White Paper: An Integrated Perspective on the Causes of Hypometric Metabolic Scaling in Animals

Larger animals studied during ontogeny, across populations, or across species, usually have lower mass-specific metabolic rates than smaller animals (hypometric scaling). This pattern is usually observed regardless of physiological state (e.g. basal, resting, field, maximally-active). The scaling of metabolism is usually highly correlated with the scaling of many life history traits, behaviors, physiological variables, and cellular/molecular properties, making determination of the causation of this pattern challenging. For across-species comparisons of resting and locomoting animals (but less so for across populations or during ontogeny), the mechanisms at the physiological and cellular level are becoming clear. Lower mass-specific metabolic rates of larger species at rest are due to a) lower contents of expensive tissues (brains, liver, kidneys), and b) slower ion leak across membranes at least partially due to membrane composition, with lower ion pump ATPase activities. Lower mass-specific costs of larger species during locomotion are due to lower costs for lower-frequency muscle activity, with slower myosin and Ca++ ATPase activities, and likely more elastic energy storage. The evolutionary explanation(s) for hypometric scaling remain(s) highly controversial. One subset of evolutionary hypotheses relies on constraints on larger animals due to changes in geometry with size; for example, lower surface-to-volume ratios of exchange surfaces may constrain nutrient or heat exchange, or lower cross-sectional areas of muscles and tendons relative to body mass ratios would make larger animals more fragile without compensation. Another subset of hypotheses suggests that hypometric scaling arises from biotic interactions and correlated selection, with larger animals experiencing less selection for mass-specific growth or neurolocomotor performance. A additional third type of explanation comes from population genetics. Larger animals with their lower effective population sizes and subsequent less effective selection relative to drift may have more deleterious mutations, reducing maximal performance and metabolic rates. Resolving the evolutionary explanation for the hypometric scaling of metabolism and associated variables is a major challenge for organismal and evolutionary biology. To aid progress, we identify some variation in terminology use that has impeded cross-field conversations on scaling. We also suggest that promising directions for the field to move forward include: 1) studies examining the linkages between ontogenetic, population-level, and cross-species allometries, 2) studies linking scaling to ecological or phylogenetic context, 3) studies that consider multiple, possibly interacting hypotheses, and 4) obtaining better field data for metabolic rates and the life history correlates of metabolic rate such as lifespan, growth rate and reproduction.

Monteggia fractures: analysis of patient-reported outcome measurements in correlation with ulnar fracture localization

BACKGROUND

Monteggia fractures and Monteggia-like lesions result after severe trauma and have high complication rates. Preliminary biomechanical studies suggested a correlation between ulnar fracture localization and clinical result.

OBJECTIVES

Key objective was to evaluate whether the site of the ulnar fracture can be correlated to clinical outcome after open reduction and internal stabilization.

METHODS

In a retrospective, monocentric study 35 patients who underwent surgical treatment after suffering a Monteggia injury or Monteggia-like lesion were included. Fractures were classified according to Bado and Jupiter, the site of the fracture location at the proximal ulna and regarding the potential accompanying ligamentary injury. In a follow-up examination validated patient-reported outcome measures and functional parameters were evaluated. Furthermore, treatment strategy and complications were analysed.

RESULTS

Mean patient age was 51.9 years (± 18.0). 69% were females (n = 24). Follow-up took place after 50.5 months (± 22.1). Fractures were classified according to Bado (I:2, II:27, III:4, IV:2). Bado II-fractures were further classified according to Jupiter (A:7, B:16, C:3, D:1). Cases were divided into subgroups depending upon the distance of the ulnar fracture site in respect to its distal endpoint (A: < 7 cm and B: > 7 cm). Average overall MEPS was 84.1 (± 19.0). Oxford elbow score and DASH were 37.2 (± 10.5) and 20.4 (± 20.5). Average extension capability reached - 7° (± 7.5). Mean flexion was 134.8° (± 19.7). Average pain according to visual analogue scale was 1.6 (± 1.9). We found no differences between the subgroups regarding the PROMs. Subgroup A displayed a worse extension capability (p = 0.027) and patients were significantly older (p < 0.01). Comparing patients with and without fracture of the radial head, we observed no differences. Patients with an accompanying injury of the coronoid process displayed higher pain levels (p = 0.011), a worse functionality (p = 0.027) and overall lower scoring in PROM.

CONCLUSION

The presented results suggest that in Monteggia fractures and Monteggia-like lesions, the localization of the ulna fracture can give a hint for its postoperative outcome. However, we could not confirm the hypothesis of an increasing instability in ulnar fractures located further distally (high severity of the potential ligamentous injury). Intraarticular fractures or injuries with a close relation to the joint have a worse prognosis, especially if the coronoid process is injured. Trial registration Registration was done with ClinicalTrials.gov under NCT05325268.

Tuning of feedforward control enables stable muscle force-length dynamics after loss of autogenic proprioceptive feedback

Animals must integrate feedforward, feedback and intrinsic mechanical control mechanisms to maintain stable locomotion. Recent studies of guinea fowl (Numida meleagris) revealed that the distal leg muscles rapidly modulate force and work output to minimize perturbations in uneven terrain. Here we probe the role of reflexes in the rapid perturbation responses of muscle by studying the effects of proprioceptive loss. We induced bilateral loss of autogenic proprioception in the lateral gastrocnemius muscle (LG) using self-reinnervation. We compared in vivo muscle dynamics and ankle kinematics in birds with reinnervated and intact LG. Reinnervated and intact LG exhibit similar steady state mechanical function and similar work modulation in response to obstacle encounters. Reinnervated LG exhibits 23ms earlier steady-state activation, consistent with feedforward tuning of activation phase to compensate for lost proprioception. Modulation of activity duration is impaired in rLG, confirming the role of reflex feedback in regulating force duration in intact muscle.

