Ten-year follow-up and clinical outcome of a metaphyseal anchoring short hip stem prosthesis: a retrospective single-centre analysis.

PURPOSE: Short stems for total hip arthroplasty are an alternative to traditional conventional long stems. Short stems are designed to facilitate minimal-invasive surgery, improve bone-stock preservation, and mimic a physiological load distribution. However, there is little evidence of the long-term outcome of short stems. This study aims to analyze the ten year survival rates and clinical outcome of one specific metaphyseal short hip stem implant. METHODS: We retrospectively analyzed the patient records of the patients who underwent a total hip arthroplasty with a monoblock partial collum sparing metaphyseal short hip stem prosthesis in 2008 and 2009 in our clinic. Patients were contacted, and clinical follow-up was recorded using the German version of the modified Harris Hip Score. Furthermore, complications, revision surgery, and post-operative radiographs were analyzed. RESULTS: Data from 339 primary implantations in 322 patients were retrieved. The mean follow-up was 10.6 years. Seven patients underwent a revision. The ten year survival rate with any revision surgery as the endpoint was 97.5%. The mean modified Harris Hip Score was 86 points (range 30 to 91 points). Five patients had an intraoperative fracture of the femur (1.6%). Two patients (0.6%) had a dislocation of the hip. The stem tip-to-cortex distance, measured in the anterior posterior view, was 2.6 mm (range 0 to 8.3 mm). CONCLUSION: The ten year survival rate of our used monoblock partial collum sparing metaphyseal short hip stem implant is comparable to traditional stems for total hip arthroplasty.

The timing of tether breakage influences clinical results after VBT.

INTRODUCTION: Tether breakage is a frequent mechanical complications after vertebral body tethering (VBT), but not all patients with a breakage show loss of correction. The reason of this clinical finding has not yet been clarified. We hypothesized that the integrity of the tether is relevant only in the early stages after VBT, when it drives growth modulation and tissue remodelling. After these mechanisms have taken place, the tether loses its function and a breakage will not alter the new shape of the spine. Thus, tether breakage would have a greater clinical relevance when occurring shortly after surgery. METHODS: All consecutive patients who underwent VBT and had a min. 2-year follow-up were included. The difference in curve magnitude between the 1st standing x-ray and the last follow-up was calculated (ΔCobb). For each curve, the presence and timing of tether breakage were recorded. The curves were grouped according to if and when the breakage was observed (no breakage, breakage at 0-6 months, 6-12 months, > 12 months). The ΔCobb was compared among these groups with the analysis of variance (ANOVA). RESULTS: Data from 152 curves were available: 68 with no breakage, 12 with a breakage at 0-6 months, 37 at 6-12 months and 35 > 12 months. The ANOVA found significant difference in the ΔCobb among the groups (Sum of square 2553.59; degree of freedom 3; mean of square 851.1; Fisher test 13.8; P < 0.0001). Patients with no breakage or breakage at > 12 months had similar ΔCobb (mean 4.8° and 7.8°, respectively, P = 0.3), smaller than the 0-6 or 6-12 groups (15.8° and 13.8°, respectively). CONCLUSION: Tether breakage leads to a consistent loss of correction when occurring within the first 12 months, while it has limited clinical relevance when occurring later on.

Analysis of the risk factors for early tether breakage following vertebral body tethering in adolescent idiopathic scoliosis.

INTRODUCTION: Tether breakage is a common mechanical complication after VBT. When this occurs shortly after surgery, patients may be at higher risk for loss of correction. Aim of this study was to analyze demographic and radiographic parameters that may potentially be risk factors for early tether breakage, as no data are yet available on this topic. MATERIALS AND METHODS: All skeletally immature patients who underwent VBT and for whom a 1-year follow-up was available were included in the study. Demographic, intraoperative and coronal and sagittal parameters from the preoperative and 1st standing X-rays were collected. Patients were divided in two groups according to the presence or absence of a breakage and the outcomes of interest were compared. RESULTS: Data from 105 patients were available (age 14.2 ± 1.5, 153 curves). Lumbar curves showed a higher risk of breakage than thoracic ones (71% vs. 29%, P < 0.0001). Overall, preoperative risk factors were a high curve magnitude (MD, mean difference - 4.1°, P = 0.03) and a limited flexibility (MD 8.9%, P = 0.006); postoperative risk factors were a large residual curve (MD - 6.4°, P = 0.0005) and a limited correction (MD 8.4%, P = 0.0005). The same risk factors were identified in thoracic curves, while in lumbar instrumentation only a higher preoperative Cobb angle represented a risk factor for breakage. Age and skeletal maturity did not represent risk factors. CONCLUSION: The main preoperative risk factors for early tether breakage after VBT are a high curve magnitude and a limited flexibility. A limited curve correction also represents a risk factor for this complication.

