Minimally versus conventional-invasive transforaminal lumbar interbody fusion in patients with failed back surgery syndrome.

BACKGROUND: Failed back surgery syndrome is an important cause of back and leg pain after spinal surgery. Transforaminal lumbar interbody fusion (TLIF) is commonly used in revision surgery for failed back surgery syndrome. In the literature, there is a lack of evidence concerning the minimally and conventional-invasive TLIF and debates are ongoing. The purpose of the present study was to compare efficacy and safety of minimally versus conventional-invasive TLIF for failed back surgery syndrome. MATERIALS AND METHODS: This study was conducted according to the STROBE Statement. Between 2011 and 2014, thirty patients with failed back surgery syndrome underwent TLIF. Group I (15 patients) received minimally invasive TLIF through paramedian approach using microscopy and fluoroscopy. Group II (15 patients) received conventional-invasive TLIF. Minimum follow-up was 12 months. RESULTS: There was a significant improvement of Oswestry Disability Index (ODI) and visual analogue scale (VAS) in both groups postoperatively. There was no statistically significant difference between both groups regarding ODI, VAS, leg and back pain pre- and postoperatively. There was a tendency to better postoperative ODI and VAS scores in group I; however this did not reach the statistical significance. One case showed adjacent segment degeneration in group I. In group II, one case had screw mal-positioning with foot drop. Another case had dural injury with postoperative fistula. CONCLUSION: TLIF is a valuable option after failed back surgery syndrome providing statistically significant improvement postoperatively. Both minimally and conventional-invasive TLIF represent a safe and reliable treatment of patients with failed back syndrome, achieving satisfactory outcome along with low rate of complications. Although the minimally invasive TLIF scored better, these differences did not reach the threshold of significance.

Nerve palsy, dislocation and revision rate among the approaches for total hip arthroplasty: a Bayesian network meta-analysis.

BACKGROUND: Total hip arthroplasty (THA) is one of the most performed intervention in orthopaedics surgery. Currently, there is no unanimous approval concerning the best approach for THA in terms of nerve palsies, dislocations and further revisions. Hence, a Bayesian network meta-analysis was conducted. METHODS: The present study was conducted according to the PRISMA extension statement for reporting of systematic reviews incorporating network meta-analyses of healthcare interventions. The literature search was performed in September 2019. The NMA was performed through the STATA Software/MP routine for Bayesian hierarchical random-effects model analysis. RESULTS: Data from 10,675 THA were collected. The mean follow-up was 10 months. The anterior approach reported the lowest risk to incur a post-operative dislocation (overall inconsistency P = 0.99). The posterolateral approach reported the lowest risk to incur a nerve palsy (overall inconsistency P = 0.77). The funnel plot revealed a low risk of publication bias. The lateral approach was found to have the lowest risk of resulting in a revision surgery (overall inconsistency P = 0.90). CONCLUSION: According to our network comparisons, the posterolateral approach for THA represent the favourable exposure with regards to nerve palsy, further dislocations and revision surgeries.

Hospitalization length, surgical duration, and blood lost among the approaches for total hip arthroplasty: a Bayesian network meta-analysis.

Despite the numerous studies, there is no consensus concerning the best approach for total hip arthroplasty (THA), and debates are ongoing. The purpose of this study was to perform a Bayesian network meta-analysis (NMA) comparing several approaches for primary THA. The focus was on peri-operative outcomes: surgical duration, total estimated blood loss, and length of the hospitalization. This Bayesian network meta-analysis was conducted according to the PRISMA extension statement for reporting systematic reviews incorporating network meta-analyses of health care interventions. In October 2019, the main databases were accessed. All the clinical trials comparing two or more different approaches for primary THA were assessed. For the methodology quality assessment, the PEDro score was performed. The Software STATA MP was used for the statistical analyses. The NMA was performed through the routine for Bayesian hierarchical random-effects analysis with the inverse variance statistic method for continuous variables. Data from 4843 procedures was analysed. Between patient's demographic, good baseline comparability was found. The comparison total estimated blood loss detected statistically significant inconsistency (P = 0.01). The posterolateral approach reported the lowest value for the surgical duration. The test for overall inconsistency was statistically significant (P = 0.4). The posterolateral approach reported the shortest hospitalization length. The test for overall inconsistency was statistically significant (P = 0.9). The posterolateral approach reported shorter surgical duration and hospitalization length. Concerning the analysis of total estimated blood loss, no significant result was obtained. Data must be considered in the light of the limitations of the present study.

