A Differentiated View on Short Stemmed Hip Arthroplasty - What are the Differences in Fixation and Biomechanics? / Kurzschaft ist nicht gleich Kurzschaft ­ wo liegen die Unterschiede in der Verankerung und der Biomechanik?

The present paper gives an overview of the different types of short stem total hip replacements. There is a pronounced inhomogeneity of the nomenclature in clinical practice as well as in regard to the scientific literature. Examples include neck preserving implants, meta-, epi- or metadiaphyseal fixed implants, microimplants, ultrashort implants, partial neck preserving implants, trochanteric sparing implants, implants with extra- and/or intramedullar fixation, implants without primary fixation, etc. Biomechanically, the short stems vary from very short, completely neck retaining versions up to implants which are just a shorter version of a standard implant. A frequently cited classification recommends the osteotomy level as a discriminating factor. This classification categorizes into a neck preserving, partial neck preserving and neck resecting short stems.

Cartilage Surgery in Overweight Patients: Clinical and MRI Results after the Autologous Matrix-Induced Chondrogenesis Procedure.

Modern orthopaedic surgery provides a variety of techniques for cartilage repair. The Autologous Matrix-Induced Chondrogenesis (AMIC) procedure is a single-step technique with a collagen I/III scaffold for the treatment of full-thickness cartilage lesions. The aim of the study was to analyze the outcome of the AMIC procedure in overweight patients with knee cartilage defects. Overweight patients treated with AMIC surgery were followed up by clinical and MRI examination. 9 patients with a cartilage defect of the knee with a mean lesion size of 2.1 ± 1.2 cm2 and an average body mass index (BMI) of 29.3 were available for the follow-up. The Lysholm Score was significantly improved by the AMIC procedure (38 to 67, p ≤ 0.008). The VAS Score was significantly lower after the procedure (9 to 3, p ≤ 0.018). In the postoperative MOCART Scale, the scaffold reached defect covering of 80%. However, 2 patients had to be revised due to persisting knee pain. The AMIC procedure enhances pain reduction and gain of knee function for cartilage defects of overweight patients. However, in cases of an increased BMI, the patient had to be informed that success rate is reduced despite good defect covering.

Hip arthroscopy for excision of osteoid osteoma and for the application of a collagen cartilage implant: Case report in a professional athlete, and literature review.

BACKGROUND: Osteoid osteoma is an osteoblastic benign bone tumor usually affecting young adolescents. Intra-articular lesions are not common; usually the diagnosis is delayed. A lot of studies report difficulties and complications in the management of osteoid osteoma of the hip joint using imaging guided techniques or open surgical procedures. Only few published cases have described that it can be treated precisely using hip arthroscopy. Additionally, the use of hip arthroscopy to apply the Chondrofiller®, an acellular collagen matrix for the management of articular cartilage defects of the hip joint, has not yet been described. CASE PRESENTATION: This report presents an osteoid osteoma of the femoral neck. A 20-year-old female professional basketball player presented with pain in the left groin since more than 12 months. On magnetic resonance and computed tomography imaging, an osteoid osteoma was suggested. The lesion was successfully removed using arthroscopy. During surgery, a concomitant grade 4 cartilage lesion on the femoral head was detected. For the treatment of this severe defect we used the Chondrofiller®, which is a new acellular collagen implant for auto-regeneration of articular cartilage. This matrix was filled into the prepared and dried defect using CO2 arthroscopy. After the hardening of the matrix the surgery was finished. The patient was pain free shortly after the operation and returned to sports within 16 weeks. Return to high-performance sports 8 months after surgery was without of any sign of complaints. CONCLUSIONS: This article demonstrates that hip arthroscopy is a valuable tool for biopsy and excision of intra-articular osteoid osteoma affecting the hip joint, as well as for addressing other concomitant pathologies such as a severe synovitis or cartilage defects. CO2 arthroscopy provided good conditions for the drying and filling of the cartilage defect with the Chondrofiller®.

Mechanical debridement versus radiofrequency in knee chondroplasty with concomitant medial meniscectomy: 10-year results from a randomized controlled study.