Biomechanical comparison of bi- and tricortical k-wire fixation in tension band wiring osteosynthesis

Background

Patients with a simple transversal fracture of the olecranon are often treated with a tension band wiring (TBW), because it is known as a biomechanically appropriate and cost-effective procedure. Nevertheless, the technique is in detail more challenging than thought, resulting in a considerable high rate of implant-related complications like k-wire loosening and soft tissue irritation. In the literature, a distinction is generally only made between transcortical (bi-) and intramedullary (mono-) fixation of the wires. There is the additional possibility to fix the proximal bent end of k-wire in the cortex of the bone and thus create a tricortical fixation. The present study investigates the effectiveness of bi- and tricortical k-wire fixation in a biomechanical approach.

Methods

TBW of the olecranon was performed at 10 cadaver ulnas from six donors in a usual manner and divided into two groups: In group 1, the k-wire was inserted by bicortical fixation (BC), and in group 2, a tricortical fixation (TC) was chosen. Failure behavior and maximum pullout strength were assessed and evaluated by using a Zwick machine. The statistical evaluation was descriptive and with a paired t test for the evaluation of significances between the two techniques.

Results

The average age of the used donors was 81.5 ± 11.5 (62–92) years. Three donors were female, and three were male. Ten k-wires were examined in BC group and 10 in the TC group. The mean bone density of the used proximal ulnas was on average 579 ± 186 (336–899) HU. The maximum pullout strength was 263 ± 106 (125–429) N in the BC group and increased significantly in the TC group to 325 ± 102 (144–466) N [p = .005].

Conclusion

This study confirms for the first time biomechanical superiority of tricortical k-wire fixation in the olecranon when using a TBW and may justify the clinical use of this method.

Prospective randomized controlled trial in the treatment of lateral epicondylitis with a new dynamic wrist orthosis

BACKGROUND

In the treatment of lateral epicondylitis (LE), the role of a new dynamic wrist orthosis is unclear.

PATIENTS AND METHODS

Patients suffering from a LE longer than 3 months were multicentrically and prospectively randomized into a physiotherapeutic group (PT group) and in a physiotherapy group plus wrist orthosis (PT + O group). Physiotherapy consisted of daily eccentric strengthening exercises under initial professional supervision. Inclusion criteria were a Placzek score greater than 4. Exclusion criteria were previous surgery, rheumatic arthritis, elbow instability, radicular symptoms, higher-grade extensor tendon rupture, or cervical osteoarthritis. The clinical evaluation was performed after 12 weeks and 12 months. The Patient-Rated Tennis Elbow Evaluation (PRTEE) scale, Placzek Score, the pain rating (VAS), range of motion and the Subjective Elbow Score were evaluated.

RESULTS

Of the initially 61 patients, 31 were followed up after 12 weeks and 22 after 12 months. Twenty-nine patients (43%) were male, the mean age was 46, and 44 patients (66%) had the right elbow involved. At 12 weeks, there was a pain reduction on the VAS in both groups (PT + O: 6.5-3.7 [p = .001]; PT: 4.7-4.1 [p = .468]), albeit it was only significant for the PT + O group. At 12 months, reduction was significant in both groups (PT + O: 1.1 [p = .000]; PT: 1.3 [p = .000]). The painless maximum hand strength in kg improved in both groups significant after 3 and 12 months. The Placzek score was reduced from 8.25 to 3.5 [p = .001] after 12 weeks for the PT + O group and from 8.1 to 3.8 [p = .000] in the PT group, as well as after 12 months in the PT + O group to 0 [p = .000] and in the PT group to 2.0 [p = .000]. The PRTEE improved in both groups after 12 weeks (PT + O: 52.8--31.3 [p = .002]; PT: 48.6-37.6 [p = .185]) and 12 months (PT + O: 16.15 [p = .000]; PT: 16.6 [p = .000]), although the reduction at 12 weeks was not significant for the PT group.

CONCLUSION

The elbow orthosis appears to accelerate the healing process with respect to the PRTEE and pain on the VAS (12 weeks follow-up), although there is an adjustment after 12 months in both groups and a significant improvement of symptoms is achieved in all endpoints.

[Corrective osteotomies for posttraumatic elbow deformities]

OBJECTIVES

Correcion of elbow joint deformities that usually develop secondary to direct or indirect trauma of the arm or elbow with subsequent inadequate healing and consecutive axial/rotational malalignment and may be associated with cosmetic or functional deficits of the arm.

INDICATIONS

Relevant malalignment of the arm axis with corresponding cosmetic or functional deficits for the patient.

CONTRAINDICATIONS

Pre-existing degenerative and chronic inflammatory changes.

SURGICAL TECHNIQUE

Generally, two-dimensional supracondylar open or closed wedge osteotomies are used. In the presence of a three-dimensional deformity (with rotational component), an additional derotational correction is necessary. Extra-articular deformities following extension fractures should be treated preferably with an open wedge osteotomy, extra-articular deformities of flexion fractures with a closed wedge osteotomy. Valgus/varus deformities may also require a closed/open wedge osteotomy primarily through a dorsal or alternatively radial approach.

POSTOPERATIVE MANAGEMENT

The arm should be immobilized with a brachial cast splint for 2-3 weeks, with passive exercises of the elbow starting on postoperative day 7.

RESULTS

In general, the results for a three-dimensional osteotomy of the distal humerus are expected to be good to very good. Only in rare cases (2.5%) is a mostly transient irritation of the ulnar nerve observed.

[Control of diffuse bleeding in unstable pelvic fractures with compression plate packing: presentation of the surgical technique]

Current recommendations on surgical management of unstable pelvic fracture with hemorrhagic shock include reduction and fixation, i.e., with a C-clamp and external fixator, angiographic embolization of injured pelvic arteries, and preferably extraperitoneal packing to control diffuse bleeding from the venous plexus and fracture site. However, the recently reported lethality at 40-60% remains seriously high. One possible reason could be the unsatisfactory efficiency of extraperitoneal packing in the case of a traumatically or surgically opened retroperitoneal compartment. In this paper, a new approach, so-called compression plate packing, is proposed to control diffuse bleeding. In this technique, the essential pressure of the packing on the bleeding site is set up with small fragment plates with screw fixation to the pelvic ring. In two first clinical cases of severe pelvic trauma the hemorrhage could be controlled reliably.

