Research Projects 1998
Lund
University Hospital, Sweden
The major part of the health care consumption in orthopedics is caused by joint diseases (osteoarthrosis and rheumatoid arthritis), fractures, back problems, injuries, and tumors. This pattern is reflected in the research activities within the Department of Orthopedics at Lund University Hospital.
Research on joint disease and its consequences spans from basic biochemical investigations to applied projects which monitor nationwide the outcome of arthroplasty and includes the following aims: Develop methods for diagnosis and monitoring of early-stage osteoarthrosis through patient-administered outcome scores, radiography, arthroscopy, MRI and analysis of joint fluid and serum markers of cartilage turnover as well as investigate the disease mechanisms; Improve diagnostic and reconstructive techniques after knee ligament injury; Improve and develop techniques for joint replacement in the rheumatoid joint; Study the process and causes of joint implant loosening in hip and knee; In a nationwide, prospective multicenter study investigate patterns of knee joint implant failure related to time, implant type, age, etc. Different methods of treatment for gangrene of the lower extremity are evaluated with regard to quality of life, cost, etc.
Fracture research includes: A study of the process of bone induction and its stimulation by human recombinant growth factors; In a nationwide, prospective multicenter study investigate the epidemiology and treatment of hip fractures and its effects on health care economics; Improve methods for osteosynthesis of hip fractures and study effects on femoral head vitality, fracture healing, and rehabilitation.
Research on lumbar back pain and sciatica aims to optimize patient information, operation methods, postoperative treatment, and utilization of hospital resources. Research on soft tissue sarcomas evaluates diagnostic procedures, surgical techniques, and prognostic classification of tumors. Research in hand surgery includes evaluation and treatment of ligament injuries in distal radius fractures in young patients. Research in pediatric orthopedics targets gait and function analysis in children with cerebral palsy and pathophysiology in Perthes' disease.
Laboratory facilities exist within the Department for the following areas: biomaterial, biomechanics, cartilage metabolism, animal experiments, bone transplantation and radiostereometry. In addition to the some 30 M.D. clinical investigators, a total of 6 laboratory technicians, 5 engineers/engineering students and 4 secretaries are engaged in the research work. Currently, a total 28 graduate students are working on their Ph.D. thesis within the Department.
These research projects thus involve the whole staff at the Department of Orthopedics at Lund University Hospital. In the interest of simplicity, only the responsible primary investigator of each project is listed in the project summary. For further details on any of these projects, as well as a complete listing of participants in each project, please contact the primary investigator. A list of publications printed in 1997 is enclosed. This annual report has been edited by Stefan Lohmander. For further information you may also use our homepage www.ort.lu.se
The two graphs below summarize some aspects of the academic activities of the Department during the last few years.
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The research is financially supported by:
- European Community
- Swedish Cancer Society
- Swedish Medical Research Council
- Foundation for Strategic Research
- Alfred ?terlund Foundation
- Sports Research Council
- Federation of Swedish County Councils
- Greta och Johan Kock Foundations
- King Gustaf V 80-year Birthday Foundation
- Lund Healthcare District
- Malm?us County Council
- Faculty of Medicine, Lund University
- National Board of Health and Welfare, Sweden
- SALUS
- Stiftelsen f? bist?d ? vanf?a i Sk?e
- Swedish Society of Medicine
- Thelma Zo?a Foundation
- Trygg-Hansa Research Foundation
- Astra
- Howmedica
- Lilly
- Merck
- Norian
- Pharmacia-Upjohn
- Scandimed
- Stryker
Projects
- Osteoarthrosis from chondrocyte to patient a continuum
- Injuries and arthrosis of the knee joint
- Reconstructive surgery in rheumatoid arthritis
- Optimized biomaterial for tissue reconstruction
- Endoprosthetic fixation
- Amputations: prevention, healing and life quality
Treatment of diabetic foot ulcers and neuroarthropathy
Computerized analysis of walking ability with BK-prosthesis
F-scan analysis of dynamic pressure in the foot sole - Modulation of bone formation
- Fractures, osteoporosis, and hip fractures in the elderly
- Lumbar pain and sciatica - diagnostics, RSA, treatment and long-term outcome
- Soft tissue sarcomatreatment and prognosis
- Ligament injuries in distal radius fractures in young patients
- Prevention of disabling joint contractures and hip dislocation in children with cerebral palsy by systematic follow-up and early initiated measures
- Pathophysiology, blood supply, synovitis and cartilage
Reaction of the femoral head and growth in Legg-Calv?Perthes? disease - Migration, loosening, and wear following total hip joint arthroplasty
- Biomechanics unit
Osteoarthrosis from chondrocyte to patient a continuum
Osteoarthrosis (OA) is a major cause of disability and early retirement. Current methods for diagnosis and assessment of progression are based on clinical and radiographic signs. As a consequence, the disease is diagnosed only in its final stages and progression is difficult to assess. We monitor the progress of post-traumatic knee OA after injury to the cruciate ligament and meniscus and correlate results of patient-administered outcome scores, radiographs, arthroscopy, magnetic resonance imaging (MRI) and biochemical markers of cartilage metabolism. Prospective and retrospective studies to monitor the development of OA, and the effect of intervention, after injury to menisci or ligaments of the knee are ongoing. The prevalence of hip OA in Iceland and Sweden is compared. Clinical trials of the effect of intraarticular injections of hyaluronan in knee OA have been performed, other clinical trials of non-surgical treatment of OA are planned.
