Microfragmented abdominal adipose tissue-derived stem cells from knee osteoarthritis patients aged 29-65 years demonstrate in vitro stemness and low levels of cellular senescence.

Purpose: To investigate the level of cellular senescence in stem cells derived from microfragmented abdominal adipose tissue harvested from patients with knee osteoarthritis (OA). Methods: Stem cells harvested from microfragmented abdominal adipose tissue from 20 patients with knee OA, aged 29-65 years (mean = 49.8, SD = 9.58), were analysed as a function of patient age and compared with control cells exhibiting signs of cellular senescence. Steady-state mRNA levels of a panel of genes associated with senescence were measured by qPCR. Intracellular senescence-associated proteins p16 and p21, and senescence-associated ß-galactosidase activity were measured by flow cytometry. Cellular proliferation was assessed using a 5-ethynyl-2'-deoxyuridine proliferation assay. Stemness was assessed by stem cell surface markers using flow cytometry and the capacity to undergo adipogenic and osteogenic differentiation in vitro. Results: No correlation was found between cellular senescence levels of the microfragmented adipose tissue-derived stem cells and patient age for any of the standard assays used to quantify senescence. The level of cellular senescence was generally low across all senescence-associated assays compared to the positive senescence control. Stemness was verified for all samples. An increased capacity to undergo adipogenic differentiation was shown with increasing patient age (p = 0.02). No effect of patient age was found for osteogenic differentiation. Conclusions: Autologous microfragmented adipose tissue-derived stem cells may be used in clinical trials of knee OA of patients aged 29-65 years, at least until passage 4, as they show stemness potential and negligible senescence in vitro. Level of Evidence: Not applicable.

Adolescents with prior patellar dislocation report affected quality of life and function, as measured using the Banff Patella Instability Instrument, Kujala and EQ-5D-5L index scores.

PURPOSE: We aimed to establish patient-reported outcome measure (PROM) reference data for a cohort of patients with prior patellar dislocation without previous knee surgery. METHODS: All inhabitants of the Faroe Islands aged 15-19 years were sent an online survey via secure email to establish a national cohort. They were asked to answer questions regarding demographics, whether they had prior patellar dislocation and to complete the PROMs: the Banff Patella Instability Instrument (BPII), Kujala, Marx activity and EQ-5D-5L questionnaires. Participants who had undergone knee surgery were excluded. Participants who had prior patellar dislocation underwent radiographic examinations to diagnose trochlear dysplasia. The study included three cohorts: the general population, prior patellar dislocation and prior patellar dislocation and trochlear dysplasia cohorts. RESULTS: Of the 3749 individuals contacted, 1119 completed the survey and responded to at least one PROM. Of these, 102 reported a history of patellar dislocation and 57 of them had trochlear dysplasia. All PROMs, except the Marx score, reflected a worse quality of life and function after patellar dislocation than in the general population cohort; this was most pronounced in the BPII. The percentage of people experiencing problems in EQ-5D-5L dimensions was higher in the patellar dislocation and trochlear dysplasia cohorts than in the general population cohort in all EQ-5D-5L domains, except anxiety/depression. CONCLUSION: Adolescents who had patellar dislocation reported reduced quality of life and function according to the BPII, Kujala and EQ-5D-5L index values, as well as all EQ-5D-5L domains, except for anxiety/depression. However, their activity levels remained high. LEVEL OF EVIDENCE: Level III.

High prevalence of patellar dislocation and trochlear dysplasia in a geographically and genetically isolated society: an observational national cohort study from the Faroese Knee Cohort.

