Ulf Leichtle

The effect of different quadriceps loading patterns on tibiofemoral joint kinematics and patellofemoral contact pressure during simulated partial weight-bearing knee flexion

PurposeThe purpose of this in vitro study was to investigate the influence of different quadriceps loading patterns on tibiofemoral joint kinematics and patellofemoral pressure.MethodsA dynamic muscle-loaded knee squat was simulated on eight knee specimens with an upright knee simulator while measuring tibiofemoral joint kinematics and patellofemoral pressure distribution. The quadriceps muscle was attached to three actuators simulating the three main extensor muscles, and five different quadriceps loading patterns were tested.ResultsTibial axial and varus-valgus-rotation are affected most while changing quadriceps loading patterns from lateral to medial. Higher internal tibial rotation is associated with higher medial muscle load compared to the symmetrical loading condition. Contact force, contact area and maximum peak pressure rise with increasing flexion angles. Accentuating the vastus lateralis muscle induces a significant reduction in patellofemoral contact force and a 30% diminished contact area at 90° of flexion.ConclusionStrengthening the vastus medialis muscle leads to increased internal tibial rotation, thus optimizing patella tracking by lowering the Q-angle. In contrast, weakness of the vastus medialis muscle causes decreased tibial internal rotation and is associated with lower patellofemoral contact pressure and contact area. Vastus medialis exercise is advisable to improve patella tracking but may not be recommended in patients with disorders due to increased patellofemoral contact pressure.

Dislocation after total hip arthroplasty: risk factors and treatment options.

OBJECTIVE The aim of this study was to analyze the setting for dislocations and redislocations after primary and revision total hip arthroplasty (THA), identify risk factors and optimize treatment. METHODS This study included 56 patients with a dislocated hip following THA (n=5,205) between 1984 and 2005 and a matched control group (n=55). Hospital charts and radiographs of all patients in both groups were analyzed. Thirty-one patients in the study group were followed both clinically and radiologically. RESULTS The dislocation rate after primary THA was 1.1% (56/5,205) and the redislocation rate after a first occurrence was as high as 39%. There was a positive correlation between the time intervals from the surgery to first dislocation and from the first dislocation to second dislocation (r=0.4). Most of the primary dislocations occurred within a short period of time after surgery, thus favoring consecutive dislocations. Female gender, as well as revision arthroplasty, was associated with a higher incidence of dislocations. No relation was found between the orientation of the acetabular cup and dislocation. CONCLUSION To prevent redislocations after the first occurrence, we suggest thorough evaluation of possible technical faults which should be addressed surgically. Considering the high redislocation rate, we also advocate a stringent conservative treatment regime especially after the first THA dislocation.

The influence of asymmetric quadriceps loading on patellar tracking — An in vitro study

BACKGROUND In patients with anterior knee pain and patellar instability, a specific training of the quadriceps muscle - especially the vastus medialis - is often recommended, although the practicability is discussed controversially and the proof of a measurable clinical effect is difficult. Therefore, this in vitro study investigates the influence of asymmetric muscle loading on the motion of the human patella. METHODS Seven human knee specimens were tested in a specially developed knee simulator. During simulated weight-bearing knee flexion, the kinematics of tibia, femur and patella were measured using an ultrasound motion capture system. The quadriceps forces were controlled to achieve a constant ankle force over the whole flexion range which is assumed to represent almost physiological loading. Three different force distributions of the quadriceps were tested - a central, equally distributed load as well as mainly lateral and medial loads. RESULTS A significant influence of different quadriceps force distributions was found for patellar tilt around a proximodistal axis (up to 1.7°) and patellar rotation around an anteroposterior axis (up to 3.8°) with respect to the femur. Interestingly, the patellar mediolateral shift was influenced only marginally (<1.5mm). CONCLUSIONS Specific muscle training might help patients with patellofemoral pain and cartilage damage by a slight modification of the kinematics, but we could show that even highly asymmetric quadriceps loads only led to a small alteration of the mediolateral shift in case of a physiologic anatomy of the trochlear groove.