[Perspectives of clinical stem cell therapy in the treatment of musculoskeletal diseases in Germany]

AIM

The treatment of large bone defects remains a challenge for the orthopaedic surgeon. Regenerative therapies with the use of mesenchymal stem cells (MSC) may provide an alternative to autogenous bone transplantation, callus distraction or the use of allografts.

MATERIAL AND METHODS

On the occasion of an expert workshop of the German Society for Orthopaedic and Trauma Surgery, a literature search regarding studies with the use of MSC was performed to evaluate its potential for future clinical studies. Furthermore, the legislative requirements were examined.

RESULTS

Various in vitro and animal studies showed the benefit of MSC in bone regeneration. However, there are sparse data from clinical studies. Due to recent legislative changes there are several regulatory demands to meet if clinical studies are performed with MSC.

CONCLUSIONS

For further evaluation of the role of MSC in the treatment of bone defects there is a need for clinical trials. The current paper provides some assistance for the successful application for clinical trials with MSC. Planning and performance of these studies may require early consultation with the regulatory authorities and cooperation of research centres in order to obtain authorisation for the evaluation of MSC. Preclinical data have to be obtained according to good laboratory practice with equivalent protocols that will be used in the clinical trials. In the latter the implementation of the guidelines for good clinical practice are mandatory.

Ovine bone marrow mesenchymal stem cells: isolation and characterization of the cells and their osteogenic differentiation potential on embroidered and surface-modified polycaprolactone-co-lactide scaffolds

The current study was undertaken with the goal being isolation, cultivation, and characterization of ovine mesenchymal stem cells (oMSC). Furthermore, the objective was to determine whether biological active polycaprolactone-co-lactide (trade name PCL) scaffolds support the growth and differentiation of oMSC in vitro. The oMSC were isolated from the iliac crest of six merino sheep. Three factors were used to demonstrate the MSC properties of the isolated cells in detail. (1) Their ability to proliferate in culture with a spindle-shaped morphology, (2) presence of specific surface marker proteins, and (3) their capacity to differentiate into the three classical mesenchymal pathways, osteoblastic, adipogenic, and chondrogenic lineages. Furthermore, embroidered PCL scaffolds were coated with collagen I (coll I) and chondroitin sulfate (CS). The porous structure of the scaffolds and the coating with coll I/CS allowed the oMSC to adhere, proliferate, and to migrate into the scaffolds. The coll I/CS coating on the PCL scaffolds induced osteogenic differentiation of hMSC, without differentiation supplements, indicating that the scaffold also has an osteoinductive character. In conclusion, the isolated cells from the ovine bone marrow have similar morphologic, immunophenotypic, and functional characteristics as their human counterparts. These cells were also found to differentiate into multiple mesenchymal cell types. This study demonstrates that embroidered PCL scaffolds can act as a temporary matrix for cell migration, proliferation, and differentiation of oMSC. The data presented will provide a reliable model system to assess the translation of MSC-based therapy into a variety of valuable ovine experimental models under autologous settings.

A moving topic: control and dynamics of animal locomotion

Animal locomotion arises from complex interactions among sensory systems, processing of sensory information into patterns of motor output, the musculo-skeletal dynamics that follow motor stimulation, and the interaction of appendages and body parts with the environment. These processes conspire to produce motions and forces that permit stunning manoeuvres with important ecological and evolutionary consequences. Thus, the habitats that animals may exploit, their ability to escape predators or attack prey, their capacity to manoeuvre and turn, or the use of their available energy all depend upon the processes that determine locomotion. Here, we summarize a series of 10 papers focused on this integrative research topic.

[Internal fixation of meta- and diaphyseal intercalary bone defects after tumour resection with intramedullary nailing and porous polymethylmetacrylate (PMMA) spacer]

BACKGROUND

Radical resection of bone tumours localized in the meta- or diaphysis of long bones frequently results in segmental defects. Several stabilization techniques with preservation of the adjacent joint have been published, but the failure rate appears to be considerable. The objective of this study is the experimental and clinical testing of a new technique which combines unreamed nailing with support of the defect by a porous polymethylmetacrylate (PMMA) spacer.

METHODS

For spacer preparation, PMMA spheres were adhered to a cylindrical spacer (Ø 32 mm) with interconnective porosity. Axial strength was determined, as was the stiffness/strengths of the combination osteosynthesis in human cadaver tibias (defect lengths 6 cm; empty defect served as a control). An experiment was also conducted with sheep. A 3 cm diaphyseal tibia defect was prepared and stabilized by nailing. For the control there was an empty defect. Group A had support of the defect with a PMMA spacer and group B a PMMA spacer coated with osteoconductive RGD-peptide. Evaluation after was made after 6 months including histology and a determination of relative torsional strength. In addition, a clinical study has been under way since October 1998, with 13 patients (defect lengths between 3-15 cm) being operated.

RESULTS

Axial stability was 12,750+/-300 N (17.56+/-0.59 MPa). There was an enhancement of 4-point bending stiffness by 35% (P=0.028), of axial stiffness by 36% (ns) and of axial strength by 553% (P=0.028). Histology showed the formation of a new bone at the spacer/muscle interface. For the sheep, relative torsional strength was enhanced by 95% (P=0.08) in group A and by 91% (P=0.047) in group B. For the patients studied, the mean follow-up period was 16.1 months, max. 48 months. One mechanical failure occurred after 24 months, which was solved by callus distraction.

CONCLUSIONS

Combination osteosynthesis is suitable for stabilizing segmental bone defects. The risk of mechanical failure appears to be low. Nevertheless, this technique should only be applied as a definitive solution if callus distraction is unfavourable due to advanced age or a poor lifetime prognosis. The method can also be used for temporary internal stabilization during prolonged postoperative chemotherapy.

[Distal radius fracture. Correlation between radiological and functional results]

BACKGROUND

The purpose of the present study was to investigate the influence of the radiological parameters on the functional outcome of patients with a fracture of the distal radius and to find out to which extent a deformity can be tolerated.

