Influence of kinematic alignment on femorotibial kinematics in medial stabilized TKA design compared to mechanical alignment.

INTRODUCTION: Worldwide more and more primary knee replacements are being performed. Kinematic alignment (KA) as one of many methods of surgical alignment has been shown to have a significant impact on kinematics and function. The aim of the present study was to compare KA and mechanical alignment (MA) with regard to femorotibial kinematics. MATERIALS AND METHODS: Eight fresh frozen human specimens were tested on a knee rig during active knee flexion from 30 to 130°. Within the same specimen a medial stabilized (MS) implant design was used first with KA and then with MA. RESULTS: The femorotibial kinematics showed more internal rotation of the tibia in KA compared to MA. At the same time, there was a larger medial rotation point in KA. Both alignment methods showed femoral rollback over the knee bend. CONCLUSION: Relating to an increased internal rotation and a more precise medial pivot point, it can be concluded that KA combined with a MS implant design may partially support the reproduction of physiological knee joint mechanics.

Immune and stem cell compartments of acetabular and femoral bone marrow in hip osteoarthritis patients.

OBJECTIVE: Hip osteoarthritis (OA) affects all components of the osteochondral unit, leading to bone marrow (BM) lesions, and unknown consequences on BM cell functionality. We analyzed the cellular composition in OA-affected acetabula compared to proximal femur shafts obtained of hip OA patients to reveal yet not explored immune and stem cell compartments. DESIGN: Combining flow cytometry, cellular assays and transcription analyses, we performed extensive ex vivo phenotyping of acetabular BM cells from 18 hip OA patients, comparing them with their counterparts from patient-matched femoral shaft BM samples. Findings were related to differences in skeletal sites and age. RESULTS: Acetabular BM had a greater frequency of T-lymphocytes, non-hematopoietic cells and colony-forming units fibroblastic potential than femoral BM. The incidence of acetabular CD45+CD3+ T-lymphocytes increased (95% CI: 0.1770 to 0.0.8416), while clonogenic hematopoietic progenitors declined (95% CI: -0.9023 to -0.2399) with age of patients. On the other side, in femoral BM, we observed higher B-lymphocyte, myeloid and erythroid cell frequencies. Acetabular mesenchymal stromal cells (MSCs) showed a senescent profile associated with the expression of survival and inflammation-related genes. Efficient osteogenic and chondrogenic differentiation was detected in acetabular MSCs, while adipogenesis was more pronounced in their femoral counterparts. CONCLUSION: Our results suggest that distinctions in BM cellular compartments and MSCs may be due to the influence of the OA-stressed microenvironment, but also acetabular vs femoral shaft-specific peculiarities cannot be excluded. These results bring new knowledge on acetabular BM cell populations and may be addressed as novel pathogenic mechanisms and therapeutic targets in OA.

[Scaffold-based Bone Tissue Engineering]. / Gerüstträgerbasiertes Knochen-Tissue-Engineering.

Tissue engineering provides the possibility of regenerating damaged or lost osseous structures without the need for permanent implants. Within this context, biodegradable and bioresorbable scaffolds can provide structural and biomechanical stability until the body's own tissue can take over their function. Additive biomanufacturing makes it possible to design the scaffold's architectural characteristics to specifically guide tissue formation and regeneration. Its nano-, micro-, and macro-architectural properties can be tailored to ensure vascularization, oxygenation, nutrient supply, waste exchange, and eventually ossification not only in its periphery but also in its center, which is not in direct contact with osteogenic elements of the surrounding healthy tissue. In this article we provide an overview about our conceptual design and process of the clinical translation of scaffold-based bone tissue engineering applications.

Acetabular defect classification in times of 3D imaging and patient-specific treatment protocols.

Parallel to the rising number of revision hip procedures, an increasing number of complex periprosthetic osseous defects can be expected. Stable long-term fixation of the revision implant remains the ultimate goal of the surgical protocol. Within this context, an elaborate preoperative planning process including anticipation of the periacetabular defect form and size and analysis of the remaining supporting osseous elements are essential. However, detection and evaluation of periacetabular bone defects using an unsystematic analysis of plain anteroposterior radiographs of the pelvis is in many cases difficult. Therefore, periacetabular bone defect classification schemes such as the Paprosky system have been introduced that use standardized radiographic criteria to better anticipate the intraoperative reality. Recent studies were able to demonstrate that larger defects are often underestimated when using the Paprosky classification and that the intra- and interobserver reliability of the system is low. This makes it hard to compare results in terms of defects being studied. Novel software tools that are based on the analysis of CT data may provide an opportunity to overcome the limitations of native radiographic defect analysis. In the following article we discuss potential benefits of these novel instruments against the background of the obvious limitations of the currently used native radiographic defect analysis.

