Tobias Vogel

Function-Orientated Structural Analysis of the Proximal Human Femur

In his model of the biomechanics of the proximal human femur, Friedrich Pauwels assumes a resultant force acting on the femoral head that is created by the partial body weight and the force of the abductor muscles inserting at the greater trochanter. This model suggests a tensile force in the region of the greater trochanter. An exact examination of the muscle insertions at the greater trochanter resulted in a contrasting hypothesis assuming a local compression stress in the region of the greater trochanter. The aim of this study was to examine which hypothesis is favored by the internal architecture of the proximal femur. Based on the architectural software Allplan®, we performed an extended analysis of the trabecular structure within the proximal femur using CT scans of 10 human cadaver femora altogether. According to our results, both the medial and the trochanteric trabecular systems are orientated approximately perpendicular to the arcuate trabecular system [angles between systems ranging from 84.6 to 93.0° (mean angle 90.7°) and from 80.9 to 86.5°, (mean angle 84.9°), respectively]; furthermore, the medial trabecular system is orientated perpendicular to the epiphysis of the femoral head (mean of angles: 94.7°). The biomechanical interpretation of these results strongly supports the idea of compressive stress in the region of the greater trochanter and makes a predominant tensile force of the abductor muscles highly unlikely.

DYSPLASIA EPIPHYSEALIS HEMIMELICA OF THE DISTAL ULNA: A CASE REPORT AND REVIEW OF THE LITERATURE

Dysplasia epiphysealis hemimelica (DEH) or Trevors Disease is a very rare disease with an estimated incidence of one in 1.000.000. The majority of cases reported affect the lower limb and only 25 case reports of 33 cases with affection of the upper limb have been published. Here we present a case of DEH affecting the distal ulnar epiphysis and the lunate in an eleven-year-old girl, a DEH location described extremely rarely before. We firstly do not only present clinical and radiological findings (plane radiographs, CT, MRI), but also the surgical approach and the histopathological results of DEH in this uncommon location. Although extremely rare, DEH should be considered also in non-typical locations.

[Outcome 4 years after isolated single-bundle posterior cruciate ligament reconstruction].

BACKGROUND The purpose of this study was to evaluate the clinical and radiological results after isolated reconstruction of the posterior cruciate ligament (PCL) using semitendinosus (ST) and gracilis (GT) tendon grafts with the arthroscopic single-bundle technique. MATERIALS AND METHODS Following PCL reconstruction using the single-bundle technique performed between 2002 and 2005, 14 patients (2 women, 12 men) prospectively underwent a standardized follow-up examination after an average postoperative time of 4 years. All patients included in this study had isolated insufficiency of the PCL and symptomatic instability. The exclusion criteria were the presence of a complex knee joint instability and the implementation of additional stabilizing measures or another method of PCL reconstructive surgery. The mean follow-up time was 47.2 ± 8.7 months. Preoperative and postoperative stress radiographs were taken using the Telos stress instrument in order to evaluate the posterior translation. Knee joint function and degree of activity were recorded using the Tegner activity score, the subjective IKDC score and the overall IKDC score. RESULTS The posterior tibial translation of 10.1 ± 1.7 mm had an overall average improvement to a postoperative value of 4.6 ± 2.3 mm (p < 0.001). The patients showed a significant improvement in the Tegner activity score from an average 2.7 ± 0.8 points to 5.7 ± 1.3 points (p < 0.001). Evaluation of the subjective IKDC showed a significant improvement from a preoperative score of 41.32 ± 11.23 points to a postoperative score of 65.08 ± 13.51 points (p < 0.001). In total, 10 patients (71.5%) exhibited a normal or nearly normal outcome. According to the objective IKDC score, 4 patients (28.5%) were categorized as moderate. CONCLUSION The above mentioned reconstruction technique can achieve a stable knee function in patients with isolated PCL insufficiency. The isolated single-bundle PCL reconstruction offers a medium-term improvement regarding the activity level and stability of the knee joint.