Biomechanical Proof of Barbed Sutures for the Efficacy of Laparoscopic Pyeloplasty

BACKGROUND AND PURPOSE The gold standard for management of adult ureteropelvic junction obstruction is laparoscopic dismembered pyeloplasty (LPP), described by Anderson-Hynes, with reduced postoperative complications, early patient release, and favorable results. LPP, however, necessitates a high level of surgical expertise, especially with regard to reanastomosis. Knotless self-anchoring barbed sutures have also been introduced into aesthetic surgery and wound closure. We compared a self-retaining suture (SRS) Quill(®) (Angiotech, Canada) with a standard monofilament suture to further investigate their biomechanical and urodynamic aspects. MATERIALS AND METHODS We analyzed breaking strength and stiffness between SRS 4.0, 3.0, and polydioxanone suture (PDS(®)) 4.0 (Ethicon, Germany) using a biomechanical testing unit. Urodynamic evaluations were performed in the porcine upper urinary tract, closing a longitudinal incision either with SRS 4.0 (without knots) or with PDS 4.0 (five knots each end). Suture line shortening, suture time, tightness, and intrapelvic pressure were measured. RESULTS SRS 4.0 breaks at a mean of 11.57 N (standard deviation [SD]=1.25, stiffness 172.8 N/mm(2), SD=10.84), SRS 3.0 at 16.01 N (1.81), and PDS 4.0 at 18.41 N (0.75, 128.9 N/mm(2), 7.45). SRS 4.0 results in a suture line shortening from mean 3.08 to 2.26 mm (-26.6%) while PDS 4.0 shortens from 3.05 to 1.81 mm (-40.7%). The maximum intrapelvic pressure demonstrated no difference, and leakage was seen in 50% of the cases. Suture time was significantly decreased with SRS use (SRS 4.0 277 s and PDS 4.0 364 s). CONCLUSION SRS offers immediate tissue adaption with reduced suture line shortening and equal tightness compared with nonbarbed material in vitro. Knotless suturing using SRS is time efficient and appears to be an excellent material for LPP.

[Implantation technique for the CUT-type femoral neck endoprosthesis].

