Biomedical subjects

C Hurschler

Publications and source records attributed to C Hurschler.

23 records · Page 2Linked to original sources

PubMed1995

The effects of elevated compartment pressure on tibial arteriovenous flow and relationship of mechanical and biochemical characteristics of fascia to genesis of chronic anterior compartment syndrome.

PURPOSE: The purpose of this study is to evaluate the effects of increased compartment pressure on anterior tibial arteriovenous flow patterns and to determine whether mechanical and biochemical properties of fascia are responsible for compartment pressure abnormalities. METHODS: Twenty patients with chronic anterior compartment syndrome (CACS) and 20 age-matched control subjects had compartment pressure measurements and analysis of tibial arterial and venous flow before and after fasciectomy. Fascia specimens were evaluated for thickness, stress failure, structural stiffness, and total collagen content and prevalence of collagen cross-linkage. RESULTS: Pressures were significantly elevated in patients with CACS versus control subjects (23.8 mm Hg vs 6 mm Hg). No significant difference in tibial arterial flow could be detected in either group (43 cm/sec mean vs 41.9 cm/sec mean). Venous drainage was severely impaired in patients with CACS but not in control subjects. CACS fascia was thicker and stiffer than control fascia specimens (0.35 mm +/- 0.12 mm, 109 +/- 65 MN/mm; versus 0.22 mm +/- 0.06 mm; 60.3 +/- 22 MN/mm). Fasciectomy normalized postoperative compartment pressures and improved venous drainage. Collagen content per unit mass was similar for both CACS and control fascia specimens, although collagen cross-linking was significantly lower in the CACS fascia than in the controls. CONCLUSIONS: Tibial venous drainage is impaired, but arterial flow is not in patients with CACS. Fascia thickness and structural stiffness can account for increased pressure in CACS compartments. Collagen content and cross-linkage are unrelated to fascia stiffness or thickness. Postoperative improvement in vascular hemodynamics and reduction in compartment pressure is caused by increased capacitance in the compartment after fasciectomy.

Anterior Compartment Syndrome↗

PubMedDate not supplied

Mechanical and biochemical analyses of tibial compartment fascia in chronic compartment syndrome.

Increases in compartment pressure associated with chronic compartment syndrome (CCS) may be due to changes in the mechanical properties and/or thickness of fascia (4,22). To explore this possibility, we compared the mechanical and biochemical characteristics (stiffness, thickness, time-dependent response, collagen content, and collagen crosslinking) of fascia from patients with symptomatic anterior compartment syndrome to fascia from adjacent collateral compartments. We tested 43 specimens harvested from 20 individuals during surgical fasciectomy. Properties of normal (lateral)-compartment (NC) and pathological (anterior)-compartment (PC) fascia were mechanically tested in the axial and transverse directions forming four groups. An external control group (EX) of six specimens of anterior and lateral-compartment fascia harvested from amputated legs was also included in the study. PC fascia was found to be thicker and structurally stiffer (elastic modulus times thickness) in the axial direction than was NC fascia (p < or = 0.05). No significant differences were found between NC and PC time-dependent response, although significant differences between percent relaxation in the pooled axial and transverse direction specimens were observed. No differences were found in the collagen content, as measured by hydroxyproline (Hyp) concentration, between NC and PC fascia. PC fascia was found to have less collagen crosslinking by hydroxylyslpyridinoline (HP) concentration. In conclusion, although this study does not elucidate etiological factors in CCS, the changes found in PC fascia suggest that fascial mechanical properties contribute to the pathology.

Adolescent↗

PubMedDate not supplied

[Biomechanical testing of different ventral fixation devices on the bovine lumbar spine].

AIM: The primary stability of ventral fixation systems has been improved over the past years and special implants supporting minimally invasive procedures have been developed. The aim of this study was to analyze the primary stability of several of these implants. METHODS: Thirty (30) lumbar segments from 5 to 7-month-old calves were harvested and tested on a pure moment apparatus (PMA) as well as a modified materials testing machine (MTS) according to the European standard recommendations of Wilke et al. Three different implant systems (MACS, Centaur and Z-plate) were included. ROM, neutral zone and stiffness were tested on the PMA up to 10 Nm, stiffness at an eccentric axial load of up to 1500 N was tested on the MTS. Bone density was investigated for all specimens. Statistical analysis was performed by ANOVA and LSD tests. RESULTS: Primary stability was improved by all fixation devices compared to the physiological specimen. The MACS implant was more stable than the Centaur and Z-plate with the exception of in lateral bending [where the Z-plate was stiffer]. Bone density was comparable in the three different experimental groups. CONCLUSION: Minimal invasive ventral fixation devices are becoming popular. The primary stability of the minimal invasive MACS was comparable to those of other well-known ventral fixation devices of the lumbar spine.

Animals↗

PubMedDate not supplied

[Effects of harvesting the central third of the patella tendon on the kinetics of the knee joint and the retropatellar pressure].

AIM: This biomechanical study was performed to evaluate the consequences of removing the central part of the patellar tendon on the kinematics and kinetics of the femoro-patellar joint. The tendonectomy was performed in the same manner as is frequently done during anterior cruciate ligament reconstructions. Of particular interest in this study was to identify potential factors of the patellar tendon resection which could result in anterior knee pain. METHOD: A simulated isokinetic knee extension from 120 degrees of flexion to full extension was performed on nine human knee cadaver specimens. Joint kinematics was evaluated with ultrasound sensors, and retropatellar contact pressure was measured using a thin-film resistive ink pressure measuring system. Data were taken before and after resection of the central third of the patellar tendon. RESULTS: Harvesting of the central third of the patellar tendon resulted in an elongation of the remaining patellar tendon by less then 0.5 mm. Furthermore, increases in patellar flexion lower than 1 degree were observed. Small changes in retropatellar pressure were also observed. CONCLUSION: The shortening of the patellar tendon due to tendon removal, as already suggested in several previous studies, is not attributed to the removal of the central portion of the tendon itself, but more likely due to secondary scarring contraction of the tissue. The changes of the patellarkinematics and the retropatellar pressure observed in this study are probably not of any clinical significance.

Adult↗

PubMedDate not supplied

Medially based anterior capsular shift of the glenohumeral joint. Passive range of motion and posterior capsular strain.

The effect of a medially based anterior capsular shift on translational and rotational range of motion and posterior capsular strain was investigated in an in vitro model. Six cadaveric shoulders were tested in a robot-assisted shoulder simulator. Translational and rotational range of motion were reduced by the capsular shift, particularly with the shoulder at higher elevation angles. At 60 degrees of elevation, anterior translation was decreased 1.9 +/- 2.9 mm, and posterior translation was decreased 2.3 +/- 6.2 mm. External rotation was decreased 11.5 degrees +/- 10.2 degrees, and internal rotation was decreased 8.9 degrees + 5.7 degrees. Posterior capsular strain change was dependent on elevation angle. At 30 degrees of elevation, strain tended to increase 5.0% +/- 7.3% in the inferior aspect and 2.9% +/- 2.6% in the superior aspect, with no change detected in the medial aspect. At 60 degrees of elevation, strain increased 6.6% +/- 8.0%, 3.2% +/- 2.6%, and 4.4% +/- 3.5% in the inferior, middle, and superior aspects, respectively. Our results support the use of the medially based anterior shift for shoulders with anterior-inferior instability or multidirectional instability with posterior involvement.

Adult↗