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.

Introduction and evaluation of a novel multi-camera surface topography system.

BACKGROUND: Surface topography can be used for the evaluation of spinal deformities without any radiation. However, so far this technique is limited to posterior trunk measurements due to the use of a single posterior camera. RESEARCH QUESTION: Purpose of this study was to introduce a new multi camera surface topography system and to test its reliability and validity. METHODS: The surface topograph uses a two-camera system for imaging and evaluating the subjects front and back simultaneously. Inter- and intra-rater reliability was tested on 40 human subjects by two observers. For validation human, subjects were scanned by MRI and surface-topography. For additional validation we used a phantom with an anthropomorphic body which was scanned by CT and surface topography. RESULTS: Inter- (0.97-0.99) and intra-rater reliability (0.81-0.98) testing revealed good and excellent results in the detection of the body surface structures and measurement of areas and volumes. CT based validation revealed good correspondence between systems in the imaging and evaluation of the phantom model (0.61-10.52 %). Results on validation of human subjects revealed good to moderate results in the detection and measurements of almost all body surface structures (1.36-13.34 %). Only measurements using jugular notch as a reference showed moderate results in validity (0.62-27.5%) testing. SIGNIFICANCE: We have introduced a novel and innovative surface topography system that allows for simultaneous anterior and posterior trunk measurements. The results of our reliability and validity tests are satisfactory. However, in particular around the jugular notch region further improvements in the surface topography reconstruction are needed.

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.

Development of a new 360-degree surface topography application.

BACKGROUND: Surface-topography has been used for almost two decades in the radiation-free clinical evaluation of spinal posture. So far, it was limited to the analysis of back surface and spine. In order to better understand, diagnose and treat complex spinal pathologies, it is important to measure the whole torso. RESEARCH QUESTION: Purpose of this study was to introduce and test an application that allows 360° reconstruction and analysis of the patient's torso. METHODS: The application uses the information gathered from eight distinct scans and angles. For validation we used an Alderson phantom as an anthropomorphic body. Defined areas and volumes were measured by CT and surface-topography. Inter- and intra-rater reliability was tested in 35 healthy subjects by two observers. RESULTS: The results revealed good correspondence between systems in the imaging and evaluation of the Alderson model (5.3-0.5%). Inter- (0.9-0.98) and intra-rater reliability (0.8-0.95) testing revealed good and excellent results in the detection of almost all body surface structures and measurement of areas and volumes. Only area and volume measurements using jugular notch as a reference showed partly moderate results in reliability (0.62-0.93) testing. SIGNIFICANCE: We were able to introduce a novel 360° torso scan application using surface topography to reconstruct torso measurements. The results of our study showed its high validity and reliability. In the future, this application needs to be tested in patients with spinal pathologies. In summary, this new application may help to better understand, diagnose and treat patients with pathologies of torso and spine.

[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.

Comparison of two different designs of forefoot off-loader shoes and their influence on gait and spinal posture.

BACKGROUND: The purpose of forefoot off-loader shoes (FOS) is to unload the operated region of the foot in order to allow early mobilization and rehabilitation. However, little is known about the actual biomechanical effects of different designs of FOS on gait, pelvis and spine. RESEARCH QUESTION: Aim of this study was to analyse and compare the effects of two different designs of forefoot unloader shoes. METHODS: Ortho-Wedge (FOS A) and Relief-Dual® (FOS B) were evaluated in this study during standing and while walking. Changes of the pelvic position and spinal posture were measured with a surface topography system and an instrumented treadmill. Gait phases were detected automatically by a built-in pressure plate. RESULTS: Both FOS resulted in a significant increase of pelvic obliquity, pelvic torsion, lateral deviation and surface rotation (p < 0.001) while standing. Between both shoe models, pelvic obliquity and lateral deviation (p < 0.05) were significantly different. During walking, both FOS had a significant effect on spine and pelvis (p < 0.05), however only minor differences were found between the designs. All gait parameters were affected more, wearing FOS A than B. Step length were significantly longer by wearing FOS (p < 0.005). However stance phase raised and swing phase is reduced on the leg wearing FOS A (p < 0.001). SIGNIFICANCE: The study showed that FOS lead to significant changes in pelvic position and spinal posture during standing and while walking. A compensating shoe on the contralateral side is therefore recommend. Gait parameters however were affected more by the traditional FOS A half-shoe. The sole- design and shape of FOS B leads to a more physiological roll-over of the foot.