[Treatment of acetabular bone defects in revision hip arthroplasty using the Revisio-System]. / Defektadaptierte Versorgung azetabulärer Knochendefekte mit dem Revisio-System.

BACKGROUND: Many different systems for the management of primary and secondary acetabular defects are available, each with its inherent advantages and disadvantages. The Revisio-System is a press-fit oval mono-block implant that makes a defect-oriented reconstruction and restoration of the center of rotation possible. MATERIAL AND METHODS: In this study, we retrospectively reviewed the outcome of 92 consecutive patients treated with this oval press-fit cup due to periacetabular bone loss. The average follow-up was 58.2 months. Defects were classified according to D'Antonio. There were 39 type II, 38 Type III, and 15 type IV defects. After an average of 4.9 years, the implant survival rate was 94.6% with cup revision as the end point and 89.1% with revision for any reason as the end point. The Harris Hip Score increased from 41.1 preoperatively to 62.3 postoperatively. The mean level of pain measured with the Visual Analogue Scale (VSA) was reduced from 6.9 preoperatively to 3.8 postoperatively. RESULTS: The Revisio-System represents a promising toolbox for defect-orientated reconstruction of acetabular bone loss in revision hip arthroplasty. Our results demonstrate that the implantation of the Revisio-System can result in a good mid-term clinical outcome.

Irreversible muscle damage in bodybuilding due to long-term intramuscular oil injection.

Intramuscular oil injections generating slowly degrading oil-based depots represent a controversial subject in bodybuilding and fitness. However they seem to be commonly reported in a large number of non-medical reports, movies and application protocols for 'site-injections'. Surprisingly the impact of long-term (ab)use on the musculature as well as potential side-effects compromising health and sports ability are lacking in the medical literature. We present the case of a 40 year old male semi-professional bodybuilder with systemic infection and painful reddened swellings of the right upper arm forcing him to discontinue weightlifting. Over the last 8 years he daily self-injected sterilized sesame seed oil at numerous intramuscular locations for the purpose of massive muscle building. Whole body MRI showed more than 100 intramuscular rather than subcutaneous oil cysts and loss of normal muscle anatomy. 2-step septic surgery of the right upper arm revealed pus-filled cystic scar tissue with the near-complete absence of normal muscle. MRI 1 year later revealed the absence of relevant muscle regeneration. Persistent pain and inability to perform normal weight training were evident for at least 3 years post-surgery. This alarming finding indicating irreversible muscle mutilation may hopefully discourage people interested in bodybuilding and fitness from oil-injections. The impact of such chronic tissue stress on other diseases like malignancy remains to be determined.

[Nerve lesions after minimally invasive total hip arthroplasty]. / Nervenläsionen nach minimal-invasiver Hüftendoprothetik.

Although there is no clear evidence, minimally invasive hip arthroplasty seems to be associated with slightly higher complication rates compared to standard procedures. Major nerve palsy is one of the least common but most distressing complications. The key for minimizing the incidence of nerve lesions is to analyze preoperative risk factors, accurate knowledge of the anatomy and minimally invasive techniques. Once clinical signs of nerve injury are evident, the first diagnostic steps are localization of the lesion and quantification of the damage pattern. Therefore, clinical assessment of the neurological deficits should be performed as soon as possible. Apart from rare cases of isolated transient conduction blockade or complete transection, the damage pattern is mostly combined. Thus, there can be evidence for dysfunction of nerve conduction (neuropraxia) and structural nerve damage (axonotmesis or neurotmesis) simultaneously. Because the earliest signs of denervation are detectable via electromyography after 1 week, it is not possible to make any reliable prognosis within the first days after nerve injury using electrophysiological methods. This review article should serve as a guideline for prevention, diagnostics and therapy of neural lesions in minimally invasive hip arthroplasty.

[Tumors of the foot: diagnostics and therapy]. / Fußtumoren: Diagnostik und Therapie.

