in terms of their response to mechanical loading. T1ρ is a more sensitive marker for load-induced patellar cartilage changes than T2 . LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;46:452-460.

Factors influencing treatment success of negative pressure wound therapy in patients with postoperative infections after Osteosynthetic fracture fixation.

BACKGROUND: Negative Pressure Wound Therapy (NPWT) is being increasingly used to treat postoperative infections after osteosynthetic fracture fixation. The aim of the present study was to analyze the influence of epidemiological and microbiological parameters on outcome. METHODS: Infections following operative fracture fixation were registered in a comprehensive Critical Incidence Reporting System and subsequently analyzed retrospectively for characteristics of patients including comorbidity, bacteria, and clinical factors. The influence of the investigated parameters was analyzed using logistic regression models based on data from 106 patients. RESULTS: Staged wound lavage in combination with NPWT allowed implant preservation in 44% and led to successful healing in 73% of patients. Fermentation characteristics, load and behavior after gram staining revealed no statistically significant correlation with either healing or implant preservation. Infecting bacteria were successfully isolated in 87% of patients. 20% of all infections were caused by bacterial combinations. We observed a change in the infecting bacterial species under therapy in 23%. Age, gender, metabolic diseases or comorbidities did not influence the probability of implant preservation or healing. The delayed manifestation of infection (>4 weeks) correlated with a higher risk for implant loss (OR 5.1 [95% CI 1.41-17.92]) as did the presence of bacterial mixture (OR 5.0 [95% CI 1.41-17.92]) and open soft-tissue damage ≥ grade 3 (OR 10.2 [CI 1.88-55.28]). Wounds were less likely to heal in conjunction with high CRP blood levels (>20 mg/l) at the time of discharge (OR 3.6 [95% CI 1.31-10.08]) or following a change of the infecting bacterial species under therapy (OR 3.2 [95% CI, 1.13-8.99]). CONCLUSIONS: These results indicate that the delayed manifestation of infection, high CRP blood levels at discharge, and alterations in the infecting bacterial species under therapy raise the risk of NPWT failure.

Arthroscopic patellar release for treatment of chronic symptomatic patellar tendinopathy: long-term outcome and influential factors in an athletic population.

BACKGROUND: Arthroscopic patellar release (APR) is utilized for minimally invasive surgical treatment of patellar tendinopathy. Evidence regarding long-term success following the procedure is limited. Also, the influence of age and preoperative performance level, are incompletely understood. The aim of this study was to investigate whether APR translates into sustained pain relief over a long-term follow-up in athletes undergoing APR. Furthermore, we analyzed if age influences clinical and functional outcome measures in APR. METHODS: Between 1998 and 2010, 30 competitive and recreational athletes were treated with APR due to chronic refractory patellar tendinopathy. All data were analyzed retrospectively. Demographic data, such as age or level of performance prior to injury were extracted. Clinical as well as functional outcome measures (Swedish Victorian Institute of sport assessment for patella (VISA-P), the modified Blazina score, pain level following exercise, return to sports, and subjective knee function were assessed pre- and postoperatively. RESULTS: In total, 30 athletes were included in this study. At follow-up (8.8 ± 2.82 years), clinical and functional outcome measures such as the mean Blazina score, VISA-P, VAS, and subjective knee function revealed significant improvement compared to before surgery (P < 0.001). The mean time required for return to sports was 4.03 ± 3.18 months. After stratification by age, patients younger than 30 years of age yielded superior outcome in the mean Blazina score and pain level when compared to patients ≥30 years (P = 0.0448). At 8 years of follow-up, patients yielded equivalent clinical and functional outcome scores compared to our previous investigation after four years following APR. CONCLUSION: In summary, APR can be regarded a successful, minimally invasive, and sustained surgical technique for the treatment of patella tendinopathy in athletes. Younger age at surgery may be associated with improved clinical and functional outcome following APR.

Examination of concomitant glenohumeral pathologies in patients treated arthroscopically for calcific tendinitis of the shoulder and implications for routine diagnostic joint exploration.

BACKGROUND: Glenohumeral exploration is routinely performed during arthroscopic removal of rotator cuff calcifications in patients with calcific tendinitis of the shoulder (CTS). However, evidence on the prevalence of intraarticular co-pathologies is lacking and the benefit of glenohumeral exploration remains elusive. The aim of the present study was to assess and quantify intraoperative pathologies during arthroscopic removal of rotator cuff calcifications in order to determine whether standardized diagnostic glenohumeral exploration appears justified in CTS patients. METHODS: One hundred forty five patients undergoing arthroscopic removal of calcific depots (CD) that failed conservative treatment were included in a retrospective cohort study. Radiographic parameters including number/localization of calcifications and acromial types, intraoperative arthroscopic findings such as configuration of glenohumeral ligaments, articular cartilage injuries, and characteristics of calcifications and sonographic parameters (characteristics/localization of calcification) were recorded. RESULTS: One hundred forty five patients were analyzed. All CDs were removed by elimination with a blunt hook probe via "squeeze-and-stir-technique" assessed postoperatively via conventional X-rays. Neither subacromial decompression nor refixation of the rotator cuff were performed in any patient. Prevalence of glenohumeral co-pathologies, such as partial tears of the proximal biceps tendon (2.1%), superior labral tears from anterior to posterior (SLAP) lesions (1.4%), and/or partial rotator cuff tears (0.7%) was low. Most frequently, glenohumeral articular cartilage was either entirely intact (ICRS grade 0 (humeral head/glenoid): 46%/48%) or showed very mild degenerative changes (ICRS grade 1: 30%/26%). Two patients (1.3%) required intraarticular surgical treatment due to a SLAP lesion type III (n = 1) and an intraarticular rupture of CD (n = 1). CONCLUSIONS: Routine diagnostic glenohumeral exploration does not appear beneficial in arthroscopic treatment of CTS due to the low prevalence of intraarticular pathologies which most frequently do not require surgical treatment. Exploration of the glenohumeral joint in arthroscopic removal of CD should only be performed in case of founded suspicion of relevant concomitant intraarticular pathologies.