[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.

Impact of scapholunate dissociation on human wrist kinematics.

Neither the complex motions of the scapholunate joint, nor the kinematic changes that occur as a result of injury to it, are fully understood. We used electromagnetic tracking within affected bones to evaluate the physiologic motions in the planes of flexion and extension, and of radial and ulnar deviation of human cadaver wrists, before and after complete transection of the scapholunate ligaments. Despite individual variance between each wrist, we were able to establish a pattern in the changes that occurred after scapholunate ligament injury. During the motions examined, the scaphoid showed an increase in translational deviation in almost all motion axes. In contrast, the movement of the lunate seemed to be impaired, especially in radial-ulnar deviation.

[Cartilage repair of the knee joint]. / Knorpelreparative Eingriffe am Kniegelenk.

BACKGROUND: Cartilage defects around the knee joint frequently occur in the region of the medial femoral condyle and the retropatellar cartilage surface. The distinction between local cartilage defects and large area degenerative cartilage lesions is very important for both prognosis and surgical therapy. The size and position of the lesion, the underlying pathomechanism and the age of the patient are very important factors which should be considered in the therapy algorithm for optimal cartilage defect restoration. Important cofactors such as stability, long leg axis and muscle balance should be taken into account. AIM: Current procedures for cartilage repair of the knee joint and their results are summarized in this article. In addition, the necessity of precise and comprehensive preoperative clinical and radiological diagnostics is displayed to be able to treat co-pathologies in order to enable a successful repair of the cartilage defect. RESULTS AND CONCLUSIONS: Preoperative planning of cartilage-repair techniques usually includes x­ray images and a magnetic resonance imaging (MRI) examination. If MRI is not available, an arthro-computed tomography could be an alternative. Modern and routinely used procedures for cartilage repair at the knee joint are microfracture, autologous matrix-induced chondrogenesis, autologous chondrocyte transplantation, matrix-induced autologous chondrocyte implantation and osteochondral transplantation. Successful surgical cartilage-repair surgeries require a correct and individualized indication, addressing of copathologies and a standardized rehabilitation that is adapted to the surgical procedure. Evidence-based criteria for an exact time point for the return to sports according to individually operative cartilage repair techniques currently do not exist.

[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.

[Evaluation of biomechanical models for therapy planning of total hip arthroplasty - direct comparison of computational results with in vivo measurements]. / Evaluierung von biomechanischen Modellen zur Therapieplanung für die Hüftendoprothesenversorgung - direkter Vergleich zwischen Berechnungsergebnissen und In-vivo-Messungen.

A consideration of the patient-specific biomechanical situation in the context of the surgical planning of total hip arthroplasty is highly recommended and may have a positive impact on the therapeutic outcome. In current clinical practice, surgical planning is based on the status of the individual hip and its radiographic appearance. Several authors proposed different biomechanical modeling approaches for the calculation of the resultant hip force R on the basis of parameters gathered from plain radiography. The comparative study presented in this paper shows that the biomechanical models by Pauwels, Debrunner, Blumentritt and Iglic provide a good approximation of the magnitude of R when compared to the in vivo data from instrumented prostheses. In contrast, the Blumentritt model resulted in abnormally high values. However, the computational results for the orientation of R show a high variability of all modeling approaches and seem to depend more on the model used than on patient-specific parameters.

[Biomechanical modelling of the wrist joint]. / Biomechanische Modellierung der Handwurzel.

BACKGROUND: The hand represents one of the most complex joint mechanisms of the human body. The hand is also an important communication medium. The spectrum of today's hand injuries reaches from minor damage up to complex traumata with loss of several functional aspects. Enormous subsequent economic costs result. The therapeutic re-establishment of the equilibrium between maximum stress and the actual applied stress is the condition for a lifelong joint function. MATERIAL AND METHODS: A literature review about biomechanical wrist models was realised. The previous models found in the literature were systematically analysed as well as verifying their suitability for clinical use regarding pathological changes, therapy approaches and modelling/simulation approaches, respectively, of wrist injuries. RESULTS: The return of the wrist joint biomechanics to the normal condition is a key factor for a successful therapy. Furthermore, it is important for the re-establishment of an unimpaired joint function. Currently, there exist only simplified descriptions and models of the wrist joint, approximated by technical joints and furthermore, they are partially contradictory. Therefore, no uniform validated biomechanical wrist model exists as yet. CONCLUSION: Regarding the arising complex clinical problems, however, a valid biomechanical wrist joint model would be necessary as assistance, in order to improve the success of systematised therapies on the basis of computer-aided model-based planning and intervention.