ZusammenfassungOperationszielEndoprothetischer Gelenkersatz der Hüfte unter größtmöglicher Erhaltung der Schenkelhalslänge. Wiederherstellung einer schmerzfreien Gelenkfunktion.IndikationenKoxarthrose, Hüftkopfnekrose bei jungen Patienten mit erhaltenem Schenkelhals.KontraindikationenGelenkinfektion.Coxa valga (Caput-Collum-Diaphysen-[CCD-]Winkel > 150°).Coxa vara (CCD-Winkel < 110°).Body-Mass-Index > 30 (relative Kontraindikation).Laufende Chemotherapie.Manifeste Osteoporose.OperationstechnikTransglutealer oder anterolateraler Zugang. Resektion des Hüftkopfes um zwei Drittel. Entfernung von Osteophyten um den Schenkelhals. In leichter Flexion und Adduktion des Beins übliche Implantation einer zementfreien Pfanne. Danach Aufraspeln des Schenkelhalses mit speziellen Raspeln für die CUT-Prothese. Probereposition mit liegender Raspel und modularem Konus (10°- oder 20°-Winkel). Zementfreie Stielimplantation.ErgebnisseZwischen 2002 und 2006 wurden bei 36 Patienten insgesamt 49 zementfreie CUT-Prothesen implantiert. Das Alter der Patienten betrug durchschnittlich 45,1 Jahre (20–60 Jahre). Der durchschnittliche stationäre Aufenthalt lag bei 10,8 Tagen und die mittlere Operationszeit bei 74 min. Der Blutverlust über die Drainagen betrug im Mittel 795 ml. Hiervon konnten jedoch durchschnittlich 297 ml rücktransfundiert werden. Zehn Patienten benötigten darüber hinaus eine Bluttransfusion. Postoperativ kam es zu keinen Infektionen, Nervenläsionen oder Hüftluxationen. Die Patienten wurden präoperativ beurteilt sowie 6 Wochen und 1 Jahr postoperativ nachuntersucht. Der Harris-Hip-Score besserte sich von 46,1 Punkten präoperativ auf 81,6 Punkte 6 Wochen und 95,7 Punkte 1 Jahr postoperativ. Eine Beinverlängerung um durchschnittlich 0,7 cm (Minimum –0,8, Maximum 2,2 cm) wurde radiologisch bei 31 der 49 Patienten ermittelt.Bis Oktober 2006 wurden zwei der 49 Prothesenstiele aufgrund einer aseptischen Lockerung gewechselt, im ersten Fall nach 19 Monaten (Hüftkopfnekrose bei systemischem Lupus erythematodes und Cortisoneinnahme) und im zweiten Fall nach 3 Jahren und 1 Monat (steroidinduzierte Hüftkopfnekrose bei Morbus Crohn und Azathioprin-[Imurek®-]Therapie). Einmal wurde 1 Monat nach der Implantation eine Revision mit Konus- und Kopfwechsel aufgrund einer Impingementsymptomatik notwendig. Bei einem Patienten kam es 2,5 Jahre nach Implantation zu einem Bruch des Keramikkopfes, was einen Konus- und Kopfwechsel erforderte. Der gesamte Nachbeobachtungszeitraum betrug im Mittel 37 Monate (Minimum 12, Maximum 55 Monate).AbstractObjectiveTotal hip replacement with maximum preservation of femoral neck. Restoration of pain-free joint function.IndicationsCoxarthrosis, femoral head necrosis in younger patients with intact femoral neck.ContraindicationsJoint infection.Coxa valga (caput-collum-diaphysis [CCD] angle > 150°).Coxa vara (CCD angle < 110°).Body mass index > 30 (relative contraindication).Ongoing chemotherapy.Osteoporosis.Surgical TechniqueTransgluteal or anterolateral approach. Resection of two thirds of the femoral head. Implantation of uncemented acetabular component. Revitalization of the femoral neck with special rasps for the CUT prosthesis. Trial reduction with bone rasp and modular cone in place (10° or 20° angle). Uncemented stem implantation.ResultsFrom 2002 to 2006, 49 uncemented CUT prostheses were implanted in 36 patients. Average age was 45.1 years (20–60 years). Inpatient stay amounted to 10.8 days and operating time to 74 min. Average blood loss through drainage was 795 ml, an average of 297 ml transfused back. Transfusion was necessary in ten patients. There were no cases of postoperative infection, nerve lesion, or hip dislocation. Patients were examined preoperatively and followed up at 6 weeks and 1 year. Harris Hip Score improved from 46.1 points preoperatively to 81.6 points at 6 weeks and 95.7 points at 1 year. Average leg length discrepancy of 0.7 cm (minimum –0.8, maximum 2.2 cm) was determined radiologically in 31 of 49 patients.It became necessary to replace two of the 49 stems due to aseptic loosening, in the first case at 19 months (femoral head osteonecrosis, lupus erythematosus, and taking cortisone), and in the second case 3 years after implantation (steroid-induced femoral head necrosis related to Crohns disease and azathioprine [Imurek®] therapy). One cone and head component had to be revised 1 month after implantation due to impingement syndrome. One ceramic head fractured 2.5 years after implantation so that cone and head required revision. The overall follow-up time was 37 months on average (minimum 12, maximum 55 months).

