Showing papers in "Clinical Orthopaedics and Related Research in 1998"
TL;DR: Using a reproducible model of experimental fracture healing in the rat, the integrated cellular responses that signal the pathways and the role of the extracellular matrix components in orchestrating the events of fracture healing are elucidated.
Abstract: Fracture healing is a complex physiologic process that involves the coordinated participation of several cell types. By using a reproducible model of experimental fracture healing in the rat, it is possible to elucidate the integrated cellular responses that signal the pathways and the role of the extracellular matrix components in orchestrating the events of fracture healing. Histologic characterization of fracture healing shows that intramembranous ossification occurs under the periosteum within a few days after an injury. Events of endochondral ossification occur adjacent to the fracture site and span a period of up to 28 days. Remodeling of the woven bone formed by intramembranous and endochondral ossification proceeds for several weeks. Spatial and temporal expression of genes for major collagens (Types I and II), minor fibrillar collagens (Types IV and XI), and several extracellular matrix components (osteocalcin, osteonectin, osteopontin, fibronectin and CD44) are detected by in situ hybridization. Immunohistochemical studies show that expression of proliferating cell nuclear antigen is both time and space dependent and differentially expressed in the callus tissues formed by the intramembranous and endochondral processes. Chondrocytes involved in endochondral ossification undergo apoptosis (programmed cell death), and early events in fracture healing may be initiated by the expression of early response genes such as c-fos. Additional characterization and elucidation of fracture healing will lay the foundation for subsequent studies aimed at identifying mechanisms for enhancing skeletal repair.
1,234 citations
TL;DR: In this article, the epicondylar axis and tibial tubercle were used as references on computed tomography scans to measure quantitatively rotational alignment of the femoral and Tibial components.
Abstract: Thirty patients with isolated patellofemoral complications after total knee arthroplasty were compared with 20 patients with well functioning total knee replacements without patellofemoral complications. The epicondylar axis and tibial tubercle were used as references on computed tomography scans to measure quantitatively rotational alignment of the femoral and tibial components. The group with patellofemoral complications had excessive combined (tibial plus femoral) internal component rotation. This excessive combined internal rotation was directly proportional to the severity of the patellofemoral complication. Small amounts of combined internal rotation (1°-4°) correlated with lateral tracking and patellar tilting. Moderate combined internal rotation (3°-8°) correlated with patellar subluxation. Large amounts of combined internal rotational (7°-17°) correlated with early patellar dislocation or late patellar prosthesis failure. The control group was in combined external rotation (10°-0°). The direct correlation of combined (femoral and tibial) internal component rotation to the severity of the patellofemoral complication suggests that internal component rotation may be the predominant cause of patellofemoral complications in patients with normal axial alignment. The epicondylar axis and tibial tubercle are reproducible landmarks which are visible on computed tomography scans and can be used intraoperatively. Using this computed tomography study can determine whether rotational malalignment is present and thus, whether revision of one or both components may be indicated.
975 citations
TL;DR: Finite element models are used to show that the patterns of tissue differentiation observed in fracture healing and distraction osteogenesis can be predicted from fundamental mechanobiologic concepts.
Abstract: Skeletal regeneration is accomplished by a cascade of biologic processes that may include differentiation of pluripotential tissue, endochondral ossification, and bone remodeling. It has been shown that all these processes are influenced strongly by the local tissue mechanical loading history. This article reviews some of the mechanobiologic principles that are thought to guide the differentiation of mesenchymal tissue into bone, cartilage, or fibrous tissue during the initial phase of regeneration. Cyclic motion and the associated shear stresses cause cell proliferation and the production of a large callus in the early phases of fracture healing. For intermittently imposed loading in the regenerating tissue: (1) direct intramembranous bone formation is permitted in areas of low stress and strain; (2) low to moderate magnitudes of tensile strain and hydrostatic tensile stress may stimulate intramembranous ossification; (3) poor vascularity can promote chondrogenesis in an otherwise osteogenic environment; (4) hydrostatic compressive stress is a stimulus for chondrogenesis; (5) high tensile strain is a stimulus for the net production of fibrous tissue; and (6) tensile strain with a superimposed hydrostatic compressive stress will stimulate the development of fibrocartilage. Finite element models are used to show that the patterns of tissue differentiation observed in fracture healing and distraction osteogenesis can be predicted from these fundamental mechanobiologic concepts. In areas of cartilage formation, subsequent endochondral ossification normally will proceed, but it can be inhibited by intermittent hydrostatic compressive stress and accelerated by octahedral shear stress (or strain). Later, bone remodeling at these sites can be expected to follow the same mechanobiologic adaptation rules as normal bone.
718 citations
TL;DR: It is hypothesized that gap size and the amount of strain and hydrostatic pressure along the calcified surface in the fracture gap are the fundamental mechanical factors involved in bone healing.
