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Biomedical subjects

C J Wirth

Publications and source records attributed to C J Wirth.

At least 19 recordsLinked to original sources
PubMed2007

[Radiologic evaluation of cup placement variation in conventional total hip arthroplasty].

PURPOSE: Determination of the amount of variation in conventional acetabular cup positioning (radiological inclination and anteversion) in view of different factors that could influence the measured angles. MATERIALS AND METHODS: The intended acetabular cup position of 45 degrees inclination and 20 degrees anteversion was checked radiologically in 950 patients who received a cementless total hip replacement. The qualifications of the surgeon, operated side and implant model were recorded and analyzed with respect to a possible correlation with the results. Since a "safe angle" cannot be defined without consideration of other variables, a tolerable deviation of the target position was investigated. RESULTS: The mean inclination angle was 48.7 degrees (SD 7 degrees, minimum 28 degrees, maximum 75 degrees ). Anteversion was measured with a mean of 18.6 degrees (SD 9 degrees, minimum -9 degrees, maximum 50 degrees ). Assuming an acceptable deviation of +/- 5 degrees from the target position (45 degrees inclination and 20 degrees anteversion), only 22.7 % of the acetabular cups were in this range. In the case of an acceptable deviation of +/- 10 degrees, 34.5 % of the cups were still outside of the acceptable range. The qualifications of the surgeon, the implanted model, as well as the operated side did not have a significant influence on the results. CONCLUSION: The common implantation technique yielded significant variation with respect to anteversion and inclination. The application of computer-aided navigation in the placement of acetabular cups would help to improve accuracy and reproducibility considerably in total hip arthroplasty.

Acetabulum↗
PubMed2006

Chronic symptomatic proximal tibiofibular instability in a 3-year-old girl.

A 3-year-old girl was presented with recurrent pain at the right knee and a "snapping" when walking. A free range of motion of both knee joints, stable cruciate and collateral ligaments and a ventrally subluxating and snapping fibula when flexing the knee were found. Due to a longer course of recurrent subluxation and pain, an operation was performed and the tibiofibular ligaments and joint capsule were tightened by sutures. Other operative techniques proposed in the literature are discussed; most of them could lead to deformities or growth disturbances. The reports of tibiofibular instability in the literature are presented. The girl is the youngest patient with idiopathic proximal tibiofibular instability reported in the literature at least in the last 75 years.

Child, Preschool↗
PubMed2006

[Results of hip arthroscopy in sports related groin pain].

INTRODUCTION: The study analyses the intraoperative findings and the clinical results of hip arthroscopy in sports related groin pain. METHODS: Between june 1998 and october 2002 we performed hip arthroscopy in 30 athletes (12 female, 18 male) with a history of sports related groin pain. Their average age was 36 (20 to 68) years. All patients had a clinical follow-up- examination at an average of 20 (12 to 48) months postoperative. The result was rated using the Larson-Score. RESULTS: We found a lesion of the acetabular labrum and performed a partial resection at 17 patients (57 %) (synovitis: n = 28 [93 %] loose bodies: n = 6 [20 %] torn ligamentum teres: n = 4 [13 %], others: n = 2 [6 %]). 11 patients (37 %) had a cartilage degeneration grade II in the Outerbridge classification (III degrees : n = 9 [30 %], I degrees : n = 4 [13 %], 0 degrees : n = 6 [20 %]). Preoperative 14 patients (47 %) complained severe groin pain (moderate: n = 14 [47 %], slight: n = 2 [6 %]) against only 3 patients (10 %) with severe groin pain at the follow-up examination (moderate: n = 11 [37 %], slight: n = 16 [53 %]). Following hip arthroscopy 28 patients (94 %) returned to full sports activity. The Larson-Score was increased significantly (p < 0.05) rating 43 (10 to 64) points preoperative to 59 (28 to 80) points at the follow-up. DISCUSSION: We found that persistent sports related groin pain was frequently caused by an intraarticular hip disorder. Following hip arthroscopy pain could be reduced in most patients as a return to full sports activity.

Abdominal Pain↗
PubMed2005

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.

Animals↗
PubMed2005

[Patellofemoral pain syndrome].