Despite the compact anatomy with thin soft tissue coverage, diagnosis of both benign and malignant tumors of the foot is often delayed. Diagnostic errors are more common than in other body regions, as neoplasias are rarely considered. Barring a few exceptions the foot is not a typical predilection site for malignant musculoskeletal tumors, although, basically any tumor entity of the musculoskeletal system can affect the foot. Delays in specific diagnostic and therapeutic procedures of these lesions can entail serious consequences for patients as tumor size is a major prognostic factor for recurrence-free survival. In cases of an indistinct persistent swelling or bone lesion a tumorous process should always be considered to ensure early diagnosis and therapy of foot tumors.

[Minimally invasive anterior approach]. / Der minimal-invasive anteriore Zugang.

The minimally invasive direct anterior approach for total hip arthroplasty (THA) was first published in 1985. Since then the technique has been further improved and the indications have been extended. The approach utilizes the muscle gap between the tensor fasciae latae muscle on the lateral side and the sartorius muscle on the medial side. This muscle gap allows a direct and quick approach to the hip joint with good muscle preservation. During preparation of the femur the tensor fasciae latae muscle is at risk of being damaged. The lateral cutaneous nerve of the thigh (NCFL) and its branches are also in danger of being damaged during skin incision and dissection of the subcutaneous tissue. In this article the technique, risks and current clinical results of THA using the minimally invasive direct anterior approach are described. The results from the literature, as well as own results are compared to the traditional transgluteal lateral Bauer approach and discussed. Reviewing the literature, special attention has been given to the incidence of NCFL lesions, damage of the tensor fasciae latae muscle and positioning of the cup. Especially for the latter, the general view is hindered in the minimally invasive technique.

Conversion hip arthroplasty via the direct anterior approach: pearls, pitfalls and personal experience.

OBJECTIVE: Conversion total hip arthroplasty (CTHA) through a direct anterior approach (DAA) in supine position. INDICATIONS: Failed osteosynthesis of proximal femoral fractures or failed conservative hip surgery, with hardware in situ. CONTRAINDICATIONS: Decayed general conditions, infection (peri-implant or systemic infection), need for greater trochanter reconstruction, severe proximal femur deformity. SURGICAL TECHNIQUE: Supine position. Mark DAA and expected limited incisions for hardware removal (HR) with the help of a C-arm. Use guidewire and extraction devices for HR. Perform a DAA with particular attention to a wide release of the femur. POSTOPERATIVE MANAGEMENT: Full progressive weight-bearing starting on day 1, depending on bone quality. Discharge with crutches following patient walking capability. Precautions for 6 weeks. RESULTS: In all, 27 conversion THAs through a DAA. Mean age at the time of surgery 59.8 (range 18-81) years. Mean body mass index was 23.5 (range 17-31.6). Reasons of previous surgery failures were avascular necrosis of the femoral head, posttraumatic arthritis and nonunion with or without hardware migration. Mean surgical time was 125.8 min (range 58-190 min, standard deviation [SD] 38.2 min). Mean follow-up time was 6.9 years (range 2-15, SD 5.03 years). Mean pre-Harris Hip Score (mHHs) was 24.4 (range 19-36, SD 5.4), while the mean post-mHHS was 90.3 (range 89-91, SD 0.95). Two patients required postoperative osteosynthesis for periprosthetic fractures due to falls. Overall complication rate was 10%.

A systematic review and meta-analysis on the value of the external rotation stress test under fluoroscopy to detect syndesmotic injuries.

Purpose: The aim was to conduct a systematic literature review and meta-anaylsis to analyze the diagnostic accuracy of the external rotation stress test (ERST) for syndesmotic injuries. Methods: The systematic review was conducted according to the PRISMA-P guidelines (Prospero ID: CRD42021282457). Four common databases were searched from inception to September 29, 2021. Eligible were any studies facilitating the ERST under fluoroscopy in a defined state of syndesmotic instability. Syndesmotic ligament-specific rupture must have been proven by MRI, arthroscopy, or controlled dissection (cadaver study). Two reviewers independently conducted each step of the systematic literature review. The risk of bias was assessed by the Quality Appraisal for Cadaveric Studies Score scale. The data analysis was performed qualitatively and quantitatively. Results: Eight studies were eligible for a qualitative analysis, and six studies were eligible for a quantitative analysis. All studies included were cadaver studies. The qualitative analysis comprised 94 specimens and revealed considerable heterogeneity. Six studies allowed for a quantitative analysis of the tibiofibular clear space (TFCS) and five studies for the medial clear space (MCS) during the ERST. The quantitative analysis of the TFCS revealed no significant differences between intact and any stage of syndesmotic injury. The MCS was able to differentiate between intact and 2-ligament- (Z = 2.04, P = 0.02), 3-ligament- (Z = 3.2, P = 0.001), and 3-ligament + deltoid ruptures (Z = 3.35, P < 0.001). Conclusion: The ERST is the only noninvasive test to assess syndesmotic instability and can be conducted bilaterally. The uninjured contralateral side can serve as a baseline reference. Based on the conducted quantitative analysis, the MCS seems to be able to differentiate between stable (intact/1-ligament) and unstable (2-ligament/3-ligament) lesions.

