[Relevance of wound drainage in total knee arthroplasty--a prospective comparative study]. / Die Bedeutung der Wunddrainage in der Knieendoprothetik--eine prospektive Vergleichsstudie.

AIM: The benefits of postoperative wound drainage in patients with total knee arthroplasty (TKA) with regards to mobilisation and wound healing were studied. We wanted to determine the efficacy of an autologous blood retransfusion system. METHOD: 150 patients with TKA were divided into three groups of 50 patients: A) three wound drainages with an autotransfusion system and suction; B) no wound drainage; C) one intraarticular wound drainage without suction. Hemoglobin values, blood transfusion requirements, blood loss, postoperative range of motion, Insall knee score and rate of complications were observed and recorded. All patients were operated without tourniquets for lower blood loss. RESULTS: In the group of patients with wound drainage and a retransfusion system the requirement of postoperative additional blood transfusion was not significantly less than in the group without wound drainage. Group A had the highest blood loss of all. The group without wound drainage had more hematomas and wound healing complications. Best results were observed within the group with one intraarticular drainage without suction. The rate of complications was not increased and the blood transfusion requirements were the lowest. CONCLUSION: This study shows that total knee replacement involving one intraarticular wound drainage without suction attains the best results.

[Hyperparathyroidism -- a differential diagnosis of cystic bone tumors]. / Hyperparathyreodismus-eine Differentialdiagnose zystischer Knochentumoren.

Clinical manifestations of primary hyperparathyroidism include neuromuscular, intestinal, and osseous symptoms with osteolytic lesions of the bone and pathological fractures. In most cases a primary adenoma of the parathyroid gland leads to an increased production of the parathormone with subsequent osteoclastic bone catabolism. Surgical treatment entails removal of the parathyroid adenoma. We present a female patient and the possible diagnostic and differential diagnostic difficulties encountered in interdisciplinary management.

The stability of bone screws in the os sacrum.

A variety of points of insertion and implantation techniques are recommended for inserting screws into the os sacrum. On the basis of 16 complete human sacrum specimens the following axial pull-out tests were performed: 1. Insertion of convergent measuring screws, 6.0 mm and 7.0 mm in outside diameter respectively, into the body of vertebra S1 using a monocortical and bicortical technique respectively with perforation of the ventral cortex. 2. Insertion of divergent screws into the ala sacralis at the level of S1 with 6-mm and 7 mm screws respectively, using a monocortical technique without perforation of the ventral cortex. 3. Insertion of convergent 6-mm screws into the body of vertebra S2 using a monocortical and bicortical technique respectively with perforation of the ventral cortex. The highest axial pull-out force was reached using convergent 6-mm screws inserted into the body of vertebra S1 using the bicortical technique with perforation of the ventral cortex (2392.4 N). The use of a 7.0-mm screw in the same implantation technique did not result in higher pull-out forces (2274.7 N). The monocortical technique reached a pull-out force of 1657.53 N with a 6-mm screw and 1505.64 N with a 7-mm screw. Convergent insertion of 6-mm screws into the body of S2 resulted in pull-out forces of 537.02 N using a bicortical and only 297.71 N using a monocortical technique. Divergent insertion of screws into the ala sacralis reached a maximal pull-out force of 495.47 N using 6-mm screws and 449.79 N using 7-mm screws. These data resulted from a monocortical implantation technique without perforation of the ventral cortex of the ala sacralis. The results of the present biomechanical study show that convergent bicortical implantation in the body of S1 is the most stable technique for screw fixation in the sacrum. The use of 7-mm rather than 6-mm screws did not lead to increased primary stability. Anatomic studies have shown that a safe area exists in the region of the ventral promontory, so this implantation technique appears to be unobjectionable.

[Biomechanical prerequisites for examining the stability of osteosynthesis procedures of the spine]. / Biomechanische Voraussetzungen zur Stabilitätsuntersuchung von Osteosyntheseverfahren an der Wirbelsäule.

Basic reflections on biomechanical tests of spinal implants are reviewed. Four different pedicle screw systems are compared during loading in extension, flexion, side-bending, and rotation. The thoracolumbar and the lumbar spine were tested. Stability against rotation forces was lowest in all systems. Because of this, a cross-connector is recommended in highly unstable situations. All tests were done in cadaver spines with normal bone mineral density (measured before the tests). The first series of tests was done without destroying the cadavers. A second series was done with maximal load until the implants or the bony bed of the screws failed. The results show that rigid implants more often led to pedicle fractures. An unstable screw rod interface led to implant failure. Cadaver tests can provide answers about the primary stability characteristic only. Fatigue tests are not possible in cadaver spines because they become autolytic before enough cycles can be applied.