Molecular fragments of the joint cartilage matrix are released to the synovial fluid after knee injury and during the development of post-traumatic OA. Concentrations of fragments of proteoglycan, cartilage oligomeric matrix protein, collagen, and other matrix molecules released into joint fluid remain elevated for many years after injury. High concentrations of the metalloproteinases (MMP) as well as tissue inhibitor of metalloproteinases are found in joint fluid after injury and in OA. Elevated levels of MMPs identify pathological joints with high sensitivity and specificity. Although we find very high concentrations of MMPs in joint fluid after injury, the role of these proteinases in cartilage destruction in OA remains unclear.
We find a consistent N-terminal in proteoglycan fragments in joint fluid in OA and in rheumatoid arthritis which corresponds to a specific cleavage of the core protein in the interglobular domain. This suggests a common final degradation step of proteoglycan in these joint diseases. The identity of the proteinase remains elusive but would be of great value in efforts to identify one of the mechanisms for proteoglycan breakdown in OA. In continued work we immunolocalize specific cleaved matrix molecule fragments in human OA and RA cartilage and joint fluid.
A patient-administered knee and osteoarthritis outcomes score has been developed and validated for patients with lesions of the anterior cruciate ligament and/or meniscus and post-traumatic OA. The score assesses pain, other disease-specific symptoms, function of daily living, function of sports and recreation, and quality of life.
The prevalence of hip OA in Iceland is several-fold higher than in Malm?City, Sweden. We are searching for genetic defects in the Icelandic population that may be one of the reasons for the high prevalence of hip OA.
The long-term goals of this project are (1) to characterize the natural history of post-traumatic OA and the effects of surgical and pharmacological intervention, (2) to identify risk factors and disease mechanisms in OA, and (3) to identify body fluid markers of OA which could be used in early diagnosis and monitoring of the disease. Such knowledge would facilitate efforts to develop drugs which could retard the destruction of joint cartilage in OA. The work is done in collaboration with Laboratories and Departments in Sweden, Iceland, Norway, Finland, England, Germany, USA, Canada, and Japan.
Injuries and arthrosis of the knee joint
Knee injuries may affect collateral and cruciate ligaments as well as menisci and joint cartilage. A typical injury is the consequence of an indirect twisting force in mainly young and middle-aged people. An injury of the anterior cruciate ligament which is left untreated may result in symptoms of instability and pain and problems to master many sports activities and strenuous work. Our present research relates to the sensory function of the limb after an anterior cruciate ligament injury and the value of different training programs. The stability after anterior cruciate ligament reconstruction is studied by radiostereometry. The value of suturing the meniscus injury is also evaluated.
In the long prospective there is an increased risk of developing arthrosis (OA) of the knee joint. We are studying the sensory function of the limb in arthrosis of the knee and also after different surgical procedures like osteotomy and arthroplasty. Treatment by wedge osteotomy has been studied in Lund since many years while osteotomy by callus distraction (CD) has been used only the last few years. A randomized study comparing traditional wedge osteotomy to CD osteotomy has been completed. Further studies on CD in more advanced OA in younger patients as well as this operation in lateral OA are also studied. Complications in callusdistraction (in a national project), gate analysis, bony healing in CD as well as mechanical lode testing are evaluated. The risk of pin inflammation - infection is studied in a randomized way comparing open and closed care of the pin incision.
