[Pain concepts in fast-track endoprosthetics]. / Schmerzkonzepte in der Fast-Track-Endoprothetik.

An effective and safe pain management is nowadays a pivotal component of fast-track endoprosthetics. The analgesic strategies should be opioid-sparing whenever possible because opioids induce side-effects that reduce the well-being of patients and are even associated with a risk of falling. This is not compatible with a fast mobilization. In order to achieve this goal, multimodal pain concepts have proven to be suitable. Decentralized analgesia with epidural and regional catheters as well as the use of local infiltration anesthesia (LIA) can be used; however, catheters are also associated with a muscular deficit and the danger of falling. Therefore, in the fast-track concepts LIA has become established. With respect to knee endoprosthetics many studies have shown that LIA achieves at least comparable results or even superiority in comparison with the use of catheters. It represents a safe and effective procedure with respect to postoperative analgesia and accelerated mobilization. A variety of protocols for the use of LIA can currently be found in the literature. In addition to analgesics the supportive administration of glucocorticoids is increasingly being used, which also reduce pain due to the anti-inflammatory effect; however, regarding this aspect relatively few prospective randomized studies in comparison to LIA are available in the literature.

[Experience in establishing a certified endoprosthesis center]. / Erfahrungen mit der Einrichtung eines zertifizierten Endoprothesenzentrums.

BACKGROUND: It is well known that morbidity rates of arthroplasties are inversely related to procedure volume. In the department of orthopaedics at a German medical school, a performance of certification of high-volume center for total hip and knee arthroplasties, called the EndoCert(®) Initiative, was started. This project was initiated by the German society of orthopaedic surgery (DGOOC) to secure the quality of total knee and hip arthroplasties. OBJECTIVES: The aim of this study is to evaluate effects of certification, pathwaycontrolled therapy and quality indicators on outcome in arthroplasty three years after implentation. MATERIALS AND METHODS: Arthroplasties performed in this certified center for total hip and knee arthroplasties were evaluated. Outcome was evaluated after the implementation of quality indicators and clinical pathways. RESULTS: After establishment of certification in the center for total hip and knee arthroplasties morbidity rates decreased as quality increased. CONCLUSION: The implementation of pathway-controlled therapy and quality indicators in a high-volume center for total joint arthroplasties shows better clinical results. Capital investment and efforts are legitimated.

Effects of perfusion and cyclic compression on in vitro tissue engineered meniscus implants.

PURPOSE: The purpose of this study was to investigate the influence of continuous perfusion and mechanical stimulation on bone marrow stromal cells seeded on a collagen meniscus implant. METHODS: Bone marrow aspirates from 6 donors were amplified in vitro. 10(6) human BMSC were distributed on a collagen meniscus implant. Scaffolds were cultured under static conditions (control) or placed into a bioreactor system where continuous perfusion (10 ml/min) or perfusion and mechanical stimulation (8 h of 10% cyclic compression at 0.5 Hz) were administered daily. After 24 h, 7 and 14 days, cell proliferation, synthesis of procollagen I and III peptide (PIP, PIIIP), histology, and the equilibrium modulus of the constructs were analyzed. RESULTS: Proliferation demonstrated a significant increase over time in all groups (p < 0.001). PIP synthesis was found to increase from 0.1 ± 0.0 U/ml/g protein after 24 h to 2.0 ± 0.5 (perfusion), 3.8 ± 0.3 (mechanical stimulation), and 1.8 ± 0.2 U/ml/g protein (static control, lower than perfusion and mechanical stimulation, p < 0.05). These differences were also evident after 2 weeks (2.7 ± 0.3, 4.0 ± 0.6, and 1.8 ± 0.2 U/ml/g protein, p < 0.01); PIIIP synthesis was found to increase from 0.1 ± 0.0 U/ml/g protein after 24 h to 2.9 ± 0.7 (perfusion), 3.1 ± 0.9 (mechanical stimulation), and 1.6 ± 0.3 U/ml/g protein (controls) after 1 week and remained significantly elevated under the influence of perfusion and mechanical stimulation (p < 0.01) after 2 weeks. Mechanical stimulation increased the equilibrium modulus more than static culture and perfusion after 2 weeks (24.7 ± 7.6; 12.3 ± 3.7; 15.4 ± 2.6 kPa; p < 0.02). CONCLUSION: Biomechanical stimulation and perfusion have impact on collagen scaffolds seeded with BMSCs. Cell proliferation can be enhanced using continuous perfusion and differentiation is fostered by mechanical stimulation.