PURPOSE: We compared the effectiveness of mechanical debridement (MD) and bipolar radiofrequency chondroplasty (RF) with regard to clinical outcome, rate of revision, and progression of knee osteoarthritis. METHODS: Sixty patients with MRI-detected grade III cartilage lesions on the medial femoral condyle were considered for the study. For MD (group 1; n = 30), each lesion was debrided using a mechanical shaver. For RF (group 2; n = 30), each lesion was smoothed using a temperature-controlled RF probe set at 50 °C. RESULTS: The 10-year follow-up was available for 47 patients (78.3 %). Sixty per cent of group 1 (n = 18) underwent revision during the follow-up period. In contrast, the revision rate in group 2 was 23.3 % (n = 7; p = 0.061). The mean survival was 94.1 months (95 % CI 77.1-111.3) and 62.5 months (95 % CI 45.9-79.2) for group 2 and group 1, respectively. Patients who did not require revision (group 1, n = 9; group 2, n = 13) were assessed before surgery and 1, 4, and 10 years after surgery using the knee injury and osteoarthritis outcome score (KOOS). At follow-up, the KOOS was higher for group 2 than group 1. At the time of surgery, no patient showed any radiological signs of osteoarthritis. The width of the medial joint was 5.4 mm (95 % CI 4.3-6.5) and 5.6 mm (95 % CI 4.9-6.3) in the MD and RF groups, respectively (n.s.). During the follow-up period, the joint space width narrowed continuously in both groups (p < 0.001), but more rapidly in the group 1 (n.s). CONCLUSION: Compared to conventional MD, 50° RF treatment appears to be a superior method based on short- and medium-term clinical outcomes and the progression of knee osteoarthritis. Clear predictors for the indications of different cartilage treatments and more randomized clinical trials are needed. LEVEL OF EVIDENCE: I.

Combination of autologous chondrocyte implantation (ACI) and osteochondral autograft transfer system (OATS) for surgical repair of larger cartilage defects of the knee joint. A review illustrated by a case report.

OBJECTIVES: Modern orthopaedic surgery provides a variety of techniques for cartilage repair. Despite comprehensive scientific data about the single procedures, there is little experience with the combination of these methods. Inspired by a case from our clinic, we performed a PubMed based literature search about the combination of cartilage restoration principles. MATERIALS AND METHODS: The literature search was performed using the terms: ``mosaicplasty'' OR ``osteochondral transplantation'' OR ``OATS'' AND ``autologous chondrocyte implantation'' OR ``autologous chondrocyte transplantation'' OR ``ACI'' OR ``matrix-associated autologous chondrocyte implantation'' OR ``MACI'' AND ``combination''. Abstracts were revised for relevance to our case. Additionally, we present a case report of the combinatory use of three established techniques. RESULTS: Two relevant publications, both reporting satisfying results concerning postoperative functional outcome, were found. Our results confirm this first encouraging assessment, although statistically valid data and prospective studies are still missing. CONCLUSIONS: The simultaneous use of different techniques for cartilage repair may provide alternative operative solutions for single complex cases, although further studies are required for a general recommendation.

Short-term results of the reverse Total Evolutive Shoulder System (TESS) in cuff tear arthropathy and revision arthroplasty cases.

INTRODUCTION: The aim of this study was to evaluate the clinical and radiological outcome of the Total Evolutive Shoulder System (TESS) in patients with cuff tear arthropathy and patients in need of a revision arthroplasty. METHODS: In this sequential study, 67 patients (56 non-stemmed, 11 stemmed) were evaluated after a mean follow-up of 17.5 months. The relative Constant and DASH scores, radiological joint geometry changes, complications and postoperative problems, which are not likely to affect the outcome, were evaluated. RESULTS: A significant increase was noticed for the relative Constant (11.3 vs. 78.8 %) and DASH scores (73.7 vs. 31.8) without significant differences between both etiology groups. Complication rates were similar to previous studies. An aseptic loosening of the non-stemmed humeral component was not noticed in the cuff tear arthropathy group, whereas one case with a loosening was noticed in the revision arthroplasty group. With nine cases (13.4 %), scapular notching rates were very low. On average, the acromiohumeral distance increased by 17 mm and the humeral offset by 13.9 mm; the height of the center of rotation decreased by 4.6 mm and the lateral glenohumeral offset by 6.1 mm, p < 0.05, respectively. CONCLUSION: Regarding the joint geometry, surgery with the TESS system provided adequate distalization and medialization of the humerus and the center of rotation. This corresponds to a good clinical outcome. The use of the surgical opportunity to implant the prosthesis with a relatively low neck-shaft angle might explain the low rates of scapular notching in our series. Regarding the case with a loosening of the humeral component, the surgeon should carefully indicate a stemless version for metaphyseal press-fit fixation in patients with revision arthroplasty.

