Evaluation of an ambulatory system for gait analysis in hip osteoarthritis and after total hip replacement.

Spatial and temporal parameters of gait have clinical relevance in the assessment of motor pathologies, particularly in orthopaedics. A new gait analysis system is proposed which consists of (a) an ambulatory device (Physilog) including a set of miniature gyroscopes and a portable datalogger, and (b) an algorithm for gait analysis. The aim of this study was the validation of this system, for accuracy and clinical applicability. Eleven patients with coxarthrosis, eight patients with total hip arthroplasty and nine control subjects were studied using this portable system and also a reference motion analyzer and force plate. The small differences in the stance period (19 +/- ms), stride length and velocity (0.4 +/- 9.6 cm and 2.5 +/- 8.3 cm/s, respectively), as well as thigh and shank rotations (2.4 +/- 4.3 degrees and 0.3 +/- 3.3 degrees, respectively), confirmed good agreement of the proposed system with the reference system. In addition, nearly the same accuracy was obtained for all three groups. Gait analysis based on Physilog was also in agreement with their Harris Hip Scores (HHS): the subjects with lower scores had a greater limp, a slower walking speed and a shorter stride. This ambulatory gait analysis system provides an easy, reproducible and objective method of quantifying changes in gait after joint replacement surgery for coxarthrosis.

Regional migratory osteoporosis: a pathogenetic hypothesis based on three cases and a review of the literature.

Regional migratory osteoporosis (RMO) is a migrating arthralgia of the weight-bearing joints of the lower limb which mainly affects middle-aged males. Its aetiology is unknown. The association of RMO with generalised osteoporosis has recently been reported. A concurrent systemic osteoporosis was also reported in some cases of transient osteoporosis of the hip (TOH), a disorder closely related to RMO. In its turn, TOH is considered a reversible stage of avascular necrosis of the hip (AVN), and the aetiopathogenesis of both of them remains strongly debated. We report three cases of RMO associated with generalised severe idiopathic osteoporosis. Three men, in the fourth and fifth decades of life, complained of at least four episodes of arthralgia in the lower limbs, with a migratory pattern, radiographic focal osteoporosis and final clinical resolution. The most striking common feature of these patients was the presence of a severe systemic osteoporosis with a prevailing trabecular involvement. We suggest that a prolonged or exaggerated activation of regional acceleratory phenomena (RAP) is the cause of transient osteoporosis. Bone tissue microdamage due to osteoporosis may be the most frequent noxious stimulus that turns RAP on, and, bone tissue microfracture is the most prevalent consequence. When this pathogenetic pathway is activated, the progression from focal osteoporosis and bone marrow oedema to avascular necrosis is associated with the amount of structural damage.

Osteointegration of 96 cementless hip prostheses with hydroxyapatite coating; 5 years follow-up.

Since 1988 at total of 96 hip prostheses with hydroxyapatite coating (HA) for both the acetabular and the femoral components have been used. HA is considered to be a biocompatible material, with a considerable capacity for osteointegration with evident osteophilia. Close integration between this material and bone tissue is determined by the formation of chemical bonds, and this leads to the development of osteoid tissue and newly-formed bone trabeculae. Based on the radiographic evaluation criteria described by Engh in 1990 and with reference to the concepts of stability and fixation of the prosthesis to the bone, it was observed that radiographic signs of osteointegration are manifested as early as 1 year after surgery, and, in particular, that the formation of bone bridges (spot welds) in the interface increases in time.

The OCTOPUS system for acetabular reconstruction.

In revision surgery of the hip, reconstruction of the acetabulum often constitutes the most complex procedure. There is frequently a considerable loss of bone substance, and correct repositioning of the rotation center of the femoral head is required. Based on surgical experience supported by clinical results the authors affirm that both of these objectives may be achieved when the OCTOPUS socket system is used. This implant, with anchoring to the iliac bone and the use of bone transplants, allows for the reconstruction of the original anatomy of the cotyle.

Methods for the study of bone regeneration in lengthening of the limbs.

In addition to standard radiography the authors used two other methods, echography and dichromatic bone densitometry, in the evaluation of bone regeneration in patients submitted to lengthening of the lower limbs. They report their findings and conclusions on the value of these methods.

Rapidly destructive bilateral hip disease: a case report and review of the literature.

We describe the case of an elderly woman with rapid destruction of the right hip followed by the same involvement of her left hip 10 months later. The clinical history, the physical examination and radiographic images suggested the diagnosis of rapidly destructive hip disease. This disease is a distinct entity, unilateral in 80%-90% of cases, which requires extensive investigation and special efforts for its identification. Essential elements for the differential diagnosis are discussed.

A study of the interface between human bone and hydroxylapatite. A morphological and morphometric investigation.

The results are reported of clinical experiments conducted on four volunteers suffering from fractures of the tibia. Dense hydroxylapatite screws were used in association with conventional internal fixation. On removal of the plates and screws at periods varying from 4 to 12 months after implantation, the hydroxylapatite screws were removed together with a core of surrounding bone in order to study the bone hydroxylapatite relationship. Conventional and scanning electron microscopy was used, as well as dichromatic bone mineralometric tests. The results confirmed the excellent biocompatibility of hydroxylapatite with human bone. Arising out of this, the possible future clinical application of dense hydroxylapatite is discussed.