[Resection margins in soft tissue sarcomas]. / Resektionsgrenzen bei Weichteilsarkomen.

BACKGROUND: Soft tissue sarcomas (STS) are a rare and heterogeneous group of malignant tumors that arise from the mesenchymal tissue. STS can form anywhere in the human body, with the extremities being preferred sites of predilection. TREATMENT: A fundamental pillar of treatment is the surgical resection of soft tissue sarcomas. The goal is always an R0 resection with a safety margin. There is no consensus in the literature about the desired tumor-free resection margin. The decisive factors for these resection margins are histopathology, presence of anatomical barriers (capsule, tendon, fascia, cartilage, periosteum) and possibilities of (neo-) adjuvant therapy. DISCUSSION: References in the literature support the role of resection margins as a predictor of local recurrence. Regarding the role of resection margins in overall survival, available data is divergent. There are known prognostic factors that influence overall survival, such as histological subtype, tumor size, tumor grading, and presence of metastases. So far, several studies have attempted to quantify the margins of resection, but no consensus has been reached, and debates are ongoing. When analyzing all the results of the data in the literature, it seems appropriate to aim for a negative resection margin >1 mm including an anatomical border structure, if possible.

[Differentiated treatment strategies for bone metastases of the extremities]. / Differenzierte Therapiestrategien bei Knochenmetastasen der Extremitäten.

BACKGROUND: Bone metastases are the most common malignant bone tumours and most commonly occur in the spine, pelvis, proximal femur and proximal humerus. Prostate and breast cancer most often metastasize to the bone. DIAGNOSTICS: In patients with a history of tumours and local unspecific pain in the back and extremities, further diagnostic examinations should be performed. For the initial diagnosis a conventional radiograph of the whole bone in two planes is sufficient. For further diagnostics, the imaging may be supplemented with CT, MRI, scintigraphy and a PET-CT (PET-MRI) if the findings are not inconspicuous on the x­ray. An indication for biopsy exists if the tumor cannot be classified, especially in solitary findings with or without previous tumor anamnesis. THERAPY: Surgical indications for bone metastases are a pathological fracture, an impending fracture, a solitary late metastasis, radiation-resistant osteolysis and therapy-resistant pain. In solitary metastases, the prognosis for patients can be significantly improved by a wide (R0 resection) depending on the primary tumour. For multiple metastases the restoration of mobility and improvement of the quality of life are in the foreground. Depending on the life expectancy and other factors, such as the location of the metastases osteosynthesis, implantations of dual head prothesis, total joint arthroplasty and tumor endoprostheses can be performed.

[Revision total hip arthroplasty : Significance of instability, impingement, offset and gluteal insufficiency]. / Revisionsendoprothetik der Hüfte : Bedeutung von Instabilität, Impingement, Offset und Glutealinsuffizienz.