Abstract: An interdisciplinary study based on animal experiments, cell culture studies, and finite element models is presented In a sheep model, the influence of the osteotomy gap size and interfragmentary motion on the healing success was investigated Increasing gap sizes delayed the healing process Increasing movement stimulated callus formation but not tissue quality Typical distributions of intramembranous bone, endochondral ossification, and connective tissue in the fracture gap are quantified The comparison of the mechanical data determined by a finite element model with the histologic images allowed the attribution of certain mechanical conditions to the type of tissue differentiation Intramembranous bone formation was found for strains smaller than approximately 5% and small hydrostatic pressure ( 4%) turned away from the principal strain axis and avoided larger deformations It is hypothesized that gap size and the amount of strain and hydrostatic pressure along the calcified surface in the fracture gap are the fundamental mechanical factors involved in bone healing
642 citations
TL;DR: The bone morphogenetic proteins are secreted signalling molecules that belong to the transforming growth factor beta family of growth and differentiation factors that are prominent at many sites during embryogenesis and likely to be key regulators of early development and organogenesis.
Abstract: The bone morphogenetic proteins are secreted signalling molecules that belong to the transforming growth factor beta family of growth and differentiation factors. Individual bone morphogenetic proteins are prominent at many sites during embryogenesis and are likely to be key regulators of early development and organogenesis. In vertebrates, one of the functions of bone morphogenetic like proteins is to induce formation of bone, cartilage, and connective tissues associated with the skeleton. This osteoinductive ability has led to the use of bone morphogenetic proteins as therapeutic agents for creation of new bone useful in treatment of skeletal injuries and diseases, and in oral and maxillofacial applications.
632 citations
TL;DR: The traditional understanding of knee kinematics holds that no single fixed axis of rotation exists in the knee, but this hypothesis has been tested and the optimal flexion axis is fixed in the femur and can be considered the trueflexion axis of the knee.
Abstract: The traditional understanding of knee kinematics holds that no single fixed axis of rotation exists in the knee. In contrast, a recent hypothesis suggests that knee kinematics are better described simply as two simultaneous rotations occurring about fixed axes. Knee flexion and extension occurs about an optimal flexion axis fixed in the femur, whereas tibial internal and external rotations occur about a longitudinal rotation axis fixed in the tibia. No other translations or rotations exist. This hypothesis has been tested. Tibiofemoral kinematics were measured for 15 cadaveric knees undergoing a realistic loadbearing activity (simulated squatting). An optimization technique was used to identify the locations of the optimal flexion and longitudinal rotation axes such that simultaneous rotations about them could best represent the measured kinematics. The optimal flexion axis was compared with the transepicondylar axis defined by bony landmarks. The longitudinal rotation axis was found to pass through the medial joint compartment. The optimal flexion axis passed through the centers of the posterior femoral condyles. No significant difference was found between the optimal flexion and transepicondylar axes. To an average accuracy of better than 3.4 mm in translation, and 2.9 degrees in orientation, knee kinematics were represented successfully by simple rotations about the optimal flexion and longitudinal rotation axes. The optimal flexion axis is fixed in the femur and can be considered the true flexion axis of the knee. The transepicondylar axis axis, which is identified easily by palpation, closely approximates the optimal flexion axis.
502 citations
TL;DR: The medial patellofemoral ligament was found to be the major medial ligamentous stabilizer of the patella and the patelotibial and patellomeniscal ligament complex played an important secondary role in restraining lateral patellar displacement.
Abstract: This study was undertaken to evaluate the medial ligamentous stabilizers of the patella in restraining lateral displacement and to assess their relative contribution after individual repair. Seventeen fresh frozen human anatomic specimen knee joints were studied. The specimens were loaded onto a testing instrument that was designed to measure the compliance of the medial and lateral patellar restraints in the coronal plane. Two different cutting and repair sequences were used to test the individual contributions of the patellar ligaments. The medial patellofemoral ligament was found to be the major medial ligamentous stabilizer of the patella. Isolated release resulted in a 50% increase in lateral displacement, and isolated repair restored balance to the patella. In addition, the patellotibial and patellomeniscal ligament complex played an important secondary role in restraining lateral patellar displacement. Isolated repair of these ligaments restored balance to near normal levels. The medial patellofemoral retinaculum played only a minor role in patellofemoral instability. Proximal realignment or medial ligament repair for patellofemoral instability specifically should address repair of the deep layers that contain the restraints to lateral patellar displacement. Failure to include these structures in repair, especially of the medial patellofemoral ligament, may lead to persistent or recurrent instability.
495 citations
TL;DR: Data from this multicenter study are remarkably similar to previous fluoroscopy data from a single surgeon series, showing a lack of customary posterior femoral rollback in both posterior cruciate retaining designs and conversely showing an average anterior femoral translation with knee flexion.