Thoracic outlet syndrome. Proposed protocol for diagnosis and treatment.

The clinical and aetiopathogenetic features of thoracic outlet syndrome are reviewed, and 51 cases treated by us over the last 10 years are analysed. A long-term follow-up (from 6 months to 10 years) was obtained in 24 patients, 19 of whom had been submitted to surgery. The long-term results were excellent or good in 15 patients and unchanged or worse in the remaining 9 cases. A careful retrospective survey of the history and clinical findings was carried out, including in particular the relevance of radiography of the cervical spine, EMG and Doppler tests. The type of surgery employed, which included both the supraclavicular and transaxillary approaches, was also taken into account. Based on this retrospective analysis the authors propose a protocol for diagnosis and treatment in a syndrome which is not always easy to interpret and which often crosses boundary lines in several specialist fields of medicine and surgery.

Periprosthetic bone density around fully hydroxyapatite coated femoral stem.

In this study, periprosthetic bone mineral density was measured at scheduled time intervals after surgery by dual energy x-ray absorptiometry in 21 patients to assess the history of bone density redistribution after femoral stem insertion. Measurements of changes in bone density with time were obtained for the regions of the greater trochanter, the lateral cortex, the tip, the medial cortex, and the calcar. In all regions, bone density decreased during the first 3 months after surgery; this was followed by a prolonged period of 18 to 30 months of bone gain, a subsequent period of steady state, and the final resumption of bone aging processes after the third postoperative year. The greatest loss was observed in the calcar region after 6 months (greater than 50%). The characteristic pattern of time related bone density changes obtained in this study may make it possible to compare other pathologic, design, or stiffness related patterns. This could have clinical relevance in the early diagnosis of pathologic processes and as a means of evaluating prosthetic designs.

Bone assessment after total knee arthroplasty by dual-energy X-ray absorptiometry: analysis protocol and reproducibility.

Bone quality is important for the success of joint prostheses implantation, and the assessment of bone density after total knee arthroplasty by means of dual-energy X-ray absorptiometry may be useful for monitoring implant stability. The aim of this study is to suggest a validated analysis protocol for the assessment of bone status after total knee arthroplasty. A dedicated densitometric analysis protocol of five regions of interest was designed, and 10 subjects who had received an uncemented knee prosthesis (8 females and 2 males, aged 55-74 years) underwent three consecutive scans in posteroanterior and lateral projections, with repositioning after each scan to test the suitability and reproducibility of the protocol. The reproducibility of the measurement of bone mineral content and density in the femoral and tibial regions ranged, respectively, from 2.1% to 4.1%, from 0.9% to 2.6% for the posteroanterior scans, and from 2.7% to 5.6% and from 2.3% to 4.7% for the lateral scans, depending on the considered region. Our results confirm that the suggested protocol allows precise assessment of bone mineral content and density, and that dual-energy X-ray absorptiometry is reliable for the evaluation of bone mass around prosthetic implants.

Experimental osteosarcoma in the mouse, induced by Moloney's murine sarcoma virus.

The writers report an experimental trial on the mouse, consisting in the induction of osteosarcoma by inoculation of Moloney's murine sarcoma virus (MSV-M) into the proximal metaphysis of the tibia. This experiment was conducted on 90 BALB/c female mice aged twenty-one days and of mean weight 12.8 g. One group of animals was also given immunodepressive drugs. The tumour developed in 100 per cent of cases, producing metastases in some of the animals and resulting in death in three cases. The radiographic changes were initially osteolytic followed later by new bone formation. The histological examinations confirmed that the tumour was of an osteosarcomatous nature. Cells characteristic of rhabdomyosarcoma were observed in the soft tissues surrounding the bone. The skeletal metastases had the characteristics of osteosarcoma, while those in the lymph glands and lungs had those of an undifferentiated sarcoma. The writers also took into consideration a series of previous trial performed at the Institute of Clinical Orthopaedics of the University of Milan, involving a total of 740 mice, in arriving at their final conclusion that MSV-M induces, in the mouse, an osteosarcoma similar to spontaneous osteosarcoma in man, capable of producing osteoid tissue, of giving rise to metastases, and of causing the death of the animal.

A study of the development of fracture callus in the presence of an experimentally induced osteosarcoma.

The results of two experiments are reported in which the formation of an osteosarcoma was induced in mice by the intraosseous injection of Moloney's virus. In the first group of fifty mice, a complete diaphyseal fracture was carried out nine days later at the site of the tumour. In the second group of 200 mice, a partial fracture was produced at the time of injection so that immobilisation was assured. The effects of cyclophosphamide and calcitonin administration were also studied in this group. The course of the repair processes of the bone was studied in both groups, and showed that, even in the presence of an osteosarcoma, these begin and can reach completion, though obstructed and delayed by the tumour.