BACKGROUND: Instability is a common cause of failure in primary and, especially, revision total hip arthroplasty. The reasons for instability include implant malpositioning, impingement, inadequate offset reconstruction, and gluteal insufficiency. Impingement following THA and revision THA is divided into prosthetic and bony impingement, and in addition to instability also causes pain in the area of the hip joint. Offset reconstruction during revision THA is of particular biomechanical importance, since insufficient reconstruction leads not only to instability and pain but also to dislocation. Abductor deficiency often occurs after revision THA and leads to a change in gait pattern, instability and pain. AIM: Current diagnostic and treatment procedures for instability, impingement, insufficient offset reconstruction and abductor deficiency after THA and revision THA are summarized. RESULTS AND DISCUSSION: Diagnosis of an instable THA and painful THA includes patient history, physical examination and medical imaging. Thus, in almost all cases, the cause can be determined and treated. Dislocation after primary THA in the early postoperative period can often be treated conservatively if accurate component placement is observed, while a late-onset and recurrent dislocation after primary and revision THA usually needs surgical procedures. To avoid bony and prosthetic THA impingement intraoperative control is absolutely necessary. If possible, the offset reconstruction is based on the condition of the native hip joint and can be achieved by using modular prostheses, neck adapters and different head lengths. Abductor deficiency also occurs frequently after revision THA and can be treated surgically if severe clinical symptoms and fatty degeneration of the abductors have been diagnosed.

[Biomechanical modeling and the relevance for total hip arthroplasty]. / Biomechanische Modellierung und ihre Bedeutung für die Hüftendoprothetik.

BACKGROUND: Providing the hip with an endoprosthesis is one of the most common orthopedic interventions in Germany. The long-term success of such a procedure depends on the consideration of the loads due to muscle and joint forces in the planning and operative care. Patient-specific information of forces acting in vivo is not available to the surgeon in clinical routine today. This is where biomechanical modeling comes in. PROCEDURES: A field of activity of biomechanical modeling is the development of methods and procedures for the precise analysis and simulation of endoprosthetic supplies. The aim was to show the possibilities of biomechanical modeling in total hip arthroplasty by means of two examples (sensitivity analysis and pre-/postoperative comparison of intervention outcome). RESULTS: The results of the sensitivity analysis showed that by modeling the position of an optimal reconstruction of the hip rotational center can be found and the forces acting on the hip joint minimized. In the case of the pre-/postoperative comparison, it can be analyzed whether there has been a decrease or increase of load postoperatively, respectively, or whether the conditions are considered to be approximately equal to the preoperative situation. In the future, biomechanical modeling will be able to significantly improve long-term function by reducing wear and optimizing muscular function of the joint. Therefore, the routine use of validated musculoskeletal analysis in the context of standardized preoperative planning and intraoperative navigation-based implementation should be considered. Thus, validated analyses of musculoskeletal loads not only contribute to the extension of basic knowledge but also to the optimization of endoprosthetic care through their integration into the clinical workflow.

[Total hip replacement in avascular femoral head necrosis]. / Endoprothetik bei aseptischer Femurkopfnekrose.

BACKGROUND: Avascular necrosis of the femoral head is a progressive perfusion disorder of the hip joint. Progress in avascular necrosis causes structural damage to the affected joint, often requiring total hip replacement. AIM: This article is intended to give the reader an overview of the current literature on total hip replacement of patients with an avascular necrosis of the femoral head. RESULTS: Before 1990, patients with avascular necrosis of the femoral head had significantly higher revision rates after total hip replacement. Recent studies, however, showed no significant differences in clinical outcomes after total hip replacement in femoral head necrosis and primary osteoarthritis. Despite the young age of the patients, good long-term clinical results can be expected even in patients with an avascular necrosis of the femoral head after total hip replacement.

[Perthes disease-diagnosis, classification and treatment based on Aachen-Dortmund treatment algorithm]. / M. Perthes ­ Diagnostik, Klassifikation und Therapie anhand des Aachen-Dortmunder Therapiealgorithmus.

Legg-Calvé-Perthes disease is a multifactorial idiopathic necrosis of the hip that typically occurs in childhood between the ages of 3 and 12. Treatment adapted to the stadium of the disease and to the clinical findings is medical art. The treatment is focused on the preservation or recovery of the arthrogenic containment of the femoral head. Multiple treatment options are available. The indications for treatment can be derived from clinical and radiological pathology. Structuring of the therapy options is the aim of this publication. For this purpose, a clear and concise overview of relevant clinical findings and useful radiographic classifications as well as reasonable therapy is presented.