BACKGROUND AND PURPOSE: We aimed to calculate the prevalence of patellar dislocation (PD) and trochlear dysplasia (TD) in a national cohort aged 15-19 years in the Faroe Island. PATIENTS AND METHODS: All inhabitants in the Faroe Islands aged 15-19 years were invited to answer an online survey, including demographics and questions regarding prior PD. Participants with prior PD were invited for radiographs and MRI of both knees to be taken. Trochlear dysplasia was defined as one of the following: Dejour type A-D on radiographs, lateral trochlear inclination angle (LTI) < 11°, or trochlear depth < 3 mm on MRI. RESULTS: 3,749 individuals were contacted, 41 were excluded, and 1,638 (44%) completed the survey. 146 reported a prior PD (the PD cohort) and 100 accepted to participate and have radiographs and MRI taken of both knees (the clinical PD cohort), 76 of whom were diagnosed with TD. The national prevalence of PD was 8.9%. The national prevalence of symptomatic TD was 6.8%. The prevalence of TD in the clinical PD cohort was 76%. TD was bilateral in 78% of TD patients, but only 27% of patients with bilateral TD had PD in both knees. CONCLUSION: The prevalence of PD in the Faroe Islands is found to be very high. The national prevalence of TD and the prevalence of TD in participants with prior PD is high, indicating a potential genetic influence.

Trochlear Shape and Patient-Reported Outcomes After Arthroscopic Deepening Trochleoplasty and Medial Patellofemoral Ligament Reconstruction: A Retrospective Cohort Study Including MRI Assessments of the Trochlear Groove.

Background: Sparse objective data are available documenting changes of trochlear shape after trochleoplasty. Purpose/Hypothesis: The purpose was to investigate whether standardized magnetic resonance imaging (MRI) measurements that characterize trochlear dysplasia (TD) change significantly after arthroscopic deepening trochleoplasty (ADT) combined with medial patellofemoral ligament (MPFL) reconstruction. It was hypothesized that MRI measurements would approximate normal values. Study Design: Case series; Level of evidence, 4. Methods: Patients who underwent ADT between October 2014 and December 2017 were considered for this study. The preoperative inclusion criteria for ADT surgery were patellar instability, a dynamic patellar apprehension sign at 45° of flexion, a lateral trochlear inclination (LTI) angle of <11°, and failed physical therapy. MRI was performed pre- and postoperatively, and standardized MRI measurements were calculated: LTI angle, trochlear depth, trochlear facet asymmetry, cartilage thickness, and trochlear height. The Banff Patella Instability Instrument 2.0 (BPII) score, Knee injury and Osteoarthritis Outcome Score (KOOS), and Kujala score were obtained pre- and postoperatively. Results: A total of 16 knees in 15 patients (12 female and 3 male; median age, 20.9 years; range, 14.1-51.3 years) were evaluated. The mean follow-up time was 63.6 months (range, 23-97 months). The median LTI angle improved from 1.25° (range, -25.1° to 10.6°) preoperatively to 10.7° (range, -17.7° to 25.8°) postoperatively (P < .001), trochlear depth increased from 0.0 mm (range, -4.2 to 1.8 mm) to 3.23 mm (range, 0.25-5.3 mm) (P < .001), and trochlear facet asymmetry improved from 4.55% (range, 0.0%-28.6%) to 17.8% (range, 0.0%-55.6%) (P < .003). Cartilage thickness was unchanged: 4.5 mm (range, 1.9-7.4 mm) preoperatively and 4.9 mm (range, 0.6-8.3 mm) postoperatively (P = .796). BPII, KOOS, and Kujala scores improved significantly (P < .0034 for all). Conclusion: Combined ADT and MPFL reconstruction led to statistically significant and clinically relevant improvements in patient-reported outcomes and standardized MRI measurements that characterize TD. The improvements corresponded to those obtained by open trochleoplasty. No significant reduction in cartilage thickness was seen.

Successful isolation of viable stem cells from cryopreserved microfragmented human adipose tissue from patients with knee osteoarthritis - a comparative study of isolation by tissue explant culture and enzymatic digestion.

