Introduction. Fully implantable distraction nails are frequently used for lengthening of the lower leg. What are the indications for
Introduction: Achondroplasia is a form of rhizomelic dwarfism. Even if patients can compensate for their short arms through the mobility in their spine during the childhood, the flexibility in their spine becomes less with aging. Because of that, as they get older they experience problems in maintaining personal hygiene especially in reaching the back. In addition putting on socks and tying their own shoes might become difficult. Methods: Inclusion criteria included any patient with a history of achondroplasia who had undergone humeral lengthening in the proximal part of the humerus (just distal to deltoid muscle insertion). Patients who had distal humeral (supracondylar) osteotomy and/or who received other than monolateral external fixator were excluded from the study. 50 humeri of 25 patients with achondroplasia were lengthened using Orthofix mono-lateral external fixator utilizing proximal humeral osteotomy. Sixteen patients were female and nine were male. Mean age was 15.4 months (range, 9.6 – 21.8). Lengthening was started at 7th day. Patients were lengthened at 1/4 turn four times a day reaching 1 mm/day. Physical therapy was performed 3 times a week. Goal of lengthening was around 10 cm or whatever length the patient could tolerate. Patients wore Sarmiento type fracture brace 4–6 weeks after the fixator was removed. Results: Mean follow-up time from surgery was 51.5 months (range, 6 – 143 months). Mean follow-up time from removal of external fixator was 44.7 months (range, 0 – 135 months). Average external fixation time was 7.3 months. In 20 humeri it was noted that the average duration of lengthening was 4.2 months (range, 3 – 5.8 months). A mean lengthening of 9.3 cm was obtained (range, 4.3 – 12.8 cm). At latest follow-up range of motion was not compromised due to lengthening. All patients had similar ROM before and after the surgery. Complications included radial nerve palsy in 8, pin tract infection in 7, fracture through regenerate in 3, premature consolidation in 1, nonunion in 1, delayed healing in 1. Radial nerve palsy recovered without intervention in one case. In others it recovered uneventfully after successful decompression. No complications at all occurred in 30 cases. Discussion: Fifty humeri of 25 patients with achondroplasia received successful
Purpose of the study: Reversed prostheses provide improved active anterior elevation in shoulders free of cuff tears by lengthening the deltoid and increasing is lever arm. The purpose of this work was to search for a correlation between arm lengthening and postoperative active anterior elevation. Material and methods: One hundred eighty-three reversed prostheses were reviewed with minimum one year follow-up for a complete clinical and radiographic work-up. Using a previously validated protocol, arm lengthening was assessed either in comparison with the contralateral side or with preoperative measurements. A statistical analysis was performed to search for a correlation between lengthening of the humerus and the arm with active anterior elevation. Results: Considering the entire series, mean lengthening of the humerus was 0.2±1.4 cm (range −4.7 to +5.4). Postoperative active anterior elevation was 141±27 (range 30–180). There was no correlation between
Purpose of the study: The aim of this biomechanical study was to assess the performance of the deltoid muscle in the absence of a rotator cuff using different models for shoulder prosthesis. Material and methods: A computer model reproducing the three dimensions of the glenohumeral joint was use to analyze the force of the deltoid muscle during abduction movements in shoulders devoid of a rotator cuff. The three heads of the deltoid were analyzed in order to determine the most effective level of muscle tension. The lever arm of the deltoid was measured from 0–90° abduction. Using this 3D model, we simulated implantation of six different models of reversed prostheses in order to assess the biomechanical situation which would be the most favorable for the deltoid. Performance of the normal deltoid was compared with the performance of the deltoid after implantation of an anatomic prosthesis and after implantation of an reversed prosthesis. Several variables were studied: medial offset of the center of rotation, lateral offset of the
Since the time of Charles Darwin, it is known that three principles of regeneration explain the similarity of neo-formed tissues, the dependence of regeneration rhythm on age and the position of the animal in the evolutionary chain. The latter principle is know as the Weisman-Pschibram principle. Regeneration depends on several factors: level of tissue specialisation and differentiation, tissue resistance to hypoxia, and other manifestations of generally recognised biological regulation. According to a fourth principle, the regenerative potential of different parts of the body depend on a cranio-caudal gradient which rhythms their postnatal growth and development. Distinction of this principle is of importance because of its practical applications. Experience with increasing the height of persons with achrondroplasty by lengthening different limb segments reveals that the femur has less regeneration potential despite its long length. Leg lengthening is preferred; saving muscle function, there is a 20% potential for lengthening. Male subjects are generally considered to be short in height when there is a 10% growth retardation of the longitudinal dimension of the body. In female subjects, generative function is considered deficient if the length of the trunk is less than 73 cm. Using these criteria, experience has shown that leg malformations are not observed in subjects with a 10% growth retardation of the limb. The rate of growth retardation has to reach 40% before growth ceases. The relative moment of posterior leg muscle force increases with increasing leg length (F = 0.063 x L – 0.7; r=0.965, n=123). With a 10% growth deficit, the leg lengthening operation limits the amplitude of ankle movement 15% on average. With the same 10% growth deficit, lengthening the femur with the same technique decreases the amplitude of knee movement 22%. It has been noted that a 40% decrease in leg muscle force after leg lengthening does not affect locomotor function. The same decrease in thigh muscles after femur lengthening alters function. Like the first three principles, the fourth has its exceptions. It is important however to distinguish the influence of biological factors from other, for example technical, factors. Thus orthopaedic surgeons prefer the