Operation of OA by an endoprosthetis joint replacement is one of the most successful treatment programs in orthopedics. None optimal placement of the artificial joint and by time the risk of loosening is one common reason for failure. Our project is the study of loosening in relation to the perioperative mechanical trauma to the bone tissue. The surface is studied both regarding evenness and direction of the cut and also the possibility of bone tissue regeneration. The soft tissue is studied with the aim to minimize surgical incision of the skin and underlying soft tissue in order to decrease postoperative pain and to facilitate rehabilitation. The surgical technique is studied by traditional cutting compared to computer and robotic cutting. This is a high technology procedure divided into three parts: planning, registration and the cutting of the bone. This part of the project is performed in corporation with the Rizzoli Clinic, Bologna, Italy. Another projects is unicompartmental endoprosthesis and minimal invasive surgery. Also long time follow-up of different cemented and noncemented prosthesis by clinical and radiographic (including radiostereometry) methods are performed.
Reconstructive surgery in rheumatoid arthritis
Instability of the cervical spine can be managed in several ways. Posterior fusion and/or decompression may include one or several levels and different types of internal fixation may be used. The clinical and radiographic results of different surgical methods are under investigation. Dynamic studies of the cervical spinal canal with magnetic resonance imaging apparatus will be started, as well as epidemiological studies on the incidence, natural course and surgical treatment results of arthritic involvement of the thoracic and lumbar spine.
The clinical and radiographic results of modular endoprostheses for the hip and knee are continuously followed. Our design of a knee joint prosthesis has now been in clinical use since 13 years, and the relation between the radiographic positioning of the prosthesis and the clinical outcome will be defined.
A multicenter study on bipolar shoulder prostheses will start during the year.
We have recently reported the results of two different methods for arthrodesis of the rheumatoid ankle. Endoprosthetic replacement of the ankle joint will start in 1998 and a number of patients will be followed with roentgenstereophotogrammetric analysis. A prospective study of different surgical methods for forefoot surgery is also in preparation.
The JCA surgery register is under continuous development. An individual patient information system is under development and re-examination of about 150 children operated with different large joint prostheses will start in the near future.
Optimized biomaterial for tissue reconstruction
The overall aim of the project is to develop improved biomaterials for increased implant survival, to obtain a better understanding of the biomaterial tissue interface, and to exchange knowledge between different disciplines and institutions. The project consists of a basic/preclinical part and a clinical part. The basic/preclinical part will (1) focus on molecular and cellular binding patterns and mechanics of existing and new chemically and structurally tailored surfaces. (2) The biological function of hydroxyapatites as replacement, implant coating and as a filler in PMMA will be studied. (3) Research on material degradation will focus on polymers in bearing surfaces and around implants to study chemical, physical, mechanical, biological and tribological properties. From a material science perspective a prime objective is to build a competence in artificial joint tribology and to develop reliable in vitro screening methods for assessing the wear of material combinations. (4) New predictive preclinical evaluation techniques for a better joint implant fixation and survival will be developed. The clinical parts will (5) be using RSA and several other imaging techniques measuring implant motion and degradation. (6) Multicenter survival studies including outcome measurements will be used for the clinical biofunction evaluation. This part includes a retrieval and patient donor program.
Ad (1). Materials will be modified to achieve different tissue organization by functionalization of the surface by attachment of biologically active ligands primarily chosen from normally occurring matrix components. Techniques to characterize and quantitate tissue organization will be refined. In the future the susceptibility of the modified surfaces to bacterial infections will be investigated.
Ad (2). Experimental models which are closer to clinical applications will be designed. The idea is to use ceramics or bone grafted knee prosthesis in rabbits, in which we will try to stimulate incorporation and remodeling of the grafts by e.g. growth factors. A micromotion chamber model will be used for further characterization.