PURPOSE: To investigate if viable stem cells could be isolated and expanded from cryopreserved microfragmented adipose tissue (AT) harvested from patients with knee osteoarthritis. METHODS: Microfragmented abdominal AT from knee osteoarthritis patients was cryopreserved at -80 °C in cryoprotectant-medium. The samples were thawed for stem cell isolation by tissue explant culture (TEC) and enzymatic digestion (ED), respectively. Viability, population doublings, and doubling time were assessed by trypan blue staining and flow cytometry. Cell type and senescence-associated ß-galactosidase activity were analyzed by flow cytometry. Osteogenic and adipogenic differentiation was assessed quantitatively by Alizarin-Red-S and Oil-Red-O staining, respectively. RESULTS: Microfragmented AT from 7 patients was cryopreserved for a period of 46-150 days (mean (SD) 115.9 days (44.3 days)). Viable stem cells were successfully recovered and expanded from all patients using both isolation methods with no significant difference in viable population doublings or doubling time from passage 1 to 3 (p > 0.05). Low levels of senescence-associated ß-galactosidase activity was detected for both methods with no significant difference between TEC and ED (p = 0.17). Stemness was verified by stem cell surface markers and osteogenic and adipogenic differentiation performance. Adventitial stem cells (CD31-CD34+CD45-CD90+CD146-), pericytes (CD31-CD34-CD45-CD90+CD146+), transitional pericytes (CD31-CD34+CD45-CD90+CD146+), and CD271+ stem cells (CD31-CD45-CD90+CD271+) were identified using both methods. More pericytes were present when using TEC (25% (24%)) compared to ED (3% (2%)) at passage 4 (p = 0.04). CONCLUSIONS: Viable stem cells can be isolated and expanded from cryopreserved microfragmented AT using both TEC and ED. TEC provides more clinically relevant pericytes than ED.

Treatment of osteoarthritis with autologous, micro-fragmented adipose tissue: a study protocol for a randomized controlled trial.

BACKGROUND: Osteoarthritis is a destructive joint disease that leads to degeneration of cartilage and other morphological changes in the joint. No medical treatment currently exists that can reverse these morphological changes. Intra-articular injection with autologous, micro-fragmented adipose tissue has been suggested to relieve symptoms. METHODS/DESIGN: The study is a blinded randomized controlled trial with patients allocated in a 1:1 ratio to 2 parallel groups. Patients suffering from pain and functional impairment due to osteoarthritis Kellgren-Lawrence grades 2-3 in the tibiofemoral joint are eligible for inclusion. The intervention group is treated with an intra-articular injection with autologous, micro-fragmented adipose tissue prepared using the Lipogems® system. The control group receives an intra-articular injection with isotonic saline. In total, 120 patients are to be included. The primary outcome is The Knee injury and Osteoarthritis Outcome Score (KOOS4) evaluated at 6 months. Secondary outcomes are KOOS at 3, 12 and 24 months; the Tegner activity score; treatment failure; and work status of the patient. The analysis will be conducted both as intention-to-treat and per-protocol analysis. DISCUSSION: This trial is the first to investigate the efficacy of autologous, micro-fragmented adipose tissue in a randomized controlled trial. The study uses the patient-reported outcome measure Knee Injury and Osteoarthritis Outcome Score (KOOS4) after 6 months as the primary outcome, as it is believed to be a valid measure to assess the patient's opinion about their knee and associated problems when suffering from osteoarthritis.

High tibial osteotomy performed with PEEK implant demonstrated a failure rate of 28.