Abstract: A study was conducted to determine in vivo femorotibial contact patterns for subjects having a posterior cruciate retaining or posterior cruciate substituting total knee arthroplasty. Femorotibial contact of 72 subjects implanted with a total knee replacement, performed by five surgeons, was analyzed using video fluoroscopy. Thirty-one subjects were implanted with a posterior cruciate retaining total knee replacement with a flat polyethylene posterior lipped insert, 12 with a posterior cruciate retaining total knee replacement with a curved insert, and 29 with a posterior cruciate substituting total knee replacement. Each subject performed successive deep knee bends to maximum flexion. Video images at 0 degree, 30 degrees, 60 degrees, and 90 degrees flexion were downloaded onto a workstation computer. Femorotibial contact paths were determined for the medial and lateral condyles using an interactive model fitting technique. Femorotibial contact anterior to the tibial midline in the sagittal plane was denoted as positive and contact posterior was denoted as negative. Analysis of average femorotibial contact pathways of both posterior cruciate retaining designs revealed posterior femorotibial contact in full extension with anterior translation of femorotibial contact commonly observed in midflexion and terminal flexion. In posterior cruciate substituting designs, anterior femoral translation was seen medially at 30 degrees to 60 degrees flexion but rarely was observed laterally. Posterior femoral rollback laterally from full extension to 90 degrees flexion was seen in 100% of subjects implanted with a posterior cruciate substituting total knee replacement, versus 51.6% (posterior lipped polyethylene insert) and 58.3% (curved insert) of those with a posterior cruciate retaining total knee replacement. Data from this multicenter study are remarkably similar to previous fluoroscopy data from a single surgeon series, showing a lack of customary posterior femoral rollback in both posterior cruciate retaining designs, and conversely showing an average anterior femoral translation with knee flexion. Posterior femoral rollback, less than in normal knees, routinely was observed in posterior cruciate substituting total knee arthroplasty, attributed to engagement of the femoral component cam with the tibial post. The abnormal anterior femoral translation observed in posterior cruciate retaining total knee arthroplasty may be a factor in premature polyethylene wear observed in retrieval studies.
453 citations
TL;DR: The authors have completed an array of preclinical studies showing the feasibility and efficacy of MSC based implants to heal large osseous defects, and suggest that by combining MSCs with an appropriate delivery vehicle, it may be possible to offer patients new therapeutic options.
Abstract: Bone marrow contains a population of rare progenitor cells capable of differentiating into bone, cartilage, muscle, tendon, and other connective tissues. These cells, referred to as MSCs, can be purified and culture expanded from animals and humans. This review summarizes recent experimentation focused on characterizing the cellular aspects of osteogenic differentiation, and exploration of the potential for using autologous stem cell therapy to augment bone repair and regeneration. The authors have completed an array of preclinical studies showing the feasibility and efficacy of MSC based implants to heal large osseous defects. After confirming that syngeneic rat MSCs could heal a critical size segmental defect in the femur, it was established that human MSCs form bone of considerable mechanical integrity when implanted in an osseous defect in an immunocompromised animal. Furthermore, bone repair studies in dogs verify that the technology is transferable to large animals, and that the application of this technology to patients at geographically remote sites is feasible. These studies suggest that by combining MSCs with an appropriate delivery vehicle, it may be possible to offer patients new therapeutic options.
449 citations
TL;DR: The ROBODOC® system is thought to be safe and effective in producing radiographically superior implant fit and positioning while eliminating femoral fractures.
Abstract: The ROBODOC system was designed to address potential human errors in performing cementless total hip replacement. The system consists of a preoperative planning computer workstation (called ORTHODOC) and a five-axis robotic arm with a high speed milling device as an end effector. The combined experience of the United States Food and Drug Administration multicenter trial and the German postmarket use of the system are reported. The United States study is controlled and randomized with 136 hip replacements performed at three centers (65 ROBODOC and 62 control). Followup was 1 year on 127 hip replacements and 2 years on 93 hip replacements. No differences were found in the Harris hip scores or the Short Form Health Survey outcomes questionnaire. Length of stay also was not different, but the surgical time and blood loss were greater in the ROBODOC group. This was attributed to a learning curve at each center. Radiographs were evaluated by an independent bone radiologist and showed statistically better fit and positioning of the femoral component in the ROBODOC group. Complications were not different, except for three cases of intraoperative femoral fracture in the control group and none in the ROBODOC group. The German study reports on 858 patients, 42 with bilateral hip replacements and this includes 30 revision cases for a total of 900 hip replacements. The Harris hip score rose from 43.7 to 91.5. In these cases the surgical time declined quickly from 240 minutes for the first case to 90 minutes. No intraoperative femoral fractures occurred in 900 cases. Other complications were comparable with total hip replacements performed using conventional techniques. The ROBODOC system is thought to be safe and effective in producing radiographically superior implant fit and positioning while eliminating femoral fractures.
429 citations
TL;DR: The rationale for the development of computer assisted knee replacement systems is presented, the operation of several different systems is described, the advantages and disadvantages of different approaches are discussed, and areas for future research are suggested.