Is the Kinect system suitable for evaluation of the hip joint range of motion and as a screening tool for femoroacetabular impingement (FAI)?

BACKGROUND: In the clinical evaluation of femoroacetabular impingement (FAI), there is a lack of quantitative, reliable and informative assessment methods for the overall functional capability of an individual. OBJECTIVE: We compared clinical and radiological measurements of the hip joint with a new methodology based on the concept of 3-dimensional reachable workspace using Microsoft Kinect. METHODS: We assessed the correlation between the alpha angle of Nötzli on full-length radiographs and the clinical internal rotation. We evaluated the accuracy of joint positions and angles of the hip between the Kinect system and clinical examination including range of motion (ROM). RESULTS: The results of our clinical trial with 24 study participants showed a significant difference between normal internal rotation (> 21°) and reduced internal rotation (⩽ 21°) in comparison to the radiological alpha angle of Nötzli (P=0.026). The acquired reachable Kinect data demonstrated a moderate agreement between the Kinect and clinical examination (correlation coefficients between 0.230 and 0.375). CONCLUSIONS: The findings suggest that a higher grade alpha angle of Nötzli accompanies reduced clinical internal rotation. The Kinect system provides reliable results of hip ROM. However, further test series must be performed for the application of Kinect in the clinical evaluation of FAI.

Comparative study of the femoroacetabular impingement (FAI) prevalence in male semiprofessional and amateur soccer players.

INTRODUCTION: Femoroacetabular impingement (FAI) represents a novel approach to the mechanical etiology of hip osteoarthritis. The cam-type femoroacetabular impingement deformity occurs frequently in young male athletes. The aim of our study was to evaluate the prevalence of FAI in male semiprofessional soccer players using clinical examination and magnetic resonance imaging (MRI), compared to amateur soccer players. In MRI, the α angle of Nötzli is determined for quantifying FAI. MATERIALS AND METHODS: According to power analysis, a total of 22 asymptomatic semiprofessional soccer players with a median of 23.3 years of age (range 18-30 years) and 22 male amateur soccer players with a median of 22.5 years of age (control group, range 18-29 years) underwent an MRI to measure the hip α angle of Nötzli. The α angle of the kicking legs of the semiprofessional group and the amateur group were analyzed. The study group was moreover evaluated by the Hip Outcome Score (HOS) and a clinical hip examination including range of motion (ROM) and impingement tests. RESULTS: In the semiprofessional group, 19 soccer players had a right kicking leg and 1 soccer player had a left kicking leg. 2 soccer players kicked with two feet. In the semi-professional group, the mean value of the α angle of the kicking leg (57.3 ± 8.2°) was significantly higher than in the amateur group (51.7 ± 4.8°, P = 0.008). In the semi-professional group, 15 (62.5 %) of 24 kicking legs had an increased α angle >55°, while 5 (27.3 %) kicking legs of the amateur group had an α angle >55°. Five semi professional soccer players had findings in clinical examination, whereof 4 had an increased α angle >55°. No participant of the amateur group showed pathological results in the clinical examination (P = 0.0484). Overall, semiprofessional soccer players had a higher proportion of an increased α angle than the amateur group. CONCLUSIONS: Semiprofessional players have a higher prevalence of an increased α angle in the kicking leg than the amateur group at the same age. The kicking leg is predisposed for FAI.

Biomechanical and functional indicators in male semiprofessional soccer players with increased hip alpha angles vs. amateur soccer players.