Implantationstechnik der Schenkelhalsprothese Typ CUT beim Hüftgelenkersatz

ZusammenfassungOperationszielEndoprothetischer Gelenkersatz der Hüfte unter größtmöglicher Erhaltung der Schenkelhalslänge. Wiederherstellung einer schmerzfreien Gelenkfunktion.IndikationenKoxarthrose, Hüftkopfnekrose bei jungen Patienten mit erhaltenem Schenkelhals.KontraindikationenGelenkinfektion.Coxa valga (Caput-Collum-Diaphysen-[CCD-]Winkel > 150°).Coxa vara (CCD-Winkel < 110°).Body-Mass-Index > 30 (relative Kontraindikation).Laufende Chemotherapie.Manifeste Osteoporose.OperationstechnikTransglutealer oder anterolateraler Zugang. Resektion des Hüftkopfes um zwei Drittel. Entfernung von Osteophyten um den Schenkelhals. In leichter Flexion und Adduktion des Beins übliche Implantation einer zementfreien Pfanne. Danach Aufraspeln des Schenkelhalses mit speziellen Raspeln für die CUT-Prothese. Probereposition mit liegender Raspel und modularem Konus (10°- oder 20°-Winkel). Zementfreie Stielimplantation.ErgebnisseZwischen 2002 und 2006 wurden bei 36 Patienten insgesamt 49 zementfreie CUT-Prothesen implantiert. Das Alter der Patienten betrug durchschnittlich 45,1 Jahre (20–60 Jahre). Der durchschnittliche stationäre Aufenthalt lag bei 10,8 Tagen und die mittlere Operationszeit bei 74 min. Der Blutverlust über die Drainagen betrug im Mittel 795 ml. Hiervon konnten jedoch durchschnittlich 297 ml rücktransfundiert werden. Zehn Patienten benötigten darüber hinaus eine Bluttransfusion. Postoperativ kam es zu keinen Infektionen, Nervenläsionen oder Hüftluxationen. Die Patienten wurden präoperativ beurteilt sowie 6 Wochen und 1 Jahr postoperativ nachuntersucht. Der Harris-Hip-Score besserte sich von 46,1 Punkten präoperativ auf 81,6 Punkte 6 Wochen und 95,7 Punkte 1 Jahr postoperativ. Eine Beinverlängerung um durchschnittlich 0,7 cm (Minimum –0,8, Maximum 2,2 cm) wurde radiologisch bei 31 der 49 Patienten ermittelt.Bis Oktober 2006 wurden zwei der 49 Prothesenstiele aufgrund einer aseptischen Lockerung gewechselt, im ersten Fall nach 19 Monaten (Hüftkopfnekrose bei systemischem Lupus erythematodes und Cortisoneinnahme) und im zweiten Fall nach 3 Jahren und 1 Monat (steroidinduzierte Hüftkopfnekrose bei Morbus Crohn und Azathioprin-[Imurek®-]Therapie). Einmal wurde 1 Monat nach der Implantation eine Revision mit Konus- und Kopfwechsel aufgrund einer Impingementsymptomatik notwendig. Bei einem Patienten kam es 2,5 Jahre nach Implantation zu einem Bruch des Keramikkopfes, was einen Konus- und Kopfwechsel erforderte. Der gesamte Nachbeobachtungszeitraum betrug im Mittel 37 Monate (Minimum 12, Maximum 55 Monate).AbstractObjectiveTotal hip replacement with maximum preservation of femoral neck. Restoration of pain-free joint function.IndicationsCoxarthrosis, femoral head necrosis in younger patients with intact femoral neck.ContraindicationsJoint infection.Coxa valga (caput-collum-diaphysis [CCD] angle > 150°).Coxa vara (CCD angle < 110°).Body mass index > 30 (relative contraindication).Ongoing chemotherapy.Osteoporosis.Surgical TechniqueTransgluteal or anterolateral approach. Resection of two thirds of the femoral head. Implantation of uncemented acetabular component. Revitalization of the femoral neck with special rasps for the CUT prosthesis. Trial reduction with bone rasp and modular cone in place (10° or 20° angle). Uncemented stem implantation.ResultsFrom 2002 to 2006, 49 uncemented CUT prostheses were implanted in 36 patients. Average age was 45.1 years (20–60 years). Inpatient stay amounted to 10.8 days and operating time to 74 min. Average blood loss through drainage was 795 ml, an average of 297 ml transfused back. Transfusion was necessary in ten patients. There were no cases of postoperative infection, nerve lesion, or hip dislocation. Patients were examined preoperatively and followed up at 6 weeks and 1 year. Harris Hip Score improved from 46.1 points preoperatively to 81.6 points at 6 weeks and 95.7 points at 1 year. Average leg length discrepancy of 0.7 cm (minimum –0.8, maximum 2.2 cm) was determined radiologically in 31 of 49 patients.It became necessary to replace two of the 49 stems due to aseptic loosening, in the first case at 19 months (femoral head osteonecrosis, lupus erythematosus, and taking cortisone), and in the second case 3 years after implantation (steroid-induced femoral head necrosis related to Crohns disease and azathioprine [Imurek®] therapy). One cone and head component had to be revised 1 month after implantation due to impingement syndrome. One ceramic head fractured 2.5 years after implantation so that cone and head required revision. The overall follow-up time was 37 months on average (minimum 12, maximum 55 months).

