Three different ligament prostheses (Leeds-Keio®, Gore-Tex® and a prototype of Aramid®) were implanted in sheep knee joints replacing the anterior cruciate ligament and the medial collateral ligament. After 1 yr the knees were explanted and their biomechanical properties were assessed by a drawer test and tensile tests of the implants. Additionally the ligament replacements, the synovial membrane and the lymph nodes were inspected histologically. For each type of prosthesis partial or total ruptures occurred. None of the operated joints regained normal stability and stiffness. Anterior knee stability was best for the Gore-Tex treated group and worst for those joints that received a Leeds-Keio implant. The stiffness and rupture strength were highest for the Gore-Tex prostheses. Histologically the strongest intra-articular inflammatory response was observed in the Gore-Tex treated joints. Inside the drill tunnels the severest foreign body reaction was found for the Aramid prostheses. Gore-Tex fibres often showed good bony integration. Wear particles formed from all prostheses and caused small granulomas and mild synovities. The results suggest that none of the tested materials represent an ideal solution for ligament replacement. Relatively good stability does not guarantee good biocompatibility and vice versa. This suggests that ligament prostheses should be applied only in salvage cases.

Mechanical stimulation of bone tissue by physical activity stimulates bone formation in normal bone and may attenuate bone loss of osteoporotic patients. However, altered responsiveness of osteoblasts in osteoporotic bone to mechanical stimuli may contribute to osteoporotic bone involution. The purpose of the present study was to investigate whether osteoblasts from osteoporotic patients and normal donors show differences in proliferation and TGF beta production in responses to cyclic strain. Human osteoblasts isolated from collagenase-treated bone explants of 10 osteoporotic patients (average age 70 +/- 6 yr) and 8 normal donors (average age 54 +/- 10 yr) were plated into elastic rectangular silicone dishes. Subconfluent cultures were stimulated by cyclic strain (1%, 1 Hz) in an electromechanical cell stretching apparatus at three consecutive days for each 30 min. The cultures were assayed for proliferation, alkaline phosphatase activity and TGF beta release in each three parallel cultures. In all experiments, osteoblasts grown in the same elastic dishes but without mechanical stimulation served as controls. Significant differences between stimulated cultures and unstimulated controls were determined by a paired two-tailed Wilcoxon test. In comparison to the unstimulated controls, osteoblasts from normal donors significantly increased proliferation (p = 0.025) and TGF beta secretion (p = 0.009) into the conditioned culture medium. In contrast, osteoblasts from osteoporotic donors failed to increase both proliferation (p > 0.05) and TGF beta release (p > 0.05) in response to cyclic strain. Alkaline phosphatase activity was not significantly affected (p > 0.05) in normal as well as osteoporotic bone derived osteoblasts.These findings suggest a different responsiveness to 1% cyclic strain of osteoblasts isolated from normal and osteoporotic bone that could be influenced by both the disease of osteoporosis and the higher average age of the osteoporotic patient group. While osteoblasts from osteoporotic donors failed to increase proliferation and TGF beta release under the chosen mechanical strain regimen that stimulated both parameters in normal osteoblasts, it is possible that some other strain regimen would provide more effective stimulation of osteoporotic cells.

We asked whether dynamization of externally fixed diaphyseal fractures could improve bone healing in comparison to rigid fixation of fractures having similar remaining gap sizes. To answer this question we evaluated metatarsal osteotomies in 12 sheep. The osteotomy with a 0.6-mm gap was stabilized with a specially designed high bending and torsional stiffness external ring fixator. Osteotomies in six sheep were stabilized rigidly (axial movement < 0.06 mm) or dynamically (axial movement 0.15-0.34 mm). The cyclical axial interfragmentary movement was caused by the load-bearing of the operated limb. With increasing healing time, the initially allowed movement was decreased by callus formation around the osteotomy. The reduction in interfragmentary movement was measured and monitored by a linear variable displacement transducer at the external fixator and a telemetry system. After 9 weeks the sheep were sacrificed and the healed bones were investigated biomechanically and histomorphologically. Compared to the rigidly fixed osteotomies, the dynamized osteotomies showed significantly (P < 0.05) greater (+41%) callus formation and 45% greater tensile strength of the newly formed bone in the cortical osteotomy gap. Histological analysis indicated that the effect of dynamization occurred mainly after the 5th week. RELEVANCE: From these results we conclude that dynamic fixation of diaphyseal gaps is advantageous in comparison to stable external fixation.

Eine Knochentransplantation ist bei 15% aller Operationen im Rahmen der Wiederherstellungschirurgie der Bewegungsorgane erforderlich [1]. Hauptindikationen zur Knochentransplantation sind: Frakturen mit Defekten, Defekte nach Osteitis, Knochenzysten, gutartige Tumoren und niedrig maligne Tumoren. Die Knochentransplantation kann allogen und autogen erfolgen.