BACKGROUND: Femoroacetabular impingement (FAI) is predominant in young male athletes, but not much is known about gait differences in cases of increased hip alpha angles. In our study, the hip alpha angle of Nötzli of soccer players was quantified on the basis of magnetic resonance imaging (MRI) with axial oblique sequences. The aim of the current study was to compare the rearfoot motion and plantar pressure in male semiprofessional soccer players with increased alpha angles to age-matched amateur soccer players. METHODS: In a prospective analysis, male semiprofessional and amateur soccer players had an MRI of the right hip to measure the alpha angle of Nötzli. In a biomechanical laboratory setting, 14 of these participants in each group ran in two shoe conditions. Simultaneously in-shoe pressure distribution, tibial acceleration, and rearfoot motion measurements of the right foot were performed. RESULTS: In the semiprofessional soccer group, the mean value of the alpha angle of group was 55.1 ± 6.58° (range 43.2-76.6°) and 51.6 ± 4.43° (range 41.9-58.8°) in the amateur group. In both shoe conditions, we found a significant difference between the two groups concerning the ground reaction forces, tibial acceleration, rearfoot motion and plantar pressure parameters (P < 0.01, P < 0.05, P = 0.04). Maximum rearfoot motion is about 22% lower in the semiprofessional group compared to the amateur group in both shoe conditions. CONCLUSIONS: This study confirmed that semiprofessional soccer players with increased alpha angles showed differences in gait kinematics compared to the amateur group. These findings support the need for a screening program for competitive soccer players. In cases of a conspicuous gait analysis and symptomatic hip pain, FAI must be ruled out by further diagnostic tests.

The deviation of the mechanical leg axis correlates with an increased hip alpha angle and could be a predictor of femoroacetabular impingement.

PURPOSE: This study was designed to evaluate whether the mechanical axis deviation (MAD) of the leg correlates with an increased hip alpha angle as described by Nötzli, which is associated with femoroacetabular impingement (FAI). METHODS: In a retrospective analysis, standing full-length anteroposterior radiographs were analysed in patients who suffered from symptomatic leg alignment. The study included 85 radiographs of 80 patients with an average age of 43.11 years (range 18-60 years). Five patients underwent a bilateral long-leg X-ray examination. All radiographs were transferred as Digital Imaging and Communications in Medicine data files from the Picture Archiving and Communications System into the OrthoPlanner software version 2.3.2. The radiographs were measured by one orthopaedic surgeon and one independent radiologist. RESULTS: The mean value of the alpha angle of Nötzli was 61.43° (49.07-74.04°). A total of 57 (67%) radiographs showed a varus deviation, 25 (29.5%) had a valgus malalignment and three (3.5%) a straight leg axis. Of 82 radiographs, 40 (48.8%) had a moderate axis deviation with a MAD <15 or > - 15 mm and a mean alpha angle of 57.81°, and 42 (51.2%) with extended axis deviation of a MAD > 15 or < - 15 mm had a mean alpha angle of 62.93°; 40 (95.2%) of these 42 showed an alpha angle > 55°. The alpha angle was significantly increased in extended axis deviation compared to moderate axis deviation (P = 0.001). CONCLUSIONS: This study confirmed that increased alpha angles were found significantly at higher degrees of axis deviation on the full-length radiograph. In cases of a MAD >15 or < - 15 mm and symptomatic coxalgia, diagnostic tests must be pursued for FAI.

The role of arthroscopy in patients with persistent hip pain after total hip arthroplasty.

