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.

Numerical investigations of stress shielding in total hip prostheses.

Aseptic loosening of the prosthesis is still a problem in artificial joint implants. The loosening can be caused by, among other factors, resorption of the bone surrounding the prosthesis owing to stress shielding. In order to find out the influence of the prosthesis type on post-operative stress shielding, a static finite element analysis of a femur provided with the conventional uncemented stem BICONTACT and of one with the femoral neck prosthesis SPIRON was carried out. Strain energy densities and maximal principal strain distributions were calculated and compared with the physiological situation. Here, stress shielding was demonstrated in both periprosthetic femora. To determine the areas of the stress shielding, the bone in each FE model was subdivided into three regions of interest (ROI): proximal, diaphyseal, and distal. The numerical computations show stress shielding in the proximal ROI of both periprosthetic femora. Diaphyseally, the femoral neck prosthesis SPIRON, in contrast to the conventional uncemented long-stem prosthesis BICONTACT, causes no decrease in the strain distribution and thus no stress shielding. Distally, no change in the load distribution of either periprosthetic femur could be found, compared with the physiological situation.

[Radiologic evaluation of cup placement variation in conventional total hip arthroplasty]. / Radiologische Evaluation der Variationsbreite der Pfannenpositionierung bei konventioneller Hüftendoprothesenversorgung.

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.

[Influence of the postoperative activity level on tibial bone tunnel enlargement and functional treatment results following anterior cruciate ligament reconstruction using a patellar tendon autograft]. / Der Einfluss des postoperativen Aktivitätsgrades auf die tibiale Bohrkanalerweiterung und das funktionelle Behandlungsergebnis nach vorderer Kreuzbandplastik mit Patellarsehnendrittel.

AIM: This study was performed to evaluate the influence of the postoperative activity level on tibial bone tunnel enlargement following anterior cruciate ligament reconstruction using a mid-third patellar tendon autograft. METHODS: A clinical and radiological assessment was performed on 50 patients (21 male, 29 female, mean age 32 years, range 18 to 57 years) following ACL reconstruction using a patellar tendon autograft. The average follow-up examination was performed 18 (12 to 30) months after the operation. RESULTS: 33 patients (66 %) developed a tibial bone tunnel enlargement > 1 mm. We found a positive correlation (+ 0.59) of the grade of activity and the muscle status (+ 0.56) to the tibial bone tunnel enlargement. Patients with a major tibial bone tunnel enlargement performed at a higher (p < 0.05) postoperative activity grade (5.2 versus 4.1 in the Tegner grading), rated higher in the Lysholm (88 versus 77 points) and IKDC scores (p < 0.05) and reported a better subjective functional outcome (p < 0.05). There was no significant correlation of the results of the knee stability tests and the age of the patients to the grade of tibial bone tunnel enlargement. CONCLUSIONS: In ACL reconstruction using a patellar tendon autograft we recommend early rehabilitation as the concomitant tibial bone tunnel enlargement does not significantly influence the clinical outcome or knee stability.

[Results of hip arthroscopy in sports related groin pain]. / Ergebnisse der Hüftarthroskopie bei sportabhängigen Leistenschmerzen.

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.

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.

[Effects of harvesting the central third of the patella tendon on the kinetics of the knee joint and the retropatellar pressure]. / Auswirkungen der Entnahme des mittleren Patellarsehnendrittels auf die Kinematik des Kniegelenkes und den retropatellaren Druck.