Abstract: Accurate alignment of knee implants is essential for the success of total knee replacement. Although mechanical alignment guides have been designed to improve alignment accuracy, there are several fundamental limitations of this technology that will inhibit additional improvements. Various computer assisted techniques have been developed to examine the potential to install knee implants more accurately and consistently than can be done with mechanical guides. For example, computer integrated instrumentation incorporates highly accurate measurement devices to locate joint centers, track surgical tools, and align prosthetic components. Image guided knee replacement provides a three-dimensional preoperative plan that guides the placement of the cutting blocks and prosthetic components. Robot assisted knee replacement allows one to machine bones accurately without the use of standard cutting blocks. The rationale for the development of computer assisted knee replacement systems is presented, the operation of several different systems is described, the advantages and disadvantages of different approaches are discussed, and areas for future research are suggested.
TL;DR: These tools successfully were introduced into the clinical practice of surgery and showed the following: There exist unpredictable and large variations in the initial position of patients' pelves on the operating room table and significant pelvic movement during surgery and during intraoperative range of motion testing.
Abstract: There has been little clinical research to examine the effects of patient positioning and pelvic motion on the alignment of the acetabular implant during total hip replacement surgery. Until now, no tools were capable of accurately measuring these variables during the actual procedure. As part of a broader program in medical robotics and computer assisted surgery, a clinical system has been developed that includes several enabling technologies. The hip navigation system (HipNav) continuously and precisely measures pelvic location and tracks relative implant alignment intraoperatively. HipNav technology is used to gauge current clinical practice and provide intraoperative feedback to surgeons with the goal of improving the precision and accuracy of acetabular alignment during total hip replacement. This system provides surgeons with a new class of image guided measurement tools and assist devices. These tools successfully were introduced into the clinical practice of surgery with results showing the following: (1) There exist unpredictable and large variations in the initial position of patients' pelves on the operating room table and significant pelvic movement during surgery and during intraoperative range of motion testing; (2) current mechanical acetabular alignment guides do not account for these variations, and result in variable and in the majority of cases unacceptable acetabular alignment; and (3) press fitting oversized acetabular components influences the final cup orientation.
TL;DR: The two senior authors (PMP, RP) independently began using an identical enhanced posterior soft tissue repair after total hip replacement through a posterior approach and found that a dislocation rate was reduced in patients before and after the enhanced closure.
Abstract: The two senior authors (PMP, RP) independently began using an identical enhanced posterior soft tissue repair after total hip replacement through a posterior approach. In the first author's experience, a dislocation rate of 4% in 395 patients before using the enhanced closure was reduced to 0% in 395 patients in whom the enhanced closure was performed. In the second author's experience, 160 total hip replacements had a dislocation rate of 6.2% before the enhanced closure whereas 124 total hip replacements had a dislocation rate of 0.8% after the enhanced closure. These results are highly statistically significant.
TL;DR: In this paper, a desktop computer controlled milling device is used as a three-dimensional printer to mold the shape of small reference areas of the bone surface automatically into the body of the template.
Abstract: Recent developments in computer assisted surgery offer promising solutions for the translation of the high accuracy of the preoperative imaging and planning into precise intraoperative surgery. Broad clinical application is hindered by high costs, additional time during intervention, problems of intraoperative man and machine interaction, and the spatially constrained arrangement of additional equipment within the operating theater. An alternative technique for computerized tomographic image based preoperative three-dimensional planning and precise surgery on bone structures using individual templates has been developed. For the preoperative customization of these mechanical tool guides, a desktop computer controlled milling device is used as a three-dimensional printer to mold the shape of small reference areas of the bone surface automatically into the body of the template. Thus, the planned position and orientation of the tool guide in spatial relation to bone is stored in a structural way and can be reproduced intraoperatively by adjusting the position of the customized contact faces of the template until the location of exact fit to the bone is found. No additional computerized equipment or time is needed during surgery. The feasibility of this approach has been shown in spine, hip, and knee surgery, and it has been applied clinically for pelvic repositioning osteotomies in acetabular dysplasia therapy.
TL;DR: Several experimental models of protracted, impaired, or compromised healing have been developed to evaluate the effects of angiogenic factors in accelerating or enhancing repair of fracture healing.
Abstract: Fracture of bone disrupts its circulation and leads to necrosis and hypoxia of adjacent bone. Under normal circumstances, fractured bone undergoes the orderly regeneration of its component tissues with complete restoration of mechanical properties. Reestablishment of the circulation is an early event in fracture healing. Several experimental models of protracted, impaired, or compromised healing have been developed to evaluate the effects of angiogenic factors in accelerating or enhancing repair.
TL;DR: Among voluntarily participating physicians, knee replacement can be a highly effective medical technology with high levels of patient satisfaction and low rates of complications.