BACKGROUND: Total hip arthroplasty (THA) is a safe and successful procedure for the treatment of osteoarthritis. One of the most common postoperative problems remains persistent hip pain. The arthroscopic evaluation of persistent hip pain following THA can be a valuable diagnostic tool in a select number of patients when carried out by experts in this technique. OBJECTIVE: Indication for arthroscopy was persistent pain after THA. Inclusion criteria were an absence of radiological loosening and a sterile aspiration 6 weeks before arthroscopy. Hip joint function and pain were evaluated pre- and postoperatively using the visual analogue scale (VAS) and the Hip Outcome Score (HOS), which scored the activities of daily living (ADL), and a sports subscale. METHODS: 5 patients (3 female, 2 male) with an average age of 60.2 ± 4.27 years (range 51-72 years) were included in the study. Arthroscopy with biopsy, adhesiolysis and psoas tendon release was performed 21.0 ± 21.97 months (range 6-57 months) after primary hip replacement. RESULTS: Pathological findings were prosthetic joint infection (two cases), impingement between acetabular component and psoas tendon (two cases), adhesions of the periprosthetic tissue (one case). The patients achieved a significant improvement of the Hip Outcome Score (HOS), from an average of 45.6 ± 22.5 (range 14.0-63.1) to 76.5 ± 3.8 (range 41.0-89.4, P=0.016). Evaluation of the VAS showed a significant improvement from a preoperative value of 8.8 ± 0.5 to a postoperative value of 3.4 ± 1.0 (P=0.001). CONCLUSION: Hip arthroscopy provides a minimal-invasive tool for diagnosis and therapy. In cases of persistent pain after THA, standard diagnostic procedures should be utilised. Arthroscopy of a hip post-THA would be highly specialised. As a next step, arthroscopy helps the diagnosis and therapy of persistent pain after THA.

Elbow extension deficit: a rare case of an osteochondral lesion on the radial head.

BACKGROUND: An extension deficit of the elbow joint can be caused by various pathologies such as arthroliths, posttraumatic scar tissues, synovitis, capsular fibrosis of the anterior joint compartment, osteophytes in the area of the olecranon fossa or osteochondral lesions (OCL). Arthroscopic treatment is a good therapeutic option for theses pathologies. OBJECTIVE: We performed a standardized elbow arthroscopy in the case of an 18-year old male roofer presented with an extension deficit of 5° which had existed for several years. As physical activity, the patient performed boxing and BMX bicycle races. The patient had no history of any kind of previous elbow surgery, injury, inflammatory or metabolic rheumatic disease or haemophilia. METHODS: In the arthroscopic evaluation, we found a central OCL of the radial head with reactive capsular hypertrophy. The OCL was treated by microfracture with a chondropic. The clinical outcome was assessed by the Disability of Arm, Shoulder and Hand (DASH) score. RESULTS: The restoration of the elbow joints full range of the motion (ROM) was achieved by arthroscopic treatment and adhesiolysis. In the follow-up examination one year after arthroscopy, the patient was asymptomatic and the elbow joint could be moved freely. Evaluation of the DASH score showed an improvement from a preoperative score of 7.0 to a postoperative score of 2.6. CONCLUSIONS: Arthroscopy of the elbow is a good tool to treat OCL on the radial head. In cases of an extension deficit of the elbow, an OCL should be considered as a differential diagnosis.

Refractory adhesive capsulitis under acitretin therapy.

BACKGROUND: Adhesive capsulitis (AC) is characterized by a limited active and passive motion. Although the exact pathology remains unknown, a number of contributing factors are discussed. OBJECTIVE: AC has probably been caused by the Re-PUVA therapy (PUVA irradiation plus acitretin) of a cutaneous T-cell lymphoma, type mycosis fungoides. Acitretin belongs to the group of retinoids and is often used in cornification disorders. METHODS: After non-successful initial conservative therapy with intraarticular steroid injections and physical therapy, a significant improvement of shoulder joint mobility was finally achieved by an arthroscopic juxtaglenoid capsulotomy and adhesiolysis. RESULTS: A therapy with acitretin should be considered as a possible trigger of AC. CONCLUSIONS: Patient's medication should be checked carefully on possible triggers of AC. The athroscopic adhesiolysis is an effective method for a frustrating conservative treatment of AC.

The impact of a high tibial valgus osteotomy and unicondylar medial arthroplasty on the treatment for knee osteoarthritis: a meta-analysis.