PATIENTS AND METHODS

A total of 344 patients with an isolated fracture of the distal radius were treated during a 3-year period; 211 of them were evaluated at an average of 16 months after the accident according to the score of Gartland and Werley as modified by Sarmiento. Furthermore, we developed our own score for evaluating the influence of radiological parameters on the functional outcome.

RESULTS

According to the AO classification, there were 20 patients with an A2, 71 an A3, 11 a B, 35 a C1, 44 a C2, and 30 a C3 fracture. Of 211 patients, 28 (13%) had a step-off in the articular surface of over 1 mm, resulting in a 24% reduction of the range of motion compared to the non-injured wrist (p<0.05). Patients with a radial shortening of more than 3 mm (n=12) had a 21% reduction of pro- and supination compared to the non-injured side (p<0.05). The radial tilt and the palmar inclination did not have a direct influence on the functional outcome. Patients treated with K-wire pinning and with an initial palmar inclination of less then -15 degrees had a significantly higher secondary loss of palmar inclination of 9 degrees compared to all others (p<0.05) at the final follow-up.

CONCLUSION

The main radiological factors influencing the functional outcome of fractures of the distal radius are radial shortening and a step-off in the articular surface.

[Percutaneous dorsal versus open instrumentation for fractures of the thoracolumbar border. A comparative, prospective study]

STUDY DESIGN

A prospective clinical study.

OBJECTIVE

To evaluate whether a percutaneous dorsal instrumentation of thoracolumbar fractures prevents irreversible damage to the spinal muscles.

METHODS

A total of 57 patients with thoracolumbar fractures (Th12-L4) were divided into two groups, comparable in terms of gender, fracture level, classification and surgical concept. In the first, 24/57 patients were treated using an open procedure (OP-G); in the second, 33/57 were treated via percutaneous dorsal instrumentation (PER-G). Fracture localisation and classification, accuracy of pedicle screw placement, perioperative blood loss, OR- and image converter time as well as muscle damage (needle-EMG) were evaluated.

RESULTS

OR- and image converter time as well as the accuracy of pedicle screw placement were not statistically different between groups. The difference in perioperative blood loss [43 (10-90) ml (PER-G) vs [870 (570-1,200 ml (OP-G)] was statistically significant (P <0.005). Needle EMG revealed no muscle damage, and the physiological activity and muscle potentials were normal (PER-G). In the OP-G, polyphasic EMG signals were most common (80%), a sign of the drop-out of numerous motor units.

CONCLUSIONS

The open procedure caused permanent and significant damage to the strongest extensors of the autochthonus back musculature, the m. multifidus, which results from multisegment combined damage to the r. posterior nervi spinalis and muscle fibres. In contrast, percutaneous placement of an internal fixative reduces perioperative access morbidity causing little iatrogenic damage to back muscles and only a minor perioperative blood loss.

Traumatische Hemipelvektomie

With an incidence of only 0.6% of all pelvic injuries, traumatic hemipelvectomy is a rare event. It is defined as open or closed avulsion of one hemipelvis with occlusion or disruption of the main vessels and lengthening or disruption of the nerves, often complicated by urogenital or anorectal injuries. The mechanism of injury in this case is a typical one with extreme abduction and external rotation of the leg, causing sacroiliac joint disruption and symphysis separation. Two other mechanisms described are avulsion when the leg becomes entangled in a piece of machinery or a massive crushing at the groin. After a fast treatment in the field, the patient described was treated with immediate open revision, tamponade and stabilization of the pelvis. Upper leg preservation by reconstruction of the femoral vessels with vascular prostheses was attempted. Because of a broad necrosis of soft tissues, early completion of the hemipelvectomy was performed. The patient recovered well. Miction and bowel evacuation as well as sexual function could be preserved. The resulting quality of life is high and the patient is socially reintegrated without problems.

Verletzungen des Fußes beim polytraumatisierten Patienten

Foot injuries in polytraumatized patients are not critical for survival but for the later quality of life. Closed fractures or dislocations of the foot are frequently overlooked or misinterpreted in association with polytrauma, which leads to severe functional impairment in those patients who survive. Repeated clinical examinations and early radiographic examinations are essential in the unconscious patient after resuscitation. Emergent indications for surgery even in the presence of multiple injuries are open injuries, incarcerated soft tissues, manifest compartment syndrome of the foot, and neurovascular injury. The decision on limb salvage or amputation has to be individualized with respect to the patient's overall condition and the severity of local trauma to the foot. The "life before limb" principle has to be respected. Emergent reduction of fracture dislocations of the talus, calcaneus, Chopart's and Lisfranc's joints via direct approaches and temporary transfixation with K-wires should be attempted in a first step whenever possible. Additional external fixation facilitates wound care and prevents soft tissue contractions until definite internal fixation becomes feasible. Early soft tissue coverage is always sought in order to avoid infection.

Einfluss von Rettungsmittel und Zielklinik auf die Letalität nach Polytrauma

BACKGROUND

The aim of this study was to document the present knowledge from the medical literature on (1) efficacy of aeromedical evacuation (helicopter emergency medical service, HEMS) and (2) influence of the level of the first receiving hospital on mortality of patients.

METHODS

Systematic review of the literature between 1970 and 2003; identification of studies with an evidence level of at least III and included control group; own results.

RESULTS

(1) 17 studies concerning the efficacy of HEMS were included into the review. No single study yielded shorter rescue times with the use of HEMS. 11 of 17 studies showed a significantly higher survival rate (8.2 to 52%) with the employment of HEMS especially with mid-degree polytrauma. (2) All 6 relevant studies dealing with hospital level found a considerable lower mortality rate (19 to 42%) for patients treated primarily at a level 1 trauma center or comparable institution.

CONCLUSIONS

The analyzed studies showed a trend toward decreased mortality rates with the employment of HEMS. Considering the comparable hospital level and even longer rescue times with HEMS, these differences can be explained with higher quality of initial diagnosis and treatment of the HEMS rescue team. Furthermore, mortality rates can be lowered significantly through primary treatment at a level 1 trauma center. Thus, the more flexible choice of the first receiving hospital represents a specific, clinically relevant advantage of HEMS in emergency medicine.