Abstract: A prospective, observational cohort investigation was performed to help understand the impact of knee replacement on patients with knee osteoarthritis in community practice. Of those, 291 patients (330 knees) were eligible and willing to participate. Forty-eight orthopaedic surgeons referred 563 patients from 25 institutions within the state of Indiana. Demographics, patient completed health status, satisfaction, independent radiographic measures, surgeon reported intraoperative factors, hospital discharge factors, and independent physical examinations were recorded. A minimum 2-year followup was obtained in 92% of the patients. At followup, 88% were satisfied, 3% were neutral, and 9% were dissatisfied with the results of their knee surgery. The physical composite score improved from 27.4 +/- 0.4 (range, 13.3-50.3) to 37.7 +/- 0.7 (range, 12.9-61.3) at two years. Maximal improvement in physical composite score was seen in patients who had their surgery performed in institutions that performed greater than 50 knee replacements per year in patients with Medicare insurance; who had a better mental health status at baseline; who had surgery performed on Monday, Friday, or Saturday; who were older; who were treated with a posterior cruciate sparing device; and who had worse preoperative function. A lower likelihood of complications were found with surgeons who performed greater than 20 knee replacements per year; midweek surgeries; in patients with more severe preoperative knee dysfunction; patients with fewer comorbidities; patients with less preoperative stiffness; patients being treated by younger surgeons; and in patients undergoing unilateral knee replacement. Among voluntarily participating physicians, knee replacement can be a highly effective medical technology with high levels of patient satisfaction and low rates of complications.
TL;DR: One hundred thirty-one patients who sustained an intertrochanteric fracture were assigned randomly to treatment with either a sliding hip screw or an intramedullary hip screw and followed up prospectively, finding no differences in the rates of functional recovery between the two fixation groups.
Abstract: One hundred thirty-one patients (135 fractures) who sustained an intertrochanteric fracture were assigned randomly to treatment with either a sliding hip screw or an intramedullary hip screw and followed up prospectively. In patients with unstable intertrochanteric fractures, the intramedullary device was associated with 23% less surgical time and 44% less blood loss; however, use of the intramedullary hip screw in patients who had a stable fracture pattern required 70% greater fluoroscopic time. Intraoperative complications occurred exclusively in patients in the intramedullary hip screw group. There were no differences in the rates of functional recovery between the two fixation groups.
TL;DR: Natural fracture healing was studied in 43 cases of isolated, closed, conservatively treated tibial shaft fracture with serial measurements of bending stiffness and standard radiographs, and the callus index predicted behavior in those fractures that showed no tendency to heal at the 10-week stage.
Abstract: Laboratory and clinical scientists and practicing clinicians need definitions of union, delayed union, and nonunion. Fracture union is a gradual process, so quantitative measures are the most meaningful. However, end point definitions also are useful, but they need empirical validation. The measure that has received the best validation in human fractures is bending stiffness. Quantitative radiologic assessment of healing is difficult because varying patterns of bone bridging can occur, including periosteal, endosteal, and intercortical patterns. Natural fracture healing was studied in 43 cases of isolated, closed, conservatively treated tibial shaft fracture with serial measurements of bending stiffness and standard radiographs. Three healing groups were defined on the basis of stiffness recovery patterns. Four cases showed delayed union, defined as failure to reach a stiffness of 7 N-m per degree by 20 weeks from fracture. The remaining cases had normal union, but at differing rates. Callus index was used as a measure of periosteal new bone formation. Stiffness measurements correlated more strongly than callus index with injury severity and functional outcome at 6 months. However, the callus index predicted behavior in those fractures that showed no tendency to heal at the 10-week stage. That is, absence of periosteal new bone in these cases presaged delayed union. These delayed union cases all eventually healed, still without producing periosteal callus, but other fractures in the series healed very rapidly, also without periosteal callus. The implication is that endosteal healing is capable of very rapid fracture bridging if conditions are right, but it also can occur late, after the periosteal healing response has ceased. These observations suggest a more rational approach to the definition of union, delayed union, and nonunion than that provided by the selection of arbitrary times. For conservatively treated fractures at least, delayed union can be defined as the cessation of the periosteal response before the fracture successfully has been bridged. Nonunion is the cessation of both the periosteal and endosteal healing responses without bridging.
Journal Article•
TL;DR: One hundred thirty-one patients who sustained an intertrochanteric fracture were assigned randomly to treatment with either a sliding hip screw or an intramedullary hip screw and followed up prospectively.
Abstract: One hundred thirty-one patients (135 fractures) who sustained an intertrochanteric fracture were assigned randomly to treatment with either a sliding hip screw or an intramedullary hip screw and followed up prospectively. In patients with unstable intertrochanteric fractures, the intramedullary device was associated with 23% less surgical time and 44% less blood loss; however, use of the intramedullary hip screw in patients who had a stable fracture pattern required 70% greater fluoroscopic time. Intraoperative complications occurred exclusively in patients in the intramedullary hip screw group. There were no differences in the rates of functional recovery between the two fixation groups.
TL;DR: A revision operation that focuses on balancing the flexion and extension spaces, in conjunction with a posterior stabilized knee implant, seems to be a reliable treatment for symptomatic flexion instability after posterior cruciate retaining total knee arthroplasty.