Prognostic value of MRI in arthroscopic treatment of chronic patellar tendinopathy: a prospective cohort study.

BACKGROUND: To date, prognostic outcome factors for patients undergoing arthroscopic treatment due to chronic patellar tendinopathy (PT) are lacking. The purpose of this study was to investigate whether preoperatively assessed MRI parameters might be of prognostic value for prediction of functional outcome and return to sports in arthroscopic treatment of chronic PT. METHODS: A prospective cohort study was conducted including 30 cases (4 female and 24 male competitive athletes) undergoing arthroscopic patellar release (APR) due to chronic PT. The mean age was 28.2 years (range, 18-49 years) at the time of surgery, and the mean follow-up period was 4.2 years (range, 2.2-10.4 years). Preoperatively assessed MRI parameters included bone marrow edema (BME) of the inferior patellar pole, patellar tendon thickening, infrapatellar fat pad (IFP) edema, and infrapatellar bursitis. Prevalences of preoperative MRI findings were correlated to functional outcome scores in order to determine statistically significant predictors. RESULTS: All athletes regained their preinjury sports levels. Athletes featuring preoperative IFP edema showed significantly inferior modified Blazina score (0.6 ± 0.7 vs. 0.2 ± 0.5), single assessment numeric evaluation (SANE; 86.0 ± 8.8 vs. 94.3 ± 7.5), and Visual Analogue Scale (VAS; 1.0 ± 1.2 vs. 0.3 ± 0.8) compared to subjects without IFP edema (p < 0.05). Return to sports required a mean of 4 ± 3.2 months. On average, patients with IFP edema needed significantly more time to return to sports than subjects without IFP edema (6.5 vs 2.8 months; p < 0.05). The simultaneous presence of BME and IFP edema was associated with significantly inferior outcomes by means of the Victorian Institute of Sport Assessment questionnaire for patients with patellar tendinopathy (VISA-P; 88.1 ± 11.9 vs. 98.6 ± 4.2), SANE (84.3 ± 10.2 vs. 93.1 ± 8.3), and VAS (1.3 ± 1.4 vs. 0.3 ± 0.9) compared to an isolated BME or isolated IFP edema. CONCLUSIONS: This is the first study identifying prognostic outcome factors in arthroscopic treatment of chronic PT. Preoperative IFP edema alone or simultaneous BME and IFP edema on preoperative MRI were associated with inferior functional outcome and delayed return to sports. Knowledge of these predictive factors might improve risk stratification, individualize treatment and postoperative rehabilitation, and contribute to improve clinical outcome. Moreover, current findings offer the potential for novel therapeutic approaches.

Comparative analysis of locking plate versus hook plate osteosynthesis of Neer type IIB lateral clavicle fractures.

INTRODUCTION: Controversy exists on optimal operative treatment of vertically unstable Neer IIB lateral clavicle fractures. Aim of this study was to analyse and compare clinical and radiological results and complications of locking plate osteosynthesis (LPO) versus hook plate osteosynthesis (HPO) with acromioclavicular joint (ACJ) stabilization. The hypothesis was, that HPO would recreate coracoclavicular stability more effectively and potentially lead to a superior outcome. METHODS: This retrospective, observational cohort study included 32 patients (19 HPO, 13 LPO) with a mean age of 44.1 ± 14.2 years at surgery. The mean follow-up period was 54.2 months (range 25.2-111.4 months). Besides standard radiography, bilateral coracoclavicular distances were assessed by means of preoperative and follow-up stress radiographs after implant removal. Clinical outcome measures included the Constant score (CS), the Oxford shoulder score (OSS), the subjective shoulder value (SSV) and the Taft score (TS). RESULTS: Bone union occurred in all but one patient and proved to occur delayed in five patients (15.6%). Radiographical healing required a mean of 4.2 ± 4.0 months irrespective of the type of osteosynthesis. At follow-up, mean coracoclavicular distance was increased by 34% (±36) without significant differences between both groups. HPO patients obtained a significantly lower TS (HPO: 9.5 ± 1.5 points, LPO: 11.1 ± 1.3 points; p = 0.005). Other mean score values did not differ (CS: 90.1 ± 7.4 points, OSS: 43.2 ± 9.2 points, SSV: 91.1 ± 14.7%). Sixteen patients (50.0%) experienced complications. Overall prevalence of complications was significantly higher in the HPO group (p = 0.014). CONCLUSIONS: Both HPO and LPO were equally effective in relation to restoration of vertical stability, overall functional outcome and fracture consolidation in treatment of Neer IIB fractures. Contrary to our hypothesis, HPO was not associated with superior recreation of the coracoclavicular distance. Considerable drawbacks of HPO were an inferior ACJ-specific outcome (Taft-Score) and a higher overall complication rate. Level of evidence IV.