Foot function after subtalar distraction bone-block arthrodesis

Subtalar distraction bone-block arthrodesis for malunited calcaneal fractures was performed in 31 patients (26 men, five women), with a mean age of 38.5 years. The mean time from injury to arthrodesis was 36 months. There were no cases of nonunion.

One patient had an early dislocation of the bone block requiring a repeat arthrodesis, and one had a soft-tissue infection. The mean AOFAS hindfoot score improved significantly from 23.5 before operation to 73.2 at a mean follow-up of 33 months (p > 0.001). Compared with the unaffected side, the talocalcaneal height was corrected by 61.8%, the talus-first metatarsal axis by 46.5%, the talar declination angle by 38.5% and the talocalcaneal angle by 35.4%. Dynamic pedobarography revealed a return to normal of the pressure distribution during roll-over and a more energetic gait. The distribution of local transfer of load correlated well with the AOFAS score. The amount of correction of the heel height correlated with a normal pattern of pressure transfer on the heel (p < 0.05).

Vorteile der minimal-invasiven Reposition, Retention und Ilizarov-(Hybrid)Fixation bei Pilon-tibiale-Frakturen unter besonderer Ber�cksichtigung von C2-/C3-Frakturen

Between October 1993 and September 1999 a total of 62 tibial pilon fractures in 59 patients were treated at the Clinic for Trauma and Reconstructive Surgery, University Hospital Carl-Gustav-Carus, Technical University Dresden. In a retrospective study 49 patients with 50 tibial pilon fractures (81%) could be examined an average of 28 months after injury. The purpose of this study was to compare clinically and radiographically the healing results obtained after using the Ilizarov technique in combination with minimally invasive internal fixation (group I) with those after a conventional surgical procedure (internal fixation with a plate, external fixation with or without minimally invasive internal fixation, and screw fixation exclusively, group II) and to evaluate the efficacy of the Ilizarov technique. Data analysis showed a significantly higher incidence of 43 C2/C3 fractures in Ilizarov group I (73%) than in group II (33.3%). Severe soft tissue injuries and particularly open injuries had a significantly higher incidence in Ilizarov group I (100%) than in group II (38%). Despite the high incidence of C2/C3 fractures and severe soft tissue injuries in group I, there was no incidence of pseudarthrosis or osteitis in the further course and there was no need for arthrodesis during the long-term course. After therapy with a conventional surgical technique, the incidence of osteitis was 5% and of delayed union of a fracture 2.5% and arthrodesis was necessary in 8%. A disadvantage of the Ilizarov system was the relatively frequent incidence of pin infection (45%) necessitating surgical debridement in 18%. The efficacy of the treatment of 43 C2/C3 fractures with the Ilizarov technique was obvious by a statistically significantly better Maryland Foot Score in comparison with group II. More than 87% of the patients treated with the Ilizarov technique and only 38% of the patients treated with a conventional surgical procedure obtained a very good or good score. According to these findings, the Ilizarov technique in combination with minimally invasive internal fixation is an effective method to treat complicated tibial pilon fractures with severe soft tissue trauma.

[Calcaneus fractures. Open reduction and internal fixation]

AIM OF THIS STUDY

Critical analysis of the medium-term results of open reduction and internal fixation (ORIF) of displaced intra-articular calcaneus fractures with a standardized protocol in a greater patient cohort.

METHODS

From October 1993 to December 1999 314 patients (mean age 42.3 years) with 348 calcaneus fractures were seen at the Dresden University Hospital. 41 fractures were open, 4 with 1st degree, 28 with 2nd and 9 with 3rd degree soft tissue damage. 275 displaced intra-articular fractures were treated with ORIF, 262 (95.3 %) with plate osteosynthesis via an extended lateral approach. 169 patients could be evaluated at a mean of 18 months (range 10-47 months) postoperatively with an extended protocol of questionnaire, physical and radiographic examination.

RESULTS

The Maryland Foot Score after 18 months follow-up averaged 80.8/100, the mean Zwipp score averaged 146.4/200. The functional result with the Merle d'Aubigné score was judged good to excellent in 86% of cases. Rates of deep infection and superficial wound edge necrosis increased significantly with open fractures and delay in surgery of more than 2 weeks after injury in closed fractures. Clinical results were adversely affected by even minor residual steps in the posterior facet (1-2 mm) as judged by CT or Brodén views (p < 0.001). Böhler's tuberosity-joint-angle had an impact on the final result when falling short compared to the unaffected contralateral side by more than 30% (p < 0.001).

CONCLUSIONS

Management of intra-articular calcaneus fractures with a standardized protocol of ORIF and early mobilization leads to reproducible good or excellent clinical results in a majority of patients. New approaches like an interlocking calcaneus plate, the use of subtalar arthroscopy, early soft tissue coverage for complex open injuries and percutaneous screw fixation for selected fractures should further improve prognosis.

[Clinical evaluation of the distal femoral nail]

METHOD

The clinical results after DFN-osteosynthesis of n=56 AO-classification 33A-fractures (32%), 33C-fractures (43%), 32X-fractures (21%) and pseudarthrosis treatment (4%) are presented.

RESULTS

Follow up was available for 54 fractures (96%) after a mean of 1.2 years (range 0.2-2.8 years). 95% of patients showed full-weight-bearing with a knee flexion of 120 (60-140) degrees. Extension-deficit >10 degrees was observed in 5.4%. All fractures were consolidated. One soft-tissue infection, one partial loss of reduction and one implant failure were observed. A significant axial malalignment was found radiologically in 17%, a loosened spiralblade or locking screw in 7.4%. In 91% of cases the result was judged as good to excellent by patients and surgeons.

CONCLUSION

The mechanical stability of the implant allows a save osteosynthesis of unstable supracondylar and complete articular femoral fractures without additional bone grafting. Mechanical stability and minimal invasive operative technique permit a safe bone healing without major complications.