PURPOSE: Both high tibial valgus osteotomy (HTO) and unicompartmental medial knee arthroplasty (UKA) are established methods for the treatment for moderate stages of OA. This is the first global meta-analysis to compare the long-term effects of both methods regarding survival, outcomes and complications of total arthroplasty. METHODS: Literature research was performed using established medical databases: MEDLINE (via PubMed), EMBASE (via OVID) and the Cochrane register. Criteria for inclusion were as follows: English or German papers, a clinical trial with a clear description of survival, an outcome evaluation using a well-described knee score and a follow-up >5 years. Statistical analysis was performed using the special meta-analysis software called "Comprehensive Meta Analysis" (version 2.0; Biostat, Englewood, NJ, USA). RESULTS: Final meta-analysis after the full-text review included 46 studies about valgus HTO and 43 studies about medial UKA. There were no significant differences between valgus HTO and medial UKA in terms of the number of total required replacements. After a 5- to 8-year follow-up, 91.0% of the valgus HTO patients and 91.5% of medial UKA patients did not need a total replacement. This value was 84.4% for valgus HTOs and 86.9% for medial UKAs after a 9- to 12-year follow-up. Mean survival time to TKA was 9.7 years after valgus HTO and 9.2 years after medial UKA. Clinical outcome was significantly better after medial UKA in a 5- to 12-year follow-up. After more than 12 years, results were comparable in both groups. No significant differences were seen in the complication rates. CONCLUSIONS: This meta-analysis aimed to find the advantages and disadvantages of two established methods for the treatment for medial compartment knee osteoarthritis. Valgus HTO is more appropriate for younger patients who accept a slight decrease in their physical activity. Medial UKA is appropriate for older patients obtaining sufficient pain relief but with reduced physical activity. LEVEL OF EVIDENCE: II.

Analysis of the sensory innervations of the greater trochanter for improving the treatment of greater trochanteric pain syndrome.

In medical practice, greater trochanteric pain syndrome has an incidence of 5.6 per 1,000 adults per year, and affects up to 25% of patients with knee osteoarthritis and low back pain in industrialized nations. It also occurs as a complication after total hip arthroplasty. Different etiologies of the pain syndrome have been discussed, but an exact cause remains unknown. The purpose of this study was to obtain a better understanding of the sensory innervations of the greater trochanter in attempt to improve the treatment of this syndrome. Therefore, we dissected the gluteal region of seven adult and one fetal formalin fixed cadavers, and both macroscopic and microscopic examination was performed. We found a small sensory nerve supply to the periosteum and bursae of the greater trochanter. This nerve is a branch of the n. femoralis and accompanies the arteria and vena circumflexa femoris medialis and their trochanteric branches to the greater trochanter. This nerve enters the periosteum of the greater trochanter directly caudal to the tendon of the inferior gemellus muscle. This new anatomical information may be helpful in improving therapy, such as interventional denervation of the greater trochanter or anatomically guided injections with corticosteroids and local anesthetics.

Isolated AL bundle reconstruction of the PCL.

INTRODUCTION: The purpose of this study was to evaluate the clinical and radiologic results after isolated reconstruction of the posterior cruciate ligament (PCL) using the semitendinosus (ST) and gracilis (GR) tendons with the arthroscopic single-bundle technique. METHODS: All patients upon whom we had performed a single-bundle PCL reconstruction between 2002 and 2005 prospectively underwent a standardized follow-up examination after 2 years. Isolated PCL reconstruction was carried out on 41 patients during the observation period. Pre- and postoperative stress radiographs were taken using the Telos stress device in order to evaluate the dorsal translation. Knee joint function and degree of activity were recorded using the Tegner activity score, the subjective International Knee Documentation Committee (IKDC) score, and the overall IKDC score. RESULTS: 33 of 41 patients (80.4%, 17 men, 16 women) completed the study. The posterior tibial translation of -10.1 ± 1.8 mm had an overall average improvement to a postoperative value of -5.0 ± 2.5 mm (p < 0.001). The patients showed a significant improvement in the Tegner activity score from an average 2.8 ± 0.8 points to 5.9 ± 1.2 points (p < 0.001). Evaluation of the subjective IKDC showed a significant improvement from a preoperative score of 41.86 ± 11.49 points to a postoperative score of 69.54 ± 11.39 points (p < 0.001). In total, 24 patients (72.8%) exhibited a normal or nearly normal outcome. CONCLUSION: The abovementioned reconstruction technique can achieve a stable knee function in patients with isolated PCL insufficiency. The isolated single-bundle PCL reconstruction offers an improvement regarding the activity level and stability of the knee joint. LEVEL OF EVIDENCE: Level IV.