AIM: This biomechanical study was performed to evaluate the consequences of removing the central part of the patellar tendon on the kinematics and kinetics of the femoro-patellar joint. The tendonectomy was performed in the same manner as is frequently done during anterior cruciate ligament reconstructions. Of particular interest in this study was to identify potential factors of the patellar tendon resection which could result in anterior knee pain. METHOD: A simulated isokinetic knee extension from 120 degrees of flexion to full extension was performed on nine human knee cadaver specimens. Joint kinematics was evaluated with ultrasound sensors, and retropatellar contact pressure was measured using a thin-film resistive ink pressure measuring system. Data were taken before and after resection of the central third of the patellar tendon. RESULTS: Harvesting of the central third of the patellar tendon resulted in an elongation of the remaining patellar tendon by less then 0.5 mm. Furthermore, increases in patellar flexion lower than 1 degree were observed. Small changes in retropatellar pressure were also observed. CONCLUSION: The shortening of the patellar tendon due to tendon removal, as already suggested in several previous studies, is not attributed to the removal of the central portion of the tendon itself, but more likely due to secondary scarring contraction of the tissue. The changes of the patellarkinematics and the retropatellar pressure observed in this study are probably not of any clinical significance.

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.

Evaluation of the learning curves associated with uncemented primary total hip arthroplasty depending on the experience of the surgeon.

The aim of the paper is to prove and to portray the learning curve in total hip arthroplasty. This prospective study included 168 patients who were operated on by three surgeons, all demonstrating different degrees of experience in performing total hip arthroplasty. Perioperative complications and postoperative radiographs were analysed. Patients were re-examined clinically and radiologically five years postoperatively. In addition, a second study with 41 patients was performed, evaluating especially the learning curve of the highly skilled surgeon in using a femoral neck prosthesis. Radiological complications presented by the first 84 operated patients (2 nd study: 25 hips) were significantly higher than those in the following 84 patients (2 nd study: 26 hips). The learning curve of all surgeons was completed after 20 operations regardless of their experience. Clinical results at follow-up were not influenced by the learning curve. Intensive preoperative planning and exchange of experiences will reduce the length of the learning curve within and outside every clinic.

[Treatment of incomplete meniscal lesions in athletes]. / Die Therapie des inkompletten Meniskusrisses beim Sportler.

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.

[Navigator concept. Optimizing the procedure for navigated total knee arthroplasty]. / Das Navigatorkonzept. Prozessoptimierung in der navigierten Knieendoprothetik.

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.

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.

[Patellofemoral pain syndrome]. / Patellofemorales Schmerzsyndrom.

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.

[Meniscus replacement with quadriceps tendon--a long-term analysis]. / Der Meniskusersatz mit autologer Quadrizepssehne -- eine Langzeitanalyse.

AIM: Early osteoarthritis of the knee is a common consequence ofA'complete meniscectomy. In order to prevent degenerative changes, meniscus replacement by autogenous quadriceps tendon was performed from 1986 until 1999 in 45 patients. In 29 patients, a reconstruction of the anterior cruciate ligament was done simultaneously. This study was intended to detect whether this meniscus replacement led to better subjective, clinical and radiological results in comparison to meniscectomised knees or meniscal allografts reported in the literature. METHODS: A standardised examination of the patients (4-17 years postoperatively, average 9 years) was carried out using the KOOS questionnaire, the IKDC examination form and a weight-bearing radiograph of the knee. RESULTS: 34 patients took part in the study. KOOS subgroups showed fair results for symptoms (25-96 points, average 65), butA'bad results for sports and quality of life (0-100, average 52; QoL 6-94, average 54). Clinical and radiological examination demonstrated on average stable knee joints without effusion (IKDC group A), but X-rays showed in most cases a clear or severe osteoarthritis of the knee (IKDC group C). Clinical and radiological findings demonstrated similar results in comparison with studies investigating results after meniscectomy without meniscus replacement. Concerning subjective results, meniscus replacement with quadriceps tendon was inferior to cryopreserved meniscal allografts. However, patients after meniscal allograft transplantation also show increasing degenerative changes of the respective joint in radiological follow-up studies. CONCLUSION: In the patient group studied here with pre-existing chondromalacia of the respective knee joint compartment and preoperative anterior instability, no advantage of meniscus replacement using quadriceps tendon over the normal course after meniscectomy could be proven. Therefore, this procedure cannot be generally recommended.

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.

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.

[Injectable carrier system for growth factor application in minimally invasive stimulation of bone healing]. / Injizierbare Trägersysteme für die Wachstumsfaktorapplikation zur minimal-invasiven Knochenheilungsstimulation.

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.