[Painful hip arthroplasty: a diagnostic algorithm]. / Schmerzhafte Hüftendoprothetik: Ein diagnostischer Algorithmus.

The number of implantations of hip prostheses in Germany is now approximately 190,000 per year. By improving the implants and the development of modern surgical techniques and instruments the revision rate has been significantly reduced. The survival rate of the implants could be further increased in recent years, however, up to 22% of patients complain about persistent pain after hip arthroplasty. The diagnosis of existing pain after total joint replacement of the hip joint to achieve a causal therapy needs a systematic approach because of the heterogeneity of the symptoms and diseases. The etiology of the pain can be joint-associated and also hip joint independent. Often the causes of pain are multifactorial so that a standardized assessment should be conducted using an algorithm. The clarification of pain begins with the history, inspection and palpation followed by a clinical examination. It is then useful to perform radiological imaging followed by invasive procedures if necessary. The exploratory revision is nowadays considered to be obsolete in the literature.

[Diagnostics and therapy of spinal metastases]. / Diagnostik und Therapie von Wirbelsäulenmetastasen.

Out of all skeletal metastases 30% are located in the spine as are 10% of primary bone tumors, whereby 52% of metastases occur in the lumbar region, 36% in the thoracic spine and 12% in the cervical spine. Patients suffer from local pain caused by irritation of the periosteum due to rapid growth of the tumor or subsequent pathologic fractures which may lead to compression and neurological impairment with paresthesia, paresis and paraplegia. If the diagnosis cannot be confirmed exactly by radiological imaging and laboratory tests, a biopsy should be performed. A precise diagnosis of the tumor entity as well as an estimation of the prognosis provides an important basis for further decision-making. The aim of therapy is pain relief and stabilization by operative and non-operative measures. Therapy is palliative with the aim of pain relief and preservation of mobility. In cases of solitary metastasis a curative operative treatment should be performed.

[Total hip replacement in developmental dysplasia: anatomical features and technical pitfalls]. / Hüftgelenkendoprothetik bei kongenitaler Dysplasie: Anatomische Besonderheiten und technische Stolpersteine.

Total hip arthroplasty is the procedure of choice for most patients with advanced, symptomatic osteoarthritis due to congenital dysplasia of the hip. However, the complexity of arthroplasty is significantly increased because of anatomic abnormalities associated with dysplasia of the hip. In addition the relatively young age of patients may affect survival of the implant. From a biomechanical standpoint the primary surgical objective is reconstruction of the anatomical center of rotation. Independent of the pelvic bone stock the socket should be located as near as possible to the anatomical acetabular location. There are various operative strategies to ascertain sufficient stability of the socket. The anterolateral deficiency of the acetabulum can be reconstructed by bulk femoral autografting or bone impaction grafting. Furthermore controlled perforation of the medial wall or implantation of reinforcement rings and oval sockets have been described. Cementless, biological socket fixation shows superior long-term results compared to cemented cups, especially in these young patients. The location of the reconstructed acetabulum and the desired leg length influence the type of femoral reconstruction and in some cases femoral shortening is required. In this article endoprosthetic reconstructive options for developmental dysplasia of the hip are discussed depending on the femoral and acetabular deformity.

[Periprosthetic fractures after total hip arthroplasty : classification, diagnosis and therapy strategies]. / Periprothetische Frakturen bei Hüftendoprothese : Klassifikation, Diagnostik und Therapiestrategien.

The number of periprosthetic fractures following hip replacement is increasing due to longer life expectancy and the rising number of joint replacements. The main causes of periprosthetic fractures include trauma, implant specific factors or loosening of the endoprosthesis. When planning therapy, surgeons should consider specific and general implant- and patient-related risk factors to ensure the best possible treatment. Established classification systems can facilitate preoperative planning. At present, the Vancouver classification system probably comes closest to the ideal, as it considers fracture configuration, stability of the implant and quality of the bone stock. Depending on these factors, therapeutic options include conservative treatment, fracture stabilisation or replacement of the endoprosthesis. The problems associated with periprosthetic fractures of varying etiology and the available treatment options are discussed against the background of the established classification systems.