Healing of Achilles tendon, an experimental study: part 2--Histological, immunohistological and ultrasonographic analysis

In 105 rabbits the course of healing was examined at one, two, four, eight and 12 weeks (21 rabbits per group) after an experimental Achilles tendon rupture. The following treatment modalities were compared: A) primary functional treatment; B) operative functional treatment (resorbable suture); and C) operative functional treatment with fibrin glue. For the functional (after)-treatment a special orthosis was applied. A 7.5 MHz Ultrasound probe was used for ultrasonographic evaluation. The histological specimens were stained in Masson-Goldner and Azan technique. Collagen Type III was depicted immunhistologically. A semiquantitative fibrocyte count was performed. The histological results showed a smooth healing in the primary functional treatment group (A), reaching parallel orientation of collagen fibers at 12 weeks. In the suture group (B), a secondary gapping of the tendon stumps was detectable after one week as in all other groups. In the fibrin group (C), the fibrin was resorbed after four weeks without essential influence to the course of healing. At 12 weeks the histological evaluation in all groups showed approximately normal tendon pattern. Immunohistochemically, all groups showed cell-associated positive reactions for type-III collagen after one week with a maximum after two weeks. The semiquantitative fibrocyte count in the primary functional group showed a maximal number after one week. In the fibrin glue and suture groups the maximal number could be found after two weeks. Sonographically an increase in tendon thickness was detectable up to the fourth week in all groups. The secondary gapping of the tendon stumps in the suture group could also be detected sonographically. The echogenicity of the tendon during the course of healing showed increasing homogeneity and parallelism in all groups. At 12 weeks the echogenicity was comparable in all groups. The experiment suggests the equivalence of primary functional treatment to a combination of operative and functional therapy in Achilles tendon rupture.

[Clinical trial with the distal femoral nail]

METHODS

The clinical results after DFN-osteosynthesis of n = 56 AO-classification 33A-fractures (32%), 33C-fractures (43%), 32X-fractures (21%) and treatment of non-union (4%) are presented.

RESULTS

Follow-up was available for 54 fractures (96%) after a mean of 1.2 years (range 0.2-2.8 years). 95% of patients showed full-weight-bearing with a knee flexion of 120 (60-140) degrees. Extension-deficit > 10 degrees was observed in 5.4%. All fractures were consolidated. One soft-tissue infection, one partial loss of reduction and one implant failure were observed. A significant axial malalignment was found radiologically in 17%, a loosened spiralblade or locking screw in 7.4%. In 91% of cases the result was judged as good to excellent by patients.

CONCLUSION

The mechanical stability of the implant allows a save osteosynthesis of unstable supracondylar and complete articular femoral fractures without additional bone grafting. Mechanical stability and minimal invasive operative technique permit a safe bone healing without major complications.

[Functional postoperative treatment of internally fixed ankle fractures with a flexible arthrodesis boot (Variostabil)]

AIM

Postoperative treatment following osteosynthesis of ankle fractures in a flexible arthrodesis boot (Variostabil) aims at fast restoration of the function of the injured extremity while allowing early full weight bearing. This treatment regimen was validated in a clinical and experimental study.

METHODS

(1) In the clinical study part, 56 patients with internally fixed ankle fractures received after treatment with the arthrodesis boot for 6 weeks. (2) In the experimental study part, the intravascular pressure was recorded in a foot vein of 8 healthy volunteers during knee bends.

RESULTS

(1) No implant failure or secondary dislocation was seen due to the after treatment. All patients rated subjective comfort and mobility as excellent. 90.5 % had a good to excellent functional result with the Philips Score. (2) Wearing the arthrodesis boot effected significantly faster venous outflow (25.8 +/- 15.2 vs. 11.3 +/- 6.0 mmHg/sec, p < 0.05) and higher pressure amplitude (53.6 +/- 12.0 vs. 26.5 +/- 9.6 mmHg) during knee bends, compared to a below-the-knee plaster cast.

CONCLUSIONS

The flexible arthrodesis boot offers safe protection of ankle fractures combined with superior functional performance (undisturbed gait, training of the ankle joint, high patient comfort and mobility, accelerated venous outflow) as compared to cast immobilization.

[Retrograde locking nail osteosynthesis of distal femoral fractures with the distal femoral nail (DFN)]

Non-operative treatment with immobilization or isometric traction has been abandoned as treatment for fractures of the distal femur at the end of the 1960ies. The technique of open reduction and internal fixation with a condylar plate as suggested by the AO has been the golden standard since the 1970ies. However, anatomic reconstruction of the condylar region with interfragmentary screw fixation and axial realignment of the femur shaft with a plate are challenging procedures especially in the presence of severely compromised soft tissues and put periosteal blood supply at risk. Soft tissue complications, axial malalignment and delayed fracture healing times led to the consideration of alternative techniques, such as intramedullary nailing which has been practiced with success since the 1940ies by Gerhard Küntscher and colleagues for femoral shaft fractures with minimal complication rates and improved results after closed reduction. The era of retrograde femoral nailing began with the systematic approach through the intercondylar notch by Green. This paper reviews the biomechanical properties, indication, technique as well as potential hazards and pitfalls of fracture management with the AO "distal femoral nail" (DFN). With appropriate application this technique is suitable for all fractures of the distal third of the femoral shaft including highly instable bicondylar fractures without damage to the soft tissues and the knee joint.

[Intramedullary nail placement with percutaneous Kirschner wires. Illustration of method and clinical examples]

Unreamed nailing is an established method for internal fixation of femoral und tibial shaft fractures. The interlocking technique allows the stabilization of metaphyseal fractures, too, but the risk of malalignment increases. The "palisade method" presented here allows the precise positioning of the nail in the marrow cavity and works as a tool for successful minimally invasive nailing in the meta/epiphyseal region. The method is easy to use and suited particularly in combination with the UFN and UTN, but is in principal applicable to other nails, too. In contrast to the "Poller Screw" method developed by Krettek et al., no biomechanical augmentation of the osteosynthesis remains.