Cytotoxic effect and tissue penetration of phenol for adjuvant treatment of giant cell tumours

Local adjuvant treatment of giant cell tumours (GCTs) of the bone with phenol has led to a significant reduction in recurrence rates. In the current study, the optimal phenol concentration and duration of intralesional exposure were evaluated. Specimens of GCTs were exposed to various concentrations of phenol solution (6, 60 and 80%) for either 1 or 3 min. Following embedding in glutaraldehyde, the tumour cell layers were examined by transmission electron microscopy. Destroyed cell organelles indicated the penetration depth as a sign of denaturation. Incubation of GCT specimens with 6% phenol solution for 3 min resulted in the most tissue damage and the deepest tissue penetration of ∼200 μm. Incubation with 60 and 80% phenol solution reached a penetration depth of only ∼100 μm. Phenol instillation may be used for the treatment of small scattered cellular debris following intralesional curettage; however, it is not suitable for treatment of remaining solid tumour tissue of GCT. The use of high phenol concentrations has no benefit and increases the risk of local or systemic intoxication.

Cartilage surface characterization by frictional dissipated energy during axially loaded knee flexion-An in vitro sheep model

Cartilage defects and osteoarthritis (OA) have an increasing incidence in the aging population. A wide range of treatment options are available. The introduction of each new treatment requires controlled, evidence based, histological and biomechanical studies to identify potential benefits. Especially for the biomechanical testing there is a lack of established methods which combine a physiologic testing environment of complete joints with the possibility of body-weight simulation. The current in-vitro study presents a new method for the measurement of friction properties of cartilage on cartilage in its individual joint environment including the synovial fluid. Seven sheep knee joints were cyclically flexed and extended under constant axial load with intact joint capsule using a 6° of freedom robotic system. During the cyclic motion, the flexion angle and the respective torque were recorded and the dissipated energy was calculated. Different mechanically induced cartilage defect sizes (16 mm², 50 mm², 200 mm²) were examined and compared to the intact situation at varying levels of the axial load. The introduced setup could significantly distinguish between most of the defect sizes for all load levels above 200 N. For these higher load levels, a high reproducibility was achieved (coefficient of variation between 4% and 17%). The proposed method simulates a natural environment for the analysis of cartilage on cartilage friction properties and is able to differentiate between different cartilage defect sizes. Therefore, it is considered as an innovative method for the testing of new treatment options for cartilage defects.

Predictive Value of Preoperative Digital Templating in THA Depends on the Surgical Experience of the Performing Physician

Digital preoperative templating is increasingly used to predict the correct component size in total hip arthroplasty (THA). Experienced surgeons could avoid the new technique and rely on a digital template done by a younger colleague. We compared the accuracy of preoperative templating between orthopedic residents (group A) and an experienced orthopedic surgeon (group B). In 106 cases, the software-predicted component sizes of both groups were compared with component sizes placed surgically. An accurate prediction of the acetabular component was achieved in 63% of cases in group A compared with 88% of cases in group B (P=.001). Concerning the femoral component, accurate prediction was achieved in 89% in group A and 97% in group B (P=.021). If performed by an experienced orthopedic surgeon, digital templating is an accurate method to predict the prosthetic component size in THA.

Differences in tibiofemoral kinematics between the unloaded robotic passive path and a weightbearing knee simulator

Cadaveric in vitro studies are essential to test hypotheses concerning surgical manipulations in the same individual. Robotic technologies as well as different knee-models have been developed to get an in-depth comprehension of knee joint kinematics. The purpose of this study was to compare utilization of these different established principles. Ten human cadaveric knee specimens were used to measure the kinematics during a weight-bearing flexion in a 6-degrees-of-freedom knee simulator. While flexing the knee, joint quadriceps muscle forces were dynamically simulated to reach a vertical ground reaction force of 100N. Fourteen knee specimens were mounted in 6-degrees-of-freedom robotic manipulator with a universal force sensor. The unloaded flexing motion of each specimen was measured by finding positions for each degree of flexion where all forces are minimal (passive path). The kinematic data of the knee-simulator and the robot concerning internal-external rotation, anterior-posterior translation, varus-valgus motion, and medial-lateral translation was examined. For all investigated degrees of freedom the kinematics of the robotic passive path differed from the loaded kinematics in the knee simulator. Simulated bodyweight as well as the examination method used has a substantial influence on joint kinematics during flexion which has to be considered when interpreting biomechanical studies as well as clinical tests.