OBJECTIVES: Opening-wedge high tibia osteotomies (HTO) can be technically challenging. The HTO iBalance system was designed to reduce vascular complications and to avoid secondary plate removal. The purpose of the study was to evaluate the performance of the HTO iBalance system in patients with symptomatic medial osteoarthritis and varus malalignment. METHODS: The study was performed as a retrospective cohort study investigating a consecutive series of patients who underwent HTO with the iBalance system performed by a single surgeon from August 2013 to March 2016 at Zealand University Hospital, Koege, and Aleris-Hamlet Hospital. The primary outcome was the degree of realignment. The secondary outcome was Knee injury and Osteoarthritis Outcome Score (KOOS). Follow-up was performed at mean (SD) 25 (9.7) months. Weight-bearing long-leg standing radiographs were taken before surgery and at follow-up. Failure was defined as collapse of the HTO defined as a correction <50% of the intended correction at time of follow-up. Logistic regression was used to identify risk factors for failure. RESULTS: 44 patients and a total of 47 knees were included in this study. Preoperatively the mechanical axis was a mean (SD) 5.8° (2.9) varus and postoperatively 2.3° (3.7) varus . The HTO failed in 13 of 47 knees (28%). Patients with failure showed no statistically significant differences to non-failure in any KOOS subscore (p>0.05). American Society of Anesthesiologists (ASA) score (p=0.01) and body mass index (BMI) (p=0.05) were correlated with failure, whereas bone transplantation and smoking were not. CONCLUSION: In this study, the failure rate of HTO was 28%. High BMI and ASA-score were the only risk factors associated with failure while bone grafting and smoking were not. LEVEL OF EVIDENCE: Retrospective cohort study, level III.

Effect of Medialization of the Trochlear Groove and Lateralization of the Tibial Tubercle on TT-TG Distance: A Cross-sectional Study of Dysplastic and Nondysplastic Knees.

BACKGROUND: Tibial tubercle-trochlear groove (TT-TG) distance is often used as a measure of lateralization of the TT and is important for surgical planning. PURPOSE: To investigate if increased TT-TG distance measured on axial magnetic resonance images is due to lateralization of the TT or medialization of the TG. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: A total of 84 knees (28 normal [NK], 28 with trochlear dysplasia [TD], and 28 with patellar dislocation without TD [PD]) were examined. The medial border of the posterior cruciate ligament (PCL) was chosen as the central anatomic landmark. The distance from the TT to PCL (TT-PCL) was measured to examine the lateralization of the TT. The distance from the TG to the PCL (TG-PCL) was measured to examine the medialization of the TG. Between-group differences were investigated by use of 1-way analysis of variance. RESULTS: The mean values for TT-TG distance were 8.7 ± 3.6 mm for NK, 12.1 ± 6.0 mm for PD, and 16.7 ± 4.3 mm in the TD group (P < .01). The mean values for TT-PCL distance were 18.5 ± 3.6 mm for NK, 18.5 ± 4.5 mm for PD, and 21.2 ± 4.2 mm in the TD group (P = .03). The mean values for TG-PCL distance were 9.6 ± 3.0 mm for NK, 7.1 ± 3.4 mm for PD, and 5.1 ± 3.3 mm in the dysplastic group (P < .01). CONCLUSION: The present results indicate that increased TT-TG distance is due to medialization of the TG and not lateralization of the TT. Knees with TD had increased TT-TG distance compared with the knees of the control group and the knees with PD. The TT-PCL distance did not differ significantly between groups, whereas the TG-PCL distance declined with increased TT-TG.

[Joint-preserving surgery in hip and knee and development of secondary osteoarthritis].

The purpose of this review was to elucidate if surgery can prevent secondary osteoarthritis (OA) in hip dysplasia, femoroacetabular impingement syndrome, varus malalignment of the knee, patella instability, anterior cruciate ligament injury and intra-articular fracture of the knee or hip. In conclusion, there is evidence that surgery for intra articular fracture of the knee or hip reduces the risk of secondary OA. There is a lack of prospective comparative studies for the remaining investigated conditions and as such no convincing evidence that surgery reduces the risk of secondary OA.

Treatment of osteoarthritis with autologous and microfragmented adipose tissue.