Healing of the Achilles tendon: an experimental study

Biomechanical properties of healing ruptures in the Achilles tendon of rabbits were examined after two, four, eight and 12 weeks. Treatment modalities were (n7): a) suture, b) fibrin-glue, c) non-surgical treatment. All animals received a functional aftertreatment consisting of a special orthotic support and free ambulation. For biomechanical testing a fixation-technique was applied that guaranteed intratendinous rupture. After two weeks, the tendons treated with fibrin glue showed better results (stiffness, maximum force to rupture, tensile stress to rupture) compared with the non-surgically treated group. The results for sutured tendons were in between those for the other groups. After four weeks, the results for sutured and for glued tendons were nearly equal and slightly better than the tendons in the non-surgical group. Late results revealed comparable biomechanical properties among all treatment groups and control tendons, suggesting our conclusion that non-surgical treatment is equal to repair using sutures or using fibrin glue as measured by stiffness and tensile stress.

[Injuries of the inferior tibiofibular syndesmosis]

The incidence of isolated distal tibiofibular syndesmotic ruptures in acute ankle sprains lies between 1% and 11%. These injuries are frequently overseen or misdiagnosed as anterolateral rotational instability of the ankle and often become apparent through protracted courses. Although the pathomechanics and extent of syndesmotic injuries have been systematically described by Lauge-Hansen and Weber, no generally accepted guidelines exist as to when these complex injuries are to be treated surgically to ensure sufficient and stable healing of the syndesmosis besides correct alignment of the distal fibula. So far, systematic follow-up regarding syndesmotic injuries in ankle fractures is missing, although it has long been recognized that tibiofibular diastasis secondary to chronic syndesmotic instability leads to external rotation of the talus. In combination with a valgus position of the talus, this instability leads to a decrease in the contact area which results in posttraumatic arthritic changes. This paper reviews the standard diagnostic and therapeutic procedures for acute syndesmotic ruptures in fracture dislocations of the ankle. Among the few corrective procedures advocated for chronic syndesmotic insufficiency are tibiofibular arthrodesis, synthetic ligament substitutes, and tenodesis with the peroneus brevis tendon. A sufficient reconstruction must restore the stability of the ankle mortise and alignment of the fibula in the tibiofibular incisura to ensure limitation of talar rotation. Therefore, a tenodesis was developed which substitutes the three important ligaments of the syndesmotic complex. The Casting procedure for chronic syndesmotic insufficiency was modified with reconstruction of the interosseous tibiofibular ligament in addition to the anterior and posterior tibiofibular ligaments. The resulting three-point fixation of the distal fibula appears more anatomically, physiologically, and biomechanically advantageous. The operative procedure is given in detail. Distal tibiofibular syndesmosis. Persistent instability of the distal syndesmosis. Ankle fractures. Syndesmotic screw.

[Effect of logistic and medical emergency resources on fatal outcome of severe trauma]

122 cases of patients who died in sequel of an accident (recruitment period 1993/94, mean ISS 40 +/- 19) in reach of air rescue base Dresden, Germany, were examined. Data were assessed from autopsy protocol and the protocol of the physician who treated on scene. We analyzed the time course of the emergency, the scheduled emergency medical service and the quality of prehospital diagnosis and therapy by the emergency team. The mean response time was 8.1 +/- 5.9 min, the mean distance between EMS bases und incident location 5.9 +/- 5.7 km. In 94.4% of all cases a mobile intensive care unit--with an emergency physician as crew member--was on scene, in 5.6% a paramedic car. Air rescue by helicopter, including an emergency physician, was performed only in 8.7% of all cases although a helicopter was available in 54% of all accidents. Mechanisms of injury were traffic accident (71.4%), fall (14.3), 5.9% accident on building site, shot and stab injuries (5.9%) and burns (1.7%). 82 patients reached the emergency room alive (67.2% mean ISS 37 +/- 18). Only 26% of all patients were transported directly to a level I trauma center. Mean survival time of all 122 patients was 146 +/- 30.4 h. Severe head injury described by autopsy protocol was diagnosed on scene in 82%. Preclinical treatment was:intubation and ventilation (63%), O2 insufflation (17.4%), no specific treatment (19.6%). Severe thoracic trauma was diagnosed in 54%. Preclinical treatment was:intubation and ventilation (64.8%), O2 application (18.8%), no specific treatment (16.2%). Severe thoracic trauma with hemato-pneumothorax (n = 26) was recognized by the emergency physician in 65.6%, specific therapy (application of chest drain) was performed in 7.1%. Preclinical diagnosis rates concerning abdominal trauma were 29% and 27.8% in case of unstable pelvis fracture. Hemorrhagic shock related to these injuries was found in 44.2%, mean resuscitation volume applicated in these cases was 960 +/- 610 ml. Typical faults in diagnosis and treatment were underestimating of severe trunk trauma and non-consistent use of invasive treatment procedures. Primary transport of the severely injured patient to a level I trauma center by helicopter was performed only rarely.

[Fatal aorto-esophageal fistula as a late complication of traumatic aortic rupture]

We report on a case of a 23 years old man who was polytraumatized in a car accident. He survived with excellent clinical outcome, but 113 days after the accident he collapsed, massive bleeding out of the mouth started and the patient died within a few minutes. A gastric ulcer bleeding was assumed, but autopsy showed the break-in of a posttraumatic aortic aneurysm into the esophagus. The difficulties of in time diagnosis of thoracic aorta lesions are discussed.