Six different ligament prostheses were implanted in 40 sheep to replace the anterior cruciate and medial collateral ligament of the right knee. After one year the explanted knee joints were tested for stability by measurement of the anterior drawer. Tensile tests on the ligament replacements were performed to determine the stiffness and rupture force of the replacement. Gross inspection of the knee joint showed abrasion and partial ruptures for all types of prostheses after one year. Depending on the type of prosthesis total rupture rates between 0 and 66% of all implants could be seen. The anterior drawer for the operated knee was 3–4 times higher than for the non-operated contralateral side. Neither the stiffness nor the rupture strength of the replacements reached the biomechanical properties of the normal ligaments.

Ultrasonography was used to inspect the ankle anatomy of 20 healthy volunteers. The images produced were correlated with anatomical structures by examining three dissected cadaver ankles. The anterolateral pouch of the articular capsule was identified by ultrasonography in 91% of the normal ankle joints as a hypoechoic area. The posterolateral pouch of the articular capsule also could be identified by ultrasonography as a hypoechoic area in 84% of the normal ankles examined. The lateral aspect of 105 traumatized ankles was examined subsequently. The ultrasound results agreed in 100% of the cases with the operative findings for the anterior talofibular ligament and in 92% for the calcaneofibular ligament.

72 patients with injury of the ankle joint were examined with ultrasound after therapy. Sonographic findings were assessed by plain x-ray films and stress views. In 39 patients an injury of the lateral ligament was treated by surgery and in 33 patients without surgery. 40 patients showed a scar of the lateral ligaments. Patients treated without surgery and showing a scar in ultrasound demonstrated a smaller tilt of the talus in stress views than patients without scars. Measurement of stability was not possible. In conclusion, sonography is a valuable tool in examining the ankle joint after therapy. With regard to stability, stress films cannot be replaced by sonography.

72 patients with injury of the ankle joint were examined with ultrasound after therapy. Sonographic findings were assessed by plain x-ray films and stress views. In 39 patients an injury of the lateral ligament was treated by surgery and in 33 patients without surgery. 40 patients showed a scar of the lateral ligaments. Patients treated without surgery and showing a scar in ultrasound demonstrated a smaller tilt of the talus in stress views than patients without scars. Measurement of stability was not possible. In conclusion, sonography is a valuable tool in examining the ankle joint after therapy. With regard to stability, stress films cannot be replaced by sonography.

Fractures of the elbow may result in deformity, pseudarthrosis and arthritis, which lead to painful and restricted use of the joint. The operative treatment of these late complications includes osteotomies, surface reconstruction, arthrolysis, arthroplasty, alloarthroplasty and arthrodesis. Indications, operative techniques and results are described and discussed.

In the department of traumatology, hand surgery, plastic and rehabilitation surgery of the University of Ulm, a prospective study was carried through over a period of 5 years (1980-1984) to record all early local complications; their course and final outcome were observed throughout this period. A total of 30,217 operations were performed, and we observed a total of 527 (i.e. 1.74%) perioperative and early postoperative complications in 447 patients. This rate remained nearly the same throughout the observation period. The complication most often found was postoperative hematoma, with an incidence of 0.61%; the hematoma had to be removed in a second operation in two-thirds of all cases. The next most frequent complication was infection of soft tissue and bones (incidence 0.49%), followed by lesions of nerve fibres (0.22%) and disturbances of wound healing and necrosis (0.15%). In comparison with those complications we were seldom confronted with luxations after implantation of femoral head prostheses, incorrect internal fixation, refractures and ischaemia after lesion of blood vessels. Most complications were localised in the knee (21.2%) and the lower leg (18.3%). We only observed 148 early complications (infection rate 0.49%), with 54 occurring in bones and joints and only 94 in soft tissue. In open fractures the infection rate totalled 2.03% and in closed fractures, 0.16%. We observed 14 joint infections (infection rate 0.16%), with 3 infections after the implantation of femoral head prostheses.(ABSTRACT TRUNCATED AT 250 WORDS)

Bei der Osteosynthese von Frakturen ist es eher die Ausnahme, eine absolute Stabilität ohne jegliche interfragmentäre Bewegung zu erreichen. In solchen Fällen kann eine callusfreie direkte Knochenheilung erzielt werden (3). Ist eine interfragmentäre Bewegung nicht vermeidbar, kommt es zur Callusbildung und sekundären Knochenheilung (2). Bei zu starken Bewegungen können Pseudarthrosen nicht ausgeschlossen werden (2). Um die Wechselwirkung zwischen interfragmentärer Dehnung (interfragmentäre Bewegung bezogen auf die Frakturspaltbreite) und dem Typ der Knochenheilung zu untersuchen, führten wir eine tierexperimentelle Studie durch. Als Versuchsmodell wurde eine Osteotomie am Schafsmetatarsus gewählt, die mit einem speziellen Fixateur externe stabilisiert wurde.