INTRODUCTION: Osteoarthritis (OA) is the leading cause of disability in elderly people. Several non-invasive solutions have been proposed with varying success rates. Recently, new therapeutic approaches, such as the use of minimally manipulated tissue products, have gained increasing popularity. The purpose of this study was to investigate the safety and feasibility of a single intra-articular injection of autologous, microfragmented adipose tissue in patients with knee OA. METHODS: The study was performed as a prospective cohort study. Microfragmented adipose tissue was obtained using a minimal manipulation technique (Lipogems). The safety of the procedure was evaluated by recording the type and incidence of any adverse events at three months. The clinical outcomes were determined using the Knee injury and Osteoarthritis Outcome Score (KOOS) scale at three, six and 12 months of follow-up. RESULTS: Twenty patients were included in the study and all participated in the follow-up. Only one adverse event was registered; a patient complaint of cosmetic changes to the abdominal subcutaneous tissue. The improvements in KOOS were significant at all follow-up. At one year, KOOS pain had improved by 14 points, symptoms by seven, activity of daily living by 13, sports by 19 and quality of life by 15. CONCLUSIONS: The intra-articular injection of autologous, microfragmented adipose tissue for treatment of knee OA seems safe. Randomised controlled trials are needed to elucidate the efficacy of the treatment. TRIAL REGISTRATION: This study was registered in ClinicalTrials.gov (NCT02697682). FUNDING: none.

[Knee pain in children and adolescents].

Knee pain is common among children and adolescents, and the most usual knee conditions are patellofemoral pain and Osgood-Schlatter disease. Long-standing knee pain often leads to reduced physical activity levels, and one in two continue to experience knee pain for years. Education of the patients and strategies to improve the ability of them to manage knee pain should be the mainstay of treatment for these types of knee pain. This review outlines current evidence on the managing of knee pain in children and adolescents and sets it into the context of a clinical care pathway from primary to secondary care.

Persistent morbidity after Medial Patellofemoral Ligament Reconstruction - A registry study with an eight-year follow-up on a nationwide cohort from 1996 to 2014.

BACKGROUND: To evaluate the trends in treatment of patellar dislocation in the Danish population as a whole from 1996 to 2014 and evaluate the incidence of persistent morbidity after Medial Patellofemoral Ligament Reconstruction (MPFL-R). METHODS: This epidemiological study was performed by retrospectively searching the Danish National Patients Registry from 1996 to 2014. The study investigated the trends in surgery performed on patients with patellar dislocations and the risk of persistent patellar morbidity (PPM) with an eight-year follow-up. PPM was defined as a new patella-related contact to the healthcare system more than a year after surgery. RESULTS: From 1996 to 2014, a total of 1956 MPFL-R were performed in Denmark. In 2014, MPFL-R constituted 75% of all patella-stabilizing surgery and was performed on almost 10% of patients with patellar dislocation. The mean risk of PPM eight years after surgery was 20.9% (18.3-23.4%), and young patients aged 10-17 showed the highest risk of 28.9% (23.7-33.7%). The risk of PPM over time was significantly higher for other patella-stabilizing surgery (33.8%) and patients receiving conservative treatment (29.4%) compared to MPFL-R. CONCLUSIONS: A rapid rise in the use of MPFL-R was found from 2005 to 2014, constituting 75% of all patella-stabilizing surgery in 2014. The overall risk of persistent patellar morbidity within eight years after MPFL-R was 21%. MPFL-R was found to give a significantly lower risk of PPM over time as compared to other patella-stabilizing surgery and conservative treatment.

Does different duration of non-operative immobilization have an effect on the redislocation rate of primary patellar dislocation? A retrospective multicenter cohort study.

BACKGROUND: Immobilization devices such as plaster splints, casts and braces have been used for first time patellar dislocation (FTPD) in order to prevent redislocation. This study evaluates different non-operative immobilization regimes upon rates of redislocation. METHODS: A retrospective cohort study with a study population of 1366 in which 601 subjects under 30years with FTPD were included from three hospitals. Exclusion criteria were osteochondral fracture, ligament injury and subluxation. Subjects were divided into five groups; unknown/none, two weeks of brace, two weeks of brace followed by bandage, four weeks of brace and six weeks of brace with increasing of range of motion. Radiographs were evaluated for trochlear dysplasia (TD), patella alta, trochlear depth and growth zone. Crude analysis and logistic regression adjusted for radiographic assessments, age, gender and rehabilitation was done in STATA® with significance p≤0.05. RESULTS: Forty-five point eight percent were between 15 and 19years and 51.4% were male. One hundred sixty-three experienced redislocation (27.1%). Logistic regression was performed at 404 subjects and showed that rehabilitation, gender, TD, patella alta, and growth zone had no significant odds ratio (OR) on redislocation. The duration of brace demonstrated no significant OR in reducing redislocation. Subjects between 20 and 29years showed lower OR in redislocation (95% CI) of 0.27 (0.11; 0.64, p=0.003). CONCLUSION: This study demonstrated no difference in duration of brace treatment in reducing patella redislocation after FTPD. Rehabilitation and predisposal factors such as TD, trochlear depth, patella alta and open growth zone did not influence the redislocation rate. Increasing age reduced risk of redislocation.