Ad (3). Reciprocating pin-on-plate wear simulations will be carried out on different material combinations. Novel candidate materials will be investigated, as well as current materials (e.g. UHMWPE) that have been modified (plasma technology, microfabrication, and polymer processing). The chemical and structural properties of the materials will be characterized prior to and after testing by using spectroscopic and microscopic techniques. Analysis of components from retrieved clinical and donor implants constitutes a reference to the in vitro studies.
Ad (4). Different tissue differentiation processes in the prosthetic bone interface are studied in a biphasic FEA program on endoprosthetic replacement with validation of this material using experimental and clinical tools including RSA.
Ad (5). A retrieval program has been implemented for patients who are entered into a RSA study group. Thus, approximately 200 patients have agreed to donate their knee prostheses for post-mortal biomechanical and histological examination. The preparation and histology will be carried out at GU and the biomechanical studies in a new laboratory under construction in Lund.
Ad (6). A national implant and biofunction study is run by the Department of Orthopedics in Lund, including all clinics in Sweden. In a later stage of this program alternative material will be followed by multicenter survival analysis in the register.
Endoprosthetic fixation
Endoprosthetic components loosen at a rate of about 5_10% after 10 years, a process in itself or in close liaison with the problem of wear of endoprosthetic components. The project aims at understanding and alleviating this problem.
RSA has shown that prostheses usually move in relation to the bone they are fixed to. It has recently been established that the pattern of this motion has a clinical connotation and prostheses at risk can be identified by RSA after about two years both in the hip and in the knee. Using the migratory pattern as end-point and primary effect variable, changes in design, operative technique, fixation concepts etc. can be studied prospectively in controlled studies. Thus a number of patient cohorts are presently being followed and factors like bone preparatory technique, cement / non-cement fixation, pressurizing cementing techniques, hydroxyapatite coating, meniscal bearing designs and periapatite coatings are being assessed. About 800 hip- and knee arthroplasties are presently being followed by RSA.
Patients having had their knees replaced are asked to donate them post-mortem in a retrieval program. Retrieved prostheses are processed for histologic examination and the cellular process corresponding to migration and inducible displacement as measured by RSA is investigated. Presently approximately 200 patients have donated their knees and 25 cases have been retrieved. Further, retrieved specimens are tested in an Instron materials testing machine for experimental correlates to RSA findings from stress examinations.
Forces and motions across the bone-prosthetic interface can be modeled using Finite Element Models (FEM). Using iterative algorithms, tissue differentiation can be modeled and findings from retrieval specimens and animal models are being used for validation purposes.
The development of endoprostheses over the last decades has concentrated on functionality as assessed by gait analysis. The VICON system of OTC has been put to use in this respect and significant relationships with RSA findings have been established. Conventional clinical instruments for follow-up have not correlated with the proven predictive ability of RSA. Outcome instruments in the form of questionnaires have, however, been found to be both valid, sensitive and reproducible instruments that can be administered though mail-outs. Within the frame-work of the Swedish Knee Arthroplasty Project (see Optimized biomaterials for tissue reconstruction), outcome instruments will be applied to knee arthroplasty patients in a large-scale mail-out study in order to arrive at the finer nuances of well-being after joint replacement. It is anticipated that differences between individual prosthetic designs and modes of fixation can be identified.
Amputations: prevention, healing and life quality
Treatment of diabetic foot ulcers and neuroarthropathy
Computerized analysis of walking ability with BK-prosthesis
F-scan analysis of dynamic pressure in the foot sole
Amputation frequency has increased during the last 50 years. More than 50% of all amputees suffer from diabetes. A research program at our department has shown that the number of amputations has decreased with two thirds during the last 10 years and that the amputation level is more distal than before. Twenty-five percent of the amputations in diabetics now are performed through the foot.
A detailed analysis and follow-up of more than 1000 diabetic patients with foot ulcer is performed, showing that two thirds of all amputations in diabetics are initiated by a small foot ulcer second to narrow shoes or shear stresses on the foot because of overloading. Very thin insoles with electronic sensors are placed in the shoes of the patient and dynamic pressures are analyzed with a computer. Special insoles and shoes are then made and the procedure is repeated to register if the intended unloading effect is achieved, thus leading to prevention of ulcers and eventual amputation. Special interest is focused on patients with diabetic polyneuropathy.