The patellofemoral pain syndrome is of high socioeconomic relevance as it most frequently occurs in young working patients. As its etiology is often unknown there is no standard treatment protocol. Several studies analyzed the different causes of patellofemoral pain and their different therapies. Static problems (pes planovalgus, instabilities, leg length differences) or chronic overuse of the knee extensor mechanism have to be identified and treated. After exclusion of intra-articular pathologies, the treatment of patellofemoral pain syndrome begins with conservative management. Stretching of the flexor and extensor muscles and training of the quadriceps muscle are the main approaches. If conservative treatment fails and patellofemoral pain persists, there are several surgical procedures for realignment of the patella in the trochlear groove and reduction of the patellofemoral pressure. Overweight patients exhibit chronic mechanical overuse of the patellofemoral joint. This leads to a higher rate of cartilage degeneration and problems at the inserting tendons and stabilizing tissues.

Arthralgia↗
PubMed2005

[Navigator concept. Optimizing the procedure for navigated total knee arthroplasty].

BACKGROUND: This study addresses work sharing during navigation-assisted total knee arthroplasty. Specifically, the concept is introduced of a "navigator" assistant who operates the navigation system during surgery while the surgeon concentrates on the primary steps of surgery. METHODS: In a prospective study of 40 total knee arthroplasties, one group of patients was treated using the navigator concept, a second group was treated using a conventional navigation setup, and a third group was treated with conventional internal and external alignment jigs. Surgery time and outcome parameters were compared. RESULTS: Results show a significant difference in surgery time between the three groups. The conventional and navigator concept groups showed similar surgery times; however, the navigation group without navigation concept exhibited longer surgery time. CONCLUSIONS: The navigator concept represents a highly effective principle to minimize surgery time needed during navigated total knee arthroplasty.

Algorithms↗
PubMed2005

Cell-based treatment of osteochondral defects in the rabbit knee with natural and synthetic matrices: cellular seeding determines the outcome.

INTRODUCTION: Matrix-associated transplantation of cartilage constructs is an appealing method in cartilage repair. Three different matrices seeded with allogenic chondrocytes were compared in an osteochondral defect model in the rabbit. An investigation was conducted to identify the best matrix for cell-based treatment of osteochondral defects in the rabbit knee joint. MATERIALS AND METHODS: Osteochondral defects (diameter 3 mm) were created in the trochlea and the femoral condyles of 33 New Zealand White rabbits, which were then treated with bioartificial cartilage constructs. The cartilage constructs were created in vitro using three different resorbable carrier materials (two fleece matrices: one of PLLA, and one composite of polydioxanon/ polyglactin, as well as one consisting of lyophilized dura) cultured with isolated allogenic chondrocytes. The defects were evaluated macroscopically, by histological and immunhistological techniques, and by scanning electron microscopy after 6 weeks, 6 months, and 12 months. The chondrocyte-seeded constructs were compared to defects treated with carrier material alone as well as to untreated control defects. RESULTS: There was a significant improvement in defect repair quality in the transport materials, which were cultured with chondrocytes prior to implantation (P < 0.0005). No significant differences were observed between the three carrier matrices, and no significant differences were seen between the unseeded matrices and the untreated control defects. CONCLUSION: There is no difference in the outcome between the three tested matrices in the treatment of osteochondral defects in the rabbit knee. The results of this in vitro experiment are promising and with refinement may lead to useful clinical therapies.

Animals↗
PubMed2005

In vivo corrosion of four magnesium alloys and the associated bone response.

Degrading metal alloys are a new class of implant materials suitable for bone surgery. The aim of this study was to investigate the degradation mechanism at the bone-implant interface of different degrading magnesium alloys in bone and to determine their effect on the surrounding bone. Sample rods of four different magnesium alloys and a degradable polymer as a control were implanted intramedullary into the femora of guinea pigs. After 6 and 18 weeks, uncalcified sections were generated for histomorphologic analysis. The bone-implant interface was characterized in uncalcified sections by scanning electron microscopy (SEM), element mapping and X-ray diffraction. Results showed that metallic implants made of magnesium alloys degrade in vivo depending on the composition of the alloying elements. While the corrosion layer of all magnesium alloys accumulated with biological calcium phosphates, the corrosion layer was in direct contact with the surrounding bone. The results further showed high mineral apposition rates and an increased bone mass around the magnesium rods, while no bone was induced in the surrounding soft tissue. From the results of this study, there is a strong rationale that in this research model, high magnesium ion concentration could lead to bone cell activation.