Quality assessment of radiological measurements of trochlear dysplasia; a literature review.

PURPOSE: To make a systematic review with quality assessments of the known measurements used to describe trochlear dysplasia. METHODS: A systematic literature search was conducted in the databases PubMed and Embase using the search string "trochlea dysplasia OR trochlear dysplasia". Papers were screened for their relevance based on predefined parameters, and all measurements showing a statistical association between trochlear dysplasia and patellar instability were presented. Four experts evaluated the quality of the measures using a purpose-made quality scale. RESULTS: The search generated 600 papers of which eight were chosen for review. Thirty-three unique measurements were identified and described in order of their date of publication. The lateral trochlea inclination was rated highest by the expert panel. The crossing sign, the trochlea bump, the TT-TG distance, the trochlea depth and the ventral trochlea prominence also had high ratings. CONCLUSION: Thirty-three unique measurements were identified with the lateral trochlea inclination as the highest rated measurement by the expert panel, and it is recommended for use in assessment of trochlear dysplasia. The crossing sign, the trochlea bump, the TT-TG, the trochlea depth and the ventral trochlea prominence were also rated well and can be recommended for use. LEVEL OF EVIDENCE: V.

High incidence of acute and recurrent patellar dislocations: a retrospective nationwide epidemiological study involving 24.154 primary dislocations.

PURPOSE: The purpose of this study was to investigate the Danish population as a whole from 1994 to 2013 to find the incidence of acute and recurrent patellar dislocation. METHODS: The study was performed as a descriptive epidemiological study. The Danish National Patient Registry was retrospectively searched from 1994 to 2013 to find the number of acute and recurrent patellar dislocation. National population data were collected from Statistics Denmark. RESULTS: The period 1994-2013 saw a total registration of 24,154 primary patellar dislocations. A mean incidence of 42 (95% CI 37-47) per 100,000 person-years at risk was found, and young females aged 10-17 had the highest incidence of 108 (95% CI 101-116). In a 10-year follow-up, patients were at an overall risk of 22.7% (95% CI 22.2-23.2) of suffering a recurrent dislocation, with young girls aged 10-17 experiencing the highest risk, namely 36.8% (95% CI 35.5-38.0). The overall risk of suffering a patellar dislocation in the contralateral knee was 5.8% (95% CI 5.5-6.1) and 11.1% (95% CI 10.4-11.7) for patients aged 10-17. CONCLUSION: A high incidence rate of primary patellar dislocation was found both as a mean in the population (42/100,000), and particularly in patients aged 10-17 (108/100,000). The risk of recurrent dislocation in the affected knee (22.7%) and the contralateral knee (5.8%) was high, which could indicate the influence of an underlying pathomorphology. This is relevant knowledge to the clinician, as he/she should be aware of the high risk of recurrent dislocation when deciding on treatment, especially in young patients. LEVEL OF EVIDENCE: IV.

Arthroscopic deepening trochleoplasty for chronic anterior knee pain after previous failed conservative and arthroscopic treatment. Report of two cases.