Factors related to healing of diabetic foot ulcers and specific treatment modalities of diabetic foot ulcers and neuroarthropathy are evaluated. Several prospective, randomized placebo-controlled studies are in progress: (1) supplementary nutrition to diabetics with Wagner grade 1-2 lesions, (2) granulocyte-colony stimulating factors to diabetics with foot infections and (3) bisphosphonates for diabetic Charcot neuroarthropathy. Several patients with major amputation (below knee or more proximal) get problems with the fitting of the prosthesis socket. A new concept, the Tec Interface socket made from polyurethane, is now evaluated with respect to socket fitting and improved walking ability with the Vicon gait analysis system which gives a 3-dimensional view of human gait. Initial results are promising with a considerable improvement of patient's satisfaction and walking ability compared to conventional sockets.
Modulation of bone formation
Aim: The aim is to reduce local bone loss, to replace bone and to stimulate local bone formation.
Background: Bone loss is an essential problem in orthopedic conditions such as tumors, infections, fractures, rheumatoid diseases and the loosening of joint prostheses. If joint prostheses loosen, the surrounding and supporting bone undergoes resorption and disappears. The reason for this bone loss is debated. Most commonly the reaction to wear particles from the articulating surfaces are thought to be the initiating factor. Missing bone can be replaced by bank bone, i.e. deep frozen bone from other patients. Bank bone is associated with several problems including the risk of transferring HIV virus. Attempts are made to replace bank bone with porous hydroxyapatite and other materials. Bank bone and other bone replacement materials incorporate slowly and incompletely. Incorporation of bank bone sometimes also leads to break down and loss of its mechanical function. Similar break down and collapse is seen for example in the femoral head after circular damage. Different signal proteins can be utilized to stimulate bone formation. "Bone morphogenetic proteins" (BMP's) can initiate bone formation extraskeletally in adult animals. Bone induction by BMP's offer new therapeutic potentials for several orthopedic problems. Other growth factors can also increase bone formation after local application and this can be used to increase incorporation of bone replacement materials.
Animal experiments: We have developed a dozen different experimental implants that are used in rodent experiments: Using titanium bone chambers, the reaction of regenerating bone is studied after local application of various growth factors, mechanical forces, fluid pressure, wear particles and also various kinds of systemic treatment. We also use titanium plates, that are in contact with the bone surface. The bone surface can then be subjected to a similar treatment as the regenerating bone in the chambers. Different variants of this plate model is used to study aspects on prosthetic loosening. We also use a knee joint endoprosthesis in rabbits.
Clinical series: We evaluate porous hydroxyapatite for bone replacement in tibial condyle fractures. In a series of patients receiving knee join replacements, we try to prevent prosthetic loosening by medication with a biphosphonate. We try to enhance healing of posterolateral spinal fusions using BMP (all these series are randomized and use roentgenstereometry as primary effect variable). We also evaluate an injectable hydroxyapatite cement that hardens after the injection. This is done in randomized series of distal radius fractures, partly using roentgenstereometry. In retro- and prospective studies, distal radial fractures in younger adults are studied in an attempt to find prognostic tools with radiography and arthroscopy to define fracture subgroups that require surgical treatment.
Current results: Bone resorption similar to prosthetic loosening can be induced by local fluid pressure. This is a new concept in the discussion about prosthetic loosening. Morselization and impaction of bank bone impairs bone incorporation (contrary to common belief), but mechanical load increases ingrowth and remodeling of the graft. Bone callus can be induced to form hyaline cartilage by mechanical signals only. Clodronate, but not alendronate, can reduce bone loss in a model of prosthetic loosening. Bone and titanium can form a tensile resistant bond by chemosorption. BMP's can decrease or stimulate bone formation depending on mechanical influence or trauma. A good clinical effect of BMP's cannot always be anticipated. An injectable hydroxyapatite cement enables rapid mobilization after a distal radius fracture, but does not give a stable fixation.
Three of the participants in the project have their clinical position at the Hand Surgery Unit in Lund.
Fractures, osteoporosis, and hip fractures in the elderly
Patients with hip fractures constitute one of the most resource consuming groups in health care. They consume 25 percent of all bed days in orthopedic Departments in Sweden. We have pioneered a treatment program with osteosynthesis, immediate direct weight bearing, and continued walking rehabilitation in the patients own home. During the last twenty years the incidence of hip fracture has doubled in persons above 80 years of age and the total number of elderly in the population increases. We must therefore continue the improvement in operation techniques and rehabilitation of the hip fracture patients.