Absorbable Implants↗
PubMed2005

[Treatment of incomplete meniscal lesions in athletes].

PURPOSE: Arthroscopic treatment of complete meniscal lesions is well established. Nevertheless there is discussion, how to treat incomplete meniscal tears, especially in younger and active patients. This study was designed to evaluate our standard-therapy without refixation of the meniscus. METHOD: Between 7/89 and 3/01 in 47 patients (48 knees, Ø age 29 years) an incomplete meniscal lesion following sports injury was found. The lesions were revitalized by "needling" or shaving. We performed no refixation. All patients had a postoperative flexion limit in an orthosis for 6 weeks. The follow-up examination was performed 6.5 (2 - 14) years postoperative. RESULTS: The avarage Lysholm-Score increased significantly from 55 points preoperative to 92 points at the follow-up examination. The Tegner-Score increased from 3.3 points preoperative to 6.2 points at the follow-up examination. The overall result was rated "exellent" and "good" by 83 % of the patients, "fair" by 15 % of the patients and "poor" by 2 % of the patients. Return to sports activity was possible at an avarage of 7 (3 - 12) months postoperative. CONCLUSIONS: In summary we found, that shaving and "needling" of an incomplete meniscal lesion in combination with partial synovectomi and standardized postoperative treatment leads to a high healing rate. A limited flexion for 6 weeks postoperativ in an orthosis at full weight bearing is recommended. In case of complete healing of the lesion the chondroprotective and joint stabilizing function of the meniscus, especially in young and active patients is obtained.

Adolescent↗
PubMed2005

Trapezius transfer in brachial plexus palsy. Correlation of the outcome with muscle power and operative technique.

Between March 1994 and June 2003, 80 patients with brachial plexus palsy underwent a trapezius transfer. There were 11 women and 69 men with a mean age of 31 years (18 to 69). Before operation a full evaluation of muscle function in the affected arm was carried out. A completely flail arm was found in 37 patients (46%). Some peripheral function in the elbow and hand was seen in 43 (54%). No patient had full active movement of the elbow in combination with adequate function of the hand. Patients were followed up for a mean of 2.4 years (0.8 to 8). We performed the operations according to Saha's technique, with a modification in the last 22 cases. We demonstrated a difference in the results according to the pre-operative status of the muscles and the operative technique. The transfer resulted in an increase of function in all patients and in 74 (95%) a decrease in multidirectional instability of the shoulder. The mean increase in active abduction was from 6 degrees (0 to 45) to 34 degrees (5 to 90) at the last review. The mean forward flexion increased from 12 degrees (0 to 85) to 30 degrees (5 to 90). Abduction (41 degrees) and especially forward flexion (43 degrees) were greater when some residual function of the pectoralis major remained (n = 32). The best results were achieved in those patients with most pre-operative power of the biceps, coracobrachialis and triceps muscles (n = 7), with a mean of 42 degrees of abduction and 56 degrees of forward flexion. Active abduction (28 degrees) and forward flexion (19 degrees) were much less in completely flail shoulders (n = 34). Comparison of the 19 patients with the Saha technique and the 15 with the modified procedure, all with complete paralysis, showed the latter operation to be superior in improving shoulder stability. In all cases a decrease in instability was achieved and inferior subluxation was abolished. The results after trapezius transfer depend on the pre-operative pattern of paralysis and the operative technique. Better results can be achieved in patients who have some function of the biceps, coracobrachialis, pectoralis major and triceps muscles compared with those who have a complete palsy. A simple modification of the operation ensures a decrease in joint instability and an increase in function.

Adolescent↗
PubMed2004

[The brachial plexus lesion. Management, consequences of palsy and reconstructive operations].

The treatment of traumatic brachial plexus lesions follows sequential steps. After acute therapy (phase I), neurological diagnostics (phase II), neurosurgery and postoperative treatment (phase III/IV), reconstructive operations (phase V) can be indicated and performed. In most cases an insufficient grade of muscle power remains. Within 6 months after injury, neurosurgery must be performed in patients with brachial plexus palsy. After malfunction of the muscles, taking into account the individual neuromuscular defects, passive joint function and bony deformities, different procedures such as muscle transposition, arthrodesis and corrective osteotomy can be performed to improve the function of the upper extremity. The treatment of patients suffering from brachial plexus lesion requires interdisciplinary teamwork.