PURPOSE: A proportion of patients having years of chronic anterior knee pain(AKP) that have not responded to non-operative modalities. Trochlear dysplasia have been found to be a cause for AKP. By restoring the anatomy with a trochleoplasty procedure the patellofemoral joint is unloaded. This study is a prospective 2year follow-up study, based on two cases with chronic AKP for several years and having severe trochlear dysplasia and both were successfully treated by arthroscopic deepening trochleoplasty. METHODS: Case one was a 46year old women with chronic anterior knee pain (AKP). Imaging showed lateral trochlear inclination angle of 2°, trochlear asymmetry 0.36, central height 81% and medial height 83%. Thepreoperative Kujala score was 70 and Knee injury and Osteoarthritis Outcome Score (KOOS) subscale for pain was 67. Case two was a 26year old man troubled by AKP and knee knee joint effusion for >8years without any instability in the history. Imaging showed lateral trochlear inclination angle of 6°, trochlear asymmetry 0.25, central height 76% and medial height 78%. The preoperative Kujala score was 49 and KOOS subscale for pain was 72. RESULTS: The postoperative Kujala score was for case one 82 and for case two 81. The postoperative KOOS subscale for pain was for case one 89 and for case two 92. Improvement in the KOOS subscale for sport and recreational activities and quality of living were also found. CONCLUSION: This is the first case report to demonstrate that patient having had years of chronic AKP and trochlear dysplasia can be successfully treated by arthroscopic trochleoplasty.

Translation, adaptation and measurement properties of an electronic version of the Danish Western Ontario Shoulder Instability Index (WOSI).

OBJECTIVES: To translate and adapt the Western Ontario Shoulder Instability (WOSI) questionnaire into Danish and, to evaluate measurement properties of an electronic Danish WOSI version. METHODS: The Swedish WOSI version was used for translation and adaptation into Danish followed by examination of test-retest reproducibility (14-day interval) besides concurrent and construct validity. Concurrent validity was examined by comparing WOSI in paper version with an electronic version, whereas construct validity was examined by comparing WOSI with Numeric Pain Rating Scale (NPRS) and the Oxford Shoulder Score (OSS). Reproducibility was evaluated with Intraclass correlations (ICC), Standard Error of Measurement (SEM), minimal detectable change (MDC) and limits of agreement (LOA). Validity was evaluated with Pearson's (r) and Concordance Correlation Coefficients (CCC). RESULTS: 41 subjects (median age 34, range 18-57) were included in the analysis of reproducibility. An ICC of 0.97 (95% CI 0.95 to 0.99) for the total WOSI score was found. SEM was 100.1, resulting in an MDC of 277.5 and LOAs within the range of -246.4 and 308.6. 25 subjects (median age 34, range 18-72) were included in the analysis of concurrent validity obtaining a CCC of 0.96 (95% CI 0.91 to 0.98). Construct validity was investigated in 62 subjects (median age 31, range 18-72) obtaining correlations of 0.83 (95% CI 0.68 to 0.97) (NPRS) and 0.79 (95% CI 0.62 to 0.94) (OSS). CONCLUSIONS: An electronic Danish version of WOSI presented excellent test-retest reproducibility and acceptable measurement errors. Also, concurrent validity between paper and electronic version was highly satisfactory as was the construct validity. Surprisingly, though, the NPRS correlated more with WOSI than OSS.

Patellar Instability - An Update.

This review is a current concept on the topic of patellofemoral instability purposing to highlight, reflect and in cooperate both recent important findings regarding the patellofemoral joint. In the past decade numerous studies have significantly contributed to our understanding of both the epidemiology, symptomatology and underlying pathomorphology of patella instability. The topic of patella instability is very complex and several biomechanical important factor have been elucidated and consequently treatment strategies are changing. Both non-surgical as well as surgical algorithms are evolving, but still there is a lot of controversies and generally there is lack of consensus. Many different surgical options exist primarily based upon repair what have been torn, or by correcting the underlining pathomorphology. Reconstruction of the medial patellofemoral ligament is the most common surgical procedure, nevertheless in cases with more severe underlining pathomorphologic factors such as trochlear dysplasia, patella alta and increased femoral anteversion, subsequent procedures correcting those abnormalities should be corrected.