[Periprosthetic fractures around the knee]. / Periprothetische Frakturen rund um das Knie.

BACKGROUND: Periprosthetic fractures of the knee joint are complex injuries and frequently represent a challenge for the surgeon. OBJECTIVE: The aim of this review is to present and discuss the current classification and treatment options for periprosthetic knee fractures. MATERIAL AND METHODS: A selective review of the existing literature on periprosthetic fractures around the knee was performed in PubMed. The various classifications and treatment regimens are discussed with respect to the advantages and disadvantages and from this knowledge a new algorithm was developed. RESULTS: The classifications of periprosthetic fractures have changed in recent years and have been replaced by a uniform fracture classification; however, not only the radiological evaluation of the fractures is crucial to determine the treatment regimen for periprosthetic fractures. A thorough evaluation of the inserted endoprosthesis should be carried out in order to be able to decide between the treatment options of osteosynthesis and revision arthroplasty. Treatment options are available for osteosynthesis and revision arthroplasty that enable a safe treatment of these complex injuries. CONCLUSION: Periprosthetic fractures of the knee joint are complex injuries, requiring a thorough preoperative planning and an interdisciplinary treatment with trauma and endoprosthetic expertise.

An alternative treatment method to restore limb-length discrepancy in osteoarthritis with high congenital hip dislocation.

AIM: The purpose of this study was to describe the rationale and to analyse the results of uncemented total hip arthroplasty (THA) in patients with osteoarthritis and congenital dislocation of the hip (CDH) prior to iliofemoral distraction. METHOD: Twenty hips were followed-up for 5.8 years (1-12 years). First the THA components were implanted after soft tissue release. In the interval, iliofemoral distraction with an external distraction apparatus was conducted. The second surgery consisted of an open reduction. An iliofemoral distraction of 0.8 mm/day was monitored. The treatment time was 86 days (50-210 days). In 61 days (32-94 days) the hip joints were distracted for 51 mm (41-75 mm). RESULT: The Harris Hip Score increased significantly by 47 points. The SF-36 health score showed a satisfying increase in all patients. CONCLUSION: In experienced hands this method is a relatively safe procedure for limb-length equalization in patients with severe CDH.

[Ex vivo microCT analysis of possible microfractures of the femoral head during implantation of a cementless hip resurfacing femoral component]. / Ex-vivo-microCT-Untersuchungen zu möglichen Mikrofrakturierungen des Hüftkopfs bei der Implantation eines zementfreien Oberflächenersatzes am Hüftgelenk.

AIM: Microfractures of the femoral head during implantation of the femoral components are suspected to be a cause of fractures at the implant/neck junction which represent a common failure mode in hip resurfacing arthroplasty. Callus formation observed in femoral head retrievals suggests the occurrence of microfractures inside the femoral head, which might be inadvertently caused by the surgeon during implantation. The aim of this biomechanical study was to analyse whether or not the implantation of a cementless femoral component hip resurfacing system causes microfractures in the femoral head. METHOD: After the preparation of 20 paired human cadaveric femoral heads, the cementless femoral component ESKA Typ BS (ESKA Implants GmbH & Co., Lübeck) was implanted on 9 specimens with an impaction device that generates 4.5 kN impaction force. On 9 specimens the femoral component was implanted by hand. One head was used as a fracture model, 1 specimen served as control without manipulation. The femoral component used for impaction was equipped with hinges to enable its removal without further interfering with the bone stock. Specimens were scanned with a microCT device before and after impaction and the microCT datasets before and after impaction were compared to identify possible microfractures. RESULTS: Twenty strikes per hand or with the impaction device provided sufficient implant seating. Neither the macroscopic examination nor the 2-dimensional microCT analysis revealed any fractures of the femoral heads after impaction. CONCLUSION: At least macroscopically and in the 2-dimensional microCT analysis, implantation of the cementless hip resurfacing femoral component ESKA Typ BS with 4.5 kN or by hand does not seem to cause fractures of the femoral head.