Non-invasive T1ρ mapping of the human cartilage response to loading and unloading.

OBJECTIVE: To define the physiological response to sequential loading and unloading in histologically intact human articular cartilage using serial T1ρ mapping, as T1ρ is considered to indicate the tissue's macromolecular content. METHOD: 18 macroscopically intact cartilage-bone samples were obtained from the central lateral femoral condyles of 18 patients undergoing total knee replacement. Serial T1ρ mapping was performed on a clinical 3.0-T MRI system using a modified prostate coil. Spin-lock multiple gradient-echo sequences prior to, during and after standardized indentation loading (displacement controlled, strain 20%) were used to obtain seven serial T1ρ maps: unloaded (δ0), quasi-statically loaded (indentation1-indentation3) and under subsequent relaxation (relaxation1-relaxation3). After manual segmentation, zonal and regional regions-of-interest were defined. ROI-specific relative changes were calculated and statistically assessed using paired t-tests. Histological (Mankin classification) and biomechanical (unconfined compression) evaluations served as references. RESULTS: All samples were histologically and biomechanically grossly intact (Mankin sum: 1.8 ± 1.2; Young's Modulus: 0.7 ± 0.4 MPa). Upon loading, T1ρ consistently increased throughout the entire sample thickness, primarily subpistonally (indentation1 [M ± SD]: 9.5 ± 7.8% [sub-pistonal area, SPA] vs 4.2 ± 5.8% [peri-pistonal area, PPA]; P < 0.001). T1ρ further increased with ongoing loading (indentation3: 14.1 ± 8.1 [SPA] vs 7.7 ± 5.9% [PPA]; P < 0.001). Even upon unloading (i.e., relaxation), T1ρ persistently increased in time. CONCLUSION: Serial T1ρ-mapping reveals distinct and complex zonal and regional changes in articular cartilage as a function of loading and unloading. Thereby, longitudinal adaptive processes in hyaline cartilage become evident, which may be used for the tissue's non-invasive functional characterization by T1ρ.

[Current overview of cartilage regeneration procedures]. / Aktuelle Übersicht knorpelregenerativer Verfahren.

BACKGROUND: Cartilage is an avascular, alymphatic and non-innervated tissue with limited intrinsic repair potential. The high prevalence of cartilage defects and their tremendous clinical importance are a challenge for all treating physicians. AIM: This article provides the reader with an overview about current cartilage treatment options and their clinical outcome. METHODS: Microfracture is still considered the gold standard in the treatment of small cartilage lesions. Small osteochondral defects can be effectively treated with the autologous osteochondral transplantation system. Larger cartilage defects are successfully treated by autologous membrane-induced chondrogenesis (AMIC) or by membrane-assisted autologous chondrocyte implantation (MACI). CONCLUSION: Despite limitations of current cartilage repair strategies, such procedures can result in short- and mid-term clinical improvement of the patients. Further developments and clinical studies are necessary to improve the long-term outcome following cartilage repair.

[Chondral and osteochondral defects : Representation by imaging methods]. / Chondrale und osteochondrale Defekte : Darstellung mittels bildgebender Verfahren.

Morphological imaging of cartilage at high resolution allows the differentiation of chondral and osteochondral lesions. Nowadays, magnetic resonance imaging is the principal diagnostic tool in the assessment of cartilage structure and composition. Conventional radiography, computed tomography, ultrasound or optical coherence tomography are adjunct diagnostic modalities in the assessment of cartilage pathologies. The present article discusses the up-to-date diagnostic practice of cartilage imaging in terms of its scientific basis and current clinical status, requirements, techniques and image interpretation. Innovations in the field such as functional MRI are discussed as well due to their mid- to long-term clinical perspective.

