Aims

Anchorage of pedicle screw rod instrumentation in the elderly spine with poor bone quality remains challenging. Our study aims to evaluate how the screw bone anchorage is affected by screw design, bone quality, loading conditions, and cementing techniques.

This study presents an historical review of the treatment of talipes equino-varus during the last centuries. The aim of the study was to show how knowledge about the pathogenesis and the progress of new techniques in orthopaedic surgery (plaster of Paris, anaesthesiology, asepsis, antisepsis) have influenced the treatment of this disease during the centuries.

This investigation is based on a study of the library of the German Orthopaedic and Science Museum that has more than 3000 historical books and theses from the middle of the 19th century to the present time.

In the 18th and 19th century there were different theories about the pathogenesis of clubfoot. For example, Paré was of the opinion that secondary forces were responsible for the deformity. Camper and Wolff were convinced that intrauterine pressure on the extremities was the reason for pes equinovarus. Little, Stromeyer and Delpech believed that shortening of the muscles was the origin. The pathogenesis of the clubfoot is still obscure.

The concept of therapy with redression and retention during the first month has not changed since Hippocrates. However, the techniques of redression and retention have changed during the decades. Machines and rural instruments were used for redression until the end of the 19th century (Lorenz, Thomas). Retention was improved by the development of new splints (Arceo, Venel, Scarpa). The introduction of plaster of Paris (Mathysen) in the treatment of the clubfoot led to a further improvement of retention in early treatment.

A new era began with asepsis and anaesthesia. These techniques allowed progress in the operative therapy of the tendons. The open and subcutaneous tenotomy was developed by Delpech, Dieffenbach, and Stromeyer.

In spite of the operative possibilities, we conclude that conservative treatment still has a major role in the concept of treatment for equinovarus.

There are nearly no studies which describe the influence of the ileotibial tract (IT) on force distribution in the knee joint in a qunatitative manner. Therfore the aim of this work was to develop a complex 3-D computer model of the lower extremity, consisting of bones, joints and muscle models describing their dynamic behaviour including a special IT model. The computer model provided the possibility to simlate training of the muscular system.

Thus the computer model provided among others the possibility to simulate training of the lateral thigh muscles and vastus lateralis with the aim to tension the IT, with the option to calculate force distribution in the knee and compare it with the effect of a tibial osteotomy.

Patients with varus knees were examined. Kinematic data during walking together with forceplate and EMG data wer collected, before and after tibial osteotomy. The anatomy of the patients was recorded by MRI.

Gait and MRI data were the input in the new developed three dimensional computer model. The scaled geometrical data by Delp (1990) and the MRI data were combined to represent the individuals anatomy.

The model of the lower extremity included 43 muscles with origins/insertions and force-length properties described by Delp (1990). The muscle model was improved by including force-velocity properties and a new muscle tendon parameter (tendon stiffness). A functional scaling method was developed to fit the muscle models to individual anatomy. The IT complex was modelled as a coupled unit of IT, tensor fascia latae and gluteus maximus. Muscle and joint forces were determined using an optimization approach minimizing the cube of the sum of muscle forces divided by their upper bounds.

Simulated muscle training of the lateral thigh muscles and vastus lateralis led to an increased tensioning of the IT. As a result the lateral knee force raised considerably similar to the increase after osteotomy. However the decrease in the medial compartment was small and not comparable with the effect of a valgus osteotomy. Tensioning of the IT leads apparently to an overall larger resulting knee force stabilizing the joint, but is not able to reduce medial knee force to an extent that can avoid osteotomy.