[Intraoperative femoral fractures during the implantation of the cementless BiCONTACT stem: a matched-pair analysis of 84 patients]. / Intraoperative Femurfrakturen bei der Implantation des zementfreien BiCONTACT-Schaftes: eine Matched-Pair-Analyse von 84 Patienten.

AIM: Intraoperative periprosthetic femoral fractures (PFF) during the implantation of primary non-cemented total hip arthroplasties (THA) are an increasing problem. Thus, the goal of this study was to analyse the postoperative performance of primary non-cemented THA in patients with intraoperative PFFs, with respect to the patient's subjective health-related satisfaction. METHOD: 42 PFFs in 1216 primary THAs using the non-cemented BiCONTACT stem were monitored. Patients were compared to a control group of 42 non-cemented THA patients without intraoperative fracture complications, using the matched-pair analysis. Preoperative and after 2.2 years (0.8-3.2 years), patients were followed-up clinically and radiographically. Clinical parameters were Harris hip score, SF-36 health score, function and pain score and postoperative complications. Radiographic parameters were bone union, stem and trochanter migration. Fractures were graded using the Vancouver classification. RESULTS: Results showed a significant increase in both Harris hip score and motion score and a significant decrease in pain score in both groups (p<0.001). The SF-36 health score increased significantly in nearly every dimension in both groups. Except for 2 patients with trochanter migrations of 25 and 20 mm, all fractures showed bony union. In 3 patients the stems subsided by 4.7 +/- 2.9 mm. The stems showed no further migration at final follow-up. 2 patients without intraoperative fractures underwent stem revision. Overall increases and postoperative complication rates were not significantly different between the groups. CONCLUSION: Mid-term THA performance and patient satisfaction are not influenced by intraoperative Vancouver A and B1 fractures during implantation of the non-cemented BiCONTACT stem compared to a collective without intraoperative fractures during implantation.

The uncemented primary Bicontact stem in revision total hip arthroplasty in young patients.

AIM: The purpose of this study was to evaluate the uncemented primary Bicontact stem (B.Braun-Aesculap, Tuttlingen, Germany) as a possible adequate alternative to other revision systems in revision total hip arthroplasty. METHODS: Twenty patients aged up to 58 years (34-58 years, mean age 5.7 +/- 5.8 years) with minor bone defects underwent a revision total hip arthroplasty with the uncemented primary Bicontact stem. The patients were assessed clinically and radiologically at follow-up (follow-up: 8.0 +/- 3. years). RESULTS: The postoperative Harris Hip Score, Motion and Pain Score improved significantly. There was only one further revision in these patients because of infection and only one case with mild stress shielding. CONCLUSION: The uncemented primary Bicontact stem seems to be a good alternative to other revision systems in total hip revision arthroplasty in young patients.

[Lig. capitis femoris. Arthroscopic diagnosis and treatment of degenerative and traumatic disorders]. / Lig.capitis femoris. Arthroskopische Diagnostik und Behandlung degenerativer und traumatischer Veränderungen.