Abstract: Between 1990 and 1995, 25 painful primary posterior cruciate ligament retaining total knee arthroplasties were revised for flexion instability. These patients shared typical clinical presentations that included a sense of instability without frank giving way, recurrent knee joint effusion, soft tissue tenderness involving the pes anserine tendons and the retinacular tissue, posterior instability of 2+ or 3+ with a posterior drawer or a posterior sag sign at 90° flexion, and above average motion of their total knee arthroplasty. The primary total knee arthroplasty was performed for osteoarthritis in 23 patients and rheumatoid arthritis in two patients. There were 13 male and 12 female patients and their mean age was 65 years (range, 35-77 years). Before the revision operation, Knee Society knee scores averaged 45 points (range, 17-68 points) and function scores averaged 42 points (range, 0-60 points). Twenty-two of the knee replacements were revised to posterior stabilized implants and three underwent tibial polyethylene liner exchange only. Nineteen of the 22 knee replacements revised to a posterior stabilized implant were improved markedly after the revision surgery. Only one of three knee replacements that underwent tibial polyethylene exchange was improved. After the revision for flexion instability, Knee Society knee scores averaged 90 points (range, 82-99 points) and function scores averaged 75 points (range, 45-100 points) for the 20 knees with a successful outcome. This study suggests that flexion instability can be a cause of persistent pain and functional impairment after posterior cruciate ligament retaining total knee arthroplasty. A revision operation that focuses on balancing the flexion and extension spaces, in conjunction with a posterior stabilized knee implant, seems to be a reliable treatment for symptomatic flexion instahility after posterior cruciate retaining total knee arthroplasty.
TL;DR: In this study an attempt was made to link the preoperative planning, intraoperative placement, and postoperative measurement of cup placement in total hip replacement using computer assisted techniques.
Abstract: The introduction of image guided systems in total hip replacement surgery provides the ability to plan precisely the alignment of the acetabular cup before surgery, and to perform the surgery according to the preoperative plan. Preoperative planners (interactive computer programs for surgical planning) based on three-dimensional medical images allow planning of optimal placement of implant components based on simulated implant performance. Exact measurement of the cup position during surgery allows precise placement of the cup and accurate measurement of the final position of the cup relative to the pelvis. This measurement is used to evaluate the radiographic techniques for postoperative measurement of cup alignment. Malposition of the acetabular component increases the occurrence of impingement, reduces the safe range of motion, and increases the risk of dislocation and wear. Dislocation of the implant after total hip replacement remains a significant clinical problem. Not fully understanding the interaction between pelvic orientation and final acetabular cup alignment may be one of the main contributing factors in the continued significant incidence of dislocations after total hip replacement. In this study an attempt was made to link the preoperative planning, intraoperative placement, and postoperative measurement of cup placement in total hip replacement using computer assisted techniques.
TL;DR: Results show that a computer assisted technique is much more accurate and safe than manual insertion in treating fractures, spondylolisthesis, or pseudarthrosis and in patients with scoliosis, four screws in four vertebrae had incorrect placement.
Abstract: Clinical evaluation of a computer assisted spine surgical system is presented. Eighty pedicle screws were inserted using computer assisted technology in thoracic and lumbar vertebrae for treatment of different types of disorders including fractures, spondylolisthesis, and scoliosis. Fifty-two patien
TL;DR: There does not seem to be any reason to recommend an operative procedure to a patient with a Rockwood et al Type III injury based on the evidence currently available and Meta-analysis of the four studies including data from surgical and conservative therapy showed no significant benefit from surgery.
Abstract: A literature review was performed to clarify available information which influences decisions whether to advise a young adult patient to undergo surgery for a severely displaced acromioclavicular dislocation. Twenty-four papers were retrieved yielding 1172 patients of whom the mean followup for the 833 surgically treated patients was 43.7 months and not surgically treated was 60.4 months. Of the 24 papers, only five reported surgical and conservative outcomes; two of these papers used prospective randomized methodology and three used nonrandomized methodology. Fourteen papers reported surgical outcome only and five papers reported conservative outcome only. Overall, 88% of surgically treated patients and 87% of nonsurgically treated patients had a satisfactory outcome. Complications most commonly listed were (surgically treated versus nonsurgically treated): need for further surgery (59% versus 6%), infection (6% versus 1%), and deformity (3% versus 37%). Return to activity was no quicker with surgery. Pain was not any more common without surgery. Range of movement was more frequently normal or near normal without surgery (95% versus 86% if surgically treated) and so was strength (92% versus 87%). Meta-analysis of the four studies including data from surgical and conservative therapy showed on significant benefit from surgery. Power studies suggest that to show a statistically significant benefit from surgery, large studies would be required, which, given the relative incidence of these injuries, would probably be multicenter and therefore vulnerable to methodologic difficulties. There does not seem to be any reason to recommend an operative procedure to a patient with a Rockwood et al Type III injury based on the evidence currently available.
TL;DR: The animal and clinical studies that consider the effects of ultrasound on fracture healing, and the in vivo and in vitro work that strives to identify the biologic mechanism(s) responsible for the ultrasound induced enhancement of osteogenesis and fracture healing are reviewed.