[Functional treatment of acute Achilles tendon rupture. A histological, immunohistological and ultrasonographic analysis of the animal model]

In 105 rabbits the course of healing was examined at 1, 2, 4, 8 and 12 weeks (21 rabbits per group) after an experimental Achilles tendon rupture. The following treatment modalities were compared: a. operative functional treatment (resorbable suture, Kleinert technique) b. operative functional treatment with fibrin glue c. primary functional treatment. For the functional (after)-treatment a special orthosis was applied. A 7.5 MHz Ultrasound probe was used for the ultrasonographic evaluation. The histological specimens were stained after Masson-Goldner with Azan. Collagen Type III was depicted immunohistologically with polyclonal antibodies. A semiquantitative fibrocytes count was performed. The histological results showed a smooth healing in the prim. functional treatment group reaching parallel orientation of collagen fibers at 12 weeks. In the fibrin glue-group the fibrin was resorbed after 4 weeks without essential influence to the course of healing. In the suture-group a secondary gapping of the tendon stumps was detectable. At 12 weeks the histological evaluation in all groups showed approximately normal tendon pattern. Immunohistochemically all groups showed cell-associated positive reactions for type III-collagen after 1 week with a maximum after 2 weeks. The semiquantitative fibrocyte count in the primary funct. group showed a maximal number after 1 week, in the fibrin glue- and suture-groups the maximal number could be found after 2 weeks. Sonographically an increase in tendon thickness was detectable up to the 4th weeks in all groups. The secondary gapping of the tendon stumps in the suture group could be detected sonographically. The echogenicity of the tendon during the course of healing showed increasing homogeneity and parallelism in all groups. At 12 weeks the echogenicity was comparable in all groups. The experiment could prove the equivalence of the primary functional treatment to operative therapy in Achilles tendon rupture.

[Biomechanical studies of human Achilles tendon rupture]

The biomechanical properties of human Achilles tendon are described with a computer-controlled material-testing machine. With an optimized fixation device for the muscle-tendon-calcaneus system the rupture was intratendineal. The tendons were compared for different rupture speed (1000 mm/min vs 100 mm/min), sex and age ( < 35 years vs > 35 years). The tendons ruptured at 1000 mm/min had better results in terms of maximum rupture force, stiffness and tensile stress, while the results for elongation and energy were less good. None of these differences were statistically significant. Significant differences were found between the sexes: male tendons had higher maximum rupture force and stiffness and a larger cross-sectional area. In the younger tendons significantly higher tensile rupture stress and lower stiffness were found.

[Functional treatment of acute rupture of the Achilles tendon. An experimental biomechanical study]

In 84 adult rabbits the biomechanical properties of healing Achilles tendon rupture were examined 2, 4, 8 and 12 weeks (21 each group) after the injury. For the first time a mop-end-tear was performed. The following treatment modalities were applied (7 rabbits in each subgroup): (a) operative functional treatment (resorbable suture; Kleinert techniques); (b) operative functional treatment (fibrin glue); (c) primary functional treatment (conservative). The functional after treatment in all groups was performed with a specially developed orthesis, which was taped to the limb. For biomechanical testing a newly developed fixation technique (cryo-clamp) was applied, which guaranteed secure intratendineal rupture. After 2 weeks the fibrin glue-treated tendon ruptures showed the best results with regard to stiffness, tensile stress and max. rupture force. These results and a higher tensile stress of the sutured tendons were significantly different from those in the conservatively treated groups. After 4 weeks the stiffness in the fibrin group and the energy and rupture force in the suture group were significantly higher than in the group treated conservatively. The 8-week results revealed comparable biomechanical properties. The only significant difference was a higher energy in the fibrin glue group than in the conservative treatment group. The experiment revealed no significant biomechanical differences after 3 months. Compared with the results recorded for plaster immobilization in the literature, the functional treatment resulted in a significantly faster course of healing.

In vivo muscle force and elastic energy storage during steady-speed hopping of tammar wallabies (Macropus eugenii)

In order to evaluate the role of elastic energy recovery in the hopping of macropodids, in vivo measurements of muscle&shy;tendon forces using buckle force transducers attached to the tendons of the gastrocnemius (G), plantaris (PL) and flexor digitorum longus (FDL) of tammar wallabies were made as the animals hopped on a treadmill at speeds ranging from 2.1 to 6.3 m s-1. These muscles and tendons constitute the main structures that are most important in energy storage and recovery. Electromyographic recordings from the lateral gastrocnemius and plantaris muscles, together with high-speed films (200 frames s-1) and video (60 fields s-1), were also used to correlate muscle activation and kinematic patterns of limb movement with force development. On the basis of in situ calibrations of the buckle transducers, we found that muscle forces and elastic energy storage increased with increased hopping speed in all three muscle&shy;tendon units. Elastic energy recovery reached a maximum of 25 % of metabolic energy expenditure at 6.3 m s-1 and is probably greater than this at higher speeds. Force sharing among the three muscles was consistently maintained over this range of speeds in terms of recruitment. Although forces and stresses were generally comparable within the gastrocnemius and plantaris muscles, maximal tendon stresses were considerably greater in the gastrocnemius, because of its smaller cross-sectional area (peak muscle stress: 227 versus 262 kPa; peak tendon stress: 36 versus 32 MPa, G versus PL). As a result, energy storage was greatest in the gastrocnemius tendon despite its much shorter length, which limits its volume and, hence, energy storage capacity, compared with PL and FDL tendons. Forces and stresses (17 MPa maximum) developed within the FDL tendon were consistently much lower than those for the other two tendons. Peak stresses in these three tendons indicated safety factors of 3.0 for G, 3.3 for PL and 6.0 for FDL. The lower stresses developed within the tendons of the plantaris and, especially, the flexor digitorum longus may indicate the need to maintain sufficient stiffness for phalangeal control of foot placement, at the expense of reduced strain energy recovery.

External skin excision in the sebaceous nose and supratip deformity

Some sebaceous noses cannot be properly reduced in size because of redundant skin. After standard rhinoplasty some noses develop a supratip deformity that recurs even after subcutaneous removal of the scar tissue. These noses can be corrected only by wedge-shaped skin excision. Most patients much prefer a pleasantly shaped nose, even at the cost of a midline scar on the nose. Most surgeons are hesitant to add scars to the face. However, the vast experience with wounds following accidents, tumor excisions, or corrections of malformations has shown that generally scar formation on the nose is inconspicuous. Nineteen patients were treated successfully by skin excision at the time of primary rhinoplasty or by a second operation.