The research project contains epidemiological, prognostic, operative, technical
as well as rehabilitation and economical aspects on the hip fracture treatment.
It also includes a nationwide study of parameters for quality assurance. Projects:
(1) Fracture epidemiology, background factors, screening and prevention.
(2) Comparison of operation methods for multifragment trochanteric fractures.
(3) Investigation of femoral head vitality after femoral neck fracture.
(4) Hip joint tamponade after trauma. (5) Traction: Importance for
early reposition of cervical hip fracture. (6) Bone transplantation. (7)
Osteonecrosis. (8) Nationwide, multicenter registration of quality in treatment
of patients with hip fractures. Techniques: epidemiology, balance testing, patient
inquiries, skeletal scintimetry, tetracycline marking, bone biopsy, histology, MRI,
CT, X-ray, ultrasound, pressure measurement.
Lumbar pain and sciatica - diagnostics, RSA, treatment and long-term outcome
Surgical treatment of lumbar spine disorders based on improved resolution in neuroimaging techniques is studied in a large prospective and consecutive study. Pre- and postoperative patient related parameters are recorded and the outcome is determined two years postoperatively. This database is continually expanding, and a protocol for national registration of lumbar spine surgery has been composed and is supported by the National Board of Health and Welfare. Preliminary results, so far presented in more than 40 scientific papers, define suitable types of diagnostic procedures and results after different types of spinal surgery. Outcome of decompressive surgery for lateral stenosis, lumbar spine surgery in the elderly, and various stabilizing procedures have been reported and clinical pictures have been scrutinized and prognostic factors for surgery identified. A 5-year follow-up of operated central spinal stenosis, carried out by an independent observer, has recently been concluded.
The study constitutes the basis for a treatment algorithm, enabling optimization of (1) method and technique of operation, (2) postoperative treatment, (3) patient information on treatment and long-term results, and (4) utilization of hospital resources.
The analysis of motion and bone healing in the spine after surgery by roentgen stereophotogrammetric analysis (RSA) forms an important aspect of this project. With this technique, normal healing after uninstrumented posterolateral lumbar spine fusion has been determined to occur between 6 and 12 months postoperatively. Further, the significance of different types of postoperative orthoses has been explored. A 5-month treatment regimen yields better results than a 3-month period. The type of orthosis used, soft, stiff, or with hip immobilization, seems to be of minor significance and the effect of the orthosis probably is exerted by minimizing gross body motions instead of intervertebral mobility at the level of fusion. The healing after instrumented posterolateral fusion occurs more rapidly and frequently than without instruments. A concept for comparing the in vivo behavior of different types of spinal implants has been developed. Fixation with biodegradable rods enhances the fusion rate of the lumbosacral level. The external fixation test according to Magerl is a valid prognostic instrument from the biomechanical point of view as demonstrated by RSA. Lumbar spine mobility after decompressive surgery, mobility after operation for thoracolumbar fracture, and comparative studies of different implants in the lumbar spine are currently examined by RSA technique in separate studies. One study evaluates in a prospective randomized fashion by means of RSA the effect of bone morphogenetic protein (BMP) on fusion healing in humans for the first time.
RSA analysis in degenerative disorders of the lumbar spine will increase our understanding of intervertebral mobility in normal and pathological conditions.
The effects on function and ADL activities of lumbar disc surgery are being explored. Non-invasive techniques for treating lumbar disc herniation are studied experimentally.
Soft tissue sarcomatreatment and prognosis
Soft tissue sarcoma comprises less than one percent of all malignancies. It is a heterogeneous group of tumors; more than 30 different histologic types have been defined. The clinical course varies, some tumors can be controlled by simple surgery, others have a strong propensity both for local recurrence and distant metastases. Prognostic factors are poorly defined.
Treatment: The principal treatment of soft tissue sarcoma is surgical removal of the primary tumor. Amputation has been replaced by limb-sparing surgery, sometimes combined with adjuvant radiotherapy. We evaluate the value of fine-needle aspiration cytology for diagnosis, radiologic criteria for definition of tumor topography, quality of surgical margins necessary for a low local recurrence risk, and the indications for adjuvant radio- and chemotherapy.