Adolescent↗
PubMed2004

[Shoulder arthrodesis. Indications, techniques, results, complications].

Besides the paralysis of shoulder muscles, large rotator cuff tears beyond repair, persistent shoulder instability with repeat dislocations and resection cases are recent indications for shoulder arthrodesis. The fusion of the shoulder is particularly useful since, despite immobilization of the glenohumeral and acromiohumeral joints, no loss of function is experienced; on the contrary, in many cases an increase of active total mobility may occur. According to the functional outcome, the majority of reports vary between 30 degrees and 90 degrees of active abduction and forward flexion with a mean value of about 60 degrees The most generally accepted arthrodesis position is 20 degrees -40 degrees abduction, forward flexion and internal rotation in relation to the trunk. This position results in a maximum development of muscle power and ensures that the arm will rest comfortably at the side, and that the scapula will not protrude. This also allows the hand to reach the head and facial region. The literature is not confined to any uniform type of arthrodesis and it would appear that the techniques and configurations of material vary considerably. A general advantage of any one particular form of arthrodesis, and the use of plates, screws or external fixators, cannot be deduced. Pseudarthrosis appears to be less frequent in cases of plate arthrodesis compared to screw arthrodesis. However, the application of plates more often results in infections, postoperative fractures of the humerus and the necessary removal of material. Screw arthrodesis is more beneficial in that the exposed area to be operated is smaller than in plate arthrodesis. Postoperative immobilization is more time consuming and, therefore, constitutes one of the disadvantages of screw fixation.

Adolescent↗
PubMed2004

[Injectable carrier system for growth factor application in minimally invasive stimulation of bone healing].

The characterization and cloning of growth factors for bone healing provide an enormous potential for minimally invasive treatment procedures for bone defects or fractures. However, the clinical application of injection vehicles for these growth factors must be made user-friendlier. In this study, two different injection vehicles were tested for their practicability and efficacy to enhance callus maturation during distraction osteogenesis. Calcium phosphate carriers showed a rather low user-friendliness and were less efficient in the animal model of distraction osteogenesis in sheep. Collagen carriers provided both a higher practicability for injection procedures and a higher efficacy.

Animals↗
PubMed2003

[Open versus arthroscopic shoulder stabilization. An analysis of the treatment costs].

In this study the total costs of clinical open and arthroscopic anterior shoulder stabilization were evaluated, analyzed and compared. From 1988 to 1998 147 patients underwent open (Bankart) or arthroscopic (ASK) anterior shoulder stabilization. We randomized two groups of 30 patients for each method (Bankart: 25 male, 5 female, 29 years of age; ASK: 25 male, 5 female, 26 years of age) and evaluated the costs of their clinical treatment. The total cost was significantly ( p<0.05, Mann-Whitney U-Test) higher for the open (5639 euro) than for the arthroscopic (4601 euro) therapy. There was a significant difference between the groups for the average cost of surgery (Bankart: 2741 euro; ASK: 2315 euro, p<0.05) and the average postoperative treatment cost (Bankart: 2202 euro; ASK: 1630 euro, p<0.05) whereas the average preoperative treatment cost was not significantly different (Bankart: 669 euro, ASK: 657 euro). The staff costs for the surgical procedure (Bankart: 1800 euro (32%), ASK: 1319 euro (29%)) and the postoperative staff costs of the nurses (Bankart: 1271 euro (23%), ASK: 997 euro (22%)) represented the greatest parts of the total costs. The average duration of the clinical treatment was 15.8 days for the open- and 12,4 days for the arthroscopic group.

Adult↗
PubMed2003

[Dynamic in vitro measurement of retropatellar pressure after knee arthroplasty].

The purpose of this study was to examine the contact pressure between the patellofemoral interface of the physiologic, native, and prosthetic patella and the femoral component in total knee arthroplasty. An electronic sensor was used to measure contact pressure in five cadaver knees. The average peak contact pressure measured on the prosthetic patella was 9.8 MPa and was significantly higher than the physiologic and native patella. Average peak contact pressures increased with flexion. Although contact pressure reflects only a part of the dynamics of the patellofemoral articulation, these data support the selective retention of the native patella in total knee arthroplasty. Nevertheless, besides the indication for prosthetic replacement of the patella, design and operative techniques should also be part of the discussion.

Aged↗