Abstract: Fracture healing is a highly complex regenerative process that is essentially a replay of developmental events. These events include the action of many different cell types, a myriad of proteins, and active gene expression that in the majority of cases ultimately will restore the bone's natural integrity. Several biologic and biophysical approaches have been introduced to minimize delayed healing and nonunions, some with promising results. One example of such an approach is low intensity pulsed ultrasound, a noninvasive form of mechanical energy transmitted transcutaneously as high frequency acoustical pressure waves in biologic organisms. Numerous in vivo animal studies and perspective double blind placebo controlled clinical trials have shown that low intensity ultrasound is capable of accelerating and augmenting the healing of fresh fractures. Preliminary evidence suggests efficacy in the treatment of delayed healing and nonunions as well. This article reviews the animal and clinical studies that consider the effects of ultrasound on fracture healing, and the in vivo and in vitro work that strives to identify the biologic mechanism(s) responsible for the ultrasound induced enhancement of osteogenesis and fracture healing.
TL;DR: Patterns of Charcot involvement of the foot and ankle with corresponding methods of treatment and subsequent responses are established and recommendations were derived to assist in selecting appropriate management options.
Abstract: The goal of this study was to characterize Charcot neuroarthropathy of the foot and ankle by specific sites of involvement (ankle, hindfoot, midfoot, and forefoot), modes of presentation, methods of management, and outcome. A summary of treatment and results for 50 ankles, 22 hindfeet, 131 midfeet, and 18 forefeet is presented. Nondisplaced neuropathic ankle fractures typically healed uneventfully with casting and bracing. For displaced ankle fractures, closed reduction and casting generally resulted in loss of reduction and progressive deterioration; better results were obtained with open reduction and internal fixation, using supplemental Kirschner wires and screws. Ankles with Charcot neuroarthropathy and preexisting arthritis typically required arthrodesis. Of the ankles with neuropathic avascular talar necrosis, approximately 1/3 did well with nonoperative intervention and 2/3 required surgery. Chronic, unstable, malaligned Charcot ankles often required arthrodesis. Neuropathic calcaneal fractures were managed successfully nonoperatively. For feet with transverse tarsal joint involvement (Schon Type IV), management was more complex. Nonoperative treatment was successful for less than 1/2. Two thirds of the feet with midtarsus involvement (Schon Types I, II, and III) were managed successfully nonoperatively; 1/3 required surgery for recurrent ulceration, instability, or osteomyelitis. Half of the feet with forefoot neuroarthropathy required surgery for malalignment, ulceration, and/or difficulty with shoewear or braces. This review has established patterns of Charcot involvement of the foot and ankle with corresponding methods of treatment and subsequent responses. From this extensive clinical experience with 221 neuropathic fractures or Charcot joints, recommendations were derived to assist in selecting appropriate management options.
TL;DR: A short term interfragmentary cyclic micromovement applied at a high strain rate induced a greater amount of periosteal callus than the same stimulus applied atA low strain rate, which significantly inhibited the progress of healing.
Abstract: Fracture of the long bones results in a repair process that has the potential to restore the anatomic morphology and mechanical integrity of the bone without scar tissue. The repair process can occur in two patterns. In the first, under conditions of rigid stabilization, direct osteonal remodeling of the fracture line can occur with little or no external callus, a process known as direct bone repair. The second pattern of repair involves bridging of the fragments with external callus and formation of bone in the fracture site by endochondral healing. This type of repair is known as indirect bone healing and occurs under less rigid interfragmentary stabilization. The rate of healing and the extent of callus in this type of repair can be modulated by the mechanical conditions at the fracture site. Applying cyclic interfragmentary micromotion for short periods has been shown to influence the repair process significantly, and characteristics of this stimulus influence the healing response observed. In the current study, a short term interfragmentary cyclic micromovement applied at a high strain rate induced a greater amount of periosteal callus than the same stimulus applied at a low strain rate. This high strain rate stimulus applied later in the healing period significantly inhibited the progress of healing. The beneficial effect of this particular biophysic stimulus early in the healing period may be related to the viscoelastic nature of the differentiating connective tissues in the early endochondral callus. In the early endochondral callus, high rates of movement induce a greater deformation of the fracture fragments because of the stiffening of the callus. Alternatively, the transduction pathway may involve streaming potentials as a result of the high movement rate.
TL;DR: Patients with diabetes who had an index major amputation had a higher mortality, an equal rate of new amputation, and a lower rehabilitation potential than did patients who have an index minor amputation.