Prognosis: Tumors are classified by light microscopy, electron microscopy, immunohistochemistry, DNA-ploidy, proliferation factors determination, chromosomal analysis, and molecular genetics. The findings from these investigations are correlated with conventional histologic classification and clinical outcome.
Several of the projects are in cooperation with the Scandinavian Sarcoma Group, the European Musculoskeletal Oncology Group and the Chromosomes and Morphology Study Group.
Ligament injuries in distal radius fractures in young patients
Fractures of the distal radius are frequent in elderly, osteoporotic patients and have been relatively well studied. In younger patients, higher energy trauma is often involved and concomitant ligament injuries could be expected. The incidence and severity of these injuries are largely unknown.
In an epidemiological study, distal radius fractures in young patients will be analyzed, e.g., regarding fracture types and mechanisms of injury. Patients who sustained a fracture 1-2 years ago, will be examined for carpal ligament injuries using arthrography and arthroscopy. The relationship between ligament injuries and subjective complaints will be studied.
In a prospective study, all younger patients with dislocated distal radius fractures will be offered arthroscopic examination of the wrist in order to detect and classify concomitant injuries of the carpal ligaments. Ligament injuries of different degrees have been found in almost all of the more than 30 patients already examined. After a one year follow-up of these patients, we hope to be able to detect which types of ligament injuries that are likely to give permanent complaints. Different methods of treatment of these ligament injuries will be studied in prospective, randomized studies.
Prevention of disabling joint contractures and hip dislocation in children with cerebral palsy by systematic follow-up and early initiated measures
There is a substantial risk of increasing contractures of hip, knee and foot in cerebral palsy. The untreated hip joint will often end up with dislocation. Apart from threatening dislocation and impaired walking ability, hip contracture also leads to sitting difficulties, hygienic inconveniences as well as increased tendency of decubitus. An established dislocation is often painful with developing arthrosis even in late teenage. If ominous signs are observed early enough deterioration can be prevented by rather simple measures (orthoses, intensified physiotherapy, tendon elongation etc.) and dislocation can likely be prevented. Today uniform follow-up as well as firm rules for preventive treatment and follow-up of these children are lacking. There is neither international consensus concerning prevention of late complication by means of early taken measures; it is probably unique for Sweden to manage a follow-up program of several years' duration.
A health-care program is designed with standardized assessment, treatment and follow-up of all spastic diplegic and tetraplegic children in southern Sweden. A central group (pediatric orthopedic surgeon, habilitation neurologist, physiotherapist, orthopedic technician, radiologist, secretary) has been established responsible for realization of the project.
Continuous directed controls are executed by the child's individual physiotherapist. When necessary this is supplemented with radiological examination or video based gait analysis as well as early taken measures according to defined criteria of treatment.
The purpose of the project is to:
- reduce the number of serious joint contracture and hip dislocation
- reduce the need for major late orthopedic operations in children
- reduce the requirement for more complicated sitting devices Continuous databased documentation facilitates comparison with other treatment procedures and outlines optimized way of treatment.
Pathophysiology, blood supply, synovitis and cartilage
Reaction of the femoral head and growth in Legg-Calv?Perthes? disease
The etiology in LCPD is a disturbed blood supply to the proximal femoral epiphysis resulting in an aseptic necrosis. The cause of this disturbance is unknown but scintimetric studies indicate that synovitis with effusion in the hip joint and subsequently increased intracapsular pressure is important. We have measured the intracapsular pressure in LCPD and have found pressures that could compromise the blood supply to the proximal femoral epiphysis.
A sonographic technique was developed to diagnose and follow the synovitis with ensuing effusion. It was correlated to the corresponding findings on CT. Sonography proved a very sensitive diagnostic tool in various forms of synovitis and subsequent intracapsular effusion.
Synovitis causes cartilage edema and ensuing cartilage hypertrophy with a risk of joint deformation, incongruency and poor containment. Serial MRI and plain radiography was used to follow the development of the femoral head. In cases of incongruency we have performed a proximal femoral varus derotation osteotomy. A recent follow up study indicates that this results in a reduced cartilage incongruency and an improved sphericity of the femoral head. The advantage with MRI in these cases is the possibility to monitor the cartilage contour development of the head of femur as well as the epiphyseal necrosis and synovitis. The cartilage reacts earlier and more rapid on MRI than the bony contour as visualized on plain radiographs.