A comparative study of mechanical properties of fresh and frozen-thawed porcine intervertebral discs in a bioreactor environment.

Limited availability of fresh intervertebral discs (IVDs) necessitates the use of frozen-thawed samples in biomechanical investigations. Several authors have reported the mechanical properties of frozen-thawed IVDs, but few studies have investigated the effects of storage temperature and cooling rate. The validity and reliability of the applied freezing-thawing procedures are still relatively unknown. The study aims to compare the mechanical responses of fresh porcine IVDs and porcine IVDs, which were frozen at different freezing temperatures with a controlled-rate cooling process and then thawed. The specimens were obtained from pigs aged 6 months. A total of 18 functional spine units (FSUs) were taken from seven porcine lumbar spines (L1-L6). The specimens were then split into three groups. The first group was tested fresh immediately and the other two groups were frozen at the same cooling rate and stored at -20°C and -80°C, respectively, before testing. The period of storage ranged between 12 and 43 days. The frozen specimens were thawed for 9h at room temperature before the tests. A special IVD bioreactor, which maintained the realistic behaviour of IVDs under various loading conditions, was developed. The analysis of variance (ANOVA) was used to determine if the observed results were statistically significant. The results indicated that frozen storage at -20°C decreases the comprehensive stiffness. In contrast, freezing to -80°C did not seem to have any effect on the mechanical properties of IVDs. No significant differences in outcome were observed for the samples, which had different spine levels. The study confirmed the reliability and usability of frozen-thawed samples stored at -80°C for biomechanical investigations.

New approach for predictive measurement of knee cartilage defects with three-dimensional printing based on CT-arthrography: A feasibility study.

PURPOSE: The aim was to prove the possibility of creating an exact module of knee cartilage defects using 3D printing. METHODS: Defects were created in cadaver knees. CT-arthrography and 3-Tesla MRI were performed. Based on CTA images a model of the cartilage was created using 3D printing. Defect-sizes in the imaging modalities were compared. RESULTS: Estimated lesion area in 3D model differed approximately 5% comparing to the defect sizes in knees. MRI underestimated the defect on average of 12%, whereas the CTA overestimated the defect about 3%. CONCLUSIONS: We proved the feasibility of creating an accurate module of knee cartilage.

[Hip arthroplasty after corrective osteotomies : Pelvis and proximal femur]. / Hüftendoprothetik nach korrigierenden Osteotomien : Becken und proximales Femur.

BACKGROUND: Pelvic and femoral osteotomies are frequently performed in patients with hip dysplasia. The aim of these surgeries are optimal biomechanical conditions of the hip joint thereby avoiding the occurrence of hip osteoarthritis or the delay of initial hip osteoarthritis progression. THERAPY: Nevertheless even with good biomechanical conditions of the hip joint, progression of hip osteoarthritis can be recognized postoperatively. A total hip arthroplasty is indicated even more after a time period with conservative treatment. In preparation for the operation, a detailed documentation of the initial clinical situation, appropriate imaging, implant selection and preoperative planning are mandatory. In addition, a biomechanical model representing the desired pre- and postoperative situation can be included in the preoperative planning. According to the previous osteotomy, the size and shape of the acetabulum after the osteotomy and the current pivot centre of the hip joint should be considered. Depending on these observations the acetabular cup can be directly inserted into the bone stock of the acetabulum or an acetabular plasty is necessary before implantation of the acetabular cup. With respect to the previous osteotomy of the femur, it needs to be clarified wether hardware removal will be necessary before total hip replacement; moreover, the anatomy of the proximal femur is critical. In addition, if necessary, a re-osteotomy of the femur is required to enable a hip stem implantation. CONCLUSION: Cementless total hip replacement should be preferred due to the younger patient age. The load of the hip replacement depends on the osseous anchoring and primary stability of the acetabular and femoral component.