Histomorphometric Analysis of Callus Formation Stimulated by Axial Dynamisation in a Standardised Ovine Osteotomy Model.

The cyclic axial dynamisation of a stabilised fracture is intended to promote callus formation and bone healing. Most studies focused on biomechanical properties or the quantity of new bone formation. Far less is known about the quality of newly formed callus tissues, such as tissue distribution and arrangement within the callus. The aim of this current study was to investigate the effect of cyclic, axial dynamisation on the quantity and quality of callus in an established delayed fracture healing model. In 41 sheep transverse osteotomies with a gap size of 3 mm were stabilised with a unilateral external fixator. In 32 of these, fracture ends were axially stimulated with displacement amplitudes of 0.8 mm, 0.4 mm, 0.2 mm, or 0.0 mm, respectively, for six weeks. In the remaining 9 sheep of the control group, an additional external fixator was mounted to achieve almost total rigidity. Animal material originating from a past animal experiment was reanalysed in this study. Histological thin-ground sections were histomorphometrically analysed regarding the histological structure and composition of the defect region. A slight tendency towards an increase in size of total callus area, area of new bone (nB.Ar), and cartilage (Cg.Ar) was detected with increasing displacement amplitudes compared to the control group. At the anterior callus side nB.Ar and Cg.Ar were significantly larger than at the posterior side in all groups independent of treatment. Regarding the quality of callus, areas of very compact bone were predominant in the treatment groups whereas in the control group a slight shift to more porous bone was observed. No difference of callus compactness was observed between the anterior and the posterior side. The established method to assess the local compactness of callus areas is a useful tool to quantitatively determine the spatial distribution of new bone tissue within the callus. The application of this method in combination with biomechanical testing might reveal interesting relations between tissue distribution and bone strength that, with traditional histomorphometry, cannot be identified.

Posterior cruciate ligament injuries of the knee joint.

Posterior cruciate ligament (PCL) injuries have a reported incidence of between 3 and 37%, depending on the clinical setting. The most common mechanism of injury in motor vehicle accidents is a dashboard injury or direct force to the proximal anterior tibia. Sports related injuries result from hyperflexion of the knee with the foot typically plantarflexed. The latter mechanism is the most common cause of isolated PCL injuries, while in the trauma population as many as 95% of patients with knee injuries have combined ligamentous damage. Improved knowledge at an anatomical, biomechanical and clinical level has provided the orthopaedist with a more defined treatment algorithm. Isolated, partial PCL injuries (grades I and II) can best be treated nonoperatively while complete injuries (grade III) may require operative treatment based on clinical symptoms. All combined ligamentous injuries usually respond best with surgical management.

The effects of external mechanical stimulation on the healing of diaphyseal osteotomies fixed by flexible external fixation.

OBJECTIVE: The purpose of this study was to investigate the effect of an externally applied mechanical stimulus on fracture healing under flexible fixation. DESIGN: Stimulation of fracture healing under various conditions of interfragmentary movement in an in vivo fracture model on 41 sheep. BACKGROUND: It is generally accepted that small interfragmentary movements (IFMs) yield better bone healing results than larger IFMs (> 1 mm). However, the optimal size of IFM within the 1-mm range remains undetermined. METHODS: Standardized transverse osteotomy of 3 mm gap size in the left ovine tibia was fixed with an unilateral external fixator. The sheep were divided into four IFM groups of 0.0, 0.2, 0.4 and 0.8 mm and stimulated with this amplitude for 1200 cycles per day at 1 Hz. After a healing period of 6 weeks, bone mineral density and biomechanical stability were evaluated to determine the quality of healing. RESULTS: The amount of callus formation increased significantly with increasing IFM (P <0.05). However, highest biomechanical stability of the healed bone and mineral density of the gap tissue was achieved with an IFM of 0.4 mm, although the differences were not significant. CONCLUSIONS: These results suggest that the optimal interfragmentary movement for acceleration of delayed fracture healing is in the range of 0.5 mm. However, the enhancement of the healing of flexibly-fixed fractures by external application of interfragmentary movement is limited. RELEVANCE: In this model the external application of a mechanical stimulus in addition to the stimulation caused by normal loading and the flexibility of the fixation did not enhance the healing process significantly. It appears that the external application of interfragmentary motion is promising perhaps only for patients unable to stimulate their fracture healing by weight-bearing.

[Late results of surgical treatment of acute and chronic instability of the ulnar collateral ligaments]. / Spätergebnisse nach operativer Behandlung frischer und chronischer Instabilitäten des ulnaren Daumenseitenbandes.

A total of 113 patients with acute and chronic instability of the ulnar collateral ligament metacarpal phalangeal (MP) joint of the thumb were treated surgically between 1980 and 1985; 82 patients were followed up after a mean period of 10 years. Of 59 patients with acute injuries, 52 were painfree with full stability of the MP joint; 23 patients with chronic instability and tendon grafting also showed restoration of stability. Nevertheless, the range of motion was reduced severely and opposition of the thumb was impaired. The results of follow-up reveal that acute reattachment of the injured ulnar collateral ligament is more effective.

[Results of conservative treatment of bony palmar plate avulsion of the middle joint (type I and type II according to Hintringer and Leixnering)]. / Ergebnisse der konservativen Behandlung von knöchernen palmaren Plattenausrissen am Mittelgelenk (Typ I und II nach Hintringer und Leixnering).

At the Unfallkrankenhaus Lorenz Böhler, avulsion fractures of the palmar plate of the proximal interphalangeal (PIP) joint type I the and II are treated by immobilisation in a PIP-Stack splint. We use 147 the classification of Hintringer and Leixnering (1991). The were immobilised for three weeks. For follow-up, 102 patients with 106 injured fingers from an overall of 147 patients treated by this method were investigated personally. 27 patients who could not attend, were evaluated by telephone. 22(17 to 25) months after the accident results were subjectively and objectively very good in 80% of the patients. In none of the patients extension was limited. In 18 patients, flexion was limited 5 to 10 degrees, in two patients 15 to 20 degrees. No patient had a limitation of flexion of more than 20 degrees.

[Heart arrest as a sequela of clavicular fracture]. / Herzstillstand als Folge einer Schlüsselbeinfraktur.

After a fracture of the medial part of the clavicle cardiac arrest occurred. This complication can be explained by vagus irritation because of fracture haematoma. The patient survived and was, six months later, of best health.