Vierjahresergebnisse nach isolierter hinterer Kreuzbandrekonstruktion in Einbündeltechnik

BACKGROUND The purpose of this study was to evaluate the clinical and radiological results after isolated reconstruction of the posterior cruciate ligament (PCL) using semitendinosus (ST) and gracilis (GT) tendon grafts with the arthroscopic single-bundle technique. MATERIALS AND METHODS Following PCL reconstruction using the single-bundle technique performed between 2002 and 2005, 14 patients (2 women, 12 men) prospectively underwent a standardized follow-up examination after an average postoperative time of 4 years. All patients included in this study had isolated insufficiency of the PCL and symptomatic instability. The exclusion criteria were the presence of a complex knee joint instability and the implementation of additional stabilizing measures or another method of PCL reconstructive surgery. The mean follow-up time was 47.2 ± 8.7 months. Preoperative and postoperative stress radiographs were taken using the Telos stress instrument in order to evaluate the posterior translation. Knee joint function and degree of activity were recorded using the Tegner activity score, the subjective IKDC score and the overall IKDC score. RESULTS The posterior tibial translation of 10.1 ± 1.7 mm had an overall average improvement to a postoperative value of 4.6 ± 2.3 mm (p < 0.001). The patients showed a significant improvement in the Tegner activity score from an average 2.7 ± 0.8 points to 5.7 ± 1.3 points (p < 0.001). Evaluation of the subjective IKDC showed a significant improvement from a preoperative score of 41.32 ± 11.23 points to a postoperative score of 65.08 ± 13.51 points (p < 0.001). In total, 10 patients (71.5%) exhibited a normal or nearly normal outcome. According to the objective IKDC score, 4 patients (28.5%) were categorized as moderate. CONCLUSION The above mentioned reconstruction technique can achieve a stable knee function in patients with isolated PCL insufficiency. The isolated single-bundle PCL reconstruction offers a medium-term improvement regarding the activity level and stability of the knee joint.

Primary stability of cementless threaded acetabular cups at first implantation and in the case of revision regarding micromotions as indicators.

Abstract The primary stability of cementless total hip endoprosthesis is of vital importance for proximate, long-term osteointegration. The extent of micromotions between implant and acetabulum is an indicator of primary stability. Based on this hypothesis, different cementless hip joint endoprosthesis were studied with regard to their micromotions. The primary stability of nine different cementless threaded acetabular cups was studied in an experimental setup with blocks of rigid foam. The micromotions between implant and implant bearing were therefore evaluated under cyclic, sinusoidal exposure. The blocks of polymer foam were prepared according to the Paprosky defect classifications. The micromotions increased with the increasing degree of the defect with all acetabuli tested. Occasionally coefficients of over 200 μm were measured. From a defect degree of 3b according to Paprosky, the implants could no longer be appropriately placed. The exterior form of the spherical implants tended to exhibit better coefficients than the conical/parabolic implants.

Vierjahresergebnisse nach isolierter hinterer Kreuzbandrekonstruktion in Einbündeltechnik@@@Outcome 4 years after isolated single-bundle posterior cruciate ligament reconstruction

BACKGROUND The purpose of this study was to evaluate the clinical and radiological results after isolated reconstruction of the posterior cruciate ligament (PCL) using semitendinosus (ST) and gracilis (GT) tendon grafts with the arthroscopic single-bundle technique. MATERIALS AND METHODS Following PCL reconstruction using the single-bundle technique performed between 2002 and 2005, 14 patients (2 women, 12 men) prospectively underwent a standardized follow-up examination after an average postoperative time of 4 years. All patients included in this study had isolated insufficiency of the PCL and symptomatic instability. The exclusion criteria were the presence of a complex knee joint instability and the implementation of additional stabilizing measures or another method of PCL reconstructive surgery. The mean follow-up time was 47.2 ± 8.7 months. Preoperative and postoperative stress radiographs were taken using the Telos stress instrument in order to evaluate the posterior translation. Knee joint function and degree of activity were recorded using the Tegner activity score, the subjective IKDC score and the overall IKDC score. RESULTS The posterior tibial translation of 10.1 ± 1.7 mm had an overall average improvement to a postoperative value of 4.6 ± 2.3 mm (p < 0.001). The patients showed a significant improvement in the Tegner activity score from an average 2.7 ± 0.8 points to 5.7 ± 1.3 points (p < 0.001). Evaluation of the subjective IKDC showed a significant improvement from a preoperative score of 41.32 ± 11.23 points to a postoperative score of 65.08 ± 13.51 points (p < 0.001). In total, 10 patients (71.5%) exhibited a normal or nearly normal outcome. According to the objective IKDC score, 4 patients (28.5%) were categorized as moderate. CONCLUSION The above mentioned reconstruction technique can achieve a stable knee function in patients with isolated PCL insufficiency. The isolated single-bundle PCL reconstruction offers a medium-term improvement regarding the activity level and stability of the knee joint.