Migration, loosening, and wear following total hip joint arthroplasty
Hans Wingstrand and Rolf ?nerf?t
Roentgenstereophotogrammetry (RSA) has developed into the most exact instrument to study micromotion in the locomotor system and is used in the development of joint arthroplasties in the knee, hip and shoulder joints as well as in fracture surgery, rheuma surgery, plastic surgery and in stereotactic surgery. The prerequisite in RSA is however the peroperative implantation of 0,8 mm tantalum ball indicators in the skeleton. Thus the method can be used only in limited prospective studies.
The purpose of this project is to evaluate and further develop a promising non-invasive method, "Einbild R?tgen Analyse" (EBRA) originally developed at the Orthopaedic Department, University of Innsbruck.
By developing EBRA into a clinically useful and cost/efficient method for the study of acetabular cup migration and loosening, a non-invasive method with acceptable precision for larger retrospective as well as prospective studies on hip joint endoprosthesis loosening is now available. Four non-invasive methods; EBRA, Sulzer, Wetherell and Sutherland were compared with RSA; EBRA proved to be the only non-invasive method with acceptable precision. EBRA was used to study cup wear, migration and cup deformation in total hip artrhoplasties.
In another project, the biomechanics of the hip joint capsule and its influence on clinical symptoms, radiological findings and subsequent loosening is studied.
Another study concerns the effect of cement particles on surface structure and wear in the polyethylene cup.
The long term results on a 10-year follow up of the ScanHip arthroplasty concerning revision rate and clnical and radiographic data are studied.
Biomechanics unit
Inaugurated in May, 1997, the biomechanics laboratory combines Ph.D.-students from both the technical and medical faculties, involved in an array of different research programs. The unit is constituted by 1) an Instron laboratory, 2) an RSA-laboratory and office space for about a dozen researchers / engineers. The Swedish Knee Arthroplasty project is also located in these localities. Additionally, a 20-person training facility (work shop) for surgical interventions forms a part of the unit. The training facility is supplied with tools and power machines for operations on bone such as insertion of prostheses, fixation of fractures, arthroscopy phantoms, etc. The unit is connected to the orthopedic operating theaters by a video-loop and two-way communication and has comprehensive AV-equipment. In immediate geographical proximity to the biomechanics unit is the Orthopedic Technical Center for prosthetics and orthotics situated. Here a comprehensive system for gait analysis -VICON - is installed, which represents a powerful addition to the unit's ability to analyze functional biomechanics in vivo.
- The Instron laboratory is built around an Instron 8511, 15kN tension / torsion testing machine supplied with the MAX software for data retrieval and wave-form generation. The room is lead shielded for simultaneous RSA investigations. Presently the Instron is being used in connection with research programs on endoprosthetic fixation, bone cement, ligament and fracture fixation etc.
- Roentgen stereophotogrammetric analysis (RSA) was developed in Lund by the late G?an Selvik. The method involves perioperative marking of objects of interest such as endoprostheses, fracture fragments, ligament insertions. Subsequent radiographs of the patient and a calibration object are digitized using precision hard-ware (precision < 10?m) and 2-D coordinates are processed to arrive at a comprehensive description of motion using Euler rigid body kinematics. The accuracy of RSA has been determined to about one order of magnitude better than conventional radiography. The laboratory is equipped with two complete RSA units using both UmRSA (Unicum, Ume? and WinRSA (Tilly Medical, Lund) software. Presently, radiography in Sweden is rapidly converting to digital technology and PACS for data storage. Consequently the unit is involved in converting to handling digital image data and automation of the digitizing process. The methods is extensively used in a number of application in the department of Orthopedics, see further this report e.g. endoprosthetic fixation, lumbar pain and sciatica and optimized biomaterials for tissue reconstruction.
- Work-station Silicon Graphics equipped with FEM soft ware (Marc) offers the possibility for analytical work using FEM-models. Presently used to model implants in the hip and the knee to study interface behavior, fluid flow etc. Also used to model animal implants for validation purposes.
Department
of Orthopaedics, Lund University Hospital, 221 85 Lund, Sweden