The LT arises from the transverse acetabular ligament and the posterior inferior portion of the acetabular fossa and attaches to the femoral head at the fovea capitis. Lesions of the LT are accompanied by dislocation or subluxation of the hip as well as acetabular fractures. However, rupture may occur simply from a twisting injury in the absence of major trauma. Atraumatic degeneration associated with osteoarthritis and dysplasia as well as after Perthes' disease and slipped epiphysis capitis can occur. The symptoms of pain, popping, locking, and catching are nonspecific for a variety of intra-articular lesions. Most of the patients complain of deep anterior groin pain, but sometimes simply pain upon activity or loss of motion are described. No examination finding would distinguish injury to the ligament. The diagnosis of rupture of the LT remains elusive to various imaging techniques. Magnetic resonance arthrography is much more sensitive than magnetic resonance imaging at detecting various lesions but has a low sensitivity for ruptures of the LT. Lesions of the LT can be diagnosed using arthroscopy and respond remarkably well to arthroscopic débridement. Long-term results and potential consequences of treatment remain to be defined.

The influence of pre-tensioning of meniscal transplants on the tibiofemoral contact area.

The purpose of the present study was to determine the effect of biological in-growth and pre-tensioning on the load transmission function of meniscal transplants. The ability of meniscal transplants to transfer load to the tibial plateau was measured in an animal model. Thirty-six sheep were divided into six groups: group A was the sham group, in group B a medial meniscectomy was performed, and in groups C-F a medial meniscal transplantation with an autograft was carried out. In groups C-F, different levels of pre-tensioning force were applied via bone tunnel sutures (C=0, D=20, E=40, and F=60 N, respectively). The animals were killed after 6 months. The excised knees were mounted in a materials testing machine at 30, 60, and 90 degrees of flexion, and loaded through the femoral axis to 500 N. A thin film pressure measuring transducer (K-scan, Tekscan) was positioned underneath the meniscus in the medial compartment in order to determine contact area and pressure. The mean contact pressure (MCP) of the sham group (A) and the groups with the transplanted meniscus (C-F) was significantly lower in relation to the meniscectomized knees (B). Significant increases in contact area and reductions in peak contact pressure were also observed. Only the meniscal transplantation group with 40 N (E) pre-tension consistently showed a significant or strong trend toward increased contact area, compared to the meniscectomized knees (B) at all flexion angles tested. All meniscal transplanted groups with the exception of the 0 N group (C) showed a significant reduction in peak contact pressure in comparison to the meniscectomized group (B). The results indicate that meniscal transplantation reduces the MCP on the tibial plateau independent of the level of intraoperative pre-tensioning. Furthermore, the menisci pre-tensioned to 40 N showed significantly increased contact area and reduced peak contact pressure in comparison to the meniscectomized knees at all flexion angles tested, and revealed results similar to those reported in the literature for meniscal allografts fixated with bone plugs.

Experimental measurement of tibiofemoral contact area in a meniscectomized ovine model using a resistive pressure measuring sensor.

Animal models are necessary for the development and analysis of surgical techniques in meniscal surgery because they are the only means of preclinically determining the influence of biological factors such as healing processes and joint remodeling. Furthermore, little is known about the biomechanical effect of meniscectomy in sheep. The aim of the study was thus to investigate the efficacy of using a resistive pressure measuring sensor to quantify the effect of chronic meniscectomy in an ovine model. Twelve sheep were divided into two groups (n = 6): a sham operated control group (A), and a medially meniscectomized group (B). After six months, lower limb specimens were loaded with a joint-compressive force of 500 N during which the pressure measuring sensor was positioned underneath the meniscus to determine contact area, mean and peak contact pressure. A significant reduction in contact area of about 55% was observed in the meniscectomized knees compared to the controls. Peak contact pressure of the meniscectomized knees significantly increased an average of 260.4% compared to the control knees. Based on the results of this study, we conclude that the resistive pressure measuring sensors provide a means to experimentally measure tibiofemoral contact mechanics even in this relatively small (compared to human) animal model.