[Quality of a multidisciplinary orthopaedic-rheumatological consultation]. / Qualität einer interdisziplinären Sprechstunde in der Rheumaorthopädie.

AIM: An interdisciplinary approach plays an important role in orthopaedic rheumatology. The aim of this study was to test the quality of an interdisciplinary consultation, which analyzed a pool of orthopaedic patients in terms of rheumatological disease. METHOD: Orthopaedic patients (n=100) were transferred to a multidisciplinary team of experts in a two-stage selection process. Patient data were examined with regard to diagnosis and therapy. A patient interview analyzed the course of disease and effects of the consultation. Patients were questioned on the development of pain, diagnostics and therapy as well as their general satisfaction. RESULTS: Rheumatological disease was diagnosed in 42% of patients, while specific anti-rheumatic therapy was started in 41%. An improvement in symptoms as a result of treatment was seen in 63% of cases. Patient examinations revealed an above-average level of satisfaction in 63% of patients. CONCLUSION: Interdisciplinary consultation led to improved and faster diagnosis and therapy of rheumatological diseases, which was positively evaluated by the pool of patients treated.

[Mega cups and partial pelvic replacement]. / Megapfannen und Beckenteilersatz.

Extensive bone loss, as encountered in both revision arthroplasty of the hip and after resection of malignant tumors of the pelvis, is a major challenge for the surgeon as well as for the revision implant. The aims are, despite extensive acetabular defects, to achieve a primary and load-stable fixation of the revision prosthesis in the pelvic bone as well as restoring the physiological joint biomechanics. At present, a large number of different alloarthroplastic revision implants and complex techniques are available for reconstruction of acetabular deficiencies. According to D'Antonio's classification of acetabular defects, particularly high-grade defects with loss of the posterior column or a pelvic discontinuity require special attention regarding implant selection and surgical planning. The object of this paper is to highlight the most important tools and techniques of endoprosthetic reconstruction for grade III and IV defects (D'Antonio) of the acetabulum by means of a classification-oriented therapeutic concept and to discuss the pros and cons of the particular implant.

Bicompartmental individualized knee replacement : Use of patient-specific implants and instruments (iDuo™).

OBJECTIVE: Bicompartmental knee replacement in patients with combined osteoarthritis (OA) of the medial or lateral and patellofemoral compartment. Patient-specific instruments and implants (ConforMIS iDuo™) with a planning protocol for optimal implant fit. INDICATIONS: Bicompartmental OA of the knee (Kellgren & Lawrence stage IV) affecting both the medial or lateral and patellofemoral compartment after unsuccessful conservative or joint-preserving surgery. CONTRAINDICATIONS: Tricompartmental OA, knee ligament instabilities, knee deformities >15° (varus, valgus, extension deficit). Relative contraindication: body mass index >40; prior unicompartmental knee replacement or osteotomies. SURGICAL TECHNIQUE: Midline or parapatellar medial skin incision, medial arthrotomy; identify mechanical contact zone of the intact femoral condyle (linea terminalis); remove remaining cartilage and all osteophytes that may interfere with the correct placement of the individually designed instruments. Balance knee in extension with patient-specific balancing chips. Resection of proximal tibia with an individual cutting block; confirm axial alignment using an extramedullary alignment guide, balance flexion gap using spacer blocks in 90° flexion. Final femur preparation with resection of the anterior trochlea. After balancing and identification of insert heights, final tibial preparation is performed. Implant is cemented in 45° of knee flexion. Remove excess cement and final irrigation, followed by closure. POSTOPERATIVE MANAGEMENT: Sterile wound dressing; compressive bandage. No limitation of active/passive range of motion (ROM). Partial weight bearing the first 2 weeks, then transition to full weight bearing. Follow-up directly after surgery, at 12 and 52 weeks, then every 1-2 years. RESULTS: In all, 44 patients with bicompartmental OA of the medial and patellofemoral compartment were treated. Mean age 59 years. Minimum follow-up 12 months. Implant converted to TKA due to tibial loosening (1 patient); patella resurfacing (3 patients). No further revisions or complications. Radiographic analyses demonstrated ideal fit of the implant with less than 2 mm subsidence or overhang. KSS pain scores improved from preoperatively 5.7 to 1.7 postoperatively with level walking, and from 7.3 preoperatively to 2.8 postoperatively with climbing stairs or inclines. The WOMAC score improved from preoperatively 43 to 79 postoperatively.