Abstract: In this prospective study, mortality, rehabilitation, and new amputations on the same or on the contralateral leg were studied in 189 patients with diabetes who had achieved healing of an index amputation. Ninety-three patients had achieved healing after an index minor (below the ankle) and 96 after an index major (above the ankle) amputation, precipitated by a foot ulcer. The healing time was 29 weeks (range, 3-191 weeks) with a minor amputation and 8 weeks (range, 3-104 weeks) with a primary major amputation. The mortality 1, 3, and 5 years after the index amputation was 15%, 38%, and 68%, respectively, and was higher in patients who had achieved healing after major amputation than in patients achieving healing after minor amputation. The rate of new amputations after 1, 3, and 5 years of observation was 14%, 30%, and 49%, respectively. There was no difference among patients with an index minor and those with an index major amputation. The rate of new major amputations was 9%, 13%, and 23%, respectively, and was higher in patients with an index major amputation. Eighty-five percent of new amputations were precipitated by a foot ulcer. Patients living independently before the index amputation returned to living independently more often after a minor than a major amputation (93% versus 61%). One year after the index amputation, 70% of patients who had achieved healing after having a minor amputation and who could walk 1 km or more before amputation had regained this walking capacity, compared with 19% of patients having a major amputation. Seventy percent of patients with an index transtibial amputation who could walk before amputation were fitted with a prosthesis, and 52% were using it regularly. Patients with diabetes who had an index major amputation had a higher mortality, an equal rate of new amputation, and a lower rehabilitation potential than did patients who had an index minor amputation.
TL;DR: The goals of these new clinically focused technologies are to develop interactive, patient specific preoperative planners to optimize the performance of surgery and the postoperative biologic response, and develop more precise and less invasive interactive smart tools and sensors to assist in the accurate and precise performance of Surgery.
Abstract: Technologies are emerging that will influence the way in which orthopaedic surgery is planned, simulated, and performed. Recent advances in the fields of medical imaging, computer vision, and robotics have provided the enabling technologies to permit computer aided surgery to become an established area which can address clinical needs. Although these technologies have been applied in industry for more than 20 years, the field of computer assisted orthopaedic surgery is still in its infancy. Image guided and surgical navigation systems, robotic assistive devices, and surgical simulators have begun to emerge from the laboratory and hold the potential to improve current surgical practice and patients' outcomes. The goals of these new clinically focused technologies are to develop interactive, patient specific preoperative planners to optimize the performance of surgery and the postoperative biologic response, and develop more precise and less invasive interactive smart tools and sensors to assist in the accurate and precise performance of surgery. The medical community is beginning to see the benefit of these enabling technologies which can be realized only through the collaboration and combined expertise of engineers, roboticists, computer scientists, and surgeons.
Journal Article•
TL;DR: A group of patients at high risk for failure to recover basic activities of daily living function within 1 year of sustaining a hip fracture can be identified.
Abstract: Three hundred thirty-eight community dwelling, ambulatory, elderly patients who sustained a hip fracture were observed prospectively to determine which patient and fracture characteristics at hospital admission predicted functional recovery at 3, 6, and 12 months. Multiple logistic regression was performed to estimate the simultaneous contributions of the predictor variables to failure of functional recovery. Before sustaining a fracture, 16% of patients were dependent on basic activities of daily living and 46% were dependent on instrumental activities of daily living. By 1 year after fracture, 73% of the patients had recovered to their basic activities of daily living status before fracture whereas only 48% had recovered to their instrumental activities of daily living status before fracture. Patients who were age 85 years or older, who lived alone before sustaining a fracture, and who had one or more comorbidities were at increased risk of delay or failure in recovering basic activities of daily living. Only instrumental activities of daily living independence before fracture predicted failure to recover instrumental activities of daily living function by 3 and 6 months after fracture. At 1 year, patient age 85 years or older was the only predictor of failure to recover instrumental activities of daily living function that existed before fracture. Based on characteristics at admission, a group of patients at high risk for failure to recover basic activities of daily living function within 1 year of sustaining a hip fracture can be identified.
TL;DR: In this article, a study of three hundred thirty-eight community dwelling, ambulatory, elderly patients who sustained a hip fracture was observed prospectively to determine which patient and fracture characteristics at hospital admission predicted functional recovery at 3, 6, and 12 months.
Abstract: Three hundred thirty-eight community dwelling, ambulatory, elderly patients who sustained a hip fracture were observed prospectively to determine which patient and fracture characteristics at hospital admission predicted functional recovery at 3, 6, and 12 months. Multiple logistic regression was performed to estimate the simultaneous contributions of the predictor variables to failure of functional recovery. Before sustaining a fracture, 16% of patients were dependent on basic activities of daily living and 46% were dependent on instrumental activities of daily living. By 1 year after fracture, 73% of the patients had recovered to their basic activities of daily living status before fracture whereas only 48% had recovered to their instrumental activities of daily living status before fracture. Patients who were age 85 years or older, who lived alone before sustaining a fracture, and who had one or more comorbidities were at increased risk of delay or failure in recovering basic activities of daily living. Only instrumental activities of daily living independence before fracture predicted failure to recover instrumental activities of daily living function by 3 and 6 months after fracture. At 1 year, patient age 85 years or older was the only predictor of failure to recover instrumental activities of daily living function that existed before fracture. Based on characteristics at admission, a group of patients at high risk for failure to recover basic activities of daily living function within 1 year of sustaining a hip fracture can be identified. Language: en