Hoffa's fat pad impingement treated arthroscopically: related findings on preoperative MRI in a case series of 62 patients.

INTRODUCTION: The morphology of painful impingement of the infrapatellar fat pad (Hoffa's disease), which is characterized by inflammation, swelling, hypertrophy, fibrosis, and/or calcifications, has been well described. The purpose of this study was to investigate whether corresponding characteristic MRI findings could be assessed in patients with infrapatellar fat pad impingement. MATERIALS AND METHODS: This study includes 62 patients with secondary symptomatic Hoffa's fat pad impingement. In these patients, the fat pad was partially resected until no impingement could be determined at full knee movement. Within a maximum of 3 months before arthroscopic surgery, patients had standardized MR imaging using a 1.5 Tesla unit with the following sequences: sagittal T1-TSE, coronal STIR-TSE, transversal fat-suppressed PD-TSE, and sagittal fat-suppressed PD-TSE (Siemens Magnetom Avanto syngo MR B 15). In this case series, the preoperative MRI appearance of the fat pad was evaluated and compared with a cohort of 255 patients without fat pad impingement but with various knee disorders at arthroscopy as well as the same standardized MRI protocol. RESULTS: In patients with Hoffa's fat pad impingement, morphologic changes such as localized edema of the superior and/or posterior part of the fat pad, a deep fluid-filled infrapatellar bursa, non-visualization of vertical and/or horizontal clefts, fibrosis, and calcifications were noted on MR imaging with remarkable frequency. Besides a significant enlargement of the fat pad, each of these MRI findings was significantly associated with impingement of Hoffa's fat pad (P < 0.05). Besides a moderate kappa score for the detection of intrahoffatic calcifications and vertical clefts, kappa values for each finding showed good inter-observer agreement. Results of logistic regression revealed that edema of Hoffa's fat pad was one of the most important diagnostic MRI criteria for the diagnosis of Hoffa's fat pad impingement. CONCLUSION: MR imaging allows identification of several changes that may be related to a symptomatic impingement of Hoffa's fat pad. In patients who are suspected of having infrapatellar fat pad impingement, such MRI findings should be considered and distinguished from other causes of anterior knee pain.

Individual and occupational risk factors for knee osteoarthritis - study protocol of a case control study.

BACKGROUND: Knee osteoarthritis (OA) is one of the frequent and functionally impairing disorders of the musculoskeletal system. In the literature, a number of occupational risk factors are discussed as being related to the development and progress of knee joint diseases, e.g. working in kneeling or squatting posture, lifting and carrying of heavy weights. The importance of the single risk factors and the possibility of prevention are currently under discussion. Besides the occupational factors, a number of individual risk factors are important, too. The distinction between work-related factors and individual factors is crucial in assessing the risk and in deriving preventive measures in occupational health. In existing studies, the occupational stress is determined mainly by surveys in employees and/or by making assumptions about individual occupations. Direct evaluation of occupational exposure has been performed only exceptionally. The aim of the research project ArGon is the assessment of different occupational factors in relation to individual factors (e.g. constitutional factors, leisure time activities, sports), which might influence the development and/or progression of knee (OA). The project is designed as a case control study. METHODS/DESIGN: To raise valid data about the physical stress associated with occupational and leisure time activities, patients with and without knee OA are questioned by means of a standardised questionnaire and an interview. The required sample size was estimated to 800 cases and an equal number of controls. The degree and localisation of the knee cartilage or joint damages in the cases are documented on the basis of radiological, arthroscopic and/or operative findings in a patient record. Furthermore, occupational exposure is analysed at selected workplaces. To evaluate the answers provided in the questionnaire, work analysis is performed. DISCUSSION: In this research project, specific information on the correlation of occupational and individual factors on the one hand and the current state of knee OA on the other will be analysed in order to describe preventive measures. In addition, information regarding a better evaluation of various forms of physical stress in different occupations will be available. This might lead to more effective prevention strategies.